Distributed Medium Access Control Protocol Research Articles

Cooperative optimization techniques in distributed MAC protocols – a survey

Purpose Cross-layer approach in media access control (MAC) layer will address interference and jamming problems. Hybrid distributed MAC can be used for simultaneous voice, data transmissions in wireless sensor network (WSN) and Internet of Things (IoT) applications. Choosing the correct objective function in Nash equilibrium for game theory will address fairness index and resource allocation to the nodes. Game theory optimization for distributed may increase the network performance. The purpose of this study is to survey the various operations that can be carried out using distributive and adaptive MAC protocol. Hill climbing distributed MAC does not need a central coordination system and location-based transmission with neighbor awareness reduces transmission power. Design/methodology/approach Distributed MAC in wireless networks is used to address the challenges like network lifetime, reduced energy consumption and for improving delay performance. In this paper, a survey is made on various cooperative communications in MAC protocols, optimization techniques used to improve MAC performance in various applications and mathematical approaches involved in game theory optimization for MAC protocol. Findings Spatial reuse of channel improved by 3%–29%, and multichannel improves throughput by 8% using distributed MAC protocol. Nash equilibrium is found to perform well, which focuses on energy utility in the network by individual players. Fuzzy logic improves channel selection by 17% and secondary users’ involvement by 8%. Cross-layer approach in MAC layer will address interference and jamming problems. Hybrid distributed MAC can be used for simultaneous voice, data transmissions in WSN and IoT applications. Cross-layer and cooperative communication give energy savings of 27% and reduces hop distance by 4.7%. Choosing the correct objective function in Nash equilibrium for game theory will address fairness index and resource allocation to the nodes. Research limitations/implications Other optimization techniques can be applied for WSN to analyze the performance. Practical implications Game theory optimization for distributed may increase the network performance. Optimal cuckoo search improves throughput by 90% and reduces delay by 91%. Stochastic approaches detect 80% attacks even in 90% malicious nodes. Social implications Channel allocations in centralized or static manner must be based on traffic demands whether dynamic traffic or fluctuated traffic. Usage of multimedia devices also increased which in turn increased the demand for high throughput. Cochannel interference keep on changing or mitigations occur which can be handled by proper resource allocations. Network survival is by efficient usage of valid patis in the network by avoiding transmission failures and time slots’ effective usage. Originality/value Literature survey is carried out to find the methods which give better performance.

A Fairness-Enhanced Intelligent MAC Scheme Using Q-Learning-Based Bidirectional Backoff for Distributed Vehicular Communication Networks

With the increasing attention to front-edge vehicular communication applications, distributed resource allocation is beneficial to the direct communications between vehicle nodes. However, in highly dynamic distributed vehicular networks, quality of service (QoS) of the systems would degrade dramatically because of serious packet collisions in the absence of sufficient link knowledge. Focusing on the fairness optimization, a Q-learning-based collision avoidance (QCA) scheme, which is characterized by an ingenious bidirectional backoff reward model R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">QCA</inf> corresponding to arbitrary backoff stage transitions, has been proposed in an intelligent distributed media access control protocol. In QCA, an intelligent bidirectional backoff agent based on the Markov decision process model can actively motivate each vehicle agent to update itself toward an optimal backoff sub-intervel BSI <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</inf> through either positive or negative bidirectional transition individually, resulting in the distinct fair communication with a proper balance of the resource allocation. According to the reinforcement learning theory, the problem of goodness evaluation on the backoff stage self-selection policy is equal to the problem of maximizing Q function of the vehicle in the current environment. The final decision on BSI <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</inf> related to an optimal contention window range was solved through maximizing the Q value or <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$Q_{\max}$</tex> . The ε-qreedy algorithm was used to keep a reasonable convergence of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$Q_{\max}$</tex> solution. For the fairness evaluation of QCA, four kinds of dynamic impacts on the vehicular networks were investigated: mobility, density, payload size, and data rate with a network simulator NS2. Consequently, QCA can achieve fair communication efficiently and robustly, with advantages of superior Jain's fairness index, relatively high packet delivery ratio, and low time delay.

