JP4095945B2 - Mobile communication base station and phase shift compensation method used therefor - Google Patents

Description

  The present invention relates to a mobile communication base station that relays communication of a mobile communication terminal such as a mobile phone or PHS (Personal Handy-phone System), and a phase shift compensation method used therefor.

In mobile communications such as cellular phones and PHS, there is a method of achieving a suitable handover between base station areas by synchronizing each other between base stations. Conventionally, as a method for realizing synchronization between base stations, a method based on a synchronization signal transmitted from a center to each base station via a signal line, or a global positioning system (GPS) is configured. Some are performed based on time information emitted by GPS satellites. Among these, in the method using the synchronization signal transmitted to the base station via a wired line, the delay time differs for each base station depending on the distance of the line between the center and the base station, and the delay is the state of the line. Therefore, it is difficult to correct the difference in delay time between the base stations with high accuracy. On the other hand, the synchronization using the GPS does not have such a difficulty, and high-precision synchronization can be realized relatively easily.
Japanese Patent Laid-Open No. 10-84567

  In order to acquire accurate time information by GPS, it is required to receive from three or more satellites. Therefore, when the number of received satellites is two or less, it is difficult to realize accurate synchronization between base stations even by a method using GPS. Even when the reference signal for synchronization cannot be obtained from the outside as described above, the phase shift is suppressed by, for example, maintaining the accuracy of the oscillation frequency by using a temperature compensated crystal oscillator for the base station oscillator. Things have been done.

  However, in the related art, the individual situation where the mobile communication base station is placed is not always considered sufficiently, and there is a problem that the phase shift is not suitably suppressed. For example, the temperature compensation characteristics of oscillators, etc., which are basically adjusted and set at the time of shipment or installation of the base station, are continuously used, and can vary depending on the installation environment and usage conditions of the base station. Changes in compensation characteristics over time are not taken into account. For this reason, the accuracy of phase shift compensation at each base station is reduced, and accurate inter-base station synchronization is difficult to obtain.

  The mobile communication base station according to the present invention controls the synchronization signal generating means based on the temperature compensation information, compensates for the phase shift of the synchronization signal according to the temperature, and constitutes a global positioning system. GPS receiving means for receiving a time signal from the above, a phase deviation detecting means for detecting a phase deviation amount of the synchronization signal based on the time signal, a temperature sensor for measuring the temperature of the communication base station, the temperature and Compensation information updating means for generating new temperature compensation information based on the measured values of the phase shift amounts and updating the temperature compensation information stored in the compensation information storage means.

  Another mobile communication base station according to the present invention includes a GPS receiver that receives a time signal from a GPS satellite that constitutes a global positioning system, and a phase shift amount of a synchronization signal that is compensated by the phase shift compensator. A phase shift detection means for detecting based on a time signal, a change transition storage means for storing phase change transition information representing a temporal transition of the detected phase shift amount, and when the phase shift amount is not detected, Phase shift estimation means for estimating the amount of phase shift based on phase change transition information.

  A preferred aspect of the present invention is a mobile communication base station in which the phase change transition information represents a temporal transition of the phase shift amount over one day.

  Another preferred aspect of the present invention includes a temperature sensor for measuring the temperature of the communication base station, and the change transition storage means stores the phase change transition information for a plurality of days together with the temperature at each time, The phase shift estimation means is a mobile communication base station that selects and uses any of the plurality of phase change transition information based on the current time and temperature.

  Still another preferred aspect of the present invention is the mobile communication base station in which the change transition storage means stores the phase change transition information of a plurality of seasons.

