Channel Medium Access Control Research Articles

On Flow Control and Optimized Back-Off in Non-Saturated CSMA

Medium Access Control (MAC) main functions encompass contention for channel access, packet scheduling, error control, and data integrity. Channel contention is a collective function involving all stations in the network, while data integrity pertains to data flows of each individual station. We propose a design where contention related functions are separated from other data management functions. The hinge connecting contention and other data management functions is a flow control algorithm, aiming at guaranteeing stability of contention queues and load on the MAC channel. With reference to Carrier-Sense Multiple Access (CSMA), we define an analytical model of contention queues under non saturated traffic. An asymptotic analysis of the model for large number of stations yields a closed form of the optimal flow control rate. The insight gained from the model is used to design an adaptive flow control algorithm that guarantees throughput optimality for all values of the number of stations.

Multiusers parallel competitive channel protocol based on unsaturated service

In order to enhance the area throughput of next generation wireless local area network (WLAN) in high density scenarios, orthogonal frequency division multiple access (OFDMA) has been adopted as one of the key technologies in the next generation WLAN communication standards. However, the performance of the existing media access control (MAC) degrades significantly under unsaturated services. Therefore, this paper proposes a multi-user parallel contention channel MAC (MU-MAC) based on unsaturated services, which can effectively reduce the channel access conflict and improve the OFDMA access efficiency of cluster member nodes. On this basis, MU-MAC is enhanced for the spatial clustering group (SCG) formation protocol and support for the unsaturated service characteristics. Further, the optimal access radius when the service is in a non-saturated state is analyzed to make the relevant theoretical analysis more generally, and the expressions for the throughput and area throughput of the proposed protocol are modeled and derived. The simulation results verify the correctness of the theoretical analysis and the efficiency of the protocol performance. The results show that MU-MAC outperforms IEEE 802.11ax and OMAX protocol in area throughput by 40.72% and 104.15%, respectively.

Cross Layering using Reinforcement Learning in Cognitive Radio-based Industrial Internet of Ad-hoc Sensor Network

The coupling of multiple protocol layers for a Cognitive Radio-based Industrial Internet of Ad-hoc Sensor Network, enables better interaction, coordination, and joint optimization of different protocols in achieving remarkable performance improvements. In this paper, network, and medium access control (MAC) layer functionalities are cross-layered by developing the joint strategy of routing and effective spectrum sensing and Dynamic Channel Selection (DCS) using the Reinforcement Learning (RL) algorithm. In an industrial ad-hoc scenario, the network layer utilizes the sensed spectrum and selected channel by MAC layer for next-hop routing. MAC layer utilizes the lowest known transmission delay of a channel for a single hop as computed by the network layer, which improves the MAC channel selection operation. The applied RLbased technique (Q learning) enables the CR Secondary Users (SUs) to sense, learn, and make the optimal decision on their environment of operations. The proposed RLCLD schemes improve the SU network performance up to 30% as compared to conventional methods.

Cross-Layer Analysis of Multi-Static RFID Systems Exploiting Capture Diversity

In this paper, we propose a framework for cross-layer analysis of multi-static passive RFID systems. The model takes into account details of the shared wireless channel, including fading and capture effect, whereas, at the medium access control (MAC) layer, the anti-collision mechanism proposed in the EPC Generation 2 standard is taken as a reference. To address the complexity of the system model, we rely on a semi-analytical approach, that combines a moment matching approximation method to abstract the physical layer and Monte-Carlo simulations to describe the MAC dynamics. Furthermore, based on the space diversity feature offered by the multi-static settings, we introduce the concept of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">capture diversity</i> and propose a modification to the standard to fully support this form of diversity. Numerical results show the impact of deployment conditions and the relative positions of interrogator, tags, and detection points on the performance of tags’ identification. We show how the number of detection points impacts the system performance under various channel conditions and MAC parameters’ settings. Finally, we validate the proposed update of the MAC protocol, showing substantial performance improvement with respect to the standard collision resolution policy.

