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Broadband Mobile Wireless Networks Lab.

FPOC: A Channel Assignment Strategy using Four Partially Overlapping Channels in Mid-scale Wireless Mesh Networks. Y.C.Lin, C.H.Lin, W.S.Hwang, and C.K.Shieh Department of Electrical Engineering National Kaohsiung University of Applied Sciences and National Cheng Kung University.

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Broadband Mobile Wireless Networks Lab.

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  1. FPOC: A Channel Assignment Strategy using Four Partially Overlapping Channels in Mid-scale Wireless Mesh Networks Y.C.Lin, C.H.Lin, W.S.Hwang, and C.K.Shieh Department of Electrical Engineering National Kaohsiung University of Applied Sciences and National Cheng Kung University Broadband Mobile Wireless Networks Lab.

  2. Outline Introduction Related Work FPOC Channel Assignment Strategy Simulation Results Conclusions

  3. Introduction 2MHz 7MHz 7MHz [1] Texas Instruments, “The Effects of Adjacent channel Rejection and Adjacent channel interference on 802.11 WLAN Performance, ” SPLY005-Nov. 2003 White Paper • Electromagnetic interference sources at 2.4GHz [1] • WLAN(IEEE 802.11b/g) • ZigBee(IEEE 802.15.4) • Wireless Phones, and so on. • Wireless interference • Co-channel interference • Adjacent Channel Interference (ACI) • Non-overlapping channel • Partially Overlapping Channels (POC) • Channel separation(chsp) of 3 and 4 (Arunesh Mishra, University of Maryland)

  4. Adjacent Channel Interference Channel:1、4、7、10 Overlap factor:0.0375 Channel:1、5、9、13 Overlap factor:0.0054 Channel:1、6、11 Overlap factor:0.0008 [2] Mitch Burton(Cirond Technologies), “Channel Overlap Calculations for 802.11b Networks, ” White Paper, Nov. 2002. • Overlap factor (olf) [2] • Overlapped area size of two separated channels

  5. Problem Statement Scenario1 Table I Dropping Rate Ch6 Ch1 Ch1 Ch11 B B C C Scenario2 A A Ch4 Ch8 Ch1 D D Ch11

  6. Related Work Link1 Link2 Distance (a) Bit Rate =2M [3] Yong Ding, “Channel Assignment with Partially Overlapping Channels in Wireless Mesh Networks, ” WICON 2008 and ICST 2008. (Michigan State University) (b) Bit Rate =5.5M • Greedy algorithm[3] • IF(Interference Factor) • Interference Range • Interference Free • Distance is over double of transmission range(R) • Channel separation(chsp) is 5 (c) Bit Rate =11M

  7. Related Work Linkab α(s)= 3.719 β(c)=1,1,1,1,1,0,0,0,0,0,0 Assign channel：channel 6 a channel 6 ch6 b 17 26 c 19 ch1 d 39 e 19 29 16 f 28 g 38 h 23 27 i 29 • Greedy algorithm[3] • Step I – Select • Calculate α(s) for each link that has not been assigned channel • Step II – Assign • Calaulate β(c) for each channel that has minimum α(s) Link12 α(s)= 3.719 β(c)=1,1,1,1,1,0,0,0,0,0,0, Assign channel：channel 6

  8. Summary and Objective a ch6 MAP 17 b ch11 ch8 26 MAP 19 ch1 c 39 d ch1 19 Interference ch3 MAP 29 e ch8 ch2 16 f MAP 28 ch1 38 MAP g ch7 23 ch3 Load Balance MAP h 27 ch10 i MAP 29 MAP • Greedy algorithm • Flexible to allocate channel in large WMNs • No consideration about: • radio load balance • partially overlapping Interference

  9. Channel Assignment Strategy - FPOC MAP 17 26 MAP 19 39 MAP radio 19 MAP 29 link 16 STA MAP 28 38 a MAP 23 b MAP 27 Traffic c MAP d STA 29 STA MAP e f STA g STA h i • Objectives • balance the radio traffic load • reduce multi-radio interference by conflict graph

  10. FPOC Channel Assignment Strategy a b 17 c 26 d 19 39 e 19 29 f 16 28 g 38 h 23 27 i 29 Node order of assignment : MAPe assigned linkeb: 39 radio1 radio2 linkeh: 38 linkeb: 39 linkeh: 38 assigned linkef: 28 linked: 29 linkba: 29 assigned linkef: 28 assigned

  11. FPOC Channel Assignment Strategy a LinkSet3 b 17 c LinkSet5 26 d 19 LinkSet1 39 e 19 29 LinkSet2 LinkSet6 f 16 28 g 38 h 23 27 LinkSet4 i 29 Link set1 Link set2 Link set6 Link set3 Link set4 Link set5 Conflict Graph

  12. FPOC Channel Assignment Strategy a LinkSet3 b 17 c LinkSet5 d 26 19 LinkSet1 39 e 19 29 LinkSet2 LinkSet6 f 16 28 g 38 23 h 27 LinkSet4 i 29 1 2 Channel 1 3 Channel 4 Channel 8 Channel 11 5 Channel 11 4 Channel 8

  13. Simulations a e c b d g j h f i Transmission Range o m k n l Interference Range p t r q s u w y v x • Parameters in NS-2 simulator • 802.11b, data rate 1 Mbps, 2 radios/node • Transceiver range: 200 m / Interference range: 400 m • Available channel: 4

  14. Simulation Results

  15. Conclusions • Wireless LAN is popular, and more APs are used in a limit space. • In mid-scale wireless mesh networks, its performance is largely affected by number of available channels. • This paper proposed • Four less interference partially overlapping channels to work • A channel assignment strategy with • Balance radio load • Channel interference • Get better throughput and dropping rate

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