RU2648285C1 - Method and delivery compensation device - Google Patents

Abstract

FIELD: radio engineering and communication.

SUBSTANCE: invention relates to communication. At a time, method includes: obtaining an accompanying signal transmitted along with an overhead signal during the transmission of an overhead signal from the first equipment to the second equipment; obtaining, respectively, the first value of the delay generated during the transmission of the accompanying signal in the first equipment, and a second delay value generated during transmission in the second equipment; obtaining a first difference value between the first delay value and the first set delay value of the first equipment and the second difference value between the second delay value and the second predetermined delay value of the second equipment; inserting the first difference value into an overhead signal for transmission to the second equipment along with an overhead signal; extracting the first difference value from an overhead signal on the second equipment and obtaining a delay compensation value, required during the transmission of the service signal in accordance with the first difference value and the second difference value; and performing a delay compensation on the service signal during the transmission of the service signal in accordance with the delay compensation value.

EFFECT: technical result is the solution of the delay problem.

15 cl, 9 dwg, 1 tbl

Description

Technical field

The invention relates to the field of optical transport networks (ONT) for data transmission and, in particular, to a method and device for delay compensation.

BACKGROUND OF THE INVENTION

With the advent of the 3rd generation (3G) era, each telecom company is building 3G mobile networks on a large scale with large investments, and base stations are the equipment that has the most quantity and cost in building 3G networks. The growing fierce competition in the field of mobile communications is forcing telecom operators to pay more attention to the cost of building a network, and a distributed base station with features such as low cost, high performance, fast operation and the like can significantly reduce the cost of network construction, operation and maintenance for operator companies. Therefore, distributed base stations are becoming the most dominant choice for the ongoing construction of a 3G network.

The main idea of a distributed base station is to separate the base frequency processing unit (BBU) and the remote radio unit (RRU) of the traditional macro level base station and connect them using fiber optic or information delivery network equipment. During the deployment of the BBU network, the control equipment of the core network and the radio network is concentrated in the engine room and connected to the RRU deployed at the planned site using optical fibers, thereby completing the network coverage.

Compared to the solution for a traditional base station, the solution for a distributed base station not only greatly reduces dependence on the machine room located on the site, reduces deployment difficulties, but also effectively increases the speed of network construction, which greatly reduces the cost of network construction, operation and maintenance for operator companies and fully meets the requirement of fast and cheap network construction put forward by the operator company. Thus, the option of building a network based on distributed base stations has become an important choice for deploying a base station of an operator company.

An implementation method for a distributed base station includes sending digital base frequency data to the RRU via a public radio interface (CPRI) via information delivery network equipment. CPRI is a standard interface initiated and formulated by companies such as Ericsson, Huawei, NEC, Nortel Networks and Siemens, and configured to connect the BBU to the RRU. The CPRI interface can be used for many 3G systems and future long-term development (LTE). Currently, direct fiber optic transmission technology and wavelength division multiplexing / OTN (WDM / OTN) can satisfy the CPRI transmission requirement. OTN-based CPRIs can increase the utilization of optical fiber bandwidth, support longer distance transmission, provide complete protection and full optical level control, support any network topology, simplify operation and maintenance, easily increase bandwidth and speed up the launch of a new radio services; and OTN-based CPRIs can also increase transmission distance and can provide protection. Thus, OTN-based CPRIs can be widely used by operator companies.

Provided that the radio equipment does not use a distributed base station and uses OTN equipment, the delay compensation mechanism is implemented inside the radio equipment, and together with the large-scale use of OTN equipment for radio communications, there is a need for OTN equipment to solve the delay problem (for the technical requirement of using an omnidirectional sending network to of a mobile communication base station, the delay in sending each send channel on the antenna port should be synchronized within the permissible range a range of values, that is, the requirement extends to the synchronization and transfer of all the RRU in a certain period of time).

SUMMARY OF THE INVENTION

An embodiment of the present invention provides a delay compensation method and apparatus that easily achieves the goal of synchronizing and transmitting the RRU of all radio equipment at a specific time by compensating for the delay by the equipment of the information delivery network, provided that there is no effect on the function of the source equipment.

The delay compensation method includes:

receiving an accompanying signal transmitted along with the service signal in the process of transmitting the service signal from the first equipment to the second equipment;

obtaining, respectively, a first delay value generated during transmission of an accompanying signal in the first equipment, and a second delay value generated during transmission in the second equipment;

obtaining a first difference value between the first delay value and the first predetermined delay value of the first equipment and a second difference value between the second delay value and the second predetermined delay value of the second equipment;

insertion of the first difference value into the service signal and its transmission together with the service signal to the second equipment;

extracting the first difference value from the service signal on the second equipment and obtaining a delay compensation value required in the process of transmitting the service signal in accordance with the first difference value and the second difference value; and

performing delay compensation on the service signal during the service signal transmission in accordance with the delay compensation value.

Alternatively, the step of obtaining a first delay value generated during the transmission of the accompanying signal in the first equipment, and a second delay value generated during the transmission in the second equipment, respectively, includes:

extracting an accompanying signal in a first predetermined position of the first equipment and obtaining information of an accompanying signal in a first predetermined position;

extracting an accompanying signal in a second predetermined position of the first equipment and obtaining information of an accompanying signal in a second predetermined position; and

obtaining the first delay value generated during the transmission of the accompanying signal in the first equipment in accordance with the information of the accompanying signal in the first predetermined position and the second predetermined position.

