A Review of Cross-layer Design in Dynamic Spectrum Access for Cognitive Radio Networks

Cognitive Radio (CR) is an intelligent radio that can dynamically access the radio spectrum. Secondary users in Cognitive Radio Network (CRN) can access the licensed spectrum without causing harmful interference to primary users. The performance of cognitive radio networking functionalities depends on the properties of the spectrum band in use. This necessitates a crosslayer design in the entire CR networking protocol stack. Current researches are investigating different techniques of using cognitive radio to reuse more locally unused spectrums to increase the total system capacity. This paper provides a comprehensive survey of cross-layer design in cognitive radio network. The cross-layer design approach jointly considers the functions of the layers to maximize the performance of CR networks.</p

Cross-layer design for cognitive radios with joint AMC and ARQ under delay QoS constraint

In order to guarantee dual quality-of-service (QoS) measures, namely, packet error rate (PER) and delay constraint, in a spectrum-sharing channel, we propose a cross-layer resource allocation approach in this paper. In particular, we assume an underlay cognitive radio scenario, in which, a secondary user (SU) is granted access to the spectrum as long as its average interference power, imposed on the primary-user (PU) receiver is below a predefined threshold. The SU employs adaptive modulation and coding (AMC) at the physical layer and automatic repeat request (ARQ) at the link-layer. An adaptive power and rate allocation scheme is proposed for the SU transmitter to meet both the PER requirement and the statistical delay constraints. To this end, we use the effective capacity concept and obtain closed-form expressions for the power allocation and capacity of the SU's link in Nakagami-m fading channels