Quality of Service

High Speed Downlink Packet Access (HSDPA) is a packet-based data service in W-CDMA downlink with data transmission up to 8-10 Mbps (and 20 Mbps for MIMO systems) over a 5MHz bandwidth in WCDMA downlink. HSDPA implementations includes Adaptive Modulation and Coding (AMC), Multiple-Input Multiple-Output (MIMO), Hybrid Automatic Request (HARQ), fast cell search, and advanced receiver design.

In 3rd generation partnership project (3GPP) standards, Release 4 specifications provide efficient IP support enabling provision of services through an all-IP core network and Release 5 specifications focus on HSDPA to provide data rates up to approximately 10 Mbps to support packet-based multimedia services. MIMO systems are the work item in Release 6 specifications, which will support even higher data transmission rates up to 20 Mbps.

HSDPA is evolved from and backward compatible with Release 99 WCDMA systems.

QoS Architecture

There are four different QoS classes:
· conversational class
· streaming class
· interactive class
· background class

List of UMTS Bearer Service Attributes:
· Traffic class ('conversational', 'streaming', 'interactive', 'background')
· Maximum bit rate (kbps)
· Guaranteed bit rate (kbps)
· Delivery order (y/n)
· Maximum SDU size (octets)
· SDU format information (bits)
· SDU error ratio
· Residual bit error ratio
· Delivery of erroneous SDUs (y/n/-)
· Transfer delay (ms)
· Traffic handling priority
· Allocation/Retention Priority
· Source statistics descriptor ('speech'/'unknown')SDU = Service Data Unit


Further reading: 3GPP 23.107