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 paper, a survivable routing algorithm is proposed for shared segment protection (SSP), called optimal self-healing loop allocation (OSHLA), which dynamically allocates spare capacity for a given working lightpath in mesh wavelength-division-multiplexing (WDM) networks with partial wavelength conversion capability. Two novel graph transformation approaches, namely graph of cycles and wavelength graph of paths, are introduced to solve this problem, in which the task of survivable routing is formulated as a series of shortest path searching processes. In addition to an analysis on the computation complexity, a suite of experiments is conducted to verify OSHLA on four networks with different topologies and traffic loads. We find that the blocking probability and computation complexity are dominated by the upper bound on the length of the working and protection segments. Comparison is made between OSHLA and four other reported schemes in terms of blocking probability. The results show that OSHLA can achieve the lowest blocking probability under the network environment of interest. We conclude that OSHLA provides a generalized framework of survivable routing for an efficient implementation of SSP in mesh WDM partial wavelength convertible networks. With OSHLA, a compromise is initiated by manipulating the upper bound on the length of working and protection segments such that the best performance-computation complexity gain can be achieved.

A novel survivable routing algorithm for shared segment protection in mesh WDM networks with partial wavelength conversion

We study energy detection based spectrum sensing of SU (Secondary User) in cognitive radios. Due to the time varying nature of wireless channels and PU (Primary User) activities, the SINR (Signal to Interference plus Noise Ratio) at the SU receiver changes from slot to slot in a time-slotted system. Unlike the conventional energy detector which uses a fixed energy threshold for spectrum sensing, we dynamically adjust the energy threshold according to the SINR. By limiting the average interference to the PU within a target level, the objective is to maximize the SU's average rate using an optimized policy function, which formulates the threshold as a linear increasing function of the SINR. Simulation results show that the SU's average rate can be significantly improved using the optimized function for dynamic threshold control.

Adaptive Threshold Control for Energy Detection Based Spectrum Sensing in Cognitive Radios

In this paper, we present a novel anonymous secure routing protocol for mobile ad hoc networks (MANETs). The proposed protocol not only provides anonymity from all the intermediate nodes, but also integrates the authenticated key exchange mechanisms into the routing algorithm design. Furthermore, a new attack on anonymous services, called snare attack, is introduced, where a compromised node lures a very important node (VIN) into communicating with him and traces back to the VIN by following the route path. An adversary can then snare the VIN and launch decapitation strike on the VIN. Finally, we present a novel DECOY mechanism as a countermeasure to enhance anonymity of VINs and defeat snare attack.

ASRPAKE: An Anonymous Secure Routing Protocol with Authenticated Key Exchange for Wireless Ad Hoc Networks

This paper introduces a cross-layer design framework for robust and efficient video multicasting over IEEE 802.16 (also known as WiMAX) networks in metropolitan areas. In the framework, multiple description coding (MDC) on scalable video bitstreams at the source for achieving multiresolution robustness is jointly designed with superposition coding (SCM) on multicast signals at the channel to overcome multiuser channel diversity in wireless multicast. The coded multicast signals under the proposed framework can cope with multiuser channel diversity and mitigate the impact due to short-term channel fluctuations, which are the two most challenging issues in achieving robust and efficient video multicasting in metropolitan areas. We formulate the proposed framework and analyze its video quality performance in terms of the total receivable/ recoverable bitstreams by a receiver. A heuristic methodology is developed for system parameter selection and performance optimization that can be applied to practical scenarios of video multicasting for IPTV services in WiMAX. Simulation is conducted based on actual standard video sequences to verify the proposed methodology on parameter selection and performance optimization. Performance gains of the proposed cross-layer design framework in the presence of fading channel diversity are demonstrated.

A cross-layer design framework for robust IPTV services over IEEE 802.16 networks

Location privacy of mobile users (MUs) in wireless communication networks is very important. Ensuring location privacy for an MU is an effort to prevent any other party from learning the MU's current and past locations. In this paper, we propose a novel anonymous mutual authentication protocol with provable link-layer location privacy preservation. We first formulate the security model on the link-layer, forward-secure location privacy, which is characterized by the fact that even when an attacker corrupts an MU's current location privacy, the attacker should be kept from knowing how long the MU has stayed at the current location. Then, based on the newly devised keys with location and time awareness, a novel anonymous mutual authentication protocol between the MUs and the access point (AP) is proposed. To the best of our knowledge, this is the first developed anonymous mutual authentication scheme that can achieve provable link-layer, forward-secure location privacy. To improve efficiency, a preset in idle technique is exercised in the proposed scheme, which is further compared with a number of previously reported counterparts through extensive performance analysis.

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Pin-Han Ho

Papers

A novel survivable routing algorithm for shared segment protection in mesh WDM networks with partial wavelength conversion

Adaptive Threshold Control for Energy Detection Based Spectrum Sensing in Cognitive Radios

ASRPAKE: An Anonymous Secure Routing Protocol with Authenticated Key Exchange for Wireless Ad Hoc Networks

A cross-layer design framework for robust IPTV services over IEEE 802.16 networks

A Novel Anonymous Mutual Authentication Protocol With Provable Link-Layer Location Privacy