JPH077500A - Frame synchronization method - Google Patents

Abstract

(57) [Abstract] [Purpose] Concerning a frame synchronization method between a transmitting device and a receiving device which periodically transmit and receive frames, the number of synchronization words is reduced as much as possible to improve data utilization efficiency and to quickly establish synchronization. To do. [Structure] Before synchronization is established, a transmitting apparatus inserts a plurality of synchronization words into the first frame and transmits, and the receiving apparatus detects the synchronization words to synchronize with the transmitting apparatus as if a true synchronization word was detected. The transmitting device returns to a normal frame by notifying that it has been established.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame synchronization system, and more particularly to a synchronization establishment system for digital data communication system.

In the digital data communication system and the like, it is necessary to instantly establish frame synchronization when the power is turned on and when switching channels of mobile communication.

[0003]

2. Description of the Related Art Conventionally, the most general frame synchronization method is to set a synchronization word at a predetermined position in a frame in a transmitting device and transmit it as shown in FIG. Was there.

Therefore, the synchronization is not established until the synchronization word is detected. For synchronization establishment, a plurality of frames are received and, for example, when the synchronization word is detected for two consecutive frames (backward protection). It was the first time to establish synchronization in the second stage.

Therefore, until the synchronization is established, the synchronization has not been established unless the same number of frames as the number of backward protection stages or more is received.

In order to eliminate such drawbacks, a method has been proposed in which a plurality of frame synchronization words are arranged in one frame and synchronization is established when a predetermined number or more of synchronization words are detected (Japanese Patent Laid-Open No. 55-55). -44263, 55-77252, JP-A-3-
No. 72736).

[0007]

However, in the above-mentioned various conventional examples, since a plurality of synchronization words are inserted in each frame, there is a problem that the utilization efficiency of data is deteriorated.

Therefore, according to the present invention, in a frame synchronization system between a transmitter and a receiver which periodically transmits and receives frames, the number of synchronization words is reduced as much as possible to improve data utilization efficiency and to establish synchronization quickly. With the goal.

[0009]

[Means and Actions for Solving the Problems] (1) Present Invention
(No. 1): FIG. 1 In the present invention, a plurality of synchronization words are inserted in the first frame before transmission is established in the transmission device and transmission is performed.

That is, as shown in FIG. 1, in addition to the predetermined synchronization word in one frame, a plurality of the same provisional synchronization words are inserted in the data part and transmitted.

Therefore, the receiving device receiving such a frame can detect the sync words (b) and (c) when the sync word search is started at the time point (a) in FIG. 1, and the (α + 20 + 20) bits are detected. Two sync words can be detected only by receiving the data of.

Then, a temporary sync word is detected and then a true sync word is detected. This is because if it is known in advance how many sync words can be inserted in one frame,
It is possible to find a true sync word at a position traced back by a predetermined number of sync words from the time when the sync word cannot be detected.

For example, in the case of triple TDMA communication as shown in FIG. 1, if the synchronization detection is performed from the slots among three slots corresponding to three frames existing in a predetermined bit (840 bit) period, In the slot, four sync words (b) to (e) are received after the sync word reception start time (a), and since the sync word cannot be received from the next time (f), it is received the fourth time. It can be seen that sync word (e) is the last sync word of the frame.

From this, the final position of the frame can be known,
Predetermined sync word within one frame (280 bits) from here (280/20 = 14 sync words in this case)
It can be seen that the true sync word (g) exists at the location traced back, and the true sync word can be detected from the start point (h) of the next cycle.

Then, the receiving apparatus which has detected the establishment of the synchronization in this way notifies the transmitting apparatus of the establishment of the synchronization, whereby the transmitting apparatus restores the normal frame of only the synchronization word and starts the transmission.

Therefore, synchronization can be established only by receiving the first frame.