Hybrid MAC Protocol for Brain–Computer Interface Applications

Brain-computer interface (BCI) can permit individuals to use their thoughts as the sole means to control objects such as smart homes and robots. While BCI is a promising interdisciplinary tool, researchers are confronting network lifetime as an obstacle to further development. Furthermore, the medium access control (MAC) protocol is the bottleneck of the network reliability. There are many standards for MAC protocols that can be utilized for productive and dependable transmission by altering the control parameters. Modifying these parameters is another source of concern due to the scarcity in knowledge about its effect. In addition, there is no instrument accessible to receive and actualize these parameters on transmitters embedded inside the cerebrum. In this article, we give the transmission instrument to both ultrahigh-frequency (UHF) radio frequency identification (RFID) and ultra-wideband (UWB) signals for multiple transmitters and ultrasonic technology mimicking the neural dusts by modifying the superframe structure. In this article, a hybrid MAC protocol is proposed, and the results show that the traffic received can be increased by 700% for UHF-RFID and more than 100% for UWB and ultrasonic technology. Comparative results for wireless channel MAC protocols using these different transmission techniques are discussed in terms of network delay, data dropped, traffic sent, and traffic received.

A Dual Channel Medium Access Control (MAC) Protocol for Underwater Acoustic Sensor Networks Based on Directional Antenna

Medium access control (MAC) protocol is an important link for achieving networks function in any wireless networks; an efficient and reliable MAC protocol is crucial for an effective underwater acoustic sensor networks (UASNs). Significant differences between UASNs and terrestrial sensor networks (TSNs) render the traditional MAC protocols applied on land inapplicable underwater. Existing MAC protocols for UASNs use the omnidirectional antenna, which wastes energy, restricts the network’s coverage range, and brings about unnecessary interferences in neighbor nodes. This paper proposes a dual channel MAC protocol for UASNs based on directional antenna (DADC-MAC), which increases the network coverage range, efficiently utilizes space, and reduces node interference compared to the omnidirectional antenna. The DADC-MAC protocol divides the channel into a data transmission channel and busy prompt message channel; the node uses the former to transmit the control frame and DATA package while the sending node and receiving node use the latter channel to inform the neighbor nodes of on-going communications to prevent DATA package collision. A neighbor discovery mechanism and directional network allocation vector are applied to resolve hidden terminal and deafness problems. Simulation results show that the DADC-MAC protocol could improve network throughput and reduce end-to-end delay, is efficient, performs well, and is well suited to both symmetrical and asymmetrical UASNs topology.

Multichannel MAC Scheme to Deliver Real-Time Safety Packets in Dense VANET

Intelligent Transportation System (ITS) provides facility of driving assistance and multimedia services to the road users. To improve the Intelligent Transportation System, Vehicular Ad-Hoc Networks are the most prominent area that improve the services of ITS. Vehicular Ad-Hoc Networks apply multiple channel medium access control scheme according to the IEEE 1609.4 standard draft. According to the standard draft multiple channel medium access control scheme, channels are split into service channels (SCHs) and control channel (CCHs). This work proposes a dynamic control channel interval (DCI) MAC scheme that can variably fix the time interval between SCHs and CCH efficiently. This work divides the SCHs interval time into small interval time slots according to the current network traffic load.

Performance Analysis of IEEE 802.11ad MAC Protocol

IEEE 802.11ad specifies a hybrid medium access control (MAC) protocol consisting of contention as well as noncontention-based channel access mechanisms. Further, it also employs directional antennas to compensate for the high freespace path loss observed in 60GHz frequency band. Therefore, it significantly differs from other IEEE 802.11(b/g/n/ac) MAC protocols and thus requires new methods to analyze its performance. In this paper, we propose a new analytical model for performance analysis of IEEE 802.11ad employing a threedimensional Markov chain considering all the features of IEEE 802.11ad medium access mechanisms including the presence of non-contention access and the different number of sectors due to the use of directional antennas. We show that the number of sectors has a high impact on the network throughput. We also show that the MAC packet delay is significantly affected by the duration of the contention period. Our results indicate that a suitable choice of the number of sectors and contention period can illustriously improve the channel utilization and MAC delay performance.

Evaluación de los protocolos MAC IEEE 802.11 y MMAC-CR en una red manet

Este artículo presenta un análisis comparativo entre los mecanismos de control de acceso al medio IEEE 802.11 y MMAC-CR (Multichannel MAC protocol for Cognitive Radio) en redes MANET (Mobile Ad Hoc Networks). El estándar IEEE 802.11 permite el uso de múltiples canales disponibles en la capa física, pero su protocolo MAC está diseñado para un solo canal. Sin embargo, un protocolo MAC de un solo canal no trabaja bien en un entorno multicanal debido al problema del terminal oculto. La metodología del artículo se basa en la descripción de los protocolos de control de acceso al medio, la simulación del throughput de estos, el análisis de los resultados y las conclusiones. Los resultados de simulación muestran cómo el protocolo MMAC-CR permite hacer un mejor uso de las oportunidades espectrales, incrementando de esta manera el throughput de la red MANET.

