JPH0350921A - Switching system for site diversity - Google Patents

Abstract

PURPOSE:To attain the changeover of a reference station without hit of a data by detecting a phase difference between frames with a changeover switch so as to absorb the phase difference of a reception data from two reference stations for the reception. CONSTITUTION:Reference stations 1, 2 generate multi-frame patterns 10, 20 synchronously with a receiver side frame timing of a satellite 4 respectively and multiplexes them on a data received from the satellite 4 and sends the result to a changeover switch 3. The switch 3 extracts both the patterns 10, 20 to detect an inter-frame phase difference and the phase difference of the reception data from both the stations 1, 2 with an absorption section 3a for the reception. Moreover, as to a phase difference of a transmission route, the switch 3 multiplexes the multi-frame pattern 30 onto the transmission data synchronously with the sender side frame timing of the satellite 4 and sends the result to the stations 1, 2. The stations 1, 2 extract the pattern 30 to extract the inter-frame phase difference of the both. The phase difference of the transmission data to both the stations 1, 2 is absorbed by an absorption section 3b and sends the result corresponding to the phase difference.

Description

[Detailed Description of the Invention] [Summary] Regarding a method of switching between a site diversity working reference station and a geographically separated standby reference station using a switching device, transmission delays due to geographical differences in the reference stations can be absorbed and transmission delays at the time of switching can be improved. The aim is to match the frame timing phase of each reference station by outputting a multi-frame pattern as a test pattern from each working/backup reference station using the frame timing of each reference station, and switching the reception route using a switching device. The phase difference obtained by subtracting the phase difference absorption of the reception route from the phase difference obtained by sending a multi-frame pattern for transmission on the route of switching device → each reference station → switching device is calculated as the transmission route. It is configured so that it is absorbed as a phase difference.

[Industrial application field]

The present invention relates to a site diversity switching system, and more particularly to a system for switching between a site diversity working reference station and a geographically distant standby reference station using a switching device.

In a TDMA system where a reference (base) station centrally manages the synchronization control of slave stations and line settings, the reference station is divided into two geographically separated working and standby stations to reduce the probability of synchronization reference loss due to rain attenuation, etc. Site diversity is configured at the station.

In such cases, when the reference station handles traffic data, the transmission/reception bus of the reference station that is operating as the main station among the two stations is usually selected, but instantaneous data interruption must be taken into consideration when switching between the working and backup paths. There is a need to.

[Prior art] Figure 5 shows an active reference station 1 with a site diversity configuration.
This shows a general system configuration in which a switching device 3 controls switching between this reference station 1 and a geographically distant standby reference station 2. In this example, the reference station 1 and the switching device 3 are located in the same station building. The reference station 1 or 2 communicates with a slave station via a communication satellite 4, and a carrier device 5 is provided between the reference station 2 and the switching device 3 as usual.

In communication between the reference station 1 or 2 and the slave station via the satellite 4, one satellite frame (data burst) is divided into n frames and sent to the reference station 1 or 2 on the ground, as shown in Figure 6. conversely, n frames of data are multiplexed and transmitted from the ground reference station 1 or 2 to the satellite 4.
will be a received data burst.

Then, the received data from the switching device 3 near the center 6 is constantly monitored, and if a failure is detected, a control signal is given to the selectors 31 and 32 of the switching device 3, and the selector 31 selects the reference station at the time of reception. A selector 32 selects a reference station during transmission.

[Problem that the invention sought to solve]

However, in such a site diversity switching method, the reference station 1. ! :2 are geographically distant, and the intervening carrier device 5 or the like causes the reference station frame relative to the satellite frame to shift by several frames both during transmission and reception through the switching device 3.

In addition, as shown in Figure 7, the phase of the satellite frame timing of both reference stations also changes depending on the position of the satellite, etc.
The above-mentioned frame shift is not constant; in other words, the satellite frame is determined when synchronization is achieved, so it may shift by several frames depending on the position of the satellite at that time.

For this reason, if an attempt is made to switch to the reference station 2 when the active reference station 1 fails, there is a problem in that an instantaneous interruption of traffic data occurs at the time of switching.

Therefore, an object of the present invention is to provide a site diversity switching method that can absorb transmission delays due to geographical differences in reference stations and match frame timing phases at the time of switching.

[Means and operations for solving the problem] In order to solve the above problem, in the site diversity switching system according to the present invention, as shown in principle in FIG.
Then, each multi-frame pattern (
Generating section) 10.20 is generated, multiplexed with the actual received data from the satellite 4, and sent to the switching device 3.

In the switching device 3, both multi-frame patterns 10.20
is extracted to detect the inter-frame phase difference, that is, the phase difference of the reception route, and corresponding to the phase difference, the absorber 3a absorbs and receives the phase difference between the received data from both reference stations 1.2.

Thereby, switching when receiving data from the satellite 4 can be performed without instantaneous data interruption.

Regarding the phase difference of the transmission route, the multi-frame pattern as a test pattern from the multi-frame generation unit 30 of the switching device 3 is sent to the reference station 1.2, and after making a U-turn, the switching device 3 determines the position between the two. It can be found by subtracting the phase difference of the receiving route from the phase difference.

Therefore, the switching device 3 multiplexes the multi-frame pattern 30 into the actual transmission data in synchronization with the frame timing on the transmitting side of the satellite 4, and sends it to the reference stations 1.2.
2, the multi-frame pattern 30 is extracted and sent back to the switching device 3.

Then, the switching device 3 extracts the multi-frame pattern (generating section) 30 from the reference station L2 and detects the inter-frame phase difference between them. At this time, since the receiving phase difference has already been absorbed by the absorber 3a as described above, the phase difference corresponds to the phase difference of the transmission route.

Therefore, if the absorber 3b absorbs the phase difference between the data transmitted to both reference stations 1.2 and transmits data corresponding to this phase difference, it is possible to eliminate instantaneous data interruption due to switching at the satellite.

〔Example〕

FIG. 2 shows an embodiment of the site diversity switching system according to the present invention. In this embodiment, a selector 31 of the switching device 3, a receiving side phase difference absorption buffer 33, and a selector 34 are shown. and the receiving side phase difference detection section 3
5 and the transmission side phase difference detection section 36 constitute the phase difference absorption section 3a shown in FIG. 1, and the transmission side phase difference absorption buffer 37
, the selector 38, and the data synthesis section 39.40.
It constitutes the phase difference absorption section 3b shown in the figure.

Further, the reference stations 1.2 have the same configuration, and only the configuration of the reference station 1 is shown in FIG. 2 for convenience. However, in this embodiment, the transmitting side is ), a compression buffer 12 that compresses the transmission data from the switching device 3 using this conversion table 11, a conversion register 13 for detecting the phase difference of the transmission route, and a compression buffer for detecting the phase difference of the transmission route. 14, and the reception side includes a multi-frame generation unit 10 for detecting the phase difference of the reception route, and a reception data DB→CH
Separate conversion table 15, decompression valve 16, conversion register 17 for detecting the phase difference of the receiving route, decompression buffer 18 for detecting the phase difference of the receiving route, and buffer 16.18.
．． 10 data synthesis sections 19. FB is a frame switching buffer, which is used to transfer data from frame timing on the transmitting side to frame timing on the receiving side. Although not shown in Figure 2, the frame timing on the ground (8KTMC) and the satellite 4
receive side frame timing (RBKT), and satellite 4
It is assumed that the transmitting side frame timings (TBKT) of 2 and 3 are generated as shown in FIG.

Next, in the embodiment shown in Fig. 2, the phase difference absorption of the reception route is first performed, and this is used to further absorb the phase difference of the transmission route, and each will be explained separately. .

- Route position 3 In order to obtain the phase difference of the received data from the reference stations 1 and 2 to the switching device 3, each of the reference stations 1.2 is provided with a multi-frame generation unit 10.20 for detecting the reception route phase difference,
The multi-frame patterns generated from each generation section 10.20 are sent as test patterns to the data synthesis section 19 (the same synthesis section 19 is included in the reference station 2).

