JP2001313648A - ATM cell radio transmission system - Google Patents

Abstract

(57) [Abstract] ATM cell radio transmission in which each transmission device can directly perform mutual transmission via a radio transmission line, and can achieve a common ATM cell radio transmission system and improve transmission efficiency. Provide a method. SOLUTION: An AT is performed using a predetermined wireless transmission frame.
In an ATM cell wireless transmission system for wirelessly transmitting M cells, a wireless transmission frame is configured in a format conforming to the HDLC frame format, and its information field 1
5, one ATM cell is inserted and wirelessly transmitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM cell wireless transmission system for wirelessly transmitting ATM (Asynchronous Transfer Mode) cells using a wireless transmission line.

[0002]

2. Description of the Related Art An ATM cell is formed of a 53-byte data structure including 5 bytes of header data as destination information called VPI / VCI (virtual path identifier / virtual channel identifier) and 48 bytes of ATM data. Generally, transmission frames including ATM cells are transmitted and received in an asynchronous manner. Conventionally, in order to wirelessly transmit such an ATM cell, a transmission protocol for transmission and reception on a wireless transmission line is uniquely defined for each wireless transmission system. For example, in a conventional wireless transmission system in which many access devices AE are connected to a base station device BSE via a public wireless transmission network, the access devices AE include:
According to the TDMA (Time Division Multiple Access) method, transmission can be performed with another access device AE via the base station device BES only in a predetermined time slot allocated on the time axis.

[0003]

However, the conventional wireless transmission system has the following problems. That is, in the conventional wireless transmission system, the access devices AT transmit data only via the base station device BSE. For this reason, not only are the access devices AE unable to directly transmit the ATM cells to each other, but also the use of the public wireless transmission network is charged, and the usage fee is increased. In addition, in the conventional wireless transmission system, there is a problem that it is difficult to reduce the system cost because software related to the transmission method must be created for each system. Further, in a conventional wireless transmission system, a time slot is uniquely assigned to each station on a time axis. For this reason, wireless transmission cannot be performed unless the assigned time slot is reached, and if there is no ATM cell to be transmitted to one wireless station, the ATM cell is transmitted in that time slot. There is no wasted time. For this reason, the conventional wireless transmission system has a problem that transmission efficiency is poor.

[0004] The present invention has been made in view of the above-mentioned problems, and enables each transmission apparatus to directly perform mutual transmission via a wireless transmission line. It is a main object of the present invention to provide an ATM cell radio transmission system capable of improving efficiency.

[0005]

In order to achieve the above object, an ATM cell radio transmission system according to claim 1, wherein an ATM cell wirelessly transmits an ATM cell using a predetermined radio transmission frame.
In the cell radio transmission system, the radio transmission frame is set to HD
It is characterized in that it is configured in a format conforming to the LC frame format, and one ATM cell is inserted into its information field for wireless transmission. Note that the HDLC frame format in the present invention includes LAP-B (Link Access
Procedure on the B-channel), LAP-D (Link Acc
ess Procedure on the D-channel) format.

According to a second aspect of the present invention, there is provided an ATM cell radio transmission system according to the first aspect.
The wireless transmission frame is transmitted by a link management procedure using a UI frame in the LAP-D frame format.

According to a third aspect of the present invention, there is provided the ATM cell radio transmission system according to the first or second aspect, wherein the ATM cell radio transmission system is a SAB using a LAP-D frame format.
Link setting is performed using an ME frame.

According to a fourth aspect of the present invention, there is provided an ATM cell radio transmission system according to any one of the first to third aspects, wherein the link is released using a DISC frame in a LAP-D frame format. Features.

According to a fifth aspect of the present invention, there is provided an ATM cell radio transmission system according to any one of the first to fourth aspects, wherein a guide time constituted by repetition of a flag is added to a leading portion of a radio transmission frame. And transmitting it.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the ATM cell radio transmission system according to the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the ATM cell radio transmission system 1 includes a plurality of service devices SE1 to SE4 (hereinafter, referred to as “service device SE” when no distinction is made).
It is provided with. In this ATM cell radio transmission system 1, the ATM cells are radio-transmitted in accordance with the ATM cell radio transmission system according to the present invention, whereby the ATM cells can be freely transmitted and received between the service devices SE, SE without defining a time slot. Transmission is possible, and even in the case where an ATM cell is lost, reliable information transmission is enabled by re-transfer according to the confirmation type information transfer procedure. Also, LAP according to the HLDC method
-By transmitting ATM cells wirelessly using the D frame format transmission method, it is common to a plurality of ATM cell radio transmission systems that differ in area and frequency without defining a transmission method for each ATM cell radio transmission system. Since the transmission method of the present invention can be used, a common wireless transmission program and hardware resources can be used.
The system cost of the TM cell wireless transmission system 1 can be reduced.

