###### Abstract  
Medium access control (MAC) protocols in ad hoc networks have evolved from single-channel independent transmission mechanisms to multi-channel concurrent mechanisms to efficiently manage the demands placed on modern networks. The primary aim of this study is to compare the performance of popular multi-channel MAC (MMAC) protocols under saturated network traffic conditions and propose improvements to the protocols under these conditions. A novel, dynamically adaptive MMAC protocol was devised to take advantage of the performance capabilities of the evaluated protocols in changing wireless ad hoc network conditions. A simulation of the familiar MAC protocols was developed based on a validated simulation of the IEEE 802.11 standard. Further, the behaviors and performances of these protocols are compared against the proposed MMAC protocols with a varying number of ad hoc stations and concurrent wireless channels in terms of throughput, Jain's fairness index, and channel access delay. The results show that the proposed MMAC protocol, labeled E-SA-MMAC, outperforms the existing protocols in throughput by up to 11.9% under a constrained number of channels and in channel access delays by up to 18.3%. It can be asserted from these observations that the proposed approach provides performance benefits against its peers under saturated traffic conditions and other factors, such as the number of available wireless channels, and is suitable for dynamic ad hoc network deployments. medium access control; multi-channel MAC protocol; ad hoc networks; adaptive MMAC; wireless communication +
Footnote †: journal: Accepted: 7 November 2022
The focus of this study is on ad hoc network characteristic-decentralized topologies with nodes communicating as peers between themselves. In an ad hoc network, a single channel needs to be shared by several nodes, and the medium access control (MAC) protocol [8; 9; 10] is responsible for the coordination between nodes. With advances in technological development, the physical (PHY) layer is vastly improved with higher data rates and a better quality of service (QoS) [11; 12; 13; 14]. Although IEEE 802.11 allows the use of multiple channels, IEEE 802.11 MAC protocol is used for handling channel access in a single channel only. Moreover, it is found to be inefficient due to multi-channel hidden terminal problems, which will be discussed later. The approaches to MMAC protocols have been classified as follows [15; 16; 17]:  
* Dedicated control channel;
* Split phase;
* Common hopping;
* Parallel rendezvous. The dedicated control channel approach splits the spectrum into one control channel and N-1 data channels where each node has two radio interfaces to operate in the control and data channel. Nodes are aware of the neighbor transmissions and no synchronization is needed. Due to the common control channel, no multi-channel hidden problem exists. The split phase, as the name suggests, divides the time into two phases--the contention and the data transfer phase. These two phases are fixed and always take place periodically. During the contention phase, all nodes listen to the common control channel, and those that succeed exchange data frames in the data exchange phase. Although the multi-channel hidden terminal is solved and tight global synchronization is needed. In common hopping, nodes follow a hopping sequence. The nodes that want to communicate stop at a frequency and communicate and then rendezvous with the hopping sequence. Hopping spreads the control signal and congestion is reduced on a particular channel, but tight global synchronization is also needed in this approach. A parallel rendezvous is similar to the common hopping approach but multiple handshakes occur simultaneously on all free channels. Although the parallelism of MMAC protocols significantly improves throughput and reduce channel access delay compared to a single-channel approach [15], there are issues that need to be addressed.