Motivated by the poor experimental scaling reported in a study of the performance of ad hoc networks in [15], we propose a new protocol for media access control in ad hoc networks. Our protocol seeks to avoid collisions without making explicit reservations for each and every packet. The key idea is to employ a random schedule which is driven by a pseudo-random number generator. By exchanging the seeds of their pseudo-random number generators within a two-hop neighborhood, the nodes effectively publish their schedules to all hidden as well as exposed nodes. This allows each node to opportunistically choose transmission slots. This scheme can also be employed during the reservation phase of a protocol such as IEEE 802.11. Throughput calculations and simulation results are presented.

Purpose of this paper. Survey of wireless network features and how they perform. New MAC protocols. Conclusions. Shortcomings of the paper, future work.

Abstract—Real-time multimedia applications necessitate predictable network resources. Quality of Service (QoS) support for such applications in mobile ad hoc networks (MANETs) requires acceptable channel conditions, QoS-aware mechanisms for channel access, identification of proper forwarding (transit) nodes, as well as measures for congestion prevention and management in those nodes. This paper proposes a new QoSaware medium access control (MAC) protocol that takes the above requirements into consideration. This novel protocol is based on the legacy IEEE 802.11, and thus can be easily integrated into existing systems without much difficulty. Simulation results confirm that our approach results in improved throughput for real-time periodic traffic, while providing deterministic delay performance.

This chapter deals with the problem of designing and effectively utilizing wireless communication channels. Since the wireless medium is inherently a shared resource, controlling channel access becomes a central theme that determines the fundamental capacity of the wireless network and has a dramatic impact on system complexity and cost. Therefore, our primary focus will be the design and implementation of Media Access Control (MAC) protocols for mobile wireless networks.

This paper proposes a new QoS-aware medium access control (MAC) protocol in mobile ad hoc networks (MANETs). This takes the unique challenges of MANETs into consideration, and works in conjunction with the location-based forwarding strategy. This novel protocol is based on the legacy IEEE 802.11, and thus can be relatively easily integrated into existing systems. It is adaptive and network-aware depending on the type and intensity of traffic, and relative mobility patterns of nodes. In addition, it makes use of the pointcoordination-function (PCF) of IEEE 802.11 in a distributed fashion for the first time in multihop MANETs. Our strategy enables two-way admission control for improved performance, whereby the forwarder-node selection algorithm allows previous hop nodes to perform implicit admission control using locally available information, while a selected forwarder-node performs explicit admission control depending on its current load. Analytical results confirm the performance improvement of our strategy. I.

2.1 Carrier Sense Multiple Access and IEEE 802.11.......... 4