Top PDF Secrecy Cooperative Networks With Outdated Relay Selection Over Correlated Fading Channels

Secrecy Cooperative Networks With Outdated Relay Selection Over Correlated Fading Channels

Secrecy Cooperative Networks With Outdated Relay Selection Over Correlated Fading Channels

Due to the broadcast nature, wireless transmission may be overheard by eavesdroppers in the network, and the severe issue of information leakage arises [1]. To prevent the wiretap, encryption algorithms and the concept of physical-layer secu- rity (PLS) have been presented in the literature. Specifically, in the pioneering work of Wyner [2], the wiretap channel model was firstly proposed. Several researchers extended this approach to fading channels and studied important metrics, such as the secrecy capacity and the secrecy outage probability (SOP) [3]–[7]. Furthermore, as relaying is a promising tech- nique for the next-generation communication networks, it is of vital importance to investigate the PLS of relaying systems. For amplify-and-forward (AF) and decode-and-forward (DF) relaying, the secrecy performance has been studied by deriv- ing analytical expression of SOP in [8]–[10]. Moreover, the asymptotic SOP with high main-to-eavesdropper ratio (MER) was provided, in order to obtain insights on the system design. In most of the works in the open literature, the eavesdrop- ping and the main channels are assumed to be statistically independent. However, this ideal assumption may not hold in practice due to reasons such as antenna deployment, proximity of the legitimate receiver and eavesdropper, and scattering environments. The impact of channel correlation between the main and eavesdropping links on the secrecy performance was studied in [11], [12], where it was found that the channel correlation is harmful to the transmission security, especially in the low MER region. In order to enhance the security, op- portunistic selection is an effective technique, which exploits the channel fluctuation between antennas, users and relays [9], [13]. The selection can be implemented in a centralized or distributed manner through dedicated feedback links, which may take some time to complete. However, in time-varying environments, channels may vary from the instant of selection to that of actual data transmission. This results in the selection based on outdated channel state information (CSI) [14] and the best relay is not always selected [15], [16].
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On the Outage Performance of Partial Relay Selection Aided NOMA System with Energy Harvesting and Outdated CSI Over Non-Identical Channels

On the Outage Performance of Partial Relay Selection Aided NOMA System with Energy Harvesting and Outdated CSI Over Non-Identical Channels

a cooperative NOMA downlink network is investigated over Nakagami- m fading channels with channel estimation errors in [4]. The authors considered direct links between the source and users. However, all these aforementioned existing works on cooperatively NOMA relaying systems were specifically limited to a single relay node. Under multiple relays deployment, attention has been given to different relay selection schemes which significantly improve the system performance. A dual-hop AF-NOMA relaying network with partial relay selection protocol over Nakagami- m fading channels was studied. In [9], the performance of NOMA schemes with partial relay selection was investigated, and direct link was considered between the source and users.
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Mitigating PAPR in cooperative wireless networks with frequency selective channels and relay selection

Mitigating PAPR in cooperative wireless networks with frequency selective channels and relay selection

Diversity techniques are effective means for combating the detrimen- tal effects of broadband wireless channel fading. It is well known that MIMO systems can potentially significantly improve the reliability of communication over fading channels using space time block coding [63]. However, it is difficult to equip small mobile units with more than one antenna due to size and cost constraints. In this case, transmit diversity can generally only be achieved through cooperative multi-node trans- mission which is known as cooperative diversity [15], where one or more relay nodes are used to forward signals transmitted from the source node to the destination node. In a cooperative communication system, there are two main cooperative methods: decode-and-forward (DF) and amplify-and-forward (AF). Cooperative multi-node diversity schemes can be exploited by using a virtual MIMO-OFDM system. Therefore, this technique has received much attention in recent years [43] due to certain advantages such as high bandwidth efficiency and its robustness to multi-path fading channels. Closed loop extended orthogonal space frequency block coding (EO-SFBC) allows four relays to communicate cooperatively with a common destination as a virtual frequency selec- tive MIMO-OFDM system.
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Performance of Nth Worst Full Duplex Relay Selection over Nakagami M Fading Channels

