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This paper provides a comprehensive performance comparison between a current robust military waveform; namely, MIL-STD-188-110D, Waveform 0, and a filter bank multicarrier spread-spectrum (FBMC-SS) waveform proposed for communications through ionospheric/skywave HF channels. Waveform 0 is effectively a direct sequence spread spectrum waveform that uses Walsh multi-codes to enhance the information transmission rate. It may thus be referred to as Walsh-DSSS. FBMC-SS, on the other hand, makes use of filter banks to provide excellent performance when the received signal is subject to partial band interference. Successful application of FBMC-SS for communications across skywave HF channels has been previously demonstrated, both theoretically and through experimental work. However, very little has been done to contrast FBMC-SS against Walsh-DSSS. The goal of this paper is to first add new features to FBMC-SS to bring it on par with Walsh-DSSS. These features include: (i), introduction of multi-codes that achieve a comparable (or better) data rate to Walsh-DSSS; and (ii), addition of a scrambling step applied to the multi-codes to make the receiver detection robust against widely spread multipaths. With this established, in the second part of the paper, we examine the performance of the developed FBMC-SS against Walsh-DSSS when both are applied for communications across skywave HF channels. The two waveforms are compared both through a theoretical study and through experimental works across several skywave channels ranging from hundreds to thousands of kilometers. [ABSTRACT FROM AUTHOR]

This paper analyzes priority-based distributed access control in vehicular networks. Characterizing the spatial correlation between vehicles, users, and roads, this paper uses Cox point processes to model vehicles and users, respectively. Then, this paper proposes that each vehicle transmits if it has the highest priority among all of its neighbors. Using the stochastic geometry framework, this paper derives the probability that a typical vehicle is retained to transmit. Then, this paper derives a second-order moment measure of the retained point process to evaluate the signal-to-interference (SIR) distribution of a typical user. The derived SIR distribution is compared to the system-level simulation of the SIR distribution of a typical user. [ABSTRACT FROM AUTHOR]

In this paper, we propose a reference-modulated permutation index differential chaos shift keying (RM-PI-DCSK) over multipath fading channels. Due to quasi-orthogonal property between different permutated chaotic signals, the proposed scheme can remarkably suppress the inter-sequence interference to recover the desired information. Moreover, the proposed RM-PI-DCSK has one more modulation bit in the reference segment than the conventional permutation index differential chaos shift keying (PI-DCSK). Both the reference signal in the first time-slot and a permuted replica of the reference in the second time-slot are modulated for efficient transmission. The theoretical bit-error-rate (BER) performance and the highly consistent simulation results demonstrate that the proposed RM-PI-DCSK can achieve a performance gain 3 dB over the conventional PI-DCSK at a BER of $10^{-4}$ , and this gain becomes larger in a high-delay-spread channel. In particular, the performance superiority of the RM-PI-DCSK is further demonstrated in a typical ultra-wideband (UWB) channel with narrow-band interference. Therefore, this proposed scheme can be deemed as an efficient transmission alternative for chaotic-based wireless communications, such as in wireless local area network (WLAN) applications and indoor applications of the transmitted-reference UWB. [ABSTRACT FROM AUTHOR]

In connected vehicular networks, it is vital to have vehicular nodes that are capable of sensing surrounding environments and exchanging messages with each other for automating and coordinating purposes. Towards this end, integrated sensing and communication (ISAC), combining both sensing and communication systems to jointly utilize their resources and pursue mutual benefits, emerges as a new cost-effective solution. In ISAC, the hardware and spectrum co-sharing leads to a fundamental tradeoff between sensing and communication performance, which is not well understood except for very simple cases with the same sensing and channel states, and perfect channel state information at the receiver (CSIR). In this paper, a general point-to-point ISAC model is proposed to account for the scenarios where the sensing state is different from but correlated with the channel state, and the CSIR is not necessarily perfect. For the model considered, the optimal tradeoff is characterized by a capacity-distortion function that quantifies the best communication rate for a given sensing distortion constraint requirement. An iterative algorithm is proposed to compute such tradeoff, and a few non-trivial examples are constructed to demonstrate the benefits of ISAC as compared to the separation-based approach. [ABSTRACT FROM AUTHOR]

Although LoRa modulation can achieve low-power and long-range transmission, its performance is significantly affected by fading channels. On the other hand, its low data rate limits the capacity. To mitigate these disadvantages, a new reconfigurable intelligent surface (RIS) assisted LoRa uplink system is proposed in this paper, where the reflection coefficients of the RIS are generated by utilizing an $M$ -ary differential phase shift keying modulator. Moreover, a low-complexity non-coherent receiver is designed for the proposed system. The new system is able to inherit the non-coherent detection of the conventional LoRa system and also transmit additional information of $\log _{2}{M}$ bits while reducing the impact of the fading channels. Furthermore, the bit-error-rate, symbol-error-rate and throughput expressions of the system are derived in closed form. Theoretical and simulated results show that the system has better performance than the conventional LoRa system and single-relay LoRa system. [ABSTRACT FROM AUTHOR]

From adapting to the propagation environment to reconstructing the propagation environment, reconfigurable intelligent surface (RIS) changes the design paradigm of wireless communications. To reconstruct the propagation environment, joint beamforming of RIS and multi-input multi-output (MIMO) is crucial. Unfortunately, due to the coupling effect of the active beamforming of MIMO and passive beamforming of RIS, it is difficult to find the optimal solution to the joint beamforming problem, so a serious performance loss will be caused. In this paper, inspired by the end-to-end (E2E) learning of communication system, we propose the E2E learning based RIS-aided communication system to mitigate the performance loss via deep learning techniques. The key idea is to simultaneously optimize the signal processing functions at base station (BS), RIS, and user, including active beamforming for BS and user, passive beamforming for RIS. This way is able to avoid the performance loss caused by alternately optimizing each function of the RIS-aided system. Specifically, we firstly utilize a deep neural network (DNN) to realize the modulation and beamforming for BS and utilize another DNN to realize the demodulation and combining for user. Then, the RIS passive beamforming is also represented by trainable parameters, which could be simultaneously optimized with the DNNs at BS and user. Simulation results show that the proposed E2E learning based RIS-aided communication system could achieve the better bit error rate (BER) performance than traditional RIS-aided communication systems. [ABSTRACT FROM AUTHOR]

