Asynchronous Session Reservation Multi-Channel MAC for Ad Hoc Networks

In recent years, multi-channel MACs have attracted considerable attention in wireless networking research. Motivation for research into multi-channel MACs is their potential to increase the capacity of wireless ad hoc networks by exploiting multiple orthogonal frequency bands. This potential has been confirmed by several simulation studies that reported promising results for multi-channel MACs. However, the analytical performance of these protocols is not well understood. In this work, we present an analytical framework for modeling the performance multi-channel MACs in multi-hop networks. We employ our framework to investigate the performance of three representative multi channel MACs: Asynchronous Multichannel Coordination Protocol (AMCP), Multi-Channel MAC (MMAC), and Slotted Seeded Channel Hopping (SSCH). The important findings of our analysis are: (1) SSCH outperforms AMCP and MMAC in both 802.11b and 802.11a scenario, (2) AMCP performs worse than MMAC in 802.11b because the overhead of AMCP's control channel is higher than that of MMAC's control interval, and (3) the overhead of AMCP's control channel becomes negligible in an 802.11a scenario and is outweighed by that of MMAC's control interval. For this reason, AMCP delivers better performance than MMAC in 802.11a scenario.

In multi-channel wireless ad-hoc network, the nodes need to negotiate the channel reservation. Preparing the control channel is one of the strategies for the channel reservation. When the control channel congests due to frame collisions, the control channel is bottleneck for obtaining high throughput. This paper proposes a MAC protocol for multi-channel wireless ad-hoc network for frame collision avoidance on the control channel. The proposed protocol requires only one transceiver in each node, no time-synchronization mechanism among nodes, and few overheads. In the protocol, the node negotiates the channel using the RTS/CTS handshake. The Pulse/Tone exchanges are applied prior to the RTS/CTS handshake for RTS-frame collision avoidance. Additionally, the exposed node problem due to Pulse/Tone exchange is also mitigated, because of the good compatibility between multi-channels and the Pulse/Tone exchanges. It is shown from simulation results that the proposed protocol achieves higher throughput than the previous protocols, especially for heavy offered load condition.

In multi-channel WLANs, the MAC protocol allocates a channel to each transmission pair while avoiding interference. In the channel allocation phase, if the MAC protocol allocates one channel iteratively to multiple narrowly spaced transmission pairs, both channel utilization and network throughput can be improved. However, such an approach leads to traffic overload; thus, if a transmission takes place over a transmission channel, the number of terminals that can receive the transmission decreases. B-MAC, a multi-channel MAC protocol designed for broadcast, starts a new broadcast transmission after waiting for a certain period of time; however, this waiting time increases the transmission overhead and degrades channel utilization. In this paper, we propose CA-BMAC, a new multi-channel MAC protocol that reduces the waiting time associated with B-MAC, and thus, the transmission overhead. Performance evaluations of the proposed protocol clarify its advantages over B-MAC.

Recent research has demonstrated the feasibility of full-duplex (FD) communication over the same frequency channel. This capability, facilitated by new self-interference suppression techniques, has great potential to increase the network capacity. However, exploiting FD in the context of a multi-user, multi-channel network is still being debated. This paper focuses on the channel access issue and presents a novel multi-channel MAC (MMAC) protocol for wireless ad hoc networks with FD and orthogonal frequency-division multiple access (OFDMA) capabilities. Through these capabilities, a node can simultaneously carry out multiple transmissions and/or receptions over the same or different channels. In our MMAC protocol, a pair of nodes negotiate data channels, transmission rates, transmission powers, and transmission modes (e.g., FD or half-duplex) in a distributed manner so that their spectral usages are minimized while their rate demands are still met. Extensive ns3 simulations show that our MMAC protocol increases the end-to-end network goodput by up to 150% and decreases the end-to-end delay by up to 300% compared with an OFDMA-based protocol without FD.

