CN100438553C - Method for decreasing facsimile negotiation frame collision - Google Patents

Abstract

The method comprises: in a fax transmission process, the fax process between calling and called terminal is divided into two independent processes by a transfer device; the transfer device controls the time of sending fax negotiation frame to both calling and called sides, and respectively negotiates with the calling and called sides.

Description

The Method of Reducing Fax Negotiation Frame Collision

technical field

The invention relates to facsimile technology, in particular to a method for reducing collision of facsimile negotiation frames.

Background technique

Facsimile communication is a communication method that uses scanning and photoelectric conversion technology to send static images such as text, pictures, and photos from the source to the receiving end through wired or wireless channels, and reproduce the still images at the receiving end. Since the 1970s, due to the opening of the file fax service on the Public Switched Telephone Network (PSTN), fax communication has been vigorously developed and has become one of the means for people to transmit information.

Referring to the fax network diagram shown in Figure 1, the fax terminal on the PSTN side is directly connected to the PSTN network, and negotiates and communicates with other fax terminals through the PSTN network; the fax terminal on the mobile side connects to a fixed wireless terminal (FWT) or mobile terminal (MS ) is connected to the mobile network, and negotiates and communicates with other fax terminals through the mobile network. In order to ensure that the fax can be negotiated normally in the mobile network, an interworking function module (InterWorking Function, IWF) specially used to process the fax service is usually integrated in the Mobile Switching Center (MSC), and the IWF transmits the fax call signaling and data It is equivalent to playing the role of a gateway, and its function is similar to that of the PSTN gateway. Among them, the IWF, PSTN gateway, FWT and MS can all be called transit devices.

Referring to the basic facsimile communication process shown in FIG. 2 , after the call is connected between the calling party and the called party, negotiation communication is performed through the interaction of multiple fax negotiation frames. First, the called party sends a digital identification signal (DIS) indicating its own performance to the calling party; after receiving the DIS, the calling party returns a digital command signal (DCS) to the called party, which includes information such as encoding mode, transmission rate, scanning density, etc. ; Immediately following the DCS, the calling party sends a training sequence (TCF) to the called party to detect whether the link quality can meet the quality requirements for fax page transmission; after the called party receives the TCF, it detects the TCF and judges whether the link quality is Can meet the requirements, if so, then return to the caller can receive confirmation (CFR), request the caller to start sending messages, otherwise, return training failure (FTT) to the caller, request the caller to retrain; the caller receives the CFR After that, start to send messages by page, and the called party will receive them; if there are multiple pages of data to be sent, the calling party will send a multi-page signal (MPS) to the called party; if all the data has been sent, the calling party will send an MPS signal to the called party End of process (EOP); after the called party receives MPS or EOP, it judges whether the quality of the received page is good, if it is good, it returns a message confirmation (MCF) to the calling party, otherwise, it returns negative retraining/acceptance retraining Training (RTN/RTP); Finally, the caller sends a disconnect connection (DCN) to the called party to end the entire fax process.

In order to ensure the normal progress of fax communication, the fax protocol stipulates that after the fax terminal sends a fax command frame, if it has not received a response frame within a certain period of time, it will resend the same command frame. For example, see Figure 3. After the calling and called lines are connected, the called sends a DIS to the calling. Send DIS.

With the development of mobile networks and the evolution of fixed networks, the fax network is becoming more and more complex. The influence of various factors such as wireless link delay and IP bearer in the fax communication process makes the end-to-end delay of fax more and more , such as satellite fax, long-distance fax, etc. Since the existing fax protocol is a half-duplex protocol, the fax terminal cannot send and receive fax negotiation frames at the same time. Therefore, excessive fax delays can easily cause collisions of fax negotiation frames. For example, as shown in Figure 3, due to delay Large, the called party resends the DIS and the calling party responds to the DCS during transmission, which causes the fax to fail.

Contents of the invention

In view of this, the object of the present invention is to provide a method for reducing the collision of fax negotiation frames, reduce the collision between fax negotiation frames, and improve the success rate of fax.

In order to achieve the above object, the technical scheme provided by the invention is as follows:

In the fax process, the end-to-end fax process between the calling party and the called party is decomposed into two independent sub-processes through the transfer device. The transfer device controls the time for sending fax negotiation frames to the calling party and the called party, respectively The calling party and the called party negotiate and communicate; after receiving the digital command signal DCS from the calling party, the transfer device directly returns the receiving confirmation CFR to the calling party, then stores the message sent by the calling party, and After receiving the CFR from the called party, forward the stored message from the calling party to the called party.

