ESTIMATION OF RADIO CHANNEL BIT ERROR RATE IN A DIGITAL RADIO TELECOMMUNICATIONS NETWORK

A system for determining when a radio telecommunications network should swit ch between a first grade of service and a second grade of service based upon a highly accurate and reliable estimate of the b it error rate BER. The system estimates (65) the BER on an uplink and a downlink on a user channel, and determines (66) whether the BER on the uplink and the downlink on the user channel are below a first set of thresholds. The system then measures the residual SFET RBER and the frame erasure rate FER on the voice channel uplink, and determines (74) whether the downlink BER, the uplink RBER, and t he uplink FER are lower than a second set of thresholds. If lower, the system sends and receives a data message on a Fast Associated Control Channel (FACCH). The system obtains a highly accurate estimate (83) of the BER on a downlink on the FACCH channel, and reports (88 ) the downlink BER in a message on the FACCH channel uplink. The system then estimates the BER on the FACCH channel uplink. Finally, the system switches the radio telecommunications network from the first grade of service to the second grade of service in response to determining that the uplink and downlink BER on the FACCH channel are below a third set of thresholds.