KR100357706B1 - Apparatus for searching preamble a mobile communication base station transciever subsystem - Google Patents

Abstract

The present invention relates to a preamble searching apparatus in a mobile communication base station that can easily find a preamble and an offset by grasping a phase of a received signal. The present invention relates to a mobile communication system having a transmitter / receiver. A phase de-lowating / unscrambling unit for receiving a scrambled signal and a phase shifted signal from the transmitter to restore the phase shift and decoding the scrambled signal; Find the phase by receiving the signal output from the scrambling unit, divide the input signal of the I path by cos (Θ _i ), and divide the input signal of the Q path by sin (Θ _i ) In addition, a Walsh detector for estimating a Walsh function, a signal output from the phase de-lowating / unscrambling unit, and the Walsh detector It consists of an offset detector that detects the offset by removing the Walsh function by multiplying the signal output from it.

Description

Apparatus for searching preamble a mobile communication base station transciever subsystem}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly, to a preamble searching apparatus in a mobile communication base station that can easily find a preamble and an offset by identifying a phase of a received signal.

1 is a block diagram of a general mobile communication system.

As shown in FIG. 1, the mobile station 1 communicates wirelessly with the base station 2, and in particular, a mobile call is possible. The base station 2 communicates with the mobile station 1 wirelessly under the control of the control station 3, and the control station 3 controls the base station 2. The exchange station 4 switches the signal transmitted from the mobile station 1 to another station or another communication network, and switches the signal transmitted from another station or another communication network to the mobile station 1 side.

Since such a mobile communication system is divided into cellular zones and cellular zones, a hand-off occurs when a mobile station moves from one service area (area A) to another service area (area B).

The handoff that occurs here is a soft handoff, which means that when a mobile station moves from one cell to another cell, it simultaneously communicates using two traffic channels allocated from both base stations at the cell boundary. In soft handoff, the mobile station establishes a call path with both base stations.

In this way, since the mobile station occupies two traffic channels in the handoff region, the usage efficiency of each traffic channel is reduced at the base station. For this reason, assuming the same number of traffic channels per base station, the call drop rate in a cellular system providing a soft handoff service is increased.

On the other hand, FDD (Frequency Division Duplex) mode of the 3GPP (3 ^rd Generation Partnership Project) in the specification UE (terminal station, User Equipment) transmits a PRACH (Physical Random Access Channel: Physical Random accessory channels) for UTRA (UMRA Terrestrial Radio Access The base station subsystem (BS) receives and demodulates an offset from a reference time of the UTRA and an access preamble signature.

In addition to evaluating correct phases of various offsets with respect to the received signal, FHT (correlation, or somewhat fewer correlations) of each preamble signature for each offset may be used. Fast Hadamard Transform).

However, if the number of offsets to be evaluated is 1000 and the number of preamble signatures is 16 as in the 3GPP specification, there is a problem in that hardware / software is complicated because 16000 correlations must be performed.

Accordingly, an object of the present invention is to solve the problems according to the prior art, and an object of the present invention is to detect a preamble signature without using fast fast adamant transform (FHT) or correlation. The present invention provides a preamble searching apparatus in a mobile communication base station that can directly obtain a preamble signature by identifying a phase shift and compensating for it.

A feature of a preamble searching apparatus in a mobile communication base station according to the present invention for achieving the above object is, in a mobile communication system having a transmitter / receiver, a phase shifted by receiving a scrambled and phase shifted signal from the transmitter Phase de-lowating / unscrambling unit for recovering the scrambled signal and recovering the phase, and finding the phase by receiving the signal output from the phase de-lowating / unscrambling unit. A Walsh detector for dividing the input signal of the I path by cos (Θ _i ) using the phase, dividing the input signal of the Q path by sin (Θ _i ), adding signals from the two paths, and estimating the Walsh function; Check the offset by removing the Walsh function by multiplying the signal output from the de-lowating / unscrambler with the signal output from the Walsh detector. It consists of an offset detector that.

