tailieunhanh - Enhanced Radio Access Technologies for Next Generation Mobile Communication phần 8

Enhanced Uplink, cũng đôi khi được gọi là HSUPA hoặc High Speed Uplink Packet Access, đã được giới thiệu trong 3GPP phát hành 6 (hoàn thành năm 2005) để bổ sung cho HSDPA và cải thiện hơn nữa WCDMA dữ liệu gói hỗ trợ, tập trung vào đường lên, điện thoại di động đầu cuối mạng, chỉ đạo. | EVOLUTION OF THE WCDMA RADIO ACCESS TECHNOLOGY 203 3. HSUPA - HIGH SPEED UPLINK PACKET ACCESS ENHANCED UPLINK Enhanced Uplink also sometimes referred to as HSUPA or High Speed Uplink Packet Access was introduced in 3GPP release 6 finalized in 2005 to complement HSDPA and further improve the WCDMA packet-data support with focus on the uplink mobile-terminal-to-network direction. Jointly HSDPA and Enhanced Uplink are often referred to as HSPA or High Speed Packet Access. The aim of Enhanced Uplink is to further improve the WCDMA support for packet-data services targeting - significantly improved uplink system capacity - further reduced delay latency with focus on the uplink - possibility for significantly higher uplink data rates To achieve these targets Enhanced Uplink introduces improved base-station-controlled uplink scheduling allowing for more efficient utilization of the uplink radio resources. Base-station-controlled uplink scheduling also enables the possibility to provide significantly higher instantaneous uplink data rates to a single user without the risk for system instability. With Enhanced Uplink peak uplink data rates beyond Mbps can be provided in the uplink in case of good channel conditions. In addition Enhanced Uplink also introduces support for fast Hybrid ARQ with soft combining also for the uplink. Similar to the downlink fast Hybrid ARQ with soft combining for the uplink provides both improved system efficiency and possibility for significantly reduced delay. It should be noted that a reduced uplink delay is beneficial also for downlink data transfer due to its positive impact on the overall radio-interface round-trip time. Thus the introduction of Enhanced Uplink also implies a further improvement in the WCDMA downlink packet-data performance. These techniques are introduced into the WCDMA standard as part of a new transport-channel type the Enhanced Dedicated Channel or E-DCH. In addition to a 10 ms TTI the E-DCH also supports a TTI of 2