In high diversity node situation, single-channel MAC protocols suffer from many collisions. To solve this problem, the research of multichannel MAC protocol has become a hotspot. And the cyclic quorum-based multichannel (CQM) MAC protocol outperformed others owing to its high frequency utilization. In addition, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQM MAC protocol, a Markov chain model, which combines the channel hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The metrics (throughput and average packet transmission delay) are calculated in performance analysis, with respect to node number, packet rate, channel slot length and channel number. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm (BSA). Finally, the Markov chain model and saturation bound are verified by Qualnet platform. And the simulation results show that the analytic and simulation results match very well.

Recently, many MAC protocols have been proposed for effective communication in the single transceiver multi-channel environment. In these MAC protocols, however, the multi-channel hidden terminal problem degrades the throughput of the communication systems. In order to mitigate the effects of the multi-channel hidden terminals, two MAC protocols have been proposed: cooperative asynchronous multi-channel MAC (CAM-MAC), where neighbouring terminals inform a sender of its bad channel selection and virtual topology MAC (VT-MAC), where redundant channel usage information is reduced by considering the network topology. However, these MAC protocols mainly focus on avoiding bad channel selections by the sender, and not on increasing good channel selections (concurrent transmissions). Therefore, in this paper, to further improve throughput performance by concurrent transmissions, we propose new multi-channel MAC protocols in which neighbour terminals of a sender recommend a better transmission channel prior to the data transmission. The performance evaluations verify that the proposed MAC protocol effectively improves the throughput performance when compared to existing MAC protocols, especially when the channel negotiation process induces the larger overhead at the short data transmission.

This paper focuses on the capacity of wireless ad hoc networks and analyzes the effect of key factors viz. network size, traffic patterns and detailed local radio interactions on the capacity of such networks. The capacity is evaluated with several different network layouts and traffic patterns through simulations. To demonstrate the impact of these factors, the capacity evaluation starts with a simple case of a chain of evenly spaced nodes in a network environment and progresses to a network with random traffic and randomly spaced nodes. Initially, capacity of static nodes is evaluated for various network layouts and traffic patterns. Since, in most scenarios, nodes do not travel significant distances during packet transmissions. As an enhancement, mobility of nodes is introduced into the network scenario and the performance is again evaluated. The simulations are carried out using OPNET modeler and the results obtained are presented in this report. The results are analyzed to understand the impact of these factors on the capacity and consequently suggest measures to increase the same. This work shows that the achievable capacity of ad hoc network depends on network size, traffic pattern and mobility. In a single cell topology, it is found that there is a 50% reduction in network throughput, if the node size increases from 2 to 10 nodes, whereas there is a 74% reduction in the throughput for chain topology for the same increase in node size. In a lattice topology with horizontal traffic, there is a 46 % reduction in network throughput when the lattice size increases from 4X4 to 5x5.The same percentage of reduction is observed when both horizontal and network traffic is introduced. In a random network topology with random traffic, there is an 80 % reduction in network throughput when the node size increases from 150 to 750 nodes. However, for the same scenario with the introduction of mobility to the nodes, a slight improvement is achieved with an overall 75% reduction in network throughput.

Existing multi-channel Medium Access Control (MAC) protocols have been demonstrated to significantly increase wireless network performance compared to single channel MAC protocols. Traditionally, the channelization structure in IEEE 802.11 based wireless networks is pre-configured, and the entire available spectrum is divided into subchannels and equal channel widths. In contrast, this paper presents a Traffic-Aware Channelization MAC (TAC-MAC) protocol for wireless ad hoc networks, where each node is equipped with a single half duplex transceiver. TAC-MAC works in a distributed, fine-grained manner, which dynamically divides variable-width subchannels and allocates subchannel width based on the Orthogonal Frequency Division Multiplexing (OFDM) technique according to the traffic demands of nodes. Simulations show that the TAC-MAC can significantly improve network throughput and reduce packet delay compared with both fixed-width multi-channel MAC and single channel 802.11 protocols, which illustrates a new paradigm for high-efficient multi-channel MAC design in wireless ad hoc networks.

