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A novel method of jitter decomposition by 1 Dimension-convolutional neural network (1D-CNN) using jitter histogram points is proposed for decomposing in the time interval error (TIE) of oscilloscope. Unlike the traditional jitter decomposition method based on the dual-Dirac model and Gaussian mixture model (GMM), the proposed jitter decomposition can reduce complexity and improve accuracy. The proposed method consists of a four-layer 1D-convolutional layer and multi-layer perceptron (MLP). Experimental results show that the proposed approach can decompose the total jitter (TJ) into deterministic jitter (DJ) and random jitter (RJ) and is better than the traditional jitter decomposition method, i.e., GMM, Fast Fourier transform and time lag correlation (FFT+TLC). Besides, results show that the proposed method’s performance is better than 2D-PointCNN, PointRNN, CNN, and PointANN.

This work proposes an average-case performance measurement as a meaningful and non-trivial way of evaluating and comparing queueing protocols on a multiple-access channel (MAC). We prove that Little’s Law holds for this way of measuring latency and number of packets in the system, also for adversarial packet arrival (which was not the case for the previously considered worst-case measurement), and analyze performance of popular MAC protocols. Interestingly, some of them have asymptotically the same average and worst case queue sizes, but not packet latencies, while others exhibit entirely opposite behavior. We also propose a consistent methodology for classifying queueing protocols, based on protocol features, such as synchronization, collision detection, queue-size awareness etc.

This letter proposes a new approach to the reliability analysis of IEEE 802.11 one-dimensional (1-D) broadcast mobile ad hoc networks. The approach finds a simple and effective way to derive the distribution of signal-to-interference-to-noise ratio (SINR) on each receiver, which is required for evaluation of the reliability metrics and the channel capacity. Having observed that the effective interference area depends on a given SINR threshold, the SINR distribution derivation is converted to estimating the SINR threshold related interference areas that are dynamically changed in a communication channel. The analysis is applied to two network configurations for example, and it is cross validated by the extensive simulations. Compared with the previous models, the new approach is more general, more precise, and faster.

This letter investigates the effect of the interference due to spectrum sharing between terrestrial and satellite systems. Based on a realistic coexistence model, we provide an exact closed-form outage probability expression of the satellite link in the presence of the terrestrial interference. We assume Nakagami fading both for terrestrial and satellite links, with an additional consideration for the shadowed Rician fading satellite link. Numerical results show that uncontrolled terrestrial interference can significantly degrade the outage performance of the satellite link. The obtained formulas are useful in predicting and preventing harmful interference when designing coexistence mechanisms for terrestrial and satellite systems.

In this letter, the outage performance of a satellite-assisted cooperative non-orthogonal multiple access (NOMA) system is studied, where a terrestrial source communicates with one terrestrial destination directly while the other terrestrial destination is assisted by a regenerative satellite. We consider the satellite channels and the terrestrial channels undergo shadowed-Rician fading and Nakagami- $m$ fading, respectively. Based on this, we derive the exact closed-form expressions for the outage probabilities. In addition, the asymptotic expressions at high signal-to-noise ratio are provided to gain further insights. Simulation results validate the accuracy of the analytical results and show the superiority over other conventional schemes.

An approximate method for evaluation of the reliability of the symbol subchannels induced by a polarizing transformation with non-binary kernels is proposed. We show that if polar codes are combined with the channel adapter, the capacities of the subchannels can be estimated recursively.

This letter considers a single-input single-output powerline communication (PLC) system employing quadrature phase-shift keying (QPSK) modulation scheme under Rayleigh fading and Nakagami- $m$ noise environment. The series form expression of the symbol error probability (SEP) for the system is derived by considering the QPSK constellation as a combination of two orthogonal binary phase-shift keying constellations. Moreover, the optimal QPSK constellation minimizing the SEP under the constraint of given average transmission power is obtained. It is observed that the optimal solution of the QPSK constellation is elliptical in shape as compared to the traditional circular QPSK constellation. Further studies on the shape of the optimal elliptical QPSK constellation with varying shape parameter of the additive noise are carried out by numerical studies.

