An Adaptive Common Control Channel MAC with Transmission Opportunity in IEEE 802.11ac

Spectral utilization is a major challenge in wireless ad hoc networks due in part to using limited network resources. For ad hoc networks, the bandwidth is shared among stations that can transmit data at any point in time. It  is important to maximize the throughput to enhance the network service. In this paper, we propose an adaptive multi-channel access with transmission opportunity protocol for multi-channel ad hoc networks, called AMCA-TXOP. For the purpose of coordination, the proposed protocol uses an adaptive common control channel over which the stations negotiate their channel selection based on the entire available bandwidth and then switch to the negotiated channel. AMCA-TXOP requires a single radio interface so that each station can listen to the control channel, which can overhear all agreements made by the other stations. This allows parallel transmission to multiple stations over various channels, prioritizing data traffic to achieve the quality-of-service requirements. The proposed approach can work with the 802.11ac protocol, which has expanded the bandwidth to 160 MHz by channel bonding. Simulations were conducted to demonstrate the throughput gains that can be achieved using the AMCA-TXOP protocol. Moreover, we compared our protocol with  the IEEE 802.11ac standard protocols.

Multichannel preamble sampling MAC protocol for wireless sensor networks

In this article, a multichannel preamble sampling MAC protocol, MCPS, especially tailored for wireless sensor networks, is proposed and thoroughly evaluated. MCPS is a low-power MAC protocol operating on multichannel using carrier sensing for collision avoidance. Specifically, MCPS exploits all the non-overlapping channels provided by IEEE 802.15.4 physical layer. Basically, MCPS uses one dedicated common control channel to wake up an intended receiver using a preamble sampling technique. However, data transmission takes place in a dedicated data channel. Indeed, MCPS allocates to every pair of sensor nodes a unique data channel that aims at being 2-hop conflict free. Hence, the probability of collision is highly reduced and even completely mitigated in some scenarios. Moreover, MCPS allows each sensor node to dynamically adjust its transmission power when sending strobed preamble or periodically generated data. Indeed, for each possible distance separating a pair of communicating nodes, MCPS adapts the appropriate transmission power and selects the appropriate data channel. Using multiple channels, MCPS allows multiple simultaneous data communications along with handshaking on the common control channel, hence reducing the end-to-end delay and improving the throughput while being energy efficient. MCPS has been implemented using OMNET++ simulator under INET framework, on top of the IEEE 802.15.4 physical layer, which was improved to support the multichannel communication. The authors compare the performance of MCPS with McMAC and X-MAC. Simulation results show that MCPS greatly improves the network performance especially in terms of throughput, waiting time, end-to-end delay, and energy per bit.