Arumugam Nallanathan
King's College London, Informatics, Faculty Member
- Arumugam Nallanathan is a Professor of Wireless Communications in the Department of Informatics at King's College Lon... moreArumugam Nallanathan is a Professor of Wireless Communications in the Department of Informatics at King's College London (University of London). He served as the Head of Graduate Studies in the Faculty of Natural and Mathematical Sciences at King's College London, 2011/12. He was an Assistant Professor in the Department of Electrical and Computer Engineering, National University of Singapore from August 2000 to December 2007. His research interests include Massive-MIMO, Millimeter-wave communications, Energy Harvesting, Small Cell Networks, Cognitive Radio and Relay Networks. He published more than 250 Journal and Conference papers with 3800+ citations and H-index of 31. He is a co-recipient of the Best Paper Award presented at the 2007 IEEE International Conference on Ultra-Wideband (ICUWB’2007). He is an IEEE Distinguished Lecturer.
He is an Editor for IEEE Transactions on Communications and IEEE Transactions on Vehicular Technology and a Guest Editor for IEEE Transactions on Emerging Topics in Computing: Special Issue on Advances in Mobile and Cloud Computing. He was an Editor for IEEE Transactions on Wireless Communications (2006-2011), IEEE Wireless Communications Letters and IEEE Signal Processing Letters. He served as the Chair for the Signal Processing and Communication Electronics Technical Committee of IEEE Communications Society,Technical Program Co-Chair (MAC track) for IEEE WCNC 2014, Co-Chair for the IEEE GLOBECOM 2013 (Communications Theory Symposium), Co-Chair for the IEEE ICC 2012 (Signal Processing for Communications Symposium), Co-Chair for the IEEE GLOBECOM 2011 (Signal Processing for Communications Symposium), Technical Program Co-Chair for the IEEE International Conference on UWB 2011 (IEEE ICUWB 2011), Co-Chair for the IEEE ICC 2009 (Wireless Communications Symposium), Co-chair for the IEEE GLOBECOM 2008 (Signal Processing for Communications Symposium) and General Track Chair for IEEE VTC 2008. He received the IEEE Communications Society Signal Processing and Communications Electronics (SPCE) outstanding service award 2012 and IEEE Communications Society RCC Outstanding Service Award 2014. He is a Senior Member of the IEEE.edit
—We evaluate and quantify the joint effect of fading and multiple interferers on the physical-layer (PHY) security of a system consisted of a base-station (BS), a legitimate user, and an eavesdropper. To this end, we present a novel... more
—We evaluate and quantify the joint effect of fading and multiple interferers on the physical-layer (PHY) security of a system consisted of a base-station (BS), a legitimate user, and an eavesdropper. To this end, we present a novel closed-form expression for the secrecy outage probability, which takes into account the fading characteristics of the wireless environment, the location and the number of interferers, as well as the transmission power of the BS and the interference. The results reveal that the impact of interference should be seriously taken into account in the design and deployment of a wireless system with PHY security.
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Cognitive radio has emerged as one of the most promising candidate solutions to improve spectrum utilization in next generation cellular networks. A crucial requirement for future cognitive radio networks is wideband spectrum sensing:... more
Cognitive radio has emerged as one of the most promising candidate solutions to improve spectrum utilization in next generation cellular networks. A crucial requirement for future cognitive radio networks is wideband spectrum sensing: secondary users reliably detect spectral opportunities across a wide frequency range. In this article, various wideband spectrum sensing algorithms are presented, together with a discussion of the pros and cons of each algorithm and the challenging issues. Special attention is paid to the use of sub-Nyquist techniques, including compressive sensing and multi-channel sub-Nyquist sampling techniques.
—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, 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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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, 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 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 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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Research Interests: Engineering, Technology, Antennas, Signal Processing, Routing protocols, and 20 moreModulation, Beamforming, Antenna arrays, Numerical Simulation, Antenna, Feedback, Outage Probability, Bit Error Rate, Amplify and Forward, Resource Management, Rayleigh fading channel, Power allocation, Antena, Antenna Array, Vehicular, Gain, Signal to Noise Ratio, Relay Network, Law on credit transactions, and Fading channels
This paper exploits the potential of physical layer security in massive multiple-input multiple-output (MIMO) aided two-tier heterogeneous networks (HetNets). We focus on the downlink secure transmission in the presence of multiple... more
This paper exploits the potential of physical layer security in massive multiple-input multiple-output (MIMO) aided
two-tier heterogeneous networks (HetNets). We focus on the
downlink secure transmission in the presence of multiple eavesdroppers.
