Achieving high-rate communication with accurate localization and wireless environment sensing has emerged as an important trend of beyond-fifth and sixth generation cellular systems. Extension of the antenna array to an extremely large scale is a potential technology for achieving such goals. However, the super massive operating antennas significantly increases the computational complexity of the system. Motivated by the inherent advantages of lens antenna arrays in reducing system complexity, we consider communication and localization problems with an extremely large lens antenna array, which we call “ExLens”. Since radiative near-field property emerges in the setting, we derive the closed-form array response of the lens antenna array with spherical wave, which includes the array response obtained on the basis of uniform plane wave as a special case. Our derivation result reveals a window effect for energy focusing property of ExLens, which indicates that ExLens has great potential in position sensing and multi-user communication. We also propose an effective method for location and channel parameters estimation, which is able to achieve the localization performance close to the Cramér-Rao lower bound. Finally, we examine the multi-user communication performance of ExLens that serves coexisting near-field and far-field users. Numerical results demonstrate the effectiveness of the proposed channel estimation method and show that ExLens with a minimum mean square error receiver achieves significant spectral efficiency gains and complexity-and-cost reductions compared with a uniform linear array.

Recently, reconfigurable intelligent surfaces (RISs) have drawn intensive attention to enhance the coverage of millimeter wave (mmWave) communication systems. However, existing works mainly consider the RIS as a whole uniform plane, which may be unrealistic to be installed on the facade of buildings when the RIS is extreme large. To address this problem, in this paper, we propose a sparse array of sub-surface (SAoS) architecture for RIS, which contains several rectangle shaped sub-surfaces termed as RIS tiles that can be sparsely deployed. An approximated ergodic spectral efficiency of the SAoS aided system is derived and the performance impact of the SAoS design is evaluated. Based on the approximated ergodic spectral efficiency, we obtain an optimal reflection coefficient design for each RIS tile. Analytical results show that the received signal-to-noise ratios can grow quadratically and linearly to the number of RIS elements under strong and weak LoS scenarios, respectively. Furthermore, we consider the visible region (VR) phenomenon in the SAoS aided mmWave system and find that the optimal distance between RIS tiles is supposed to yield a total SAoS VR nearly covering the whole blind coverage area. The numerical results verify the tightness of the approximated ergodic spectral efficiency and demonstrate the great system performance.

Achieving ultra-reliable, low-latency and secure communications is essential for realizing the industrial Internet of Things (IIoT). Non-coherent massive multiple-input multiple-output (MIMO) has recently been proposed as a promising methodology to fulfill ultra-reliable and low-latency requirements. In addition, physical layer authentication (PLA) technology is particularly suitable for IIoT communications thanks to its low-latency attribute. A PLA method for non-coherent massive single-input multiple-output (SIMO) IIoT communication systems is proposed in this paper. Specifically, we first determine the optimal embedding of the authentication information (tag) in the message information. We then optimize the power allocation between message and tag signal to characterize the trade-off between message and tag error performance. Numerical results show that the proposed PLA is more accurate then traditional methods adopting the uniform tag when the communication reliability remains at the same level. The proposed PLA method can be effectively applied to the non-coherent system.

Achieving ultra-reliable, low-latency and secure communications is essential for realizing the industrial Internet of Things (IIoT). Non-coherent massive multiple-input multiple-output (MIMO) is one of promising techniques to fulfill ultra-reliable and low-latency requirements. In addition, physical layer authentication (PLA) technology is particularly suitable for secure IIoT communications thanks to its low-latency attribute. A PLA method for non-coherent massive single-input multiple-output (SIMO) IIoT communication systems is proposed in this paper. This method realizes PLA by embedding an authentication signal (tag) into a message signal, referred to as “message-based tag embedding”. It is different from traditional PLA methods utilizing uniform power tags. We design the optimal tag embedding and optimize the power allocation between the message and tag signals to characterize the trade-off between the message and tag error performance. Numerical results show that the proposed message-based tag embedding PLA method is more accurate than the traditional uniform tag embedding method which has an unavoidable tag error floor close to 10%.

The transmission capacity of a vehicular network is still an interesting and challenging problem as capacity is impacted by transmission distance between both vehicles, density of vehicles, relay among vehicles, noise and interference. This study analyses the transmission capacity of vehicular device‐to‐device relay networks with multi‐users (service vehicle (SV) and helper vehicle (HV)) in the overlay mode. SVs coexisting with HVs share the spectrum resources. Utilising stochastic geometry theory, SVs and HVs are modelled as the Poisson point process in vehicular networks, respectively. Subsequently, the HVs existence probability and the expectation distance with HV link are derived to calculate the successful transmission probabilities for SV to SV communication. With this characteristic HV relay transmission signals exceed transmission distance, the authors further calculate the transmission capacities with SV to SV communication assisted by HVs and reveal the influence of vehicles' density and transmission power. Besides, the relationship between transmission capacities, the variable direct link distance of SV to SV communication is also analysed. Simulation results indicate that transmission capacity can be improved by an assisted HV and influenced by a few system parameters, including the direct link distance between source SV and destination SV, SVs density and HVs density.

