Cooperative Diversity Protocols Research Articles

Shortest Propagation Delay-Based Relay Selection for Underwater Acoustic Sensor Networks

Underwater acoustic sensor networks (UASNs) have recently attracted considerable attention because of the numerous underwater applications. The propagation delay, however, is the most challenging factor for successful communication in UASNs. This article presents a cooperative communication scheme for reliable transmission in UASNs. To cope with packet collision caused due to propagation delay, we propose an adaptive control packet collision avoidance (ACP-CA) scheme to avoid collision of control packets during the communication channel reservation phase (CCRP). Moreover, to reduce a collision between data packets, we propose a relay selection scheme, called the shortest propagation delay-based relay selection (SPD-RS), to select the best relay node (R) for re-transmission in the data transmission phase (DTP). We evaluate the proposed scheme performance in terms of network throughput, average packet success rate, average packet drop rate, and latency. Compared to opportunistic cooperative diversity (OCD) and conventional medium access protocol (CMAP), the proposed scheme performs remarkably well by improving the network throughput and packet success rate, reducing the packet drop rate, and minimizing the latency.

Cooperative Diversity Selection Protocol Using Pareto Method with Multi Objective Criterion in Wireless Ad Hoc Networks

In cooperative diversity of ad hoc networks, the selection of the path pair becomes very important to achieve optimum performance. In this paper, it was created the cooperative diversity protocol by using Pareto method for multi objective criteria problems namely the signal to noise ratio (SNR) and load variance. Pareto method was used to find a nondominated solution by way of Continuously Updated. The non-dominated solution was chosen based on the smallest euclidean distance. The advantage of this protocol is to provide fair and the best path pairs of cooperative diversity. From the simulation results, it was obtained the path pairs for cooperative diversity is path S-11-D and S-28-D selected by the smallest value of euclidean distance that is 0.108 and 0.379. Furthermore, the reliability of protocol with Pareto method was compared with the scalarization method in the form of value of cumulative distribution function (CDF).

Distributed Spatial Modulation: A Cooperative Diversity Protocol for Half-Duplex Relay-Aided Wireless Networks

In this paper, distributed spatial modulation (DSM) is introduced. DSM is a cooperative diversity protocol for multirelay wireless networks, which is based on the concept of spatial modulation (SM). The distinguishable feature of DSM lies in improving the reliability of the source via distributed diversity and by increasing the aggregate throughput of the network since new data is transmitted during each transmission phase. This is achieved by encoding the data transmitted from the source into the spatial positions of the available relays and by exploiting the signal domain to transmit the data of the relays. At the destination, a diversity combiner that is robust to demodulation errors at the relays is proposed, and its end-to-end error probability and achievable diversity are studied. It is mathematically proved that DSM allows the source to achieve second-order diversity. With the aid of Monte Carlo simulations, DSM is compared against state-of-the-art cooperative protocols, and it is shown to provide a better error probability.

Modified Cooperative Subchannel Allocation Algorithms and PSO Based Power Allocation for an Alamouti Decode and Forward Relaying Protocol in Multiuser OFDMA Systems

The present work is a discussion on the performance analysis of Modified Cooperative Subchannel Allocation (CSA) Algorithms which is used in Alamouti Decoded and Forward (Alamouti DF) Relaying Protocol for wireless multi-user Orthogonal Frequency Division Multiplexing Access (OFDMA) systems. In addition, the performance of approximate Symbol Error Rate (SER) for the Alamouti DF Relaying Protocol with the Cooperative Maximum Ratio Combining Technique (C-MRC) is analyzed and compared with SER upper bound. The approximate SER is asymptotically tight bound at higher Signal-to-Noise Ratio (SNR). From the asymptotic tight bound approximate SER, Particle Swarm Optimization (PSO) based Power Allocation (PA) is determined for the Alamouti DF Relaying Protocol. The simulation results suggested that the Modified Throughput based Subchannel Allocation Algorithm achieved an improved throughput of 6% to 33% compared to that of existing cooperative diversity protocol. Further, the Modified Fairness based Subchannel Allocation Algorithm rendered fairness of 7.2% to 17% among the multiuser against the existing cooperative diversity protocol.

