 same area covered by a GSM voice network. For CS-2, this is due to the lack of body loss in the data environment. For CS-1, this is due to the coding scheme being similar to that already employed in GSM (stand-alone dedicated control channel, or SDCCH). The coverage areas for CS-3 and CS-4 are somewhat reduced, however, due Figure 2.22 Coverage areas of coding schemes relative to CS-1 Capacity Planning to their reduced error protection and hence higher required C/I. These services will therefore typically be available closer to the cell centre. Similarly, EGPRS Modulation Coding Schemes 5 through 9 will be further reduced based on their C/I requirements. The C/I distribution (associated with frequency re-use) will determine the coverage area for the different coding schemes. In addition, new sites may be required to ensure contiguous high bit rate coverage. In many cases, EGPRS performance will be dictated more by the cell interference than by the absolute sensitivity; i.e. the network coverage is more often interference-limited than noise-limited. It is possible to estimate typical C/I distributions across a cell for a given re-use pattern. In this way, it is possible to predict the user throughput available across the cell. Under normal circumstances, the higher the re-use factor, the higher the cell C/I. Therefore, a system with more spectrum will be likely to offer higher average data rates than a system with limited spectrum. 2.5.3 Coverage Planning in WCDMA Networks The link budget calculation for the WCDMA system and coverage planning for the GSM system have already been discussed. The fundamental process for coverage planning in the WCDMA system is quite similar to that of the GSM system. However, propagation models need to be adjusted to take into consideration the WCDMA technology. The cell range R can be calculated using the Okumara-Hata or the Walfish-Ikegami models. After this, the site are a can be calculated, which is 2.6R2. However, in the WCDMA networks, some additional measurements and adjustme