Capacity-Approaching Multiuser Communications over Multiple Input/Multiple Output Broadcast Channels

2009 ◽  
pp. 417-454
Author(s):  
Uri Erez ◽  
Stephan ten Brink
2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Monchai Lertsutthiwong ◽  
Thinh Nguyen ◽  
Bechir Hamdaoui

We develop a framework that exploits network coding (NC) and multiple-input/multiple-output (MIMO) techniques, jointly together, to improve throughput of downlink broadcast channels. Specifically, we consider a base station (BS) equipped with multiple transmit antennas that serves multiple mobile stations (MSs) simultaneously by generating multiple signal beams. Given the large number of MSs and the small number of transmit antennas, the BS must decide, at any transmission opportunity, which group of MSs it should transmit packets to, in order to maximize the overall throughput. We propose two algorithms for grouping MSs that take advantage of NC and the orthogonality of user channels to improve the overall throughput. Our results indicate that the proposed techniques increase the achievable throughput significantly, especially in highly lossy environments.


2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Hyun-Ho Choi

The interference alignment (IA) is a promising technique to efficiently mitigate interference and to enhance capacity of a wireless network. This paper proposes an interference alignment scheme for a cellular network withLcells andKusers under a multiple-input multiple-output (MIMO) Gaussian interfering broadcast channel (IFBC) scenario. The proposed IA scheme aligns intercell interferences (ICI) into a small dimensional subspace through a cooperative receive beamforming and cancels both the ICI and interuser interferences (IUI) simultaneously through a transmit beamforming. We characterize the feasibility condition for the proposed IA to achieve a total number of degrees of freedom (DoF) ofLKin terms of the numbers of transmit antennas and receive antennas. Then we derive the maximum number of DoF achieved by the proposed IA by finding an optimal dimension of ICI alignment subspace for a given antenna configuration. The numerical results show that the proposed IA scheme has a better DoF performance than the conventional schemes.


2014 ◽  
Vol 1049-1050 ◽  
pp. 1776-1780
Author(s):  
Hai Ying Ren ◽  
Yuan An Liu ◽  
Fang Liu ◽  
Jin Chun Gao ◽  
Kai Ming Liu ◽  
...  

Multiple-input multiple-output (MIMO) interference broadcast channel (IBC) plays an important role in the modern wireless communications. The upper bound of degree of freedom (DoF) and corresponding achievable schemes have been investigated. However, all the achievable schemes require perfect channel state information at transmitters (CSIT). In the absence of CSIT, the DoF value is still unknown. This paper mainly focuses on theG-cellK-user MIMO IBC, where there areMantennas at each transmitter andNantennas at each receiver. The transmitters only know channel coherent time internals rather than the values of channel coefficients. The users in the same cell are assumed to be able to share the channel information. Based on a heterogeneous block fading model, a blind interference alignment (IA) scheme is proposed for this scenario. We show that when and , then a total of degrees of freedom (DoF) can be achieved. The inner bound is same with the decomposition DoF upper bound.


2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Zhirong Zeng ◽  
Huiqin Du ◽  
Zujian Wu

This paper considers a multiuser (MU) multiple-input multiple-output (MIMO) visible light communication (VLC) system with broadcast channels. Due to the simultaneous transmission of the different source data to the receivers covered with the light rays, the interuser interference (IUI) may degrade the system performance. We strive to suppress the IUI by minimizing the maximum mean square errors (MSE) under the assumption of the perfect knowledge of channel state information (CSI). However, since the CSI may not be perfectly known in practice, a robust design is required against the channel uncertainties. Additionally, the nonnegativity and the limited linear range of the optical signals have been taken into account in the VLC transceiver designs. Simulation results validate that the proposed min-max-MSE approach can provide fair transmission, compared with the minimization of sum-MSE approach. Furthermore, it is demonstrated that the robust scheme is capable of providing robustness and gaining a considerable bit error rate (BER) performance.


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