JP3036914B2 - Delay time reduction method by fluctuation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an ATM (Asynchronous
The present invention relates to a method for reducing delay time due to fluctuation, which reduces delay time for absorbing fluctuation occurring in a transmission network such as a transfer mode network.

[0002]

2. Description of the Related Art Generally, in an ATM network, transmission data is assembled into a plurality of cells, and the cells are transmitted to a receiving terminal via a transmission network. Data transmission is performed by reading.
In such a transmission network, fluctuations occur in the network (fluctuations mean that cells transmitted at equal intervals are received at irregular intervals), so that received data is not interrupted by the fluctuations. Normally, the receiving terminal prepares a memory for absorbing the fluctuation, and when receiving the first cell, temporarily stores the received cell in the fluctuation absorbing memory, and after the fluctuation time elapses, the cell from the fluctuation absorbing memory. Is read and decomposed to read out transmission data. That is, in such a transmission network, it is necessary to store data in the fluctuation absorbing memory of the receiving terminal for the time to absorb the fluctuation, and thus a data delay occurs by this time.

In recent years, the processing speed of data terminals has also increased, and
The data arrival time of d to End (hereinafter referred to as delay) is also decreasing, and it is necessary to minimize the delay even in a terminal having a fluctuation absorbing memory on the receiving side. In addition, in the actual operation, since the transmission speed differs depending on the terminal, especially in a terminal having a low communication speed, the delay is particularly large in the “response” of the terminal.
As a problem.

[0004] In a transmission network having a fluctuation such as a conventional ATM network, as described above, a terminal that receives data waits for the fluctuation time when the first cell is received and decomposes the cell. Was.

A data transmission mode using such a transmission network will be described with reference to FIGS. In FIG. 5, reference numeral 51 denotes a transmitting terminal, 52 denotes an ATM network, and 53 denotes a receiving terminal.
Now, as shown in FIG. 6, when transmitting transmission data # 1 from the transmitting terminal 51, the data # 1 is transmitted from the SD to the cell assembling unit 51a. The cell assembling section 51a assembles the transmission data # 1 sequentially into cells # 1 to # 4,
It transmits to the network 52. The transmitted cell causes fluctuations in the ATM network 52 and arrives at the receiving terminal 53. This fluctuation time is defined as T _Y. In the receiving terminal 53, cell # 1
Arrives, the AT using the fluctuation waiting timer 53a
The mobile station waits for a fluctuation time T _Y (MAX) that may occur in the M network 52, and disassembles the cells by the cell disassembly unit 53b as soon as the time T _Y (MAX) elapses. That is, T _Y (MAX)
The cells arriving within the time period are all the fluctuation absorption memory 53c.
Store in. From the viewpoint of data delay, fluctuation delay occurs in addition to transmission path delay.

[0006]

Therefore, in the data transmission mode using such a transmission network, the receiving terminal 53 always has the fluctuation time T _Y (MAX) which may occur in the ATM network 52. There is a drawback that the user has to wait and a delay occurs.

The present invention has been made in consideration of such circumstances, and has as its object to reduce the delay time.

[0008]

FIG. 1 is a block diagram showing the configuration of a data transmission mode using a transmission network such as an ATM network to which the present invention is applied, and FIG. 2 shows the timing of signals in the system of the present invention. The method of the present invention will be described with reference to these figures. In the delay time reducing method according to the present invention, a transmission terminal 101 assembles transmission data into cells and transmits the cells to a transmission network 102. In the transmission system for performing data transmission by decomposing cells received by the receiving terminal 103 and reading out transmission data to the receiving terminal 103 via the receiving terminal 103,
Is stored in the fluctuation absorption memory 104, and the cell is read out from the fluctuation absorption memory 104 after waiting for a time obtained by subtracting a time required for decomposing one cell from the maximum fluctuation time generated in the transmission network 102. Reading out transmission data by decomposing cells.

That is, in the present invention, the basic operation is the same as the conventional operation shown in FIGS. 5 and 6, and the cell received by the receiving terminal 103 is made to wait as in the conventional case. The delay time is minimized by shortening the cell waiting time from the fluctuation time T _Y (MAX) generated in the transmission network 102 by the time required to decompose one cell. As shown in cell #
The time from when 1 is received to when it is decomposed is set as T _Y (MAX) −T _O , and the delay time is reduced by T _O.

[0010]

According to the present invention, as shown in the time chart of FIG. 2, the end-to-end delay time is shortened by one cell assembling time, and the terminal "response" at the end-to-end is shortened. Benefits are born.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited to this.

