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The concept of interference alignment has been studied mainly from an information-theoretic and signal processing point of view, focusing on scenarios with a high degree of coordination among nodes often achieved by means of transmission scheduling. However, many real-world networks employ random access policies rather than deterministic scheduling, and it is therefore important to understand how...
In this paper we analyze the performance of advanced OFDM packet scheduling techniques based on 3GPP UTRAN Long Term Evolution (LTE) framework for high velocity scenarios. Based on our previous investigations in system performance analysis, we demonstrate that packet scheduler being part of the whole radio resource management (RRM) process has a major impact on it. On the other hand high user velocities...
Multiple-Input Multiple-Output (MIMO) communications have shown great promise in providing high spectral efficiency for wireless ad hoc networks. In this paper we study the problem of joint routing, scheduling, power control and bit rate selection in MIMO-based ad hoc network with the goal of maximizing the system throughput that satisfies a given end-to-end traffic demand. We formulate this cross-layer...
The virtual MIMO (V-MIMO) and coordinated multipoint transmission (CoMP) are adopted by the LTE system to extend the uplink spectral efficiency. V-MIMO makes use of spatial multiplexing to increase system throughput while CoMP by means of mitigating inter cell interference (ICI) significantly achieve the same effect. In this paper, we present an orthogonality based proportional fair scheduling (OPF)...
MIMO system has attracted considerable attention recently for its potential to increase the system capacity. In this paper, we aim to design practical user scheduling algorithms to maximize the system performance. Various MAC scheduling policies have been implemented, in order to provide distributed traffic control and robustness against interference. Further, in order to increase the efficiency of...
Significant throughput gains can be achieved in a multi-user MIMO (MU-MIMO) wireless system by exploiting the combination of multi-user scheduling and multi-user diversity. Open-loop MU-MIMO (OL-MU-MIMO) is a codebook based precoding technique where precoders are fixed a priori at the base station (BS) in a known fashion and the user needs to feedback which precoding vector is to be chosen referred...
In future fourth generation wireless networks OFDM and MIMO techniques will be heavily exploited to provide connectivity to heterogeneous users offering different data traffic types. This paper proposes a low complexity resource allocation strategy for MIMO-OFDMA (Multiple-Input Multiple-Output Orthogonal Frequency Division Multiple Access) broadcast channel to support delay-sensitive traffic with...
Multiple-Input Multiple-Output (MIMO) technology has great potential for improving the throughput of Wireless Mesh Networks (WMNs). In this paper, we investigate the joint stream allocation and scheduling problem for single-user MIMO communication in WMNs with the objective of maximizing the demand satisfaction for a set of flows. The notion of transmission configuration (TC) is introduced and a heuristic...
Efficiently scheduling the optimal multi-user multiple-input multiple-output links presents a considerable challenge since it depends upon accurate knowledge of the multi-user channel state information and involves significant computational complexity. This paper demonstrates a technique for efficiently scheduling based on a few key parameters that describe the physical nature of multi-user propagation...
This paper addresses the scheduling problem for multiuser multi-input multi-output (MU-MIMO) system based on Tomlinson-Harashima Precoding (THP). By considering the channel gain and channel correlation jointly, a low-complexity multiuser scheduling approach is proposed. Compared with the existing scheduling schemes, the proposed scheme can avoid complicated searching process, and thus reduce the scheduling...
The major problem of multiuser MIMO precoding and scheduling is the required Channel State Information (CSI) at the base station which needs to be provided to the base station via a feedback channel in case of frequency division duplex. Each user quantizes the channel direction information and computes a Channel Quality Indicator (CQI), e.g., based on the Signal-to-Interference-and-Noise Ratio (SINR),...
Block diagonalization (BD) is an attractive method for approaching sum capacity in multiuser multiple-input multiple-output (MIMO) broadcast channels. However, when channel state information (CSI) is limited, the performance of the BD is degraded because inter-user interference cannot be completely eliminated. In this paper, we study limited feedback systems for the BD where a large number of users...
In this paper, we investigate interference-aware joint secondary user (SU) selection/scheduling and quantized power control (JSUS-QPC) schemes for the uplink communication in the cognitive MIMO system. The main objective of the JSUS-QPC is to maximize the sum-rate capacity of the cognitive MIMO uplink communication system under the constraint that the interference to the primary users (PU) is below...
In this paper, we present a performance evaluation for six scheduling algorithms over a MIMO-OFDM based cellular system. We have selected a set of scheduling algorithms that may use information about the instantaneous channel conditions, status of transmission queues, QoS requirements or pending HARQ retransmissions. Performance evaluation is focused on average delay under different cell load conditions,...
In multiuser multiple input multiple output (MIMO) systems, it is optimal to serve multiple users at the same time in order to achieve high data rates. However, the use of a transmit beamforming technique requires a well designed user selection scheme to obtain good performances. The optimal scheduling solution can only be obtained through a highly computationally complex exhaustive search. In addition,...
In an ad hoc network, efficiently scheduling the optimal multi-user multiple-input multiple-output links is challenging. Specifically, optimal scheduling requires full understanding of the subspace structure of the channel matrices, but exploiting this detailed information during scheduling requires significant computational and algorithmic complexity. This paper demonstrates efficient yet effective...
We consider the problem of power minimization under per-user quality of service (QoS) constraints (expressed in terms of rates) in parallel multiple-input single-output (MISO) broadcast channels employing linear zero-forcing precoding. Solving the arising scheduling problem by an exhaustive search is prohibitively complex due to its combinatorial nature so that the use of successive user allocation...
We consider a coordinated multicell multiple-antenna downlink transmission in a cellular network also known as \textit{network MIMO}, which is expected to play a key role in future broadband cellular systems. While clustered network MIMO is a practical scheme to benefit from multicell cooperation, it still suffers from inter-cluster (uncoordinated) interference especially for the cell-edge users....
This paper presents system level downlink performance evaluation results for the TDD based LTE-Advanced networks utilizing some of the most recent technologies for mobile systems. The main enhanced technology components used in the systems include multi-user (MU)-MIMO, intra-site coordinated multipoint (CoMP) transmission and space-time-frequency proportional fair scheduling. Performance comparison...
In this paper we evaluate a recently proposed multiple-input multiple-output (MIMO) system called the Layered Steered Space-Time Codes (LSSTC). The LSSTC system is evaluated for multi-user environments where scheduling can be used to increase the system capacity by harnessing the multi-user diversity. This evaluation is done by comparing the capacity and the probability of error for several combinations...
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