  A phase shift compensation method for a mobile communication base station according to the present invention includes a GPS reception step of receiving a time signal from GPS satellites constituting a global positioning system, and a phase shift amount of a synchronization signal based on the time signal. A phase shift detection step for detecting, a phase shift compensation step for compensating for a phase shift of the synchronization signal using the detected phase shift amount, a temperature measurement step for measuring the temperature of the communication base station, and the synchronization signal Compensation information for generating new temperature compensation information based on the measured values of the temperature and the phase shift amount and updating the temperature compensation information currently stored An update step, wherein the phase shift compensation step detects the phase shift based on the temperature compensation information when the phase shift amount is not detected. To estimate the amount to compensate for the phase shift of the synchronization signal using the estimated phase shift amount.

  A phase shift compensation method for a mobile communication base station according to the present invention includes a GPS reception step of receiving a time signal from GPS satellites constituting a global positioning system, and a phase shift amount of a synchronization signal based on the time signal. A phase shift detection step for detecting, a phase shift compensation step for compensating for a phase shift of the synchronization signal using the detected phase shift amount, and phase change transition information representing a temporal transition of the detected phase shift amount A change transition storing step for storing the phase shift compensation step, and the phase shift compensation step estimates the phase shift amount based on the phase change transition information when the phase shift amount is not detected, and the estimated phase shift The amount is used to compensate for the phase shift of the synchronization signal.

  According to the present invention, normally, the phase shift is accurately compensated based on the time signal from the GPS satellite, while the temperature compensation information is updated using the phase shift amount obtained based on the GPS satellite at the base station. The As a result, it is possible to cope with changes in temperature compensation information over time that may be different for each mobile communication base station, and the accuracy of phase deviation compensation based on temperature compensation information that is performed when it becomes impossible to detect the amount of phase deviation based on GPS satellites. Will improve.

  According to another aspect of the present invention, the phase shift amount can be different for each base station depending on the environment, usage load, etc. while the phase shift is accurately compensated based on the time signal from the GPS satellite. Is measured based on GPS satellites and recorded as phase change transition information. When the phase shift amount cannot be detected based on the GPS satellite, the phase shift compensation can be performed using the phase change transition information. Here, since the phase change transition information is based on the results in each base station, it is possible to compensate for the phase shift with high accuracy corresponding to the individual situation of each base station.

  Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

[Embodiment 1]
FIG. 1 is a block diagram showing a schematic configuration of a mobile communication base station according to the present invention. The mobile communication base station 2 includes a wireless communication unit 4, a wired communication unit 6, a GPS receiving unit 8, a temperature sensor 10, a control unit 12, and an antenna 14, and is connected to a network 16 by a signal line.

  The wireless communication unit 4 communicates wirelessly with a mobile communication terminal such as a mobile phone or a PHS terminal via the antenna 14. The wireless communication is performed under synchronization between base stations, and a GPS receiver 8 is provided for the synchronization. The GPS receiving unit 8 receives radio waves emitted from GPS satellites, acquires a time signal contained therein, and inputs the time signal to the control unit 12.

  The wired communication unit 6 communicates with the network 16. The network 16 is connected to another mobile communication base station 2 and a center (not shown). The wireless communication unit 4 and the wired communication unit 6 can exchange communication signals with each other, whereby the mobile communication terminal is connected to the network 16 via the mobile communication base station 2. And so on. The center provided on the network 16 supplies a synchronization signal for synchronization between base stations to each mobile communication base station 2, and this synchronization signal is received by the wired communication unit 6 and input to the control unit 12. The

  The temperature sensor 10 measures the temperature in the housing of the mobile communication base station 2, and the measurement result is input to the control unit 12. The control unit 12 performs temperature compensation control of the oscillator based on the measured temperature.

  The control unit 12 controls each unit of the mobile communication base station 2. In particular, the control unit 12 generates a reference clock synchronized between the base stations using the time signal from the GPS receiving unit 8, the synchronization signal from the center, and the temperature measured by the temperature sensor 10. When the wireless communication unit 4 operates based on this reference clock, synchronization between base stations for wireless communication is realized.

