CN1407834A - Method for realizing transmission of time division multichannel pulse modified signals in ether network - Google Patents

Abstract

The invention provides a method for transmitting a time-division multi-channel pulse code modulation signal in Ethernet, by constructing the input time-division multi-channel pulse code modulation signal into a data packet that can be transmitted in Ethernet at the sending end, and then at the receiving end The buffer area at the terminal is restored to a time-division multi-channel pulse code modulation signal through receiving processing and parallel-to-serial conversion, and completes the transmission in the Ethernet. The invention realizes the transmission of voice service and data service on the Ethernet, and controls and processes the delay jitter and packet loss of the voice service during transmission. By adopting the method of the invention, the Ethernet can give full play to its flexible networking characteristics in the metropolitan area network, realize voice services, and reduce network construction costs.

Description

Realization of Time Division Multi-channel Pulse Code Modulation Signal Transmission in Ethernet

technical field

The invention relates to a transmission method of time-division multi-channel (TDM) pulse code modulation (PCM) signals, in particular to a realization method for converting the time-division multi-channel PCM signals so that they can be transmitted in the Ethernet.

Background technique

At present, between digital program-controlled telephone exchanges and other telephone user access equipment or between transmission equipment, communication is carried out through time division (TDM) multiplexing of pulse code modulation signals, and time division multi-channel PCM signals are strictly in accordance with transmitted in synchronous timing. As the proportion of data services in the backbone communication network is increasing, the integration of voice services and data services is required, and data services are mainly transmitted and exchanged in the form of data packets (PACKET), and the transmission of data packets is asynchronous. Therefore, it is meaningful to study how to eliminate the effects of delay jitter and packet loss by transmitting time-division multi-channel PCM signals through data packets. Ethernet is a widely used data packet transmission method, which has the advantages of convenient networking, simple structure, and low cost. With the application of Ethernet in the broadband metropolitan area network, if the connection between digital program-controlled telephone switches and other telephone user access equipment or transmission equipment can pass through Ethernet, it will be conducive to flexible networking and reduce construction investment and network fusion.

Contents of the invention

The technical problem solved by the present invention is to provide a method for transmitting a time-division multi-channel pulse code modulation signal in Ethernet, so that the time-division multi-channel PCM signal can be conveniently transmitted in Ethernet after conversion processing, and then on the receiving side via Restore processing to the original time-division multi-channel PCM signal.

The realization steps of the realization method of a kind of time-division multi-channel pulse code modulation signal transmission in Ethernet of the present invention are as follows:

Step 1: Store each time-division multi-channel pulse code modulation signal into the buffer area by frame through the corresponding serial-to-parallel first-in-first-out buffer (FIFO);

Step 2: Composing the signal data in the buffer area in step 1 into an Ethernet packet;

Step 3: Send the Ethernet packet constructed in Step 2 to the receiving end of Ethernet;

Step 4: The receiving end receives the Ethernet data packet sent by the sending end;

Step 5: The receiving end extracts the data in the data area of the Ethernet packet and saves it in the receiving buffer;

Step 6: Restore the signal data corresponding to each time-division multi-channel pulse code modulation signal in the receiving buffer area to a time-division multi-channel pulse code modulation signal through the corresponding parallel-to-serial first-in-first-out buffer, and clear the corresponding The data area to complete the signal transmission in the Ethernet.

Each time-division multi-channel pulse code modulation signal corresponds to a serial-to-parallel FIFO buffer and a parallel-to-serial FIFO buffer.

In said step 2, first: an information body composed of frames of N ₁ time-division multi-channel pulse code modulation signals, a sequence number N representing each of said time-division multi-channel pulse code modulation signals, and a representation whose number is N ₂ The cyclic sequence numbers of the Ethernet packets form the Ethernet packet data area, and then combine with the other parts of the Ethernet packet to form an Ethernet data packet.

