Abstract:
A base station for a mobile telephone system adopting a code division multiple access method comprising: a first delay profile measuring unit for receiving a random access channel signal, which is input to the base station for setting up a call, detecting at least one peak of the random access channel signal, and detecting the time of receiving the peak of the random access channel signal; and a data channel demodulator which despreads a data channel signal of the call set up by the random access channel signal, based on the peak receiving time of the random access channel signal detected by the first delay profile measuring unit.

Description:
This patent application claims priority based on a Japanese patent application, H11-046729 filed on Feb. 24, 1999, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a code division multiple access base station and in particular to a code division multiple access base station and which can process a signal wave having a long delay time. 
     2. Description of the Related Art 
     To deal with the variation of the delay time of a received signal, the conventional code division multiple access (CDMA) base station measures the delay profile of a transmission path from a received signal. The delay profile is the response of a signal wave transmitted through different transmission paths received at a base station. Because the signal wave transmits through different paths, the waveform of the signal wave is transformed by the influence of each transmission path. The conventional CDMA base station then selects a plurality of peaks having an effective power level and synthesizes the selected peak to demodulate the received signal. 
     FIG. 1 shows a configuration of a CDMA base station. A CDMA base station has an antenna  10 , a receiving unit  12 , a RACH signal receiver  14 , a DCH signal receiver  16 , and a controller  26 . The RACH signal receiver  14  has a delay profile measuring unit  18  and a demodulator  20 . The DCH signal receiver  16  has a delay profile measuring unit  22  and a demodulator  24 . 
     The antenna  10  receives a random access channel (PACH) signal and a data channel (DCH) signal which are spread spectrum modulated. 
     FIG. 2 shows how the RACH signal and the DCH signal are transmitted between the base station and the mobile station. First, the RACH signal is input to the base station from the mobile station to setup a c all. The RACH signal includes information such as the telephone number and a registration number of the user of the mobile station. Here, as an example, the RACH message of the RACH signal is 10 msec long. The RACH signal is transmitted by burst transmission where the communication is started and finished abruptly. 
     The ACH signal is then output from the base station to the mobile station. The ACH signal includes the information that the base station has acknowledged the mobile station. Then, the mobile station can start a call and sends the DCH signal to the base station. The DCH signal is a call signal set by the RACH signal. The DCH signal begins at an approximate predetermined time after the transmission of the ACH signal and finishes at a predetermined time after the commencement of the DCH signal transmission. Here, as an example, each DCH message of the DCH signal has a 10 msec time length. 
     The RACH signal and the DCH signal are complex signals having two-dimensions, namely an I-phase and a Q-phase. The receiving unit  12  converts the frequency of the RACH signal and DCH signal down to a baseband frequency from a carrier wave frequency band, and outputs to the RACH signal receiver  14  and the DCH signal receiver  16 , respectively. The RACH signal receiver  14  receives the RACH signal from the receiving unit  12  to despread the RACH signal. 
     The DCH signal receiver  16  receives the DCH signal from the receiving unit  12  to despread the DCH signal. The delay profile measuring unit  18  detects a peak of the RACH signal from the receiving unit  12  and detects the time of receiving the peak of the RACH signal. The delay profile measuring unit  18  then outputs the detected peak receiving time of the RACH signal to the demodulator  20  through the controller  26 . The demodulator  20  despreads the RACH signal received from the receiving unit  12  based on the peak receiving time of the RACH signal detected by the delay profile measuring unit  18 . The demodulator  20  then outputs the despread and demodulated RACH signal. 
     The delay profile measuring unit  22  receives the DCH signal from the receiving unit  12  and detects a peak of the DCH signal and detects the time of receiving the peak of the DCH signal. The delay profile measuring unit  22  then outputs the detected peak receiving time of the DCH signal to the demodulator  20 , through the controller  26 . The demodulator  24  despreads the DCH signal received from the receiving unit  12  based on the peak receiving time of the DCH signal detected by the delay profile measuring unit  22 . The demodulator  24  then outputs the despread and demodulated DCH signal. 
