Cooperative spectrum sensing in cognitive radio networks: A survey

This document provides updates to IEEE Std 802.16's MIB for the MAC, PHY and asso- ciated management procedures in order to accommodate recent extensions to the standard.

IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems Draft Amendment: Management Information Base Extensions

The Transmission Control Protocol.

With the rapid deployment of new wireless devices and applications, the last decade has witnessed a growing demand for wireless radio spectrum. However, the fixed spectrum assignment policy becomes a bottleneck for more efficient spectrum utilization, under which a great portion of the licensed spectrum is severely under-utilized. The inefficient usage of the limited spectrum resources urges the spectrum regulatory bodies to review their policy and start to seek for innovative communication technology that can exploit the wireless spectrum in a more intelligent and flexible way. The concept of cognitive radio is proposed to address the issue of spectrum efficiency and has been receiving an increasing attention in recent years, since it equips wireless users the capability to optimally adapt their operating parameters according to the interactions with the surrounding radio environment. There have been many significant developments in the past few years on cognitive radios. This paper surveys recent advances in research related to cognitive radios. The fundamentals of cognitive radio technology, architecture of a cognitive radio network and its applications are first introduced. The existing works in spectrum sensing are reviewed, and important issues in dynamic spectrum allocation and sharing are investigated in detail.

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Advances in cognitive radio networks: A survey

Intelligent reflecting surface (IRS) is an enabling technology to engineer the radio signal propagation in wireless networks. By smartly tuning the signal reflection via a large number of low-cost passive reflecting elements, IRS is capable of dynamically altering wireless channels to enhance the communication performance. It is thus expected that the new IRS-aided hybrid wireless network comprising both active and passive components will be highly promising to achieve a sustainable capacity growth cost-effectively in the future. Despite its great potential, IRS faces new challenges to be efficiently integrated into wireless networks, such as reflection optimization, channel estimation, and deployment from communication design perspectives. In this paper, we provide a tutorial overview of IRS-aided wireless communications to address the above issues, and elaborate its reflection and channel models, hardware architecture and practical constraints, as well as various appealing applications in wireless networks. Moreover, we highlight important directions worthy of further investigation in future work.

Intelligent Reflecting Surface-Aided Wireless Communications: A Tutorial

In this letter, a novel reconfigurable intelligent surface (RIS) aided partial non-orthogonal multiple access (P-NOMA) downlink is investigated, where the passive beamforming on the RIS is designed for serving paired user equipments (UEs), with their signal frequencies partially overlapped. We consider the general case that all UEs have both direct and reflection links undergoing Rayleigh and Nakagami- ${m}$ fadings. By approximating the effective channel gains of the P-NOMA UEs as Gamma random variables, we derive the closed-form expressions of the lower and upper bounds on the achievable rates. The accuracy of the derived close-form expressions are verified through simulation and numerical results, where the proposed RIS-aided P-NOMA downlink considerably outperforms the conventional NOMA and orthogonal counterparts.

Partial Non-Orthogonal Multiple Access: A New Perspective for RIS-Aided Downlink

Special Issue on Secure and privacy-preserving Autonomous Vehicle Networks (AVNs)

This paper tackles the resource allocation problem for wavelength division multiplexing (WDM) networks supporting virtual private networks (O-VPNs), in which working and spare capacity are allocated in the networks for satisfying a series of traffic matrices corresponding to a group of O-VPNs. Based on the (M:N)/sup n/ protection architecture where multiple protection groups (PGs) are supported in a single network domain, we propose two novel integer linear programming (ILP) models, namely ILP-I and ILP-II, aiming to initiate a graceful compromise between the capacity efficiency and computation complexity without losing the ability of addressing the QoS requirements in each O-VPN. ILP-I optimizes the task of resource allocation by taking each O-VPN as a PG, while the ILP-II breaks down each O-VPN into multiple small PGs where all the working paths in each PG are mutually link-disjointedly routed. Experiment results show that in terms of capacity efficiency, a significant improvement can be achieved by ILP-I compared to that by ILP-II at the expense of much longer computation time. Although ILP-II is outperformed by ILP-I, it can handle the situation with an arbitrary size of O-VPNs. We conclude that the proposed ILP-II model yields a scalable solution for the capacity planning in the survivable optical networks supporting O-VPNs based on the (M:N)/sup n/ protection architecture.

Survivable routing and wavelength assignment (RWA) in optical virtual private networks (O-VPNs)

This paper introduces a novel dynamic survivable routing scheme in all-optical mesh networks, namely dynamic joint design heuristic (DJH), for achieving ultrafast and signaling-free failure restoration with low blocking probabilities. A unique feature of DJH is a joint design for the optical layer monitoring plane and survivable routing, where monitoring trails(m-trails)are launched and can possibly reuse the spare capacity reserved for protection light-paths (P-LPs). We demonstrate how the proposed scheme determines the working lightpath and the corresponding P-LP(s), along with the configuration of the alarm code table at each node for each newly arrived connection request, where the targeted all-optical restoration can be fully ensured. Extensive simulation is conducted to examine the proposed DJH scheme in terms of blocking probabilities and compare it with a couple of previously reported counterparts, namely a p-cycle-based dynamic routing scheme and a failure dependent protection-based survivable routing scheme without considering all-optical monitoring. We verify the proposed scheme and disclose insights on its performance behaviors.

On achieving all-optical and signaling-free failure restoration under dynamic traffic

This article investigates energy-efficient secure communication design with the help of multiple phase-adjustable intelligent reflecting surfaces (IRSs). By creating desirable radiation patterns of wireless environment, the IRSs are used to significantly improve the number of bits securely delivered to the destination per energy consumption in Joule, also known as the secrecy energy efficiency (SEE). By manipulating the discrete reflecting coefficients of multiple IRSs and taking advantage of the active beamforming, this article develops an efficient alternating optimization algorithm based on successive convex approximation and penalty-based techniques to effectively fight against multiple eavesdroppers. Simulation results characterize the graceful tradeoff between conflicting performance metrics, i.e., total power consumption and secrecy rate in the multi-IRS-aided secure communication system, and corroborate that incorporating multiple IRSs is beneficial to both the SEE and secrecy rate enhancement compared to existing related benchmarks.

Pin-Han Ho

Papers

Partial Non-Orthogonal Multiple Access: A New Perspective for RIS-Aided Downlink

Special Issue on Secure and privacy-preserving Autonomous Vehicle Networks (AVNs)

Survivable routing and wavelength assignment (RWA) in optical virtual private networks (O-VPNs)

On achieving all-optical and signaling-free failure restoration under dynamic traffic

Secrecy Energy Efficiency Maximization for Distributed Intelligent-Reflecting-Surface-Assisted MISO Secure Communications