JP3522178B2 - Code division multiple access base station - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a code division multiple access base station. Particularly, the present invention relates to a code division multiple access base station capable of processing a signal having a long delay time.

[0002]

2. Description of the Related Art In order to cope with a change in delay time of a received signal, a conventional code division multiple access (CDMA) base station measures a delay profile of a signal transmission path from the received signal. The delay profile is a response of a signal wave transmitted through different transmission paths and received by the base station. Since signal waves travel through different transmission paths,
The waveform of the signal wave changes under the influence of each transmission line. Therefore, the conventional CDMA base station selects a plurality of peaks having an effective power level and synthesizes the selected peaks to demodulate the received signal.

FIG. 1 shows the structure of a CDMA base station. C
The DMA base station includes an antenna 10, a receiving unit 12, a RACH
Signal receiving unit 14, DCH signal receiving unit 16, and control unit 2
Have six. The RACH signal receiving unit 14 has a delay profile measuring unit 18 and a demodulating unit 20. The DCH signal receiving unit 16 includes a delay profile measuring unit 22 and a demodulating unit 2
Have 4.

The antenna 10 receives a spread spectrum modulated random access channel (RACH) signal and a data channel (DCH) signal.

FIG. 2 shows a random access channel (R
ACH) signal and data channel (DCH) signal
It shows how it is communicated between the base station and the mobile station. First
At 1, the RACH signal is input from the mobile station to the base station to set up the call. The RACH signal contains information such as the telephone number and registration number of the user of the mobile station. In the example of FIG. 2, the RACH message of the RACH signal is 10 ms long. The RACH signal indicates that communication has suddenly started,
It is transmitted by a burst transmission that ends abruptly.

Next, a reception ( ACK ) signal is output from the base station to the mobile station. The ACK signal includes information that the base station has approved the mobile station. The mobile station can then initiate the call and send a DCH signal to the base station. The DCH signal is a call signal set by the RACH signal. The DCH signal starts at a substantially specified time after the ACK signal is transmitted, and ends at a predetermined time after the DCH signal is transmitted. In the example of FIG. 2, each DCH message of the DCH signal has 10
It has a length of milliseconds.

The RACH signal and the DCH signal are two-dimensional complex signals of I phase and Q phase. The receiver 12
The frequencies of the RACH signal and the DCH signal are converted from the carrier frequency band to the baseband frequency band and output to the RACH signal receiving unit 14 and the DCH signal receiving unit 16, respectively. The RACH signal receiving unit 14 receives the RACH signal from the receiving unit 12 in order to despread the RACH signal.

The DCH signal receiving section 16 receives the DCH signal from the receiving section 12 in order to despread the DCH signal. The delay profile measuring unit 18 detects the peak of the RACH signal received from the receiving unit 12, and detects the time when the peak of the RACH signal is received. Next, the delay profile measurement unit 18 outputs the detected peak reception time of the RACH signal to the demodulation unit 20 via the control unit 26. RACH detected by the delay profile measuring unit 18
The demodulation unit 20 despreads the RACH signal received from the reception unit 12 based on the peak reception time of the signal. Next, the demodulation unit 20 outputs the despread and demodulated RACH signal.

The delay profile measuring section 22 includes a receiving section 1
2, the DCH signal is received, the peak of the DCH signal is detected, and the time when the peak of the DCH signal is received is detected.
Next, the delay profile measuring unit 22 detects the detected DCH.
The peak reception time of the signal is sent to the demodulation unit 2 via the control unit 26.
Output to 4. The demodulation unit 24 despreads the DCH signal received from the reception unit 12 based on the peak reception time of the DCH signal detected by the delay profile measurement unit 22. Next, the demodulation unit 24 de-spreads and demodulates D.
Output CH signal.

The control unit 26 includes a delay profile measuring unit 1
For 8 and 22, the type of spreading code for despreading the RACH signal and DCH signal and the timing for generating the spreading code are set. The control unit 26 further inputs the peak reception time of the RACH signal from the delay profile measuring unit 18 and outputs it to the demodulation unit 20. Further, the control unit 26
The peak reception time of the DCH signal is input from the delay profile measurement unit 22 and output to the demodulation unit 24.

