Broadband connectivity and mobile technology have been widely applied in the world. With these advanced technologies, the proliferation of smart devices and their applications by accessing mobile internet have come up with a giant leap forward, leading to the ever-increasing scale and complexity of cellular networks. This presents imminent challenges to anomaly detection in cellular networks. In this study, the authors discuss challenges and current literature of anomaly detection for cellular networks to embrace the ‘big data’ era. First, they review the state-of-the-art techniques in the area of anomaly detection in cellular networks. Then, the challenges are pinpointed for anomaly detection due to the cellular network big data. Finally, they introduce a big data analytic-based anomaly detection method for cellular networks.

Vehicular ad-hoc networks (VANETs) despite their potential benefits, especially for intelligent transportation and safety systems face some important challenges. The main challenges are caused by high mobility of vehicles and dynamic environment. In addition, VANET channel is wireless and is extremely error prone. To overcome these problems, several routing strategies have been proposed in order to find paths with high reliability and low delay. One of these strategies is the opportunistic routing (OR) paradigm where its performance can be significantly affected by the method applied for prioritised transmission to the nodes within the relays set. The OR protocol proposed in this study is based on the Dempster–Shafer evidence theory. In this method, the source vehicle employs the packet advancement, vehicle density, and packet delivery probability as parameters for determining the appropriate vehicle as to the next hop. The number of vehicles participating in forwarding the packets is optimised using trust-based calculations. In addition, the source vehicle can schedule a set of relay nodes based on their degree of trust. Highway environment simulations suggest that compared to other published methods in the literature, the proposed method can improve routing performance in terms of all quality-of-service metrics.

The asymptotic performance and optimisation of systematic fountain codes are investigated on Rayleigh fading and Nakagami fading channels. Firstly, the closed-form bit error rates (BER) of systematic LT (SLT) codes and systematic Raptor (SR) codes are derived based on Gaussian approximation method, the results of which are close to that obtained by discretised density evolution. Secondly, a novel optimisation model combining linear programming and theoretical error probability is proposed to design the degree distributions of SLT/SR codes on fading channels. The simulation results show that the optimised codes provide better BER performance than the codes originally designed for binary erasure channel and additive white Gaussian noise channel. Moreover, the proposed method is easily extended to Rician fading channel and unfading channel.

The study of using the Global Navigation Satellite System (GNSS) to locate Geostationary Earth Orbit (GEO) satellites is very valuable. In this thesis, a new RF strategy is proposed. The back-lobe signal and the main-lobe signal of GNSS satellites are used to provide positioning services for GEO satellites and the receiver antenna beam-forming method is used to improve receiver sensitivity. Additionally, this thesis proposes a satellite selection algorithm that matches the proposed RF strategy. The simulation found that the receiver needs higher sensitivity to detect the back-lobe signal of the GNSS satellite but that the number of visible satellites had doubled and the geometric distribution of the satellite had also been greatly improved. The simulation based on the measured data proves that using a 16*16 antenna array and beam-forming by maximum signal-to-interference and noise ratio algorithm can make five beams of GNSS receivers in GEO orbit and that the side-lobe suppression ratio is up to  dB, which greatly improves the signal receiving gain. After adopting the above technology, the GPS positioning accuracy of GEO spacecraft can be optimised from the order of kilometres to the metres.

Establishing secured communication among the intended users of wireless networks is a major concern. Especially, providing confidentiality is a critical requirement in a wireless communication system which is more susceptible to eavesdroppers. Prevailing cryptographic methods were proven to meet the security needs to some extent. Sophisticated encryption techniques cannot be always deployed in wireless devices, where the resources are limited. However, physical layer security is recently emerging into a promising paradigm to aid security in wireless networks by exploiting the dynamics of wireless channel. In this study, a physical layer security technique was proposed to enhance confidentiality which selects the modulation type adaptively, based on both channel signal-to-noise ratio and phase between transmitter and receiver. The performance of the proposed technique is evaluated for two types of eavesdroppers such as random and intelligent attackers through simulations. The proposed method improves confidentiality and throughput while maintaining the targeted symbol error rate than the existing algorithms.

