Procedure for the determination of the length of a standard code sequence of a CDMA signal

• US 20030202538A1
• Filed: 04/28/2003
• Published: 10/30/2003
• Est. Priority Date: 04/30/2002
• Status: Active Grant

• Current Assignee: Rhode & Schwarz GmbH & Co. KG
• Original Assignee: Rhode & Schwarz GmbH & Co. KG
• Inventors: Nitsch, Bernhard
• Granted Patent: US 7,233,586 B2
• Time in Patent Office: Days
• US Class Current: 370/479
• CPC Class Codes: H04B 1/7077 Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception

Abstract

The invention concerns a procedure for the determination of the length (L_preamble) of a standard code sequence (preamble), which is transmitted in a CDMA signal in a defined code channel, which has a different code class than the code class of the at least one code channel, in which before and/or after the standard code sequence, data are transmitted, and said procedure has the following steps:

the determination of a chip sequence of the CDMA signal corresponding to an assumed hypothetical length (L_hyp) of the standard code sequence,

generation of a symbol-sequence by the decoding of the chip sequence with the code of at least of one of the standard code sequence non-occupied analysis code channels which has the same code class as the code channel of the standard code sequence.

the determination of an estimated value of the performance ({circumflex over (P)}_hyp) of symbol sequence, which corresponds to the hypothetical length (L_hyp) of the standard code sequence.

determine, as to whether or not, the estimated value of the performance ({circumflex over (P)}_hyp) of the symbol sequence of the assumed hypothetical length (L_hyp) of the standard code sequence understeps a predetermined threshold value.

for the case, that the estimated value of the performance ({circumflex over (P)}_hyp) of the symbol sequence of the assumed hypothetical length (L_hyp), of the standard code sequence, understeps the predetermined threshold value, make the decision, that the assumed hypothetical length (L_hyp) of the standard code sequence is correct.

Claims

1. A procedure for the determination of the length (L_preamble) of a standard code sequence (preamble), which is transmitted in a CDMA signal in a defined code channel (3₁), which has a different code class (CC_preamble) than the code class (CC_data) and has at least one code channel (4₀-4₁₅), in which before and/or after the standard code sequence, data are transmitted, and said procedure has the following steps:

a) the determination of a chip sequence of the CDMA signal in accord with an assumed hypothetical length (L_hyp) of the standard code sequence,

b) generation of a symbol-sequence by the decoding of the chip sequence with the code (w₅^CN(v)) at least of one of the standard code sequence non-occupied analysis code channel (3₀), which has the same code class (CC_preamble) as the code channel (3₁) of the standard code sequence.

c) the determination of an estimated value of the performance ({circumflex over (P)}_hyp) of the symbol sequence, which corresponds to the hypothetical length (L_hyp) of the standard code sequence.

d) determine, as to whether or not, the estimated value of the performance ({circumflex over (P)}_hyp) of the symbol sequence of the assumed hypothetical length (L_hyp) of the standard code sequence understeps a predetermined threshold value.

e) for the case, that the estimated value of the performance ({circumflex over (P)}_hyp) of the symbol sequence of the assumed hypothetical length (L_hyp) of the standard code sequence, understeps the predetermined threshold value, make the decision, that the assumed hypothetical length (L_hyp) of the standard code sequence is correct.

f) for the case, that the estimated value of the performance ({circumflex over (P)}_hyp) of the symbol sequence of the assumed hypothetical length (L_hyp), of the standard code sequence does not understep the predetermined threshold value, undertake successive repetition of the step a) to e) with successively lesser assumed hypothetical lengths (L_hyp) of the standard code sequence.

2. A procedure in accord with claim 1, therein characterized, in that for the case in which the estimated value of the performance ({circumflex over (P)}_hyp) of the symbol sequence, even in a case of the shortest possible length of the standard code sequence as the assumed hypothetical length (L_hyp) does not understep the predetermined threshold value, then the decision is to be made, that no standard code sequence exists in the CDMA signal.

3. A procedure in accord with claim 1 or claim 2, therein characterized in that the steps a) to f) are carried out for a plurality of analysis code channels (3₀-3₃₁), which have the same code class (CC_preamble) as the code channel (3₁), and that particular hypothetical length (L_hyp) of the standard code sequence is to be considered as correct, which agrees with the most evaluated analysis code channels (3₀-3₃₁).

4. A procedure in accord with one of the claims 1 to 3, therein characterized, in that before the decoding, a scrambling of the CDMA signal is carried out and in the case of the decoding, the relationship:

5. A procedure in accord with claim 4, therein characterized, that in the case of the determination of the estimated value of the performance ({circumflex over (P)}_hyp) of the symbol sequence of the assumed hypothetical length (L_hyp) of the standard-code sequence, the relationship:

6. A procedure in accord with claim 5, therein characterized, in that the threshold value of the estimated performance ({circumflex over (P)}_hyp) arises from the equation

7. A procedure in accord with claim 6, therein characterized, in that the threshold factor k is equal to ½

.

8. A procedure in accord with claim 6 or claim 7, therein characterized in that, if the following equation is true:

9. A procedure in accord with one of the claims 1 to 8, therein characterized, in that the code class (CC_preamble) of the analysis code channel (3₀) is greater than the code class (CC_data) of the at least one code channel (4₀-4₁₅) for the transmission of data.

10. A computer program with a program code for the execution of all steps in accord with one of the claims 1 to 9, when the program is carried out in a computer or a digital micro processor.

11. A computer program is a program code, which is stored on a machine-readable carrier, for the execution of all steps in accord with one of the claims 1 to 9, when the program is carried out in a computer or a digital micro processor.

12. A digital storage medium with electronically readable control signals, which can coact with a computer or a digital signal processor, so that a procedure in accord with the claims 1 to 9 can be carried out.