Alternatively, the step of obtaining a first delay value generated during transmission of the accompanying signal in the first equipment and a second delay value generated during transmission in the second equipment, respectively, further includes:

extracting an accompanying signal in a third predetermined position of the second equipment and obtaining information of an accompanying signal in a third predetermined position;

extracting the accompanying signal in the fourth predetermined position of the second equipment and obtaining information of the accompanying signal in the fourth predetermined position; and

obtaining a second delay value generated during the transmission of the accompanying signal in the second equipment in accordance with the information of the accompanying signal in the third predetermined position and the fourth predetermined position.

Alternatively, the first predetermined delay value of the first equipment is the maximum delay value measured by the first equipment in a predetermined period of time; and the second predetermined delay value of the second equipment may be the maximum delay value measured by the second equipment in a predetermined period of time.

Alternatively, the calculation formula for the delay compensation value is as follows:

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

Alternatively, the step of performing delay compensation in the process of transmitting an overhead signal in accordance with the delay compensation value includes:

performing delay compensation in the process of transmitting an overhead signal through the “first come, first go” queue (FIFO); wherein the output of the FIFO queue can be controlled by a delay compensation value.

Alternatively, the step of controlling the output of the FIFO queue by means of a delay compensation value includes:

converting the delay compensation value to N cycle values of the FIFO queue read / write clock in accordance with the FIFO queue read / write clock; and

serial output of service signals after recording N service signals in the FIFO queue.

An embodiment of the present invention further provides a delay compensation device, which comprises:

an extraction module, configured to receive an accompanying signal transmitted along with the service signal in the process of transmitting the service signal from the first equipment to the second equipment;

a delay receiving unit configured to obtain a first delay value generated during the transmission of the accompanying signal in the first equipment, and a second delay value generated during the transmission in the second equipment, respectively;

a difference value obtaining unit configured to obtain a first difference value between a first delay value and a first predetermined delay value of a first equipment, and a second difference value between a second delay value and a second predetermined delay value of a second equipment;

an insertion unit configured to insert the first difference value into the service signal and transmit the first difference value together with the service signal to the second equipment;

a compensation receiving unit configured to extract the first difference value from the service signal on the second equipment, and obtain a delay compensation value necessary in the process of transmitting the service signal in accordance with the first difference value and the second difference value; and

a compensation module configured to perform delay compensation on the service signal during the transmission of the service signal in accordance with the delay compensation value.

Alternatively, the delay receiving module comprises:

a first clock signal acquiring module adapted to extract an accompanying signal in a first predetermined position of the first equipment and obtain information of an accompanying signal in a first predetermined position;

a second clock signal acquiring module adapted to extract an accompanying signal in a second predetermined position of the first equipment and obtain information of an accompanying signal in a second predetermined position; and

a first delay receiving submodule configured to obtain a first delay value generated during the transmission of the accompanying signal in the first equipment in accordance with the information of the accompanying signal in the first predetermined position and the second predetermined position.

Alternatively, the delay receiving module further comprises:

a third clock signal acquiring module adapted to extract an accompanying signal in a third predetermined position of the second equipment and obtain information of an accompanying signal in a third predetermined position;

a fourth clock signal acquiring module adapted to extract an accompanying signal in a fourth predetermined position of the second equipment and obtain information of an accompanying signal in a fourth predetermined position; and

the second delay receiving submodule, configured to obtain a second delay value generated during the transmission of the accompanying signal in the second equipment in accordance with the information of the accompanying signal in the third predetermined position and the fourth predetermined position.

Alternatively, the first predetermined delay value of the first equipment is the maximum delay value measured by the first equipment in a predetermined period of time; and the second predetermined delay value of the second equipment is the maximum delay value measured by the second equipment in a predetermined period of time.

Alternatively, the calculation formula for the delay compensation value, in particular, is as follows:

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

Alternatively, the compensation module may comprise:

a compensation submodule, configured to perform delay compensation during the transmission of the overhead signal through the FIFO queue; wherein the output of the FIFO queue can be controlled by a delay compensation value.

Alternatively, the compensation submodule comprises: a conversion module configured to convert the delay compensation value into N cycle values of the FIFO queue read / write clock in accordance with the FIFO queue read / write clock; and

an output module configured to sequentially output service signals after writing N service signals to the FIFO queue.

In the delay compensation method of an embodiment of the present invention, the delay values of the accompanying signal transmitted together with the service signal in the first equipment and the second equipment are obtained for calculating a delay compensation value required in the process of transmitting the service signal and performing delay compensation on the service signal; and the goal of synchronizing and transmitting the RRU of all the radio equipment in a certain period of time by compensating for the delay by the equipment of the information delivery network can easily be achieved if there is no effect on the functions of the source equipment, thereby satisfying the technical requirement of the omnidirectional sending network at the mobile communication base station.

