free bits the challenge of the wireless internet
Download
Skip this Video
Download Presentation
Free Bits The Challenge of the Wireless Internet

Loading in 2 Seconds...

play fullscreen
1 / 28

Free Bits The Challenge of the Wireless Internet - PowerPoint PPT Presentation


  • 95 Views
  • Uploaded on

Free Bits The Challenge of the Wireless Internet. Roy Yates Rutgers University. Wireless Data over 2G Cellular. Cellular Voice: Anytime Anywhere Slow : 10K bps High cost/bit v cents/min voice = 13 v cents/MB Data over Cellular: Slow and Expensive: 20 cents/min voice = $2.60/MB.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Free Bits The Challenge of the Wireless Internet' - ryder


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
wireless data over 2g cellular
Wireless Data over 2G Cellular
  • Cellular Voice:
    • Anytime Anywhere
    • Slow: 10K bps
    • High cost/bitv cents/min voice = 13v cents/MB
  • Data over Cellular:
    • Slow and Expensive:20 cents/min voice = $2.60/MB
wireless data over 3g cellular
Wireless Data over 3G Cellular
  • Higher speed: 144K or 384K bps
  • 2X or 3X increase in BW efficiency
    • Reverse link pilots
    • Wideband signal processing
    • Better multiplexing, adaptive modulation
  • 2X or 3X reduced cost/bit

But voice is still 10K bps v cents/min = 13v cents/MB

cellular expensive bits
Cellular = Expensive Bits
  • v=1 cent/min = 13cents/MB
  • Fill an MP3 player: 30 MB = $3.90
  • Upload digital camera photos
    • 32 MB = $4.16
  • Sync laptop disk with desktop
    • 50 MB = $6.50
  • 144 kbps Internet access on Amtrak
    • 75K bps average for 3 hours = $13.16
internet access free bits
Internet Access = Free Bits
  • Internet: Applications and attitudes are based on “free” bits
  • Conventional radio access is a toll booth
  • Radio bits need to be “free”

How do we deliver free bits over radio?

anytime anywhere costs but data can tolerate delay
ANYTIME ANYWHERE costs $…but DATA can tolerate delay!
  • Information services: e-mail, voice mail, fax, maps, non-interactive web pages, ...
  • We don’t need ubiquitous coverage
  • Reduced coverage  Higher data rates
  • A little wait might be worthwhile!
infostations
Infostations
  • Network of wireless ports
  • Discontinuous coverage
  • Asymmetric link
  • High data rate transmission
  • Data services
isolated infostation
Isolated Infostation
  • Optimization Problem:
    • With finite energy, how many bits can be delivered?
  • Solution: Wait for the very good channel, blast away!
highway infostations
Highway Infostations
  • Distance attenuation time varying channel
  • Transmit power profile Time Average Capacity[Goldsmith]
coverage capacity delay
Coverage, Capacity, Delay
  • Cellular Infostations
    • Infostationsat BS cellsites
  • Do infostations really offer more capacity?
  • At what delay?
traditional cellular
Traditional Cellular
  • Modulation and BER  SIR threshold
  • SIR  Cluster size N (frequency reuse)
  • For worst-case location!
cell area coverage area
Cell area Coverage area
  • No need for ubiquitous coverage
  • Better Radio Channel
    • Higher received power
    • Less interference
  • Smaller cluster size
  • More bandwidth available

HIGHER DATA RATE!

which system is better
Which system is better?

6M bps (64 QAM)

2M bps (QPSK)

approximate queueing model

Approximate Queueing Model
  • Every Infostation is modeled as an M/M/1 queue with reneging

Reneging: Customersleave before sending all bits

queue parameters
User density, u

Cell radius, R

Mobile speed, v, fV(v)

Coverage radius, r

Data rate, c

Messages per user per second, u

Message size, m

= (2p r)(u/2) E[V]

1/ m = E[X] =

= u tc (m/c)

n = 2E[V]/p r

Queue Parameters

f

q

R

r

2d cycle time
2D Cycle Time

See [Borras & Yates, WCNC 99]

throughput
Throughput

N=1Reuse

(r/R)2

64QAM 6.25%

16QAM 13.7%

QPSK 31.4%

BPSK 43.6%

delay
Delay

Light LoadSimple ModulationWide Coverage

Heavy LoadComplex ModulationLimited Coverage

infostations beyond cellular
Infostations beyond Cellular
  • Cellsites aren’t ideal for Infostations
    • Cellsites are chosen for widest coverage
      • On hills, high towers
  • Infostations exploit being really close
  • Clever (convenient) locations can really help!
optimized locations
Optimized Locations

Download

a map

Low bit-rate

cellular

E-mail voice mail

fax

Internetaccess

cheap bits high rates
Cheap Bits, High Rates!
  • No coverage requirements
    • Lots of interference  range reduced.
    • Range may be zero in places
  • Need a sufficiency of good locations
  • No need for licensed spectrum
    • Use 100 MHz U-NII bands
  • Short range wideband communications
    • VERY High Rates!
infostation applications
Infostation Applications
  • Upload digital camera photos
    • Walking by photo kiosk
    • 32 MB in 3 sec = 80 Mb/s
  • Internet access on Amtrak
    • Infostation every 500 feet
    • 25 ft coverage radius at 400 Mb/s
    • 40 Mb/s average capacity
infostation applications1
Infostation Applications
  • Sync laptop disk with desktop
    • At the airport in the X-ray machine
    • 50 MB in 1 sec = 400 Mb/s
  • Fill an MP3 player
    • While passing thru doorway
    • 30 MB in 2 sec = 240 Mb/s

Very high data rates!!

high rates new applications
High Rates = New Applications
  • Data Sprinklers (or hoses) [Badrinath]
    • Download a local information database
  • Images of everything local
    • Where can I find …… ?
    • What’s that building?
    • Where am I?
  • If bits are fast and free, lots of content can go unused
research problems
Research Problems
  • Network problems
    • Protocols for pre-fetching
    • Coordinated Data Delivery
  • Radio Problems
    • 500 Mb/s in a handset!
    • Channel estimation
      • Finding the coverage sweet spot
    • Coverage/channel shaping
systems research
Systems Research

New problems everywhere in the stack!

Freebits

LimitedCoverage

High Bit Rates

NewApplications

  • Propagation
  • Transceiver
  • Link Layer
  • Networks
  • Applications
ad