The proliferation of IEEE 802.11 or WiFi networks, and the explosive growth in traffic demands call for solutions to maximize the capacity of WiFi networks. Hence, maximizing the spatial reuse of WiFi networks is critical as doing so allows multiple concurrent transmissions. In this respect, a critical network parameter, Clear Channel Assessment (CCA) threshold, plays a vital role as it dictates whether a node is allowed to transmit after sensing the channel. In this paper, we propose to use Deep Q-network (DQN) under two learning patterns to select the CCA threshold of devices. We further consider Transmit Power Control (TPC) in conjunction with CCA threshold selection to improve the capacity of a WiFi network. The simulation results show that our approach is capable of selecting the optimal CCA threshold for each device. As a result, the average throughput is 62.4% higher than that of a legacy Dynamic Sensitivity Control (DSC) algorithm. [ABSTRACT FROM AUTHOR]

In this paper, we propose a game theoretic framework for secure physical layer authentication (PLA) by applying the spatial correlations of received signal strength (RSS) in the air-to-ground channels between an unmanned aerial vehicle (UAV), a legitimate transmitter, and a spoofer. Based on our hypothesis model, we first derive the false alarm rate and miss detection rate for the UAV receiver. We then formulate a zero-sum PLA game where the UAV receiver selects its RSS detection threshold while the spoofer selects its attack probability to maximize their respective utilities. We derive the Nash equilibrium (NE) and its existence condition for the proposed PLA game. Monte Carlo simulation results accurately verify our analytical expressions for the false alarm rate and miss detection rate. Numerical results highlight the complex interplay between the detection threshold, spoofing attack probability and UAV altitude in the derived NE. [ABSTRACT FROM AUTHOR]

Cache-enabled Device-to-Device (D2D) communications, recognized as one of the key enablers of the fifth generation (5G) cellular network, are a promising solution for reducing the great burden on mobile core networks and backhaul links. Caching, however, imposes a new networking user Key Performance Index (KPI), which is the probability of user satisfaction. In other words, how likely is it that the user will obtain the necessary information from the network? Such probability depends on the type of transmission, (i.e., half duplex or full duplex) and on many elements related to the caching system, including the way the information is cached or the popularity of the cached information. The analysis of those elements produces different modes of operation. To evaluate the new KPI, the probabilities of each mode of operation must be extracted from the transmission and caching conditions. This paper presents a thorough analysis of those probabilities, including the relevance of the relationship between caching policies, content popularity and transmission types. Such relationships allow the smooth evaluation of user satisfaction under different conditions. [ABSTRACT FROM AUTHOR]

Dynamic wireless charging (DWC) is one of the most promising and economical power supply solutions for electric vehicles (EVs), which can address range anxiety and downsize the volume of onboard batteries. To solve the null power phenomenon and transfer power pulsation phenomenon in DWC scheme, this paper proposes a new magnetic coupler array to implement continuous charging and reduce the output power variation. The transmitters are placed with a proper interval to eliminate the adjacent coupling and enlarge the coil array’s effective length. ANSYS Maxwell is utilized to demonstrate the finite element analysis (FEA) of the DWC system. A larger receiver coil is designed to significantly mitigate power pulsation and increase the magnetic coupling as the receiver moves along the array. With the well-designed receiver coil, the output power pulsation is $\pm$ 1.52 $\%$. For the high-power capacity scenario, a multilevel connected DC-DC converter is designed on the receiver side to regulate the transfer power. Besides, a passivity-based control (PBC) is developed for the receiving DC-DC converter based on the Euler-Lagrange (EL) model, and a current sharing compensator is employed to balance each phase inductor current. Finally, a 500- $\text{W}$ prototype is constructed, and experimental results are represented to validate the proposed optimized coil array and the proposed PBC method. [ABSTRACT FROM AUTHOR]

Faster-than-Nyquist signaling (FTNS) has emerged as a promising technique to increase communication capacity in bandwidth-limited channels. However, the presence of FTN-induced inter-symbol interference (FTN-ISI) in the received observations, is detrimental to channel estimation (CE) and data detection in terms of computational complexity and performance. This paper copes with these problems by incorporating linear pre-equalization (LPE) and composite precoding formed by linear spectral precoding and Tomlinson-Harashima precoding (THP), into the FTNS. Specifically, LPE completely pre-equalizes the FTN-ISI, while spectral precoding resolves the LPE-caused signal spectral broadening by introducing proper artificial ISI, which is pre-equalized by THP. Channel-induced ISI, as the only ISI component in the observations, is estimated and equalized using the classical frequency-domain low-complexity schemes. We show that there are four advantages of the LPE-aided CE over the CE designed for the FTN transmissions without FTN-ISI pre-equalization, namely lower pilot overhead, simpler yet optimal pilot sequence design, lower mean-squared error of CE, and more robust against the FTN-ISI. Simulation results show that our scheme improves the performance of CE and detection, compared to existing FTN frequency-domain CE and equalization schemes. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the precoding scheme for multiple-input multiple-output multiple antennas eavesdropper (MIMOME) channels under the constraint of finite-alphabet inputs to ensure secure transmission between the source and the destination in the presence of an eavesdropper. With finite-alphabet inputs, there are no closed-form solutions for mutual information (MI) and its gradient-minimum mean-square error (MMSE) matrix. Therefore traditional precoding schemes based on direct calculation of MI and MMSE matrix through numerical integration involve prohibitive computational burden. To address this problem, this paper first derives asymptotically optimal lower bounds of MI and ergodic MI with which the computational complexity can be significantly reduced compared with the direct computation of MI. With the derived lower bounds, a low-complexity precoding scheme is proposed to maximize the secrecy rate, wherein a gradient descent based algorithm is used to obtain the precoding result. In the low and high signal-to-noise ratio (SNR) regions, we demonstrate that the proposed precoding scheme gives the same result as directly maximizing the secrecy rate, which indicates that the proposed low-complexity precoding scheme is asymptotically optimal. [ABSTRACT FROM AUTHOR]

This paper investigates covert communications with finite blocklength in the presence of multiple randomly distributed wardens, which are modeled as a Poisson point process (PPP). Specifically, the protection area, which is guarded by the transmitter against the wardens, is introduced in order to enhance the covert communication performance. First, the closed-form expressions of covert communication constraint are derived under both the non-colluding and colluding detection strategies over the channels suffering both path-loss and small scaling fading. Then, considering the constraint of maximum available blocklength, the transmit power and the blocklength are jointly optimized to maximize the average effective covert throughput (AECT). Differing from the existing literature with only one warden, it is demonstrated that the increasing of maximum available blocklength causes the improvement of maximum AECT only when the density of warden is small. In addition, our examinations show that the expansion of the protection area indeed improves the maximum AECT, and the improvement under the non-colluding detection strategy is more significant than that under the colluding detection strategy. [ABSTRACT FROM AUTHOR]

