Low-Latency Wireless LAN System using Polling-Based MAC

A low-latency, low-error-rate wireless architecture with the hybrid coordination function controlled channel access (HCCA) technique of IEEE802.11e for industrial applications such as video monitoring systems and control applications in plants and factories is studied. The proposed HCCA technique enables dynamic scheduling in response to changes in the conditions of radio links, thus achieving deterministic latency communications under unstable radio link conditions. The communication performances were analyzed by computer simulation. Performance evaluations with a prototype in which the proposed scheme was integrated demonstrate that the proposed system can achieve a low latency of 50 ms and a low error rate of less than 10-6 in video transmissions in radio environments where other conventional wireless LAN systems coexist.