Uplink Multi-BS MIMO with Limited Backhaul Bandwidth

S backhaul overhead, although lower than that of JD, is still In modern cellular wireless communication systems, inter-cell relatively high. Note that for any information bit, if its LLRs interference (ICI) has become a dominant factor that restricts the generated at different BSs have the same sign, its estimate improvement of system performance such as throughput and remains the same before and after LLR combination. This coverage. A wide range of techniques have been developed to suggests that the BSs only need to exchange LLRs for those bits solve ICI, like fractional frequency reuse, coordinated scheduling, with mismatched local decoding results at different BSs. Based ICI-aware power control etc. Among various alternatives, on this observation we propose a three-stage information cooperative multiple-input-multiple-output (MIMO) processing exchange technique for SC, in which the cooperative BSs locate among multiple base stations (BSs) [1][2] (referred to as multi- the bits that need LLR exchange and combination in the first two BS MIMO below) is one of the most spectral efficient solutions. stages and forward LLRs for these bits to the central processing Multi-BS MIMO can be implemented in two ways: coordinated unit in the third stage. As only a very small part of information beamforming towards terminals in the downlink [1], and bits has mismatched local decoding results at different BSs, the coordinated detection in the uplink [2]. In this paper, we focus on backhaul overhead is significantly reduced.