The delay profile measuring units 18 and 22 are
Since the delay profile having a long delay time is measured, the base station can receive various delayed signals sent from various places within the cell area of the base station. Each delay profile has a different delay time because the signal travels different transmission paths during the transmission of the signal. At the same time as measuring the delay profile, the control unit 26 controls the demodulation units 20 and 24 to send the RACH signal
Notify the peak reception time of the CH signal. Therefore, the demodulation units 20 and 24 have the RACH with various delay times.
Each of the signal and the DCH signal can be despread.

FIG. 3 shows a detailed configuration of the delay profile measuring section 18. The delay profile measuring unit 18 can measure a delay profile having a long delay time. The delay profile measuring unit 18 includes a RACH signal matched filter 28 and a RACH signal delay profile measuring unit 34. The delay profile measuring unit 18 has a plurality of RACH signal matched filters 28 for despreading the RACH signals sent from a plurality of users.
For simplicity of explanation, only one RACH signal matched filter 28 is shown in FIG. The RACH signal matched filter 28 includes a spread code generator 30 and a complex correlator 3
Have two. The complex correlator 32 may include a complex matched filter. RACH signal delay profile measuring unit 34
Has a power level calculation unit 36, a delay time adjustment unit 38, a delay profile averaging unit 40, and a path detection unit 42.

The RACH signal matched filter 28 receives the RACH signal from the receiver 12 and despreads it. RACH
The signal delay profile measurement unit 34 uses the despread RA
The peak reception time of the RACH signal is detected from the CH signal,
The peak reception time of the RACH signal is output to the control unit 26.

The spread code generator 30 generates a spread code and outputs it to the complex correlator 32. The complex phase shifter 32 uses the spreading code generated by the spreading code generation unit 30 to generate R
Despread the ACH signal. The RACH signal is I phase and Q
Since it is a complex signal having a phase, the signal demodulated by the complex correlator 32 is also a complex signal having an I phase and a Q phase. The power level calculator 36 calculates the absolute value of the I-phase and Q-phase vectors of the demodulated RACH signal in order to obtain the power level of the demodulated RACH signal. By the power level calculation, the two-dimensional data of the demodulated RACH signal having the I phase and the Q phase is converted into one-dimensional data.

The delay time adjusting unit 38 adjusts the delay times of a plurality of delay profiles having different delay times to the same delay time. The delay profile averaging unit 40 has a memory that stores a plurality of delay profiles with adjusted delay times. As shown in FIG. 4 below, the delay profile averaging unit 40 cumulatively adds the respective peaks of the plurality of delay profiles, so that the peaks can be separated from the noise and interference components.

In this case, it is assumed that the RACH signal is spread spectrum modulated by a spread code of 256 chips. The delay profile averaging unit 40 has a function of 51
It has a memory area of 20 words. Here, one chip is equal to 4 words. 5120 words are obtained by multiplying 256 chips by 5 symbol periods and then multiplying by 4, which is the number of oversamplings. The path detection unit 42 detects the peak reception time of the RACH signal by detecting the peak of the RACH signal equal to or more than the threshold.

The delay profile measuring section 22 has the same structure as the delay profile measuring section 18. The delay profile measuring unit 18 and the delay profile measuring unit 22 are
The spreading code used for despreading is different. The spreading code used in the delay profile measuring unit 18 is RAC
The spreading code used for despreading the H signal and used for the delay profile measuring unit 22 is used for despreading the DCH signal. Delay profile measuring unit 18
Similarly, the delay profile measuring unit 22 can measure a delay profile having a long delay time such as 5 symbol periods.

FIG. 4 shows an example of delay profiles of RACH signals output from a plurality of RACH signal matched filters 28. The delay profile is shown with respect to time. Here, the delay profile measuring unit 18 measures the five RACH signal matched filters 28a, 28b, 28c, 2 in order to measure the delay profile of 5 symbol periods.
It has 8d and 28e in parallel. One symbol period is
It has 1024 samples. The delay profile shown in FIG. 4 is transmitted from one mobile station. Since the signal transmitted from the mobile station is transmitted via various transmission paths, the base station receives the delay profile having various delay times.

In FIG. 4, each output of the RACH signal matched filters 28a, 28b, 28c, 28d, and 28e has three peaks. One of the three peaks is the peak of the direct wave, and the remaining two peaks are the peaks of the delayed wave. These three peaks indicate that the RACH signal was transmitted via three paths. The direct wave is directly transmitted from the mobile station to the base station, and the remaining two delayed waves are indirectly transmitted from the mobile station to the base station while being reflected.