Comparison of Cooperative Diversity Protocols in Various Relay Locations through Network Coding

In this paper, the performance of Network Coded (NC) based cooperative network for various relay location over Rayleigh fading channels is studied. Comparisons of Amplify and Forward (AAF), Detect and Forward (DTF) and Decode and forward (DCF) protocols for the proposed system are shown. The performance of relays in AAF, DTF and DCF is analyzed in terms of bit error rate (BER) vs signal to noise ratio (SNR). Matlab is used to build Monte-Carlo link level simulation. The effect of relays at different position is studied.

Predictive relay-selection cooperative diversity in land mobile satellite systems

Cooperative diversity protocols promise a new dimension of diversity that provides better communication by engaging nearby relays in forming a ‘virtual’ array of antennas for combined signal transmission. The current incremental cooperative diversity algorithms incrementally select best relay(s) to cooperate based on the channel quality reported by the relays. However, the algorithms do not take into consideration the fact that the chosen best relay(s) at estimation may not always be the best at the time of communication. This is due to the time delay between the relay selection and its transmission of signal (problem of outdated channel quality information (CQI)). To solve this problem, the concept of channel prediction is introduced and employed whereby each relay determines a predicted value of its CQI based on its past measurements. The paper therefore develops a novel predictive relay-selection (PRS) cooperative diversity model that seeks to improve land mobile satellite communication through prediction protocols. In the model, the chosen best relay is the one with the best predicted CQI value instead of the traditional outdated one. Performance analysis of outage probability and average bit error probability for the newly developed PRS cooperation shows that the PRS cooperation is better than direct and outdated CQI relay communication. Copyright © 2015 John Wiley & Sons, Ltd.

A SURVEY ON INCREMENTAL RELAYING PROTOCOLS IN COOPERATIVE COMMUNICATION

Cooperative communication is one of the latest techniques in wireless communication to form virtual antenna arrays. Cooperative communication is an alternative method for MIMO (Multiple input multiple output) system. This scheme assumes TDMA (Time division multiple access) channel accessing and divides the communication into two phases which includes direct transmission and retransmission by the relay terminal. A few cooperative diversity protocols ,for example fixed relaying, selection relaying and incremental relaying are used in order to perform different sorts of processing by the relay terminals, and combining at the destination terminals. Each diversity protocol exhibits its own unique performance. Fixed relaying can be further classified into amplify and forward (AF) relaying and decode and forward (DF) relaying. In AF , relay users amplifies the signal and retransmits it, and in the case of DF, the relay users decodes and retransmits the signal. The Selection relaying is performed by taking the fading coefficient into account. In this report, the recent works on incremental relaying protocol has been summarized. Incremental relaying is based on the feedback mechanism. In this scheme, relay users perform retransmission only if needed, based on the received SNR (Signal to noise ratio) or decoding error that occurs during direct transmission. It is used in cooperative communication in order to attain efficient use of degrees of freedom and to overcome bandwidth inefficiency. The authors have presented a number of protocols such as Incremental selection amplify and forward (ISAF), Joint incremental selection relaying (JISR), Fractional Incremental relaying (FIR), Selective Fractional Incremental relaying (SFIR) and Efficient Incremental relaying (EIR).

Outage probability analysis of space–time block coding‐orthogonal frequency division multiplexing cooperative systems

In this study, the performance of a multi-carrier (MC) multi-relay system with multi-antenna at source and destination nodes is investigated based on Alamouti space–time block coding (STBC) and amplify-and-forward (AF) cooperative diversity protocol with different schemes. In particular, transmission of each STBC in the system is initiated by signal broadcasting from the source node to the destination node and all the relay nodes. Depending on the cooperative scheme, one or more relays, applying AF protocol, transmit the signal to the destination. Applying maximum ratio combination technique to both the direct and the relayed subcarriers at the destination, the outage probability bounds are analytically derived for various schemes of relaying. Simulation results confirm the validity of the derived bounds, and show that the cooperative MC-multiple-input–multiple-output channel yields a notable outage performance with an acceptable capacity, especially in the average best relay selection scheme, which exploits the limited feedback.