Resource allocation in wireless communication systems is of great concern in order to guarantee the efficient utilisation of scary resources. In space–time block codes-based multiple-input multiple-output with orthogonal frequency division multiplexing (STBC-MIMO-OFDM) system, scheduling the appropriate user to the available antenna is the major challenge. To overcome the challenge, this study proposes a priority-based scheduling mechanism using the hybrid optimisation, Dolphin-Rider Optimisation (DRO), which is a combination of Dolphin Echolocation Algorithm and Rider Optimisation Algorithm. The prioritisation follows the power and quality of service constraints of the users in such a way that the energy efficiency is enabled in the system. The performance of the system is analysed using the Rayleigh and Rician channels with the transmission media as, text, audio, and image. Moreover, the comparative analysis of the proposed DRO is enabled using three modulation schemes, Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying, and quadrature amplitude modulation. The proposed user scheduling mechanism with the BPSK modulation is found to be effective with a minimal bit error rate and maximal throughput of 3.78×10⁻⁷ and 0.875.

Voice quality assessment of phone calls is a relevant task for mobile service providers. In this context, the main objective of this research is to provide a model that improves the performance of ITU-T Rec. P.563. To accomplish this objective, the proposed model considers two aspects, better response in lossy network and adequate treatment of silences segments into the audio signal. Thus, a function is determined to suppress silences in the speech signal according to the packet loss rate value. Furthermore, the proposed model is implemented on both a voice quality server and a mobile device. Experimental results show that P.563 algorithm performance was really improved by the proposed model, approximating its results to those given by P.862 algorithm, reaching a Pearson correlation coefficient of 0.9957 and a root mean square error of 0.2983. Moreover, subjective test results demonstrated that the proposed model results overcome those obtained by the P.563 algorithm.

In this paper, the authors investigate a multiuser massive multi-input-multi-output (MIMO) relay system with mixed analog-todigitalconverter (ADC) architecture. It is assumed that the channel state information (CSI) is imperfect between the relay and the user. Sum Spectral efficiency (SE) and Energy efficiency (EE) with the maximum-ratio combining (MRC) detector are derived. In addition, the authors have studied the trade-off between achievable Spectral efficiency and energy efficiency. it is revealed that the trade-off between the sum SE and EE with respect to key system parameters, including number of BS antennas, user transmit power, the power of the CSI error, and the quantization bits. Finally, numerical results show that the mixed-ADC structure can obtain a better energy-rate trade-off than low-precision ADC structure.

Device-to-device (D2D) and heterogeneous networks (HetNets) are two promising technologies to be introduced in the upcoming 5G network, for improving spectral efficiency and decreasing latency. However, sharing the same spectrum resources among different tiers of HetNet raised the interference challenge. In this paper, cross-tier interference management for underlay D2D users is studied in a heterogeneous macro-small cell network assuming imperfect channel state information (CSI). The network consists of one macro-cell with a centered macro-base Station (MBS) and several small-cell base stations (SCBS). Two types cellular users are considered; macro-cell cellular user equipment (MUE) associated with the MBS, and small-cell cellular user equipment (SUE) linked to SCBS. While two types of D2D users are considered; macrocell D2D (MD) located outside the range of the small cells and cross-tier D2D user equipment (CD), where each user of the D2D pair belongs to different network tier. Closed form expressions for the D2D optimal power that aim to maximize the coverage probability and the signal-to-interference-noise ratio (SINR) of both links are derived, while guaranteeing the quality of service (QoS) requirements for the cellular user. The effect of channel estimation error on the performance of both D2D and cellular users is evaluated.

