JP2004165975A - Radio base station apparatus and search window correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio base station apparatus small in the circuit scale of a searcher and short in the period of time required for path searching. <P>SOLUTION: The radio base station equipment is provided with a transmitter-receiver 2 performing radio communication with a mobile terminal and a radio base station 1 connected with the transmitter-receiver 2 through an optical channel including an optical fiber 3, and the radio base station 1 is provided with a delay measuring part 5 for measuring a delay amount generated in the optical channel of information signals sent out from the mobile terminal. The delay measuring part 5 sends out a flag signal at a prescribed timing, measures the time until the sent-out flag signal is looped back in the transmitter-receiver 2 and returned, and calculates the delay amount from the measured time. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radio base station apparatus used in mobile communication, particularly to a CDMA (Code Division Multiple Access) type radio communication using an optical line, and to a search window correction method performed in such an apparatus.
[0002]
[Prior art]
A CDMA system based on a spread spectrum system is known as one of the wireless communication systems. Among the CDMA systems, a direct sequence (DS) system in which an information signal is directly multiplied by a high-speed code sequence is particularly excellent in noise resistance and interference resistance. This is effective in a wireless communication system using a terminal or the like as a mobile terminal.
[0003]
In wireless communication, a signal transmitted from a transmission side arrives at a reception side through various transmission paths (multipaths) due to reflection and diffraction at a building or the like. For this reason, in the case of the DS system, it is common to perform rake (RAKE) reception in which signals arriving via such a multipath are individually separated and combined (see Patent Document 1).
[0004]
When rake reception is performed, a path search is performed to obtain the reception timing and reception level of each of the multiple pallets. In this path search, a given spreading code (same as a spreading code (high-speed code sequence) used for spreading modulation at the time of transmission) is multiplied with a received signal by gradually shifting the timing at fixed time intervals. Then, a correlation value at each timing is obtained, thereby obtaining a delay profile. Usually, the detection of the delay profile is performed within a preset search window range, and the reception timing and reception level of each path are acquired from the detected delay profile.
[0005]
In the above delay profile, the timing of the peak with the highest correlation value is the reception timing on the path with the highest reception level. Normally, reception timings at a plurality of peaks are obtained from the highest correlation value, and rake combining is performed by separating the reception signals based on these reception timings.
[0006]
Recently, in a wireless communication system adopting the DS system, a wireless base station that performs rake reception as described above has a plurality of wireless relay devices (transceivers and transceivers) that perform wireless communication between the wireless base station and mobile terminals. ), And each of the wireless relay devices is connected to be able to communicate with a wireless base station via an optical fiber. According to this system, a plurality of communication areas can be set in one base station (see Patent Document 2).
[0007]
[Patent Document 1]
JP-A-2002-111548
[Patent Document 2]
JP 2001-309423 A
[0008]
[Problems to be solved by the invention]
However, in a wireless base station device in which a transceiver is connected to a wireless base station via an optical fiber, a method for accurately measuring a delay amount in an optical line via the optical fiber has not been provided. For this reason, there have been the following problems and development requirements as issues.
[0009]
The search window is set within a range in which a delay in a communication path until a signal transmitted from the transmission side (mobile terminal) is input to the path search unit on the reception side is considered. For example, when a transceiver is connected to a wireless base station via an optical fiber, the search window is a fixed delay (“delay in the wireless base station” + “delay in the transceiver”) and a search window in the optical line via the optical fiber. The range is set in consideration of the delay and the delay of the wireless path (including multipath) (delay corresponding to the radius (distance) of the communication area of the transceiver). Usually, the range of the search window is uniform and fixed. For this reason, for example, when multiple transceivers are connected to a wireless base station with optical fibers having different fiber lengths for the purpose of covering dead zones such as tunnels and basements, the delay in the optical fiber having the longest fiber length is reduced. It is necessary to set a search window that takes into account. In this case, the range of the search window becomes very large.
[0010]
When the range of the search window becomes large, there arises a problem that the circuit scale of the path search unit becomes large and the time required for the path search becomes long. Hereinafter, the reason will be specifically described.
[0011]
In the DS system, at the time of transmission, as shown in FIG. 12, for example, an information signal composed of bit data is multiplied (spread) by a spreading code (high-speed code string) composed of chip data. The spread-modulated signal is an exclusive OR of the information signal and the spreading code. At the time of reception, the spread modulated signal is multiplied (despread) by the same code as the spreading code shown in FIG. The signal after despreading is an exclusive OR of the spread-modulated signal and the spread code, whereby the original information signal is restored.
[0012]
The detection of the delay profile in the path search is performed by multiplying the spread signal by the received signal while gradually shifting the timing at a time interval of 1 / n chip over the range of the search window. For example, when the length of the optical fiber is 20 km and the radius (distance) of the communication area is 10 km, a search window is set in consideration of the delay in the transmission path of a total of 30 km, and a path search is performed over the range of the search window. Thus, a delay profile as shown in FIG. 13 is obtained. In this delay profile, the reception power (corresponding to the correlation value) is plotted on the vertical axis, and the delay time is plotted on the horizontal axis. About two thirds of the search window is a portion that takes into account the delay amount in the optical line. As the fiber length increases, the length of this portion increases, and accordingly, the range of the search window increases, and the time required for the path search increases.
[0013]
Further, the path search unit multiplies each of the spread codes delayed by each delay device with a delay unit for delaying the spread code at a time interval of 1 / n chip, and multiplies the received signal by a correlation value (received power). ), And the number of delay units and power calculation units is basically determined by the time resolution (time interval) and the range of the search window. When the range of the search window is widened, the number of delay units and power calculation units increases, and as a result, the circuit scale of the path search unit increases.
[0014]
The length of each optical fiber is measured when the wireless base station device is installed, and the measurement result is used to exclude a portion corresponding to the delay amount in the optical line from the search window range. Something is also possible. However, in this case, there is a problem in that the work for measuring the length of the optical fiber is required, and the number of man-hours for installing the wireless base station apparatus increases.