Modeling IEEE 802.15.4 Networks Over Fading Channels

Although the performance of the medium access control (MAC) of the IEEE 802.15.4 has been investigated under the assumption of ideal wireless channel, the understanding of the cross-layer dynamics between MAC and physical layer is an open problem when the wireless channel exhibits path loss, multi-path fading, and shadowing. The analysis of MAC and wireless channel interaction is essential for consistent performance prediction, correct design and optimization of the protocols. In this paper, a novel approach to analytical modeling of these interactions is proposed. The analysis considers simultaneously a composite channel fading, interference generated by multiple terminals, the effects induced by hidden terminals, and the MAC reduced carrier sensing capabilities. Depending on the MAC parameters and physical layer thresholds, it is shown that the MAC performance indicators over fading channels can be far from those derived under ideal channel assumptions. As novel results, we show to what extent the presence of fading may be beneficial for the overall network performance by reducing the multiple access interference, and how this information can be used for joint selection of MAC and physical layer parameters.

A MAC protocol with mobility support in cognitive radio ad hoc networks: Protocol design and analysis

Cognitive radio ad hoc networks (CRAHNs) have recently been proposed as a way to bring cognitive radio (CR) technology to traditional ad hoc networks. An important problem is to design a medium access control (MAC) protocol that addresses the decentralized control and local observation for spectrum management. In this paper, we propose a cognitive MAC protocol with mobility support (CM-MAC) based on carrier sense multiple access/collision avoidance (CSMA/CA) technique, where our protocol can respond to the vicinity state of CR nodes to primary exclusive regions. This paper analyzes the throughput performance for the proposed MAC protocol with the consideration of multiple PU activities and CR nodes. Our analytical results show that the proposed MAC protocol outperforms the throughput performance of the classical CSMA/CA MAC and statistical channel allocation (SCA) MAC protocols.

Multi-channel MAC Protocol in Cognitive Radio Networks

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.

A Survey and Qualitative Analysis of Multi-channel Mac Protocols for VANET

Vehicular Ad-hoc Network (VANET) is an emerging and promising technology that places great demand on the access capability of the existing wireless technology. In VANET one primary issue is Medium Access Control (MAC), which aims to utilize the radio spectrum efficiently, to resolve potential contention and collision among vehicles for using the medium. Contention reduces the performance of single channel MAC layer and the workload distribution is also not well defined. So multi channel MAC protocols are useful to provide better quality of services (QoS) wherein, multi channel interference is a major problem to assign channel to a particular vehicle. Hence a survey is necessary on multi channel MAC protocols based on various parameters in vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) communication. This paper gives a brief overview of various issues involved in the design of multi channel MAC protocol in VANET.

Hopping control channel MAC protocol for opportunistic spectrum access networks

Opportunistic spectrum access (OSA) is considered as a promising approach to mitigate spectrum scarcity by allowing unlicensed users to exploit spectrum opportunities in licensed frequency bands. Derived from the existing channel-hopping multiple access (CHMA) protocol, we introduce a hopping control channel medium access control (MAC) protocol in the context of OSA networks. In our proposed protocol, all nodes in the network follow a common channel-hopping sequence; every frequency channel can be used as control channel and data channel. Considering primary users' occupancy of the channel, we use a primary user (PU) detection model to calculate the channel availability for unlicensed users' access. Then, a discrete Markov chain analytical model is applied to describe the channel states and deduce the system throughput. Through simulation, we present numerical results to demonstrate the throughput performance of our protocol and thus validate our work.

Collision Free MAC Protocol for Multi-Hop Wireless Networks

Collision rate increases significantly with the appearance of hidden nodes in multi-hop wireless network, which results in unsuccessful transmissions and leads to performance degradation of the network. The RTS/CTS handshakes of 802.11DCF can not eliminate hidden nodes, and the situation becomes worse when the nodes are equipped with higher speed wireless devices, which require higher signal to interference and noise ratio (SINR) for successful reception. This paper analyzes the prevalence of hidden nodes in multi-hop wireless network and proposes an MAC protocol named double channel collision free media access protocol—DCCFMA to solve the hidden nodes problem. DCCFMA is a dual channel MAC (media access control) protocol, receiver adjusts the transmitting power of the control channel according to the signal power received from the transmitter so as to cover all hidden nodes around the receiver. Simulation results show that DCCFMA solves hidden nodes problem better than RTS/CTS (ready-to-send/clear-to-send) handshakes and achieves 24% additional network throughput as compared to that of 802.11 DCF.

