own as Enhanced GPRS or EGPRS systems. The system enables data transmis- sion speeds of up to 384 kbps to be attained. However, to achieve this it must use all eight timeslots that can each carry 48 kbps. Additionally it uses a different form of modulation to that used for GSM. Instead of using GMSK it uses 8 phase shift keying modulation (8PSK) and this enables operators to offer similar data speeds to those that will be achieved with the full 3G networks. As such it provides an evolutionary path between the second and third generation networks. Implementation requires software and hardware upgrades to the base stations themselves and to the base station controllers. New handsets are also required. cdmaOne cdmaOne is the marketing name for the system that is specified under IS95. After it was first issued the specification was updated from IS-95A to IS-95B. The original specification supported voice and data up to 14.4 kbps; the updated IS-95B specification supports data up to 115.2 kbps. Much of the way in which the system operates, and the infrastructure that is uses, is similar to GSM and will not be described again. However, the main difference is that it uses direct sequence spread spectrum in the form of CDMA as its modulation scheme. The use of different orthogonal codes (Walsh codes) provides the method of multiple access whereas GSM primarily uses TDMA and analogue systems use FDMA. It is claimed that CDMA systems provide a far more efficient use of the available spectrum than either FDMA or TDMA systems and for this reason CDMA is being widely adopted. When using CDMA, all users in the cell operate on the same centre frequency. As the different users are allocated different orthogonal codes, each mobile is able to isolate its own signal from the base station and extract the data contained within the transmission. A full description of the way in which CDMA works is given in Chapter 3 and the information will not be repeated here. However, for the system to be able to operate satisfactorily the differen