Collision-free distributed MAC protocol for passive optical intra-rack data center networks

In this paper, we present a distributed medium access control (MAC) protocol and a network architecture suitable for optical intra-rack data center networks (DCNs). The intra-rack communication is performed using passive optical components, over four data wavelength division multiplexing (WDM) channels of either 40 or 100 Gbps each, keeping low power consumption. On the other hand, the inter-rack communication is performed over a separate network through upper layer routers. In this study, we focus only on the intra-rack communication. We introduce an intra-rack DCN (IR-DCN) architecture that works in the optical domain, and two IR-DCN configurations with different total nominal capacity: 160 and 400 Gbps, respectively. Also, we propose a synchronous pre-transmission coordination fair access intra-rack MAC (intra-MAC) protocol taking into account the traffic characteristics and priority classes within existing DCNs. The proposed intra-MAC protocol totally eliminates packet collisions, achieving high performance. Particularly, it reaches high bandwidth utilization even under heavy loads: 90% and 87.5% for the two IR-DCN configurations of 160 and 400 Gbps total capacity, respectively. Also, it achieves low mean end-to-end (e2e) packet delay, lower than 0.25 and 0.12 ms, respectively, providing a reliable solution for time-sensitive DCN traffic. Specifically, simulation results demonstrate that the highest priority traffic experiences e2e delay lower than 1.9 and 1.1 µs, respectively, which is sufficient for the service of the strictest delay requirements of time-sensitive cloud applications. The intra-MAC protocol is decentralized, without the need for a network controller, providing high flexibility. Our IR-DCN proposal is studied in comparison to other currently dominant intra-rack/cluster DCNs, and it achieves from 6% to 57% higher throughput and from 20% to 99% lower e2e delay at high loads. Comparatively, it is on average 80% and 68% more energy and cost efficient, respectively.

A Mean Field Game Analysis of Distributed MAC in Ultra-Dense Multichannel Wireless Networks

This report analyzes the performance of distributed Medium Access Control (MAC) protocols in ultra-dense multichannel wireless networks, where $N$ frequency bands (or channels) are shared by $M=mN$ devices, and devices make decisions to probe and then transmit over available frequency bands. While such a system can be formulated as an $M$ -player Bayesian game, it is often infeasible to compute the Nash equilibria of a large-scale system due to the curse of dimensionality . In this report, we exploit the Mean Field Game (MFG) approach and analyze the system in the large population regime ( $N$ tends to $\infty $ and $m$ is a constant). We consider a distributed and low complexity MAC protocol where each device probes $d/k$ channels by following an exponential clock which ticks with rate $k$ when it has a message to transmit, and optimizes the probing strategy to balance throughput and probing cost. We present a comprehensive analysis from the MFG perspective, including the existence and uniqueness of and convergence to the Mean Field Nash Equilibrium and the price of anarchy with respect to the global optimal solution. Our analysis shows that the price of anarchy is at most one half, but is close to zero when the traffic load or the probing cost is low. Our numerical results confirm our analysis and show that the MFNE is a good approximation of the $M$ -player system. Further, this report demonstrates the novelty of MFG analysis, which can be used to study other distributed MAC protocols in ultra-dense wireless networks.

MPDMAC-SIC: Priority-based distributed low delay MAC with successive interference cancellation for multi-hop industrial wireless networks

Communications in industrial applications such as wireless factory automation demand different timing requirements. Providing timely medium access of the critical traffic and its prioritization over regular traffic at the same time is a significant challenge in industrial wireless networks. Successive Interference Cancellation (SIC) technique is an effective way to decrease access delay by allowing multiple packets reception concurrently. A series of novel Medium Access Control (MAC) protocols are proposed to differentiate access delay for various traffic types or exploit SIC for unique traffic type. Our protocol in this paper (MPDMAC-SIC) is the first priority based distributed MAC protocol that employs SIC to provide low access delay and accommodate different types of traffic for multi-hop industrial wireless networks. Two major contributions of our work are: first, we propose a low delay protocol for priority based multi-hop industrial wireless networks by enabling multiple packet reception on power domain with SIC. In MPDMAC-SIC, a power contention procedure other than traditional RTS/CTS contention in CSMA/CA DCF is introduced to allocate proper transmitting power for transmitters. Second, MPDMAC-SIC is modeled by discrete time Markov chain to minimize access delay by optimizing window size in power contention. According to the simulation results, MPDMAC-SIC performs better on access delay and packet arriving rate, compared to the existing good performing priority based CSMA/CA in both single-hop and multi-hop networks.

