KR19980045887A - Parallel Parallel Correlator - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low speed parallel correlator, and to a low speed parallel correlator which enables the simultaneous calculation of multiple correlation values using a single fast adder and a latch for storing data.

Description

Low speed parallel adder

The present invention relates to a low speed parallel correlator, and more particularly, to a low speed parallel correlator used in an initial synchronization acquisition device of a CDMA system.

In general, the base station initial synchronization device of the CDMA system needs a high speed correlator because it needs to find the initial synchronization of the CDMA signal reaching the base station in a short time. As a method of implementing such a high speed correlator, there is a method of using one high speed correlator and a method of obtaining a high speed effect by connecting a plurality of low speed correlators in parallel, and when using the high speed correlator, a high speed multi-bit adder is required. . In addition, since the EPLD implementation of the high speed single correlator has a speed limitation, it is generally more advantageous to use several low speed correlators in parallel. However, such a slow parallel correlator requires a multi-bit adder for each correlator, which is complicated in hardware and increases the area of hardware.

Accordingly, an object of the present invention is to provide a low speed parallel correlator that can solve the above disadvantages by using a high speed single multi-bit adder and a latch for storing data.

According to the present invention for achieving the above object, the signal input means, the PN signal generating means, and the signals input from the signal input means are made into K identical signals, and the PN code generated from the PN signal generating means is the Kth. And delay the output of each delayed output signal with the signal output means from the signal input means and the PN delay means, and the signal output from the input signal copy and PN delay means is input to the chip speed according to the control signal An input signal multiplexing means for selecting and outputting one pair of the input signal and the PN code pair, a cumulative value multiplexing means for outputting one cumulative value stored in the cumulative value storing means, and an output from the cumulative value multiplexing means; Adds an input signal value according to a PN code outputted from the input signal multiplexing means to a cumulative value; Affiliated is characterized by consisting of the adder means, and said adder demultiplexer for receiving a signal outputted from the means on, the demultiplexer for receiving the signals output from each correlation value storage means.

1 is a conceptual diagram of a CDMA system initial synchronization acquisition device to which the present invention is applied.

2 is a structural diagram of a CDMA system initial synchronization acquisition device using a general serial correlator.

3 is a structural diagram of a CDMA system initial synchronization acquisition device having a parallel correlator using a data storage latch and a multiplexer;

4 is a detailed diagram of a CDMA system initial synchronization acquisition device having a parallel correlator using a data storage latch and a multiplexer.

Explanation of symbols on the main parts of the drawings

101: signal data input means 102: correlator means

103: PN generator means 104: correlation value storage means

105: processing means 210: correlator means

211: input data 212: sign converter

213: Multiplexer 214: Addition and storage means

220: correlation value storage means 221 and 222: correlation value 0 and correlation value N

230: PN generator means 240: treatment means

310: signal input means 320: correlator means

321: input signal multiplexing means 322: adder means

323: demultiplexer 324: input signal copy and PN delay means

325: cumulative value multiplexing means 326: cumulative value storage means

330: PN generation means 340: Correlation value storage means

350: processing means 410: signal input means

420: input signal copying and PN delay means 430: PN generating means

440: input signal multiplexing means 450: adder means

460 demultiplexer 470 cumulative value multiplexing means

480: cumulative value storage means 490: correlation value storage means

The present invention proposes a method that can achieve an effect similar to that of a low speed correlator in parallel by a multiplexing technique using a single fast adder and a latch for storing data. Next, the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram of a CDMA system initial synchronization acquisition device to which the present invention is applied, wherein the J-bit data of the chip rate input from the data input unit 101 and the 1-bit PN data correlator unit 102 generated by the PN generation unit 103 are shown. ), The correlation value is calculated. The correlation value for the calculated one PN offset is stored in the correlation value storing means 104. This process is repeated for a certain number of PN offsets, and then each correlation value data is stored in the correlation value storage means 104 and read by the processing means 105. The processing means 105 detects the initial synchronization of the signal using the correlation value read from the correlation value storage number 104.