Preferably, the control of the time for the transfer device to send fax negotiation frames to the calling party and the called party includes: after the fax call is connected, the transfer device constructs a DIS to send to the calling party, and after receiving the DCS from the calling party, sends a message to the calling party. The caller returns the CFR, and after receiving the DIS from the called party, sends the received DCS to the called party.

Preferably, the time for the transfer device to control sending fax negotiation frames to the calling party and the called party includes: after the transfer device receives the DIS from the called party, it forwards the received DIS to the calling party, and after receiving the DIS from the calling party After receiving the DCS, return the CFR to the calling party, and after receiving the DIS from the called party, send the received DCS to the called party.

Preferably, the control of the time for the transfer device to send the fax negotiation frame to the calling party and the called party includes: the transfer device constructs a DIS to send to the calling party, returns a CFR to the calling party after receiving the DCS from the calling party, and After receiving the DIS from the called party, construct a DCS and send it to the called party.

Wherein, after the transfer device receives the DIS from the called party, sending the received DCS to the called party includes: after the transfer device receives the DCS from the calling party, it judges that the current time is far from the last time it received the DCS from the called party. Whether the time of DIS is within the expected collision-free time window, if yes, send the received DCS to the called party directly; otherwise, after receiving the DIS from the called party next time, send the received DCS to be called.

For the first preferred solution, when the rate in the DCS received by the relay device from the calling party is higher than the rate in the DIS from the called party, the method further includes: after the relay device receives the DCS from the calling party, Return the FTT to the calling party, modify the rate in the DCS according to the rate in the DIS, and send the modified DCS to the called party. For the first preferred solution, when the rate in the DCS received by the relay device from the calling party is lower than the rate in the DIS from the called party, the method further includes: after the relay device receives the DCS from the calling party, Forward the received DCS to the called party.

For the first preferred solution, when the format of the DCS received by the relay device from the calling party is inconsistent with the message format in the DIS from the called party, the method further includes: the relay device directly forwards the received DCS to the called party .

For the first preferred solution, when the format of the DCS from the calling party received by the relay device is inconsistent with the message format in the DIS from the called party, the method further includes: the relay device forwards the DIS from the called party to the calling party .

Preferably, the time for the transfer device to control sending fax negotiation frames to the calling party and the called party includes: after the transfer device receives the MPS or EOP from the calling party, it returns the MCF to the calling party directly; and forwards the message to the called party After calling, send MPS or EOP to the called party.

For the fourth preferred solution, when the relay device receives the RTN/RTP from the called party, the method further includes: after the relay device receives the RTN/RTP, resends the DCS to the called party, and stores the RTN/RTP sent by the calling party. message, after the calling party sends the message, it responds to RTN/RTP to the MPS from the calling party, and after receiving the DCS sent by the calling party, returns FTT or CFR, and after receiving the CFR sent by the called party, forward the stored message to the called party.

The method provided by the present invention further includes: the calling party sends a disconnection request to the switching center when the fax ends; the switching center forwards the disconnection request to the transfer device after receiving the disconnection request; After receiving the disconnection response from the transfer device, the switching center sends a disconnection request to the called party; after receiving the disconnection request, the called party returns a disconnection response to the switching center; the switching center After receiving the disconnection response from the called party, return the disconnection response to the calling party to complete the disconnection operation.

Wherein, the switching center is an MSC, or a PSTN signaling control module, or a FWT signaling control module, or an MS signaling control module.

The transit device is an IWF, or a PSTN gateway, or a FWT, or an MS.

It can be seen that the present invention decomposes the end-to-end facsimile process between the calling party and the called party into two mutually independent sub-processes through the transfer device, and the transfer device controls the time to send the fax negotiation frame to the calling party and the called party. This enables the transit device to negotiate and communicate with the calling party and the called party respectively. From the perspective of delay, negotiating separately is equivalent to decomposing a large delay into several smaller delays, which can eliminate the impact of excessive fax delay and reduce the collision of fax negotiation frames. Thereby improving the fax success rate.

Description of drawings

FIG. 1 is a schematic diagram of a facsimile network in the prior art;

FIG. 2 is a schematic diagram of the basic facsimile communication process in the prior art;

FIG. 3 is a schematic diagram of collision of fax negotiation frames in the prior art;

Fig. 4 is the facsimile communication flowchart in the embodiment of the present invention;

FIG. 5 is a schematic diagram of a facsimile communication process in an embodiment of the present invention;

FIG. 6 is a schematic diagram of the processing process when the initial negotiation rate is inconsistent in an embodiment of the present invention;

FIG. 7 is a schematic diagram of the processing process when the called party responds to RTN/RTP in the embodiment of the present invention;

Fig. 8 is a flowchart of disconnection in the embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and examples.