Multiple-input-multiple-output (MIMO) systems significantly increase the network throughput and coverage probability for short-packet communications. In this paper, a tight lower bound on the average achievable rate of MIMO short-packet communication systems is theoretically derived, considering flat uncorrelated Rayleigh fading MIMO channels. The derivations are based on the eigenvalue analysis of a Wishart matrix and Jensen's inequality. Given the actual transmission rate, a tight approximation on the average block error rate (BLER) of MIMO short-packet communication systems is also provided, which is based on the moment generating function and inverse Laplace transform. Numerical results demonstrate that both our theoretically derived analytical average achievable rate lower bound and approximate average BLER are almost the same as the simulation results. [ABSTRACT FROM AUTHOR]

Device-to-device (D2D) communication affords the benefits of improved network spectral efficiency, throughput, energy efficiency, and delay performance. However, D2D communication underlaid cellular uplinks are degraded by interference between D2D user equipment (DUE) and cellular user equipment (CUE) that use the same frequency band. In this context, researchers have proposed the optimization of the transmit power of the devices to mitigate interference. This power allocation problem is generally modeled as a NP-hard combinatorial optimization problem with linear constraints; therefore, traditional optimization methods are ineffective in addressing the problem. In this paper, we apply a deep reinforcement learning (DRL) algorithm to optimize the transmit power for both DUEs and CUEs in the context of D2D communication underlaid uplink cellular networks, which can solve the optimization problem via optimal decision-making together with efficient deep network training. Our simulation results show that the proposed algorithm affords a near-global-optimum solution with lower computation complexity than exhaustive search, and outperforms the fixed-power, weighted minimum mean square error (WMMSE), gradient descent method, and Newton-Raphson approaches. [ABSTRACT FROM AUTHOR]

In this paper, we consider an intelligent reflecting surface (IRS) enabled mobile network, where a fixed access point (AP) communicates with a mobile user (MU) via the aid of an IRS. We assume that the MU moves from one elementary square to another following a Markov random walk within a grid, and propose a maximum a posteriori (MAP) criterion to track the movement of the MU by leveraging the line-of-sight component of the IRS-MU link. Since it is infeasible to derive an explicit expression for the average probability of estimation error (APEE) for the proposed MAP criterion, we derive a closed-form upper bound for the APEE, which is used as the cost function to optimize the phase shifts of the IRS units. Considering the unit modulus constraints incurred by the IRS units, a manifold optimization (MO) method is firstly employed to gain a favorable solution to the formulated optimization problem, followed by a low-complexity codebook based solution to circumvent the high computational cost of the MO method. Our numerical results demonstrate the superior performance of the proposed IRS phase shift designs over the benchmark method. [ABSTRACT FROM AUTHOR]

The benefits of intermediate couplers (IC) in inductive power transfer (IPT) systems are well documented in the literature. However, the lack of guideline rules makes the selection process of the passive components and operation mode difficult. This paper presents an iterative design methodology based on the equivalent mathematical model of the system to determine the optimal magnetic coupler (MC) dimensions and resonant tanks parameters that operates the system in a quasi constant current mode. It was found that the transconductance function of a series-series (SS) with an intermediate coupler exhibits a quasi-load independent characteristic when the reflected reactance from the receiver side is null. The design methodology then combines the self and mutual coupling profiles of the MC, obtained from a finite element analysis (FEA) tool, with the system specifications and constraints to find all possible solutions. A set of selection metrics are proposed to identify the optimal solution. This work also presents an identification method of the load and mutual inductances based only in the information available from the transmitter side. The proposed method uses the steady-state equations and does not require any form of communication to the receiver side. An experimental prototype was built and assembled in a converted combustion vehicle with efficiency of 89 $\%$. [ABSTRACT FROM AUTHOR]

The study of the fundamental limits of covert communications, where a transmitter Alice wants to send information to a desired recipient Bob without detection of that transmission by an attentive and capable warden Willie, has emerged recently as a topic of great research interest. Previous work has assumed that the distribution of the multipath fading on the channel, which we term the channel distribution information (CDI), is known to Alice, hence facilitating her characterization of Willie's capabilities to detect the signal. However, in practice, Willie tends to be passive and the environment heterogeneous, implying a lack of signaling interchange between the transmitter and Willie makes it difficult if not impossible for Alice to estimate the CDI exactly and provide covertness guarantees. In this paper, we address this issue by developing covert communication schemes for various assumptions on Alice's imperfect CDI: 1) when the transmitter knows the channel distribution is within some distance of a nominal distribution; 2) when only the mean and variance of the channel distribution are available; 3) when Alice knows the channel distribution is complex Gaussian but the variance is unknown. In each case, we formulate new optimization problems to find the power allocations that maximize covert rate subject to a covertness requirement under uncertain CDI. Moreover, Willie may be able to estimate CDI exactly or be faced with an error in estimation, and we investigate two these issues. Numerical results are presented to compare the proposed schemes from various aspects, for attaining desirable covert system performance. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the use of reconfigurable intelligent surfaces (RIS) to allow multiple user pairs to communicate simultaneously over the same channel. We propose a Riemannian manifold optimization approach to solve the problem of configuring the RIS passive reflection coefficients to minimize the total interference under constant modulus constraints. We compare the proposed approach to the widely-used semidefinite relaxation approach (SDR) for dealing with the constant modulus constraints. We investigate, using extensive numerical simulations, the effects of various system parameters, such as the number of users, the number of RIS elements, and the fraction of power received through the RIS. Our results demonstrate that RISs can substantially minimize interference allowing multiple user pairs to simultaneously communicate over the same channel and that the proposed approach vastly outperforms the semidefinite relaxation-based approach, which fails to find satisfactory solutions. [ABSTRACT FROM AUTHOR]

