JP3088345B2 - Phase synchronization error correction method and phase synchronization error correction system in telecommunications - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and system for correcting a phase synchronization error in telecommunications employing a TDMA (time division multiple access) system, and more particularly to a phase synchronization method capable of improving transmission efficiency and effectively utilizing frequency. The present invention relates to an error correction method and system.

[0002]

2. Description of the Related Art Conventionally, a method and a system for correcting a phase synchronization error in telecommunications employing a TDMA system include:
As in a terrestrial communication network such as a cellular network, the service area is several hundred meters to several kilometers, and the guard time required to absorb the distance deviation and the distance fluctuation between the transmitter and the receiver is determined by the frame length. On the other hand, it is small enough. Therefore, the phase error of the timing signal generated by the distance deviation and the distance variation is absorbed by the guard time.

[0003] That is, a terminal station such as a mobile station synchronizes phase with a reference timing signal transmitted from a base station serving as a reference station, and the extracted timing signal, for example, guards an average delay time in a service area. Communication is performed with a fixed correction corresponding to the center of time.

[0004]

The above-described conventional method and system for correcting phase synchronization error in telecommunications have the problem that the amount of information that can be transmitted is reduced or the required frequency resources are increased. .

[0005] The reason is that when the diameter of a service area using a communication satellite extends over 100 km, when the phase error is absorbed only by the guard time, the length of the guard time is reduced to the frame length. This is because the ratio occupies a relatively large ratio with respect to the transmission ratio.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and system for correcting a phase synchronization error in telecommunications, which can solve the above-mentioned problems and improve transmission efficiency or make effective use of frequency.

[0007]

According to a first aspect of the present invention, there is provided a phase synchronization error correcting method for remote communication according to the present invention.
In a phase synchronization error correction method in remote communication employing a DMA (time division multiple access) method, a reference station is set to a communication satellite.
The terminal station is a ground station, and the communication satellite and the ground
At least one of the stations is illuminated by the communications satellite on the earth.
To each ground station
The distance being reported, as well as a small
At least the location information of communication satellites and ground stations is
Based on the position information obtained from the satellite system
Distance information including one of the distances estimated
Has the ground station in advance, the ground station, when initial synchronization timing for said TDMA communication, receives the reference timing of built this communication satellite from the communication satellite <br/>, reference timing and received The output timing is coarsely corrected according to the distance information, and the coarsely corrected output timing is burst-output in a predetermined format.
The communication satellite detects the coarsely corrected output timing from the received predetermined format, compares the output timing with a built-in reference timing, detects a difference as error information, and outputs the detected error information to the terminal station. , And the ground station receives the error information, and finely corrects the output timing based on the received error information.

One of the concrete means is to communicate with a reference station.
Satellites and terminal stations can be used as ground stations, and approximate distance information can be derived.
The location information of at least one of the
A satellite system for sending information to the ground station
In the star, a reference timing signal generator for generating a reference timing, a timing signal detector for detecting a timing signal from an information signal received in a burst form from the ground station, and a timing signal detected by the timing signal detector. An error detection unit that detects and outputs error information by comparing with a reference timing generated from the reference timing generation unit, the ground station includes an initial synchronization start instruction unit that instructs start of initial synchronization of output timing, When the start of the initial synchronization is instructed from the initial synchronization start instructing unit, the communication
A reference timing detecting section for detecting the reference timing received from the satellite, and the error information detecting unit for detecting the error information received from the communication satellite, the reference timing and the error information detecting unit detected by the reference timing detecting section A phase correction unit for correcting the phase of the reference timing of the self- ground station based on at least one of the detected error information ; and each beam emitted from the communication satellite onto the earth.
That is measured up to the center position and notified to each ground station
And the distance received from the satellite system
Approximately based on the position information obtained by detecting the position information
Output to the communication satellite based on a distance estimation information unit that stores at least one of the calculated distances as an estimated distance to the communication satellite in advance, and correction information by the phase correction unit and estimated distance information of the distance estimation information unit. A timing packet generator for roughly correcting the timing to generate and output a packet for detecting a phase synchronization error.