Licensed-Assisted Access Long-Term Evolution (LAA- LTE) framework can offload excessive data stream to the unlicensed spectrum. Devices from different operators will compete for the same band and have to endure a more complex and congested channel conditions. Therefore a rapid and efficient access mechanism should be introduced in the LAA framework. Based on the Type B LBT channel access scheme, this work proposes an Energy-Based Signal Assisted Access (EBSA) mechanism. The EBSA mechanism can realize the rapid information transfer between devices belonging to different operators. Then a Markov chain model is set up and used to analyze this mechanism theoretically. Simulation results verify the validity of the theoretical analysis, and in the ultra-dense employed LAA network, the proposed method is efficient compared with the existing access mechanisms.

Packet collision and packet delay are considered to be critical for safety applications in vehicular networks. This paper designs a new analytical model to evaluate the performance of channel switching for IEEE 802.11p/WAVE in vehicular networks. Under this model, it explicitly expresses the WAVE channel switching, and constructs contention window size and number of vehicles as packet collision probability and packet delay time function of variables. Finally, we evaluate accuracy of the designed model of collision caused by channel switching and transmission delay in vehicular networks. The results show that the model could analyzes perfectly packet collision which is caused by channel switching and packet delay in vehicular networks.

Node location information with high accuracy is very important in many applications of wireless sensor networks. In addition, the nodes are power-limited, hence, we need to save energy to guarantee the operations of network. These two metrics positioning accuracy and energy consumption should be balanced, mean that one should improve them both at the same time. In this paper, we model the energy consumption of nodes in the network by using the carrier-sense multiple-access/collision-avoidance (CSMA/CS) technique in combination with request-to-send (RTS)/clear-to-send (CTS) mechanism based IEEE 802.11 protocol to perform the transmission process of nodes. Otherwise, based on the mathematical model of direction-of-arrival (DoA) estimation error variance as a function of Received-Signal-Strength (RSS) we derive the Cramer-Rao lower bound (CRLB) of achievable accuracy of the target node that jointly utilizes difference-received-signal-strength (DRSS) and DoA measurements to estimate location as the objective function of positioning error. The Non-dominated Sorting Genetic Algorithm (NSGA-II) optimization algorithm can effectively find the Nash Equilibrium or Pareto optimal solutions of our dual objective optimization problem. The results show a high performance in both localization accuracy and energy consumption of the proposed algorithm.

In this paper, we give a closed form expression for the statistics of two independent exponential for two-hop links of vehicular networks. Then these statistics results help us to analyze the performance of two-hop vehicular communication networks with vehicle relay based on Amplify and Forward (AF) protocol over flat Rayleigh-fading channels. It is shown that the choice of gain of AF effects on bounds on the performance of these relay vehicular networks. And outage probability formula is obtained. Furthermore, we give out specifically a vehicle relay selection scheme. The "best" vehicle relay has been selected by satisfying specific criteria in respect of signal-to-noise ratio (SNR). Finally, simulation results display the difference between regeneration and non-regeneration vehicular systems. At low average SNR, AF relay vehicular networks have better performance. However, these two kinds of systems have similar outage probability at high average SNR.

We present optimization algorithm for relay (RLY) selection and, source (SRC) and RLY power allocations in a cooperative multicast millimeter-wave (mmWave) system with non-line-of-sight (non-LoS) sensing. We show that there is a significant benefit to the system outage performance by allocating powers for the SRC and the RLYs selected from the candidates availing of line-of-sight (LoS) paths. Specifically, we consider the joint optimization of RLY selection, and, SRC and RLY power allocations to minimize the largest outage probability among all the common-multicast group (co-MGroup) users. The joint optimization problem is non-convex and the complexity of finding the optimal solution is extremely high. Using the dual-step iterative optimization (DIO) algorithm, the joint problem is decomposed into a non-convex RLY selection, and, a convex SRC and RLY power allocation problem. By exploiting the search method and the Lagrange multipliers algorithm, we present efficient algorithms that yield the optimal solutions for both RLY selection (non-convex) and, SRC and RLY power allocation problems. The simulation results indicate significant improvements both on outage probability and power consumption performances over the traditional two-stage multicasting.