[0015]
Recently, it has been attempted to provide a location information service in a wireless communication system. One of the systems for providing such a location information service is an OTDOA (Observed Time Difference of Arrival) type positioning system that measures distances between three wireless base stations and a mobile terminal based on signal arrival times. There is. When the OTDOA method is applied to the above-described wireless communication system, it is necessary to accurately measure the amount of delay in an optical line via an optical fiber for each transceiver. However, such a measuring means has never existed, and its development has been desired.
[0016]
An object of the present invention is to provide a wireless base station apparatus and a search window correction method capable of accurately measuring the delay amount of an optical line (optical fiber), having a small searcher circuit scale, and requiring a short time for a path search. Is to provide.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, a radio base station apparatus of the present invention includes a transceiver in which an information signal transmitted from a mobile terminal is received via a plurality of radio paths,
The transceiver has a wireless base station connected via an optical line,
The wireless base station,
Delay measuring means for measuring the amount of delay occurring in the optical line, of the information signal transmitted from the mobile terminal,
Searcher means for detecting a delay profile for obtaining the reception timing of the information signal in a plurality of valid radio paths of the plurality of radio paths,
The searcher unit corrects a range of a search window for detecting the delay profile based on the delay amount calculated by the delay measuring unit.
[0018]
Further, the radio base station apparatus according to the present invention is configured such that the first and second radio base station apparatuses are connected to each other via a first optical line, and each of which receives an information signal transmitted from a mobile terminal via a plurality of radio paths. A transceiver
The first transceiver has a wireless base station connected via a second optical line,
The wireless base station,
A first delay measuring unit for measuring a first delay amount generated in the second optical line of the information signal transmitted from the mobile terminal;
Searcher means for detecting a delay profile for obtaining the reception timing of the information signal in a plurality of valid radio paths of the plurality of radio paths,
The second transceiver has second delay measuring means for measuring a second delay amount of the information signal transmitted from the mobile terminal in the first optical line,
The searcher means, when the information signal is received by the first transceiver, determines a range of a search window for detecting the delay profile by the first delay measurement means. The delay is corrected based on the amount of delay, and when the information signal is received by the second transceiver, the range of the search window for detecting the delay profile is calculated by the first delay measuring unit. The correction is performed based on a first delay amount and the second delay amount calculated by the second delay measuring means.
[0019]
The search window correction method of the present invention is a search window correction method performed in a device in which a transceiver that performs wireless communication with a mobile terminal is connected to a wireless base station via an optical line,
A first step of receiving the information signal transmitted from the mobile terminal by the transceiver via a plurality of wireless paths;
A second step of calculating an amount of delay occurring in the optical line of the information signal received by the transceiver;
A third step of detecting a delay profile for acquiring a reception timing of the information signal in a plurality of valid radio paths of the plurality of radio paths,
The third step includes a step of correcting a range of a search window for detecting the delay profile based on the delay amount calculated in the second step.
[0020]
Also, the search window correction method of the present invention is characterized in that the first and second wireless communication apparatuses are connected to each other via a first optical line, and wireless communication is performed with a mobile terminal via a plurality of wireless paths. A search window correction method performed in an apparatus having a transceiver and a wireless base station to which the first transceiver is connected via a second optical line,
A first step of calculating a first delay amount of the information signal received by the first transceiver in the second optical line;
A second step of calculating a second delay amount occurring in the first optical line of the information signal received by the second transceiver;
A third step of detecting a delay profile for acquiring a reception timing of the information signal in a plurality of valid radio paths of the plurality of radio paths,
In the third step, when the information signal is received by the first transceiver, the search window range for detecting the delay profile is calculated by the first delay measuring unit. When the information signal is received by the second transceiver, the range of a search window for detecting the delay profile is calculated by the first delay measuring means. And correcting based on the first delay amount and the second delay amount calculated by the second delay measuring means.
[0021]
According to the present invention as described above, it is possible to measure the amount of delay in an optical line between a radio base station and a transceiver, so that the search window range is corrected based on the measured amount of delay. Can be. The range of the search window corrected in this way is sufficiently smaller than the range of the search window in the conventional one. Specifically, the range of the search window becomes narrower than that of the conventional one because the delay amount of the optical line need not be considered. Therefore, the circuit scale becomes smaller and the time required for the path search becomes shorter as the range of the search window becomes narrower. Furthermore, by detecting the delay amount of the optical line, it becomes possible to detect the radio propagation time between the transceiver and the mobile terminal with high accuracy.
[0022]
Further, according to the present invention, when installing a wireless base station apparatus, it is not necessary to measure the length and delay time of an optical line as in the related art, so that the number of installation steps is greatly reduced.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a block diagram illustrating a schematic configuration of a wireless base station device according to an embodiment of the present invention. This radio base station apparatus is used in a CDMA mobile communication radio system, and includes a transceiver 2 for performing radio communication between a radio base station 1 and a mobile terminal (not shown); An information signal input from a higher-level device (for example, a mobile switching center) is output from the radio base station 1 to the transceiver 2 via the optical fiber 3 and further transmitted therefrom via the radio. And an information signal received by radio from the mobile terminal is output from the transceiver 2 to the wireless base station 1 via the optical fiber 3 and further output to the higher-level equipment. And
[0025]
The radio base station 1 performs transmission / reception of information signals and rake (RAKE) reception of an information signal in a DS (direct spreading) method using a spreading code composed of predetermined chip data (high-speed code sequence). It comprises a baseband signal processing section 4, a delay measuring section 5, a multiplexing section 6a, a separating section 7a, and an E / O section (photoelectric converting section) 8a.
[0026]
The baseband signal processing unit 4 multiplies (secondarily modulates) a digital information signal (a signal subjected to primary modulation) input from a higher-level device with a spreading code (high-speed code sequence) on the downlink. Is supplied to the multiplexing unit 6a as a transmission signal, and the reception signal separated by the separation unit 7a is rake-received on the uplink.
[0027]
The delay measuring unit 5 measures the amount of delay in the optical line including the optical fiber 3, and transmits a predetermined flag signal, and measures the time from when the flag signal is looped back and received by the transceiver 2. , The delay amount of the optical line in the uplink is measured.
