Vol. 50 No (Feb. 2009) LAN AP Access Point LAN Local Area Network VoIP Voice over Internet Protocol SaaS Software as a Servie PLR P

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1 Title Author(s) 異種サービス混在環境における無線 LAN アクセスポイント選択アルゴリズム森岡, 康史 ; 東野, 武史 ; 塚本, 勝俊 ; 小牧, 省三 Citation 情報処理学会論文誌. 50(2) P.750-P.764 Issue Date Text Version publisher URL DOI rights 情報処理学会

2 Vol. 50 No (Feb. 2009) LAN AP Access Point LAN Local Area Network VoIP Voice over Internet Protocol SaaS Software as a Servie PLR Packet Loss Rate QoS Quality of Service IEEE802.11e QoS LAN AP QoS QoS AP AP AP AP QoS PLR Wireless LAN Access Point Selection Algorithm for Heterogeneous Services Environment Yasufumi Morioka, 1 Takeshi Higashino, 1 Katsutoshi Tsukamoto 1 and Shozo Komaki 1 This paper proposes an AP (Access Point) selection algorithm for heterogeneous service environment. Recent rapid developments of high-speed WLAN (Wireless LAN) enable to use various multimedia services such as VoIP (Voice over Internet Protocol), video streaming and SaaS (Software as a Service) in mobile environments. Each of these services requires different QoS which are acceptable PLR (Packet Loss Rate), delay time and so on. IEEE802.11e can provide a QoS for each service, however, there is a requirement of load balancing among APs to provide an appropriate QoS for each service in large scale WLANs. The proposed algorithm realizes an AP selection for appropriate load balancing and provision of QoS according to its required QoS, the number of associated to each AP and traffic load of each AP in an overall WLAN service area. Simulation results show improvement PLR (Packet Loss Rate), delay time and throughput in heterogeneous service environment compared to conventional algorithms. 1. IEEE802.11a/g 1),2) LAN Local Area Network IEEE802.11n 3) WWW World Wide Web VoIP Voice over Internet Protocol YouTube WWW SaaS Software as a Service QoS: Quality of Service LAN QoS QoS LAN QoS IEEE802.11e 4) IEEE802.11e PLR Packet Loss Rate QoS LAN AP STA AP STA LAN AP STA AP STA AP STA QoS LAN AP QoS LAN STA QoS 1 Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University 750 c 2009 Information Processing Society of Japan

3 751 LAN STA 5) 9) STA AP 10) 18) 5) SS AP SS AP STA AP UDP 6) 5) 7) 8) SS AP Intelligent Switch 7) AP 9) 9) NOC Network Operation Center STA STA AP STA AP 10) 14) RSSI: Received Signal Strength Indicator AP AP STA STA AP STA QoS STA STA 10) 11) RSSI AP STA 11) DLBA Dynamic Load Balance Algorithm STA RSSI PER Packet Error Rate STA 12) 13) MLT Maximizing Local Throughput FTP FTP 14) MLT AP STA FTP STA FTP VoIP FTP IEEE802.11e AP QoS QoS STA QoS 15) 16),17) HRFA 18) IEEE802.11e AP QoS MAC Media Access Control IEEE802.11e STA 15) AP STA IEEE802.11e STA AP 16) AP QoS 17) STA AP AP PLR Packet Loss Rate HRFA 18) AP AP AP UDP User Datagram Protocol VoIP RT Real Time UDP NRT Non Real Time UDP TCP Transmission Control Protocol TCP TCP UDP QoS AP VoIP RT FTP TCP NRT QoS

