发明名称 |
Fleraccesskodning genom att använda böjda sekvenser vid mobilradiokommunikation |
摘要 |
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. |
申请公布号 |
FI970637(A) |
申请公布日期 |
1997.04.11 |
申请号 |
FI19970000637 |
申请日期 |
1997.02.14 |
申请人 |
ERICSSON INC. |
发明人 |
BOTTOMLEY, GREGORY E.;DENT, PAUL W. |
分类号 |
H04Q7/38;H01J13/00;H04B1/707;H04J11/00;H04J13/00;H04J13/16;H04L1/00;H04L1/02;H04L9/00;H04L9/18;(IPC1-7):H04B;H04J |
主分类号 |
H04Q7/38 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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