Mobility Reduces the Number of Secondary Users in Cognitive Radio Networks
Xinbing Wang, Luoyi Fu, Yingzhe Li, Zizhong Cao, Xiaoying Gan · 2011
In this paper, we study the capacity and delay scaling laws for cognitive radio networks (CRN). The primary network consists of n static, randomly and evenly distributed primary users (PUs), which require high throughput with low delay. The secondary network consists of m = O(n1+δ) randomly and evenly distributed cognitive secondary users (SUs) with δ >; 0, which move in different area according to the hierarchical i.i.d. mobility model. The secondary network is carefully designed to support the primary network, so that PUs may achieve near-optimal performance in both capacity and delay aspects. Then by utilizing hierarchical cooperation among SUs with different mobility, a new hierarchical relay algorithm is proposed to improve the delay performance extensively. Under optimal condition, this algorithm may provide Ω(n-δ') per-node throughput and O(nδ") average delay for PU with δ', δ" >; 0, and significantly improve the performance of SU at the same time.