(2) The present invention ( No. 2): FIG. 2 In the present invention, the provisional synchronization words in one frame are different from each other, and which position in the frame each corresponds to is preliminarily set by the receiving device. Send it from the transmitter so that it can be understood.

Therefore, for example, as shown in FIG. 2, a sync word (20 bits) is included in a signal of one frame (280 bits).
If there are a predetermined number (14), the true sync word is at the beginning of the frame and is set as “sync word 1”, and in order, “sync word 2”, “sync word 3”, ...
The contents of the synchronization word are set by the transmitting device so as to be "synchronization word 14", and this should be known in advance by the receiving device.

Then, in the receiving device, when the synchronization word starts to be received at the time (a) and "synchronization word 3" and "synchronization word 4" can be received, it is true that 2 * synchronization word is traced back from here. "Sync Word 1" can be found,
The sync word can be detected from the next frame.

Then, the receiving device which has detected the establishment of synchronization in this way notifies the transmitting device of the establishment of the synchronization, whereby the transmitting device restores the normal frame of only the synchronization word and starts the transmission.

(3) The present invention ( No. 3): FIG. 3 In the present invention, additional information of a predetermined number of bits is given corresponding to the positions of a plurality of synchronization words inserted in the first one frame, and is transmitted from the transmitter. .

That is, as shown in FIG. 3, the sync word at the head of the frame is set as a true sync word, and information indicating the position of the sync word of a predetermined bit (for example, 8 bits) is added to each sync word. For example, if the data immediately after the sync word at the time of establishing the synchronization is D3 (a) as shown in the figure, the true value can be obtained by going back from here by (3 x sync word) + (3 x added data). The sync word can be found and the sync word can be detected from the next frame.

Then, the receiving device which has detected the establishment of synchronization in this way notifies the transmitting device of the establishment of the synchronization, so that the transmitting device restores the normal frame of only the synchronization word and starts the transmission.

(4) Present Invention ( No. 4): FIG. 4 In the present invention, when searching for a synchronization word in TDMA communication, not only the slot (frame) addressed to the own station but also the slot addressed to another station are synchronized. It is intended to be detected.

That is, as shown in FIG. 4, not only is the synchronization word SW1 of the slot addressed to the own station detected at time (a), but the synchronization words SW2 and SW of the slots addressed to other stations are detected.
The detection of 3 is also performed at the time points (b) and (c), respectively.

Therefore, when the synchronization words more than the backward protection number can be detected in (a), (b) and (c), the synchronization is established at the time (d) of the own station addressed slot of the next cycle.

In this way, only a true synchronization word is inserted in one frame, and quick synchronization can be established without reducing the data utilization efficiency.

(5) The present invention (No. 5): FIG. 5 In the present invention, when the transmitting device interleaves and transmits the synchronization word, the synchronization word converted so that synchronization can be surely established after deinterleaving is performed. It is a multiple insertion in the frame.

This will be described with reference to FIG. 5. First, when the data shown in FIG. 5A is transmitted, one frame is composed of 21 bits from A to U, and the true synchronization word is underlined. As 3 bits of "ABC" with
When this is interleaved at a depth of "7", the data transmission order is as shown in FIG.

Since such interleaved data is transmitted as shown in FIG. 7C, the beginning of the frame cannot be known unless synchronization is established on the receiving side, and therefore the interleave is decoded at the correct position. I can't.

For example, when received as shown in FIG. 3D, "GHI", "JKL", "MNO", ...
If either "BCa" or "EFd" is a temporary synchronization word, synchronization can be established.

Therefore, in addition to the synchronization word "ABC" shown in FIG. 7B, "BCa" or "Ca" until synchronization is established.
If "b" is temporarily inserted, the sync word can be detected without fail even if deinterleaving is performed from an arbitrary position.

