12
High-Speed Downlink Packet Access
12.1 Introduction
This chapter presents High-Speed Downlink Packet Access (HSDPA) for Wideband Code Division Multiple Access (WCDMA), the key new feature included in the Release 5 specifications. The HSDPA concept has been designed to increase downlink packet data throughput by means of fast physical layer (L1) retransmission and transmission combining, as well as fast link adaptation controlled by the Node B (Base Transceiver Station (BTS)). This chapter is organized as follows: first, HSDPA key aspects are presented and a comparison with Release 99 downlink packet access possibilities is made. Next, the impact of HSDPA on the terminal uplink (user equipment (UE)) capability classes is summarized and an HSDPA performance analysis is presented, including a comparison with Release 99 packet data capabilities and performance in the case of a shared carrier between HSDPA and non-HSDPA traffic. Then the link budget for both HSDPA and High-Speed Uplink Packet Access (HSUPA) is presented and followed by the Iub dimensioning example for HSDPA. The chapter concludes with a description of the Release 6 enhancements for HSDPA.
12.2 Release 99 WCDMA Downlink Packet Data Capabilities
Various methods for packet data transmission in WCDMA downlink already exist in Release 99. As described in Chapter 10, the three different channels in Release 99/Release 4 WCDMA ...
