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To solve the problems of control channel bottleneck and communication delay in multi-radio wireless sensor networks, this paper designs an asynchronous MAC protocol named UMD2-MAC in which a union mechanism of prime channel hopping(PCH for short) and control-channel reservation is used. The channel hopping makes sure that the average delay of selecting the same channel is small while the reservation...
The use of directional antennas in support for ad hoc communications has increased significantly since these antennas provide throughput gain and increase space division. Most of the proposed directional MAC protocols in the literature rely on the use of control frames - such as RTS/CTS - for channel reservation and to reduce the collision probability of data frames. However, RTS/CTS control frames...
The IEEE 802.11 Distributed Coordination Function (DCF) does not require the presence of a central controller or access point. It is therefore, the standard protocol used for resolving medium access contention in mobile ad hoc networks. IEEE 802.11 DCF is based on carrier sense multiple access with collision avoidance and Binary Exponential Back off Algorithm (BEBA). BEBA can improve the system throughput...
In this paper we study the interactions of TCP and IEEE 802.11 MAC in Wireless Mesh Networks (WMNs). We use a Markov chain to capture the behavior of TCP sessions, particularly the impact on network throughput performance due to the effect of queue utilization and packet relaying. A closed form solution is derived to numerically determine the throughput. Based on the developed model, we propose a...
A good approximate analytical formulation of the saturated throughput of a Cooperative MAC (CoopMAC) is presented via a two-dimensional discrete-time Markov chain rather than using an approximation. A helper node is used to relay packets from the source node to the destination node within a coverage via a faster two-hop link if possible. The analytical model is formulated with a number of data rates...
Analytical formulations of the throughput of cognitive multi-channel MACs with perfect and imperfect sensing are presented. Both imperfect concurrent sensing and imperfect sequential sensing schemes are considered. A discrete time Markov chain is used to model the number of communicating node pairs in the MAC protocols. The throughput of the MAC protocol with perfect sensing is expressed as a function...
Analytical formulations of the throughput of multi-channel medium access control (MAC) protocols are presented. Both multi-channel multi-rate MAC and multi-channel CoopMAC protocols are considered. A discrete time Markov chain is used to model the number of nodes communicating with the AP in the multi-channel multi-rate MAC protocol, while another discrete time Markov chain is used to model the number...
Since the IEEE 802.11 standard supports multiple data rates at the physical layer, many rate adaptation mechanisms have been proposed to utilize this multi-rate capability by dynamically switching rates in response to different channel conditions. In IEEE 802.11b networks, the guarantee of an equal transmission opportunity for all participating nodes results in performance anomaly. Traditional solutions...
In this paper, a random access protocol for quality of service (QoS) support targeted for medical wireless body area sensor networks (WBASNs) is proposed. In this proposal, the sensor nodes are classified into nodes of life-critical health information, and nodes of non-critical health information. The proposed QoS-based MAC protocol prioritizes the critical packets access to the transmission medium...
IEEE 802.11 distributed coordination function (DCF) medium access control (MAC) does not provide airtime fairness for all stations in a multi-rate scenario as it only provides max-min throughput fairness. This gives rise to the rate anomaly problem where the maximum throughput is limited by the slowest transmitting station. In our paper, we propose airtime fairness in a rate separation IEEE 802.11b...
Wireless access in vehicular environment (WAVE) architecture of intelligent transportation system has been standardized in the IEEE 802.11p specification. The WAVE network supports the features of multi-rate and multi-channel and it is going to be widely deployed in realistic roadway environments in order to provide traffic information and convenient services. However, the adopted contention-based...
In many space communication scenarios high priority space traffic is received by a ground antenna and retransmitted via a ground link to a ground asset. In most instances this ground link supports multiple communication streams concurrently, and needs to multiplex the space traffic with these streams using a certain MAC layer protocol. By design, such MAC layer protocols will add a certain random...
Dynamic spectrum access can enable secondary network users to access unused spectrum, or whitespace, which is found between the transmissions of primary users in a wireless network. The main design objectives for secondary user access strategy are to be able to "scavenge" spatio-temporally fragmented whitespace opportunities while limiting the amount of interference caused to the primary...
Dynamic spectrum access can enable secondary network users to access unused spectrum, or whitespace, which is found between the transmissions of primary users in a wireless network. The main design objectives for secondary user access strategy are to be able to ??scavenge?? spatio-temporally fragmented whitespace opportunities while limiting the amount of interference caused to the primary users....
This paper analyzes the performance of enhanced relay-enabled distributed coordination function (ErDCF) for wireless ad hoc networks under transmission errors. The idea of ErDCF is to use high data rate nodes to work as relays for the low data rate nodes. ErDCF achieves higher throughput and reduces energy consumption compared to IEEE 802.11 distributed coordination function (DCF) in an ideal channel...
In wireless ad hoc networks, the performance of the media access control (MAC) protocol has significant impact on the overall network performance. In contention-based MAC protocols, nodespsila access to the shared channel is not synchronized, and they contend for the channel whenever there are packets in their buffers ready to be sent. To reduce self-contention, Fast-Forward Mechanism and Quick Exchange...
Wireless LANs have achieved a tremendous amount of growth in recent years. During this time, user requirements have evolved, so it is necessary to have differentiation mechanisms in the access networks to achieve user requirements. WLAN standard IEEE 802.11 doesn't provide any differentiation between different services to achieve throughput and delay requirement, this paper propose a new modification...
A mobile ad hoc network is a network without any infrastructure or service access points. In wireless ad hoc networks, the performance of the media access control (MAC) protocol has significant impact on the overall network performance. In contention-based MAC protocols, nodes' access to the shared channel is not synchronized, and they contend for the channel whenever there are packets in their buffers...
The spectrum resource gets scared with the development of wireless communication. Users in cognitive wireless mesh network need to switch among multi-channels to communicate. In this paper, we propose a mathematical model of multi-channel DCA protocol in cognitive wireless mesh network. This model is based on Bernoulli and M/M/K queuing model. From the validation by compare simulation with analytical...
Channel Utilization is a performance index to measure the protocol efficiency of a WLAN medium access control (MAC). This paper presents a simple method to achieve maximum channel utilization for the IEEE 802.11n using basic Distributed Coordination Function (DCF). We find that the channel utilization only depends on the number of stations for the IEEE 802.11n with a given maximum aggregated frame...
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