[0028]
The multiplexing unit 6a multiplexes the flag signal supplied from the delay measuring unit 5 on the transmission signal on which spread modulation (secondary modulation) has been performed. The E / O unit 8a converts the multiplexed signal (transmission signal + flag signal) from the multiplexing unit 6a into an NRZ signal such as 8B10B and converts it into an optical signal on the downlink, and transmits and receives the signal from the transceiver 2 on the uplink. To convert an optical signal (received signal + flag signal) input through the optical fiber 3 into an electric signal.
[0029]
The transceiver 2 converts a transmission signal from the radio base station 1 into a high-frequency signal for use in system operation and transmits the signal to the mobile terminal on the downlink, and receives and transmits the signal from the mobile terminal on the uplink. The received high-frequency signal is converted to an intermediate frequency signal and output to the radio base station 1. The configuration includes a multiplexing unit 6b, a demultiplexing unit 7b, an E / O unit 8b, and a radio unit 9. .
[0030]
The E / O unit 8b converts an optical signal (transmission signal + flag signal) input from the wireless base station 1 via the optical fiber 3 into an electric signal on the downlink and outputs the signal from the multiplexing unit 6b on the uplink. The multiplexed signal is converted into an NRZ signal such as 8B10B and converted into an optical signal. The separation unit 7b separates the multiplexed signal (transmission signal + flag signal) converted into an electric signal by the E / O unit 8b into a transmission signal and a flag signal. The radio unit 9 transmits the transmission signal separated by the demultiplexing unit 7b to the mobile terminal by radio communication on the downlink, and receives the information signal by radio communication from the mobile terminal on the uplink. The multiplexing unit 6b multiplexes the information signal (received signal) received by the radio unit 9 with the flag signal separated by the separating unit 7b, and inputs the multiplexed signal to the E / O unit 8b.
[0031]
Similar to the radio base station 1, the mobile terminal can perform transmission / reception of information signals and rake (RAKE) reception in a DS (direct spreading) system using a spreading code (high-speed code sequence). The information signal (received signal) received by the radio unit 9 from the mobile terminal is subjected to secondary modulation with the same spreading code as the spreading code used in the baseband signal processing unit 4.
[0032]
Next, the operation of the wireless base station device of the present embodiment will be specifically described.
[0033]
(1) Downlink operation:
When the information signal subjected to the primary modulation is input from the higher-level device to the radio base station 1, first, in the radio base station 1, the baseband signal processing unit 4 performs spread modulation on the input information signal. While performing (secondary modulation), the delay measuring section 5 outputs a flag signal and starts measuring the delay time in the optical line. Next, the multiplexing unit 6 a multiplexes the spread-modulated transmission signal and the flag signal input from the delay measuring unit 5. Then, the E / O unit 8 a converts the multiplexed signal (transmission signal + flag signal) into an optical signal and sends out the optical signal onto the optical fiber 3.
[0034]
When the optical signal (transmission signal + flag signal) transmitted from the wireless base station 1 onto the optical fiber 3 is input to the transceiver 2, the E / O unit 8b of the transceiver 2 first receives the input signal. The optical signal (transmission signal + flag signal) is converted into an electric signal. Next, the separation unit 7b separates the multiplexed signal (transmission signal + flag signal) converted into the electric signal into a transmission signal and a flag signal. Then, the radio unit 9 transmits the separated transmission signal to the mobile terminal.
[0035]
The mobile terminal performs rake reception of the transmission signal from the transceiver 2 using the same spreading code as that used in the radio base station 1. Thereby, the spread modulated information signal can be returned to the original signal.
[0036]
(2) Uplink operation:
When an information signal that has been subjected to spread modulation (secondary modulation) with a predetermined spreading code is transmitted from the mobile terminal to the transceiver 2, first, in the transceiver 2, the radio unit 9 converts the transmitted information signal. Receive. Next, the multiplexing unit 6b multiplexes the received information signal (received signal) and the flag signal separated by the separation unit 7b. Then, the E / O unit 8 b converts the multiplexed signal (received signal + flag signal) into an optical signal and sends out the optical signal onto the optical fiber 3.
[0037]
When an optical signal (received signal + flag signal) transmitted from the transceiver 2 onto the optical fiber 3 is input to the wireless base station 1, the E / O unit 8a of the wireless base station 1 first inputs the signal. The optical signal (received signal + flag signal) is converted into an electric signal. Next, the separating unit 7a separates the multiplexed signal (received signal + flag signal) converted into the electric signal into a received signal and a flag signal. Next, the delay measuring unit 5 determines the time required from transmission to reception of the flag signal separated by the separation unit 7a, that is, from the time that the flag signal reciprocates on the optical line via the optical fiber 3, the time of the optical line. Calculate the delay amount in the uplink. Next, the baseband signal processing unit 4 corrects the search window range based on the delay amount calculated by the delay measurement unit 5. With this correction, it is possible to detect a delay profile related to the received signal separated by the separation unit 7a within a search window in which only the delay of the radio path is considered. Finally, the baseband signal processing unit 4 determines reception timings on a plurality of effective paths based on the detected delay profile, and rake-combines the reception signals on the respective effective paths. The received signal obtained by the rake combining is output from the wireless base station 1 to a higher-level device.
[0038]
In the above operation, the most characteristic point is that the delay measuring section 5 calculates the delay amount of the optical line in the uplink, and the baseband signal processing section 4 uses the calculated delay amount to search window. Are the two points that correct the range. Hereinafter, those characteristic points will be described in more detail.
[0039]
First, calculation of the delay amount of the optical line in the uplink will be described. FIG. 2 shows a specific configuration of the delay measuring unit 5, and FIG. 3 shows an example of a data format of a multiplexed signal transmitted over an optical line.
[0040]
Referring to FIG. 2, the delay measuring section 5 includes a control section 51 and a counter 52. The control unit 51 sends a flag signal to the multiplexing unit 6a in synchronization with the frame signal input from the multiplexing unit 6a, and instructs the counter 52 to start counting. As shown in FIG. 3, the frame signal is a signal in which “Low pulses” are output at regular intervals, and the multiplexing unit 6a multiplexes the flag signal with the transmission signal in synchronization with the frame signal. . Similarly, in the multiplexing unit 6b, the flag signal is multiplexed with the received signal in synchronization with the similar frame signal.
