Improving Downlink UMTS Capacity by Exploiting Direct Mobile-to-Mobile Data Transfer

The goal of this work is to analyze the feasibility of a peer-to-peer file sharing technique in mobile cellular environments, taking into account key characteristics and peculiarities of the UMTS radio access network (UTRAN). The concept is referred here to as mobile-to-mobile (m2m). Our research efforts explore the performance benefits of m2m file sharing applications in UMTS networks in terms of releasing overall downlink capacity. In our concept the users that are interested in downloading a popular file form a mobile cooperative community and using the fact that traffic load of multimedia services is asymmetrically distributed between uplink and downlink, contribute their own currently not used uplink capacity for providing the packets of the content to other users within the group in multicast mode on the uplink carrier frequencies. As a result a major part of the traffic is shifted away from the downlink, making the released downlink capacity available for providing better quality of service (QoS) for real-time services. Two alternative scenarios of serving user requests (m2m and conventional UMTS mode) have been analyzed. The results indicate a dramatic increase in service probability and overall throughput gain of up to 85 % in a UMTS network, supported by the m2m data transmission mode. Furthermore, results show that by a well-designed m2m routing policy and proper utilization of uplink resources substantial reduction of the expected file download time can be achieved.