Outage analysis for joint antenna and path selection decode-and-forward relay networks

This paper investigates the joint relay and antenna selection strategy for amplify-and-forward (AF) cognitive radio-inspired non-orthogonal multiple access (CR-NOMA) systems. The outage performance is analyzed for the cooperative CR- NOMA networks over Nakagami-m fading channels. The exact expression for the outage probability is derived in closed-form as well as the asymptotic expression. Based on the analytical results, the impacts of relay numbers, antenna numbers and fading parameters on outage performance are clearly revealed. Finally, simulation results demonstrate that CR-NOMA can meet different users' quality of service (QoS) requirements and achieve superior outage performance over NOMA with fixed power allocation (F-NOMA). Compared with orthogonal multiple access (OMA) relaying networks, CR-NOMA can achieve a significant performance gain and user fairness.

This paper investigates the performance of a two-way decode-and-forward (DF) multi-antenna relay network. A joint antenna selection scheme for all nodes is first proposed based on the maximizing the worse received signal to noise ratio (SNR) of two end users. Then, we derive the probability density function (PDF) and cumulative distribution function (CDF) of the received SNRs of both users. We also achieve the closed-form expressions of average bit error rate (BER) and outage probability of the relay system. Furthermore, we reveal the asymptotic behavior of our system when transmitting SNR or the number of antennas is large. Our analysis shows that the proposed DF antenna selection scheme achieves full diversity. The numerical results finally verify the accuracy of our analysis.

SummaryOne of the main imperfections degrading the performance of full‐duplex (FD) relaying systems is the outage floor. In this work, a power scaling method is proposed, which overcomes this effect even when there does not exist a direct channel between source and destination nodes. The system is composed of decode‐and‐forward (DF) FD relays over the Nakagami‐m fading environment. To promote system performance, joint antenna and relay selection methods are employed in the FD relaying systems. Each FD relay is equipped with multiple antennas for receiving and the other for transmitting the information. The transmitting and receiving antennas are chosen based on the instantaneous channel variations, and one relay is selected to improve the signal‐to‐interference and noise ratio (SINR) of the FD relaying system. The performance of the proposed design is investigated. Moreover, the closed‐form equations of the ergodic capacity and outage probability are attained. The analytical results are confirmed by different simulations. Results indicate that the proposed design achieves an additional spatial diversity gain because of using the antenna selection at the relay nodes. Moreover, by power scaling (PS) method, the system performance is effectively improved compared to the conventional FD relaying structures.

Diversity is an integral technique in the advancement of wireless communications. Multiple-input multiple-output (MIMO) technology continues to occupy a pivotal position in the fourth-generation (4G) standards and beyond. With the advent of full-dimension (FD) MIMO and massive MIMO, new paradigms are being targeted in the disruptive technology. Third-generation partnership project (3GPP) has also emphasized the advanced MIMO technology for achieving its vision of International Mobile Telephony (IMT) 2020. However, implementing multiple antennas can be cumbersome due to limiting factors such as size, cost, and hardware limitations. In such a scenario, where implementing many antennas is not feasible, the benefits of diversity can be reaped by employing cooperative communication. Single antenna mobiles can share their mobile stations giving rise to a virtual MIMO system. In this paper, the authors have analyzed the performance of cooperative mobile stations in a frequency selective channel. Orthogonal frequency division multiplexing (OFDM), known for its robustness against multipath fading, is the modulation technique employed to circumvent the hazardous effects of intersymbol interference (ISI). MIMO is the key technology for achieving capacity advantage and improving link reliability. The blend of these two cutting edge technologies in a cooperative relay system presents encouraging results and inferences. Maximal Ratio Combining (MRC) is employed at the relay and the receiver to maximize the signal-to-noise ratio (SNR). Decode and forward (DF) protocol is used at the relay node owing to its regenerative nature and adaptability. The closed-form expressions for bit error rate (BER) and outage probability (Pout) are derived and compared with the experimental results. The effect of power decay factor is analyzed and simulation is done for 2 × 2, 2 × 3, and 2 × 4 transmit and receive antennas. The number of antennas at the relay is kept as 2. The analytical results agree with the simulation results.

Telecommunications improvements in the last decades have led to an increase in the available data rate and reliability, and to reduce latency. Massive MIMO (mMIMO) has emerged as a promising solution to replace simple antenna setups. This arrangement involves a large number of transmitter antennas compared to the served terminals in the covered area, enabling higher data rates through the key characteristics of mMIMO. Despite its advantages, the utilization of such large arrays is energy-intensive. With fewer antennas, it is possible to achieve high data rates with reduced power consumption. Antenna selection is crucial for energy efficiency while maintaining computational efficiency. Additionally, power allocation in the downlink for each served terminal is an important step to consider. This work aims to propose a joint algorithm for selecting antennas and distributing energy among terminals, simplifying the process through low-complexity algorithms. The results show the penalty in sum-rate capacity for each proposed method. The two proposed algorithms demonstrate an adequate approach to the target value asymptotically as the number of transmitter antennas increases. This implies the possibility of achieving the joint process with significantly lower computational costs compared to perform antenna selection and power allocation separately.

