Medium Access Protocol Research Articles

Transmission protocols in Cognitive Radio Mesh Networks

A Cognitive Radio (CR) is a radio that can adjust its transmission limit based on available spectrum in its operational surroundings. Cognitive Radio Network (CRN) is made up of both the licensed users and unlicensed users with CR enable and disabled radios. CR’S supports to access dynamic spectrum and supports secondary user to access underutilized spectrum efficiently, which was allocated to primary users. In CRN’S most of the research was done on spectrum allocation, spectrum sensing and spectrum sharing. In this literature, we present various Medium Access (MAC) protocols of CRN’S. This study would provide an excellent study of MAC strategies.

On Secure Communications Over a Wiretap Channel With Fixed-Rate Transmission: Protocol Design and Queueing Analysis

In this letter, we consider a wiretap channel when a source node maintains two buffers (queues) to store its data and secret key packets. We propose two medium-access protocols. In the first proposed protocol, we assume that the legitimate source and its destination share random secret key packets when the main channel is better than either the channel between the eavesdropper and the source or the channel between the eavesdropper and the destination. These key packets are stored in a separate key queue at the source and its destination, and they are utilized to secure data packets whenever channel conditions favor eavesdropper channels over the main communication channel. In the second proposed protocol, the source employs a random-access scheme based on the link and queue states. Our numerical results demonstrate the gains of our proposed protocols in terms of the mean service rate of the data queue and the average queueing delay of the data packets.

CADMA: collision-avoidance directional medium access for vehicular ad hoc networks

Quick and accurate message transmission is an important research topic for vehicular ad hoc networks (VANET). Most studies assume that the periodic broadcast of beacon frames between vehicles increases the safety of the driver. In particular, there has been a lot of research into broadcasting based on carrier sense multiple access with collision avoidance (CSMA/CA) algorithms for medium access. However, the CSMA/CA algorithm is not an optimum technique for the VANET system, due to the transfer delay that occurs in inducing frequent collisions on transmission signals. In this paper, we propose a collision-avoidance directional medium access (CADMA) protocol and infrastructure-utilized clustering method for VANET to support reliable data transfer. In the proposed scheme, the CADMA protocol uses non-competitive transmission methods and cluster heads (CHs) to manage access by allocating the nodes resources. In addition, the roadside unit (RSU) helps with the clustering process. The simulation results indicate that the CADMA can reduce transmission delays and the collision rate of the broadcasting signal, and have shown that the CADMA can be effectively utilized for the VANET systems.

Design and Analysis of Medium Access Protocol: Throughput and Short-Term Fairness Perspective

We consider a simple MAC protocol, called the renewal access protocol (RAP), that adopts all of the legacy 802.11 standard but the backoff stage feature. To meet two objectives in the design of the RAP—optimal throughput and high short-term fairness—we develop a mathematical model of the RAP and rigorously analyze the performance of the RAP. First, we show that the throughput performance of the RAP depends only on the expectation of the selection distribution where the backoff counter is selected, provided that the number of terminals is fixed, which is in accordance with a well-known result. Second, with the help of renewal and reliability theories, we analyze the short-term fairness of the RAP. We also show that if the RAP has a selection distribution of the New Better than Used in Expectation (NBUE) type, the RAP can guarantee high short-term fairness. Third, we construct a special binomial distribution that is obviously of the NBUE type that can achieve high short-term fairness as well as optimal throughput when used as the selection distribution of the RAP. Furthermore, by the Poisson approximation for binomial distributions, we propose to use in practice a Poisson distribution corresponding to the special binomial distribution. Numerical and simulation results are provided to validate our analysis.

Centralized MAC protocol for hierarchical caching processors

The subject of research is the architecture of modern processors with hierarchical organization of cache subsystem. Analysis of implementation possibility of wireless connectivity between cores and Level 3 cache has been carried out. In order tospecify the requirements to wireless communication channel, communication in modern general-purpose processors has been explored by an example of Intel Core i7 (Haswell). Interaction model of cache subsystem components has been developed, and on its basis interaction characteristics between them are being evaluated. Analysis of the model shows that the latency of cache line transmission via the proposed channel is about 0.26 nanoseconds, which correlates well with the latency of L1 cache (about 2 nanoseconds). Also, wireless channel satisfies the distance requirements, giving the possibility for data transmission upto 3 centimeters, as well as power requirements with consumption of 1 uW. The result of research is the developed medium access protocol for wireless connectivity between computational cores and Level 3 cache. To account for required simplicity of implementation and efficiency of operation, it is proposed to use the single frequency range for all radio interfaces and time division multiple access scheme with prescribed fields for addressing and data. The paper deals with protocol data unit structure, which is used for communication between units. Possibility of shared time counter creationis used for synchronization between units. Time division duplex with possibly dynamic non-equal time shares is used to organize uplink and downlink communications. Time division mechanism gives the possibility for the system to adapt to load irregularities between the cores through allocation of various amounts of time slots for each core.

