Cellular success

Cambridge Consultants has designed a cellular basestation radio based on a consumer-grade handset component, to support picoChip’s reference design for the 3G femtocell market.

The radio is said to extend picoChip’s reference design for a 3G home basestation, providing developers with an low cost implementation for a global market that is expected to grow to 100 million units per annum within a few years. Femotcell products allow cellular operators to counter the competitive technologies of UMA (Universal Mobile Access) and VoWiFi (voice-over-WiFi), with the added advantage of allowing customers to use their existing standard cellular handsets.

The HSDPA/HSUPA-compatible WCDMA design is said to break new ground by adapting an IC created for low-cost/high-volume handset applications to implement the high-specification basestation radio, combined with an architectural split that exploits the very high computational performance available in the picoArray DSP device to perform the baseband and system control functions.

The resulting 3G home basestation design requires just these two major ICs – a bill of materials that meets the cost targets needed for this mass application. Alternative implementations can require more expensive carrier-class radio components, combined with processing cores based on DSP and FPGA technologies. The 3G basestation design supports HSDPA and HSUPA (high speed downlink packet access and uplink packet access) data rates of 7 Mbits/second and 2 Mbits/second respectively.

picoChip awarded the design contract to Cambridge Consultants because the product developer offered experience of designing radios for highly cost sensitive markets such as 2G, ZigBee, DECT and Bluetooth.

‘If this application is to succeed, the bill of materials has to be in the same ballpark as a WiFi access point, a market with a supplier base that has a lead of several years in driving down costs,’ said Cambridge Consultants’ Tim Fowler. ‘A novel architectural split gave us the key – allowing us to use an existing consumer IC for the radio. We believe that this design could trim a year or more off the time it would normally take OEMs to get the costs of 3G access points down to the point needed for mass roll out.’

The design is based on a commercial handset radio IC, and the PC202 picoArray – picoChip’s device targeted at high volume applications. This latter multi-core DSP incorporates an array of processors, combined with an ARM 926EJ-S processor, and other resources needed to implement a baseband processor including a cryptographic engine and turbo coding logic.

Figures from ABI Research predict that there will be 102 million home basestation, or femtocell, users worldwide by 2011. The femtocell handles cellular calls locally and traffic is then carried to the operator’s core network through broadband connections. This reduces the need for multiple handsets (or expensive ‘dual-mode’ cellular and WiFi terminals) and allows network coverage and capacity to be increased.