Performance of Nth Worst Full Duplex Relay Selection over Nakagami M Fading Channels

scheme is an efficient approach to achieve space diversity and hardware simplic- ity. Relay selection problem in AF cooperative system has been studied in [4], the authors considered dynamically switches between FD and HD relaying based on the instantaneous quality of the loop interference, and they showed that the diversity gain can be significantly improved by employing multiple FD relays. In [5], the opportunistic decode-and-forward (DF) relay selection with FD scheme has been studied. Optimal DF relay selection for FD mode in underlay cognitive radio networks has been studied in [7], in which an optimum relay-selection so- lution for treating the tradeoff between the improved outage probability and the performance degradation can always be achievable within the signal-to-noise ra- tio (SNR) range of (10 dB, 15 dB).
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Relay Optimization for ANC and PNC over Rician Fading Channels

Relay Optimization for ANC and PNC over Rician Fading Channels

Co-operation and network coding are two such powerful techniques that heightened the proficiency of wireless Networks. This paper mainly focuses on Physical-layer Network Coding (PNC) and Analog Network Coding (ANC), as they are the most studied variants of network coding in literature and represent radically different strategies between themselves, thus shedding light into which problems may hinder the scalability of network coding to more better wireless network topologies. Also, performance of cooperative networks can be enhanced with optimum relay selection. In this paper, we present the simulation results for both Analog Network Coding and Physical-layer Network Coding. We have evaluated the bit error rate (BER) over Rician fading channelsfor ANC and PNC with relay optimization by taking path loss in our system model. BPSK modulation is used for simulation results.
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Relay selection in cooperative networks with frequency selective fading

Relay selection in cooperative networks with frequency selective fading

Cooperative relay systems with orthogonal channels typically either employ multiple orthogonal relay subchan- nels in conjunction with repetition coding, or all relays use a single orthogonal relay channel along with distributed space-time coding (DSTC) [7]. While the use of repetition codes is attractive for its simplicity, this approach requires relay scheduling and dedicated orthogonal channels for each relay which uses up precious system resources. On the other hand, when using a single orthogonal relay chan- nel with DSTC, the scheduling of relays is of no concern, but DSTC requires synchronization between relays which is very difficult in distributed networks. Asynchronous forms of space-time coding have been proposed (e.g. [8]), but the decoding complexity may still be prohibitively complex to permit their use in low-cost wireless ad hoc networks. Furthermore, the non-linearity of most existing RF front-ends poses additional implementation challenges for DSTC-based approaches [9].
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A Review on Multiple Relay Selection Scheme for Cooperative Relay Networks

A Review on Multiple Relay Selection Scheme for Cooperative Relay Networks

There are several types of diversity techniques that have been popularly employed to combat fading in wireless networks. These include temporal diversity, and spatial diversity. While temporal diversity techniques transmit multiple copies of the transmitted signal at different time instants, frequency diversity techniques spread the transmitted signal across different frequency channels or across multiple frequency carriers in a wide spectrum. Spatial diversity techniques on the other hand have received the widest attention compared to other popular diversity techniques. Spatial diversity is achieved by propagating independent versions of the transmitted signal over multiple transmit antennas, or employing multiple receive antennas to recover the transmitted signal. When multiple antennas are used at the transmitter it is referred to as transmit diversity. Conversely, when multiple receive antennas are employed at the receiver it is referred to as receive diversity. Spatial diversity techniques have been well exploited by multiple-input multiple-output (MIMO) systems. MIMO systems, also, referred to as multiple- antenna systems, improve the robustness and reliability of communication by employing multiple transmit and/or multiple receive antennas, and utilizing spatial diversity techniques. In order to reap the benefits of spatial diversity, the multiple antennas need to be spaced sufficiently far apart, usually antenna separation of at least a few wavelengths is required to guarantee spatial diversity.
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Continuous transmit in cognitive radio systems: outage performance of selection decode and forward relay networks over Nakagami m fading channels

