Improving Throughput and Availability of Cellular Digital Packet Data (CDPD)
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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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- Cellular Digital Packet Data System Specification, Release 1.0, July 19, 1993.Google Scholar
- W.C.Y. Lee, “Data Transmission via Cellular Systems,” 43rd IEEE Vehicular Technology Conference, May 18–20,1993, Secaucus, New Jersey.Google Scholar
- V. H. MacDonald, “The cellular concept,” The Bell System Technical Journal, January 1979.Google Scholar
- W.C.Y. Lee, Mobile Cellular Telecommunications Systems, New York: McGraw-Hill, 1989.Google Scholar
- N. J. Boucher, The Cellular Radio Handbook. 2d Ed. Mendicino, CA: Quantum, 1992.Google Scholar
- R.E. Blahut, Digital Transmission of Information, Reading Massachusetts: Addison Wesley, 1990.Google Scholar
- P.A. Bello and W. M. Cowan, “Theoretical study of on/off transmission over Gaussian multiplicative circuits,” Proceedings of the IRE National Communications Symposium, Utica, NY, Oct 1962.Google Scholar
- S. Lin and DJ. Costello, Error Control Coding Fundamentals and Applications, Englewood Cliffs, NJ: Prentice Hall, 1983.Google Scholar
- TIA IS-55A, “Recommended Minimum Performance Standards of 800 MHz Dual-Mode Mobile Stations,” September 1993.Google Scholar