We first address the impact of massive MIMO on the
maximum receive power based user association. We then derive the tractable upper bound expressions for the secrecy outage probability of a HetNets user.We show that the implementation of massive MIMO significantly improves the secrecy performance, which indicates that physical layer security could be a promising solution for safeguarding massive MIMO HetNets. Furthermore, we show that the secrecy outage probability of HetNets user first degrades and then improves with increasing the density of PBSs.
two-tier heterogeneous networks (HetNets). We focus on the
downlink secure transmission in the presence of multiple eavesdroppers.
We first address the impact of massive MIMO on the
maximum receive power based user association. We then derive the tractable upper bound expressions for the secrecy outage probability of a HetNets user.We show that the implementation of massive MIMO significantly improves the secrecy performance, which indicates that physical layer security could be a promising solution for safeguarding massive MIMO HetNets. Furthermore, we show that the secrecy outage probability of HetNets user first degrades and then improves with increasing the density of PBSs.
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This paper develops a tractable framework for exploiting the potential benefits of physical layer security in three-tier wireless sensor networks using stochastic geometry. In such networks, the sensing data from the remote sensors are... more
This paper develops a tractable framework for exploiting the potential benefits of physical layer security in three-tier wireless sensor networks using stochastic geometry. In such networks, the sensing data from the remote sensors are collected by sinks with the help of access points, and the external eavesdroppers intercept the data transmissions.We focus on the secure transmission in two scenarios: i) the active sensors transmit their sensing data to the access points, and ii) the active access points forward the data to the sinks. We derive new compact expressions for the average secrecy rate in these two scenarios. We also derive a new compact expression for the overall average secrecy rate. Numerical results corroborate our analysis and show that multiple antennas at the access points
can enhance the security of three-tier wireless sensor networks.
Our results show that increasing the number of access points
decreases the average secrecy rate between the access point and its associated sink. However, we find that increasing the number of access points first increases the overall average secrecy rate, with a critical value beyond which the overall average secrecy rate then decreases. When increasing the number of active sensors, both the average secrecy rate between the sensor and its associated access point and the overall average secrecy rate decrease. In contrast, increasing the number of sinks improves both the average secrecy rate between the access point and its associated sink, as well as the overall average secrecy rate.
can enhance the security of three-tier wireless sensor networks.
Our results show that increasing the number of access points
decreases the average secrecy rate between the access point and its associated sink. However, we find that increasing the number of access points first increases the overall average secrecy rate, with a critical value beyond which the overall average secrecy rate then decreases. When increasing the number of active sensors, both the average secrecy rate between the sensor and its associated access point and the overall average secrecy rate decrease. In contrast, increasing the number of sinks improves both the average secrecy rate between the access point and its associated sink, as well as the overall average secrecy rate.
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ABSTRACT Due to global energy concerns, much emphasis is placed on reducing the energy usage of power line communications (PLC). PLC, however, presents many significant challenges, such as narrowband interference, that makes the energy... more
ABSTRACT Due to global energy concerns, much emphasis is placed on reducing the energy usage of power line communications (PLC). PLC, however, presents many significant challenges, such as narrowband interference, that makes the energy efficiency reduced. In this paper, a green data transmission system is proposed that improves the energy efficiency of PLC by using spectrum sensing techniques. Furthermore, a performance optimization algorithm is presented that maximizes the energy efficiency of PLC by carefully choosing the optimal spectrum sensing duration and the optimal transmit powers. Numerical results verify that the proposed system can mitigate the effects of interference, with improved energy efficiency.
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ABSTRACT For the emerging 60GHz millimeter-wave communications, the nonlinearity is usually inevitable due to RF power amplifiers operating in the ultra-high frequency and enormous bandwidth, which, in collusion with frequency-selective... more
ABSTRACT For the emerging 60GHz millimeter-wave communications, the nonlinearity is usually inevitable due to RF power amplifiers operating in the ultra-high frequency and enormous bandwidth, which, in collusion with frequency-selective propagations, poses great challenges to signal detections. In contrast to classical schemes calibrating nonlinear distortions in transmitters, a blind detection algorithm is presented in this investigation, with which both the multipath response and symbols contaminated by nonlinear distortions and multipath interferences are estimated in receiver-ends. The Monte-Carlo sequential importance sampling based particle filtering is used, and the non-analytical distribution is approximated numerically by a group of random measures with evolving weights. By applying the Taylor's series expansion techniques, a local linearization model is further constructed to facilitate the practical design of a sequential detector. Simulation results validate the proposed blind detection scheme. By excluding the transmitting predistorter with complex computations and implementations, the presented algorithm provides a promising signal detection framework in 60GHz systems.