On the Achievable Diversity of Repetition-Based and Relay Selection Network-Coded Cooperation

In this paper, we provide a mathematical framework for the analysis, design, and optimization of network-coded cooperative diversity (NCCD) protocols. The analysis is applicable to relay-aided protocols based on the error propagation model, which rely on appropriately designed diversity-combining demodulators at the destination. Wireless networks with an arbitrary number of sources and relays are considered. Arbitrary multilevel modulation schemes and network codes constructed over a non-binary Galois field (GF) are analyzed. NCCD protocols based on repetition-based and relay selection cooperation are investigated. Two takeaway messages emerge from our analysis: 1) repetition-based NCCD protocols are capable of achieving full-diversity, e.g., if the GF size is sufficiently large and the network code satisfies the maximum distance separable (MDS) property; and 2) NCCD protocols based on relay selection are capable of achieving full-diversity under more restrictive assumptions than repetition-based protocols, e.g., if the number of active relays is no fewer than the number of sources and an MDS network code is used.

Finite‐SNR diversity‐multiplexing trade‐off of inter‐vehicular cooperative diversity protocols

The finite-signal-to-noise ratio (SNR) diversity-multiplexing trade-off (DMT) of cooperative diversity protocols are investigated in vehicular networks based on cascaded Rayleigh fading. Lower bounds of DMT at finite SNR for orthogonal and non-orthogonal protocols are derived. The results showcase the first look into the achievable DMT trade-off of cooperative diversity in volatile vehicular environments. It is shown that the diversity gains are significantly suboptimal at realistic SNRs.

Extended low‐density parity‐check codes for feedback‐based cooperative diversity schemes

Cooperative diversity or user cooperation achieves the diversity gain without adding physical antennas to the users or mobile stations. The users work in a cooperative fashion by using their single antennas to create a virtual transmit diversity, called relay diversity or cooperative diversity. The diversity gain achieved by cooperative diversity can be further improved using error correction codes. Low-density parity-check (LDPC) codes are linear block codes with good error correction capabilities. The authors present a novel approach using extended LDPC codes to increase the diversity gain in cooperative diversity. The authors also compare the extended LDPC codes with the punctured LDPC codes in a cooperative diversity and show that there is a performance–complexity tradeoff between the punctured and the extended LDPC codes in the cooperative diversity. Furthermore, the authors will propose two feedback-based protocols for cooperative diversity and compare their throughput with non-feedback-based cooperative diversity using extended LDPC codes.

MAC Protocols for Cooperative Diversity in Wireless LANs and Wireless Sensor Networks

In this paper, we present a survey of cooperative diversity-enabled Medium Access Control (MAC) protocols for Wireless LANs (WLANs) and Wireless Sensor Networks (WSNs). Cooperative diversity has emerged as a promising technique to combat fading and improve reliability in a wireless environment. In cooperative diversity protocols, neighboring nodes act as virtual multiple-input-multiple-output (VMIMO) systems, where they cooperate with the transmitter-receiver pair to deliver multiple copies of a packet to the receiver via independent fading channels. These multiple copies of the same packet can be combined at the receiver to recover the original packet, thus improving reliability by exploiting spatial diversity in the wireless channel. MAC protocols play an important part in realizing this concept by effectively coordinating transmissions between source, partner and destination nodes. Cooperative MAC protocols can also collect channel state information (CSI) between neighboring nodes and provide this information to the routing layer, where it can be exploited for partner selection. For this reason, the research community has proposed a large number of cooperative MAC protocols to realize this concept. We present an overview of these protocols and discuss their handshaking schemes, medium access schemes, results, strengths, and any observed shortcomings.

