- Electronic Engineering and Computer Science
Queen Mary University of London
Mile End Road, London E1 4NS, UK - +44 (0) 20 7882 5813
- Yuanwei Liu is a Lecturer (Assistant Professor) in School of Electronic Engineering and Computer Science at Queen Ma... moreYuanwei Liu is a Lecturer (Assistant Professor) in School of Electronic Engineering and Computer Science at Queen Mary University of London (QMUL) , London, U.K. (Sep. 2017-present). He was a Postdoctoral Research Fellow at King's College London (KCL) , London, U.K. (Sep. 2016- Aug. 2017). He received the Ph.D. degree from QMUL in 2016. He received the M.S. and B.S. degrees from Beijing University of Posts and Telecommunications (BUPT) in 2014 and 2011, respectively. He currently serves as an Editor of the IEEE Communications Letters and the IEEE Access.
His research interests include Non-Orthogonal Multiple access (NOMA), Millimeter Wave Communications, Internet of Things (IoT), Resource Allocation in 5G networks, Stochastic Geometry and Matching Theory, Machine Learning and Big Data.edit
This paper investigates the physical layer security of non-orthogonal multiple access (NOMA) in large-scale networks with invoking stochastic geometry. Both single-antenna and multiple-antenna aided transmission scenarios are considered,... more
This paper investigates the physical layer security of non-orthogonal multiple access (NOMA) in large-scale networks with invoking stochastic geometry. Both single-antenna and multiple-antenna aided transmission scenarios are considered, where the base station (BS) communicates with randomly distributed NOMA users. In the single-antenna scenario, we adopt a protected zone around the BS to establish an eavesdropper-exclusion area with the aid of careful channel-ordering of the NOMA users. In the multiple-antenna scenario, artificial noise is generated at the BS for further improving the security of a beamforming-aided system. In order to characterize the secrecy performance, we derive new exact expressions of the security outage probability for both single-antenna and multiple-antenna aided scenarios. To obtain further insights, 1) for the single antenna scenario, we perform secrecy diversity order analysis of the selected user pair. The analytical results derived demonstrate that the secrecy diversity order is determined by the specific user having the worse channel condition among the selected user pair; and 2) for the multiple-antenna scenario, we derive the asymptotic secrecy outage probability, when the number of transmit antennas tends to infinity. Monte Carlo simulations are provided for verifying the analytical results derived and to show that: i) The security performance of the NOMA networks can be improved by invoking the protected zone and by generating artificial noise at the BS; and ii) The asymptotic secrecy outage probability is close to the exact secrecy outage probability.
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In this letter, we investigate the context-aware resource allocation for device-to-device communications accounting for the quality-of-service (QoS) requirements and priorities of different applications based on users' requests. We... more
In this letter, we investigate the context-aware resource allocation for device-to-device communications accounting for the quality-of-service (QoS) requirements and priorities of different applications based on users' requests. We formulate a context-aware optimization problem and implement the matching theory to solve the problem. We propose a novel algorithm where the D2D user equipments and resource blocks (RBs) act as two opposite sets of players and interact with each other to obtain the optimal matching. We analytically prove that the algorithm converges to a two-sided exchange stability within limited number of swap operations. We also demonstrate that the proposed algorithm significantly outperforms the context-unaware resource allocation algorithm by around 62.2%.
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In this letter, we aim at solving the resource allocation problem for device-to-device (D2D) communications underlaying cellular networks. Particularly, multiple D2D pairs are allowed to reuse the same resource block (RB), and one D2D... more
In this letter, we aim at solving the resource allocation problem for device-to-device (D2D) communications underlaying cellular networks. Particularly, multiple D2D pairs are allowed to reuse the same resource block (RB), and one D2D pair is allowed to use the spectrum of multiple RBs. Our objective is to maximize the system sum rate by satisfying the signal-to-interference-plus-noise ratio (SINR) constraints for both D2D and cellular user equipments (UEs). In order to solve this non-deterministic polynomial-time (NP) hard optimization problem, we propose a novel algorithm for obtaining a sub-optimal solution based on the many-to-many two-sided matching game with externalities. To characterize the properties of the proposed algorithm, we prove that it converges to the two-sided exchange stability within limited number of iterations. Additionally, simulation results show that the proposed algorithm can achieve the near-optimal system sum rate and significantly outperforms a one-to-one matching algorithm.
