Simulation Model for Evaluation of Distributed Processing in Multi-Hop PacketRadio Networks

摘要

This paper describes a simulation model developed to aid in the evaluation ofdistributed processing scenarios in a highly dynamic environment such as a multi-hop packet radio network. The simulation model has a set of (user selectable number of) identical packet radio nodes, employs spread spectrum random access protocols, and has an error model that includes the effects of interference from concurrent transmissions as well as that induced by an on-off partial band jammer. An abstract description of a typical distributed processing scenario with hierarchical primary and subtask structures has been devised wherein a distributed task is described by a 'script' that specifies processing time, sequences of subtasks (distributed over other nodes) and lengths of request and response messages. A distributed task consists of a primary task and a hierarchy of one or more subtasks, hosted at one or more packet radio nodes and is initiated by receiving a request message from some other node. When all the subordinate subtasks are complete, the subtask sends its response message to the initiating node. As the distributed application depends on reliable communication, some transport functions such as end-to-end acknowledgments and a limited number of retransmissions per packet are also included. We obtained some numerical results through preliminary runs of the simulation model.