An optical network based on elastic optical switches allows requests using different spectrum widths to improve utilisation efficiency. This study considers one three-stage WSW (waveband switching-space switching-waveband switching), optical node architecture for elastic optical networks. A sufficient condition for a rearrangeable non-blocking WSW architecture with limited input/output links has been derived in an earlier work. In this study, the author improves the upper bound by adopting a new interstage link partition scheme associated with a tricky routing algorithm. Suppose a WSW architecture has r input/output links each of which has n frequency slot units (FSUs). Compared with earlier results, the results of the proposed scheme show that s − 1 (or 3s − 4) FSUs per interstage link can be reduced for even (or odd) min{r, n}, where s = min{⌈r/2⌉, ⌈n/2⌉}. The reduction gain is at least 3.5% (or 10%) for even (or odd) min{r, n} if r = n ≤ 26, even achieving 23.3% for limited odd r = n.

Geolocation of mobile nodes with non-orthogonal multiple access (NOMA) is a crucial process for enabling advanced location-based services (LBSs) in 5G networks. In this study, the authors investigate the theoretical limits of received-signal-strength (RSS)-based positioning for uplink cooperative NOMA under different network conditions with special emphasis on the user fairness feature. In addition, they compare the performance of the RSS-based positioning of cooperative NOMA with that of orthogonal multiple access (OMA). The Cramer-Rao lower bounds are derived in order to show the fundamental limits of position estimation error by taking amplify-and-forward and decode-and-forward relaying into account. The numerical results for both schemes are presented and compared considering the effects of number of relays and user equipments, different relaying on the performance of RSS positioning. The effects of power allocation on the user fairness of cooperative NOMA are also investigated. The results show that the cooperative NOMA outperforms cooperative OMA in terms of positioning. It provides high precision position accuracy and user fairness under different network conditions. Hence, the results suggest that the RSS-based positioning for uplink cooperative NOMA is a promising technique for achieving user fairness and supporting diversified low-cost LBSs in 5G networks.

There are different types of messages containing different priorities in vehicular ad hoc networks. Hence, queue rescheduling is required according to priorities of arrived messages. In this study, a data structure with less computational complexity is proposed to minimise queuing delay. Further, to maintain quality of service, preemptive priority is applied to time-bound safety messages by transferring non-safety messages to other bands using the concept of cognitive radio technology. The time-bound messages are transmitted using the dedicated short-range communication spectrum without the need for spectrum sensing by vehicles. The other messages with no deadline constraint are switched to other bands near-dedicated short-range communication spectrum. The results show that 6.25% improvement in packet delivery ratio of cognitive radio-enabled preemptive priority is achieved in comparison to existing cognitive radio protocol. The delay shows a slight increment of 1.1%. The packet delivery ratio of cognitive radio-enabled non-preemptive priority is improved by 3.24% while the delay is improved by 3.17%. The data storage required for storing sensing data of 50 channels for 10 days is only 45 Mb.

This study deals with semi-blind (SB) channel estimation of multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) system using maximum likelihood (ML) technique. For the ML cost optimisation function, new expectation maximisation (EM) algorithms for the channel taps estimation are introduced. Different approximation/simplification approaches are proposed for the algorithm's computational cost reduction. The first approach consists of decomposing the MIMO-OFDM system into parallel multiple-input single-output OFDM systems. The EM algorithm is then applied to estimate the MIMO channel in a parallel way. The second approach takes advantage of the SB context to reduce the EM cost from exponential to linear complexity by reducing the size of the search space. Finally, the last proposed approach uses a parallel interference cancellation technique to decompose the MIMO-OFDM system into several single-input multiple-output OFDM systems. The latter are identified in a parallel scheme and with a reduced complexity. The performance of the proposed approaches are discussed, assessed through numerical experiments and compared with respect to the Cramèr Rao Bound and to other EM-based solutions reported in the literature.

