Archive for the ‘Technology’ Category
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1 Introduction
Ad hoc networks are a new paradigm of wireless communication for mobile hosts (which we call nodes). In an ad hoc network, there is no fixed infrastructure such as base stations or mobile switching centers. Mobile nodes that are within each other’s radio range communicate directly via wireless links, while those that are far apart rely on other nodes to relay messages as routers. Node mobility in an ad hoc network causes frequent changes of the network topology. Military tactical operations are still the main
Application of ad hoc networks today. For example, military units (e.g., soldiers, tanks, or planes), equipped with wireless communication devices, could form an ad hoc network when they roam in a battlefield. Ad hoc networks can also be used for emergency, law enforcement, and rescue missions. Since an ad hoc network can be deployed rapidly with relatively low cost, it becomes an attractive option for commercial uses such as sensor networks or virtual classrooms.
1.1 Security goals
Security is an important issue for ad hoc networks, especially for those security-sensitive applications. To secure an ad hoc network, we consider the following attributes: availability, confidentiality, integrity, authentication, and non-repudiation.
Availability ensures the survivability of network services despite denial of service attacks. A denial of service attack could be launched at any layer of an ad hoc network. On the physical and media access control layers, an adversary could employ jamming to interfere with communication on physical channels. On the network layer, an adversary could disrupt the routing protocol and disconnect the network. On the higher layers, an adversary could bring down high-level services. One such target is the key management service, an essential service for any security framework.
Confidentiality ensures that certain information is never disclosed to unauthorized entities. Network transmission of sensitive information, such as strategic or tactical military information, requires confidentiality. Leakage of such information to enemies could have devastating consequences. Routing information must also remain confidential in certain cases, because the information might be valuable for enemies to identify and to locate their targets in a battlefield.
Integrity guarantees that a message being transferred is never corrupted. A message could be corrupted because of benign failures, such as radio propagation impairment, or because of malicious attacks on the network.
Authentication enables a node to ensure the identity of the peer node it is communicating with. Without authentication, an adversary could masquerade a node, thus gaining unauthorized access to resource and sensitive information and interfering with the operation of other nodes.
Finally, non-repudiation ensures that the origin of a message cannot deny having sent the message. No repudiation is useful for detection and isolation of compromised nodes. When a node A receives an erroneous message from a node B, non-repudiation allows A to accuse B using this message and to convince other nodes that B is compromised.
There are other security goals (e.g., authorization) that are of concern to certain applications, but we will not pursue these issues in this paper.
1.2 Challenges
The salient features of ad hoc networks posses both challenges and opportunities in achieving these security goals.
First, use of wireless links renders an ad hoc network susceptible to link attacks ranging from passive eavesdropping to active impersonation, message replay, and message distortion. Eavesdropping might give an adversary access to secret information, violating confidentiality. Active attacks might allow the adversary to delete messages, to inject erroneous messages, to modify messages, and to impersonate a node, thus violating availability, integrity, authentication, and non-repudiation.
Secondly, nodes, roaming in a hostile environment (e.g., a battlefield) with relatively poor physical protection, have non-negligible probability of being compromised. Therefore, we should not only consider malicious attacks from outside a network, but also take into account the attacks launched from within the network by compromised nodes. Therefore, to achieve high survivability, ad hoc networks should have a 2 distributed architecture with no central entities. Introducing any central entity into our security solution could lead to significant vulnerability; that is, if this centralized entity is compromised, then the entire network is subverted.
Thirdly, an ad hoc network is dynamic because of frequent changes in both its topology and its membership (i.e., nodes frequently join and leave the network). Trust relationship among nodes also changes, for example, when certain nodes are detected as being compromised. Unlike other wireless mobile networks, such as mobile IP [21, 48, 34], nodes in an ad hoc network may dynamically become affiliated with administrative domains. Any security solution with a static configuration would not suffice. It is desirable for our security mechanisms to adapt on-the-fly to these changes.
Finally, an ad hoc network may consist of hundreds or even thousands of nodes. Security mechanisms should be scalable to handle such a large network.
1.3 Routing Protocol and Threats
Routing protocols for ad hoc networks are still under active research. There is no single standard routing protocol. Therefore, we aim to capture the common security threats and to provide guidelines to secure routing protocols. In most routing protocols, routers exchange information on the topology of the network in order to establish routes between nodes. Such information could become a target for malicious adversaries who intend to bring the network down. There are two sources of threats to routing protocols. The first comes from external attackers. By injecting erroneous routing information, replaying old routing information, or distorting routing information, an attacker could successfully partition a network or introduce excessive traffic load into the network by causing retransmission and inefficient routing.
The second and also the more severe kind of threats come from compromised nodes, which might advertise incorrect routing information to other nodes. Detection of such incorrect information is difficult: merely requiring routing information to be signed by each node would not work, because compromised nodes are able to generate valid signatures using their private keys.
To defend against the first kind of threats, nodes can protect routing information in the same way they protect data traffic, i.e., through the use of cryptographic schemes such as digital signature. However, this defense is ineffective against attacks from compromised servers. Worse yet, as we have argued, we cannot neglect the possibility of nodes being compromised in an ad hoc network. Detection of compromised nodes through routing information is also difficult in an ad hoc network because of its dynamically changing topology: when a piece of routing information is found invalid, the information could be generated by a compromised node, or, it could have become invalid as a result of topology changes. It is difficult to distinguish between the two cases.
On the other hand, we can exploit certain properties of ad hoc networks to achieve secure routing. Note that routing protocols for ad hoc networks must handle outdated routing information to accommodate the dynamically changing topology. False routing information generated by compromised nodes could, to some extent, be considered outdated information. As long as there are sufficiently many correct nodes, the routing protocol should be able to find routes that go around these compromised nodes. Such capability of the routing protocols usually relies on the inherent redundancies — multiple, possibly disjoint, routes between nodes — in ad hoc networks.
2. Key Management Service
We employ cryptographic schemes, such as digital signatures, to protect both routing information and data traffic. Use of such schemes usually requires a key management service. We adopt a public key infrastructure because of its superiority in distributing keys and in achieving integrity and non-repudiation. Efficient secret key schemes are used to secure further communication after nodes authenticate each other and establish a shared secret session key. In a public key infrastructure, each node has a public/private key pair. Public keys can be distributed to other nodes, while private keys should be kept confidential to individual nodes. There is a trusted entity called Certification Authority (CA) [11, 47, and 26] for key management. The CA has a public/private key pair, with its public key known to every node, and signs certificates binding public keys to nodes. The trusted CA has to stay on-line to reflect the current bindings, because the bindings could change over time: a public key should be revoked if the owner node is no longer trusted or is out of the network; a node may refresh its key pair periodically to reduce the chance of a successful brute-force attack on its private key. It is problematic to establish a key management service using a single CA in ad hoc networks. The CA, responsible for the security of the entire network, is a vulnerable point of the network: if the CA is unavailable, nodes cannot get the current public keys of other nodes or to establish secure communication with others. If the CA is compromised and leaks its private key to an adversary, the adversary can then sign any erroneous certificate using this private key to impersonate any node or to revoke any certificate.
A standard approach to improve availability of a service is replication. But a naive replication of the CA makes the service more vulnerable: compromise of any single replica, which possesses the service private key, could lead to collapse of the entire system. To solve this problem, we distribute the trust to a set of nodes by letting these nodes share the key management responsibility.
3. Push! Photo: Informal Photo Sharing in Ad-Hoc Networks
As mobile camera phones become ubiquitous the practice of photography changes. Camera phone pictures are usually taken with sharing in mind. Meanwhile, publicly sharing photographs online has become increasingly popular with websites such as Flickr. Push! Photo is a mobile photo sharing application where photos can be made public and immediately accessed by anyone nearby. The application also automatically searches for photos on nearby devices to find interesting and relevant photos. Push! Photo shows how it is possible to share digital photos just as easy as paper photos.
Shoot!
Publicize!
Discover!
Enjoy!
3.1 THE PUSH! PHOTO PROTOTYPE
The current prototype of Push! Photo allows photos to be made public, and users can browse their own photo collection as well as those of others nearby. When devices are in proximity of one another, they will automatically start to search each other’s public photo collections for
Photographs relevant to one self. These photos are shown as a multi-picture slideshow, which is extended as new photos are found. To browse photos from an event shown in a particular photo the user can click on that picture in the slideshow. The application will then download all photos from nearby devices taken at that event. In this way, if a user spots an interesting picture in the slideshow, she can easily find more photos from the same occasion. To decide
Whether two photos are from the same event, information about whom else was around and the time of shooting is used. The application implements a discovery service to find other devices when they are within Wi Fi-range. Thus the application is always aware of who else (using Push!Photo) is around at a particular time. As a photograph is taken, the resulting picture is tagged with this information together with the time and the identity of the photographer. The current prototype is an application running on
Pocket PCs with WiFi-cards and external SD-cameras
3.2 RELATED WORK
In previous work with Push! Music [2] music files were replaced with so called media agents which were enabled to autonomously copy themselves between devices over a wireless ad hoc network. The media agents try to find their
way to potential listeners as users meet, and as a song is copied it automatically enters the play list. In this way the users discover new music while passively listening. Other projects have looked at mobile photo sharing. Davis et al. in MM2 uses the notion of co-presence to simplify the decision of with whom to share [1]. Photos are then uploaded automatically to a central web server where the sharing recipients can access the photos. Kohno and Rekimoto instead use GPS information and time stamps to decide if pictures are from the same event or not [4]. This is used to let users easily browse each others photos when standing in a group to serve as a topic of discussion. The system also let users drag and drop pictures between your own and other’s devices. As a contrast, Push! Photo aims to look into how mobile sharing can be simplified by allowing seamless sharing, and using context and tagging to automatically find interesting and relevant photographs
4 Conclusions
In this paper, we have analyzed the security threats an ad hoc network faces and presented the security objectives that need to be achieved. On one hand, the security-sensitive applications of ad hoc networks require high degree of security; on the other hand, ad hoc networks are inherently vulnerable to security attacks. Therefore, security mechanisms are indispensable for ad hoc networks. The idiosyncrasy of ad hoc networks poses both challenges and opportunities for these mechanisms. This paper focuses on how to secure routing and how to establish a secure key management service in an ad hoc networking environment. These two issues are essential to achieving our security goals. Besides the standard security mechanisms, we take advantage of the redundancies in ad hoc network topology and use diversity coding on multiple routes to tolerate both benign and Byzantine failures. To build a highly available and highly secure key management service, we propose to use threshold cryptography to distribute trust among a set of servers. Furthermore, our key management service employs share refreshing to achieve proactive security and to adapt to changes in the network in a scalable way. Finally, by relaxing the consistency requirement on the servers, our service does not rely on synchrony assumptions. Such assumptions could lead to vulnerability. A prototype of the key management service has been implemented, which shows its feasibility. The paper represents the first step of our research to analyze the security threats, to understand the security requirements for ad hoc networks, and to identify existing techniques, as well as to propose new mechanisms to secure ad hoc networks. More work needs to be done to deploy these security mechanisms in
an ad hoc network and to investigate the impact of these security mechanisms on the network performance.
