Asynchronous Multi-Channel MAC Protocol

The so-called Internet of Things (IoT) aims at connecting every single object to the Internet with the purpose to automate every aspect of daily life. The IoT relies heavily on wireless low-power and lossy networks (LLNs) that collect information from the physical world and send the measurements to data aggregation and processing nodes. Most LLNs operate in the non-licensed industrial, scientific, and medical radio band, which is shared by a considerable number of systems. Coexisting wireless systems cause interference to each other, limiting their achievable performance. Multichannel communications enable frequency diversity, which in turn provides robustness against interference as well as increased network capacity. There is a considerable interest in multichannel medium access control (MAC) protocols for LLNs, including an evolving standard for the MAC layer of LLNs. In this paper, we review the latest advances in the topic and introduce a new classification framework for multichannel MAC protocols for LLNs. While our framework builds on previous review and classification studies, it adds aspects of a MAC protocol that reflect its interactions with the surrounding network stack. Seeing the resource constraints of the LLN devices, the study of such interactions—which is missing in prior classification efforts—can be the key for improving future designs. Relevant protocols published since 2006 are discussed and classified using the presented framework, including the recent multichannel MAC protocols for LLNs, such as the latest version of the IEEE 802.15.4 standard for time slotted channel hopping.

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.

A cooperative CDMA-based multi-channel MAC protocol for mobile ad hoc networks

Medium access control (MAC) protocols have been studied under different contexts for several years now. In all these MAC protocols, nodes make independent decisions on when to transmit a packet and when to back-off from transmission. In this paper, we introduce the notion of node cooperation into MAC protocols. Cooperation adds a new degree of freedom which has not been explored before. Specifically we study the design of cooperative MAC protocols in an environment where each node is equipped with a single transceiver and has multiple channels to choose from. Nodes cooperate by helping each other select a free channel to use. We show that this simple idea of cooperation has several qualitative and quantitative advantages. Our cooperative asynchronous multi-channel MAC protocol (CAM-MAC) is extremely simple to implement and, unlike other multi-channel MAC protocols, is naturally asynchronous. We conduct extensive simulation experiments. We first compare CAM-MAC with IEEE 802.11b and a version of CAM-MAC with the cooperation element removed. We use this to show the value of cooperation. Our results show significant improvement in terms of number of collisions and throughput for CAM-MAC. We also compare our protocol with MMAC and SSCH and show that CAM-MAC significantly outperforms both of them.

Cognitive Radio (CR) exploits underutilized licensed spectrums to improve its bandwidth availability. Using CR technology, a node is able to adapt its transmission and reception radio parameters including channel frequency dynamically according to local spectrum availability. For channel access between wireless nodes, a cognitive Medium Access Control (MAC) protocol is necessary to coordinate the CRs. Multi-channel MAC protocol extensions have been proposed in IEEE802.11 to enable a node to operate in multiple channels in order to improve network-wide throughput. These multi-channel MAC protocols have several functions that can be leveraged by cognitive MAC protocols due to their similarities in certain aspects, though the CR has an additional requirement to cope with the existence of licensed users that have higher authority over the channels. Current research in cognitive MAC protocols assumes the availability of a common control channel at all times, which is an approach in the multi-channel MAC protocols. This approach has certain hardware requirements that may not be readily available at CR nodes. Hence, other approached may be necessary. In this paper, various types of multi-channel MAC protocols are reviewed, followed by discussion of their merits and demerits in multi-channel environments. The purpose is to show the additional functionalities and challenges that each multi-channel MAC protocol has to offer and address in order to operate in multihop CR networks. By providing discussion on possible technology leverage from multi-channel to cognitive MAC protocols, we aim to establish a foundation for further research and discussion.