Internet of things (IoT) is a revolution of the internet where a group of computing devices, sensors, machines or people, having unique identifiers and the ability to transfer data over the network without human intervention, are interconnected. Opportunistic networks (OppNets) are a type of disruption-tolerant networks, where network topology is not fixed and the devices are connected intermittently. Opportunistic IOT (OppIoT) is a blend of OppNets and IoT networks, where the data are shared among IoT devices and human communities exploiting the opportunistic contact nature of humans. The data is usually transmitted in a broadcast manner, exposing it to all the members of the network. Thus, securing the data transmitted is of utmost importance in OppIoT. This article proposes a trust-based schemE (called T_CAFE ) for securing the network against several attacks like sybil, bad mouthing, good mouthing, black hole and packet fabrication attacks. Using the opportunistic network environment simulator for performing simulations, it is found that the proposed T_CAFE protocol enhances the network security and outperforms routing protocols such as SHBPR, RSASec and ATDTN in terms of legitimate packet delivery, higher probability of message delivery, lower count of dropped messages and lower value of latency in packet delivery.

Quadrature spatial modulation (QSM) is one of the most prevalent transmission techniques for future wireless mobile network due to its high spectral efficiency (SE) and low complexity. However, it is restrictive to downlink of the cellular network deployments. Therefore, this paper proposes QSM for the multiuser uplink data transmission that increases the SE of the network by deploying multiple antennas at the mobile user with only two radio frequency (RF) chains. Maximum likelihood (ML) decoder is used to detect the received signal and attains the optimal detection performance but it is impractical because of its high computational complexity. Consequently, this paper proposes compressed sensing (CS) based orthogonal matching pursuit (OMP) detection as it has a suboptimal performance with a low computational complexity which can be a practical solution in the high-density uplink multiuser network. However, conventional OMP algorithm has a low estimation performance due to multiuser interference which corrupt channel matrix. Thus, this work design an equalizer that mitigates the multiuser interference and improve the detection performance by orthonormalizing the columns of channel matrix. Simulation analysis confirm that the proposed QSM technique based on CS detector outperforms the conventional schemes in terms of SE and bit error rate (BER).

Channel estimation, which is a key task in massive multiple-input multiple-output orthogonal-frequency division-multiplexing systems (MIMO-OFDM), is severely affected by the problem of pilot contamination during the uplink transmission. Thus, the aim of this study is to investigate, via the Cramér-Rao Bound tool, the effectiveness of semi-blind (SB) methods for pilot contamination mitigation. For synchronous cells, these analyses demonstrate the possibility to efficiently solve the pilot contamination problem, with SB approaches, when considering a finite-alphabet (non-Gaussian) communications signal. However, considering only the signal's Second Order Statistics is not enough for solving such an issue even if the SB approach is adopted. Moreover, the analyses show that it is possible to get close to the optimal performance with a SB approach even if the pilots are non-orthogonal as long as they are not fully coherent. For the asynchronous cells case, it has been demonstrated that the pilot contamination still occurs under small inter-cell delays, but can be strongly mitigated with large inter-cell delays.

The interpolation-based algebraic decoding for Reed–Solomon (RS) codes can correct errors beyond half of the code's minimum Hamming distance. Using soft information, the algebraic soft decoding (ASD) further improves the decoding performance. This paper presents a unified study of two classical ASD algorithms, the algebraic Chase decoding and the Koetter-Vardy decoding. Their computationally expensive interpolation is solved by the module minimisation (MM) technique which consists of basis construction and basis reduction. Compared with Koetter's interpolation, the MM interpolation yields a smaller computational cost for the two ASD algorithms. Re-encoding transform is further applied to reduce the decoding complexity by reducing the degree of module generators. Based on assessing the degree of module seeds, a complexity reducing approach is introduced to further facilitate the two ASD algorithms. Computational cost of the two algorithms as well as their re-encoding transformed variants will be analysed. Performance of the two ASD algorithms will be compared under decoding expenditure benchmark, providing more practical insights of their applications.