Cooperative spectrum sharing (CSS) is a joint spectrum access technique that involves collaboration between primary user (PU) and secondary user (SU) systems. An instance of CSS occurs when the SU transmitter acts as a relay for the PU system. In forwarding the PU signal, the SU transmitter deliberately superimposes the signal intended for the SU receiver. This process unfortunately causes mutual interferences at both PU and SU receivers. Achievable rates for both systems are typically analyzed by assuming Gaussian signals and interferences. Unlike most of previous work, this paper studies the use of practical digital modulation schemes in CSS. The novelty of the proposed CSS approach lies on the smart alignment and superimposition of the SU's pulse amplitude modulated signal to the PU's phase-shift keying signal. It is shown that the SU signal does not interfere with the PU signal, it actually improves the PU signal strength. This paper then focuses on deriving the approximated theoretical transmission rates for both the PU and SU. Interestingly, the analysis shows superior transmission rates for both systems, compared to that achieved by conventional signal superimposition approaches. Simulation results then confirm the matching with the analytical results and validate the performance advantages of the proposed CSS approach. [ABSTRACT FROM AUTHOR]

The 21st century is defined as the era of technological development. With drastic increase in population, automation is becoming the need of the hour in order to make life more comfortable and easy. Due to the advancement and development in the field of automation and embedded system, the notion of smart car has become very popular. Smart cars are modernizing trends in the traditional automobile industry. Companies across the globe have been investing a huge amount of resources on the production and design of smart cars. Every technological development needs to overcome certain obstacles, and hence, in this paper, a design of a collision detection system for smart car using light fidelity (Li-Fi) and ultrasonic sensor on the Arduino platform is proposed. This design consists of an ultrasonic sensor, an Arduino processor, and a Li-Fi circuit. The ultrasonic is used for measurement of distance between vehicles, and Arduino processes the data and makes decisions accordingly. Data transmission between vehicles is ensued using a Li-Fi transmitter circuit and a Li-Fi receiver circuit. The transmitter circuit is mounted on the tail lights of the leading car and the receiver circuit is mounted on the front side of the car that follows. Using visible light communication, the transmitter circuit transmits the calculated speed and the information is received by the receiver circuit of the second car. On the basis of the information received, the speed of the second car is changed in order to avoid collision. In this paper, a system that can detect and thus avoid collision between vehicles and prevent accidents is proposed and studied. [ABSTRACT FROM AUTHOR]

This paper represents the design, feasibility evaluation, and performance validation of ICMR, a novel cross layer protocol that can maximize concurrent transmissions and avoid data frame interference in wireless networks, achieving a higher throughput comparing with the 802.11 standard and other state-of-the-art protocols. Observations on the 802.11 standard reveal that nodes around both the transmitter and receiver of the ongoing link waste concurrent transmission opportunities, degrading the network throughput dramatically. A state-of-the-art protocol IRMA is proposed to improve the network throughput through exploiting concurrent transmissions at the transmitter side. In this paper, a new ICMR protocol focuses on the receiver side to further improve the network throughput, through exploiting discernible interference cancellation, a physical layer mechanism that can successfully detect data frames when collided by control frames. We analyze the concurrent transmission opportunities of one link from the transmitter's transmission opportunities and the receiver's reception opportunities, then formulate the opportunities and give theoretical analysis to indicate that ICMR will have a higher opportunity over other protocols. Feasibility of the discernible interference cancellation mechanism is demonstrated through experiment results based on USRP2, and the throughput improvement of ICMR comparing with the other protocols is confirmed through simulations based on ns-2. [ABSTRACT FROM AUTHOR]

In this paper, we investigate deep learning-aided distributed transmit power control in the context of an underlay cognitive radio network (CRN). In the proposed scheme, the fully distributed transmit power control strategy of secondary users (SUs) is learned by means of a distributed deep neural network (DNN) structure in an unsupervised manner, such that the average spectral efficiency (SE) of the SUs is maximized whilst allowing the interference on primary users (PUs) to be regulated properly. Unlike previous centralized DNN-based strategies that require complete channel state information (CSI) to optimally determine the transmit power of SU transceiver pairs (TPs), in our proposed scheme, each SU TP determines its own transmit power based solely on its local CSI. Our simulation results verify that the proposed scheme can achieve a near-optimal SE comparable with a centralized DNN-based scheme, with a reduced computation time and no signaling overhead. [ABSTRACT FROM AUTHOR]

In this paper, spectrum sharing incentive for legitimate wireless information surveillance at the physical layer is investigated. The concept behind this is that authorized government agencies want to eavesdrop the communication between a suspicious source-destination pair, and stimulate the help of another source-destination pair (referred to as secondary users) looking for transmission opportunities. We thus propose to let the secondary receiver act as a monitor to eavesdrop the suspicious communication and let the secondary transmitter act as a friendly jammer to improve the eavesdropping performance, such that they are granted to share the spectrum of the suspicious users, as a reward. To guarantee the eavesdropping performance, the successful eavesdropping probability is required to be larger than that with passive eavesdropping. The problems of jointly optimizing the transmit power of the secondary transmitter and the successive interference cancellation (SIC) decoding order at the secondary receiver to maximize the average secondary transmission rate and minimize the secondary transmission outage probability are investigated. Two scenarios are considered for the availability of the channel state information (CSI). The first scenario assumes perfect CSI, and the optimal strategies for the transmit power control and the SIC decoding ordering are derived. The second scenario assumes partial CSI, where the instantaneous CSI of the secondary transmission link and the statistical CSI of the links related to the suspicious communication are available, and the optimal strategies for maximizing an approximate average secondary transmission rate and minimizing an approximate secondary transmission outage probability are proposed. Extensive simulation results validate the effectiveness of the proposed strategies. [ABSTRACT FROM AUTHOR]

The cooperative non-orthogonal multiple access (NOMA) networks with one pair primary user and one pair cognitive user share the same spectrum resource via a common relay is considered in this paper. We propose a dynamic power transmission scheme for both uplink and downlink NOMA transmission in cognitive relay networks, which preserves the quality of service for the primary user. The closed-form expressions of overall outage probability and average sum rate for the proposed dynamic power transmission scheme of cognitive relay NOMA networks are derived. Both developed analytical results and Monte Carlo simulations show that the proposed dynamic power control scheme can dramatically enhance performance gain for the proposed networks, compared to other existing NOMA power allocation schemes. [ABSTRACT FROM AUTHOR]

