Performance Analysis of Slotted Secondary Transmission with Adaptive Modulation under Interweave Cognitive Radio Implementation

TL;DR

This paper evaluates the delay and throughput of secondary transmissions in cognitive radio using a slotted protocol, employing Markov models to analyze performance and collision probabilities under interweave spectrum access.

Contribution

It introduces a discrete-time Markov model for slotted secondary transmission and derives closed-form collision probability and extended delivery time distributions.

Findings

Derived closed-form collision probability expressions.

Analyzed queuing delay and throughput for small packets.

Validated models with numerical simulations.

Abstract

In cognitive radio communication, unlicensed secondary user (SU) can access under-utilized spectrum of the licensed primary user (PU) opportunistically for emerging wireless applications. With interweave implementation, SU has to perform spectrum sensing on the target frequency band and waits for transmission if PU occupies the channel. This waiting time results in extra delay for secondary transmission. In this paper, the delay and throughput performance of secondary packet transmission is evaluated with slotted transmission protocol. We propose a discrete-time Markov model to characterize secondary slotted transmission process. Close-form solution of collision probability is obtained. We then carry out the queuing delay and throughput analysis based on a two-dimensional-finite-state Markov chain for small-size packet transmission. For large-size packets, the distribution function of extended delivery time for secondary packet transmission is also derived. Selected numerical results are presented to illustrate the mathematical formulas and to validate our research results.