HSDPA (High Speed Downlink Packet Access) is an enhancement to W-CDMA, a technology that is also referred to as UMTS, the 3G path chosen by most GSM operators around the world. Today, there are already some 75 UMTS networks in operation around the world. Globally, many UMTS operators are planning on the HSDPA upgrade, and operators that have not deployed UMTS yet are likely to go directly to HSDPA. (Ed’s Note: We’ve been following the evolution to next-gen high-speed mobile for at least 18 months now. Google WWJ for more on this topic.)
In the United States, Cingular (via its purchase of AT&T Wireless) has UMTS available in six cities. However, the company is planning an aggressive deployment of HSDPA, with 15 to 20 cities planned by the end of 2005 and most major metropolitan areas by the end of 2006. The six cities with current UMTS service will be upgraded to HSDPA as well.
HSDPA is important for operators because current UMTS technology, which based on 3GPP WCDMA Release 99 specifications, is extremely efficient for voice service, but it is not optimized for data services. The HSDPA upgrade, based on 3GPP Release 5 specifications, keeps the same voice mechanisms but adds highly efficient data capability. It does this through radio mechanisms such as higher order modulation (16QAM in addition to QPSK), improved error correction, dynamic adaptation of modulation and coding based on radio conditions, and a tighter link between mobile and base station. It also adds a packet scheduling approach that favors downlink transmissions to users with the best radio conditions, thus allowing them to receive data at higher throughput rates. Since conditions vary by users over time, this results in what is called user diversity. All these approaches working in combination result in at least a doubling of spectral efficiency, and with later improvements on the roadmap, a further doubling. Bottom line: The network can support many more users at a higher speed. Continue
[Eds Note] A good read for primer, however it has no mention of progress the device side. While we hear that Fujitsu, NEC and Panasonic are field testing HSDPA units in Tokyo and DoCoMo has pushed the roll-out back until Q4, it would be interesting to find out where the over-seas handsets (or they will only have PCI data cards) are coming from.. and maybe ‘when’ too?!?