5 Acknowledgments
I would like to thank my friends for their invaluable contributions to this work. I am also grateful to my family and the anonymous reviewers for their comments and suggestions that helped to improve the quality of the paper.
I am grateful to Almighty for His blessings upon me.
6 References
[1] E. Ayanoglu, C.-L. I, R. D. Gitlin, and J. E. Mazo. Diversity coding for transparent self-healing and
fault-tolerant communication networks. IEEE Transactions on Communications, 41(11):1677–1686,
November 1993.
[2] M. Castro and B. Liskov. Practical Byzantine fault tolerance. In Proceedings of the 3rd USENIX
Symposium on Operating System Design and Implementation (OSDI’99), pages 173–186, New Orleans,
LA USA, February 22–25, 1999. USENIX Association, IEEE TCOS, and ACM SIGOPS.
[3] Y. Desmedt. Threshold cryptography. European Transactions on Telecommunications, 5(4):449–457,
July–August 1994.
[4] Y. Desmedt and Y. Frankel. Threshold cryptosystems. In G. Brassard, editor, Advances in Cryptology—
Crypto’89, the 9th Annual International Cryptology Conference, Santa Barbara, CA USA, August 20–24,
1989, Proceedings, volume 435 of Lecture Notes in Computer Science, pages 307–315. Springer, 1990.
[5] Y. Desmedt and S. Jajodia. Redistributing secret shares to new access structures and its applications.
Technical Report ISSE TR-97-01, George Mason University, July 1997.
[6] A. Ephremides, J. E. Wieselthier, and D. J. Baker. A design concept for reliable mobile radio networks
with frequency hopping signaling. Proceedings of the IEEE, 75(1):56–73, January 1987.
[7] P. Feldman. A practical scheme for non-interactive verifiable secret sharing. In Proceedings of the 28th
Annual Symposium on the Foundations of Computer Science, pages 427–437. IEEE, October 12–14,
1987.
[8] M. J. Fischer, N. A. Lynch, and M. S. Peterson. Impossibility of distributed consensus with one faulty
processor. Journal of the ACM, 32(2):374–382, April 1985.
[9] Y. Frankel, P. Gemmel, P. MacKenzie, and M. Yung. Optimal resilience proactive public-key cryptosystems.
In Proceedings of the 38th Symposium on Foundations of Computer Science, pages 384–393,
Miami Beach, FL USA, October 20–22, 1997. IEEE.
[10] Y. Frankel, P. Gemmell, P. MacKenzie, and M. Yung. Proactive RSA. In B. S. Kaliski Jr., editor,
Advances in Cryptology—Crypto’97, the 17th Annual International Cryptology Conference, Santa Barbara,
CA USA, August 17–21, 1997, Proceedings, volume 1294 of Lecture Notes in Computer Science,
pages 440–454. Springer, 1997.
[11] M. Gasser, A. Goldstein, C. Kaufman, and B. Lampson. The digital distributed systems security architecture.
In Proceedings of the 12th National Computer Security Conference, pages 305–319, Baltimore,
1 Introduction
Ad hoc networks are a new paradigm of wireless communication for mobile hosts (which we call nodes). In an ad hoc network, there is no fixed infrastructure such as base stations or mobile switching centers. Mobile nodes that are within each other’s radio range communicate directly via wireless links, while those that are far apart rely on other nodes to relay messages as routers. Node mobility in an ad hoc network causes frequent changes of the network topology. Military tactical operations are still the main
Application of ad hoc networks today. For example, military units (e.g., soldiers, tanks, or planes), equipped with wireless communication devices, could form an ad hoc network when they roam in a battlefield. Ad hoc networks can also be used for emergency, law enforcement, and rescue missions. Since an ad hoc network can be deployed rapidly with relatively low cost, it becomes an attractive option for commercial uses such as sensor networks or virtual classrooms.
1.1 Security goals
Security is an important issue for ad hoc networks, especially for those security-sensitive applications. To secure an ad hoc network, we consider the following attributes: availability, confidentiality, integrity, authentication, and non-repudiation.
Availability ensures the survivability of network services despite denial of service attacks. A denial of service attack could be launched at any layer of an ad hoc network. On the physical and media access control layers, an adversary could employ jamming to interfere with communication on physical channels. On the network layer, an adversary could disrupt the routing protocol and disconnect the network. On the higher layers, an adversary could bring down high-level services. One such target is the key management service, an essential service for any security framework.
Confidentiality ensures that certain information is never disclosed to unauthorized entities. Network transmission of sensitive information, such as strategic or tactical military information, requires confidentiality. Leakage of such information to enemies could have devastating consequences. Routing information must also remain confidential in certain cases, because the information might be valuable for enemies to identify and to locate their targets in a battlefield.
Integrity guarantees that a message being transferred is never corrupted. A message could be corrupted because of benign failures, such as radio propagation impairment, or because of malicious attacks on the network.
Authentication enables a node to ensure the identity of the peer node it is communicating with. Without authentication, an adversary could masquerade a node, thus gaining unauthorized access to resource and sensitive information and interfering with the operation of other nodes.
Finally, non-repudiation ensures that the origin of a message cannot deny having sent the message. No repudiation is useful for detection and isolation of compromised nodes. When a node A receives an erroneous message from a node B, non-repudiation allows A to accuse B using this message and to convince other nodes that B is compromised.
There are other security goals (e.g., authorization) that are of concern to certain applications, but we will not pursue these issues in this paper.
1.2 Challenges
The salient features of ad hoc networks posses both challenges and opportunities in achieving these security goals.
First, use of wireless links renders an ad hoc network susceptible to link attacks ranging from passive eavesdropping to active impersonation, message replay, and message distortion. Eavesdropping might give an adversary access to secret information, violating confidentiality. Active attacks might allow the adversary to delete messages, to inject erroneous messages, to modify messages, and to impersonate a node, thus violating availability, integrity, authentication, and non-repudiation.
Secondly, nodes, roaming in a hostile environment (e.g., a battlefield) with relatively poor physical protection, have non-negligible probability of being compromised. Therefore, we should not only consider malicious attacks from outside a network, but also take into account the attacks launched from within the network by compromised nodes. Therefore, to achieve high survivability, ad hoc networks should have a 2 distributed architecture with no central entities. Introducing any central entity into our security solution could lead to significant vulnerability; that is, if this centralized entity is compromised, then the entire network is subverted.
Thirdly, an ad hoc network is dynamic because of frequent changes in both its topology and its membership (i.e., nodes frequently join and leave the network). Trust relationship among nodes also changes, for example, when certain nodes are detected as being compromised. Unlike other wireless mobile networks, such as mobile IP [21, 48, 34], nodes in an ad hoc network may dynamically become affiliated with administrative domains. Any security solution with a static configuration would not suffice. It is desirable for our security mechanisms to adapt on-the-fly to these changes.
Finally, an ad hoc network may consist of hundreds or even thousands of nodes. Security mechanisms should be scalable to handle such a large network.
1.3 Routing Protocol and Threats
Routing protocols for ad hoc networks are still under active research. There is no single standard routing protocol. Therefore, we aim to capture the common security threats and to provide guidelines to secure routing protocols. In most routing protocols, routers exchange information on the topology of the network in order to establish routes between nodes. Such information could become a target for malicious adversaries who intend to bring the network down. There are two sources of threats to routing protocols. The first comes from external attackers. By injecting erroneous routing information, replaying old routing information, or distorting routing information, an attacker could successfully partition a network or introduce excessive traffic load into the network by causing retransmission and inefficient routing.
The second and also the more severe kind of threats come from compromised nodes, which might advertise incorrect routing information to other nodes. Detection of such incorrect information is difficult: merely requiring routing information to be signed by each node would not work, because compromised nodes are able to generate valid signatures using their private keys.
To defend against the first kind of threats, nodes can protect routing information in the same way they protect data traffic, i.e., through the use of cryptographic schemes such as digital signature. However, this defense is ineffective against attacks from compromised servers. Worse yet, as we have argued, we cannot neglect the possibility of nodes being compromised in an ad hoc network. Detection of compromised nodes through routing information is also difficult in an ad hoc network because of its dynamically changing topology: when a piece of routing information is found invalid, the information could be generated by a compromised node, or, it could have become invalid as a result of topology changes. It is difficult to distinguish between the two cases.
On the other hand, we can exploit certain properties of ad hoc networks to achieve secure routing. Note that routing protocols for ad hoc networks must handle outdated routing information to accommodate the dynamically changing topology. False routing information generated by compromised nodes could, to some extent, be considered outdated information. As long as there are sufficiently many correct nodes, the routing protocol should be able to find routes that go around these compromised nodes. Such capability of the routing protocols usually relies on the inherent redundancies — multiple, possibly disjoint, routes between nodes — in ad hoc networks.