Error Performance and Diversity Analysis of Multi-Source Multi-Relay Wireless Networks with Binary Network Coding and Cooperative MRC

In this paper, we contribute to the theoretical understanding, the design, and the performance evaluation of multi—source multi—relay network—coded cooperative diversity protocols. These protocols are useful to counteract the spectral inefficiency of repetition—based cooperation. We provide a general analytical framework for analysis and design of wireless networks using the Demodulate—and—Forward (DemF) protocol with binary Network Coding (NC) at the relays and Cooperative Maximal Ratio Combining (C—MRC) at the destination. Our system model encompasses an arbitrary number of relays which offer two cooperation levels: i) full—cooperative relays, which postpone the transmission of their own data frames to help the transmission of the sources via DemF relaying and binary NC; and ii) partial—cooperative relays, which exploit NC to transmit their own data frames along with the packets received from the sources. The relays can apply NC on different subsets of sources, which is shown to provide the sources with unequal diversity orders. Guidelines to choose the packets to be combined, i.e., the network code, to achieve the desired diversity order are given. Our study shows that partial—cooperative relays provide no contribution to the diversity order of the sources. Theoretical findings and design guidelines are validated through extensive Monte Carlo simulations.

Performance analysis of hybrid decode-amplify-forward incremental relaying cooperative diversity protocol using SNR-based relay selection

In this paper, we propose a hybrid decode-amplify-forward incremental cooperative diversity protocol using SNR-based relay selection. In the proposed protocol, whenever destination unsuccessfully receives the source's signal, one of relays that exploit hybrid decode-amplify-forward technique is chosen to retransmit the signal. We derive approximate closed-form expressions of outage probability and average channel capacity. MonteCarlo simulations are presented to verify the theoretical results and compare the performance of the proposed protocol with the direct transmission protocol and conventional incremental relaying protocols.

Delay Optimal Scheduling for Cognitive Radios with Cooperative Beamforming: A Structured Matrix-Geometric Method

There have been increasing interests in integrating cooperative diversity into Cognitive Radios (CRs). However, conventional cooperative diversity protocols require at least two randomly available idle timeslots or temporal spectrum holes for one transmission, thus leading to limited throughput and/or large latency. In this paper, we propose a novel cross-layer approach for efficient scheduling in CR systems with bursty secondary traffics. Specifically, cooperative beamforming is exploited for Secondary Users (SUs) to access busy timeslots or spatial spectrum holes without causing interference to primary users. We first propose a basic cooperative beaMforming and Automatic repeat request aided oppoRtunistic speCtrum scHeduling (MARCH) scheme to balance available spectrum resources, namely temporal and spatial spectrum holes, between the source and the relays. To analyze the proposed scheme, we develop a tandem queuing framework, which captures bursty traffic arrival, dynamic availability of spectrum holes, and time-varying channel fading. The stable throughput region and the average delay are characterized using a structured matrix-analytical method. We then obtain delay optimal scheduling schemes for various scenarios by jointly optimizing the scheduling parameters. Finally, we propose a modified scheme, MARCH-IR, which combines MARCH with Incremental Relay selection to further improve the system performance. Simulation results reveal that the proposed schemes provide significant Quality of Service (QoS) gains over conventional scheduling schemes that access only temporal spectrum holes.

Multilevel Coded Cooperation for Multiple Sources

This paper proposes a novel cooperative diversity protocol using multilevel coded (MLC) modulation, which aims at wireless networks composed of more than two cooperative nodes. If the time-division (TD) based cooperative diversity is applied to the case of multiple sources, its transmission efficiency decreases in proportion to the number of sources which results in the degradation of performance. Although several cooperative diversity protocols based on symbol superposition have been proposed to overcome this inherent degradation, most of them are designed for a two-node cooperation and their complexity increases exponentially with the number of cooperating nodes. To the contrary, the proposed MLC cooperation takes advantage of the simplicity of MLC structure and allows a flexible design, without exponential increase of overall complexity. We introduce two rate allocation design criteria, i.e., minimum outage probability and maximum transmission rate, and demonstrate the advantages of the MLC cooperation in terms of outage probability and frame error rate (FER) performance.