Brief Description of the Drawings

In FIG. 1 is a flowchart of the main steps of a delay compensation method in accordance with an embodiment of the present invention;

in FIG. 2 is a block diagram of a case 1 of applying a delay compensation method in accordance with one embodiment of the present invention;

in FIG. 3 is a signal flow diagram of a delay compensation method in accordance with one embodiment of the present invention;

in FIG. 4 depicts a basic network topology in a specific embodiment 1 in accordance with one embodiment of the present invention;

in FIG. 5 is a block diagram of a CPRI6 service access scheme in specific embodiment 1 in accordance with one embodiment of the present invention;

in FIG. 6 is a schematic representation of a delay measurement path in a specific embodiment 1 in accordance with one embodiment of the present invention;

in FIG. 7 is a block diagram of the internal logic of a user programmable logic array (FPGA) and frame former in specific embodiment 2, in accordance with one embodiment of the present invention;

in FIG. 8 is a schematic representation of the relative positions of the frame headers at each point in a specific embodiment 2 in accordance with one embodiment of the present invention; and

in FIG. 9 is a block diagram of a delay compensation device in accordance with one embodiment of the present invention.

Specific Embodiments

Specific embodiments of the present invention will be described in detail below with reference to the drawings. Embodiments of the present invention and characteristics in embodiments may be freely combined, provided that there are no conflicts.

To solve the problem of the inability to eliminate the delay between the two components of the separate equipment due to the fact that all the radio equipment uses internal delay compensation mechanisms in related technology, an embodiment of the present invention provides a delay compensation method and apparatus. The delay values of the accompanying signal transmitted together with the service signal in the first equipment and the second equipment are obtained for calculating the delay compensation value required in the process of transmitting the service signal and performing delay compensation on the service signal; and the goal of synchronizing and transmitting the RRU of all the radio equipment in a certain period of time by compensating for the delay by the equipment of the information delivery network can easily be achieved if there is no effect on the functions of the source equipment, thereby satisfying the technical requirement of the omnidirectional sending network at the mobile communication base station.

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

stage 1: receiving the accompanying signal transmitted along with the service signal in the process of transmitting the service signal from the first equipment to the second equipment;

step 2: obtaining, respectively, the first delay value generated during the transmission of the accompanying signal in the first equipment, and the second delay value generated during the transmission in the second equipment;

step 3: obtaining a first difference value between the first delay value and the first predetermined delay value of the first equipment and a second difference value between the second delay value and the second predetermined delay value of the second equipment;

step 4: inserting the first difference value into the service signal transmitted along with the service signal to the second equipment;

step 5: extracting the first difference value from the service signal on the second equipment and obtaining the delay compensation value required in the process of transmitting the service signal in accordance with the first difference value and the second difference value; and

step 6: performing delay compensation on the service signal in the process of transmitting the service signal in accordance with the value of the delay compensation.

In the aforementioned embodiment of the present invention, the accompanying signal from step 1 may be a specific signal extracted from the service signal and related to the service, and there may also be another signal inserted into the service signal, and any signal that can be transmitted together with the service signal applicable to an embodiment of the present invention. In step 2, the accompanying signal from step 1 is extracted at the positions requiring measurement of the first equipment and the second equipment, respectively, and the transmission delay between the two signals in the first equipment and the second equipment is measured to accordingly obtain the first delay value and the second delay value, respectively; in this case, the first delay value and the second delay value can be measured using the method of counting clock signals, that is, the measurement clock signal is inserted into the entire process of transmitting the service signal, and the delay values are determined in accordance with the number of clock signals between the positions with the measurement requirement.

Since the first delay value in the first equipment and the second delay value in the second equipment are unstable and the delay values change together with changes in factors such as time and signal intensity, to ensure the stability of the delays, the first set delay value of the first equipment and the second delay set value are set second equipment, and the corresponding difference values, i.e. the first difference value and the second difference value between the real-time delay values and the set delay values are obtained in step 3; wherein the first predetermined delay value and the second predetermined delay value are specially obtained using a large amount of experimental data, and can also be obtained in accordance with the theoretical parameters of the first equipment or second equipment by a method for calculating numerical values, which is not limited to a fixed method, and all methods suitable for correctly obtaining the first delay predetermined value and the second delay predetermined value are applicable to the embodiment of the image taenia.

In this case, the service signal is compensated in accordance with the compensation value required by the delays obtained in step 5 by the delay device or equipment in step 6; wherein the delay device or equipment is a delay circuit, an FPGA-based device, a time delay switch or the like, which will not be discussed in detail one after another in this document. It is important to note the following: during the practical application of the delay compensation method, in particular, described in the present invention, with respect to the service signal during transmission from the first equipment to the second equipment, the signals are transmitted in two directions on each component of the equipment, both of which have delay and require delay compensation, so it is necessary to compensate for delays in two directions of the equipment, respectively, to maintain delays stable during the transfer of service from the needle when performing compensation by the delay device in step 6.

In the above embodiment of the present invention, step 2 includes:

step 21: extracting an accompanying signal in a first predetermined position of the first equipment and obtaining information of an accompanying signal in a first predetermined position;

step 22: extracting an accompanying signal in a second predetermined position of the first equipment and obtaining information of an accompanying signal in a second predetermined position; and

step 23: obtaining a first delay value generated during the transmission of the accompanying signal in the first equipment in accordance with the information of the accompanying signal in the first predetermined position and the second predetermined position.

Stage 2 may further include:

step 24: extracting the accompanying signal in the third predetermined position of the second equipment and obtaining information of the accompanying signal in the third predetermined position;

step 25: extracting the accompanying signal in the fourth predetermined position of the second equipment and obtaining information of the accompanying signal in the fourth predetermined position; and

step 26: obtaining a second delay value generated during the transmission of the accompanying signal in the second equipment in accordance with the information of the accompanying signal in the third predetermined position and the fourth predetermined position.

