In the mid-1980s voice calls were the most important service in fixed and wireless networks. This is the reason why GSM was initially designed and optimized for voice transmission. Since the mid-1990s, however, the importance of the Internet has been constantly increasing. GPRS, the General Packet Radio Service, enhanced the GSM standard to transport data in an efficient manner and enabled wireless devices to access the Internet. With Enhanced Datarates for GSM Evolution (EDGE), further additions were specified to improve speed and latency. The first part of this chapter discusses the advantages and disadvantages of GPRS and EDGE compared to data transmission in classic GSM and fixed-line networks. The second part of the chapter focuses on how GPRS and EDGE have been standardized and implemented. At the end of the chapter, some applications of GPRS and EDGE are discussed and an analysis is presented on how the network behaves during a web-browsing session.
As discussed in Chapter 1, the GSM network was initially designed as a circuit-switched network. All resources for a voice or data session are set up at the beginning of the call and are reserved for the user until the end of the call, as shown in Figure 2.1. The dedicated resources assure a constant bandwidth and end-to-end delay time. This has a number of advantages for the subscriber: