Network-Centric Cooperation Schemes for Uplink Interference Management in Cellular Networks

The huge growth in demand for wireless data combined with shortages of spectrum has led to an urgent need for spectral efficiency and cell-edge performance improvements in cellular networks. This has led to the shrinking of macro-cell sizes and also Heterogeneous Network deployments with overlays of small cells and macro-cells sharing the same spectrum. With these trends in cellular network evolution, out-of-sector interference becomes a major impediment and the impairments due to interference are especially severe on the uplink where near-far effects are more likely to be experienced. This article provides a holistic treatment of network-centric cooperation schemes that have emerged as strong candidates for uplink interference management in evolving cellular networks (e.g. networks based on 3GPP Long-Term Evolution based air-interface technologies and beyond). In particular, we introduce 3 novel approaches that have recently been proposed: (a) Network MIMO which carries out joint multi-antenna signal processing across sectors; (b) Network Interference Cancellation Engine (NICE) which opportunistically cancels dominant interferers that have already been decoded at neighboring sectors and requires 1-2 orders of magnitude less backhaul overhead; and (c) a hybrid approach which combines the strengths of both Network MIMO and NICE in an attempt to achieve further spectral efficiency benefit without incurring huge backhaul overhead. Several considerations of both theoretical and practical significance (overhead, latency) related to these approaches are discussed and simpler variants that may apply in the context of heterogeneous networks are also considered. Quantitative investigations of these network-centric cooperation schemes in realistic operating environments show that substantial improvements of up to a factor of 2 in average and cell-edge spectral efficiency may be achieved.