In a specific embodiment of the present invention, steps 21-26 are the steps of obtaining a first delay value and a second delay value by applying a clock counting method; wherein the measurement clock signal is inserted into the service signal transmission process, and, alternatively, the measurement clock signal can use the system clock signal of the service signal transmission system, and can also be an independently specified clock signal, without being limited to a fixed shape.

Alternatively, the first predetermined position and the second predetermined position of the first equipment are set different in accordance with different equipment, without being limited to fixed positions; the first information of the clock signal in the first predetermined position represents the corresponding position of the first predetermined position on the measurement clock signal, and the second information of the clock signal in the second predetermined position represents the corresponding position of the second predetermined position in the measurement clock; step 23 is further performed to obtain a first delay value by calculating the number of clock signals between the first predetermined position and the second predetermined position on the measurement clock; and, for example, there are 4 periods of a measurement clock signal between the first information of the clock signal and the second information of the clock signal, the first delay value is 4 measurement clocks, and in particular, the measurement unit of the delay value is usually a nanosecond. In this case, the process of obtaining the second delay value corresponds to the process of obtaining the first delay value, and they will not be discussed in detail one after another in this document.

It should be explained that delay compensation is not performed inside the first equipment after receiving the first delay value of the first equipment in the embodiment of the present invention, instead, the first delay value is inserted into an overhead signal for transmission to the second equipment, and, alternatively, the first delay value is transmitted by applying the reserved OTN service information to perform the interaction of the two components of the individual equipment.

In the aforementioned embodiment of the present invention, the first predetermined delay value of the first equipment is the maximum delay value measured by the first equipment in a predetermined period of time; and the second predetermined delay value of the second equipment is the maximum delay value measured by the second equipment in a predetermined period of time.

In this embodiment of the present invention, the method of obtaining the maximum delay value of the first equipment and the maximum delay value of the second equipment can be as follows: a relatively more accurate maximum delay value can be obtained by measuring many components of the same equipment and performing power supply, interrupting the power supply and connecting and disconnecting optical fiber at least 100 times for experimental data and experimental analysis yes data.

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

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

It should be explained that the calculation formula for the delay compensation value in this embodiment is only an optional embodiment of the invention and is not intended to limit the protection scope of the present invention, and any other algorithm that can correctly calculate the delay compensation value can be applied in these variants the implementation of the present invention.

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

step 61: performing delay compensation in the process of transmitting an overhead signal through the FIFO queue, wherein the output of the FIFO queue is controlled by the delay compensation value.

In this case, the FIFO queue is a traditional sequential method of execution, the input command is first executed and completed, and then the second command is executed. The principle of the FIFO queue is as follows: the FIFO queue does not classify messages, the FIFO queue allows messages to enter the queue in accordance with the sequence of messages arriving at the interface, while the FIFO queue allows messages to leave the queue according to the sequence of incoming messages at the output of the queue, messages received in the queue earlier, leave the queue earlier, and messages that arrived in the queue later leave the queue later.

In a specific embodiment of the present invention, the step of controlling the output of the FIFO queue by means of a delay compensation value includes:

step 62: converting the delay compensation value to N cycle values of the FIFO queue read / write clock signal in accordance with the FIFO queue read / write clock signal; N is an integer that is greater than or equal to 1.

Step 63: sequentially output N overheads after writing overheads to the FIFO queue.

Still for the above example, in a specific application of the present invention, the FIFO queue is equivalent to a cache, and if the number of overheads in the FIFO queue is less than N, the FIFO queue does not externally read data, but supports internal data writing; if the number of overheads in the FIFO queue is N, the output end of the FIFO queue can externally read the data component, each time the data component is written to the FIFO queue; it should be clarified that data is continuously written to the FIFO queue and the FIFO queue can support external data reading if service signals are transmitted all the time; however, since the number of service signals in the FIFO queue is N, it is ensured that each service signal is output from the second equipment with a maximum delay value, thereby ensuring delay stability.

The FIFO queue read / write clock in the aforementioned embodiment of the present invention may also apply a system clock or apply a clock corresponding to the aforementioned measurement clock. If the read-write clock of the FIFO queue corresponds to the measurement clock when calculating the delay value and the delay compensation value, the plurality of time periods of the clock signal can be directly used to calculate without converting to a certain number of nanoseconds, in which case the delay compensation value in step 62 is directly equal to N values of the period of the clock signal, so that the calculation steps are simplified.

With reference to case 1, the delay compensation process according to the invention is described in detail as shown in FIG. 2 and FIG. 3.

In application case 1, as shown in FIG. 2, two equipment components (OTN equipment 1 and OTN equipment 2) in the information delivery network are used between two components of terminal equipment (external equipment 1, external equipment 2), respectively, and when a signal is transmitted between two components of terminal equipment, the requirement is usually made delay stability, so the requirement to send a signal to OTN equipment is relatively strict, and OTN equipment is necessary to ensure delay stability. To this end, the present invention provides a delay compensation method as shown in FIG. 3.

Stage 1: first, signals that take the entire path that probably generates a delay change are extracted from or inserted into board 1 and board 2, respectively, the signal (accompanying signal) is usually extracted from or inserted into the signal path in front of board 1 / signal board 2 and the same signal is extracted from the signal path for the board 1 / board 2, and the delay between the two signals is measured.

