Network Coding with Multimedia Transmission and Cognitive Networking: An Implementation based on Software-Defined Radio

Network coding (NC) is considered a breakthrough to improve throughput, robustness, and security of wireless networks. Although the theoretical aspects of NC have been extensively investigated, there have been only few experiments with pure NC schematics. This paper presents an implementation of NC under a two-way relay model and extends it to two\ua0non-straightforward scenarios: (i) multimedia transmission with layered coding and multiple-description coding, and (ii) cognitive radio with Vandermonde frequency division multiplexing (VFDM). The implementation is in real time and based on software-defined radio (SDR). The experimental results show that, by combining NC and source coding, we can control the quality of the received multimedia content in an on-demand manner. Whereas in the VFDM-based cognitive radio, the quality of the received content in the primary receiver is low (due to imperfect channel estimation) yet retrievable. Our implementation results serve as a proof for the practicability of network coding in relevant applications

Sensing techniques for Cognitive Radio - State of the art and trends

This document was initiated in the framework of the IEEE Standards Coordinating Committee 411(Dynamic Spectrum Access Networks) within the 1900.6 Working group (Spectrum SensingInterfaces and Data Structures for Dynamic Spectrum Access and other Advanced RadioCommunication Systems).This documents aims at identifying the spectrum sensing techniques being used of researched and thatmay be considered for the 1900.6 standardization activities. Although it gathers State of the Artmaterial, this document does not aim at being a scientific paper in that regard that the equations arenot always justified or demonstrated. However, it provides sufficient information to have a goodperspective on the problems to solve, the techniques that have been proposed and the one that mayemerge in the next few years. Links to a wide bibliography section is systematically provided toenable the reader to get more technical details.Since 1900.6 deals with Spectrum Sensing, the focus is put on this issue in this paper.Section 3 deals with single sensor spectrum sensing. In this section, the level of a priori knowledgeabout the signal to detect is discussed and different techniques are presented according to thisparameter.Section 4 is somehow an extension of section 3 in which the problem is extended to the identificationof systems in presence through the estimation of key specific parameters. The example of OFDMsignal is highlighted for which sub-carrier spacing one of the parameters considered to differentiatethe standards.Section 5 extends the scope of section 3 by considering several sensors. Cooperative sensing andcollaborative sensing are discussed in this section.Section 6 briefly discussed the estimation of the load of a system. This information may be adetermining parameter to decide on the network to get connected to.Section 7 provides application examples of the spectrum sensing techniques described previously inscenarios involving standardized wireless systems. Performance of the techniques is discussed.Section 8 reminds that a cognitive radio often has to sense information that is not captured byspectrum sensing. For instance, battery lifetime may be relevant for decision making in batteryoperated devices