WO2016000423A1

WO2016000423A1 - Delay compensation method and device

Info

Publication number: WO2016000423A1
Application number: PCT/CN2014/094269
Authority: WO
Inventors: 张雪
Original assignee: 中兴通讯股份有限公司
Priority date: 2014-06-30
Filing date: 2014-12-18
Publication date: 2016-01-07
Also published as: MY189564A; CN105323030A; RU2648285C1

Abstract

Provided are a delay compensation method and device. The method comprises: a following signal transmitted with a service signal is obtained in the process for transmitting the service signal from a first device to a second device; a first delay value brought by transmitting the following signal in the first device, and a second delay value brought by transmitting the following signal in the second device are respectively obtained; a first difference value between the first delay value and a preset delay value of the first device, and a second difference value between the second delay value and a preset delay value of the second device are obtained; the first difference value is inserted into the service signal and transmitted with the service signal to the second device; the first difference value is abstracted from the service signal on the second device, and a delay compensation value needed in the service signal transmission process is obtained according to the first difference value and the second difference value; delay compensation for the service signal in the service signal transmission process is performed according to the delay compensation value.

Description

Method and device for delay compensation

Technical field

The present invention relates to the field of communication optical transmission network OTN, and in particular, to a method and apparatus for delay compensation.

Background technique

With the advent of the 3G era, major communication operators have launched large-scale construction of 3G mobile communication networks, and the base station is the largest and most costly equipment for 3G network construction. The increasingly fierce competition in the field of mobile communications has made communication operators pay more attention to the cost of network construction than ever before. Distributed base stations have the characteristics of low cost, high performance and fast operation, which can greatly save operators' network construction and operation and maintenance costs. Therefore, distributed base stations have become the most important choice for current 3G network construction.

The core concept of the distributed base station is to separate the traditional macro base station baseband processing unit (BBU) and the radio remote unit (RRU), and the two are connected through optical fibers or bearer network devices. During the network deployment, the BBU, the core network, and the wireless network control device are centralized in the equipment room, and the RRUs deployed on the planning site are connected through optical fibers to complete network coverage.

Compared with the traditional base station solution, the distributed base station solution not only greatly reduces the dependence on the site equipment room, reduces the difficulty of deployment, but also effectively increases the network construction speed, which greatly saves the network construction cost and operation and maintenance cost for the operator. It meets the needs of operators for fast and low-cost network construction. Therefore, the network construction mode of distributed base stations has become an important choice for carrier base station deployment.

The distributed base station is implemented by using a Common Public Radio Interface (CPRI) to transmit digital baseband data to a remote radio remote unit (RRU) through a bearer network device. The public wireless interface specification CPRI is a standard interface for connecting BBUs and RRUs initiated by companies such as Ericsson, Huawei, NEC, Nortel Networks and Siemens. The CPRI interface can be used in a variety of 3G formats as well as future LTE. At present, both fiber direct drive and WDM/OTN technologies can meet the transmission requirements of CPRI. The use of the optical transport network OTN to carry the CPRI interface signal can improve the bandwidth utilization of the optical fiber, support longer-distance transmission, provide complete protection and rich optical layer management, support any topology networking, simplify operation and maintenance management, and simplify expansion. Can increase the speed of launching new wireless services; and use the optical transport network OTN to carry CPRI, It also extends the transmission distance and provides protection. Therefore, CPRI over OTN will be widely used by operators.

Before the wireless device does not use the distributed base station, the OTN device is not used in the case of the delay compensation mechanism implemented in the wireless device. With the large number of applications of the OTN device in the wireless communication, the OTN device is urgently needed to solve the delay. Problem (For the omnidirectional transmit network application technical requirements for mobile communication base stations, the transmission delay of each transmit channel at the antenna port needs to be synchronized within the allowable range value; that is, all RRUs must be synchronized and transmitted at the specified time) .

Summary of the invention

The embodiment of the invention provides a method and device for delay compensation, which can conveniently implement delay compensation of the bearer network device without affecting the function of the original device, so that the RRUs of all wireless devices are at a specified time. The purpose of intra-synchronous transmission.

A method of delay compensation, comprising:

Acquiring a follow signal of the following service signal transmission in the process of transmitting the service signal from the first device to the second device;

Obtaining, respectively, a first delay value generated by the following signal transmission in the first device and a second delay value generated by transmitting in the second device;

Obtaining a first difference between the first delay value and a first preset delay value of the first device, and the second delay value and a second preset delay value of the second device Second difference

Inserting the first difference into the service signal to transmit the service signal to the second device;

Extracting, by the second device, the first difference value from the service signal, and acquiring a delay compensation value required for a service signal transmission process according to the first difference value and the second difference value;

And delaying the service signal in the process of transmitting the service signal according to the delay compensation value.

