May 2019 edition of the TCCN Newsletter launched

(Download the newsletter here)

Since December 2015, this Newsletter has presented and discussed some emerging topics related to the TCCN areas of interest. More specifically, it has covered a broad range of applications and techniques, for instance, non-orthogonal multiple access, ultra-reliable low-latency communications (URLLC), millimeter wave communications, unmanned aerial vehicle (UAV) communications, and massive machine-type communications (mMTC). We have interviewed over a dozen experts in these fields, included several interesting position papers, and provided state-of-the-art reviews. My sincere thanks to all the previous directors for their
contributions and help which have made this Newsletter a great success.

From my side, I have contributed in two previous TCCN Newsletter editions as Feature Editor, and this TCCN Newsletter issue is the first one that I am acting as Director. It has been a great pleasure and honor for me, and I am excited to cover two areas that will likely have impact in 5G and beyond: a) Blockchain and b) Internet of Things (IoT). In the Blockchain area, we have interviewed Prof. Dusit Niyato, from Nanyang Technological University, Singapore, and Dr. Bhaskar Krichnamachari, from USC, who are leading experts in this area. We have also had the pleasure to get a position paper from Dr. BhaskarKrichnamachari. Within the context of IoT, we have interviewed Prof. Luiz A. da Silva, from Trinity College Dublin, Dr. Samir Perlaza, from INRIA, France, and Prof. Sergey Andreev, fromTampere University, Finland, who provided uswith their outlook on the opportunities and challenges of IoT. Finally, Prof. Giancarlo Fortino and Dr. Claudio Savaglio, from Università della Calabria, Italy, provided a position paper that presents ACOSO-Meth (Agent-based Cooperating Smart Objects Methodology), the first agent-based methodology that specifically and seamlessly supports the main phases of engineering of IoT ecosystems and related services.

Finally, I would like to thank our two feature topic editors: Prof. Walid Saad, from Virginia Tech – USA, and Prof. Pedro H. J. Nardelli, from Lappeenranta University of Technology – Finland, for their efforts in arranging the content of this Newsletter. Moreover, we want to thank all authors and interviewees for sharing with us their experience and time. I would finally like to acknowledge the gracious support from the TCCN chair, Dr. Yue Gao and all TCCN officers. If you have any suggestion, feel free to contact me at: We hope that you enjoy the material of this Newsletter!

Daniel Benevides da Costa
Director, IEEE ComSoc TCCN Newsletter
Federal University of Ceará, Brazil

Dec 2018 edition of the TCCN Newsletter launched

(Download the newsletter here)

Over the past couple of years, we have strived to reshape this newsletter to expose some of the more emerging topics related to the TCCN areas of interest. In this regard, we have covered a broad range of applications and techniques, ranging from ultra-reliable low latency communications (URLLC) to the Internet of Things. We have interviewed over a dozen experts in these fields, and included several interesting position papers and reviews of the state-of-the-art.

In this final TCCN Newsletter for which I will be the director, I am excited to cover two areas that will likely have impact in 5G and beyond: a) Communications with unmanned aerial vehicles (UAVs) and b) massive machine type communications (mMTC). In the UAVs area, we have reviewed two key papers from recent works. We have also had the pleasure to interview Dr. Christian Bettstetter from the University of Klagenfurt, Austria, is a leading expert in this area.

Moreover, Dr. Halim Yanikomeroglu from Carelton University, who initiated much of the research on UAV communications, has also provided us with an exciting position paper in this domain. Within the context of mMTC, we have interviewed Dr. Giuseppe Durisi from Chalmers University, Sweden, Dr. Zaher Dawy from the American University of Beirut, Lebanon, and Dr. Toktam Mahmoodi from King’s College, UK, who provided us with their outlook on the opportunities and challenges of mMTC. Finally, Dr. Ekram Hossain from the University of Manitoba, Canada, provided a position paper that outlines the role of NOMA in machine type communications.

Finally, I would like to thank our two feature topic editors: Dr. Daniel Benevides da Costa from UFC – Brazil and Dr. Omid Semiari from Georgia Southern University, USA, for their efforts in arranging the content of this Newsletter. Moreover, we want to thank all interviewees for sharing with us their experience and time. I would finally like to acknowledge the gracious support from the TCCN chair, Dr. Jianwei Huang and all TCCN officers over the past two years. I look forward to seeing future TCCN newsletters with more exciting research insights and discussions.

