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Nowadays, there are massive demands on the broadband multimedia services. Data security in today's world is an essential issue in different aspects of life such as marketing services, defense, financial, and health care. Modulation schemes, channel coding, diversity techniques, etc., are types of physical layer security methods, which are used to ensure the data from unauthorized access. In addition, various cryptographic techniques are usually used to secure data transmission between sender and the intended receiver. The combination of cryptographic techniques and physical layer security schemes makes it better for transferring multimedia data through unsecure or potentially risky communication (wired and wireless) path. Many chaotic-based encryption algorithms have been suggested to ensure confidentiality and security for multimedia data over an insecure wireless channel. Cryptography techniques do not involve any system complexity but add a little computation complexity. Use of advanced processors mitigates the computational burden. In this paper, we have discussed efficient transmission of an encrypted color image through a multiple-input multiple-output-orthogonal frequency division multiplexing (MIMO–OFDM) system over a Rayleigh fading with an additive white Gaussian noise channel. Four schemes of chaotic-based encryption are employed. Both 2 × 2 MIMO - OFDM and 4 × 4 MIMO - OFDM wireless communication systems are presented. Peak signal-to-noise ratio metric is used to evaluate the quality of the received image at different signal-to-noise ratios. Other metrics such as number of changing pixel rate, unified averaged changed intensity, correlation coefficient, entropy, and histogram are evaluated. [ABSTRACT FROM AUTHOR]

Non-orthogonal multiple access (NOMA) technique can potentially increase spectral efficiency and improve the network capacity of wireless networks. Ergodic secrecy capacity (ESC) is an important parameter for evaluating the security of wireless systems. In this paper, we investigate the secrecy performance of a cooperative NOMA system with an untrusted user using a half-duplex amplify-and-forward relay in terms of ESC over Rayleigh fading environments. A satellite source uses the NOMA technique to communicate with the near and far users, which is assisted by a relay for downlink communication, and an untrusted user, i.e., an eavesdropper, also interacts with this relay. We derive the lower bound ESC of the proposed system and analyze its performance in terms of power allocation coefficient, variance between relay and user, variance between relay of the eavesdropper, and average signal-to-noise ratio of the eavesdropper link. Simulation results demonstrate that the cooperative NOMA system outperforms the cooperative orthogonal multiple access system in terms of ESC. Finally, Monte Carlo simulations are used to validate the analytical results. [ABSTRACT FROM AUTHOR]

In design and analysis problems of wireless communication systems, a set of signal-to-noise ratio random variables may have to be dealt with. For example, this applies to transmit and/or receive diversity systems, and to scheduling and resource allocation problems. In such cases, it can be important to know how a given signal-to-noise ratio random variable ranks among the whole set of random variables. For example, in opportunistic multiuser systems, allocating resources to a user depends strongly on the probability of that user's signal-to-noise ratio being larger than those of all (or most) other users. Considering a set of signal-to-noise ratio random variables, ranking probability is defined in this paper as the probability of a signal-to-noise ratio random variable being smaller than a given number of signal-to-noise ratio random variables in the set. Candidacy probability is defined as the probability of a signal-to-noise ratio random variable belonging to a subset of signal-to-noise ratio random variables with highest values. Closed form expressions for ranking and candidacy probabilities of signal-to-noise ratio random variables are derived, assuming Rayleigh fading. The derived probabilities are compared to those found by simulation. Comparisons confirm the correctness of the derived expressions. Simulations have been performed assuming a cellular base station that is serving a number of users. In several experiments, different levels of variation in the average signal-to-noise ratios of the users have been assumed. Results confirm the need for applying some fairness constraints in signal-to-noise ratio order-based scheduling algorithms to prevent situations where some users may not get enough access to system resources. [ABSTRACT FROM AUTHOR]

