Low-rate long-range mode for OFDM wireless LAN

摘要

A system for implementing an orthogonal frequency division multiplexing scheme and providing an improved range extension. The system includes a transmitter for transmitting data to a receiver. The transmitter includes a symbol mapper for generating a symbol for each of a plurality of subcarriers and a spreading module for spreading out the symbol on each of the plurality of subcarriers by using a direct sequence spread spectrum. The symbol on each of the plurality of subcarriers is spread by multiplying the symbol by predefined length sequences. The receiver includes a de-spreader module for de-spreading the symbols on each of the plurality of subcarriers. The de-spreader module includes a simple correlator receiver for obtaining maximum detection. The correlator produces an output sequence of a same length as an input sequence and the de-spreader module uses a point of maximum correlation on the output sequence to obtain a recovered symbol.

主权项

1. A wireless network device capable of use within a wireless network including a legacy wireless device, the wireless network device comprising:
a symbol mapper configured to generate modulation symbols, and map the modulation symbols to a plurality of subcarriers; a spreading module configured to spread the modulation symbols into a number (L) of chips, using a direct sequence spread spectrum technique; the wireless network device configured to generate a frame including a proprietary signal portion and a legacy signal portion; the proprietary signal portion encoded using the direct sequence spread spectrum technique on a plurality of subcarriers; the legacy signal portion is compatible with the legacy wireless device, the legacy signal portion including a legacy preamble instructing the legacy wireless device to set a Clear Channel Assessment (CCA) bit to a value that causes the legacy wireless device to ignore the proprietary signal portion.