| 摘要 |
PURPOSE:To conduct high speed code book retrieval even when the size of the code book is large by providing a bit inversion position information generating means generating bit inversion position information and a retrieval means for retrieving a code word and a code vector to the device. CONSTITUTION:A control section 20 references an M1 bit code word bit inverting location information table 18 based on the value k1 of a low-order counter 16 to provide the output of bit inversion location information (v) to a computer section 21. The computer section 21 makes calculation of equation I to inverts a sign of thetav and to update an inner product C and a power G. A comparator section 22 makes discrimination of C<2>Gb>Cb<2>G (C is an inner product, Gb, Cb are parameters, and G is a code vector power). In the case of C<2>Gb>Cb<2>G, optimum parameters Cb, Gb and a variable mb are updated by using the C, G, n, and no updating is made in the case of C<2>Gb<Cb<2>G. Then the value k1, the count (n) are incremented by 1, the information (v) is obtained from the table 18 by the same procedure to update the inner product C and the power G, and a succeeding code word is retrieved by the comparison with the preceding optimum code word. The retrieval above is continued till the value k1 reaches 2M<1>-1. |
