JPS5866444A - Data transmitter - Google Patents

Abstract

PURPOSE:To improve the efficiency of transmission, by dividing a TDMA frame into plural time slots by means of plural types of optical signals of different wavelengths and permitting the simultaneous transmission of optical signals having different wavelengths even for the same time slot. CONSTITUTION:An optical transmitter transmits plural types of optical signals of different wavelengths to each of plural optical stations which are connected to each other via a common optical fiber transmission line 1. A demultiplexer 7 separates the light of each wavelength from plural types of optical signals of different wavelengths which are received from the line 1. Then plural time slots are set into the frame which is repeated with a prescribed period. The wavelength used to an optical signal transmitted through each slot is designated by each optical station so as to avoid transmitting an optical communication of the same wavelength within the same time slot in a different way from the optical stations.

Description

[Detailed Description of the Invention] The present invention provides TDMA (Time Dial) using optical signals.
The present invention relates to a data transmission device using the visionMultipl@Access) system.

A conventional device of this type is shown in FIG. In the figure, (1) is an optical fiber transmission line, (2) is an optical station, (3) is an optical coupler, (4) is an optical transmitter (symbol is TX), and (5) is an optical receiver (symbol is )
, (6) is a terminal device (symbol is MUX).

Fig. 2 is an operation time diagram showing a no-frame configuration when each party station accesses the optical fiber transmission line (1) in the IIi TDMA system.The frames are repeated with a period of Tf, and in one frame there are as shown in Fig. 2. RB (Reference Burst) in FIG. 2, where a plurality of time slots are defined as shown by rectangles, and each time slot is assigned to each optical station.
is a signal used by the master station as a reference for the transmission time slot, that is, a synchronization signal, and each optical station determines the position of the time slot assigned to it with reference to the RB. Second
Figure DB (Data Burst) 1 m2
*3+4 is the time slot allocated to the signal transmission of each optical station, for example DBI is allocated for the transmission of the first optical station. Address FiDB1 of the optical station to receive the call. Put it within the signal of... Each station transmits its own signal in bursts within its allotted time. Furthermore, each station receives all the bursts in the frame (excluding the bursts sent by its own station), and inputs any signal that is detected at the destination address as a signal intended for its own station into its own register.

As the number of stations using a common fiber transmission path increases in the conventional arrangement described above, the number of time slots in T increases, and therefore the duration of one time slot becomes shorter, and the ITDMA frame However, the disadvantage is that the time during which the own station can transmit is reduced, making it impossible to handle the desired amount of communication.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and uses multiple types of optical signals with different wavelengths to divide an ITDMA frame into multiple time slots as in the past. It is an object of the present invention to provide a data transmission device with high transmission efficiency by allowing simultaneous transmission of optical signals having different wavelengths even in time slots.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 3 is a block diagram showing an embodiment of the present invention. In FIG. 3, (1) is the same part as (1) in FIG. 1, (3 Todoroki),
(4a) - (5g) and (6a) respectively correspond to (3), (4), (5) and (6) in Fig. 1, (7) is a duplexer, (8) and ( 8m) '#i is a switch that selects the wavelength of each transmitted and received burst optical signal, and (9) is a multiplexer.

Further, FIG. 4 is an operation time diagram showing the frame structure in this invention, and FIG.
), different wavelengths λ1. as shown in (d). λ2. λ3
．． Temporally parallel frames are constructed every λ4.

FIG. 5 is a characteristic diagram showing the demultiplexing characteristics of the duplexer (7).

The operation of the circuit shown in FIG. 3 will be explained below. In the example shown in FIG. 4, the RB from the master station is transmitted at wavelength λ1. If the master station is the first optical station and sends out the data burst shown by DBI in Fig. 4, the frame Tf
In the first time slot, the wavelength λ1 is used, in the second time slot, the wavelength λ2, in the third time slot, the wavelength λ3, and in the next time slot, the wavelength λ4. Send DBI with . Also the fourth
In the example shown in the figure, the DBI of wavelength λ, transmits the signal to arrive at the second optical station (shown as TO2 in Figure 4).
, wavelength λ2. The DBI at λ4 transmits the signal to arrive at the third optical station (shown as TO3 in Figure 4) at wavelength λ.
DBI 3 sends a signal (shown as TO4 in FIG. 4) to arrive at a fourth optical station. The second, third, and fourth optical stations similarly transmit data bursts shown as DB2, DB3, and DB4, respectively, in FIG. 4 to their respective partner stations at their respective wavelengths.

Assuming that the wavelength of the data burst and the order of its time slots are predetermined as shown in Figure 4, for example, the second optical station receives DBI with wavelength λ1 in the time slot following RB, and then Switch (8a) is controlled to receive DB4 with wavelength λ3 in a time slot, receive DB3 with wavelength λ1 in the next time slot, and receive DB4 with wavelength λ1 in the furthest time slot of the frame. do it.

The guard time placed between the RB and each DB in FIG. 4 is the guard time for switching the switches (8) and (8a). As is clear from Fig. 4, DBI, DB2, DB3, and DB4 are always capable of transmitting during one frame Tf, except for the RB time slot and the guard time, and therefore, each party station transmits much more data during one frame than before. It is possible to send out large amounts of data.

As described above, according to the present invention, each data burst signal in a TDMA frame can be transmitted at any wavelength of multiple optical signals with different waveforms, and when receiving, an optical signal of any wavelength can be selected for each burst. Since the structure is designed to be able to receive data automatically, the frame structure can be set freely, and it becomes possible to configure a highly flexible data transmission network depending on the usage status of the data transmission system.

Furthermore, it is possible to send a plurality of burst signals within an ITDMA frame, and the IB data transmission capability is improved accordingly. Furthermore, when this invention is used to increase the number of optical signals in an existing TDMA data transmission device, it has the effect of increasing the number of optical signals with the least number of modifications to the terminal equipment, including the synchronization system. ,

[Brief explanation of drawings]

Figure 1 is a block diagram showing a conventional gfW, Figure 2 is a TD
FIG. 3 is a block diagram showing an example of the frame structure in the MA system. FIG. 4 is an operation time diagram showing an example of the frame structure f+v in the invention. FIG. It is a characteristic diagram showing the demultiplexing characteristic of the duplexer used in this invention. (1)...Optical fiber transmission line, (3a)...Optical coupler, (41)...Optical transmitter, (5a)...Optical receiver, (6m)...Terminal Device, (7)... duplexer, (
8) , (8a)...each switch. Note that in the drawings, the symbols indicate the same or equivalent parts. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In a data transmission device in which a plurality of optical stations transmit data between stations using a common optical fiber transmission path, each of the plurality of optical stations is provided with a plurality of types of optical signals having different wavelengths. an optical transmitter that sends out to an optical fiber transmission line; and a demultiplexer that separates light of each wavelength from the plurality of types of optical signals having different wavelengths received from the optical fiber transmission line provided at each of the stations. A plurality of time slots are defined in a frame that is repeated at a predetermined period, and each optical station transmits light using each slot to prevent optical communication using the same wavelength from being transmitted from optical stations with different internal pressures in the same time slot. 1. A data transmission device comprising: means for specifying a wavelength used for a signal.