Optimized Relay Selection and Power Allocation by an Exclusive Method in Multi-Relay AF Cooperative Networks

( Jianrong Bao ),( Bin Jiang ),( Chao Liu ),( Xianyang Jiang ),( Minhong Sun ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.7

In a single-source and multi-relay amplify-forward (AF) cooperative network, the outage probability and the power allocation are two key factors to influence the performance of an entire system. In this paper, an optimized AF relay selection by an exclusive method and near optimal power allocation (NOPA) is proposed for both good outage probability and power efficiency. Given the same power at the source and the relay nodes, a threshold for selecting the relay nodes is deduced and employed to minimize the average outage probability. It mainly excludes the relay nodes with much higher thresholds over the aforementioned threshold and thus the remainders of the relay nodes participate in cooperative forwarding efficiently. So the proposed scheme can improve the utility of the resources in the cooperative multi-relay system, as well as reduce the computational complexity. In addition, based on the proposed scheme, a NOPA is also suggested to approach sub-optimal power efficiency with low complexity. Simulation results show that the proposed scheme obtains about 2.1dB and 5.8dB performance gain at outage probability of 10^-4, when compared with the all-relay-forward (6 participated relays) and the single-relay-forward schemes. Furthermore, it obtains the minimum outage probability among all selective relay schemes with the same number of the relays. Meanwhile, it approaches closely to the optimal exhaustive scheme, thus reduce much complexity. Moreover, the proposed NOPA scheme achieves better outage probability than those of the equal power allocation schemes. Therefore, the proposed scheme can obtain good outage probability, low computational complexity and high power efficiency, which makes it pragmatic efficiently in the single-source and multi-relay AF based cooperative networks.

Outage Capacity Analysis for Cooperative DF and AF Relaying in Dissimilar Rayleigh Fading Channels

Suchitra Shrestha(스레스타),KyungHi Chang(장경희) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.4A

Cooperative relaying permits one or more relay to transmit a signal from the source to the destination, thereby increasing network coverage and spectral efficiency. The performance of cooperative relaying is often measured as outage probability. However, appropriate measure for the channel quality is outage capacity. Although the outage probability for cooperative relaying protocol has been analyzed before, very little research has been addressed for the outage capacity. This paper is the first of its kind to derive a closed-form analytical solution of outage capacity using fixed decode and forward relaying and amplify and forward relaying in dissimilar Rayleigh fading channels, considering channel coefficients known to the receiver side. The analytical results show a tradeoff between the SNR and the number of relays for specific outage capacity. A comparison between decode and forward relaying and amplify and forward relaying shows that decode and forward relaying outperforms amplify and forward relaying for a large number of relays.

Outage Capacity Analysis for Cooperative DF and AF Relaying in Dissimilar Rayleigh Fading Channels

스레스타,장경희,Shrestha, Suchitra,Chang, Kyung-Hi The Korea Institute of Information and Commucation 2008 韓國通信學會論文誌 Vol.33 No.4A

Cooperative relaying permits one or more relay to transmit a signal from the source to the destination, thereby increasing network coverage and spectral efficiency. The performance of cooperative relaying is often measured as outage probability. However, appropriate measure for the channel quality is outage capacity. Although the outage probability for cooperative relaying protocol has been analyzed before, very little research has been addressed for the outage capacity. This paper is the first of its kind to derive a closed-form analytical solution of outage capacity using fixed decode and forward relaying and amplify and forward relaying in dissimilar Rayleigh fading channels, considering channel coefficients known to the receiver side. The analytical results show a tradeoff between the SNR and the number of relays for specific outage capacity. A comparison between decode and forward relaying and amplify and forward relaying shows that decode and forward relaying outperforms amplify and forward relaying for a large number of relays.

다수의 주 사용자가 존재하는 무선인지 네트워크의 중계 전송 성능 평가

이제민(Jemin Lee),왕한호(Hano Wang),노고산(Gosan Noh),홍대식(Daesik Hong) 大韓電子工學會 2010 電子工學會論文誌-TC (Telecommunications) Vol.47 No.5