This multi-frame pattern is generated in synchronization with the frame timing RBKT on the receiving side of each station.
It is possible to set all "1°" to the frame that matches , and set all "0" to the other frames.

On the other hand, the received data from the satellite 4 is manually inputted to the decompression buffer I6, and the separated received data is sent to the data synthesis section 19 with reference to the separation table 5.

At this time, since the output of the decompression buffer 18 for detecting the transmission route phase difference is not generated, the data synthesis section 19 outputs the received data in the form of a multi-frame inserted, as shown in FIG.

The output of each data synthesis section 19 of the reference station 1.2 is transferred to the switching device 3.
The signal is sent to the reception route phase difference detection section 35, where each multi-frame pattern is extracted and the phase difference between them is detected.

When this phase difference detection signal is sent to the selector 34, the selector 34 selects only the detected phase difference from the reception route phase difference absorption buffer 33 consisting of a plurality of buffers.
Since the output from the buffer that delays the output of the data synthesis unit 19 is selected and sent to the selector 31, the reference station 1-2
It is possible to absorb the phase difference between the receiving routes.

Therefore, even if a switching control signal is applied to the selector 31 and switching is performed, data continuity can be maintained.

The phase difference of one route (see 4): The phase difference of the transmission route is determined by sending a multi-frame pattern as a test pattern from the multi-frame generation unit 30 of the switching device 3 to the reference station 1.2, making a U-turn, and switching. The phase difference between the two is determined by the device 3, and by subtracting the phase difference of the reception route from this, the phase difference of the transmission route can be determined.

For this reason, first, the multi-frame pattern is combined with the transmission data in the data combining sections 39 and 40.

The multi-frame pattern on the transmitting side may be similar to the multi-frame pattern on the receiving side described above, but a free run may be used without cuing the multi-frames. Also, initially, the selector 38 is set to select the output of a predetermined buffer (for example, the buffer with the smallest amount of phase difference delay) among the plurality of buffers included in the phase difference absorption buffer 37.

The data outputted from the data synthesis units 39 and 40 in this manner is provided to the compression buffers 12 of the reference stations 1 and 2, respectively, and the compression buffers 12 multiplex the data by referring to the multiplexing conversion table 11 and perform the desired processing. It performs a compression operation and transmits the data to the satellite 4. In addition, reference station 1.
The transmitted data from Satellite 2 is both given to Satellite 4, and the reference station is switched as appropriate on Satellite 4. However, in this case, since the time slots are different due to TDMA communication, data will not collide with each other when received on Satellite 4. None. Furthermore, the multi-frame pattern is removed from the output data of the compression buffer 12.

On the other hand, the transmission data including the multi-frame pattern is also sent to the compression buffer 14 which operates at exactly the same timing as the compression buffer 12, and is sent to the conversion register 13 for phase difference detection.
In this case, the register 13 plays the same role as the conversion table 11, but the fixed channel and data stream I- into which the multi-frame pattern is inserted are D
Since it is sufficient to have a relationship with B, a register is simply used.

The transmission data compressed in this way is transferred to the frame timing of the receiving side by the frame transfer buffer FB, which operates at the same timing as the decompression buffer 16, and sent to the decompression buffer 18. The decompression buffer 18 decompresses the compressed data output from the buffer FB and restores it to its original state.
At step 9, the received data in the buffer 16 and the multi-frame pattern from the buffer 18 are combined and output.

Incidentally, at this time, since the phase difference absorption operation of the reception route has already been completed, the multi-frame generation section 10 has not generated a multi-frame pattern.

The output data from each data synthesis unit 19 of the reference stations 1 and 2 are both sent to the switching bag M3, but among these, the output data of the reference station 1 located at the same place as the switching device 3 is already sent to the above-mentioned reception route. The second phase difference absorption operation causes the selector 3 to
The received signal is delayed by one buffer in the reception route phase difference absorption buffer 33 selected by No. 4, and is sent to the selector 31 together with the output data of the reference station 2 which is not delayed at all.