Data collection is a basic application of wireless sensor networks, where every sensor node collects data and then forwards data to the Sink node through a multi-hop path. In traditional TDMA scheduling, sensors consume extra energy because of the state transitions which occur numerous times in a TDMA frame. And the longer the length of a TDMA frame, the longer duration of a data collection and the larger of time latency. For the problem mentioned above, Slot Reuse Continuous Link Scheduling problem is proposed in this paper, and then formalized into a cross-layer optimization problem involving the network, medium access control, and physical layers with the objective of maximizing the energy efficiency. We transform the problem into two sub-problems: constructing a data collection tree; joint power control and link scheduling for the data collection tree. Based on an existing data collection tree, we propose an algorithm for allocating a continuous slot and transmission power on every link. Simulation results show that the proposed algorithm can shorten the duration of a data collection process, reduce the number of state transitions and energy consumption, improve network energy efficiency when compared with other existing data collection strategies.

In this work, we consider outage performance for a 5G wireless cellular network consisting of multiple cooperative multicast groups (MGroups) under kinds of fading channels, which allows users adhering to different MGroups can be served simultaneously. Based on the law of total probability theory, we first propose a new analytical approach to derive a new probability density equality lemma, which can be used to upper bound average outage probability of multiple MGroups (MMGroups) systems with interference-aware spectrum sharing transmissions in the case that interference channel state information (CSI) is known. After then, based on the proposed probability density equality lemma, we also analyze average outage probability upper bound under kinds of fading channels with inter-MGroup interferences. The simulated results reveal that the derived upper bounds indeed provide upper bounds over the average outage probability of MMGroups systems operated on kinds of fading channels, and these bounds become tight when interferences decrease or outage thresholds drop.

This paper proposes a novel relay selection strategy based on the feedback beamforming (BF) information for 60GHz millimeter-wave (mmWave) wireless communication systems under non-line-of-sight (NLoS) condition. First, an approach of collecting instantaneous channel state information (CSI) through overheard during BF is devised. Second, with the aim of maximizing overall network throughput capacity, the optimal relay selection issue for NLoS links is formulated as a bipartite graph, and the Kuhn Munkres (KM) algorithm is provided to resolve it. Third, both theoretical analysis and simulation results show that the improvements achieved over the best harmonic mean selection scheme in terms of overall network throughput capacity and outage probability.

In this paper, a joint design of axis alignment and positioning under non-line-of-sight (NLoS) indoor conditions or 60 GHz millimeter-wave (mmWave) wireless local area networks/wireless personal area networks (WLANs/WPANs) is proposed. First, an axis alignment scheme called rotation vector method is proposed, in which the newly joining station (STA) rotates x- and y-axis based on the proposed two-step-wisely refinement principle to make its axis aligned with the personal basic service set (PBSS) control point/access point (PCP/AP). Second, the equipotential region (ER) based positioning approach is carried out for the newly joining STA in a conference room rich with obstacles. Finally, our proposed joint design is evaluated both through theoretical analysis and simulation. The results show that the number of rotation is reduced by the proposed axis alignment scheme without cost of the alignment accuracy under a same condition, and the positioning accuracy is increased by the proposed joint design.

This paper proposes a novel link scheduling strategy for concurrent transmission in millimeter-wave (mmWave) wireless personal area networks (WPANs) based on beamforming information. Firstly, we consider the signal-to-interference-plus noise ratio (SINR) as the links coexistence criterion, and derive the interference model with different antenna configurations. Then we describe how to use the beamforming information to calculate the SINR for concurrent transmission in a common service period (SP). A first-request-first-scheduling (FRFS) SINR based algorithm is applied to schedule links in SPs. Simulation results show that the proposed link scheduling scheme performs well and achieves a higher spatial multiplexing gain.

In this paper, a hybrid MAC based on-line resource management scheme, which considers QoS, fairness, and hybrid MAC, for kiosk service in 802.15.3c millimeter-wave system is proposed. In particular, a heuristic success oriented dynamic CAP duration determination (S-CDD) method is designed. Then, after satisfying the basic service rate requirements, fairness concerned multi-user CTA allocation algorithm (MCAA) which takes charge the CTA allocation is designed conditioned on different BER scenarios. Finally, simulations are conducted to validate the effectiveness of S-CDD method and the performance of MCAA.

The limited bandwidth and the finite battery power of mobile devices represent one of the greatest limitations of current WPANs. In this paper, an analytical model for the energy efficiency of the IEEE 802.15.4 slotted CSMA/CA which can be studied as slotted non-persistent CSMA was proposed and validated. Key to the accuracy of the model is a careful study of the idle period after last collision, which has been studied by Zhang et al. (2006). Specifically, a distributed mechanism to improve the energy efficiency for contention control in IEEE 802.15.4 was also present and evaluated and show that power saving and throughput maximization can be jointly achieved. Simulation results indicate that our mechanism is very effective and robust. This mechanism can be used to extend the standard 802.15.4 access mechanism without requiring any additional hardware.