courseware System-level Modeling for Wireless Sensor Networks Jan Madsen Informatics and Mathematical Modelling Technical University of Denmark Richard Petersens Plads, Building 321 DK2800 Lyngby, Denmark

SoC-MOBINET coursewareJan Madsen2 Sensor networks? The Hogthrob project  Developing a sensor network infrastructure for sow monitoring  Functionalities  Tracking  Detecting heat period ……  Low Cost (~1 €)  Low Energy (2 years lifetime)  Consortium:  DTU, DIKU, KVL  National Committee for Pig Production  IO Technologies The real HOGTHROB

SoC-MOBINET coursewareJan Madsen3 sending receiving idle Sensor networks CSPCSPCSPCSPCSPCSP

SoC-MOBINET coursewareJan Madsen4 receiving sending idle Sensor networks CSPCSPCSPCSPCSPCSP

SoC-MOBINET coursewareJan Madsen5 Sensor node rtos battery cpu radiosensor sensing processing communicating CSP

SoC-MOBINET coursewareJan Madsen6 Sensor node  Ultra low energy  Low flexibility  Ultra low cost (1$)  Small size (1..10 Mtr)  Low clock frequency  DSP and RF dominated  Limited memory  Hardware/software codesign rtos battery cpu radiosensor

SoC-MOBINET coursewareJan Madsen7 Sensor node design rtos cpu radiosensor battery sensing processingcommunicating rtos cpuasic sensor radio

SoC-MOBINET coursewareJan Madsen8 Sensor network model

SoC-MOBINET coursewareJan Madsen9 Sensor node: Uni-processor... rtos a Framework to experiment with different RTOS strategies Focus on analysis of timing, energy and resource sharing Abstract software model, i.e. no behavior/functionality Easy to create tasks and implement RTOS models Based on SystemC

SoC-MOBINET coursewareJan Madsen10 System model rtos a

SoC-MOBINET coursewareJan Madsen11 System model rtos

SoC-MOBINET coursewareJan Madsen12 System model rtos

SoC-MOBINET coursewareJan Madsen13 System model  Task messages:  ready  finished  RTOS commands:  run  preemept  Resume rtos

SoC-MOBINET coursewareJan Madsen14 System model - SystemC pa = new task("task_a",1,50,3,12,0,ready); registerTask(pa); pb = new task("task_b",2,40,2,10,0,ready); registerTask(pb); pc = new task("task_c",3,30,1,10,0,ready); registerTask(pc); rtos identifier period priority offset WCET

SoC-MOBINET coursewareJan Madsen15 Link model  Aim: Adding tasks without having to create seperate communication links  Uses the SystemC master- slave library  If two tasks send a message at the same time – they are executed in sequence, but in undefined order  Global ”clock” is used to keep track of time rtos clock

SoC-MOBINET coursewareJan Madsen16 Task model r1r1 r 1 = time at which task becomes released (or active) e1e1 e 1 = worst case execution time (WCET) d 1 = deadline, task should complete before this! d1d1 s1s1 s 1 = time at which task starts its execution T1T1 T 1 = period, minimum time between task releases 1 o 1 = offset (or phase) for first released o1o1

SoC-MOBINET coursewareJan Madsen17 Task model

SoC-MOBINET coursewareJan Madsen18 Sensor node model

SoC-MOBINET coursewareJan Madsen19 Energy modeling

SoC-MOBINET coursewareJan Madsen20 Communication example   s     r   Send node Receive node synch. allocator scheduler synch. allocator scheduler Wireless Network  

SoC-MOBINET coursewareJan Madsen21 Modeling radio communication csbo cs Txp Txd send idle Modeling the CSMA protocol idle carrier sensepreambledata CPU Transiver Protocol Sender:

SoC-MOBINET coursewareJan Madsen22 CSMA Protocol for sending idle back off carrier sense Tx pre- amble Tx data send !send bo_counter>0 bo_counter==0 !channel clear channel clear & cs_counter==0 cs_counter>0 pr_counter>0 pr_counter==0 data_counter>0 data_counter==0

SoC-MOBINET coursewareJan Madsen23 Modeling radio communication csbo cs Txp Txd carrier sensepreambledata CPU Transiver Protocol Sender: pollidlepollidlepollsyn Rxd poll channelsynchronizedata CPU Transiver Protocol Receiver:

SoC-MOBINET coursewareJan Madsen24 Sensor network example

SoC-MOBINET coursewareJan Madsen25 Example 1: Simple broadcast Application task 0 = idle 1 = ready 2 = running 3 = preempted 4 = self-preempted Sending task 0 = idle 1 = back-Off 2 = carrier sensing 3 = transmit preamble 4 = transmit data Receiving task 0 = idle 1 = polling 2 = synchronize 3 = receive data

SoC-MOBINET coursewareJan Madsen26 Example 2: Radio interference Application task 0 = idle 1 = ready 2 = running 3 = preempted 4 = self-preempted Sending task 0 = idle 1 = back-Off 2 = carrier sensing 3 = transmit preamble 4 = transmit data Receiving task 0 = idle 1 = polling 2 = synchronize 3 = receive data

SoC-MOBINET coursewareJan Madsen27 Example 3: Network routing

SoC-MOBINET coursewareJan Madsen28 Example 3: Routing Application task 0 = idle 1 = ready 2 = running 3 = preempted 4 = self-preempted Sending task 0 = idle 1 = back-Off 2 = carrier sensing 3 = transmit preamble 4 = transmit data Receiving task 0 = idle 1 = polling 2 = synchronize 3 = receive data

SoC-MOBINET coursewareJan Madsen29 Example 3: Battery shortage Application task 0 = idle 1 = ready 2 = running 3 = preempted 4 = self-preempted Sending task 0 = idle 1 = back-Off 2 = carrier sensing 3 = transmit preamble 4 = transmit data Receiving task 0 = idle 1 = polling 2 = synchronize 3 = receive data Node 2 runs out of battery

SoC-MOBINET coursewareJan Madsen30 Summary  SystemC based framework to study the dynamic behavior of a sensor network  Exploring global effects of sensor node design  Example sensor network based on Mica-nodes and TinyOS from UC Berkeley  Work in progress  Power/energy models for power management  Mobile sensor nodes  Detailed component models  To be used in the Hogthrob project