4 752 LAN RT QoS PLR NRT QoS QoS IEEE802.11e AP LAN RT RT AP TCP NRT RT STA AP AP NRT TCP RT NRT QoS HRFA IEEE802.11e STA AP QualNet 19) 2. 1 RT TCP NRT RT UDP NRT TCP AP UDP TCP UDP TCP STA AP RT RT RT Usage All Usage 1 AP 1 STA Associated STA 5 AP 2 1 Fig. 1 The problems of the conventional algorithms. STA 4 AP 1 RT 10% 100% AP 2 RT 30% AP 1 100% STA AP RT STA RSTA NRT STA NRSTA AP 2 RT RSTA AP 1 RSTA AP 1 AP 1 RT 20% AP RT NRT NRSTA STA AP 2 NRSTA AP 1 18% AP 2 30% AP 2 NRSTA 16),17) HRFA 18) AP RT NRT UDP RT RT NRT FTP TCP NRT RSTA AP 1 NRSTA AP 1 AP 2 100% AP TCP NRT AP RSTA RT NRSTA RT NRT NRSTA NRSTA AP FTP TCP NRT VoIP UDP RT QoS AP RSTA RT AP

5 753 LAN NRSTA RT NRSTA AP RT IEEE802.11e QBSS Load Element AAC Available Admission Capacity AAC RT 1 32 µs AAC = 0 1 RT 0 RT AAC = RT NRSTA NRSTA IEEE802.11e NRSTA STA STA QBSS Load Element SC Station Count AP STA AP RSTA NRSTA AP AP AP AP AP AP AP AP AP RSSI AP AP M AP AP[i] 1 i M RSTA (1) S RT [i] AP S RT [i] = AAC[i] R[i] R MAX (1) AAC[i] AP[i] AAC 0 AAC[i] R[i] AP[i] R MAX AP R MAX =max(r[i] 1 i M) (1) 2 Fig. 2 Flowchart of the proposed algorithm. AAC[i] RT AAC[i]+1 AAC[i] =0 AAC[i] (1) AP R[i] R MAX AP AP[i] NRSTA S NRT[i] AP S NRT[i] (2) (3) For AAC[i] = S R[i] 1 NRT[i]= R MAX N STA[i]+1 For AAC[i] < S AAC[i]+1 R[i] 1 NRT[i]= R MAX N STA[i] AAC[i] R[i] R MAX S RT [i] N STA[i] AP[i] STA (2) AAC[i] = RSTA NRSTA NRSTA N STA[i]+1 (3) AAC[i] RSTA NRSTA RSTA IEEE802.11e RSTA AP STA (2) (3)

6 754 LAN RSTA 1 NRSTA NRSTA NRT N STA[i] NRSTA QoS AP NRSTA S RT [i] RSTA RT AP NRSTA RT STA RT RT AP NRSTA NRSTA STA AP STA AP 3.3 RT 3 RSTA RT STA 3(a) RSTA AP 1 RT STA RSTA STA RT AP 1 STA AP NRSTA STA NRT STA STA AP 1 AP 1 NRSTA AP 2 AP 3(b) RT AP 1 AP 2 RT RSTA NRSTA AP AP RSTA AP NRSTA RSTA (1) RSTA RT RSTA AP NRSTA RSTA (1) RT RSTA 10 kbps 100 kbps 1 Mbps 3 RSTA 300 RSTA 3 AP AP RSTA RSTA 100 AP Mbps AP RSTA ,000 AP RSTA 99% RSTA RSTA AP 3(a) NRSTA Table 1 1 AP 99% Average bandwidth usage and 99% confidence interval of each AP. Fig. 3 3 RT The problems of AP selection in the coexistence of different RT services. AP , AP , AP , 37.14

7 755 LAN Table 2 2 AP RSTA 99% Average number of RSTAs and 99% confidence interval of each AP. AP , AP , AP , RSTA RSTA NRSTA AP 3.4 STA 2 NRSTA AP NRSTA NRT NRSTA IEEE802.11e SC NRSTA NRSTA SC STA NRSTA STA AP 4 RT NRT 1 4(a) RSTA STA RSTA STA NRSTA STA NRSTA NRSTA AP 4(b) NRSTA STA NRSTA STA NRSTA STA NRSTA NRSTA AP 4(c) RSTA NRSTA AP AP RSTA AP NRSTA AP STA NRSTA 4(c) AP RSTA AP RSTA NRSTA 4 STA Fig. 4 The problems of AP selection using the number of associated STAs. STA AP 3.5 STA AP STA STA AP STA AP QoS AP 3 STA AP STA AP STA AP AP STA AP AP AP QoS