EASO-TDMA: enhanced ad hoc self-organizing TDMA MAC protocol for shipborne ad hoc networks (SANETs)

As very high frequency (VHF) data links are overloaded due to the rise of Automatic Identification System (AIS) applications, additional VHF channels and the development of corresponding communication technologies are necessary. For this reason, shipborne ad hoc networks (SANETs) and the medium access (MAC) protocol for SANETs,ad hoc self-organizing-time division multiple access (ASO-TDMA), have been proposed, which provide ocean-going ships with diverse data services cost-effectively. In this paper, a new MAC protocol for SANETs, enhanced ASO-TDMA (EASO-TDMA), is proposed in order to manage the bottleneck and under-utilization problems resulting fromASO-TDMA and thus enhances the overall performance of SANETs. To accomplish this, in EASO-TDMA, a ship adaptively allocates its time slots according to the number of subscribing ships, which make their communication route to a base station at the shore via the ship, by referring to the routing table. The performance of EASO-TDMA is investigated through simulations and compared with that of ASO-TDMA. The simulation results indicate that EASO-TDMA outperforms ASO-TDMA, regardless of the network conditions, with 25 % higher reception success rate, 25 % lower collision rate, and 21 % higher channel utilization at maximum. In particular, the end-to-end delay of EASO-TDMA is on average 1/12 of that of ASO-TDMA, and this implies that EASO-TDMA can be effective for delay-sensitive data services.

Efficient and Reliable MPEG-4 Multicast MAC Protocol for Wireless Networks

Multicasting is the transmission of data to a group of nodes identified by a single destination address. Furthermore, multicasting is considered as an appropriate transmission method for multimedia services. Multimedia applications are expected to become more prevalent over mobile ad hoc networks in the near future. Therefore, achieving reliability in multimedia communications is an important task. Video compression technologies are about reducing and removing redundant video data so that a digital video file can be effectively sent over a network. With modern compression standards, such as Moving Picture Expert Group 2 (MPEG-2), MPEG-4, and H.264, which is also known as advanced video coding MPEG-4 part 10, losses of different frames have different impacts on video quality. In this paper, we propose a leader-based reliable multicast medium-access control layer protocol for multimedia applications to enhance video quality. We present a Markov chain model and numerical formulation of our proposed protocol. Simulation results show that our proposed method is better than other protocols in terms of the number of decodable frames, peak signal-to-noise ratio (PSNR), and video quality.

Throughput Enhancement of Cognitive Radio Networks through Improved Frame Structure

cognitive radio (CR) system exploits spectrum bands that are not fully utilized by the licensed users. For the successful deployment of the technology, the biggest challenge is to make network protocols more adaptive to use the available bandwidth effectively. Various medium access protocols (MAC) have been proposed by researchers to manage spectrum sensing and the channel utilization between two kind of users namely licensed primary users and unlicensed secondary users. In this paper, a modified self-scheduling multi-channel cognitive radio MAC protocol based on cooperative communication is proposed to enhance the network throughput by modifying its frame structure. The proposed frame structure also eliminates the sensing throughput tradeoff that was encountered in the conventional scheme. The simulation results show that the proposed scheme significantly outperforms the conventional scheme by increasing the throughput 200Mbps.

Node Synchronization Across Two-layered Heterogeneous Clustered Wireless Sensor Network

Time synchronization is a mandatory feature needed for Wireless Sensor Network to operate consistently and to be capable to chronologically link to global time. Time synchronization is important when the sensor nodes employ TDMA [9] based medium access protocols and when sensor nodes want to operate on some time managed schedule as well. Time stamping is one of the most widely used approaches, because of simple implementation and of being quite precise. Based on the time stamp exchange approach we provide network wide synchronization that employs neighbouring node information to determine if synchronization should be continued on the same level or in the second level of nodes.

Energy Consumption and Fault Tolerance in the MAC Protocols for WSN

Wireless sensor networks are currently experiencing widespread enthusiasm in the field of research, mainly because of the great benefits they promise in terms of flexibility, cost, range and robustness. In addition, such networks find use in a wide variety of applications, for example in collecting remote data, type of climate monitoring, seismic activity, or in other areas such as home automation and medical. Unfortunately, their disadvantages are up to their promises. Indeed, the sensor nodes are subjected to high energy consumption constraints due to their compact size as well as the deployment environment. Frequent replacement of batteries is excluded in a field that can be difficult to access. Therefore, the main challenge remains as a result of miniaturization and reduces power consumption to maximize network lifetime. The objective of this work is to make a thorough study of the energy consumption in wireless sensor networks. The study points are addressed at the media access protocol or MAC protocol.

