Impact and Multiplexing of SIP Signaling in GSM

Abstract: By the introduction of IMS, future mobile voice traffic will gradually be based on IP. This means that GSM has to undergo further development in order to stay compatible with other mobile networks. Before introducing VoIP into GSM, the impact of the SIP signaling needs to be investigated. Therefore, the objective of this master thesis is to simulate and evaluate how SIP signaling could be multiplexed with VoIP traffic and other MMTel services in the GSM network. In order to multiplex the SIP signaling with other traffic types, new delay sensitive scheduling algorithms have been derived and analyzed along with a dynamic allocation algorithm. The allocation algorithm provide each mobile user with a number of timeslots and frequencies used to transmit its data, while the scheduling algorithms are used to conclude which user that should get the highest priority when several users try to transmit data at the same time and on the same frequency. Unfortunately, it was not possible to receive any reliable data within the given timeframe due to bugs and errors in the simulator software. Therefore, the conclusions in this master thesis are based on our expectations on such simulations. The conclusion is that in order to maximize the number of VoIP users in the GSM system, the presence signaling should be lower prioritized than VoIP and SIP signaling. It is also concluded that the delay sensitive scheduler which is dependent on previous penalties in both the UL and DL scheduling is to be preferred when high multiplexing levels are reached. Furthermore, the throughput of the downprioritized MMTel service should not be expected to be high when the VoIP traffic is intense.