Competition Awaits

Femtocells have some competition in today’s market and will see more in the future. T-Mobile’s T-Mobile@Home service provides Wi-Fi connectivity as well as VoIP over Wi-Fi for the home. Subscribers use dual-mode phones that work with the usual operator basestations but revert to VoIP over Wi-Fi when at home. Other services use this UMA technique with dual-mode phones.

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WiMAX will be a competitor too. Once this broadband wireless service rolls out, there will be dual-mode phones using WiMAX at home. Clearwire’s WiMAX Internet service can also accommodate phones for VoIP. Whether a WiMAX broadband connection would work as the backhaul for a femtocell isn’t clear yet, but it is obviously a possibility. WiMAX femtocells are another potential solution. And, the subscriber’s Wi-Fi home wireless network will compete with the femtocell for Internet access, so there’s lots of potential overlap.

The Femto Future

Femtocells are well on their way to becoming a real segment of the cellular business. Sprint Nextel’s Airave service already operates in several U.S. cities. AT&T, Verizon, and other carriers are in trials throughout the U.S. and are expected to launch services either later this year or in 2010. Multiple femtocell vendors are making it a very competitive sector. With the economic conditions as they are, though, some experts expect femto efforts to be put off until 2010 and beyond.

Texas Instruments is betting on the femto movement. Its low-power TMS320TC16484 DSP can support the MAC and PHY processing for 2G, 3G, or 4G wireless basestations. It will handle any of the wireless standards, including GSM/EDGE, WCDMA, HSPA, cdma2000 including EV-DO, and the LTE and WiMAX 4G technologies.

This chip eliminates the need for a separate RISC processor and improves the data throughput. The processor also eliminates latencies stemming from inter-processor communication and simplifies the system’s software. The TMS320TC16484uses TI’s popular TMS320C64xx DSP with on-chip L1 and L2 cache. Two turbo accelerators for the TCP are provided as well.

Depending upon the model, the wide range of peripheral interfaces includes Serial RapidIO, GMII for Ethernet, HPI, I2C, two McBSP (multichannel buffered serial ports), UTOPIA, GPIO, and DDR2 (Fig. 2). The TMS320TC16484 is made with 65-nm CMOS and runs at an 850-MHz or 1-GHz clock rate.

Percello’s PRC6000 digital baseband processor targets UMTS femtocells using WCDMA, HSDPA/HSUPA/HSPA+, or LTE. It fully complies with the 3GPP release 7 standard and features multiprocessing programmable DSPs and hardware accelerators. The PRC SoC uses external RF and memory but handles all other PHY and MAC functions. Percello also recently announced a partnership with Ubiquisys, the leading supplier of 3G femtocells.