Optionally, the step of separately acquiring the first delay value generated by the following signal transmission in the first device and the second delay value generated by transmitting in the second device includes:

Extracting the following signal at a first preset position of the first device, and acquiring information of the following signal at the first preset position;

Extracting the following signal at a second preset position of the first device to acquire the following signal Information at the second preset position;

And acquiring, according to the information of the following signals at the first preset position and the second preset position, a first delay value generated by the following signal transmitted in the first device.

Optionally, the step of separately acquiring the first delay value generated by the following signal transmission in the first device and the second delay value generated by transmitting in the second device further includes:

Extracting the following signal at a third preset position of the second device, and acquiring information of the following signal at the third preset position;

Extracting the following signal at a fourth preset position of the second device, and acquiring information of the following signal at the fourth preset position;

And acquiring, according to the information of the following signals at the third preset position and the fourth preset position, a second delay value generated by the following signal transmission in the second device.

Optionally, the first preset delay value of the first device is a maximum delay value measured by the first device in a preset time period; and the second preset delay of the second device is The value is the maximum delay value measured by the second device within a preset period of time.

Optionally, the formula for calculating the delay compensation value is:

Delay compensation value = (maximum delay value of the first device - first delay value) + (maximum delay value of the second device - second delay value).

Optionally, the step of delay compensation of the service signal transmission process according to the delay compensation value includes:

Delaying compensation of the service signal transmission process by a first-in first-out queue; wherein the delay compensation value is used to control the output of the first-in first-out queue.

Optionally, the step of using the delay compensation value to control an output of the first-in first-out queue includes:

And calculating, according to the read/write clock of the first-in first-out queue, the delay compensation value into a read/write clock period value of the N first-in first-out queues;

When the N service signals are written in the first-in first-out queue, the service signals are sequentially output.

The embodiment of the invention further provides a device for delay compensation, comprising:

The extracting module is configured to acquire a follow signal of the following service signal transmission during the process of transmitting the service signal from the first device to the second device;

a delay acquisition module, configured to respectively acquire a first delay value generated by the following signal transmission in the first device and a second delay value generated by transmitting in the second device;

a difference obtaining module, configured to obtain a first difference between the first delay value and a first preset delay value of the first device, and the second delay value and the second device a second difference of the second preset delay value;

Inserting a module, configured to insert the first difference into the service signal to transmit the service signal to the second device;

a compensation acquisition module, configured to extract the first difference value from the service signal on the second device, and obtain a delay compensation in a transmission process of the service signal according to the first difference value and the second difference value value;

The compensation module is configured to perform delay compensation on the service signal in the process of transmitting the service signal according to the delay compensation value.

Optionally, the delay obtaining module includes:

The first clock acquisition module is configured to extract the following signal at a first preset position of the first device, and acquire information of the following signal at the first preset position;

a second clock acquisition module, configured to extract the following signal at a second preset position of the first device, and acquire information of the following signal at the second preset position;

The first delay acquisition submodule is configured to acquire a first delay value generated by the following signal transmission in the first device according to the information of the following signal at the first preset position and the second preset position.

Optionally, the delay obtaining module further includes:

a third clock acquisition module, configured to extract the following signal at a third preset position of the second device, and acquire information of the following signal at the third preset position;

a fourth clock acquisition module, configured to extract the following signal at a fourth preset position of the second device, and acquire information of the following signal at the fourth preset position;

And a second delay acquisition submodule configured to acquire a second delay value generated by the following signal transmission in the second device according to the information of the following signal at the third preset position and the fourth preset position.

Optionally, the calculation formula of the delay compensation value is specifically:

Optionally, the compensation module includes:

The compensation submodule is configured to delay compensation of the service signal transmission process by using a first in first out queue; wherein the delay compensation value is used to control the output of the first in first out queue.

Optionally, the compensation submodule includes:

The scaling module is configured to convert the delay compensation value into a read/write clock period value of the N first-in first-out queues according to the read/write clock of the first-in first-out queue;

The output module is configured to sequentially output the service signals after writing N service signals in the first-in first-out queue.

In the method for delay compensation according to the embodiment of the present invention, the required delay compensation value during the transmission of the service signal is calculated by acquiring the delay value of the following signal transmitted by the following service signal in the first device and the second device. And delay compensation of the service signal; without affecting the function of the original device, the delay compensation of the bearer network device is conveniently implemented, so that the RRU of all the wireless devices are synchronously transmitted within the specified time. The technical requirements of the omnidirectional transmitting network to the mobile communication base station are satisfied.