We propose a technique for multiple access communications based on the spatial graph coupling principle. Contrary to the existing approaches that require regularized packet transmission times to create a chain of temporally-coupled packets we present a construction of a self-coupling packet. Each transmitted data packet is encoded and modulated in a way that allows the receiver to perform successful cancellation of the inter-packet interference for the case when the packets are transmitted at random times. We show that the overall system throughput can approach the channel capacity limit. Numerical results demonstrate superior bit-error rates achieved by the self-coupling system compared to the temporal-coupling system.

To evaluate the performance of wireless multi-path channels with discrete inputs, this letter investigates the ergodic mutual information (EMI) of a generalized fading type named mixture gamma distribution (MGD) under $M$ -ary quadrature amplitude modulation ( $M$ -QAM) signaling. An accurate closed-form expression for the EMI is developed to approximate the exact value. The MGD fading can be specialized into several regularly used fading cases including Rayleigh fading, Nakagami- $m$ fading, $\eta -\mu $ fading, $\kappa -\mu $ fading, and ${\mathcal {K}}_{G}$ fading, and then the corresponding closed-form EMI formulas are separately derived to measure these fadings. Compared with the Gaussian source signals based research on MGD fading, this work sheds light on the performance with discrete inputs instead of Gaussian inputs, thereby being more practical. This study can be regarded as a unified tool to evaluate the EMI with discrete inputs over arbitrary wireless channels.

Network coding has received great attention for its ability to dramatically improve the performance of wireless networks. However, there still is a lack of research on how and to which degree the packet size affects the performance of a wireless network with network coding. In this letter, we study the issue of optimal packet size for inter-flow network coding enabled two-hop error-prone wireless networks with the IEEE 802.11. We analyze the network throughput of such networks and then derive the optimal packet size for maximizing the network throughput under various cases. The simulation results validate the accuracy of our analytical results.

In this letter, we use squared iterative method with parameter checking to accelerate the convergence rate of expectation/conditional maximization (ECM) algorithm when estimating the channel parameters blindly in flat fading non-Gaussian channels, and further, we proposed automatic modulation classification (AMC) in flat fading non-Gaussian channels based on the proposed maximum likelihood estimator. The numerical results show that the proposed method can accelerate the convergence rate of ECM algorithm, and AMC based on the proposed method is faster than that based on ECM, while the accuracy of the former shows nearly no loss compared with that of the latter.

In this letter, we propose an UAV-based relaying system with energy harvesting functionality. In particular, we assume that this system is operated in urban communication environments, where the channel between the UAV and the land destination is modeled as shadowed-Rician fading or shadowed-Rayleigh fading. Based on this setting, outage probability analysis for different urban environment parameters is derived. Finally, Monte Carlo simulations are conducted to verify the accuracy of our analytical results. � 1997-2012 IEEE. Manuscript received September 11, 2018; revised October 2, 2018; accepted October 15, 2018. Date of publication October 22, 2018; date of current version December 10, 2018. This work was in part supported by the National Natural Science Foundation of China (NSFC) under Grant 61671160, the sponsorship agreement in support of research and collaboration by Ooredoo, Doha, Qatar, the Department of Education of Guangdong Province (No. 2016KZDXM050), and the open research fund of National Mobile Communications Research Laboratory, Southeast University (No. 2018D01). The associate editor coordinating the review of this paper and approving it for publication was C. Zhong. (Corresponding author: Liang Yang.) L. Yang is with the College of Computer Science and Electronic Engineering, Hunan University, Changsha 410082, China (e-mail: liangyang.guangzhou@gmail.com). Scopus

We consider interference cancellation-based random access for scenarios of multiple users communicating with a common receiver. An instinct feedback is assumed to inform the users whether their packets were correctly recovered. Users update their transmission packets once recovered, or a retransmission process is triggered. At the receiver, interference cancellation decoding is employed to resolve packet collisions. By modeling the transmission and packet recovery as a Markov process, a throughput analysis is provided based on which the optimal transmission probability is derived.

In this letter, we investigate theoretical BER performances of generalized frequency division multiplexing (GFDM) systems with receivers based on Gabor window. Considering relationships between zero forcing and minimum mean square error (MMSE) receivers, theoretical BER expressions of GFDM systems with an MMSE receiver are derived over AWGN and fading channels through calculating noise enhancement factor at the receiver. To demonstrate the generality of proposed methods, analytical BER expressions of DFT and weighted-type fractional Fourier transform precoded GFDM systems are also given and verified by simulation results.