2. Key Management Service
We employ cryptographic schemes, such as digital signatures, to protect both routing information and data traffic. Use of such schemes usually requires a key management service. We adopt a public key infrastructure because of its superiority in distributing keys and in achieving integrity and non-repudiation. Efficient secret key schemes are used to secure further communication after nodes authenticate each other and establish a shared secret session key. In a public key infrastructure, each node has a public/private key pair. Public keys can be distributed to other nodes, while private keys should be kept confidential to individual nodes. There is a trusted entity called Certification Authority (CA) [11, 47, and 26] for key management. The CA has a public/private key pair, with its public key known to every node, and signs certificates binding public keys to nodes. The trusted CA has to stay on-line to reflect the current bindings, because the bindings could change over time: a public key should be revoked if the owner node is no longer trusted or is out of the network; a node may refresh its key pair periodically to reduce the chance of a successful brute-force attack on its private key. It is problematic to establish a key management service using a single CA in ad hoc networks. The CA, responsible for the security of the entire network, is a vulnerable point of the network: if the CA is unavailable, nodes cannot get the current public keys of other nodes or to establish secure communication with others. If the CA is compromised and leaks its private key to an adversary, the adversary can then sign any erroneous certificate using this private key to impersonate any node or to revoke any certificate.
A standard approach to improve availability of a service is replication. But a naive replication of the CA makes the service more vulnerable: compromise of any single replica, which possesses the service private key, could lead to collapse of the entire system. To solve this problem, we distribute the trust to a set of nodes by letting these nodes share the key management responsibility.
3. Push! Photo: Informal Photo Sharing in Ad-Hoc Networks
As mobile camera phones become ubiquitous the practice of photography changes. Camera phone pictures are usually taken with sharing in mind. Meanwhile, publicly sharing photographs online has become increasingly popular with websites such as Flickr. Push! Photo is a mobile photo sharing application where photos can be made public and immediately accessed by anyone nearby. The application also automatically searches for photos on nearby devices to find interesting and relevant photos. Push! Photo shows how it is possible to share digital photos just as easy as paper photos.
Shoot!
Publicize!
Discover!
Enjoy!
3.1 THE PUSH! PHOTO PROTOTYPE
The current prototype of Push! Photo allows photos to be made public, and users can browse their own photo collection as well as those of others nearby. When devices are in proximity of one another, they will automatically start to search each other’s public photo collections for
Photographs relevant to one self. These photos are shown as a multi-picture slideshow, which is extended as new photos are found. To browse photos from an event shown in a particular photo the user can click on that picture in the slideshow. The application will then download all photos from nearby devices taken at that event. In this way, if a user spots an interesting picture in the slideshow, she can easily find more photos from the same occasion. To decide
Whether two photos are from the same event, information about whom else was around and the time of shooting is used. The application implements a discovery service to find other devices when they are within Wi Fi-range. Thus the application is always aware of who else (using Push!Photo) is around at a particular time. As a photograph is taken, the resulting picture is tagged with this information together with the time and the identity of the photographer. The current prototype is an application running on
Pocket PCs with WiFi-cards and external SD-cameras
3.2 RELATED WORK
In previous work with Push! Music [2] music files were replaced with so called media agents which were enabled to autonomously copy themselves between devices over a wireless ad hoc network. The media agents try to find their
way to potential listeners as users meet, and as a song is copied it automatically enters the play list. In this way the users discover new music while passively listening. Other projects have looked at mobile photo sharing. Davis et al. in MM2 uses the notion of co-presence to simplify the decision of with whom to share [1]. Photos are then uploaded automatically to a central web server where the sharing recipients can access the photos. Kohno and Rekimoto instead use GPS information and time stamps to decide if pictures are from the same event or not [4]. This is used to let users easily browse each others photos when standing in a group to serve as a topic of discussion. The system also let users drag and drop pictures between your own and other’s devices. As a contrast, Push! Photo aims to look into how mobile sharing can be simplified by allowing seamless sharing, and using context and tagging to automatically find interesting and relevant photographs
4 Conclusions
In this paper, we have analyzed the security threats an ad hoc network faces and presented the security objectives that need to be achieved. On one hand, the security-sensitive applications of ad hoc networks require high degree of security; on the other hand, ad hoc networks are inherently vulnerable to security attacks. Therefore, security mechanisms are indispensable for ad hoc networks. The idiosyncrasy of ad hoc networks poses both challenges and opportunities for these mechanisms. This paper focuses on how to secure routing and how to establish a secure key management service in an ad hoc networking environment. These two issues are essential to achieving our security goals. Besides the standard security mechanisms, we take advantage of the redundancies in ad hoc network topology and use diversity coding on multiple routes to tolerate both benign and Byzantine failures. To build a highly available and highly secure key management service, we propose to use threshold cryptography to distribute trust among a set of servers. Furthermore, our key management service employs share refreshing to achieve proactive security and to adapt to changes in the network in a scalable way. Finally, by relaxing the consistency requirement on the servers, our service does not rely on synchrony assumptions. Such assumptions could lead to vulnerability. A prototype of the key management service has been implemented, which shows its feasibility. The paper represents the first step of our research to analyze the security threats, to understand the security requirements for ad hoc networks, and to identify existing techniques, as well as to propose new mechanisms to secure ad hoc networks. More work needs to be done to deploy these security mechanisms in
an ad hoc network and to investigate the impact of these security mechanisms on the network performance.
5 Acknowledgments
I would like to thank my friends for their invaluable contributions to this work. I am also grateful to my family and the anonymous reviewers for their comments and suggestions that helped to improve the quality of the paper.
I am grateful to Almighty for His blessings upon me.
6 References
[1] E. Ayanoglu, C.-L. I, R. D. Gitlin, and J. E. Mazo. Diversity coding for transparent self-healing and
fault-tolerant communication networks. IEEE Transactions on Communications, 41(11):1677–1686,
November 1993.
[2] M. Castro and B. Liskov. Practical Byzantine fault tolerance. In Proceedings of the 3rd USENIX
Symposium on Operating System Design and Implementation (OSDI’99), pages 173–186, New Orleans,
LA USA, February 22–25, 1999. USENIX Association, IEEE TCOS, and ACM SIGOPS.
[3] Y. Desmedt. Threshold cryptography. European Transactions on Telecommunications, 5(4):449–457,
July–August 1994.
[4] Y. Desmedt and Y. Frankel. Threshold cryptosystems. In G. Brassard, editor, Advances in Cryptology—
Crypto’89, the 9th Annual International Cryptology Conference, Santa Barbara, CA USA, August 20–24,
1989, Proceedings, volume 435 of Lecture Notes in Computer Science, pages 307–315. Springer, 1990.
[5] Y. Desmedt and S. Jajodia. Redistributing secret shares to new access structures and its applications.
Technical Report ISSE TR-97-01, George Mason University, July 1997.
[6] A. Ephremides, J. E. Wieselthier, and D. J. Baker. A design concept for reliable mobile radio networks
with frequency hopping signaling. Proceedings of the IEEE, 75(1):56–73, January 1987.
[7] P. Feldman. A practical scheme for non-interactive verifiable secret sharing. In Proceedings of the 28th
Annual Symposium on the Foundations of Computer Science, pages 427–437. IEEE, October 12–14,
1987.
[8] M. J. Fischer, N. A. Lynch, and M. S. Peterson. Impossibility of distributed consensus with one faulty
processor. Journal of the ACM, 32(2):374–382, April 1985.
[9] Y. Frankel, P. Gemmel, P. MacKenzie, and M. Yung. Optimal resilience proactive public-key cryptosystems.
In Proceedings of the 38th Symposium on Foundations of Computer Science, pages 384–393,
Miami Beach, FL USA, October 20–22, 1997. IEEE.
[10] Y. Frankel, P. Gemmell, P. MacKenzie, and M. Yung. Proactive RSA. In B. S. Kaliski Jr., editor,
Advances in Cryptology—Crypto’97, the 17th Annual International Cryptology Conference, Santa Barbara,
CA USA, August 17–21, 1997, Proceedings, volume 1294 of Lecture Notes in Computer Science,
pages 440–454. Springer, 1997.
[11] M. Gasser, A. Goldstein, C. Kaufman, and B. Lampson. The digital distributed systems security architecture.
In Proceedings of the 12th National Computer Security Conference, pages 305–319, Baltimore,
Mark Terry asked:
GE Healthcare and the University of Pittsburgh Medical Center (UPMC) recently announced they were beginning a joint venture in digital pathology. Together, they formed Omnyx, LLC, which would build and market a system for digital pathology. To date, digital pathology is a market that’s only been nibbled at the edges, and is primarily the domain of microscope companies such as Zeiss, Nikon, and Olympus. However, a small number of companies, bolstered by advances in digital image-gathering, are entering what is predicted to become a $2 to $4 billion industry.
Digital Pathology
Simply put, digital pathology is the utilization of digital photography to capture images on microscope slides. In the past (the early 1990s), there were a number of technical problems with digital imaging of anatomic pathology samples. Digital cameras captured the microscope slide images and stored them. However, the resolution of the digital photographs was not competitive with microscope optics and storage space was limited. A massive amount of data storage was required if the images of an entire microscope slide were to be archived. In addition, the task of capturing the entire microscope slide contents was time-consuming and laborious.
Dick Soenksen, CEO of digital pathology company Aperio Technologies, Inc., believes there are four requirements for effective digital pathology systems. They are:
1. Scanning ability.
2. Software to manage digital slides. In digital radiology they are called PACS (picture archiving and communication systems).
3. Information management systems.
4. The ability to perform image analysis on the digital slides.
Aperio Technologies, Inc.
If there is a leader in digital pathology systems–and it’s not clear that there is one–Aperio is probably it. Their headquarters is in Vista, California, with a European office in Bristol, U.K. **** Soenksen, CEO of Aperio, says, “We are focused on digital pathology. That’s the only thing we do and it’s the only thing we’ve ever done. From our perspective, digital pathology is managing the information that’s generated by being able to digitize entire slides.”
One of the more interesting components of Aperio is their Digital Slide Scanning Service. Rather than invest in a system, the pathologist can ship their slides to Aperio and the company will use the ScanScope Scanner to digitize the slides, which are then returned along with a CD or DVD or via Internet access. Although the digital pathology market’s goal is undoubtedly to have all pathologists, labs, and hospitals using their technology in-house, this is a potential way to get pathologists to digitize early.