Future wireless networks are expected to face several issues, but cooperative non-orthogonal multiple access (C-NOMA) is a promising technology that could help solve them by providing unprecedented levels of connection and system capacity. In this regard, the influence of the power location coefficient (PLC) for remote users adopting multiple-input-multiple-output (MIMO) and massive MIMO has been explored to provide effective performance. The goal of this study is to design fifth-generation (5G) downlink (DL) NOMA power domain (PD) networks with a variety of distances and PLCs for remote users and then to compare their outage probability (OP) performance versus signal to noise ratio (SNR). As a novel approach to improving OP performance rate and mitigating the influence of the PLC for remote users, DL C-NOMA is combined with 16×16, 32×23, and 64×64 MIMO and 128×128, 256×256, and 512×512 massive MIMO. The results were obtained that the 64×64 MIMO improves the OP for the remote user by 65.0E-03, while the 512×512 massive MIMO achieved an improvement that reaches 1.0E-06 for the PLC of 0.8 at SNR of 14 dB. The Rayleigh fading channels and MATLAB simulation tools were utilized to carry out the study work. [ABSTRACT FROM AUTHOR]

A best relay selection algorithm for a cooperative multi-hop cross-layer single-input single-output (SISO) amplify-and-forward (AF) wireless relay network is analyzed in this work, with the application where exact channel state information (CSI) is known. We present algorithmic strategies to simplify a multi-hop parallel SISO relay network into a series multi-hop network by finding the best path having the maximum received signal-to-noise ratio (SNR). The best relay selection by using dynamic programming search entails high computations and large memory requirements, as well as involves the full CSI information, making this approach impractical for large-scale networks. The goal of the proposed low-cost near-optimal routing strategy in this work is to provide close to optimal performance with much less complexity compared to traditional routing. Next, we also propose a low-cost power allocation to further improve system performance over traditional power allocation found in the literature. Computer simulations show excellent performance improvement of our proposed methods in terms of bit error rate (BER) as well as outage probability over the traditional relaying and power allocation algorithms.

In this work, we present symbol error performance analysis of probabilistic shaping (PS) for wireless communications in noise-limited and fading channels. Two fading models considered are the Rayleigh and log-normal fading channels. The results are corroborated with simulation and compared with the conventional uniformly distributed input symbols. In all channel conditions, PS results in significant reductions in the SNR required to achieve a specific error probability compared to the conventional uniformly shaped symbols. For example, in a noise-limited channel, PS based quadrature amplitude modulation (QAM) signal results in SNR gains of 1.16 dB, 1.41 dB, and 1.52 dB compared to the uniformly distributed QAM symbols at equal entropy rates of 4, 6, and 8 bit/symbol and a symbol error ratio (SER) of $1\times 10^{-3}$ .

Summary: The channel estimation (CE) process is an important phase that has a considerable influence on the performance of massive multiple‐input multiple‐output systems, in particular, in a more realistic scenario where the channels are spatially correlated (ScD). Thereby, in this work, the uplink (UL) CE process and channel hardening (CH) feature is addressed for ScD Rayleigh fading channels using the statistical Bayesian minimum mean square error estimator. The spatial correlation (SC) of the channels is described using different models, namely, the Gaussian local scattering (GLS) model, the uniform local scattering model, and the proposed hybrid model. Each model (i.e., GLS model and the uniform local scattering model) is studied using two arrangements, that is, for a uniform linear array (ULA) and uniform planar array (UPA). Moreover, the CH feature is investigated under SC of the channels using different models. Furthermore, this study proposes an efficient hybrid strategy based on SC of the channels for UL CE; that is, this work proposes a hybrid covariance matrix (CM) for UPA arrangement by relying on the Kronecker product of the CMs generated through two ULA arrangements, where the first CM is generated through horizontal ULA using GLS model, whereas the second CM is generated through vertical ULA using uniform local scattering model (i.e., one‐ring model). Numerical results regarding CE and CH are provided to assert the theoretical expressions, where the CE is evaluated using the normalized mean square error, whereas the CH is assessed using the variance of CH. [ABSTRACT FROM AUTHOR]

