QP-CSMA-CA: A modified CSMA-CA-based cognitive channel access mechanism with testbed implementation

Abstract

In this paper, a modified carrier sense multiple access-collision avoidance (CSMA-CA) mechanism, termed as quiet period-CSMA-CA (QP-CSMA-CA) is proposed, for the purposes of coexistence in a cognitive networking set-up with secondary clients that seek access using 802.11. In work to date, dedicated quiet periods have been defined for this purpose, as a synchronized duration wherein all clients are prohibited from uplink transmissions; this interval is intended for sensing channel status so as to detect out-of-network transmissions. However, such dedicated periods may adversely impact system throughput as the price for coexistence. In QP-CSMA-CA, the Wi-Fi nodes perform channel sensing during an extended back-off phase; thereby bypassing the need for separate dedicated sensing interval. The proposed QP-CSMA-CA protocol is implemented on the universal software radio peripheral (USRP)-based software defined radio platform and configured in a small network for measuring throughput and latency. Experimental and simulation results show the efficacy of the proposed algorithm over the dedicated sensing-based mechanism when compared in terms of system throughput and medium access latency.

An Enhanced Reliable Access Scheme for Massive IoT Applications in Ubiquitous IoT Systems

“…In the related research of channel access schemes based on random contention, Ghosh and others [27] designed an improved CSMA access scheme for wireless ad hoc networks. The scheme uses the idea of channel reservation to divide the channel into several independent parts.…”