Vodafone CTO has high hopes for carrier aggregation

The availability of devices, especially tablets, will now decide when the technology is rolled out on a larger scale

Tests of carrier aggregation, a technology that will help increase the speeds of LTE networks, have been a positive surprise, but another technology called small cells needs to become more mature before it can help offload mobile networks, according to two executives at Vodafone Germany.

Growing data volumes and the need to become more flexible have operators looking at multiple technologies to improve their networks, and Vodafone in Germany is at the forefront of testing many of these, including carrier aggregation and LTE broadcast.

Last year, the operator was one of the first to announce tests of carrier aggregation with a theoretical download speed of 225Mbps (bits per second). The technology, which is part of LTE-Advanced, allows networks to devote more resources to some users by treating two or more channels in the same or different frequency bands as if they were one.

Vodafone's test used one 10MHz andA one 20MHz channel for up to 225Mbps.

"We were pleasantly surprised, it was much more stable than we had thought," said Eric Kuisch, chief technology officer at Vodafone Germany.

The test, which was conducted with Huawei Technologies, showed that the network could deliver speeds over 200Mbps per second over a longer period and not just during short peaks. When further away from the base station, speeds were still at between 140Mbps and 180Mbps.

The next step will be to test how the technology can cope with a larger number of different kinds of devices.

The availability of products with carrier aggregation, especially tablets, will decide when Vodafone can roll out the technology on a larger scale, according to Kuisch. With an LTE tablet with carrier aggregation, users will be able to use video services with better quality and that will help drive interest, he said.

Kuisch didn't want to specify when the tablets would arrive, and open the door for a commercial launch, but it can't be too far off into the future. At last month's Mobile World Congress, Intel said that the first products based on its XMM 7260 modem would arrive by the end of June. At the conference, Qualcomm and Samsung also showed a specially modified Samsung Galaxy Note 3 smartphone that was capable of speeds up to 300Mbps, with a version of carrier aggregation that used two times 20MHz of spectrum.

Another technology Vodafone Germany is at the forefront of testing is LTE broadcast. This time working with Ericsson, Vodafone has put the technology through its paces at a soccer stadium.

"Massive simultaneous usage has always been an issue in mobile networks," Kuisch said.

With LTE broadcast, Vodafone is hoping to address that challenge. It lets multiple users receive the same content simultaneously without straining the network, which is useful in places such as airports and sports arenas, according to Kuisch.

"There it has the potential to improve the customer experience tremendously. But we need to do a little more research on what information will be broadcast," Kuisch said.

LTE broadcast is somewhere in the middle between the lab and a commercial roll out, but the advantage is that it there is already a real-world need for the technology, according to Kuisch. That isn't always the case as the telecom industry develops new technologies.

"The other thing we need to find out is the economics. Where do we need to build it, because it is not something you do nationwide. That would be silly," Kuisch said.

The test Vodafone Germany announced last month has been extended and expanded.

Using more spectrum is the most straightforward way of increasing speeds in a mobile network. Another slightly more complicated upgrade path is adding Wi-Fi as well as smaller base stations or so-called small cells to offload existing mobile networks.

"Small cells is a buzzword. The challenge is going to be to find the right balance when you move traffic between Wi-Fi, the macro network and your small cells. It is possible, but it's quite complex," said Arash Ashouriha, chief network officer at Vodafone Germany.

For this to work, moving between the different networks has to be seamless to the user, and today that isn't the case, according to Ashouriha. The operator is working with both suppliers and some third-party application vendors on what could be the best way to make the switch between networks unnoticeable, he said.

"Small cells will be ready for mass roll outs sometime in the beginning of next year," Ashouriha said.

One of the hottest topics at Mobile World Congress was NFV (Network Functions Virtualization), which will allow operators to get many of the same advantages that server virtualization has provided enterprises, including lower costs and the ability to roll out new services faster using NFV.

"I think it's a blessing," Kuisch said.

Having to install new hardware with integrated software when a network needs to be upgraded is a really prehistoric way of working, according to Kuisch. It costs a lot of money and has a negative impact on the environment.

"Network Functions Virtualization will give us the possibility to minimize the impact on society and also on our own resources," Kuisch said.

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