CN102136901A - Time synchronization method, device and system - Google Patents

Abstract

The embodiment of the invention discloses a time synchronization method, device and system, and relates to the communication field. In order to provide the xDSL technology that realizes high-precision time synchronization and meet the needs of mobile services, the technical solution provided by the embodiment of the present invention is as follows: when the uplink and downlink delays between the PMD layer of the receiving end and the PMD layer of the sending end are equal, the local The first receiving time information when the DTU deframer receives the detection bits of the first detection data transmission unit; the second transmission time information when the local DTU framer sends the detection bits of the second detection data transmission unit; The first transmission time information when detecting the detection bit of the data transmission unit and the second reception time information when receiving the detection bit of the second detection data transmission unit; according to the first and second transmission time information and the first and second reception time The time of the information is adjusted so that the local clock and the clock of the sending end achieve time synchronization.

Description

Time synchronization method, device and system

technical field

The present invention relates to the communication field, in particular to a time synchronization method, device and system.

Background technique

With the development of wireless technology, the gradual commercialization of third-generation mobile communications and LTE (Long Term Evolution, Long Term Evolution), mobile base stations are gradually developing in the direction of high-density deployment, high bandwidth, and low cost. Therefore, it is required to apply the broadband access technology to the mobile bearer network. In order to reduce the cost of the mobile bearer network. At the same time, broadband access technology needs to provide high-precision clock transmission, that is, high-precision frequency synchronization and high-precision time synchronization, so as to meet the needs of mobile services.

xDSL (Digital subscriber line, digital subscriber system) technology is the most widely deployed access technology at present, and it can be used as a solution to reduce the cost of mobile bearer network when it is applied to mobile bearer network. At present, xDSL technology has provided NTR (Network Time Reference, network clock reference) solution, which can meet the requirements of high-precision frequency synchronization for mobile services.

In terms of time synchronization, due to the existing xDSL system, the uplink and downlink delays of the physical layer are not equal (that is, not symmetrical), and cannot meet the PTP (Precision Time Protocol, time synchronization protocol) scheme for the uplink and downlink of the physical layer. Delay symmetry requirements. Therefore, the existing xDSL system cannot adopt PTP to realize high-precision time synchronization. In addition, the existing Ethernet system uses synchronous pulse signals for time synchronization. Division Multiplexing, Orthogonal Frequency Division Multiplexing (OFDM) systems, etc.), there is no clear boundary between adjacent symbols. Therefore, it is difficult for existing xDSL systems to achieve high-precision time synchronization using the method used by Ethernet access systems. .

In the process of realizing the present invention, the inventors found that there are at least the following problems in the prior art: the existing xDSL system cannot provide high-precision time synchronization to meet the needs of mobile services.

Contents of the invention

Embodiments of the present invention provide a time synchronization method, device and system, which can provide xDSL technology for high-precision time synchronization to meet the needs of mobile services.

In order to achieve the above object, embodiments of the present invention adopt the following technical solutions:

A time synchronization method comprising:

When the uplink and downlink time delays between the PMD layer of the receiving end and the PMD layer of the sending end are equal, when receiving the first detection data sending unit sent by the sending end, the first receiving time information is obtained, and the first receiving time information Time information when the DTU deframer at the receiving end receives the detection bits of the first detection data transmission unit;

When sending the second detection data sending unit to the sending end, the second sending time information is obtained, and the second sending time information is when the DTU framer of the receiving end sends the detection bit of the second detection data sending unit time information;

Receive the first sending time information and the second receiving time information sent by the sending end, the first sending time information is the time information when the DTU framer of the sending end sends the detection bits of the first detection data sending unit, The second receiving time information is the time information when the DTU deframer at the sending end receives the detection bits of the second detection data transmission unit;

Perform time adjustment according to the first sending time information, the first receiving time information, the second sending time information and the second receiving time information, so that the clock of the receiving end and the clock of the sending end reach the same time Synchronize.

A time synchronization device comprising:

The data sending unit parses the frame module, configured to receive the first detection data sending unit sent by the sending end; or receive the first sending time information and the second receiving time information sent by the sending end, the first sending time information is The time information when the DTU framer at the sending end sends the detection bits of the first detection data sending unit, and the second receiving time information is when the DTU deframer at the sending end receives the detection bits of the second detection data sending unit time information;

A data sending unit framing module, configured to generate a second detection data sending unit, and send the second detection data sending unit to the sending end;

The clock acquisition module is used to acquire the first receiving time information, the first receiving time information is the time information when the data sending unit parses the frame module to receive the detection bit of the first detection data sending unit; or, acquire the second 2. Sending time information, the second sending time information is the time information when the framing module of the data sending unit sends the detection bits of the second detection data sending unit;

Correction module, for when the uplink and downlink delays between the PMD layer of the receiving end and the PMD layer of the sending end are equal, according to the first receiving time information and the second sending time information obtained by the clock acquisition module, the data sending unit Time adjustment is performed on the first sending time information and the second receiving time information obtained by the frame parsing module, so that the clock of the receiving end is synchronized with the clock of the sending end.

A time synchronization device comprising:

The data sending unit framing module is used to send the first detection data sending unit to the receiving end, and send the first sending time information and the second receiving time information acquired by the clock acquisition module to the receiving end;

The data sending unit parses the frame module, which is used to receive the second detection data sending unit sent by the receiving end;

A clock acquiring module, configured to acquire first sending time information, where the first sending time information is the time information when the data sending unit framing module sends the detection bits of the first detected data sending unit; or, acquire the second 2. Receiving time information, where the second receiving time information is the time information when the frame analysis module of the data sending unit receives the detection bits of the second detection data sending unit.