8 756 LAN 12) 13) AP RT QoS 20),21) RSSI RSSI 13) 3 AP STA AP AP AP AP AP QoS 22) UDP RT TCP NRT QualNet 19) TCP UDP m 200 m 3 AP N STA 5 STA 2 STA STA STA AP 5 Fig. 5 Simulation area models. Uniform 5(a) STA AP STA Non-Uniform 5(b) 5(b) AP AP AP Non-Uniform-1 AP Non-Uniform-2 Uniform Non-Uniform-1 Non-Uniform-2 10,000 PLR AP MAC IEEE802.11g QoS MAC IEEE802.11e IEEE802.11g 2) IEEE802.11e 4) AP IEEE802.11g 54 Mbps UDP TCP VoIP VoIP G ) 1 FTP FTP Ethernet 24)

9 757 LAN Frequency 3 IEEE802.11g Table 3 IEEE802.11g simulation parameters GHz, GHz, GHz PLCP Preamble 16 µsec PLCP Header (Signal) 1Symbol PLCP Header (Service) 16 bit MAC Header 24 Octet LLC Header 8Octet FCS 4Octet PLCP Tail 6bit Symbol Length 4 µsec MAC ACK Length 10 Octet Slot Time 9 µsec SIFS 16 µsec DIFS 34 µsec CWmin 15 CWmax IEEE802.11e Table 4 IEEE802.11e simulation parameters. Access Background Voice Category (AC BK) (AC VO) CWmin 31 7 CWmax AIFSN Table 5 Parameters of each traffic. Application VoIP FTP Transport Protocol UDP TCP Payload Size 160 Byte 1460 Byte Interval 20 ms Required Rate 64 kbps Best Effort Direction UP DOWN DOWN Access Category AC VO AC BK STA 6 Case 1 Case 3 3 Case 1 VoIP FTP 0:1 N STA FTP 2 NRSTA STA Case 1 6 Case STA STA Table 6 Traffic rate and the number of STAs configurations of each case. VoIP FTP STA range Case N 30 Case N 60 Case N 120 STA FTP Case 2 VoIP FTP 1:0 N STA VoIP RSTA HRFA 2 Case 2 HRFA VoIP PLR Case 3 VoIP FTP 1:1 N STA VoIP FTP Case 3 STA VoIP PLR FTP 3 2 STA 6 FTP 1460 TCP IEEE802.11g 54 Mbps 1 AP 22.7 Mbps 3 AP 68.1 Mbps AP STA 54 Mbps AP STA STA STA Case 1 STA 2 Mbps STA STA N 0 N 30 IEEE802.11e 54 Mbps 1 AP VoIP AP VoIP 18 PLR IEEE802.11e VoIP

10 758 LAN 6 VoIP PLR Fig. 6 PLR and delay to the number of associated VoIP STAs. 7 Case 1 FTP Fig. 7 FTP throughput of Case 1. PLR FTP AC Access Category CW Contention Window STA 54 Mbps 1 AP VoIP 16 3 AP STA 54 Mbps VoIP 48 VoIP 48 AP STA PLR 0 Case 2 VoIP STA N =40 N =60 40 N 60 Case 3 STA VoIP FTP 1:1 N 96 VoIP STA Case N 120 TCP UDP Case 1 Case 2 TCP UDP Case 3 Case AP STA Uniform Case 3 STA Non-Uniform Case 1 Case 2 Uniform Case 3 Non-Uniform-1 Non-Uniform-2 5 VoIP STA AP NSTA RT RT NRT AP HRFA AP RSSI 3 Proposed 4.2 Case 1 Case 1 FTP 7 7 Proposed 2 Mbps Proposed FTP FTP Proposed FTP STA FTP STA AP STA NSTA Proposed NSTA Proposed STA AP AP FTP