     The controller  26  sets a type of spreading code and timing of generation of the spreading code for despreading the RACH signal and the DCH signal for the delay profile measuring units  18  and  22 . The controller  26  also inputs the peak receiving time of the RACH signal from the delay profile measuring unit  18  and outputs this to the demodulator  20 . Furthermore, the controller  26  inputs the peak receiving time of the DCH signal and outputs this to the demodulator  24 . 
     The delay profile measuring units  18  and  22  measures a delay profile with a long delay time, so that the base station can receive various delay signals sent from various places inside the cell region of the base station. During the transmission of the signals, the signals transmit on a different path so that each of the delay profiles has a different delay time. At the same time as measuring the delay profile, the controller  26  notifies the demodulators  20  and  24  of the peak receiving time of the RACH and the DCH signal, so that the demodulators  20  and  24  can despread each RACH signal and DCH signal having various delay times. 
     FIG. 3 shows a detailed configuration of a delay profile measuring unit  18 . The delay profile measuring unit  18  can measure a delay profile having a long delay time. The delay profile measuring unit  18  has 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  to despread the RACH signals sent from the plurality of users. Only one RACH signal matched filters  28  is shown in FIG. 3 for simplicity. The RACH signal matched filter  28  has a spreading code generator  30  and a complex correlator  32 . The complex correlator  32  may include complex matched filter. The RACH signal delay profile measuring unit  34  has a power level calculator  36 , a delay time adjuster  38 , a delay profile averaging unit  40 , and a path detector  42 . 
     The RACH signal matched filter  28  inputs a RACH signal from the receiving unit  12  and despereads the input RACH signal. The RACH signal delay profile measuring unit  34  detects the peak receiving time of the RACH signal from the despread RACH signal, and outputs the peak receiving time of the RACH signal to the controller  26 . 
     The spreading code generator  30  generates a spreading code and outputs this to the complex correlator  32 . The complex correlator  32  despreads the RACH signal using spreading code generated by the spreading code generator  30 . Because the RACH signal is a complex signal having an I-phase and a Q-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 a vector in the I-phase and the Q-phase of the demodulated RACH signal, to obtain a power level of the demodulated RACH signal. As a result of the power level calculation, the demodulated RACH signal having an I-phase and a Q-phase two-dimensional data changes to one-dimensional data. 
     The delay time adjuster  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 to store the plurality of delay profiles, the delay times of which have been adjusted. The delay profile averaging unit  40  sums each of the peaks of the delay profiles as shown below in FIG. 4, so that the peak can be separated from the noise or interference components. 
     In this case, it is assumed that the RACH signal is spread spectrum modulated by the 256 chips of the spreading code. To enable the summing of a maximum of 5-symbol periods of the delay time, the delay profile averaging unit  40  has a memory region for 5120 words. Here, 1 chip is equal to 4 words. The 5120 words are obtained by multiplying the 256 chips by the 5 symbols and further multiplying by 4, which is an over sampling number. The path detector  42  detects the peak receiving timing of the RACH signal by detecting the peaks of the RACH signal above the threshold value. 
     The delay profile measuring unit  22  has the same configuration as the delay profile measuring unit  18 . The difference between the delay profile measuring unit  18  and the delay profile measuring unit  22  is the spreading code used for despreading. The spreading code used for the delay profile measuring unit  18  is used for despreading the RACH signal, and the spreading code used for the delay profile measuring unit  22  is used for despreading the DCH signal. As in the delay profile measuring unit  18 , the delay profile measuring unit  22  can also measure a delay profile having a long delay time such as  5  symbol periods. 