In this letter, we study a power-domain non-orthogonal multiple access (NOMA) system in which a base station (BS) superimposes the transmit signals to the users. To enhance spectral efficiency and link reliability for the far-distance user, a full-duplex (FD) relay assists the BS while the near-distance user is reached over the direct link. For this setting, we analyze outage probability and sum rate of the NOMA system over Nakagami- $m$ fading with integer fading severity parameter $m$ . Numerical results are provided for outage probability and sum rate to show the effect of system parameters on the performance of the FD NOMA system over Nakagami- $m$ fading.

In this letter, we investigate the combination of non-orthogonal multiple access (NOMA) with the conventional Alamouti space–time lock coding scheme over Nakagami- m fading environments. In the network, one base station serves multiple users simultaneously by using Alamouti scheme. The exact outage probability (OP) expression is obtained in closed-form. Moreover, asymptotic analysis is also conducted to provide more insights into the OP through diversity order and array gain. The theoretical results verified by the Monte Carlo simulations show that Alamouti scheme can double the diversity order of NOMA network, which also depends on Nakagami channel parameter m and user’s ordinal number.

This letter initiates the study of energy-efficiency gains provided by caching. We focus on the cache-aided Gaussian interference channel in the low-SNR regime. We propose a strategy that creates content overlaps at the transmitter caches to allow for co-operation between the transmitters. This co-operation yields a beamforming gain, which has to be traded off against a multicasting gain. We evaluate the performance of this strategy and show its approximate optimality in both the single-receiver case and the single-transmitter case.

This letter analyzes the downlink coverage probability of user-centric wireless network in a comprehensive fading environment. The comprehensive fading environment consists of two types of fading models: 1) a long-term shadowed fading, where all signals experience an identical and independent lognormal shadowing and 2) an instantaneous fading, where the desired signal experiences $\kappa $ – $\mu $ shadowed fading with integer fading parameters and the interfering signals experience arbitrary fading. Based on the Gaussian–Hermit quadrature, a tractable and accurate expression for the serving distance with lognormal shadowing is obtained. Under a general cell association rule, a simple and generic expression for the downlink coverage probability of user-centric wireless network in the comprehensive fading scenario is successfully derived and verified through simulation. The derived expression reveals that there is no need for the coverage analysis with respect to the instantaneous interfering fading channels in terms of the independence assumption between network model and fading channels.

In this letter, we show that Huffman’s source coding method is not optimal for cache-aided networks. To that end, we propose an optimal algorithm for the cache-aided source coding problem. We define cache-aided entropy , which represents a lower bound on the average number of transmitted bits for cached-aided networks. A sub-optimal low-complexity cache-aided coding algorithm is presented. In addition, we propose a novel polynomial-time algorithm that obtains the global-optimal source code for wide range of cache sizes. Simulation results show a reduction in the average number of transmitted bits by more than 50% over Huffman’s method at moderate cache sizes.

The current contention mechanism of the IEEE 802.11 distributed coordination function (DCF) is known to have some drawbacks, e.g., collisions and low short-term fairness induced by minimizing the backoff stage after every successful transmission. To solve the drawbacks we propose an adaptive contention window control scheme which uses a single backoff stage while maintaining the advantages of the current IEEE 802.11 DCF such as simplicity and distributivity. We first introduce the key concept called the optimal collision probability and explain the detailed procedure of the proposed scheme which is based on the optimal collision probability. The convergence of the proposed scheme is shown. The validation from simulation results shows that the proposed scheme provides higher throughputs and higher short-term fairness than the IEEE 802.11 DCF.

In this letter, we study the outage performance of non-orthogonal multiple access (NOMA) with fixed power allocation over Nakagami- ${m}$ fading channels, where the fading parameters of NOMA users are different. In this scenario, new closed-form expressions are derived for the outage behavior of individual users and the system, respectively. Next, the diversity orders are obtained under high signal-to-noise ratio condition. The derived analytical expressions are exact and unprecedented in the earlier literature. Finally, simulations are conducted to confirm the validity of the analysis and show the outage performance of NOMA under different fading parameters of Nakagami- ${m}$ fading channels.