This study is targeted towards designing and analysing the X and Ku bands receiving antenna using the Code Blocks software and Advanced Design System simulation tool for energy harvesting in order to satisfy the energy needs of autonomous wireless sensors on board of geostationary satellite for structural health monitoring of the satellite panels, where weight, cost, size and efficiency are the principal space antenna parameters accounted. The energy harvester generally consists of receiving antenna, which harvests and scavenges the circumambient electromagnetic field and inputs the rectifier in order to power the sensors. In this study, a compact, wideband semi-ellipse patch antenna backed with defected ground structure is presented. The antenna compactness (186.8 mm³) is obtained by truncating the elliptical patch to form a semi-ellipse patch without compromising the band of interest which reduces from launching weight and cost. The proposed antenna covers X and Ku bands for voltage standing wave ratio ≤2 with a maximum return loss of 28.75 dB, the efficiency of 95%, the gain of 9.6 dBi and directivity of 14 dBi, which makes the proposed antenna compatible to use with the rectifier in order to satisfy the energy needs of wireless sensors.

In software-defined wide area networks (SD-WANs), finding an optimal number of controllers and their placement is termed as the controller placement problem. The existing solutions based on multi-objective optimisation techniques incur high computation time. Heuristic algorithms based methods quickly converge to local optimum solutions and clustering-based approaches demand that the number of controllers required to be predefined. In SD-WANs, computationally simple solutions for controller placement can be developed using non-parametric clustering algorithms. The proposed modified density peak (modified-DP) clustering algorithm decides the multi-controller placement for the selected networks from the Internet Topology Zoo. The computed performance metrics are compared with hierarchical k-means, modified affinity propagation (modified-AP), and basic DP (basic-DP) clustering algorithms. The criteria importance through inter-criteria correlation method calculates weights of each performance metric, and a normalised weighted additive utility function computes the utility value for the controller placement using each algorithm. The modified-DP computes the minimum utility value and optimal placement of SDN controllers compared to hierarchical k-means, modified-AP, and basic-DP. The Cbench tool calculates the maximum throughput for the controller placement in each network topology. The calculated fairness in the utilisation of the controllers justifies the optimal controller placement using modified-DP.

In this study, cooperative caching is investigated in fog radio access networks. To maximise the offloaded traffic, a cooperative caching optimisation problem is formulated. By analysing the relationship between clustering and cooperation and utilising the solutions of the knapsack problems, the above challenging optimisation problem is transformed into a clustering subproblem and a content placement subproblem. To further reduce complexity, the authors propose an effective graph-based approach to solve the two subproblems. In the graph-based clustering approach, a node graph and a weighted graph are constructed. By setting the weights of the vertices of the weighted graph to be the incremental offloaded traffics of their corresponding complete subgraphs, the objective cluster sets can be readily obtained by using an effective greedy algorithm to search for the max-weight independent subset. In the graph-based content placement approach, a redundancy graph is constructed by removing the edges in the complete subgraphs of the node graph corresponding to the obtained cluster sets. Furthermore, they enhance the caching decisions to ensure each duplicate file is cached only once. Compared with traditional approximate solutions, their proposed graph-based approach has lower complexity. Simulation results show remarkable improvements in terms of offloaded traffic by using the proposed approach.

In this study, advanced multiple-input multiple-output (MIMO) techniques for body-to-body (B2B) sensor-based communication for sporting activities like running and cycling under different scenarios have been proposed. Enhanced spatial modulation and spatial media-based modulation have been investigated for efficient MIMO-based B2B communication. Special sensors have been proposed to deploy such techniques. Lognormal (LN) mixture model has been used because it can address the shadowing effects in B2B communication for such activities. Since LN mixture cannot yield closed-form expressions, it has been approximated using mixture of gamma (MG) distribution to achieve closed-form expressions for bit error rate (BER) in MIMO-based B2B communication for the first time. The system performance for the proposed methods has been analysed in terms of BER and theoretical upper bound expressions using MG distribution have been verified by Monte Carlo simulations.