1 is a block diagram of a general mobile communication system;

2 is a simple configuration diagram of a PRACH transmitter applied to the present invention;

3 is a block diagram of a preamble searching apparatus in a mobile communication base station according to the present invention;

4 is a detailed configuration diagram of the phase de-lowating / unscrambling unit of FIG. 3;

5 is a detailed block diagram of the Walsh detector of FIG.

FIG. 6 is a detailed configuration diagram of the offset detector of FIG. 3.

<Description of the symbols for the main parts of the drawings>

100: phase de-rotating and unscrambling,

110: Walsh detector,

120: offset detector.

Hereinafter, a preferred embodiment of a preamble searching apparatus in a mobile communication base station according to the present invention will be described with reference to the accompanying drawings.

2 is a schematic diagram of a PRACH transmitter applied to the present invention.

As illustrated in FIG. 2, W _{16, j, i} is a Walsh function, an index j, and a period 16 is called an access preamble signature. The access preamble signature uses one of sixteen.

In addition, C _{4096, i} is a scramble code having a period of 4096, which is a GOLD code.

Then, the transmission signal is multiplied by the access preamble signature by the scramble code and transmitted on the I and Q paths.

In the path I, the Walsh function W _{4,3, i} is multiplied and then cos is multiplied.

In addition, the Q path is multiplied by the Walsh function W _{4,2, i} and then multiplied by sin.

Thus, multiplying W _{4,3, i} and W _{4,2, i} is called a phase rotator. Then, I path and Q path are added and then transmitted to the base station.

On the other hand, the receiver of the base station should receive the transmission signal to find out which preamble signature was used and also know the delay of the signal transmitted by the terminal from the base station reference time.

The delay of the signal transmitted by the terminal tests whether the phase is correct for all phases for a predetermined time.

3 is a block diagram of a preamble searching apparatus in a mobile communication base station according to the present invention.

As shown in FIG. 3, a phase de-lowating / unscrambler that recovers the scrambled signal while recovering the phase shift by receiving the scrambled and phase shifted r (t) signal from the transmitter. Phase de-rotating and unscrambling (100) and the signals U _{Z, I} , U _{Z, Q} outputted from the phase de-rotating / unscrambling unit 100 are applied to find a phase and phase of the phase. The Walsh detector estimates W _{16, k, i} by dividing the input signal of path I by cos (Θ _i ) and dividing the input signal of Q path by sin (Θ _i ) and adding the signals from both paths. ) 110 and the Walsh function by multiplying the signals U _{Z, I} , U _{Z, Q} output from the phase de-lowating / unscrambling unit 100 with the signals output from the Walsh detector 110. It consists of an offset detector 120 to remove and detect the offset.

FIG. 4 is a detailed configuration diagram of the phase de-lowating / unscrambled unit of FIG. 3.

As shown in FIG. 4, the first mixer 100-1 mixing the r (t) signal and the cos (W _C t + Θ) signal output from the baseband I path, and the base having 90 degrees out of phase. The second mixer 100-3 mixing the r (t) signal and the sin (W _C t + Θ) signal output from the band Q path and the signal output from the first mixer 100-1 are received. A first low pass filter (H ^* (f)) 100-5 for generating a low band signal and a second low pass filter for receiving a signal output from the second mixer 100-3 to form a low band signal (H ^* (f)) (100-7) and the first low-pass filter (H ^* (f)) 100-5 is output in one direction and the sampled signal is switched and applied to the received signal A third mixer (100-9) for mixing the inverse signal C _{4096, k} * W _{4,3, k} , which is a Walsh function for the scramble code and the pacing lowtading, and the first low pass filter (H ^* ( f)) output from the other side and sampled The switching being applied that is scrambling the received signal code and the L low-rise table dingyong Walsh functions Q-band signal path C _{4096, k} * W _4,2, and a fourth mixer (100-11) for mixing the _k, the Q-path inverse, which is a Walsh function for scramble code and phase low-tading to be applied by switching the sampled signal output in one direction from the second low pass filter (H ^* (f)) 100-7. The fifth mixer 100-13 mixing the signal C _{4096, k} * W _{4,2, k} and the second low pass filter (H ^* (f)) 100-7 are outputted in the other direction and are sampled. And a sixth mixer 100-15 for switching the received signal and mixing the inverse signal C _{4096, k} * W _{4,3, k} , which is a Walsh function for scramble code and phase lowtading, with the applied signal. A first summer (100-17) for adding up the signal output from the third mixer (100-9) and the signal output from the fifth mixer (100-13), and the fourth horn. And a second summer 100-19 that sums the inverse signal output from the summer 100-11 and the signal output from the sixth mixer 100-15.

