A modulus realization structure and realization method of prach baseband signal

Abstract

The invention discloses a PRACH baseband signal modular realization structure and a realization method, This structure is FPGA structure, is used for modulus operation of a product of two 15-bit unsigned integers x and y to 24576, is characterized by comprising a truncator 1 and a truncator 2 for truncating x and y respectively, a S201 module, a S202 module, a S203 module, a S204 module, a S205 module, a S206 module, a S207 module, a S208 module, a S209 module, a S210 module, an adder, a subtractor, a judger and a selector, truncator 1 and truncator 2 have the same structure and all include 10 sub-truncators. The invention simplifies the calculation of the IDFT in the signal generation process through the layer-by-layer truncation to simplify the modulus operation, thereby simplifying thewhole signal generation process.

Description

technical field [0001] The present invention relates to the communication field, in particular to a PRACH (Physical Random Access Channel, Physical Random Access Channel) baseband signal modulo realization structure and realization method. Background technique [0002] In the LTE protocol, the time-continuous random access signal s(t) on the PRACH channel is defined by the following formula: [0003] [0004] Where t represents time, 0≤t<T SEQ +T CP ,T SEQ , T CP The value is related to the preamble format, see Table 1. k 0 Indicates the starting position of the RB occupied by the PRACH, k indicates the RB index within the occupied bandwidth, K indicates the subcarrier spacing difference between the random access preamble and the uplink data, β PRACH Indicates the PRACH signal transmission power coefficient, n indicates the ZC sequence index, T CP Indicates the length of the cyclic prefix, f RA Indicates the random access subcarrier spacing, Indicates the fre...

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Problems solved by technology

[0030] DFT / IDFT transformation is a very complicated operation. When the formula is directly used for transformation, the amount of complex multiplication operation is proportional to the square of the number of points. Therefore, the DFT / IDFT transformation of the above-mentioned points, especially the DFT / IDFT transformation of the format 0--3, is not suitable for direct calculation. , using the DFT / IDFT transformation fast algorithm Cooley-Tukey algorithm can greatly reduce the calculation amount of DFT / IDFT transformation, but the Cooley-Tukey algorithm is a fast algorithm for general signal DFT / IDFT transformation , if the algorithm is used directly when generating the baseband signal of the PRACH channel, the particularity of the ZC sequence is not fully utilized; and the DFT operation is a prime point DFT operation (839 points or 139 points), it is not suitable to use Cooley Tukey (cooley- tukey) algorithm to decompose; IDFT is 24576 points in format 0--3, and 4096 points in format 4, especially in format 0--3, it is a large-point IDFT operation, using cooley-tukey (cooley-tukey) The algorithm still has a lot of computation

In the format 0--3, the IDFT of 24576 points is modulo 24576, and the resource consumption of the existing implementation structure is very large

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