JPS58194440A - Forming system of synchronizing word - Google Patents

Abstract

PURPOSE:To simplify the constitution of a synchronous word detector, by having the same synchronizing word for both the reference burst and the data burst with a time division multiplex communication system and using a burst discriminating code formed with a small number of bits during acquisition of synchronism. CONSTITUTION:The same synchronous word (unique word) 4 is used for both reference and data burst data, and a burst discriminating code 5 consisting of two bits is added to the word 4. For the code 5, 11 and 00 are defined as the reference burst and the data burst respectively, for example. When the word 4 and the code 5 are detected during acquisition of synchronism, an estimation gate is opened after one frame. Furthermore, the estimation gate is opened after one frame if both word 4 and code 5 are detected in the same way. If the similar detections are carried out continuously with N frames within the estimation gate, it is decided that the reference burst has been caught in a correct way. Thereafter only the word 4 is detected within the estimation gate with no use of the code 5. The position of the data burst is decided on the basis of the position of the reference burst. Therefore the data burst can be correctly discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronization word construction method for burst reception in a time division multiplex communication system.

In the time division multiplex communication system, as shown in Figure 1,
Reference burst (100) to maintain frame synchronization
and multiple dataverses carrying traffic) (10
Two types of bursts can be distinguished: 1 to 10n). To receive these bursts and detect their location at the receiving end, a specific fixed synchronization word, usually called a unique word, is used. When the side frames are not synchronized, it is necessary to first detect the unique word of the reference burst and establish frame synchronization. Once the unique word of the reference burst (100) is captured, the data burst (101~10n) The unique word position of the data burst (101-10n) can be predicted with reference to the position of the reference burst, and by generating a prediction gate, the unique word of the data burst (101-10n) is detected in this gate, and in this way dataverse) (10
1 to 10n) is detected.

The conventional unique word configuration uses different words with low cross-correlation as unique words for these two types of bursts. FIG. 2 shows the positions of unique words within a burst.

In the figure, (1) shows a fixed button part for enabling the receiver to operate for each burst, (2) shows a unique word part for reference bursts, and (3) shows a unique word part for data bursts. FIG. 3 shows the configuration of a synchronization word detection circuit section for detecting such two unique words. In the figure, αυ is an input terminal for inputting a received digital data string, α is a reference burst unique word detector, and C13 is a data burst unique word detector.

The two detectors are always operated in parallel and detect unique word bumps present in the received digital data string. For example, unique word patterns typically have a length of 20 bits or more.

As mentioned above, in the conventional synchronization word detection circuit, two completely different
This method requires a type detector, which has the disadvantage of increasing the amount of hardware.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it makes the unique word pattern of the reference burst and the data burst the same, and uses a burst identification code consisting of a small number of bits at the time of synchronization pull-in. By using this, the purpose is to simplify the unique word detector.

An embodiment of the present invention will be described below with reference to the drawings. Fourth
The figure shows an example of a synchronization word structure according to the present invention. In FIG. 4, (4) is a unique word portion common to the reference burst and data burst, which is considered to be 20 bits in this example. (5
) is a burst identification code consisting of 2 bits, for example code +1 . ．． 11 is a reference burst, and the code 00 is a data burst.

Reference burst detection at the time of synchronization pull-in is performed as follows.

If the 111 unique word pattern (4) and the reference burst burst identification code +51 are detected, the prediction gate is opened one frame later, and if the same is detected again, the prediction gate is opened one frame later.

3゜IcOyoic, ZN7v-1-MINI,,,r
If a similar detection is performed within ffjJJJ'f-)', it is assumed that the reference burst has been correctly captured, and thereafter the detection within the prediction gate is limited to unique word detection. That is, no burst identification code is used.

The data burst starts from the position of the reference burst.
Since the position is determined in advance, unique word detection of a data burst can be correctly identified by generating a data burst prediction gate even if the unique word pattern is the same as that of the reference burst. As is clear from the above description, the data burst detector does not require a burst identification code.

Note that since a prediction gate cannot be generated when a reference burst is detected for the first time, there is a possibility that a data burst may be mistaken for a reference burst. That is, if the value of the reference burst is 011, this can be prevented by selecting 000 for the data burst, and by increasing the value of N in the pull-in process.

In the above example, the burst identification code has been explained as having 2 bits, but if a slightly larger number of bits is used, the reliability of initial acquisition will increase.

As described above, according to the present invention, only one complex unique word detector is required, and the burst identification code can also be realized by a simple coincidence detector, so that the apparatus can be miniaturized.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the positional relationship between reference bursts and data bursts in a time division multiplex communication system, FIG. 2 is a diagram showing the burst formats of reference bursts and data bursts,
FIG. 3 is a diagram showing an example of the configuration of a synchronization word detection circuit according to the conventional synchronization word construction method, and FIG. 4 is a diagram showing an example of the configuration of a synchronization word according to the present invention. In the figures, the same reference numerals indicate the same or corresponding parts. il+...Fixed pattern part, (4)...Unique word part, (5)...Burst identification code. Agent Makoto Kuzuno - Procedural amendment (spontaneous) Commissioner of the Japan Patent Office 1, Indication of tenant work Patent application Sho IT-7806 No. 2,
Title of the invention Synchronous word construction method 3, relationship with the tenant making the amendment Patent applicant address Rishiro, Tokyo ■1 Okibi-no-uchi 2-2-3
Title (601): Ryodenki Co., Ltd. Representative Katayuni 8be 4, Agent address 2 Marunouchi, Chiyo I11-ku, Tokyo, "Item 2, No. 3 > ¥5, Subject of amendment (1) Patent in the specification Scope of Claims and Detailed Description of the Invention Column 6 Contents of Amendment (1) The scope of claims in the specification is corrected as shown in the attached sheet (
2) The description will be amended as follows. 7. A document stating the scope of claims of the specification with a revised list of attached documents
1
Claims: In a time division multiplex communication system in which a standard burst and other bursts are transmitted separately, the same synchronization word (unique word) is used in the standard burst and other bursts, and the above two types added thereto. Different burst identification codes are used for each burst, and when searching for a reference burst, the reference burst is identified using the above unique word and burst identification code, and after synchronization is acquired, the reference burst is identified using only the above unique word without using the burst identification code. A synchronization word construction method that enables the detection of synchronized data bursts. 2

Claims (1)

[Claims] In a time division multiplex communication system that transmits a reference burst and other bursts separately, the reference burst and other bursts have the same synchronization M (unique word), and the two types of bursts added to this have different bursts. When searching for a reference burst, the reference burst is identified using the unique word and the burst identification code, and after synchronization is acquired, the reference burst and data burst are detected using only the unique word without using the burst identification code. A synchronization word construction method that enables