Dr. Walid Saad
Vice Chair, IEEE ComSoc TCCN
Department of Electrical and Computer Engineering
Virginia Tech, USA

May 2018 edition of the TCCN Newsletter launched

(Download the newsletter here)

For decades, the wireless network evolution has been driven by a strive for higher data rates. Indeed, the whole premise of 4G networks had been on delivering higher rate and high network capacity. However, the advent of the Internet of Things and associated services, such as autonomous vehicles and virtual reality, has radically changed the wireless landscape. In particular, we are witnessing a major shift from data rate-centric wireless networks, to networks that require very low latency and high reliability. In this new latency-centric landscape, cognitive networking approaches will inevitably play a key role. In this regard, this TCCN Newsletter will delve into two key emerging technologies that pertain to the paradigm of highly reliable, low latency communications: a) ultra reliable low latency communication (URLLC) and b) mobile edge computing (MEC). Both URLLC and MEC will be critical components of emerging 5G networks and major contributors for the shift from rate-centric systems to latency-centric systems. Consequently, exposing their challenges and opportunities is essential. In order to do so, this first issue of the TCCN Newsletter of 2018 will bring together two feature topics on URLLC and MEC. Within each feature topic, we review the state of the art and provide an in-depth exposition of some of the recent research contributions. For URLLC, we also provide two expert interviews with Drs. Mehdi Bennis and Marios Kountouris, that provide the academic and industrial perspectives on URLLC. In the context of MEC, beyond also reviewing key papers, we provide two expert interviews with Drs. Kaibin Huang and Yang Yang.

That said, we would like to thank our two feature topic editors: Dr. Daniel Benevides da Costa from UFC – Brazil and Dr. Jie Xu, from Guangdong University of Technology, for their efforts in arranging the paper reviews and expert opinion. Moreover, we want to thank all interviewees for sharing with us their useful experience and future outlook on the discussed areas. I would finally like to acknowledge the gracious support from the TCCN chair, Dr. Jianwei Huang and all TCCN officers. As always, if you have any suggestions, feel free to contact me at: We hope that you enjoy the material provided here!

Dr. Walid Saad
Vice Chair, IEEE ComSoc TCCN
Department of Electrical and Computer Engineering
Virginia Tech, USA

November 2017 edition of the TCCN Newsletter launched

(Download the newsletter here)

Dynamic spectrum access and spectrum sharing lie at the heart of cognitive radio networks. As such, developing new multiple access techniques along with exploiting unconventional frequency bands are necessary steps needed to ensure the wide-scale deployment of cognitive radio networks. In this regard, this TCCN Newsletter will delve into two key emerging technologies in this regard: a) non-orthogonal multiple access (NOMA) and b) Millimeter wave communications (mmWave). Both NOMA and mmWave are considered as major components of emerging 5G networks and, as such, exposing their challenges and opportunities is essential. In order to do so, this second issue of the TCCN Newsletter of 2017 will bring together two feature topics on NOMA and mmWave. Within each feature topic, we review the state of the art and provide an in-depth exposition of some of the recent research contributions. For NOMA, we also provide a position paper from Dr. Zhiguo Ding’s group who has been the driving force behind many of the key contributions in NOMA. In addition to these two feature topics, we discuss the theme of “Spectrum Scarcity”, which has been driving much of the research in wireless networks, in general, and cognitive radio networking, in particular, over the past few years. Within the context of this theme, we get expert opinions from Drs. Akbar Sayeed and Mérouane Debbah along with two position papers from the groups of Dr. Danijela Cabric and Dr. George K. Karagiannidis, that expose various research challenges within this theme.

That said, we would like to thank our two feature topic editors: Dr. Daniel Benevides da Costa from UFC – Brazil and Dr. Omid Semiari, from Georgia Southern University, for their efforts in arranging the paper reviews, positions papers, and expert opinion. Moreover, we want to thank all authors and interviewees for contributing their significant research works to the two feature topics and sharing with us their useful experience and future outlook on the area. I would finally like to acknowledge the gracious support from the TCCN chair, Dr. Jianwei Huang and all TCCN officers.  As always, if you have any suggestions, feel free to contact me at: We hope that you enjoy the material provided here!

Dr. Walid Saad
Vice Chair, IEEE ComSoc TCCN
Department of Electrical and Computer Engineering
Virginia Tech, USA

Third Edition of the TCCN Newsletter launched

Cognitive radio networks are at the cusp of a major revolution. What started as a paradigm for spectrum sharing and dynamic spectrum access, grew into a major wireless communications field that weaves together multiple disciplines ranging from communication theory to machine learning, network science, and network science. As such, the concept of a cognitive network is rapidly evolving from a traditional, spectrum-centric perspective to a broader, network-wide perspective, in which cognition should no longer be restricted to spectrum access but must instead span the entire panoply of network functions.

This need for large-scale, intelligent cognition in wireless networks coupled with the ongoing 5G revolution, is also ushering in numerous innovative applications for cognitive radio networks that range from smart transportation to broad Internet of Things (IoT) ecosystems. In order to accompany this major change in cognitive networking paradigm, this first issue of the TCCN Newsletter of 2017 will primarily focus on new analytics and wireless applications which are expected to be central to tomorrow’s cognitive radio networks. In particular, this newsletter will feature two key cognitive radio networking topic: a) The Internet of Things and b) Machine Learning. For each topic, we have gathered a review on innovative new results that have appeared in the recent literature. Then, we had some stimulating discussions with leaders in the fields, in order to provide an in-depth discussion on the major technical challenges and opportunities in these two central areas of cognitive radio networking.

That said, we would like to thank our two feature topic editors: Dr. Nguyen Tran from Kyung Hee University and Dr. Muhammad Zeeshan Shakir from the University of West Scotland, for their efforts in arranging the paper reviews and expert interviews. Moreover, we want to thank all interviewees for contributing their significant research works to the two feature topics and sharing with us their useful experience and future outlook on the area. I would finally like to acknowledge the gracious support from the TCCN chair, Dr. Jianwei Huang and all TCCN officers. As always, if you have any suggestions, feel free to contact me. We hope that you enjoy the material provided here!

