A proposal for seamless handovers in GSM indoor wireless networks

We consider the evolution of a GSM-based indoor corporate network, where base transceiver stations (BTS) are IP end-points of the local area network (LAN). Multiplexing capabilities of real time protocol (RTP) payloads are exploited in order to transport efficiently TRAU (transcoding and rate adaptation unit) frames between each BTS and the BSC (base station controller)/access node. In this context, two RTP connections are used to transmit downlink TRAU frames to both current BTS and candidate BTS during handover execution, thus preventing typical loss of voice frames during this phase. This contributes to improving the quality of service (QoS) for voice communications in the selected environment. Signaling issues and assignments of resources to individual connections within a single RTP/UDP/IP connection in the described environment are also addressed. The proposed architecture also offers advantages for implementing tandem free operation (TFO) in a local environment.