  FIG. 2 is a block diagram showing a schematic configuration for generating a reference clock in the present embodiment. The control unit 12 includes an oscillator 20, a frequency divider 22, a temperature compensation information storage unit 24, a GPS phase information generation unit 26, a line phase information generation unit 28, and a phase trend data generation unit 30 as a configuration for generating a reference clock. .

  The oscillator 20 receives a GPS 1 second pulse which is a time signal from the GPS receiver 8 and a line 8 kHz signal which is a synchronization signal from the center, and generates an original signal having a predetermined frequency so as to synchronize with a signal having a certain period. To do. The frequency divider 22 divides the original signal by a predetermined ratio to generate a 20 mS cycle clock signal, which is supplied to the wireless communication unit 4 as a reference clock. The temperature compensation information storage unit 24 stores temperature compensation characteristics, reads temperature compensation information corresponding to the temperature measurement value by the temperature sensor 10, and outputs the temperature compensation information to the oscillator 20. Based on this temperature compensation information, the oscillator 20 compensates for fluctuations in the oscillation frequency corresponding to the temperature.

  The 20 mS clock generated by the frequency divider 22 is supplied to the radio communication unit 4 and is also input to the GPS phase information generation unit 26 and the line phase information generation unit 28. The GPS phase information generation unit 26 receives the 20 mS clock and the GPS 1 second pulse, detects a phase shift amount of the 20 mS clock with reference to the GPS 1 second pulse, and outputs the detected phase difference data to the phase trend data generation unit 30 as GPS phase information. . Similarly, the line phase information generation unit 28 receives the 20 mS clock and the line 8 kHz signal, detects the phase shift amount of the 20 mS clock with reference to the line 8 kHz signal, and supplies the line phase information to the phase trend data generation unit 30. Output.

  The phase trend data generation unit 30 receives a temperature measurement value from the temperature sensor 10 in addition to the GPS phase information and the line phase information, generates phase correction information, and outputs the phase correction information to the oscillator 20. The oscillator 20 controls the phase of the original signal according to the phase correction information.

  FIG. 3 is a block diagram showing a schematic configuration of the phase trend data generation unit 30. The phase trend data generation unit 30 includes a phase correction data generation unit 40, a phase change transition storage unit 42, and a trend generation unit 44.

  When the GPS phase information is obtained from the GPS phase information generation unit 26, the phase correction data generation unit 40 generates and outputs phase correction information for the oscillator 20 based on the GPS phase information. On the other hand, when the number of GPS satellites that can be captured is insufficient, phase correction information for the oscillator 20 is generated and output based on the line phase information from the line phase information generation unit 28. Here, if the number of GPS satellites to be captured is 0, the line phase information is selected, and if the number is 3 or more, the GPS phase information is selected.

  When the GPS phase information is obtained, the phase correction data generation unit 40 outputs the phase correction information based on the GPS phase information as described above, and associates the temperature measurement value from the temperature sensor 10 with the GPS phase information. To the phase change transition storage unit 42. The phase change transition storage unit 42 stores these temperature measurement values and GPS phase information. At this time, the phase change transition storage unit 42 can store the time when the GPS phase information is obtained, and the date in association with the temperature measurement value and the GPS phase information. Thus, the phase change transition storage unit 42 stores the GPS phase information as phase change transition information associated with the temperature measurement value, time, and date (season).

  The phase change transition information is stored, for example, as a set of time transitions of GPS phase information over one day. The phase shift amount can be influenced by the communication load handled by the mobile communication base station 2 (or change in the power supply voltage affected by the influence) in addition to the temperature. Therefore, for example, the phase change transition storage unit 42 classifies and stores phase change transition information in units of one day based on date information according to factors that may cause different communication loads, such as by day of the week or by season. Can do. Further, the phase change transition information can be set to one unit of another time scale such as a temporal transition of GPS phase information over one week. FIG. 4 is a schematic diagram showing an example of phase change transition information over one day, with the horizontal axis representing time and the vertical axis representing GPS phase information. This example shows that the phase shift shifts to the positive side during the day when the temperature rises and the communication load increases, and shifts to the negative side at night.