BRIEF abstract

1 is a flow chart showing the basic steps of a method for delay compensation according to an embodiment of the present invention;

2 is a schematic diagram showing an application scenario of a method for delay compensation according to an embodiment of the present invention;

3 is a schematic diagram showing signal transmission of a method for delay compensation according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a network basic topology according to a specific embodiment 1 of the embodiment of the present invention;

FIG. 5 is a block diagram showing the access to the CPRI6 service according to the first embodiment of the present invention;

6 is a schematic diagram of a delay measurement path according to Embodiment 1 of the embodiment of the present invention;

7 is a block diagram showing an internal logic and a framer of an FPGA according to Embodiment 2 of the embodiment of the present invention;

FIG. 8 is a schematic diagram showing a relative position of a frame header of each point in a second embodiment of the embodiment of the present invention; FIG.

FIG. 9 is a schematic structural diagram of an apparatus for delay compensation according to an embodiment of the present invention.

Preferred embodiment of the invention

Specific embodiments of the present invention will be described in detail below with reference to the drawings. The features of the embodiments of the present invention and the embodiments may be arbitrarily combined with each other without conflict.

The embodiment of the present invention provides a method and a device for delay compensation by acquiring an following service signal transmission in the related art that the wireless device adopts an internal delay compensation mechanism and the delay between two separate devices cannot be solved. The delay value of the following signal in the first device and the second device calculates the required delay compensation value during the transmission of the service signal, and delays the service signal; and does not affect the function of the original device. In this case, the delay compensation of the bearer network device is conveniently implemented, so that the RRUs of all the wireless devices are synchronously transmitted within a specified time, and the technical requirements of the omnidirectional transmit network to the mobile communication base station are satisfied.

As shown in FIG. 1 , an embodiment of the present invention provides a method for delay compensation, including:

Step 1: acquiring, in a transmission process of the service signal from the first device to the second device, a follow signal that follows the service signal transmission;

Step 2: respectively acquiring a first delay value generated by the following signal transmission in the first device and a second delay value generated by transmitting in the second device;

Step 3: Obtain a first difference between the first delay value and a first preset delay value of the first device, and the second delay value and a second preset of the second device The second difference of the delay value;

Step 4: insert the first difference value into the service signal and transmit the service signal to the second device;

Step 5: Extract the first difference value from the service signal on the second device, and obtain a delay compensation value required for a service signal transmission process according to the first difference value and the second difference value;

Step 6. Perform delay compensation on the service signal in the process of transmitting the service signal according to the delay compensation value.

In the above embodiment of the present invention, the following signal in step 1 may be a certain signal related to the service extracted from the service signal, or may be other signals inserted into the service signal, as long as it can always follow the transmission of the service signal. The signals are applicable in the embodiments of the present invention. In step 2, the following signals are extracted in the first device and the second device respectively, and the transmission delays between the two signals in the first device and the second device are respectively measured. corresponding a first delay value and a second delay value; wherein the measurement of the first delay value and the second delay value is obtained by a clock counting method, that is, inserting a measurement clock during the entire process of the service signal transmission, according to The number of clocks between locations that need to be measured determines the delay value.

Since the first delay value in the first device and the second delay value in the second device are unstable, the delay value changes according to factors such as time and signal strength, so in order to ensure the stability of the delay First, the first preset delay value of the first device and the second preset delay value of the second device are preset, and the corresponding difference between the real-time delay value and the preset delay value is obtained through step 3. That is, the first difference value and the second difference value; wherein the first preset delay value and the second preset delay value are specifically obtained by using a large amount of experimental data, and may also pass the theory of the first device or the second device. The parameters are calculated by numerical calculation, and are not limited to a fixed manner. All the manners that can correctly obtain the first preset delay value and the second preset delay value are applicable in the embodiments of the present invention.

Wherein, step 6 compensates the service signal with the delay device or device according to the compensation value required for the delay obtained in step 5; wherein the delay device or device is a delay circuit, an FPGA device delay or a delay switch, etc. Wait, don't repeat them here. It should be noted that the method for delay compensation in the transmission process of the service signal transmitted from the first device to the second device is specifically described in the present invention. In practical applications, each device has a signal transmission in two directions. Both of them will generate delays, and delay compensation is required. Therefore, when using the delay device for compensation in step 6, the delays in the two directions of the device need to be compensated separately, so as to delay the transmission of the service signal. Stable.

In the above embodiment of the present invention, step 2 may include:

Step 21: Extract the following signal at a first preset position of the first device, and acquire information about the following signal at the first preset position;

Step 22: Extract the following signal at a second preset position of the first device, and obtain information about the following signal at the second preset position;

Step 23: Acquire a first delay value generated by the following signal transmission in the first device according to the information of the following signal at the first preset position and the second preset position.