Continuous transmit in cognitive radio systems: outage performance of selection decode and forward relay networks over Nakagami m fading channels

Motivated by cooperative communications and our results in [17,18], in this paper, we extend our strategy ‘AT’ (the cognitive source (CS) will be able to transmit over all time slots and in any time slot, then, it will be able to operate continuously whenever either the primary user is active or absent) into cognitive relay selection. We derive the closed form of outage probability of relay selec- tion in dual-hop transmission over independent but not necessarily identically distributed (i.n.i.d.) Nakagami-m channels, with integer values of fading severity parameter m.
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Outage Performance of Cognitive Relay Networks with Best Relay Selection in Nakagami m Channels

Outage Performance of Cognitive Relay Networks with Best Relay Selection in Nakagami m Channels

Cooperative technology, emerging as a new spatial diversity technique, can effectively combat fading and improve the throughput. However, the advantages of such system achieve at the expense of a reduction in spectral efficiency. As such, relay selection has been investigated [6,7] to overcome this shortcoming. Re- cently, cooperation also has great potential to be used in cognitive radio networks, known as cognitive relay net- works (CRNs) [8-14]. In [11], the exact outage probabil- ity of an underlay CRNs using DF relaying with multiple PUs in Rayleigh fading channels has been derived. Most
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A Novel Relay Selection Strategy for Two User Cooperative Relaying Networks

A Novel Relay Selection Strategy for Two User Cooperative Relaying Networks

Cooperative communication has recently to become known as a promising technique to combat fading in wireless networks.substantially, cooperative communication takes benefit of the broadcast characteristic of wireless channels. It has been established that cooperation in wireless communications in an significant manner can improve the link quality by exploiting the spatial diversity of multiple terminals [1] –[3]. Cooperative techniques are promising candidates for prominent wireless networks.

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Cooperative relay selection based UEP scheme for 3D video transmission over Rayleigh fading channel

Cooperative relay selection based UEP scheme for 3D video transmission over Rayleigh fading channel

3D video has received increased attention during the last years due to the recent advances in capturing, coding, and display technologies and it is anticipated that the 3D video applications will increase rapidly in the near future. One of the most popular and widely used formats for representing 3DV is video plus depth (V+D) [1]. In Depth Image Based Rendering [DIBR] technique [2], depth map are required to generated good quality of 3D video but does not need to be significantly high to render 3D scene unlike color sequence. Color and depth images need to be transmitted over communication channels to the end user for display. However, the color sequence is directly viewed by the user. Therefore, in trans- mission, if the color sequence is lost, it will be degraded 3D video quality than the loss of depth sequence. Transmitting 3D video over networks such as the Internet and wireless networks presents new challenges and consumer applications will not gain much popularity unless the transmission problem of 3D video is addressed. However, transmission of 3D video contents is expected to be the next big revolution in multimedia applications.
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Relay Selection in Cooperative Networks with Frequency Selective Fading

Relay Selection in Cooperative Networks with Frequency Selective Fading

Cooperative relay systems with orthogonal channels typically either employ multiple orthogonal relay subchan- nels in conjunction with repetition coding, or all relays use a single orthogonal relay channel along with distributed space-time coding (DSTC) [7]. While the use of repetition codes is attractive for its simplicity, this approach requires relay scheduling and dedicated orthogonal channels for each relay which uses up precious system resources. On the other hand, when using a single orthogonal relay chan- nel with DSTC, the scheduling of relays is of no concern, but DSTC requires synchronization between relays which is very difficult in distributed networks. Asynchronous forms of space-time coding have been proposed (e.g. [8]), but the decoding complexity may still be prohibitively complex to permit their use in low-cost wireless ad hoc networks. Furthermore, the non-linearity of most existing RF front-ends poses additional implementation challenges for DSTC-based approaches [9].
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Performance analysis of relay selection in cooperative networks over Rayleigh flat fading channels

