1 Efficient Backbone Synthesis Algorithm for Multi-Radio Wireless Mesh Networks Huei-jiun Ju and Izhak Rubin Electrical Engineering Department University of California, Los Angeles (UCLA) WCNC 2006

2 Outline Introduction Related Work Multi-Radio Backbone Synthesis Algorithm (MR-BAS) Multi-Radio MBN On-Demand Routing (MR-MBNR) Performance evaluation Conclusions

3 Introduction- Mesh Backbone Network Topology

4 The advantage of backbone Mesh Network Easy for routing Power saving Increasing the efficiency

5 Introduction- Mobile Backbone Network (MBN) Nodes are classified into two categories, Backbone Capable Nodes (BCNs) and Regular Nodes (RN), based on their ability In this paper AP nodes are analogous to BCNs while non-AP act as regular RNs.

6 Introduction- Motivation MBN is designed so that it involves a sufficient but not excessive number of backbone nodes.

7 Related Work ETSA (Extended mobile backbone network topology algorithm) Each node have a single radio, use 1-hop complete neighborhood and 2-hop BN neighbor information and all nodes operate at the same frequency. CDS construction algorithm Each node have a single radio and make use of complete 2-hop neighborhood data.

8 MR-BSA In this paper Multi-radio backbone synthesis algorithm (MR- BSA) is used for constructing and maintaining a backbone network in this paper. Each AP node is either elected to serve as a BN or is one-hop away from a BN Backbone Nodes are classified with three type. BN_A, BN_B and BN_C.

9 MR-BSA - System model BN_A RN BCNBN_A

10 MR-BSA - System model BN_B RN BN_ARN BN_ABN_B

11 MR-BSA - System model BN_C RN BN_ARN BN_ABN_C

12 MR-BSA - System model AP nodes are equipped with two radio (high capacity channel and low capacity channel) modules and routing intelligence. Non-AP nodes are only employed a single radio and possessed no routing capability. Each channel can be operated at its selected data channel. Each node has two timer : Short Timer and Long Timer, and the Long Timer is set to be 3 times Short Timer. AP_node Client_node 一： high capacity channel 一： low capacity channel

13 MR-BSA - Short Timer expires When the Short Timer expires, the node broadcast Hello message to it’s neighbor on high capacity channel ( BCN or BN) and low capacity channel. Node Hello message

14 MR-BSA - Hello message Hello message on high capacity channel contains Node’s ID Status Weight Associated BN ID BN neighbor list

15 MR-BSA - Hello message Hello message on low capacity channel contains Node’s ID Status Weight Associated BN ID Predecessor node’s ID Number of hops to the closest BN

16 MR-BSA - Hello message Through periodic Hello message exchange Each BCN learns its 1-hop neighborhood and 2-hop BN neighbor across the high capacity channel. All nodes learn their 1-hop neighborhood across the low capacity channel.

17 MR-BSA - Long Timer expires When the Long Timer expires, the node updates its neighbor lists based on the number of Hello messages received from each neighboring radio within the previous period.

18 MR-BSA Association algorithm is used for constructing the backbone network. BCN to BN and BN to BCN conversion algorithm is used for maintaining the backbone network.

19 MR-BSA- Association Algorithm In the high capacity channel BCN try to find a BN_A node with highest weight in its 1-hop neighborhood to associate with. If no neighboring BN is detected, the node attempts to associate with a BCN. And selecting among all its neighboring BCNs. BCN BN_A Weight=3 BN_A Weight=4 BN_A Weight=5 BCN Weight=3 BCN Weight=4 BCN Weight=5 一： high capacity channel 一： low capacity channel BN Hello message

20 MR-BSA- Association Algorithm In the low capacity channel BCNs and RNs try to find a BN node with highest weight to associate with. If no neighboring BN is detected, BCN or RN BN Weight=3 BN Weight=4 BN Weight=5 BCN or RN BCN 一： high capacity channel 一： low capacity channel BN Hello message ＋

21 MR-BSA- BCN to BN conversion Algorithm BCN to BN conversion algorithm executes based on high capacity channel neighborhood information. BN_A BN_BBN_C BCN

22 MR-BSA- BCN to BN conversion Algorithm

23 MR-BSA- BCN to BN conversion Algorithm Case : Client coverage condition RN BCN Weight=4 RN BCN Weight=5 BN_A BCN Weight=3 BCN 一： high capacity channel 一： low capacity channel

24 MR-BSA- BCN to BN conversion Algorithm Case : Local 2-hop BN_A connection BN_A BN_BBCN Weight=5 一： high capacity channel 一： low capacity channel BCN Weight=4

25 MR-BSA- BCN to BN conversion Algorithm Case : Local 2-hop BN_A and BN_C connection BN_A BCN Weight=5 BCN Weight=4 BN_C BCN BN

26 MR-BSA- BCN to BN conversion Algorithm Case : Local 3-hop BN_A connection BN_A BN_C BCN BN_C ＋ ＋ ＋

27 MR-BSA- BN to BCN conversion Algorithm BN to BCN conversion algorithm executes based on high capacity channel neighborhood information. During the execution of BN to BCN conversion algorithm BN also updates its role as BN_A,B or C BN_A BN_BBN_C BCN

28 MR-BSA- BN to BCN conversion Algorithm

29 MR-BSA- BN to BCN conversion Algorithm Case : Client coverage condition BN Weight=4 BN Weight=3 BCN 一： high capacity channel 一： low capacity channel RN

30 MR-BSA- BN to BCN conversion Algorithm Case : Local 2-hop BN_A connection BN_A BN_BBCN Weight=5 一： high capacity channel 一： low capacity channel BCN Weight=4

31 MR-BSA- BN to BCN conversion Algorithm Case : Local 2-hop BN_A and BN_C connection BN_A BCN Weight=4 BCN BN Weight=3 BN_C

32 MR-BSA- BN to BCN conversion Algorithm Case : Local 3-hop BN_A connection BN_A BN_C BN Weight=3 BCN Weight=5 BCN

33 Multi-Radio MBN On-Demand Routing (MR-MBNR) Through use of on-demand routing protocols such as Ad hoc On-demand Distance Vector (AODV) and Dynamic Source Routing (DSR), source-destination routes are discovered by flooding route request (RREQ) packets across the entire network.

34 Performance evaluation Simulation model QualNet V DCF MAC layer protocol Channel data rate 2Mbps Radio transmission range 300m Short_Timer:2secs Long_Timer:6secs The results have been averaged over 5 randomly generated topologies.

35 Performance evaluation- Backbone Network

36 Performance evaluation- Backbone Network

37 Performance evaluation

38 Performance evaluation- Throughput Performance (single channel)

39 Performance evaluation- Throughput Performance (single channel)

40 Performance evaluation- Throughput Performance (two channel) The notation “Lx” represents the results for setting the low capacity radio transmit power to x dBm.

41 Conclusions The MR-BSA scheme presented here Guarantees to construct and maintain a connected backbone network Reduce routing overhead and to provide scalable and efficient operation for the wireless network.