Dr. Walid Saad
Vice Chair, IEEE ComSoc TCCN
Department of Electrical and Computer Engineering
Virginia Tech, USA

Secure Cognitive Radio Networks with Multi-Phase Smart Relaying and Cooperative Jamming

Originally posted in Sec-IG blog (link to the original post)

Pin-Hsun Lin and Eduard A. Jorswieck

Dresden University of Technology, Germany

Due to the broadcast nature of wireless networks, communications are potentially subject to attacks, such as passive eavesdropping or active jamming. Instead of using the traditional cryptographic approaches [2] to combat the malicious users, we consider the information-theoretic secrecy. Note that the information-theoretic secrecy approach, initiated by Shannon [3] and developed by Wyner [4], can exploit the randomness of the wireless channels to ensure the secrecy of the transmitted messages while there is no assumption on the computation capabilities at the malicious users. As a performance measure for communication systems with secrecy constraints, a secrecy rate is defined as a rate at which the message can be transmitted reliably and securely between the legitimate nodes. However, similar to communication networks without secrecy constraints, the overall performance is limited by the relative channel qualities to guarantee secure communications. Many signal processing and multi-user techniques have therefore been proposed to overcome this limitation such as the use of multiple antennas.

Recently, there has been a substantial interest in the secrecy of multi-user systems [5], with a particular emphasis on potential cooperation between users to enhance the secrecy of communications. Cooperation in communication networks is an emerging technique to improve the reliability of wireless communication systems, and it involves multiple parties assisting each other in the transmission of messages, see e.g., [6]. Assuming that the cooperative node(s) can be trusted and that they aim at increasing the secrecy of the original transmission in the presence of a possible external eavesdropper, several cooperative strategies have been proposed. As one kind of cooperative communications schemes, cognitive radio technology has been proposed by Mitola in [7] as an efficient way to enhance the spectrum efficiency which has considerable development over the last few decades. The concept of cooperation for secrecy, and the corresponding cooperative techniques can naturally be applied to the cognitive radio network.

In this article, we consider a cognitive radio (CR) network including four single-antenna half-duplex nodes, where the CR receiver is treated as a potential eavesdropper with respect to the primary transmission [1]. In exchange for cooperation from the CR user to improve/maintain his own secrecy rate, the primary user allows the CR user to share part of the spectrum. Compared to some important literature in this research line, e.g., [8], [9], and [10], etc., we additionally consider the following secure coexistence conditions:

(i) the transmission of CR transmitter does not degrade the primary user’s secrecy rate, and
(ii) the encoder and decoder at the primary transmitter and receiver, respectively, are left intact whether CR transmits or not.

The reasons to consider the secure coexistence conditions are twofold. First, to utilize the time-frequency slot in the overlay sense, cognitive radio systems are obligated not to interfere the primary systems, which is common in cognitive radio systems design. Second, with the condition (ii), cognitive radios are backward compatible with the legacy systems, which cannot sense and adapt to the environment agilely. This conditions make the cognitive radio capable of operating in broader usage scenarios. One of the possible practical scenarios of the considered model is that, the primary users belong to a licensed system, who sells rights of the spectrum usage to a femtocell system. Here we can let the CR transmitter and receiver be the femtocell base station and users, respectively. However, the femtocell operator may not be able to guarantee that the femtocell users are malicious or not. Thus, to provide a secrecy transmission to the primary users, not only the primary base station needs to use the wiretap coding, but also the femtocell base station needs to help to maintain the secrecy transmission for the primary system.

We analyze the achievable secrecy rate with weak secrecy of the cognitive user in the cognitive radio network under the secure coexistence conditions. In addition, we derive the rate constraints to guarantee that the primary user’s weak secrecy is unchanged as well, which requires different analysis compared to [8], [9], [10]. For example, the relation between channels observed by the primary transmitter before and after the cognitive transmitter is active should investigated for proper relay and jamming design. Otherwise, either the reliability of the cognitive user or the secrecy of the primary user will be violated. In Fig. 1 we show two improper system designs, where the black rectangular denotes the wiretap code used by the primary user, i.e., the row and column of it are indexed by the secure and confusion messages, respectively and each entry is a codeword. The height and width of the blue rectangular denote the capacity of the channels between the primary transmitter to the primary receiver and that between the primary transmitter to the CR receiver, respectively, after CR transmitter starts to transmit. Fig. 1 (a) shows that, both reliability and secrecy are fulfilled. However, the cognitive transmitter may overdesign the relay power for the primary user’s signal such that the capacity is too large, which is inefficient for the CR user. In particular, that means CR transmitter wastes power on constructing a too good channel for the primary user., while the remained power for CR’s own transmission is reduced. In contrast, Fig. 1 (b) shows that, the relay is efficient, i.e., the new channel is efficient for the transmission of the secure message. However, the confusion rate is not high enough for the new channel, which causes that the secrecy is violated. Therefore, the analysis of the aforementioned rate constraints is important. In addition, we also derive a capacity upper bound for the CR user under both discrete memoryless and additive white Gaussian noise (AWGN) channels to evaluate the performance of the achievable scheme.

