The potential for femtocells has been with us for a few years now, but few have been put into service. Sprint has had them for over a year, but so far AT&T and Verizon haven’t done much other than implement field trials. T-Mobile isn’t likely to offer them, as its equivalent @Home system implements the Universal Mobile Access (UMA) standard, which lets home users talk through their Wi-Fi enabled cell phones using Voice over Internet Protocol (VoIP) by way of their Wi-Fi home network and broadband connection.

Yet we can almost certainly predict that we will see femtos offered to home cellular subscribers in the near future. Though we initially thought of them as consumer home products, femtos will also find a place in the enterprise where increased data applications are being used and network congestion is occurring.

Texas Instruments is certainly making it easier than ever to offer a femtocell unit for 2G/3G and even 4G systems using GSM, CDMA, WCDMA, TD-SCDMA, WiMAX, and Long-Term Evolution (LTE) thanks to its latest DSP family. The TMS320TCI6485 and TMS320TCI6489 both serve as the baseband component of a femtocell. External transmitters and receivers are needed as well as some DDR2 RAM.

Targeting residential applications, the TCI6485 includes two of TI’s well-regarded 850-MHz C64x DSP cores. Supporting eight home users simultaneously, it delivers HSDPA connectivity with up to 15-Mbit/s downlink and 5.7-Mbit/s HSUPA uplink data rates. The cell size is less than 100 m. It includes all L1, L2 and L3 processing functionality. Designed for enterprise femtocells, the TCI6489 is similar but includes three 64Cx DSP cores. It can handle 32 users simultaneously using the same HSPA specs mentioned above. The cell site coverage area is less than 200 m.

The cores include L1 data memory, L1 program memory, and the rake search algorithm (RSA). L2 memory is also provided for each core, with 2 Mbytes for the TCI6485 and 3 Mbytes for the TCI6489. The TCI6489 has four lanes of antenna interface that comply with the CPRI/OBSAI basestation standards to connect to the analog front end for multiple-input multiple-output (MIMO) use.

Also, the cores include the Receiver Accelerator Coprocessor (RAC) used in UMTS phones, a Viterbi coprocessor (VCP2), and a turbo coprocessor (TCP2) to help reduce the load on the DSP. The TCI6485 has two lanes for the antenna interface but is otherwise similar. There’s lots of I/O, including a Gigabit Ethernet port, a buffered serial port (McBSP), a DDR2 interface, and the FSync for frame synchronization. GPIO and I2C are provided as well.

These chips come with mimoON’s Layer 1 (PHY) as defined in Release 6 of the 3GPP specifications with migration path to R7 and R8. This software leverages TI’s WCDMA functional libraries and on-chip accelerators for optimal performance. It’s provided in higher-level language with modules that can be customized and expanded. Multiple MIMO configurations are also available.

Another software feature, Continuous Computing’s comprehensive protocol stack for Layers 3 and 3, is optimized for improved data and control plane performance aligned with HSPA, HSPA+ and LTE latency. It also provides an easy migration path to these advanced technologies and standards.

The TCI6485 and TCI6489 will be sampling in the third quarter of 2009. Production will begin in the fourth quarter of 2009. A reference design will be available in the fourth quarter as well.