An Efficient Scalable Scheduling MAC Protocol for Underwater Sensor Networks.

Underwater Sensor Networks (UWSNs) utilise acoustic waves with comparatively lower loss and longer range than those of electromagnetic waves. However, energy remains a challenging issue in addition to long latency, high bit error rate, and limited bandwidth. Thus, collision and retransmission should be efficiently handled at Medium Access Control (MAC) layer in order to reduce the energy cost and also to improve the throughput and fairness across the network. In this paper, we propose a new reservation-based distributed MAC protocol called ED-MAC, which employs a duty cycle mechanism to address the spatial-temporal uncertainty and the hidden node problem to effectively avoid collisions and retransmissions. ED-MAC is a conflict-free protocol, where each sensor schedules itself independently using local information. Hence, ED-MAC can guarantee conflict-free transmissions and receptions of data packets. Compared with other conflict-free MAC protocols, ED-MAC is distributed and more reliable, i.e., it schedules according to the priority of sensor nodes which based on their depth in the network. We then evaluate design choices and protocol performance through extensive simulation to study the load effects and network scalability in each protocol. The results show that ED-MAC outperforms the contention-based MAC protocols and achieves a significant improvement in terms of successful delivery ratio, throughput, energy consumption, and fairness under varying offered traffic and number of nodes.

Distributed quality of service routing protocol for multimedia traffic in WiMedia networks

Ultra-wideband (UWB) technology has emerged as a solution for the wireless interface between medical sensors and personal servers in future telemedicine systems. The WiMedia Alliance has specified a distributed medium access control protocol based on UWB for high-rate WPANs. In the cases of some applications, data traffic between the source device and destination device is transmitted via one or more intermediate links before it reaches the destination device. However, when all data frames do not transmit in the current DRP reservation block, a relay device cannot transmit the received data frame from the source device in the current DRP policy, until the next DRP duration reserved for forwarding to the destination device begins. This policy increases end-to-end latency between the source device and destination device significantly. Therefore, in this paper, we propose a novel reservation-based routing protocol to minimize the end-to-end delay between source and destination. The proposed routing protocol utilizes the number of medium access slots and hop-count to decide the optimal route between the source device and destination device. The simulation results show that the proposed protocol can enhance the throughput and delay performance and improve energy efficiency by minimizing the packet drop and collision.

Distributed Medium Access Control Protocol for Successive Interference Cancellation-Based Wireless Ad Hoc Networks

Successive interference cancellation (SIC) enables the successful reception of multiple concurrent transmissions and elimination of interference through successive decoding. However, previously proposed distributed medium access control protocols have not exploited SIC. They mostly focused on either interference avoidance, based on the assumption that a receiver can only decode one transmission at a time, or self-interference cancellation, where a node can be a receiver and a transmitter at the same time. In this letter, we propose the first distributed communication protocol for SIC-based wireless networks, based on a novel message exchange and decision mechanism, to enable the simultaneous transmission of multiple neighboring nodes around the transmitter and receiver. The message exchange allows a random subset of neighboring nodes to test the feasibility of their simultaneous transmission. The decision mechanism evaluates the successive decoding capability of SIC receivers with the additional activation of neighboring nodes. We demonstrate the throughput improvement of the proposed algorithm via extensive simulations.