With the rapid development of wireless communication, 5G is gradually growing into a large-scale basic Internet that supports various industries in the whole society. The substantial expansion of its service scope poses many challenges for the underlying technology, especially for the crucial component of the physical Layer-Orthogonal Frequency Division Multiplexing (OFDM). Recently, Neural Networks (NNs) have attracted extensive attention due to their excellent performance in computing vision and natural language processing. Its strong universality also provides new development space for traditional communications. This manuscript conducts an in-depth study on channel estimation for OFDM systems and explores the possible application of a Generalized Regression Neural Network (GRNN) to estimate the Channel Impulse Response (CIR) attenuated by AWGN and Rayleigh fading system. Moreover, three traditional channel estimation algorithms, i.e., LS, MMSE, and LMMSE, are derived by mathematics. In addition, this thesis illustrates several typical neural networks in detail, including their internal structure, parameter updating process, and related optimization algorithms. [ABSTRACT FROM AUTHOR]

With the rapid development of wireless communication, 5G is gradually growing into a large-scale basic Internet that supports various industries in the whole society. The substantial expansion of its service scope poses many challenges for the underlying technology, especially for the crucial component of the physical Layer-Orthogonal Frequency Division Multiplexing (OFDM). Recently, Neural Networks (NNs) have attracted extensive attention due to their excellent performance in computing vision and natural language processing. Its strong universality also provides new development space for traditional communications. This manuscript conducts an in-depth study on channel estimation for OFDM systems and explores the possible application of a Generalized Regression Neural Network (GRNN) to estimate the Channel Impulse Response (CIR) attenuated by AWGN and Rayleigh fading system. Moreover, three traditional channel estimation algorithms, i.e., LS, MMSE, and LMMSE, are derived by mathematics. In addition, this thesis illustrates several typical neural networks in detail, including their internal structure, parameter updating process, and related optimization algorithms.

The proposed cooperative spectrum sensing network presented in this paper has potential properties that could improve the detection probability. The proposed network consists of multiple cognitive radio (CR) nodes. Each CR node is equipped with several antennas, and selection combining is used to identify the highest value of sensing data associated with each antenna. Further, this sensing data is passed to fusion center and primary user activity is identified at the fusion centre using the fusion rules. This study mainly focuses on identifying unknown signals in a Rayleigh fading environment using an improved energy detector. Initially, the novel analytical closed-form of expressions for false alarm and missing detection probabilities was provided under Rayleigh fading with multiple antennas at each CR. Further, the performance of the total error rate is studied under single and multiple antenna scenarios, and a quantitative evaluation is offered to determine average throughput and energy efficiency performance. Later, to simulate the performance with a solid foundation of mathematical analysis, a simulation test-bed is created in MATLAB. Finally, the performance is improved with the proposed scheme compared to conventional scheme. [ABSTRACT FROM AUTHOR]

This paper proposes a full-rate space-time code selection technique for multiple transmitter antenna diversity systems. The technique uses orthogonal space-time codes for transmitting with two antennas and a quasi-orthogonal space-time code when transmitting with four antennas. We selected the space-time code and the transmitter antennas by comparing the equivalent SISO channels with a set of predetermined threshold levels, found off-line as a function of the Doppler frequency. The performance of the proposed technique was evaluated using the error rate and the spectral efficiency, outperforming other existing techniques. [ABSTRACT FROM AUTHOR]

This research paper focused on the enhancement improvement of communication system using a combined modulation signal of Quadrature Amplitude Multiplexing and Orthogonal-frequency division multiplexing (OFDM) using a performance metrics of bit error rate (BER) and Signal to Noise Ratio (SNR) tested on a Rayleigh fading channel. The GSC is introduced at the receiving end to give a better received signal with in turn will result in better Quality of Service. The bit error rate (BER) performance of this type of systems are evaluated in the Rayleigh fading channel using Additive White Gaussian Noise (AWGN) channel as an ideal model. [ABSTRACT FROM AUTHOR]

