Qualcomm Inc (QCOM)

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HSDPA gets 3G up to speed
by Ian Poole
Thursday 13 October 2005
High speed downlink packet access technology is giving 3G networks the speed of CDMA systems, says Ian Poole

http://www.electronicsweekly.com/Articles/2005/10/13/36550/HSDPAgets3Guptospeed.htm

No sooner had 3G mobile phone networks started to roll out than there was the promise of even higher speeds with HSDPA (high speed downlink packet access). Using this, 3G is better able to compete with the speeds being offered...

Article Continues Below... by other cellular systems such as cdma2000 used elsewhere around the globe, and it is also better able to meet the expectations of those who have become accustomed to high data speeds offered by Wi-Fi and ADSL.

Now, after the development of the standards, operators are beginning to release information about launch dates for services. Cingular in the US announced its first HSDPA networks will be in operation in late 2005, and T mobile has announced its intention to launch services in Austria and Germany in 2006. Also mobiles are beginning to appear on the market, now that silicon manufacturers have brought their products to market.

Higher speeds

Currently the networks that are being rolled conform to the Release 99 version of the UMTS standard, and this offers a maximum data rate of 2Mbit/s, although current networks are only able to provide speeds of 384kbit/s. The following release of the standard was Release 4 and this reflected a number of updates to the network. However, it was within Release 5 of the standard that the features for HSDPA were included.

Using HSDPA the maximum capability has been raised to 14.4Mbit/s on the downlink from the base station or Node B to the mobile or user equipment (UE). Although this requires sharing between users, and it is dependent on channel usage and factors such as the radio conditions, the overall data rate achievable will be much higher. This will enable many new features to become faster and more accessible, thereby bringing higher revenue levels to the operators.

Silicon

HSDPA mobiles have just started to reach the market in advance of some of the networks going live. LG has announced a mobile using a Qualcomm chipset. However, Freescale has also brought its offerings to the market. The first was the i.300 platform which sampled in the first quarter of 2005.

It is now being shipped and used by several mobile manufacturers. This platform is being been further developed as the MXC 300. This will be sampled in the 4th quarter of 2005 and it adopts a single core modem architecture and a protocol enhancement which allows the entire protocol stack to be run on a single processor rather than using the conventional approach that splits the protocol stack across the DSP and conventional processor.

John Diehl, director and general manager, platforms division at Freescale, says: “The Freescale HSDPA platforms are delivering such a level of integration that our customers can utilise a ten times increase in data rate for less than a five per cent increase in silicon area.”

Different services require different speeds. As a result, Release 5 specifies 12 categories of downlink speeds for end user devices. This wide range of speeds gives device manufacturers more leeway to use different combinations of scheduling and tolerance to the radio channel conditions to achieve various data rates. Both the i.300 and the MXC 300 support 3.6Mbit/s (the first HSDPA category being rolled out), and it is anticipated that Category 8 (7.2Mbit/s) and category 10 (14.4Mbit/s) will be supported during 2007.

Apart from the silicon and the phones themselves, developments have been ongoing in other areas to ensure that services operate correctly when the updates to the networks are rolled out. Conformance testing is one such area. The GCF (Global Certification Forum), the body that oversees the certification for UMTS and also for GSM, will see test cases submitted for approval for HSDPA in October this year.




Aeroflex will be submitting its test cases that will be fully Release 5 compliant (pictured above). Phil Medd, product manager for Aeroflex, says: “This represents a major step forwards and has helped move forwards the introduction of the test cases in a timely fashion.”

Having the test cases available will enable the new mobiles hitting the market to be fully tested and certified prior to their release. With the complexity of 3G, and the very high customer expectations arising from the current reliable 2G services that are offered this is particularly important.

Next steps

With HSDPA now becoming a reality, the next step is HSUPA (high speed packet uplink). This enhancement, which is part of Release 6 of the standard is expected to start roll out in 2007. The release was “frozen” in March of this year, enabling developers to move ahead with their programmes knowing that only minor changes and clarifications would be made.

The introduction of HSUPA will help applications that require a more symmetric balance between the uplink and downlink. Accordingly new applications such as IMS (IP multimedia services) can be accommodated more easily. Apart from this it will have advantages for other non IMS applications, including basic functions such as transferring or emailing large files.

The upgrades to networks to provide the new high speed services can be achieve relatively easily as it is essentially a software change. In this way it is a particularly cost effective option for network operators. For the end user a new mobile is needed, although this is not a major problem as most people upgrade their mobiles relatively frequently. Accordingly it should be possible for the take up of the new services to be quite fast, allowing operators to see a return on their investment.