ifference depending on the transmission rates. When assuming the same Eb/No for all rates, e.g. the overhead for 384 kbps does not exceed 6% of the total power in the DPCCH if we the define DPCCH overhead as 1010g10(1+10 (DPDCH - DPCCH) Thus, when looking at the power differences for the reference service rates, logically we can conclude that to support 384 kbps we will need a denser site deployment than we would for 144 kbps. Relative Transmission Power Distribution 12.2kbps 144kbps 384kbps 1024kbps Overhead [dB] DPCCH [dB] DPDCH [dB] Figure 7.8 DPCCH/DPDCH and overhead power distribution. In particular this applies to higher rates in data packet transmission. The UMTS Network and Radio Access Technology Other factors having impact on the uplink Eb/No values are: multi-path diversity, macro- diversity gain, advanced BS signal processing techniques, and receiver antenna diver- sity. In the first case, when looking at characteristics of the reference multi-path channels in Chapter 2, we see that the vehicular channels have more taps that those for the pedes- trian ones. More taps implies higher multi-path diversity gain and thereby larger cover- In the second case, in the absence of high multi-path diversity gain during soft hand- over, i.e. when the MS receives a signal from at least two BSs, the probability of accu- rate signal detection increases resulting in higher micro-diversity gain. Better baseband processing, e.g. adaptive filters for fading environments will improve error rates and thereby lower Eb/No values, which in turn will increase coverage. Finally, through antenna diversity techniques we can also get a coverage gain of 2- 3 dB. For example, transmit diversity can use two independent transmit paths from the base station to the mobile, in order to mitigate the effect of fading. The two paths may come from using two spatially separated antennas, or by using the two orthogonal po- larizations of one cross-polarised antenna [5,6]. On the uplink, two-branch diversity combining or Maximal Ratio Combining