The spreading code of the first symbol of the long code is assigned to the RACH signal matched filter 28a. The spreading code of the second symbol of the long code is assigned to the RACH signal matched filter 28b. Similarly, the spreading codes of the third, fourth and fifth symbols of the long code are RACH signal matched filters 28c and 28, respectively.
d and 28e. The spreading code is composed of a long code and a short code. The long code is used to distinguish a specific mobile station from a plurality of mobile stations. The long code has a long period of a plurality of symbol periods. Therefore, even if the same long code is used, the code is changed by changing the timing of generating the code. Therefore, the long code assigned to the RACH signal matched filter 28a is RA
It is different from the long code assigned to the CH signal matched filter 28b.

By assigning the long code first symbol to the RACH signal matched filter 28a for despreading, the first peak appears during the first symbol period. By assigning the second symbol of the long code to the RACH signal matched filter 28b for despreading, a second peak appears during the second symbol period, and so on, as well as the third, fourth and fifth. Peaks appear during the third, fourth, and fifth symbol periods, respectively. Therefore, the delay profile measuring unit 18 can measure the peak of the RACH signal that appears during the period of 5 symbols.

Next, the delay time adjusting unit 38 delays the first peak by 4 symbol periods, the second peak by 3 symbol periods, the third peak by 2 symbol periods, and the fourth peak. Is delayed by one symbol period. Therefore, all peaks in the delay profile have the same delay time of 4 symbol periods. Next, the respective peaks of the five delay profiles are cumulatively added by the delay profile averaging unit 40. That is, the peaks of the direct waves of the respective delay profiles are cumulatively added.
The peaks of the first delayed wave of the respective delay profiles are cumulatively added separately from the peaks of the direct wave and the second delayed wave. The peaks of the second delayed wave of each delay profile are cumulatively added separately from the peaks of the direct wave and the first delayed wave. The delay profile shown below the arrow in FIG. 4 shows the result of cumulative addition of five delay profiles.

[0023]

Similar to the delay profile measuring unit 18, the conventional delay profile measuring unit 22 has five DCH signal matched filters in parallel in order to measure the delay profile of 5 symbol periods. . Further, the delay profile averaging unit of the delay profile measuring unit 22 requires a memory area of 25600 words in total in order to store 5 delay profiles for 5 symbol periods. Furthermore, all 5120 words must be searched in order to detect a peak from the 5120 word data. The path detector 42 is connected to the digital signal processor (D
SP), the path detection unit 42 must search all 5120 words in order to detect a peak, so the path detection unit 42 must process a huge amount of data at high speed. did not become.

Therefore, it is an object of the present invention to provide a code division multiple access base station which can solve the above problems. This object is achieved by a combination of features described in independent claims of the invention. The dependent claims define further advantageous specific examples of the present invention.

[0025]

A code division multiple access base station for a mobile communication system using a code division multiple access system according to a first aspect of the present invention is input to a base station to set up a call. Receiving a random access channel signal, detecting at least one peak from the random access channel signal, and detecting a time to receive the peak of the random access channel signal.
A delay profile measuring section, and a data channel demodulating section for despreading a data channel signal for which a call is set by the random access channel signal based on the peak reception time of the random access channel signal detected by the first delay profile measuring section. Is preferably provided.

The code division multiple access base station receives the data channel signal, detects at least one peak from the data channel signal, and receives the peak of the data channel signal based on the peak reception time of the random access channel signal. The data channel demodulation unit may further include a second delay profile measurement unit for detecting time, and the data channel demodulation unit may despread the data channel signal based on the peak reception time of the data channel signal detected by the second delay profile measurement unit. preferable.

Further, in the code division multiple access base station, the first delay profile measuring section detects the peak receiving time of the random access channel signal and outputs the detected peak receiving time to the second delay profile measuring section. 1
It is preferable to have a path detector. The second delay profile measuring section has a spreading code generating section for generating a spreading code for despreading the data channel signal based on the peak reception time of the random access channel signal,
The first path detector may supply the spread code generator with the peak reception time of the random access channel signal.

The second delay profile measuring section determines, based on the peak reception time of the random access channel signal,
A spreading code generation unit that generates a spreading code for despreading the data channel signal may be included. The spreading code generator may continuously generate a plurality of spreading codes, each corresponding to a plurality of symbol periods of the data channel signal, based on the peak reception time of the random access channel signal.