본 논문은 underlay 기법으로 다수의 주 사용자 수신기들(primary receivers)이 부 사용자들(secondary users)과 공존할 때 부 사용자들의 협력을 통한 중계 전송의 성능을 평가하였다. 무선 인지 환경에 적합한 중계기 선택 기준을 사용하였을 때 부 사용자의 outage probability를 유도하였다. 이러한 분석을 통하여, 공존하는 다수의 주 사용자들로 인하여 증가하는 부 사용자의 outage probability 양을 정량적으로 표현하였다. 모의실험을 통하여, 주 사용자의 개수가 증가할수록 중계 전송이 직접 정송에 비하여 민감하게 성능이 감소하고, 이로 인하여 중계 전송이 직접 전송에 비하여 비효율적일 수 있음을 보여주었다. 또한, 비록 다수의 주 사용자가 존재하더라고 중계기 선택의 다이버시티를 늘려 줌으로서 중계 전송이 직접 전송보다 효율적일 수 있음을 확인하였다. This paper evaluates the outage probability of cognitive relay networks with cooperation between secondary users based on the underlay approach, when multiple primary receivers coexist with secondary users. Using an appropriate relay selection criterion in cognitive radio networks, we derive the outage probability of secondary user. It is shown that the outage probability increases as the number of primary receivers increases and we quantify the increase. Through the simulation results, we verify that the performance of relaying transmission is varied more sensitively compared to that of direct transmission as the number of primary receivers increases. In addition, the relaying transmission can be less efficient than the direct transmission when multiple primary receiver exist but it can be more efficient than the direct transmission by increasing the relay selection diversity.

Outage Equivalence of Opportunistic Relaying and Selection Cooperation in Presence of Co-Channel Interference

MinChul Ju,Kyu-Sung Hwang IEEE 2015 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.14 No.6

<P>In this paper, we investigate two different relay selection schemes, opportunistic relaying (OR) and selection cooperation (SC), for decode-and-forward (DF)-based relay networks consisting of a source, multiple relays, and a destination in the presence of multiple co-channel interferers, where each terminal has a single antenna and operates in a half-duplex mode. For the network, we first extend the conventional OR and SC to relay networks with the direct-path and multiple co-channel interferers, and obtain the exact and closed-form outage probability of the OR. Then, we show that the SC is equivalent to the OR in terms of outage performance for relay networks with the direct-path and multiple co-channel interferers. Finally, we show that the SC and OR are outage-optimal under the aggregate power consumption constraint at the relays for relay networks with the direct-path and multiple co-channel interferers.</P>

Outage Analysis and Optimization for Four-Phase Two-Way Transmission with Energy Harvesting Relay

( Guanyao Du ),( Ke Xiong ),( Yu Zhang ),( Zhengding Qiu ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.10

This paper investigates the outage performance and optimization for the four-phase two-way transmission network with an energy harvesting (EH) relay. To enable the simultaneous information processing and energy harvesting at the relay, we firstly propose a power splitting-based two-way relaying protocol (PSTWR). Then, we discuss its outage performance theoretically and derive an explicit expression for the system outage probability. In order to find the optimal system configuration parameters such as the optimal power splitting ratio and the optimal transmit power redistribution factor, we formulate an outage-minimized optimization problem. As the problem is difficult to solve, we design a genetic algorithm (GA) based algorithm for it. Besides, we also investigate the effects of the power splitting ratio, the power redistribution factor at the relay, and the source to relay distance on the system outage performance. Finally, extensive simulation results are provided to demonstrate the accuracy of the analytical results and the effectiveness of the GA-based algorithm. Moreover, it is also shown that, the relay position greatly affects the system performance, where relatively worse outage performance is achieved when the EH relay is placed in the middle of the two sources.

Hybrid Spectrum Sharing with Cooperative Secondary User Selection in Cognitive Radio Networks

( Md Fazlul Kader ),( Asaduzzaman ),( Md. Moshiul Hoque ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.9

In this paper, we propose a cooperative hybrid spectrum sharing protocol by jointly considering interweave (opportunistic) and underlay schemes. In the proposed protocol, secondary users can access the licensed spectrum along with the primary system. Our network scenario comprises a single primary transmitter-receiver (PTx-PRx) pair and a group of M secondary transmitter-receiver (STx-SRx) pairs within the transmission range of the primary system. Secondary transmitters are divided into two groups: active and inactive. A secondary transmitter that gets an opportunity to access the secondary spectrum is called “active”. One of the idle or inactive secondary transmitters that achieves the primary request target rate R_PT will be selected as a best decode-and-forward (DF) relay (Re) to forward the primary information when the data rate of the direct link between PTx and PRx falls below R_PT. We investigate the ergodic capacity and outage probability of the primary system with cooperative relaying and outage probability of the secondary system. Our theoretical and simulation results show that both the primary and secondary systems are able to achieve performance improvement in terms of outage probability. It is also shown that ergodic capacity and outage probability improve when the active secondary transmitter is located farther away from the PRx.