[0041]
The flag signal sent from the control unit 51 is multiplexed into a transmission signal by the multiplexing unit 6a, converted into an optical signal by the E / O unit 8a, and sent out onto the optical fiber 3 (downlink). The flag signal transmitted onto the optical fiber 3 is converted into an electric signal by the E / O unit 8b, and separated from the transmission signal by the separation unit 7b. The flag signal separated by the separation unit 7b is multiplexed into a reception signal by the multiplexing unit 6b, converted into an optical signal again by the E / O unit 8b, and sent out onto the optical fiber 3 (uplink). ). The flag signal transmitted onto the optical fiber 3 is separated from the received signal by the separation unit 7a and input to the counter 52.
[0042]
The counter 52 starts the counting operation in response to the count start instruction input from the control unit 51, and stops the counting operation at the timing when the flag signal transmitted by the control unit 51 is turned back by the transceiver 2 and returned. The count value A at that time is sent to the control unit 51. The count value A is a time during which the transmitted flag signal reciprocates on the optical line via the optical fiber 3, and the control unit 51 calculates the delay amount B (= A) of the optical line in the upstream line from the count value A. / 2) is calculated.
[0043]
Next, the point that the search window range is corrected based on the delay amount B will be described together with the specific configuration of the baseband signal processing unit 4.
[0044]
FIG. 4 shows a configuration example of the baseband signal processing unit 4. 4, the baseband signal processing unit 4 includes a searcher unit 10, finger units 20a to 20c, and a rake combining unit 30.
[0045]
The searcher unit 10 is a unit that detects a delay profile related to the received signal separated by the separation unit 7a in a search window range in which only the delay of the radio path is taken into account. Amount correction unit 12, m delay units 13 ₁ ~ 13 _m , N power calculators 14 ₁ ~ 14 _n , Comparator 15.
[0046]
The spreading code generator 11 performs a spreading code (the same as the spreading code used when the mobile terminal transmits a signal corresponding to the received signal by wireless communication) for despreading the received signal separated by the separating unit 7a. ). The delay amount correction unit 12 delays the spread code input from the spread code generation unit 11 by the delay amount B input from the delay measurement unit 5. The output of the delay amount correction unit 12 is ₁ ~ 13 _m Are connected to one end of a line connected in series, so that each delay device gives a delay for a fixed time.
[0047]
Power calculator 14 ₁ ~ 14 _n Are connected in parallel, and the reception signal separated by the separation unit 7a is input to one input of each. Power calculator 14 ₁ The output of the delay amount correction unit 12 is supplied as it is to the other input. Power calculator 14 ₂ ~ 14 _n The other input of the ₁ ~ 13 _m Is supplied.
[0048]
The comparator 15 is connected to each power calculator 14. ₁ ~ 14 _n Are detected, three peaks are detected in order from a higher reception level (reception power) on a delay profile obtained from these inputs, and a reception timing C1 corresponding to a delay time of the three peaks is detected. , C2, and C3 are supplied to the finger portions 20a, 20b, and 20c, respectively.
[0049]
The finger units 20a to 20c are connected in parallel, and one input of each of them is supplied with the reception signal separated by the separation unit 7a. The finger units 20a, 20b, and 20c perform correlation detection at the reception timings C1, C2, and C3 supplied from the comparator 15, respectively. The rake combining unit 30 combines the received signals after adjusting the respective delay times of the paths detected by the finger units 20a to 20c.
[0050]
In the baseband signal processing unit 4 configured as described above, the power calculation unit 14 of the searcher unit 10 ₁ ~ 14 _n , A spread code input from the delay amount correction unit 12 and delay-corrected by the delay amount B is used for a predetermined time interval (this time interval is ₁ ~ 13 _m Given by The product is multiplied by the received signal input from the separation unit 7a while gradually shifting the timing. As a result, the power calculator 14 ₁ ~ 14 _n 5, it is possible to acquire a delay profile in a search window range in which only the delay of the wireless path is considered, for example, as shown in FIG. The example of FIG. 5 is a delay profile detected when the radius of the wireless communication area is 10 km.
[0051]
Delay device 13 constituting searcher unit 10 ₁ ~ 13 _m And power calculator 14 ₁ ~ 14 _n Is determined by the size of the search window if the time resolution ((1 / n) chip: n is a natural number) is constant. Reducing the range of the search window also reduces the number of delay units and power calculation units. The range of the search window in the delay profile shown in FIG. 5 is narrower than the range of the search window in the delay profile shown in FIG. 13 by the amount not considering the delay (distance 20 km) in the optical line. Therefore, the number of delay units and power calculation units can be reduced by the narrower search window range, and the circuit scale of searcher unit 10 is reduced accordingly. Also, the time required for the path search is shortened.
[0052]
(Example)
FIG. 6 is a block diagram showing an example of a wireless communication system using the wireless base station device shown in FIG. In this wireless communication system, the transceiver 2a is communicably connected to the wireless base station 1 via an optical fiber 3a having a fiber length of 100 m, and the transceiver 2b is connected to the wireless base station via an optical fiber 3b having a fiber length of 10 km. It is communicably connected to the station 1. The radius of the communication area (cell) of each of the transceivers 2a and 2b is 10 km. The amount of delay in each of the optical fibers 3a and 3b is 5 μs per km.
[0053]
The transceivers 2a and 2b are the same as the transceiver 2 shown in FIG. The wireless base station 1 is the same as that shown in FIG. 1, and includes the delay measuring unit 5 shown in FIG. 2 and the baseband signal processing unit 4 shown in FIG. The count clock of the counter 52 of the delay measuring unit 5 is 50 MHz (1 clock = 20 ns). Device fixed delay (the delay in the wireless base station 1 and the delay in the transceiver 2a (or the transceiver 2b), not including the delay in the optical line section via the optical fiber 3a (or the optical fiber 3b)) Is 1 μs.
