OVSF code estimation method
A technology of OVSF code and code sequence, applied in the field of WCDMA, can solve the problem of difficult to obtain OVSF code sequence and so on
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Embodiment 1
[0051] Such as figure 1 Shown, a kind of OVSF code estimation method comprises the following steps:
[0052] S1. Preprocessing the received signal;
[0053] S2. Set the initial search spreading factor Sf=512, the initial search sequence number i=1, and the near-zero rate threshold Tnzr of the symbol;
[0054] S3. Take the current spreading factor Sf in the OVSF code tree, despread the preprocessed signal through the OVSF code sequence with the code number i, and calculate the average power value ap(i) of all symbols after the despreading process ;
[0055] S4, judging whether i
[0056] If so, increase the serial number i by 1, and return to step S3;
[0057] If not, then enter step S5;
[0058] S5, set the power value threshold Tap, find all the sequence numbers i satisfying ap(i)>Tap in the OVSF code tree, and enter step S6;
[0059] S6. Calculate in turn the near-zero rate nzr of the symbol corresponding to the despreading process obtained by the se...
Embodiment 2
[0087] In this embodiment, there are 2 users in total, wherein the spreading factor used by user 1 is 256, and the OVSF code whose code number is 162 is used as its spreading code, and the spreading factor used by user 2 is 128, and the OVSF code number is 2 Code is as its spreading code, signal-to-noise ratio SNR=-10dB, adopts the OVSF code sequence of each user's estimation of the inventive method, concrete steps are:
[0088] First, the codes of each layer in the OVSF code tree are numbered according to the sequence numbers i=1,...,Sf, such as figure 2 shown;
[0089] S1. Preprocessing the received signal: Before performing OVSF code sequence estimation, the above I-channel or Q-channel signals need to be normalized, namely:
[0090] X=X / max(X)
[0091] S2, set the initial factor Sf=512, the initial search sequence number i=1, if the absolute value of the symbol after despreading is less than 0.006, the symbol is considered to be close to 0, and the near-zero rate is def...
Embodiment 3
[0102] Randomly generate 1-8 user signals, the spreading factor and code sequence number of the OVSF code used by each user are random, but the OVSF code used by each user satisfies the mutual orthogonal relationship, and the signal-to-noise ratio ranges from -24dB to -2dB, Carry out 100 independent experiments under each signal-to-noise ratio, and the correct rate of ovsf code spreading factor estimation is as follows: Figure 4 As shown, it can be seen from the figure that when the SNR is higher than -15dB, the correct rate of recognition of the OVSF code sequence can reach more than 90%, which reflects the excellent performance of this method under low SNR.
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