FIG. 5 is a detailed configuration diagram of the Walsh detector of FIG. 3.

As shown in FIG. 5, a phase detector Θ = tan ^−1, which finds a phase by receiving signals U _{Z, I} , U _{Z, and Q} output from the phase de-lowating / unscrambling unit 100. (U _{Z, I} , U _{Z, Q} )) 110-1 and the phase signal output from the phase detection unit 110-1 to divide the input signal of I path by cos (Θ _i ) to delay the phase. The second phase delay unit for delaying the phase by dividing the input signal of the Q path by sin (Θ _i ) using the first phase delay unit 110-3 and the phase output from the phase detection unit 110-1. (110-5), the first mixing the signal U _{Z, I} output from the phase de-lowating / unscrambling unit 100 and the signal output from the first phase delay unit (110-3) 7 mixer 110-7, the signal U _{Z, Q} output from the phase de-lowating / unscrambling unit 100 and the signal output from the second phase delay unit 110-5 are mixed. 8th mixer (1 10-9), and a third adder for outputting the Walsh function W _{16, k, i} by adding the signal output from the seventh mixer 110-7 and the signal output from the eighth mixer 110-9 ( 110-11).

FIG. 6 is a detailed configuration diagram of the offset detector of FIG. 3.

As shown in FIG. 6, the signal U _{Z, I} output from the phase de-lowating / unscrambling unit 100 and the signal W _{16, k, i} output from the Walsh detector 110 are mixed. The ninth mixer 120-1, the signals U _{Z and Q} output from the phase de-lowating / unscrambling unit 100 and the signals W _{16, k} output from the Walsh detector 110 _. a tenth mixer 120-3 for mixing _i , a first integrator 120-5 for integrating a signal output from the ninth mixer 120-1, and the tenth mixer 120-3 A second integrator 120-7 for integrating the signal output from the first integrator, a first squarer 120-9 for squaring the integral signal output from the first integrator 120-5, and the second integrator A second squarer (120-11) that squares the integrated signal outputted from (120-7), a signal output from the first squarer (120-9) and an output from the second squarer (120-11) outputting the Z _k by summing the signals and Claim 4 is composed of summing amplifier (120-13).

The operation of the preamble searching apparatus in the mobile communication base station configured as described above is as follows.

First, the phase de-lowating / unscrambling unit 100 receives a scrambled and phase shifted r (t) signal from the transmitter, restores the phase shift, and decodes the scrambled signal to detect the Walsh detector. Output to the 110 and the offset detector 120, respectively.

The Walsh detector 110 receives a signal U _{Z, I} , U _{Z, Q} output from the phase de-lowating / unscrambling unit 100 to find a phase and inputs an I path using the phase. The signal is divided by cos (Θ _i ), the input signal of the Q path is divided by sin (Θ _i ), the signal is added from the two paths _, and W _{16, k, i} is estimated and output to the offset detector 120.

In particular, if the received signal is in phase with the code generated locally at the base station,

U _{Z, I} = A _i cos (Θ _i ) * W _{16, j, i} ,

U _{Z, Q} = A _i cos (Θ _i ) * W _{16, j, i}

Becomes Where A _i represents attenuation.

The offset detector 120 multiplies the signals U _{Z, I} , U _{Z, Q} output from the phase de-lowating / unscrambler 100 with the signal output from the Walsh detector 110. The function is removed to detect the energy of the offset signal.

The operation of the phase de-lowating / unscrambling unit 100 will be described in detail with reference to FIG. 4 as follows.

First, the first mixer 100-1 mixes a cos (W _C t + Θ) signal with an r (t) signal output from the baseband I path, thereby providing a first low pass filter (H ^* (f)) (100). Output the signal with -5).

