h uses up some of the capacity of a CDMA system, are taken into account and it appears that cdmaOne has a capacity improvement of around 30 per cent. While much smaller than the original figures seemed to indicate, it is still very important when the level of calls that can be carried represents the earnings that can be made by the telephone company, and a figure of 30 per cent is very significant. Another of the advantages of CDMA is that new cells can be added relatively easily without the need for a considerable amount of frequency Cellular telecommunications 273 planning. By adding new cells, further capacity is gained, albeit at the expense of additional interference because there are more mobiles and base stations that can interfere with one another. Although there is a loss of capacity in each cell, there are more cells and this brings an overall improvement in capacity, often by as much as 15 additional channels for the addition of a new base station. Fortunately by tailoring the antennas in each base station to provide the required coverage it is possible to limit the levels of overlap in the cells, and thereby reduce some of the causes of interference. CDMA2000 CDMA2000 was devised in response to the effort to generate a global third generation mobile telecommunications system. While there are three main 3G standards that can be used, CDMA2000 has the advantage that it provides a full evolution from IS-95 (cdmaOne) through to the full high data rate 3G service. In this CDMA2000 the main evolution points are a progression from cdmaOne to the CDMA2000 1X, then 1xEV-DO (Evolution Data Only) and then 1xEV-DV (Evolution Data and Voice). The last two evolutions, i.e. EV-DO and EV-DV, are sometimes col- lectively referred to as CDMA2000 1xEV. The various CDMA2000 systems will be described in the order of their evolution, showing the various additions and the path that their development follows. The basic CDMA2000 system is available in two configurations, namely 1X and 3X. The 1X variant was first launched in 