  When phase change transition information having the same or similar classification conditions such as day of the week or season is obtained, the phase change transition storage unit 42 can update what is already stored at any time. In this update process, the previously obtained data can be overwritten with the one obtained later, or the data already stored and the data obtained later are weighted and averaged at a predetermined rate. You can also

  The phase change transition information stored in the phase change transition storage unit 42 is read by the trend generation unit 44 when the time signal from the GPS satellite cannot be received. The trend generation unit 44 receives the temperature measurement value from the temperature sensor 10, searches for and reads out GPS phase information corresponding to the current temperature from the storage contents of the phase change transition storage unit 42. Here, when the phase change transition storage unit 42 stores the GPS phase information in association with information other than the temperature as described above, the trend generation unit 44, for example, in addition to the temperature, Using the day of the week and season as search conditions, the daily phase change transition information is retrieved from the phase change transition storage unit 42 and read out.

  The GPS phase information or the daily phase change transition information acquired from the phase change transition storage unit 42 is input to the phase correction data generation unit 40, and the phase shift amount estimation information (current estimation value or future change prediction). Used as

  In an example of a use form in the phase correction data generation unit 40 of the estimation information regarding the phase shift amount given from the trend generation unit 44, the GPS phase information from the GPS phase information generation unit 26 and the line from the line phase information generation unit 28 are used. When both of the phase information cannot be obtained, phase correction information is generated based on the estimation information. In another example, when the number of GPS satellites captured decreases and the reliability of the GPS phase information decreases, the phase correction data generation unit 40 uses the GPS phase information, the line phase information, and the estimation information in a complementary manner. Generate correction information. For example, in this case, the phase correction data generation unit 40 generates phase correction information based on the average value of the information, or when any one of the information shows a significant difference from the other two, A process may be performed in which one piece of information is determined to be abnormal and phase correction information is generated using the remaining two pieces. Further, when the GPS phase information cannot be obtained, the phase correction information can be generated based on the line phase information and the estimation information.

[Embodiment 2]
A block diagram showing a schematic configuration of a mobile communication base station according to the second embodiment of the present invention is the same as FIG. 1 shown in the first embodiment, and this is incorporated herein.

  FIG. 5 is a block diagram showing a schematic configuration for generating a reference clock in the present embodiment. In the figure, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the present embodiment, the control unit 12 includes an oscillator 20, a frequency divider 22, a temperature compensation information storage unit 24, and a temperature compensation information generation unit 50 as a configuration for generating a reference clock.

  In the present embodiment, the GPS phase information generated by the GPS phase information generation unit 26 and the line phase information generated by the line phase information generation unit 28 are respectively input to the oscillator 20 as phase correction information. The GPS phase information is also input to the temperature compensation information generation unit 50. The temperature compensation information generation unit 50 stores the GPS phase information and the temperature measurement value from the temperature sensor 10 in association with each other. The temperature compensation information generation unit 50 generates a new temperature compensation characteristic of the oscillator 20 based on the relationship between the temperature and the phase shift amount thus obtained, and the temperature compensation characteristic stored in the temperature compensation information storage unit 24. Update.

It is a block diagram which shows the structure of the outline of the mobile communication base station which concerns on this invention. It is a block diagram which shows the schematic structure which produces | generates a reference clock in 1st Embodiment. It is a block diagram which shows the schematic structure of a phase trend data generation part. It is a schematic diagram which shows an example of the phase change transition information over one day. It is a block diagram which shows the schematic structure which produces | generates a reference clock in 2nd Embodiment.

Explanation of symbols

  2 mobile communication base station, 4 wireless communication unit, 6 wired communication unit, 8 GPS receiving unit, 10 temperature sensor, 12 control unit, 14 antenna, 16 network, 20 oscillator, 22 frequency divider, 24 temperature compensation information storage unit , 26 GPS phase information generation unit, 28 line phase information generation unit, 30 phase trend data generation unit, 40 phase correction data generation unit, 42 phase change transition storage unit, 44 trend generation unit, 50 temperature compensation information generation unit.

