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High-Speed Uplink Packet Access (HSUPA) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 5.76 Mbit/s. The name HSUPA was created by Nokia. The official 3GPP name for 'HSUPA' is Enhanced Uplink (EUL).〔(3GPP specification: 25.321 )〕 The specifications for HSUPA are included in Universal Mobile Telecommunications System Release 6 standard published by 3GPP. – "The technical purpose of the Enhanced Uplink feature is to improve the performance of uplink dedicated transport channels, i.e. to increase capacity and throughput and reduce delay." ==Description== HSUPA uses an uplink ''enhanced dedicated channel'' (E-DCH) on which it employs link adaptation methods similar to those employed by High-Speed Downlink Packet Access HSDPA, namely: * ''shorter Transmission Time Interval'' enabling faster link adaptation; * ''HARQ'' (hybrid ARQ) with ''incremental redundancy'' making retransmissions more effective. Similarly to HSDPA, HSUPA uses a ''packet scheduler'', but it operates on a ''request-grant'' principle where the UEs request a permission to send data and the scheduler decides when and how many UEs will be allowed to do so. A request for transmission contains data about the state of the transmission buffer and the queue at the UE and its available power margin. However, unlike HSDPA, uplink transmissions are not orthogonal to each other. In addition to this ''scheduled'' mode of transmission the standards also allows a self-initiated transmission mode from the UEs, denoted ''non-scheduled''. The ''non-scheduled'' mode can, for example, be used for VoIP services for which even the reduced TTI and the Node B based scheduler will not be able to provide the very short delay time and constant bandwidth required. Each MAC-d flow (i.e. QoS flow) is configured to use either ''scheduled'' or ''non-scheduled'' modes; the UE adjusts the data rate for ''scheduled'' and ''non-scheduled'' flows independently. The maximum data rate of each ''non-scheduled'' flow is configured at call setup, and typically not changed frequently. The power used by the ''scheduled'' flows is controlled dynamically by the Node B through absolute grant (consisting of an actual value) and relative grant (consisting of a single up/down bit) messages. At the Physical Layer, HSUPA introduces new channels E-AGCH (Absolute Grant Channel), E-RGCH (Relative Grant Channel), F-DPCH (Fractional-DPCH), E-HICH (E-DCH Hybrid ARQ Indicator Channel), E-DPCCH (E-DCH Dedicated Physical Control Channel) and E-DPDCH (E-DCH Dedicated Physical Data Channel). E-DPDCH is used to carry the E-DCH Transport Channel; and E-DPCCH is used to carry the control information associated with the E-DCH. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「High-Speed Uplink Packet Access」の詳細全文を読む スポンサード リンク
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