Stage 2: a lot of measurements are made on the board, and the maximum values measured by the delay measurement module 1 and the delay measurement module 2 are selected from all measurements on the board, the maximum delay values of the equipment 1 and equipment are defined as Ta_delay_max and Tb_delay_max, respectively.

Step 3: the delay values, Ta_delay_now and Tb_delay_now, of the two boards are measured after power is applied to the boards, there are many measurement methods, and for example, the time for a frame header from input to equipment to output from equipment is measured to obtain a delay value.

Step 4: the measured delay value of the board 1 is transmitted to the board 2 by means of an overhead transmission, and then the measured delay value (Ta_delay_now) of the board 1 is removed from the board 2.

Step 5: the measured value Ta_delay_now of the board 1 and the delay value Tb_delay_now of the board 2 are compared with the maximum delay values (Ta_delay_max and Tb_delay_max) to obtain the difference values, respectively, and the two difference values are compensated by the delay compensation module.

Application Example 1

The practical condition of the method will be tested below with the support of the CPRI6 service on the OTN board, as an example. A block diagram of the application is shown in FIG. 4, and a specific circuit of a service processing unit on a board is shown in FIG. 5.

Here, the client side refers to the service that the board refers to, and the line side refers to the service supporting CPRI, and refers to the OTN service. The service processing process is designed to process the client and line-side services through the FPGA logic first and converting the service signals that pass through the frame driver chip and reach the optical port into optical signals for transmission.

Firstly, it is necessary to measure the section with delay instability, and then the maximum delay value is obtained using many measurements. Here, the delay existing in the odu2 layer of the sending section of the linear side is measured by odu2 by the frame header (fp1) in the input position of the board and the frame header (fp2) in the output position of the board. The logic module that implements such a measurement is a delay measurement unit 1, and the first delay value that is measured is Ta_delay_now.

Secondly, the two boards are connected via optical fiber. For example, for OTN, the first Ta_delay_now delay value, which is measured, can be transmitted to the downstream portion for compensation through the payload area or OTN overhead.

Then, the section delay from the receiving line side to the sending client side is measured using the frame header (fp3) in the input position of the board and the frame header (fp4) in the output position of the board. The logic module that implements such a measurement is a delay measurement module 2, and the second delay value that is measured is Tb_delay_now.

Finally, the logic performs an operation on two delay values and maximum delay values (Ta_delay_max and Tb_delay_max), which are obtained as a result of a large number of preliminary tests, to obtain the value fifo_value. Then, the delay value is compensated by compensating for the FIFO delay.

It is important to note that whether the measurement clock and the FIFO delay compensation clock is the same clock or not is one of the factors that affect the time accuracy. In addition, it is necessary to obtain specific values of Ta_delay_max and Tb_delay_max by performing a large number of combinations of measurements on the board for many time periods.

The delay measurement process is shown in FIG. 6.

The condition for changing the delay of the OTN board is analyzed, and a method for measuring the delay value Tdelay_now is performed.

In FIG. Figure 6 shows a schematic representation of the entire OTN board service processing process, with the client side connected to the CPRI6 service with a bandwidth of 6.144 Gbit / s, and the line side uses fiber optics for the feedback loop.

To determine the part with delay instability, processing on the client side, on the linear side, in the scalable interface of the shaper of frames with parallel-serial conversion 4.2 (SFI4.2) or in the shaper of frames, it is necessary to extract the corresponding test signals from the FPGA logic and the shaper and then capture signals in each test position through internal programming of logic or the Chipscope analyzer.

Thus, the frame header indicator signals are found at four positions A, B, C, and D in FIG. 5. Three test paths are indicated by a red dashed line to perform the test as follows.

Position A: Signal extracted by the sending side of the client side in FPGA logic.

Position B: frame header signal extracted from odu2 of the inserted part of the service information in the frame former, while the signal was located before forward error correction (FEC) encoding.

Position C: frame header signal extracted from the extracted part of the service information to the frame former; the signal was extracted after encoding with FEC.

Position D: signal received by the receiving side of the client side in FPGA logic.

After determining the four positions of the signal extraction, three test paths are determined, as shown in FIG. 6, and these three paths cover the entire process of processing services:

path 1: contains all the logic circuits on the client side and the linear side, SFI4.2 and part of the processing modules in the frame former;

path 2: contains coding and decoding schemes and a part from the optical module to the optical fiber in the frame former; and

path 3: contains part of the processing modules in the driver, SFI4.2 and the logic of the linear side and the client side of the receiving side.

Three ways are tested accordingly to obtain the following conclusion (such a test method is not the main method of the invention and will not be discussed here in detail):

delay changes mainly exist in path 1 and path 3, and delay variation in another path can be ignored, so that the goal of delay compensation can only be achieved by compensating paths 1 and 3 to facilitate testing; and therefore, fifo is added to the receiving side of the line side of the FPGA to compensate for the delay to realize and maintain the maximum value of the delay in a stable state during power-up each time.

From the above, it is known that the first delay value Ta_delay_now and the second delay value Tb_delay_now after power on each time are the delay values of path 1 and path 3, respectively. The two parts are compensated to maintain the delay values in a stable state.