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In this paper, a novel resource allocation design is investigated for non-orthogonal multiple access (NOMA) enhanced heterogeneous networks (HetNets), where small cell base stations (SBSs) are capable of communicating with multiple small... more
In this paper, a novel resource allocation design is investigated for non-orthogonal multiple access (NOMA) enhanced heterogeneous networks (HetNets), where small cell base stations (SBSs) are capable of communicating with multiple small cell users (SCUs) via the NOMA protocol. With the aim of maximizing the sum rate of SCUs while taking the fairness issue into consideration, a joint problem of spectrum allocation and power control is formulated. Particularly, the spectrum allocation problem is modeled as a many-to-one matching game with peer effects. We propose a novel algorithm where the SBSs and resource blocks (RBs) interact to decide their desired allocation. More importantly, we introduce the concept of 'experimentation' into the matching game for further improving the SCUs' sum rate. The proposed algorithm is proved to converge to a two-sided exchange-stable matching. The power control of each SBS is formulated as a non-convex problem, where the sequential convex programming is adopted to iteratively update the power allocation result by solving the approximate convex problem. The obtained solution is proved to satisfy the Karush-Kuhn-Tucker (KKT) conditions. We unveil that: 1) The proposed algorithm closely approaches the optimal solution within a limited number of iterations; 2) The 'experimentation' action is capable of further enhancing the performance of the matching algorithm; and 3) The developed NOMA-enhanced HetNets achieve a higher SCUs' sum rate compared to the conventional OMA-based HetNets.
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—This paper investigates the performance of millimeter wave (mmWave) communications in clustered device-to-device (D2D) networks. The locations of D2D transceivers are modeled as a Poisson Cluster Process (PCP). In each cluster, devices... more
—This paper investigates the performance of millimeter wave (mmWave) communications in clustered device-to-device (D2D) networks. The locations of D2D transceivers are modeled as a Poisson Cluster Process (PCP). In each cluster, devices are equiped with multiple antennas, and the active D2D receiver (D2D-Rx) utilizes mmWave to communicate with one of proximate D2D transmitters (D2D-Txs). We introduce three serving D2D-Tx selection scenarios: 1) uniformly distributed D2D-Tx model; 2) nearest D2D-Tx model; 3) closest line-of-site (LOS) D2D-Tx model. To characterize the performance of the considered scenarios, we derive new analytical expressions for the coverage probability and area spectral efficiency (ASE). In addition, for the sake of efficiently illustrating the general trends of our system, a closed-form lower bound for the special case with intra-cluster interferences is derived. We provide Monte Carlo simulations to corroborate the theoretical results and show that: 1) The coverage probability is mainly affected by the intra-interference with LOS links; 2) There exists an optimum number of simultaneously active D2D-Txs in each cluster for maximizing ASE; and 3) Closest LOS model outperforms the other two scenarios but at the cost of extra system overhead.
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In this paper, a novel non-orthogonal multiple access (NOMA) enhanced device-to-device (D2D) communication scheme is considered. Our objective is to maximize the system sum rate by optimizing subchannel and power allocation. We propose a... more
In this paper, a novel non-orthogonal multiple access (NOMA) enhanced device-to-device (D2D) communication scheme is considered. Our objective is to maximize the system sum rate by optimizing subchannel and power allocation. We propose a novel solution that jointly assigns subchannels to D2D groups and allocates power to receivers in each D2D group. For the subchannel assignment, a novel algorithm based on the many-to-one two-sided matching theory is proposed for obtaining a suboptimal solution. Since the power allocation problem is non-convex, sequential convex programming is adopted to transform the original power allocation problem to a convex one. The power allocation vector is obtained by iteratively tightening the lower bound of the original power allocation problem until convergence. Numerical results illustrate that: i) the proposed joint subchannel and power allocation algorithm is an effective approach for obtaining near-optimal performance with acceptable complexity; and ii) the NOMA enhanced D2D communication scheme is capable of achieving promising gains in terms of network sum rate and number of accessed users, compared to traditional orthogonal multiple access (OMA) based D2D communication scheme.