The second delay profile measuring unit uses a plurality of spreading codes generated by the spreading code generator to despread a data channel signal having a plurality of symbol periods, and a plurality of despread symbols. A delay profile averaging unit that stores a data channel signal of a period and adds the stored data channel signals of a plurality of symbol periods, and a second pass that detects a peak reception time of the data channel signal from the added data channel signal It is preferable to further include a detection unit.

The spreading code generator preferably initiates the spreading code generation when it receives the peak of the random access channel signal. The delay profile averaging unit may start storing the despread data channel signals of a plurality of symbol periods based on the peak reception time of the random access channel signal.

A method of processing a received signal for a mobile communication system using a code division multiple access system according to a first aspect of the present invention comprises the steps of receiving a random access channel signal to set up a call, Detecting at least one peak from the random access channel signal, detecting the time to receive the peak of the random access channel signal, and talking on the random access channel signal based on the peak reception time of the random access channel signal. And despreading the established data channel signal.

The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the claimed invention, and the features described in the embodiments Not all combinations are essential to the solution of the invention.

FIG. 5 shows the configuration of the CDMA base station of the present invention. The CDMA base station includes an antenna 50, a receiving unit 52,
It has a RACH signal receiving unit 54, a DCH signal receiving unit 56, and a control unit 66. The RACH signal receiving section 54 has a delay profile measuring section 58 and a demodulating section 60. DC
The H signal receiving unit 56 includes a delay profile measuring unit 62 and a demodulating unit 64.

The antenna 50 receives the spread spectrum modulated RACH signal and DCH signal. The RACH signal and DCH signal are two-dimensional complex signals of I phase and Q phase. The receiving unit 52 converts the frequency of the received signal from the carrier frequency band to the baseband frequency band,
It outputs to the RACH signal receiving unit 54 and the DCH signal receiving unit 56, respectively. The RACH signal receiving unit 54 uses the RAC
Receive multiple RACH signals from multiple users to despread and demodulate the H signal. The DCH signal receiving unit 56 receives a plurality of DCH signals sent from a plurality of users in order to despread and demodulate the DCH signal.

The delay profile measuring section 58 includes a receiving section 5
2 detects the peak of the RACH signal received from
The time when the peak of the H signal is received is detected. Next, the delay profile measurement unit 58 outputs the detected peak reception time of the RACH signal to the demodulation unit 60 via the control unit 66. Further, the delay profile measuring unit 58 outputs the detected peak reception time of the RACH signal to the delay profile measuring unit 62. Based on the peak reception time of the RACH signal detected by the delay profile measurement unit 58, the demodulation unit 60 inputs a plurality of RACH signals sent from a plurality of users from the reception unit 52 and despreads them. Next, the demodulation unit 20 outputs the despread and demodulated RACH signal.

The delay profile measuring section 62 includes a receiving section 5
The DCH signal is input from 2 and the delay profile measuring unit 5
Based on the peak reception time of the RACH signal input from 8, the peak reception time of the DCH signal is detected. Next, the delay profile measurement unit 62 outputs the detected peak reception time of the DCH signal to the demodulation unit 64 via the control unit 66. Based on the peak reception time of the DCH signal detected by the delay profile measurement unit 62, the demodulation unit 64
Despreads multiple DCH signals sent from multiple users.

The control unit 66 controls the delay profile measuring unit 5
RA sent by multiple users for 8 and 62
The type of spreading code used to despread the CH signal and the DCH signal and the timing of generating the spreading code are set. Further, the control unit 66 controls the delay profile measuring unit 5
The peak reception time of the RACH signal is input from 8 and output to the demodulation unit 60. Further, the control unit 66 inputs the peak reception time of the DCH signal from the delay profile measurement unit 62 and outputs it to the demodulation unit 64.

FIG. 6 shows the detailed configuration of the delay profile measuring section 58. The delay profile measuring unit 58 uses the RA
It has a CH signal matched filter 68 and a RACH signal delay profile measuring unit 74. Delay profile measuring unit 5
8 includes a plurality of RACH signal matched filters 68 for despreading RACH signals sent from a plurality of users.
Have. For simplicity of explanation, only one RACH signal matched filter is shown in FIG. The RACH signal matched filter 68 has a spread code generator 70 and a complex correlator 72. The complex correlator 72 may include a complex matched filter. The RACH signal delay profile measuring unit 74 includes a power level calculating unit 76 and a delay time adjusting unit 7.
8, delay profile averaging unit 80, and path detection unit 82
Have.