     FIG. 4 shows an example of a delay profile of a RACH signal output from a plurality of RACH signal matched filters  28 . The delay profiles are shown relative to time. Here, the delay profile measuring unit  18  has five RACH signal matched filters  28   a ,  28   b ,  28   c ,  28   d , and  28   e  in parallel, for measuring the delay profile of 5 symbol periods. One symbol period has 1024 samples. The delay profiles shown in FIG. 4 are sent from one mobile station. Because the signal wave sent from a mobile station transmits via various,paths, the base station receives delay profiles having various delay times. In FIG. 4, the output of each of the RACH signal matched filters  28   a ,  28   b ,  28   c ,  28   d , and  28   d  has three peaks, one direct wave and two delayed waves. These three peaks show that the RACH signal is transmitted through three paths. The direct wave is transmitted directly from the mobile station to the base station, and the other two delay waves are transmitted by reflection. 
     The spreading code of the long code of the first symbol is allotted to the RACH signal matched filter  28   a . The spreading code of the long code of the second symbol is allotted to the RACH signal matched filter  28   b , and so on. The spreading code is comprised of a long code and a short code. The long code is used for distinguishing the specific mobile station from a plurality of mobile stations. The long code has a long period due to a plurality of symbol periods. Thus, even in the same long code, the code is different by changing the timing of generation of the code. Therefore, the long code allotted to the RACH signal matched filter  28   a  is different to the long code allotted to the RACH signal matched filter  28   b.    
     By allotting the first symbol of the long code to the RACH signal matched filter  28   a  for despreading, the first peaks emerge in the first symbol period. By allotting the second symbol of the long code to the RACH signal matched filter  28   b  for despreading, the second peaks emerge in the second symbol period, and so on. Therefore, the delay profile measuring unit  18  can measure the peaks of the RACH signal emerging during the 5 symbol periods. 
     The delay time adjuster  38  then delays the first peak for four symbol periods, delays the second peak for three symbol periods, delays the third peak for two symbol periods, and delays the forth peak for one symbol period. Therefore, all the peaks of the delay profiles have the same delay time for the four symbol periods. Then, each of the peaks of the five delay profiles is summed by the delay profile averaging unit  40 . The peak of the direct waves of each of the delay profiles are summed. The peaks of the first delayed waves of each of the delay profiles are summed separately to the direct waves and the second delay waves. The peaks of the second delayed waves of each of the delay profiles are summed separately to the direct waves and the first delay waves. The delay profile shown below the arrow in FIG. 4 is a result of the summing of the five delay profiles. 
     The conventional delay profile measuring unit  22  has five signal matched filters in parallel, to measure the delay profile for five symbol periods as in the delay profile measuring unit  18 . Furthermore, the delay profile averaging unit of the delay profile measuring unit  22  must have a memory region of a total of 25600 words, to store the five delay profiles for five symbol periods. Furthermore, to detect the peaks from the 5120 words, all 5120 words must be retrieved. If the path detector  42  is comprised of a digital signal processor, the path detector  42  has to process an enormous volume of data at high speed because the path detector  42  has to retrieve all 5120 words in order to detect the peaks. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the present invention to provide a code division multiplex receiver which overcomes the above issues in the related art. This object is achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention. 
     According to the first aspect of the present invention, a base station for a mobile telephone system adopting a code division multiple access method can be provided. The base station may comprise a first delay profile measuring unit for receiving a random access channel signal, which is input to the base station for setting up a call, detecting at least one peak of the random access channel signal, and detecting a time of receiving the peak of the random access channel signal; and a data channel demodulator which despreads a data channel signal of the call set up by the random access channel signal based on the peak receiving time of the random access channel signal detected by the first delay profile measuring unit. 
     The base station can be provided such that the base station further comprises a second delay profile measuring unit which receives the data channel signal, detects at least one peak of the data channel signal, and detects a receiving time of the peak of the data channel signal based on the peak receiving time of the random access channel signal; and the data channel demodulator despreads the data channel signal based on the peak receiving time of the data channel signal detected by the second delay profile measuring unit. 
