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.

/pdf/advances-in-cognitive-radio-networks-a-survey-3gp2nvo27m.pdf

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

— This paper introduces a MAC-layer Active Dropping (AD) scheme for achieving effective resource utilization and maintaining application-level quality of services in real-time video streaming over the emerging wireless broadband access networks based on time-division multiple access (TDMA). By proactively dropping the MAC-layer protocol data units (MPDUs) of a video frame that are unlikely to meet its application-layer delay bound, the proposed scheme releases the precious transmission resources to the subsequent frames or other competing service streams. This leads to more efficient resource utilization than that by the conventional prioritization-based cross-layer approaches which simply manipulate transmission and/or retransmission priority of each MPDU. Furthermore, an analytical model is developed to evaluate how confident a video frame can be effectively delivered within its application-layer delay bound, where the effects of time-varying wireless channel, requirement of bitstreams decodability in each video frame, retransmission of lost data, and playback buffer at the recipient software in a WiMAX network are jointly considered. Extensive simulations are conducted to illustrate the effectiveness of the proposed scheme.

MAC-Layer Active Dropping for Real-time Video Streaming in IEEE 802.16 Networks

The paper investigates dual-link fault localization in all-optical ring networks using optical probes (called monitoring bursts). By defining a single monitoring node (MN) in the ring that initiates and terminates a set of monitoring trails (m-trails), the MN can localize any dual-link fault by inspecting the on-off status of the launched optical bursts. We investigate relevant problems in the proposed fault monitoring approach, including m-trail allocation, burst launching time scheduling, and node switch fabric configuration, where constructions are developed to derive optimal solutions and are further examined in numerical experiments. 2(|Ej| − 1) m-trails and at most (2δ + L)(|E| − 1) + δ(|E| − 2) of monitoring delay are required for dual-link fault localization from a single MN in a ring with|E| links, where δ is the burst propagation delay along a unidirectional link and L is the burst length.

Fault localization in all-optical ring networks

To achieve fast Unambiguous Failure Localization, an essential problem for the network operators is to determine how to efficiently probe the network elements such that the number of probes is the minimum. By launching a set of m-trails, the transmitter of each m-trail constantly probes the health of the links along the m-trail, and the monitor at the receiver issues an alarm once detecting any irregularity. A failure may interrupt multiple m-trails which incurs a set of alarms. The m-trails should be allocated such that the network controller can uniquely and precisely localize the failure state according to the issued alarms. The chapter is on the m-trail allocation problem by introducing algorithms and approaches in presence of single and multiple link failures, respectively. With single-link failures, an essentially optimal construction for m-trail allocation is provided for lattice topologies. For general topologies, a suite of heuristics are presented, including Random Code Swapping (RCA–RCS) for single-link failures, Adjacent Link Failure Localization and Link Code Construction for adjacent link failures, and Greedy Code Swapping (CGT-GCS) for dense-shared risk link group failures based on combinatorial group testing.

https://link.springer.com/content/pdf/10.1007%2F978-1-4614-7738-9_3.pdf

Failure Localization Via a Central Controller

In this paper, we consider broadcasting layered source codes over a single-relay network using a half duplex non-orthogonal amplify-forward (HD-NAF) relaying protocol. Distortion exponent (i.e., the SNR exponent of the average distortion) is taken to evaluate the system performance in the high SNR regime. We prove that the HD-NAF relay network with two-layered codes corresponds to a successive refinable diversity multiplexing tradeoff (DMT) curve.With the identified property, a closed-form expression for an achievable upper bound of the system distortion exponent is derived, which can be achieved via properly allocated power and rate of each layer. Numerical evaluation is conducted to show performance advantages of the considered two-layered HD-NAF protocol against its counterparts.

Layered sources in non-orthogonal amplify-forward relay networks

Reconfigurable intelligent surface (RIS) offers a potential performance boost for next-generation wireless networks, with significant improvements in spectral and energy efficiencies. In this paper, considering a two-user multiple-input single-output non-orthogonal multiple access (MISO-NOMA) downlink, we propose a RIS-aided cooperative transmission scheme using hybrid simultaneous wireless information and power transfer (SWIPT) and transmit antenna selection (TAS) protocols. Particularly, in the proposed scheme, the cell-center user servering as a relay helps the cell-edge user with the support of hybrid time-switching (TS), power-splitting (PS) SWIPT protocols and RIS passive beamforming. To evaluate the network performance, we first derive the best- and worst-case of closed-form expressions in terms of outage probability. For gleaning further insights, we also investigate the diversity order and the high signal-to-noise ratio (SNR) slope for the relevant outage probability. Simulation and numerical results demonstrate the achievable performance improvement for our proposed scheme with respect to schemes of orthogonal multiple access (OMA), non-cooperative NOMA and cooperative NOMA without RIS. In addition, the proposed scheme achieves a higher diversity gain with more transmit antennas and RIS elements.

Pin-Han Ho

Papers

MAC-Layer Active Dropping for Real-time Video Streaming in IEEE 802.16 Networks

Fault localization in all-optical ring networks

Failure Localization Via a Central Controller

Layered sources in non-orthogonal amplify-forward relay networks

Hybrid Time-Switching and Power-Splitting EH Relaying for RIS-NOMA Downlink