Next, an ATM cell radio transmission format according to an embodiment of the present invention will be described.

An information transfer frame for ATM cell transmission used in the ATM cell radio transmission system 1 is HDL.
It is composed of a RAP-D frame based on a C frame. Further, the frame is an information transfer frame (I) for performing information transmission according to the acknowledgment type information transfer procedure.
(Information) frame) and a monitoring frame (S (Supervision) frame) for monitoring the information transfer state
And an information transfer frame (U (Unnumbered) frame) for performing information transfer according to an unacknowledged information transfer procedure. In this case, as shown in FIG. 2A, a guide time 11 is inserted at the beginning of the information transfer frame for ATM cell transmission. The guide time 11 is used to insert the same pattern data (seven bytes) as that of the start flag unit 12 described later, and to cause the service device SE of the transmission partner to perform synchronous lock. Hereinafter, the description will be made assuming that the guide time 11 is not included in the octet value.

In the first octet of the information transfer frame, a 1-byte start flag section 12 is inserted.
In the octet, a 2-byte address field part 1
3 is inserted. Similarly, at the 4th and 5th octets, a 2-byte control field section 14 is inserted. After the 6th octet, an information field section 15, a 2-byte frame check sequence section 16, and a 1-byte end The flag unit 17 is inserted.

The start flag unit 12 functions as a guide time for causing the receiving-side service device SE to perform synchronous locking, as in the case of the guide time 11, and for example, “1” consecutive “6”. 01111110 "pattern. Therefore, the service device SE on the transmission side and the reception side can perform so-called insertion / removal of 0 so that the data and the flag can be identified. As shown in FIG. 2B, the first byte (the second octet) of the address field section 13 is 1 byte.
CR (Command / Responc) consisting of a 0 data portion 21 of bits and 1 bit for identifying a command and a response
e) SAPI (Service) consisting of bit 22 and 6 bits
Access Point Identifier) subfield 23, and the next byte (3rd octet) consists of 1-bit 1-data portion 24 and 7-bit TEI (Terminal).
Endpoint Identifier) subfield 25.

In this case, the SAPI value in the SAPI subfield 23 is usually used for meaning (specifying the type of information for a received frame) defined by the ITU-T recommendation.
Is used as an information field for zone identification. Specifically, when performing zone identification by frequency, for example, when the value of SAPI is “0”, it is defined as a zone (group) of frequency f1 and the value of SAPI is “2”.
In the case of, it is defined as a zone of the frequency f2. Therefore, a plurality of zones can exist hierarchically using a plurality of frequencies. Therefore, unlike the conventional wireless transmission system, this ATM cell wireless transmission system 1
By using a plurality of frequencies, a mobile object can be included in the transmission device in the system. When zone identification is performed according to the area, the area is assigned to the SAPI value. On the other hand, the TEI subfield 25 is provided with link numbers (1 to N) described later. Therefore, T
By checking the link number in the EI subfield 25, the device numbers of the service devices SE on the transmission side (C side) and the reception side (R side) can be identified.

Further, the control field section 14 is used for transmitting data in a confirmation type information procedure or a broadcast format between the service devices SE, SE, and as shown in the coding diagram of FIG. It has a function of specifying an information transmission procedure. Here, the types of frames are roughly classified into information (I), monitoring (S), and unacknowledged information transfer (U).

In the information field section 15, one 53-byte ATM cell is inserted. In this case, in the normal transmission method, since the information field section 15 is defined to have an arbitrary data length, it is possible to insert several ATM cells. On the other hand, in this ATM cell radio transmission system 1, by inserting only one ATM cell into the information field section 15, it is possible to avoid a situation in which data is continuously transmitted by a specific service device SE. Can be imparted with a fair transmission right to the service device SE. Further, the frame check sequence unit 16 is used for performing frame error detection by the CRC method.

Next, this ATM cell radio transmission system 1
Will be described with reference to FIGS.

First, a link is formed on the side of the service device SE that transmits an ATM cell. In this case, this ATM
In the cell radio transmission system 1, as shown in FIG. 1, for example, a service device SE1 and service devices SE2 to SE4
The wireless transmission lines between the service devices SE2 and SE3 and the service devices SE3 and 4 are links 4 and 5, respectively. Similarly, the service device SEM and the service device SE (M + 1 ) Is a link N. In this case, in the ATM cell radio transmission system 1, the transmission order of the information transfer frame is defined in advance so as to circulate through the link 1 to the link N. Therefore, each service device SE first determines whether or not an information transfer frame is being transmitted before link formation. Specifically, for example, when 640 bits corresponding to the bit length of almost one information transfer frame are not received, it is determined that the information transfer frame is not transmitted from any of the service devices SE. Therefore, first, the service device SE1 forms the link 1 (or the links 2 and 3). In this case, the service device SE1
Does not have an ATM cell to transmit, the service device SE2 forms a link. Therefore, only the service device SE having the ATM cell to be transmitted forms a link. Therefore, since no time slot is assigned, only the service device SE having the ATM cell to be transmitted is sequentially given the transmission right. As a result, when the number of service devices SE having ATM cells to be transmitted is small, loss of transmission time due to waiting for a time slot can be reduced, thereby improving transmission efficiency.

