1. Performance Analysis of Decentralized RAN (Radio Access Network) Selection Schemes December 28 th, 2004 Yang, Sookhyun

2. 2/17 Contents Introduction Previous Works RAN Selection Schemes Evaluation Method Performance Analysis Conclusion

3. 3/17 Background Emerging various wireless access technologies –2G, 3G celluar, satellite, WiBro/WiMax (IEEE 802.16), Wi-Fi (IEEE 802.11a/b/g), Bluetooth (IEEE 802.15) In the Fourth-generation (4G) wireless network –Multiple broadband wireless access –Seamless mobility across heterogeneous networks (HPi) WWAN: large coverage, high cost WLAN: high speed, moderate cost WPAN: small area, low speed, low cost

4. 4/17 Motivation RAN Discovery –Discover available access networks –Scan a wide range of frequencies –Power management RAN selection –Determine the optimal access network among available RANs –Many selection parameters User’s network preference Communication charge Available bandwidth Power dissipation Bluetooth Wi-Fi Satellite WiMax Celluar

5. 5/17 Previous Works Centralized approaches –A centralized server collects and monitors available RANs –A centralized server manages a mobile host’s position (GPS) –BAN (Basic Access Network)-based scheme –WISE (Wise Interface Selection) Decentralized approaches –A mobile host itself monitors available RANs –PPM (Power and Performance Management) –NAV (Network Allocation Vector)-based scheme

6. 6/17 Decentralized Approaches RAN discovery –Periodically turns on NICs (Network Interface Card) –Static or Dynamic period –All NIC or a CAN (Candidate Access Network) RAN selection –QoS guarantee –Signal strength is increasing –Minimum power consumption –Select before a handoff occurs –Handoff occurs when QoS does not guarantee

7. 7/17 How to discover available RANs Static/Dynamic period –Static period ∝ {network’s coverage} –Dynamic period ∝ –{mobile host’s velocity} ≈ {∆signal strength} CAN (Candidate Access Network) –Pre-select the optimal RAN among available RAN as a CAN –Periodically check that a selected CAN guarantees QoS {network’s coverage} {mobile host’s velocity}

8. 8/17 How to select the optimal RAN

9. 9/17 Objective Evaluate the performance of the following RAN selection schemes –Static period with a CAN –Dynamic period with a CAN –Static period without a CAN –Dynamic period without a CAN –Continuously active scheme Performance Metrics –Achieved bandwidth –Number of handovers –Power consumption per seconds

10. 10/17 Evaluation Environments AP BS NS2’s mobility generator 2.4Mbps Signal is Good~! 1.2Mbps Signal is not good~! 0Mbps Signal is bad~! BS AP BS

11. 11/17 Configuration Mobile node –100 nodes, maximum 11m/s ( ≒ 40km/h) –Equipped with all types of network interfaces Network characteristics Coverage (Km) Bandwidth (Mbps) Type 2.52.4CDMA1X 15802.16 0.454802.11a 0.411802.11b 0.454802.11g Transmit (J/Mbits) Idle (W) Receive (J/Mbits) 1.1690.0820.206 (0.264)(0.2)(0.13) 0.02210.035 0.2050.750.123 0.0370.750.026 Off (W) ON (W) -- -- -- 1.7(1ms)2.3(0.3s) -- Power Consumption

12. 12/17 Network Topologies (a)Insufficient network resource (b) Sufficient network resource

13. 13/17 Achieved bandwidth (a)Insufficient network resource(b) Sufficient network resource Performance Analysis (1/3)

14. 14/17 Number of handovers (a)Insufficient network resource(b) Sufficient network resource Performance Analysis (2/3) QoS degradation

15. 15/17 Power consumption per Sec (a)Insufficient network resource(b) Sufficient network resource Performance Analysis (3/3) 4.5 ~ 40% of a continuously active

16. 16/17 Observations and Analysis Four selection schemes show the same achieved bandwidth Dynamic or a CAN give large energy-saving But, when bandwidth is sufficient –Static/dynamic with a CAN trigger too many handovers But, when bandwidth is not sufficient –Static with a CAN consumes more power than Dynamic without a CAN

17. 17/17 Conclusion Evaluated decentralized approaches for RAN selection Implemented a simulator for wireless overlay network environment Dynamic with a CAN reduces large amount of power consumption without degrading achieved bandwidth But, too many handovers occur when bandwidth is sufficient

18. 18/17

19. 19/17 Network Topologies (a)Insufficient network resource (b) Sufficient network resource CDMA1X (4) 802.11b (31) 802.11g (10) 802.16 (10) 802.11a (10) CDMA1X (4) 802.16 (20) 802.11a (21) 802.11g (26) 802.11b (25) 65 96