The RACH signal matched filter 68 has a RAC
The RACH signal is input from the receiving unit 52 to despread the H signal, despread, and the despread RACH signal is RA.
The signal is output to the CH signal delay profile measuring unit 74. RA
The CH signal delay profile measurement unit 74 detects the peak reception time of the RACH signal from the despread RACH signal and outputs it to the control unit 66 and the delay profile measurement unit 62.

The spread code generator 70 generates a spread code based on the peak reception time of the RACH signal input from the controller 66 and outputs it to the complex correlator 72. Complex phase converter 7
2 uses the spreading code generated by the spreading code generation unit 70 to despread the RACH signal input from the reception unit 52. Since the RACH signal is a complex signal having an I phase and a Q phase, the signal demodulated by the complex correlator 72 is also a complex signal having an I phase and a Q phase. The power level calculator 76 calculates the absolute value of the I-phase and Q-phase vectors of the demodulated RACH signal in order to obtain the power level of the demodulated RACH signal. Demodulated R having two-dimensional data of I phase and Q phase by power level calculation
The ACH signal is converted into a one-dimensional data signal. Two
The method of converting the signal of the dimensional data into the signal of the one-dimensional data is not limited to the above method, and another method may be used.

The delay time adjusting unit 78 adjusts the delay times of a plurality of delay profiles having different delay times to the same delay time. The delay profile averaging unit 80 has a memory that stores a plurality of delay profiles with adjusted delay times. Since the delay profile averaging unit 80 cumulatively adds the respective peaks of the delay profile as shown in FIG. 9 below, the peak of the RACH signal can be separated from noise and interference components. Path detection unit 82
Detects the peak reception time of the RACH signal by selecting at least one peak of the RACH signal equal to or more than the threshold value from the delay profile averaged by the delay profile averaging unit 80.

FIG. 7 shows a detailed configuration of the delay profile measuring section 62. The delay profile measuring unit 62 uses DC
It has an H signal matched filter 84 and a DCH signal delay profile measuring section 90. Here, the delay profile measuring unit 62 has one DCH signal matched filter 84. The DCH signal matched filter 84 includes the spread code generator 8
6 and complex correlator 88. The complex correlator 88 may include a complex matched filter. The DCH signal delay profile measuring section 90 has a power level calculating section 91, a delay profile averaging section 92, and a path detecting section 94.

The spread code generator 86 receives the peak reception time of the RACH signal from the delay profile measurer 58. The spreading code generation unit 86 uses the delay profile measurement unit 5
The spread code is generated based on the peak reception time of the RACH signal supplied from the signal generator 8. That is, the spread code generator 8
6 generates a spreading code when receiving the peak of the RACH signal. Therefore, the delay profile measuring unit 62
Is the DCH based on the peak reception time of the RACH signal.
Detect the peak reception time of the signal. Here, the delay profile measuring unit 58 is directly electrically connected to the delay profile measuring unit 62. The peak reception time of the RACH signal is determined by the delay profile measuring unit 5 via the control unit 66.
8 may be supplied to the delay profile measuring unit 62.

The complex phase shifter 88 despreads the DCH signal input from the receiving section 52 using the spreading code generated by the spreading code generating section 86. Since the DCH signal is a complex signal having I phase and Q phase, the signal demodulated by the complex correlator 88 is also a complex signal having I phase and Q phase. The power level calculation unit 91 uses the demodulated DCH
To obtain the power level of the signal, the absolute values of the I-phase and Q-phase vectors of the demodulated DCH signal are calculated. By the power level calculation, the demodulated DCH signal having two-dimensional data of I phase and Q phase is converted into one-dimensional data. The method of converting a signal of two-dimensional data into a signal of one-dimensional data is not limited to the above method, and another method may be used.

The delay profile averaging unit 92 has a memory for storing the delay profile of the DCH signal. The delay profile averaging unit 92 cumulatively adds the respective peaks of the delay profile, as shown in FIG. 10 below. The path detection unit 94 selects at least one peak equal to or more than the threshold value from the delay profile averaged by the delay profile averaging unit 92, and thereby the DCH
Detect the peak reception time of the signal.

