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In multi-interface multi-channel (MIMC) based tactical ad hoc networks, QoS support is one of the main challenging issues for multi-hop transmissions. To support QoS in such a harsh environment, we propose a novel MAC scheme to minimize multi-hop as well as per-hop delay. The current IEEE 802.11 MAC protocols should contend to reserve the channel resource at every hop by each sender. The every-hop...
There are real challenges in both the IEEE 802.11 wireless local area network (WLAN) protocol and the medium access control (MAC)-functions providing the required quality-of-service, high throughput and minimum latencies. The IEEE 802.11 layer supports both the distributed coordination function (DCF) and the enhanced DCF (EDCF). The different access categories (AC) within the EDCF can enhance the...
The MAC protocol is important, especially for wireless LAN because of limited bandwidth. A great deal of research has been carried out and some of proposed schemes are effective. Specifically, considerable effort has been devoted to improving the IEEE 802.11 standard which is utilized widely. Previous theoretical analysis gave the upper bound of IEEE 802.11 DCF throughput which is far below the channel...
In multi-hop wireless mobile ad hoc network each node is capable of sending, receiving and forwarding data packets. Since it is an infrastructure-less networks, it makes it feasible to set up at anyplace and at any time. Supporting Quality of Service (QoS) in such network is a challenge due to limited available resources like bandwidth etc. This paper describes a new approach of Medium Access Control...
A contention-tone-based wireless local area network (WLAN) protocol uses out-of-band signaling for contention resolution to achieve efficient medium access. It is shown that such a protocol can operate at near-optimal channel utilization in the medium access control (MAC) layer. This paper addresses the service differentiation design aspect of a contention-tone-based WLAN protocol. In particular,...
In this paper, the performance of traffic based adaptive (TBA) and size based adaptive (SBA) backoff algorithms for IEEE 802.11 DCF has been evaluated. TBA backoff algorithm utilizes contention status in the channel for adjusting the backoff algorithm but SBA backoff algorithm assigns different priority levels based on packet size to traffic loads which is involved with best effort and real time traffic...
In this paper, size based adaptive backoff algorithm (SBA backoff algorithm) for IEEE 802.11 DCF has been developed to provide quality of service (QoS) requirements. SBA backoff algorithm assigns different priority levels based on packet size. Also, SBA backoff algorithm was utilized in the mobile ad-hoc network (MANET), which is a collection of mobile independent nodes. Because of dynamic topology,...
In this paper we investigate the problem of providing QoS within IEEE 802.11 EDCA ad-hoc networks. Our study shows that a strong unfairness in medium access between certain nodes may appear. It also shows that the possible unfairness is dependent on the actual placement of nodes. Furthermore, the inability of the four-way handshake mechanism to improve the performance of the analyzed networks is also...
Although the existing QoS-supported MAC Protocols can provide QoS guarantee at some degree, most of them sacrifice the performance of best-effort traffic. An adaptive QoS-supported backoff mechanism for MAC Protocol is proposed, in which nodes can adjust their backoff algorithm according to the network load state they measured. So the proposed adaptive backoff algorithm can improve the link utility...
In current trends, the central target of interest for multimedia applications is to meet the stringent quality of service (QoS) requirements for traffic flow over contention based MAC protocol of IEEE 802.11 WLAN. To achieve this objective, our paper proposes a connection admission control (CAC) policy, which attempts to maintain the flow of incoming traffic in the wireless network so as to effectively...
In this paper, we propose to add a new queue in IEEE 802.11 MAC protocol for real-time multimedia traffic in wireless LAN. The queue contributes to improving multimedia service quality by reducing end to end delay, a QoS parameter. To control two queues, we use a scheduler based on the PAD algorithm which selects a packet from one of two queues appropriately for forwarding. Moreover, we adapt the...
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