Accession Number : ADP006892

Title :   A Reliable Multi-User Distributive HF Communications System using Narrowband CDMA,

Corporate Author : NORWEGIAN TELECOMMUNICATIONS REGULATORY AUTHORITY OSLO

Personal Author(s) : Miller, T. E.

Report Date : JUN 1991

Pagination or Media Count : 8

Abstract : This paper describes the principles, design and application of a new type of code-division multiple-access (CDMA) communications system. In such a multi-user communications system, the two main constraints placed upon the codes used are that they should have inverse repeat time domain properties and that their periods should be in the ratio 1 :2: 4 .... 2n. This ensures that the line spectral components of the transmitted sequences do not coincide, and thus the codes am uncorrelated in the time domain. It is also important for these codes to have an autocorrelation function (ACF), which approximates to an impulse, so they can be conveniently detected using matched filters. An HF multi-user system has been developed which makes use of multi-level pseudorandom sequences, particularly p-level m sequences. The clock rate of these sequences is adjusted so that the major spectral energy is transmitted within a nominal HF 3kHz bandwidth.

Descriptors :   *MULTIPLE ACCESS, *SIGNAL PROCESSING, *COMMUNICATION AND RADIO SYSTEMS, AUTOCORRELATION, ENERGY, FILTERS, MATCHED FILTERS, RATIOS, SEQUENCES, TIME, TIME DOMAIN, HIGH FREQUENCY, CHANNELS, NOISE(ELECTRICAL AND ELECTROMAGNETIC), WHITE NOISE, GAUSSIAN NOISE, RADIOFREQUENCY, REPRINTS, SYMPOSIA.

Subject Categories : Radio Communications
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE