Access Point Selection Considering the Effect of Interference in the Wireless LAN

Transcription

1 THE INSTITUTE OF ELECTRONICS, INFORMATION AND COMMUNICATION ENGINEERS TECHNICAL REPORT OF IEICE. LAN Access Point LAN (APAccess Point) IEEE 82.11b/g ( ) AP AP IEEE 82.11a/b/g (STAStation) AP STA AP LAN IEEE 82.11b LAN LAN AP Abstract Access Point Selection Considering the Effect of Interference in the Wireless LAN Jin KANEKO, Yutaka FUKUDA, and Yuji OIE DeptComputer Science and ElectronicsKyushu Insititute of Technology Kawazu 68-4Iizuka Japan Information Science CenterKyushu Insititute of Technology Sensui 1-1TobataKitakyushu Japan jin@infonet.cse.kyutech.ac.jp, fukuda@isc.kyutech.ac.jp, oie@cse.kyutech.ac.jp According to the spreading of the wireless LAN, multiple access points (APs) will be much more likely to be available there for stations (STAs). On the contrary, in the wireless LAN, a relatively limited amount of bandwidth is available. Certainly, IEEE 82.11b defines 14 possible frequencies, however, they are close enough to interfere with each other. If STAs select their APs based on the existing scheme, which only uses the received signal strength, the interference among both APs and STAs is very likely to be caused, thereby preventing the efficient use of the wireless resources significantly. Therefore, in this paper, we first investigate how interference among both APs and STAs affects the throughput performance from experimental results. Based on these experiments, we propose the decentralized AP selection scheme with avoiding interference, and show that the proposed solution can alleviate the effect of the interference and improve the throughput performance compared with the existing AP selection scheme. Key words Wireless LANInterferenceIEEE 82.11bWireless Station(STA)Access Point(AP)AP selection 1. LAN(Local Area Network) LAN LAN LAN LAN (APAccess Point) LAN IEEE 82.11b/g 1

2 1 IEEE 82.11b ( ) FER AP (STAStation) AP STA -6 Xi [dbm] -4-1 Xr [dbm] AP X r dbm X i FER STA LAN STA1 attenuator AP STA2 UDP transmitter receiver coaxial cable ethernet cable 3. 2 Xr[dBm] interference Xi[dBm] anechoic chamber RSSI-FER 2 IEEE 82.11b 11 Mb/s STA1 LAN STA2 1,5 Byte UDP IEEE 82.11b/g STA1 2.4 GHz ISM(Industrial Scientific and Medical Band) (2 attenuator) X r dbm 1 STA1 (2 interference) 1 MHz 1 2 X i dbm AP MHz 1 AP (anechoic chamber) AP X r dbm X i dbm STA (Frame Error Rate 5 14 FER) STA IC ISM LAN 3. 2 [1] [2] 3. 1 STA1 AP AP X r dbm X i dbm [3] [4] FER 3 FER AP 3 X i = 4 dbm X r FER X i = 4 dbm STA X r = 4 dbm FER AP 1 FER 2

3 Idle status (6) (3) (2) (c) 1 Search status (4) (2) Re-serch status (5) (a) (b) FER 4 4. AP (a) [5] [6] AP (c) MLT(AP selection algorithm for Maximizing Local Throughput) 3 5 Xr dbm FER STA AP MLT 4. 1 MLT [5] [6] STA AP STA MLT FER 3 MLT 3 FER MLT STA AP 5 AP (a) 5 P FER Packe Error Rate(PER)N AP STA W th = 1 P FER N + 1 (b) FER 1 STA ( ) 4 FER STA Search Interval AP AP-1 AP-2 Backoff Time Re-Search (2) (a) AP-2 FER Idle (3) STA AP-1 AP STA Search FER (4) AP 5. Backoff Time (5) STA Idle Time Search AP (6) [5] [6] ns-2.27 STA MLT AP LAN IEEE 82.11b AP STA Xr [dbm] ( ) (b) STA (c) AP 6 AP 6 m 3 m AP MLT AP1 PER AP2 AP3 P 4 STA 6 3 m STA 3 m AP STA TCP 3 FER 1,5 Byte FTP Greedy AP 3