... In order to deal with the hidden terminal problem in cognitive radio networks, multiplecognitive users can cooperate to conduct spectrum sensing. ... In other recent works [10], [11], optimal sensing-throughput tradeoff was studied. ...
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In this paper, a new analytical method based on exact statistical modeling of multiple access interference (MAI) is proposed for exact bit error rate (BER) computation of time hopping pulse position modulation (TH-PPM) ultra wideband... more
In this paper, a new analytical method based on exact statistical modeling of multiple access interference (MAI) is proposed for exact bit error rate (BER) computation of time hopping pulse position modulation (TH-PPM) ultra wideband (UWB) systems. The proposed modeling considers full asynchronism. Furthermore, it is also suitable for modeling the MAI components contributed by individual paths in channels with
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... j T u T jT r bt rt dt s I n τ + = − = + where ( ) { } 1 2 1 (0) M s ww m s m MN ER = ∈ − − and the MAI component is given by Modeling of Multiple Access Interference and SER Derivation for M-ary TH-PAM /PPM UWB Systems S.Niranjayan,... more
... j T u T jT r bt rt dt s I n τ + = − = + where ( ) { } 1 2 1 (0) M s ww m s m MN ER = ∈ − − and the MAI component is given by Modeling of Multiple Access Interference and SER Derivation for M-ary TH-PAM /PPM UWB Systems S.Niranjayan, A. Nallanathan and B. Kannan ...
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Impulse radio (IR) is based on an ultra-wideband time-hopping spread spectrum technique in which sub-nanosecond pulses are modulated to convey information by shifting the relative time position of the pulses. The paper analyzes the... more
Impulse radio (IR) is based on an ultra-wideband time-hopping spread spectrum technique in which sub-nanosecond pulses are modulated to convey information by shifting the relative time position of the pulses. The paper analyzes the influence of temporal and spatial diversities on the performance of ultra-wideband impulse radio systems. We investigate how antenna diversity (uniform linear array and rectangular array) can
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ABSTRACT In this paper, we investigate the cluster identification of ultra-wideband (UWB) multipath propagations from a promising biological processing perspective. In the presented biological cluster extraction method, both the amplitude... more
ABSTRACT In this paper, we investigate the cluster identification of ultra-wideband (UWB) multipath propagations from a promising biological processing perspective. In the presented biological cluster extraction method, both the amplitude decay and time of arrival of UWB channel impulse response (CIR) are fully taken into considerations. Each resolvable multipath component is projected onto a two dimensional amplitude-time workspace, and then modeled as a virtual ant-agent. Thus, these ant-agents can move around in this 2-D space with a preference to the high local environment similarity. By establishing a subtle population similarity and specifying an efficient position adaptation strategy, cluster identification can be elegantly realized by the biological ant colony clustering (ACC) procedure. As the experimental simulations shown, the suggested algorithm can accurately and efficiently identify the involved multiple clusters in a completely automatic manner, which is of great importance to UWB channel modeling and parameters extractions.
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Bluetooth is an emerging, short range, indoor wireless network technology, based on FH-CDMA/TDD, which allows a collection of devices to form small overlapping networks, called piconets, in an ad hoc fashion. The performance of a... more
Bluetooth is an emerging, short range, indoor wireless network technology, based on FH-CDMA/TDD, which allows a collection of devices to form small overlapping networks, called piconets, in an ad hoc fashion. The performance of a Bluetooth link is evaluated in multipath fading channels in the presence of interference from an IEEE 802.11b wireless local area network (WLAN).
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Space-time (ST) block coded multi-carrier code division multiple access (MC-CDMA) has been proposed as an attractive solution for high data rate transmission in a multipath fading environment. A space-time-frequency (STF) block coded... more
Space-time (ST) block coded multi-carrier code division multiple access (MC-CDMA) has been proposed as an attractive solution for high data rate transmission in a multipath fading environment. A space-time-frequency (STF) block coded MC-CDMA scheme is presented. The proposed scheme is a four-branch transmitter diversity system which utilizes block codes formed over the space, time and frequency domains. The performance of the STF block coded MC-CDMA scheme is then compared with that of the ST block coded MC-CDMA and SF block coded MC-CDMA systems with four transmitting antennas. It is shown that the proposed STF block coded MC-CDMA scheme gives better performance over fast frequency selective fading channels.
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An interesting demonstration for this paper.
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A full tutorial version for our paper published in Proceedings of the IEEE.