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Sum Rate Characterization of Joint Multiple CellSite Processing
, 2005
"... The sumrate capacity of a cellular system model is analyzed, considering the uplink and downlink channels, while addressing both nonfading and flatfading channels. The focus is on a simple Wynerlike multicell model, where the system cells are arranged on a circle, assuming the cellsites are lo ..."
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Cited by 68 (11 self)
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The sumrate capacity of a cellular system model is analyzed, considering the uplink and downlink channels, while addressing both nonfading and flatfading channels. The focus is on a simple Wynerlike multicell model, where the system cells are arranged on a circle, assuming the cellsites are located at the boundaries of the cells. For the uplink channel, analytical expressions of the sumrate capacities are derived for intracell TDMA scheduling, and a “WideBand ” (WB) scheme (where all users are active simultaneously utilizing all bandwidth for coding). Assuming individual percell power constraints, and using the Lagrangian uplinkdownlink duality principle, an analytical expression for the sumrate capacity of the downlink channel is derived for nonfading channels, and shown to coincide with the corresponding uplink result. Introducing flatfading, lower and upper bounds on the average percell sumrate capacity are derived. The bounds exhibit an O(loge K) multiuser diversity factor for a number of users percell K ≫ 1, in addition to the array diversity gain. Joint multicell processing is shown to eliminate outofcell interference, which is traditionally considered to be a limiting factor in highrate reliable communications. This paper was presented in part at the 9
Input optimization for multiantenna broadcast channels and perantenna power constraints
 in Proc. IEEE GLOBECOM
, 2004
"... Abstract — This paper considers a Gaussian multiantenna broadcast channel with individual power constraints on each antenna, rather than the usual sum power constraint over all antennas. Perantenna power constraints are more realistic because in practical implementations each antenna has its own p ..."
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Abstract — This paper considers a Gaussian multiantenna broadcast channel with individual power constraints on each antenna, rather than the usual sum power constraint over all antennas. Perantenna power constraints are more realistic because in practical implementations each antenna has its own power amplifier. The main contribution of this paper is a new derivation of the duality result for this class of broadcast channels that allows the input optimization problem to be solved efficiently. Specifically, we show that uplinkdownlink duality is equivalent to Lagrangian duality in minimax optimization, and the dual multipleaccess problem has a much lower computational complexity than the original problem. This duality applies to the entire capacity region. Further, we derive a novel application of Newton’s method for the dual minimax problem that finds an optimal search direction for both the minimization and the maximization problems at the same time. This new computational method is much more efficient than the previous iterative waterfillingbased algorithms and it is applicable to the entire capacity region. Finally, we show that the previous QRbased precoding method can be easily modified to accommodate the perantenna constraint. I.
Distributed Antenna Processing in Cellular Systems
, 2007
"... This chapter presents a survey of information theoretic results available on DAS in cellular systems. The treatment focuses on the derivation of the sumrate of different intercell and intracell communications strategies for both uplink and downlink. A simple symmetric family of cellular models in ..."
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This chapter presents a survey of information theoretic results available on DAS in cellular systems. The treatment focuses on the derivation of the sumrate of different intercell and intracell communications strategies for both uplink and downlink. A simple symmetric family of cellular models in which the intercell interferences are emerging from a the adjacent cells only is considered. Although hardly realistic, this family of models accounts for essential parameters of cellular systems such as intercell interference and fading. Whenever computation of the sumrate is intractable or yields little insight into the problem, asymptotic performance criteria (e.g. extremeSNR parameters) are evaluated. Emphasis is placed on the assessment of benefits of cooperation among APs (i.e. joint detection/precoding). 1 2CHAPTER 1. AN INFORMATION THEORETIC VIEW OF DISTRIBUTED ANTENNA PROCESS Mathematical tools underlying the results are introduced briefly where necessary. Finally, some advanced topics, such as cooperation among terminals, are discussed as well. 1.1