In addition, the second mixer 100-3 mixes the sin (W _C t + Θ) signal with the r (t) signal output from the baseband Q path that is 90 degrees out of phase with the I path to form a second low pass filter. Output the signal to (H ^* (f)) (100-7).

Here, the cos (W _C t + Θ) and sin (W _C t + Θ) signals multiplied by the baseband I path and the baseband Q path are for time delay.

The first low pass filter (H ^* (f)) 100-5 filters the signal output from the first mixer 100-1 into a low band to filter the third mixer 100-9 and the fourth mixer. Output to mixer 100-11.

In this case, the third mixer 100-9 is multiplied by the I path reverse signal C _{4096, k} * W _{4,3, k} , and the fourth mixer 100-11 is the Q path reverse signal C _{4096, k} *. W _{4,2, k} is multiplied.

In addition, the second low pass filter (H ^* (f)) 100-7 filters the signal output from the second mixer 100-3 to a low band to filter the fifth mixer 100-13 and the sixth mixer. Output to mixer 100-15.

In this case, the fifth mixer 100-13 is multiplied with the Q path inverse signal C _{4096, k} * W _{4,2, k} , and the sixth mixer 100-15 has the I path inverse signal C _{4096, k} *. W _{4,3, k} is multiplied.

The third mixer 100-9 and the fifth mixer 100-13 output signals to the first combiner 100-17. Accordingly, the first summers 100-17 output the signals U _{Z, I} which are scrambled and whose phase shift is restored.

In addition, the fourth mixer 100-11 and the sixth mixer 100-15 output signals to the second combiner 100-19. Accordingly, the second summer 100-19 outputs signals U _{Z and Q} which are scrambled and whose phase shift is restored.

The operation of the Walsh Detecter 110 will now be described in detail with reference to FIG. 5.

First, the phase detector Θ = tan ^-1 (U _{Z, I} / U _{Z, Q} ) 110-1 is a signal U _Z, output from the phase de-lowating / unscrambling unit 100 _{, I} , U _{Z, and Q} are applied to find the phase and output the phases to the first phase delay unit 110-3 and the second phase delay unit 110-5.

At this time, the first phase delay unit 110-3 divides the phase of the I path by cos (Θ _i ) and outputs the result to the seventh mixer 110-7.

In addition, the second phase delay unit 110-5 divides the phase of the Q path by sin (Θ _i ) and outputs the result to the eighth mixer 110-9.

In addition, the seventh mixer 110-7 is output from the signal U _{Z, I} signal and the first phase delay unit 110-3 outputted from the phase de-lowating / unscrambling unit 100. The signals are mixed and output to the third summer 110-11.

In addition, the eighth mixer 110-9 may be output from the signals U _{Z and Q} signals output from the phase de-lowating / unscrambling unit 100 and the second phase delay unit 110-5. The signals are mixed and output to the third summer 110-11.

Therefore, the third summer 110-11 adds the signals output from the seventh mixer 110-7 and the eighth mixer 110-9, estimates W16, k, and i, and calculates the estimated Walsh function. Output to the offset detector 120.

The operation of the offset detector 120 will now be described in detail with reference to FIG. 6.

First, the ninth mixer 120-1 is a signal U _{Z, I} output from the phase de-lowating / unscrambler 100 and a signal W _{16, k,} output from the Walsh detector 110 _{. i} is mixed and output to the first integrator 120-5.

In addition, the tenth mixer 120-3 may output signals U _{Z and Q} output from the phase de-lowating / unscrambling unit 100 and signals W _{16, k} and output from the Walsh detector 110 _{. i} is mixed and output to the second integrator 120-7.

The first integrating unit 120-5 and the second integrating unit 120-7 integrate the signals output from the ninth mixer 120-1 and the tenth mixer 120-3 by Nw, respectively. And output to the first squarer (120-9) and the second squarer (120-11).

Subsequently, the first squarer 120-9 and the second squarer 120-11 output a signal to the fourth summer 120-13.

