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34
Multi-Cell MIMO Cooperative Networks: A New Look at Interference
- J. Selec. Areas in Commun. (JSAC
, 2010
"... Abstract—This paper presents an overview of the theory and currently known techniques for multi-cell MIMO (multiple input multiple output) cooperation in wireless networks. In dense networks where interference emerges as the key capacitylimiting factor, multi-cell cooperation can dramatically improv ..."
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Cited by 257 (40 self)
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Abstract—This paper presents an overview of the theory and currently known techniques for multi-cell MIMO (multiple input multiple output) cooperation in wireless networks. In dense networks where interference emerges as the key capacitylimiting factor, multi-cell cooperation can dramatically improve the system performance. Remarkably, such techniques literally exploit inter-cell interference by allowing the user data to be jointly processed by several interfering base stations, thus mimicking the benefits of a large virtual MIMO array. Multicell MIMO cooperation concepts are examined from different perspectives, including an examination of the fundamental information-theoretic limits, a review of the coding and signal processing algorithmic developments, and, going beyond that, consideration of very practical issues related to scalability and system-level integration. A few promising and quite fundamental research avenues are also suggested. Index Terms—Cooperation, MIMO, cellular networks, relays, interference, beamforming, coordination, multi-cell, distributed.
Joint Base Station Clustering and Beamformer Design for Partial Coordinated Transmission in Heterogeneous Networks
, 2012
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1 Adaptive Spatial Intercell Interference Cancellation in Multicell Wireless Networks
, 909
"... Downlink spatial intercell interference cancellation (ICIC) is considered for mitigating other-cell interference using multiple transmit antennas. A principle question we explore is whether it is better to do ICIC or simply standard single-cell beamforming. We explore this question analytically and ..."
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Cited by 29 (8 self)
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Downlink spatial intercell interference cancellation (ICIC) is considered for mitigating other-cell interference using multiple transmit antennas. A principle question we explore is whether it is better to do ICIC or simply standard single-cell beamforming. We explore this question analytically and show that beamforming is preferred for all users when the edge SNR (signal-to-noise ratio) is low (< 0 dB), and ICIC is preferred when the edge SNR is high (> 10 dB), for example in an urban setting. At medium SNR, a proposed adaptive strategy, where multiple base stations jointly select transmission strategies based on the user location, outperforms both while requiring a lower feedback rate than the pure ICIC approach. The employed metric is sum rate, which is normally a dubious metric for cellular systems, but surprisingly we show that even with this reward function the adaptive strategy also improves fairness. When the channel information is provided by limited feedback, the impact of the induced quantization error is also investigated. It is shown that ICIC with well-designed feedback strategies still provides significant throughput gain. Index Terms Cellular network, other-cell interference, base station coordination, interference cancellation, limited feedback. I.
Fast algorithms and performance bounds for sum rate maximization in wireless networks
- in Proceedings of IEEE INFOCOM
, 2009
"... Abstract — Sum rate maximization by power control is an important, challenging, and extensively studied problem in wireless networks. It is a nonconvex optimization problem and achieves a rate region that is in general nonconvex. We derive approximation ratios to the sum rate objective by studying t ..."
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Cited by 28 (10 self)
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Abstract — Sum rate maximization by power control is an important, challenging, and extensively studied problem in wireless networks. It is a nonconvex optimization problem and achieves a rate region that is in general nonconvex. We derive approximation ratios to the sum rate objective by studying the solutions to two related problems, sum rate maximization using an SIR approximation and max-min weighted SIR optimization. We also show that these two problems can be solved very efficiently, using much faster algorithms than the existing ones in the literature. Furthermore, using a new parameterization of the sum rate maximization problem, we obtain a characterization of the power controlled rate region and its convexity property in various asymptotic regimes. Engineering implications are discussed for IEEE 802.11 networks. Index Terms — Duality, Distributed algorithm, Power control, Weighted sum rate maximization, Nonnegative matrices and applications,
An overview of radio resource management in relay-enhanced OFDMA-based networks
- IEEE Communications Surveys and Tutorials
"... Abstract—Researchers in both academia and industry have accepted OFDMA as the most appropriate air-interface for the emerging broadband wireless access networks and standards. A number of IEEE working groups and various research forums are focusing on developing relay and mesh-enabled networks with ..."