In mobile ad-hoc network, some multi-channel MAC protocols utilize multiple channels to reduce the collision of wireless transmission and thus get high throughput. These multi-channel MAC protocols aim at improving the performance of unicast communication, and multicast data are generally transmitted as broadcast. So multicast cannot benefit from the multi-channel technique. This paper proposes a multi-channel media access control protocol for multicast (MCMAC) which uses multi-channel techniques to improve multicast performance. To improve the reliability of MAC layer, we extended a reliable multi-channel MAC protocol for multicast (RMCMAC) based on MCMAC. Taking ODMRP [S.-J. Lee et al., 2000] as an example of multicast routing protocols, we evaluate the multicast performance of MCMAC and RMCMAC for ad hoc networks via detailed simulation.

Traditional IEEE 802.11-based networks use only a single channel to ensure connectivity; however, multi-channel capability is available to provide higher network throughput by allowing simultaneous multiple transmissions that do not interfere with each other. The use of multiple channels raises several new challenges: mainly finding the receiver, scheduling the next transmission, balancing the load among channels, and dealing with multi-channel hidden terminals. This paper proposes a novel and efficient, asynchronous multi-channel medium-access control (MAC) protocol using a single transceiver. The key technique is that the proposed protocol separates searching and scheduling processes where searching users switch channels faster than regular users. Simulation results indicate that the proposed protocol achieves up to 14.10 Mbps network throughput, whereas the IEEE 802.11 MAC protocol, with a single channel, provides only 4.35 Mbps in the best case when three orthogonal channels with an 11- Mbps data rate are available

Proposal of Receiver Initiated MAC Protocol for WSN in urban environment using IoT

Multichannel media access control (MAC) protocols can increase wireless network capacities. The rendezvous problem is the most frequently encountered challenge in developing multichannel MAC protocols. Some studies have assumed that each device is equipped with one additional antenna; however, this increases the hardware cost. Other studies have divided the timeline of each channel into several beacon intervals. All stations are awake simultaneously on a predefined channel to enable rendezvous opportunities; however, this leads to low bandwidth utilization. This paper presents an efficient staggered multichannel MAC protocol (SMC-MAC) for ad hoc networks. By using a single antenna, the proposed SMC-MAC applies a staggered channel model with a home channel concept for exploiting multichannel bandwidth resources. Performance results reveal that the proposed SMC-MAC outperforms existing multichannel MAC protocols in terms of network throughput, control packet collision ratio, packet delay time, packet discarding, packet loss ratio, control overhead, and robustness.

Using multi-channel MAC protocols in mobile ad hoc networks (MANETs) is a promising way to improve the through-put performance. Channel assignment, which directly determines the efficiency of the frequency utilization, is the critical part of multi-channel schemes. Current 802.11-like schemes of multi-channel MAC do not efficiently use the multiple channels due to the overhead caused by channel assignment. Moreover, the control channel saturation problem limits the number of channels of these previous schemes. In this paper, we propose a new scheme called SAM-MAC (Self-Adjustable Multi-channel MAC), which features with one common channel and two half-duplex transceivers for each node. A method called self-adjustment is used to reassign the channels and balance the traffic on different channels. Due to less contention in common channel and smaller channel assignment overhead, this scheme increases the throughput compared with previous approaches. Control channels are free from saturation problem and can furthermore be used for data transmission.

CogMOR-MAC: A cognitive multi-channel opportunistic reservation MAC for multi-UAVs ad hoc networks

Ultra wide band (UWB) technology is a wireless communication technology which has a lot of characters, such as low cost and power consumption, simple structure, precise location ability, high space capability, which is suitable for ad hoc wireless network particularly. Its precise location ability has great help in designing of MAC layer of ad hoc wireless. In this paper, we design a multi-channel MAC protocol of ad hoc wireless network based on location information, mainly introduce the part of channel assignment. The main ideas of this protocol is to assign channel according to the physical location of hosts and we discuss the effect of grid size and simulation shows this protocol has better performance in reduce interference and throughput of networks than static channel assign protocol if we choose proper grid size.