High speed downlink packet access

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High speed downlink packet access

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High speed downlink packet access

  1. 1. High-Speed Downlink Packet Access Pankaj Khodifad
  2. 2. Introduction • High-Speed Downlink Packet Access (HSDPA, also known as High-Speed Data Packet Access) is 3G (third generation) mobile telephony communications protocol in the High-Speed Packet Access (HSPA) family • Current speed is 42 Mbps(downlink), it can be increased 337 Mbps with HSPA+ 3GPP standards
  3. 3. HS DSCH For HSDPA new HS DSCH channel is added which is implemented by three new physical layer channel 1. HS-SCCH 2. HS-DPCCH 3. HS-PDSCH
  4. 4. HS-HCCH • The High Speed-Shared Control Channel (HS-SCCH) informs the user that data will be sent on the HS- DSCH, 2 slots ahead
  5. 5. HS-DPCCH • The Uplink High Speed-Dedicated Physical Control Channel (HS-DPCCH) carries acknowledgment information and current channel quality indicator (CQI) of the user • This value is then used by the base station to calculate how much data to send to the user devices on the next transmission
  6. 6. HS-PDSCH • The High Speed- Physical Downlink Shared Channel (HS-PDSCH) is the channel mapped to the above HS- DSCH transport channel that carries actual user data
  7. 7. HARQ • Data is transmitted together with error correction bits. So minor errors can thus be corrected without retransmission • If retransmission is needed, the user device saves the packet and later combines it with retransmitted packet to recover the error-free packet

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