Saturday, 21 June 2008

WiMax and LTE backwards compatibility

Most of you must be hearing on daily basis about the race for 4G and who will reach there first and will claim the victory for the 4G post.

The competition between WiMax and LTE is really blossoming and both the camps never miss any opportunity to find a hole or negative in other. One of the major point of conflict in recent days between the two camps (WiMax and LTE) is the backwards compatibly of the two technologies.
WiMax based on the 802.16 standard could push data transfer speeds up to 1 Gbit/s while maintaining backwards compatibility with existing WiMax radios. Vendor sources, however, have expressed some scepticism about the speed with which the work can be completed (the end of 2009 is being mooted as a baked date) and the chances of maintaining backwards compatibility with mobile 802.16 technology.

What's really provoking the disbelieving chuckles are the requirement for backwards capability between current and future 802.16e offerings and the planned advanced air interface. Such disbelief is not that surprising when you think back to the recent interoperability issues between 802.16d and 802.16e

Around the same time that LTE rolls out, the Institute of Electrical and Electronics Engineers' (IEEE) 802.16m, or WiMAX 2.0, will make its way into products, analysts said. But there is not doubt in one thing though that WiMax is ahead of LTE in terms of technology as of today. Service providers with the right spectrum, available capital and access to enough sites to place base stations are in great position to take advantage of WiMAX's head start on the 4G market. Backwards compatibility is one area where WiMax heads towards a grey area whereas LTE at the same time is supposed to be very much backwards compatible. The network architecture for LTE/SAE already shows interface defined for the handover between LTE and 3G. The debate between WiMAX and LTE has become dirty when it comes to the issue of backwards compatibility.
Speaking exclusively to WiMaxVision from the WiMax Forum's member conference in Hawaii, Siavash Alamouti, CTO of Intel's Mobile Wireless Group, takes issue with a key claim made by proponents of LTE. Alamouti's argued and puts a very big question mark on LTE’s backwards compatibility claims.
Word is already out in the industry that although they welcome 'healthy' technology competition to mobile WiMAX in the so-called '4G'space, a number of misconceptions have been promulgated by some vendors, and even some analysts, about main rival LTE. Some peoples biggest gripe is LTE being perceived in some quarters as backwards compatible with 3GPP standards, from WCDMA through to HSPA+.

One of the reasons why many of the mobile giants decided to be in LTE camp is because of its claims for the backwards compatibility. But a doubt has started creeping in and some industry sources even says that they see no genuine evolution in LTE as LTE requires an entirely new RAN and system architecture to 3G, in much the same way as mobile WiMAX does.
To make an LTE device backwards compatible, you would have to add 3G modules to that device but you could do that with mobile WiMAX or in fact any other technology argues Siavash Alamouti of Intel.

My above claim is supported when I heard that Qualcomm announced in February it was expanding its device and base station chipsets to include LTE along with UMTS and CDMA2000. The chipsets will allow backward compatibility to legacy UMTS and CDMA2000 networks for carriers that deploy LTE. The new family of Qualcomm MDM9xxx-series LTE device chipsets will include:
MDM9200™ chipset designed to support UMTS, HSPA+ and LTE
MDM9800™ chipset designed to support EV-DO Rev. B, UMB and LTE
MDM9600™ chipset designed to support UMTS, HSPA+, EV-DO Rev. B, UMB and LTE

LTE, however, has made standardisation progress with the announcement by 3GPP last month that some RAN specifications have been frozen and are now under change control, but there is still some work to be done before the 3GPP Release 8 specification for LTE is finalised, probably by the end of the year.

Where WiMAX is today in 2008 I think LTE will be in late 2010 and early 2011, which is early stages, ready to deploy, but the equipment not necessarily completely interoperable. As for WiMax I expect we'll see embedded mobile WiMAX laptops coming onto the market between April and June this year.

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