Opportunity prediction at MAC-layer sensing for ad-hoc cognitive radio networks

Knowledge of channel usage pattern of primary users (PUs) helps in predicting future channel availability which can reduce MAC-layer sensing overhead in cognitive radio networks. In this work, two important issues of MAC-layer sensing have been investigated for underlay mode cognitive radio networks. These are - (a) estimation and modeling of licensed channel usage pattern of PUs, while tolerating interference from secondary users (SUs), and (b) usage of learnt channel usage patterns for discovery of opportunities by the SUs. Accordingly, a Hidden Markov Model (HMM) based channel usage pattern of PUs is proposed for use by the SUs to predict the spectrum opportunity. The proposed model uses estimated interference power constraint (IPC) in determining the interference due to presence of SUs to protect the PUs from harmful interference. A formulation deriving the availability metric (AM) for licensed channels is developed which helps in selecting the best channel by an SU for its transmission needs. Experimental results show that the trained HMMs can be used for predicting future channel availability, provided the same IPC condition prevails for a certain period. It is also observed that the AM of the channel sequences generated by the trained HMMs is effective in selecting a suitable channel for transmission. Furthermore, a distributed medium access control protocol for data dissemination (DMDD) in underlay mode CRNs is proposed which utilizes the proposed channel usage model. Simulation based results have shown the effectiveness of the proposed channel usage model.

Distributed MAC protocol for multichannel cognitive radio ad hoc networks based on power control

Spectrum for wireless communications is traditionally assigned by inefficient spectrum access schemes. Portions of the spectrum are exclusively used by specific wireless systems. In recent studies, measurements indicated that allocated spectrum bands are not efficiently used in a certain geographic area, and the utilization of licensed spectrum is highly dependent on location and time. In cognitive radio ad hoc networks (CRAHNs), Secondary Users (SUs) can opportunistically utilize spectrum that is available from Primary Users (PUs). SUs must hop from one spectrum band to another to obtain the spectrum opportunities. In this paper, we propose a distributed medium access control (DMAC) protocol based on power control for CRAHNs, to mitigate the hidden and exposed terminal problems of multichannel PUs and SUs by building an appropriate number of monitor nodes in suitable positions. We develop the Markov chain model to characterize the performance of our proposed DMAC protocol for the saturation network. In this study, transmitter power control is based on the estimated distance between SU communication pairs; this increases channel spatial reuse and throughput, and reduces PU outage probability. In addition, DMAC uses the neighbors of PUs to inform SU communication pairs in the one-hop range; this also reduces PU outage probability. We also compare our proposed scheme to existing MAC protocols for CRAHNs. We show that DMAC will improve channel spatial reuse and normalized throughput, and reduce PU outage probability.

Distributed medium access control protocol based on successive collision detection for dense wireless sensor networks

The medium access control protocol plays an important role to decrease access collisions in dense wireless sensor networks where multiple sensors in the same vicinity attempt to transmit a packet simultaneously. In this article, we propose a distributed medium access control protocol that uses successive multiple collision detection phases for dense wireless sensor network environments by enhancing the typical carrier sense multiple access with collision resolution protocol that uses only a single collision detection phase. In the proposed medium access control protocol, colliding stations are filtered in each collision detection phase and only surviving stations compete again in the next collision detection phase. Therefore, the collision detection probability becomes higher as the collision detection phases proceed. Utilizing the successive multiple collision detection phases, we analyze the throughput numerically and find optimal operating parameters—such as the number of collision detection phases and the number of collision detection slots per phase—that maximize the throughput. Analysis and simulation results show that the proposed medium access control protocol using the successive collision detection technique significantly outperforms the conventional carrier sense multiple access with collision resolution protocol.

Channel-Aware Medium Access Control in Multichannel Cognitive Radio Networks

Distributed medium access control (MAC) is important for efficient exploitation of spectrum opportunities in cognitive radio networks. This letter proposes a channel-aware distributed MAC protocol for multichannel cognitive radio networks. The transmitting nodes use channel state information to exploit the available multiuser and multichannel diversity, by contending only under relatively favorable channel conditions. Towards this end, each node utilizes a threshold that is dynamically updated according to certain rules. Simulation results corroborate the throughput gains achieved by the proposed protocol.

PAD-MAC: primary user activity-aware distributed MAC for multi-channel cognitive radio networks.