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In this paper, a novel cooperative non-orthogonal multiple access (NOMA) system is proposed, where one near user is employed as decode-and-forward (DF) relaying switching between full-duplex (FD) and half-duplex (HD) mode to help a far... more
In this paper, a novel cooperative non-orthogonal multiple access (NOMA) system is proposed, where one near user is employed as decode-and-forward (DF) relaying switching between full-duplex (FD) and half-duplex (HD) mode to help a far user. Two representative cooperative relaying scenarios are investigated insightfully. The first scenario is that no direct link exists between the base station (BS) and far user. The second scenario is that the direct link exists between the BS and far user. To characterize the performance of potential gains brought by FD NOMA in two considered scenarios, three performance metrics outage probability, ergodic rate and energy efficiency are discussed. More particularly, we derive new closed-form expressions for both exact and asymptotic outage probabilities as well as delay-limited throughput for two NOMA users. Based on the derived results, the diversity orders achieved by users are obtained. We confirm that the use of direct link overcomes zero diversity order of far NOMA user inherent to FD relaying. Additionally, we derive new closed-form expressions for asymptotic ergodic rates. Based on these, the high signal-to-noise radio (SNR) slopes of two users for FD NOMA are obtained. Simulation results demonstrate that: 1) FD NOMA is superior to HD NOMA in terms of outage probability and ergodic sum rate in the low SNR region; and 2) In delay-limited transmission mode, FD NOMA has higher energy efficiency than HD NOMA in the low SNR region; However, in delay-tolerant transmission mode, the system energy efficiency of HD NOMA exceeds FD NOMA in the high SNR region.
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This paper investigates the application of non-orthogonal multiple access (NOMA) in millimeter wave (mmWave) communications by exploiting beamforming, user scheduling and power allocation. Random beamforming is invoked for reducing the... more
This paper investigates the application of non-orthogonal multiple access (NOMA) in millimeter wave (mmWave) communications by exploiting beamforming, user scheduling and power allocation. Random beamforming is invoked for reducing the feedback overhead of considered systems. A non-convex optimization problem for maximizing the sum rate is formulated, which is proved to be NP-hard. The branch and bound (BB) approach is invoked to obtain the ϵ-optimal power allocation policy, which is proved to converge to a global optimal solution. To elaborate further, a low complexity suboptimal approach is developed for striking a good computational complexity-optimality tradeoff, where matching theory and successive convex approximation (SCA) techniques are invoked for tackling the user scheduling and power allocation problems, respectively. Simulation results reveal that: i) the proposed low complexity solution achieves a near-optimal performance; and ii) the proposed mmWave NOMA systems is capable of outperforming conventional mmWave orthogonal multiple access (OMA) systems in terms of sum rate and the number of served users.
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In this paper, the potential benefits of applying non-orthogonal multiple access (NOMA) technique in K-tier hybrid heterogeneous networks (HetNets) is explored. A promising new transmission framework is proposed, in which NOMA is adopted... more
In this paper, the potential benefits of applying non-orthogonal multiple access (NOMA) technique in K-tier hybrid heterogeneous networks (HetNets) is explored. A promising new transmission framework is proposed, in which NOMA is adopted in small cells and massive multiple-input multiple-output (MIMO) is employed in macro cells. For maximizing the biased average received power for mobile users, a NOMA and massive MIMO based user association scheme is developed. To evaluate the performance of the proposed framework, we first derive the analytical expressions for the coverage probability of NOMA enhanced small cells. We then examine the spectrum efficiency of the whole network, by deriving exact analytical expressions for NOMA enhanced small cells and a tractable lower bound for massive MIMO enabled macro cells. Lastly, we investigate the energy efficiency of the hybrid HetNets. Our results demonstrate that: 1) The coverage probability of NOMA enhanced small cells is affected to a large extent by the targeted transmit rates and power sharing coefficients of two NOMA users; 2) Massive MIMO enabled macro cells are capable of significantly enhancing the spectrum efficiency by increasing the number of antennas; 3) The energy efficiency of the whole network can be greatly improved by densely deploying NOMA enhanced small cell base stations (BSs); and 4) The proposed NOMA enhanced HetNets transmission scheme has superior performance compared to the orthogonal multiple access (OMA) based HetNets.
