Computer Networks and Communications
Content
COMPUTER NETWORKS AND COMMUNICATIONS 1.Introduction Mobile Computing is an umbrella term used to describe technologies that enable people to access network services anyplace, anytime, and anywhere. Ubiquitous computing and nomadic computing are synonymous with mobile computing. Information access via a mobile device is plagued by low available bandwidth, poor connection maintenence, poor security, and addressing problems. Unlike their wired counterparts, design of software for mobile devices must consider resource limitation, battery power and display size. Consequently, new hardware and software techniques must be developed. For example, applications need to be highly optimized for space, in order to fit in the limited memory on the mobile devices. For Internet enabled devices, the good old TCP/IP stack cannot be used; it takes too much space and is not optimized for minimal power consumption. Given the plethora of cellular technologies that have emerged in such a market, it becomes extremely difficult to provide support for interdevice communication 2.Content Mobile Computing *Specification of Mobile Computing Mobile computing used to be exclusively a matter of dragging a laptop computer around,* plus various adapters and other widgets. Road warriors have more choices now. Of course, USB thumb drives, also called USB flash drives, are probably the benchmark technology for mobile computing these days; before you think about other methods, check if you can do it cheaper and easier with a thumb drive. *Services of Mobile Computing Mobility services can be classified into three groups. First there are services designed to overcome common restrictions of mobile computing, which arise mainly from the slowness, insecurity and instability of wireless or analogous connection lines utilized by the mobile user. These services are called common mobility services (CMS). Examples are connection management, caching or encryption services. The second group of services handles the management and administration of mobile users moving around and connecting their portables to networks at different places. These mobility management services (MMS) include tasks such as the authentication of users, accounting and billing issues or profiling of the users habits. The tasks necessary to adapt certain existing applications to mobile usage are implemented by high level services, which are called special mobility services (SMS). Special mobility services adapt existing services to the mobile conditions. For example to allow remote database access over a wireless connection line one has to take special care of possible frequent connection losses especially in the context of the state of the database. Viewing services as distinct building blocks, we are able to sketch an architecture for a mobility services enhanced system .
*Frequencies of Mobile Computing Bluetooth is an industrial specification for wireless personal area networks (PANs). Bluetooth provides a way to connect and exchange information between devices such as mobile phones, laptops, PCs, printers, digital cameras, and video game consoles over a secure, globally unlicensed short-range radio frequency. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group. Bluetooth technology relies on two things, a radio frequency technology and the protocol software enabling it to transmit data to other devices. Bluetooth-capable devices can transmit data to other devices not within the line of sight of the user. It also enables different devices to communicate using certain rules such as the amount of data that will be sent, the type of communication between the devices and the radio frequency or frequencies this communication will take place. These protocols ensure that Bluetooth devices experience the least amount of interference from other Bluetooth capable objects while communicating with each other. smartphones are the ideal productivity solution for both voice and data for your mobile workforce. They ll be able to stay in touch with the people and information that matter most. Access email, instant message, access the Internet, run business applications and more.Communicate your way: Call, email, instant message, or text message, all with one device. Internet Technology and Services EXPLAIN VOIP (Voice Over IP) A telephone service that uses the Internet as a global telephone network. Many companies, including Vonage, 8×8 and AT&T (CallVantage), typically offer calling within the country for a fixed fee and a low per-minute charge for international. Broadband Internet access (cable or DSL) is required, and regular house phones plug into an analog telephone adapter (ATA) provided by the company or purchased from a third party. Explain BLOG A blog is a lot like a journal except it is generally intended to be read by others. The topics for blogs vary greatly; some being about day to day activities and others taking a more corporate or political slant. There is no defined or widely accepted format and so blogs range from one liners that the author adds every few hours to relatively long, well thought out arguments for or against a topic of interest. Types of network EXPLAIN PAN, VPN, WLAN, AND WIMAX PAN
A Personal Area Network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. The devices may or may not belong to the person in question. The reach of a PAN is typically a few meters. PANs can be used for communication among the personal devices themselves (intrapersonal communication), or for connecting to a higher level network and the Internet (an uplink). Personal area networks may be wired with computer buses such as USB and FireWire. A wireless personal area network (WPAN) can also be made possible with network technologies such as IrDA and Bluetooth. VPN Short for (Virtual Private Network), VPN is a type of network that allows a user to connect to a network through a tunneling protocol and access internal internet and intranet web sites and email. Virtual Private Networks are commonly used to allow an employee with a large company to connect to the company s intranet WLAN A wireless LAN (or WLAN, for Wireless Local Area Network, sometimes referred to as LAWN, for local area wireless network) is one in which a mobile user can connect to a local area network (LAN) through a wireless (radio) connection. The IEEE 802.11 group of standards specify the technologies for wireless LANs. 802.11 standards use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing and include an encryption method, the