11 759 LAN 4.3 Case 2 Case 2 VoIP PLR Proposed HRFA PLR 6% N 42 Proposed HRFA PLR N >42 Proposed HRFA PLR Proposed VoIP Proposed HRFA Proposed HRFA VoIP AP RT AP Proposed AP AP STA Proposed (1) (3) 8 Case 2 VoIP PLR Fig. 8 VoIP PLR of Case 2. AP R MAX AP R[i] HRFA w (4) (5) w = Tmax T rh (4) T max =max(t rh 0 h H 1) (5) T rh r h MAC T max H 10 Proposed HRFA 54 Mbps HRFA VoIP 10 Proposed HRFA AP 54 Mbps AP 1 36 Mbps AP 2 1 Mbps 10 Proposed w P AP 1 w P (AP1) = 1.0 AP 2 w P (AP2) = 0.67 HRFA w H AP 1 w H(AP1) = 1.0 AP 2 w H(AP2) = 0.93 Proposed HRFA RT RT AP 1 RT 50% Proposed HRFA AP1 (100% 50%) 1.0 =0.50 AP 1 9 Case 2 VoIP Fig. 9 VoIP one-way delay of Case 2. Fig Proposed HRFA Normalized score weight of Proposed and HRFA.

12 760 LAN AP 2 AP 1 AP 2 RT Proposed (100% x%) 0.67 > % HRFA 46% HRFA AP 2 46% AP 2 Proposed AP 2 25% AP 2 Proposed HRFA AP 9 Proposed HRFA 145 PLR Proposed N 42 HRFA N>42 HRFA NSTA RSSI N 52 Proposed HRFA STA AP 1 AP STA AP 2 AP STA 1 AP STA NSTA RSSI Proposed HRFA 32 N 42 Proposed HRFA PLR 1.5% 20 Proposed HRFA 10 Proposed HRFA HRFA AP STA Proposed AP HRFA STA HRFA ITU-T G ) PLR R Proposed R =83.7 HRFA R =89.7 G ) High Satisfied 6 STA N =48 VoIP PLR STA 48 Case 2 N =48 STA 54 Mbps 6 STA AP 54 Mbps STA 54 Mbps STA STA 6 STA AP STA 54 Mbps STA 4.4 Case Uniform Case 3 Uniform VoIP PLR FTP Proposed NSTA PLR 7.6% HRFA 6% RSSI 17% Case 2 N 84 Proposed HRFA PLR N >84 PLR Proposed VoIP FTP Proposed RSTA AP Case 2 Proposed AP STA PLR 12 Proposed NSTA 130 HRFA 145 RSSI 255 Case 2 N 84 HRFA N>84 HRFA N >108 NSTA RSSI Proposed HRFA Case 2 AP STA 60 N 84 Proposed HRFA PLR 1.7% 35 Case2 Proposed AP Case 2 R N =84 Proposed R =83.4 HRFA R =89.9 High

13 761 LAN Case 3 Uniform VoIP PLR Fig. 11 VoIP PLR of Case 3. Case 3 Uniform VoIP Fig. 12 VoIP one-way delay of Case 3. Case 3 Uniform FTP Fig. 13 FTP throughput of Case FTP N 64 Proposed N >64 RSSI N =92 Proposed 210 kbps VoIP PLR Proposed 17% 200 R 30 RSSI VoIP NSTA N 86 N >86 Proposed VoIP FTP 40 kbps HRFA STA 2 RSTA NRSTA HRFA NRSTA VoIP FTP STA VoIP PLR FTP Non-Uniform Case 3 Non-Uniform VoIP PLR FTP AP Non-Uniform-1 AP Non-Uniform2 VoIP PLR FTP Proposed AP Non-Uniform-1 14 Proposed NSTA PLR 19% HRFA 3.1% RSSI 70% Proposed PLR AP Proposed AP AP STA PLR 15 Proposed NSTA 292 HRFA 73 RSSI 577 N >100 NSTA Proposed HRFA Case 2 AP STA 16 FTP N 82 Proposed N 84 NSTA N =84 Proposed NSTA PLR 19% 290 R 85 NSTA