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—Driven by the rapid escalation of the wireless capacity requirements imposed by advanced multimedia applications (e.g., ultra-high-definition video, virtual reality etc.), as well as the dramatically increasing demand for user access... more
—Driven by the rapid escalation of the wireless capacity requirements imposed by advanced multimedia applications (e.g., ultra-high-definition video, virtual reality etc.), as well as the dramatically increasing demand for user access required for the Internet of Things (IoT), the fifth generation (5G) networks face challenges in terms of supporting large-scale heterogeneous data traffic. Non-orthogonal multiple access (NOMA), which has been recently proposed for the 3rd generation partnership projects long-term evolution advanced (3GPP-LTE-A), constitutes a promising technology of addressing the above-mentioned challenges in 5G networks by accommodating several users within the same orthogonal resource block. By doing so, significant bandwidth efficiency enhancement can be attained over conventional orthogonal multiple access (OMA) techniques. This motivated numerous researchers to dedicate substantial research contributions to this field. In this context, we provide a comprehensive overview of the state-of-the-art in power-domain multiplexing aided NOMA, with a focus on the theoretical NOMA principles, multiple antenna aided NOMA design, on the interplay between NOMA and cooperative transmission, on the resource control of NOMA, on the coexistence of NOMA with other emerging potential 5G techniques and on the comparison with other NOMA variants. We highlight the main advantages of power-domain multiplexing NOMA compared to other existing NOMA techniques. We summarize the challenges of existing research contributions of NOMA and provide potential solutions. Finally, we offer some design guidelines for NOMA systems and identify promising research opportunities for the future.
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In this paper, a downlink multiple-input-multiple-output (MIMO) non-orthogonal multiple access (NOMA) scenario is considered. We investigate a dynamic user clustering problem from a fairness perspective. In order to solve this... more
In this paper, a downlink multiple-input-multiple-output (MIMO) non-orthogonal multiple access (NOMA) scenario is considered. We investigate a dynamic user clustering problem from a fairness perspective. In order to solve this optimization problem, three sub-optimal algorithms, namely top-down A, top-down B, and bottom up, are proposed to realize different tradeoffs of complexity and throughput of the worst user. In addition, for each given user clustering case, we optimize the power allocation coefficients for the users in each cluster by adopting a bisection search based algorithm. Numerical results show that the proposed algorithms can lower the complexity with an acceptable degradation on throughput compared with the exhaustive search method. It is worth noting that top-down B algorithm can achieve a good tradeoff between complexity and throughput among the three proposed algorithms.
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In this paper, non-orthogonal multiple access (NOMA) is applied to large-scale underlay cognitive radio (CR) networks with randomly deployed users. In order to characterize the performance of the considered network, new closed-form... more
In this paper, non-orthogonal multiple access (NOMA) is applied to large-scale underlay cognitive radio (CR) networks with randomly deployed users. In order to characterize the performance of the considered network, new closed-form expressions of the outage probability are derived using stochastic-geometry. More importantly, by carrying out the diversity analysis, new insights are obtained under the two scenarios with different power constraints: 1) fixed transmit power of the primary transmitters (PTs), and 2) transmit power of the PTs being proportional to that of the secondary base station. For the first scenario, a diversity order of m is experienced at the m-th ordered NOMA user. For the second scenario, there is an asymptotic error floor for the outage probability. Simulation results are provided to verify the accuracy of the derived results. A pivotal conclusion is reached that by carefully designing target data rates and power allocation coefficients of users, NOMA can outperform conventional orthogonal multiple access in underlay CR networks.
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This paper exploits an amplify-and-forward (AF) two-way relaying network (TWRN), where an energy constrained relay node harvests energy with wireless power transfer. Two bidirectional protocols, multiple access broadcast (MABC) protocol... more
This paper exploits an amplify-and-forward (AF) two-way relaying network (TWRN), where an energy constrained relay node harvests energy with wireless power transfer. Two bidirectional protocols, multiple access broadcast (MABC) protocol and time division broadcast (TDBC) protocol, are considered. Three wireless power transfer policies, namely, dual-source (DS) power transfer; single-fixed-source (SFS) power transfer; and single-best-source (SBS) power transfer are proposed and well-designed based on time switching receiver architecture. We derive analytical expressions to determine the throughput both for delay-limited transmission and delay-tolerant transmission. Numerical results corroborate our analysis and show that MABC protocol achieves a higher throughput than TDBC protocol. An important observation is that SBS policy offers a good tradeoff between throughput and power.
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This letter proposes several relay selection policies for secure communication in cognitive decode-and-forward relay networks, where a pair of cognitive relays is opportunistically selected for security protection against eavesdropping.... more
This letter proposes several relay selection policies for secure communication in cognitive decode-and-forward relay networks, where a pair of cognitive relays is opportunistically selected for security protection against eavesdropping. The first relay transmits the secrecy information to the destination, and the second relay, as a friendly jammer, transmits the jamming signal to confound the eavesdropper. We present new exact closed-form expressions for the secrecy outage probability. Our analysis and simulation results strongly support our conclusion that the proposed relay selection policies can enhance the performance of secure cognitive radio. We also confirm that the error floor phenomenon is created in the absence of jamming.
