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HSDPA (high speed downlink packet access) is an enhancement to WCDMA that delivers a high-performance cellular-data capability. It is introduced into 3GPP as an evolution of WCDMA to handle a wide variety of multimedia services with different QoS requirements. In 3GPP specifications, there are three typical UMTS service classes, streaming, interactive and background, which can be transported over HSDPA. The most popular application of packet-switched streaming services, video streaming, is studied, and the traffic characteristics of such a service transported over HSDPA are analyzed. When a video sequence is coming, NodeB should decide how to choose the HS-DSCH (high-speed downlink shared channel) transport mode, i.e. codes, modulation and transport block size, depending, to some extent, on the traffic characteristics of this service delivered on the selected transport mode. Some answers are proposed, including the principles of choosing TBS, codes and modulation, delay and bandwidth requirement calculation, FER requirement guarantee, and so on. With these analysis results, the comparison of two transmission strategies, i.e. using a guaranteed number of codes and using the maximal number of codes, are presented. The simulations also identify these results and give the suggestion of channel bandwidth redundancy.