These two data are also sent to the transmission route phase difference detection unit 36, where the phase difference (this is only the phase difference of the transmission route since the phase difference of the reception route has already been removed) is detected, and the selector By selecting the third day, the output of a desired one of the transmission route phase difference absorption buffers 37 is selected.

Therefore, from the data synthesis units 39 and 40, the reference station 1
．． There is no phase difference in the transmission data sent to the satellite 2, and even if switching is performed at the satellite 4, there will be no instantaneous data interruption.

Note that the pattern can be sent at any time, regardless of whether it is on the sending or receiving side, and even in this case, no signal collision occurs.
The phase difference absorption on the transmitting side should be carried out after the receiving side has finished (,
It is more preferable to constantly monitor whether the phases of both patterns are matched.

Also, the phase difference absorption of the transmission route does not include the phase difference of the aerial route from the reference station 1.2 to the satellite 4, but since this is already known, the compression buffer 12 of the reference station 1.2 When compressing the signal, the phase difference is taken into account and transmitted, so that the signal is absorbed.

Further, in the above embodiment, the reference station 1 (currently used) and the switching device 3 are provided in the same station building, but the present invention is not limited to this, and the reference station 2 (currently used) and the switching device 3 may be provided in the same building. .

〔Effect of the invention〕

As described above, according to the site diversity switching method according to the present invention, a multi-frame pattern as a test pattern is output from each working/backup reference station using the frame timing of each reference station, and the switching device selects the reception route. The phase difference obtained by subtracting the phase difference absorption of the reception route from the phase difference obtained by performing phase difference absorption and sending a multi-frame pattern for transmission on the route of switching device → each reference station → switching device is calculated as the phase difference of the transmission route. Since it is configured to absorb the phase difference, the reference station can be switched without instantaneous data interruption, and this phase difference absorption/switching operation can be performed during normal transmission/reception operations without a special test period. This eliminates the need for data loss and retransmission operations.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the site diversity switching method according to the present invention, FIG. 2 is a block diagram showing an embodiment of the switching device and reference station of the site diversity switching method according to the present invention, and FIG. is a time chart diagram showing the phase difference absorption operation of the reception route according to the method of the present invention, FIG. 4 is a time chart diagram showing the phase difference absorption operation of the transmission route according to the method of the present invention, and FIG. FIG. 6 is a configuration block diagram of the diversity switching method; FIG. 6 is a diagram showing the relationship between satellite frames and terrestrial frames; FIG. 7 is a diagram showing frame timing phases. In FIG. 1, 1.2... Reference station, 3... Switching device, 4... Satellite, l0120.3σ... Multi-frame pattern generation section, 3a, 3b... Phase difference absorption section. In the figures, the same reference numerals indicate the same or corresponding parts. agent

Claims (2)

[Claims] (1) In a method of switching between a site diversity working reference station (1) and a geographically distant backup reference station (2) using a switching device (3), each reference station (1) (2) is connected to a satellite (4). The multi-frame pattern is multiplexed with actual received data in synchronization with the frame timing on the receiving side and sent to the switching device (3), and the switching device (3) extracts the multi-frame pattern and calculates the inter-frame phase difference. Both reference stations (
1) A site diversity switching system characterized in that reception is performed by absorbing the phase difference of the received data from (2). (2) In a method in which a switching device (3) switches between a site diversity working reference station (1) and a geographically distant standby reference station (2), the switching device (3) is on the transmitting side of the satellite (4). The multi-frame pattern is multiplexed into actual transmission data in synchronization with the frame timing and sent to each reference station (1) (2), and each reference station (1) (2) extracts the multi-frame pattern and extracts the multi-frame pattern from the switching device. (3), the switching device (3) extracts the multi-frame pattern, detects the inter-frame phase difference after absorbing the received phase difference, and switches between both reference stations (1) in response to the phase difference. ) (2) The transmission data is transmitted by absorbing the phase difference of the data to be transmitted.
Site diversity switching method described.