     The first delay profile measuring unit may have a first path detector which detects the peak receiving time of the random access channel signal and may output the detected peak receiving time to the second delay profile measuring unit. The second delay profile measuring unit may have a spreading code generator which generates a spreading code for despreading the data channel signal based on the peak receiving time of the random access channel signal; and the first path detector may provide to the spreading code generator the peak receiving time of the random access channel signal. 
     The base station may further comprises a controller which inputs the peak receiving time of the random access channel signal from the first delay profile measuring unit and outputs to the second delay profile measuring unit. The second delay profile measuring unit may have a spreading code generator which generates a spreading code for despreading the data channel signal based on the peak receiving time of the random access channel signal. 
     The base station can be provided such that the spreading code generator may sequentially generate a plurality of the spreading codes, each of which corresponds to the data channel signal of each of a plurality of symbol periods, based on the peak receiving time of the random access channel signal. The second delay profile measuring unit may further have: a complex correlator which despreads the data channel signal of the plurality of symbol periods using the plurality of spreading codes generated by the spreading code generator; a delay profile averaging unit which stores the despread data channel signal of the plurality of symbol periods and sums each of the stored data channel signals of the plurality of symbol periods; and a second path detector which detects the peak receiving time of the data channel signal from the summed data channel signal. 
     The spreading code generator may start generating the spreading code when receiving the peak of the random access channel signal. The delay profile averaging unit may start storing the despread data channel signal based on the peak receiving time of the random access channel signal. The first delay profile measuring unit may receive a plurality of the random access channel signals, detects at least one peak for each of the plurality of the random access channel signals, and detects the peak receiving time for each of the plurality of the random access channel signals. 
     According to the second aspect of the present invention, a method of processing a received signal for a mobile telephone system adopting a code division multiple access method can be provided. The method comprises steps of receiving a random access channel signal for setting up a call; detecting at least one peak of the random access channel signal; detecting a time of receiving the peak of the random access channel signal; and despreading a data channel signal of the call set by the random access channel signal based on the peak receiving time of the random access channel signal. 
     The method may further comprises steps of receiving the data channel signal; detecting at least one peak of the data channel signal; and detecting a receiving time of the peak of the data channel signal based on the peak receiving time of the random access channel signal; and despreading the data channel signal based on the peak receiving time of the data channel signal. The peak detecting step of the data channel signal may generate a spreading code for despreading the data channel signal based on the peak receiving time of the random access channel signal. 
     The method can be provided such that the peak detecting of the data channel signal may sequentially generate a plurality of spreading codes, each of which corresponds to the data channel signal of each of a plurality of symbol periods, based on the peak receiving time of the random access channel signal. The peak detecting of the data channel signal may: despread the data channel signal of the plurality of symbol periods using the plurality of spreading codes generated by the spreading code generating; store the despread data channel signals of the plurality of symbol periods; sum each of the stored data channel signals of the plurality of symbol periods; and detect the peak of the data channel signal from the summed data channel signal. 
     The spreading code generating step may start generating the spreading code when receiving the peak of the random access channel signal. The data channel signal storing step may start storing the despread data channel signal based on the peak receiving time of the random access channel signal. 
     This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a configuration of a CDMA base station. A CDMA 
     FIG. 2 shows how the RACH signal and the DCH signal are transmitted between the base station and the mobile station. 
     FIG. 3 shows a detailed configuration of a delay profile measuring unit  18 . 
     FIG. 4 shows an example of a delay profile of a RACH signal 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 unit  58 . 
     FIG. 7 shows a detailed configuration of a delay profile measuring unit  62 . 
     FIG. 8 shows an example of the delay profile output from the RACH signal matched filters  68   a ,  68   b ,  68   c ,  68   d , and  68   e.    
     FIG. 9 shows the procedure of averaging the delay profiles shown in FIG.  8 . 
     FIG. 10 shows an example of the delay profiles of the RACH signal and the delay profile of the DCH signal obtained by using the peak receiving time of the RACH signal. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention will now be described based on the preferred embodiments, which do not intend to limit the scope of the present invention, but exemplify the invention. All of the features and the combinations thereof described in the embodiment are not necessarily essential to the invention. 
