On the capacity region of wireless ad hoc relay networks

I. Introduction Wireless ad hoc network regarded as a risingnetwork model has been discussed widely. Thestudy of the capacity of wireless ad hoc networkshas received significant attention recently. Guptaand Kumar in Ref.[1] proposed a model for studyingthe capacity of fixed ad hoc networks, where nodesare randomly located but are stationary. They madea somewhat pessimistic conclusion that the trafficrate per Source-to-Destination (S-D) pair will go tozero as the number of nodes per unit are…     

Using network coding to achieve the capacity of deterministic relay networks with relay messages

In this paper, we derive the capacity of the deterministic relay networks with relay messages. We consider a network that consists of five nodes, four of which can only communicate via the fifth one. However, the fifth node is not merely a relay as it may exchange private messages with the other network nodes. First, we develop an upper bound on the capacity region based on the notion of a single‐sided genie. In the course of the achievability proof, we also derive the deterministic capacity of a four‐user relay network (without private messages at the relay). The capacity achieving schemes use a combination of two network coding techniques: the simple ordering scheme and detour scheme. In the simple ordering scheme, we order the transmitted bits at each user such that the bi‐directional messages will be received at the same channel level at the relay, while the basic idea behind the detour scheme is that some parts of the message follow an indirect paths to their respective destinations. This paper, therefore, serves to show that user cooperation and network coding can enhance throughput, even when the users are not directly connected to each other. Finally, we make a conjecture about the capacity region of the general K‐node relay network with relay messages. Copyright © 2016 John Wiley & Sons, Ltd.     

Criterions of designing codebooks and a relay selection scheme for a relay network

For a relay network system with amplify and forward protocol, in this paper, analysis of performance is conducted, and an upper bound of pairwise error probability is obtained. Moreover, a scheme of relay selection is analyzed under assumptions that (i) the relays amplify and forward received signals without any signal processing; (ii) the receiver only knows channel state information from the relays to the receiver; and (iii) the transmitter and the relays do not have any channel state information. Based on the upper bound, a criterion of designing codebook is proposed. Surprisingly, this bound shows that increasing the number of relays can hardly improve performance. Furthermore, the error probability is decreasing with a speed of P^?1, no matter how large the relay number is, where P is the total energy. Also, for the relay selection, the optimal selecting way is to select only one relay with the largest channel gain, which is very different from existing schemes. These results are all confirmed by simulations. Copyright © 2015 John Wiley & Sons, Ltd.     