Since cognitive wireless network (CRN) has the characteristic of secondary use, it can enable the device to dynamically access available spectrum without interference to primary users (PUs), which can effectively alleviate contradiction between the lack of spectrum resources and the growing demand for wireless access. However, Medium Access Control (MAC) protocol as CRN core components, can achieve competition access of the licensed spectrum and coordination control, which will maximize spectrum utilization efficiency and network throughput. The contribution of this survey is threefold. First, we analyze the characteristics of the existed multi- channel MAC protocol in CRN; Second, according to the different ways of spectrum access in CRNs, the multi-channel MAC protocols are classified into time-slotted based MAC protocol, control channel based MAC protocol and hybrid MAC protocol, and the paper emphatically analyzed the advantages and disadvantages of these multi-channel MAC protocols; Finally, the paper explores the difficulties and the challenges of multi-channel MAC protocols design in cognitive wireless network.

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.

We propose a cross-layer based multi-channel Medium Access Control (MAC) protocol to maximize the utilization of the leftover spectrum of primary user channels in cognitive radio networks. This protocol integrates the spectrum sensing at Physical layer and the packet scheduling at the MAC layer for mobile ad-hoc networks. With a TDMA-based control channel, we have a scheme to handle collision. Moreover, our scheme is suitable for heterogeneous network with different device capabilities. We formulate the channel allocation problem as a constrained optimization problem and propose strategies to handle channel allocation based on graph theoretic principles, specifically using Weighted Bipartite Graph Matching technique. We name our proposed modeling as Weighted Bipartite Multi-Vertex Matching (WBMM) and describes three different schemes based on this model. We conduct extensive simulation studies to analyze and compare the performance of the proposed strategies.

This paper proposes a novel multi-channel medium access control (MAC) that is based on CSMA/CA mechanism. The objective of this research is to evaluate the possibility of increasing network capacity and addressing collision problem of wireless sensor network comprising of low spec physical hardware. The proposed protocol can be implemented into wireless sensor network platform i.e. MICAz, Tmote-Sky without any additional hardware or firmware. Experiment results show that the proposed protocol can effectively improve the network performance compared with traditional single channel MAC.

Multichannel Medium Access Control (MAC) protocols for IoT can potentially improve network performance. Therefore, a considerable number of such protocols have been proposed in the last decade, ranging from slotted synchronous to contention-based asynchronous multichannel protocols. In this paper two of the most representative multichannel MAC layer protocols are compared: Time-Slotted Channel Hopping (TSCH) using the Orchestra scheduling algorithm, and Energy-Efficient Multichannel MAC (EM-MAC). The performance of these protocols is assessed under different traffic loads and node densities using the standard IPv6 Routing Protocol for Low-Power and Lossy Networks (LLNs), i.e. RPL. The results show the cross-layer interaction between the RPL protocol and the multichannel MAC schemes under study. Moreover, it can be generally appreciated that TSCH/Orchestra performs better in terms of Packet Delivery Ratio (PDR) whereas EM-MAC exhibits lower power consumption. These characteristics reveal the suitability of these protocols for different IoT applications.

<p>CR technology, which is the next-generation wireless communication system, improves the utilization of the overall radio spectrum through dynamic adaptation to local spectrum availability. In CR networks, unlicensed or Secondary Users (SUs) may operate in underutilized spectrum (called white spaces) owned by the licensed or Primary Users (PUs) conditional upon PUs encountering acceptably low interference levels. Ideally, the PUs are oblivious to the presence of the SUs. Context awareness enables an SU to sense and observe its operating environment, which is complex and dynamic in nature; while intelligence enables the SU to learn knowledge, which can be acquired through observing the consequences of its prior action, about its operating environment so that it carries out the appropriate action to achieve optimum network performance in an efficient manner without following a strict and static predefined set of policies. Traditionally, without the application of intelligence, each wireless host adheres to a strict and static predefined set of policies, which may not be optimum in many kinds of operating environment. With the application of intelligence, the knowledge changes in line with the dynamic operating environment. This thesis investigates the application of an artificial intelligence approach called reinforcement learning to achieve context awareness and intelligence in order to enable the SUs to sense and utilize the high quality white spaces. To date, the research focus of the CR research community has been primarily on the physical layer of the open system interconnection model. The research into the data link layer is still in its infancy, and our research work focusing on this layer has been pioneering in this field and has attacted considerable international interest. There are four major outcomes in this thesis. Firstly, various types of multi-channel medium access control protocols are reviewed, followed by discussion of their merits and demerits. The purpose is to show the additional functionalities and challenges that each multi-channel medium access control protocol has to offer and address in order to operate in CR networks. Secondly, a novel cross-layer based quality of service architecture called C2net for CR networks is proposed to provide service prioritization and tackle the issues associated with CR networks. Thirdly, reinforcement learning is applied to pursue context awareness and intelligence in both centralized and distributed CR networks. Analysis and simulation results show that reinforcement learning is a promising mechanism to achieve context awareness and intelligence. Fourthly, the versatile reinforcement learning approach is applied in various schemes for performance enhancement in CR networks.</p>

