发明名称 |
CIPHERING FOR CODE DIVISION MULTIPLE ACCESS CELLULAR RADIO |
摘要 |
<p>Individual information signals encoded with a common block error-correction code are assigned a unique scrambling mask, or signature sequence, taken from a set of scrambling masks having selected correlation properties. The set of scrambling masks is selected such that the correlation between the modulo-2 sum of two masks with any codeword in the block code is a constant magnitude, independent of the mask set 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 scrambling 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.</p> |
申请公布号 |
NZ251900(A) |
申请公布日期 |
1996.10.28 |
申请号 |
NZ19930251900 |
申请日期 |
1993.04.08 |
申请人 |
ERICSSON GE MOBILE COMMUNICATIONS INC |
发明人 |
DENT, PAUL W;BOTTOMLEY, GREGORY E |
分类号 |
H04Q7/38;H04B1/707;H04J11/00;H04J13/00;H04L1/00;H04L9/00;(IPC1-7):H04K1/00;H04B7/26;H04B1/69;H04B7/216 |
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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