FIG. 8 shows the RACH signal matched filter 68.
The example of the delay profile output from a, 68b, 68c, 68d, and 68e is shown. A delay profile of 10 symbol periods is shown in FIG. Here, the delay profile measuring unit 58 has five RACH signal matched filters 68a, 68b, 68c, 68d, and 68e in parallel. A signal wave transmitted via two paths, one direct wave and one delayed wave, is shown in FIG.

First, the direct wave of the RACH signal is input to the antenna 50. Direct wave is code 1 to code 1
Spread spectrum modulation is performed by a spread code of 0.
That is, each of the spread codes of code 1 to code 10 is multiplied with each of the RACH signals of a plurality of signal periods. For example, the RACH signal of the first symbol period is multiplied with code 1, and the RACH signal of the second symbol period is multiplied with code 2. Thus, the RACH for each symbol period
The signal is spread spectrum modulated with a different spreading code. Each code has a length of time of one symbol period. Next, the delayed wave is input to the antenna 50 with some delay time as compared with the direct wave. Similarly to the direct wave, the delayed wave is also spread spectrum modulated by the spread code of code 1 to code 10.

Next, the direct wave and the delayed wave are RACH signal matched filters 68a, 68b, 68c, 68d, and 6 respectively.
Despread by each of the 8e. Codes 1 and 6
Are supplied to the RACH signal matched filter 68a. Codes 2 and 7 are provided to the RACH signal matched filter 68b. Codes 3 and 8 are provided to the RACH signal matched filter 68c. Codes 4 and 9 are provided to the RACH signal matched filter 68d. Code 5 and 10
Are supplied to the RACH signal matched filter 68e. Next, the RACH signal matched filter 68a uses the code 1 and the code 6 to despread each of the direct wave and the delayed wave. Therefore, the set of the direct wave and the delayed wave despread by the code 1 appears in the first symbol period.
Next, the set of the direct wave and the delayed wave despread by the code 6 appears in the sixth symbol period. Since there is a time interval of 5 symbol periods between Code 1 and Code 6, the set of direct and delayed waves despread by Code 1 and Code 6 has a time interval of 5 symbol periods.

Similarly, the set of the direct wave and the delayed wave despread by the codes 2 and 7 appears in the second symbol period and the seventh symbol period. The set of the direct wave and the delayed wave despread by the codes 3 and 8 appears in the third symbol period and the eighth symbol period. A set of direct and delayed waves despread by codes 4 and 9 appear in the 4th and 9th symbol periods. Finally, the set of direct and delayed waves despread by Codes 5 and 10 appear in the 5th and 10th symbol periods.

FIG. 9 shows the procedure by which the delay profiles shown in FIG. 8 are averaged. FIG. 9A shows the output of the power level calculator 76. RACH signal matching filter 68
The power levels of outputs a, 68b, 68c, 68d, and 68e are calculated by the power level calculator 76. The RACH signal has a value of -1 or 1, and the power level calculation unit 76 calculates the absolute value by calculating the square of the RACH signal, so that the values of all RACH signals are 1. . Therefore, the output of the power level calculation unit 76 becomes a power indicating whether the spread code generated by the spread code generation unit 70 matches the spread code of the transmission signal. When the spreading code generated by the spreading code generation unit 70 matches the spreading code of the transmission signal, a power peak appears in the delay profile.

FIG. 9B shows the output of the delay time adjusting section 78. R despread by code 1 and code 6
The delay profile of the ACH signal is delayed by 4 symbol periods. R despread by code 2 and code 7
The delay profile of the ACH signal is delayed by 3 symbol periods. R despread by code 3 and code 8
The delay profile of the ACH signal is delayed by 2 symbol periods. R despread by code 4 and code 9
The delay profile of the ACH signal is delayed by one symbol period. Thus, all delay profiles are
It is located in the symbol cycle.

9C and 9D show the output of the delay profile averaging unit 80. The five delay profiles shown in FIG. 9B are cumulatively added in the same sample period of the same symbol period, and each have two peaks of a direct wave and a delayed wave as shown in FIG. 9C.
A set of delay profiles is obtained. Then, each peak set is cumulatively added in the same sample period of each symbol period. Therefore, as shown in FIG. 9D, it has two peaks of a direct wave and a delayed wave.
A set of delay profiles is obtained. Next, the delay profile measuring unit 58 advances the delay profile by four symbol periods and positions the delay profile at the first symbol period. Finally, the peak reception time of the RACH signal is detected using the added delay profile shown in FIG.