Non‐orthogonal multiple access (NOMA) is a key technology beyond 5G/6G wireless and mobile communication systems. Simply because of the high efficiency of resource utilization, the system can meet the ever‐increasing requirements of higher data rates and ultra‐reliability. Keeping that in mind, we seek in this paper to derive simple closed‐form expressions to compute the maximum achievable user rate and formulate the probability density function of the SNR and SINR in the system. In addition to that, we determine the outage probability of the system in a generalized and explicit form. All of that is in terms of the user's deterministic propagation channel parameters, such as power allocation factor, noise level, position, and pathloss coefficient. Simulation results validate the accuracy of the obtained formulae. [ABSTRACT FROM AUTHOR]

Non-Orthogonal Multiple Access (NOMA) technology can accommodate more subscribers concurrently and achieve higher spectrum efficiency than Orthogonal Multiple Access (OMA) technologies. This work investigates the performance of the two subscriber downlink cooperative NOMA system with Scaled Selection Combining (SSC) comprising a Base Station (BS), a cell edge subscriber and a near subscriber. Due to the channel conditions, the error performance of the cell edge subscriber is poorer compared to the near subscriber. To mitigate this and enhance the performance, the proposed SSC combines signals from BS and near subscriber and chooses the best signal between them. The Symbol Error Probability (SEP) of this cellular system with M−ary Phase Shift Keying (MPSK) modulation is derived under the Rayleigh fading environment. The optimum scaling factor to reduce the SEP is also obtained. The theoretical SEP expressions of SSC are validated with the Monte-Carlo simulations. The proposed system provides better SEP and outperforms the non-cooperation and traditional Selection Combining (SC) schemes. Additionally, the efficacy of the proposed system under various modulation schemes is studied. [ABSTRACT FROM AUTHOR]

With the further development and wide application of wireless technology in 6G, people are increasingly inseparable from wireless devices, from the ground to the air. The power consumption and service life of devices have become an urgent problem to be solved. In this paper, the energy harvesting relaying system based on the power splitting method with unidirectional DF half-duplex and full-duplex relay is proposed. The relay node is powered by itself through energy harvesting. Specifically, we analyze the system capacity, and the formula of system outage probability is also obtained. Simulation results show the performance of the half-duplex and full-duplex system. With a smaller power splitting factor, more energy is harvested, the outage probability is lower, and the capacity is higher. [ABSTRACT FROM AUTHOR]

A non-multipath and a receive diversity power line communication (PLC) system subject to Rayleigh fading is considered in this paper with the transmitter employing non-orthogonal $M$ -ary frequency-shift keying ($M$ FSK) modulation scheme for data transmission. With the PLC systems corrupted by additive complex Nakagami- $m$ background noise, an optimal receiver for non-multipath PLC system and a Gauss-optimal receiver structure for the multipath PLC system are proposed using which, closed-form expressions for the symbol error probability (SEP) are derived using a characteristic function approach. The optimal correlation coefficients between the symbols of a binary FSK modulation scheme minimizing the SEP of the systems are obtained, which is further generalized by proposing a search-based algorithm to derive the optimal symbol correlation matrix for an $M$ FSK modulation leading to the minimal SEP values of the PLC systems. Numerical results show that the index value of the optimal correlation matrix depends on the system parameters namely the noise shape parameter and the average signal-to-noise ratio only for the case of the non-multipath PLC system, whereas there is no such dependency in the case of the multipath PLC system. [ABSTRACT FROM AUTHOR]

