Novel Medium Access Control (MAC) Protocols for Wireless Sensor and Ad Hoc Networks (WSANs) and Vehicular Ad Hoc Networks (VANETs)

Efficient medium access control (MAC) is a key part of any wireless network communication architecture. MAC protocols are needed for nodes to access the shared wireless medium efficiently. Providing high throughput is one of the primary goals of the MAC protocols designed for wireless networks. MAC protocols for Wireless Sensor and Ad hoc networks (WSANs) must also conserve energy as sensor nodes have limited battery power. On the other hand, MAC protocols for Vehicular Ad hoc networks (VANETs) must also adapt to the highly dynamic nature of the network. As communication link failure is very common in VANETs because of the fast movement of vehicles so quick reservation of packet transmission slots by vehicles is important. In this thesis we propose two new distributed MAC algorithms. One is for WSANs and the other one is for VANETs. We demonstrate using simulations that our algorithms outperform the state-of-the-art algorithms

Better Result in Packet Loss and Saving Energy in Ad-Hoc Network by using Improved MAC Protocol

An Ad-Hoc network is a wireless, decentralized, dynamic network in which devices associate with each other in their link range, in which the basic 802.11 MAC protocol uses the Distributed Coordination Function (DCF) to share the media between various devices. But use of 802.11 MAC protocol in Ad-Hoc networks affected by different issues such as restricted power capacity, packet loss because of transmission error, various control traffic and failure to avoid packet collision. To solve these problems various protocols have been proposed. But we don�t have any perfect protocol which can resolve the issues related to power management, packet collision and packet loss efficiently. In this research paper, we suggest a new protocol to adjust the upper & lower bounds for the contention window to decrease the number of collisions. As well as it proposes a power control scheme, triggered by the MAC layer to reduce the packet loss, energy wastage and decrease the number of collisions during transmission. The proposed MAC protocol is implemented and performance is compared with existing 802.11 MAC protocol. We computed the Packet Delivery Fraction(PDF), average End-to-End(e-e) delay, average throughput and packet loss in several conditions. We find proposed protocol is comparatively improved than the existing protocol

An Improved MAC Protocol to Reduce Packet Loss and Energy Wastage in Ad-Hoc Networks

An Ad-Hoc network is a wireless, decentralized, dynamic network in which devices associate with each other in their link range, in which the basic 802.11 MAC protocol uses the Distributed Coordination Function (DCF) to share the media between various devices. But use of 802.11 MAC protocol in Ad-Hoc networks affected by different issues such as restricted power capacity, packet loss because of transmission error, various control traffic and failure to avoid packet collision. To solve these problems various protocols have been proposed. But we don’t have any perfect protocol which can resolve the issues related to power management, packet collision and packet loss efficiently. In this research paper, we suggest a new protocol to adjust the upper & lower bounds for the contention window to decrease the number of collisions. As well as it proposes a power control scheme, triggered by the MAC layer to reduce the packet loss, energy wastage and decrease the number of collisions during transmission. The proposed MAC protocol is implemented and performance is compared with existing 802.11 MAC protocol. We computed the Packet Delivery Fraction(PDF), average End-to-End(e-e) delay, average throughput and packet loss in several conditions. We find proposed protocol is comparatively improved than the existing protocol

Spectrum and Energy Efficient Medium Access Control for Wireless Ad Hoc Networks

The increasingly growing number of mobile devices and volume of mobile data traffic necessitate establishing an effective self-organizing wireless ad hoc network to efficiently utilize radio spectrum and energy. The transmissions time and bandwidth should be dynamically coordinated based on instantaneous traffic load of the links in the network. Energy consumption in a mobile device can be reduced by putting the radio interface into a sleep mode. However, the mobile device cannot receive incoming data packets in the sleep mode. Thus, awake and sleep times of radio interfaces should be carefully planned to avoid missing incoming packets. In a wireless network, links that are far apart in distance can simultaneously transmit using the same bandwidth without interfering reception at destination nodes. Concurrent transmissions should be properly scheduled to maximize spatial spectrum utilization. Also, the transmission power level of each link should be optimized to enhance spectrum and energy efficiencies. First, we present a new energy-efficient medium access control (MAC) scheme for a fully connected wireless ad hoc network. Energy consumption is reduced by periodically putting radio interfaces in the sleep mode and by reducing transmission collisions. The network throughput and average packet transmission delay are also improved because of lower collision and contention overhead. The proposed MAC scheme can achieve energy saving for realtime traffic which requires a low packet transmission delay. An analytical model is established to evaluate the performance of the proposed MAC scheme. Analytical and simulation results demonstrate that the proposed scheme has a significantly lower energy consumption, achieves higher throughput, and has a lower packet transmission delay in comparison with existing power saving MAC protocols. Second, we present a novel distributed MAC scheme based on dynamic space-reservation to effectively coordinate transmissions in a wireless ad hoc network. A set of coordinator nodes distributed over the network area are employed to collect and exchange local network information and to periodically schedule links for transmission in a distributed manner. For each scheduled transmission, a proper space area around the receiver node is reserved to enhance spatial spectrum reuse. Also, the data transmission times are deterministic to minimize idle-listening radio interface energy consumption. Simulation results demonstrate that the proposed scheme achieves substantially higher throughput and has significantly lower energy consumption in comparison with existing schemes. We study joint scheduling and transmission power control in a wireless ad hoc network. We analyze the asymptotic joint optimal scheduling and transmission power control, and determine the maximum spectrum and energy efficiencies in a wireless network. Based on the asymptotic analysis, we propose a novel scheduling and transmission power control scheme to approach the maximum spectrum efficiency, subject to an energy consumption constraint. Simulation results show that the proposed distributed scheme achieves 40% higher throughput than existing schemes. Indeed, the scheduling efficiency of our proposed scheme is about 70% of the asymptotic optimal scheduling and transmission power control. Also, the energy consumption of the proposed scheme is about 20% of the energy consumed using existing MAC protocols. The proposed MAC, scheduling and transmission power control schemes provide effective spectrum sharing and energy management for future wireless hotspot and peer-to-peer communication networks. The presented asymptotic analysis determines the maximum spectrum and energy efficiencies in a wireless network and provides an effective means to efficiently utilize spectrum and energy resources based on network traffic load and energy consumption constrains