Can multiple subchannels improve the delay performance of RTS/CTS-based MAC schemes?

We analyze the delay performance of RTS/CTS-based (Request-To-Send/Clear-To-Send) multi-channel MAC (Medium Access Control) schemes for wireless networks. These schemes usually employ multiple data subchannels for data transmission and one control subchannel to send the RTS/CTS dialogue for channel reservation. Through theoretical analysis and simulations, we show that, in fully-connected networks, such multi-channel MAC schemes suffer longer delays than the corresponding single channel MAC scheme, that puts the RTS/CTS dialogue on the same channel as data packet transmissions. This conclusion holds even when data packets have different priorities and higher priority traffic is sent ahead of lower priority traffic.

A cross-layer approach for WLAN voice capacity planning

This paper presents an analytical approach to determining the maximum number of on/off voice flows that can be supported over a wireless local area network (WLAN), under a quality of service (QoS) constraint the authors consider multiclass distributed coordination function (DCF) based medium access control (MAC) that can provision service differentiation via contention window (CW) differentiation. Each on/off voice flow specifies a stochastic delay bound at the network layer as the QoS requirement. The downlink voice flows are multiplexed at the access point (AP) to alleviate the MAC congestion, where the AP is assigned a smaller CW compared to that of the mobile nodes to guarantee the aggregate downlink throughput. There are six-fold contributions in this paper: 1) a nonsaturated multiclass DCF model is developed; 2) a cross-layer framework is proposed, which integrates the network-layer queueing analysis with the multiclass DCF MAC modeling; 3) the channel busyness ratio control is included in the framework to guarantee the analysis accuracy; 4) the framework is exploited for statistical multiplexing gain analysis, network capacity planning, contention window optimization, and voice traffic rate design; 5) a head-of-line outage dropping (HOD) scheme is integrated with the AP traffic multiplexing to further improve the MAC channel utilization; 6) performance of the proposed cross-layer analysis and the associated applications are validated by extensive computer simulations.

Understanding the key performance issues with MAC protocols for multi‐hop wireless networks

AbstractMulti‐hop wireless networks arise in the context of ad hoc networks, sensor networks, and mesh networks, and their performance depends critically on the underlying medium access control (MAC) protocol. Inspite of the large body of work devoted to MAC protocols and associated problems, the relative importance of these problems is still not well understood. This is because most of the previous work focuses on designing a protocol to solve a particular problem, or on identifying scenarios where a protocol will not work well. In addition, most of the work is also based on simplistic assumptions about the physical wireless medium, like fixed ranges for communication and interference, or concepts like capture threshold where the desired signal strength is compared with interference from a single node at a time, rather than cumulatively.Our paper seeks to address these issues. We believe it is extremely critical that (i) we develop an understanding of the relative significance of the problems affecting MAC protocols, and that (ii) we use a realistic model for the physical channel for design and performance evaluation. Towards this end, we evaluate the performance of three currently proposed MAC protocols, IEEE 802.11 [1], RI‐BTMA [2], and DUCHA [3] under a realistic channel model with additive interference. Since these protocols solve or suffer from different sets of problems, our evaluation provides a differential diagnosis of the severity of these problems. Based on our observations, we propose a simple and robust two channel MAC protocol (entitled 2CM) that is based on IEEE 802.11 augmented with a busy‐tone channel. The 2CM protocol (i) mitigates the hidden node problem considerably, (ii) does not waste bandwidth in terms of logical control channels, and (iii) provides a reliable link layer acknowledgment. Through extensive simulations, we show that 2CM offers a consistently high throughput performance while not sacrificing link layer reliability in a variety of scenarios, thereby vindicating our approach. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Analyzing split channel medium access control schemes

In this work, we analyze and evaluate the maximum achievable throughput of split-channel MAC schemes that are based on the RTS/CTS (ready-to-send/clear-to-send) dialogue and that rely on pure ALOHA or on p-persistent carrier sensing multiple access (CSMA) contention resolution techniques. Our results show that, when radio propagation delays are negligible and when the pure ALOHA mechanism is used, then for a network with relatively large number of nodes, the maximum achievable throughput of the split-channel MAC schemes is lower than that of the corresponding single-channel MAC schemes. When the split-channel MAC schemes employ the p-persistent CSMA mechanism, then they out-perform the corresponding single-channel schemes when the maximum end-to-end propagation delays are at least 25% of the transmission time of the control packets on the single shared channel.