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UCAN: A Unified Cellular and Ad-Hoc Network Architecture

UCAN: A Unified Cellular and Ad-Hoc Network Architecture. Haiyun Luo Ramachandran Ramjee Prasun Sinha, Li Erran Li, Songwu Lu. 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.

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UCAN: A Unified Cellular and Ad-Hoc Network Architecture

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  1. UCAN: A Unified Cellular and Ad-Hoc Network Architecture Haiyun Luo Ramachandran Ramjee Prasun Sinha, Li Erran Li, Songwu Lu UCAN @ MOBICOM'03

  2. 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 UCAN @ MOBICOM'03

  3. 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 UCAN @ MOBICOM'03

  4. 802.11b Motivation: Experiment • 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 Verizon Wireless CDMA2000-1X Base Station Destination in Lab Room Relay in Lab Corridor UCAN @ MOBICOM'03

  5. Results • Average T’put • No-relay 51.6Kbps • Relay 93.9Kbps • Max T’put • No-relay 95Kbps • Relay 130Kbps UCAN @ MOBICOM'03

  6. Outline • UCAN Device • UCAN Architecture • Base-station assisted routing • Incentive provisioning • Simulation evaluation • Conclusion, future work UCAN @ MOBICOM'03

  7. 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 UCAN @ MOBICOM'03

  8. low data-rate high data-rate 802.11b UCAN Architecture Base Station Poor WAN Channel Relay Proxy Good WAN Channel UCAN @ MOBICOM'03

  9. high data-rate 802.11 Issues • Routing • Node mobility • HDR channel dynamics • Scheduling • Incentives • WAN operator • Proxy & relay 1xEV-DO Base Station Poor Channel Relay Proxy Good Channel UCAN @ MOBICOM'03

  10. 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 UCAN @ MOBICOM'03

  11. B F C E F E E 2. Proxy Candidates D, E, F, inform BS 3. Base station chooses E as Proxy --- Proxy table: D On-demand Proxy Discovery 2 1 1. RtRequest Flooding with Limited Range (2 hops) --- Client Downlink Quality (A:2) 1 7 2 F 6 10 2 B E A 2 1 BS C 5 D J 2 8 2 UCAN @ MOBICOM'03

  12. E 2. Base station assigns E as proxy --- Proxy table: Greedy Proxy Discovery 4 2 0. Maintains one-hop neighboring devices’ downlink channel qual 1 7 2 F 1. RtRequest Unicast with Range Limit (2 hops) --- A’s Downlink Quality included 6 10 2 B E A 2 1 BS C 5 D 2 8 2 UCAN @ MOBICOM'03

  13. 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 UCAN @ MOBICOM'03

  14. 6 6 6 6 6 B B B B B 3. Base station assigns D as proxy --- Proxy table: D Route Maintenance 1. If B moves away 2 2. E reports error to Base station 10 3. Base station proxy table: 2 E A BS C 5 J 2 8 UCAN @ MOBICOM'03

  15. 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) UCAN @ MOBICOM'03

  16. 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 ? UCAN @ MOBICOM'03

  17. Incentives for Relay Clients • 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 Poor Channel Relay Proxy Good Channel 802.11 UCAN @ MOBICOM'03

  18. Simulation • 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 Destination Destination Relay Relay Proxy Proxy NAM Snapshot UCAN @ MOBICOM'03

  19. 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 UCAN @ MOBICOM'03

  20. 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) UCAN @ MOBICOM'03

  21. 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 … UCAN @ MOBICOM'03

  22. 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 UCAN @ MOBICOM'03

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