| 摘要 |
The present invention provides a method and apparatus for detecting interference in a wireless communications system. The invention compares the receiver FFT output of a received signal against known sequences such as the packet synchronization sequence, frame synchronization sequence, and channel estimation sequence. By comparing the reference signal to the known sequences, the invention estimates the instantaneous signal to noise ratio (SNR) for each tone of a wireless transmission. To improve the SNR estimate, the invention computes a weighted average across multiple OFDM symbols. The invention looks for significant increases (spikes) in the SNR as a way of distinguishing interfering signals from noise. The invention can store separate SNR estimates for each transmitter in a wireless network. One embodiment of the invention uses Viterbi branch metrics in conjunction with the estimated SNR to determine the presence of an interfering signal. If interference is detected the invention feeds the inverse of the SNR estimate into the Viterbi decoder or declares and erasure for that symbol. |
