Moving towards HSUPA (high speed uplink packet access): a complete 3.5G wireless system

Current 3G systems do not provide the much needed throughput for high data rate applications. To enhance downlink performance, high speed downlink packet access (HSDPA) technology is introduced which is often referred as a 3.5G system. HSDPA relies on a new downlink shared channel HS-DSCH. Enhancement in the downlink is considered assuming that for most of the applications, e.g., surfing, data download, etc; downlink traffic is far greater than uplink. HSDPA provides high throughput in downlink but uplink data has a limitation in 3G systems. For some applications, like video telephony, data flows equally in both directions. Thus, enhancement of uplink capability is a key to make a complete 3.5G system. High speed uplink packet access (HSUPA) is a technology being considered for this purpose. This paper discusses in detail the various technological aspect of HSUPA. Changes required in UMTS node B and UE to support HSUPA are also discussed.