We consider multichannel ALOHA for machine-type communications to support a number of devices with multiple subchannels in this letter. In particular, we focus on the stability of multichannel ALOHA when only fast retrial is employed for re-transmissions of collided packets. For the stability analysis, the Foster–Lyapunov criterion is considered. For a stable system, the rate control is applied, and a certain rate control scheme of limited feedback is proposed.

In this letter, we consider a cumulative distribution function-based scheduling (CS) algorithm in downlink cellular networks. We present exact and approximate formulas for the probability distribution of the starving time of a user of the CS algorithm over Nakagami- $m$ Markov fading channels. The approximate formula provides a tight result for a large number of users with low computational complexity. Through numerical studies based on our analysis, we investigate the impact of the scheduling parameters and the Nakagami fading parameters on the starving time of the CS algorithm.

We develop the Bayesian test for detecting the relay misbehavior (false data injection) at the packet level in lossy one-way wireless relay networks. The proposed approach exploits overheard erroneous packet from the source as a reference in verifying the correctness of relayed packet at the destination. We derive the probability of false alarm and missed detection as a function of the overhearing error rate, the number of bits modified in a packet, and the packet length. We show that the probability of false alarm and missed detection decreases as the packet length increases and converges to zero, regardless of the overhearing error rate, if the packet length is sufficiently long.

The secrecy systems operating over spatially correlated composite fading channels is analyzed in this letter. We adopt a multiplicative composite channel model for both the legitimate communication link and the link between the eavesdropper and the legitimate transmitter, consisting of Nakagami- $m$ distributed small-scale fading and shadowing (large-scale fading) modeled by the Gamma distribution. We consider the realistic case where small-scale fading between the links is independent, but shadowing is arbitrarily correlated, and present novel analytical expressions for the probability that the secrecy capacity falls below a target secrecy rate. The presented numerically evaluated results, verified by equivalent computer simulations, offer useful insights on the impact of the shadowing correlation and composite fading parameters on the system’s secrecy outage performance.

This letter presents an analytical framework based on Markov modulated batch Poisson processes for stochastic modeling of WiFi temporal activity and its idle gaps, or white spaces. The proposed model takes into account the dynamic and bursty nature of WiFi traffic to mathematically characterize the duration and the frequency of occurrence of white spaces in unlicensed bands. Closed-form expressions as well as simple approximations are derived. Numerical results demonstrate the accuracy of the model, along with the plenitude of the spectral resources in an arbitrary WiFi network that may be exploited opportunistically, with minimum impact on WiFi activity.

We consider an ultra-dense network where each mobile is attached to the access point, which provides the best reference signal received power considering both path-loss and small-scale fading. In order to evaluate the effect of outdated channel state information (CSI) brought by feedback delay, we first derive the estimated and accurate handover probability according to outdated and perfect CSI, respectively. Furthermore, two metrics are proposed to measure the handover failure, i.e., false handover probability and miss handover probability . Simulations show that in sparse or ultra-dense networks, the imperfection of CSI is acceptable for handover decisions; however, in between, i.e., dense networks (medium-size networks), handover decisions are very sensitive to the user velocity and CSI imperfection.

In this letter, we study coded random access with multichannel ALOHA where incremental redundancy-based re-transmissions are employed. A closed-form expression for the throughput is derived, which allows optimizing key parameters for given conditions. A scaling property of multichannel ALOHA is also shown with an asymptotic throughput, which demonstrates that the throughput grows linearly with the number of subchannels in coded multichannel ALOHA for any initial rate.

Network densification will produce frequent handover for mobile users, which could largely diminish the densification gain. We develop a comprehensive analytical model for the handover rate in K-tier heterogeneous cellular networks, where each tier is modeled as an independent Poisson point process with unique transmit power, path-loss exponent, spatial density, and association bias. The spatial randomness of users’ mobility is captured and analyzed by stochastic geometric theory, and we derive closed-form expressions for handover rate with arbitrary mobile trajectories. The relationship between total handover rate and horizontal/vertical handover rate is analyzed, and the effect of the user’s velocity, BS densities, path-loss exponents, and association bias are found. There is an optimum value of BS densities to keep a good tradeoff between handover rate and user’s throughput. Finally, simulation results verify the accuracy of the derivation.