BioImagene
Cupertino, California-based BioImagene focuses on imaging systems for life sciences and digital pathology solutions. Mohan Uttarwar, President and CEO of BioImagene, says that their core competencies are, “The digitization of microscope slides, bringing in high-resolution image management, searching, mining of imaging data, and image analysis. Finally, the power of the Internet can be used to manage information, whether it’s a clinical report, educational content, peer reviews–formal or informal–or second opinions. All these pieces put together are something we as a company have focused on.”
Uttarwar cites four issues that are slowing adoption.
1. Lack of standardization.
2. Psychology, or resistance on the part of pathologists.
3. Ease of use and high quality.
4. Pricepoint.
Psyche Systems Corporation
Psyche Systems (Milford, MA) is not a digital pathology company per se, but a laboratory information system. They offer a number of different solutions for information management in a variety of laboratory areas, including anatomic pathology. Their AP solution is called the WindoPath Anatomic Pathology Information System, which has a modular, customizable design and can be integrated into several different laboratory information systems.
MIMvista Corporation
Based in Cleveland, Ohio, MIMvista recently made the news–somewhat contrary to Psyche’s comments about PocketPath–because of their development of a pathology imaging system specifically for Apple’s iPhone. MIM stands for Multi-modality Imaging, which has its roots in a digital radiology system dubbed Fusion.
Omnyx
As mentioned earlier, in June 2008, GE Healthcare and the University of Pittsburgh Medical Center entered into a joint agreement to start a digital pathology device company called Omnyx. Omnyx will be headquartered in Pittsburgh and also have a site in Piscataway, NJ, in addition to facilities in Israel and in Albany, New York. As yet, Omnyx does not have an actual product, although they plan to have a prototype device developed by the end of 2008 and expect to launch a product in 2010. Gene Cartwright, CEO of Omnyx says, “We believe it will be a little less than two years before we have a product. I think that we’ll be able to describe it in high level detail by the end of this year, but it’s the sort of product that needs FDA approval and that adds a certain amount of time to it.”
Cartwright believes the reason the field of digital pathology is receiving so much interest at the moment is that some of the technical hurdles are close to being solved. “The main ones are speed of acquisition of an image, quality of the image, ability to navigate around the image without having to wait for the image to come up, and then the ability to stream images. The cost of storage has dropped by 30 to 40 percent a year.”
Educational Use
John Woosley, MD, PhD, Professor of Pathology at the University of North Carolina at Chapel Hill, notes an increased use of digital slides in medical education. He sees it as an opportunity for medical schools to cooperate and share teaching materials, primarily because once a slide has been scanned, it costs nothing to duplicate
Conclusion
As noted, pathology is one of the last areas of clinical medicine to become digitized, following radiology and cardiac imaging. Typically the domain of microscope companies like Nikon, Zeiss and Olympus, a number of small companies have entered the market with new optics technology and digital information management software.
Although a number of companies and researchers have approached digital pathology over the last ten to fifteen years, they were hampered largely by the difficulty of acquiring high-resolution images of the entire microscope at high enough quality to be clinically useful. As digital image capture technology improved along with increased digital storage capacity at lower prices, digital pathology may have reached a tipping point where the technology is available at a reasonable cost.
It’s not clear how large that market may actually be. Omnyx’s Cartwright says, “The assumption is the market will adopt digital pathology at the same rate that digital radiology was adopted. So in several years we believe–and at the price points we’re assuming the market will support–that the market will be worth about $2 billion.”
Aperio’s Soenksen is more optimistic. “We’ve looked at the market and we’ve made a hypothetical full-adoption in the market and say it’s close to $4 billion a year. That’s about twice the size of what GE had in their analysis. We see more value in digital diagnosis that could be applied to automate things that pathologists are currently spending time on.”
GE Healthcare and the University of Pittsburgh Medical Center (UPMC) recently announced they were beginning a joint venture in digital pathology. Together, they formed Omnyx, LLC, which would build and market a system for digital pathology. To date, digital pathology is a market that’s only been nibbled at the edges, and is primarily the domain of microscope companies such as Zeiss, Nikon, and Olympus. However, a small number of companies, bolstered by advances in digital image-gathering, are entering what is predicted to become a $2 to $4 billion industry.
Digital Pathology
Simply put, digital pathology is the utilization of digital photography to capture images on microscope slides. In the past (the early 1990s), there were a number of technical problems with digital imaging of anatomic pathology samples. Digital cameras captured the microscope slide images and stored them. However, the resolution of the digital photographs was not competitive with microscope optics and storage space was limited. A massive amount of data storage was required if the images of an entire microscope slide were to be archived. In addition, the task of capturing the entire microscope slide contents was time-consuming and laborious.
Dick Soenksen, CEO of digital pathology company Aperio Technologies, Inc., believes there are four requirements for effective digital pathology systems. They are:
1. Scanning ability.
2. Software to manage digital slides. In digital radiology they are called PACS (picture archiving and communication systems).
3. Information management systems.
4. The ability to perform image analysis on the digital slides.
Aperio Technologies, Inc.
If there is a leader in digital pathology systems–and it’s not clear that there is one–Aperio is probably it. Their headquarters is in Vista, California, with a European office in Bristol, U.K. **** Soenksen, CEO of Aperio, says, “We are focused on digital pathology. That’s the only thing we do and it’s the only thing we’ve ever done. From our perspective, digital pathology is managing the information that’s generated by being able to digitize entire slides.”
One of the more interesting components of Aperio is their Digital Slide Scanning Service. Rather than invest in a system, the pathologist can ship their slides to Aperio and the company will use the ScanScope Scanner to digitize the slides, which are then returned along with a CD or DVD or via Internet access. Although the digital pathology market’s goal is undoubtedly to have all pathologists, labs, and hospitals using their technology in-house, this is a potential way to get pathologists to digitize early.
BioImagene
Cupertino, California-based BioImagene focuses on imaging systems for life sciences and digital pathology solutions. Mohan Uttarwar, President and CEO of BioImagene, says that their core competencies are, “The digitization of microscope slides, bringing in high-resolution image management, searching, mining of imaging data, and image analysis. Finally, the power of the Internet can be used to manage information, whether it’s a clinical report, educational content, peer reviews–formal or informal–or second opinions. All these pieces put together are something we as a company have focused on.”
Uttarwar cites four issues that are slowing adoption.
1. Lack of standardization.
2. Psychology, or resistance on the part of pathologists.
3. Ease of use and high quality.
4. Pricepoint.
Psyche Systems Corporation
Psyche Systems (Milford, MA) is not a digital pathology company per se, but a laboratory information system. They offer a number of different solutions for information management in a variety of laboratory areas, including anatomic pathology. Their AP solution is called the WindoPath Anatomic Pathology Information System, which has a modular, customizable design and can be integrated into several different laboratory information systems.
MIMvista Corporation
Based in Cleveland, Ohio, MIMvista recently made the news–somewhat contrary to Psyche’s comments about PocketPath–because of their development of a pathology imaging system specifically for Apple’s iPhone. MIM stands for Multi-modality Imaging, which has its roots in a digital radiology system dubbed Fusion.
Omnyx
As mentioned earlier, in June 2008, GE Healthcare and the University of Pittsburgh Medical Center entered into a joint agreement to start a digital pathology device company called Omnyx. Omnyx will be headquartered in Pittsburgh and also have a site in Piscataway, NJ, in addition to facilities in Israel and in Albany, New York. As yet, Omnyx does not have an actual product, although they plan to have a prototype device developed by the end of 2008 and expect to launch a product in 2010. Gene Cartwright, CEO of Omnyx says, “We believe it will be a little less than two years before we have a product. I think that we’ll be able to describe it in high level detail by the end of this year, but it’s the sort of product that needs FDA approval and that adds a certain amount of time to it.”
Cartwright believes the reason the field of digital pathology is receiving so much interest at the moment is that some of the technical hurdles are close to being solved. “The main ones are speed of acquisition of an image, quality of the image, ability to navigate around the image without having to wait for the image to come up, and then the ability to stream images. The cost of storage has dropped by 30 to 40 percent a year.”
Educational Use
John Woosley, MD, PhD, Professor of Pathology at the University of North Carolina at Chapel Hill, notes an increased use of digital slides in medical education. He sees it as an opportunity for medical schools to cooperate and share teaching materials, primarily because once a slide has been scanned, it costs nothing to duplicate
Conclusion
As noted, pathology is one of the last areas of clinical medicine to become digitized, following radiology and cardiac imaging. Typically the domain of microscope companies like Nikon, Zeiss and Olympus, a number of small companies have entered the market with new optics technology and digital information management software.
Although a number of companies and researchers have approached digital pathology over the last ten to fifteen years, they were hampered largely by the difficulty of acquiring high-resolution images of the entire microscope at high enough quality to be clinically useful. As digital image capture technology improved along with increased digital storage capacity at lower prices, digital pathology may have reached a tipping point where the technology is available at a reasonable cost.
It’s not clear how large that market may actually be. Omnyx’s Cartwright says, “The assumption is the market will adopt digital pathology at the same rate that digital radiology was adopted. So in several years we believe–and at the price points we’re assuming the market will support–that the market will be worth about $2 billion.”
Aperio’s Soenksen is more optimistic. “We’ve looked at the market and we’ve made a hypothetical full-adoption in the market and say it’s close to $4 billion a year. That’s about twice the size of what GE had in their analysis. We see more value in digital diagnosis that could be applied to automate things that pathologists are currently spending time on.”
Craig Thornburrow asked:
Photo stamps can be a fun and unique way of sharing your favorite photo with family and friends. You can use photo stamps for just about any occasion and purpose, from letters, postcards, invitations to cards and packages.
Photo stamps come in several different rates from thirty nine cents for first class standard to twenty four cents for postcards and photo stamps. Larger postage rates can be made for packages. Photo stamps cost from about $17.99 for a single sheet of twenty thirty nine cent stamps and many photo stamps sites offer a discount when two or more sheets are purchased at one time.
