One day all 2G spectrum will be 3G, CTO says
O2 is trialling UMTS technology at the 900MHz frequency currently used by GSM operators to carry 2G services. The trials, which are taking place on the operator’s Isle of Man network – often used to test out new technology — are designed to see how UMTS protocols and services will work at lower frequencies than the 2.1GHz currently mandated for 3G usage. Qualcomm is providing test terminals and Lucent the network infrastucture.
O2 is keen on UMTS at 900MHz because it means it can cover greater areas in a cell site, wnd also get better in-building coverage than higer frequency radio waves offer.
Dave Williams, O2’s CTO, said that the operator wanted to see if it could get an increase in coverage and in-building penetration whilst avoiding interference with other services at the frequency.
“We want to try and prove that UMTS will share the same link budget at 900MHz, and to try and prove that in a real trial,” Williams said.
Getting UMTS to work at lower frequencies with the same performance as GSM would help operators because it would mean they could cover areas without needing to site new base stations or equipment.
“What good would look like from these trials is if we get the same figures and link budget as 900Mhz. It would essentially then be an electronics upgrade to the existing base stations,” Williams said.
But Williams denied that the solution was designed to meet existing 3G license conditions.
“We’ve met those [the license conditions] in more or less every country in which we are deploying 3G,” he said.
However, the road ahead is not completely smooth for O2. There is no regulatory approval in its markets for 3G at 900MHz, or 1800MHZ for that matter. And although Williams says he thinks there will be handsets for UMTS at 900MHz by early next year, that seems aggressive.
But Williams pointed out that Cingular already has GSM and UMTS services at 850Mhz in the USA, and that the band is already standardised within 3GPP.
“This is a long term deployment effort. Years from now all 2G spectrum will be used for 3G beyond work on regualtion and spectrum. 2G spectrum will clearly be used for 3G, and different countries will take different approaches in allowing that the happen. When they do we want to make sure we’ve tested the technology,” Williams said.
In terms of the technical requirement, with UMTS requiring 5MHz carriers compared to 200KHz channel bandwidths for GSM, Williams admits the operator has some work to do in most of its territories to meet that. There is also need for some filtration to segment services, to ensure GSM and UMTS services can exist side by side in the same frequency plan.