4 1ch interference 2ch AP AP1 6 [m] AP2 AP3 7ch 14ch 3[m] area where STAs exit 6 3[m].4 (2) MLT.35 (a)sharp (b)smooth AP STA.3 (c)conservative 4.2 (a) (b) (c) 3.25 LAN STA.15 STA.1 balance index [7] balance index (2) 1 β 1 N average throuput[kb/s] B i STA i N STA (a) (b) β = ( X B i ) 2 /(N X B 2 i ) (2) 6. [Kb/s] balance AP index (2) MLT AP STA (a) (b) (2)MLT AP (c) AP Kb/s STA probability density function probability density function average throuput[kb/s] 3 % 8 (a)(b)(c) STA 3 Kb/s AP 1 balalnce index STA (a) STA AP 8 (a) (a) (b) Kb/s STA 5 % (c) AP STA 5(2) STA AP LAN (b)(c) 8 Kb/s ISM STA [3] AP (b)(c) FER STA FER (b)(c) (b)(c) radio (2)MLT (2)MLT AP (c) AP balance index 4

5 2 AP STA () STA () AP AP AP1 AP2 AP3 (b) (c) AP.1 [Kb/s] AP (b) (c) (b) (c) STA AP (b)(c) AP (b)(c) 7ch 6. 2 (b)(c) (b)(c) AP Network1: AP, AP3 STA 6 3 m 3 m( average throuput[kb/s] 6 ) 1 2 probability density function 9 5 AP 6. 3 AP STA AP 9 (b)(c) STA (b)(c) AP Kb/s STA (c) STA 9 AP 2 AP ISP(Internet Service STA (c) Provider) AP APAP1 STA 1 AP 3 % (c) STA AP3 1 AP1AP2 2 AP m 5 m 2 AP1AP3 (b) (c) AP STA 12 STA 9 STA 2 4 STA 1 (c) AP STA (b) (b)(c) AP AP (c) (2) MLT 5 STA (b) STA 4 AP STA (b) AP (b) 23 Kb/s (c) (b)smooth (c)conservative STA 4 25[m] 1ch AP1 Interferance 2ch AP3 5[m] 14ch AP2 25[m] Network2: AP1, AP2 5[m] 5

6 4 AP AP [Kb/s] (b) (2) MLT Robustness- Proceedings of the IEEE VTC24-Fall, Los AP (2)MLT Angeles, CASeptember 26-29, 24 AP STA [7] Dah-Ming Chiu and Raj Jain Analysis of the Increase and Decrease Algorithmes for Congestion Avoidance in Computer Network Computer Network and ISDN Systems AP vol17 pp (b) [8] Kamal JainJitendra PadhyeVenkata N.Padmanabhan Inpact Of Interference On Multi-hop Wireless Network Performance MobiCom 3 September [9] Hung-Yu WeiSamrat GangulyRauf IzmailovZygmunt 7. J.Hass Interference-Aware IEEE WiMax Mesh Networks Proceedings of IEEE Vehicular Technology LAN Conference-VTC 25 SpringMay 25 STA AP IEEE 82.11b STA AP AP STA STA LAN AP [8] [9] LAN AP (B) ( 17771) NICT JGN2 (PCC) 11b DCF Proceedings of IEEE Vehicular Technology Conference-VTC 23 Fall23 [5] Yutaka FukudaTakamitsu Abe and Yuji Oie Decentralized Access Point for Wireless LANs In the Proceedings Of WTS 24 SA3May 24. [6] Yutaka Fukudaand Yuji Oie Decentralized Access Point Selection Architecture for Wireless LANs -Deployability and [1] IEEE 82.11g Bluetooth CQ24 75pp [2] LAN B [3] IEEE 82.11b LAN B [4] M Cesana, D Maniezzo, P Bergamo, M Gerla Interference Aware (IA) MAC: an Enhancement to IEEE82. 6