Real-time IP applications such as IP telephony, IP video streaming, and transport of time-sensitive information need predictable network resources. Examples of network resources include minimum guaranteed bandwidth, and special processing of certain types of packets at points of congestion, regardless of traffic fluctuations in the network. Support for such applications in mobile ad-hoc networks requires acceptable channel conditions, QoS aware mechanisms for channel access, identification of transit nodes that can sustain the resulting traffic, as well as measures for congestion prevention and management at the nodes. This paper provides a framework for QoS support in Mobile ad-hoc IP networks, and discusses methods to enable QoS aware media access control, and routing IP packets with QoS constraints.in the direction from one node to another is roughly similar to the bandwidth available in the reverse direction. Discussion in this paper is limited to unicast transmission of packets, and support for multicast will be addressed in a future paper. MANETS are expected to carry tactical Internet traffic on poor quality radio circuits, i.e., channels with high biterror rates (BER). In addition to Gaussian background noise, channel errors may also be caused by factors such as impulsive noise, signal fading, unintentional interference from other users of the band, and intentional enemy jamming. Clearly, for tactical communications, performance over a wide range of channel conditions is essential. One of the characteristics of MANETS is that they are bandwidth limited, and the available bandwidth is subject channel impairments. The latter induces the use of redundant codes, which further reduces the available bandwidth. When channel impairments reach beyond a certain threshold, coding methods alone do not suffice to ensure transmission. Such a threshold is identified as a
1.INTRODUCTIONAs real-time applications find their Way into the Internet, efforts to SUPPOrt QOS in Ip networks have intensified. Approaches range from allocating resources to individual flows, to throwing "enough bandwidth" to the problem. Mobile networks in general, mobile ad-hoc networks (MANET) that transport military applications in particular, have very distinct characteristics that require specialized solutions for QoS support. In this paper, we review components of an overall architecture to support QoS, and propose a solution specialized for MANETS. I n this paper, we assume that applications have the ability to request appropriate network resources, and to indicate it by generating specific packets, and/or marking the packets that carry the application content. We also assume that the links are bi-directional, and that the bandwidth available BER of in [CANS]. When the BER reaches beyond such a threshold, it would make sense to declare that particular link unreachable, and seek an alternate path. Another characteristic of MANETS is that there is contention from multiple users in inserting each packet into the shared transmission link. Thus, a ...