MMLAB NETWORK SEMINAR Tree-Based Data Broadcast in IEEE 802.15.4 and ZigBee Networks Written by Gang Ding(Purdue Univ.), Zafer Sahinoglu(MERL), Philip Orlik(MERL), Jinyun Zhang(MERL), Bharat Bhargava(Purdue Univ.) 2007.03.23 Presented by Chang, Dukhyun

Contents Introduction Background Proposed Algorithms 802.15.4 & ZigBee Networks Proposed Algorithms ZigBee On-Tree Self-Pruning Algorithms ZigBee On-Tree Selection Algorithms Performance Evaluations Conclusion

Introduction Broadcasting in Ad hoc Networks Flooding -> broadcasting storm problem Finding minimum forwarding nodes -> NP hard Some heuristic algorithms algorithms based on greedy forward node selection algorithms assuming extra info (location, 2-hop neighbor info) -> inefficient or not practical in ZigBee Networks

Introduction Characteristics of ZigBee Networks limited computation and storage capacity no sophisticated algorithms small size & low cost no accurate location info. low data rate & low power no exchanging large neighbor info Motivated to find localized and light-weight broadcast algorithm

802.15.4 & ZigBee Networks Device Types FFD, RDD Network Structure

802.15.4 & ZigBee Networks Routing Tree Routing AODVjr Forming tree structure with assigning address An = Aparent + Cskipx(n-1) + n (n≥1) Cskip

802.15.4 & ZigBee Networks Assigning address No Routing tables ! if Cskip= 21 when d=0 Current Broadcasting in ZigBee Networks only tree neigbors rebroadcast A0=0 No Routing tables ! A0=1 A0=22

ZigBee On-Tree Self-Pruning Motivation General Self-Pruning (a Scalable Broadcast Algorithm(SBA)) rebroadcasting after random period if all neighbors of a node v(=N(v)) are covered, no rebroadcasting must receive packets from N(v) 2-hop neighbor info is assumed need to exchange neighbor info. -> not practical in ZigBee networks ZigBee On-Tree Self-Pruning using light info. tree structure info. 1-hop neighbor’s address 1-hop neighbor’s # of children when node u is a neighbor node of node v we cannot know N(u) but on-tree neighbor of node u(=TN(u))

ZigBee On-Tree Self-Pruning ZigBee On-Tree Self-Pruning Algorithm rebroadcasting after random period if all On-Tree neighbors of a node v(=TN(v)) are covered, no rebroadcasting can know coverage rapidly using TN(u)

ZigBee On-Tree Selection Goal Find the smallest node set subset F(v) s.t. F(v) is subset of N(v) to on-tree cover TN(N(v)) Motivation no 2-hop neighbor info. -> using on-tree neighbor info. solves problem in polynomial time (OOS) solves problem with polynomial memory (ZOS) cover the whole network Consider covering TN(N(v)) -> trade-off!

ZigBee On-Tree Selection Optimal On-Tree Selection Algorithm Candidate forward nodes of v To-be-covered nodes of A

ZigBee On-Tree Selection Example compare with greedy algorithm (Ad Hoc Broadcast Protocol(AHBP))

Performance Evaluation an event-driven simulator in MATLAB 100m x 100m Comparison Scalable Broadcast Algorithm(SBA) Ad Hoc Broadcast Protocol(AHBP) ZigBee broadcast algorithm currently used Global algorithm (global network topology is known)

Performance Evaluation Physical topology ZigBee topology ZigBee(100) SBA(85) OSR(51) AHBP(36) ZOS(31) Global(10)

Performance Evaluation The number of rebroadcasting nodes Coverage time

Performance Evaluation Average duplicated packets

Conclusion Given only phisical 1-hop neighbor & logical tree neighbors, this paper two roadcast algorithms for IEEE 802.15.4 & ZigBee networks the on-tree self –pruning rebroadcast algorithm the ZigBee on-tree selection algorithm, ZOS The proposed schemes outperform other schemes These schemes are feasible in computation complexity & memory space complexity