Many people wonder how the United States Postal Service can tell the difference between a photo stamp and a counterfeit photo stamp. The information based indicia is how the United States Postal Service can tell the difference. The information based indicia is a specially designed two dimensional bar code on the printed photo stamps between the border and photos.
The special designed bar code contains information such as the date of the creation of the photo stamps and the software package serial number. A great deal of research has gone into the information based indicia technology and the end result is that photo stamps are completely reliable and trust worthy.
The size of each photo stamp postage measures 1.9 inches in width and 1.4 inches in height and the actual photo area is 1.1 inches in width and 1.1 inches in height. When creating photo stamps the most important thing is the photo you choose for your stamp so keep in mind the actual size of the final image when choosing your photo. You have two choices when choosing your photo for your photo stamps you can either choose to take the photo with the photo stamp in mind or you can choose a photo that has already been taken.
When taking a photo for your photo stamps the composition of your photo is very important. When setting up the shot for you photo stamp, it is important to choose a setting without a lot of background objects, such as trees and buildings. Next, you want to choose a pose that when shrunk down to the actual photo size of 1.1 inches by 1.1 inches you can still clearly see what or who the photos are of.
When using a person as the object of your photo stamp, it is a good idea to just use a close up of the face. When using multiple people, try for a close up head shot getting all the people included in the photo to lean their heads towards one another. When using an inanimate object for your photo stamp make sure that when shrunk down to the actual image size on the stamp that you can still make out what the object is.
When choosing to use a photo that has already been taken, you want to try to use a editing program to shrink the photo down to 1.1 inches by 1.1 inches to make sure you can still see the photo clearly. When choosing your photo make sure to pick a photo with a clutter free background.
You can choose either a color or black and white photo for you photo stamps, you can also use a custom drawing or design. When choosing a photo for your photo stamps close up shots that was focused and sharp work the best. When using a custom drawing or design the most important thing is to make sure the image will be clear and recognizable when shrunken down.
Photo stamps can be a fun and unique way of sharing your favorite photo with family and friends. You can use photo stamps for just about any occasion and purpose, from letters, postcards, invitations to cards and packages.
Photo stamps come in several different rates from thirty nine cents for first class standard to twenty four cents for postcards and photo stamps. Larger postage rates can be made for packages. Photo stamps cost from about $17.99 for a single sheet of twenty thirty nine cent stamps and many photo stamps sites offer a discount when two or more sheets are purchased at one time.
Many people wonder how the United States Postal Service can tell the difference between a photo stamp and a counterfeit photo stamp. The information based indicia is how the United States Postal Service can tell the difference. The information based indicia is a specially designed two dimensional bar code on the printed photo stamps between the border and photos.
The special designed bar code contains information such as the date of the creation of the photo stamps and the software package serial number. A great deal of research has gone into the information based indicia technology and the end result is that photo stamps are completely reliable and trust worthy.
The size of each photo stamp postage measures 1.9 inches in width and 1.4 inches in height and the actual photo area is 1.1 inches in width and 1.1 inches in height. When creating photo stamps the most important thing is the photo you choose for your stamp so keep in mind the actual size of the final image when choosing your photo. You have two choices when choosing your photo for your photo stamps you can either choose to take the photo with the photo stamp in mind or you can choose a photo that has already been taken.
When taking a photo for your photo stamps the composition of your photo is very important. When setting up the shot for you photo stamp, it is important to choose a setting without a lot of background objects, such as trees and buildings. Next, you want to choose a pose that when shrunk down to the actual photo size of 1.1 inches by 1.1 inches you can still clearly see what or who the photos are of.
When using a person as the object of your photo stamp, it is a good idea to just use a close up of the face. When using multiple people, try for a close up head shot getting all the people included in the photo to lean their heads towards one another. When using an inanimate object for your photo stamp make sure that when shrunk down to the actual image size on the stamp that you can still make out what the object is.
When choosing to use a photo that has already been taken, you want to try to use a editing program to shrink the photo down to 1.1 inches by 1.1 inches to make sure you can still see the photo clearly. When choosing your photo make sure to pick a photo with a clutter free background.
You can choose either a color or black and white photo for you photo stamps, you can also use a custom drawing or design. When choosing a photo for your photo stamps close up shots that was focused and sharp work the best. When using a custom drawing or design the most important thing is to make sure the image will be clear and recognizable when shrunken down.
Ron McNeil asked:
Taking photos can be a lot of fun. It doesn’t matter if you’re taking images of pets, family, sports or scenery, it’s still enjoyable for you. Part of the enjoyment of taking photos is sharing them with others. While before to do this you might have had to send them via snail mail, now all you need to do is go on the computer and use photo gallery software to share them with as many people as you like. It’s a much more convenient way of sharing photos with the people you care about. You’ll learn the basics of photo gallery software in this article.
What is Photo Gallery Software?
So what exactly is photo gallery software? Well, it’s kinda like a digital version of a photo album. If you’ve taken lots of pictures with older cameras (you know, before they were digital), you’ve probably created some photo albums to keep the photos organized. Photo software is just like this, except instead of holding a photo album in your hands, you’ll instead have one on the computer.
A traditional photo gallery software program will allow you to import photos. That is, you’ll be allowed to press a button, select photos from your harddrive, and then put them in your photo by using the software. When you’ve added in all the photos and pressed the button to create the photo gallery, your online photo will be created instantly.
How does Photo Gallery Software Work?
No two photo gallery software programs are alike, but most offer the some of the same features to customers. Usually, when you use the photo software to add images, the program then creates a photo album to house the images. Depending on the software program you are using, during this process, you might be able to choose between different themes for the album. For instance, you might get to customize the gallery’s border, background, text etc.
When the photo album is created, other things are created as well. Thumbnails for the images are also created, which allows people to see a small version of the image and then decide, based on that, whether to click the thumbnail (to see the whole image) or not. This is very handy if you want to have a page for your photos which doesn’t take forever to load. All the HTML coding is also taken care of by the photo gallery software. This is probably a huge relief for those webmasters who can’t be bothered with coding their own photo gallery for their site.
Some photo software programs will allow you to add image captions in when you are adding the images to the program. This allows you to take care of everything within the album while adding the photos in, rather than having to wait until later.
Depending on the photo gallery software program you use, you might also have a great selection of file formats to use. A lot of the best photo software programs will accept many image formats ranging from jpeg and gif to psp. This allows you to upload virtually any type of image format you may have.
Web or Computer?
Not all photo gallery software is the same. Some are focused more on uploading images to the web, while others will only help you to create photo albums for people to browse while using your computer. Usually when you are looking at the information about the program, you’ll be able to tell where the images go. If they are uploaded to a web site, it could be either the photo software maker’s web site, or it could be your own.
Uploading to Your Web Site/Their Web Site
If you’re new to the whole photo gallery thing, it can be difficult to choose the best photo software for your needs. You’re not sure which is the best, and to make this decision, it’s important to think things through. Do you have plans for hosting the photo album on your web site? Do you want the URL (web site address) to be your own? If so, you’re going to want a photo gallery software program that does this for you. Keep in mind that such a program will have to have FTP support, so make sure it does this.
But what if you don’t want to host your own images? While most photo software programs that offer web capabilities are built to work with existing web sites, some offer the ability to upload images to the photo gallery software program’s web site. Your photo along with your photos will be given space on their web site and you’ll be able to pass that link on to others.
Taking photos can be a lot of fun. It doesn’t matter if you’re taking images of pets, family, sports or scenery, it’s still enjoyable for you. Part of the enjoyment of taking photos is sharing them with others. While before to do this you might have had to send them via snail mail, now all you need to do is go on the computer and use photo gallery software to share them with as many people as you like. It’s a much more convenient way of sharing photos with the people you care about. You’ll learn the basics of photo gallery software in this article.
What is Photo Gallery Software?
So what exactly is photo gallery software? Well, it’s kinda like a digital version of a photo album. If you’ve taken lots of pictures with older cameras (you know, before they were digital), you’ve probably created some photo albums to keep the photos organized. Photo software is just like this, except instead of holding a photo album in your hands, you’ll instead have one on the computer.
A traditional photo gallery software program will allow you to import photos. That is, you’ll be allowed to press a button, select photos from your harddrive, and then put them in your photo by using the software. When you’ve added in all the photos and pressed the button to create the photo gallery, your online photo will be created instantly.
How does Photo Gallery Software Work?
No two photo gallery software programs are alike, but most offer the some of the same features to customers. Usually, when you use the photo software to add images, the program then creates a photo album to house the images. Depending on the software program you are using, during this process, you might be able to choose between different themes for the album. For instance, you might get to customize the gallery’s border, background, text etc.
When the photo album is created, other things are created as well. Thumbnails for the images are also created, which allows people to see a small version of the image and then decide, based on that, whether to click the thumbnail (to see the whole image) or not. This is very handy if you want to have a page for your photos which doesn’t take forever to load. All the HTML coding is also taken care of by the photo gallery software. This is probably a huge relief for those webmasters who can’t be bothered with coding their own photo gallery for their site.
Some photo software programs will allow you to add image captions in when you are adding the images to the program. This allows you to take care of everything within the album while adding the photos in, rather than having to wait until later.
Depending on the photo gallery software program you use, you might also have a great selection of file formats to use. A lot of the best photo software programs will accept many image formats ranging from jpeg and gif to psp. This allows you to upload virtually any type of image format you may have.
Web or Computer?
Not all photo gallery software is the same. Some are focused more on uploading images to the web, while others will only help you to create photo albums for people to browse while using your computer. Usually when you are looking at the information about the program, you’ll be able to tell where the images go. If they are uploaded to a web site, it could be either the photo software maker’s web site, or it could be your own.
Uploading to Your Web Site/Their Web Site
If you’re new to the whole photo gallery thing, it can be difficult to choose the best photo software for your needs. You’re not sure which is the best, and to make this decision, it’s important to think things through. Do you have plans for hosting the photo album on your web site? Do you want the URL (web site address) to be your own? If so, you’re going to want a photo gallery software program that does this for you. Keep in mind that such a program will have to have FTP support, so make sure it does this.
