1 Minimum Latency Broadcasting in Multiradio, Multichannel, Multirate Wireless Meshes Junaid Qadir*, Chun Tung Chou+, Archan Misra ++, and Joo Ghee Lim + * National University of Sciences and Technology, Islamabad, Pakistan. + University of New South Wales, Sydney, Australia ++ Applied Research, Telcordia Technologies, IEEE/ACM TRANSACTIONS ON MOBILE COMPUTING, VOL. 8, NO. 11, NOVEMBER 2009

2 Outline  Introduction  Network and interference model  Heuristics to construct MLB tree in MR 2 -MC multi-rate mesh  Simulation  Conclusions

3 Introduction  A wireless mesh network is a multihop wireless network consisting of A large number of wireless nodes Some gateway nodes and connected with a wired network.  However, low spatial reuse of a single radio channel (due to wireless interference) poses an impediment to the widespread adoption of WMN as a viable access technology.

4 Introduction  The minimum latency broadcasting (MLB) problem is particularly challenging in Multi- Radio, Multi-Hop Wireless Mesh Networks  How to support “efficient” broadcast in such networks is an important issue.

5 Network and interference model  The system has C non overlapping orthogonal frequency channels Each node is equipped with Q radio interfaces where Q <= C.  In order to efficiently utilize the network resources, two radio interfaces at the same node are not tuned to the same channel.  The channel assignment is done by the following channel assignment algorithms CCA, VCA and ISNTC

6 Network and interference model  A graph,where l and A denote the latency of each link and the channel assignment function, respectively. v u 2313 A(u)={2,3}A(v)={1,3}

7 Network and interference model  Each edge is represented by a ,where vu Channel k

8 Network and interference model A(y)={2,3} l(w, x, 1)=l(w, x, 2)=l(y, z, 3)= 1/ m l(w, z, 1)=l(x, y, 2)=1 400 m latency

9 Network and interference model  Link-layer multicast transmissions 4-tuple : the node p  V is to transmit to all the nodes in the set I  V in a link-layer multicast using latency l on channel k. For, the following are required 

10 Problem statement  Given the graph, and the broadcast source node s, the objective is to find a set of link-layer multicast transmissions such that: The union of all links from all the transmissions forms a spanning tree on G The broadcast latency is minimized

11 Heuristics to construct MLB tree in MR 2 -MC multi-rate mesh  Multiradio, Multichannel Shortest Path Tree (MSPT)  Multi-radio, Multichannel WCDS Tree (MWT)  Locally Parallelized, Multi-radio, Multichannel WCDS Tree (LMT)  Parallelized, Approximate-Shortest, Multi- radio, Multichannel WCDS Tree (PAMT)

12 Multiradio, Multichannel Shortest Path Tree (MSPT)

13 Multiradio, Multichannel Shortest Path Tree (MSPT) S

23 14 Multiradio, Multichannel Shortest Path Tree (MSPT) S

15 Multi-radio, Multichannel WCDS Tree (MWT)

23 16 Multi-radio, Multichannel WCDS Tree (MWT) S /32/1< 1 2 1

23 17 Multi-radio, Multichannel WCDS Tree (MWT) S /32/1<

18 Locally Parallelized, Multi-radio, Multichannel WCDS Tree (LMT)

19 Locally Parallelized, Multi-radio, Multichannel WCDS Tree (LMT) A B C S Channel 2 |{B,C}| / 1 = 2 Channel 3 |{A, B,C}-{B,C}| / 3 =

20 Parallelized, Approximate-Shortest, Multi- radio, Multichannel WCDS Tree (PAMT)

21 C 15 B 12 A 12 E 32 S 32 D 31 Label=1=latency Label= N(A,2,1)={B,C,D}N(A,2,1)={B,C}

22 Simulation  N nodes are randomly located in an area of 1200m * 1200 m  three channel assignment schemes in our current work: CCA, VCA, and INSTC A 1 CCA 2 B 12 A 1 VCA 2 B 13 C 12 C 14 fixedrandom

23 Simulation  INSTC—construct a K-connected graph 1-connected topology

24

25

26 VCA, INSTC > CCA

27 Simulation CCA channel assignment 100 packets

28 CCA channel assignment

29 Conclusions  The authors proposed four heuristic algorithm for MR 2 -MC WMNs  PAMT outperforms the other algorithms  The performance of CCA (which usually performs poorly for unicast flows) is generally better than both VCA and INSTC.

30 Thank you~

31 MSPT LMT PAMT MWT