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

This paper introduces a new dynamic availability-aware survivable routing scheme under the framework of generalized multi-protocol label switching (GMPLS)-based recovery, which aims to achieve the best generality for the network operation in meeting the end-to-end (E2E) availability requirement of each connection. The paper first defines the partial restorability, justifies the feasibility of equipping a connection with partial restorability under the GMPLS control plane, and highlights the approach of evaluating the E2E availability for a pair of working and partially restorative SRG (shared risk group)-disjoint shared backup label switched paths (LSPs). A compact matrix expression is developed for modeling the minimum spare capacity along each link and the cost function for solving both of the paths. Based on the developed cost function, a novel integer linear program (ILP) is formulated to dynamically determine the working and backup LSPs of the corresponding connection request with the least amount of total capacity while the E2E availability requirement of the connection is met. We demonstrate that the model is general to the traffic uniformity, connection indivisibility, and working bandwidth restorability compared with the previous studies. Simulation is conducted to verify the proposed ILP model by making a comparison with a number of legacy schemes that achieve 100% restorability in facing a specific number of simultaneous failures, such as shared path protection (SPP), 1+1 protection, and dual-failure protection. In the case study, we have seen merits in the proposed algorithm by significantly reducing the required redundancy in the effort of achieving the given availability constraint for each connection request.

A Study on Dynamic Survivable Routing with Availability Constraint for GMPLS-Based Recovery

The use of Orthogonal Frequency Division Multiplexing (OFDM) technology helps an optical transmission system to break the limitation of wavelength grids by Wavelength Division Multiplexing (WDM), in which a flexible and elastic transmission paradigm is created, so as to achieve better spectrum efficiency and flexibility of the fiber resources. This paper investigates a novel adaptive transmission strategy in OFDM based optical transmission systems, aiming to minimize the transmission cost for a bulk data transfer request in terms of energy consumption and bandwidth usage without violating the constraints on the transmission delay and bit error rate (BER) at the receiver. By considering nonlinear effects of Mach-Zehnder modulator (MZM) and amplified spontaneous emission (ASE) noise from optical amplifier, a novel analytical model for the BER expression is provided and the corresponding optimization problem is formulated. In particular, the proposed formulation is the first in the literature that considers the effect of Peak-to-Average Power Ratio (PAPR) on both electrical and optical domain signals. By adaptively choosing the number of subcarriers, modulation level, and coupled laser power, the transmission cost for a given request can be minimized.

An optimization framework for energy-efficient elastic optical transmission systems

http://rboutaba.cs.uwaterloo.ca/Papers/Journals/2006/Haque06.pdf

Group shared protection for spare capacity reconfiguration in optical networks

Multi-copy utility-based routing has been considered as one of the most applicable approaches to effective message delivery in Delay Tolerant Networks (DTNs). By allowing multiple message replicas launched, the ratio of message delivery or delay can be significantly reduced compared with other counterparts. Such an advantage, nonetheless, is at the expense of taking more buffer space at each node and higher complexity in message forwarding decisions. This paper investigates an efficient message scheduling and dropping policy via analytical modeling approach, aiming to achieve optimal performance in terms of message delivery delay. Extensive simulation results, based on a synthetic mobility model and real mobility traces, show that the proposed scheduling framework can achieve superb performance against its counterparts in terms of delivery delay.

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Message Scheduling and Forwarding in Congested DTNs

In this paper, we propose an approach of optimal protection domain allocation, called OPDA (optimal protection domain allocation), for dynamically allocating spare capacity for a given working lightpath in WDM networks with partial wavelength conversion capability. The optimization process is formulated as a shortest path searching problem in a transferred graph of cycles and wavelength graph of paths. We conduct a series of experiments to verify the proposed approach on four networks with different topologies and traffic load. We conduct experiments to compare the blocking probability of using OPSA with four reported schemes. The results show that OPDA achieves the best performance.

Pin-Han Ho

Papers

A Study on Dynamic Survivable Routing with Availability Constraint for GMPLS-Based Recovery

An optimization framework for energy-efficient elastic optical transmission systems

Group shared protection for spare capacity reconfiguration in optical networks

Message Scheduling and Forwarding in Congested DTNs

Protection domain allocation for optical networks with partial wavelength conversion