Step 2 may also include:

Step 24, extracting the following signal at a third preset position of the second device, and acquiring information of the following signal at the third preset position;

Step 25: extract the following signal at a fourth preset position of the second device, and obtain the Following the information of the signal at the fourth preset position;

Step 26: Acquire a second delay value generated by the following signal transmission in the second device according to the information of the following signal at the third preset position and the fourth preset position.

In a specific embodiment of the present invention, steps 21 to 26 describe a step of acquiring a first delay value and a second delay value by using a clock counting method; wherein, in the process of transmitting a service signal, a measurement clock is inserted, optionally The measurement clock can use the system clock of the service signal transmission system, or can be a separately set clock, and is not limited to a fixed form.

Optionally, the first preset position and the second preset position of the first device are differently set according to different devices, and are not fixed to one position; the first clock information at the first preset position, that is, the first preset position is Corresponding position on the measurement clock, the second clock information in the second preset position, that is, the correspondence between the second preset position on the measurement clock; and then performing step 23, by calculating the first preset position on the measurement clock and The number of clocks between the two preset positions obtains a first delay value; for example, there are 4 measurement clock cycles between the first clock information and the second clock information, and the first delay value is 4 measurement clocks. The period value, specifically, the unit of the delay value is generally ns. The obtaining process of the second delay value is consistent with the obtaining process of the first delay value, and details are not described herein.

It should be noted that, in the embodiment of the present invention, after obtaining the first delay value of the first device, the delay compensation is not performed inside the first device, but the first delay value is inserted into the service signal and transmitted to the first In the second device, optionally, the first delay value uses a reserved overhead of the OTN to perform a delay value transmission method to implement interaction between two separate devices.

In the above embodiment of the present invention, the first preset delay value of the first device is a maximum delay value measured by the first device within a preset time period; and the second pre-second of the second device The delay value is a maximum delay value measured by the second device within a preset time period.

In the embodiment of the present invention, the method for obtaining the maximum delay value of the first device and the maximum delay value of the second device may be: by measuring a plurality of the same devices, and at least dropping the power and inserting and removing the optical fiber 100 times to obtain an experiment. Data, and then analyze its experimental data to get a more accurate maximum delay value.

In the above embodiment of the present invention, the calculation formula of the delay compensation value is:

It should be noted that the calculation formula of the foregoing delay compensation value in the embodiment of the present invention is only an optional embodiment of the present invention, and is not used to limit the protection scope of the present invention. Other algorithms capable of correctly calculating the delay compensation value are in this embodiment. Both of the embodiments of the invention are applicable.

In the above embodiment of the present invention, step 6 includes:

Step 61: Perform delay compensation on the service signal transmission process by using a first-in first-out queue; wherein the delay compensation value is used to control the output of the first-in first-out queue.

Among them, FIFO-first-in first-out queue, the abbreviation of First Input First Output, this is a traditional sequential execution method, the first entered instruction is completed and retired, followed by the second instruction. The principle of the first-in first-out queue is: the FIFO queue does not classify the message, and the FIFO enters the queue according to the order in which the message arrives at the interface. At the same time, the FIFO exits the queue in the order of the queue, advanced. The message will be sent out first, and the incoming message will be sent out.

In a specific embodiment of the present invention, the step of using the delay compensation value to control the output of the first in first out queue includes:

Step 62: Convert the delay compensation value into a read/write clock period value of the N first-in first-out queues according to the read/write clock of the first-in first-out queue; N is an integer greater than or equal to 1.

Step 63: After the N service signals are written in the first-in first-out queue, the service signals are sequentially output.

In the above example, in the specific application of the present invention, the first-in first-out queue FIFO is equivalent to a buffer. When the number of service signals in the FIFO is less than N, the FIFO does not read outward, and writes data to the FIFO; When the number of service signals in the FIFO is equal to N, a data is written into the FIFO, and the output of the FIFO reads out a data outward; it should be noted that the service signal is always transmitted, and the FIFO is constantly being continuously When the data is written, the FIFO will continuously read out the data; at the same time, since the number of service signals in the FIFO is equal to N, it is ensured that each service signal is output from the second device end with the maximum delay value, thereby ensuring The stability of the delay.

The read/write clock of the first-in first-out queue in the above embodiment of the present invention may also adopt a system clock or a clock consistent with the above-mentioned measurement clock. If the read/write clock of the first-in first-out queue is consistent with the measurement clock, the delay value and the delay compensation value can be directly calculated by using several times of the clock period value, without converting to a specific ns, and then step 62 The delay compensation value in the direct value is N clock cycle values, which simplifies the calculation steps.

