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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...
UWB technology has offered a huge application bandwidth and its bandwidth has been reached up to Gbps recently. One of the various UWB specifications, WiMedia Alliance's MAC and PHY can also be used for high-speed multimedia applications to establish wireless video area network (WVAN). In this paper, we propose a gigabit UWB video transmission system for WVAN. To guarantee Gbps operation, we implemented...
The increasing use of wireless networks and the constant minituarization of electrical devices has empowered the development of body area networks (BAN). The BAN for medical applications cover continuous waveform sampling of biomedical signals, monitoring of vital signal information. In order to fulfill the diverse medical applications, these networks have to follow stringent technical requirements...
The primary responsibility of a medium access control (MAC) protocol in Ad hoc Network is the distributed arbitration for the shared channel for transmission of packets. The performance of Ad hoc Network depends upon the sincerity of the MAC protocol. The MAC protocol of this type of network should be distributed, faired & free from hidden and exposed terminal problem. It should also support real-time...
A goal for next generation mobile networks is to provide seamless personal mobile communication and improved quality of service (QoS). Fair, class based service and lossless handoff are a focus for improving QoS. The research presented in this paper proposes a scheduling mechanism for providing improved QoS in mobile broadband Internet Protocol (IP) high-speed downlink packet access (HSDPA) networks...
The primary concern of broadband wireless technologies is to provide the end-to-end Quality of Service (QoS) for integrated real-time and non real-time applications. The main focus of the IEEE 802.16d/e MAC layer is to manage the radio recourse in an efficient way. The basic functional blocks of the QoS model are addressed by the standards to support five different types of service classes. However,...
It is difficult to provide QoS guarantees for streams in wireless network based on IEEE802.11 DCF because of limited bandwidth. Taking CBR traffic as example, we studied the traffic performance with different parameters in this paper. The results show that for an overloaded network, the traffic with longer packet size has greater throughput. Since the MAC layer performs the same competitive algorithm,...
The bandwidth in wireless networks is usually shared by a number of wireless nodes. The channel capacity depends on the number of accessing nodes, time, environmental conditions and location of nodes. Due to varying channel conditions, several issues are observed in the transmission of real time multimedia. The existing research on multimedia streaming can be classified into adaptation techniques...
One of the major concerns in wireless sensor networks (WSNs) is improving the network lifetime. This paper addresses the problem of energy saving in an IEEE 802.15.4a large-scale full mesh WSNs based on UWB technology. It presents a network architecture to facilitate resource sharing and to ensure load and energy balancing. With a particular focus on medium access control (MAC) protocols, we propose...
Multimedia communications over the Internet have undergone considerable growth in recent years thanks to various mature technologies. However, the well-known wireless standard IEEE 802.11 cannot provide adequate bandwidth and jitter for multimedia communications. In this paper, a dual-mode access scheme with QoS features is proposed to solve the asymmetric link problem resulting from the 802.11 distributed...
The IEEE 802.16 standard defines MAC and physical layer protocols for broadband wireless access, however it does not specify any scheduling algorithm. In this paper, we propose a RED-based Weighted Fair Priority Queuing algorithm for inter-class scheduling and a channel aware algorithm for intra-class scheduling. Weights of the service classes are adaptive according to the QoS requirements of each...
Spectrum scarcity and underutilized frequency bands are the most challenging wireless networking problems in the last decade. Cognitive radio (CR) is the promising solution for these two problems. We propose a protection and fairness oriented cognitive radio MAC protocol (PROFCR) for ad hoc networks. PROFCR allows secondary users (SU) to utilize the unused and underutilized frequency bands while bounding...
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...
The collision probability experienced by each node on a link plays an important role in estimating the available bandwidth at the Medium Access Control (MAC) layer. The available bandwidth is a crucial information to the decision made by Admission Control for QoS support in wireless networks. Most of existing Admission Control schemes proposed for wireless Ad-Hoc networks neglect the fact that collision...
The IEEE 802.15.4 standard defines physical layer and medium access control (MAC) layer protocols for the low rate wireless personal areas network (LR-WPAN). The analytical models of 802.15.4 MAC have been primarily developed under the assumptions of the ideal channels or uniform error channels which fail to capture the characteristics of bursty and correlated channel errors in the practical wireless...
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, we evaluate the throughput performance of Hybrid Automatic Repeat reQuest (HARQ) protocols using Adaptive Modulation and Coding (AMC) based on either the instantaneous Signal to Noise Ratio (SNR) or the average SNR. We also propose a cross layer optimization algorithm in order to offer the highest throughput at the physical (PHY) layer and verify some Quality Of Service (QOS) constraints...
IEEE 802.11 Wireless Local Area Network (WLAN) is one of the most widely deployed wireless network technologies in the world today. However, 802.11 MAC algorithm is unable to support modern multimedia applications which require certain level of quality of service (QoS) guarantees in terms of consistent, timely and reliable data transfer. The 802.11e MAC protocol provides extension for adjustment of...
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