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Cross-Layer Optimization for Wireless Sensor Networks Yuecheng Zhang, Liang Cheng LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University Target Applications Local data exchanging system Global data collecting system Remote lab, environment sensing, and etc. Sensor network and robot collaborative system Multi-hop Local Positioning System (MLPS) Large constructions’ automatic examination Robot + Sensor network + Multimedia streaming Sensor network and human-being collaborative system Firefighting aids, smart battlefield and etc. LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University Important Issues Network Scale Cost vs. Budget Throughput vs. Bandwidth System Lifetime Power consumption vs. Power supply Existing solutions Low power hardware design Transmission power/range control Power-aware protocol stacks Power saving working modes Node Versatility Functionality vs. Resource constraints Functionality: collecting, storing, processing, fusing, relaying Constraints: computing power, storage, specific device and etc. LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University Optimization Goals Enable large scale networks Lengthen system lifetime Low cost High efficiency Improve power efficiency Prevent system deconstruction Support node versatility Multiple functionality Multiple applications LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University Why Cross-Layer Possibility Optimization goals can be pursued in multiple layers layered optimizations assume cross-layer cooperation Some applications do not need all layers Multi-hop Local Positioning System (MLPS) Necessity Optimizing single layer is not enough Optimizations may be conflict with each other One-for-all consolidate design for feasible applications LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University Why Cross-Layer (Cont.) Network Scale System Life-time Node Versatility Upper Layers Data fusion Compression Power-aware working mode Control Load-aware working mode decision Transport Layer Network Layer QoS (Bounded Delay) QoS-power tradeoff Load-aware transportation control Node naming Efficient routing Node discovery Power-aware routing Reduce overhead Load-aware routing Simplified discovery Distributed storage MAC Layer Physical Layer Contention control Channel reuse Synchronized sleep Transmission range control Load-aware channel allocation Ultra Wide Band Low power design LONG Lab: http://long.cse.lehigh.edu Powerful battery CSE Department Lehigh University Attach specific accessories (GPS) Why Cross-layer (Cont.) Heterogeneity Intra connection vs. Inter connection Scalability Correctness verification Reusability Code reuse Module reuse General purpose sensor networks LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University Current results Networking layer Data-Link layer Efficient broadcasting MAC Time synchronization module Self-nominating Floossiping LESSAR (LEvel Synchronization by Sender Adjuster and Receiver) Positioning module PLACE (Power-based Location And Coordination Estimation) LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University Self-Nominating CT(B)=10 Ready->Rcvd CT(B)=3 Rcvd B CT(C)=9 Ready->Rcvd C CT(C)=2 Rcvd->Ready D CT(E)=12 Ready->Rcvd C E CT(D)=7 Ready->Rcvd A B E A CT(F)=9 Ready->Rcvd D F F CT(D)=0 Rcvd->Sent Advantages: Robust Flexible B Ready C Disadvantages: CT(E)=12 Rcvd A Artificial random delay LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University Sent D E CT(F)=9 Rcvd F Future tasks Do some theoretical study on the system limitations System Throughput & Network Scale Node Synchronization and Positioning accuracy Channel allocation and Mode decision Identify and justify feasible application models Implement the applications Complete the protocol stacks Tune the protocols and functional modules Optimize the applications Developing the research platform LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University The End Questions? LONG Lab: http://long.cse.lehigh.edu CSE Department Lehigh University