This HSPA tutorial covers HSPA Overview, HSDPA, HSUPA, features of HSPA, HSPA channels, difference between HSDPA and HSUPA, HSPA+ features etc.
HSPA stands for High speed packet access, the standard mainly designed to support high speed data rate in the uplink and downlink. HSPA falls under categories viz. HSDPA, HSUPA and HSPA+. All the HSPA standards follow different UMTS releases. HSDPA was UMTS R5 release and supports about 14Mbps peak data rates. HSUPA was UMTS R6 release and supports about 5.76 Mbps uplink data rates. HSPA+ follows R7-R9 UMTS releases. HSPA supports spectral efficiency of about 2.9bits/sec/Hz.
As mentioned HSDPA is mainly designed for high speed data rates in the downlink mainly for internet based applications and hence the name High Speed Downlink Packet Access. As mentioned in UMTS tutorial, UMTS architecture composed of three main parts UE (User Equipment), RAN (Radio Access Network) and Core Network. In HSDPA changes are incorporated on air interface side and hence UE and RAN have been modified to take care of higher data rate requirements compare to its predecessor i.e. UMTS R99. No changes have been done on core network side.
Silent features of HSDPA
-It supports asymmetric data transfer mode
-Bandwidth is about 5MHz same as WCDMA
-Supports both voice and data applications
-Turbo coding is used as FEC technique
-Adaptive coding and modulations based on channel conditions hence achieve better data rate under good channel conditions due to higher modulation-code rate assignment.
-utilizing maximum power for transmission
-minimizing use of redundant packets (under better channel conditions) in data transfer
-HARQ support for new channels introduced at PHY layer
-12 categories are available for UE; Category 10 is most commonly which supports 14 Mbps.
In HSDPA HS-DSCH (High-Speed Downlink Shared Channel) is introduced as transport channel. This is supported by three physical layer channels viz. HS-PDSCH (High Speed-Physical Downlink Shared Channel), HS-SCCH (High Speed-Shared Control Channel), HS-DPCCH (High Speed-Dedicated Physical Control Channel). PDSCH carries user information/data. SCCH informs UE that data will be carried on DSCH. DPCCH carries ACK/NACK and CQI.
HSPA+ uses the same 5MHz band of WCDMA spectrum and hence great ease for operators. In the same 5MHz HSPA+ tries to increase data rate by using MIMO/higher order modulation techniques. Hence it roughly achieves 42.2 Mbps data rate and spectral efficiency of about 8.4 bits/sec/Hz.
The biggest achievement here with HSPA+ is that latency is reduced using a concept called CPC (Continuous Packet Connectivity). HSPA+ supports DC-HSDPA which supports dual cell or dual carrier concept where carrier aggregation of two nearby adjacent bands of 5MHz each are used for the same area of the cell to increase the performance.
HSDPA vs HSUPA-Difference between HSDPA and HSUPA
For difference between HSDPA and HSUPA refer following page,
HSDPA versus HSUPA
HSPA, HSDPA, UMTS refer following 3GPP link for detailed explanation.