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In this paper, three scheduling algorithms are presented for multi-user MIMO precoding based on code book to achieve precoding and multi-user diversity gain in broadcast channel. Randomicity, feedback load and system capacity are considered in the three criteria. The precoding matrices are generated based on the per user unitary and rate control (PU2RC) proposed by Samsung. Theoretical analysis and...
In MIMO multi-relay systems, close-loop precoding at relay nodes is not necessary if unicast modes are carried out. However, in unicast modes, the inter-stream interference at relay nodes may degrade the system capacity. In this paper, two unicast modes are proposed to reduce the negative impact of the residual interference. The first one suppresses the interference by applying orthogonal precoding...
We present field experiment results on multiple input multiple output (MIMO) precoding using orthogonal frequency division multiple access (OFDMA) in the E-UTRA downlink. We measured the throughput performance of 4??4 MIMO precoding with 1- to 4-stream transmission. Time variation characteristics of throughput, SINR, and antenna correlations are compared to evaluate the selection criteria for the...
The capacity of a multipoint MIMO wireless network is interference-limited. In order to increase the system capacity, MIMO precoding at the transmitter and decoding at the receiver can be employed so that interference among different nodes is eliminated or suppressed. In this paper, we propose precoding/decoding techniques based on an iterative zero-forcing approach. By utilizing the extra degrees...
In this paper, we consider a multiuser distributed MIMO system, under multipath fading channels, with orthogonal frequency division multiplexing (OFDM) technology. The aim is to extend and evaluate, co-located precoding schemes that have been recently proposed, in a distributed scenario. Assuming knowledge of CSI prior to transmission, we can remove the interference among users by employing precoding...
In the wireless communication system, multi-input multi-output technique can be used to increase capacity. In the MIMO system, the non-linear precoding can archive the MIMO channel capacity through perfect feedback with a high complexity. To reduce the complexity, linear precoding with limited feedback information rate is used in most of simultaneous communication system. Further more, open loop precoding...
In this paper we consider the CQI reporting problem in MIMO downlink with adaptive switching between single user and multiuser mode and finite rate feedback. The feedback consist of channel directional information, which is the precoding weight, and channel quality information, which is a quantized value of estimated post processing SINR. The quantization of the channel directional information causes...
Tomlinson-Harashima precoding (THP) is considered as a prominent precoding scheme due to its capability to efficiently cancel out the known interference at the transmitter side. Therefore, the information rates achieved by THP are superior to those achieved by conventional linear precoding schemes. In this paper, a new lower bound on the achievable information rate for the regularized THP scheme under...
In this work an efficient low-complexity user selection algorithm for the multiuser MISO downlink wireless channel is presented. The algorithm combines Zero-Forcing linear precoding with low-complexity correlation-based Space Division Multiple Access (SDMA) and aims at maximizing the sum rate of all system users. The complexity of the algorithm is analyzed and is shown to be lower than previously...
In this paper, an interference alignment system for the MIMO network is investigated. Three different precoding schemes, which are based on zero-forcing (ZF), minimum mean square error (MMSE) and maximum SLR criteria, are proposed. The simulation results show that the proposed precoding schemes are very efficient and can provide good performance for the considered MIMO network.
In this paper, the performance of vector precoding in multiple input multiple output broadcast channels (MIMO BC) is investigated and compared with other channel decomposition techniques utilized for implementing zero forcing (ZF) preceding. It is a known result that ZF precoding requires pseudo inversion of the channel matrix, where this operation is only optimum when the transmitter power is unconstrained...
The combination of relay and Multiple-Input Multiple-Output (MIMO) techniques can significantly benefit the signal transmission in cellular networks. In this work, we propose a novel relaying scheme for the relay assisted MIMO broadcast channel including user classification and preceding. The users are firstly classified as Direct Link (DL) users and Relay Link (RL) users according to their channel...
Coordinating transmission techniques by multiple base stations or radio access points have recently attracted a lot of attention because of its potential for inter-cell co-channel interference mitigation and spectral efficiency significant improvement. This paper explicitly presents network multi-point coordinating downlink transmission technologies, especially discusses the clustered supercell configuration...
Linear precoding for multiuser multiple input multiple output (MIMO) cellular systems has generally focused on a single isolated cell. A crucial tool in algorithm development has been a downlink/uplink duality. Here we investigate downlink multiuser communications across multiple cells. Previous work identified the resulting asynchronous interference as a key issue. We prove the existence of a downlink/uplink...
In this paper we reduce the feedback overhead in two-stream MIMO with per stream link adaptation and codebook based precoding. The amount of feedback may be reduced by indicating the CQI of one stream in a differential manner. The performance of the system depends on how the differential feedback is designed. We optimize the differential feedback for the weaker data stream by considering an optimum...
In this paper, we propose a duality-optimization based framework to maximize the weighted sum throughput for a multiple-input multiple-output (MIMO) ad hoc network. The new schemes include an approximate global optimization approach and an iterative search approach based on the duality framework. Transmitter adaptive precoding and receiver minimum mean-square-error (MMSE) detection for interference...
Interference among multiple base stations that co-exist in the same location limits the capacity of wireless networks. In this paper, we propose a nonlinear multi-user MIMO cooperative downlink transmission scheme. The algorithm eliminates the interference and achieves symbol error rate (SER) fairness among different users. To eliminate the interference, Tomlinson Harashima precoding (THP) is used...
In this paper a novel channel inversion (CI) precoding scheme is introduced for the downlink of multiple input multiple output (MIMO) systems. The proposed technique outperforms conventional CI by exploiting some of the consequential inter- channel interference (ICI). It achieves this by applying partial channel inversion such that the constructive part of ICI is preserved and exploited while the...
Until recently, mobile communication tasks have been grouped into different layers in a hierarchical layer approach. In this conventional approach, layer-specific protocols are developed and optimised independently. As new wireless applications emerge, requiring high data rates and flexibility for supporting applications with significantly varying QoS requirements, it has become imperative that a...
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