Design and Analytical Analysis of a Novel DBA Algorithm with Dual-Polling Tables in EPON

Ethernet passive optical network is a point-to-multipoint structure, and an effective media access protocol should be designed for collision avoidance and bandwidth allocation. Most previous researches have aimed to solve the problem using dynamic bandwidth allocation (DBA) algorithms with polling-based schemes. Unfortunately, idle channel time among the polling cycles cannot be overcome efficiently. In this paper, a dual-polling DBA (DP-DBA) algorithm which consists of an interpolling mechanism and an intrapolling mechanism is proposed. The interpolling mechanism helps eliminate the idle time problem while the intrapolling part aggregates the unused bandwidth of the light-loaded users and those due to nondefragmentation of the Ethernet frames of the general users. We also evaluate the performance of the DP-DBA algorithm by a comparison with the interleaved polling with adaptive cycle time (IPACT), the dynamic bandwidth allocation with a modified grant table generation algorithm (DBA2), the Double-Phase Polling (DPP), and the adaptive DBA algorithm with sorting report messages (Sort-DBA) schemes with simulation results. For greater realism with regard to general applications, we also simulate the asymmetric traffic loads at the optical network units (ONUs).The results show that DP-DBA outperforms the other DBA schemes under asymmetric load conditions.

ECOSENSE: An Energy Consumption Protocol for Wireless Sensor Networks

Abstract This paper ‘ECOSENSE’ proposes a medium access protocol derived for wireless sensor networks. Energy is a precious resource for wireless sensor networks, as sensor nodes are powered by small batteries. Various approaches have been proposed so far, to increase the life of wireless sensor networks. With the goal of developing a practical, efficient energy consumption protocol for wireless sensor networks, we introduced a threshold policy for the nodes in the entire network, where the sensors are distributed activated, whenever they are required. We calculated the life period of sensors and using priority levels and threshold values, we prolong the lifespan of sensor nodes. Scheduling is done according to the remaining life period of sensor nodes. We compare our algorithm with the existing S-MAC protocol and found considerably better due to its reconfigurable activation policy.

Networked Optimal Control with Random Medium Access Protocol and Packet Dropouts

This paper is concerned with an optimal control framework for networked control systems in which the channel access of actuators is governed by a group random access protocol. The system is modeled as a switching Markov jump system with multiple modes according to channel-access status of the actuators, and an independent identical distribution Bernoulli process is used to describe the random packet dropouts of the channel. Then, an optimal control design methodology is addressed to satisfy the quadratic cost function by applying the well-developed theory for jump linear systems and stochastic optimal control while guaranteeing the mean-square exponential stability of networked control systems. And, finally, a numerical example is exploited to demonstrate the effectiveness of the proposed method.

DynMAC: A resistant MAC protocol to coexistence in wireless sensor networks

The growth of mobile and ubiquitous computing has increased the demand for wireless communications, which in turn raises interference levels and spectrum pollution, causing problems of network coexistence. The coexistence assurance between these devices and wireless sensor networks is a big challenge. This paper proposes a new medium access protocol, DynMAC (Dynamic MAC), which uses mechanisms of dynamic channel reconfiguration, recovery from lost links and reconfiguration of transmission parameters based on the properties of the cognitive radios, to deal with this problem. Simulations and experiments using a real WSN testbed, were performed to validate our protocol. Results show that the proposed mechanisms solve the WSN configuration problems, in noisy and interference environments, and enable the coexistence with different networks and devices operating in the same frequency spectrum, while maintaining application requirements in critical deployment scenarios.

A Scalable, 2.9 mW, 1 Mb/s e-Textiles Body Area Network Transceiver With Remotely-Powered Nodes and Bi-Directional Data Communication

<?Pub Dtl=""?> This paper presents transceivers and a wireless power delivery system for a Body-Area Network (BAN) that uses an e-textiles-based physical layer (PHY) capable of linking a diverse set of sensor nodes monitoring vital signs on the user's body. A central base station in the network controls power delivery and communication resource allotment for every node using a general-purpose on-chip Node Network Interface (NNI). The architecture of the network ensures fault-tolerance, reconfigurability and ease of use through a dual wireless-wireline topology. The nodes are powered at a peak end-to-end efficiency of 1.2% and can transmit measured data at a peak rate of 1 Mb/s. Modulation schemes for communication in both directions have been chosen and a Medium Access and Control (MAC) protocol has been designed and implemented on chip to reduce complexity at the power-constrained nodes, and move it to the base station. While transferring power to a single node at maximum efficiency, the base station consumes 2.9 mW power and the node recovers 34 µW, of which 14 µW is used to power the network interface circuits while the rest can be used to power signal acquisition circuitry. Fabricated in 0.18 µm CMOS technology, the base station and the NNI occupy 2.95 mm 2 and 1.46 mm 2 area, respectively.

