Consider a fixed orientation multi-user visible light communication (VLC) system with multi-color light emitting diodes (LEDs) where each transmitter serves a user with limited coordination impeding transmitter-side b...
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Consider a fixed orientation multi-user visible light communication (VLC) system with multi-color light emitting diodes (LEDs) where each transmitter serves a user with limited coordination impeding transmitter-side beamforming. In this paper, a multi-layer coding and constrainedpartialgroup decoding (CPGD) method is proposed to tackle strong color interference and increase the system throughput. After channel model formulation, user information rates are allocated and decoding order for all the received data layers is obtained by solving a max-min fairness problem using a greedy algorithm. An achievable rate is derived under the truncated Gaussian input distribution. To reduce the decoding complexity, a map on the decoding order and rate allocation is constructed for all positions of interest on the receiver plane parallel to the transmitter plane, and its size is reduced by a clustering algorithm. Meanwhile, the symmetrical geometry of LED arrays is exploited. Finally, the transmitter-user association problem is formulated and solved by a genetic algorithm. It is observed that the system throughput increases as the receivers are slightly misaligned with corresponding LED arrays due to the reduced interference level, but decreases afterwards due to the weakened link gain.
We propose novel coding and decoding methods for a fully connected K-user Gaussian interference channel via assigning multiple codebooks (layers) to each transmitter, such that at each receiver decoding interferers pa...
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ISBN:
(纸本)9781424492688
We propose novel coding and decoding methods for a fully connected K-user Gaussian interference channel via assigning multiple codebooks (layers) to each transmitter, such that at each receiver decoding interferers partially becomes feasible. Each receiver first identifies which interferers it should decode and which layers of them should be decoded, and then successively decodes a group of layers with a constraint on its group size treating the remaining layers as Gaussian noise. We provide a distributed algorithm that determines the transmission rate at each transmitter also finds the order of the layers to be successively decoded at each receiver. We also consider practical design of a system that employs the quadrature amplitude modulations (QAM) and rateless codes. Numerical results are provided on the achievable sum-rate under the ideal case of Gaussian signaling with random codes as well as on the system throughput under practical modulations and channel codes. The results show that the proposed multi-layer coding scheme with CPGD offers significant performance gain over the traditional un-layered transmission with single-user decoding.
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