     FIG. 5 shows a configuration of a CDMA base station of the present invention. The CDMA base station has an antenna  50 , a receiving unit  52 , a RACH signal receiver  54 , a DCH signal receiver  56 , and a controller  66 . The RACH signal receiver  54  has a delay profile measuring unit  58  and a demodulator  60 . The DCH signal receiver  56  has a delay profile measuring unit  62  and a demodulator  64 . 
     The antenna  50  receives a RACH signal and a DCH signal which are spread spectrum modulated. The signal is a complex signal having the two-dimensions of an I-phase and a Q-phase. The receiving unit  52  converts the frequency of a received signal down to a baseband frequency from a carrier wave frequency band, and outputs to the RACH signal receiver  54  and the DCH signal receiver  56 . The RACH signal receiver  54  receives a plurality of RACH signals sent from the plurality of users in order to despread and demodulate the RACH signals. The DCH signal receiver  56  also receives a plurality of DCH signals sent from the plurality of users in order to despread and demodulate the DCH signals. 
     The delay profile measuring unit  58  receives a RACH signal from the receiving unit  52  and detects the peak of the RACH signal and further detects the receiving time of the peak of the RACH signal. The delay profile measuring unit  58  then outputs the peak receiving time of the RACH signal to the demodulator  60  through the controller  66 . The delay profile measuring unit  58  also outputs the peak receiving time of the RACH signal to the delay profile measuring unit  62 . The demodulator  60  inputs a plurality of RACH signals sent from the plurality of users from the receiving unit  52 , and despreads the RACH signal based on the peak receiving time of the RACH signal detected by the delay profile measuring unit  58 . 
     The delay profile measuring unit  62  inputs the DCH signal and detects the peak of the DCH signal and further detects the receiving time of the peak of the DCH signal based on the peak receiving time of the RACH signal input from the delay profile measuring unit  58 . The delay profile measuring unit  62  then outputs the peak receiving time of the DCH signal to the demodulator  64  through the controller  66 . The demodulator  64  despreads a plurality of DCH signals sent from the plurality of users, based on the peak receiving time of the DCH signal detected by the delay profile measuring unit  62 . 
     The controller  66  sets the type of spreading code and timing of generation of the spreading code for the delay profile measuring unit  58  and  62 , used for despreading the RACH signal and the DCH signal sent from the plurality of users. The controller  66  also inputs the peak receiving time of the RACH signal from the delay profile measuring unit  58  and outputs to the demodulator  60 . The controller  66  inputs the peak receiving time of the DCH signal and outputs to the demodulator  64 . 
     FIG. 6 shows a detailed configuration of a delay profile measuring unit  58 . The delay profile measuring unit  58  has a RACH signal matched filter  68  and a RACH signal delay profile measuring unit  74 . The delay profile measuring unit  58  has a plurality of RACH signal matched filters  68  to despread the RACH signals sent from the plurality of users. Only one RACH signal matched filters  68  is shown in FIG. 6 for simplicity. The RACH signal matched filter  68  has a spreading code generator  70  and a complex correlator  72 . The complex correlator  72  may include complex matched filter. The RACH signal delay profile measuring unit  74  has a power level calculator  76 , a delay time adjuster  78 , a delay profile averaging unit  80 , and a path detector  82 . 
     The RACH signal matched filter  68  inputs a RACH signal to despread the RACH signal and outputs the despread RACH signal to the RACH signal delay profile measuring unit  74 . The RACH signal delay profile measuring unit  74  detects the peak receiving time of the RACH signal from the despread RACH signal and outputs to the controller  66  and the delay profile measuring unit  62 . 