The basic idea of the present invention is: the end-to-end facsimile process between the calling party and the called party is decomposed into two mutually independent sub-processes through the transfer device, and the transfer device controls the time for sending the fax negotiation frame to the calling party and the called party, Negotiate and communicate with the calling party and the called party respectively.

Referring to the facsimile communication flowchart shown in FIG. 4 and the facsimile communication process schematic diagram shown in FIG. 5, the facsimile communication process in this embodiment mainly includes the following steps:

Step 401: After the facsimile call is connected, the relay device constructs a DIS according to the actual situation of the system and sends it to the calling party while waiting for the called party's DIS. For example, construct a DIS that describes the maximum capability supported by the system, that is, construct the DIS according to the maximum fax rate supported by the system.

Step 402: After the transit device receives the DCS from the calling party, it returns the CFR to the calling party, and judges whether the time between the current time and the last time it received the DIS from the called party is within the expected time window without collision, if If yes, execute step 403; otherwise, execute step 404.

Step 403: The transit device directly sends the received DCS to the called party, and then executes Step 405.

Step 404: After receiving the DIS from the called party next time, the transit device sends the received DCS to the called party, and then executes Step 405.

In addition, in addition to constructing a DIS to send to the calling party, the transit device can also construct a DCS to send to the called party instead of forwarding the DCS sent by the calling party. That is to say, the transit device constructs a DIS to send to the calling party, returns a CFR to the calling party after receiving the DCS from the calling party, and constructs a DCS to send to the calling party after receiving the DIS from the called party.

Step 405: After receiving the CFR from the called party, the transit device forwards the received message from the calling party to the called party.

Step 406: After receiving the MPS or EOP from the calling party, the transit device directly replies the MCF to the calling party; and after the message is forwarded, sends the MPS or EOP to the called party according to the caller's message end instruction.

That is to say, if the calling party sends MPS, the transit device sends MPS to the called party after the packet is forwarded; if the calling party sends EOP, the transit device sends EOP to the called party after the message is forwarded.

In addition, regarding the situation that the calling party has multiple pages of messages to be transmitted, the processing of each page of messages by the transit device is similar to the above steps, and will not be repeated here. The difference is that, for the first page of messages, the transit device forwards them to the called party after receiving the CFR from the called party; for subsequent messages, the transit device forwards them to the called party after receiving the MCF from the called party.

Step 407: After the message transmission is completed, the entire fax process is ended.

It should be noted that the processing methods for each fax negotiation frame shown in FIG. 4 and FIG. 5 can be used together or separately. For example, only the DIS and the DCS are separately negotiated to avoid the collision of the DIS and the DCS; or only the MPS/EOP and the MCF are separately negotiated to avoid the MPS/EOP and the MCF collision.

It can be seen from the above description that during the fax process, the relay device can avoid collisions between fax negotiation frames by negotiating with the calling party and the called party respectively. Problems such as inconsistent negotiation results of the called party occur. Several possible problems will be described in detail below.

1. The negotiation rate is inconsistent at the initial stage.

The transmission rate specified in the DCS received by the transit device from the calling party may be inconsistent with the transmission rate specified in the DIS from the called party. In this way, the timing difference between the transfer device and the calling party, and between the transfer device and the called party will be too large, which will affect the real-time performance of the fax.

At this time, the following methods can be used to deal with it: If the rate in the DCS received by the transfer device from the calling party is higher than the rate in the DIS from the called party, as shown in Figure 6, the transfer device will send a call to the caller after receiving the DCS Send FTT back, request the calling party to reduce the rate, modify the rate in DCS according to the rate in DIS, and send the modified DCS to the called party; if the rate in DCS is lower than the rate in DIS, the transit device will receive The DCS forwarded to the called party, instructing the called party to use the rate in the DCS. Through this method, the transmission rates of the calling party and the called party can be coordinated, so that the timing between the transfer device and the caller, and the transfer device and the called party can be basically the same, avoiding adverse effects on the real-time performance of the fax.