On the other hand, when the service device SE1 has an ATM cell to be transmitted to the service device SE2, the service device SE1 transmits a UI frame (see FIG. 3) in the LAP-D frame format as shown in FIG. The information transfer frame is transmitted according to the used link management procedure (unconfirmed information transfer) (step 31). In this case,
The link management procedure message frame shown in FIG. 5 is transmitted as an information transfer frame. As shown in the figure, the link management procedure message frame includes a guide time 41,
A start flag section 42, an address field section, a control field section in which a UI command is inserted, an information field section, and a 48-byte field having a normal value "0"
A sub-data 50 into which putting made of repetition of "1" is inserted, a frame check sequence unit 51,
An end flag section 52 is formed. In this case, the address field portion includes a SAPI subfield 43 in which an identification code for identifying the zone to which the service device SE2 belongs is inserted, and a TEI subfield in which a value (for example, FFH) indicating that a link has not yet been established is inserted. Field 4
4 are formed. Further, the information field portion has a fixed value (for example, 0F) as the management entity identifier.
H) Management entity identification 46 into which is inserted
, A reference number 47 composed of a combination of the SAPI value and the TEI value, a message type 48, and an operation display 49 in which the device number of the service device SE of the link request source is inserted. Further, the message type 48 includes a link request (for example, 81H) and a link allocation (for example, 82H).
Alternatively, a message type of link rejection (for example, 83H) is inserted, and when transmitting by the service device SE1, data indicating a link request is inserted.

Next, the service device SE2 is
A link management procedure message frame is transmitted in a link management procedure using a UI frame in the LAP-D frame format (step 32). At this time, when permitting the link assignment, the service device SE2 inserts data (for example, 82H) indicating that the link assignment is allowed into the message type 48, and rejects the link assignment with the message type 48 when rejecting the link assignment. Meaning data (for example, 83H) is inserted. Further, the service device SE2 inserts an identification code for zone identification to which the service device SE1 belongs into the SAPI subfield 43,
In addition, an unused link number is inserted into the TEI subfield 44.

Next, the service device SE1 transmits the LAP-
A link setting is requested using a SABME (asynchronous balanced mode setting) frame (see FIG. 3) in the D frame format (step 33). Subsequently, the service device S
E2 is a UA in the LAP-D frame format
A link management procedure message frame for link setting confirmation using an (unnumbered confirmation) frame (see FIG. 3) is transmitted (step 34). At this time, if it is necessary to continuously send ATM cells within a predetermined time on the time axis, continuous data such as voice and image should be provided so as not to hinder reproduction.
It is necessary to notify the other party's service device SE2 of the number of transmitted ATM cells. In this regard, in the conventional wireless transmission system, the method is individually defined, whereas
In the TM cell radio transmission system 1, the service device SE1
However, according to the unacknowledged information transfer procedure defined in the LAP-D system, a bandwidth allocation request is issued using a link management procedure message frame using an unacknowledged information frame (UI frame) in the control field unit 14. Meaning data (for example, 91H) is inserted into the message type 48, and a value indicating the band is set in the sub-data 50 and transmitted. Therefore, in the ATM cell radio transmission system 1, band allocation can be easily performed.

Thereafter, the service device SE1 transmits an information transfer frame based on the I frame in which the ATM cell is inserted to the service device SE2 (step 35).
Next, the service device SE2 transmits the R using the S frame.
The R command (see FIG. 3) is transmitted to the service device SE1 (step 36). At this time, both service devices SE
1, SE2 detects a missing cell of the ATM cell according to the confirmation type information transfer procedure. Specifically, both service devices S
E1 and SE2 are N (S) parameter (send number) and N of control field data (see FIG. 3) inserted into the control field section 14 of the information frame (I).
By referring to the (R) parameter (receive number), it is possible to detect a missing cell of the ATM cell. When a cell loss is detected, the information transfer frame is retransmitted in accordance with the RAP-D retransmission procedure (acknowledgment information transfer procedure). Therefore, the reliability of ATM cell transmission can be improved.