     The spreading code generator  70  generates a spreading code based on the peak receiving time of the RACH signal input from the delay profile measuring unit  58  and outputs this to the complex correlator  72 . The complex correlator  72  despreads the RACH signal received from the receiving unit  52  using the spreading code generated by the spreading code generator  70 . Because 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 a vector in the I-phase and Q-phase of the demodulated RACH signal, to obtain the power level of the demodulated RACH signal. As a result of the power level calculation, the demodulated RACH signal having I-phase and Q-phase two-dimensional data changes to one-dimensional data. Instead of the method shown above, other methods can be used for conversion of two-dimensional data signals to one-dimensional data signals. 
     The delay time adjuster  78  adjusts the delay time of a plurality of delay profiles having different delay times, to the same delay time. The delay profile averaging unit  80  has a memory to store a plurality of delay profiles, the delay times of which have been adjusted. The delay profile averaging unit  80  sums up each of the peaks of the delay profiles as shown below in FIG. 9, so that peaks of the RACH signal can be separated from the noise or interference components. The path detector  82  detects the peak receiving time of the RACH signal by selecting at least one peak above the threshold value from the delay profile averaged by the delay profile averaging unit  80 . 
     FIG. 7 shows a detailed configuration of a delay profile measuring unit  62 . The delay profile measuring unit  62  has a DCH signal matched filter  84  and a DCH signal delay profile measuring unit  90 . Here, the delay profile measuring unit  62  has one DCH signal matched filter  84 . The DCH signal matched filter  84  has a spreading code generator  86  and a complex correlator  88 . The complex correlator  88  may include complex matched filter. The DCH signal delay profile measuring unit  90  has a power level calculator  91 , a delay profile averaging unit  92 , and a path detector  94 . 
     The spreading code generator  86  inputs the peak receiving time of the RACH signal from the delay profile measuring unit  58 . The spreading code generator  86  generates the spreading code based on the peak receiving time of the RACH signal provided from the delay profile measuring unit  58 . In other words, the spreading code generator  86  generates the spreading code when receiving the peak of the RACH signal. Therefore, the delay profile measuring unit  62  detects the peak receiving time of the DCH signal based on the peak receiving time of the RACH signal. Here, the delay profile measuring unit  58  has a direct electrical connection to the delay profile measuring unit  62 . However, the peak receiving time of the RACH signal can also be provided to the delay profile measuring unit  62  from the delay profile measuring unit  58  through the controller  66 . 
     The complex correlator  88  despreads the DCH signal received from the receiving unit  52 , using the spreading code generated by the spreading code generator  86 . Because the DCH signal is a complex signal having an I-phase and a Q-phase, the signal demodulated by the complex correlator  88  is also a complex signal having an I-phase and a Q-phase. The power level calculator  91  calculates the absolute value of a vector in the I-phase and Q-phase of the demodulated DCH signal, to obtain the power level of the demodulated DCH signal. As a result of the power level calculation, the demodulated DCH signal having I-phase and Q-phase two-dimensional data changes to one-dimensional data. Instead of the method shown above, other methods can be used for conversion of two-dimensional data signals to one-dimensional data signals. 
     The delay profile averaging unit  92  has a memory to store the delay profile of the DCH signal. The delay profile averaging unit  92  sums up each of the peaks of the delay profiles as shown below in FIG.  10 . The path detector  94  detects the peak receiving time of the DCH signal by selecting at least one peak above the threshold value from the delay profile averaged by the delay profile averaging unit  92 . 
     FIG. 8 shows an example of the delay profile output from the RACH signal matched filters  68   a ,  68   b ,  68   c ,  68   d , and  68   e  in parallel. The delay profiles for ten symbol periods are shown in FIG.  8 . Here, the delay profile measuring unit  58  has five RACH signal matched filters  68   a ,  68   b ,  68   c ,  68   d , and  68   e . The signal wave transmitted through the two paths are shown in FIG. 8, that is, one direct wave and one delayed wave. First, the direct wave of the RACH signal is input to the antenna  50 . The direct wave is spread spectrum modulated by the spreading code of code  1  through to code  10 . Each of code  1  through to code  10  is multiplied with the RACH signal of each of the plurality of signal periods. 
