Saturday 9 June 2007

Cellular Multi-Mode Madness












At the moment you can get most places with UMTS2100 including limited coverage on Vodafone NZ. The future looks a lot more difficult. With the Telecom announcement today NZ will be getting what is called an E-GPRS network operating at 850MHz. This will offer GSM/GPRS/EDGE. For real 3G as in HSDPA you will still need 2100MHz but as we all know this frequency is limited in what it can offer in terms of coverage and in-building penetration.



It has been rumored that Vodafone are trialling a UMTS900 network in NZ which certainly makes sense. With this 3G band Vodafone needs 60% less cells sites for the same coverage footprint currently offered on their UMTS2100 network. They can also use the same antennas and feeders currently used for GSM900 but the downside is that they will need to give up at least 2.6MHz of their existing GSM spectrum to act as a guard band between GSM and UMTS. It doesn't sound like much but it does cut into voice capacity.



UMTS900 is very new and only this year have the first tests calls been completed in Europe. Being new means a lack of devices which is a similar position Telstra found themselves in with their NextG network. NextG operates at 850MHz but this is UMTS (HSDPA) and not the same as the Telecom E-GPRS network. Same frequency different technology.



Over the last year more and more data devices have been appearing to support UMTS850. These devices are tri-mode as in they support UMTS850/1900/2100MHz so they work on Telstra (850), Cingular (850/1900) and the 'rest of the world' (2100).



In NZ Vodafone is adding a new spin by playing with UMTS900. At this stage there are no UMTS850/900/2100MHz devices and I am not sure what (if any) radio issues will be faced with building such a product. Given that UMTS900 has been trialled in Europe and that 900 is the dominant global GSM band it is quite feasible that 900/2100MHz will rule supreme with 850/1900MHZ relegated to side frequencies operating in different pockets around the world. Although, as voice usage grows carriers are running out of 900MHz spectrum. But then again they could also choose UMTS800 (not to be confused with UMTS850) and IP Wireless (the company that supplies technology to Woosh) is tinkering with UMTS450 which has traditionally been used for CDMA450. On top of that we have UMTS1700, UMTS2600, UMTS1800 and now talk of UMTS2500.




Will add some more details on this soon.


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