The universal availability of unmanned aerial vehicles (UAVs) has resulted in many applications where the same make/model can be deployed by multiple parties. Thus, identifying a specific UAV in a given swarm, in a manner that cannot be spoofed by software methods, becomes important. We propose RF fingerprinting for this purpose, where a neural network learns subtle imperfections present in the transmitted waveform. For UAVs, the constant hovering motion raises a key challenge, which remains a fundamental problem in previous works on RF fingerprinting: Since the wireless channel changes constantly, the network trained with a previously collected dataset performs poorly on the test data. The main contribution of this paper is to address this problem by: (i) proposing a multi-classifier scheme with a two-step score-based aggregation method, (ii) using RF data augmentation to increase neural network robustness to hovering-induced variations, and (iii) extending the multi-classifier scheme for detecting a new UAV, not seen earlier during training. Importantly, our approach permits RF fingerprinting on manufacturer-proprietary waveforms that cannot be decoded or altered by the end-user. Results reveal a near two-fold accuracy in UAV classification through our multi-classifier method over the single-classifier case, with an overall accuracy of 95% when tested with data under unseen channel. Our multi-classifier scheme also improves new UAV detection accuracy to a near perfect 99%, up from 68% for a single neural network approach. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the covert communications in an overlay cognitive radio (CR) network, where multiple secondary transmitters (STs) opportunistically send confidential information to a secondary receiver (SR). In contrast to current studies with ensuring security of information transmitted, we are motivated to protect communication behavior in CR network, which is considered as a higher-level security. To address covert rate and fairness performance, three joint user-jammer scheduling schemes are proposed, namely, rate-oriented secondary user scheduling (R-SUS), link-oriented secondary user scheduling (L-SUS), and fairness oriented secondary user scheduling (F-SUS). Numerical results show that the minimal detection error probability at eavesdropper (Eve) can be effectively impacted by creating channel uncertainty with the jamming signal. Further, it can be seen that under the same covert constraint, the R-SUS scheme achieves the best covert rate performance, full diversity can be obtained by the L-SUS scheme, while the F-SUS scheme exploits an advantage of better fairness. [ABSTRACT FROM AUTHOR]

In this paper, we propose a practical code scrambling scheme for secure transmissions with channel coding over wiretap channels. We develop explicit scrambling and descrambling matrix generation algorithms that can be performed with a key of limited length for each message transmission. We demonstrate that the proposed scheme avoids the direct inverse operation for large scrambling and descrambling matrices through binary operations. Therefore, without huge complexity loads and feedback overheads being incurred, the scrambling and descrambling matrices at the transmitter and legitimate receiver, respectively, can be simultaneously updated to the new pair through a few binary operations on each side. We also demonstrate that the proposed scheme approaches the perfect scrambling condition for maximizing the decoding error spreading when a sufficiently long independent key with a uniform Bernoulli distribution is provided, where the key length condition in practical applications can be overcome via key accumulation over transmissions. In addition, the proposed scheme also benefits from the descrambling matrix mismatch when the estimation for the key at the eavesdropper is imperfect. Numerical results confirm our analysis and indicate that the proposed scheme significantly improves the secrecy performance of code scrambling in wiretap channels. [ABSTRACT FROM AUTHOR]

The cooperation of radar and communications becomes important in vehicular environments due to the demand for radar-assisted communications or communications-assisted radar. In this paper, the tradeoff between bi-static radar and communications in a joint radar-communications setting is studied. We propose three schemes by using time division, superposition or their mixture. For each scheme, three optimization problems are formulated to maximize either the probability of detection for radar subject to a minimum communications rate, the communications rate subject to a minimum probability of detection for radar, or a combined measure of tradeoff. Specifically, given a fixed amount of total time or power for both communications and radar, the optimal power allocation and/or time allocation between radar and communications are derived. Numerical results show that the superposition scheme outperforms the time division scheme and the mixture scheme with considerable performance gains. They also show that the surveillance channel in radar and the communications channel are more important than the direct channel in radar. [ABSTRACT FROM AUTHOR]

Both caching and interference alignment (IA) are promising techniques for next-generation wireless networks. Nevertheless, most of the existing works on cache-enabled IA wireless networks assume that the channel is invariant, which is unrealistic considering the time-varying nature of practical wireless environments. In this paper, we consider realistic time-varying channels. Specifically, the channel is formulated as a finite-state Markov channel (FSMC). The complexity of the system is very high when we consider realistic FSMC models. Therefore, in this paper, we propose a novel deep reinforcement learning approach, which is an advanced reinforcement learning algorithm that uses a deep $Q$ network to approximate the $Q$ value-action function. We use Google TensorFlow to implement deep reinforcement learning in this paper to obtain the optimal IA user selection policy in cache-enabled opportunistic IA wireless networks. Simulation results are presented to show that the performance of cache-enabled opportunistic IA networks in terms of the network's sum rate and energy efficiency can be significantly improved by using the proposed approach. [ABSTRACT FROM PUBLISHER]

Existing research on a simultaneous wireless information and power transfer (SWIPT) system is based on the assumption of Gaussian inputs. However, the optimal design on Gaussian inputs may lead to dramatic performance loss for practical systems with finite-alphabet inputs. This paper focuses on the precoder design for a SWIPT system with finite-alphabet inputs and instantaneous channel state information over a multiple-input multiple-output channel. We formulate the optimal precoder design as an optimization problem, in which the objective is to maximize the mutual information over the channel from the transmitter to the information receiver under the constraints of transmit power and harvested energy threshold. The formulated problem is NP-hard, so a global optimal solution cannot be found within the polynomial time. The main contributions of this paper are as follows: 1) By using its structure, the NP-hard problem is relaxed to a semidefinite programming problem. Then, a general solving framework for both co-located and separated receiver cases, based on the semidefinite relaxation (SDR) technique, is developed to achieve a near optimal precoder. 2) For the case of co-located receivers, we show that the optimal precoder design is a concave problem with respect to power allocation; then, a specific algorithm for co-located receivers is proposed. Compared with the general SDR-based method, the specific algorithm for co-located receivers exhibits almost the same performance but much lower complexity. 3) The performance of several practical co-located receiver designs is analyzed in SWIPT systems with finite-alphabet inputs. Finally, we provide simulation results to show the efficacy of the proposed algorithms. [ABSTRACT FROM PUBLISHER]

In a frequency division complementary coded CDMA (FD-CC-CDMA) system, multiple tuners have to be used for multi-carrier modulation, which has a very high complexity and power consumption. In this paper, we propose a CP-free OFDM scheme to implement multi-carrier modulation in an FD-CC-CDMA system, which is named as CP-free OFDM-CC-CDMA system. The transmitter in the CP-free OFDM-CC-CDMA system offers a unique flexibility to adjust the amount of data processed at the same time to ensure that the OFDM block size exceeds the delay spread of a multipath channel, which attributes to effective mitigation of multipath induced inter-symbol interference (ISI). At the receiver of a CP-free OFDM-CC-CDMA system, minimum mean square error (MMSE) equalization and MMSE combining are used to mitigate multi-user interference (MUI) and inter-carrier interference (ICI). The obtained results show that a CP-free OFDM-CC-CDMA system offers a much higher transmission efficiency than FD-CC-CDMA and OFDM-DS-CDMA systems. In addition, the proposed CP-free OFDM-CC-CDMA system outperforms OFDM-DS-CDMA system in terms of bit error rate due to its inherent powerful diversity gain. [ABSTRACT FROM AUTHOR]

