Cisco Technology, Inc.

Vincent K Jones Iv

James M Gardner

Gregory G Raleigh

Alireza Raissinia

Derek Gerlach

Systems and methods for optimally combining signals from multiple antennas to ameliorate the effects of noise and/or interference on OFDM communications are provided. In one embodiment, an initial spatial statistical characterization of interference and/or noise is based on training symbols received via each antenna. Because the transmitted values of the training symbols are already known, there is no need to estimate their transmitted value to form this initial statistical characterization. The data symbol values received via the multiple antennas are combined based on the initial spatial statistical characterization. The result of this combination step is then used to form a refined spatial statistical characterization of noise and/or interference. The received data symbol values are then recombined based on the refined spatial statistical characterization.

OFDM interference cancellation based on training symbol interference

Systems and methods for wide frequency offset synchronization are provided. A synchronization data sequence is encoded onto a series of OFDM frequency domain bursts as interburst phase differences between training symbols included within the successive bursts. The interburst phase differences may also encode system configuration information. This technique may be used in conjunction with other synchronization techniques to greatly extend the frequency acquisition range achievable with low cost analog components.

Wide frequency offset correction using encoded interburst phase differences

Systems and methods for sharing a single decoder among data streams originating with multiple sources. Error correction coding techniques are modified to facilitate decoding of data from multiple sources multiplexed in the time domain at the decoder input. A single decoder accommodates multiple sources that have been encoded using disparate code rates. One application is an OFDM point to multipoint system.

Decoding data from multiple sources

Systems and methods for wide offset frequency synchronization in OFDM communications. Frequency domain OFDM bursts include training symbols having known transmitted values in known frequency domain positions. Received values at the known training symbol positions are correlated from burst to burst. The magnitudes are used to establish and correct small integer frequency offsets as measured in frequency domain symbol widths. The phase of the correlation result is used to determine and correct integer frequency offsets that exceed the training tone spacing. Use of the phase to correct large frequency offsets greatly extends the acquisition range required for low cost analog components.

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Redwood Shores, CA, United States of America

Vincent K Jones Iv