Vodafone has been trial the delivery of 4G services used a combination of licensed and unlicensed spectrum. Using unlicensed spectrum to deliver 4G is controversial with unlicensed users such as Wi-Fi network owners.
There are three versions being looked at including LTE-Unlicensed (LTE-U), Licensed Assisted Access (LAA) and Wi-Fi Link Access (LTEWA). LTE-U is the most controversial as it does not implement ‘listen before talk) mechanisms to avoid interference with other signals such as Wi-Fi using the same band.
Vodafone used LAA technology for its trial. Dr Li Lin, Specialist in Mobile Access Centre of Excellence at Vodafone Group, explained the driver behind the trial in a blog published on 18 November.
He said: ‘In the last three months Vodafone customers used 400 petabytes of data on their mobile phones for the first time (enough to listen to Spotify non-stop from the Stone Age to the Space Age). In our European markets, this surge in data usage is driven by customers using on average twice as much 4G data as they did on 3G.
‘More data usage puts pressure on the licensed spectrum which Vodafone buys and so we are pleased to have become the first network in the world to successfully trial delivering LTE on a commercial network by aggregating both licensed and unlicensed bands. This technology will help us to further expand 4G capacity and improve the experience our customers have when using mobile broadband.’
The trial took place in conjunction with Vodafone Netherlands on 17 November with the support of Ericsson and Qualcomm Technologies. The test used an Ericsson RBS 6402 small cell and a test device powered by the Qualcomm Snapdragon X12 modem. The trail achieved download speeds of over 274 Mbps by aggregating 20MHZ of licensed spectrum in the 1800 band and 20MHz on the unlicensed 5GHz band.
Dr. Lin noted: ‘The unlicensed spectrum can be shared among different technologies (e.g. Wi-Fi). In the trial we were pleased that LTE achieved good co-existence with the existing Wi-Fi system.’
He continued: ‘Adding unlicensed spectrum to our existing licensed spectrum will enable us to use spectrum more efficiently and increase the capacity of Vodafone networks. The 5GHz unlicensed spectrum band, targeted using this License Assisted Access (LAA) technique, is less crowded than licensed bands, with up to 600MHz of spectrum available.
‘That means our customers would be able to download data faster, a particular benefit when undertaking demanding online activity, such as watching videos or playing games.’
He explained that Vodafone is committed to developing LAA within the 3GPP standards process and has no plan to roll out the technology in Europe until that is concluded. The LAA standards should be finalised in 3GPP Release13 in 2016.