FIG. 10 shows an example of the delay profile of the RACH signal and the delay profile of the DCH signal obtained using the peak reception time of the RACH signal. Where 5
The delay profile for the symbol period is shown in FIG. Similar to FIG. 8, 5 delay profiles are 5
RACH signal matched filters 68a, 68b, 68
It is output from c, 68d, and 68e. The first delay profile of the RACH signal is input to the RACH signal matched filter 68a with the delay time shown in FIG. Here, the DCH signal matched filter 84 is
Based on the peak reception time of the H signal, the spreading code generation timing is moved by the delay time of the output of the RACH signal matched filter 68a. Therefore, the DCH signal matched filter 84 starts despreading the DCH signal at the new measurement start time.

The spreading codes of code 1 to code 5 are DC
It is continuously generated by the H signal matched filter 84.
Here, the codes 1 to 5 of the DCH signal are RAC
It is different from Code 1 to Code 5 used for the H signal.
The DCH signal matched filter 84 includes code 1 to code 5
Since the DCH signal is despread by using
Two peaks appear in one symbol period.
Next, the power level of each delay profile is
It is calculated by the power level calculator 91. Next, the delay profile averaging unit 92 cumulatively adds peaks in the same sample period of each symbol period. Therefore, the peaks of the direct waves are cumulatively added to each other, and the peaks of the delayed waves are cumulatively added to each other separately from the peaks of the direct waves. Therefore, a delay profile having two peaks of the direct wave and the delayed wave, which is shown on the right side of the arrow in FIG. 10, is obtained.

In the case of the delay profile measuring section 58, RA
The arrival time of the CH signal is unknown. For example, FIG. 8 shows an example in which the direct wave despread by Code 1 is first input to the base station. However, it is usually unknown which signal enters the base station first. Therefore, the delay profile measuring unit 58 has five RACH signal matched filters 68, and thus it is necessary to wait for a RACH signal having the same spreading code as that of the delay profile measuring unit 58 for five symbol periods.

Unlike the above delay profile measuring section 58, the delay profile measuring section 62 uses the peak reception time of the RACH signal, so that the delay profile measuring section 62 can know which DCH signal arrives. . Therefore, the delay profile measuring unit 62 spreads D with the spreading code that matches the spreading code of the matched filter.
It is not necessary to have multiple matched filters to wait for the CH signal. Furthermore, since the delay profile averaging unit 92 needs to store only the data output from one DCH signal matched filter 84, the amount of data to be stored can be reduced. As a result, the delay profile averaging unit 92
The size of the memory inside can be reduced.

Further, D is set in the delay profile measuring section 62.
Since there is only one CH signal matched filter 84, the delay time adjustment unit is unnecessary in the DCH signal delay profile measurement unit 90. The DCH signal matched filter 84 searches, for example, the peak reception time of the DCH signal in a time domain within a half symbol period centered on the peak reception time of the RACH signal.

Assuming that the memory capacity required for the delay profile averaging section 92 is 1024 words, the memory capacity required for the conventional delay profile averaging section 40 is 5120.
Is a word. Therefore, the delay profile averaging unit 9
The memory capacity required for 2 can be greatly reduced. Further, since the delay profile measuring unit 62 does not need the delay time adjusting unit, the configuration of the delay profile measuring unit 62 can be simplified. Further, since the path detection unit 94 has only to detect the peak of the DCH signal from the data of 1024 words, the amount of data processed for peak detection can be greatly reduced.

Although the present invention has been described using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is apparent to those skilled in the art that various modifications and improvements can be added to the above-mentioned embodiment. It is apparent from the description of the scope of claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

[0061]

As is apparent from the above description, according to the present invention, a signal having a long delay time can be processed by a code division multiple access base station having a small circuit configuration.

[Brief description of drawings]

FIG. 1 shows a configuration of a CDMA base station.

FIG. 2 shows how RACH and DCH signals are communicated between a base station and a mobile station.

FIG. 3 shows a detailed configuration of a delay profile measuring section 18.

FIG. 4 shows an example of a delay profile of RACH signals output from a plurality of RACH signal matched filters 28.