The process of delay compensation of the present invention is described in detail in conjunction with application scenario 1, as shown in FIG. 2 and FIG. Show:

Application scenario As shown in FIG. 2, two devices (OTN device 1 and OTN device 2) in the bearer network are respectively applied between two terminal devices (external device 1 and external device 2), between the two terminal devices. When transmitting signals, there is often a requirement for delay stability. Therefore, the requirements for transmitting signals to the OTN equipment are stricter, and the OTN equipment needs to ensure the stability of the delay. In view of this, the present invention provides a method of delay compensation, as shown in FIG.

The first step is to extract or insert a signal covering the entire path that may cause a delay change in the board 1 and the board 2, and generally extract or insert a signal (following signal) upstream of the board 1 / board 2, The same signal is extracted downstream of the corresponding board 1/board 2, and the delay between the two signals is measured.

In the second step, the samples of the multiple boards are measured, and the maximum values measured by the delay measurement module 1 and the delay measurement module 2 are found in all the single board samples, and the maximum values of the delays of the device 1 and the device 2 are respectively defined as Ta_delay_max and Tb_delay_max.

In the third step, the delay values of the two boards, Ta_delay_now and Tb_delay_now, are measured after the board is powered. There are many measurement methods, such as measuring the time between the frame head of a frame and the time from the incoming device to the outgoing device.

In the fourth step, the delay value measured by the board 1 is transmitted to the board 2 through the service transmission, and then the delay value (Ta_delay_now) measured by the board 1 is extracted in the board 2.

In the fifth step, the value Ta_delay_now measured by the board 1 and the delay value Tb_delay_now of the board 2 are respectively compared with the maximum values of the delays (Ta_delay_max and Tb_delay_max), and the difference is seen, and then the delay compensation module is used to compensate the difference. Two differences.

Application example one

In the following, we take the example of carrying the CPRI6 service on the OTN board as an example to verify the practice of the method. The application block diagram is shown in Figure 4. The block diagram of the specific board service processing is shown in Figure 5.

The client side refers to the service that our board accesses, and the line side refers to the service that carries the CPRI. This refers to the OTN service. The business process is first processed by the FPGA logic for the customer service and the line side service, and then converted to an optical signal for transmission through the framer chip and then to the optical port.

First, it is necessary to measure which period has delay instability, and then the maximum value of the delay is obtained after multiple measurements. Here, the odu2 layer is sent to the line side, and there is a delay, which is passed through the board position. The odu2 frame header (fp1) and the frame header (fp2) at the exiting board position are measured and obtained. The logic module that implements this measurement is the delay measurement module 1, and the measured first delay value is Ta_delay_now.

Secondly, the two boards are connected by optical fibers. Taking OTN as an example, the measured first delay value Ta_delay_now can be transmitted to the downstream site for compensation through the OTN overhead or the payload area.

Then, on the line side, the delay of the client side is received, and the measurement is obtained by the frame header (fp3) of the board position and the frame header (fp4) of the board position. The logic module that implements this measurement is the delay measurement module 2, and the measured second delay value is Tb_delay_now.

Finally, the logic computes the two delay values from the maximum delay values (Ta_delay_max and Tb_delay_max) that have been extensively tested before, resulting in fifo_value. This delay value is then compensated by the delay compensation FIFO.

It should be noted that whether the clock of the measurement clock and the delay compensation FIFO is a clock is one of the factors that affect the time measurement error. In addition, the specific values of Ta_delay_max and Tb_delay_max need to be obtained by measuring a large number of single-plate sample combinations multiple times.

The delay measurement process is shown in Figure 6.

Analyze the delay variation of the OTN board and give a measure of the delay value Tdelay_now.

Figure 6 shows the entire service processing block diagram of the OTN board. The client side connects the 6.214 Gb/s CPRI6 service and the line side fiber loopback.

In order to determine which part of the delay instability is generated on the client side, the line side, the sfi4.2 interface or the inside of the framer, it is necessary to draw the corresponding test signal in the FPGA logic and the framer, and then use the logic internal Programming or chipscope captures the signals everywhere for testing.

Therefore, the frame header indication signals at four positions A, B, C, and D in Fig. 5 are found. Draw three test paths with red dashed lines and perform the following tests.

A position: In the FPGA logic, the signal extracted by the client side is transmitted.

B position: In the framer, the odu2 overhead inserts the header signal from the part, which is before the FEC encoding.

C position: In the framer, the frame header signal is extracted from the overhead extraction part, and this signal is after FEC decoding.

D position: In the FPGA logic, the signal extracted by the client side receiving side.