[0033]

Embodiments (1) Embodiment of the present invention (1): FIG. 6 In this embodiment, a receiver 1, a sync word coincidence detection unit 2 for receiving an output signal of the receiver 1, and a sync word coincidence detection The pulse detection unit 3 receives the coincidence detection signal of the unit 2 and the counter 4 that counts the output signal of the pulse detection unit 3 and controls the synchronous word coincidence detection unit 2 and the data processing unit 5.

In the operation of this embodiment, before the synchronization is established, the received signal (1) from the receiver 1 is input bit by bit to the sync word coincidence detection section 2 as shown in FIG. 20-bit sync word and pattern match detection are performed.

As a result, when the pattern matching is detected, the matching detection pulse (2) is output to the pulse detecting section 3. Once the sync word is detected, the sync word is continuously received as shown in FIG.
It is output every 0 bits.

When the sync word is no longer detected at the time point (f) after the sync words (b) to (e) are detected, the time point traced back by the predetermined sync word number in one frame as described with reference to FIG. Since (g) can be detected as a true synchronization word, the synchronization is established, and the pulse detection unit 3 outputs the synchronization establishment signal (3) to the counter 4.

After the synchronization is established in this way, 560 bits after this point (slot and after the lapse of slots)
To receive a normal signal format (a format composed of one 20-bit sync word and data).

Since the synchronization word comes in a period of 840 bits after 560 bits (point (h) in FIG. 1), the counter 4
In accordance with the control signal (4), synchronization detection is performed in this portion, and the data processing unit 5 also performs processing in accordance with this synchronization detection.

(2) Embodiment of the present invention ( No. 2): FIG. 7 In this embodiment, the received signal (1) from the receiver 1 is input bit by bit to the sync word coincidence detection unit and is shown in FIG. As described above, pattern matching detection is performed with all 20-bit synchronization words 1 to 14. In this case, the synchronization word match detection unit 2
2 provides all the sync word patterns of the sync words 1 to 14 shown in FIG. 2, and the content of each of these sync words indicates the position of the sync word in one frame.

Therefore, when any one of the sync words is found to match, the sync word match detector 2 outputs the match detection pulse (2) and the matched pattern identification signal (5).

Before the establishment of synchronization, once the synchronization word is detected, the synchronization word is continuously obtained. Therefore, the coincidence detection pulse (2) is detected every 20 bits, and when the number of backward protection stages is 2, When the coincidence detection pulse (2) is received twice consecutively, the pulse detection unit 3 outputs the synchronization establishment signal (3), and recognizes the number of the synchronization word based on the pattern identification signal (5) at this time, The position of the true synchronization word 1 is detected and the synchronization is established.

After the synchronization is established, the normal format starts to be received. Therefore, the true sync word position operation unit 6 periodically detects only the part where the true sync word 1 exists by the control signal (6). The data processing unit 5 controls so as to perform the data processing according to the control.

(3) Embodiment of the present invention (Part 3): FIG. 8 In this embodiment, in addition to the embodiment of FIG.
And the ON / OFF switch 8 are provided, and the switch 8 is configured to close when the coincidence detection pulse (2) is received twice in succession when the pulse detection unit 3 has two rear protection stages. As a result, the output signal (1) of the receiver 1 is given to the detection unit 7.

The detecting section 7 detects any of the additional information D1 to D10 of each sync word shown in FIG. 3, and gives the detection result (7) to the calculating section 6.

The calculation unit 6 determines that the synchronization word detected as a match is 1
Since the number of the synchronization word in the frame is shown, the synchronization signal is given to the coincidence detection unit 2 by the control signal (6) so that only the portion where the true synchronization word 1 exists is periodically performed. The data processing unit 5 also performs data processing according to this.

(4) Embodiment of the present invention (4): FIG. 9 This embodiment has basically the same configuration as the embodiment shown in FIG. 7, but is different from the embodiment of FIG. As shown in FIG. 4, the word coincidence detection unit 2 detects not only the synchronization word SW1 in the slot of its own station but also the synchronization words SW2 and SW3 in the slots of other stations. When this coincidence detection is performed, the pulse detection unit 3 and the arithmetic unit 6 establish similar synchronization, and the data processing unit 5 performs data processing.