On the transport capacity of Gaussian multiple access and broadcast channels

We study the transport capacity of the Gaussian multiple access channel (MAC), which consists of multiple transmitters and a single receiver, and the Gaussian broadcast channel (BC), which consists of a single transmitter and multiple receivers. The transport capacity is defined as the sum, over all transmitters (for the MAC) or receivers (for the BC), of the product of the data rate with a reward r(x) which is a function of the distance x that the data travels. In the case of the MAC, assuming that the sum of the transmit powers is upper bounded, we calculate in closed form the optimal power allocation among the transmitters, that maximizes the transport capacity, using Karush-Kuhn-Tucker (KKT) conditions. We also derive asymptotic expressions for the optimal power allocation, that hold as the number of transmitters approaches infinity, using the most-rapid-approach method of the calculus of variations. In the case of the BC, we calculate in closed form the optimal allocation of the transmit power among the signals to the different receivers, both for a finite number of receivers and for the case of asymptotically many receivers, using our results for the MAC together with duality arguments. Our results can be used to gain intuition and develop good design principles in a variety of settings. For example, they apply to the uplink and downlink channel of cellular networks, and also to sensor networks which consist of multiple sensors that communicate with a single central station. Work was carried out while all authors were with the Telecommunications Research Center Vienna (ftw.), and supported by K plus funding for the ftw. project I0 “Signal and Information Processing.” Parts of this work have appeared, in preliminary form, in [1,2,3], Gautam A. Gupta holds a joint B.S./M.S. degree in mathematics and computing at the Department of Mathematics of the Indian Institute of Technology at New Delhi. During the summer of 2003, he attended a summer course on Probability and Statistical Mechanics organized by the Scoula Normale Superiore, in Pisa, Italy. During the summers of 2004 and 2005 he worked at the Telecommunications Research Center Vienna (ftw.) as a summer intern. During the spring of 2006, he was a visitor at the Norwegian University of Science and Technology, working toward his M. S. Thesis. Stavros Toumpis received the Diploma in electrical and computer engineering from the National Technical University of Athens, Greece, in 1997, the M.S. degrees in electrical engineering and mathematics from Stanford University, CA, in 1999 and 2002, respectively, and the Ph.D. degree in electrical engineering, also from Stanford, in 2003. From 1998 to 1999, he worked as a Research Assistant for the Mars Global Surveyor Radio Science Team, providing operational support. From 2000 to 2003, he was a Member of the Wireless Systems Laboratory, at Stanford University. From 2003 to 2005, he was a Senior Researcher with the Telecommunications Research Center Vienna (ftw.), in Vienna, Austria. Since 2005, he is a Lecturer at the Department of Electrical and Computer Engineering of the University of Cyprus. His research is on wireless ad hoc networks, with emphasis on their capacity, the effects of mobility on their performance, medium access control, and information theoretic issues. Jossy Sayir received his Dipl. El.-Ing. degree from the ETH Zurich in 1991. From 1991 to 1993, he worked as a development engineer for Motorola Communications in Tel Aviv, Israel, contributing to the design of the first digital mobile radio system ever produced by Motorola. He returned to ETH from 1993 to 1999, getting his PhD in 1999 under the supervision of Prof. J.L. Massey. The title of his thesis is “On Coding by Probability Transformation.” Since 2000, he has been employed at the Telecommunications Research Center (ftw) in Vienna, Austria, as a senior researcher. His research interests include iterative decoding methods, joint source and channel coding, numerical capacity computation algorithms, Markov sources, and wireless ad hoc and sensor networks. Since July 2002, he manages part of the strategic research activities at Ftw and supervises a group of researchers. He has taught courses on Turbo and related codes at Vienna University of Technology and at the University of Aalborg, Denmark. He has served on the organization committees of several international conferences and workshops. Ralf R. Müller was born in Schwabach, Germany, 1970. He received the Dipl.-Ing. and Dr.Ing. degree with distinction from University of Erlangen-Nuremberg in 1996 and 1999, respectively. From 2000 to 2004, he was with Forschungszentrum Telekommunikation Wien (Vienna Telecommunications Research Center) in Vienna, Austria. Since 2005 he has been a full professor at the Department of Electronics and Telecommunications at the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway. He held visiting appointments at Princeton University, U.S.A., Institute Eurecom, France, The University of Melbourne, Australia, and The National University of Singapore and was an adjunct professor at Vienna University of Technology. Dr. Müller received the Leonard G. Abraham Prize (jointly with Sergio S. Verdú) from the IEEE Communications Society and the Johann-Philipp-Reis Prize (jointly with Robert Fischer). He was also presented an award by the Vodafone Foundation for Mobile Communications and two more awards from the German Information Technology Society (ITG). Dr. Müller is currently serving as an associate editor for the IEEE Transactions on Information Theory.     

Optimal energy-efficient scheme for two-way relay channel using physical layer network coding

Systems are always designed and optimized based on full traffic load in the current literatures.However,practical systems are seldom operating at full load,even at peak traffic hours.Instead of maximizing system rate to achieve the full load,an optimal energy-efficient scheme to minimize the transmit power with required rates is investigated in this article.The considered scenario is a two-way relay channel using amplify-and-forward protocol of physical layer network coding,where two end nodes exchange mess...     

多用户MIMO双向中继信道鲁棒预编码

在多用户MIMO双向中继系统中,若使用非理想信道模型,中继处仅能获得部分下行信道状态信息,这样将导致系统性能大幅度下降。由此提出基于最小信干噪比最大化的鲁棒预编码方案。仿真表明,该方案不仅可以使最差信干噪比最大化,也有效地改善了系统的比特误码率性能。     

Denoise-and-forward based adaptive diversity scheme for physical-layer network coding with multiple relay node

The capacity issue of a denoise-and-forward(DNF) protocol was focused on based PNC system of frequency non-selective Rayleigh fading channel.First,the total sum-rate of the system was derived.With the derived sum-rate expression,two policies maximizing the system sum-rate are proposed.On this basis,a novel adaptive diversity scheme was proposed.Closed-form expressions of the system outage probability with the new proposed scheme as well as the amplify-and-forward (AF) based PNC system and the conventional direct transmission were derived over frequency-nonselective Rayleigh fading channels.Simulation experiments are conducted and the results show that the outage performance of the system can be im-proved significantly compared to the AF based PNC system and the conventional direct transmission scheme.     

