1. 9/18/2003UCAN @ MOBICOM'031 UCAN: A Unified Cellular and Ad-Hoc Network Architecture Haiyun Luo Ramachandran Ramjee Prasun Sinha, Li Erran Li, Songwu Lu

2. 9/18/2003UCAN @ MOBICOM'032 Wireless WAN v.s. LAN 1xEV-DO (HDR) Large coverage Low data rate Infrastructure only IEEE 802.11 Small coverage High data rate Ad-hoc capable Base Station

3. 9/18/2003UCAN @ MOBICOM'033 Wireless WAN v.s. LAN Observations: Commercial applications need availability assurance – only through WAN infrastructure Low data-rate (depending on location) client reduces WAN T’put Goal: Cost-effective way to improve WAN channel utilization, while maintaining fairness Solution: A new network paradigm to improve WAN T’put through opportunistic use of ad-hoc LAN

4. 9/18/2003UCAN @ MOBICOM'034 Motivation: Experiment Verizon Wireless CDMA2000-1X Dual interfaces Verizon Wireless CDMA2000-1X 144Kbps 802.11b 11Mbps Destination Laptop Locate in Lab Room w/ Poor CDMA2000- 1X Channel Relay Computer Locate in Lab Corridor w/ Good CDMA2000-1X Ch’l Destination in Lab Room Relay in Lab Corridor Base Station 802.11b

5. 9/18/2003UCAN @ MOBICOM'035 Results Average T’put No-relay 51.6Kbps Relay 93.9Kbps Max T’put No-relay 95Kbps Relay 130Kbps

6. 9/18/2003UCAN @ MOBICOM'036 Outline UCAN Device UCAN Architecture Base-station assisted routing Incentive provisioning Simulation evaluation Conclusion, future work

7. 9/18/2003UCAN @ MOBICOM'037 UCAN Device Dual interfaces: both 3G WAN and 802.11 LAN Laptops with 3G wireless modem and 802.11 card GTRAN Wireless ‘DotSurfer 5000 Wireless Modem” 802.11b and CDMA2000-1X in a single client card

8. 9/18/2003UCAN @ MOBICOM'038 UCAN Architecture low data-rate high data-rate Poor WAN Channel Good WAN Channel 802.11b Relay Proxy Base Station

9. 9/18/2003UCAN @ MOBICOM'039 Issues high data-rate Poor Channel Good Channel 802.11 Relay Proxy Routing Node mobility HDR channel dynamics Scheduling Incentives WAN operator Proxy & relay 1xEV-DO Base Station

10. 9/18/2003UCAN @ MOBICOM'0310 Routing Proxy discovery, proxy and route maintenance On-demand and greedy proxy discovery Base station assisted error recovery Design principles Leverage always-available HDR links Frugal use of HDR links (downlink and uplink) Client push v.s. base station pull

11. 9/18/2003UCAN @ MOBICOM'0311 On-demand Proxy Discovery BS C A B E J F 1. RtRequest Flooding with Limited Range (2 hops) --- Client Downlink Quality (A:2) C B E F D 2. Proxy Candidates D, E, F, inform BS F E D 3. Base station chooses E as Proxy --- Proxy table: E 2 2 610 5 8 7 1 2 1 1 2 2 2 Dst.Proxy AE

12. 9/18/2003UCAN @ MOBICOM'0312 Greedy Proxy Discovery BS C A B E D F 1. RtRequest Unicast with Range Limit (2 hops) --- A’s Downlink Quality included 2. Base station assigns E as proxy --- Proxy table: E 2 2 610 5 8 7 4 2 1 1 2 2 2 Dst.Proxy AE 0. Maintains one-hop neighboring devices’ downlink channel qual

13. 9/18/2003UCAN @ MOBICOM'0313 UCAN Proxy Discovery On-demand Best proxy within certain range Flooded RTREQ message Multiple Proxy Application messages on HDR uplink Greedy Proactive neighborhood maintenance Unicast RTREQ propagation Single Proxy Application message

14. 9/18/2003UCAN @ MOBICOM'0314 Route Maintenance BS C A E J 1. If B moves away 3. Base station assigns D as proxy --- Proxy table: D 2 2 B 610 5 8 2 Dst.Proxy AD 2. E reports error to Base station 3. Base station proxy table: Dst.Proxy AA B 6 B 6 B 6 B 6 Dst.Proxy AE

15. 9/18/2003UCAN @ MOBICOM'0315 Route Maintenance Proxy downlink channel degradation: Periodical piggyback in data packets Skip the proxy with degraded channel data rate Any case: Route failure detection and recovery (1 single message) Recovery from mobile client (receiver-initiated) HDR base station assisted (fast, efficient, reliable)

16. 9/18/2003UCAN @ MOBICOM'0316 Providing Incentives WAN operators Increased channel utilization through ad-hoc relay Increased channel diversity through HDR base station scheduling No extra equipment cost Clients actively receiving Increased throughput of their own flows through HDR base station scheduling Idle clients ?

17. 9/18/2003UCAN @ MOBICOM'0317 Incentives for Relay Clients Poor Channel Good Channel 802.11 Relay Proxy Refined PF scheduling Use destination’s own channel rate Make entire path available at base station Simplified loop detection Further increased channel diversity Award all relay clients Base Station

18. 9/18/2003UCAN @ MOBICOM'0318 Simulation NAM Snapshot Destination Relay Proxy NS-2 simulation HDR downlink TDMA channel w/ slow and Rayleigh fast fading Proxy discovery and path maintenance HDR scheduling Mobile clients of different densities Multiple FTP/TCP, CBR/UDP flows

19. 9/18/2003UCAN @ MOBICOM'0319 Simulation Summary Throughput gain Single flow w/ 3-hop relay: up to 50% gains with average 1 neighbor, 210% throughput gain with average 4 neighbors Up to 60% aggregate throughput gain in five flow case w/ 3-hop relay – PF scheduling Resilient to node mobility, sensitive to node density Greedy proxy discovery: 50% higher energy consumption on 802.11b interfaces On-demand proxy discovery: Up to 7 times higher overhead on HDR uplink

20. 9/18/2003UCAN @ MOBICOM'0320 Related Work Multi-hop cellular A-GSM, ODMA, MCN: reduce power consumption MADF: tradeoff between channel utilization and complexity iCAR: pre-deployed, dedicated, stationary relay devices Routing for p2p traffic in MANET DSDV, DSR, AODV, TORA, GPSR, LANMAR, LAR Cooperation enforcement (Hubaux et al)

21. 9/18/2003UCAN @ MOBICOM'0321 UCAN Architectural Benefits Integration of two complementary wireless data technologies Cellular networks Improved channel utilization and network throughput w/o additional equipment cost Ad-hoc networks Improved connectivity through more efficient and reliable routing Incentives for commercial application scenarios Other resources in managed WAN infrastructure: key management, time sync, localization …

22. 9/18/2003UCAN @ MOBICOM'0322 Summary A new network paradigm of unified and cellular ad-hoc architecture Opportunistic use of ad-hoc relay to improve wireless WAN throughput Routing, scheduling and incentive provisioning Simulation evaluation Design space for Wireless WAN LAN Collaboration Future work: uplink proxy, multicast, flooding, QoS for p2p traffic