The other operations are similar to those of the embodiment shown in FIG.

(5) Embodiment of the present invention (5): FIGS.
11 In this embodiment, in addition to the embodiments of FIGS. 7 and 9, a deinterleaver 9 is provided between the receiver 1 and the synchronization word coincidence detection unit 2, and the received signal (1 ) Is deinterleaved and provided to the synchronization word coincidence detection unit 2 in the form as shown in FIG.

The sync word coincidence detection unit 2 detects the coincidence of "BCa" or "Cab" in addition to the sync word "ABC". When the coincidence is detected, the coincidence detection pulse (2) is detected. The pattern identification signal (8) is given to the calculation unit 6 while being given to the unit 3.

The calculation unit 6 recognizes which of the above sync words is based on the pattern identification signal (8), calculates the position of the true sync word "ABC", and supplies the control signal (9) to the deinterleaver 9. .

After the synchronization is established in this way, the normal format (the synchronization word in the frame is only "ABC")
Since the calculation unit 6 receives the control signal (6) to the synchronization word coincidence detection unit 2, the synchronization search is performed in the portion where the synchronization word “ABC” exists. Further, the deinterleaver 9 performs the synchronization word from the beginning of the frame according to the control signal (9).

The operation of the embodiment shown in FIG. 10 will be described below for easier understanding.

First, in the example shown in FIG. 5, bit A
11A, the output signal (10) of the deinterleaver 9 is as shown in FIG.
It becomes “ ABC DEFGHHIJKLMNOPQRSTU”, and it can be seen that deinterleaving was performed at the correct position.

Next, when the reception is started from the bit D with a delay of 1 bit from the above correct position, the output signal (10) of the deinterleaver 9 is "DEFGHIJKLMNOPQ."
RSTU BCa ". This is because, as compared with the case of FIG. 11A, reception is started 1 bit later, so that the second line is the first line, the third line is the second line, and so on. One row at a time, there is no sync word on the first row,
A provisional synchronization word is newly inserted in the 7th line, and this can be detected by the detection unit 2.

Next, when reception is started from bit G with a delay of 2 bits from the correct position, the output signal (10) of the deinterleaver 9 is "GHI" as shown in FIG.
JKLMNOPQRSTU BCa EFd ", and the provisional synchronization word" BCa "can be detected in the sixth line.

In the same manner, the provisional sync word "BCa" can be detected in some row in any case until it is received from bit B with a delay of 7 bits.

However, when the data is received from bit E with a delay of 8 bits, the above synchronization word "BCa" cannot be detected as shown in FIG.

Therefore, this time, the output signal (10) of the deinterleaver 9 becomes "EFdHIgKLjNOmQRpTU.
s Cab ", so the tentative synchronization word" Ca
b ”can be detected.

Similarly, the provisional sync word "Cab" can be detected in any of the rows until the bit C delayed by 14 bits is received.

When reception is started from bit F with a delay of 15 bits, the output signal (10) of the deinterleaver 9 is "FdeIghLjk" as shown in FIG.
OmniRpqUst abc ", and there is neither the synchronization word" BCa "nor" Cab "as described above.
"Abc" in the row is nothing but the true sync word of the next frame shifted by one cycle, and is equal to the sync word "ABC".

In this way, the number of temporary synchronization words = (1
Number of bits in frame / interleave depth) -1 =
If (21/7) -1 = 2 provisional synchronization words are used as described above, synchronization can be established no matter where reception is started.

[0062]

As described above, according to the frame synchronization method of the present invention, before synchronization is established, a transmitter inserts a plurality of synchronization words in the first frame and transmits the same.
Since the receiving device detects that a synchronization word is detected and the transmitting device is notified that the synchronization has been established, the transmitting device is configured to restore the normal frame. The synchronization word can be detected quickly only by itself, and it greatly contributes to the performance improvement when synchronizing the communication device.