In this study, the authors consider a multiple-input–multiple-output cooperative communication system, based on a single amplify-and-forward relay over a Rayleigh fading channel. They investigate the performance of two sub-optimal transmit receive antenna selection (TRAS) schemes employing M-ary phase shift keying (M-PSK). They take the advantages of the moment generating function expression, to avoid the hypergeometric functions commonly used in literature. They derive analytical expressions for the symbol error rate (SER) based on two upper bounds of the instantaneous end-to-end signal-to-noise ratio (SNR), which are tightly lower bounded for the SER. In addition, an SER upper bound is derived for both TRAS strategies which gets tighter at high SNR. This upper bound is used to determine the system optimal power allocation. Diversity orders for both TRAS strategies are extracted. Their theoretical analysis shows that the SNR upper bound I is tighter compared to the SNR upper bound II especially for sub-optimal strategy I. At high SNR, the derived SER upper bound approaches the derived SER. Interestingly, it is observed that the optimal power factors lead to a lower SER. Simulation results are presented in comparison with the derived SER for the two upper bounds.

Device-to-device (D2D) communications in cellular networks allow proximity users to communicate directly without going through the base station. Concentrating on scenarios where the direct communication between potential D2D users may not be reliable due to poor proximity and link condition, and paying attention to energy harvesting wireless communications, this study focuses on the green relay-assisted D2D communications, where long-term evolution-advanced layer-3 relays powered by renewable energy are employed. To achieve the trade-off between system capacity maximisation and user fairness, the authors formulate an offline resource block (RB) and power allocation problem under imperfect channel information with the objective of maximising the weighted sum-rate of all users. Then, based on battery dynamics, the original problem is reformulated as an online one with energy outage avoidance. To obtain distributed solutions, the online problem is further transformed into a convex one, and the rate outage-probability requirement is also converted for tractability. Finally, applying Lagrangian duality, the distributed RB and power allocation is derived, which is globally optimal to the reformulated online problem. Comparing with a baseline scheme where all users communicate directly without assistance of relays, numerical results show the superiority of the proposed approach in terms of the average achievable data rate.

The authors study some electromagnetic field representations with a focus on optical communications, light polarisation and phase. Well-known three- and four-dimensional representations are compared with each other and with new ones that are presented and analysed from an analytical point of view. A symmetry emerges in the relationships between the various representations, showing that they are closely related formulas. In fact, different representations point out different characteristics or domains of the same phenomenon. This study results in a more accurate description of the electromagnetic field and especially in its capacity to carry information for telecommunications purposes. From a technological point of view, the partial orthogonality of the described spaces suggests the possibility of exploiting simultaneously more than one representation in order to carry more information or the possibility of using these representations as a natural codifying system with the aim of increasing reliability or confidentiality of communications.

A compressed sensing-based channel estimation (CE) method is proposed for doubly selective channels whilst multiple-input multiple-output (MIMO)–orthogonal frequency-division multiplexing (OFDM) system is employed. According to the simulation results, the proposed CE method, which is dubbed as the MIMO-linearising scheme performs better than the basic expansion model (BEM), which is a state-of-the-art CE method and applies frequency domain scattered pilots. Furthermore, MIMO-linearising can be utilised as an accurate procedure for estimating only the positions of non-zero channel taps in the scenarios where those positions change with a slower rate than amplitudes and phases of the channel taps. Based on that priori estimated positions (PEPs), modified versions of the linearising scheme and the BEM methods, called MIMO-linearising-PEP and BEM-PEP, respectively, are described, showing improvement on performance and spectral efficiency. In addition, by considering the physical characteristic of the vehicular channels, an alternative version of the MIMO-linearising-PEP, called MIMO-linearising-efficient, is described to reduce the computational complexity and increase the spectral efficiency further. Simulation results indicate that the proposed CE methods can measure the channel more accurately and enhance the car detection accuracy in the frames which have been used as the inputs of the communication systems.

