Multichannel MAC protocol with dynamic backoff contention for distributed cognitive radio networks

Abstract

Multiuser access is a critical issue in distributed cognitive radio networks (DCRNs), as the collisions among the competing secondary users (SUs) may decrease the network throughput significantly. In order to reduce the collisions, we propose a dynamic backoff algorithm to find an optimal backoff contention window to maximize the network throughput and reduce the channel access delay. Based on the proposed algorithm, a multichannel medium access control (MAC) protocol with dynamic backoff contention (MMAC-DB) is designed. In this protocol, the time duration of each channel is divided into four phases: idle, sensing-sharing, contention, and data transmission. The dynamic backoff algorithm is implemented in the contention phase. Moreover, a duration tradeoff is made between the data transmission phase and the contention phase. The effectiveness of the proposed protocol is examined by extensive simulations, which shows that the proposed protocol can enhance the throughput and reduce the channel access delay.

Receiver-prioritized Next Transmission in Multichannel MAC Protocol for Wireless Ad-hoc Networks

“…In CARMA-MC protocol [5], each node defines its own default channel by using its assigned unique value like network address, and the node which wants to transmit a data frame to the neighbor node switches from its own default channel to the receiver's default channel, and then transmits the data frame to the receiver node. In some multichannel protocols such as MMAC protocol [6], EFCM protocol [7] and CR-MAC protocol [8], the time axis is divided into fixed time slots, and each time slot is divided into a channel negotiation period and a data frame transmission period. At first each node which wants to transmit a data frame reserves a data channel by negotiating with the receiver node, then they switch to the data channel and transmit/receive the data frame.…”