In the said step 5, after receiving the Ethernet packet, the receiving end does not check and extracts the data and the cyclic sequence number in the data area, and presses the sequence number and the packet cyclic sequence of each time-division multi-channel pulse code modulation signal represented in the data area Store the data into the corresponding receive buffer.

The value of the number _N1 of frames of the time-division multi-channel pulse code modulation signal for constructing an Ethernet data packet is not less than 2.

Each receiving buffer area is equally divided into _N3 receiving buffer subareas, _N2 is a multiple of N3 whose value is not less than ₃ , and the information body of the Ethernet packet is respectively put into _N3 according to the order of the packet cycle sequence number In the receiving buffer sub-areas, each sub-area places the information bodies of N ₂ /N ₃ Ethernet packets connected with the packet cycle sequence numbers.

Set a receiving buffer sub-area completion pointer, when the receiving buffer sub-area X receives the Ethernet packet of the last cyclic sequence number of the sub-area or receives the Ethernet packet of any cyclic sequence number in the buffer sub-area X+1 When receiving a package, if there is data in the cache subarea X-1, the receiving cache subarea completion pointer points to the cache subarea X-1; if there is no data in the cache subarea X-1, then when the cache subarea X+1 When the Ethernet packet with the last cyclic sequence number or any Ethernet packet with a cyclic sequence number in the buffer sub-area X+2 is received, the completion pointer of the received buffer sub-area points to the buffer sub-area X.

When X is N ₃ -1, then X-1 is N ₃ -2, X+1 is N ₃ , and X+2 is 1; if X is N ₃ , then X-1 above is N ₃ -1, X+1 is 1, and X+2 is 2.

When the completion pointer of the receiving buffer sub-area points to a certain buffer sub-area, if some Ethernet packets with cyclic sequence numbers in the sub-area are not received, a specific noise packet is used to fill it.

When the receiving cache sub-area receives a repeated cycle sequence number Ethernet packet before the data reception is completed, the previous packet is refreshed with the repeated subsequent packet.

Description of drawings

Fig. 1 is the realization method schematic diagram of the present invention to time division multi-channel PCM signal transmission in Ethernet;

Fig. 2 is the flow chart of the receiving method of time-division multi-channel pulse coded digital signal transmission in Ethernet of the present invention;

Fig. 3 is the flow chart of the sending method of time-division multi-channel pulse coded digital signal transmission in Ethernet of the present invention;

Detailed ways

The method flow of the present invention will be briefly introduced below. With reference to the schematic diagram of the implementation method of the present invention shown in FIG. The Ethernet packet, then reaches the Ethernet receiving end through Ethernet transmission and switching, stores the TDM-PCM signal information body that composes the Ethernet packet in the receiving buffer, and then performs receiving processing to send the data to the corresponding parallel-to-serial conversion The FIFO is reduced to a TDM-PCM signal.

The transmission and switching of Ethernet is a two-way communication circuit, the implementation method of the present invention is the same for the uplink and downlink directions, and only one of them is illustrated in FIG. 1 .

A specific example will be used to further illustrate below. The first time-division multi-channel PCM rate in Figure 1 is 2.048 megabits per second, and the length of a frame is 125 microseconds with a total of 32 time slots and 32 bytes; refer to the TDM-PCM signal at the sending end as shown in Figure 2 Through the serial-to-parallel conversion FIFO, take N ₁ =8, N ₂ =12, N ₃ =4; the header of 2 bytes is the serial number of the time-division multi-channel PCM signal, and the serial number N is 01; the Ethernet transmission delay is 1 millisecond. In this way, an Ethernet packet is 22+2+256+2=282 bytes. After completion, the time-division multi-channel PCM signal enters the sending FIFO buffer, and then is encapsulated into an Ethernet packet and sent to the Ethernet.

As shown in Fig. 3, at the receiving end, after receiving the Ethernet packet, the receiving end does not perform verification to extract the sequence number, 256 byte data and packet cycle sequence number of the time-division multi-channel PCM signal in the data area, and divide the data by time-division multi-channel The sequence number of the PCM and the sequence number of the packet cycle store the data into the corresponding 12 receiving buffer areas with a data size of 256 bytes.

