gradation without dependency on margins, which may lead to over-dimensioning. 7.6.7 Coverage Analysis After providing the background to calculate the Eb/No values and the link budget in the last two sections, we now look at the practical design factors having impact on coverage. Coverage may not be an issue at the introduction of UMTS in some regions, because the requirements will be gradual. However, from the service side, to back a pragmatic busi- ness case, a network will most likely start with about 50% coverage of populated areas as mentioned at the beginning of this chapter. Thus, such coverage will depend to a good degree on service strategy. From the network design side, this implies that good indoor coverage for high rate services will require dense sites in the urban areas with Deploying 3G Networks downlink limitation and less dense in rural areas with uplink limitation. The latter im- plies that coverage and capacity trade-off will go hand in hand even at the beginning of UMTS service. Here we are mainly concerned with coverage. 7.6.7.1 Uplink (UL) and Downlink (DL) Coverage DL coverage depends primarily on the load because the transmission power may remain the same despite the number of MSs active in a given BS, where all share the same power. This means that DL coverage will decrease as a function of the number of MSs and their transmission rates. The latter implies that additional power will afford better coverage for higher rates in the DL. In WCDMA higher transmission rates imply more spreading, which results in lower processing gain, thereby smaller coverage. On the other hand, higher bit rates (demand- ing more transmission power), require lower Eb/No because the extra power allows bet- ter channel estimation, thereby compensating for larger coverage. In relation physical channels, i.e. DPCCH/DPDCH, the dependency of the bit rate for Eb/No has to do with the mode of channel operation. Figure 7.8 shows that there is a difference in the power utilization for each channel; it is also an overhead d