But what if you don’t want to host your own images? While most photo software programs that offer web capabilities are built to work with existing web sites, some offer the ability to upload images to the photo gallery software program’s web site. Your photo along with your photos will be given space on their web site and you’ll be able to pass that link on to others.
Suwat Muenpan asked:
In the case of poor quality toner in a laser printer, the black areas won’t be as dense. However, now that good quality, name brand color laser printers are much more affordable, I think it is time for their reconsideration. Enter the color laser printer, which has a relatively low toner cost and does its best quality printing on inexpensive, plain laser paper. In addition, higher quality rag-content bond papers can also be used effectively with a color laser printer. SMEs need an inexpensive laser printer that achieves quality results quickly. If you’re intent on reproducing photos, you’re better off with a good quality inkjet printer instead of a laser.
Since then, laser printers have decreased further in price and increased in quality. A laser printer is a common type of computer printer that reproduces high quality text and graphics on plain paper. Toner Cartridge Depot presents a convenient way to purchase quality office products, laser printer toners, ink cartridges and printer cartridges at competitive prices. Plus, low-end colour lasers often produce colour output quality that rivals that of much more expensive printers. Quality, resolution, and colorThe standard resolution in most laser printers today is 1200 dots per inch (dpi). – Excellent quality: The text is very clear with no dots visible anywhere – exactly what you would expect from a quality laser printer.
When it comes to quantity and quality, I use a Laser printer and if it happens to be a color laser, so be it. Color laser printers are for people who want the speed and text quality of a black-and-white laser but require color, too. However, only the most expensive color laser printers can match the true photo quality of the best photo ink jets.
While colored toner is available, color laser printers are generally much more expensive. 30% of a new product · This product is a recycled version of the used toner cartridge for laser printer. The toner is black in most cartridges, but may be cyan, magenta, and yellow in color laser printers. Inexpensive color laser printers usually ship with a starter set of toner cartridges, which generally hold about a third of a normal cartridge. Last year the answer would have been “go inkjet” because of quirks in laser printer toner technology. Color laser printers add colored toner (typically but not always cyan, yellow, and magenta
see CMYK) in three additional steps or passes. bulk toner will do but must include instructions for my minolta qms 2300 DL laser printer. Click here to save on laser printer toner. Firstly, if I went out and spent this much on a laser printer I wouldn’t expect to be shafted with a ’starter toner pack’. When it comes to laser printers, the main consumable cost you will encounter is toner cartridge replacement. A slightly modified colour laser printer addresses these toner particles to a solid support. Because an entire page is transmitted to a drum before the toner is applied, laser printers are sometimes called page printers. In a write-black printer the laser positively charges the printed areas to attract the toner, which gives better detail than a write-white printer.
Built on an advanced print engine, this 8ppm monochrome laser printer is productive and easy to use. First, laser printer cartridges are able to print thousands of pages and are usually cheaper per page than inkjet cartridges. Dot-matrix printers can print up to 500 cps, and laser printers range from about 4 to 20 text pages per minute. Because laser printers do not use ink, they have less image smearing problems than inkjet printers and are able to print pages faster. The result is a color laser printer that is ready to print as soon as you connect it. Today a comparable laser printer that boasts more memory, a higher print speed and duplexing capability can be had for about $300.00. The fastest color laser printers can print over 60 pages per minute (3600 pages per hour).
The laser printer does not print in color, but my project didn’t require color. If you print a lot, you too may want to consider adding a laser printer to your computer set-up. So whenever I click on the print icon, the document is automatically sent to the laser printer. Most laser printers print only in monochrome. The application being used must support Postscript in order for the laser printer to print Postscript documents. A laser printer with duplex printing can print on one side of the paper, turn the paper over, and print on the other side.
http://www.accessory-computer-store.com/laser-printer/
In the case of poor quality toner in a laser printer, the black areas won’t be as dense. However, now that good quality, name brand color laser printers are much more affordable, I think it is time for their reconsideration. Enter the color laser printer, which has a relatively low toner cost and does its best quality printing on inexpensive, plain laser paper. In addition, higher quality rag-content bond papers can also be used effectively with a color laser printer. SMEs need an inexpensive laser printer that achieves quality results quickly. If you’re intent on reproducing photos, you’re better off with a good quality inkjet printer instead of a laser.
Since then, laser printers have decreased further in price and increased in quality. A laser printer is a common type of computer printer that reproduces high quality text and graphics on plain paper. Toner Cartridge Depot presents a convenient way to purchase quality office products, laser printer toners, ink cartridges and printer cartridges at competitive prices. Plus, low-end colour lasers often produce colour output quality that rivals that of much more expensive printers. Quality, resolution, and colorThe standard resolution in most laser printers today is 1200 dots per inch (dpi). – Excellent quality: The text is very clear with no dots visible anywhere – exactly what you would expect from a quality laser printer.
When it comes to quantity and quality, I use a Laser printer and if it happens to be a color laser, so be it. Color laser printers are for people who want the speed and text quality of a black-and-white laser but require color, too. However, only the most expensive color laser printers can match the true photo quality of the best photo ink jets.
While colored toner is available, color laser printers are generally much more expensive. 30% of a new product · This product is a recycled version of the used toner cartridge for laser printer. The toner is black in most cartridges, but may be cyan, magenta, and yellow in color laser printers. Inexpensive color laser printers usually ship with a starter set of toner cartridges, which generally hold about a third of a normal cartridge. Last year the answer would have been “go inkjet” because of quirks in laser printer toner technology. Color laser printers add colored toner (typically but not always cyan, yellow, and magenta
see CMYK) in three additional steps or passes. bulk toner will do but must include instructions for my minolta qms 2300 DL laser printer. Click here to save on laser printer toner. Firstly, if I went out and spent this much on a laser printer I wouldn’t expect to be shafted with a ’starter toner pack’. When it comes to laser printers, the main consumable cost you will encounter is toner cartridge replacement. A slightly modified colour laser printer addresses these toner particles to a solid support. Because an entire page is transmitted to a drum before the toner is applied, laser printers are sometimes called page printers. In a write-black printer the laser positively charges the printed areas to attract the toner, which gives better detail than a write-white printer.
Built on an advanced print engine, this 8ppm monochrome laser printer is productive and easy to use. First, laser printer cartridges are able to print thousands of pages and are usually cheaper per page than inkjet cartridges. Dot-matrix printers can print up to 500 cps, and laser printers range from about 4 to 20 text pages per minute. Because laser printers do not use ink, they have less image smearing problems than inkjet printers and are able to print pages faster. The result is a color laser printer that is ready to print as soon as you connect it. Today a comparable laser printer that boasts more memory, a higher print speed and duplexing capability can be had for about $300.00. The fastest color laser printers can print over 60 pages per minute (3600 pages per hour).
The laser printer does not print in color, but my project didn’t require color. If you print a lot, you too may want to consider adding a laser printer to your computer set-up. So whenever I click on the print icon, the document is automatically sent to the laser printer. Most laser printers print only in monochrome. The application being used must support Postscript in order for the laser printer to print Postscript documents. A laser printer with duplex printing can print on one side of the paper, turn the paper over, and print on the other side.
http://www.accessory-computer-store.com/laser-printer/
Charles M. Morelli asked:
If you’re in the market for a new cellphone, now is a great time to go shopping. Cellular carriers and resellers are constantly offering special offers. Some companies offer free cellphones (after rebates), calling plans with thousands of minutes, etc.
With all these ads, where do you start? You can go to a local wireless store and see the latest makes and models. You can also research a variety of cellphones on the Internet. If you go to a wireless store, be prepared to spend some time, energy, and gas.
If you want to shop from home or the office, and avoid any sales hassles, you can shop for a new cellphone on the Internet. You’ll save time, money, and gas, and possibly get a better deal on a new cellphone.
Three factors will determine how much you will pay for a new cellphone: 1.) PRICE, 2.) FEATURES, and 3.) CALLING PLAN.
If you’re on a tight budget and don’t want to pay anything up front for a cellphone, look for cellphone offers with instant rebates. The instant rebate amount is deducted from the cellphone’s purchase price when you order.
If the cellphone you want costs some money up front, look for cellphone offers with mail-in rebates. You’ll pay the purchase price of the cellphone when you order, and receive a mail-in rebate coupon.
Some cellphone offers promote rebates as much as $100.00 or more. Mail-in rebate checks can take several weeks to arrive, and they’re great if you don’t mind waiting for them. If and when you get a rebate check, it’s like getting cash back. For example, if your cellphone’s purchase price was $100.00, and you receive a $100.00 rebate check, your cost after the rebate is zero.
Cellphones with few features cost less than cellphones with advanced features. If you just want to make calls, you don’t need a cellphone with advanced features. If you’re going to take pictures, download videos, music, and e-mails, you’ll need a high-end model with advanced features like a QWERTY keyboard, camera, large video display, MP3 player, and more.
The last and most important factor is the calling plan. Plans differ from carrier to carrier and you have to decide which plan is best for you. Think how you will be using the phone regularly before choosing a plan. You should estimate how many minutes you will use each day during peak hours, which are typically from 6am-9pm, Monday to Friday. For example, if you can limit your talk time to 30 minutes a day, that comes out to approximately 600 minutes per month.
To get the best deal, look for a plan with the lowest monthly rate and the most minutes per month. Get a plan with more minutes than you’ll need to avoid costly overage charges. Monthly rates of some plans offering the same number of minutes per month could vary. Make sure to look for a plan that offers free long distance, weeknight, and weekend calls. This plan allows you to talk nationwide for a long time at night and on weekends.
If your relatives, friends, and co-workers use the same carrier, you might want to select that carrier. Some carriers offer unlimited mobile-to-mobile calling to other people on the same network or other money-saving features for free or a flat fee.
Some plans don’t offer certain cellphone models, and not all plans are available in all areas. If the plan you choose doesn’t offer the cellphone model you want, search for other cellphones that are offered by the plan. The cellphone you want may be offered by another plan from the same carrier or by a plan from a different carrier.
