Performance analysis of the GSM signalling protocol LAPDm

The increasing user demands on mobile networks with regard to the integration of services and availability of supplementary services lead to an increasing importance and complexity of signalling protocols. Especially the efficiency and robustness of signalling protocols at the (GSM) air interface must be seen as one of the critical parts in the process carrying out user requests within an acceptable time space and have to be improved simultaneously with data transfer protocols. This paper describes the impact of LAPD_m protocol on the chronological sequence, duration and successful implementation of the signalling phase. A simulative performance evaluation based on a formal protocol specification in SDL has beers carried out for different radio conditions. Especially the influence of modified protocol parameters and different channel allocation strategies have been examined, compared and evaluated