     For example, the first symbol period of the RACH signal, signal  1 , is multiplied with code  1 , and the second symbol period of the RACH signal is multiplied with code  2 . Then, each of the symbol periods of the RACH signal is spread spectrum modulated by the different spreading codes. Each of the codes has a time length of one symbol period. Next, the delayed wave is input to antenna  50  with some delay time with the direct wave. The delayed wave is also spread spectrum modulated by the spreading code of code  1  through code  10 . 
     Next, the direct wave and the delayed wave are despread by each of the RACH signal matched filters  68   a ,  68   b ,  68   c ,  68   d , and  68   e . Codes  1  and  6  are provided to the RACH signal matched filter  68   a . Codes  2  and  7  are provided to the RACH signal matched filter  68   b . Codes  3  and  8  are provided to the RACH signal matched filter  68   c . Codes  4  and  9  are provided to the RACH signal matched filter  68   d . Codes  5  and  10  are provided to the RACH signal matched filter  68   e . Then, the RACH signal matched filter  68   a  despreads each of the direct wave and the delayed wave using code  1  and code  6 . Therefore, the pair of the direct wave and the delayed wave, which are despread by code  1  emerge at the first symbol period. Then, the pair of the direct wave and the delayed wave, which are despread by the code  6  emerge at the sixth symbol period. The pair of the direct wave and the delayed wave despread by codes  1  and  6  have a time interval of five symbol periods because there is a time interval of five symbol periods between the code  1  and the code  6 . 
     Similarly, the pair of the direct wave and the delayed wave, which are despread by the codes  2  and  7  emerge at the second symbol period and the seventh symbol period. The pair of the direct wave and the delayed wave, which are despread by the codes  3  and  8  emerge at the third symbol period and the eighth symbol period. The pair of the direct wave and the delayed wave, which are despread by the codes  4  and  9  emerge at the forth symbol period and the ninth symbol period. Finally, the pair of the direct wave and the delayed wave, which are despread by the codes  5  and  10  emerge at the fifth symbol period and the tenth symbol period. 
     FIG. 9 shows the procedure of averaging the delay profiles shown. in FIG.  8 . FIG.  9 (A) shows the output of the power level calculator  76 . The outputs of the RACH signal matched filters  68   a ,  68   b ,  68   c ,  68   d , and  68   e  are the calculated power levels calculated by the power level calculator  76 . Because the RACH signal has a value of −1 or 1, and because the power level calculator calculates the absolute value by calculating the square of the RACH signal, all the values of the RACH signals become 1. Therefore, the output of the power level calculator  76  becomes the power, which shows whether the spreading code generated by the spreading code generator  70  is matched with the spreading code of the transmitted signal. If the spreading code of the spreading code generator and the spreading code of the wave signal are matched, the peak of the power appears in the delay profile. 
     FIG.  9 (B) shows the output of the delay time adjuster  78 . The delay profile of the RACH signal despread by the codes  1  and  6  is delayed for four symbol periods. The delay profile of the RACH signal despread by the codes  2  and  7  is delayed for three symbol periods. The delay profile of the RACH signal despread by the codes  3  and  8  is delayed for two symbol periods. The delay profile of the RACH signal despread by the codes  4  and  9  is delayed for one symbol period. In this way, all the delay profiles are located in the fifth symbol period. 
     FIG.  9 (C) and FIG.  9 (D) shows the output of the delay profile averaging unit  80 . The five delay profiles shown in FIG.  9 (B) are summed at the same sample period in the same symbol period, then two pair of delay profiles having two peaks of the direct wave and the delay wave can be obtained as shown in FIG.  9 (C). Next, the pair of peaks is summed in such a way that each of the peaks is summed at the same sample period in each of the symbol periods. Therefore, as shown in FIG.  9 (D), one pair of peaks of the direct wave and the delay wave is obtained. Then, the delay profile measuring unit  58  advance the delay profile for four symbol periods so that the delay profile is located at the first symbol period. Finally, the peak receiving time of the RACH signal is detected using the summed delay profile shown in FIG.  9 (D). 