[0009]

[0010]

According to a second aspect of the present invention, a ground station is provided based on the output timing precisely corrected by the initial synchronization.
Communication satellites der which has received the information signal output from that terminal station
The reference station detects a timing signal from the received information signal, compares the detected timing signal with a built-in reference timing, determines error information detected as a difference according to a predetermined allowable error range, and determines the allowable error. If it exceeds the range, send the correction required information to the terminal station,
The terminal station performs the procedure for the initial synchronization based on the reference timing received from the reference station when receiving the correction required information.

This specific means is provided when the reference station further receives the error information output from the error detecting section and compares the error information with a preset error allowable range to determine whether the error is outside the error allowable range. A correction required determining unit for transmitting correction information addressed to the terminal station; and the terminal station further detects the required correction information received from the reference station and drives the initial synchronization start instruction unit. An information detection unit is provided.

According to this method or configuration, the terminal station
During the initial synchronization, first perform the coarse correction, and then
After which it is possible to form a feedback loop that can be appropriately correcting the phase errors caused by the distance between the reference station and the terminal station as the satellite communication varies in telecommunications.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a functional block diagram showing an embodiment of the present invention. FIG. 1 shows only the main parts related to the present invention.

In the phase synchronization error correction system in remote communication shown in FIG. 1, TDMA applied to satellite communication is used.
Based on the method, the communication satellite 1 of the reference station includes a reference timing signal generation unit 11, a timing signal detection unit 12, an error detection unit 13, a required correction determination unit 14, a signal reception unit 15, and a signal formation transmission unit 16, , The ground station 2 of a plurality of terminal stations provided for the reference station,
1, reference timing detection unit 22, error information detection unit 23,
Phase correction section 24, distance estimation information section 25, timing packet generation section 26, correction information required detection section 27, signal formation transmission section 28, signal reception section 29, and position information section 30
Shall be provided.

The reference timing signal generator 11 generates a reference timing signal in the system and sends it to the error detector 13 and the signal generator / sender 16.

The timing signal detector 12 detects a packet signal received from the ground station 2 via the signal receiver 15, extracts a timing signal from the packet signal, and sends it to the error detector 13.

The error detection unit 13 compares the reference timing generated by the reference timing signal generation unit 11 with the timing signal of the ground station extracted by the timing signal detection unit 12, and determines the phase error signal as error information to determine whether correction is necessary. It is to be sent to the section 14 and the signal formation sending section 16.

The required correction judging section 14 has an allowable range of the phase error signal received from the error detecting section 13 in advance, and if the phase error signal is out of the allowable range from the received error information, outputs the necessary correction information to the signal forming and transmitting section. 16 shall be sent.

The signal receiving section 15 sends a packet signal obtained by demodulating a burst signal received from the ground station 2 to the timing signal detecting section 12 and also to an information processing section (not shown). It is assumed that the information processing section detects the received information signal and performs a process related to a predetermined communication.

The signal forming / sending unit 16 broadcasts the reference timing signal received from the reference timing signal generating unit 11 to the ground station 2 at a predetermined time as a reference timing, and transmits the error information received from the error detecting unit 13 and the correction required judgment. Part 14
Each of the necessary correction information received from the base station is formed into a signal and transmitted to the ground station.

The initial synchronization start instructing section 21 sets the start of the initial synchronization at the time of initial phase synchronization and when driven by the correction information detection section 27, and sets a reference timing detection section 22.
Shall be driven.

The reference timing detecting section 22 detects the reference timing received at a predetermined time from the communication satellite 1 via the signal receiving section 29 when receiving the drive from the initial synchronization start instructing section 21 and sends it to the phase correcting section 24. Shall be.

The error information detector 23 detects error information received from the communication satellite 1 via the signal receiver 29 and sends it to the phase corrector 24.