International audience; In this letter, index modulation (IM) is proposed for OFDM systems based on a discrete cosine transform (DCT) implementation. The new DCT-OFDM-IM scheme is shown to yield spectral efficiency improvements of up to 38% relative to OFDM-IM and up to 55% relative to OFDM while occupying the same bandwidth and maintaining similar robustness against frequency selective fading channels for low modulation orders.

We investigate the symbol error rate (SER) of a transmit antenna selection (TAS)-maximal ratio combining (MRC) with relay and user selection in multiple-input multiple-output systems over non-identical Nakagami fading channels. This letter derives the exact cumulative density function (cdf) of the effective signal-to-noise ratio for the proposed system. Using the cdf, this letter derives the exact closed-form expressions of the TAS-MRC with relay and user selection for the SER with M-ary quadrature amplitude modulation over non-identical Nakagami fading channels including quantification of the diversity order using asymptotic analysis.

The multi-packet reception (MPR) technique enables access points to correctly receive simultaneously transmitted packets. Therefore, the network saturation throughput can be significantly improved by introducing MPR into wireless local area networks (WLANs). In this letter, we develop a novel analytical model to evaluate the saturation throughput of a WLAN with MPR. In contrast to previous models, we adopt the stationary distribution of backoff counter value after a generic overlapping transmission process to characterize the behavior of a contending station. Then, we derive the saturation throughput based on this distribution. Comparisons with simulation results show that our analytical model provides a close evaluation of the saturation throughput. Moreover, the impacts of several parameters on the saturation throughput are also investigated using the proposed model.

We consider a random access network in which $K$ nodes wish to send independent packets to an access point (AP). In this letter, a novel method of feedback construction and an adaptive retransmission protocol of collided packets are proposed, which enable efficient successive interference cancellation at the AP. We show that the optimal throughput efficiency of one is achievable by only exploiting $\log K$ bits of feedback from the AP to $K$ nodes, while the maximum throughput efficiency of slotted ALOHA is known to be $e^{-1}\approx 0.37$ for large $K$ . Note that the proposed technique achieves the optimal throughput efficiency for any finite $K$ , while the conventional techniques asymptotically achieve the optimal throughput efficiency only when $K$ tends to infinity.

This letter proposes a simple but accurate approximation to analytically model both the inter-wireless local area networks (WLANs) interactions and the negative effect of collisions in the performance of high density WLAN scenarios. Inter-WLANs interactions are characterized using a continuous time Markov chain (CTMC) model, where states represent the set of active WLANs at a given time. Then, the effect of collisions is considered by analyzing the local dynamics between contending WLANs at every state of the CTMC. Simulation results confirm the accuracy of the presented approach.

This letter provides a general analytical framework for multiple-input multiple-output space shift keying systems considering hardware impairments, at the transmitter and receiver sides, and co-channel interference. Specifically, a closed-form expression for the average bit error probability (ABEP) in the case of two transmit antennas and arbitrary number of receive antennas is derived. As well, a tight upper bound ABEP expression in the general case of arbitrary number of transmit and receive antennas is obtained. Besides, an asymptotic simple expression is found over Rayleigh fading channels. Analytical results, which are validated via simulation ones, explicitly demonstrate that non-zero bounds of the ABEP exist in the high power region, which is in contrast to the case of ideal hardware, where the ABEP asymptotically goes to zero.

In this letter, we develop a recurrence formula for the capacity of Nakagami- $m$ fading channel with BPSK/QPSK modulations when channel state information is available at the receiver. For each fading parameter $m$ , a simply constructed series representation with a fast-convergence rate can be obtained through the recurrence formula. The series expansion provides a numerically efficient way to calculate the capacity for both Rayleigh and Nakagami- $m$ fading channels. The simulation results show that the recurrence formula is a good alternative for estimating the capacity of Nakagami fading channel.

Modulation diversity (MoDiv) is a simple and practical transmission enhancement technique that utilizes different modulation mappings to reduce packet loss rate and achieve higher link throughput. MoDiv is particularly meaningful and effective in Hybrid-Automatic Repeat reQuest (HARQ) systems. We study the deployment and optimization of MoDiv for HARQ in a MIMO-coordinated multi-point scenario under Rician fading channel to mitigate packet loss. We formulate the design optimization of MoDiv into a quadratic 3-D assignment problem, then solve it using a modified iterated local search method. Numerical results demonstrate clear performance gain over simple retransmissions and over a heuristic design under fading channels.

