Femtocell solution to public coverage woes

Lamp-posts could soon be festooned with miniature cellular basestations in a bid to fill gaps in operators' coverage maps, according to Doug Pulley, chief technology officer of chip supplier picoChip.

Femtocells are beginning to find favour as a way of guaranteeing high-quality coverage in homes and offices as the use of mobile data increases. Vodafone is pushing the idea with its Sure Signal product, and picoChip says eleven other operators worldwide are also introducing femtocell offerings. Together he expects them to ship 1.5million domestic and office femtocells this year.

Pulley has been thinking about a 'metro-femtocell', built using consumer electronics techniques but designed to achieve continuous coverage in dense metropolitan areas. He estimates that the bill of materials for an outdoor femtocell serving a 2km radius would be around five times that of a domestic version serving a 200m radius. Such metro-femtocells could be particularly attractive for future LTE services, which trade higher bandwidth for lower reach.

"It's very expensive to service the rising data burden if you just try to build basestations," said Pulley. "This would be the cheapest LTE basestation you could buy."

picoChip has added two chips to its picoXcell range, as well as a suite of HSPA+ femtocell access point software, to enable customers to build more capable femtocells supporting eight or 32 users. The software provides the core components of a 3GPP standards-defined Home NodeB.

The chips support 42Mbit/s downlink and 11Mbit/s uplink data rates, MIMO and receive diversity in order to be able to support more users in the kind of usage situations necessary for enterprise and ‘greater femto’ applications.

The software stack has been developed with Continuous Computing and includes all of the software modules needed to build a complete Home NodeB femtocell, including the RNC stack; a network synchronisation module; a security module; an operations and maintenance module; a self-organising network module; and a radio resource manager.

picoChip parts are turning up elsewhere in the femtocell market. AirHop Communications and Continuous Computing have announced a reference design, based on picoChip parts, that combines a protocol stack from Continuous Computing and self-organised networking software from AirHop.The Airhop software enables networks of femtocells to organise and reorganise themselves dynamically.

“The topic of ‘self-organised networking’ or ‘SON’ is now becoming widespread, with many vendors claiming that they have a solution,” said Manish Singh, vice president of product line management at Continuous Computing. “AirHop’s eSON helps operators by improving coverage, increasing capacity and hence reducing customer churn.”

Rupert Baines, vice president of marketing for picoChip, added: “There is immense scope to optimise the efficiency of networks with better real-time SON algorithms or cognitive radio concepts.”

picoChip and Ikanos Communications have also struck a deal to develop home gateways that integrate femtocells, xDSL modems and routers. Sagemcom is using the two companies' chips in its BroadW@ve gateway , which is currently in field trials with several service providers.

Eric Rieul, Sagemcom’s director of energy and telecom business unit, said: “Ikanos and picoChip are enabling us to quickly bring to market the next-generation of advanced femtocell gateways, which are capable of meeting our service providers’ stringent requirements.”

The gateway supports quality of service schemes to prioritise time-critical traffic, such as voice calls, over less critical data services. A single piece of management software will make it easier to provide location- and context-based femtozone services, such as security alerts and smart home control.

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