The phase correction unit 24 first receives the reference timing of the communication satellite 1 detected by the reference timing detection unit 22 at the time of initial synchronization, generates a reference timing signal in the ground station 2 based on the reference timing, and generates a timing packet. It is sent to the generation unit 26, and then the direction of phase advance or delay and the amount of correction are converted based on the error information received when the error information detected by the error information detection unit 23 is received. It is assumed that the reference timing signal is finely corrected and used inside the ground station 2. Therefore, the transmission timing of the information packet transmitted to the communication satellite 1 is stable with high accuracy based on the timing finely corrected by the phase correction unit 24.

It is assumed that the distance estimation information section 25 previously stores distance information between the communication satellite 1 serving as a reference station and the ground station 2 and is read by the timing packet generation section 26. On the other hand, although not shown, a means for extracting information received from the satellite at the ground station is provided, and the above-described distance information is determined based on distance information extracted from a signal transmitted by the satellite, The calculation may be performed based on the in-range beam information extracted from the information transmitted from the satellite and the distance information stored in advance.

The timing packet generator 26 receives a rough timing based on the reference timing signal generated by the ground station 2 received from the phase corrector 24 and the approximate distance read out from the distance approximate information 25 when instructing the start of the initial synchronization. It is assumed that a packet signal for phase error detection based on the corrected timing is generated and transmitted to the communication satellite 1 via the signal forming and transmitting unit 28.

When the necessary correction information detecting section 27 detects the necessary correction information received from the communication satellite 1 via the signal receiving section 29, it drives the initial synchronization start instructing section 21.

The signal forming and transmitting section 28 forms a packet for phase error detection and a packet of information data output from the timing packet generating section 26 into a packet signal, and bursts to the communication satellite 1 in a set time zone. Shall be sent.

The signal accepting section 29 demodulates a signal received from the communication satellite 1 of the reference station and demodulates the reference timing detecting section 22, the error information detecting section 23, the correction required information detecting section 27, and the information (not shown). It is assumed that the packet is sent to an information processing unit that detects and processes the packet.

The position information section 30 detects and outputs geographic information and position information received from another satellite system, for example, a GPS (Global Positioning System) satellite, and outputs the distance estimation information section 25 with the position information. It is provided when distance information is determined based on output information of the unit 30.

Next, a main operation procedure according to the present invention in a communication satellite will be described with reference to FIG. 1 and FIG.

First, in FIG. 2 (A), in the communication satellite 1, the reference timing signal generated by the reference timing signal generator 11 is transmitted to a plurality of ground stations serving as terminal stations by the signal forming / transmitting unit 16 at a predetermined time. On the other hand, it is transmitted by broadcast notification (procedure 101).

The timing signal detector 12 detects a timing packet signal for phase synchronization error detection received via the signal receiver 15, and extracts a timing signal from the timing packet signal (step 102). The extracted timing signal is roughly corrected by the reference timing signal of the communication satellite 1 and transmitted from the ground station 2, and is sent to the error detection unit 13 for detecting a phase synchronization error.

The error detector 13 detects the phase synchronization error by comparing the timing of the received timing signal with the timing of the reference timing signal generated by the reference timing signal generator 11 (step 103), and detects the detected timing error. Is transmitted as error information to the source ground station 2 of the timing packet signal for detecting the phase synchronization error via the signal forming / transmitting unit 16 (step 104).

The ground station 2 finely corrects the reference timing of the ground station 2 based on the received error information, and sends out an information signal to the communication satellite 1 at a stable timing.

In FIG. 2B, the timing signal detecting section 12 receives the packet signal of the information signal at the timing precisely corrected from the ground station 2 via the signal receiving section 15 and detects it. A timing signal is extracted from the packet signal (procedure 111) and sent to the error detection unit 13. The error detection unit 13 detects a phase synchronization error by comparing the timing of the timing signal from the timing signal detection unit 12 with the reference timing signal of the reference timing signal generation unit 11, and determines the detected timing error as a correction required determination unit 14. (Step 112).

The correction necessity determination unit 14 examines the received timing error (step 113), and when it detects an abnormality such as out of the allowable range which has been previously determined from the timing error (step 114, YES), the timing correction is required. The necessary correction information is transmitted to the ground station 2 that transmitted the information packet signal via the signal formation transmitting unit 16 (step 115).