Next, the service devices SE1 and SE2
The RR commands using the monitoring (S) frame are transmitted to each other (steps 37 and 38), and when there are no more ATM cells to be transmitted, the service device SE1 sends the LAP-
DISC frame in D frame format (Fig. 3
(See step 39). At this time, the service device SE1 sets the control field unit 14
A non-acknowledgment type information transfer frame in which a DISC (disconnect) command is inserted is transmitted to the service device SE2. Then
The service device SE2 transmits the unacknowledged information transfer frame in which the UA command is inserted into the control field unit 14 to the service device SE2 (step 40). This allows
The link is broken. These processes are performed by each service device S
ATM to be transmitted by being sequentially performed by E
A cell is transmitted between each service device SE.

It should be noted that the present invention is not limited to the above-described embodiment, and the configuration can be changed as appropriate. For example, in the present embodiment, the ATM cell radio transmission system using the LAP-D has been described.
-B, an ATM cell radio transmission system may be employed. However, in the case of using the ATM cell radio transmission system based on LAP-D, the transmission procedure is easier than in the system using the ATM cell radio transmission system based on LAP-B.
It goes without saying that each transmission procedure and the content to be inserted into each field can be changed as appropriate.

[0027]

As described above, according to the ATM cell radio transmission system of the first aspect, the frame for radio transmission is HDL
By constructing a format conforming to the C frame format and inserting one ATM cell into the information field for wireless transmission, each transmission device can directly perform mutual transmission via a wireless transmission line. . Therefore, there is no need to use a public wireless transmission network, so that a usage fee can be eliminated. At the same time, the transmission method of a plurality of ATM cell radio transmission systems having different regions and frequencies can be shared without defining a transmission method for each ATM cell radio transmission system. Software) and hardware resources (PLD and gate array) can be shared.
The system cost of the TM cell wireless transmission system can be reduced. In addition, by using a frame having a format conforming to the HDLC frame format, the ATM cell can be transmitted by the confirmation type information transfer procedure, whereby the retransmission procedure can be easily realized using an existing program or hardware resources. Therefore, the system cost of the wireless transmission system can be reliably reduced. In addition, ATMs can be transmitted between transmission devices without specifying time slots.
Since cells can be freely transmitted by radio, transmission efficiency can be improved. In addition, even when the ATM cell is lost, the ATM cell can be re-transferred in accordance with the acknowledgment information transfer procedure, so that the information transmission can be reliably performed.

According to the second aspect of the present invention, an ATM cell wireless transmission system transmits a wireless transmission frame in a link management procedure using a UI frame in a LAP-D frame format, thereby enabling communication with a transmission apparatus on the other end. A link can be easily formed between the two, and band allocation can be easily performed.

According to the ATM cell radio transmission system of the third aspect, by setting a link using a SABME frame in the LAP-D frame format, it is possible to easily establish a link with a transmission apparatus on the other side. Settings can be made.

Further, according to the ATM cell radio transmission system of the present invention, by releasing the link using the DISC frame in the LAP-D frame format, the link formed between the transmission device and the transmission device of the other party is released. Can be easily released.

According to the ATM cell radio transmission system of the present invention, a guide time composed of a repetition of a flag is inserted into a head portion of a radio transmission frame and transmitted, whereby the transmission device on the other side is transmitted. Can be securely locked.

[Brief description of the drawings]

FIG. 1 is a system conceptual diagram of an ATM cell radio transmission system 1 according to an embodiment of the present invention.

FIG. 2A is a data configuration diagram of an information transfer frame,
FIG. 3B is a data configuration diagram of the address field unit 13.

FIG. 3 is a coding diagram showing coding of a control field unit 14;

FIG. 4 is a flowchart showing a transmission procedure when transmitting an information transfer frame.

FIG. 5 is a coding diagram showing an example of a link management procedure message frame.

[Explanation of symbols]

 1 ATM Cell Radio Transmission System 11 Guide Time 14 Control Field SE1-SE4 Service Equipment

Claims (5)

[Claims] 1. An AT using a predetermined wireless transmission frame.
In an ATM cell wireless transmission system for wirelessly transmitting M cells, it is preferable that the wireless transmission frame is formed in a format conforming to the HDLC frame format, and that one ATM cell is inserted into its information field and wirelessly transmitted. Characteristic ATM cell radio transmission system. 2. The wireless communication apparatus according to claim 1, wherein the wireless transmission frame is transmitted by a link management procedure using a UI frame in a LAP-D frame format.
TM cell radio transmission system. 3. The ATM cell radio transmission system according to claim 1, wherein a link is set using a SABME frame in a LAP-D frame format. 4. The ATM cell radio transmission system according to claim 1, wherein the link is released using a DISC frame in a LAP-D frame format. 5. The ATM cell radio transmission system according to claim 1, wherein a guide time composed of a repetition of a flag is inserted into a head portion of the radio transmission frame and transmitted. .