A time synchronization system, including a sending end and a receiving end;

The sending end is configured to obtain the first transmission when sending the first detection data sending unit to the receiving end when the uplink and downlink delays between the PMD layer of the sending end and the PMD layer of the receiving end are equal. Time information, the first sending time information is the time information when the DTU framer of the sending end sends the detection bit of the first detection data transmission unit; when receiving the second detection data transmission unit sent by the receiving end, Acquire the second receiving time information, the second receiving time information is the time information when the DTU deframer of the sending end receives the detection bits of the second detection data sending unit; send the first sending time to the receiving end information and said second receiving time information;

The receiving end is configured to obtain first receiving time information when receiving the first detection data sending unit sent by the sending end, and the first receiving time information is that the DTU deframer of the receiving end receives the first detection The time information when the detection bit of the data sending unit; When sending the second detection data sending unit to the sending end, obtain the second sending time information, and the second sending time information is that the DTU framer of the receiving end sends the described The time information when detecting the bit of the second detection data sending unit; receiving the first sending time information and the second receiving time information sent by the sending end; according to the first sending time information, the first receiving time information, Time adjustment is performed on the second sending time information and the second receiving time information, so that the clock of the receiving end is time-synchronized with the clock of the sending end.

The time synchronization method, device and system provided by the embodiments of the present invention, when the uplink and downlink time delays between the PMD layer of the receiving end and the PMD layer of the sending end are equal, the sending end sends the DTUframer to the detection bit of the first detection data transmission unit The obtained first sending time information is notified to the receiving end, and the DTU deframer of the receiving end obtains the first receiving time information when receiving the detection bit of the first detection data sending unit; and, the receiving end obtains the DTU framer and sends the second detection data sending unit The second sending time information when the detection bit is detected, the sending end notifies the receiving end of the second receiving time information obtained when the DTU deframer receives the detection bit of the second detection data sending unit; then, the receiving end sends the information according to the first sending time, Time adjustment is performed on the first receiving time information, the second sending time information and the second receiving time information, so that the clock at the receiving end is synchronized with the clock at the sending end. Therefore, a simple time synchronization mechanism can be used in the xDSL system to achieve accurate time synchronization between the clock at the sending end and the clock at the receiving end, meeting the needs of mobile services for time synchronization accuracy. Therefore, it is possible to achieve high-precision time synchronization while reducing the cost of the mobile bearer network.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the drawings that need to be used in the description of the embodiments. Apparently, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings according to these drawings without creative efforts.

FIG. 1 is a schematic flowchart of a time synchronization method provided by an embodiment of the present invention;

FIG. 2 is a schematic flowchart of another time synchronization method provided by an embodiment of the present invention;

Fig. 3 is the schematic diagram of time delay between the PMD layer of the sending end and the PMD layer of the receiving end according to the embodiment of the present invention;

Fig. 4 is a structural diagram of a PMS-TC layer functional model according to an embodiment of the present invention;

FIG. 5 is a structural diagram of a PMS-TC layer functional model according to an embodiment of the present invention;

6 is a schematic diagram of a framing format of a data sending unit according to an embodiment of the present invention;

7 is a schematic diagram of a framing format of a data sending unit according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a time synchronization device provided by an embodiment of the present invention;

FIG. 9 is a schematic diagram of another time synchronization device provided by an embodiment of the present invention;

FIG. 10 is a schematic diagram of a time synchronization system provided by an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In order to provide xDSL technology for high-precision time synchronization to meet the needs of mobile services, an embodiment of the present invention provides a time synchronization method, as shown in Figure 1, including:

101. When the uplink and downlink delays between the PMD (Physical Media Dependent) layer of the receiving end and the PMD layer of the sending end are equal, when the receiving end receives the first detection data transmission unit sent by the sending end, obtain the first One receiving time information, the first receiving time information is the time information when the DTU deframer at the receiving end receives the detection bit of the first detection data transmission unit;

For example, the uplink delay and downlink delay between the PMD layer of the receiving end and the PMD layer of the sending end can be obtained before the time synchronization operation between the clock of the sending end and the clock of the receiving end, for example, by means of measurement, quantification, etc. . When it is determined that the uplink and downlink delays between the PMD layer at the receiving end and the PMD layer at the sending end are not equal according to the obtained uplink delay and downlink delay between the PMD layer at the receiving end and the PMD layer at the sending end, you can use the compensated The method is adjusted so that the uplink and downlink delays between the PMD layer at the receiving end and the PMD layer at the sending end are equal.

When receiving a DTU (Data Transfer Unit, data sending unit), the receiving end can determine that the specified bit data in the DTU is used for time synchronization according to predetermined rules (such as the serial number of the DTU or the indicator in the DTU, etc.) . Here, the DTU is referred to as a first detection data transmission unit, and the specified bit data is referred to as a detection bit, for example, the first bit of the first detection data transmission unit. When the local DTUdeframer receives the detection bit of the first detection data sending unit, the receiving end obtains the time information of the local clock, that is, the first reception time information, such as the time stamp Ts1.

102. The receiving end obtains second sending time information when sending the second detection data sending unit to the sending end, and the second sending time information is the detection bit of the second detecting data sending unit sent by the DTU framer of the receiving end time information;

For example, the receiving end can determine a certain DTU to be sent to the sending end for time synchronization according to preset rules. Here, the DTU is referred to as a second detection data transmission unit. When the local DTU framer sends the specified bits of the second detection data sending unit, the receiving end obtains the time information of the local clock, that is, the second sending time information, such as the time stamp Ts2. Here, this predetermined bit is called a detection bit.

In addition, the detection bit of the second detection data sending unit and the detection bit of the first detection data sending unit can be in the same position in the first detection data sending unit and the second detection data sending unit, such as the first detection data sending unit unit and the second detection data to send the first bit of the unit. Certainly, the detection bits of the second detection data sending unit and the detection bits of the first detection data sending unit may also be in different positions in the first detection data sending unit and the second detection data sending unit respectively.

103. The receiving end receives the first sending time information and the second receiving time information sent by the sending end, and the first sending time information is when the DTU framer of the sending end sends the detection bit of the first detection data sending unit The time information of the time information, the second receiving time information is the time information when the DTU deframer of the sending end receives the detection bit of the second detection data transmission unit;

For example, the receiving end can determine whether the DTU includes the time information when the DTU framer of the sending end sends the detection bit data of the first detection DTU according to a predetermined rule (such as the DTU sequence number of the received DTU or the indicator in the DTU, etc.), That is, the first sending time information, such as the time stamp Tm1. And, the receiving end can determine the time information when the DTU deframer of the sending end receives the detection bit of the second detection data transmission unit in a certain DTU according to predetermined rules (such as the sequence number of the received DTU or the indication mark in the received DTU, etc.) , that is, the second receiving time information, such as the time stamp Tm2. Wherein, the first information-carrying data sending unit or the second information-carrying data sending unit is transmitted through a first delay channel. Here, the DTU including the first sending time information is called a first information-carrying data sending unit, and the DTU including the second receiving time information is called a second information-carrying data sending unit. The receiving end obtains the first sending time information from the specified bits of the first information-bearing data sending unit, and obtains the second receiving time information from the specified bits of the second information-bearing data sending unit.

