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As one of the candidate wireless access techniques of 5G system, non-orthogonal multiple access (NOMA) is a power domain non-orthogonal multiple-access technique, which can greatly enhance spectral efficiency and system capacity. This paper mainly focus on user pairing and access theme of NOMA system, and respectively presents channel state sorting pairing algorithm (CSS-PA) as user pairing (UP) theme...
This paper considers a downlink Coordinated Multi Point (CoMP) transmission network, where the base stations (BSs) are connected to a central unit via backhaul links to serve mobile users (MUs). The objective is to jointly optimize the BS mode (active or sleep), MU association, and cooperative beamforming to minimize the total power consumption including backhauling power. We formulate the problem...
This work focuses on the downlink of a single-cell large-scale MIMO system in which the base station equipped with M antennas serves K single-antenna users. In particular, we are interested in reducing the implementation complexity of the optimal linear precoder (OLP) that minimizes the total power consumption while ensuring target user rates. As most precoding schemes, a major difficulty towards...
In this paper, an optimal algorithm is proposed for the joint power allocation and relay assignment problem in OFDM relay networks. The network model consists of single-source single-destination with N half-duplex decode-and-forward (DF) relays. The source node uses orthogonal frequency division multiplexing (OFDM) to transmit information to relays where each serves one subcarrier. Our objective is...
Compute-and-Forward (C&F) has been proved to be an efficient approach for multiuser, multihop wireless networks. It allows intermediate relays to infer and forward linear combinations of the transmitted messages, in order to achieve high computation rate. The coefficient selection for each relay is a shortest vector problem (SVP). The most common solutions for such a problem are exhaustive search...
In massive multiple-input multiple-output (MIMO) uplink, the minimum mean square error (MMSE) algorithm is near-optimal and linear, but still suffers from high-complexity of matrix inversion. Based on Gauss-Seidel (GS) method, an efficient architecture for massive MIMO soft-output detection is proposed in this paper. To further accelerate the convergence rate of the conventional GS method with acceptable...
Among various discrete transforms, discrete Fourier transformation (DFT) is the most important technique that performs Fourier analysis in various practical applications, such as digital signal processing, wireless communications, to name a few. Due to its ultra-high computing complexity as O(N2), in practice the N-point DFT is usually performed in the form of fast Fourier transformation (FFT) with...
As the size of CMOS devices continues to scale down, the reliability of circuits becomes one of main challenges in low supply voltage designs. Markov Random Field (MRF) circuits, a probabilistic-based approach, can achieve higher noise immunity compared to traditional designs under conditions of ultra-low supply voltage and low threshold voltage. However, the basic MRF elements have complex structures...
In this paper, a two-stage phase-increment-based frequency estimator with a general pilot-symbol-assisted- modulation (PSAM) structure is proposed for burst-mode communications. We derive the true Cramer-Rao bounds (CRBs) under the general PSAM structure for pure data-aided (DA) estimator. The proposed phase increment-based estimator is a pure DA estimator and implemented via two stages. In the first...
In this work we propose a new recursive block decoding method for MIMO systems. A complexity reduction is obtained compared to existing methods by avoiding the exhaustive decoding on one block. We propose the use of a semi-exhaustive search using a list composed of the Maximum Likelihood (ML) solution and its neighborhoods. We show through error probability derivation that we can achieve the full...
In this paper, optimum soft-output (SO) multiple-input multiple-output (MIMO) sphere detectors (SDs) are studied. Noting that ordering the channel matrix columns plays an important role in reducing the tree-search complexity of a SD, we propose an optimized layer-ordering scheme based on the minimum cumulative residual criterion. The proposed scheme is studied in the context of a 4 × 4 MIMO system,...
Because of the existence of channel noise, channel coding serves as an indispensable part of mobile communication system and the essential guarantee for the reliable, accurate, and effective transmission of information. As one of the most competitive channel code candidates for the 5th generation (5G) mobile communication, polar codes are the first codes which can provably achieve the symmetric capacity...
Recently massive multi-input multi-output (MIMO) techniques have attracted growing research interest. However, most existing works assume centralized control, which may involve a heavy overhead as the number of users also becomes massive. In this paper, we focus on random-access massive MIMO systems. We first analyze the performances of two conventional schemes widely used in massive MIMO, and derive...
Space shift keying (SSK) transmission is a low-complexity complement to spatial modulation (SM) that solely relies on a spatial-constellation diagram for conveying information. The achievable performance of SSK is determined by the channel conditions, which in turn define the minimum Euclidean distance (MED) of the symbols in the received SSK constellation. In this contribution we concentrate on improving...
Energy Detector is a spectrum sensing algorithm which senses the present spectrum in real time and calculates the energy of available primary users. Primary users (PU) are one who can legally use the allocated spectrum to them. For calculated values of energy, we can find out whether primary user is present or not by comparing it with user defined threshold value representing noise level. In this...
In this paper, three novel techniques are proposed and investigated for multiple relay selection in dual hop OFDM networks. These techniques are based on the exploitation of sparse signal recovery theory and on carefully-designed groupings of the subcarriers depending on the channel quality. In particular, the proposed techniques use the Orthogonal Matching Pursuit algorithm which enables them to...
The multiuser switched diversity (MUSwiD) selection scheme is useful in reducing the required amount of channel estimations and system complexity in wireless networks. In this paper, we propose and evaluate the performance of cognitive amplify-and-forward (AF) MUSwiD relay networks where a cognitive user is selected among a set of users for data reception. The selection process is performed such that...
In this paper the joint cost-sharing and multi-relay selection problem in two-way relay networks is modeled as a repeated Bayesian Stackelberg game. In each Stackelberg stage, the two source nodes submit payment offers to the relays targeting the next best relay that maximizes the network power efficiency. Each relay, as a follower, will participate only if its cost will be covered by the payments...
In this paper, the problem of distributed multi-relay selection in cooperative wireless networks is studied via a political coalition formation game approach. Specifically, a sum-rate maximizing distributed coalition formation algorithm is proposed, in which a winning coalition eventually emerges, which is also self-enforcing (and hence stable). In addition, the proposed algorithm offers a sum-rate...
Precoder index modulation (PIM) is a recently proposed transmission scheme in which the index of the chosen precoder matrix from a set of predetermined pseudo-random phase precoder (PRPP) matrices will also convey information bits in addition to the information bits conveyed through conventional modulation symbols. In this paper, first we derive lower and upper bounds on the capacity of PIM. Second,...
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