Case study

There are many custom connectivity applications which can benefit from OFDM’s superb performance in difficult radio propagation environments. One example is high-end conferencing system. This system has to provide robust wireless link for ten or more high definition audio channels in parallel, for discussion, language distribution and simultaneous interpretation. The propagation is non-line-of-sight (NLOS) with typically up to 50m range.

Solution

Bitgear’s inhouse OFDM 802.11a FPGA core is excellent base to support multiple-access on physical layer. To provide robust link, QPSK modulation is used in OFDM subchannels. Pilots are not needed for tracking, and standard scrambler / interleaver and FEC ½ setting provide necessary coding gain. Bitgear designs custom OFDM systems with implementation penalty of just 1.5dB in compare to ideal BER curves. Implementation is performed on Xilinx low-cost FPGA, with hardware-in-the-loop iterations to fine tune equalizer and automatic gain control of the design integrated in the RF system.

Added Value

• Custom receivers design based on OFDM inhouse FPGA core
• FPGA implementation
• Hardware integration