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In this work we present a unified treatment on the most common metrics used in the utility function of state-of-the-art user selection algorithms for sum rate maximization in MISO systems under Zero-Forcing Beamforming. We present the way that such metrics are used to maximize the total sum rate and the relations held among each other. Via simulation we found upper bounds of the average total sum...
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We propose a low-complexity transmission strategy in multi-user multiple-input multiple-output downlink systems. The adaptive strategy adjusts the precoding methods, denoted as the transmission mode, to improve the system sum rates while maintaining the number of simultaneously served users. Three linear precoding transmission modes are discussed, i.e., the block diagonalization zero-forcing, the...
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In multiusers MIMO Interfering Broadcast Channels with limited feedback, there are quantization errors of quantized channel direction information (CDI). The system sum-rate performance will certainly degrade due to designing precoder with mismatch channel state information. Using tools from random matrix theory, some statistical characteristics of quantization error for CDI are obtained, and a precoder...
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In this paper, we propose a multi-user orthogonal frequency-division multiplexing (OFDM) transmission scheme with partial channel reusing between users, suitable for multiple-input multiple-output (MIMO) systems with not-so-large antenna arrays. The spectrum efficiency is improved at the price of adding multiuser interference (MUI) which can be overcome by the multiplexing gain of MIMO. In addition,...
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A coordination strategy among a large cellular MIMO network is presented in this paper. With clustered linear precoding and dynamic frequency reservation techniques, JDFR-BDGMD (Joint Dynamic Frequency Reservation and Block Diagonalization precoding with Geometric Mean Decomposition precoding scheme) greatly mitigates intra-cluster interference as well as inter-cluster interference in the downlink...
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The article presents a prototype of a distributed system for wheelchair users assessment characterized by multi-sensing, embedded processing compatible IEEE 1451.4 standard for smart sensors and wireless communication based on IEEE 802.15.4. A set of smart sensing channels are connected in a 1-Wire network supported by an embedded platform that assures the acquisition and appropriate digital processing...
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The architectural structure of Radio Access Networks (RANs) in Multi-Radio Access Technology (RAT) cellular systems is based on the independent iteration of single RAT RANs and statically dividing radio frequency resources between co-deployed RATs, leading to high system complexity and suboptimal spectrum utilization. This paper proposes the unification of RAN operation and presents a scalable RAN...
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In this paper, we investigate a cooperative relay network where two users exchange messages through a full-duplex relay. A joint relay transmit-receive antenna selection and opportunistic source selection (RAS-OSS) strategy is proposed to improve the performance of the full-duplex relay network, when the roles of the antennas at the full-duplex relay are not predefined. Both of the amplify-and-forward...
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Cognitive radio is an emerging technology that is used to solve the problem of scarce spectrum resource utilization. Among its fundamental functions, the most important is the spectrum sensing which requires high accuracy and low complexity particularly at very low signal-to-noise ratio (SNR) values. In this paper, we discuss a recently proposed spectrum sensing detector [1] which explores the sparsity...
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This paper studies the security performance of random codes in the syndrome coding scheme. We propose theoretical analysis using a putative (n, k) code having the same distribution of syndrome probabilities as the ensemble of all (n, k) random codes to calculate the average equivocation of random codes, and compare the theoretical results with the simulation results generated from Monte Carlo analysis...
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We design and assess some practical low-density parity-check (LDPC) coded transmission schemes for the Gaussian broadcast channel with confidential messages (BCC). This channel model is different from the classical wiretap channel model as the unauthorized receiver (Eve) must be able to decode some part of the information. Hence, the reliability and security targets are different from those of the...
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The paper focuses on using Network Coding (NC) with TCP for multi-hop wireless networks to provide fault-tolerant and timely delivery of streaming data. The paper shows that there is an inherent latency in video playback when TCP with random linear NC is employed. With the objective of reducing latency and jitter at the receiver, the paper proposes a Variable Bucket size based Network Coding (VBNC)...
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Network coding techniques are usually applied upon network layer protocols to improve throughput in wireless networks. However, the packet scheduling algorithm has long been neglected. With proper scheduling, bottleneck nodes can clear their packet queue faster than a vanilla round-robin scheduling algorithm. Therefore, a higher Coding+MAC gain can be achieved. In this paper, we formulate the scheduling...
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We focus in this work on optimal maximum a posteriori (MAP) decoding for lattice-based physical-layer network coding operating in Gaussian multiple access relay channels. We consider a general lattice design that makes our results hold for any lattice coding schemes of any dimensions including the Compute-and-Forward framework. By examining the MAP decoding rule, we first derive an analytical bound...
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In this paper, we investigate the performance of the so-called Cross Network operating under diverse Network Coding (NC) techniques. We study the impact of Medium Access Control (MAC) layer fairness on the throughput performance of the network for the cases of pure relaying, digital NC with and without overhearing and physical layer NC with and without overhearing. We provide a comparison among these...