FIG. 5 shows a configuration of a CDMA base station of the present invention.

FIG. 6 shows a detailed configuration of a delay profile measuring section 58.

FIG. 7 shows a detailed configuration of a delay profile measuring section 62.

FIG. 8 shows RACH signal matched filters 68a, 68b, 6
The example of the delay profile output from 8c, 68d, and 68e is shown.

9 shows a procedure by which the delay profiles shown in FIG. 8 are averaged.

FIG. 10 shows a RACH signal delay profile and RAC.
An example of the delay profile of the DCH signal obtained using the peak reception time of the H signal is shown.

[Explanation of symbols]

10, 50 ... Antenna 12, 52 ... Receiver 14, 54 ... RACH signal receiving unit 16, 56 ... DCH signal receiving unit 18, 22, 58, 62 ... Delay profile measuring unit 20, 24, 60, 64 ... Demodulation unit 26, 66 ... Control unit 28 ... Control unit 28, 68 ... RACH signal matching filter 30, 70, 86 ... Spread code generator 32, 72, 88 ... Complex correlator 34, 74 ... RACH signal delay profile measuring unit 36, 76, 91 ... Power level calculator 38, 78 ... Delay time adjustment unit 40, 80, 92 ... Delay profile averaging unit 42, 82, 94 ... Path detection unit 84 ... DCH signal matching filter 90 ... DCH signal delay profile measuring unit

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-9-55693 (JP, A) JP-A-10-178386 (JP, A) JP-A-10-303855 (JP, A) International Publication 96/037079 (WO, A1) Takano Yano 2 persons, “High-speed synchronization acquisition method in CDMA packet mobile communication”, 1996 IEICE Society Conference, Proceedings 1, August 30, 1996, p. 324, B-323 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04J 13/00-13/06 H04B 1/69-1/713 H04B 7/26

Claims (3)

(57) [Claims] 1. Mobile communication using a code division multiple access system.
Is a code division multiple access base station for
The random access that is input to the base station to set up the call.
Receiving the access channel signal, the random access channel
The spread code with the length of multiple symbols is used for the channel signal.
By despreading using the random access channel
Detect at least one peak from the channel signal,
Receiving the peak of the random access channel signal
First delay profile measurement for detecting peak reception time
The call by the fixed part and the random access channel signal
Receive the data channel signal set by the
Detect at least one peak in a multichannel signal
And the peak of the random access channel signal
Based on the reception time, the peak of the data channel signal
Second delay processor for detecting the peak reception time of receiving a peak
The file measurement unit and the first delay profile measurement unit
Therefore, the random access channel signal detected
The second delay profile based on the peak reception time of
Data channel signal detected by the measuring unit.
Based on the peak reception time of the
Equipped with a data channel demodulator that despreads the channel signal
For example, the first delay profile measurement unit, the peak reception of the random access channel signal
Time is detected and the detected peak reception time is delayed by the second delay.
Has a first pass detector that outputs to the extended profile measurer
Then, the second delay profile measuring unit receives the peak of the random access channel signal.
Despread the data channel signal based on time
Spreading code generating unit for generating a spreading code for use, and a plurality of spreading codes generated by the spreading code generating unit
Using the data channel of the plurality of symbol periods.
A matched filter for despreading the digital signal and the data channel for the despreaded plurality of symbol periods.
Channel signal and stores the plurality of stored symbol cycles.
Delay to add each of the data channel signals
From the profile averaging unit and the added data channel signal, the data channel
Second path for detecting the peak reception time of the channel signal
A detection unit, wherein the first path detection unit is configured to execute the run code to the spread code generation unit.
Use the peak reception time of the dam access channel signal.
And the spreading code generator is configured to transmit the random access channel.
Based on the peak reception time of the
Each of multiple symbol periods of the data channel signal
It is possible to continuously generate the plurality of spread codes corresponding to this.
And a code division multiple access base station. 2. The first delay profile measuring unit includes a plurality of matched filters for despreading the random access channel signal, and a plurality of delay profiles output from the plurality of matched filters and having different delay times. The code division multiple access base station according to claim 1 , further comprising: a delay profile averaging unit that adjusts the delay time to the same delay time and then performs cumulative addition. 3. The one matched filter searches for the peak reception time of the data channel signal within a time domain within a half symbol period centered on the peak reception time of the random access channel signal. The code division multiple access base station according to claim 1 .