[Brief description of drawings]

FIG. 1 is a principle diagram of a frame synchronization method according to the present invention (No. 1).

FIG. 2 is a principle diagram of a frame synchronization method according to the present invention (No. 2).

FIG. 3 is a principle diagram of a frame synchronization method according to the present invention (part 3).

FIG. 4 is a principle diagram of a frame synchronization method according to the present invention (Part 4).

FIG. 5 is a principle diagram of a frame synchronization method according to the present invention (No. 5).

FIG. 6 is a block diagram showing an embodiment of a frame synchronization system according to the present invention (No. 1).

FIG. 7 is a block diagram showing an embodiment of a frame synchronization system according to the present invention (Part 2).

FIG. 8 is a block diagram showing an embodiment of a frame synchronization system according to the present invention (part 3).

FIG. 9 is a block diagram showing an embodiment of a frame synchronization system according to the present invention (Part 4).

FIG. 10 is a block diagram showing an embodiment of a frame synchronization system according to the present invention (No. 5).

FIG. 11 is a diagram for explaining the operation of the embodiment of the frame synchronization system according to the present invention (No. 5).

FIG. 12 is a frame format diagram for explaining a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 receiver 2 sync word coincidence detection section 3 pulse detection section 4 counter 5 data processing section 6 true sync word position calculation section 7 D1 to D10 detection section 8 deinterleaver In the drawings, the same reference numerals indicate the same or corresponding portions.

Claims (5)

[Claims] 1. A frame synchronization method between a transmitting device and a receiving device, which periodically transmit and receive frames, wherein a plurality of synchronization words are inserted into the first frame from the transmitting device and transmitted before the synchronization is established. It is assumed that synchronization has been established with the transmitting device by assuming that a true synchronization word is detected with a position which is one frame backward from the time when the device cannot detect the synchronization word after detecting the synchronization word. A frame synchronization method characterized in that the transmitting device returns to a normal frame upon notification. 2. In a frame synchronization method between a transmitting device and a receiving device that periodically transmit and receive frames, before synchronization is established, a plurality of synchronization words are included in a plurality of synchronization words in the first frame from the transmitting device and have different contents. Moreover, a true sync word is set by inserting a position corresponding to a position in the frame in advance and transmitting the position, and tracing back the position in the frame from the time when the receiving device detects the sync word as the head position of the frame. The frame synchronization method is characterized in that the transmission device returns to a normal frame by notifying that the synchronization has been established to the transmission device. 3. A frame synchronization method between a transmitting device and a receiving device, which periodically transmit and receive frames, wherein, before synchronization is established, a plurality of synchronization words correspond to positions within the frame in the first frame from the transmitting device. The information is transmitted by adding a predetermined number of bits of information, and a position traced back by the position in the frame indicated by the additional information from the time when the receiving device synchronously detects the synchronization word and the additional information is set as the head position of the frame. A frame synchronization method characterized in that the transmitter returns to a normal frame by notifying the transmitter that synchronization has been established assuming that a true synchronization word has been detected. 4. TDMA for periodically transmitting and receiving frames
In the frame synchronization method between the transmission device and the reception device in communication, one synchronization word is inserted into each frame from the transmission device and transmitted before synchronization is established, and the reception device uses only the slot addressed to itself as the synchronization word. The frame synchronization method is characterized in that the synchronization detection is performed not only for the slots addressed to other stations but the synchronization is established to the transmission device. 5. A frame synchronization method between a transmitting device and a receiving device, which periodically transmit and receive frames, wherein a plurality of synchronization words are interleaved and transmitted in the first frame from the transmitting device before synchronization is established, and the reception is performed. A frame synchronization method characterized in that a device prepares a sync word converted so that the device can always establish synchronization after deinterleaving, detects synchronization, and notifies the transmitting device that synchronization has been established.