Admission Control and Interference Management in Dynamic Spectrum Access Networks
- PDF / 727,044 Bytes
- 12 Pages / 600.05 x 792 pts Page_size
- 56 Downloads / 221 Views
Research Article Admission Control and Interference Management in Dynamic Spectrum Access Networks Jorge Martinez-Bauset, Vicent Pla, M. Jose Domenech-Benlloch, and Diego Pacheco-Paramo Departamento de Comunicaciones, Universidad Polit´ecnica de Valencia (UPV), Camino de Vera s/n, 46022 Valencia, Spain Correspondence should be addressed to Jorge Martinez-Bauset, [email protected] Received 6 October 2009; Revised 16 February 2010; Accepted 9 May 2010 Academic Editor: Gian Luigi Ferrari Copyright © 2010 Jorge Martinez-Bauset et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We study two important aspects to make dynamic spectrum access work in practice: the admission policy of secondary users (SUs) to achieve a certain degree of quality of service and the management of the interference caused by SUs to primary users (PUs). In order to limit the forced termination probability of SUs, we evaluate the Fractional Guard Channel reservation scheme to give priority to spectrum handovers over new arrivals. We show that, contrary to what has been proposed, the throughput of SUs cannot be maximized by configuring the reservation parameter. We also study the interference caused by SUs to PUs. We propose and evaluate different mechanisms to reduce the interference, which are based on simple spectrum access algorithms for both PUs and SUs and channel repacking algorithms for SUs. Numerical results show that the reduction can be of one order of magnitude or more with respect to the random access case. Finally, we propose an adaptive admission control scheme that is able to limit simultaneously the forced termination probability of SUs and what we define as the probability of interference. Our scheme does not require any configuration parameters beyond the probability objectives. Besides, it is simple to implement and it can operate with any arrival process and distribution of the session duration.
1. Introduction Cognitive radio networks are envisaged as the key technology to realize dynamic spectrum access (DSA). Such paradigm shift in wireless communications aims at solving the scarcity of radio spectrum [1–4]. The DSA concept proposes to boost spectrum utilization by allowing DSA users (SUs) to access the licensed wireless channel in an opportunistic manner so that interference to licensed users (PUs) is kept to a minimum. The idea of DSA is undoubtedly compelling and its realization will induce a huge advance in wireless communications. However, there are many challenges and open questions that have to be addressed before DSA networks become practically realizable [5, 6]. To fulfill the requirement of minimum interference to PUs, a SU with an ongoing communication must vacate the channel when a licensed user is detected. The SU may switch to a different unused spectrum band which is referred to as spectrum mobility or spectrum handover (SH). If no avail
Data Loading...