FIG. 3 is a block diagram showing a configuration of a data transmission form using an ATM network to which the delay time reduction method by fluctuation according to the present invention is applied. In this figure, 1 is a transmitting terminal, 2 is a cell multiplexing device, 3 is an ATM network, 4 is a cell separating device, and 5 is a receiving terminal. The transmitting terminal 1 has H
DLC terminal # 1 and HDLC terminal # 2 are provided.
The cell multiplexing device 2 includes two cell assembling units 2a and 2b.
And a cell multiplexing unit 2c. The cell separation device 4 includes a cell separation unit 4a and two cell decomposition units 4b and 4c. The two cell decomposition units 4b and 4c further include a fluctuation absorption memory 41, a fluctuation waiting timer 42, and a decomposition unit 43. ing. HDLC terminal # 3 and HDL
C terminal # 4 is provided.

The operation in such a configuration will be described below. Data transmission from HDLC terminals # 1 and # 2
2.4 kbps ST2 from cell assembling units 2a, 2b
This is performed by an SD signal by a clock (CLK). Therefore, the transmission speed of these HDLC terminals # 1 and # 22 is 2.4.
kbps.

The cell assembling units 2a and 2b convert only valid data from the SD signals from the HDLC terminals # 1 and # 2 into cells (to assemble cells is referred to as cells) and transmit them. Here, it is assumed that 128 bytes of valid data from HDLC terminals # 1 and # 2 are assembled into 44-byte cells. In the cell multiplexing unit 2c, each cell assembling unit 2a, 2b
Are multiplexed and transmitted to the ATM network 3.

The cells that have passed through the ATM network 3 are received by the cell separation unit 4a of the cell separation device 4 of the receiving station. The cell separation unit 4a separates the multiplexed cells and transmits them to the cell separation units 4a and 4b. In each of the cell separation units 4b and 4c,
When the first cell (the first cell) is received, the cell is stored in the fluctuation absorption memory 41, and at the same time, the fluctuation waiting timer 4
Start 2 The time setting of the fluctuation waiting timer 42 is A
The time is obtained by subtracting the time required to decompose one cell from the fluctuation time that may occur in the TM network 3, and after the time set by the fluctuation waiting timer 42 has elapsed, the cell is sent to the decomposing unit 43 to decompose the cell. .

For example, as shown in FIG. 4, the fluctuation time that can occur in the ATM network 3 is 500 ms, and
As for the time for decomposing the cell, the terminal speed is 2.4 k.
Since one cell is 44 bytes in bps, 1/240
Assuming that about 146 ms from 0 × 8 × 44 ≒ 146, the set time of the fluctuation waiting timer 42 is 500 ms-146 m
s = 354 ms. Therefore, each cell separation unit 4
In steps b and 4c, after receiving the first cell, the cell is stored in the fluctuation absorption memory 41, and the fluctuation waiting timer 42 sets the cell to 35.
After the elapse of the set time of 4 ms, the cell is sent to the decomposing unit 43 to decompose the cell. The decomposed data is R
D is transmitted to HDLC terminals # 3 and # 4 of receiving terminal 5.

In this way, by reading the cells from the fluctuation absorption memory 41 after waiting for the time obtained by subtracting the decomposition time of one cell from the maximum fluctuation time generated in the ATM network 3, the terminal speed of 2.4 kbps can be obtained. In this case, the data transmission speed can be reduced by about 146 ms from End to End compared to the related art.

[0018]

As described above, according to the present invention, the time required for a receiving terminal to wait for a cell is shortened by the time required to decompose one cell from the fluctuation time. Can be shortened by one cell assembling time, which greatly contributes to the performance improvement of the end-to-end terminal “response”.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a data transmission mode to which the present invention is applied.

FIG. 2 is a time chart showing signal timings in the system of the present invention.

FIG. 3 is a block diagram showing a configuration of an embodiment of a data transmission mode to which the present invention is applied.

FIG. 4 is a time chart showing signal timings according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a transmission form using a conventional ATM network.

FIG. 6 is a time chart showing timings of signals in a transmission form using the conventional ATM network shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmitting terminal 2 Cell multiplexing device 2a, 2b Cell assembling unit 2c Cell multiplexing unit 3 ATM network 4 Cell separating device 4a Cell separating unit 4b, 4c Cell decomposing unit 41 Fluctuation absorption memory 42 Fluctuation waiting memory 43 Decomposing unit 5 Receiving terminal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/56 H04L 12/28 H04Q 11/04

Claims (1)

(57) [Claims] 1. A transmitting terminal (101) assembles transmission data into cells, transmits the cells to a receiving terminal (103) via a transmission network (102), and receives the cells at the receiving terminal (103). In a transmission system that performs data transmission by decomposing data and reading out transmission data, a cell received by a receiving terminal (103) is stored in a fluctuation absorption memory (104), and a maximum fluctuation time generated in a transmission network (102) is obtained. A method for reducing the delay time due to fluctuations, comprising reading a cell from the fluctuation absorption memory (103) after waiting for a time obtained by subtracting a time required to decompose one cell from the memory, and reading out transmission data by decomposing the read cell.