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Now you can get accurate, crystal clear information on lightning fast, always-on GPRS, the 2.5G technology thatís setting the pace today in handheld Internet access. Youíll find it in GPRS: General Packet Radio Service, the first and only guide to answer such fundamental questions as "What is it?" "How does it work?" and "How much is it going to cost me?" The author, telecom expert and best-selling writer R.J. "Bud" Bates, reveals GPRSís features, functions, and architecture, information crucial whether youíre providing or applying GPRS. His straightforward, abundantly illustrated, step-by-step presentation of how GPRS works, how it connects the Internet, and how to implement it will help you put GPRS in place quickly and profitably as you explore:
Before delving directly into the GPRS systems and services, it is prudent to have common ground on the use of the radio-based systems. Therefore, a review (or introduction) of GSM is appropriate. After all, if GPRS is an over-lay to GSM, we should at least understand how and why GSM works.
Commercial service was introduced in mid-1991. By 1993, 36 GSM networks were already operating in 22 countries. Today, you can be instantly reached on your mobile phone in over 171 countries worldwide and on 400 networks (operators). Over 550 million people were subscribers to GSM mobile telecommunications.1 GSM truly stands for Global System for Mobile telecommunications. Roaming is the ability to use your GSM phone number in another GSM network. You can roam to another region or coun-try and use the services of any network operator in that region that has a roaming agreement with the GSM network operator in your home region/country. A roaming agreement is a business agreement between two network operators to transfer items such as call charges and subscription information back and forth as their subscribers roam into each other's areas.
The frequency band allocated to a cellular mobile radio system is distributed over a group of cells and this distribution is repeated in all of an operator's coverage area. The entire number of radio channels available can then be used in each group of cells that form the operator's coverage area. Frequencies used in a cell will be reused several cells away. The distance between the cells using the same frequency must be sufficient to avoid interference. The frequency reuse will increase the capacity in the number of users considerably. The patterns can be a four-cell pattern or other choices. The typical clusters contain 4, 7, 12, or 21 cells.
In order to work properly, a cellular system must verify the following two main conditions:
The number of cells in each cluster is very important. The smaller the number of cells per cluster, the greater the number of channels per cell. Therefore, the capacity of each cell will be increased. However, a balance must be found in order to avoid the interference that could occur between neighboring clusters. This interference is produced by the small size of the clusters (the size of the cluster is defined by the number of cells per cluster). The total number of channels per cell depends on the number of available channels and the type of cluster used.
1 As of May 2001