Performance analysis of relay selection in cooperative networks over Rayleigh flat fading channels

versions of the signal and can make better decision on the detection of the transmitted information. In DF, the received noisy message at the relay is decoded first, and then the relay re-encodes the decoded message, and for- wards it to the destination node. In the case of accurate symbol estimation, DF outperforms AF relaying, where the relay can reliably decode the source node message as the noise will not be amplified [5-8]. Diversity order two is achieved at high signal to noise ratio (SNR) using one relay for AF and adaptive DF schemes, using maximum ratio combining (MRC) technique to demodulate the received signals. In adaptive DF, the relay transmits if it decodes the message correctly (e.g., by using cyclic redundancy check), or otherwise keeps silent [9,10]. In common coop- erative diversity networks with N relaying nodes, N + 1 orthogonal channels or time slots are used to provide N + 1 diversity order, which encounters bandwidth penalty [11-14]. In [15], opportunistic best relay selection is used to utilize the resources efficiently; only two channels or time slots are required despite the number of relays, while maintaining a full diversity order N + 1, when the best relay is only used. Laneman et al. [3] proved that best relay selection achieves full diversity order for AF and DF cooperation schemes under flat fading Rayleigh chan- nels. In there, the performance was measured in terms of the outage events and the associated outage probabilities. Different criteria for relay selection are investigated with their achievable diversity order in [16]. The average sym- bol error probability (SEP) of the cooperative system is used to analyze the performance of various systems and channel models as in [8].
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Performance of Multiple-Relay Cooperative Diversity Systems with Best Relay Selection over Rayleigh Fading Channels

Performance of Multiple-Relay Cooperative Diversity Systems with Best Relay Selection over Rayleigh Fading Channels

The best-relay selection scheme for cooperative networks has been introduced in [7], and the authors showed that this scheme has the same diversity order as the regular cooperative diversity in terms of the capacity outage. How- ever, this important result was given using semianalytical asymptotic analysis at high SNR (without deriving a closed- form expression for the capacity outage). In [8], the authors presented an asymptotic analysis (at high SNR values) only of the symbol error probability of amplify-and-forward best- relay selection scheme, and compared it with the regular cooperative systems. The authors showed that best-relay selection scheme maintains full diversity order in terms of the symbol error probability. In [9], the authors analyzed the capacity outage probability of the best-relay selection scheme with decode-and-forward, and they showed that it outperforms distributed spacetime codes for network with more than three relaying nodes. This gain is due to the efficient use of power by the best-relay selection scheme networks. However, to the best of our knowledge, no one has derived closed-form expressions for the symbol error probability and capacity outage of the cooperative diversity network using the best-relay selection scheme at any SNR (not only high SNR values).
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Outage probability of fixed gain dual hop relay selection channels with heterogeneous fading

Outage probability of fixed gain dual hop relay selection channels with heterogeneous fading

The paradigm of cooperative communication has been shown to provide significant advantages in cellular net- works (and many other applications) for more than a decade [1]. With the deployment of LTE networks across the world in recent years [2] and the shifting of focus in the research community to 5G cellular technology [3], the ideas surrounding cooperative communication are evolv- ing. Of particular interest in the discussion of 5G is relay- aided communication. The heterogeneous structure of 5G networks will consist of layers of macrocells, small cells, relays, and device-to-device (D2D) networks [4]. In areas lacking a wired backhaul infrastructure, relays are, and will continue to be, deployed to act as picocell base sta- tions to local user equipments (UEs) and to mimic (for the most part) a UE in the view of the macrocell base station. Within the D2D networking paradigm, relays will form a key component in the control infrastructure of a 5G network, linking D2D networks to the macrocell base sta- tion [4]. This idea can be further extended to connect D2D
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Cooperative Diversity Analysis using DF Relay Network over Rayleigh Fading Channel

Cooperative Diversity Analysis using DF Relay Network over Rayleigh Fading Channel

Transmission over wireless channel suffers with random fluctuation in signal level known as fading and from cochannel interference [1]. Diversity is a very powerful technique to mitigate fading and improve robustness to interference. Cooperative relaying has been adopted as an effective strategy to improve network capacity and link reliability in emerging standards, such as long term evolution-advanced (LTE-A) and IEEE802.1m [2].