Wired Equivalent Privacy algorithm. A personal area network WIMAX WiMax is the industry term for a long-range wireless networking standard. WiMax technology has the potential to deliver high-speed Internet access to rural areas and other locations not serviced by cable or DSL technology. WiMax also offers an alternative to satellite Internet services.WiMax technology is based on the IEEE 802.16 WAN communications standard. WiMax signals can function over a distance of several miles / kilometers. Data rates for WiMax can reach up to 75 megabits per second (Mb/s). A number of wireless signaling options exist ranging anywhere from the 2 GHz range up to 66 GHz. Conclusion Mobile computing (like the peer to peer transaction model did) brings about a new paradigm of distributed computing in which communication may be achieved through wireless networks and users can compute even as they relocate from one support environment to another. The impact of mobile computing on systems design goes beyond the networking level and directly effects data management. Although being a relatively new area, mobile data management has attracted a lot of research efforts, motivated by both a great market potential and by many challenging research problems
Reference Book Shelly Cashman,SVermat (2004),Thomson Course Technology, Discovery Computer. Internet http://en.wikipedia.org/wiki/image:Bluetooth.headset.jpg www.wimax.com/deployment/network
*Frequencies of Mobile Computing Bluetooth is an industrial specification for wireless personal area networks (PANs). Bluetooth provides a way to connect and exchange information between devices such as mobile phones, laptops, PCs, printers, digital cameras, and video game consoles over a secure, globally unlicensed short-range radio frequency. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group. Bluetooth technology relies on two things, a radio frequency technology and the protocol software enabling it to transmit data to other devices. Bluetooth-capable devices can transmit data to other devices not within the line of sight of the user. It also enables different devices to communicate using certain rules such as the amount of data that will be sent, the type of communication between the devices and the radio frequency or frequencies this communication will take place. These protocols ensure that Bluetooth devices experience the least amount of interference from other Bluetooth capable objects while communicating with each other. smartphones are the ideal productivity solution for both voice and data for your mobile workforce. They ll be able to stay in touch with the people and information that matter most. Access email, instant message, access the Internet, run business applications and more.Communicate your way: Call, email, instant message, or text message, all with one device. Internet Technology and Services EXPLAIN VOIP (Voice Over IP) A telephone service that uses the Internet as a global telephone network. Many companies, including Vonage, 8×8 and AT&T (CallVantage), typically offer calling within the country for a fixed fee and a low per-minute charge for international. Broadband Internet access (cable or DSL) is required, and regular house phones plug into an analog telephone adapter (ATA) provided by the company or purchased from a third party. Explain BLOG A blog is a lot like a journal except it is generally intended to be read by others. The topics for blogs vary greatly; some being about day to day activities and others taking a more corporate or political slant. There is no defined or widely accepted format and so blogs range from one liners that the author adds every few hours to relatively long, well thought out arguments for or against a topic of interest. Types of network EXPLAIN PAN, VPN, WLAN, AND WIMAX PAN
A Personal Area Network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. The devices may or may not belong to the person in question. The reach of a PAN is typically a few meters. PANs can be used for communication among the personal devices themselves (intrapersonal communication), or for connecting to a higher level network and the Internet (an uplink). Personal area networks may be wired with computer buses such as USB and FireWire. A wireless personal area network (WPAN) can also be made possible with network technologies such as IrDA and Bluetooth. VPN Short for (Virtual Private Network), VPN is a type of network that allows a user to connect to a network through a tunneling protocol and access internal internet and intranet web sites and email. Virtual Private Networks are commonly used to allow an employee with a large company to connect to the company s intranet WLAN A wireless LAN (or WLAN, for Wireless Local Area Network, sometimes referred to as LAWN, for local area wireless network) is one in which a mobile user can connect to a local area network (LAN) through a wireless (radio) connection. The IEEE 802.11 group of standards specify the technologies for wireless LANs. 802.11 standards use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing and include an encryption method, the Wired Equivalent Privacy algorithm. A personal area network WIMAX WiMax is the industry term for a long-range wireless networking standard. WiMax technology has the potential to deliver high-speed Internet access to rural areas and other locations not serviced by cable or DSL technology. WiMax also offers an alternative to satellite Internet services.WiMax technology is based on the IEEE 802.16 WAN communications standard. WiMax signals can function over a distance of several miles / kilometers. Data rates for WiMax can reach up to 75 megabits per second (Mb/s). A number of wireless signaling options exist ranging anywhere from the 2 GHz range up to 66 GHz. Conclusion Mobile computing (like the peer to peer transaction model did) brings about a new paradigm of distributed computing in which communication may be achieved through wireless networks and users can compute even as they relocate from one support environment to another. The impact of mobile computing on systems design goes beyond the networking level and directly effects data management. Although being a relatively new area, mobile data management has attracted a lot of research efforts, motivated by both a great market potential and by many challenging research problems
Reference Book Shelly Cashman,SVermat (2004),Thomson Course Technology, Discovery Computer. Internet http://en.wikipedia.org/wiki/image:Bluetooth.headset.jpg www.wimax.com/deployment/network