2 is a structural diagram of an initial synchronization acquisition device of a CDMA system using a general serial correlator, wherein the correlator means 210 has one terminal (0) of J-bit input data 211 whose sign is changed by the code converter 212. Is input through the multiplexer (MUX) 213 to which the J-bit input data 211 is input, and two PN data generated by the PN generator means 230. It consists of a multiplexer 213 for selectively sending the input data to the addition and storage means 214. In this case, if the output of the PN generator means 230 is 0, the data converted from the sign of the input data is sent to the addition and storage means 214. If the output of the PN generator means 230 is 1, the input data is intact. The addition and storage means 214 is sent. Here, the correlator means 210 repeats the addition by the integration period to obtain a final correlation value for one PN offset. The correlation value for the one PN offset thus obtained is stored in one memory, for example, the correlation value 0 memory 221 in the correlation value storage unit 220. In this way, all correlation values for N PN offsets are obtained and stored in each correlation value memory. Thereafter, when the values are input to the correlation value N memory 222 and all the values are stored in the correlation value memory, all N correlation data are sent to the processing means 240. The processing means 240 detects the maximum PN offset value by using the correlation value received from the correlation value storing means 200. This general serial initial synchronization acquisition device has a disadvantage in that the initial synchronization acquisition time is very long. . In other words, if the chip speed is 4,096Mcps, the integration period is 512 chips, and the window length is 512, the maximum synchronization acquisition time is calculated as in Equation (1) below. However, it is assumed here that the shift interval of the input data is one chip.

512 × 512 / (4.096 × 10 ⁶ ) = 64 msec. (1)

3 is a structural diagram of a CDMA system initial synchronization acquisition device having a parallel correlator using a data storage latch and a multiplexer, which is generated from the signal input means 310 and the PN generation means 330 at a chip rate of K bits. The PN data input at the chip rate of 1 bit is input to the correlator means 320. Herein, the internal operation of the correlator means 320 will be described.

The input signal copying and PN delaying means 324 copies the data input at the K-bit chip rate into K data of the same bit and then outputs the same to the input multiplexing means 321. In addition, the input signal copying and PN delay means 324 uses the output generated in each delay step while delaying PN data input at the chip speed of 1 bit from the PN generating means 330 by (K-1) times. Generate K 1-bit PN signals. Each generated signal is outputted to the input multiplexing means 321. The input signal multiplexing means 321 multiplexes the J-bit K input signals and the delayed K 1-bit PN signals output from the input signal copying and PN delay means 324 to output one J input signal and one PN. After generating the code, the generated signal is output to the adder means 322 at K times the chip speed. As described above, the input signal multiplexing means 321 inputs a pair of K input signals and PN codes of chip speed to the adder means 322 at K times the chip speed. The adder means 322 adds or subtracts a signal input from the input signal multiplexing means 321 to an accumulator value input by the cumulative value multiplexing means 325 according to a PN code, and adds the result to the demultiplexer. (DEMUX) 323 is stored in the corresponding storage space of the cumulative value storage means 326 again. In this way, a correlation value with PN codes of K offsets can be calculated for one input signal. In this way, the correlation values for the K PN offsets are simultaneously obtained as input data for one integration period, and the result is stored in the correlation value storage means 340. When the same process is repeated L times to obtain K × L correlation values, the processing means 350 reads K × L correlation value data. That is, the correlation values for K PN offsets are calculated at the same time using one adder without adding the adder necessary for calculating the correlation value for each PN offset to the correlation value calculation branch of each PN offset. In addition, since the result of adding each input data in the correlation value calculation of each PN offset has the cumulative value storage area instead of the cumulative calculation by the adder, it can be used by multiplexing with one adder. When the synchronous acquisition time of the initial synchronization acquisition device of the CDMA system using the correlator of this type is calculated under the same assumption as used in Equation (1), Equation (2) is given.

512 × 512 / K (4.098 × 10 ⁶ ) = 64 / K msec (2)

In Equation (2), it can be seen that the acquisition time is inversely proportional to K. In other words, it can be seen that as more branches obtain correlation values for multiple PN offsets at the same time, synchronization acquisition time decreases. This is the advantage of the parallel correlator.