Improving security and reliability is a main concern in many wireless transmission systems. In this paper, we explore the security and reliability in cognitive relay networks with an eavesdropper and multiple relays where the decode-and-forward (DF) protocol is considered. We propose a novel cognitive relay selection to improve the security and reliability of the considered system. The most important contribution is that we obtain the cumulative distribution functions (CDFs) of the channels from the selected relay to the destination and to the eavesdropper, respectively, which makes other related theoretical research possible. Furthermore, based on the proposed relay selection criterion, we derive the accurate closed-form outage probability and intercept probability of the considered system. At last, simulation results verify the correctness of our derivations. Interestingly, although the relay selection is based on the relay-destination channel and the relay-eavesdropper channel, it can be seen from the theoretical results that the reliability performance is completely irrelevant to the relay-eavesdropper channel's statistical characteristics, whereas the security performance is entirely independent of statistical characteristics of the relay-destination channel. In addition, the security performance is always improved with the increasing number of relays, but the reliability performance is not proportional to the number of relays any more when the number of relays reaches a certain value. [ABSTRACT FROM AUTHOR]

This paper investigates the channel capacity of coherent reception with antenna diversity in Rayleigh fading using asymmetric constellations, such as nonbinary two-sided amplitude-shift keying (ASK) and quadrature amplitude modulation (QAM) with ≥ 8 levels. Due to the asymmetries, the capacity achieving input or a priori probability distributions deviate from uniformity. To perform the investigation, an analytical expression for the mutual information, in terms of an integral over a single variable, between the input (transmitted symbol) and the output (received signal vector comprising signals at receive antennas), is derived. For two-sided ASK, 8-QAM with cross constellation, and 16-QAM, analytical closed form expressions for the high and low signal-to-noise (SNR) approximations, respectively, of the capacity achieving input probability distribution, the capacity, and the relative gain in mutual information (between using the uniform and the capacity achieving input probability distributions) are obtained. Numerical results show that at low SNRs, the use of the capacity achieving nonuniform input probability distribution offers significant advantage over the use of the uniform input probability distribution, while at high SNRs, this advantage is significant only for configurations with one receive antenna. Furthermore, the high and low SNR approximations are shown to be reasonably accurate. [ABSTRACT FROM AUTHOR]

Efficient channel management is a challenge that next-generation wireless networks need to meet in order to satisfy increasing bandwidth demand and transmission rate requirements. Non-orthogonal multiple access (NOMA) is one of such efficient channel allocation methods used in 5G backhaul wireless mesh networks. In this paper, we propose a power demand-based channel allocation method for 5G backhaul wireless mesh networks by employing NOMA and considering traffic demands in small cells, thereby improving channel utility. In this scheme, we work with physical layer transmission. The foremost aim is to mutually optimize the uplink/downlink NOMA channel assignment in order to increase user fairness. The approach concerned may be divided into two steps. First, initial channel allocation is performed by employing the traveling salesman problem (TSP), due to its similarity to many-to-many double-side user-channel allocation. Second, the modified particle swarm optimization (PSO) method is applied for allocation updates, by introducing a decreasing coefficient which may have the form of a standard stochastic estimate algorithm. To enhance exploration capacity of modified the PSO, a random velocity is included to optimize the convergence rate and exploration behavior. The performance of the designed scheme is estimated through simulation, taking into account such parameters as throughput, spectral efficiency, sum-rate, outage probability, signal-to-interference plus noise ratio (SINR), and fairness. The proposed scheme maximizes network capacity and improves fairness between the individual stations. Experimental results show that the proposed technique performs better than existing solutions. [ABSTRACT FROM AUTHOR]

Abstract Many shortest link scheduling algorithms adopt non-fading SINR interference model, which assumes that the received signal power will always remain determinate as long as the transmission power of the corresponding sender is fixed. In fact, because environment always influences the propagation of radio signals, the received signal power is by no means a certain value. Rayleigh fading is a statistical model for radio signals propagation. It assumes that the strength of a signal on a receiver is a random variable, varying with the Rayleigh distribution. This paper proposes a shortest link scheduling algorithm under the Rayleigh fading model (SLSRF). The SLSRF partitions the wireless network area into hexagons and colors the hexagons with three different colors such that two neighboring hexagons have different colors. The senders of the links scheduled simultaneously are arranged in hexagons with the same color. The correctness of the SLSRF is proved through theoretical analysis, and the efficiency is illustrated by elaborate simulations. Our simulation results demonstrate that the schedule delay of SLSRF is less than that of some results under the non-fading SINR interference model. Furthermore, we extend the SLSRF to a distributed version, which is suitable for large wireless networks.

