Cellular Networks and Wireless Data Applications - Essay Example

Cellular Networks and Wireless Data Applications Cellular Networks - An Overview A cellular network is a radio network made up of a number of radio cells (or just cells) each served by a fixed transmitter, known as a cell site or base station. These cells are used to cover different areas in order to provide radio coverage over a wider area than the area of one cell. Cellular networks are inherently asymmetric with a set of fixed main transceivers each serving a cell and a set of distributed (generally, but not always, mobile) transceivers which provide services to the network's users. Cellular networks offer a number of advantages over alternative solutions: Increased capacity Reduced power usage Better coverage (Wikipedia) There are two main competing technologies in a cellular network. They are: Global System for Mobile Communications (GSM' and Code Division Multiple Access (CDMA) The network technology used in both the above varies. In order to select a preferable network technology that suits the individual needs, understanding the difference between both the technologies is very important. GSM - The GSM association is an international organization that was founded in the year 1987. The main objective of the organization was to provide and develop (Sameer) Likewise CDMA is a proprietary standard that was designed by the Qualcomm of the United States of America. The CDMA network was popular in North America and Asia. GSM technology became popular in America whereas the CDMA technology gained popularity in the outer parts of America and various other parts of the world. With the advent of cellular phones doing double and triple duty as streaming video devices, podcast receivers and email devices, speed is important to those who use the phone for more than making calls. CDMA has been traditionally faster than GSM, though both technologies continue to rapidly leapfrog along this path. Both boast "3G" standards, or 3rd generation technologies. EVDO, also known as CDMA2000, is CDMA's answer to the need for speed with a downstream rate of about 2 megabits per second, though some reports suggest real world speeds are closer to 300-700 kilobits per second (kbps). This is comparable to basic DSL. As of fall 2005, EVDO is in the process of being deployed. It is not available everywhere and requires a phone that is CDMA2000 ready. GSM's answer is EDGE (Enhanced Data Rates for GSM Evolution), which boasts data rates of up to 384 kbps with real world speeds reported closer to 70-140 kbps. With added technologies still in the works that include UMTS (Universal Mobile Telephone Standard) and HSDPA (High Speed Downlink Packet Access), speeds reportedly increase to about 275-380 kbps. This technology is also known as W-CDMA, but is incompatible with CDMA networks. An EDGE-ready phone is required. In the case of EVDO, theoretical high traffic can degrade speed and performance, while the EDGE network is more susceptible to interference. Both require being within close range of a cell to get the best speeds, while performance decreases with distance. The most common example of the cellular network with respect to the present day technology is the Cellular phone or the mobile phone. The use of cellular network with relevance to the mobile phones is explained in detail below. Cellular phones, today, have become like any other consumer durable, which almost every common is using everyday. This development, in the world of cellular communication has happened during the last two decades. Cellular phone is a device that helps us communicate with other people staying anywhere in the world. Most of the people who use a cellular phone do not actually know how this process of communicating over phone with a person in another part of the world is possible. The communication process that is taking place through a cellular phone is with the help of a supportive infrastructure called as the Cellular network. With the help of this supportive infrastructure, cellular phones are integrated into the Public Switch Telephone Network (PSTN). All the cell phones and mobile stations of the cellular networks are provided a wireless access to the PSTN. The entire network is divided into a number of small parts called as cells. These cells are known as the coverage areas of the network. Every cell is served by a Base Station (BS) which is fixed. This Base Station is further connected to the Mobile Telephone Switching Office (MTSO). MTSO is also known as mobile switching center. The connections do not end here. A cluster of Base Stations are connected to the MRSO which further is connected to the PSTN. The spectrum of frequency that is allowed for cell phones is in fact very limited and minimal in nature. Despite this drawback, today's cellular networks are very successful. This is with the help of the frequency reuse concept. This is why the coverage area is divided into cells, each of which is served by a BS. Each BS (or cell) is assigned a group of frequency bands or channels. To avoid radio co-channel interference, the group of channels assigned to one cell must be different from the group of channels assigned to its neighboring cells. Though there should be variation in the cells of the group to avoid radio channel interference, two similar cells which are far apart from each other can be assigned to the same group. A typical formation is created by joining a cluster of seven neighborhood cells. (Zhang) The concept of frequency reuse is pictorially represented below: If there are a total of M channels allocated for cellular communications and if the coverage area consists of N cells, there are a total of MN/7 channels available in the coverage area for concurrent use based on the seven-cell reuse pattern. That is the network capacity of this coverage area. Because of the increasing usage of the mobile phones, the capacity of the network may not be sufficient. In order to handle this, a technique called cell splitting is used. (Black) (Rappaport) According to the Cell splitting technique, the sizes of the cells are decreased by lowering both the transmitter power and also the height of the antenna. If an original cell is divided into four smaller cells then the coverage area with say N cells will be covered by 4N cells that are smaller in size. Now the capacity of the new cell can be represented as 4MN/7. This