After determining the four positions of the extracted signals, according to FIG. 6, three test paths are determined, and the three paths cover the whole process of service processing:

Path 1: Contains all logic and SFI4.2 interfaces on the client side and line side as well as partial processing modules in the framer.

Path 2: Includes codec in the framer and optical module to fiber section.

Path 3: Contains some of the processing modules in the framer and the SFI4.2 interface and the receiving side line side and client side logic.

The conclusion obtained by the separate tests of the three paths is (the test method is not the main method of the present invention and will not be described in detail herein):

The delay variation mainly exists in path 1 and path 3. The delay variation of other paths can be neglected. Therefore, in order to facilitate the test,

compensation path

1 and 3 can realize the purpose of delay compensation. Therefore, add fifo on the receiving side of the FPGA line side to delay compensation, so that each power-on delay reaches the maximum value and is in a stable state.

It can be seen from the above that the first delay value Ta_delay_now and the second delay value Tb_delay_now after power-on are the delay values of path 1 and path 3, respectively. By compensating the two parts, the delay value reaches a steady state.

In the embodiment of the present invention, the delay value that Fifo needs to compensate is: Tdelay_offset={(Ta_delay_max-Ta_delay_now)+(Tb_delay_max-Tb_delay_now)}.

The read and write clocks of the FIFO are all system clocks. The fifo water level is controlled by Tdelay_offset. If the number of service signals is less than Tdelay_offset, the data is not read. The data is written to fifo. When the number of service signals is equal to Tdelay_offset, fifo starts to continuously Read data out. This ensures the stability of the delay.

This application example shows the measurement of the delay stability and the compensation method when the service board of the OTN device carries the cpri6 service. This method is also applicable to other rate services related to CPRI, such as CPRI2/CPRI3/CPRI4/CPRI5/CPRI6/CPRI7 services, and the whole process is basically the same as that of the first embodiment.

This method is also applicable to other service boards of the OTN equipment. In the FPGA service design, if there is a demand for delay stability, this method can be applied to compensate.

Application example two

The following boards carry synchronous Ethernet as an example to verify the feasibility of this method.

First, the service loopback determines that the client-side delay variation is stable. To determine whether the delay instability is generated at the SFI4.2 interface, or in the framer, whether it is on the receiving side or on the transmitting side, it needs to be in the FPGA and The corresponding signal is extracted from the framer, and the signal is captured by the chipscope to test.

Therefore, the frame header indication signals at five positions A, B, C, D, and E in Fig. 7 are found.

A position frame header: In the FPGA logic, the line transmission side, the frame header of the otu2 data to be sent to the SFI4.2 interface.

B position frame header: In the Framer, the frame header signal is extracted from the overhead insertion portion, and this signal is before the FEC encoding.

C position frame header: In the framer, the frame header signal is extracted from the overhead extraction part, and this signal is after FEC decoding.

D position frame header: In the framer, the client sends the frame header extracted by the overhead part.

E position frame header: In the FPGA logic, on the line receiving side, the frame header signal before the OTU2 overhead is extracted.

After determining the 5 points of the extracted signal, according to Figure 7, four paths are determined:

1. Extract the frame header from the otu2 overhead of the FPGA line side to the li_tx_insfp of the overhead insertion part before the framer encoding.

2. The li_rx_dropfp signal from the li_tx_insfp signal to the framer decoding. (Before the test thought that the li_rx_dropfp signal was decoded before it was proved by many tests, after looking for the framer manual, this signal should be after decoding.)

3. The cl_tx_insfp signal from the li_rx_dropfp signal to the frame side client side transmission side overhead insertion portion.

4. From the cl_tx_insfp signal to the otu2 frame header on the receiving side of the FPGA line side.

The above signal is captured by chipscope, and the frame header signal of point A is used as the trigger signal, and the relative positions of points B, C, D, and E are recorded separately after each power-off. The waveform is shown in Figure 8.

Calculate the number of clocks between each frame header and the A-point frame header, and obtain relative delay data as shown in Table 1.

Table 1 Delay value of each point relative to point A (unit, number of system clocks)

According to the above data, when the system clock is 6ns (192MHz), the calculation results are as follows:

The delay variation of route 1+2 is (1469-1441)*6=168ns, and the delay of path 1 is about (246-219)*6=162ns, so the codec delay of framer does not change much.

The delay variation of route 3+4 needs to find the maximum and minimum value in (E-C) and then make the difference, which is (253-219)*6=204ns.

It is concluded that the main changes exist in path 1 and (3+4), and the framer codec does not change much after the board is powered off.

Because the codec in the framer can't be tested separately, if the codec delay in the framer changes a lot, it is very troublesome, and you can't use fifo for delay compensation. Fortunately, the delay variation of the framer codec is small and can be ignored.