This paper considers that a transmitter superposes secrecy transmissions to a closer receiver with a high security level in the active MIMO-OFDM channel it is using to send data to a farther receiver with a low security level, by using NOMA techniques. A joint optimization of power allocation and beamforming is important to maximize the secrecy rate to the closer receiver, while keeping the requested data rate of the farther receiver unaffected. The optimization problem is challenging because of coupled variables, and has yet to be addressed. We propose to decouple the problem between subcarrier power allocation and beamforming. Given beamforming, we prove the subcarrier power allocation for the two receivers can be equivalently transformed to two convex problems with waterfilling structures and closed-form solutions. Given power allocation, beamforming can be decoupled between subcarriers by distributing the rate requirement of the farther receiver across the subcarriers. The per-subcarrier beamforming is convexified by applying semidefinite relaxation and the Dinkelbach method. Simulations show the proposed approach can outperform its existing alternatives in terms of secrecy rate, and holistic designs of power allocation and beamforming are critical. [ABSTRACT FROM AUTHOR]

Hardware impairments (HI) always exist in wireless devices, especially the low-cost ones. However, due to the complicated mathematical analysis, previous studies on wireless networks usually neglected the HI, particularly for full-duplex relaying (FDR) systems. In this paper, we consider the impact of the HI on the outage probabilities (OPs) and ergodic capacities (ECs) of both one-way (OW) and two-way (TW) amplify-and-forward (AF) FDR systems. We also take into account the residual self-interference (RSI) due to the imperfect self-interference cancellation (SIC), which appears at the FDR node of the considered HI-OW-AF-FDR system and all nodes of the considered HI-TW-AF-FDR system. Particularly, we derive the exact expressions of the outage probabilities and ergodic capacities for the HI-OW-AF-FDR and HI-TW-AF-FDR systems using mathematical analysis. Numerical results show that the OPs and ECs of the two systems are significantly affected by both HI and RSI, however the impact of the HI is more serious. It is recommended that besides SIC techniques, effective methods to reduce the HI should also be used to guarantee the system performance. [ABSTRACT FROM AUTHOR]

Due to the non-ideality of analog components, transmitters (TXs) and receivers (RXs) suffer from hardware impairments such as in-phase/quadrature (I/Q) imbalance, which manifests itself as the mismatches of amplitude, phase and frequency response between I/Q branches. Without compensation, I/Q imbalance can severely degrade the system performance. This paper addresses the joint compensation of TX and RX I/Q imbalances for single carrier frequency domain equalization (SC-FDE) systems. Specifically, we develop an expectation maximization (EM) based approach to separately estimate TX and RX I/Q imbalances, and the multipath channel. With the obtained estimates, we can readily fulfill the compensation of I/Q imbalances. Unlike previous methods, which only estimate the combined effect of I/Q imbalances and the multipath channel, we are able to obtain the separate estimates of the TX I/Q imbalance, the RX I/Q imbalance and the multipath channel. This will significantly alleviate the computation burden of the proposed compensation scheme in the long run. Simulation results show that the proposed scheme outperforms the counterparts, and can significantly mitigate the adverse effects of I/Q imbalances. [ABSTRACT FROM AUTHOR]

Vehicle to vehicle (V2V) communications using dedicated short-range communications (DSRC) are considered a promising technology for enhancing road safety. However, in V2V communications, passenger cars suffer from obstruction of bigger vehicles such as buses or trucks. Based on our measurement, a big vehicle can cause a signal loss from 10 to 15 dB due to shadowing. This results in a shorter communication range and reduces the safety message dissemination capability. In this paper, we analyze the impact of shadowing caused by multiple big vehicles on the V2V communication of passenger cars. We propose a model that takes into account both geometric and stochastic shadowing of multiple big vehicles. In order to cope with the physical size of vehicles and safety distance between them in the real world, we propose to use a repulsive point process called hardcore repulsive Poisson point process (PPP) to model the locations of vehicles. Generating procedure and some basic properties of this process are introduced. Based on the proposed model, we derive the average length of the shadow region and the shadowing loss caused by multiple big vehicles. We show that when the number of big vehicles increases from 10% to 80% of total vehicles in one lane, the shadow region increases from 50 m to 450 m on the road. Furthermore, the shadowing loss causes the relative number of cars within communication range of a typical car to reduce from 90% to between 15% and 50%, depending on whether the big vehicles are in the same or the adjacent lane of the consider car. We analyse the packet collision probability while taking into consideration the big vehicle shadow region and observe significant packet collisions without dedicated bus lanes. [ABSTRACT FROM AUTHOR]

In cognitive radio enabled vehicular ad-hoc networks (CR-VANETs), the secondary users, i.e., the secondary intelligent vehicles have the ability to perceive the driving environment and use the unoccupied spectrum of primary users for data transmission. In this paper, we consider the radar assisted CR-VANETs, in which the secondary users firstly sense the surroundings using radar modules periodically and Swerling 0, Swerling 2 and Swerling 4 target models are considered respectively. Note that the secondary users access the spectrum of primary users and communicate with their corresponding receivers when no one is detected by the low range radar module. Moreover, we design the joint radar sensing and data transmission frame structure and formulate the radar sensing-throughput tradeoff problem mathematically. It is proved that the formulated tradeoff indeed has the optimal radar sensing time which yields the maximum throughput for the secondary networks. Numerical results and simulations verify that the optimal radar sensing time achieving the maximum throughput for Swerling 0 target model is ${0.05}\; \text{ms}$ when the radius of the radar sensing region is 320 meters, the densities of the primary users and secondary users are $\lambda _p=0.01 / m^2$ and $\lambda _s=0.2 / m^2$ , the received radar SNR is 10 dB and the detection probability is 99.9%. For the Swerling 2 and Swerling 4 target models, the optimal radar sensing times achieving the maximum throughput is ${0.14}\; \text{ms}$ and ${0.08}\; \text{ms}$ respectively when the detection probability is 99%. [ABSTRACT FROM AUTHOR]