     FIG. 10 shows an example of the delay profiles of the RACH signal and the delay profile of the DCH signal obtained using the peak receiving time of the RACH signal. Here, the delay profiles for five symbol periods are shown in FIG.  10 . As for FIG. 8, five delay profiles are output from the five RACH signal matched filters  68   a ,  68   b ,  68   c ,  68   d , and  68   e . The first delay profile of the RACH signal is input to the RACH signal matched filter  68   a  with the delay time shown in FIG.  10 . The DCH signal matched filter  84  shifts the timing of generation of the spreading code based on the peak receiving time of the RACH signal, here shown as the delay time at the output of the RACH signal matched filter  68   a . Thus, the DCH signal matched filter  84  starts despreading the DCH signal at the new measurement commencement time. 
     The spreading codes of the codes  1  through to code  5  are sequentially generated by the DCH signal matched filter  84 . Here, the codes  1  through to code  5  of the DCH signal are different from the codes  1  through to code  5  used for the RACH signal. The DCH signal matched filter  84  despreads the DCH signal using the codes  1  through to code  5 , so that the five pairs of peaks emerge at each of the symbol periods. Then, the power level of each of the delay profiles is calculated in the power level calculator  91 . Next, the delay profile averaging unit  92  sums the peaks at the same sample period for each of the symbol periods. Therefore, the peaks of the direct waves are summed together, and the peaks of the delayed waves are summed together, separately from the peaks of the direct wave. Then, the delay profile shown on the right-hand side of the arrow in FIG. 10 can be obtained, having the two peaks of the direct wave and the delayed wave. 
     In the case of the delay profile measuring unit  58 , the arrival time of the RACH signal is unknown. For example, FIG. 8 shows an example where the direct wave modulated by the code  1  is input to the base station first. However, it is usually not known which signal is input to the base station first. Therefore, the delay profile measuring unit  58  has five RACH signal matched filters so that the delay profile measuring unit  58  can wait for five symbol periods for the RACH signal having the same spreading code as the spreading code of the RACH signal matched filter  58 . 
     Contrary to the above, because the delay profile measuring unit  62  uses the peak receiving time of the RACH signal, the delay profile measuring unit  62  can know which DCH signal will be arriving. Therefore, the delay profile measuring unit  62  does not have to have a plurality of matched filters to wait for the DCH signal modulated with the spreading code that matches with the spreading code of the matched filter. Furthermore, the delay profile averaging unit  92  has to store only the data output from one DCH signal matched filter  84 , so the quantity of data to be stored can be reduced. The result is, the size of the memory inside the delay profile averaging unit  92  can be reduced. 
     Furthermore, the delay time adjuster becomes unnecessary in the DCH signal delay profile measuring unit  90  because there is only one DCH signal matched filter  84  in the DCH signal delay profile measuring unit  90 . The DCH signal matched filter  84  searches the peak receiving time of the DCH signal from the time region of peak receiving time of the RACH signal as a center, to within half a symbol period, for example. 
     If the capacity of the memory necessary for the delay profile averaging unit  92  is 1024 words, the capacity of the memory necessary for the conventional delay profile averaging unit  40  is 5120 words. Therefore, the capacity of the memory necessary for the delay profile averaging unit  92  is greatly reduced. Also, since the delay profile measuring unit  62  does not need the delay time adjuster, the structure of the delay profile measuring unit  62  can be simplified. Furthermore, because the path detector  94  can detect the peak of the DCH signal from the 1024 words of data, the quantity of data to be processed for peak detection is greatly reduced. 
     Although the present invention has been described by way of exemplary embodiments, it should be understood that many changes and substitutions may be made by those skilled in the art without departing from the spirit and the scope of the present invention which is defined only by the appended claims.