V2I 통신음영지역의 V2V 중계 시스템에서 단일 중계기 선택의 전송 실패확률 분석

신은희(Eun-Hee Shin),권영민(Young-Min Kwon),송병훈(Byung-Hun Song),이인호(In-Ho Lee) 한국정보과학회 2013 정보과학회 컴퓨팅의 실제 논문지 Vol.19 No.5

지능형 교통 시스템(ITS: Intelligent Transport System)은 빠르고 안전한 차세대 교통체계 구축을 위해 활발하게 추진되고 있는 기술이다. ITS는 운전자에게 신속하고 정확하게 교통정보를 제공해줌으로써 운전자가 적합한 운전경로를 선택할 수 있게 해주며 운전시간을 단축시켜서 탄소배출량도 줄일 수 있어, 이러한 ITS에서의 V2I(Vehicle-to-Infrastructure), V2V(Vehicle-to-Vehicle) 통신에 대한 관심이 높아지고 있다. 본 논문에서는 V2I로 해결될 수 없는 통신음영지역에서의 V2V 중계 시스템을 설명한다. 다수 개의 중계차량들이 있을 때 한 대의 중계차량을 선택하는 방법을 설명하고, 이때 얻을 수 있는 전송 실패확률을 구한다. V2V 중계 시스템에서 다수 개의 중계차량들 중 최적의 중계차량을 선택함으로써 전송 실패확률을 줄일 수 있으며, V2I 통신음영지역에서 V2V 통신을 가능하게 하여 통신범위를 넓힐 수 있음을 보인다. Recently, the intelligent transport system (ITS) is pursued vigorously to build a next-generation of a fast and safe transport system. By providing traffic information quickly and accurately, ITS allows drivers to choose the proper driving directions and to shorten the driving time, and drivers can reduce carbon emissions. So V2I(Vehicle-to-Infrastructure) and V2V(Vehicle-to -Vehicle) communications in ITS have been receiving great attention. In this paper, V2V relay system in shadow zone where cannot be covered by V2I is described. Assuming that there are multiple relay vehicles, we explain single relay vehicle selection scheme and obtain the outage probability. By selecting the best relay vehicle among multiple relay vehicles in V2V relay system, we can reduce the outage probability. And we show that the coverage for vehicle communication becomes large by enabling V2V communication in V2I shadow zone.

Outage Analysis and Optimization for Time Switching-based Two-Way Relaying with Energy Harvesting Relay Node

( Guanyao Du ),( Ke Xiong ),( Yu Zhang ),( Zhengding Qiu ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.2

Energy harvesting (EH) and network coding (NC) have emerged as two promising technologies for future wireless networks. In this paper, we combine them together in a single system and then present a time switching-based network coding relaying (TSNCR) protocol for the two-way relay system, where an energy constrained relay harvests energy from the transmitted radio frequency (RF) signals from two sources, and then helps the two-way relay information exchange between the two sources with the consumption of the harvested energy. To evaluate the system performance, we derive an explicit expression of the outage probability for the proposed TSNCR protocol. In order to explore the system performance limit, we formulate an optimization problem to minimize the system outage probability. Since the problem is non-convex and cannot be directly solved, we design a genetic algorithm (GA)-based optimization algorithm for it. Numerical results validate our theoretical analysis and show that in such an EH two-way relay system, if NC is applied, the system outage probability can be greatly decreased. Moreover, it is shown that the relay position greatly affects the system performance of TSNCR, where relatively worse outage performance is achieved when the relay is placed in the middle of the two sources. This is the first time to observe such a phenomena in EH two-way relay systems.

Exact Outage Probability of Two-Way Decode-and-Forward NOMA Scheme with Opportunistic Relay Selection

( Tan-phuoc Huynh ),( Pham Ngoc Son ),( Miroslav Voznak ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.12

In this paper, we propose a two-way relaying scheme using non-orthogonal multiple access (NOMA) technology. In this scheme, two sources transmit packets with each other under the assistance of the decode-and-forward (DF) relays, called as a TWDFNOMA protocol. The cooperative relays exploit successive interference cancellation (SIC) technique to decode sequentially the data packets from received summation signals, and then use the digital network coding (DNC) technique to encrypt received data from two sources. A max-min criterion of end-to-end signal-to-interference-plus-noise ratios (SINRs) is used to select a best relay in the proposed TWDFNOMA protocol. Outage probabilities are analyzed to achieve exact closed-form expressions and then, the system performance of the proposed TWDFNOMA protocol is evaluated by these probabilities. Simulation and analysis results discover that the system performance of the proposed TWDFNOMA protocol is improved when compared with a conventional three-timeslot two-way relaying scheme using DNC (denoted as a TWDNC protocol), a four-timeslot two-way relaying scheme without using DNC (denoted as a TWNDNC protocol) and a two-timeslot two-way relaying scheme with amplify-and-forward operations (denoted as a TWANC protocol). Particularly, the proposed TWDFNOMA protocol achieves best performances at two optimal locations of the best relay whereas the midpoint one is the optimal location of the TWDNC and TWNDNC protocols. Finally, the probability analyses are justified by executing Monte Carlo simulations.