In this press release Ericsson and Telstra (Australia) report that they have successfully tested a range update of Telstra’s W-CDMA UMTS/HSDPA network operating in the 850 MHz band to support cell ranges of up to 200 km. The press release says that downlink speeds of 2.3 MBit/s were achieved over this distance.
It would have been nice if the press release would have gone a bit more into the details of how this was achieved as that sort of range and speed can not be achieved with the typical cell site on a rooftop transmitting at 10 watts and a standard mobile phone in the hands of a user. It is more likely that a base station with high transmit power on an elevated position like a hill was used in combination with a stationary handset, power amplifier and directional antenna.
It would also have been interesting to hear some details from Telstra on where they plan to deploy this. Australia is a big country so I guess there is quite an opportunity this way to bring high speed internet to people living far away from cities where broadband Internet is available either by conventional UMTS coverage, DSL or cable. Also, this offers interesting opportunities to cover ship routes along costs.
The technical background: Looks like this is the result of Ericsson’s recent Release 7 work item in 3GPP on "Extended WCDMA Cell Range up to 200km" which was reported to completed in December 2006 in TSG#34. According to the work item, a Node-B (base station) so far was only able to report propagation delays on the random access channel in the order of 768 chips, or a range of about 60 km. The work item description further says that changing this parameter in the radio network has no impact on currently deployed terminals, hence, the measure is backwards compatible.
Note that for conventional network deployment scenarios, being able to report propagation delays for the random access channel of up to 60 km is more than enough given the fact that due to capacity reasons and propagation in urban environments, UMTS cells are usually spaced just 2 km or even less apart.