Alternatively, the receiving end can also determine whether the DTU contains the first sending time information and the second receiving time information, such as the time stamp Tm1 and the time stamp Tm. Wherein, the third information-carrying data sending unit transmits through the first delay channel. Here, the DTU is referred to as a third information-carrying data sending unit, and the receiving end obtains the first sending time information and the second receiving time information from specified bits of the third information-carrying data sending unit.

Or, the receiving end can also obtain the time information (i.e. the first sending time information) when the DTU framer of the sending end sends the detection bit of the first detection data transmission unit from the management message sent by the sending end, such as the time stamp Tm1. Then, the receiving end receives the management message sent after the sending end, from which the time information (i.e. the second receiving time information) when the DTU deframer of the sending end receives the detection bit of the second detection data transmission unit, such as the time stamp Tm2. Here, the management message including the first sending time information is called a first management message, and the management message including the second receiving time information is called a second management message.

Or, the receiving end can also receive the management message sent by the sending end, and obtain the time information (that is, the first sending time information) when the DTU framer of the sending end sends the detection bit of the first detection data sending unit and the DTU framer of the sending end receives the first detection bit. 2. Time information when the detection bit of the data sending unit is detected (that is, the second receiving time information). Here, the management message is referred to as the third management message.

104. The receiving end performs time adjustment according to the first sending time information, the first receiving time information, the second sending time information, and the second receiving time information, so that the clock of the receiving end and the clock of the sending end reach the same time Synchronize.

For example, when the uplink and downlink interleaving delays generated by the interleaver on the channel between the sending end and the receiving end are equal (when the interleaver is disabled, the uplink and downlink interleaving delays are considered to be equal), you can After obtaining the first sending time information Tm1, the first receiving time information Ts1, the second sending time information Ts2 and the second receiving time information Tm2, according to the formula Offset=(Ts1+Ts2-Tm1-Tm2)/2, the receiving The time offset Offset between the clock at the end and the clock at the sender. When the interleaver is disabled, the uplink and downlink interleaving delays are considered to be equal. In the case that the uplink and downlink interleaving delays generated by the interleaver are not equal, the uplink and downlink interleaving delay difference Delay _ilv of the interleaver is obtained. After the receiving end obtains the first sending time information Tm1, the first receiving time information Ts1, the second sending time information Ts2 and the second receiving time information Tm2, according to the formula Offset=(Ts1+Ts2-Tm1-Tm2-Delay _ilv )/ 2. To obtain the time offset Offset between the clock of the receiving end and the clock of the sending end. After the time offset Offset is obtained, the time of the local clock is adjusted according to the time offset Offset, so that the clock of the receiving end is synchronized with the clock of the sending end. Generally speaking, the master clock is at the transmitting end and the slave clock is at the receiving end. Time synchronization between the clock at the receiving end and the clock at the sending end means time synchronization between the slave clock and the master clock.

In addition, before performing time synchronization, and after obtaining the uplink and downlink delay difference Delay _pmd between the PMD layer of the receiving end and the PMD layer of the sending end, the uplink and downlink time between the PMD layer of the receiving end and the PMD layer of the sending end are not adjusted. Adjustment is delayed, and after the receiving end obtains the first sending time information Tm1, the first receiving time information Ts1, the second sending time information Ts2 and the second receiving time information Tm2, according to the formula Offset=(Ts1+Ts2-Tm1- Tm2-Delay _ilv -Delay _pmd )/2 to obtain the time offset Offset between the clock at the receiving end and the clock at the sending end. And, the time of the local clock is adjusted according to the time offset Offset, so that the clock of the receiving end and the clock of the sending end achieve time synchronization.

The time synchronization method that this embodiment provides, by when the uplink and downlink time delay between the PMD layer of the receiving end and the PMD layer of the sending end is equal, the receiving end obtains the first detection data sending unit when the DTU deframer receives the first detection data transmission unit sent by the sending end Receiving time information, the receiving end obtains the second sending time information when sending the detection bit of the second detection data sending unit to the sending end, and obtains the first sending time information and the second receiving time information sent by the sending end; then, according to the first Time synchronization adjustment is performed on the first sending time information, the first receiving time information, the second sending time information, and the second receiving time information. Therefore, a simple time synchronization mechanism can be used in the xDSL system to achieve precise time synchronization between the clock at the sending end and the clock at the receiving end, meeting the needs of mobile services for time synchronization accuracy. Therefore, it is possible to achieve high-precision time synchronization while reducing the cost of the mobile bearer network.

In addition, when the sending end and the receiving end have multiple delay channels, the above-mentioned DTU framer and DTU deframer can be set on only one delay channel between the sending end and the receiving end, and the clock of the sending end and the clock of the receiving end can be synchronized. Time synchronization. Thus, high-precision time synchronization is realized with a small number of devices.

Corresponding to the above method, the embodiment of the present invention also provides a time synchronization method, as shown in Figure 2, including:

201. When the uplink and downlink delays between the PMD layer of the sending end and the PMD layer of the receiving end are equal, when the sending end sends the first detection data sending unit to the receiving end, obtain the first sending time information, and the first sending time The information is the time information when the DTU framer at the sending end sends the detection bits of the first detection data transmission unit;

For example, the uplink and downlink delay between the PMD layer of the sending end and the PMD layer of the receiving end can be obtained before the time synchronization operation between the clock of the sending end and the clock of the receiving end, for example, by means of measurement and quantization. According to the obtained uplink and downlink time delay between the sending end and the PMD layer of the receiving end, when it is determined that the uplink and downlink time delay between the sending end and the receiving end's PMD layer is not equal, it can be adjusted by means of compensation, so that the sending end's The uplink and downlink delays between the PMD layer and the PMD layer at the receiving end are equal.

