n the maximum air interface throughput and Iub efficiency. If lub is dimensioned to support peak rates in the air interface, the lub efficiency will be low, but as the lub is dimensioned to support the average cell capacity, the peak throughput at the air interface may by limited by the Iub. Typically the average throughput criteria plus a certain margin would be defined. It is important to note that the capacity available for HSDPA can be obtained after considering first the capacity needed for DCH, voice calls and signalling. RNC Configuration Typically the operator needs to define the number of RNC locations or how the Node Bs are distributed under different RNC sites. Different requirements need to be considered when deciding the number and configuration of the RNCs, i.e. the total traffic in the area, lub connectivity and limitation of the number of sites/cells. B.5.3 HSDPA Planning HSDPA performance mainly depends on radio propagation and C/I conditions. Network planning needs to guarantee that the minimum criteria are fulfilled to ensure the required performance. As part of the planning, the planner should try to ensure clear cell dominance areas and minimise the SHO areas and interference from neighbour sites. Figure B.9 shows an example of the planning process for HSDPA on a network where WCDMA has already been implemented. In the first place, the R99 network (NW) should be monitored SO that current traffic can be analysed. The average BTS power used, BTS load, RNC utilisation, lub utilisation HSDPA Planning and Dimensioning Analyse R99 NW HSDPA Performance Node B, lub, RNC performance Target config Performance HSDPA Parameter Monitoring Planning Figure B.9 HSDPA planning process and SHO overhead should be considered. This is similar to the first phase of the dimensioning analysis. HSDPA performance target and strategy should be considered in conjunction with the load information to estimate the actual capacity needed. From the coverage point of view, there are different strategies that the operator can 