Radio frequency energy harvesting (EH) technology can harvest the electromagnetic energy in the surrounding environment, and reduce the dependence of the communication devices on battery or power grid as power source, which is a very promising means of energy substitution and acquisition scheme. The random characteristics of wireless channel fading and possible co-channel interference (CCI) have great influence on EH efficiency and wireless communication performance with more complicated theoretical analysis. In this paper, the exact closed-form expressions of effective throughput of "harvest-store-use" and "harvest-use" multi-slot EH schemes with Rayleigh channel fading and CCI are derived theoretically. The simulation results show that in Rayleigh fading channels with CCI, CCI is beneficial to energy harvesting of EH device, but it will deteriorate the reception of required signals by information receiving device. Although there are obvious differences in working mechanism, working conditions and communication performance between the "harvest-store-use" scheme and the "harvest-use" scheme, the optimal time slot should be selected to balance the transmission probability and delay, minimize the interference of CCI to the desired signal, and improve the energy conversion efficiency of the energy harvester.

Efficient channel management is a challenge that next-generation wireless networks need to meet in order to satisfy increasing bandwidth demand and transmission rate requirements. Non-orthogonal multiple access (NOMA) is one of such efficient channel allocation methods used in 5G backhaul wireless mesh networks. In this paper, we propose a power demand-based channel allocation method for 5G backhaul wireless mesh networks by employing NOMA and considering traffic demands in small cells, thereby improving channel utility. In this scheme, we work with physical layer transmission. The foremost aim is to mutually optimize the uplink/downlink NOMA channel assignment in order to increase user fairness. The approach concerned may be divided into two steps. First, initial channel allocation is performed by employing the traveling salesman problem (TSP), due to its similarity to many-to-many double-side user-channel allocation. Second, the modified particle swarm optimization (PSO) method is applied for allocation updates, by introducing a decreasing coefficient which may have the form of a standard stochastic estimate algorithm. To enhance exploration capacity of modified the PSO, a random velocity is included to optimize the convergence rate and exploration behavior. The performance of the designed scheme is estimated through simulation, taking into account such parameters as throughput, spectral efficiency, sum-rate, outage probability, signalto-interference plus noise ratio (SINR), and fairness. The proposed scheme maximizes network capacity and improves fairness between the individual stations. Experimental results show that the proposed technique performs better than existing solutions.

Cooperative communication is a key factor in 5G and beyond standards for increasing the quality of service and aids for dense networks. It works in conjugate with non-orthogonal multiple access (NOMA) to increase the connectivity and spectral efficiency. In this paper, a novel minimum variance maximum mean relay selection scheme with fixed power allocation (MVMM-FPA) is proposed for two-stage cooperative NOMA (C-NOMA) networks using decode-and-forward protocol. The outage probability analytical expressions are derived for the MVMM-FPA over Rayleigh fading channel and its performance is observed with the conventional relay selection (RS) schemes. The impact of outage performance on target rate for users and number of relays have been analyzed for the proposed scheme. Monte Carlo simulations are used to corroborate the analytical expressions of outage probability. Simulation results reveal that the MVMM-FPA RS scheme for C-NOMA offers a minimal outage probability than existing max–min RS and orthogonal multiple access schemes without sacrificing the spectral efficiency. [ABSTRACT FROM AUTHOR]

