User cooperative mobility for better multimedia communication quality

For mobile multimedia communications, Quality of Service (QoS) is significantly important. In general it will incur costs to improve QoS. Regarding utility function of cost versus gain for an individual user, it is useful to evaluate relationship between cost such as energy consumption and gain such as QoS. Network operators or service providers could invest more resource facilities to improve QoS that will result in rising users' service fees. User cooperative mobility is one of key technology that does not select between cost and gain tradeoff, but provides the best solution.