What is High Speed Uplink Packet Access(HSUPA) or 3.75G and what is the Difference between HSDPA and HSUPA?

By | July 23, 2011

High Speed Uplink Packet Access (HSUPA) also known as 3.75 G (3.75 generation of wireless telecommunication technology) is a protocol which aims at providing higher uplink speed equals to 5.8 Mbps. HSUPA is related to group of protocols from HSPA (High Speed Packet Access) as defined by 3GPP (3rd Generation Partnership Project).HSUPA protocol name is baptized by nokia however 3rd Generation Partnership Project(3GPP) calls it as Enhanced Uplink (EUL).Working of HSUPA is similar as that of HSDPA with the only difference that HSDPA protocol provides high speed of downlink and HSUPA protocol improves the uplink speed by increasing the throughput , capacity and decreasing delays. HSUPA works on request grant principle in which user will seek permission from scheduler to transmit data (data is send in packets), scheduler then decides at what time the user can send data and number of users who will be permitted to send data. HSUPA permits non-scheduled modes. In non-scheduled modes the users can self-initiate transmission like Voice Calls or Multi-media sessions. HSUPA introduces a new channel named as Uplink Enhanced dedicated channel (E-DCH) which uses link adaptation methods like Shorter Transmission Time Interval results in faster link adaptation and Hybrid automatic repeat request (HARQ) results in effective retransmissions. Using these techniques the mobile phone and network can communicate at faster speed. HSUPA also has a new feature called as multi-code transmission; using this feature the user can find increase in the uplink speed. HSUPA includes new channels like F-DPCH (Fractional-DPCH), E-AGCH (Absolute Grant Channel), E-DPCCH (E-DCH Dedicated Physical Control Channel), E-HICH (E-DCH Hybrid ARQ Indicator Channel), E-DPDCH (E-DCH Dedicated Physical Data Channel) and E-RGCH (Relative Grant Channel). E-DPDCH (E-DCH Dedicated Physical Data Channel) carries the E-DCH Transport Channel whereas E-DPCCH (E-DCH Dedicated Physical Control Channel) transmits theĀ  information concerning to E-DCH.

What is the difference between HSDPA and HSUPA?

  • HSDPA improves the speed of downlink data transmission.HSUPA improves the speed of uplink data transmission.
  • In HSDPA code space and the transmission power are the shared sources which are controlled by Node B.In HSUPA the amount of allowed uplink interference is the shared resource.The amount of allowed uplink interference depends on the transmission power of the individual User.
  • In HSDPA the scheduler and the transmission buffers are part of the same node therefore buffer status gets updated automatically.In HSUPA the scheduler and the transmission buffers are allotted to different user therefore the User (User Equipments) needs to inform the scheduler at Node B about the buffer status.
  • Adaptive Modulation is not supported by HSUPA. It only supports BPSK modulation scheme.Adaptive Modulation is supported by HSDPA.
  • Using HSDPA we can listen to music online, watch videos, downloading files, can do internet browsing and much more at lightning fast speed.Using HSUPA we can upload files or seed files in a file sharing network, send emails with large attachments within few minutes.
  • Generally we do more of downloading as compared to uploading so more bandwidth is allocated to HSDPA as compared to HSUPA.
Comments
  • Karan November 29, 2013 at 4:20 am

    Great document indeed .. Can somebody tell me why F_DPCH information goes in common e_dch information when the UE state is CELL_FACH in case of SIB5 ? What’s the dependency of HS_UPA on F_DPCH ? and how will F_DPCH be used in case common UL transport channel E_DCH is being used ? Yours answers would be of great help to me.

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