The sender generates corresponding DTUs from the data and management messages sent by the TPS-TC (Transport Protocol Specific-Transmission Convergence) layer. When the sending end sends the generated DTU to the receiving end, it can determine a specified bit in a certain DTU according to a preset rule, and use it for time synchronization. Here, the DTU is referred to as a first detection data transmission unit, and the specified bit is referred to as a detection bit, such as the first bit. When the local DTU framer sends the detection bit of the first detection data transmission unit, the sending end obtains the time information of the local clock, that is, the first transmission time information, such as the time stamp Tm1.

202. The sending end acquires second receiving time information when receiving the second detection data sending unit sent by the receiving end, and the second receiving time information is that the DTU deframer at the sending end receives the detection bit of the second detection data sending unit time information;

For example, when receiving a DTU, the sending end can determine that the specified bits in the DTU are data for time synchronization according to predetermined rules (such as the sequence number of the DTU, etc.), and the DTU is referred to as the second detection data herein. sending unit. When the local DTU deframer receives the detection bit of the second detection data transmission unit, the sending end obtains the time information of the local clock, that is, the second receiving time information, such as the time stamp Tm1.

203. The sending end sends the first sending time information and the second receiving time information to the receiving end, so that the receiving end performs timing according to the first sending time information and the second receiving time information Synchronized adjustments.

For example, the sending end may determine a certain DTU according to a preset rule, add the first sending time information to the DTU, and send the DTU to the receiving end. The DTU is the first information-carrying data sending unit. Then, the sending end may determine a certain DTU according to a preset rule, add the second receiving time information to the DTU, and send the DTU to the receiving end. The DTU is the second information-carrying data sending unit. Wherein, the first information-carrying data sending unit or the second information-carrying data sending unit is transmitted through a first delay channel. For example, the sending end may add the first sending time information to the DTU with the specified sequence number and send it to the receiving end. Then, the sending end adds the second receiving time information to the DTU with the specified sequence number and sends it to the receiving end. Alternatively, the sending end may also select a DTU as the first information-carrying data sending unit after sending the first detection data sending unit, and add the first sending time information and the indication identifier in the first information-carrying data sending unit, the indication The identifier is used to indicate that the DTU contains the first sending time information. And, after receiving the second detection data sending unit, select a DTU as the second information-carrying data sending unit, add the second receiving time information and the indicator in the second information-carrying data sending unit, and the indicator is used to indicate The DTU includes the second receiving time information.

Alternatively, the sending end may also determine a certain DTU according to a preset rule, add the first sending time information and the second receiving time information to the DTU, and send the DTU to the receiving end. The DTU is the third information-carrying data sending unit. Wherein, the third information-carrying data sending unit transmits through the first delay channel.

Alternatively, the sending end may also send a management message including the first sending time information to the receiving end, where the management message is referred to as the first management message, and then, the sending end sends a management message including the second receiving time information to the receiving end , the management message is referred to as the second management message here.

Alternatively, the sending end may also send a management message to the receiving end, which includes the first sending time information and the second receiving time information, and the management message is the third management message.

In addition, before performing time synchronization, and after obtaining the uplink and downlink delay difference Delay _pmd between the PMD layer of the receiving end and the PMD layer of the sending end, the uplink and downlink time between the PMD layer of the receiving end and the PMD layer of the sending end are not adjusted. Adjustment is delayed, and after the receiving end obtains the first sending time information Tm1, the first receiving time information Ts1, the second sending time information Ts2 and the second receiving time information Tm2, according to the formula Offset=(Ts1+Ts2-Tm1- Tm2-Delay _ilv -Delay _pmd )/2 to obtain the time offset Offset between the clock at the receiving end and the clock at the sending end. And, the time of the local clock is adjusted according to the time offset Offset, so that the clock of the receiving end and the clock of the sending end achieve time synchronization.

The time synchronization method provided by the present embodiment, when the uplink and downlink time delay between the PMD layer of the receiving end and the PMD layer of the sending end is equal, the sending end obtains when the DTU framer sends the detection bit of the first detection data transmission unit to the receiving end The first sending time information, the sending end obtains the second receiving time information when the DTU deframer receives the detection bit of the second detection data sending unit sent by the receiving end, and notifies the first sending time information and the second receiving time information to The receiving end; enabling the receiving end to perform time synchronization adjustment according to the first sending time information and the second receiving time information. Therefore, a simple time synchronization mechanism can be used in the xDSL system to achieve precise time synchronization between the clock at the sending end and the clock at the receiving end, meeting the needs of mobile services for time synchronization accuracy. Therefore, it is possible to achieve high-precision time synchronization while reducing the cost of the mobile bearer network.

In addition, when the sending end and the receiving end have multiple delay channels, the above-mentioned DTU framer and DTU deframer can be set on only one delay channel between the sending end and the receiving end, and the clock of the sending end and the clock of the receiving end can be synchronized. Time synchronization. Thus, high-precision time synchronization is realized with a small number of devices.

In the above embodiments, when performing time synchronization operations, the uplink and downlink delays between the PMD layer at the sending end and the PMD layer at the receiving end need to be equal. In existing xDSL systems (such as ADSL, ADSL 2/2+, VDSL 2, etc.), the uplink and downlink delays between the central office and the PMD layer of the terminal have relatively good symmetry, especially in the VDSL2 system. The structure of the existing xDSL can be shown in FIG. 3 . Generally speaking, the master clock is located at the central office, and the slave clock is located at the terminal. In the embodiment of the present invention, when the PMS-TC (Physical Media Specific-Transmission Convergence, Physical Media Specific-Transmission Convergence) layer has only one delay channel, the DTUframer is located before the screamer (as shown in Figure 4). Business data and management data are encapsulated into the data sending unit by DTU framer. Optionally, when the PMS-TC layer enables two delay channels, the DTU framer only exists on the 0th delay channel (that is, the channel of p=0, as shown in FIG. 5 ). When the PMS-TC layer enables two delay channels, only the delay difference generated by the interleaver in the 0th delay channel is measured. It is assumed that Delay1 is the delay from the PMD layer of the central office to the PMD layer of the terminal, that is, the downlink delay of the PMD layer, and Delay2 is the delay from the PMD layer of the terminal to the PMD layer of the central office, that is, the uplink delay of the PMD layer. When the uplink and downlink delays between the PMD layer of the client and the PMD layer of the terminal are not equal, that is, Delay1≠Delay2, some means can be used to make the uplink and downlink delays of the PMD layer equal, that is, Delay1=Delay2. For example, the uplink and downlink delays of the PMD layer are respectively obtained by measurement, quantization, etc., and then the uplink delay and the downlink delay between the PMD layer of the central office and the PMD layer of the terminal are equal through compensation, that is, Delay1=Delay2, with symmetry.