Claims (7)

Synchronization signal generating means for generating synchronization signals for synchronizing base stations, compensation information storing means for storing temperature compensation information for the synchronization signal generating means, and controlling the synchronization signal generating means based on the temperature compensation information In a mobile communication base station comprising phase shift compensation means for compensating for the phase shift of the synchronization signal according to temperature,
GPS receiving means for receiving time signals from GPS satellites constituting the global positioning system;
A phase shift detection means for detecting a phase shift amount of the synchronization signal based on the time signal;
A temperature sensor for measuring the temperature of the communication base station;
Compensation information update means for generating new temperature compensation information based on the measured values of the temperature and the phase shift amount, and updating the temperature compensation information stored in the compensation information storage means;
A mobile communication base station characterized by comprising: In a mobile communication base station comprising synchronization signal generating means for generating a synchronization signal for synchronizing base stations with each other, and phase shift compensation means for controlling the synchronization signal generating means and compensating for the phase shift of the synchronization signal,
GPS receiving means for receiving time signals from GPS satellites constituting the global positioning system;
A phase shift detection unit that detects a phase shift amount of the synchronization signal compensated by the phase shift compensation unit based on the time signal;
Change transition storage means for storing phase change transition information representing a temporal transition of the detected phase shift amount;
A phase shift estimation means for estimating the phase shift amount based on the phase change transition information when the phase shift amount is not detected;
A mobile communication base station characterized by comprising: In the mobile communication base station according to claim 2,
The phase change transition information represents a temporal transition of the phase shift amount over one day;
A mobile communication base station. In the mobile communication base station according to claim 3,
It has a temperature sensor that measures the temperature of the communication base station,
The change transition storage means stores the phase change transition information for a plurality of days together with the temperature at each time,
The phase shift estimation means selects one of the plurality of phase change transition information based on the current time and temperature and uses it for estimation,
A mobile communication base station. In the mobile communication base station according to any one of claims 2 to 4,
The change transition storage means stores the phase change transition information of a plurality of seasons;
A mobile communication base station. A phase shift compensation method for compensating for a phase shift of a synchronization signal that synchronizes base stations with each other in a mobile communication base station,
A GPS receiving step for receiving a time signal from GPS satellites constituting the global positioning system;
A phase shift detection step for detecting a phase shift amount of the synchronization signal based on the time signal;
A phase shift compensation step for compensating for the phase shift of the synchronization signal using the detected phase shift amount;
A temperature measuring step for measuring the temperature of the communication base station;
Regarding temperature compensation information about the synchronization signal generating means for generating the synchronization signal, new temperature compensation information is generated based on the measured values of the temperature and the phase shift amount, and the temperature compensation information currently stored is updated. A compensation information update step,
Have
The phase shift compensation step includes:
Estimating the phase shift amount based on the temperature compensation information when the phase shift amount is not detected, and compensating the phase shift of the synchronization signal using the estimated phase shift amount;
A phase shift compensation method characterized by the above. A phase shift compensation method for compensating for a phase shift of a synchronization signal that synchronizes base stations with each other in a mobile communication base station,
A GPS receiving step for receiving a time signal from GPS satellites constituting the global positioning system;
A phase shift detection step for detecting a phase shift amount of the synchronization signal based on the time signal;
A phase shift compensation step for compensating for the phase shift of the synchronization signal using the detected phase shift amount;
A change transition storing step for storing phase change transition information representing a temporal transition of the detected phase shift amount;
Have
The phase shift compensation step includes:
When the phase shift amount is not detected, estimating the phase shift amount based on the phase change transition information, and compensating the phase shift of the synchronization signal using the estimated phase shift amount;
A phase shift compensation method characterized by the above.

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