Indoor wireless LAN access methods for factories

Access control mechanisms that can be implemented in factories, namely, random access, deterministic access, and polling access methods, are investigated. Based on the parameters for an existing mobile data communications system, the performances of the access protocols are compared in a broad sense and in terms of mean message delay performance. An indoor wireless local area network is a convenient and relatively low-cost method of communicating control information and data to and from mobile robots in a factory automation application. The random access protocols perform better in the low utilization range. The polling and deterministic access protocols perform well in the middle to high utilization range. For direct control of an autonomous robot fleet and applications with a small number of stations, the deterministic access methods prevail under the conditions studied. For a polling system, the response time is strongly dependent on the polling overhead, which is very implementation-dependent