Random access scheme for communication system

This invention discloses a random access method, in which access point AP can dynamically adjust the number of random access channels of the next frame according to the condition of network load reflected by the access channels and broadcast through downlink public control channels. When the request for the occurrence of group collision needs repeated access mobile terminal MT, utilizing binary index retreat algorithm, dynamically expends size of competition window, and according to down public control channel published random access channel number, successful access request number and MT service access priority level, real-time refreshes sending probability to reduce repeated collision probability. At circumstance of low or high network load, the invention can increase random access probability of success, and reduce access time delay, and provide better service Qos for high-level user.