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Improving Throughput and Availability of Cellular Digital Packet Data (CDPD)

  • Jay M. Jacobsmeyer
Chapter
  • 92 Downloads
Part of the The Springer International Series in Engineering and Computer Science book series (SECS, volume 309)

Abstract

Cellular Digital Packet Data (CDPD) is a packet radio system designed to provide reliable 19.2 kbps data service over the North American cellular phone system. The chief obstacle to high speed data transmission on CDPD is multipath fading. Time-varying amplitude and phase force CDPD to operate at a throughput far below that of equivalent non-fading channels. A new adaptive data rate technique can improve throughput on CDPD by more than a factor of 5. This technique adapts the data rate by varying the number of information bits, k, of a k/k+1 trellis code employing M-ary DPSK or CPFSK modulation. This adaptive trellis code ensures that we can raise the data rate without expanding the bandwidth. A novel soft-decision Viterbi decoder performs error correction, signal estimation, and rate changing in a single device. The built-in estimator automatically estimates the channel carrier-to-interference ratio with a standard deviation of 25 dB. An added benefit of the adaptive rate scheme is an increase in the service area of 17% for an omnidirectional cell and 9% for a directional cell.

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Copyright information

© Springer Science+Business Media Dordrecht 1995

Authors and Affiliations

  • Jay M. Jacobsmeyer
    • 1
  1. 1.Pericle Communications CompanyColorado SpringsUSA

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