capacity is four times smaller than the original network capacity. Characteristics of a Cellular Network Each and every distribution station of the cellular network should be standardized and also should be able to differentiate between the signals from its own transmitter and other transmitter signals. This is the basic requirement of any successful network. In order to make the cellular networks better there were two different aspects that were discovered. They are Frequency Division Multiple Access (FDMA) and Code Division Multiple Access (CDMA). FDMA works by using varying frequencies for each neighboring cell. By tuning to the frequency of a chosen cell the distributed stations can avoid the signal from other cells. The principle of CDMA is more complex, but achieves the same result; the distributed transceivers can select one cell and listen to it. Other available methods of multiplexing such as polarization division multiple access (PDMA) and time division multiple access (TDMA) cannot be used to separate signals from one cell to the next since the effects of both vary with position and this would make signal separation practically impossible. Time division multiple access, however, is used in combination with either FDMA or CDMA in a number of systems to give multiple channels within the coverage area of a single cell. Wireless Data Applications Wireless networks are the fastest growing trend in networks - no wires are necessary to make the connection their application to mobile computers such as notebook computers and personal digital assistants (PDAs) are the fastest growing segment of the computer industry today. Wireless networks have many uses. A common use is the creation of a portable office. People often want to use their portable electronic equipment to send and receive telephone calls, faxes, and electronic mails, and access remote files and so on from anywhere on land, sea or air. Wireless networks uses three major protocols as described below: Wireless application protocol (WAP) a special protocol that allows mobiles to connect to the internet. Short Messaging Services (SMS) a service of sending text messages of up to 160 characters long to mobile phones. Global System for Mobile (GSM) the most widely used mobile telephone protocol worldwide. (ICMR) Given below is a brief description about the Wireless Data Applications (MobileInfo.com) Wireless Networks GSM Network & Wireless Data Information GSM Network Summary Brief description A 2nd generation digital cellular communications network technology that has been established as a worldwide standard except in North America and Japan. Corresponds to PCS in services offered, but its standards are different. Components Mobile user equipment with international mobile subscriber identity (IMSI) in a SIM module implemented as a smart card. Base station subsystem. Mobile services switching center (MSC). SS-7 network and four databases - home location, visitor, authentication and security. Frequency bands 849-890 MHz, 935-960 MHz and 1.7-1.8 GHz frequency bands have been reserved for GSM operation. Coverage Extensive in Europe, Asia, South America (almost a defector standard).' In USA and Canada, it competes with CDMA and TDMA-based PCS networks.' Capacity and speed Greater than AMPS-based cellular and growing rapidly: 22 million subscribers can be expected by the year 2000. 9,600 bps for data Communications protocols supported X.25 and ISDN LAPD TCP/IP through emulation but not natively' Most suitable applications GSM-based Short message service (SMS) similar to North America's narrowband PCS 2-way paging. Other data applications, including access to the Internet Facsimile. Costs 50 % higher than analog cellular in the U.S. Availability Now - ahead of PCS implementation in the U.S. Security Very good. Pros Dominant international standard in most of the world. Low-cost all-digital mobile user set. Purely digital. Cons No backward compatibility with analog. Slower speed (typically 9600) as compared to 19.2 or higher with CDMA/TDMA PCS. Higher service fees than PCS despite advanced infrastructure development. The wireless market consists of five primary applications. All of these applications, with the exception of Notification, require a two-way wireless network. Notification This is the first wireless technology to be widely accepted by customers in the U.S. Notification is the familiar numeric paging, text paging and the new acknowledgement paging services offered by the paging service providers. This market should keep expanding although many mobile professionals may shift to SMS (Small Messaging Service) on their digital wireless telephones as that capability improves. Notification is the application where paging service providers excel. Telemetry This market is Two-Way Messaging for fixed devices. It is unique in that it provides messaging services to devices (e.g., pumps, vending machines, pipelines, electrical substations, traffic signals, etc.) not humans. Today, private networks carry most telemetry activity. However, as public networks offer these services; new devices are also using public networks. Two-Way Messaging Two-Way Messaging is the wireless transmission of short messages (usually under 2,000 characters) between belt-worn or palm-size devices rather than full email. While Two-Way Messaging is being used today in devices such as Research in Motion's Interactive Pager, it still faces the challenge to integrate seamlessly important message delivery with existing email services. With wireless voice systems such as GSM, CDMA, and iDEN "cellular phones" currently adding data capabilities, many mobile professionals may find these services adequate for checking email up to two or three times a day. The growth of email and the need for real-time response may drive professionals to small Two-Way Messaging devices so that they can handle the growing information flow at anytime (e.g., waiting for others, walking between buildings, meetings) to make them more productive. Email Two-Way Messaging and Email are different in a couple of ways. Email is defined as messages that are not time critical (can be handled within one or two business days), messages that are large (greater than a few hundred words), and messages that contain attached documents. At this time, Metricom and Wireless Voice Networks can handle true email. Packet data networks such as BellSouth Wireless Data