Cooperative Diversity With Mobile Nodes: Capacity Outage Rate and Duration

The outage probability is an important performance measure for cooperative diversity schemes. However, in mobile environments, the outage probability does not completely describe the behavior of cooperative diversity schemes since the mobility of the involved nodes introduces variations in the channel gains. As a result, the capacity outage events are correlated in time and second-order statistical parameters of the achievable information-theoretic capacity such as the average capacity outage rate (AOR) and the average capacity outage duration (AOD) are required to obtain a more complete description of the properties of cooperative diversity protocols. In this paper, assuming slow Rayleigh fading, we derive exact expressions for the AOR and the AOD of three well-known cooperative diversity protocols: variable-gain amplify-and-forward, decode-and-forward, and selection decode-and-forward relaying. Furthermore, we develop asymptotically tight high signal-to-noise ratio (SNR) approximations, which offer important insights into the influence of various system and channel parameters on the AOR and AOD. In particular, we show that on a double-logarithmic scale, similar to the outage probability, the AOR asymptotically decays with the SNR with a slope that depends on the diversity gain of the cooperative protocol, whereas the AOD asymptotically decays with a slope of -1/2 independent of the diversity gain.

Multi-relay cooperative diversity protocol with improved spectral efficiency

Cooperative diversity protocols have attracted a great deal of attention since they are thought to be capable of providing diversity multiplexing tradeoff among single antenna wireless de- vices. In the high signal-to-noise ratio (SNR) region, cooperation is rarely required; hence, the spectral efficiency of the cooperative protocol can be improved by applying a proper cooperation selection technique. In this paper, we present a simple "cooperation selection" technique based on instantaneous channel measurement to improve the spectral efficiency of cooperative protocols. We show that the same instantaneous channel measurement can also be used for relay selection. In this paper two protocols are proposed-proactive and reactive; the selection of one of these protocols depends on whether the decision of cooperation selection is made before or after the transmission of the source. These protocols can successfully select cooperation along with the best relay from a set of available M relays. If the instantaneous source-to- destination channel is strong enough to support the system requirements, then the source simply transmits to the destination as a non- cooperative direct transmission; otherwise, a cooperative transmission with the help of the selected best relay is chosen by the system. Analysis and simulation results show that these protocols can achieve higher order diversity with improved spectral efficiency, i.e., a higher diversity-multiplexing tradeoff in a slow-fading environment.

Code Combining Cooperative Diversity in Long-haul Transmission of Cluster based Wireless Sensor Networks

A simple modification of well known Low Energy Adaptive Clustering Hierarchy (LEACH) protocol is proposed to exploit cooperative diversity. Instead of selecting a single cluster-head, we propose M cluster-heads in each cluster to obtain a diversity of order M. The cluster-heads gather data from all the sensor nodes within the cluster using same technique as LEACH. Cluster-heads transmit gathered data cooperatively towards the destination or higher order cluster-head. We propose a code combining based cooperative diversity protocol which is similar to coded cooperation that maximizes the performance of the proposed cooperative LEACH protocol. The implementation of the proposed cooperative strategy is analyzed. We develop the upper bounds on bit error rate (BER) and frame error rate (FER) for our proposal. Space time block codes (STBC) are also a suitable candidate for our proposal. In this paper, we argue that the STBC performs worse than the code combining cooperation.

Cognitive Cooperation for the Downlink of Frequency Reuse Small Cells

We develop a cooperative diversity protocol coded over space, time, and frequency to achieve improved quality of service for mobile users in the downlink of small-cell frequency reuse networks. The proposed protocol, called cooperative frequency reuse (CFR), leverages the cellular frequency reuse concept to create space and frequency diversity among pairs of adjacent base stations. The CFR protocol is compatible with the half-duplex mode and is distributed in the sense that each base station acts in autonomy, without the need of a centralized entity. It is implemented in two phases. During the first phase, each base station independently serves its own users on its dedicated frequency band. It simultaneously listens to the symbols transmitted by neighboring base stations. Cognitive cooperation is introduced in the second phase, where each base station transmits on two frequency bands to the scheduled users in both base stations, by means of an appropriately chosen distributed space time code based on the Golden code. We analyze and discuss the performance of the proposed protocol in terms of bit error rate, probability of outage, and ergodic sum rate under different scenarios. Simulation results show that the proposed protocol yields considerable improvement over direct transmission frequency reuse strategies.