Cognitive radio (CR) has emerged as a promising technology to solve problems related to spectrum scarcity and provides a ubiquitous wireless access environment. CR-enabled secondary users (SUs) exploit spectrum white spaces opportunistically and immediately vacate the acquired licensed channels as primary users (PUs) arrive. Accessing the licensed channels without the prior knowledge of PU traffic patterns causes severe throughput degradation due to excessive channel switching and PU-to-SU collisions. Therefore, it is significantly important to design a PU activity-aware medium access control (MAC) protocol for cognitive radio networks (CRNs). In this paper, we first propose a licensed channel usage pattern identification scheme, based on a two-state Markov model, and then estimate the future idle slots using previous observations of the channels. Furthermore, based on these past observations, we compute the rank of each available licensed channel that gives SU transmission success assessment during the estimated idle slot. Secondly, we propose a PU activity-aware distributed MAC (PAD-MAC) protocol for heterogeneous multi-channel CRNs that selects the best channel for each SU to enhance its throughput. PAD-MAC controls SU activities by allowing them to exploit the licensed channels only for the duration of estimated idle slots and enables predictive and fast channel switching. To evaluate the performance of the proposed PAD-MAC, we compare it with the distributed QoS-aware MAC (QC-MAC) and listen-before-talk MAC schemes. Extensive numerical results show the significant improvements of the PAD-MAC in terms of the SU throughput, SU channel switching rate and PU-to-SU collision rate.

A Distributed Medium Access Control Protocol for Cognitive Radio Ad Hoc Networks

We propose a distributed medium access control protocol for cognitive radio networks to opportunistically utilize multiple channels. Under the proposed protocol, cognitive radio nodes forecast and rank channel availability observing primary users’ activities on the channels for a period of time by time series analyzing using smoothing models for seasonal data by Winters’ method. The proposed approach protects primary users, mitigates channel access delay, and increases network performance. We analyze the optimal time to sense channels to avoid conflict with the primary users. We simulate and compare the proposed protocol with the existing protocol. The results show that the proposed approach utilizes channels more efficiently.

A Contention Delay Minimization Scheme in WiMedia Networks

Ultra wideband (UWB) technology has emerged as a solution for the wireless interface between medical sensors and a personal server in future telemedicine systems. The WiMedia Alliance has specified a distributed medium access control protocol based on UWB for high-rate WPANs. Because WiMedia devices transmit data frames using CSMA/CA in PCA duration, waste of time slot interval occurs by collision, and data transmission and the overall throughput is decreased. Therefore, we propose medium access scheme to improve conflict and channel waste and to minimize contention by using own beacon slot number and neighbor's beacon slot number. Simulation results have shown that the proposed scheme has excellent performance in terms of throughput, delay, jitter, and fairness.

OFDMA-Based Channel-Width Adaptation in Wireless Mesh Networks

Channel-width adaptation can optimize multiple performance metrics of a wireless communication link, including transmission rate, communication range, resilience to delay spread, and power consumption. Supporting variable channel width has been considered one of the most critical features of a communication radio. How to leverage a channel-width adaptive radio to improve throughput of a wireless network is a challenging problem in the medium access control (MAC) layer. So far, there exist research results on either theoretical analysis or protocol implementation for a point-to-multipoint (PMP) infrastructure network. However, the impact of channel width to a multihop wireless network has not been fully investigated yet. More specifically, how to exploit variable channel width to enhance throughput of a multihop wireless network remains an unresolved research issue. This paper addresses this issue in wireless mesh networks (WMNs) considering orthogonal frequency-division multiple-access (OFDMA)-based channel-width adaptation. Theoretical analysis is first carried out to identify appropriate algorithms for channel width adaptation. To this end, resource allocation with OFDMA-based channel-width adaptation is formulated as an optimization problem, which is proved to be NP-complete. To reduce the computational complexity, a greedy algorithm is derived to obtain a suboptimal solution. Based on such a greedy algorithm, a distributed MAC protocol is designed for channel-width adaptation for OFDMA-based WMNs. It takes advantage of variable channel width in different time slots to achieve highly efficient resource allocation. Simulation results illustrate that the distributed MAC protocol significantly outperforms MAC protocols based on traditional channel-width adaptation.