Therefore, by testing the delay value of path 1 and path (3+4), add fifo on the receiving side of the FPGA line side to delay compensation, so that each power-on delay reaches the maximum value, which is in a stable state. can.

It can be seen from the above that the delay values T1delay_now and T2delay_now after power-on are the delay values of path 1 and path (3+4), respectively. Through the system clock, the delay of these paths is measured, and finally, according to the above measurement compensation method, the effect of delay compensation is finally achieved.

In order to achieve the above objective, as shown in FIG. 9, the embodiment of the present invention further provides a device for delay compensation, including:

The extraction module 10 is configured to transmit a service signal from the first device to the second device Obtaining a follow signal that follows the transmission of the service signal;

The delay obtaining module 20 is configured to respectively acquire a first delay value generated by the following signal transmission in the first device and a second delay value generated by transmitting in the second device;

The difference obtaining module 30 is configured to obtain a first difference between the first delay value and a first preset delay value of the first device, and the second delay value and the second device a second difference of the second preset delay value;

The inserting module 40 is configured to insert the first difference value into the service signal and transmit the service signal to the second device;

The compensation acquisition module 50 is configured to extract the first difference value from the service signal on the second device, and obtain a delay required in a service signal transmission process according to the first difference value and the second difference value. Time compensation value;

The compensation module 60 is configured to perform delay compensation on the service signal in the process of transmitting the service signal according to the delay compensation value.

In the above embodiment of the present invention, the delay obtaining module 20 includes:

In the above embodiment of the present invention, the delay obtaining module 20 further includes:

In the embodiment of the present invention, the first preset delay value of the first device is a maximum delay value measured by the first device within a preset time period; and the second preset of the second device is The delay value is the number The maximum delay value measured by the second device during a preset period of time.

In the embodiment of the present invention, the calculation formula of the delay compensation value is:

In the above embodiment of the present invention, the compensation module 60 includes:

In the embodiment of the present invention, the compensation submodule includes:

It should be noted that the apparatus for delay compensation provided by the embodiment of the present invention is a device applying the above method, and all embodiments of the foregoing method are applicable to the device, and all of the same or similar beneficial effects can be achieved.

One of ordinary skill in the art will appreciate that all or a portion of the steps of the above-described embodiments can be implemented using a computer program flow, which can be stored in a computer readable storage medium, such as on a corresponding hardware platform (eg, The system, device, device, device, etc. are executed, and when executed, include one or a combination of the steps of the method embodiments.

Alternatively, all or part of the steps of the above embodiments may also be implemented by using an integrated circuit. These steps may be separately fabricated into individual integrated circuit modules, or multiple modules or steps may be fabricated into a single integrated circuit module. achieve. Thus, the invention is not limited to any specific combination of hardware and software.

The devices/function modules/functional units in the above embodiments may be implemented by a general-purpose computing device, which may be centralized on a single computing device or distributed over a network of multiple computing devices.

When each device/function module/functional unit in the above embodiment is implemented in the form of a software function module and sold or used as a stand-alone product, it can be stored in a computer readable storage medium. The above mentioned computer readable storage medium may be a read only memory, a magnetic disk or an optical disk or the like.

Industrial applicability

In the embodiment of the present invention, the delay of the bearer network device is conveniently implemented without affecting the function of the original device, so that the RRUs of all the wireless devices are synchronously transmitted within a specified time, and the omnidirectional transmitting group is satisfied. Network technical requirements for mobile communication base stations.

Claims

A method of delay compensation, comprising:

Acquiring a follow signal of the following service signal transmission in the process of transmitting the service signal from the first device to the second device;

Obtaining, respectively, a first delay value generated by the following signal transmission in the first device and a second delay value generated by transmitting in the second device;

Obtaining a first difference between the first delay value and a first preset delay value of the first device, and the second delay value and a second preset delay value of the second device Second difference

Inserting the first difference into the service signal to transmit the service signal to the second device;

Extracting, by the second device, the first difference value from the service signal, and acquiring a delay compensation value required for a service signal transmission process according to the first difference value and the second difference value;

And delaying the service signal in the process of transmitting the service signal according to the delay compensation value.
The method of delay compensation according to claim 1, wherein said respectively acquiring a first delay value generated by the following signal transmission in said first device and a second delay value generated by transmission in said second device The time value steps include:

Extracting the following signal at a first preset position of the first device, and acquiring information of the following signal at the first preset position;

Extracting the following signal at a second preset position of the first device, and acquiring information of the following signal at the second preset position;