Fig. 1. Improper design of the relay and jamming.

We then propose a multi-phase transmission scheme, which considers the following additional phases. First, to accommodate the operations of practical systems, we take into account the first additional phase for listening to/decoding the primary’s signal at the CR transmitter. Note that the primary user’s signal is commonly assumed non-causally known at CR transmitter. Second, we introduce another additional phase as the third one to endow the cognitive system an extra degree of freedom for utilizing different transmission schemes. For AWGN channels, this degree of freedom improves the performance by exploiting pure relaying and jamming but not simultaneously transmitting cognitive user’s own signal.

Finally, we illustrate our results through one numerical example as shown in Fig. 2 based on a geometrical setup, which highlights the impact of the node geometry on the achievable rates and on the optimal power allocation and time splitting of the CR transmitter. Note that we fix the locations of the primary transmitter and receiver at the coordinates (0,0) and (1,0), respectively. The CR receiver is fixed at (1,-1). We assume a path-loss model with path-loss exponent. The power constraints at the primary and CR transmitters are 10 dB and 20 dB, respectively. Note that we also include the power control as a possible design parameter for the CR transmitter, i.e., the transmission power utilized is not necessarily fixed to its maximum. The unit of rate results is bit per channel use. Further numerical results in [1] show that 1) the proposed 3-phase clean relaying scheme indeed improves the cognitive user’s rate; 2) the proposed achievable scheme is close to capacity when the CR transmitter/receiver is far/close enough to the primary receiver/transmitter, respectively.

Fig. 2. Maximum achievable CR user’s rates as a function of the position of the CR transmitter.



[1] P. -H LIn, F. Gabry, R. Thobaben, E. A. Jorswieck and M. Skoglund, “Multi-Phase Smart Relaying and Cooperative Jamming in Secure Cognitive Radio Networks”, IEEE Transactions on Cognitive Communications and Networking, Vol. 2, No 1 pp. 38-52, Mar. 2016

[2] A. J. Menezes, P. C. van Oorschot, and S. A. Vanstone, Handbook of Applied Cryptography. Boca Raton, FL, USA: CRC Press, 1996.

[3] C. E. Shannon, “Communication theory of secrecy systems”, Bell Syst. Tech. J., vol. 28, no 4, pp. 656-715, Oct. 1949.

[4] A. D. Wyner, “The wire-tap channel”, Bell Syst. Tech. J., vol. 54, no 8, pp. 1355-1387, Oct. 1975.

[5] Y. Liang, A. Somekh-Baruch, H. V. Poor, S. S. Shamai, and S. Verdú, “Capacity of cognitive interference channels with and without secrecy,” IEEE Trans. Inf. Theory, vol. 55, no. 2, pp. 604–619, Feb. 2009.

[6] H. G. Bafghi, S. Salimi, B. Seyfe, and M. R. Aref, “Cognitive interference channel with two confidential messages,” in Proc. IEEE Int. Symp. Inf. Theory Appl. (ISITA), Taichung, Taiwan, 2010, pp. 952–956.

[7] R. K. Farsani and R. Ebrahimpour, “Capacity theorems for the cognitive radio channel with confidential messages,” in Proc. IEEE Int. Symp. Inf. Theory (ISIT), Honolulu, HI, USA, 2014, pp. 1416–1420.

CFP: Cognitive Radio and Networks Symposium at IEEE GLOBECOM 2017

Scope and Motivation: Emerging cognitive radio communications and networking technologies potentially provide a promising solution to the spectrum underutilization problem in wireless access, improving the interoperability and coexistence among different wireless/mobile communications systems and making the future-generation radio devices/systems autonomous and selfreconfigurable. The goal of this symposium is to bring together and disseminate state of the art research contributions that address various aspects of analysis, design, optimization, implementation, standardization, and application of cognitive radio communications and networking technologies. The scope of this symposium includes (but is not limited to) the topics below.

Main Topics of Interest: The Cognitive Radio and Networks Symposium seeks original contributions in, but not limited to, the following topical areas:

● Challenges and issues in designing cognitive radios and cognitive radio networks

● Architectures and building blocks of cognitive radio networks

● Spectrum sensing, measurements and statistical modeling of spectrum usage

● Waveform design, modulation, and interference aggregation for cognitive radio

● Distributed cooperative spectrum sensing and multi-user access

● Cognitive medium access control, interference management and modeling

● Dynamic spectrum sharing

● Handoff and routing protocols

● Resource allocation for multi-antenna based cognitive radio communications

● Energy-efficient cognitive radio communications and networking

● Self-configuration, interoperability and co-existence issues

● Distributed adaptation and optimization methods

● Machine learning techniques for cognitive radio systems

● Architecture and implementation of database-based cognitive radio networks

● Cooperative and coordinated communications

● Economic aspects of spectrum sharing in cognitive radio networks

● Regulatory policies and their interactions with communications and networking

● Privacy and security of cognitive spectrum-agile networks

● Attack modeling, prevention, mitigation, and defense in cognitive radio systems

● Physical-layer secrecy in cognitive networks

● Modeling and performance evaluation

● Quality of service provisioning in cognitive radio networks

● Spectrum sensing and sharing for Internet of Things

● Spectrum sensing and sharing for mm-wave

● Applications and services (e.g., cognitive networking in TV whitespace, adaptation with LTE networks such as LTE-unlicensed, and integration with other merging techniques such as massive MIMO and full-duplex)

● Cognitive radio standards, test-beds, simulation tools, and hardware prototypes. The authors of selected papers from this symposium will be invited to submit an extended version of their work for fast-track review in the IEEE Transactions on Cognitive Communications and Networking.

