CDMA450 1xEVDO Performance in Long-Distance Backhauls

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CDMA450 1xEVDO Performance in Long-Distance
Backhauls

• Sergiu Nedevschi, Sonesh Surana
• U.C. Berkeley

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CDMA 450

• CDMA2000 standard operating at 450MHz
• Advantages of 450MHz
• Better propagation, smaller loss
• Larger coverage per basestation, fewer
  basestations
• Universal coverage at reduced initial cost

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CDMA 1xEV-DO

• EVolution Data Only
• Another channel dedicated to data transfer
• Leverages same RF characteristics as CDMA1xRTT
• Small incremental effort for upgrading to EV-D0
• Characteristics
• Download BW 2.4Mbps max, 100-200kbps typical
• Upload BW 155Kbps

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CDMA450 1x EV-DO is Promising
450 MHz 850MHz 1900MHz
Dense Urban 2.8 1.8 0.8
Urban 3.0 1.9 0.9
Suburban 5.9 4.0 2.3
Rural 19.4 14.0 8.8
Cell radius
Typical Pop/ KM2 450 MHz 850MHz 1900MHz
Dense Urban 15000 305,525 126,263 24,941
Urban 7500 175,365 70,341 15,783
Suburban 1500 135,655 62,352 19,729
Rural 100 97,788 50,921 20,119
Population per cell
Underserved Rural ?
Solution increase range even further !
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Enhancing Performance at Cell EdgeFixed vs.
Mobile

• High-gain directional antennas
• 9-12 db Yagi antennas
• Enhanced transmit power device
• Problem with mobile devices reverse link
  bottleneck
• Fixed local-loop phones up to 2W (vs. 200mW
  mobile)
• Receive diversity
• Problem with mobile handsets difficult to have
  small factor with 450MHz antennas for receive
  diversity
• Fixed phones form factor non-important

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ZAPP Network
ROMANIA
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Signal Quality
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Signal Quality
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Signal Quality
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Upload Throughput
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Download Throughput
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Conclusions

• In fixed settings, 1xEVDO in 450MHz band can be
  used for backhauls over 50Kms long
• Sites at 50Km getting 1.9Mbps (very close to
  maximum)
• Maximum distance limited by software
• Current limitations related to link asymmetry
• Addressed in 1xEV-DO rev. A
• Higher TX power for terminals required
• Both directive antennas and dual receive are
  essential in long-range performance
• Economically feasible?