As the demand for wireless data grows to unprecedented levels, cellular service providers have been investigating different ways to meet this growing demand. The deployment of small cells with reduced transmission powers and reduced coverage areas is being considered as one potential solution. Using the same spectrum employed by existing macro cells, small cells allow increased spatial reuse of bandwidth, thus providing the potential for improved user rates. One challenge for small cells, though, is that due to their weaker signals (lower transmission powers, antennas with smaller antenna gains), the coverage area tends to be significantly reduced and the incremental benefit of deploying each small cell is limited. In this paper, resource partitioning is proposed along with suitably modified cell selection criteria to improve the performance of heterogeneous networks comprising small and macro cells that operate in the same swath of spectrum. Our simulation results demonstrate that with four small cells deployed per sector, 5%-ile and 50%-ile user throughputs both improve by ~150% relative to the same case without resource partitioning.
enhancements are similar in concept to those incorporated in third generation cellular standards such as CDMA2000* high rate packet data (HRPD) [4] or the high speed downlink packet access (HSDPA) feature within the Universal Mobile Telecommunications System (UMTS) standard [1], they have been specifically tailored to an OFDMA air interface. Additional subchannelization options have been added in IEEE 802.16e to improve resource management flexibility and achieve better system performance under a wide range of operating conditions. IEEE 802.16e also adds new medium access control (MAC) procedures related to handover support. Multiple carrier bandwidths and associated fast
The huge growth in demand for wireless data, combined with shortages of spectrum, has led to an urgent need for spectral effi ciency and cell-edge performance improvements in cellular networks. Macrocells are shrinking in size, and heterogeneous networks are being deployed where small cells and macrocells now share the same spectrum. With these trends in cellular network evolution, out-of-sector interference is becoming a major impediment. Impairments due to interference are especially severe on the uplink, where near-far effects are more likely to be experienced. This paper provides a holistic view of the 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 three novel approaches: 1) network multiple input multiple output (MIMO), which carries out joint multi-antenna signal processing across sectors; 2) network interference cancellation engine (NICE) which opportunistically cancels dominant interferers that have already been decoded at neighboring sectors and decreases backhaul overhead by one to two orders of magnitude; and 3) a hybrid approach which combines the strengths of both network MIMO and NICE in an attempt to achieve further spectral effi ciency without incurring huge backhaul overhead. Several considerations of both theoretical and practical signifi cance (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 improvement may be achieved in average and cell-edge spectral effi ciency.
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