Researches in MACS Lab http macs cityu edu
Researches in MACS Lab http: //macs. cityu. edu. hk/ Prof. Xiaohua Jia Dept of Computer Science City University of Hong Kong
On-going research projects l l 可信移动互联网络的关键理论与应用研究 , NSF China Key Project (07– 10) Minimum Latency Broadcast and Data Aggregation in Wireless Ad Hoc and Sensor Networks, HK UGC (07 – 09) Energy Efficient Query Dissemination and Aggregation in Wireless Sensor Networks, HK UGC (06 – 07) Virtual Backbone Construction in Multihop Ad Hoc Wireless Networks, HK UGC (05 – 07)
Wireless Sensor and Ad Hoc Networks Sensor surveillance systems Given the locations of sensors and targets, sensor initial energy, find a schedule for sensors to watch the targets in turn, such that the lifetime is maximized. “Maximizing Lifetime of Sensor Surveillance Systems”, IEEE/ACM Trans on Networking, Vol. 15, No. 2, Apr 07. "Maximal Lifetime Scheduling for Sensor Surveillance Systems with K Sensors to 1 Target", IEEE Trans on Parallel and Distributed Systems, Vol. 17, No. 12, Dec 06.
Wireless Sensor and Ad Hoc Networks Broadcast / multicast in ad hoc networks l Efficient flooding "A Distributed and Efficient Flooding Scheme Using 1 -hop Information in Mobile Ad Hoc Networks, " IEEE Trans on Parallel and Distributed Systems, Vol. 18, No. 5, May 2007. l Energy efficient routing “Energy efficient broadcast routing in ad hoc wireless networks”, IEEE Trans on Mobile Computing, Vol. 3, No. 2, Apr - Jun, 2004. l Minimum latency broadcast / multicast
Wireless Sensor and Ad Hoc Networks Real-time data aggregation l CSMA model (802. 15. 4) l TDMA model l Multi-channel
Wireless Mesh Networks (WMN)
Channel Assignment in WMNs Given a network physical topology (determined by transmission power of nodes) and limited # of channels, assign channels to the radios in each node, such that certain connectivity of the network is preserved and the network interference is minimized. Channel assignments can be: l l l static assignment dynamic assignment hybrid assignment
Topology Control in WMNs l Topology control in WMNs includes two steps: l l l Power adjustment l l l Define the physical topology of network A link between two nodes if they are reachable via transmission power. Channel assignment l l l Power adjustment Channel assignment Define the logical topology on the top of the physical topology A link between two nodes if they are reachable and use a common channel. Goals of topology control l l Min interference (given connectivity requirement) Qo. S guaranteed (end-end bandwidth, delay, etc) topology
Timeslot schedule in TDMA systems l l Free timeslot matching on links Interference (inter-flow / intra-flow)
Timeslot schedule in SR/SC systems Given traffic demand on each link, find a TDMA schedule that all traffic demands can be met and the TDMA cycle is minimized.
Channel assignment and timeslot schedule in MR/MC systems l l l Separate channel assignment from slot scheduling (channel static) Joint channel assignment and slot scheduling (channel switchable at packet level) Real-time traffic scheduling
Channel assignment and timeslot schedule in a tree
Multiple trees configuration in WMNs Given a set of mesh routers and multiple gateway nodes, configure a set of trees (via power-adjustment or channel-assignment), such that the total throughput of the trees is maximized. Issues to be considered: l Load balancing l Interference l Timeslot schedule
Online Qo. S routing & timeslot scheduling l l Qo. S unicast Qo. S multicast
Thanks!
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