[0054]
FIG. 7 shows a timing chart of input / output signals of the delay measuring unit 5 when measuring the delay amount of the optical line in the transmission path via the transceiver 2b. In FIG. 7, the count clock is a reference clock for counting by the counter 52, and here is 50 MHz (1 clock = 20 ns). The frame signal is a signal supplied from the multiplexing unit 6a to the delay measuring unit 5, and “Low pulse” is output at regular intervals as shown in FIG. The count value is the count value of the counter 52, and is shown here in decimal.
[0055]
The control unit 51 outputs a flag signal and starts counting in synchronization with the “Low pulse” of the frame signal input from the multiplexing unit 7b. The counter 52 counts with a count clock of 50 MHz (1 clock = 20 ns). When the output flag signal is looped back by the transceiver 2b and input again to the delay measuring unit 5, the counter 52 stops counting. In this example, the counter 52 is stopped at the count “10000”.
[0056]
Since the count value is “10000” and the count clock is “1 clock = 20 ns”, the control unit 51 determines the one-way delay amount T of the optical line.
T = 10000 × 20 ns / 2 = 100 μs
It is calculated from: The delay amount T (100 μs) calculated in this way is supplied to the searcher unit 12.
[0057]
In the searcher unit 12, first, the delay amount correction unit 12 delays the spread code supplied from the spread code generation unit 11 by the time corresponding to the delay amount T (100 μs) supplied from the delay measurement unit 5. Make corrections. By this delay correction, it is possible to detect a delay profile in a search window range as shown in FIG. 5, which considers only the delay of the wireless path (10 km). When the delay profile is detected, the comparator 15 detects a plurality of peaks on the delay profile in descending order of the reception level (reception power), and determines the reception timing corresponding to the delay time of those peaks. Each is supplied to a plurality of finger portions. Accordingly, correlation detection can be performed at a plurality of finger units, and rake reception can be performed.
[0058]
(Other embodiments)
FIG. 8 is a block diagram illustrating a schematic configuration of a wireless base station device according to another embodiment of the present invention. In this radio base station apparatus, the transceiver 100 and the radio base station 1 are connected to be capable of optical communication via an optical fiber 3a ', and the transceiver 100 and the transceiver 200 are capable of optical communication via an optical fiber 3b'. It is of a connected, daisy-chain structure. The fiber lengths of the optical fibers 3a 'and 3b' are 5 km and 10 km, respectively.
[0059]
In the wireless base station apparatus of the present embodiment, information signals are transmitted and received to and from a mobile terminal (not shown) in one of the communication areas (cells) of the transceivers 100 and 200. When the mobile terminal is in the communication area of the transceiver 100, an information signal input from a higher-level device (for example, a mobile switching center) is transmitted from the radio base station 1 to the transceiver 100 via the optical fiber 3a 'on the downlink. It is output and transmitted wirelessly to the mobile terminal. Also, in the uplink, an information signal wirelessly received from the mobile terminal is output from the transceiver 100 to the wireless base station 1 via the optical fiber 3a ', and is supplied from there to a higher-level device.
[0060]
When the mobile terminal is in the communication area of the transceiver 200, an information signal input from a higher-level device is output from the wireless base station 1 to the transceiver 100 via the optical fiber 3a 'on the downlink, and 100 is output to the transceiver 200 via the optical fiber 3b ', from which it is transmitted wirelessly to the mobile terminal. In the uplink, an information signal wirelessly received from the mobile terminal is output from the transceiver 200 to the transceiver 100 via the optical fiber 3b ', and further transmitted from the transceiver 100 to the wireless base station via the optical fiber 3a'. 1 and is supplied to the host device from there.
[0061]
As described above, in the wireless base station apparatus of the present embodiment, when the mobile terminal is in the communication area of the transceiver 200, the mobile terminal relays the transceiver 100. It has a function to measure the amount. FIG. 9 shows a specific configuration of the radio base station apparatus. Hereinafter, the device configuration will be specifically described with reference to FIGS. 8 and 9.
[0062]
The wireless base station 1 is the same as that shown in FIG. 1, and has a configuration including a baseband signal processing unit 4, a delay measuring unit 5, a multiplexing unit 6a, a separating unit 7a, and an E / O unit 8a. Here, it is assumed that the delay measuring unit 5 measures the delay amount in the first optical line including the optical fiber 3a ′, sends out the flag signal A, and returns the flag signal A by the transceiver 100 for reception. The delay amount of the first optical line in the uplink is measured from the time until the delay.
[0063]
The transceiver 100 converts the transmission signal from the radio base station 1 into a high-frequency signal for use in system operation and transmits the signal to the mobile terminal on the downlink, or receives and transmits the signal from the mobile terminal on the uplink. Or the like to convert the received high-frequency signal into an intermediate frequency signal and output it to the radio base station 1. The radio communication unit 101, the delay measuring unit 102, the multiplexing / demultiplexing unit 103, the E / O unit 104a and 104b.
[0064]
Radio section 101 and multiplexing / demultiplexing section 103 are basically the same as multiplexing section 6b, demultiplexing section 7b and radio section 9 shown in FIG. The E / O unit 104a converts an optical signal (transmitted signal + flag signal A) supplied via the optical fiber 3a 'into an electric signal on the downlink, and outputs the signal from the multiplexing / demultiplexing unit 103 on the uplink. It converts an input multiplexed signal (received signal + flag signal A) into an optical signal, and is basically the same as the E / O unit 8b shown in FIG. The delay measuring section 102 measures the amount of delay in the second optical line including the optical fiber 3b ', sends a flag signal B, and the flag signal B is returned by the transceiver 200 and received. The delay amount of the second optical line in the uplink is measured from the time until the delay. The E / O section 104b converts the multiplexed signal (transmission signal + flag signal B) input from the multiplexing / demultiplexing section 103 into an optical signal on the downlink, and also transmits the multiplexed signal via the optical fiber 3b 'on the uplink. The supplied optical signal (received signal + flag signal B) is converted into an electric signal.
[0065]
The transceiver 200 has the same configuration as the transceiver 100, and includes a radio unit 201, a delay measurement unit 202, a multiplexing / demultiplexing unit 203, and E / O units 204a and 204b. The delay measuring section 202 and the E / O section 204b are necessary when the transceiver 200 is further used as a relay point. When such a relay point is not configured, the delay measurement unit 202 and the E / O unit 204b may be deleted.