Distributed Estimation and Control of Algebraic Connectivity over Random Graphs

In this paper we propose a distributed algorithm for the estimation and control of the connectivity of ad-hoc networks in the presence of a random topology. First, given a generic random graph, we introduce a novel stochastic power iteration method that allows each node to estimate and track the algebraic connectivity of the underlying expected graph. Using results from stochastic approximation theory, we prove that the proposed method converges almost surely (a.s.) to the desired value of connectivity even in the presence of imperfect communication scenarios. The estimation strategy is then used as a basic tool to adapt the power transmitted by each node of a wireless network, in order to maximize the network connectivity in the presence of realistic Medium Access Control (MAC) protocols or simply to drive the connectivity toward a desired target value. Numerical results corroborate our theoretical findings, thus illustrating the main features of the algorithm and its robustness to fluctuations of the network graph due to the presence of random link failures.Comment: To appear in IEEE Transactions on Signal Processin

Improve Energy Efficiency In Cooperative Medium Access Control Protocol For Wireless Networks

Cooperative communication has drawn a substantial attention in recent years due to the efficient and optimal utilization of constraint resources in dynamic wireless networks at a reduced infrastructural deployment and cost. In the medium access control (MAC) layer perspective, two major problems are associated with cooperative networks. The ability of cooperative MAC (CMAC) protocols to achieve multi-objective target orientation limit their adaptation to the future generation of wireless networks, since most of the existing protocols focus only on a single target objective. Besides, the sustainability of energy-constrained wireless networks due to limited energy supply capacity hinders their performance to ensure stable and reliable communication. These aforementioned problems limit the adaptation of the existing protocols to fit into the future generation of wireless networks. To adequately address these problems, two distinct CMAC protocols are proposed in this thesis to cater for the unpredictable and dynamic nature of the wireless network. Firstly, a new network lifetime-aware CMAC protocol named LEA-CMAC is proposed for energy-constrained wireless ad-hoc networks. An optimization problem is formulated with an objective of extending the lifetime of the network. The solution to this non-linear problem is provided in terms of optimal transmit power at the source and relay terminals in symmetric and asymmetric transmit power policies. The solution provided by this protocol is limited in terms of energy efficiency and network lifetime since the network totally rely on the helper nodes limited-powered batteries for their transmissions. Secondly, a novel CMAC protocol with radio frequency (RF) energy harvesting (EH) capability named EH-CMAC is proposed in a reactive relaying energy-constrained wireless ad-hoc networks to address the limitation in the earlier proposed LEA-CMAC protocol. The protocol possesses the ability to ensure a sustainable and reliable wireless connectivity in a dynamic wireless environment through the selection of an appropriate transmission mode that best suits the instantaneous network requirement. The protocol comprises of two distinct energy-efficient techniques namely, the outage probability quality-of-service (QoS) requirement and the transmit power optimization techniques which are applied in both traditional and EH relaying schemes. These techniques are selected and adapted based on the instantaneous network information and target objectives. In addition, a distributed and adaptive relay selection backoff process is proposed in each case to satisfy the available network information and achieve a multi-objective target oriented protocol. Through extensive simulation and comparison with existing CMAC protocols, the results show that LEA-CMAC extend the network lifetime by 85.67% over an existing CMAC protocol, while EH-CMAC extends the network lifetime by 90.99% over a traditional CMAC protocol. Thus, both protocols achieve a multi-objective target orientation under general circumstances

A tool for rapid MAC protocols prototyping and designing for wireless sensor networks

Wireless Sensor Networks (WSNs)consists of several resource constrained sensor nodes distributed over an specific geographical area. WSNs are typically energy constraint due to the fact the sensor nodes are battery powered. Medium Access Control (MAC) protocols used in WSNs are usually designed to be power aware, i.e., they are more energy efficient than MAC protocols used for other ad-hoc wireless networks such as IEEE 802.11 [2]; to increase the lifetime of the nodes. Traditional MAC protocol implementations are done for specific hardware platforms using a monolithic approach. Therefore, it is very difficult to port from one platform to another without modifying the whole implementation protocol. This reduces code reusage and increases the implementation efforts. We have designed and implemented a toolchain which allows to design and prototype MAC protocols for WSNs in a simple manner. In addition, it allows non-specific sensors users to implement and execute them in sensor nodes without worrying about technical specifications of the platforms. The toolchain has been implemented in TinyOS using a component-based design. Special care has been taken to ensure hardware independence of the protocol implementations described in this thesis has been integrated with [1] to allow runtime reconfiguration of MAC protocols. We have evaluated our toolchain against monolithic implementations in terms of memory consumption and execution time. The results show that the toolchain introduces an acceptable memory and execution time overhead, less than 5 %, compared to the monolithic approach and substantially eases the implementation efforts