If the procedure 114 is "NO" and the timing error is within the predetermined allowable range, no action is taken until an abnormality such as out of the allowable range is detected.

Next, referring to FIG. 1 and FIG. 3, the main operation procedure of the ground station according to the present invention will be described.

First, when the start of the initial synchronization is set (step 201), the initial synchronization start instructing unit 21 drives the reference timing detection unit 22. The driven reference timing detection unit 22 detects a reference timing from a signal received from the communication satellite 1 via the signal reception unit 29 (Step 20).
2), and sends the detected reference timing to the phase correction unit 24.

The phase corrector 24 corrects the reference timing of the ground station 2 based on the detected reference timing of the communication satellite 1 (step 203), and the timing packet generator 26
Send to The timing packet generator 26 roughly corrects the transmission timing to the communication satellite 1 from the timing received from the phase corrector 24 and the distance information to the communication satellite 1 previously stored in the distance estimation information unit 25 (step 204). A timing packet based on the transmission timing is generated and transmitted to the communication satellite 1 via the signal forming / transmitting unit 28 (procedure 20).
5).

As described above, the communication satellite 1 returns an error between the timing extracted from the timing packet and the reference timing of the communication satellite 1, which is the reference timing of the system, to the ground station 2 as timing error information.

In the ground station 2, the error information detecting section 23 detects timing error information from the signal received via the signal receiving section 29 (procedure 206) and sends it to the phase correcting section 24.
The phase corrector 24 finely corrects the output timing based on the received timing error information (procedure 207), and uses it for the transmission timing of the information packet signal.

As described above, the information packet signal transmitted at the output timing that has been finely corrected detects the timing error with respect to the reference timing in the communication satellite 1 and, when the error deviates from a predetermined error range, the correction information required. Is sent. Therefore, the ground station 2 requires the correction information detection unit 27
However, when this is detected (YES in step 208), the initial synchronization start instruction unit 21 is driven to set the start of the initial synchronization,
The reference timing detecting section 22 is driven to return to the above-mentioned procedure 202 for detecting the reference timing signal received from the communication satellite 1, and the procedure of the initial synchronization is restarted.

As described above, at the time of initial synchronization, a timing packet signal for detecting a phase synchronization error is generated and transmitted based on the output timing roughly corrected from the reference timing signal of the system broadcasted from the communication satellite and transmitted. The satellite receives the timing of this timing packet signal,
The error between this timing and the reference timing is reported to the source ground station, and the ground station corrects the timing again.The precise correction is performed by controlling the long-distance feedback loop between the communication satellite and the ground station. High synchronization state can be established.

Further, even after the communication is started by the information packet signal, the error between the reference timing of the system and the timing of the packet signal transmitted from the ground station is monitored, and when the timing error deviates from the allowable range. Can generate an alarm based on the correction information required, so the distance between the communication satellite and the ground station fluctuates due to high-speed movement during a long-term call, and the timing of the signal transmitted from the ground station is shifted. Also, since the fine correction can be automatically performed in the initial synchronization procedure, stable communication can always be expected.

Further, as described above, when the communication satellite multiplexes and outputs the approximate distance to the ground station, the distance estimation at the ground station can be controlled by the communication satellite. In this case, the communication satellite can control the coarse correction of the transmission timing of the ground station for each beam. Also,
According to this method, by transmitting data for correcting the distance between the communication satellite and the ground station for each beam from the communication satellite, for example, even in a scanning beam method that changes at least one of the beam width and the beam position, The ground station can know the distance from the communication satellite.

Next, specific examples of the timing signal detector 12 and the error detector 13 in FIG. 1 will be described with reference to FIG.

The timing signal detector 12 shown in FIG.
The packet is detected from the signal received from the ground station 2, a timing signal is extracted, and sent to the error detection unit 13. The packet signal received from the ground station 2 includes a preamble section, a unique word (hereinafter abbreviated as UW) section, a data section, and an error detection code section. Since the preamble unit is used for carrier detection and clock extraction in the demodulator of the signal reception unit 15, the timing signal detection unit 12 has a UW unit, a data unit,
And only the error detection code part is accepted.