[0066]
Next, a rake reception operation performed in the wireless base station device of the present embodiment will be specifically described. The rake combining is basically the same as the rake combining in the configuration shown in FIG. 1, and therefore, the description will focus on the detection of the delay profile.
[0067]
First, the operation of detecting a delay profile when the mobile terminal is within the communication area of the transceiver 100 will be described. In this case, the delay profile is basically detected by the same operation as the operation of detecting the delay profile in the configuration shown in FIG. First, in the wireless base station 1, the delay measuring unit 5 sends out the flag signal A, and the first optical signal in the uplink line starts from the time when the sent out flag signal A is turned back by the transceiver 100 and received again. The line delay A is measured. Next, the baseband processing unit 4 performs a correction for delaying the internally generated spread code by the time of the delay amount A supplied from the delay measurement unit 5. By this delay correction, a search taking into account only the delay of the wireless path (a delay of a distance corresponding to the radius of the communication area of the transceiver 100 or the transceiver 200 and given in advance) as shown in FIG. Detect the delay profile within the window.
[0068]
Next, the operation of detecting a delay profile when the mobile terminal is within the communication area of the transceiver 100 will be described. In this case, in addition to the delay measurement of the first optical line (the portion of the optical fiber 3a ') by the delay measuring unit 5 in the wireless base station 1, the second optical line by the delay measuring unit 102 in the transceiver 100 is used. The delay measurement of the optical fiber 3b 'is performed. More specifically, the delay measuring section 102 sends the flag signal B, and the delay from the time when the sent flag signal B is looped back by the transceiver 200 to when it is received again is the delay of the second optical line in the uplink. Measure quantity B. Then, the transceiver 100 sends the delay amount B measured by the delay measuring section 102 to the delay measuring section 5 of the wireless base station 1 on the uplink.
[0069]
In the radio base station 1, the delay measuring unit 5 supplies the baseband signal processing unit 4 with a total delay amount (A + B) of the delay amount A in the first optical line and the delay amount B in the second optical line. Then, the baseband signal processing unit 4 performs a correction for delaying the internally generated spread code by a time corresponding to the delay amount (A + B) supplied from the delay measurement unit 5. By this delay correction, a search taking into account only the delay of the wireless path (a delay of a distance corresponding to the radius of the communication area of the transceiver 100 or the transceiver 200 and given in advance) as shown in FIG. A delay profile can be detected within the window.
[0070]
Also in the above-described wireless base station apparatus of the present embodiment, the range of the search window can be reduced. Therefore, the number of delay units and power calculation units can be reduced as much as the search window range is narrowed, and the circuit size of the searcher unit is reduced accordingly. Also, the time required for the path search is shortened.
[0071]
When the daisy chain structure as in the present embodiment is adopted, both the transmission signal transmitted on the downlink and the reception signal transmitted on the uplink may be transmitted by time division multiplexing. For example, a transmission signal transmitted from the radio base station 1 (or a reception signal received from a mobile terminal) is time-division multiplexed into a signal addressed to the transceiver 100 and a signal addressed to the transceiver 200 as shown in FIG. May be transmitted.
[0072]
The above description is one embodiment of the present invention, and the configuration can be variously changed according to the design. For example, in the configuration of FIG. 1, only one transceiver is shown, but a plurality of transceivers may be connected to the wireless base station via different optical fibers. Further, in the configuration of FIG. 9, a daisy chain structure in which three or more transceivers are connected may be employed. Further, the configuration of FIG. 1 and the configuration of FIG. 9 can be combined.
[0073]
(Application example: positioning system)
The current position of the mobile terminal can be detected using the wireless communication system including the wireless base station device according to each of the embodiments described above. One example of a system capable of such position detection is an OTDOA type positioning system. FIG. 11 shows a conceptual diagram of position detection in the OTDOA positioning system.
[0074]
In FIG. 11, the three wireless base stations 21a to 21c adopt any one of the forms of the wireless base station apparatuses of the above-described embodiments. Although a transceiver is not shown in FIG. 11 for convenience, a plurality of transceivers are connected to the wireless base stations 21a to 21c via optical fibers. Further, position information (for example, latitude and longitude) of a plurality of connected transceivers is given in advance to each of the wireless base stations 21a to 21c.
[0075]
The position of the mobile terminal 22 is determined by measuring the distance between the mobile terminal 22 and the three wireless base stations 21a to 21c (actually, the distance between the mobile terminal 22 and the transceivers of the wireless base stations 21a to 21c) from the signal arrival time. It is done by doing. For example, when circles each having the radius of the distance to the mobile terminal 22 are drawn around each wireless base station (actually, the transceiver), the intersection of each circle becomes the position of the mobile terminal 22. If the position of the wireless base station (actually, the transceiver) is known in advance, the position of the mobile terminal 22 can be obtained.
[0076]
The measurement of the distance from the mobile terminal 22 in each of the radio base stations 21a to 21c is performed as follows. Here, assuming that each of the wireless base stations 21a to 21c has the configuration of the wireless base station device shown in FIG. 1, the position detecting operation of the mobile terminal 22 will be described.
[0077]
In the wireless base station 21a, the delay measuring unit 5 transmits the flag signal, and measures the delay amount of the optical line in the uplink from the time until the transmitted flag signal is looped back by the transceiver 2 and received again. . Next, the baseband processing unit 4 performs a correction to give a delay to the internally generated spread code by the time of the delay amount supplied from the delay measurement unit 5. By this delay correction, a search taking into account only the delay of the wireless path (a delay of a distance corresponding to the radius of the communication area of the transceiver 100 or the transceiver 200 and given in advance) as shown in FIG. A delay profile can be detected within the window.
[0078]
The baseband processing unit 4 acquires the reception timing C of the path having the largest received power from the highest peak on the delay profile detected as described above, and reports this to the delay measurement unit 5. For example, in the example of FIG. 5, 20 μs is acquired as the reception timing C. The delay measuring unit 5 calculates a radio propagation time E (= CD) between the transceiver 2 and the mobile terminal 22 from the known device fixed delay amount D. For example, if the reception timing C is 20 μs and the device fixed delay amount D is 1 μs, the radio propagation time E is 19 μs. This calculation result is supplied to a positioning system as a host device.