Taking the scene shown in FIG. 3 as an example, the above-mentioned embodiment will be further described in detail in the following ways.

method one

The time synchronization method of this embodiment includes:

301. When the uplink and downlink delays between the PMD layer of the central office and the PMD layer of the terminal are equal, at the central office, the DTU framer generates a DTU from the data and management messages sent by the upper layer (TPS-TC layer), and sends the generated DTU to the terminal DTUs. And, according to the preset setting, the time information when the DTU framer sends the xth bit of a certain DTU is obtained from the local clock (ie, the master clock), that is, the first sending time information (time stamp Tm1). And, the time stamp Tm1 acquired by the central office is carried in the next DTU.

Specifically, it can be as follows: when the uplink and downlink delays of the PMD layer of the central office and the PMD layer of the terminal are equal, at the central office, the DTU framer located at the PMS-TC layer receives the data and management messages sent from the TPS-TC layer, and will receive Data and management messages generate DTUs. Wherein, the size of the DTU is equal to the payload of one or more RS codewords (one RS codeword is K bytes), that is, n*K bytes (n>=1). Each DTU can be contained in a fixed number of symbols (DMTsymbol), that is, each symbol contains an integer number of DTUs, or each DTU is contained in an integer number of symbols, that is, L _p =k*DTU _size =k*n* K or k*L _p =DTU _size =n*K (wherein, k and n are both integers not less than 1, and L _p is the number of bits included in a symbol, that is, the size of a symbol). In addition, when the channel corresponding to the DTU framer contains an interleaver, the size of the interleaver (ie D*I) is equal to one or more RS codewords (wherein, the length of an RS codeword is N bytes), ie D*I =m*N.

Assume that the DTU framer is preset to reserve t bytes at a specific position when generating DTU. According to the predetermined rule, select the corresponding DTU (i.e. the first information bearing data sending unit), and send the time information of the local clock (master clock) when the DTU framer sends the xth bit of the previous DTU, i.e. the time stamp Tm1, Added to the reserved t bytes.

For example, taking DTU a as an example, the DTU framer at the central office generates DTU a according to the data and management messages received from the TPS-TC layer. When sending the xth bit of DTU a, obtain the time information of the local clock, that is, the time stamp Tm1, and as shown in Figure 6 or 7, reserve t bytes in DTU a+1 to carry the time stamp Tm1 . In addition, after the DTU framer obtains the time stamp Tm1 of the x-th bit of sending DTU a, it is not limited to carrying the time stamp Tm1 in DTU a+1, and can also carry the time stamp Tm1 in other designated DTUs. In the remaining t bytes.

302. At the terminal, according to the preset setting, obtain the time information when the DTU deframer receives the xth bit of the DTU sent by the central office for time synchronization from the local clock (ie, the slave clock), that is, the first receiving time information (time stamp Ts1). And, when receiving the next DTU of the DTU, the time stamp Tm1 when the DTU framer at the central office sends the xth bit of the DTU is obtained from the next DTU.

For example, when the DTU deframer of the terminal receives the xth bit of DTU a, it obtains the time information of the local clock, that is, the time stamp Ts1, and when receiving DTU a+1, it analyzes DTU a+1, and from the DTU The time stamp Tm1 when the DTU framer at the central office sends the xth bit of DTU a is obtained from the t bytes reserved by a+1.

303. At the terminal, the DTU framer generates a DTU according to the data and management messages sent by the upper layer (TPS-TC layer), and sends the generated DTU to the central office. And, according to the preset setting, the time information when the DTU framer sends the xth bit of each DTU is obtained from the local clock (ie, the slave clock), that is, the second sending time information (time stamp Ts2).

For example, taking DTU b as an example, at the terminal, the DTU framer at the PMS-TC layer receives the data and management messages sent from the TPS-TC layer, and generates DTU b according to the received data and management messages. And, when the DTU framer sends the xth bit of DTU b, it obtains the time information of the local clock, that is, the time stamp Ts2.

304. At the central office, according to the preset setting, obtain the time information at the xth bit of the DTU sent by the DTU deframer receiving terminal for time synchronization from the local clock (ie, the master clock), that is, the second receiving time information (time stamp Tm2). And, the time stamp Tm2 obtained by the central office is carried in the DTU sent to the terminal later.

For example, when the DTU deframer at the central office receives the xth bit of DTU b, it obtains the time information of the local clock, that is, the time stamp Tm2. Moreover, after the DTU deframer at the central office obtains the timestamp Tm2 when receiving the xth bit of DTU b, as shown in Figure 6 or 7, t bytes can also be reserved in DTU c to carry the acquired timestamp Tm2 The serial number of the DTU corresponding to the time stamp, and the indication bit used to indicate the sending and receiving attribute of the carried time stamp. Wherein, the indication bit can be set as follows: when the indication bit is set to 1, the time stamp is the sending time stamp of the DTU; when the indication bit is set to 0, the time stamp is the receiving time stamp of the DTU. Here, the indication bit in the reserved t bytes of DTU c is set to 0. Then, send the DTU c carrying the timestamp Tm2 to the terminal. In addition, in the DTU containing the reserved t bytes sent by the sender, the serial number of the DTU corresponding to the time stamp, and the indication bits used to indicate the sending and receiving attributes of the carried time stamp can be carried. in the reserved t bytes.

