Cache-induced opportunistic MIMO cooperation: A new paradigm for future wireless content access networks

Advanced interference mitigation techniques such as cooperative MIMO (CoMP) have been proposed to improve the spectral efficiency of future 5G wireless networks. However, conventional CoMP is quite costly because it requires high capacity backhaul for payload exchange between the BSs. In this paper, we propose a novel solution framework of cache-induced opportunistic CoMP to achieve the CoMP gain for multimedia streaming applications without expensive backhaul. Specifically, by caching a portion of the media files, the base stations (BS) opportunistically employ CoMP to transform the cross-link interference into spatial multiplexing gain. We study a mixed-timescale optimization of (short timescale) MIMO precoding and (long timescale) cache control to minimize the transmit power under the QoS constraint. By exploiting the timescale separations of the optimization variables, we derive low complexity multi-timescale solution for the MIMO precoding and cache control. The solution has significant gains over various baselines.