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Cited by 21 (4 self)
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Abstract—Researchers in both academia and industry have accepted OFDMA as the most appropriate air-interface for the emerging broadband wireless access networks and standards. A number of IEEE working groups and various research forums are focusing on developing relay and mesh-enabled networks with cooperative communication features. Among these research efforts are IEEE 802.11s, IEEE 802.16j/m, and 3GPP’s advanced long term evolution (LTE-advanced). The combination of OFDMA with relaying techniques provides rich opportunities for cost-effective and high-performance networks. To exploit such opportunities requires intelligent radio resource management (RRM) algorithms. Although a number of publications have highlighted the important and challenging issues involved in designing RRM algorithms for OFDMA networks, only recently a number of papers have investigated relay-enhanced OFDMA-based multicellular networks. By and large, the literature indicates that these issues constitute a hot research topic that will continue to attract interest. This paper provides a survey of the current literature on OFDMA networks enhanced with decode-and-forward relaying and provides their link to earlier literature in non-OFDMA networks. In addition, a rich list of references is provided to direct the readers toward some of the emerging techniques. Index Terms—RRM, OFDMA, relaying, 4G, scheduling, throughput, fairness. I.
Distributed Interference-Aware Energy-Efficient Power Optimization
"... Abstract—Power optimization techniques are becoming in-creasingly important in wireless system design since battery tech-nology has not kept up with the demand of mobile devices. They are also critical to interference management in wireless systems because interference usually results from both aggr ..."
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Cited by 19 (1 self)
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Abstract—Power optimization techniques are becoming in-creasingly important in wireless system design since battery tech-nology has not kept up with the demand of mobile devices. They are also critical to interference management in wireless systems because interference usually results from both aggressive spectral reuse and high power transmission and severely limits system performance. In this paper, we develop an energy-efficient power optimization scheme for interference-limited wireless communi-cations. We consider both circuit and transmission powers and focus on energy efficiency over throughput. We first investigate a non-cooperative game for energy-efficient power optimization in frequency-selective channels and reveal the conditions of the existence and uniqueness of the equilibrium for this game. Most importantly, we discover a sufficient condition for generic multi-channel power control to have a unique equilibrium in frequency-selective channels. Then we study the tradeoff between energy efficiency and spectral efficiency and show by simulation results that the proposed scheme improves both energy efficiency and spectral efficiency in an interference-limited multi-cell cellular network. Index Terms—Interference, energy efficiency, power optimiza-tion, OFDM, non-cooperative power control. I.
Decentralized inter-cell interference coordination by autonomous spectral reuse decisions
- in Proc. European Wireless Conference (EW 2008
, 2008
"... Abstract—Future wireless packet switched cellular networks will require dense frequency reuse to achieve high capacity. At the same time, measures are required which limit the interference on the frequency carriers. It is assumed that central entities performing the task of interference coordination ..."
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Cited by 13 (2 self)
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Abstract—Future wireless packet switched cellular networks will require dense frequency reuse to achieve high capacity. At the same time, measures are required which limit the interference on the frequency carriers. It is assumed that central entities performing the task of interference coordination with global knowledge should be avoided. Rather, distributed algorithms are sought for. To this end, we propose decentralized resource allocation algorithms that enable base stations to select a pool of favorable resources with low interference based on local knowl-edge only. The actual user-level resource allocation from that pool will then be performed by fast schedulers operating on the preselected resources within each cell. We analyze and evaluate the proposed resource selection algorithms by introducing a simplified wireless network model and applying methods from game theory. Proving the existence of Nash equilibria shows that stable resource allocations can be reached by selfish agents. In addition to that, we perform simulations to determine the speed of convergence and the resulting equilibrium interference levels. By comparing these to an optimal global solution, which is derived by solving an integer linear program, we are able to quantify the efficiency loss of the distributed game approach. It turns out that even though the distributed game results are sub-optimal, the low degree of system complexity and the inherent adaptability make the decentralized approach promising especially for dynamic scenarios. I.