Dissemination of cached contents on device-to-device (D2D) links is one promising technique to relieve network load. In this correspondence paper, we extend our Markov chain model (A. Ahmed, H. Shan, and A. Huang, 2019) to analyze the impact of both node mobility and multiple concurrent transmissions in a cluster based mobile caching network. To unearth the impact of the former factor, we derive the steady-state probability of nodes in different clusters under the Markov mobility model. To reveal the impact of the latter factor, the per-node collision-free transmission chance in each active cluster is tunable by building the network with spatial reuse time division multiple access (STDMA) and the receiver based code division multiple access (R-CDMA) codes. Diverse network performance metrics are derived from the analytical framework. Simulation results verify the accuracy of the analysis and examine the impact of system parameters. [ABSTRACT FROM AUTHOR]

Low latency and high reliability are key features of the fifth-generation (5G) machine-type communications. In this paper, we provide a stringently delay-constrained model for multi-user interference channel, and formulate the rate and power allocation problem based on Markov decision process (MDP), which is solved by value iteration algorithm. In particular, to make timely transmission of each packet after being encoded, we characterize the delay constraint on sum of buffering delay and transmission delay. Then, the rate splitting and group decoding are employed at transmitters and receivers, respectively, which can offer significant improvement of achievable rate region. In addition, we also consider the receiving latency and propose novel delay-constrained partial group decoding (DC-CPGD), where all desired messages can be decoded within allowable interference cancellation steps to effectively control this latency. Two rate allocation algorithms are proposed with limited information exchange. Numerical results demonstrate that the proposed DC-CPGD can perform close to exhaustive search, and the proposed MDP-based adaptive transmission combined with DC-CPGD can significantly reduce the transmission cost under stringent delay requirement. [ABSTRACT FROM AUTHOR]

A dual-coupled inductor-capacitor-capacitor and series (LCC-S) compensated wireless power transfer (WPT) system with a compact receiver size is proposed in this paper to improve the misalignment performance and achieve fault tolerant operation as well as a stable output power. The compensation coil and the main coil are integrated as two decoupled unipolar coils on the transmitter side, while they are both coupled with the receiver coil. The two mutual inductances among the two decoupled coils and the receiver coil have opposite impacts on the output power when they both increase or decrease. Therefore, the output power can remain stable when the misalignment increases. The short- and open-circuit characteristics are analyzed, which demonstrates that the proposed topology can achieve both short- and open-circuit protection. A prototype was built and the experimental results verified the theoretical analysis and simulations. The system can deliver from 297 W to 321 W when the x-misalignment increases from 0 mm to 90 mm, with a dc-dc efficiency of 92.78% to 93.56%. The proposed WPT system can be used for the wireless charging of e-mobility scooters and autonomous underwater vehicles. The system can provide a stable output and can tolerate both short- and open-circuit faults at the output. [ABSTRACT FROM AUTHOR]

An autonomous V2V communication mode (also known as side-link mode 4), which facilitates V2V communication in out of eNB coverage areas, has recently been introduced into the Long term evolution (LTE) standard. Recent research has studied the performance of this LTE-V2V autonomous mode for a highway use case. However, performance analysis for a highway use case cannot be easily applied to an intersection use case as it may contain non-line-of-sight (NLOS) communication links. In this paper, we analyze and evaluate the safety message broadcasting performance of LTE-V2V autonomous mode in an urban intersection scenario. Considering practical path loss models, we present the impact of NLOS communication link on the overall message dissemination performance. Through the analytical and simulation results, we show that the overall message dissemination performance degrades drastically with increasing vehicle density and increasing distance of the transmitting vehicle from the intersection. To improve the performance, we propose a vehicle-assisted relaying scheme in which the relaying vehicle is selected in an autonomous manner. We also present two resource allocation strategies for the relaying vehicle. For low to medium vehicle density along the street, we observe significant improvement in message dissemination through relaying compared to the scheme without relaying. [ABSTRACT FROM AUTHOR]

Transceiver hardware impairments (e.g., phase noise, high power amplifier nonlinearities, in-phase/quadrature-phase imbalance, and quantization errors) degrade the performance of channel estimation in millimeter wave (mmWave) multiple-input multiple-output (MIMO) systems. Although compensation methods can be exploited to mitigate the impact of hardware impairments, there always remains residual impairments that will distort the training pilots and received signals. In this paper, we reformulate the channel estimation with transceiver impairments into a sparse recovery problem from a Bayesian perspective and propose an efficient channel estimation algorithm. The proposed algorithm can effectively deal with the perturbation in channel estimation problem caused by the transmitter hardware impairments with small amount computation times. Simulation results demonstrate the superior performance of the proposed algorithm compared to the conventional orthogonal matching pursuit algorithm (OMP) based channel estimation method and Bayesian inference method. [ABSTRACT FROM AUTHOR]

In this paper, we propose an ergodic interference alignment (IA) method for interference elimination in spectrum sharing multiple-input multiple-output (MIMO) radar and multi-user MIMO communication systems. In existing ergodic IA methods, the channel state information (CSI) is generally assumed to be constant, but time-varying channels should be considered in practice. Differently, our proposed ergodic IA allows to time-varying and/or frequency selective channels for spectrum sharing radar-communication systems. The essence is equivalent to design a simple transmit beamforming, which helps to find a pair of desired complementary channels easily without long-time system delay, therefore, the interferences can be effectively cancelled. The proposed method is evaluated by generalized likelihood ratio test (GLRT) and signal to interference plus noise ratio (SINR) for the radar functionality, while the communication functionality is examined by bit error rate (BER) performance. Both theoretical analysis and simulation results validate that the effectiveness of the ergodic IA method for spectrum sharing radar-communication systems. [ABSTRACT FROM AUTHOR]

One of the goals of this paper is to contribute to finding distributed power control strategies, which exploit efficiently the information available about the global channel state; it may be local or noisy. A suited way of measuring the global efficiency of a distributed power control scheme is to use the long-term utility region. First, we provide the utility region characterization for general utility functions when the channel state obeys an independent block fading law and the observation structure is memoryless. Second, the corresponding theorem is exploited to construct an iterative algorithm, which provides one-shot power control strategies. The performance of the proposed algorithm is assessed for energy-efficient and spectrally efficient communications and shown to perform much better than state-of-the-art techniques, with the additional advantage of being applicable even in the presence of arbitrary observation structures such as those corresponding to noisy channel gain estimates. [ABSTRACT FROM AUTHOR]