The timing signal detection section 12 has a UW signal collation data pattern for detecting the head position of the packet signal, compares this pattern with the received UW section pattern, and compares the pattern with the received UW section pattern. The position is detected and this detection signal is sent to the error detection unit 13.

The error detection section 13 has a counting clock signal generation circuit 31 and an error detection circuit 32. The error detection circuit 32 has a counter 33 and a latch circuit 34. The error detection circuit 32 detects an arrival time difference by comparing the reference time of the communication satellite 1 with the arrival time of the packet signal received from the ground station 2.

In the illustrated error detection circuit 32, the counter 33 is initialized by the reference timing output from the reference timing signal generation unit 11, and then counts the clock output from the counting clock signal generation circuit 31, Next, the latch circuit 34 receives the packet arrival timing from the timing signal detector 12, stores the count value of the counter 33, and outputs it as error information.

In the above description, when the timing error from the reference timing due to the information packet signal is within the allowable range,
Although there is no action, a function of transmitting error information from the communication satellite to the ground station may be added.

As described above, the functional blocks and the procedures have been specifically illustrated in the above description. However, the distribution and merging of the functions and the movement of the procedures are free as long as the above functions are satisfied. Is not limited.

[0057]

As described above, according to the present invention, the following effects can be obtained.

The first effect is that the transmission efficiency in the communication system can be improved and the frequency can be effectively used .
Since the time required to establish the initial phase synchronization is short,
High timing can be maintained stably .

The reason is that, according to the first aspect, the phase synchronization error between the communication satellite and the ground station can be corrected with high accuracy by a feedback loop, so that the guard time between packet signals can be set small. Is possible
In addition, the reference time timing and coarse correction information for each
When outputting from a communication satellite with weighting, the beam width or
Scanning beam system that dynamically changes the beam position
Can be supported and from other systems such as GPS
When using a method to obtain geographic information,
Information such as the average delay time of each beam
In addition, the distance between the communication satellite and the ground station is accurately entered.
Because it is possible .

[0060]

[0061]

The second effect is at least as in satellite communication.
Even when one of the mobile units is a mobile unit, there is no restriction such as a restriction on a talk time and a restriction on a moving range depending on interference between slots.

The reason is that, according to the second aspect of the present invention, even if a dynamic position shift occurs during communication in a communication satellite or a ground station , that is, a reference station or a terminal station , the timing is not changed. This is because highly accurate correction can be performed in a short time when the error deviates from the allowable range.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing one embodiment of a main procedure by the communication satellite of the present invention.

FIG. 3 is a flowchart showing one embodiment of a main procedure by the ground station of the present invention.

FIG. 4 is a block diagram showing an example of a part of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Communication satellite 2 Ground station 11 Reference timing signal generation part 12 Timing signal detection part 13 Error detection part 14 Correction required judgment part 15 Signal reception part 16 Signal formation transmission part 21 Initial synchronization start instruction part 22 Reference timing detection part 23 Error information detection Unit 24 phase correction unit 25 distance estimation information unit 26 timing packet generation unit 27 required correction information detection unit 28 signal formation transmission unit 29 signal reception unit 30 position information unit 31 counting clock signal generation circuit 32 error detection circuit 33 counter 34 latch circuit

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Takeda 2-12-5 Iwamotocho, Chiyoda-ku, Tokyo Inside the Next Generation Satellite Communication and Broadcasting System Research Laboratories (72) Inventor Yoichi Kawakami Iwamoto, Chiyoda-ku, Tokyo (12) Inventor Shinichi Taira 2-12-5 Iwamotocho, Chiyoda-ku, Tokyo, Japan Next-generation Satellite Communication and Broadcasting System Laboratory (72) Inventor Seira Yoneda 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation (56) References JP-A-2-241140 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) H04B 7/14-7/26 H04J 3/00-3/06 H04L 7/00

Claims (6)

