A Prototype System for Evaluating Multi-Cell Cooperative Transmission in Asynchronous Mobile Radio Networks

Mobile communication services are now expected to support the speeds offered by fixed lines. To fill this demand, a critical goal is to improve user throughput performance especially at the cell-edge, even in the LTE (Long Term Evolution)-Advanced system. Multi-cell cooperative transmission is a promising technology and has been extensively studied. This technology requires highly accurate synchronization between multiple BSs. However, the future mobile network will consist of asynchronous networks (e.g., those controlled by IP protocols) and stable synchronization is not possible with existing techniques. We have been studying synchronization schemes for asynchronous networks to realize multi-cell cooperative transmission. In this paper, we present a prototype of a multi-cell cooperative transmission system that combines our synchronization scheme with radio equipment. Experiments confirm its synchronization accuracy, and the resulting wireless transmission performance in the field evaluation indicates our synchronization scheme provides a practical and effective approach.