Joint Admission Control, Channel Assignment and QoS Routing for Coverage Optimization in Multi-Hop Cognitive Radio Cellular Networks

Abstract

In recent years, cognitive radio technology (CR) has been proposed to allow unlicensed secondary users (SUs) to opportunistically access the channels unused by primary users. As a result, there is a lot of recent interests on studying cognitive radio cellular networks (CogCells) that can support both PUs and SUs. Due to the limited transmission range of SUs, in this work we consider supporting Multi-hop infrastructure-based secondary systems (SSs), where SUs can communicate with the BS over multiple hops. The use of SSs improves the reliability and coverage compared to its single-hop counterpart. In addition, SUs are allowed to access multiple channels, which helps to increase transmission reliability and coverage and relieve interference at PUs. To enable multi-hop secondary transmissions, it is also important to support efficient routing. In CogCells, efficient admission control, channel assignment and routing is crucial for the coverage optimization of SSs and to ensure the QoS requirements in CogCells.In this paper, we mathematically formulate the problem of joint admission control, channel assignment and QoS routing to maximize the coverage of SUs in a CogCell system that supports multi-hop secondary transmissions, taking into account the interference constraints and QoS requirements from the PUs and admitted SUs. To our best knowledge, this is the first study that attempts to optimize the coverage of SUs in multi-hop CogCells with the concurrent support of the above three important procedures. We show that the problem is NP-hard and propose three different algorithms to solve the coverage optimization problem and give the theoretical analyses of its performances in terms of approximation ratio to the optimum. Our solutions include a greedy heuristic approximation scheme, an algorithm that can provide exact solution, and a new approximation solution with a poly-logarithmic approximation ratio guarantee, e.g., the performance of our algorithm is within a poly-logarithmic factor of that of any optimal algorithm for the problem.

Latency optimal broadcasting in noisy wireless mesh networks

“…A new randomized, diameter-linear algorithm in the noisy radio network model had been proposed with running time Θ(D + log n log log n(log n + log 1 δ )) to complete the single-message broadcasting with a probability of at least 1 − δ. The work in [6] also described how to extend two robust single-message broadcasting schemes to the multi-message scenario, achieving throughputs of Ω Latency-efficient communication schemes under the traditional physical interference model had also been studied extensively in [21], [3], [26], [27], [29], [30]. Very recently, Xin and Xia proposed a "noisy" physical interference model and showed some interesting latency-efficient gossiping schemes in [31].…”

Multi‐interface cognitive radio for enhanced routing in multi‐hop cellular networks

“…Here, the SUs that are able to make local detection decisions either directly report their 1‐bit decision to the CR BS or they forward their decision to other favorable SUs based on the states of their reporting channels. Xin et al proposed a joint admission control, channel assignment, and quality of service (QoS) routing solution that maximize the coverage of SUs in a CR cellular network, which supports multi‐hop secondary transmissions.…”