Because there are different delays and packet loss phenomena in Ethernet transmission, in order to eliminate these effects, the receiving buffer area is divided into 1, 2, 3, and 4 areas, and each area can store 3 Ethernet packets. The data. Determine-receipt decision rule:

In the initial stage, if there is data in zone 1, it points to zone 1 when the last packet with sequence number 6 in zone 2 is received or any packet with a cyclic sequence number in zone 3 is received in the initial stage; If there is no data in area 1, it will point to area 2 when the packet with the last cycle sequence number 9 in area 3 is received or any packet with a cycle sequence number in area 4 is received; if there is no data in area 2, it will point to area 2 If the packet with the last cycle sequence number 12 is received or any packet with a cycle sequence number in zone 1 is received, it is judged to point to zone 3; if there is no data in zone 3, the packet with the last cycle sequence number 3 in zone 1 is used Received or any cyclic sequence number packet in zone 2 is received, it is judged to point to zone 4, and then moves circularly.

If there is data in area 1, when the packet with the last cycle sequence number 6 in area 2 is received or any packet with a cycle sequence number in area 3 is received, it is judged that the data reception in area 1 is complete, and if Packets with certain serial numbers in area 1 that have not been received will be treated as packet loss, filled with a specific noise packet, and then put the data in area 1 into the first-in-first-out buffer of the No. No. 1 multi-channel pulse-coded digital signal clears the data in area 1 at the same time. If a repeated cycle sequence number packet is received in this area before the data reception is completed, the old packet will be refreshed with the last received packet.

Similarly, the completion of data reception in zone 2 is determined by the receipt of the packet with the last cyclic sequence number 9 in zone 3 or the receipt of any packet with a cyclic sequence number in zone 4; the completion of data reception in zone 3 is determined by the last A packet with a cyclic sequence number of 12 is received or any packet with a cyclic sequence number in area 1 is received as a decision; data reception in area 4 is completed when the last packet with a cyclic sequence number 3 in area 1 is received or in area 2 Any one of the cyclic sequence number packets is received as a decision; packet loss and received duplicate packets are processed in the same way as in area 1.

The average delay of the system is equal to N ₁ times 125 microseconds plus 2 times 125 times N ₁ times N ₂ divided by N ₃ microseconds plus the Ethernet transmission delay. In this example, the average delay of the system is equal to 8 times 125 microseconds plus 2 times 125 times 8 times 12 divided by 4 microseconds plus Ethernet transmission delay of 1 millisecond = 8 milliseconds is acceptable.

The processing process for the time-division multi-channel PCM signal of other serial numbers is the same as the above method, and will not be repeated here.

Bit errors may occur due to delay jitter and packet loss in Ethernet. However, if the Ethernet bandwidth is sufficient and the Ethernet switch is non-blocking in the future, as well as setting appropriate values of N ₁ , N ₂ , and N ₃ , the bit error rate can be greatly reduced. Since the noise packet filling method is used for packet loss, the impact on users can be ignored when the packet loss is not serious.

Claims (10)

1. the implementation method that time division multichannel pulse modified modulation signal transmits in Ethernet is characterized in that, realizes that the step of described method is:

Step 1: deposit the time division multichannel pulse modified modulation signal of each bar in buffer area frame by frame by corresponding deserialize first-in first-out buffer (FIFO);

Step 2: the signal data of the buffer area in the step 1 is formed the Ethernet data bag;

Step 3: the receiving terminal that the Ethernet data bag of structure in the step 2 is sent to Ethernet;

Step 4: the Ethernet data bag that the receiving terminal receiving end/sending end is sent;

Step 5: receiving terminal extracts Ethernet bag data field data, and is kept in the reception buffer area;

Step 6: the signal data in receiving buffer area with the time division multichannel pulse modified modulation signal correspondence of each bar passes through corresponding parallel change serial first-in first-out buffer respectively, revert to time division multichannel pulse modified modulation signal, and empty corresponding data field, finish the signal transmission in Ethernet.