Channel State Information Based Distributed Reservation Protocol for Energy Efficiency in WiMedia Networks

Ultra wideband (UWB) technology has emerged as a solution for the wireless interface between medical sensors and a personal server in future telemedicine systems. The WiMedia Alliance has specified a distributed medium access control protocol based on UWB for high-rate wireless personal area networks. The legacy WiMedia standard must statically reserve an additional transmission time of 30 %, since transmission time is limited to network environment in wireless network. When channel environment is deteriorating badly, the additional reservation may not have enough time. Because the legacy WiMedia standard must wait the next reservation period if sending device does not transmit data frames in the current reservation period, the transmission delay occurs. Also, in a good channel environment, the additional reservation time results in a waste of performance. Therefore, there is a need to provide the reliability of data transmission as sending device predicts channel environment in WiMedia network and reserves the distributed reservation protocol (DRP) reservation duration considering the estimated channel environment. In this paper, we propose a novel resource reservation scheme considering channel environment in WiMedia network. The simulation results show that proposed protocol can enhance the throughput and delay performance and improve energy efficiency by minimizing the idle period of DRP reservation block.

RF-MAC: A Medium Access Control Protocol for Re-Chargeable Sensor Networks Powered by Wireless Energy Harvesting

Wireless charging through directed radio frequency (RF) waves is an emerging technology that can be used to replenish the battery of a sensor node, albeit at the cost of data communication in the network. This tradeoff between energy transfer and communication functions requires a fresh perspective on medium access control (MAC) protocol design for appropriately sharing the channel. Through an experimental study, we demonstrate how the placement, the chosen frequency, and number of the RF energy transmitters impact the sensor charging time. These studies are then used to design a MAC protocol called RF-MAC that optimizes energy delivery to sensor nodes, while minimizing disruption to data communication. In the course of the protocol design, we describe mechanisms for (i) setting the maximum energy charging threshold, (ii) selecting specific transmitters based on the collective impact on charging time, (iii) requesting and granting energy transfer requests, and (iv) evaluating the respective priorities of data communication and energy transfer. To the best of our knowledge, this is the first distributed MAC protocol for RF energy harvesting sensors, and through a combination of experimentation and simulation studies, we observe 300% maximum network throughput improvement over the classical modified unslotted CSMA MAC protocol.

Media access protocol for a coexisting cognitive femtocell network

Femtocell networks are widely deployed to extend cellular network coverage into indoor environments such as large office spaces and homes. Cognitive radio functionality can be implemented in femtocell networks based on an overlay mechanism under the assumption of a hierarchical access scenario. This study introduces a novel femtocell network architecture, that is characterized by a completely autonomous femtocell bandwidth access and a distributed media access control protocol for supporting data and real-time traffic. The detailed description of the architecture and media access protocol is presented. Furthermore, in-depth theoretical analysis is performed on the proposed media access protocol using discrete-time Markov chain modeling to validate the effectiveness of the proposed protocol and architecture.

Distributed MAC Protocol Supporting Physical-Layer Network Coding

Physical-layer network coding (PNC) is a promising approach for wireless networks. It allows nodes to transmit simultaneously. Due to the difficulties of scheduling simultaneous transmissions, existing works on PNC are based on simplified medium access control (MAC) protocols, which are not applicable to general multihop wireless networks, to the best of our knowledge. In this paper, we propose a distributed MAC protocol that supports PNC in multihop wireless networks. The proposed MAC protocol is based on the carrier sense multiple access (CSMA) strategy and can be regarded as an extension to the IEEE 802.11 MAC protocol. In the proposed protocol, each node collects information on the queue status of its neighboring nodes. When a node finds that there is an opportunity for some of its neighbors to perform PNC, it notifies its corresponding neighboring nodes and initiates the process of packet exchange using PNC, with the node itself as a relay. During the packet exchange process, the relay also works as a coordinator which coordinates the transmission of source nodes. Meanwhile, the proposed protocol is compatible with conventional network coding and conventional transmission schemes. Simulation results show that the proposed protocol is advantageous in various scenarios of wireless applications.