In addition, there is another situation: the DCS received by the transit device from the calling party is inconsistent with the provisions on other information such as message format in the DIS from the called party. For this situation, the transfer device can have two processing methods, one is to directly forward the received DCS to the called party; the other is to discard the DCS sent by the calling party and forward the DIS from the called party to the calling party. Which method to use in actual application depends on the content of the called DIS.

In order to solve the problem of inconsistent negotiation rates at the initial stage, in step 401, the transit device may not construct a DIS to send to the calling party, but directly forward the received DIS to the calling party after receiving the DIS from the called party , the subsequent related steps are the same as those in Figure 4.

2. The called party responds to RTN/RTP.

After the transmission of a page message is completed, the called party may respond RTN/RTP to the received MPS. Since the transit device has already replied the MCF to the calling party after receiving the MPS from the calling party, this may cause the receiving rate of the called party to be lower than the sending rate of the calling party, resulting in a large backlog of message data on the transiting device or causing the called early stitch removal.

At this time, as shown in Figure 7, it can be solved by the following method: after the transfer device receives the RTN/RTP, it resends the DCS retraining to the called party to reduce the message transmission rate between the transfer device and the called party; and, The transit device stores the message sent by the caller after replying to the MCF to the caller. After the caller sends the message, it responds to the MPS sent by the caller with RTN/RTP, and receives the DCS sent by the caller. Finally, according to the response of the called party to resending DCS, return FTT or CFR to the calling party to reduce the sending rate of the calling party, so that the sending rate of the calling party is consistent with the receiving rate of the called party. After receiving the incoming CFR, forward the stored message to the called party. Wherein, the return of FTT or CFR to the calling party according to the response of the called party to the resending DCS refers to that if the transfer device receives the FTT from the called party after resending the DCS to the called party, the transfer device receives the FTT from the callee After the calling party receives the DCS, it returns FTT to the calling party; if the transit device receives the CFR from the called party after resending the DCS to the called party, the transit device returns the CFR to the calling party after receiving the DCS from the calling party .

Third, the thread removal problem.

The transfer device negotiates with the calling party and the called party separately, which may lead to inconsistent timing of interaction between the transfer device and the calling party, and between the transfer device and the called party. For example, when the calling party has finished sending the message, the called party is still receiving the message. If the calling party initiates a disconnection request at this time, according to the existing protocol, the switching center will immediately forward the received disconnection request to the called party, and then disconnect the answer. This will inevitably cause the called party to disconnect immediately, so that the message cannot be received completely.

The NO.7 signaling system stipulates that the disconnection operation must wait for the disconnection request to be answered before it can be completed. Therefore, as shown in Figure 8, the disconnection initiated by the calling party can be processed through the following steps:

Step 801: the calling party sends a disconnection request (Release_Req) to the switching center when the fax ends.

Step 802: After receiving the disconnection request, the switching center forwards the disconnection request to the transfer device to apply for whether disconnection is possible.

Step 803: After receiving the called message, the transit device returns a release acknowledgment (Release_Ack) to the switching center.

Step 804: After receiving the disconnection response from the transit device, the switching center sends a disconnection request to the called party.

Step 805: After receiving the disconnection request, the called party returns a disconnection response to the switching center.

Step 806: After receiving the disconnection response from the called party, the switching center returns a disconnection response to the calling party to complete the disconnection operation.

For the disconnection initiated by the called party, it is considered that the facsimile process is interrupted, and the switching network immediately forwards the received disconnection request to the called party. The specific processing process is the same as that of the prior art, and will not be repeated here.

The transit device mentioned in this article is IWF, PSTN gateway, FWT or MS, etc. For example, for a mobile network, the transit device is IWF, and the switching center is MSC; for a PSTN network, the transit device is a PSTN gateway, and the switching center is a PSTN signaling control module; for FWT or MS, the transit device is specifically the FWT or MS Fax relay function module, switching center is the signaling control module of FWT or MS.

It can be seen that the method provided by the present invention can reduce the collision between fax negotiation frames caused by excessive time delay and improve the success rate of fax.

The purpose, technical solutions and beneficial effects of the present invention have been further described in detail above. It should be understood that the above description is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. shall be included in the protection scope of the present invention.

Claims (15)

1, a kind of method that reduces facsimile negotiation frame collision, it is characterized in that, in facsimile posting, by transferring equipment with caller and called between end-to-end facsimile posting be decomposed into two separate subprocess, transferring equipment control was communicated by letter with called holding consultation with caller respectively to the time of caller and called transmission facsimile negotiation frame;

Described transferring equipment behind the digital command signal DCS that receives from caller, but directly return confirmation of receipt CFR to caller, store the message that caller is sent then, and after receiving from called CFR, be transmitted to the message from caller of storage called.