Adaptive beamforming techniques are widely known for their capability of leveraging the performance of antenna arrays. The effectiveness of such techniques typically increases as the number of antennas grows. In contrast, computational and hardware costs very often limit the deployment of beamforming in large-scale arrays. To circumvent this problem, antenna selection strategies have been developed aiming to maintain much of the performance gain obtained by using a large array while keeping computational and hardware costs at acceptable levels. In this context, the present paper is dedicated to the development of two new adaptive algorithms for solving the problem of joint antenna selection and beamforming for uplink reception in mobile communication systems. Both algorithms are based on an alternating optimization strategy and are designed to operate with a limited number of radio-frequency chains. The main difference between the proposed algorithms is that the first is formulated by considering the minimum mean-square error (MMSE) criterion, while the second is based on the minimum-variance distortionless-response (MVDR) approach. The numerical simulation results confirm the effectiveness of the proposed algorithms.

We analyze the performance of a dual-hop downlink cellular amplify-and-forward cooperative system in the presence of both channel estimation errors and radio frequency (RF) impairments, where multiple antennas are deployed only at the base station (BS) and single-antenna at relays and mobile stations (MS). Specifically, we derive approximate as well as exact closed-form expressions for the outage probability and expected spectral efficiency. In addition, simple asymptotic expressions at the high signal-to-noise ratio (SNR) regime are obtained, which facilitate the characterization of the achievable diversity order of the system. To validate the derived analytical expressions, we presented simulation results which are sufficiently tight across the entire range of SNRs. Findings of the paper suggest that full diversity order can be achieved only when the RF front-end hardware is assumed to be perfect, while in practice the imperfections in hardware are inevitable and reduce diversity order of the system. Moreover, the influence of key parameters such as the number of antennas, users, and relays on the system performance has been presented with the influence of the level of RF impairments.

Recently, the use of unmanned aerial vehicles (UAVs) as a relay node has been envisaged as an enabling technology in the upcoming wireless communication era. Thus, in this paper, we consider a full-duplex (FD) cooperative communication system with a source and a destination, where UAV serves as a mobile relay. Here, the transmission power cost is debited to energy harvested using simultaneous wireless information and power transfer (SWIPT) and self-interference energy harvesting (EH) via power-splitting (PS) protocol. In poor channel conditions, UAV uses a soft angular modulation scheme to perceive the soft information. In this proposed system, we present the outage probability over the Nakagami-m fading channels. A closed-form solution for the outage probability is derived. In addition, we formulate an optimization problem to minimize end-to-end outage probability subject of the UAV's power profile. The KKT conditions have been used to obtain a closed-form solution of the proposed optimization problem. Finally, numerical results are provided to evaluate the proposed system under various setups.

In this paper, we consider a multiple-input multiple-output (MIMO) system consisting of one source, one destination and one eavesdropper, where each node is equipped with an arbitrary number of antennas. To improve the security of source-destination transmissions, we investigate the antenna selection at the source and propose the optimal antenna selection (OAS) and suboptimal antenna selection (SAS) schemes, depending on whether the source node has the global channel state information (CSI) of both the main link (from source to destination) and wiretap link (from source to eavesdropper). Also, the traditional space-time transmission (STT) is studied as a benchmark. We evaluate the secrecy performance of STT, SAS, and OAS schemes in terms of the probability of zero secrecy capacity. Furthermore, we examine the generalized secrecy diversity of STT, SAS, and OAS schemes through an asymptotic analysis of the probability of zero secrecy capacity, as the ratio between the average gains of the main and wiretap channels tends to infinity. This is different from the conventional secrecy diversity which assumes an infinite signal-to-noise ratio (SNR) received at the destination under the condition that the eavesdropper has a finite received SNR. It is shown that the generalized secrecy diversity orders of STT, SAS, and OAS schemes are the product of the number of antennas at source and destination. Additionally, numerical results show that the proposed OAS scheme strictly outperforms both the STT and SAS schemes in terms of the probability of zero secrecy capacity.

In this paper, we study the end-to-end performance of multi-hop wireless powered relaying networks cognitively operating with primary networks over Nakagami-m fading channels. Our analysis considers multi-hop wireless powered relaying systems in which all communication nodes harvest energy from a multiple antennas power beacon (PB) to transmit data to multiple destinations in the presence of a multiple antennas primary receiver (PR). Aiming at improving end-to-end system performance, we propose two relay selection schemes, namely data channel based relay selection (DbRS) and interference channel based relay selection (IbRS), under cognitive radio approach. By taking into account the harvested energy and the interference power constraint, we derive the exact closed-form expression for the outage probability (OP) of the proposed schemes, which is then verified by Monte Carlo simulations over Nakagami-m fading channels. The tractable asymptotic OP of each scheme is also provided unveiling several important insights on system characteristics and performance trends. Moreover, we develop the asymptotic upper bounds for the ergodic capacity and bit error rate (BER) of the considered multi-hop relaying network. Numerical results in terms of system OP, ergodic capacity, and average BER performance are provided to demonstrate that DbRS scheme outperforms IbRS one, which by its turn outperforms random relay selection scheme. Finally, the influences of the number of antennas at PB and PR, number of relays in each cluster, number of hops, the PB and PR placements, and time switching ratio on the overall system performance are examined and discussed comprehensively.

