4g could hit home at 120Mbit/sec

Mobile phone operators could introduce 4g links offering links of upwards of 120Mbit/sec via home femtocell base stations.

The 4g technology is known as Long Term Evolution (LTE) but looks like become shorter term as the industry consolidates around it in the face of potential competition from Wimax.

China Mobile, Verizon have all said at Mobile World Congress that they will support LTE. Vodaphone said it planned a rollout by 2010.

Giants Alcatel-Lucent and NEC announced a joint venture to pool existing R &D resources and deploy LTE as soon as next year. The technology will build on existing 3g infrastructure.

Intel has teamed up with Pipex in Britain to form a company called Freedom4, which has begun rolling out the technology. Wimax is scheduled to be implemented on motherboards using the company´s new low-drain Menlow platform later this year.

But Intel people here seem to be rather more muted about Wimax that in the past. One spokesman on the stand, where mini-PCI cards supporting both Wifi and Wimax were one show, said it was possible that the two technologies might converge.
Vodaphone chief executive Arun Sarin said WiMax should be “harmonised” with LTE.

Both Wimax and LTE use similar Orthogonal Frequency Division Multiplexing (OFDM) technolog. Reference designs on show here support both using the same hardware on a single board, with the Wimax and LTE layers all done in software. Most of the companies developing LTE also offer Wimax.

Chinese giants Huawei and ZTE are both demonstrating LTE links capable of 120Mbit/sec using 20MHz channels, or 60Mbits using 10MHz. This is the data rate per base station and does not mean users will get that speed.

But they could if the technology is rolled out using femtocells. A design on show here used hardware from Bath-based PicoChip, with software developed by the German company Mimoon.

Mimoon development engineer Karsten Alecke said the aim was to create a femtocell supporting Wimax or LTE costing less than $100. “It could replace Wifi in the house. You would need only one box,” he said.

The advantage of femtocells for cellular operators is that they make best use of expensive spectrum, massively increasing the maximum user density. They also offload the ´backhaul´ (the link from the base station to trunk lines) to the host home´s service provider – though that leaves the thorny question of who will pay for that bandwidth.

Femtocells would mean that home users, apart from getting better cellphone coverage, would have access to the entire bandwidth of the base station, allowing faster data rates.

Links within the home, currently perhaps supplied by Wifi, might be free, depending on the operator´s business model. But the operator has to make it worth while for a household to opt into the system.