In this embodiment of the present invention, the delay value to be compensated by Fifo is: Tdelay_offset = {(Ta_delay_max - Ta_delay_now) + (Tb_delay_max - Tb_delay_now}.

All FIFO read / write clocks are a system clock, fifo fill level is controlled by Tdelay_offset if the number of service signals is less than Tdelay_offset, data is not read and data is written to fifo all the time, and if the number of service signals is Tdelay_offset, fifo begins to save data read externally, thereby ensuring delay stability.

Application example 1 explains a method for measuring stability and delay compensation if the equipment OTN service card supports the cpri6 service. The method also applies to CPRI related services with different performance, such as CPRI2 / CPRI3 / CPRI4 / CPRI5 / CIPR6 / CPRI7 services, and the entire processing process is essentially the same with the specific embodiment 1.

The method is also applied to other service boards from OTN equipment, and during the design of FPGA services, the method can be applied to compensate for the case of requiring stability of the delay.

Application Example 2

The feasibility of the method is checked with support for synchronous Ethernet on the board, as an example.

First, it is determined that the delay variation of the client side is very stable due to the service feedback loop, and in order to determine where the delay instability is created - in SFI4.2, in the frame shaper, or on the receiving side, or on the sending side, it is necessary extract the appropriate signals from the FPGA and frame former and capture the signals at each position for testing with the Chipscope analyzer.

Thus, the frame header indicator signals are found in four positions A, B, C, D and E in FIG. 7.

Frame header at position A: The header of the otu2 data frame to be sent to SFI4.2 on the linear sending side to the FPGA logic.

The frame header at position B: the frame header signal extracted from the inserted part of the service information in the frame former, the signal is located before encoding with FEC.

The frame header in position C: the frame header signal extracted from the extracted part of the service information in the frame former, the signal is located after encoding with FEC.

Frame header at position D: frame header extracted by the overhead part of the sending client side in the frame former.

Frame header at position E: frame header signal before extracting OTU2 overhead information on the linear receiving side in FPGA logic.

After determining five signal extraction points, four test paths are determined, as shown in FIG. 7:

1: from the frame header extracted from the otu2 header on the linear side of the FPGA to li_tx_insfp in the inserted part of the service information before encoding the frame shaper;

2: from the li_rx_insfp signal to the li_rx_dropfp signal after decoding the frame shaper (it is believed that the li_rx_dropfp signal is located before decoding in the test performed earlier, many tests proved that this is incorrect, and the signal should be located after decoding from the shaper instruction);

3: from the signal li_rx_dropfp to the signal cl_tx_insfp in the inserted part of the service information on the sending side of the client side of the frame former; and

4: from cl_tx_insfp to the otu2 frame header on the receiving side of the line side of the FPGA.

The above signals are captured using a Chipscope analyzer, the frame header signal at point A is defined as the trigger signal, and the relative positions of points B, C, D, and E are recorded after interruption of power supply and power supply each time. The waveform is shown in FIG. 8.

The number of clocks between each frame header and frame header at point A is calculated to obtain the relative delay data shown in Table 1.

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

the change in the path delay (1 + 2) is (1469 - 1441) * 6 = 168 ns, while the change in the delay of the path 1 is probably (246 - 219) * 6 = 162 ns, so the change in the delay of the encoding and decoding of the frame former is not big; and

the maximum and minimum should be found from (Е-С) to calculate the difference value (253 - 219) * 6 = 204 not to change the path delay (3 + 4).

Thus, the following conclusion is made: the changes mainly exist in paths 1 and (3 + 4), and the change in the encoding and decoding delay of the frame former after the power supply is cut off and the board is powered up is not big.

It is not possible to test the encoding and decoding separately in the frame shaper, and if the change in delay in the coding and decoding of the frame shaper is large, it is difficult and impossible to use fifo to compensate for the delay. Fortunately, the change in coding and decoding delay is small and can be ignored.

Thus, the variation in the delay of path 1 and the path (3 + 4) can be tested and added on the receiving side of the linear side of the FPGA to compensate for the delay to realize and maintain the maximum delay value in a stable state during power-up each time.

From the above, it is known that the delay values Tldelay_now and T2delay_now after each power-up time are the delay values of path 1 and path (3 + 4), respectively. The delays of these paths are measured using the system clock, and the delay compensation effect is finally achieved in accordance with the aforementioned measurement and compensation method.

To better achieve the aforementioned goal, as shown in FIG. 9, an embodiment of the present invention further provides a delay compensation device, which comprises:

extraction module 10, configured to receive an accompanying signal transmitted along with the service signal in the process of transmitting the service signal from the first equipment to the second equipment;

a delay receiving unit 20 configured to obtain a first delay value generated during transmission of an accompanying signal in the first equipment, and a second delay value generated during transmission in the second equipment, respectively;

a difference value obtaining unit 30, configured to obtain a first difference value between a first delay value and a first delay setpoint of a first equipment, and a second difference value between a second delay value and a second delay setpoint of a second equipment;

an insertion unit 40, configured to insert the first difference value into the service signal and transmit the first difference value together with the service signal to the second equipment;

a compensation receiving unit 50, configured to extract the first difference value from the overhead signal on the second equipment, and obtain a delay compensation value necessary in the process of transmitting the overhead signal in accordance with the first difference value and the second difference value; and

compensation module 60, configured to perform delay compensation on the service signal during the transmission of the service signal in accordance with the delay compensation value.