In this embodiment, the central office transmits the time stamps Tm1 and Tm2 respectively through two DTUs. Of course, the central office can also carry the acquired time stamps Tm1 and Tm2 in the same DTU and send the DTU to the terminal.

305. At the terminal, when receiving the DTU carrying the time stamp Tm2 received by the DTU deframer at the central office, acquire from the DTU the time stamp Tm2 when the DTU deframer at the central office receives the xth bit of the DTU sent by the terminal.

For example, when the DTU deframer of the terminal receives DTU c, it analyzes DTU c, and determines that the time stamp obtained from the t bytes is the time stamp Tm2 when the DTU deframer of the central office receives the xth bit of DTU b.

306. At the terminal, perform time synchronization adjustment according to the time stamps Tm1, Ts1, Ts2, and Tm2.

Specifically, if interleaving is not enabled on the channel between the sending end and the receiving end, after knowing the time stamps Tm1, Ts1, Ts2, and Tm2, the equation Tm1+Delay1+Offset=Ts1, and Ts2 can be obtained +Delay2-Offset=Tm2, where Offset is the time offset between the master-slave clocks of the central office and the terminal, and Delay1 is the delay required for the xth bit of DTU to be sent from the MUX module of the central office to the DEMUX module of the terminal , Delay2 is the delay required for the xth bit of the DTU to be sent from the MUX module of the terminal to the DEMUX module of the central office. Since the uplink and downlink delays of the PMD layer of the central office and the PMD layer of the terminal are equal, that is, Delay1=Delay2, the equation can be derived from the above equation

Offset=(Ts1+Ts2-Tm1-Tm2)/2

When interleaving is enabled on the channel between the sending end and the receiving end, it is assumed that Delay3 is the delay generated by interleaving from the master clock to the slave clock, that is, the downlink delay generated by interleaving, and Delay4 is the delay generated by the slave clock. The delay generated by interleaving from the clock to the master clock, that is, the uplink delay generated by interleaving. Then, after knowing the timestamps Tm1, Ts1, Ts2 and Tm2, the equation can be obtained

Tm1+Delay1+Delay3+Offset=Ts1;

Ts2+Delay2+Delay4-Offset=Tm2.

At this time, Delay1 and Delay2 do not include the interleaving delay caused by the interleaver. When Delay1≠Delay2, it is necessary to make Delay1=Delay2 through compensation.

When the uplink and downlink interleaving delays generated by interleaving are equal (that is, Delay3=Delay4, or (D-1)×(I-1) is equal), the equation can be derived

Offset=(Ts1+Ts2-Tm1-Tm2)/2

When the uplink and downlink interleaving delays generated by interleaving are not equal (that is, Delay3≠Delay4, or (D-1)×(I-1) is not equal), the terminal can calculate the interleaver parameters according to different uplink and downlink interleaver parameters. The generated uplink and downlink delay difference Delay _ilv , that is, Delay3-Delay4=Delay _ilv . From this, the equation Offset=(Ts1+Ts2-Tm1-Tm2-Delay _ilv )/2 can be derived

After calculating the Offset according to the above formula, the terminal can adjust the local clock (that is, the slave clock) according to the offset, so that the master clock and the slave clock can achieve time synchronization.

way two

The time synchronization method of this embodiment includes:

401. When the uplink and downlink delays between the PMD layer of the central office and the PMD layer of the terminal are equal, at the central office, the DTU framer generates a DTU according to the data and management messages sent by the upper layer (TPS-TC layer), and sends the DTU to the terminal . And, according to the preset setting, whenever h DTUs are separated between the DTU currently sent by the DTU framer and the last DTU to obtain the timestamp, the first DTU sent by the DTU framer to send the current DTU is obtained from the local clock (ie, the main clock). The time information of x bits, that is, the first transmission time information (time stamp Tm1. And, the time stamp Tm1 acquired by the central office is carried in the next DTU.

Specifically, it can be as follows: when the uplink and downlink delays of the PMD layer of the authority end and the PMD layer of the terminal are equal, at the office end, the DTU framer located at the PMS-TC layer receives the data and management messages sent from the TPS-TC layer, and according to the received Data and management messages generate DTUs. Assuming that it is pre-set at the central office or terminal, t bytes are reserved in the DTU when the DTU framer at the PMS-TC layer generates the DTU. When h DTUs are separated between each other, obtain the time stamp when the DTU framer sends the xth bit of the current DTU from the local clock (that is, the main clock), and add the time stamp to the t bytes reserved for the next DTU .

For example, after the DTU framer at the central office generates DTUs according to the data and management messages received from the TPS-TC layer, it obtains the time stamp when the DTU frame r sends the xth bit of the current DTU every h DTUs, that is, the When there are h DTUs between the DTU a currently generated by the DTU framer and the last DTU to obtain the timestamp, the DTU framer at the central office obtains the time information of the local clock when sending the xth bit of DTU a, that is, the timestamp Tm1. And, as shown in Figure 6 or 7, t bytes are reserved in DTU a+1 to carry the timestamp Tm1.

In addition, after the DTU framer obtains the time stamp Tm1 when sending the xth bit of DTU a, it is not limited to carrying the time stamp Tm1 in DTU a+1, and can also carry the time stamp Tm1 in the reserved space of other DTUs. of t bytes.

Further, it is also possible to carry the time stamp Tm1 when the DTU framer sends the xth bit of DTUa in all DTUs or a specified number of DTUs between the two consecutive time stamped DTU a and DTU a+h . In addition, indication bits can be carried in these DTUs, and the indication bits can be used to indicate the number of times these DTUs carry the timestamp, or whether it is the first time to send the timestamp.

For example, after the central office obtains the time stamp when the DTU framer sends the xth bit of DTU a, it carries the time stamp Tm1 in the reserved t bytes of DTU a+1, and sets the indicated bit to 1, that is, DTU a+1 is the DTU carrying the timestamp Tm1 for the first time. Carry the time stamp Tm1 in the predetermined t bytes from DTU a+2 to DTU a+k (k≤h+1), and set the indication bit to 0, that is, DTU a+2,... , the time stamp Tm1 information has been carried in the DTU before DTU a+k.

