Application

1. EbT CtS Distributed Source Coding of Correlated Data from Image Sensors Conclusions and Future Work X1 X2 BSC p Non-uniform Channels X1 Correlation X2 Channel Rn Systematic (X2 ,PX2 ) X2 X2 Channel Decoder n Encoder k PX2 P'X2 Wireless Rate R Channel (1-R)n Energy-Efficient Data Gathering in Sensor and Actor Networks: A High Bit-rate Image Sensing Application Rajnish Kumar, Mina Sartipi, Junsuk Shin, Ramanuja Vedantham, Yujie Zhu, Faramarz Fekri, Umakishore Ramachandran, Raghupathy Sivakumar Application Mutual Exclusion for Command Delivery from Base Station to LED Array Actors Heterogeneous wireless sensor and actor network consisting of mica2 motes with light sensors, LED array actors, IPAQs with image sensors (cameras), where • Light sensors report the light readings periodically to the Base Station (BS) • LED array actors are turned on based on the light readings • Base station sends a command to cameras to turn on the camera after LED arrays are on • Cameras send the image data to the BS Minimize the total number of transmissions for the three phases for energy-efficient communication Motivation: Motivation: • Image sensors have correlated data. • Distributed source coding can exploit correlation structure with low power algorithms • Need for mutual exclusion in the acting ranges of the LED arrays • Mutual Exclusion in WSANs: Execute a given command exactly once (or desired number of times) for any particular location irrespective of the distribution of actors • Relaxed Definition: Choose a minimal set of actors such that the overlap between acting regions is minimal Correlation Model: Goal: X1, X2 : I.I.D binary sequence; Prob [ Xi =0 ] = Prob [ Xi=1 ] = 1/2. Prob [ X1≠ X2 | X1 ] = p Illustration of Mutual Exclusion: • Definitions for illustration • Rm: Region covered by set of actors already included as part of actor cover • ri and rj: New area covered by actor i and j respectively • ni and nj: New overlap area for actor i and j respectively • oi and oj : Old overlap area for actor i and j respectively Distributed Source Coding: X1 and X2 have correlated information. Goal: Compressing X2: • Without communicating with X1 • With the knowledge that X1 is present at the decoder Modeling Distributed Source Coding with Parallel Channels: Sensor Stack with Cross-layering support for efficient Image sensor placement Energy-efficient communication strategy from Light sensors to Base Station Motivation: Motivation: • Cross-layering can help in better camera placement for the application considered • Without cross-layering, there is information overlap across layers • Modules make inefficient decision • DFuse application needs routing information to decide about role migration • Need for energy-efficient communication from light sensors to sink • Traditional communication strategy conveys information between the sender and the receiver using energy (EbT) only • Energy consumption is keb, where k is the length of the bit-stream and ebis energy per bit • Can we use time as an added dimension to convey information? Use non-uniform LDPC code for channel coding. Sensor Stack without Cross-layering support: Conclusions: • Energy savings for distributed source coding: 40% • Energy savings for cross-layer support: 110% • Energy savings for energy-efficient communication: 88% • Energy savings for Mutual exclusion for LED array actors: 55% • Overall expected energy savings: 88 + 55 + 110+ 40 = 293% Communication through Silence (CtS): • A new communication strategy that conveys information using silent periods in tandem with small amount of energy • The energy consumption for CtS is always 2eb irrespective of the amount of information being sent Future Work: • Distributed source coding for image sensors • Implement the algorithm on image sensors to evaluate energy saving benefits • Cross-layer support for image sensor placement • Implement the IES architecture for the heterogeneous testbed for data fusion • Energy-efficient communication from light sensors to the BS • Implement CtS communication strategy from light sensors to the BS • Mutual exclusion for LED array actors • Implement mutual exclusion on LED arrays to minimize energy consumption Sensor Stack with Cross-layering support: • Information Exchange Service: • Efficient use of limited memory • Simple interface for information sharing • Extensibility • Asynchronous delivery • Complex event notification