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Wireless energy harvesting is regarded as a promising energy supply alternative for energy-constrained wireless networks. In this paper, a new wireless energy harvesting protocol is proposed for an underlay cognitive relay network with... more
Wireless energy harvesting is regarded as a promising energy supply alternative for energy-constrained wireless networks. In this paper, a new wireless energy harvesting protocol is proposed for an underlay cognitive relay network with multiple primary user (PU) transceivers. In this protocol, the secondary nodes can harvest energy from the primary network (PN) while sharing the licensed spectrum of the PN. In order to assess the impact of different system parameters on the proposed network, we first derive an exact expression for the outage probability for the secondary network (SN) subject to three important power constraints: 1) the maximum transmit power at the secondary source (SS) and at the secondary relay (SR), 2) the peak interference power permitted at each PU receiver, and 3) the interference power from each PU transmitter to the SR and to the secondary destination (SD). To obtain practical design insights into the impact of different parameters on successful data transmission of the SN, we derive throughput expressions for both the delay-sensitive and the delay-tolerant transmission modes. We also derive asymptotic closed-form expressions for the outage probability and the delay-sensitive throughput and an asymptotic analytical expression for the delay-tolerant throughput as the number of PU transceivers goes to infinity. The results show that the outage probability improves when PU transmitters are located near SS and sufficiently far from SR and SD. Our results also show that when the number of PU transmitters is large, the detrimental effect of interference from PU transmitters outweighs the benefits of energy harvested from the PU transmitters.
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As the latest member of the multiple access family, non-orthogonal multiple access (NOMA) has been recently proposed for 3GPP Long Term Evolution (LTE) and envisioned to be an essential component of 5th generation (5G) mobile networks.... more
As the latest member of the multiple access family, non-orthogonal multiple access (NOMA) has been recently proposed for 3GPP Long Term Evolution (LTE) and envisioned to be an essential component of 5th generation (5G) mobile networks. The key feature of NOMA is to serve multiple users at the same time/frequency/code, but with different power levels, which yields a significant spectral efficiency gain over conventional orthogonal MA. This article provides a systematic treatment of this newly emerging technology, from its combination with multiple-input multiple-output (MIMO) technologies, to cooperative NOMA, as well as the interplay between NOMA and cognitive radio. This article also reviews the state of the art in the standardization activities concerning the implementation of NOMA in LTE and 5G networks.
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In this paper, we consider a cognitive radio (CR) network in which energy constrained secondary users (SUs) can harvest energy from the randomly deployed power beacons (PBs). A new frame structure which includes four time slots, namely,... more
In this paper, we consider a cognitive radio (CR) network in which energy constrained secondary users (SUs) can harvest energy from the randomly deployed power beacons (PBs). A new frame structure which includes four time slots,
namely, energy harvesting, spectrum sensing, energy harvesting and data transmission is proposed. In the energy harvesting slot, a new wireless power transfer (WPT) scheme in a bounded power transfer model is proposed to enable power SUs wirelessly.
Closed-form expressions for the power outage probability of the proposed WPT scheme are derived. In the spectrum sensing slot, we propose to utilize the compressive sensing (CS) technique
which enables sub-Nyquist sampling to further reduce the energy consumption at SUs. Throughput of the secondary network with the proposed frame structure is formulated into a nonlinear constraint problem. Three methods are provided to obtain the maximal throughput of secondary network by optimizing the time slots allocation and the transmit power.
namely, energy harvesting, spectrum sensing, energy harvesting and data transmission is proposed. In the energy harvesting slot, a new wireless power transfer (WPT) scheme in a bounded power transfer model is proposed to enable power SUs wirelessly.
Closed-form expressions for the power outage probability of the proposed WPT scheme are derived. In the spectrum sensing slot, we propose to utilize the compressive sensing (CS) technique
which enables sub-Nyquist sampling to further reduce the energy consumption at SUs. Throughput of the secondary network with the proposed frame structure is formulated into a nonlinear constraint problem. Three methods are provided to obtain the maximal throughput of secondary network by optimizing the time slots allocation and the transmit power.