Terahertz (THz)-band (0.1–10 THz) communication is envisioned as a key wireless technology of the next decade, able to support wireless Terabit-per-second links in 6G systems. THz communication exhibits an extremely large bandwidth (tens to hundreds of GHz) at the cost of a very high path loss ($>$ 100 dB for distances beyond a few meters). Therefore, highly directional antennas (DAs) are needed simultaneously in transmission and reception at all times to establish reliable communication links. The application of highly DAs introduces new challenges in the neighbor discovery process. In this paper, a time-efficient neighbor discovery protocol for THz-band communication networks is proposed. The protocol expedites the neighbor discovery process by leveraging the full antenna radiation pattern to detect a series of effective signals and map them to the universal signal patterns, which indicate the potential direction of the signal source. A mathematical framework is developed to compare the neighbor discovery protocols with and without the antenna side-lobes information in free space. The X60 testbed is utilized to validate the proposed neighbor discovery protocol. Furthermore, a feasibility analysis of the proposed protocol inside a bounded space (e.g., a square room) is conducted. Numerical results are presented to illustrate the performance improvements achieved by the proposed protocol when compared to the traditional neighbor discovery protocols with only main-lobe information. [ABSTRACT FROM AUTHOR]

In traditional orthogonal frequency division multiplexing (OFDM) systems, a cyclic prefix (CP) must be used in every block for intersymbol interference (ISI) suppression in time-dispersive channels at a price of severely impaired spectrum efficiency. To deal with this issue, the symbol cyclic shift equalization (SCSE) algorithm was proposed to implement a CP-free OFDM system. In this paper, we aim to further reduce the computational complexity of the SCSE algorithm. In particular, a pulse amplitude modulation (PAM) is used at a transmitter to construct conjugate symmetric OFDM blocks, while only partial samples in an OFDM block are involved in the SCSE algorithm at the receiver side, leading to a significantly reduced implementation complexity if compared to an SCSE quadratic-amplitude modulation(QAM)/phase-shift keying (PSK)-OFDM system, where all samples in an OFDM block must be involved in the detection process. The performance of the proposed SCSE PAM-OFDM scheme is analyzed and compared to traditional OFDM systems. The results obtained from this paper verify the effectiveness of the proposed scheme. [ABSTRACT FROM PUBLISHER]

In this paper, we propose regularized block diagonalization (RBD) precoding using artificial noise (AN) for physical layer security in downlink multi-user MIMO wireless networks. We derive secrecy sum rate and asymptotic secrecy sum rate for the proposed scheme. The optimum power allocation for legitimate users and the AN signal are derived in closed form for optimal asymptotic secrecy sum rate. Our analysis shows that to achieve best performance, it is more efficient to degrade the performance of the eavesdropper than improving legitimate users’ rates. We also study the impact of error in channel estimation on the system and derive closed-form SINR and secrecy sum-rate expressions for this case. Simulations show that the secrecy sum rate of RBD precoding outperforms the secrecy sum rate of regularized channel inversion by 0.5 bits/s/Hz. We also show that in the presence of channel estimation error, our approximate closed forms for secrecy sum rate are very closed to the actual secrecy sum rate over a wide range of SNR and channel estimation error values. [ABSTRACT FROM AUTHOR]

The advancement of integrated millimeter-wave products opens the possibility of leveraging communications in 60-GHz band to meet the unprecedented traffic demand in WLAN. Despite the vast bandwidth available, millimeter-wave signals suffer from high attenuation and weak diffraction ability. Therefore, wireless communication at 60 GHz is characterized by the inherent directivity and susceptibility to blockage. Multiple Access Point (AP) architecture is proposed for 60-GHz WLAN to enhance spatial reuse and survive blockage. In the presence of multiple APs in the network, this paper addresses the important problem of user-AP association and resource allocation. We study three schemes of different complexity and investigate how to maximize user throughput with joint consideration of AP assignment and transmission scheduling. To solve the formulated problem, we propose a branch-and-cut-based solution procedure. We perform a detailed comparative analysis of the three schemes and advocate to use one-shot AP assignment-based scheduling scheme due to its simplicity and good performance. To deal with real-time traffic and human blockage, we propose an online algorithm to implement the one-shot AP assignment-based scheme to avoid frequent service disruption. Our results show that the proposed online algorithm is competitive when compared with the optimal offline algorithm. [ABSTRACT FROM AUTHOR]

In this paper, two carrier index differential chaos shift keying (CI-DCSK) with simultaneous wireless information and power transfer schemes, which integrate CI-DCSK modulation with wireless power transfer, are proposed. In the proposed schemes, based on the transmission characteristics of index modulation, the inactive carriers of CI-DCSK are exploited to deliver energy by transmitting random noise-like signals subjected to normal distribution. By applying time switching (TS) at the receiver, each frame time of the proposed schemes is divided into two intervals. Unlike usual TS-based systems, two intervals of the proposed schemes are related, where energy harvesting and decoding of the modulated bits are both operated in the second interval. Analytical bit error rate (BER) expressions over additive white Gaussian noise and multipath Rayleigh fading channels of the two schemes are derived. The expression for the parameter $\xi$ is also derived that measures the probability of self-sufficiency of these schemes. The impact of the dividing point of two intervals on BER performance of systems is also analyzed and optimized. Since the energy on the inactive carriers is adjustable, the schemes are always self-sustainable in energy supply. To provide the best performance, the ratio of energy on the inactive carriers to that on the active carriers is optimized. Simulation results show that though performances of the proposed schemes are a little worse than CI-DCSK with the same spectral efficiency, the proposed schemes are all self-sustainable. [ABSTRACT FROM AUTHOR]

This paper considers a new wireless information surveillance scenario, where a legitimate monitor tries to eavesdrop on the suspicious messages sent by an unmanned aerial vehicle aided suspicious transmitter. By using the characteristic of the suspicious system, we propose an effective proactive jamming scheme to maximize the achievable eavesdropping rate. A successive convex approximation based iterative algorithm is first developed to solve the original non-convex optimization problem. Based on this result, the eavesdropping rate maximization problem is then solved by applying the one-dimensional search method. Moreover, we also study the special case of two suspicious receivers for gaining more useful insights on designing the optimal jamming transmission strategy. Numerical results show that the proposed proactive jamming approach can significantly enhance the achievable eavesdropping rate compared to the reference scheme. [ABSTRACT FROM AUTHOR]