2. the implementation method that a kind of time division multichannel pulse modified modulation signal according to claim 1 transmits in Ethernet, it is characterized in that the corresponding deserialize first-in first-out buffer of the time division multichannel pulse modified modulation signal of described each bar and the parallel serial first-in first-out buffer that becomes.

3. the implementation method that a kind of time division multichannel pulse modified modulation signal according to claim 1 transmits in Ethernet is characterized in that, in the described step 2, and first general: N ₁Sequence number N, a number of the information agent that the frame of individual time division multichannel pulse modified modulation signal constitutes, the time division multichannel pulse modified modulation signal of described each bar of expression are N ₂The cyclic sequence number of expression Ethernet bag sequencing form Ethernet bag data field, form an Ethernet data bag in conjunction with the other parts byte that constitutes the Ethernet bag again.

4. the implementation method that a kind of time division multichannel pulse modified modulation signal according to claim 3 transmits in Ethernet is characterized in that, the number N of the frame of the time division multichannel pulse modified modulation signal of an Ethernet data bag of described structure ₁Value be not less than 2.

5. the implementation method that a kind of time division multichannel pulse modified modulation signal according to claim 3 transmits in Ethernet, it is characterized in that, receiving terminal receives that not doing verification behind the Ethernet bag extracts in the data field data and cyclic sequence number in the described step 5, and data is deposited in the reception buffer area of correspondence by the sequence number of the time division multichannel pulse modified modulation signal of each bar of the expression in the data field and bag cyclic sequence number.

6. the implementation method that a kind of time division multichannel pulse modified modulation signal according to claim 5 transmits in Ethernet is characterized in that, described each reception buffer area all is divided into N ₃Individual reception buffer memory subarea, N ₂Be N ₃Multiple, the information agent of Ethernet bag is put into N respectively according to bag cyclic sequence order ₃In the individual reception buffer memory subarea, bag cyclic sequence number continuous N is placed in each subarea ₂/ N ₃The information agent of individual Ethernet bag.

7. the implementation method that a kind of time division multichannel pulse modified modulation signal according to claim 6 transmits in Ethernet, it is characterized in that, set a reception buffer memory subarea and finish pointer, when in receiving buffer memory subarea X, receiving the Ethernet bag of last cyclic sequence of this subarea number or receiving the Ethernet bag of any cyclic sequence number among the X+1 of buffer memory subarea, if among the X-1 of buffer memory subarea data are arranged, then receive the buffer memory subarea and finish pointed buffer memory subarea X-1; If do not have data among the X-1 of buffer memory subarea, then, receive the buffer memory subarea and finish pointed buffer memory subarea X when the Ethernet bag of last cyclic sequence among the X+1 of buffer memory subarea number or when receiving the Ethernet bag of any cyclic sequence number among the X+2 of buffer memory subarea.

8. the implementation method that a kind of time division multichannel pulse modified modulation signal according to claim 7 transmits in Ethernet is characterized in that described X is N ₃-1 o'clock, then X-1 was N ₃-2, X+1 is N ₃, X+2 is 1; As working as X is N ₃The time, then Shang Mian X-1 is N ₃-1, X+1 is 1, and X+2 is 2.

9. the implementation method that a kind of time division multichannel pulse modified modulation signal according to claim 7 transmits in Ethernet, it is characterized in that, when certain buffer memory subarea of pointed is finished in described reception buffer memory subarea, if the Ethernet bag of some cyclic sequence in this subarea number is not received, then fill up with a specific noise bag.

10. the implementation method that a kind of time division multichannel pulse modified modulation signal according to claim 7 transmits in Ethernet, it is characterized in that, when receiving the cyclic sequence Ethernet bag of repetition before described reception buffer memory subarea Data Receiving is finished, then refresh previous bag with a back bag that repeats.