CROSS-LAYER QOS DESIGN: OVERCOMING QOS-UNAWARE SLOT ALLOCATION

Layer 2 radio resource allocation schemes being used in mobile ad hoc networks (MANET) do not always take into account the Quality of Service (QoS) requirements of network traffic. As an example, the current USAP (Unifying Slot Assignment Protocol) slot allocation scheme is QoS-unaware. Consequently the scheme could grant available slots to lower priority traffic instead of higher priority traffic. This greatly reduces the effectiveness of QoS management schemes at other layers of the protocol stack (e.g. DiffServ at layer 3, and admission control at the application layer). We describe a cross-layer solution to this problem where a Local QoS Control (LQC) component is placed on every node. The LQCs on nodes in a channelized neighborhood share their per traffic class radio resource needs, enabling the LQC at each node to determine its urgency for additional slots comparing to that of other nodes in the neighborhood. Thus, in nodes that have a less urgent need for slots, the LQC can filter local application traffic to reduce the local demand for slots, which in turn helps those nodes with more urgent need to have a better chance securing additional slots. A description of the approach and a performance analysis is presented.