On the MAC-BC duality of multiuser non-regenerative MIMO relay systems

Multiple input multiple output(MIMO) relaying techniques can greatly improve the spectral efficiency and extend network coverage for future wireless systems.This article investigates a multiuser MIMO relay channel,where a base station(BS) with multiple antennas communicates with multiple mobile stations(MS) via a relay station(RS) with multiple antennas.The RS applies linear processing to the received signal and then forwards the processed signal.The dual channel conditions between MIMO relay multiple access channel(MAC) and broadcast channel(BC) are first developed for single-relay scenario with white Gaussian noise.Then the MAC-BC duality for MIMO relay systems is established by proving that the capacity region of MIMO relay MAC is equal to that of dual MIMO relay BC under the same total network transmit power constraint.In addition,the duality is also extended to multi-relay scenario with arbitrary noise.Finally,several simple general numerical examples are provided to better illustrate the effectiveness of the MIMO relay MAC-BC duality.     

Multi relay node selection strategy for energy capture collaborative relay network

An energy capture cooperative relay network was studied.Unlike traditional cooperative relay networks,the relay nodes generally did not have a fixed energy supply but could carry out energy capture.For this network,a natural question was how to determine whether the relay nodes perform energy capture or data forwarding,and how to select the relay node to assist the information transmission between the source node and the destination node.Based on this problem,a multi-relay node selection scheme was proposed,which select the operation according to the energy of the current time slot of the relay node.In each time slot,the relay node that meet the battery threshold requirements was selected to assist in transmission.The Markov chain was used to model the charging and discharging process of the relay node battery,and the probability of interruption and throughput of the wireless network was obtained.And the value of the battery threshold when the throughput was maximized,that is,when the probability of network breakage was minimum was solved.Finally,the advantages of this scheme were verified by numerical experiments.     

MIMO双向中继信道的网络预编码算法研究

在衰落信道环境下,多输入多输出（MIMO）网络编码比传统的网络编码具有更好的鲁棒性.而网络编码与无线中继技术的结合也是目前最具潜力的研究热点之一.从通信基本原理的角度对MIMO双向中继系统的3种通信模型进行介绍,对相应的网络预编码实现的算法和机制进行研究对比,指出3种模型各自的优缺点.最后,讨论该领域的进一步研究方向.     

多径下Turbo码IDMA网络编码中继合作系统性能分析

基于交织多址网络编码中继合作系统,分析了其采用Turbo编码后在多径信道环境下的系统性能。研究了该系统中利用不同交织器来实现多用户的多址接入方式以及网络编码的中继合作机制。将多径信道以及Turbo编码融入该系统中,搭建计算机仿真环境,通过仿真数据分析系统性能。仿真结果表明,在多径信道环境下,采用Turbo编码的交织多址网络编码中继合作系统的系统误码率有明显改善。     

Differential space–time network coding in MIMO two‐way relay channel network

This paper focuses on noncoherent detection scheme for multiple‐input multiple‐output two‐way relay channel network with two two‐antennas source nodes and one single‐antenna relay node. An orthogonal differential space–time network coding (ODSTNC) scheme based on relay detection and forward protocol is proposed. The proposed scheme combines space–time coding with network coding, and the differential modulation and detection are used in both multiple access stage and broadcast stage. The multiple‐symbol differential detection is employed at the relay. The maximum likelihood decision and its low‐complexity sphere decoding decision are given. The upper and lower bounds on the average symbol error probability for this system under differential binary phase shift keying (DBPSK) are derived, and a diversity order of 2 is confirmed to be achieved. The simulation results show that the ODSTNC scheme has good performance, and it is available for the applications of far distance signal transmission between two terminals where channel state information is unknown. Copyright © 2014 John Wiley & Sons, Ltd.     

