Periodical intermittent interference suppression algorithm for 2.4-GHz-band adaptive array

The intermittent interference periodically radiated from a microwave oven degrades the performance of 2.4-GHz-band wireless LANs. We discuss the intermittent interference suppression technique using an adaptive array. We have proposed a low-cost analog beamformer called an adaptive array steered by local phase shifters (AA-LPS) which is suitable for high data rates. A null forming algorithm for the AA-LPS has also been proposed. This algorithm suppresses incoming interferences by minimizing the output power of the array. The advantage of the algorithm is that the weights are calculated using the output level of the array instead of the array input vector. To apply the algorithm against an intermittent interference, we modify the sampling timing of the algorithm. The modified algorithm samples only during the microwave active periods. A beam pattern measurement using the AA-LPS with 6 elements shows that the proposed algorithm directs a null to the microwave oven, and a throughput measurement based on the cyclic transmission of a 1500-byte packet shows that the AA-LPS can significantly improve the throughput.