Enhancing network quality using baseband frequency hopping, downlink power control and DTX in a live GSM network

Baseband frequency hopping in the combination with downlink power control and discontinuous transmission has been investigated as a quality improving feature in a live GSM network. Using the dropped call rate and the frame erasure rate to measure the network quality, the use of frequency hopping proves a powerful network quality enhancement feature. By optimising the frequency plan and the handover algorithm a reduction in dropped calls is achieved. Along with frequency hopping, downlink discontinuous transmission has been investigated. In this situation an increase in bad quality, partly due to the statistical inaccuracy with discontinuous transmission in GSM and maybe due to poor performance of the mobile stations, was encountered. The current status is therefore to reject the use of downlink discontinuous transmission until more information about the performance of the mobile stations is found. The combination of baseband frequency hopping and downlink power control has also been investigated. Even with a maximum dynamic range of 6 dB a large average base station transmitting power reduction is achieved. However no quality improvements in terms of dropped calls could be found.