4 is a detailed diagram of a CDMA system initial synchronization acquisition device having a parallel correlator using a data storage latch and a multiplexer, wherein the input signal copy and PN delay means 420 is a J-bit chip rate input from the signal input means 410. The signals of K are made into K identical signals and output to the input signal multiplexing means 440. Then, the 1-bit PN code generated by the PN signal generating means 430 is delayed up to K-1, and each output is output to the input signal multiplexing means 420 as the signal output from the signal input means 410. do. At this time, the signal input 421 of the J bit chip rate and the PN code 422 of mK-1 are simultaneously input to the input signal multiplexing means 440, and the signal input 423 of the same J bit chip rate is offset (m−). 1) It is input to the input signal multiplexing means 440 simultaneously with the PN code 424 which is K. The input signal multiplexing means 440 selects one pair of the input signal input at the chip speed and the K pair of PN codes according to the control signal, and outputs the pair to the adder means 450 of K times the chip speed. The cumulative value multiplexing means 470 stores one cumulative value selected by the input signal selection control signal used in the input signal multiplexing means 440 among the cumulative values stored in the cumulative value storing means 480 to the adder means 450. Is entered. The adder means 450 adds or subtracts the input signal value according to the PN code output from the input signal multiplexing means 440 to the accumulated value output from the accumulated value multiplexing means 470. The result added or subtracted by the adder means 450 is stored by the demultiplexer 460 as the cumulative value storage means 480 again. In addition, referring to the calculation order between the input signal and the cumulative value in the adder means 450, the K-th branch input signal 423 is always the cumulative value storage means 480 by the PN code of the offset m-1. The cumulative value store (m-1) in K481 is added and subtracted. This process works the same in all K branches. In the case of a system having L integration periods, when a correlation value is obtained for an input signal, each of the K outputs of the adder means 450 after the addition and subtraction of each PN offset with respect to the L-th input signal is accumulated. Is stored in the correlation and storage means 490 by the demultiplexer 460 without being stored back into the cumulative value store. At this time, the cumulative value storage units of the cumulative value storage unit 480 are reduced to initial values. In this way, the correlation values with K PN offsets are simultaneously calculated using L input signals. The correlation value calculation circuit for the K PN offsets is obtained by one adder means 450, a multiplexer and a cumulative value storage means ( 480).

As described above, according to the present invention, a correlation value for several PN offsets can be obtained at the same time by using a single fast adder and a latch for storing data, thereby achieving the same effect as configuring multiple low-speed correlators in parallel. Therefore, a low speed parallel correlator can be configured which can easily improve the synchronization speed of the initial synchronization device of the CDMA system. With this method, the number of parallel correlators that can be implemented with one adder is limited by how fast the fast adder circuit is than the chip speed of the input data. In other words, if the adder operates P times faster than the chip speed, the number of parallel correlators that can be implemented with one adder is P. Therefore, such a structure can reduce the burden on the hardware associated with the implementation of the multi-bit adder to enable the initial synchronization acquisition device of the efficient CDMA system and relatively simplify the structure of the hardware. Therefore, by using the same type of correlator in parallel, it is possible to implement a very early CDMA system early acquisition device with little hardware burden.

Claims (1)

Signal input means, PN signal generating means, An input signal which makes the input signals from the signal input means into K identical signals, delays the PN code generated from the PN signal generating means to the Kth, and outputs each delayed output together with the signal output from the signal input means; Signal copying and PN delay means, An input signal multiplexing means for receiving a signal output from the input signal copying and PN delay means and selecting and outputting one pair of the input signal and the PN code pair according to a control signal; Cumulative value multiplexing means for outputting one cumulative value among the cumulative values stored in the cumulative value storing means; An adder means for adding or subtracting an input signal value according to a PN code outputted from the input signal multiplexing means to a cumulative value outputted from the accumulated value multiplexing means; A demultiplexer for receiving a signal output from the adder means; And a correlation value storing means for receiving a signal output from the demultiplexer.