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In this paper, the application of simultaneous wireless information and power transfer (SWIPT) to non-orthogonal multiple access (NOMA) networks in which users are spatially randomly located is investigated. A new cooperative SWIPT NOMA... more
In this paper, the application of simultaneous wireless information and power transfer (SWIPT) to non-orthogonal multiple access (NOMA) networks in which users are spatially randomly located is investigated. A new cooperative SWIPT NOMA protocol is proposed, in which near NOMA users that are close to the source act as energy harvesting relays to help far NOMA users. Since the locations of users have a significant impact on the performance, three user selection schemes based on the user distances from the base station are proposed. To characterize the performance of the proposed selection schemes, closed-form expressions for the outage probability and system throughput are derived. These analytical results demonstrate that the use of SWIPT will not jeopardize the diversity gain compared to the conventional NOMA. The proposed results confirm that the opportunistic use of node locations for user selection can achieve low outage probability and deliver superior throughput
in comparison to the random selection scheme.
in comparison to the random selection scheme.
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—In this paper, we investigate secure device-to-device (D2D) communication in energy harvesting large-scale cognitive cellular networks. The energy constrained D2D transmitter harvests energy from multi-antenna equipped power beacons... more
—In this paper, we investigate secure device-to-device
(D2D) communication in energy harvesting large-scale cognitive
cellular networks. The energy constrained D2D transmitter
harvests energy from multi-antenna equipped power beacons
(PBs), and communicates with the corresponding receiver using
the spectrum of the primary base stations (BSs). We introduce a
power transfer model and an information signal model to enable
wireless energy harvesting and secure information transmission.
In the power transfer model, three wireless power transfer
(WPT) policies are proposed: 1) cooperative power beacons
(CPB) power transfer, 2) best power beacon (BPB) power
transfer, and 3) nearest power beacon (NPB) power transfer.
To characterize the power transfer reliability of the proposed
three policies, we derive new expressions for the exact power
outage probability. Moreover, the analysis of the power outage
probability is extended to the case when PBs are equipped
with large antenna arrays. In the information signal model, we
present a new comparative framework with two receiver selection
schemes: 1) best receiver selection (BRS), where the receiver
with the strongest channel is selected, and 2) nearest receiver
selection (NRS), where the nearest receiver is selected. To assess
the secrecy performance, we derive new analytical expressions
for the secrecy outage probability and the secrecy throughput
considering the two receiver selection schemes using the proposed
WPT policies. We presented Monte-carlo simulation results to
corroborate our analysis and show: 1) secrecy performance
improves with increasing densities of PBs and D2D receivers
due to larger multiuser diversity gain, 2) CPB achieves better
secrecy performance than BPB and NPB but consumes more
power, and 3) BRS achieves better secrecy performance than
NRS but demands more instantaneous feedback and overhead.
A pivotal conclusion is reached that with increasing number of
antennas at PBs, NPB offers a comparable secrecy performance
to that of BPB but with a lower complexity.
(D2D) communication in energy harvesting large-scale cognitive
cellular networks. The energy constrained D2D transmitter
harvests energy from multi-antenna equipped power beacons
(PBs), and communicates with the corresponding receiver using
the spectrum of the primary base stations (BSs). We introduce a
power transfer model and an information signal model to enable
wireless energy harvesting and secure information transmission.
In the power transfer model, three wireless power transfer
(WPT) policies are proposed: 1) cooperative power beacons
(CPB) power transfer, 2) best power beacon (BPB) power
transfer, and 3) nearest power beacon (NPB) power transfer.
To characterize the power transfer reliability of the proposed
three policies, we derive new expressions for the exact power
outage probability. Moreover, the analysis of the power outage
probability is extended to the case when PBs are equipped
with large antenna arrays. In the information signal model, we
present a new comparative framework with two receiver selection
schemes: 1) best receiver selection (BRS), where the receiver
with the strongest channel is selected, and 2) nearest receiver
selection (NRS), where the nearest receiver is selected. To assess
the secrecy performance, we derive new analytical expressions
for the secrecy outage probability and the secrecy throughput
considering the two receiver selection schemes using the proposed
WPT policies. We presented Monte-carlo simulation results to
corroborate our analysis and show: 1) secrecy performance
improves with increasing densities of PBs and D2D receivers
due to larger multiuser diversity gain, 2) CPB achieves better
secrecy performance than BPB and NPB but consumes more
power, and 3) BRS achieves better secrecy performance than
NRS but demands more instantaneous feedback and overhead.
A pivotal conclusion is reached that with increasing number of
antennas at PBs, NPB offers a comparable secrecy performance
to that of BPB but with a lower complexity.
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A full tutorial version for our paper published in Proceedings of the IEEE.
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An interesting demonstration for this paper.