The outage performance of dual-hop multiple-input multiple-output (MIMO) decode-and-forward (DF) relay network with partial Nth-best relay selection scheme is investigated. Both the relay and destination are subjected to multiple co-channel interference (CCI) and additive white Gaussian noise (AWGN). Transmit antenna selection with maximal ratio combining (TAS/MRC) is employed to obtain multi-antenna diversity. Exact and asymptotic expressions for the outage probability are derived, which are validated by the Monte Carlo simulations. Our results reveal that the diversity order is determined by the worse hop and directly proportional to the number of antennas at the relay. Specially, only the first hop diversity order is affected by the number of relays and the value of N. In addition, the interference deteriorates the outage performance by reducing the coding gain of the system. These results provide further insights into the practical system design.

This paper examines the effect on Outage probability and Detection probability by using Maximal Ratio Combining (MRC), Square Law Combining (SLC) along with the addition of two relay transmission protocols Amplify and Forward (AF) and Decode and Forward (DF) over Rayleigh Fading Channel. In MRC the co-phased signals with highest Signal to Noise Ratio (SNR) are taken where SLC does not rely on phase estimation. The AF protocol works on the principle that the relay receives the signal and amplifies it along with the noise. In DF, the received signal at relay is decoded and again it is re-encoded before sending it to the destination. Single and multiple relays are taken in different scenarios and the diversity techniques (MRC and SLC) along with the relay transmission protocols (AF and DF) are analyzed. The performance of receiver's parameters, i.e. detection probability (P d ) and Outage probability (P out ) are examined. The simulation results clearly show the performance of the efficient combining scheme with the appropriate relay transmission protocol.

The symbol error rate (SER) and the bit error rate (BER) of orthogonal space-time block codes (OSTBCs) with antenna selection over keyhole fading channels are examined. Considered are receive antenna selection, transmit antenna selection, and joint antenna selection at both the transmitter and the receiver. The exact SERs of OSTBCs for M-PSK and square MQAM constellations are obtained using the technique of moment generating function (MGF). By applying the Bonferroni-type bounds, tight lower and upper bounds for both the SER and BER are provided in closed-form expressions with finite-range single integrals. The bounds can be applied to arbitrary constellations and mappings. Numerical results show that the bounds can be used to provide practically the exact SER and BER over a wide range of the signal-to-noise ratio.

Euclidean distance optimized antenna selection (EDAS) has proven to be able to achieve high transmit diversity gains for spatial modulation (SM) multiple-input multiple-output (MIMO) systems, but the exhaustive search over all possible antenna subsets may result in an intractable search complexity, especially for large-scale MIMO (LS-MIMO) systems. In this paper, a novel EDAS-equivalent criterion, relaying on matrix dimension reduction, is proposed to reduce the search complexity. Based upon this criterion, for small-scale SM-MIMO systems, a pair of transmit antenna selection (TAS) schemes, namely, the tree search based antenna selection (TSAS), and the decremental antenna selection (D-AS) schemes, are developed. Specifically, the TSAS scheme works by iteratively splitting the original Euclidean distance (ED) matrix into submatrices with smaller dimensions. TSAS achieves the same bit error rate (BER) performance as that of the exhaustive search at the cost of exponential search complexity. To address this issue, D-AS is carried out by excluding one specific transmit antenna from all the possible candidates in each iteration based on the channel information. D-AS is able to offer a near-optimal BER performance with a further reduction in terms of the search complexity. Moreover, we extend the D-AS scheme to LS-SM-MIMO systems by sorting all the ED elements with the low-complexity heapsort algorithm. Our simulation results show that the proposed D-AS algorithm outperforms conventional TAS schemes conceived for LS-SM-MIMO systems.

In this paper, the system performance analysis of a two-way decode and forward (DF) relaying network over the Rician fading environment under hardware impairment effect is proposed, analyzed and demonstrated. In this analysis, the analytical mathematical expressions of the achievable throughput, the outage probability, and ergodic capacity were proposed, analyzed and demonstrated. After that, the effect of various system parameters on the system performance is deeply studied with closed-form expressions for the system performance. Finally, the analytical results are also demonstrated by Monte-Carlo simulation in comparison with the closed-form expressions. The numerical results demonstrated and convinced the effect of the system parameters on the system performance of the two-way DF relaying network. The results show that the analytical mathematical and simulated results match for all possible parameter values.DOI: http://dx.doi.org/10.5755/j01.eie.24.2.20639