Abstract
Abstract Consider an infrastructure-based multi-band cognitive radio network (CRN) where secondary users (SUs) opportunistically access a set of sub-carriers when sensed as idle. The carrier sensing threshold which affects the access opportunities of SUs is conventionally regarded as static and treated independently from the resource allocation in the model. In this article, we study jointly the optimization of detection threshold and resource allocation with the goal of maximizing the total downlink capacity of SUs in such CRNs. The optimization problem is formulated considering three sets of variables, i.e., detection threshold, sub-carrier assignment and power allocation, with constraints on the PUs’ rate loss and the power budget of the CR base station. Two schemes, referred to as offline and online algorithms respectively, are proposed to solve the optimization problem. While the offline algorithm finds the global optimal solution with high complexity, the online algorithm provides a close-to-optimal solution with much lower complexity and realtime capability. The performance of the proposed schemes is evaluated by extensive simulations and compared with the conventional static threshold selection algorithm specified in the IEEE 802.22 standard.
Highlights
The rapid development of new wireless devices and services has lead to a growing demand for radio spectrum, making the problem of spectrum shortage more serious
In a cognitive radio (CR) network (CRN), secondary users (SUs) may coexist with primary users (PUs) of a primary radio network (PRN) in two ways: spectrum underlay which means that secondary (unlicensed) users (SUs) may operate under the noise floor of primary (licensed) users (PUs), or spectrum overlay which allows SUs operate only when the spectrum allocated to PUs
We study the joint optimization of detection threshold and sub-carrier assignment and power allocation (SAPA) scheme with the goal of maximizing the total downlink capacity of SUs in such an infrastructure-based CRN
Summary
The rapid development of new wireless devices and services has lead to a growing demand for radio spectrum, making the problem of spectrum shortage more serious. Little work has been done on joint optimization of detection threshold and resource allocation in multi-band CRNs. In [17], a joint optimal power allocation (OPA) and detection threshold scheme is proposed to maximize SUs’ capacity in spectrum sharing CRNs. In [18], the sensing threshold is determined to optimize two different sensing objectives: weighted network total capacity and the more traditional Bayesian cost, by exploiting location information. In [18], the sensing threshold is determined to optimize two different sensing objectives: weighted network total capacity and the more traditional Bayesian cost, by exploiting location information These two schemes are not designed for multi-band CRNs. In [19], a joint cross-layer scheduling and sensing framework is designed to optimize average weighted SUs’ capacity, by adapting SAPA across SUs (under a constraint on average interference to PUs). This framework assumes fixed sensing parameters such as the MDP and the FAP when optimizing SUs’ capacity
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