How to Submit a Paper:

The submission is through EDAS. Please check IEEE Globecom 2017 website for full instructions. This CFP can also be found at:

Symposium Co-Chairs:

● Jianwei Huang (The Chinese University of Hong Kong)

● K.P. Subbalakshmi (Stevens Institute of Technology)

● Yue Gao (Queen Mary University of London)


Jianwei Huang is an Associate Professor and Director of the Network Communications and Economics Lab (, in the Department of Information Engineering at the Chinese University of Hong Kong. He received the Ph.D. degree from Northwestern University in 2005, and worked as a Postdoc Research Associate at Princeton University during 2005-2007. He is the co-recipient of 8 international Best Paper Awards, including IEEE Marconi Prize Paper Award in Wireless Communications in 2011. He has co-authored five books: “Wireless Network Pricing,” “Monotonic Optimization in Communication and Networking Systems,” “Cognitive Mobile Virtual Network Operator Games,” “Social Cognitive Radio Networks”, and “Economics of Database-Assisted Spectrum Sharing”. He has served as a Founding Associate Editor of IEEE Transactions on Cognitive Communications and Networking, an Associate Editor of IEEE Transactions on Wireless Communications, and a Founding Associate Editor of IEEE Journal on Selected Areas in Communications – Cognitive Radio Series. He is the Vice Chair of IEEE ComSoc Cognitive Network Technical Committee and the Past Chair of IEEE ComSoc Multimedia Communications Technical Committee. He has served as a Distinguished Lecturer of IEEE Communications Society since 2015. At the age of 37, he was elevated to IEEE Fellow for his contributions to resource allocation in wireless cellular and cognitive radio systems, and his seminal work on the economics based analysis and design of modern wireless communication systems.

K.P. Subbalakshmi is a Professor, Department of Electrical and Computer Engineering at Stevens Institute of Technology. Her research interests are in Cognitive Radio Networking, Cognitive Cloud Computing, Dynamic Spectrum Access security, Social Media Analysis and Forensics and their applications to smart cities and connected communities. She was named a Jefferson Science Fellow in 2016. As a JSF she worked at the US Department of State, on technology and policy issues in 5G networks, IoT and Smart and Connected Communities during the Academic Year 2016-2017. She is also a Co-Founder of two technology start-ups that commercialize her work on cognitive radio networks and text analytics. She served as a Subject Matter Expert for the National Spectrum Consortium in 2015. She is a Founding Associate Editor of the IEEE Transactions on Cognitive Communications and Networking. She is the Founding Chair of the Special Interest Group on Security, IEEE COMSOC’s Technical Committee on Cognitive Networks. She is a recipient of the New Jersey Inventors Hall of Fame, Innovator Award.

Yue Gao is a Senior Lecturer (Associate Professor) and Director of Whitespace Machine Communication Lab ( in the School of Electronic Engineering and Computer Science at Queen Mary University of London in United Kingdom. He worked as Research Assistant and Lecturer (Assistant Professor) in the School of Electronic Engineering and Computer Science at QMUL. He received his Bachelor degree from Beijing University of Posts and Telecommunications in China in 2002, and his MSc and PhD degrees in telecommunications and microwave antennas from QMUL in 2003 and 2007, respectively. He has authored and coauthored over 100 peer-reviewed journal and conference papers, 2 best paper awards, 2 patents and 2 licensed works to companies, and one book chapter. He is a Senior Member of the IEEE and has served as the Signal Processing for Communications Symposium Co-Chair for IEEE ICCC 2016, and is serving Publicity Co- Chair for GLOBECOM 2016, and the General Co-Chair of the IEEE WoWMoM 2017.

Posted in CFP

Artificial Intelligence as an Enabler for Cognitive Self-Organizing Future Networks

Originally posted in Sec-IG blog (link to the original post)

Siddique Latif¹, Farrukh Pervez¹, Muhammad Usama², Junaid Qadir²

¹National University of Science and Technology, Islamabad
²Information Technology University (ITU), Lahore

The explosive increase in number of smart devices hosting sophisticated applications is rapidly affecting the landscape of information communication technology industry. Mobile subscriptions, expected to reach 8.9 billion by 2022 [1], would drastically increase the demand of extra capacity with aggregate throughput anticipated to be enhanced by a factor of 1000 [2]. In an already crowded radio spectrum, it becomes increasingly difficult to meet ever growing application demands of wireless bandwidth. It has been shown that the allocated spectrum is seldom utilized by the primary users and hence contains spectrum holes that may be exploited by the unlicensed users for their communication. As we enter the Internet Of Things (IoT) era in which appliances of common use will become smart digital devices with rigid performance requirements (such as low latency, energy efficiency, etc.), current networks face the vexing problem of how to create sufficient capacity for such applications. The fifth generation of cellular networks (5G) envisioned to address these challenges are thus required to incorporate cognition and intelligence to resolve the aforementioned issues. Cognitive radios (CRs) and self-organizing wireless networks are two major technologies that are envisaged to meet the future needs of such next generation wireless networks.