Great cellphone deals are out there, if you take the time and effort to look for them.
If you’re in the market for a new cellphone, now is a great time to go shopping. Cellular carriers and resellers are constantly offering special offers. Some companies offer free cellphones (after rebates), calling plans with thousands of minutes, etc.
With all these ads, where do you start? You can go to a local wireless store and see the latest makes and models. You can also research a variety of cellphones on the Internet. If you go to a wireless store, be prepared to spend some time, energy, and gas.
If you want to shop from home or the office, and avoid any sales hassles, you can shop for a new cellphone on the Internet. You’ll save time, money, and gas, and possibly get a better deal on a new cellphone.
Three factors will determine how much you will pay for a new cellphone: 1.) PRICE, 2.) FEATURES, and 3.) CALLING PLAN.
If you’re on a tight budget and don’t want to pay anything up front for a cellphone, look for cellphone offers with instant rebates. The instant rebate amount is deducted from the cellphone’s purchase price when you order.
If the cellphone you want costs some money up front, look for cellphone offers with mail-in rebates. You’ll pay the purchase price of the cellphone when you order, and receive a mail-in rebate coupon.
Some cellphone offers promote rebates as much as $100.00 or more. Mail-in rebate checks can take several weeks to arrive, and they’re great if you don’t mind waiting for them. If and when you get a rebate check, it’s like getting cash back. For example, if your cellphone’s purchase price was $100.00, and you receive a $100.00 rebate check, your cost after the rebate is zero.
Cellphones with few features cost less than cellphones with advanced features. If you just want to make calls, you don’t need a cellphone with advanced features. If you’re going to take pictures, download videos, music, and e-mails, you’ll need a high-end model with advanced features like a QWERTY keyboard, camera, large video display, MP3 player, and more.
The last and most important factor is the calling plan. Plans differ from carrier to carrier and you have to decide which plan is best for you. Think how you will be using the phone regularly before choosing a plan. You should estimate how many minutes you will use each day during peak hours, which are typically from 6am-9pm, Monday to Friday. For example, if you can limit your talk time to 30 minutes a day, that comes out to approximately 600 minutes per month.
To get the best deal, look for a plan with the lowest monthly rate and the most minutes per month. Get a plan with more minutes than you’ll need to avoid costly overage charges. Monthly rates of some plans offering the same number of minutes per month could vary. Make sure to look for a plan that offers free long distance, weeknight, and weekend calls. This plan allows you to talk nationwide for a long time at night and on weekends.
If your relatives, friends, and co-workers use the same carrier, you might want to select that carrier. Some carriers offer unlimited mobile-to-mobile calling to other people on the same network or other money-saving features for free or a flat fee.
Some plans don’t offer certain cellphone models, and not all plans are available in all areas. If the plan you choose doesn’t offer the cellphone model you want, search for other cellphones that are offered by the plan. The cellphone you want may be offered by another plan from the same carrier or by a plan from a different carrier.
Great cellphone deals are out there, if you take the time and effort to look for them.
19
Dec
Brian Cliette asked:
The key to opening a boutique that will sell cellphones is to find a great deal on cellphones. Cheap cellphones may lead someone to believe that they are cheap quality. However, this term refers only to the amount one would have to pay to obtain a wholesale quantity of cellphones in order for their business to resell for a profit. It is easy to get fooled into thinking you’re making a great deal buying on the Internet because you’ll never actually meet your dealer face-to-face. For this reason, it is important to only deal with reputable dealers when it comes to wholesale cellphones.
Wholesale Iphones Wholesale Cellphone Lists
To find a great deal on cheap cellphones, you could purchase the seller list from www.cellphonecellphone.com. They have the best contact list available on the Internet. With the list, you can find sellers all around the world who are dedicated to providing you and your business with a great deal on cell phones. At our website, you can choose from brand name cellphones or you can get cheap cellphones that have been previously used but have been completely refurbished.
Also available through www.cellphonecellphone.com is a section of articles and satisfied user testimonials. The articles can help you get to know the business of getting deals on cellphones and how to sell them for a good price and still make a profit. You can find information about cellphones and cellphone accessories in one place. This knowledge will be useful running your boutique because customers will inevitably want to ask questions that you will need to have the answers to. If you don’t know enough about the phones and accessories you are selling, you will probably lose the business of the customer and earn a reputation for being inexperienced. The user testimonials are a great way to know that this list is the real deal. People who have used the seller list to get cheap cellphones have been so satisfied with the results that they took the time to post about it for skeptical people such as yourself to read and know that they aren’t going to be wasting their time or money.
Cheap cellphones are available from different websites and companies around the world, but it can be difficult to know which ones you can trust. The best way to go about finding deals is to establish how much you are willing to pay and then find a seller who is within your range. It is vital to do the research to be sure that you are dealing with reputable people who are dedicated to getting a great product to you for a fair price. Running a business can be trial and error but if you work hard and learn as much as you can about your products, you re sure to keep your customers coming back. The key to running a successful business is to be honest and establish a good relationship with your customers. getting a deal on cheap cellphones could be the first step to the success of your new business.
The key to opening a boutique that will sell cellphones is to find a great deal on cellphones. Cheap cellphones may lead someone to believe that they are cheap quality. However, this term refers only to the amount one would have to pay to obtain a wholesale quantity of cellphones in order for their business to resell for a profit. It is easy to get fooled into thinking you’re making a great deal buying on the Internet because you’ll never actually meet your dealer face-to-face. For this reason, it is important to only deal with reputable dealers when it comes to wholesale cellphones.
Wholesale Iphones Wholesale Cellphone Lists
To find a great deal on cheap cellphones, you could purchase the seller list from www.cellphonecellphone.com. They have the best contact list available on the Internet. With the list, you can find sellers all around the world who are dedicated to providing you and your business with a great deal on cell phones. At our website, you can choose from brand name cellphones or you can get cheap cellphones that have been previously used but have been completely refurbished.
Also available through www.cellphonecellphone.com is a section of articles and satisfied user testimonials. The articles can help you get to know the business of getting deals on cellphones and how to sell them for a good price and still make a profit. You can find information about cellphones and cellphone accessories in one place. This knowledge will be useful running your boutique because customers will inevitably want to ask questions that you will need to have the answers to. If you don’t know enough about the phones and accessories you are selling, you will probably lose the business of the customer and earn a reputation for being inexperienced. The user testimonials are a great way to know that this list is the real deal. People who have used the seller list to get cheap cellphones have been so satisfied with the results that they took the time to post about it for skeptical people such as yourself to read and know that they aren’t going to be wasting their time or money.
Cheap cellphones are available from different websites and companies around the world, but it can be difficult to know which ones you can trust. The best way to go about finding deals is to establish how much you are willing to pay and then find a seller who is within your range. It is vital to do the research to be sure that you are dealing with reputable people who are dedicated to getting a great product to you for a fair price. Running a business can be trial and error but if you work hard and learn as much as you can about your products, you re sure to keep your customers coming back. The key to running a successful business is to be honest and establish a good relationship with your customers. getting a deal on cheap cellphones could be the first step to the success of your new business.
Brian Cliette asked:
We might as well face it: everyone has a cellphone these days. You can’t go anywhere in the United States without running into people carrying cellphones. They’re in the grocery store, they’re in line behind you at the ticket office, they’re in traffic next to you gabbing happily away. How is it that everyone in the country seems able to afford such costly cellphones with loads of cool features and still pay for their monthly plans? Twenty years ago, cellphones were a luxury that only the very wealthy could afford to own. Today, if you don’t have a cellphone then you’re treated as if you’re living in the Dark Ages. You’re out-of-touch, behind the times, technologically impaired – and all because you don’t have a cellphone. But how are you supposed to purchase a cellphone with all those extras like ringtones, camera-capability, graphics, games, and fun accessories? After all, no one is made of money, and new, upgraded phones are coming out every single day. But worry no more! Cheap Cellphones are now available at www.cellphonecellphone.com, so now everyone can try to keep up with the Joneses.
Wholesale Iphones Wholesale Cellphone Lists
Offering name-brand Cheap Cellphones at wholesale prices, using this website anyone can purchase the phones they want without having to take on a second job just to pay for them. The www.cellphonecellphone.com site allows you to purchase all the phones you desire, at the wholesale prices that previously only big-name cellphone suppliers were offered. Cellphones don’t have to be expensive when what you’re usually paying for is the brand-name associated with the product. Cheap Cellphones and accessories are now available to everyone, not just large companies already involved in the cellphone industry. You don’t have to be a business owner or cellphone supplier to take advantage of the rock-bottom prices offered on the site.
Why pay a higher price for your phone than these big companies? Cheap Cellphones, the phones at wholesale prices offered at www.cellphonecellphone.com are all the brand-name phones you see advertised on television every day. Offering the latest in cellphone technology and upgrades, it is now possible for anyone and everyone to stay in touch using the best cellphones on the market today – and the price you’ll pay is the price that big-name companies who sell hundreds of phones a week are offered. Big cellphone companies mark up prices on their phones, charging increasingly and ridiculously high amounts for phones that are slimmer, smaller, more technologically capable, and more attractive. But when all these same phones and cellphone products are offered at wholesale prices, it would be silly to pay the prices that the big names demand.
The Cheap Cellphones offered through the site are no different than the expensive cellphones you might buy in any number of cellphone stores located throughout the country. The only difference is in the price. The choice is yours. Either you can pay the high prices that big-name companies demand, prices they are forced to raise higher and higher in order to stay ahead of the competition and cover their huge overhead, or you can buy Cheap Cellphones at wholesale prices. The phones are all the same, but the prices are not.
We might as well face it: everyone has a cellphone these days. You can’t go anywhere in the United States without running into people carrying cellphones. They’re in the grocery store, they’re in line behind you at the ticket office, they’re in traffic next to you gabbing happily away. How is it that everyone in the country seems able to afford such costly cellphones with loads of cool features and still pay for their monthly plans? Twenty years ago, cellphones were a luxury that only the very wealthy could afford to own. Today, if you don’t have a cellphone then you’re treated as if you’re living in the Dark Ages. You’re out-of-touch, behind the times, technologically impaired – and all because you don’t have a cellphone. But how are you supposed to purchase a cellphone with all those extras like ringtones, camera-capability, graphics, games, and fun accessories? After all, no one is made of money, and new, upgraded phones are coming out every single day. But worry no more! Cheap Cellphones are now available at www.cellphonecellphone.com, so now everyone can try to keep up with the Joneses.