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To Enhance the Performance of Relay Based Cooperative Spectrum Sensing In Cognitive Radio Networks over Nakagami-M-Channels

To Enhance the Performance of Relay Based Cooperative Spectrum Sensing In Cognitive Radio Networks over Nakagami-M-Channels

Jian Li et al. [7] Proposed modeling of interference co-channel in wireless networks of cognitive. The technology called cognitive radio shares the bands of frequency which are underutilized and whose license is with primary users. However, due to problem of uncertainty in primary user detection, the possibility of interference of secondary user with primary user is there when both users are simultaneously active. So, interference consequences are very accurate is proposed by the researchers for the description of this co-channel interference along with .pdf, .cdf variance, mean of the above interference faced by primary users. The model which is proposed keeps many factors into account like scheme of spectrum sensing, secondary users spatial distribution and condition of channel which include fading Nakagami and shadowing. Also mathematical expression of influences which is exact is also given from these factors. Many practical applications are there of this framework like cognitive network evaluation of any shape and secondary users density and also power control methods and spectrum sensing methods used by secondary users. To check the effectiveness of method used, simulation results are provided.
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Multiuser diversity in correlated Rayleigh fading channels

Multiuser diversity in correlated Rayleigh fading channels

Employment of adaptive modulation and scheduling leads to substantial performance improvement in multiu- ser systems, normally called multiuser diversity [1-12]. This is the main motivation for the current scheduling- based systems and this article as well. In these methods, the transmitter is provided with some information about the channel quality of different users. This information is then utilized by a scheduler to select the appropriate users, coding, and modulation such that an objective function is optimized. System throughput and fairness between the users are two objective functions mainly considered in the literature. Furthermore, depending on the number of users, channels characteristics and the feedback load resources, the transmitter information about the channels quality can be perfect or imperfect.
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Application of non orthogonal multiple access in cooperative spectrum sharing networks over Nakagami m fading channels

Application of non orthogonal multiple access in cooperative spectrum sharing networks over Nakagami m fading channels

Abstract—This paper proposes a novel non-orthogonal multi- ple access (NOMA)-based cooperative transmission scheme for a spectrum-sharing cognitive radio network, whereby a secondary transmitter (ST) serves as a relay and helps transmit the primary and secondary messages simultaneously with employing NOMA signaling. This cooperation is particularly useful when the ST has good channel conditions to a primary receiver but lacks of the radio spectrum. To evaluate the performance of the proposed scheme, the outage probability and system throughput for the primary and secondary networks are derived in closed forms. Simulation results demonstrate the superior performance gains for both networks thanks to the use of the proposed NOMA- based cooperative transmission scheme. It is also revealed that NOMA outperforms conventional orthogonal multiple access and achieves better spectrum utilization.
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Performance Analysis of SSC Diversity Receivers over Correlated Ricean Fading Satellite Channels

Performance Analysis of SSC Diversity Receivers over Correlated Ricean Fading Satellite Channels

single integrals. In [8] the cumulative distribution functions (CDF) of SC, in correlated Rayleigh, Ricean, and Nakagami- m fading channels were derived in terms of single-fold in- tegrals and infinite series expressions. In [9] the ABEP of dual-branch EGC and MRC receivers operating over corre- lated Weibull fading channels was obtained. In [10] the per- formance of MRC in nonidentical correlated Weibull fad- ing channels with arbitrary parameters was evaluated. In [11] an analysis for the Shannon channel capacity (CC) of dual-branch SC diversity receivers operating over correlated Weibull fading was presented. In [12], infinite series expres- sions for the capacity of dual-branch MRC, EGC, SC, and SSC diversity receivers over Nakagami-m fading channels have been derived.
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