 (HSDPA) as the expanded throughput solution for UMTS networks in 3GPP release 5. The objectives is to present a general overview of the main features that allow the provision of these higher throughputs, up to 14 Mbps theoretically, as well as practical limitations and resource requirements for fulfilment of the target performance. Planning and dimensioning considerations for HSDPA and the regular WCDMA network will also be pointed out. In addition, further evolution of UMTS capabilities towards HSPA (high speed packet access) will be described. Known as HSUPA (high speed uplink packet access), this 3GPP release 6 feature promises throughputs of up to 5.4 Mbps in the uplink. B.1 Introduction High speed downlink packet access (HSDPA) is an extension of the capabilities of UMTS included in 3GPP release 5, with the target of providing higher bit rates and capacity. It is also called 3.5G, with transmission rates up to 14.4 Mbps and 20 Mbps (for MIMO systems) over a 5 MHz bandwidth. HSDPA can significantly enhance downlink speeds, with average realistic throughputs of 400-700 kbps and bursts at over 1 Mbps, even in the initial stage. This dramatically improves the user experience of different applications such as web browsing, streaming or Intranet access. Also, in combination with HSUPA, it can be the driver for advance services like VoIP. HSDPA shares the spectrum and codes from WCDMA and, most of the time, only requires a software upgrade of existing UMTS R99 base stations. HSDPA offers a lower cost per bit and is mainly intended for non-real-time (NRT) traffic, but potentially allows new application areas with higher data rates and lower delay variances. The maximum number of UEs on HSDPA does in theory depend on the number of available channellisation codes for the associated DPCHs. The most critical parameter affecting HSDPA performance is the transmission power. Since the total power of the base station is shared with R99 DCH, a trade-off between HSDPA and R99 users needs to be considered. This trade-off is a