CRs are intelligent and fully programmable radios that can dynamically adapt according to their prevalent environment. In other words, they sense the spectrum and dynamically select the clearer frequency bands for better communication in the most prevailing conditions. In this way, CRs can adaptively tune their internal parameters to optimize the spectrum usage, transmission waveform, channel access methods and modulation schemes with enhanced coverage. However, it is due to the recent advancements in machine learning, software defined radio (SDR) that CR is able to emerge from simulation environment to the real-time applications [3].

The overwhelming traffic growth coupled with the greedy approach towards high quality of service (QoS) has been a major challenge for current wireless systems in terms of network resources and QoS. A new paradigm for wireless communication called 5G has been envisioned to address these challenges. The major component of the envisioned 5G scheme is Self-Organizing Network (SON). SON is a relatively new concept in perspective of wireless cellular networks, it refers to an intelligent network that learns from its immediate environment, while autonomously adapting accordingly to ensure reliable communication. In fact, SON underlines new aspect for automation of future networks in 5G era.

The sensing, learning and reasoning behavior of both CRs and SON is achieved by extensively using artificial intelligence (AI) and machine-learning techniques. The CRs are an evolved form of SDRs, realized by the embodiment of cognitive engine (CE) that exploits the AI techniques for the cognitive behavior to decide optimally.

The CR network (CRN) follows the cognitive cycle, for unparalleled resource management and better network performance. Cognitive cycle, as illustrated in figure 1, begins with sensing of dynamic radio environment parameters, subsequently observing and learning recursively the sensed values for reconfiguration of the critical parameters in order to achieve the desired objectives.

Fig. 1: Learning process in cognitive radios

Cognitive cycle is elaborated in figure 2, which highlights the parameters that CR needs to quantify in order to utilize the available spectrum without affecting primary user’s performance. The sensed parameters are treated as stimuli for achieving different performance objectives, for instance, minimizing the bit error rate or minimizing the power consumption etc. [4]. To achieve the aforementioned objectives, CR adaptively learns deciding optimal values for various significant variables such as power control, frequency band allocation, etc. [4].

Fig. 2: The cognitive cycle of CR

CR incorporates machine learning techniques for dynamic spectrum access (DSA) and capacity maximization. AI-based techniques for decision making such as optimization theory, Markov decision processes (MDPs), and game theory is used to encompass a wide range of applications [3]. The popular learning techniques used in cognitive cycle are support vector machine (SVM), artificial neural networks (ANNs), metaheuristic algorithms, fuzzy logic, genetic algorithms, hidden Markov models (HMMs), Bayesian learning, reinforcement learning, multi-agent systems. Fuzzy logic theory has been used for effective bandwidth, resource allocation, interference and power management [3], [5]–[7]. Genetic algorithms (GAs) have been employed for CRs spectrum and parameters optimization [8]–[10]. ANNs have been incorporated to improve the spectrum sensing and adaptively learn complex environments, without substantial overhead [11], [12]. Game theory enables CRNs to learn from its history, scrutinize the performance of other CRNs, and adjust their own behavior accordingly [13], [14]. In multi-agent domain, reinforcement learning (RL) a reward-penalty based technique, which reinforces immediate rewards to maximize long term goals has been employed for efficient spectrum utilization [15], minimum power consumption [16] and filling the spectrum holes dynamically [17]. SVM, a supervised classification model, is being utilized for channel selection [18], adaptation of transmission parameters [19] and beam-forming design [20]. In CRNs, HMMs have been widely used to identify spectrum holes detection [21], spectrum handoff [22], and competitive spectrum access [23]. The range of AI-based techniques are not limited to the above mentioned applications, other applications of AI in CRNs are expressed in [3], [4]. By combining increasing spectrum agility, context aware adaptability of CR and AI techniques, CR has become an increasingly important feature of wireless systems. IEEE 802.16h has recommended CR as one of its key features and a lot of efforts are being made to introduce CR features in 3GPP LTE-Advance.