2, method according to claim 1, it is characterized in that, described transferring equipment control comprised to the time of caller and called transmission facsimile negotiation frame: after facsimile call is connected, transferring equipment structure digital identification signal DIS sends to caller, behind the digital command signal DCS that receives from caller, but return confirmation of receipt CFR to caller, and after receiving, send to the DCS that receives called from called DIS.

3, method according to claim 1, it is characterized in that, described transferring equipment control comprised to the time of caller and called transmission facsimile negotiation frame: after transferring equipment is received from called DIS, the DIS that receives is transmitted to caller, behind the DCS that receives from caller, return CFR to caller, and after receiving, send to the DCS that receives called from called DIS.

4, method according to claim 1, it is characterized in that, described transferring equipment control comprised to the time of caller and called transmission facsimile negotiation frame: transferring equipment structure DIS sends to caller, behind the DCS that receives from caller, return CFR to caller, and after receiving the called DIS that sends, structure DCS sends to called.

5, according to claim 2 or 3 described methods, it is characterized in that, described transferring equipment is after receiving from called DIS, the DCS that receives is sent to called comprising: after transferring equipment is received DCS from caller, judge the current time apart from received last time from time of called DIS whether in the time window that can not bump of expection, if then directly send to the DCS that receives called; Otherwise, after receiving from called DIS next time, send to the DCS that receives called.

6, method according to claim 2, it is characterized in that, when the speed among the DCS of caller that transferring equipment is received is higher than from the speed among the called DIS, this method further comprises: after transferring equipment is received DCS from caller, return failure to train FTT to caller, and, send to amended DCS called according to the speed among the modifying rates DCS among the DIS.

7, method according to claim 2, it is characterized in that, when the speed among the DCS of caller that transferring equipment is received was lower than from the speed among the called DIS, this method further comprised: transferring equipment is transmitted to the DCS that receives called after receiving DCS from caller.

8, method according to claim 2 is characterized in that, transferring equipment receive from the DCS of caller with from the message format among the called DIS when inconsistent, this method further comprises: transferring equipment directly is transmitted to the DCS that receives called.

9, method according to claim 2 is characterized in that, transferring equipment receive from the DCS of caller with from the message format among the called DIS when inconsistent, this method further comprises: transferring equipment will be transmitted to caller from called DIS.

10, method according to claim 1, it is characterized in that, described transferring equipment control comprised to the time of caller and called transmission facsimile negotiation frame: transferring equipment is received from behind the multipage signal MPS of caller or the process end EOP, is directly confirmed MCF to the caller returned packet; And after message is transmitted to called finishing, to called transmission MPS or EOP.

11, method according to claim 10, it is characterized in that, when transferring equipment is received and is negated from called receiving that training/receiving again is sure trains RTN/RTP again, this method further comprises: after transferring equipment is received RTN/RTP, to called repeating transmission DCS, and the message that sends of storage caller, after caller sends message, to MPS response RTN/RTP from caller, and after receiving the DCS that caller is sent, according to called the response of retransmitting DCS is returned FTT or CFR to caller, and after receiving the called CFR that sends, be transmitted to the message of storing called.

12, method according to claim 1 is characterized in that, this method further comprises: caller sends the request of taking out stitches to switching center when fax completion; After the request of taking out stitches is received by switching center, transmit the request of taking out stitches to transferring equipment; Transferring equipment is returned to take out stitches to switching center and is replied after called message receives; After switching center receives and replys from taking out stitches of transferring equipment, to the called transmission request of taking out stitches; Called receive the request of taking out stitches after, return to take out stitches to switching center and reply; After switching center receives and replys from called taking out stitches, return to take out stitches to caller and reply, finish the operation of taking out stitches.

13, method according to claim 12, it is characterized in that described switching center is a moving exchanging center MSC or for public switched telephone network pstn signaling control module or for the signaling control module of wireless fixed terminal FWT or be the signaling control module of mobile terminal MS.

14, according to claim 1,2,3,4,6,7,8,9,10,11 or 12 described methods, it is characterized in that described transferring equipment is IWF module I WF or for public switched telephone network PSTN gateway or for wireless fixed terminal FWT or for mobile terminal MS.

15, method according to claim 5 is characterized in that, described transferring equipment is IWF module I WF or for public switched telephone network PSTN gateway or for wireless fixed terminal FWT or for mobile terminal MS.

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