Performance analysis for relay networks with hierarchical support vector machines

In this paper, we consider a cooperative relay scheme for a mobile network with MIMO technology. The channel capacity for two well‐known relaying schemes are investigated: analogue relaying (amplify and forward) and digital relaying (decode and forward) from a mobile device to the base station through a relay node. In order to further increase the channel capacity, we propose an efficient hierarchical procedure based on support vector machine, namely hierarchical support vector machines (HSVM), to estimate the wireless networks condition approximately and design two ways (matched filter and minimum mean square error filter) of increasing the channel capacity according to the estimated wireless network condition. The proposed HSVM can estimate the wireless networks condition in much shorter time compared with the traditional minimum mean square error scheme without incurring much estimation error, which is spatial, useful for delay sensitive communication. For digital relaying, the effect of imperfect channel decode is also addressed. Our numerical results demonstrate the reduction of estimation complexity by adopting HSVM and the significant improvement of network capacity by applying the matched filter weight at relay nodes according to the network estimation. Copyright © 2011 John Wiley & Sons, Ltd.     

非正交多址中继系统复数域网络编码优化设计

无线中继与网络编码是提高通信系统数据可靠性和吞吐率的重要技术手段,重点研究了单中继非正交多址系统复数域网络编码的优化设计问题.首先,在限制源节点和中继节点的总发送功率并假设各个源节点发送功率相同的条件下,证明了当源节点与中继节点发送功率相等时基于复数域网络编码的单中继非正交多址系统误符号率(SEP)性能最佳.其次,以编码增益为目标函数,提出了一种复数域网络编码的优化设计方法.与已有的复数域网络编码系数设计方法相比,此方法能满足任意源节点个数条件下复数域网络编码系数的优化设计要求,同时可以有效地避免因为网络编码系数选择不当造成信号重叠的现象,提升和改进系统的SEP性能.     

一种基于RIP和帧中继的网络设计

广域网和以太网是两种不同的网络技术,而小型局域网因为其业务多样性和分布离散性,使得其需要兼容不同协议的网络。提出一种基于以太网RIP路由协议和广域网的帧中继协议的网络设计,满足不同协议互通,为不同核心路由器和交换机之间配置RIP路由、静态默认路由和帧中继子接口,最终完成了该网络的布置。     

Nth best relay selection with network coding in two‐way relay systems

In this paper, we propose an Nth best relay selection (Nth‐RS) scheme for analog network coding in two‐way relay systems. In traditional two‐way single‐relay selection schemes, only the best one is selected to forward network‐coded signals. However, in practical applications, the best relay may be unavailable because of the scheduling or overload constraints. In this case, we investigate a more general scheme, where the Nth best but available relay is selected. To evaluate the transmission of reliability, the expression of outage probability in exponential–integral form and its asymptotic expression in closed form are presented. Moreover, the upper bound and lower bound of outage probability are also derived. The analysis reveals that the diversity order of Nth‐RS equals to (M ? N + 1), where M is the number of relay nodes, and the results are verified by simulations. In order to improve system performance, transmit power between sources and relay is optimally allocated to minimize the upper bound of outage probability under total power constraint. Simulation results show that Nth‐RS scheme with proposed power allocation can achieve substantial improvement over equal power allocation scheme. Copyright © 2012 John Wiley & Sons, Ltd.     

On the capacity of the state‐dependent interference relay channel

This paper considers the state‐dependent interference relay channel (SIRC) in which one of the two users may operate as a secondary user and the relay has a noncausal access to the signals from both users. For discrete memoryless SIRC, we first establish the achievable rate region by carefully merging Han‐Kobayashi rate splitting encoding technique, superposition encoding, and Gelfand‐Pinsker encoding technique. Then, based on the achievable rate region that we derive, the capacity of the SIRC is established in many different scenarios including (a) the weak interference regime, (b) the strong interference regime, and (c) the very strong interference regime. This means that our capacity results contain all available known results in the literature. Next, the achievable rate region and the associated capacity results are also evaluated in the case of additive Gaussian noise. Additionally, many numerical examples are investigated to show the value of our theoretical derivations.     

中继蜂窝网络中动态无线资源分配方案

提出一种中继蜂窝网络中基于动态复用分割的无线资源分配方案。该方案在所设计的帧结构基础上,从时间域和频率域进行联合的资源分配。其基本思想是通过小区间的协作使频带资源可以最有效的复用来提高系统性能。仿真结果论证了该方案在小区容量方面可以获得较大的增益。     

分布式发电对配电网继电保护的影响分析

本文对分布式发电进行研究,分析其对配电网继电保护的影响.