A thorough analysis of the performance of delay distribution models for IEEE 802.11 DCF

Deriving the complete distribution of the end-to-end delay in a wireless multi-hop network is of paramount interest when delay-sensitive flows have to be conveyed over such networks. First works have proposed models to derive the total delay distribution of networks assuming the well-known IEEE802.11 DCF medium access (MAC) protocol. Current derivations can be decomposed into two main steps: (i) the calculation of the total delay probability generating function (PGF) and (ii) its numerical inversion. We show in this paper that there is a need for a thorough performance evaluation of these models since both steps introduce errors, naming modeling and inversion errors. We argue that both types of errors have to be analyzed separately to characterize the accuracy of the analytical derivations of the literature. Therefore, this paper defines two performance evaluation metrics that measure the magnitude of both types of errors. Both metrics are illustrated to select and optimize the most accurate model to calculate the single-hop end-to-end delay distribution of nodes using the IEEE802.11 DCF MAC protocol. The most accurate model is extended to calculate the end-to-end delay distribution for a 2-hop wireless communication.

A Cross-Layer Optimization Approach for Lower Layers of the Protocol Stack in Sensor Networks

A cross-layer optimization approach for the physical and medium access control layers of wireless sensor networks is introduced in this article. This approach includes a Markov chain model, simulations, and analytical derivations that are applied to the analysis of sensor networks using impulse radio ultra-wideband signals with noncoherent energy detection. This type of communication system has low-power transmission requirements and noise like signal characteristics with low interference to other wireless systems. The energy efficiency of different Reed-Solomon code rates and uncoded case are studied in a star topology network, where slotted Aloha, as defined in the IEEE 802.15.4a standard, is used as the medium access protocol. Analytical and simulation results clearly show the potential energy gains that can be achieved with the proposed optimization approach that can be also used in the evaluation and optimization of other combinations of physical and medium access control protocols.

Enhanced capacity and coverage by Wi-Fi LTE integration

Wi-Fi provides cost-effective data capacity at hotspots in conjunction with broadband cellular networks. The hotspots are required to capture a large number of users and provide high data rates. Data rates, over the Wi-Fi interface, are influenced by the media access protocol, which loses throughput due to delays and unintended collisions when a large number of users are active. The hotspot range which determines the number of users, that can associate, is limited by the lower power of the client rather than the access point. By diverting the traffic destined to the access point via another access network, both range and efficiency can be improved. This uplink redirection or diversion is achieved by simultaneous use of the Wi-Fi and LTE radio interfaces. Three options - loose, tight, and hybrid integration are presented towards providing enhanced capacity and coverage.

Large Overlaid Cognitive Radio Networks: From Throughput Scaling to Asymptotic Multiplexing Gain

We study the asymptotic performance of two multi-hop overlaid ad-hoc networks that utilize the same temporal, spectral, and spatial resources based on random access schemes. The primary network consists of Poisson distributed legacy users with density λ^{(p)} and the secondary network consists of Poisson distributed cognitive radio users with density λ^{(s)} = (λ^{(p)})^beta (β > 0, β ≠ 1) that utilize the spectrum opportunistically. Both networks are decentralized and employ ALOHA medium access protocols where the secondary nodes are additionally equipped with range-limited perfect spectrum sensors to monitor and protect primary transmissions. We study the problem in two distinct regimes, namely β > 1 and 0 1. On the contrary, spectrum sensing turns out to be unnecessary when β < 1 and employing spectrum sensors cannot improve the network performances.

An optimal fuzzy control medium access in wireless body area networks

Wireless body area network (WBAN) collects significant signals of human body or environment information for health monitoring or professional services. But normal medium access protocols can hardly make a balance and ensure enough reliability of a network because there are specific features and service quality in WBAN applications. Contention access or fixed allocation of bandwidth cannot meet all nodes׳ requirements and may cause collisions and delay. Especially in emergency medical situations, some data must be transmitted immediately for accurate diagnosis and decision. The dropping of critical messages could possibly create life threatening results. In order to improve the reliability and efficiency of data transmission in WBAN, this paper proposes a fuzzy control medium access (FCMA) mechanism based on input parameters for performance gains. It controls the contention window in contention access period (CAP) and slots allocation in contention free period (CFP) according to nodes׳ status. Through simulation analysis, the improved performance of throughput, latency, and packets breakdown is demonstrated by efficient usage of bandwidth and avoidance of collision.