14 762 LAN 14 Case 3 Non-Uniform VoIP PLR Fig. 14 VoIP PLR of Case 3. Proposed NSTA VoIP AP Non-Uniform Proposed VoIP PLR HRFA 13% 263 Proposed AP STA 1 AP HRFA STA AP Proposed STA AP 1 AP STA 16 FTP NSTA 230 kbps Proposed 1 AP STA STA AP HRFA NSTA VoIP PLR FTP AP HRFA NSTA VoIP PLR NSTA FTP RSSI RSSI STA Case 3 Non-Uniform VoIP Fig. 15 VoIP one-way delay of Case 3. Case 3 Non-Uniform FTP Fig. 16 FTP throughput of Case RT NRT QoS STA STA RT NRT STA STA 1 AP AP AP RT NRT STA 1 STA RT NRT

15 763 LAN 1) IEEE Std a-1999: Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, High-speed Physical Layer in the 5 GHz Band, IEEE (1999). 2) IEEE Std g-2003: Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Amendment 4: Further Higher Data Rate Extension in the 2.4 GHz Band, IEEE (2003). 3) IEEE P802.11n/D.3.00: Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Amendment 4: Enhancements for Higher Throughput, IEEE (2007). 4) IEEE Std e-2005: Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Amendment 8: Medium Access Control (MAC) Quality of Service Enhancements, IEEE (2005). 5) Yoshida, T., Miyamoto, G., Kuroda, M. and Ishihara, S.: Load balancing of Wireless LAN with network triggered Handover, Proc. WPMC 05, pp (2005). 6) LAN 2006 pp.b (2006). 7) LAN NS Vol.103, No.386, pp (2003). 8) Alex, H. and Bob, F.: Radio Resource Management in Wireless LANs, IEEE Communications Magazine, Vol.42, No.12, pp.s9 S14 (2004). 9) Yigal, B., Seung-Jae, H. and Li, E.L.: Fairness and Load Balancing in Wireless LANs Using Association Control, IEEE/ACM Trans. Networking, Vol.15, No.3, pp (2007). 10) Papanikos, I. and Logothetis, M.: A study on dynamic load balance for IEEE802.11b wireless LAN, Proc. COMCON 2001 (2001). 11) Shiann-Tsong, S. and Chih-Chiang, W.: Dynamic Load Balance Algorithm (DLBA) for IEEE Wireless LAN, Tamkang Journal of Science and Engineering, Vol.2, No.1, pp (1999). 12) Fukuda, Y. and Oie, Y.: Decentralized access point selection architecture for wireless LANs Deployability and robustness, Proc. IEEE VTC 2004 Fall, pp (Sep. 2004). 13) Wireless LAN IN Vol.102, No.693, pp (2002). 14) LAN Access Point IN Vol.105, No.628, pp (2005). 15) IEEE802.11e LAN AP 2007 pp.b (2007). 16) Morioka, Y., Minoda, Y., Higashino, T., Tsukamoto, K. and Komaki, S.: Proposal of AP Selection Scheme for QoS Guarantee in Wireless LAN, Proc. COIN- NGNCON2006 (July 2006). 17) Morioka, Y., Minoda, Y., Higashino, T., Tsukamoto, K. and Komaki, S.: Proposal of SIP based AP selection agent system in Wireless LAN, Proc. Pimrc 07 (Sep. 2007). 18) Takeuchi, S., Sezaki, K. and Yasuda, Y.: Access Point Selection Strategy in IEEE802.11e WLAN Networks towards Load Balancing, IEICE Trans. Commun., Vol.J89-B, No.4, pp (2006). 19) 20) SIP Vol.105, No.80, pp (2005). 21) Kashihara, S., Tsukamoto, K. and Oie, Y.: Service-oriented mobility management architecture for seamless handover in ubiquitous networks, IEEE Wireless Communications, Vol.14, No.2, pp (2007). 22) Matsunaka, T., Izumikawa, H. and Sugiyama, K.: An Effective Authentication Procedure Considering User Expiry Time During Handover, Proc. Pimrc 06, pp.1 5 (2006). 23) ITU-T: Recommendation G.711: PULSE CODE MODULATION (PCM) OF VOICE FREQUENCIES, ITU-T (1989). 24) IEEE Std : Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications, IEEE (2005). 25) ITU-T: Recommendation G.107: The E-model, a computational model for use in transmission planning, ITU-T (2005). 26) ITU-T: Recommendation G.109: Definition of categories of speech transmission quality, ITU-T (1999). ( ) ( )

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