Electrical and Computer Engineering Research Report 2008

Department Research New Chair Publications Enterprisehttps://digitalcommons.mtu.edu/ece-annualreports/1005/thumbnail.jp

Efficient MAC in cognitive radio systems: A game-theoretic approach

In this paper, we study the problem of efficient medium access control (MAC) among cognitive radio devices that are equipped with multiple radios and thus are capable of transmitting simultaneously at different frequencies (channels). We assume that radios contend on each channel using the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. We study two MAC problems: (i) the allocation of the available channels among radios, and (ii) the optimal usage of each allocated channel by the radios occupying it. Both problems are studied in a game-theoretic setting, where devices aim to selfishly maximize their share of the available bandwidth. As for the first problem, we show that the ”price of anarchy" is close to 1, that is, Nash equilibria imply nearly system optimal allocations of the available channels. For the second problem, we design a game such that it admits a unique Nash equilibrium that is is both fair and Pareto-optimal. Furthermore, we propose simple mechanisms that enable selfish cognitive radio devices not only to coordinate efficiently on the available channels but also to optimally use every single allocated channel

QoS-aware distributed spectrum sharing for heterogeneous wireless cognitive networks

Ubiquitous wireless networking calls for efficient dynamic spectrum allocation (DSA) among heterogeneous users with diverse transmission types and bandwidth demands. To meet user-specific quality-of-service (QoS) requirements, the power and spectrum allocated to each user should lie inside a bounded region in order to be meaningful for the intended application. Most existing DSA methods aim at enhancing the total system utility. As such, spectrum wastage may arise when the system-wise optimal allocation falls outside individual users\u27 desired regions for QoS provisioning. The goal of this paper is to develop QoS-aware distributed DSA schemes using game-theoretic approach. We derive DSA solutions that respect QoS and avoid naively boosting or sacrificing some users\u27 utilities to maximize the network spectrum utilization. Specifically, we propose two game-based DSA algorithms: one resorts to proper scaling of the transmission power according to each user\u27s useful utility range, and the other embeds the QoS factor into the utility function used during gaming. To evaluate DSA schemes from a practical QoS perspective, we introduce two new metrics, namely system useful utility and fraction of QoS-satisfied users . Simulations confirm that the proposed DSA techniques outperform existing QoS-blind game models in terms of the spectrum sharing efficiency in heterogeneous networks. Convergence analysis of the proposed QoS-aware DSA algorithms is also provided. © 2007 Elsevier B.V. All rights reserved