Opportunities and challenges in OFDMA-based cellular relay networks: A radio resource management perspective
- IEEE Trans. Veh. Technol
, 2010
"... Abstract—The opportunities and flexibility in relay networks and orthogonal frequency-division multiple access (OFDMA) make the combination a suitable candidate network and air-interface technology for providing reliable and ubiquitous high-data-rate coverage in next-generation cellular networks. Ad ..."
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Cited by 10 (4 self)
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Abstract—The opportunities and flexibility in relay networks and orthogonal frequency-division multiple access (OFDMA) make the combination a suitable candidate network and air-interface technology for providing reliable and ubiquitous high-data-rate coverage in next-generation cellular networks. Advanced and intelligent radio resource management (RRM) schemes are known to be crucial toward harnessing these opportunities in future OFDMA-based relay-enhanced cellular networks. However, it is not very clear how to address the new RRM challenges (such as enabling distributed algorithms, intra-cell/inter-cell routing, intense and dynamic co-channel interference (CCI), and feedback overhead) in such complex environments comprising a plethora of relay stations (RSs) of different functionalities and characteristics. Employment of conventional RRM schemes in such networks will highly be inefficient if not infeasible. The next-generation networks are required to meet the expectations of all wireless users, irrespective of their locations. High-data-rate connectivity, mobility, and reliability, among other features, are examples of these expectations. Therefore, fairness is a critical performance aspect that has to be taken into account in the design of prospective RRM schemes. This paper reviews some of the prominent challenges involved in migrating from the conventional cellular architecture to the relay-based type and discusses how intelligent RRM schemes can exploit the opportunities in relay-enhanced OFDMA-based cellular networks. We identify the role of multiantenna systems and explore the current approaches in literature to extend the conventional schedulers to next-generation relay networks. This paper also highlights the fairness aspect in such networks in the light of the recent literature, provides some example fairness metrics, and compares the performances of some representative algorithms. Index Terms—Cellular, fairness, load balancing, orthogonal frequency-division multiple access (OFDMA), radio resource management (RRM), relaying, routing, scheduling, throughput.
Iterative resource allocation for maximizing weighted sum min-rate in downlink cellular OFDMA systems
- IEEE Trans. Signal Process
, 2011
"... All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately. ..."
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Cited by 10 (6 self)
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All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Cross-layer Optimization for Wireless Networks with Deterministic Channel Models
"... Abstract—Existing work on cross-layer optimization for wireless networks adopts simple physical-layer models, i.e., treating interference as noise. In this paper, we adopt a deterministic channel model proposed in [11, 12], a simple abstraction of the physical layer that effectively captures the eff ..."
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Cited by 8 (4 self)
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Abstract—Existing work on cross-layer optimization for wireless networks adopts simple physical-layer models, i.e., treating interference as noise. In this paper, we adopt a deterministic channel model proposed in [11, 12], a simple abstraction of the physical layer that effectively captures the effect of channel strength, broadcast and superposition in wireless channels. Within the Network Utility Maximization (NUM) framework, we study the cross-layer optimization for wireless networks based on this deterministic channel model. First, we extend the wellapplied conflict graph model to capture the flow interactions over the deterministic channels and characterize the feasible rate region. Then we study distributed algorithms for general wireless multi-hop networks. The convergence of algorithms is proved by Lyapunov stability theorem and stochastic approximation method. Further, we show the convergence to the bounded neighborhood of optimal solutions with probability one under constant steps and constant update intervals. Our numerical evaluation validates the analytical results. I.