Or, after the central office obtains the time stamp when the DTU framer sends the xth bit of DTU a, it carries the time stamp Tm1 of DTU a in the reserved t bytes of DTU a+1, and sets the indication bit to 1 , that is, DTU a+1 is the DTU carrying the timestamp Tm1 for the first time. The time stamp Tm1 is carried in the reserved t bytes of DTU a+2 to DTU a+k (k≤h+1), and the indication bits are respectively set to 2, ..., k, that is DTU a+2 is the DTU carrying the timestamp Tm1 for the second time, ..., DTU a+k is the DTU carrying the timestamp Tm1 for the kth time.

402. At the terminal, according to the preset setting, when receiving a DTU separated by h DTUs from the DTU obtained by the previous central office, obtain the DTU deframer from the local clock (that is, the slave clock) and receive the xth DTU of the DTU The time information of the bit time, that is, the first receiving time information (time stamp Ts1). And, when receiving the next DTU of the DTU, the time stamp Tm1 when the DTU framer at the central office sends the xth bit of the DTU is obtained from the next DTU.

For example, when the terminal determines that the received DTU a is separated by h DTUs from the DTU obtained by the previous central office, the DTU deframer of the terminal obtains the time information of the local clock when the xth bit of DTU a is received, that is, the timestamp Ts1, and, when receiving DTU a+1, analyze DTU a+1, and obtain the DTU framer at the central office from the reserved t bytes of DTU a+1 when sending the xth bit of DTU a Timestamp Tm1.

403. At the terminal, the DTU framer generates a DTU according to the data and management messages sent by the upper layer (TPS-TC layer), and sends the DTU to the central office. And, according to the preset setting, whenever h DTUs are separated between the DTU currently sent by the DTU framer and the last DTU to obtain the timestamp, the DTU framer sends the current DTU from the local clock (that is, the slave clock) The time information at the xth bit, that is, the second transmission time information (time stamp Ts2).

For example, the terminal obtains the time stamp when the DTU framer sends the xth bit of the current DTU every h DTUs, that is, when there are h DTUs between DTU b and the last DTU that obtained the time stamp, the DTU framer of the terminal When the xth bit of DTU b is sent, the time information of the local clock is obtained, that is, the time stamp Ts2.

404. At the central office, according to the preset setting, when receiving a DTU separated by h DTUs from the DTU obtained by the previous terminal, obtain the DTU deframer from the local clock (ie, the master clock) and receive the xth DTU of the DTU The time information of the bit time, that is, the second reception time information (time stamp Tm2). And, the time stamp Tm2 obtained by the central office is carried in the DTU sent to the terminal later.

For example, when the central office determines that there is a distance of h DTUs between the received DTU b and the DTU obtained by the last terminal, the DTU deframer at the central office obtains the time information of the local clock when receiving the xth bit of DTU b, that is, the time Stamp Tm2, and, after the DTUdeframer obtains the time stamp Tm2 when receiving the xth bit of DTU b, it can also reserve t bytes in DTU c as shown in Figure 6 or 7 to carry the obtained time stamp Tm2 and the sequence number of the DTU b corresponding to the timestamp, and the indication bit used to indicate the sending and receiving attributes of the carried timestamp. Wherein, the indication bit can be set as follows: when the indication bit is set to 1, the time stamp is the sending time stamp of the DTU; when the indication bit is set to 0, the time stamp is the receiving time stamp of the DTU. Here, the indication bit in the reserved t bytes of DTU c is set to 0. Then, send the DTU c carrying the timestamp Tm2 to the terminal.

In this embodiment, the central office transmits the time stamps Tm1 and Tm2 respectively through two DTUs. Of course, the central office can also carry the acquired time stamps Tm1 and Tm2 in the same DTU and send the DTU to the terminal.

405. At the terminal, when receiving the DTU carrying the time stamp Tm2 received by the DTU deframer at the central office, acquire from the DTU the time stamp Tm2 when the DTU deframer at the central office receives the xth bit of the DTU sent by the terminal.

For example, when the terminal receives DTU c, it parses DTU c, and the time stamp obtained from the t bytes is the time stamp Tm2 when the DTU deframer at the central office receives the xth bit of DTU b.

406. At the terminal, perform time synchronization adjustment according to the time stamps Tm1, Ts1, Ts2, and Tm2. For the specific adjustment method, refer to step 306, which will not be repeated here.

way three

The time synchronization method of this embodiment includes:

501. When the uplink and downlink delays between the PMD layer of the central office and the PMD layer of the terminal are equal, at the central office, the DTU framer generates a DTU according to the data and management messages sent by the upper layer (TPS-TC layer), and sends the DTU to the terminal . And, according to the preset setting, obtain the time information when the DTU framer sends the xth bit of each DTU from the local clock (i.e. the master clock), i.e. the first transmission time information (time stamp Tm1. And, the central office The acquired time stamp Tm1 is carried in a prescribed management message (such as an eoc message) and sent to the terminal through an embedded channel.

502. At the terminal, according to the preset setting, the time information when the DTU deframer receives the xth bit of each DTU, that is, the first receiving time information (time stamp Ts1), is obtained from the local clock (ie, the slave clock). Moreover, the management message is received through the embedded channel, and the time stamp Tm1 when the DTU framer at the central office sends the xth bit of the DTU is obtained from the management message.

503. At the terminal, the DTU framer generates a DTU according to the data and management messages sent by the upper layer (TPS-TC layer), and sends the DTU to the central office. And, according to the preset setting, the time information when the DTU framer sends the xth bit of each DTU is obtained from the local clock (ie, the slave clock), that is, the second sending time information (time stamp Ts2).

504. At the central office, according to preset settings, the time information when the DTU deframer receives the xth bit of each DTU, that is, the second receiving time information (time stamp Tm2), is obtained from the local clock (ie, the master clock). In addition, the time stamp Tm2 obtained by the central office is carried in a prescribed management message (such as an eoc message), and sent to the terminal through an embedded channel.

Here, the central office transmits the time stamps Tm1 and Tm2 respectively through two management messages. Of course, the central office can also carry the obtained time stamps Tm1 and Tm2 in the same management message and send it to the terminal through an embedded channel.