In the above embodiment of the present invention, the delay receiving unit 20 comprises:

a first clock signal acquiring module adapted to extract an accompanying signal in a first predetermined position of the first equipment and obtain information of an accompanying signal in a first predetermined position;

a second clock signal acquiring module adapted to extract an accompanying signal in a second predetermined position of the first equipment and obtain information of an accompanying signal in a second predetermined position; and

a first delay receiving submodule configured to obtain a first delay value generated during the transmission of the accompanying signal in the first equipment in accordance with the information of the accompanying signal in the first predetermined position and the second predetermined position.

In the above embodiment of the present invention, the delay receiving unit 20 further comprises:

a third clock signal acquiring module adapted to extract an accompanying signal in a third predetermined position of the second equipment and obtain information of an accompanying signal in a third predetermined position;

a fourth clock signal acquiring module adapted to extract an accompanying signal in a fourth predetermined position of the second equipment and obtain information of an accompanying signal in a fourth predetermined position; and

the second delay receiving submodule, configured to obtain a second delay value generated during the transmission of the accompanying signal in the second equipment in accordance with the information of the accompanying signal in the third predetermined position and the fourth predetermined position.

In this embodiment of the present invention, the first predetermined delay value of the first equipment is the maximum delay value measured by the first equipment in a predetermined period of time; and the second predetermined delay value of the second equipment is the maximum delay value measured by the second equipment in a predetermined period of time.

In this embodiment of the present invention, the calculation formula for the delay compensation value is as follows:

delay compensation value = (maximum delay value of the first equipment is the first delay value) + (maximum delay value of the second equipment is the second delay value).

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

a compensation submodule, configured to perform delay compensation during the transmission of the overhead signal through the FIFO queue; wherein the output of the FIFO queue is controlled by the delay compensation value.

In an embodiment of the invention, the compensation submodule comprises:

a conversion module configured to convert the delay compensation value into N cycle values of the FIFO queue read / write clock signal in accordance with the FIFO queue read / write clock signal; and

an output module configured to sequentially output N overheads after writing overheads to the FIFO queue.

In the delay compensation device of an embodiment of the present invention, the delay values of the accompanying signal transmitted together with the service signal in the first equipment and the second equipment are obtained for calculating a delay compensation value required in the process of transmitting the service signal and performing delay compensation on the service signal; and the goal of synchronizing and transmitting the RRU of all the radio equipment in a certain period of time by compensating for the delay by the equipment of the information delivery network can easily be achieved if there is no effect on the functions of the source equipment, thereby satisfying the technical requirement of the omnidirectional sending network at the mobile communication base station.

It should be explained that the delay compensation device provided by the embodiment of the present invention is a device using the above method, all embodiments of the above method are applicable to the device, and the same or similar advantageous effects can be achieved.

Specialists in the art should understand that all or part of the steps of the above embodiment can be implemented by a computer program, while the computer program can be stored on a computer-readable storage medium, the computer program runs on an appropriate hardware platform (such as a system, equipment, device and apparatus, etc.), and one or a combination of the steps of the method according to an embodiment is turned on at runtime.

Alternatively, all or part of the steps of the aforementioned embodiment may also be implemented by means of an integrated circuit, wherein these steps may respectively form integrated circuit modules, or a plurality of modules or steps may form a single integrated circuit module for implementation. Thus, the invention is not limited to a combination of any particular hardware or software.

Each device / function module / function block in the aforementioned embodiment can be implemented by a universal computing device, and they can be concentrated on one computing device and can also be distributed over a network formed by a plurality of computing devices.

When implemented in the form of a software function module and sold or used as an independent product, each device / function module / function block in the above embodiment may be stored in a computer-readable storage medium. The aforementioned computer-readable storage medium may be read only memory, magnetic disk, compact disc or the like.

Industrial applicability

According to an embodiment of the present invention, the goal of synchronizing and transmitting the RRU of all the radio equipment in a certain period of time by compensating for the delay by the equipment of the information delivery network is easily achieved provided that the functions of the source equipment are not affected, thereby satisfying the technological requirement of the omnidirectional sending network at the base station mobile communications.

Claims (49)

