Embedded TinyOS In Wireless Sensor Network Scheduling Mechanism And Implementation

Wireless sensor network is a mode of information obtaining and processing, asthe rapid development of MEMS, wireless communication network and embeddedsystem. It owns broadly application prospects in domains of industrial, agriculture,military defense, bio-medical treatment, emergency rescue, environmental monitoringand so on. This article mainly takes TinyOS operating system as the platform ofwireless sensor network, and puts forward two advanced programs about TinyOSschedule mechanism.As the necessary software support, the operating system has the responsibility tocarry out more complex scheduling and management in wireless sensor network. It isrunning in each network node, and it’s the foundation of the top application. TinyOS,as a typical wireless sensor networks operating system, is widely used, and itsexisting scheduling mechanism adopts FCFS (first-come-first-served). But it can’tguarantee systematic respondent performance. Important tasks which can’t beexecuted reliably and timely will cause communication performance to descend.To address some shortages of the scheduling mechanism, an incremental priorityscheduling mechanism and a preemptive priority scheduling mechanism are proposed.In the incremental priority scheduling mechanism, the priorities of the tasks onwireless sensor nodes could be adjusted when inserted into the queue. Important taskswith higher priorities are executed firstly in the head of the queue. For the low-priori-ty tasks, in order to avoid the result of the high-priority tasks frequently inserted, thepriorities of tasks behind the new task are increased by one. The schedulingmechanism not only ensures the high priority of important task to be executed in time,but also guarantees that lower priority tasks will be blocked by higher priority tasksfrequently.In the preemptive priority scheduling, a high-priority task which arrives at thetask queue are executed by preemptive way more timely. In addition, low-priority taskare not preempted frequently by setting the number of the preemptions. This paperactualizes the preemption algorithm which needs no additional stack space. Thepreemptive priority scheduling, in which important tasks can be executed first bypreempting, is suitable for reliability applications.The TOSSIM simulation results indicate that at the cost of small increase in energy consumption, the two scheduling mechanisms effectively improve tasks sentand received, reduce the packet loss rate, and greatly improve the communicationperformance of sensor networks.