Theoretical developments on selection combiner output (SCO) multivariate distributions of popular correlated fading environments, such as Rayleigh, Rician, and Nakagami- $m$ , have been studied in the literature, but those of generalized-Rician fading have not been rigorously studied. The generalized-Rician fading environment, comprising of $n$ underlying non-zero mean independent and identically distributed Gaussian random variables, can be generalized to Rayleigh, Rician, and Nakagami- $m$ fading. In addition, available findings on this topic in the open literature are scattered with mathematical mistakes. This letter thus derives SCO correlated generalized-Rician multivariate cumulative distribution function, then identifies mathematical errors in the open literature, and corrects them. Cross verification of well-known results is mathematically employed. Simulation details of average bit error rate for binary frequency-shift keying are also given for verification purposes.

We present a generic approximation of the packet error rate (PER) function of uncoded schemes in the additive white Gaussian noise channel using extreme value theory (EVT). The PER function can assume both the exponential and the Gaussian $Q$ -function bit error rate forms. The EVT approach leads us to a best closed-form approximation, in terms of accuracy and computational efficiency, of the average PER in block-fading channels. The numerical analysis shows that the approximation holds tight for any value of signal-to-noise ratio (SNR) and packet length whereas the earlier studies approximate the average PER only at asymptotic SNRs and packet lengths.

In this letter, the performance of uncoded and space frequency block coding (SFBC) orthogonal frequency division multiplexing (OFDM) system over two-wave with diffuse power (TWDP) fading environment is analyzed. A general closed-form expressions of average bit error rate for both $M$ -ary phase shift keying and $M$ -ary quadrature amplitude modulation are derived using moment generating function of TWDP fading distribution. Results are verified with the benchmark results available in the literature (i.e., Rayleigh and Rician). Numerical results with various TWDP fading channel parameter ( $K$ and $\Delta $ ) and with different modulation orders for uncoded and SFBC OFDM systems show excellent agreement with simulation results.

In this letter, we investigate the performance of coherent free-space optical (FSO)—orthogonal frequency division multiplexing (OFDM) systems with multiple receivers over an atmospheric turbulence channel considering the frequency offset effect. In particular, we derive an exact average bit error probability (ABEP) of coherent FSO-OFDM systems in a turbulence-induced fading channel. To mitigate the atmospheric turbulence-induced amplitude fluctuations and phase aberrations, a modal compensation technique is assumed to be employed at the receivers. Numerical results confirm the validity of the derived ABEP expression.

Applying Alamouti code to filter bank multicarrier (FBMC) is a challenging issue due to the intrinsic inter-antenna inter-carrier interference (ICI), which does not exist in Alamouti coded orthogonal frequency division multiplexing (OFDM). We propose a frequency reversal Alamouti coded scheme for FBMC. As the frequency reversal symbol arrangement in itself cannot handle the inter-antenna ICI, we carefully consider the signal structure of FBMC and specify the additional requirements to satisfy self-ICI cancellation property. Only with a simple signal modification in the transmitter and the typical Alamouti decoding in the receiver, the proposed scheme achieves ideal (ICI-free) Alamouti code performance if the fading is locally flat over the Alamouti coded block. By properly dividing the total bandwidth into multiple blocks, the proposed scheme achieves near ICI-free performance for the multi-path fading channels.

A queue stability analysis in a wireless multicast network with packet erasure channels is studied in this letter. In particular, a new queuing model consisting of several sub-queues is introduced, where each packet in a sub-queue is associated with an index set indicating its intended users. Our objective is to maximize the input rate under the queue stability constraints. We formulate it as a linear programming problem and propose a network coding-based packet scheduling scheme that finds the optimal solution. Finally, the simulation results corroborate our method.