Wholesale Iphones Wholesale Cellphone Lists
Offering name-brand Cheap Cellphones at wholesale prices, using this website anyone can purchase the phones they want without having to take on a second job just to pay for them. The www.cellphonecellphone.com site allows you to purchase all the phones you desire, at the wholesale prices that previously only big-name cellphone suppliers were offered. Cellphones don’t have to be expensive when what you’re usually paying for is the brand-name associated with the product. Cheap Cellphones and accessories are now available to everyone, not just large companies already involved in the cellphone industry. You don’t have to be a business owner or cellphone supplier to take advantage of the rock-bottom prices offered on the site.
Why pay a higher price for your phone than these big companies? Cheap Cellphones, the phones at wholesale prices offered at www.cellphonecellphone.com are all the brand-name phones you see advertised on television every day. Offering the latest in cellphone technology and upgrades, it is now possible for anyone and everyone to stay in touch using the best cellphones on the market today – and the price you’ll pay is the price that big-name companies who sell hundreds of phones a week are offered. Big cellphone companies mark up prices on their phones, charging increasingly and ridiculously high amounts for phones that are slimmer, smaller, more technologically capable, and more attractive. But when all these same phones and cellphone products are offered at wholesale prices, it would be silly to pay the prices that the big names demand.
The Cheap Cellphones offered through the site are no different than the expensive cellphones you might buy in any number of cellphone stores located throughout the country. The only difference is in the price. The choice is yours. Either you can pay the high prices that big-name companies demand, prices they are forced to raise higher and higher in order to stay ahead of the competition and cover their huge overhead, or you can buy Cheap Cellphones at wholesale prices. The phones are all the same, but the prices are not.
Steve Knowles asked:
The GPS-enabled cellphone market is forecast to more than double by 2012, hitting 550 million units. Put it all
together and GPS chipset revenue is expected to more than double to $1.3 billion in just three years time,
according to In-Stat. The GPS-based NextGen system, slated for completion by 2025, will straighten routes (blue)
and allow more planes to safely share the skies. Currently, Air Traffic Control Towers (ATCT) guide planes through
takeoff, then hand them over to a Terminal Radar Approach Control (TRACON) facility that keeps approach and
departure corridors orderly over the next 50 miles. The GPS system has been designed to be as nearly accurate as
possible. However, there are still errors.
Cell phone GPS tracking can also be a useful feature to the emergency services or police when responding to a 911
call from a GPS cell phone. For this reason, the FCC has legislated that wireless networks provide location
information for 911 calls made from cell phones. Cell phone GPS tracking systems is touted as one of the most
advanced technological milestones in the history of mobile communication systems. Global Positioning Systems (GPS)
enables the users to trail his own location through the analysis of satellite signals beamed down from many
satellites. Cell phone GPS website Mandated in the aftermath of September 11th, the Federal Communication
Commission (FCC) required cell service providers to make GPS tracking of cell phone calls possible. All phones made
since 2005 are GPS-trackable.
Cell phone GPS tracking is one of those advances. Cell Phone GPS tracking can prove useful in many walks of life
and especially when any emergency arises. Picture the scene of a road accident where injuries have occurred.
Update: Nokia intend the N95 to be a powerful one for all replacement for a media player, digital camera, digital
camera, PDA and now a GPS navigation device. It features a 2-way slide concept to simplify switching between
different functionalities. Nokia, Motorola and Beneflon are just a few of the companies now providing GPS-enabled
phones. This will change as the other manufacturers catch up, then we will see this technology being installed as a
default inclusion.
The GPS-enabled cellphone market is forecast to more than double by 2012, hitting 550 million units. Put it all
together and GPS chipset revenue is expected to more than double to $1.3 billion in just three years time,
according to In-Stat. The GPS-based NextGen system, slated for completion by 2025, will straighten routes (blue)
and allow more planes to safely share the skies. Currently, Air Traffic Control Towers (ATCT) guide planes through
takeoff, then hand them over to a Terminal Radar Approach Control (TRACON) facility that keeps approach and
departure corridors orderly over the next 50 miles. The GPS system has been designed to be as nearly accurate as
possible. However, there are still errors.
Cell phone GPS tracking can also be a useful feature to the emergency services or police when responding to a 911
call from a GPS cell phone. For this reason, the FCC has legislated that wireless networks provide location
information for 911 calls made from cell phones. Cell phone GPS tracking systems is touted as one of the most
advanced technological milestones in the history of mobile communication systems. Global Positioning Systems (GPS)
enables the users to trail his own location through the analysis of satellite signals beamed down from many
satellites. Cell phone GPS website Mandated in the aftermath of September 11th, the Federal Communication
Commission (FCC) required cell service providers to make GPS tracking of cell phone calls possible. All phones made
since 2005 are GPS-trackable.
Cell phone GPS tracking is one of those advances. Cell Phone GPS tracking can prove useful in many walks of life
and especially when any emergency arises. Picture the scene of a road accident where injuries have occurred.
Update: Nokia intend the N95 to be a powerful one for all replacement for a media player, digital camera, digital
camera, PDA and now a GPS navigation device. It features a 2-way slide concept to simplify switching between
different functionalities. Nokia, Motorola and Beneflon are just a few of the companies now providing GPS-enabled
phones. This will change as the other manufacturers catch up, then we will see this technology being installed as a
default inclusion.
23
Oct
Dhiraj Bandurkar asked:
Wireless Routers
Like any other wireless system, a wireless router gives you freedom to free the valuable workspace from the tangling wires. Technically speaking, a wireless router is a special network router that connects different workstations wirelessly and routes network traffic between workstations and an existing Internet connection. Some of the wireless routers are actually wired routers with wireless access points built in so you can have wired and/or wireless at the same time. Another choice is a wireless router with a built-in DSL or cable modem. You can also consider a hardware & software security combo box to connect and protect your home network or office network. The wireless router is capable of sharing Internet connections amongst several computers via 802.3 Ethernet and 802.11b/g wireless data links.
The wireless routers are quite popular among the network users. More so, because it is as good as using the wired networks with absolutely no compromise on the connectivity, speed, and security. A wireless LAN router generally adds a built-in access point function to a multi-port Ethernet router. With this it combines multiple Ethernet networks with wireless connections as well. A typical wireless LAN router includes four Ethernet ports, an 802.11 access point, and sometimes a parallel port so it can function as a print server. This gives wireless users the same ability as wired users to send and receive packets over multiple networks.
There are many manufacturers of the wireless routers, popular of them are D-Link, Netgear, Actiontec etc. Out of these, the D-Link routers is what we find is the popular product amongst the home and commercial users. These wireless routers have an uncanny ability that delivers superior performance capability to transfer large files and handle heavy network traffic. Wireless routers offer many important benefits in the home and small office setting. For instance, you can opt to a cable modem service that provides a single IP address through DHCP to the router, and the router then provides IP addresses via DHCP to clients on your local network. This helps to a great deal whenever that client needs to access the Internet. Wireless routers are very much ideal for wireless networks in commercial or public areas, specially if there are multiple networks that are accessible. The wireless routers if considered in an enterprise environment give network administrators an extra way to monitor and update their networks. As the wireless routers only send packets to specific, directed addresses, they do not forward the broadcast packets that are sent out by other devices. A big advantage of wireless routers is that they provide an added layer of security, both on the wired side and wireless side. The wired side is usually protected by a firewall and has extensive access control filters.
That is why, not only the wireless routers are more user friendly and space saving, they are also great on speed, and have an ability to handle multiple networks with ease and without sacrificing the security.
Wireless Routers
Like any other wireless system, a wireless router gives you freedom to free the valuable workspace from the tangling wires. Technically speaking, a wireless router is a special network router that connects different workstations wirelessly and routes network traffic between workstations and an existing Internet connection. Some of the wireless routers are actually wired routers with wireless access points built in so you can have wired and/or wireless at the same time. Another choice is a wireless router with a built-in DSL or cable modem. You can also consider a hardware & software security combo box to connect and protect your home network or office network. The wireless router is capable of sharing Internet connections amongst several computers via 802.3 Ethernet and 802.11b/g wireless data links.
The wireless routers are quite popular among the network users. More so, because it is as good as using the wired networks with absolutely no compromise on the connectivity, speed, and security. A wireless LAN router generally adds a built-in access point function to a multi-port Ethernet router. With this it combines multiple Ethernet networks with wireless connections as well. A typical wireless LAN router includes four Ethernet ports, an 802.11 access point, and sometimes a parallel port so it can function as a print server. This gives wireless users the same ability as wired users to send and receive packets over multiple networks.
There are many manufacturers of the wireless routers, popular of them are D-Link, Netgear, Actiontec etc. Out of these, the D-Link routers is what we find is the popular product amongst the home and commercial users. These wireless routers have an uncanny ability that delivers superior performance capability to transfer large files and handle heavy network traffic. Wireless routers offer many important benefits in the home and small office setting. For instance, you can opt to a cable modem service that provides a single IP address through DHCP to the router, and the router then provides IP addresses via DHCP to clients on your local network. This helps to a great deal whenever that client needs to access the Internet. Wireless routers are very much ideal for wireless networks in commercial or public areas, specially if there are multiple networks that are accessible. The wireless routers if considered in an enterprise environment give network administrators an extra way to monitor and update their networks. As the wireless routers only send packets to specific, directed addresses, they do not forward the broadcast packets that are sent out by other devices. A big advantage of wireless routers is that they provide an added layer of security, both on the wired side and wireless side. The wired side is usually protected by a firewall and has extensive access control filters.
That is why, not only the wireless routers are more user friendly and space saving, they are also great on speed, and have an ability to handle multiple networks with ease and without sacrificing the security.