1. A method of compensating for delay, including: receiving an accompanying signal transmitted along with the service signal in the process of transmitting the service signal from the first equipment to the second equipment; obtaining a first delay value generated during the transmission of the accompanying signal in the first equipment, and a second delay value generated during the transmission of the accompanying signal in the second equipment, respectively; obtaining a first difference value between the first delay value and the first predetermined delay value of the first equipment and a second difference value between the second delay value and the second predetermined delay value of the second equipment; inserting the first difference value into the service signal and transmitting the first difference value together with the service signal to the second equipment; extracting the first difference value from the service signal on the second equipment and obtaining a delay compensation value required in the process of transmitting the service signal in accordance with the first difference value and the second difference value; and performing delay compensation on the service signal during the service signal transmission in accordance with the delay compensation value. 2. The delay compensation method according to claim 1, characterized in that the step of obtaining a first delay value generated during the transmission of the accompanying signal in the first equipment and a second delay value generated during the transmission of the accompanying signal in the second equipment, respectively, includes: extracting an accompanying signal in a first predetermined position of the first equipment and obtaining information of an accompanying signal in a first predetermined position; extracting an accompanying signal in a second predetermined position of the first equipment and obtaining information of an accompanying signal in a second predetermined position; and obtaining the first delay value generated during the transmission of the accompanying signal in the first equipment in accordance with the information of the accompanying signal in the first predetermined position and the second predetermined position. 3. The delay compensation method according to claim 1, characterized in that the step of obtaining a first delay value generated during the transmission of the accompanying signal in the first equipment, and a second delay value generated during the transmission of the accompanying signal in the second equipment, respectively, further includes: extracting an accompanying signal in a third predetermined position of the second equipment and obtaining information of an accompanying signal in a third predetermined position; extracting the accompanying signal in the fourth predetermined position of the second equipment and obtaining information of the accompanying signal in the fourth predetermined position; and obtaining a second delay value generated during the transmission of the accompanying signal in the second equipment in accordance with the information of the accompanying signal in the third predetermined position and the fourth predetermined position. 4. The delay compensation method according to claim 1, characterized in that the first predetermined delay value of the first equipment is the maximum delay value measured by the first equipment in a predetermined period of time, and the second predetermined delay value of the second equipment is the maximum delay value measured by the second equipment in a predetermined period of time. 5. The method of delay compensation according to claim 4, characterized in that the calculation formula for the delay compensation value is as follows: delay compensation value = (maximum delay value of the first equipment is the first delay value) + (maximum delay value of the second equipment is the second delay value). 6. The method of delay compensation according to claim 1, characterized in that the step of performing delay compensation in the process of transmitting an overhead signal in accordance with the delay compensation value includes: performing delay compensation in the process of transmitting an overhead signal through the “first come, first go” queue (FIFO); wherein the output of the FIFO queue is controlled by the delay compensation value. 7. The delay compensation method according to claim 6, characterized in that the step of controlling the output of the FIFO queue by means of the delay compensation value includes: converting the delay compensation value to N cycle values of the FIFO queue read / write clock in accordance with the FIFO queue read / write clock; and serial output of service signals after recording N service signals in the FIFO queue, wherein N is an integer that is greater than or equal to 1. 8. A delay compensation device, comprising: an extraction module, configured to receive an accompanying signal transmitted along with the service signal in the process of transmitting the service signal from the first equipment to the second equipment; a delay receiving unit configured to obtain a first delay value generated during an accompanying signal transmission in the first equipment, and a second delay value generated during an accompanying signal transmission in the second equipment, respectively; a difference value obtaining unit configured to obtain a first difference value between a first delay value and a first predetermined delay value of a first equipment, and a second difference value between a second delay value and a second predetermined delay value of a second equipment; an insertion unit configured to insert the first difference value into the service signal and transmit the first difference value together with the service signal to the second equipment; a compensation receiving unit configured to extract a first difference value from an overhead signal on the second equipment and obtain a delay compensation value necessary in the process of transmitting an overhead signal in accordance with the first difference value and the second difference value; and a compensation module configured to perform delay compensation on the service signal during the transmission of the service signal in accordance with the delay compensation value. 9. The delay compensation device according to claim 8, characterized in that the delay receiving module comprises: a first clock signal acquiring module adapted to extract an accompanying signal in a first predetermined position of the first equipment and obtain information of an accompanying signal in a first predetermined position; a second clock signal acquiring module adapted to extract an accompanying signal in a second predetermined position of the first equipment and obtain information of an accompanying signal in a second predetermined position; and a first delay receiving submodule configured to obtain a first delay value generated during the transmission of the accompanying signal in the first equipment in accordance with the information of the accompanying signal in the first predetermined position and the second predetermined position. 10. The delay compensation device according to claim 8 or 9, characterized in that the delay receiving module further comprises: a third clock signal acquiring module adapted to extract an accompanying signal in a third predetermined position of the second equipment and obtain information of an accompanying signal in a third predetermined position; a fourth clock signal acquiring module adapted to extract an accompanying signal in a fourth predetermined position of the second equipment and obtain information of an accompanying signal in a fourth predetermined position; and the second delay receiving submodule, configured to obtain a second delay value generated during the transmission of the accompanying signal in the second equipment in accordance with the information of the accompanying signal in the third predetermined position and the fourth predetermined position. 11. The delay compensation device according to claim 8, characterized in that the first predetermined delay value of the first equipment is the maximum delay value measured by the first equipment in a given period of time; and the second predetermined delay value of the second equipment is the maximum delay value measured by the second equipment in a predetermined period of time. 12. The delay compensation device according to claim 11, characterized in that the calculation formula for the delay compensation value is as follows: delay compensation value = (maximum delay value of the first equipment is the first delay value) + (maximum delay value of the second equipment is the second delay value). 13. The delay compensation device according to claim 8, characterized in that the compensation module comprises: a compensation submodule, configured to perform delay compensation during the transmission of an overhead signal by means of the FIFO queue, wherein the output of the FIFO queue is controlled by the delay compensation value. 14. The delay compensation device according to claim 13, characterized in that the compensation submodule comprises: a conversion module configured to convert the delay compensation value into N cycle values of the FIFO queue read / write clock signal in accordance with the FIFO queue read / write clock signal; and an output module configured to sequentially output service signals after writing N service signals to the FIFO queue, wherein N is an integer that is greater than or equal to 1. 15. A computer-readable storage medium containing a computer program, wherein the computer program comprises a program command that, when executed by a computer, enables the computer to execute the method according to any one of claims. 1-7.

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