and American Mobile/ARDIS can easily handle moderate-size messages up to and, in some cases, beyond 10,000 characters. Interactive Data Exchange Interactive Data Exchange includes the set of applications that is usually referred to as "query-response." These messages are based on forms. A form is filled out and the information (query) is sent to a specific database server. The reply (response) is received back into the same or a different form depending upon the application. Interactive Data Exchange also includes "push" messaging. Push messaging occurs when the server initiates a connection and "pushes" messages to a user in the field. Examples of interactive data exchange are police access to criminal information databases, package delivery and racking, dispatch applications and consumers purchasing movie tickets. Some sales force automation applications such as order entry and order status also fall into this application area. There are two types of data networks-switched circuit and packet. Switched circuit is often called "dial-up". A device using a switched circuit network only connects to it when data is to be sent. For example, when dialing an ISP to get on the Internet you are using a switched circuit network. In fact, all telephone calls are made over a switched circuit network. The connection is only present when you are talking. With switched circuit networks, you pay for the amount of time you are "connected" and the connection needs to be established each time, usually by dialing a telephone number. While connected on a switched circuit network you have exclusive use of the connection you have established and can send data continuously. A packet network is one where you are connected all the time and only pay for the actual data sent. On a packet network, your data is divided into small packets. Each packet has a destination and source address attached to it. It is like dialing a number each time a packet is sent, but much faster. Packet networks are more efficient for many kinds of data applications and allow for instant communications without the need to establish a (dial up) connection to the network. Nearly all data-only wireless networks are packet networks. In contrast, nearly all voice-only networks are switched circuit. (Systems) Many general remote access computer connections assume the user will establish a dial up connection and, therefore, they have been designed for use in such environments. In order for many applications to use a packet network, the software must be modified to communicate via a packet network. This can be easily accomplished using middleware which provides a standard interface to wireless data networks and shields developers from the many challenges of achieving reliable communication in a wireless environment. (SUN microsystems) Private Packet-Data Networks In a private network, a company or government agency purchases radio frequencies and buys and operates the entire radio network infrastructure for the exclusive use of that entity. Private networks are primarily operated to ensure network availability at all times. Since the network is privately operated, the bandwidth is not shared with other users as in a private network; therefore, the network can be built to the capacity required to ensure availability. Voice-And-Data Networks Digital phone networks will soon be offering circuit-switched data at reasonable speeds with high reliability. These networks will roll out faster switched circuit dial-up speeds over the next two to three years. These networks will also support packet data. This capability will develop over the next several years with speeds ranging from 14.4 to 384 Kbps. These networks also offer very short message data using a technology called Short Messaging System (SMS). Using SMS, only a few hundred characters can be sent at a time over the network. SMS is designed as a pager replacement technology for digital phones. SMS can also be used to signal devices to make Switched circuit connections or other functions. The next advancement for data on these networks is the offering of switched circuit data. Switched circuit offers the same dial-up service that one gets using a standard telephone connection. Also these days Wireless LANs have become popular. A wireless LAN eliminates or greatly reduces the need for wires and cables. Thus, it becomes much easier to set up, relocate and maintain a LAN. (Wikipedia)LAN radio may either involve a high frequency radio technology similar to digital cellular, or a low frequency radio technology, called spread spectrum. The other wireless LAN technology is called infrared because it uses beams of infrared rays to establish network links between the various LAN components. (ICMR) The market outlook for widespread adoption of wireless data over the next few years is strong. In addition to the drivers above, a couple of new technologies and services make the outlook for wireless data bright. New technologies, like wireless Personal Area Networks (PANs), will make it easier for professionals to connect their computing devices with wide area wireless networks. An important requirement for professionals to adopt new technology is its ease-of-use. The advent of PANs is likely to significantly increase wireless use by mobile professionals. (Systems) The cost of wireless devices and network usage is dropping fast. For example, the cost of a cellular telephone and the associated service has fallen significantly over the last 10 years. It is expected that this trend will continue. As the cost of wireless devices and services drop, the overall use of wireless data will grow. Many new devices are becoming available that fit better with the needs of a broader set of individual needs in the professional segment. The traditional "business operations" applications of wireless data will continue to grow also. Bibliography 1. Black. 1996. 2. ICMR. Information Technology & Systems. Hyderabad: ICFAI Center for Management Research, 2003. 3. MobileInfo.com. MOBILEINFO.COM. 12 Novermber 2007 . 4. Rappaport. 2002. 5. Sameer. Quazen. 30 June 2006. 12 November 2007 . 6. SUN microsystems. SDN. 12 November 2007 . 7. Systems, Nettech. Introduction to Wireless Data. 12 November 2007 . 8. Wikipedia. Wikipedia. August 2005. 12 November 2007 . 9. -. Wikipedia. 12 November 2007 . 10. Zhang, Jinguyan. Cellular Networks. 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