stem Regarding interfaces GPRS model network Base transceiver station see also figure8-6 Base station controller Gateway mobile services switching center External Mobile switching centre networks network Visitor location register Home location register Authentication centre Equipment identity register Serving GPRS support node Intranet Gateway GPRS support node Internet Air interface Corporate LAN A, Abis Interfaces (GSM) SMS - Interfaces (GPRS) (IW)MSC GPRS additions to GPRS access MSC/VLR Access SMS Short message service equipment network SMS-IWMSC short message service interworking MSC Figure 13.24 An overview of the GPRS system with the new parts 13.11.3 EDGE EDGE is considered a 3 G type system. It is an extension of GPRS, and the main additions are related to the base station/base station controller part. While UMTS will utilize a new spectrum, EDGE will only be deployed in the existing frequency bands, such as 900 MHz, 1800 MHz and 1900 Mhz. EDGE is increasing the speed in the air interface through a new modulation technology with eight phases (eight-phase shift keying) Each phase represents a sequence of three bits. See Figure 13.25. Up to 384 kbit/s can be achieved when all eight time slots are used. GMSK modulation (Gaussian minimum shift keying) for GPRS offers maximum 115 kbit/s. EDGE uses the same TDMA frame structure, logical channel and 200 kHz carrier bandwidth as today's GSM networks. The base station controller needs a software upgrade from GPRS functionality, and the BTS needs EDGE-capable hardware. All other parts of the network are identical to GPRS. Also the radio planning can be maintained. No new sites are needed. Implementing GPRS caused an impact on operators, such as: packet-switched data in a cellular network new node types new business models marketing and selling new types of services pricing and charging new types of services Understanding Changing Telecommunications - Building a Successful Telecom Business Currently: EDGE: GMSK modulation 8PSK modulation (0,1,0) (0,0,0) (0,1,1) (0,