Basics of a wireless Ad-Hoc°。■。 Network There is no fixed communication infrastructures Tasks are self-organized without central control Network is dense: control and Autonomous tracking in communication overlap Sensor Network Control and communication patterns are specific: one-to-many, many-to-one Network topology is dynamic: topology self-reconfiguration is necessary Autonomous failure detecting power re- assigning in Power supply network
Basics of A Wireless Ad-Hoc Network • There is no fixed communication infrastructures. • Tasks are self-organized without central control • Network is dense: control and communication overlap • Control and communication patterns are specific: one-to-many, many-to-one • Network topology is dynamic: topology self-reconfiguration is necessary Autonomous tracking in Sensor Network Autonomous failure detecting & power reassigning in Power supply network f /c
An Example of wireless Sensor Network 0 Internet and satellite++ Sink 0c0 0 00 fask manager node er Sensor field Sensor nodes I figure 1. Sensor nodes scattered in a sensor field
An Example of Wireless Sensor Network
How Can Distributed Systems Work Autonomously (What are centralized/decentralized systems? Example 50 kids are playing in a ground. How can they form a circle when their teacher asks them to do? Condition 1: each kid can see all other kids Condition2: Each kid can see some kids.。。 Questions: In which case will a circle be formed faster Observations More global information a node has the easier the work will be done It is expensive to get global information form dynamic distributed systems
How Can Distributed Systems Work Autonomously? (What are centralized/decentralized systems?) Example 50 kids are playing in a ground. How can they form a circle when their teacher asks them to do? Condition 1: Each kid can see all other kids. Condition 2: Each kid can see some kids. Questions: In which case, will a circle be formed faster? Observations: • More global information a node has, the easier the work will be done. • It is expensive to get global information form dynamic distributed systems
Communication on Wireless AD-NETs Communication Mode Directed Graph e=(V日 V=nodes E=ledge u,v): if node u can transmit data to node v lodes with different communication range
Communication on Wireless AD-NETs Directed Graph G=(V,E) V={nodes} E={edge (u,v): if node u can transmit data to node v} Nodes with different communication range Communication Model
Communication on Wireless AD-NETs -Continue Example of communication tasks: Broadcast Algorithm 1: Broadcast by flooding cach node if v received the message then Source transmit the message How to solve collision problem? using randomized algorithm generate a random number k transmit data at kth time slot It may need long time in a dense network !!!
Source How to solve collision problem? -- using randomized algorithm: generate a random number k, transmit data at kth time slot. • It may need long time in a dense network !!! Example of communication tasks : Broadcast Communication on Wireless AD-NETs – Continue Algorithm 1: Broadcast by flooding Each node v: if v received the message then transmit the message