This letter proposes a graph-based satellite handover framework for the low earth orbit (LEO) satellite communication networks. In order to maintain the connection with the communicating counterpart, the user has to switch between consecutive satellites covering the very user. A directed graph with covering period of the satellite as its node, and the link representing the possible handover between two overlapping periods, is calculated in advance, and then, the satellite handover process can be viewed as finding a path in the directed graph. By setting the link weight according to different handover criterions, the graph-based framework can support a variety of satellite handover strategies, which shows the improved flexibility over the existing research. The application of the framework to find the shortest handover path conducted on two typical LEO satellite networks, viz., Iridium and Globalstar, also corroborates the effectiveness of the proposed handover framework.

This letter studies the outage performance of multihop cognitive relay networks with energy harvesting in underlay paradigms, wherein the secondary users are powered by a dedicated power beacon (PB) and their transmit powers are subject to the harvested energy from PB and the interference constraint from the primary user. We derive the exact outage probability for Rayleigh block fading and prove that the outage probability is monotonically decreasing with respect to the transmit power of PB. Furthermore, we derive the asymptotic outage probability to study the outage saturation phenomenon and propose an iterative algorithm that jointly optimizes the transmit power of PB and the harvest-to-transmit ratio to approximate the minimum outage probability. Simulation results validate the theoretical results.

A Markovian battery model for energy harvesting (EH) secondary users (SUs) is proposed to derive the probability of packet loss due to sensing inaccuracy and energy outage in the EH cognitive radio network (CRN). With the proposed analysis, the packet loss probability can easily be predicted and utilized to optimize the transmission policy (i.e., opportunities for successful transmission and EH) of EH SUs to improve their throughput. Especially, the proposed method can be applied to upper layer (scheduling and routing) optimization. To this end, we validate the proposed analysis through Monte-Carlo simulation and show an agreement between the analysis and simulation results.

The letter presents a novel framework for 5G nodes with vertical multi-homing capabilities by using radio access technology aggregation on the network protocol layer and using Lyapunov optimization. The proposed 5G node framework leads to high performance utility networks with QoS provisioning for any given service, high average throughput, and multi-RAT capabilities (part of 5G trends), while at the same time achieving stochastic queuing network stability. The proposed framework uses the Lyapunov drift-plus-penalty theorem, which provides a methodology for designing an algorithm to maximize the average throughput and stabilize the queuing. The proposed algorithm, implemented within the mobile nodes and proxy node on the mobile network side, is able to handle simultaneously multiple multimedia flows via multiple wireless and mobile interfaces. The performance of the proposed framework for 5G nodes is evaluated with simulation and analytical results. The results show that the given framework achieves maximal aggregated throughput subject to average power constraints on the node interfaces, and at the same time minimizes average queue backlogs subject to minimal network delay.

In this letter, cognitive two-tier femtocell networks are considered, where each femtocell transmits over subchannels that are considered idle by spectrum sensing. Since femtocells transmit on the “idle” subchannels based on imperfect cognitive sensing, co-tier and cross-tier interference will arise. We derive the average uplink throughput of cognitive femtocell networks, where fractional power control and adaptive modulation are adopted. Besides, by maximizing the system throughput, the optimal channel access probability of each femtocell is obtained. Simulation results verify the validity of the analysis.

This letter considers a single hop wireless multicast network. We first introduce a new two-level queuing system consisting of a main queue and a virtual queue, where each packet in the virtual queue is associated with a user index set. Then, we propose a network coding based packet scheduling method to maximize the system input rate under the queue stability constraint. Our analytical and simulation results demonstrate the effectiveness of the proposed solution.

In the literature, the performance of multihop wireless networks is extensively analyzed over various fading channels subject to an additive white Gaussian noise (AWGN). However, and to the best of authors’ knowledge, the generalized Gaussian noise case has not been considered before. Motivated by this, we therefore analyze the system performance—in terms of the average bit error rate—of a multihop wireless communication system that operates over the $\alpha$ - $\mu$ fading channels perturbed by an additive white generalized Gaussian noise (AWGGN). To this end, we obtain an exact closed-form expression for the average bit error rate (BER) for $M$ -ary quadrature amplitude modulation ( $M$ -QAM) over the $\alpha$ - $\mu$ fading channels with AWGGN. Some representative numerical results are presented to study the influence of the fading parameters, as well as the influence of the shaping noise parameter. These results are supported with Monte-Carlo simulations to validate our analysis.