And acquiring, according to the information of the following signals at the first preset position and the second preset position, a first delay value generated by the following signal transmitted in the first device.
The method of delay compensation according to claim 1 or 2, wherein said respectively acquiring a first delay value generated by the following signal transmission in said first device and a transmission generated in said second device The steps of the two delay values further include:

Extracting the following signal at a third preset position of the second device, and acquiring information of the following signal at the third preset position;

Extracting the following signal at a fourth preset position of the second device to acquire the following signal Information at the fourth preset position;

And acquiring, according to the information of the following signals at the third preset position and the fourth preset position, a second delay value generated by the following signal transmission in the second device.
The method of delay compensation according to claim 1, wherein the first preset delay value of the first device is a maximum delay value measured by the first device within a preset time period; The second preset delay value of the second device is a maximum delay value measured by the second device within a preset time period.
The method of delay compensation according to claim 4, wherein the calculation formula of the delay compensation value is:

Delay compensation value = (maximum delay value of the first device - first delay value) + (maximum delay value of the second device - second delay value).
The method of delay compensation according to claim 1, wherein the step of delay compensation of the service signal transmission process according to the delay compensation value comprises:

Delaying compensation of the service signal transmission process by a first-in first-out queue; wherein the delay compensation value is used to control the output of the first-in first-out queue.
The method of delay compensation according to claim 6, wherein said step of controlling said output of said first-in first-out queue by said delay compensation value comprises:

And calculating, according to the read/write clock of the first-in first-out queue, the delay compensation value into a read/write clock period value of the N first-in first-out queues;

When the N service signals are written in the first-in first-out queue, the service signals are sequentially output;

Where N is an integer greater than or equal to 1.
A delay compensation device includes:

An extraction module, configured to: acquire a follow signal transmitted by the service signal during the process of transmitting the service signal from the first device to the second device;

a delay acquisition module, configured to: respectively acquire a first delay value generated by the following signal transmission in the first device and a second delay value generated by transmitting in the second device;

a difference obtaining module, configured to: obtain a first difference between the first delay value and a first preset delay value of the first device, and the second delay value and the second a second difference of the second preset delay value of the device;

Inserting a module, configured to: insert the first difference value into the service signal and transmit the service signal to the second device;

a compensation acquisition module, configured to: extract the first difference value from the service signal on the second device, and acquire, according to the first difference value and the second difference value, a service signal transmission process Delay compensation value;

The compensation module is configured to: perform delay compensation on the service signal in the process of transmitting the service signal according to the delay compensation value.
The apparatus for delay compensation according to claim 8, wherein the delay acquisition module comprises:

a first clock acquisition module, configured to: extract the following signal at a first preset position of the first device, and acquire information of the following signal at the first preset position;

a second clock acquisition module, configured to: extract the following signal at a second preset position of the first device, and acquire information of the following signal at the second preset position;

a first delay acquisition sub-module, configured to: acquire, according to information of the follow-up signal at the first preset position and the second preset position, a first delay value generated by the following signal transmitted in the first device .
The apparatus for delay compensation according to claim 8 or 9, wherein the delay acquisition module further comprises:

a third clock acquisition module, configured to: extract the following signal at a third preset position of the second device, and acquire information of the following signal at the third preset position;

a fourth clock acquisition module, configured to: extract the following signal at a fourth preset position of the second device, and acquire information of the following signal at the fourth preset position;

The second delay acquisition sub-module is configured to: acquire, according to information of the following signals at the third preset position and the fourth preset position, a second delay value generated by the following signal transmission in the second device.
The apparatus for delay compensation according to claim 8, wherein the first preset delay value of the first device is a maximum delay value measured by the first device within a preset time period; The second preset delay value of the second device is a maximum delay value measured by the second device within a preset time period.
The apparatus for delay compensation according to claim 11, wherein said delay compensation value The calculation formula is:

Delay compensation value = (maximum delay value of the first device - first delay value) + (maximum delay value of the second device - second delay value).
The apparatus for delay compensation according to claim 8, wherein the compensation module comprises:

The compensation sub-module is configured to: delay compensation of the service signal transmission process by using a first-in first-out queue; wherein the delay compensation value is used to control the output of the first-in first-out queue.
The apparatus for delay compensation according to claim 13, wherein the compensation submodule comprises:

a conversion module, configured to: convert the delay compensation value into a read/write clock period value of the N first-in first-out queues according to the read/write clock of the first-in first-out queue;

An output module, configured to: sequentially output a service signal after writing N service signals in the first-in first-out queue;

Where N is an integer greater than or equal to 1.
A computer program comprising program instructions which, when executed by a computer, cause the computer to perform the method of any of claims 1-7.
A computer readable storage medium carrying the computer program of claim 15.