In multi-monitoring-task mobile sensor networks,different monitored objects have different requirements for real-time transmission.To satisfy those requirements,a multi-layered real-time data routing protocol (MRDR) was proposed to satisfy the requirements of both soft real-time and hard real-time monitoring.In MRDR,a layer mechanism was introduced into mobile sensor networks and the network was divided into layers with equal width.For ordinary event messages with higher delay tolerance,MRDR could enable messages to be forwarded to the sink at as low energy consumption as possible.For emergent event messages with lower delay tolerance,MRDR could send messages to the sink by multi-hop real-time transmission.At the same time,for the problem of energy holes in hard real-time routing,a backward mechanism was proposed to enable emergent event messages avoiding node holes and finally be transmitted to the sink.At last,to reduce message redundancy,message queue management was designed and the principle for discarding messages was presented when the queue was full.To evaluate the performance,simulation was carried out to compare MRDR and other three algorithms in terms of network lifetime,average delivery ratio and average delay.The result proved the efficiency of MRDR.In different network environments,MRDR could effectively be applied to multi-monitoring-task mobile sensor networks and satisfy different requirements of different real-time transmissions.%在多监控任务移动传感器网络中,不同的监控对象对数据传输实时性有着不同的要求.为满足监控数据不同的实时性要求,提出了既能满足软实时监控要求,也能满足硬实时监控要求的多级分层实时数据路由协议MRDR (layer-based multilevel real-time data routing protocol).MRDR协议将分层机制引入移动传感器网络,将网络分成宽度相等的若干圆环.对具有实时性要求更低的普通事件消息,MRDR在消息失效前以尽量低的能耗将消息转发至sink节点.对于实时性要求更高的紧急事件消息,MRDR让消息以层间多跳方式实时传输到sink.同时,针对硬实时路由过程中的节点空洞问题,提出了消息回传机制,使得紧急事件消息能绕过节点空洞并最终传输至sink.最后,为降低网络中的消息冗余,设计了消息队列管理机制,给出了队列满时的消息丢弃原则.为评价算法性能,仿真实验对比了MRDR与其他3种算法在网络寿命、数据传输成功率与消息平均延迟方面的表现,结果验证了算法的有效性.在不同的网络环境下,MRDR算法能有效适应多监控任务移动传感器网络,满足具有不同实时性要求的不同消息的传输要求.
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