The rapid proliferation of multi-radio access technology-disparate smart devices has resulted in complicated heterogeneous mobile networks thus making configuration, management and maintenance cumbersome and error-prone. 5G, expected to handle diverse devices at a massive scale, is foreseen as one of the most complicated networks and hence extensive efforts are being carried out for its standardization. In the recent years, SONs, as depicted in figure 3, have gained significant attention regarding self-configuration, self-optimization and self-healing of such complex networks. The idea behind SONs is to automate network planning, configuration and optimization jointly in a single process in order to minimize human involvement. The planning phase, which includes ascertaining cells locations, inter-cell connecting links and other associated network devices as well as parameters, precedes the configuration phase [24]. Self-configuration means that a newly deployed cell is able to automatically configure, test and authenticate itself and adjust its parameters such as transmission power, inter-cell interference etc. in a plug and play fashion [24]. Self-healing allows trouble-free maintenance and enables networks to recover from failures in an autonomous fashion. In addition, it also helps in routine upgrades of the equipments in order to remove legacy bugs. Self-optimization is the ability of the network to keep improving its performance with respect to various aspects including link quality, coverage, mobility and handoff with an objective to achieve network level goals [24]. Since AI-based techniques are capable to handle complex problems in large systems intrinsically, these techniques are now being proposed to achieve Self Organization (SO) in 5G.

Fig. 3: Illustration of AI-based self-organization in the networks

Self-configuration, in cellular networks, refers to the automatic configuration of initial parameters—neighbouring cells list, IP Addresses and radio access parameters—by a node itself. AI techniques like Dynamic Programming (DP), RL and Transfer Learning (TL) may be employed in 5G to automatically configure a series of parameters to render best services. RL, as opposed to DP which initially builds the environment model to operate, is a model free learning technique that iterates through to reach optimal strategy and may yield superior results in dynamically changing radio conditions [25]. Self-healing is about automatic fault detection, its classification and initiating necessary actions for recovery. Irregularities and anomalies in network may be timely spotted to further restore the system by leveraging different AI based sensing techniques like Logistic Regression (LR), SVM and HMM [25]. Self-optimization includes continuous optimization of parameters to achieve system-level objectives such as load balancing, coverage extension, and interference avoidance. AI techniques that may be exploited to optimize provisioning of QoS to various services mainly belong to the class of unsupervised learning. Besides Gradient Boosting Decision Tree (a supervised learning technique), Spectral Clustering, One-class SVM and Recurrent Neural Networks are few examples in this regard [25]. Figure 4 summarizes the AI algorithms that can be utilized to enhance cellular networks performance.

Fig. 4: AI algorithms for 5G

AI techniques may also exploit network traffic patterns to predict future events and help pre-allocate network resources to avoid network overloading. Furthermore, user-centric QoS-provisioning across tiers of heterogeneous cells may also be granted using AI [25]. Similarly, GAs are employed for cell planning and optimization of coverage with power adjustment [26]. GAs are also suited for the problem of finding the shortest path routing in a large scale dynamic networks [27]. Wenjing et al. in [28] proposed an autonomic particle swarm compensation algorithm for cell outage compensation. The study in [29] introduces the self-optimization technique for the transmission power and antenna configuration by exploiting the fuzzy neural network optimization method. It integrates fuzzy neural network with cooperative reinforcement learning to jointly optimize coverage and capacity by intelligently adjusting power and antenna tilt settings [29]. It adopts a hybrid approach in which cells individually optimize respective radio frequency parameters through reinforcement learning in a distributed manner, while a central entity manages to cooperate amongst individual cells by sharing their optimization experience on a network level [29]. Cells iteratively learn to achieve a trade-off between coverage and capacity through optimization, since increase in coverage leads to reduction in capacity, while additionally improving energy efficiency of the network [29]. ANNs can also be effectively utilized for the estimation of link quality [30]. Mobile devices in an indoor environment have also been localized through the use of ANNs [31]. In fact, AI-based techniques enable network entities to automatically configure their initial parameters before becoming operational [24], adaptively learn radio environment parameters to provide optimal services [25], autonomously perform routine maintenance and upgrades and recover from network failures [24],[25].

In view of the continued proliferation of smart devices, we anticipate that CRs and SON will soon become the basic building blocks of future wireless networks. These technologies will transform future networks into an intelligent network that would encompass user preferences alongside network priorities/constraints. AI, being the basis of both these technologies, will continue to drive ongoing 5G standardization efforts and therefore be the cause of a major paradigm shift. AI techniques will continue to intervene future networks finding their usage in from radio resource management to management and orchestration of networks. In fact, we anticipate that future wireless networks would be completely dominated by AI.


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Performance Analysis of Cognitive Radio Systems with Imperfect Channel Knowledge

Originally posted in Sec-IG blog (link to the original post)

Ankit Kaushik, Friedrich Jondral
Communications Engineering Lab, Karlsruhe Institute of Technology, Germany
Contact Information:

Over the last decade, wireless communication is witnessing a tremendous growth in the data traffic due to ever-increasing number of connected devices. According to the recent surveys on mobile traffic by prominent market leaders Cisco [1] and Ericsson [2], the existing mobile traffic is expected to increase 11-fold  by 2021. Certainly, in future, the state-of-the-art standards (fourth-Generation (4G) – LTE, WiMAX) are incapable of sustaining the substantial amount of data traffic, originating from these devices. It is being visualized that a major portion of this requirement can be satisfied through an additional spectrum. Due to exclusive usage, the spectrum below 6 GHz is not able to meet this demand of additional spectrum, leading to its scarcity. To this end, Cognitive Radio (CR), along with millimeter-wave technology [3] and visible-light communication [4], is envisaged as an alternative source of spectrum. The latter techniques are limited to a point-to-point communication, by which mobility is compromised. In contrast, a CR system aims at an efficient utilization of the spectrum below 6 GHz – suitable for mobile communications – by enabling a secondary access to the licensed spectrum while ensuring a sufficient protection to the licensed users (also referred as a primary system).

