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Cooperative relay is considered as an efficient scheme to improve the physical layer security of a wireless relay system in the presence of eavesdroppers. In this paper, multiple-level relay scheme is proposed. We consider relay weight design for secrecy rate maximization subject to a power constraint. The results show that a higher achievable secrecy rate is achieved in the two-level relay channel...
As everyone knows, the energy of signals diminishes with increasing distance, so users at the edge of hexagon cells have lower signal-to-noise ratio (SNR) than users at the center, which means they are more easily interfered by signals from other base stations. So we consider the application of relay to the cellular case to help users at the edge to eliminate interferences and obtain higher sum-rate...
In the wireless cooperative relay system, the private information can be intercepted by the untrusted relays. The traditional method of artificial noise based on physical layer security consumed much more power to protect the security of private information. To solve this problem, this paper combines amplify-and-forward coefficient of the relays with the joint channel state information (JCSI), and...
We propose a new transmission scheme for MEMO Y channel by combining the antenna selection algorithm with signal space alignment and network coding strategy. This strategy works with more relaxed constraint between M and N. The average symbol error rate of the transmission scheme is analyzed for the multiple-access phase and the broadcast phase respectively. We show that the proposed scheme can provide...
The paper proposed a zone fault locating scheme. By using topology matrix of distribution system with DGs, describing matrices of adaptative condition of distribution system zones were established and types of zones were achieved. Then fault range could be targeted in related areas by comparing preset values with differential current values calculated by fault currents value from distribution automatic...
In this paper, we consider the sensor network, where multiple sensors communicate with a single fusion center via their respective direct links and relays. We propose schemes exploiting both quantize-and- forward (QF) and compressive sensing (CS) in relay networks, aiming to take full use of the diversity to recover the original sparse signals through the collection of a small number of samples. Such...
In this paper, we consider a dual-hop multipleinput-multiple-output (MIMO) half-duplex amplify-and-forward relay network. Each terminal is equipped with multiple antennas. A novel and efficient precoding scheme based on per-antennasignal to leakage plus noise ratio (PA-SLNR) maximization is used at the relay downlink. We consider linear processing only at the relay terminal. The channel state information...
The scarcity of radio resources coupled with the high data rate demands in the last few years, induced incremental relaying techniques one of the most promising technologies. This is simply because it allows reaping spatial diversity and saving the channel resources at the same time. In this contribution, we make use of the Decode and Forward incremental relaying technique in OFDM cooperative systems...
In this paper, a multiuser two-way filter-and- forward relaying scheme for wireless communication over wideband channels is considered. We propose pre/post-rake processing in conjunction with optimized filtering at the relay to reduce the signal processing burden at the source and destination nodes. Two relay filter design problem formulations are introduced, namely (a) a convex optimization problem...
It is well known that relay is able to neutralize some interferences in destinations. In this paper we use not only relay to neutralize interferences but also interference alignment to reduce the number of antennas needed in destinations. To this end, a scheme of cognitive relay-aided interference neutralization and alignment is proposed. To neutralize and align interferences, the relay needs to retransmit...
Asymmetry in average channel conditions is a challenging factor in two-way relay communication (TWRC) system in order to obtain a balanced performance at two end nodes. In this paper, for a coded TWRC system, we consider hierarchical modulation and network coding assisted bit interleaved coded modulation (HMNC-BICM) based system. The performance of the considered HMNC-BICM based system is compared...
The achievable performance of successive relay system will significantly degrade, if severe inter- relay interference (IRI) exist. In this paper, two beamforming methods are proposed for mitigating the IRI inflicted by multiple-input multiple-output (MIMO) assisted two-path successive relay nodes. More specifically, we exploit the additional degree of freedom offered by the spatial domain during the...
In this paper we study and analyze coverage region for half-duplex multiple-input multiple-output (MIMO) relay channel with amplify-and-forward (AF) strategy at the relay station. By assuming mixed Rayleigh and Rician fading channels with two different relay station situations, we consider the objective of maximizing coverage region for a given transmission rate and find the optimal relay location...
Transmission in frequency selective channels has some challenges due to the generated ISI which significantly deteriorates the performance of the system; hence, most of the proposed methods in literature for flat fading cannot be established in frequency selective conditions. Filter and forward strategy was proposed in AF protocol for combating the ISI in frequency selective channels. In this paper,...
Physical layer security has attracted a great deal of attentions in recent years. This is achieved through using the physical layer characteristics to help sender to transfer data reliably with perfect secrecy. Using multiple-antenna relay node can improve the secrecy capacity of such channel. In this paper, we study the cooperative wiretap channel in which secure data transmission is achieved with...
This paper considers an amplify-and-forward (AF) cooperative system with multiple relays which may eavesdrop on the source signal without authorization. In conventional cooperative system where the relays are assumed trustworthy, the precoding design usually tends to optimize quality of the received signal at the relays. However, the considered system relies on the relays' assistance and requires...
An adaptive delay-tolerant distributed space-time coding (DSTC) scheme with feedback is proposed for two-hop cooperative multiple-input multiple-output (MIMO) networks using an amplify-and-forward strategy and opportunistic relaying algorithms. Maximum likelihood receivers and adjustable code matrices are considered subject to a power constraint. In the proposed delay-tolerant DSTC scheme, an adjustable...
In this paper, a network consisting of several partially connected subnetworks where each subnetwork includes one relay is considered. “Partially connected” means that not all nodes are connected to all relays. Some nodes may be connected to multiple relays. The entire bidirectional pair-wise communication between the nodes takes place via the intermediate half-duplex amplify-and-forward relays, considering...
In this paper, large partially connected wireless relay interference networks are considered. The entire network is made up of multiple disjoint groups of source-destination node pairs and relays called subnetworks. Each subnetwork is assumed to be fully connected. The different subnetworks are mutually connected by a few inter-subnetwork links. A two-hop relay-aided interference alignment scheme...
The data relay satellite as a typical GEO satellite application plays an important role in the TT&C and data transmission based on space. Taking into account operation and production cost of the relay satellite very high, so it is great to significantly improve the social and economic benefits as much as possible to extend the satellite in orbit life. Many countries have adopted without north-south...
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