Title:
【発明の名称】移動無線通信用のベント系列を用いた多元接続符号化
Document Type and Number:
Japanese Patent JPH10507322
Kind Code:
A
Abstract:
Information symbols spread using orthogonal or bi-orthogonal codewords are assigned a unique scramble mask that is taken from a set of scramble masks having selected correlation properties. The set of scramble masks is selected such that the correlation between the modulo-2 sum of two scramble masks with any codeword is a constant magnitude, independent of the codeword and the individual masks being compared. In one embodiment, when any two masks are summed using modulo-2 arithmetic, the Walsh transformation of that sum results in a maximally flat Walsh spectrum. For cellular radio telephone systems using subtractive CDMA demodulation techniques, a two-tier ciphering system ensures security at the cellular system level by using a pseudorandomly generated code key to select one of the scramble masks common to all of the mobile stations in a particular cell. Also, privacy at the individual mobile subscriber level is ensured by using a pseudorandomly generated ciphering key to encipher individual information signals before the scrambling operation.
Inventors:
Bot Murray, Gregory E.
Dent, Paul W.
Dent, Paul W.
Application Number:
JP50752195A
Publication Date:
July 14, 1998
Filing Date:
August 11, 1995
Export Citation:
Assignee:
Ericsson Incorporated
International Classes:
H01J13/00; H04B1/707; H04J11/00; H04J13/00; H04J13/12; H04L1/00; H04L1/02; H04L9/00; H04L9/18; H04J13/16; (IPC1-7): H04L9/18; H04J13/00; H04L1/02
Attorney, Agent or Firm:
Akira Asamura (3 outside)