Despite the fact that an extensive amount of literature – including [5]-[7] – has been dedicated to the field of CR, its performance analysis has been dealt inadequately from a deployment perspective. Therefore, making it difficult to understand the extent of vulnerability caused to the primary system. In this context, it is essential to establish a deployment-centric viewpoint for analyzing the performance of a CR system. Following this viewpoint, it has been identified that the involved channels’ knowledge at the secondary transmitter is pivotal for the realization of cognitive techniques. However, the aspect of channel knowledge in context to CR systems, particularly its impact on the performance, has not been clearly understood. With the purpose of curtailing this gap, the research carried out at Communications Engineering Lab (CEL), Karlsruhe Institute of Technology (KIT) proposes a successful integration of this knowledge – by carrying out channel estimation – in reference to different CR systems, namely interweave, underlay and hybrid systems. More specifically, our work outlines the following aspects corresponding to the aforementioned CR systems, employing different cognitive techniques such as spectrum sensing, power control and their combination.

Analytical Framework
First, an analytical framework is established to characterize the effects such as time allocation and variation, arising due to the incorporation of imperfect channel knowledge, that are detrimental to the performance of the CR systems [8,9].

In order to satisfy the low complexity and the versatility towards unknown primary user signal requirements, which are necessary for the deployment of the CR systems, a received power-based channel estimation is included in the proposed framework. In this regard, an effort has been made to facilitate a direct incorporation of the estimated parameter (received power) to the performance characterization of the CR systems.

Besides, a stochastic approach is followed for characterizing the variations in the system. In particular, these variations cause uncertainty in the interference power received at the primary system, which may completely disrupt the operation of the CR systems. In order to maintain this uncertainty below a desired level, new interference constraints are proposed.

Performance Tradeoffs
Second, as a major observation, it has been identified that the estimation time is closely associated with the performance of the CR systems. On one side, it is related to the variations incurred in the system, through which the level of uncertainty in the interference can be effectively controlled, ultimately affecting the performance in terms of throughput at secondary receiver, defined as secondary throughput. While on the other side, the time resource allocated for channel estimation directly influences the secondary throughput. In our work, this kind of dual dependency of the secondary throughput on the estimation time has been investigated in the form of performance tradeoffs, namely estimation-sensing-throughput tradeoff for the interweave system and the hybrid system, and estimation-throughput tradeoff for the underlay system, cf. Figure 1.


Figure 1. An illustration of a) estimation-sensing-throughput and b) estimation-throughput tradeoff for interweave system and underlay systems, respectively. The performance tradeoff depicts the achievable throughput at secondary receiver.

These tradeoffs present a useful tool for visualizing the response of a CR system to different choices of the estimation time so that the performance degradation introduced due to the channel estimation can be precisely regulated. In other words, a system designer can utilize these tradeoffs to preclude situations under which the performance degradation becomes intolerable. Conversely, from a theoretical perspective, these tradeoffs can be used to determine a suitable estimation time that yields the maximum achievable secondary throughput while obeying the interference constraints.

Hardware Deployment
Third, using a software defined radio platform, hardware implementations are carried out to validate the feasibility of the analysis proposed [10]-[12]. In addition to this, hardware demonstrators are deployed, which in a way present the operation of CR systems in more practical conditions.

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[8] A. Kaushik, S. K. Sharma, S. Chatzinotas, B. Ottersten, and F. K. Jondral, “Sensing-Throughput Tradeoff for Interweave Cognitive Radio System: A Deployment-Centric Viewpoint,” IEEE Trans. Wireless Commun., vol. 15, no. 5, pp. 3690–3702, May 2016.
[9] A. Kaushik, S. K. Sharma, S. Chatzinotas, B. Ottersten, and F. K. Jondral, “On the Performance Analysis of Underlay Cognitive Radio Systems: A Deployment Perspective,” IEEE Trans. on Cogn. Commun. Netw., vol. 2, no. 3, pp. 273–287, Sep. 2016.
[10] A. Kaushik, M. Mueller, and F. K. Jondral, “Cognitive Relay: Detecting Spectrum Holes in a Dynamic Scenario,” in Tenth International Symposium on Wireless Communication Systems (ISWCS), 2013, pp. 1–2.
[11] A. Kaushik, F. Wunsch, A. Sagainov, N. Cuervo, J. Demel, S. Koslowski, H. J ̈ kel, and F. Jondral, “Spectrum sharing a for 5G wireless systems (Spectrum sharing challenge),” in IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN), Sep. 2015, pp. 1–2.
[12] H. Becker, A. Kaushik, S. K. Sharma, S. Chatzinotas, and F. K. Jondral, “Experimental Study of an Underlay Cognitive Radio System: Model Validation and Demonstration,” in 11th International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM), May-Jun. 2016, pp. 511–523.