(57) [Claims] 1. A phase synchronization error correction method in telecommunications employing a TDMA (Time Division Multiple Access) method, wherein a reference station is a communication satellite and a terminal station is a ground station,
At least one of the star and the ground station has the communication satellite
Measure up to the center position of each beam irradiated on the earth
Distances owned and notified to each ground station, and approximate distances
Location information of at least communication satellites and ground stations that can guide information
From satellite systems that send broadcasts to ground stations by broadcast
One of the distances estimated based on the location information
Distance information has the ground station in advance including the ground station, the time of initial synchronization timing for TDMA communication, receives the reference timing of built this communication satellite from the communications satellite, the received reference timing and said distance output timing coarsely corrected in accordance with the information, the crude corrected output timing burst outputted by a predetermined format, then the communication satellite, detects the output timing of the coarse correction from a predetermined format received The output timing is compared with a built-in reference timing, a difference is detected as error information, the detected error information is transmitted to the terminal station, and then the ground station receives and receives the error information. Phase synchronization error correction method in telecommunications, characterized by precisely correcting output timing based on error information . Wherein Oite to claim 1, wherein the initial synchronization by fine corrected communication satellites der which has received the information signal outputted from the pre <br/> SL terminal station is a ground station on the basis of the output timing
The reference station detects a timing signal from the received information signal, compares the detected timing signal with a built-in reference timing, determines error information detected as a difference based on a predetermined allowable error range, When exceeding the allowable error range, the correction information is transmitted to the terminal station, and the terminal station, upon receiving the correction information, performs the initial synchronization based on a reference timing received from the reference station. A phase synchronization error correction method in telecommunications characterized by performing a procedure for: 3. The phase synchronization error correction method in remote communication according to claim 1, wherein the format of the burst output is a packet based on a predetermined protocol. 4. A reference station in telecommunications employing a TDMA (time division multiple access) system is a communication satellite or a terminal station.
Communication satellites and territories that can serve as supervisors and provide approximate distance information.
Broadcast at least one location information of the upper station to the ground station
A phase synchronization error correction system including a satellite system , wherein the communication satellite includes a reference timing signal generation unit that generates a reference timing, and a timing signal detection unit that detects a timing signal from an information signal received in a burst format from the ground station. And an error detection unit that detects and outputs error information by comparing a timing signal detected by the timing signal detection unit with a reference timing generated by the reference timing generation unit, wherein the ground station has an initial output timing. An initial synchronization start instruction unit for instructing the start of synchronization, a reference timing detection unit for detecting the reference timing received from the communication satellite when instructed to start the initial synchronization from the initial synchronization start instruction unit, and the communication satellite An error information detection unit for detecting the error information received from the More detected reference timing and the error information at least self-locations based on the one of the error information detected by the detecting unit
A phase correction unit for correcting the phase of the reference timing of the upper station,
Center position of each beam illuminated on the earth by the communication satellite
Was detected and what was notified to each ground station was detected.
Distance and the position information received from the satellite system
Distance estimated based on the position information obtained by detection
A distance estimate information unit for <br/> previously stored at least one of the release as an approximation distance between the communication satellite, by the approximate distance information of the correction information by the phase correction unit distance estimate information unit to said communication satellite the output timing crude corrected and a timing packet generation unit for generating and outputting a packet for phase synchronization error detection, when the initial synchronization at the ground station performs a first coarse correction followed by a feedback loop to fine correction And a phase synchronization error correction system in telecommunications. 5. The reference station according to claim 4 , wherein the reference station, which is a communication satellite , further receives error information output from the error detection unit, compares the received error information with a preset error allowable range, and determines whether the error is outside the error allowable range. In this case, a correction required determining unit for transmitting the correction required information to the terminal station, which is a ground station, is provided, and
The terminal station further includes a required correction information detecting unit that detects the required correction information received from the reference station and drives the initial synchronization start instruction unit, and is caused by a change in a distance between the reference station and the ground station. A phase synchronization error correction system in remote communication, wherein a phase error is corrected during information communication. 6. The method of claim 4 or in claim 5, a phase synchronization error correction system in a telecommunications, characterized in that format to be burst output is the packet based on a predetermined protocol.