Accurate Emulation of Wireless Sensor Networks Hejun Wu

Accurate Emulation of Wireless Sensor Networks Hejun Wu Joint work with Qiong Luo, Pei Zheng*, Bingsheng He, and Lionel M. Ni Department of Computer Science The Hong Kong University of Science & Technology, China *Arcadia University, USA

Wireless Sensor Networks (WSNs) Proxy User Client Sink Sensor mote

Wireless Sensor Networks (WSN) Proxy User Client Sink Sensor mote Query

Wireless Sensor Networks (WSN) Proxy User Client Sink Sensor mote Query Result

Motivation of VMNet ► Substitute for sensor § Easy to handle § Low price ►A nodes in research realistic & controllable environment § Debugging § Testing § Evaluating Performance Applications Network protocols OS Drivers ► Parameter setting § Simulation § Modeling and validation for

VMNet architecture

Components in a VM Virtual mote Virtual CPU Virtual UART( In Virtual Sink) Virtual sensor board Virtual clock Virtual radio frequency module Virtual socket EM (Emulation Manager) Real mote binary code Virtual main board

Virtual Radio Channel To VRFM From VRFM Bits Bit error Module Collision signal to VRFM Collision Module Queue UDP packet from other VMs via LAN Delay Module UDP packet to other VMs via LAN Control messages To/From Network Manager (NM)

Key Features of VMNet ► Open architecture § Easy to transform to other WSN hardware emulation ► Detailed emulation § CPU instructions § Operations of the components ► CPU, ► Accurate Sensor and Radio running status logs § Accurate time emulation ► Granularity: microsecond level § power consumption evaluation

Open architecture design ► Conflict between generality & accuracy § Generality is desirable ►Ability to emulate various WSNs § Accuracy ►Close ► Highly to the specified target WSN modularized structure of a VM § Ensures the reusability ► Virtual socket in a VM § Uniform interface between modules

Highly modularized structure Virtual mote Virtual CPU Virtual UART( In Virtual Sink) Virtual sensor board Virtual clock Virtual radio frequency module Virtual socket EM (Emulation Manager) Real mote binary code Virtual main board

Performance Evaluation on Applications of WSNs ► Based on the fact that § Operation and time can be deduced by ►Instructions executed by the CPU in a sensor mote ►An instruction always takes constant time ► VMNet approach in performance evaluation § Logging and reporting ► Operations and time

Logging in VMNet ► The operations : ► VMNet logs § Running states ► the operations of each component (e. g. III) § CPU clocks ► describe the start time and end time A fraction of a VMNet log Running states Time (In terms of CPU clock cycles) III 1926031985 IIR 1926032167 CIR 1926034874 The operations of components CPU Sensor Radio Compute ( C) Acquire (A) Transmit (T) Idle (I) Receive(R) Hibernate ( H) Power down (P) Control(C) Idle(I) Power down (p)

Conclusion ► Detailed emulation § Useful for many areas in a WSN ►Architecture, processing. OS, and sensor network query § Provides ►parameter ► and validation for simulation & modeling Performance evaluation § Especially valuable for query processing ►Query Optimization: § choose a query plan with minimum energy and time cost ►Query processor benchmark study

Future Work ► Power consumption evaluation ► Work in progress § Scalability § Mobile WSN emulation § Graphical Interface for VMNet ► In the near future § Use multiple PCs to emulate a WSN