Accordingly, the fourth summer 120-13 adds the first squarer 120-9 and the second squarer 120-11 to detect the offset, and the energy of the offset is synchronized. Is detected and has a value close to '0' for an offset that is not synchronized.

As described above, the present invention has the effect of greatly reducing the H / W complexity of an offset detector that can be generally used by obtaining an access preamble signature for each offset using a Walsh detector and multiplying the offset to detect the energy. .

Claims (4)

In a mobile communication system having a transmitter / receiver, A phase de-lowating / unscrambler configured to receive a scrambled and phase shifted signal from the transmitter to restore the phase shift and to decode the scrambled signal; Find the phase by receiving the signal output from the phase de-lowating / unscrambling unit, and divide the input signal of I path by cos (Θ _i ) by using the phase, and divide the input signal of Q path into sin ( A Walsh detector for estimating a Walsh function by dividing by Θ _i ) and adding signals from two paths; Preamble search in the mobile communication base station, characterized in that the offset detector for detecting the offset by removing the Walsh function by multiplying the signal output from the phase de-lowating / unscrambling unit and the signal output from the Walsh detector Device. The method of claim 1, The phase de-lowating / unscrambling unit comprises: a first mixer for mixing the r (t) signal and the cos (W _C t + Θ) signal output from the baseband I path; A second mixer for mixing the r (t) signal and the sin (W _C t + Θ) signal outputted from the baseband Q path having a phase difference of 90 degrees; A first low pass filter receiving a signal output from the first mixer to produce a low band signal; A second low pass filter receiving a signal output from the second mixer to produce a low band signal; I path inverse signal C _{4096, k} * W _{4,3, which is a} Walsh function for scramble code and phase low tapering, is applied by switching a sampled signal output in one direction from the first low pass filter _. a third mixer for mixing _k ; Q path inverse signal C _{4096, k} * W _{4,2, which is a} Walsh function for scramble code and pacing lowtading, is applied by switching a sampled signal output from the first low pass filter in the other direction and sampling the signal _; a fourth mixer for mixing _k ; Q path inverse signal C _{4096, k} * W _{4,2, which is a} Walsh function for scramble code and phase low tapering, is applied by switching the sampled signal output from the second low pass filter in one direction and sampled a fifth mixer for mixing _k ; I path inverse signal C _{4096, k} * W _{4,3, which is a} Walsh function for scramble code and pacing lowtading, is applied by switching and sampling the signal outputted from the second low pass filter in the other direction a sixth mixer for mixing _k ; A first summer for adding up the signal output from the third mixer and the signal output from the fifth mixer; And a second adder configured to add an inverse signal output from the fourth mixer and a signal output from the sixth mixer. The method of claim 1, The Walsh detector includes: a phase detector for finding a phase by receiving signals U _{Z, I} , U _{Z, and Q} output from the phase de-lowating / unscrambling unit; A first phase delay unit for delaying a phase by dividing the input signal of the I path by cos (Θ _i ) using the phase output from the phase detector; A second phase delay unit for delaying the phase by dividing the input signal of the Q path by sin (Θ _i ) by using the phase output from the phase detector; A seventh mixer for mixing the signals U _{Z, I} output from the phase de-lowating / unscrambling unit and signals output from the first phase delay unit; An eighth mixer for mixing the signals U _{Z and Q} output from the phase de-lowating / unscrambling unit and the signals output from the second phase delay unit; And a third combiner for outputting the Walsh function W _{16, k, i} by adding the signal output from the seventh mixer and the signal output from the eighth mixer. The method of claim 1, The offset detector may include: a ninth mixer configured to mix the signals U _{Z, I} output from the phase de-lowating / unscrambling unit and the signals W _{16, k, i} output from the Walsh detector; A tenth mixer for mixing the signals U _{Z, Q} output from the phase de-lowating / unscrambling unit and the signals W _{16, k, i} output from the Walsh detector; A first integrator for integrating the signal output from the ninth mixer; A second integrator for integrating the signal output from the tenth mixer; A first squarer that squares an integrated signal output from the first integrator; A second squarer that squares an integrated signal output from the second integrator; And a fourth summer outputting Z _k by adding the signal output from the first squarer and the signal output from the second squarer.