4 Introduction Carrier-sensing Range Network Model Distributed Data Collection Simulation 6 Conclusion 2
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Centralized algorithms vs. Distributed algorithms in WSNs Challenges in Distributed and asynchronous data collection C1: only local information is available C2: how to avoid disadvantages introduced by time asynchronization C3: how to theoretical analyze a distributed and asynchronous data collection algorithm Contributions Derive a under the generalized physical interference model for each node Propose a scalable and order-optimal Distributed Data Collection (DDC) algorithm Simulations are conducted to validate DDC 4
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n sensor nodes, s i (1≤i≤n), i.i.d. in a square area transmission radius r, Single radio, one common channel with bandwidth W bits/second Interference model 6
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R 0 -feasible state: a set of active nodes, s.t. all the nodes in this set can conduct data transmission simultaneously and each has a data transmitting rate no less than R 0. R-set (S R ): assume R is the carrier-sensing range. An R-set S R is any maximal subset of V s.t. any two nodes in S R has a distance of at least R. R 0 -Proper Carrier-sensing Range (R 0 -PCR): the carrier-sensing range R is a R 0 -PCR if for any R-set S R, it is always a R 0 -feasible state. 8
How to decide the proper carrier-sensing range? . (Theorem 1) 9
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Connected Dominating Set (CDS)-based data collection tree 11
Distributed Data Collection (DDC) algorithm 12
Analysis Any node with data for transmission can transmit at least one data packet within time. (Theorem 2) The time consumption of collecting all the data packets at to is upper bounded by. (Corollary 2) After time, it takes DDC at most time to collection all the data to the sink. (Theorem 3) The lower bound of data collection capacity achieved by DDC is, which is scalable and order optimal. (Theorem 4) 13
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Network setting Power = 1, data packet size = 1, time slot = 1, and …… Multi-Path Scheduling (MPS) algorithm [7] 15
Capacity 16
Scalability 17
We study the distributed data collection problem in asynchronous WSNs We propose a Distributed Data Collection (DDC) algorithm, which is scalable and order-optimal Simulations are conducted to validate the performance of DDC 18