Wireless Access Networks in 100x100

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Wireless Access Networksin 100x100

• Ed Knightly
• ECE/CS Departments
• Rice University
• http//www.ece.rice.edu/knightly

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Status of Residential Broadband
Source Analysys (April 2003)
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And Still Growing
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How Fast is Broadband?

• Average maximum download speed
• Cable 708 kb/sec
• DSL 467 kb/sec
• Report by comScore, 2003

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Wireless Access Networks

• Issue fiber is not always cost effective to
  deploy
• Wireless promises widely deployed Internet access
  to residences, hot spots, and public places
• Goals
• High bandwidth
• High availability
• Large-scale deployment
• High reliability
• Nomadicity
• Economic viability

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WiFi Hot Spots?

• 11 Mb/sec, free spectrum, inexpensive APs/NICs

Carriers Backbone/Internet
T1
Medium bandwidth (wire), sparse, and expensive

• Why? poor economics
• High costs of wired infrastructure (10k
  500/month)
• Pricing U.S. 3 for 15 minutes CH 0.90
  CHF/minute
• Dismal coverage averaging 0.6 km2 per 50 metro
  areas projected by 2005

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Cellular?

• Cellular towers are indeed ubiquitous
• Coverage, mobility,
• High bandwidth is elusive
• Aggregate bandwidths in Mb/sec range, per-user
  bandwidths at dial-up speeds
• Expensive spectral fees and high infrastructure
  costs

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Two Architectures

• Multi-hop Wireless
• Wireless back-haul network
• One-hop Wireless
• Fiber to the neighborhood
• Pole-top wireless
• Issue cost of deployment vs. bandwidth

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TAPs Multihop Wireless Infrastructure

• Transit Access Points (TAPs) are APs with
• MIMO/beam forming antennas
• multiple air interfaces
• enhanced MAC/scheduling/routing protocols
• Form wireless backbone with limited wired
  gateways

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TAPs Multihop Wireless Infrastructure

• Transit Access Points (TAPs) are APs with
• MIMO/beam forming antennas
• multiple air interfaces
• enhanced MAC/scheduling/routing protocols
• Form wireless backbone with limited wired
  gateways

• High bandwidth
• High spatial reuse and capacity scaling
• Opportunistic protocols
• High availability
• Redundant paths and non-mobile infrastructure
• Deployability
• Good economics
• Unlicensed spectrum, few wires, exploit WiFi
  components

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Key Multi-Hop Challenges

• Multi-hop Wireless Architecture
• low infrastructure costs (few wires/free
  spectrum)
• Scale system capacity
• APs will need to forward traffic to wires
• Medium access and protocol design
• distributed opportunistic protocol design
• exploit unique network architecture
• Secure and DoS-resilient protocol design
• Proof-of-concept prototypes and testbeds

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One-Hop Wireless

• Fiber-to-the-neighborhood and one-hop wireless
• Differences with cellular
• No mobility
• Near symmetry of devices
• Both sides can have antenna arrays
• Neither side is battery powered
• Unlicensed spectrum
• Goal 100x100
• Challenges
• Most of multi-hop plus optimizations for one-hop

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Prototype and Testbed Deployment

• FPGA implementation of enhanced opportunistic,
  beamforming, multi-channel, QoS MAC
• Build prototypes and deploy on Rice campus and
  nearby neighborhoods
• Measurement study from channel conditions to
  traffic patterns

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Inter-disciplinary Collaborations

• PHY-Hardware
• Protocols (all layers)
• Economics
• Where is the wireless/fiber boundry
• Distance fiber cost vs. wireless capacity
• Security
• What issues unique to wireless?
• New DoS-resilience challenges

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Summary

• Status quo
• WiFi footprint is dismal
• Cellular is too slow
• TAPs
• Reduce backhaul cost with a multi-hop
  infrastructure
• One-hop wireless
• Increased bandwidth with FTT Neighborhood
• Inter-disciplinary challenges abound
• Wireless architectures
• Protocol design and analysis
• Distributed, scalable, secure,