[0079]
In the other two radio base stations 21b and 21c, the radio propagation time E (= CD) between the transceiver 2 and the mobile terminal 22 is calculated in the same procedure as in the case of the radio base station 21a. The calculation result is supplied to a positioning system as a host device.
[0080]
In the positioning system, the position of the mobile terminal 22 is obtained from the wireless propagation time E supplied from each of the wireless base stations 21a to 21c and the position information of the transceiver of each wireless base station.
[0081]
According to the above-described positioning system, each of the wireless base stations 21a to 21c can accurately measure the delay amount in the optical line including the optical fiber, so that the accurate position of the mobile terminal 22 can be detected.
[0082]
Further, in the example of FIG. 11, the position is detected from the distance between at least three wireless base stations and the mobile terminal. However, in the configuration of FIG. 1 or the configuration of FIG. It is also possible to perform position detection from the distance between the three transceivers and the mobile terminal.
[0083]
【The invention's effect】
As described above, according to the present invention, since the range of the search window can be reduced as compared with the related art, the circuit scale of the searcher unit can be reduced accordingly. Therefore, a small-sized, low-cost wireless base station with low power consumption can be provided.
[0084]
In addition, since the delay amount of the optical line (optical fiber portion) can be automatically measured, the number of installation work can be significantly reduced.
[0085]
Furthermore, since the radio propagation time between the transceiver and the mobile terminal can be accurately calculated, the current position of the mobile terminal can be detected with high accuracy in the application to the positioning system of the OTDOA system.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of a wireless base station device according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a specific configuration of a delay measuring unit shown in FIG.
FIG. 3 is a diagram illustrating an example of a data format of a multiplexed signal transmitted over an optical line of the wireless base station device illustrated in FIG. 1;
FIG. 4 is a block diagram illustrating a specific configuration of a baseband signal processing unit illustrated in FIG. 1;
FIG. 5 is a diagram showing an example of a delay profile detected in the wireless base station device shown in FIG.
FIG. 6 is a block diagram showing an example of a wireless communication system using the wireless base station device shown in FIG.
7 is a timing chart for explaining an operation when measuring the amount of delay of an optical line in a transmission path via the transceiver shown in FIG. 6;
FIG. 8 is a block diagram illustrating a schematic configuration of a wireless base station device according to another embodiment of the present invention.
FIG. 9 is a block diagram showing a specific configuration of the radio base station apparatus shown in FIG.
FIG. 10 is a diagram showing an example of a delay profile detected in the wireless base station device shown in FIG.
FIG. 11 is a conceptual diagram for explaining position detection in an OTDOA type positioning system which is an application example of the wireless base station apparatus of the present invention.
FIG. 12 is a diagram illustrating a DS system.
FIG. 13 is a diagram showing an example of a delay profile detected in a conventional wireless base station device.
[Explanation of symbols]
1 wireless base station
2, 2a, 2b, 100, 200 transceiver
3, 3a, 3b, 3a ', 3b' optical fiber
4 Signal processing unit
5, 102, 202 Delay measurement unit
6a, 6b Multiplexer
7a, 7b Separation unit
8a, 8b, 104a, 104b, 204a, 204b E / O unit
9, 101, 201 Radio unit
10 Searcher Club
11 Spreading code generator
12 Delay amount correction unit
13 ₁ ~ 13 _m Delay unit
14 ₁ ~ 14 _n Power calculator
15 Comparators
20a-20c finger part
21a-21b wireless base station
22 Mobile terminal
30 Lake synthesis unit
51 Control unit
52 counter
103, 203 multiplexing / demultiplexing unit

Claims (16)

A transceiver in which an information signal transmitted from a mobile terminal is received via a plurality of wireless paths;
The transceiver has a wireless base station connected via an optical line,
The wireless base station,
Delay measuring means for measuring the amount of delay occurring in the optical line, of the information signal transmitted from the mobile terminal,
Searcher means for detecting a delay profile for obtaining the reception timing of the information signal in a plurality of valid radio paths of the plurality of radio paths,
The radio base station apparatus, wherein the searcher unit corrects a range of a search window for detecting the delay profile based on the delay amount calculated by the delay measuring unit. The delay measuring means transmits a flag signal at a predetermined timing, measures a time required for the transmitted flag signal to be looped back by the transceiver and returned, and calculates the delay amount from the measured time. The radio base station apparatus according to claim 1, wherein The searcher means,
Spreading code generating means for generating a predetermined spreading code;
Delay amount correcting means for causing a delay by the amount of the delay calculated by the delay measuring means to a predetermined spreading code generated by the spreading code generating means,
Delay profile detection means for detecting the delay profile using the predetermined spreading code delayed by the delay amount correction means,
3. The apparatus according to claim 1, further comprising a comparison unit configured to acquire reception timings of the information signals on the plurality of valid wireless paths based on the delay profile detected by the delay profile detection unit. 4. Wireless base station device. The searcher means outputs the reception timing of the information signal in the radio path having the highest reception level of the plurality of valid radio paths obtained from the delay profile to the delay measurement means,
4. The wireless communication apparatus according to claim 3, wherein the delay measuring unit calculates a wireless propagation time between the transceiver and the mobile terminal based on the calculated delay amount and the reception timing input from the searcher unit. 3. The wireless base station device according to 1. First and second transceivers connected to each other via a first optical line, each receiving an information signal transmitted from a mobile terminal via a plurality of wireless paths;
The first transceiver has a wireless base station connected via a second optical line,
The wireless base station,
A first delay measuring unit for measuring a first delay amount generated in the second optical line of the information signal transmitted from the mobile terminal;
Searcher means for detecting a delay profile for obtaining the reception timing of the information signal in a plurality of valid radio paths of the plurality of radio paths,
The second transceiver has second delay measuring means for measuring a second delay amount of the information signal transmitted from the mobile terminal in the first optical line,
The searcher means, when the information signal is received by the first transceiver, determines a range of a search window for detecting the delay profile by the first delay measurement means. The delay is corrected based on the amount of delay, and when the information signal is received by the second transceiver, the range of the search window for detecting the delay profile is calculated by the first delay measuring unit. A radio base station apparatus, wherein correction is performed based on a first delay amount and the second delay amount calculated by the second delay measuring means. The first delay measuring means transmits a first flag signal at a predetermined timing, and measures a time until the transmitted first flag signal is returned by the first transceiver and returned. And calculating the first delay amount from the measured time;