Fifth generation cellular networks must support dense user environments where close proximity users and highly correlated channels are prevalent. This study presents a novel decorrelating zero-forcing (DZF) scheme. It improves downlink zero-forcing (ZF) performance over multi-user multiple-input multiple-output channels when highly correlated users are present. DZF groups correlated users into pairs where the stronger user is labelled ‘near’ and the weaker user, ‘far’. For the far and unpaired users, the proposed design is similar to conventional ZF (CZF) in that the base station performs traditional ZF and the users employ the leading left singular vectors of the channel for processing. In contrast, the near users employ the second strongest left singular vector which decorrelates their effective channel with the paired far user. This reduces the noise inflation inherent in ZF for correlated channels. From simulations and analysis the authors demonstrate that DZF has both rate and fairness advantages over CZF when highly correlated users are present. Furthermore, they design a hybrid ZF (HZF) scheme, which harnesses the advantages of both CZF and DZF, hence providing robustness against the joint scheduling of semi-orthogonal and highly correlated users with very little additional complexity. Simulations clearly demonstrate that HZF has higher rates than CZF and DZF.

A relay selection algorithm was proposed to improve a communication rate of D2D (device-to-device) users in-vehicle networking communication systems based on social network combined with Q-learning. The scheme was divided into two steps. Firstly, a social threshold was introduced to filter the potential relay nodes to reduce the number of probing times based on the user's interest similarity in D2D communication network. Then, an optimal relay selection algorithm was proposed to maximise the total rate of D2D links based on a Q-learning algorithm. This method can provide the optimal relay selection scheme to meet the requirements of vehicle networking communication. The simulation results showed that the proposed scheme could reduce the number of probing relays and improve the communication speed of the system on the basis of ensuring communication security.

In a multiple-input multiple-output (MIMO) cognitive radio network, the cognitive users (CUs) coexist with the primary users (PUs) in the same spectrum for boosting the spectrum efficiency. Based on the informed limit of the interference power from the PUs, the CUs' compete to minimise the total interference power generated. In this study, noncooperative and cooperative game theoretic approaches are derived for network interference management (NIM). In the first scenario, the NIM problem computes the sum of minimum individual CU's interference power produced on the PU to converge to equilibrium by using the best response iteration method. The second one, NIM estimates Nash product to converge to Nash bargaining solution by using the dual decomposition method. Numerical results prove the effectiveness of the cooperative scenario that minimises the network interference power. Two new metrics are proposed to evaluate the performance in these scenarios. The interference cooperative loss metric estimates the overall network interference power loss from CUs cooperation rather than non-cooperation in the game theoretic solution. Capacity cooperative gain metric estimates the overall network capacity gain from CUs cooperation rather than non-cooperation in the game theoretic solution for a fixed acceptable interference level.

Microseismic monitoring technology has been used widely in the field of the monitoring of dynamic disaster in hydraulic fracturing. A cable-less self-positioning seismograph, developed by Jilin University, China, can record microseismic data and transmit data through wireless local area networks (WLANs). However, when the system is overseeing too many seismographs, load imbalance among the access points (APs) and channel congestion might prevent it from collecting all the data quickly enough for real-time monitoring. This paper proposes a data-transmission system that combines a load-balancing scheme with a high-throughput polling mechanism in WLANs to allow the real-time transmission. The improved load-balancing scheme allows all the seismographs to associate with the available APs and keeps load balance among the APs. During data transmission, the high-throughput polling mechanism maximizes the total throughput in the WLANs and avoids throughput degradation due to fierce channel collision. Our experimental results show that the performance of the system is significantly improved compared with the original data-transmission system. The time of acquire the data could be reduced by about 70% compared to origin method. The average data-transmission speed of the system is improved 3.5 times relative to the original scheme so it is satisfying for real-time monitoring.

This note aims to report and correct a mistake in the mentioned paper by Min Long et al. An error occurs in the derivation of the average bit error rate for binary signals with non-coherent and coherent detection in Rayleigh fading channels. The corrected derivation is substantiated by the results of Numerical and Monte Carlo simulations.