In this paper, a novel hybrid 3D Video (3DV) encryption framework based on the Rubik's cube is suggested to attain simultaneous encryption of a group of 3DV frames. The suggested hybrid encryption framework begins with chaotic Baker map permutation, Advanced Encryption Standard (AES), or Ron's Code (RC6) technique implemented in Cipher Feedback (CFB) mode of operation as a first step for encrypting the multiple 3DV frames, separately. Then, the resulting encrypted 3DV frames are further encrypted in a second stage with Rubik's cube technique. The chaotic, RC6, or AES encrypted 3DV frames are utilized as the faces of the Rubik's cube. The RC6 and the AES techniques introduce a degree of diffusion from the concepts of image encryption, while the chaotic Baker map adds a degree of permutation. Moreover, the Rubik's cube technique simultaneously adds more permutations to the encrypted 3DV frames. The encrypted 3DV frames are further transmitted over a wireless channel with different Orthogonal Frequency Division Multiplexing (OFDM) versions and decrypted at the receiver side. The quality evaluation of the decrypted 3DV frames at the receiver side reveals good performance. The simulation results prove that the suggested hybrid encryption framework is reliable and it presents recommended security and robustness levels. [ABSTRACT FROM AUTHOR]

Error-rate formulas for equal-gain combining (EGC) in independent Rayleigh fading usually take the form of a single or double integral, and simple closed-form solutions are available only for simple EGC with two or three branches (EGC-2/EGC-3). In this paper, we derive a simple explicit solution to 4-branch EGC (EGC-4), aiming to complement few closed-form results in the literature. [ABSTRACT FROM AUTHOR]

The emerging Wireless Body Area Network (WBAN) has a great potential to strengthen health care sector, as it paves ways for the development of new services and applications. In making WBAN technically feasible, high Signal to Noise ratio (SNR) and low outage probability plays a vital role. In vivo communication is one where communication between living beings can be carried out wirelessly. It utilizes data gathered in real time for quick and accurate responses in emergency situations. To fully benefit from and further explore the potentiality of WBANs for realistic applications, it is critical to analyze the performance of in vivo WBAN communication over different frequency bands. Over the past many years, Medical Implant Communication System (MICS) band has extensively been used for implant medical applications and Terahertz (THz) band shows promising link capability to support increased data rates. In the proposed work, performance of an in vivo WBAN system, at MICS and Terahertz frequencies based upon IEEE 802.15.6 channel models (CM), CM1 and CM2 has been assessed. The effect of incorporating cooperative communication for in vivo WBAN is then presented to see how it enhances the network performance at both the bands. The impact on the system's SNR and outage probability is investigated for number of relays. The outage behavior of amplify and forward cooperative communication with multiple relays is investigated over a Rayleigh fading channel. Results show considerable increase in the system SNR and decrease in outage probability with increase in number of relays, which strongly indicates the possibility of incorporating cooperative communication to elevate the performance of in vivo WBAN at both MICS and terahertz frequencies. Further, nature inspired optimization is done to reduce the outage probability. Results show that the projected technique surpasses the non-optimized technique and ensures favorable results. The results achieved at THz band have also been compared to that obtained at MICS band and it is demonstrated that better performance can be achieved at THz band by incorporating cooperative communication in the network. [ABSTRACT FROM AUTHOR]

In this paper, we derive closed-form expressions for significant statistical properties of the link signal-to-noise ratio (SNR) and the separation distance in mobile ad hoc networks subject to Ornstein-Uhlenbeck (OU) mobility and Rayleigh fading. In these systems, the SNR is a critical parameter as it directly influences link performance. In the absence of signal fading, the distribution of the link SNR depends exclusively on the squared distance between nodes, which is governed by the mobility model. In our analysis, nodes move randomly according to an Ornstein-Uhlenbeck process, using one tuning parameter to control the temporal dependency in the mobility pattern. We derive a complete statistical description of the squared distance and show that it forms a stationary Markov process. Then, we compute closed-form expressions for the probability density function (pdf), the cumulative distribution function (cdf), the bivariate pdf, and the bivariate cdf of the link SNR. Next, we introduce small-scale fading, modeled by a Rayleigh random variable, and evaluate the pdf of the link SNR for rational path loss exponents. The validity of our theoretical analysis is verified by extensive simulation studies. The results presented in this work can be used to quantify link uncertainty and evaluate stability in mobile ad hoc wireless systems. [ABSTRACT FROM AUTHOR]