The second delay measuring means transmits a second flag signal at a predetermined timing, and measures a time until the transmitted second flag signal is returned by the second transceiver and returned. The radio base station apparatus according to claim 5, wherein the second delay amount is calculated from the measured time. The searcher means,
Spreading code generating means for generating a predetermined spreading code;
When the information signal is received by the first transceiver, a predetermined spread code generated by the spread code generating means is divided by the first delay amount calculated by the first delay measuring means. And when the information signal is received by the second transceiver, the predetermined spread code generated by the spread code generation means is calculated by the first delay measurement means. Delay amount correcting means for causing a delay by a delay amount obtained by adding the second delay amount calculated by the second delay measuring means to one delay amount;
As for the information signal received by the first transceiver, the delay profile is detected by using the predetermined spreading code delayed by the first delay amount by the delay amount correcting means. The information signal received by the second transceiver is delayed by the delay amount correcting means by a delay amount corresponding to the sum of the first and second delay amounts. Delay profile detection means for detecting the delay profile using a spreading code,
7. The comparing device according to claim 5, further comprising: comparing means for acquiring reception timings of the information signals on the plurality of valid wireless paths based on the delay profile detected by the delay profile detecting means. Wireless base station device. The searcher means outputs the reception timing of the information signal in a radio path having a highest reception level among the plurality of valid radio paths, obtained from the delay profile, to the first delay measurement means,
When the information signal is received by the first transceiver, the first delay measurement unit determines the first delay amount based on the first delay amount and the reception timing input from the searcher unit. Calculating a radio propagation time between a transceiver and the mobile terminal, and when the information signal is received by the second transceiver, a delay amount obtained by adding the first and second delay amounts; The radio base station apparatus according to claim 7, wherein a radio propagation time between the second transceiver and the mobile terminal is calculated from the reception timing input from a means. A search window correction method in which a transceiver that performs wireless communication with a mobile terminal is performed in a device connected to a wireless base station via an optical line,
A first step of receiving the information signal transmitted from the mobile terminal by the transceiver via a plurality of wireless paths;
A second step of calculating an amount of delay occurring in the optical line of the information signal received by the transceiver;
A third step of detecting a delay profile for acquiring a reception timing of the information signal in a plurality of valid radio paths of the plurality of radio paths,
The third step includes a step of correcting a range of a search window for detecting the delay profile based on the delay amount calculated in the second step. The second step is
Transmitting a flag signal at a predetermined timing, measuring a time until the transmitted flag signal is looped back by the transceiver, and returning, and calculating the delay amount from the measured time. The search window correction method according to claim 9, wherein The third step is
Generating a predetermined spreading code;
Causing a delay in the generated predetermined spreading code by the delay amount calculated in the second step;
Detecting the delay profile using the delayed predetermined spreading code,
Acquiring the reception timing of the information signal in the plurality of valid wireless paths based on the detected delay profile. From the delay profile obtained from the delay profile, the reception timing of the information signal in the radio path having the highest reception level among the plurality of valid radio paths, and the delay amount calculated in the second step, the transceiver The method according to claim 11, further comprising a fourth step of calculating a radio propagation time between the mobile terminal and the mobile terminal. A first and second transceivers connected to each other via a first optical line, each performing wireless communication with a mobile terminal via a plurality of wireless paths; and A search window correction method performed in a device having a wireless base station connected via a second optical line,
A first step of calculating a first delay amount of the information signal received by the first transceiver in the second optical line;
A second step of calculating a second delay amount occurring in the first optical line of the information signal received by the second transceiver;
A third step of detecting a delay profile for acquiring a reception timing of the information signal in a plurality of valid radio paths of the plurality of radio paths,
In the third step, when the information signal is received by the first transceiver, the search window range for detecting the delay profile is calculated by the first delay measuring unit. When the information signal is received by the second transceiver, the range of a search window for detecting the delay profile is calculated by the first delay measuring means. A correction step based on the first delay amount and the second delay amount calculated by the second delay measuring means. The first step is to transmit a first flag signal at a predetermined timing, and measure a time until the transmitted first flag signal is returned by the first transceiver and returned. Calculating the first delay amount from the measured time,
The second step transmits a second flag signal at a predetermined timing, and measures a time until the transmitted second flag signal is returned by the second transceiver and returned. 14. The search window correction method according to claim 13, further comprising a step of calculating the second delay amount from the measured time. The third step is
Generating a predetermined spreading code;
When the information signal is received by the first transceiver, the predetermined spread code is delayed by the first delay amount calculated in the first step, and the second spread code is delayed by the second spread code. When the information signal is received by the transmitter / receiver, the second delay calculated in the second step is added to the first delay amount calculated in the first step for the predetermined spreading code. Causing a delay by the amount of the delay that has been added;
For the information signal received by the first transceiver, the delay profile is detected using the predetermined spreading code delayed by the first delay amount, and the second transmission / reception is performed. Detecting the delay profile using the predetermined spreading code that has caused a delay by an amount equal to the sum of the first and second delay amounts, for the information signal received by the device;
The method according to claim 13, further comprising: acquiring a reception timing of the information signal on the plurality of valid wireless paths based on the detected delay profile. When the information signal is received by the first transceiver, obtained from the delay profile, the reception timing of the information signal on a radio path having a highest reception level among the plurality of valid radio paths, and From the delay amount of 1, the wireless propagation time between the first transceiver and the mobile terminal is calculated, and when the information signal is received by the second transceiver, it is obtained from the delay profile, From the reception timing of the information signal in the radio path having the highest reception level among the plurality of valid radio paths, and the delay amount obtained by adding the first and second delay amounts, the second transceiver The method according to claim 15, further comprising a fourth step of calculating a radio propagation time between the mobile terminals.

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