Directional antennas in Ad hoc networks offer more benefits than the traditional antennas with omni-directional mode. With directional antennas, it can increase the spatial reuse of the wireless channel. A higher gain of directional antennas makes terminals a further transmission range and fewer hops to the destination. This paper presents the design, implementation and simulation results of a multi-channel Medium Access Control (MAC) protocols for dense Vehicular Ad hoc Networks using directional antennas with local beam tables. Numeric results show that our protocol performs better than the existing multichannel protocols in vehicular environment.

In this paper, we propose and investigate an efficient multichannel Medium Access Control (MAC) protocol for Cognitive Radio Ad Hoc Networks (CRAHNs). The proposed protocol supports Secondary Users' (SUs) dynamic utilization of the licensed channel of Primary Users (PUs) to enable the SUs' performance of a multichannel data transmission simultaneously and without interfering with each other. The proposed protocol can be cooperative or non-cooperative. The cooperative protocol scheme enables a SU to sense PU's presence independently in a multichannel architecture and then broadcasts the report to its neighbors in a proactive fashion. The performance of the cooperative and non-cooperative protocol schemes is simulated and compared. The performance demonstration focuses not only on the SU performance but also on the PU's performance with an Ad hoc On-demand Distance Vector (AODV) routing protocol. The simulation results show that the proposed protocol enhances the network utilizations in general and that the cooperative scheme significantly enhances the Packet Delivery Ratio (PDR) and decreases the end-to-end delay of SUs with high traffic PU connections.

Communication in the underwater wireless sensor networks (UWSNs) faces many challenges due to the acoustic wave characteristics. Acoustic wave has very limited bandwidth, long propagation delay, high bit error rate (BER), and unreliable communication compared to the radio wave. Therefore, media access control (MAC) protocols proposed in terrestrial wireless sensor networks (TWSNs) cannot be implemented underwater as TWSNs rely on radio waves and enables multiple transmissions at a time without causing a collision. Besides, underwater nodes operate in a half-duplex mode and only allows one transmission at a time. Designing an efficient MAC protocol for underwater time-sensitive applications, such as the oil/gas pipeline and climate change prediction applications is necessary. While each application has its own requirements, the software-based approach promises great enhancements to meet more than one application's requirements. The software-based approach allows us to reconfigure the variables through a software without additional hardware requirements. To address the above issues, this paper proposes a software-based MAC protocol that utilizes optical and acoustic wave for communication and allows multiple transmissions at a time in different directions. This study aims to maximize throughput, packet delivery ratio (PDR), network utilization while minimizing latency.

This paper presents a new CDMA-based multichannel medium access control protocol for ad hoc networks, which is named as two-phase coding multichannel protocol with power control. The first phase code is used to broaden the area reuse and the second phase code is employed to distinguish between different nodes in one specific area. This algorithm efficiently eliminates hidden terminal and exposed terminal problems during data transmission and greatly increases the throughput. In addition, it has good scalability and can be easily accomplished with GPS. Although many multichannel MAC protocols adopting CDMA techniques have been presented, few have addressed the near-far problem. We incorporate power control in our algorithm and reduce the near-far interference. The implementation of two-phase coding with power control is discussed, and the primary simulation result demonstrates that the proposed protocol offers better performance.