505. At the terminal, receive the management message through the embedded channel, and obtain the time stamp Tm2 when the DTU deframer at the central office receives the xth bit of the DTU from the management message.

506. At the terminal, perform time synchronization adjustment according to the time stamps Tm1, Ts1, Ts2, and Tm2. For the specific adjustment method, refer to step 306, which will not be repeated here.

Optionally, in order to ensure the security and accuracy of the time stamp during transmission, in the above embodiment, the time stamp and its related information carried in the reserved t bytes of the DTU can also be verified, For example, use CRC (Cyclical Redundancy Check, Cyclic Redundancy Check) or Gray (Golay) code to obtain the verification information of the timestamp and its related information, and carry the verification information with the reserved t words of DTU section.

Optionally, in the above embodiment, the DTU framer can also be used to output data at a uniform speed, so as to ensure the stability of the PMS-TC layer delay and make the time synchronization operation more accurate. Further, in the above embodiment, the PMS-TC layer may output data at a uniform rate to ensure a constant input rate of the PMD layer, thereby making the interface delay between the PMS-TC layer and the PMD layer stable. Therefore, the uplink and downlink delays between the output of the PMS-TC layer and the input of the peer PMS-TC layer are equal, that is, the uplink and downlink delays are symmetrical.

In addition, in the above-mentioned embodiment, the ways for the central office and the terminal to obtain the time stamp are preset, but the way for the central office and the terminal to obtain the time stamp may also be determined through management message negotiation.

The time synchronization method provided by the embodiments under the above-mentioned various modes, when the uplink and downlink time delays between the PMD layer of the authority end and the PMD layer of the terminal are equal, when the detection bit of the first detection data transmission unit is sent by the central office by the DTU framer The first sending time information is notified to the terminal, and the terminal obtains the first receiving time information when the DTU deframer receives the detection bit of the first detection data transmission unit, and the terminal obtains the time when the DTU framer sends the detection bit of the second detection data transmission unit For the second sending time information, the central office notifies the terminal of the second receiving time information when the DTUdeframer receives the detection bit of the second detection data sending unit, and then, the terminal sends the second sending time information according to the first sending time information and the first receiving time information. Time adjustment is performed on the time information and the second received time information, so that the clock of the terminal and the clock of the central office achieve time synchronization. Therefore, a simple time synchronization mechanism can be used in the xDSL system to achieve accurate time synchronization between the master and slave clocks between the central office and the terminal, and to meet the needs of mobile services for time synchronization accuracy. Therefore, it is possible to achieve high-precision time synchronization while reducing the cost of the mobile bearer network.

In addition, when the central office and the terminal have multiple delay channels, the above-mentioned DTU framer and DTU deframer can be set on only one delay channel between the central office and the terminal to perform time synchronization between the master clock and the slave clock. Thus, high-precision time synchronization is realized with a small number of devices.

Corresponding to the above method, an embodiment of the present invention also provides a time synchronization device, as shown in FIG. 8 , including:

The data sending unit parses the frame module 801, configured to receive the first detection data sending unit sent by the sending end; or, receive the first sending time information and the second receiving time information sent by the sending end, the first sending time information The time information when the framing module of the data sending unit at the sending end sends the detection bit of the first detection data sending unit, and the second receiving time information is the time information when the frame analysis module of the data sending unit at the sending end receives the first detection bit 2. Time information when detecting the detection bit of the data transmission unit;

A data sending unit framing module 802, configured to generate a second detection data sending unit, and send the second detection data sending unit to the sending end;

A clock acquisition module 803, configured to acquire first receiving time information, where the first receiving time information is the time information when the data sending unit parsing frame module 801 receives the detection bits of the first detected data sending unit; or, Acquire second sending time information, where the second sending time information is time information when the data sending unit framing module 802 sends the detection bits of the second detection data sending unit;

Correction module 804, for when the uplink and downlink time delay between the PMD layer of the receiving end and the PMD layer of the sending end is equal, according to the first receiving time information and the second sending time information obtained by the clock obtaining module 803, the data The sending unit analyzes the first sending time information and the second receiving time information received by the frame module 801 and performs time adjustment, so that the clock of the receiving end is time-synchronized with the clock of the sending end.

Further, the data sending unit parsing frame module 801 specifically includes:

An analysis frame data receiving unit, configured to receive the first detection data sending unit or the first information-carrying data sending unit or the second information-carrying data sending unit or the third information-carrying data sending unit sent by the sending end;

An analysis frame time acquisition unit, configured to acquire first sending time information from the first information-bearing data sending unit received by the analysis frame data receiving unit; or, from the second information-bearing data received by the analysis frame data receiving unit Acquiring the second receiving time information from the sending unit; or acquiring the first sending time information and the second receiving time information from the third information-carrying data sending unit received by the parsing frame data receiving unit.

Further, the parsing frame data receiving unit is specifically configured to receive the first information-carrying data sending unit or the second information-carrying data sending unit or the third information-carrying data sending unit through the first delay channel.

Alternatively, the data sending unit parsing frame module 801 specifically includes:

An analysis frame data receiving unit, configured to receive the first detection data sending unit sent by the sending end;

a message receiving unit, configured to receive the first management message or the second management message or the third management message sent by the sending end;

An analysis frame time obtaining unit, configured to obtain first sending time information from the first management message received by the message receiving unit; or obtain second receiving time information from the second management message received by the message receiving unit; Or, acquire the first sending time information and the second receiving time information from the third management message received by the message receiving unit.

Further, the correcting module 804 specifically includes:

An offset acquisition unit, configured to, when the uplink and downlink interleaving delays of the interleaver are equal, according to the first transmission time information Tm1, the first reception time information Ts1, the second transmission time information Ts2, the The second receiving time information Tm2 and the formula Offset=(Ts1+Ts2-Tm1-Tm2)/2 to obtain the time offset Offset;

The time adjustment unit is configured to adjust the clock of the receiving end according to the time offset Offset obtained by the offset obtaining unit, so that the clock of the receiving end and the clock of the sending end achieve time synchronization.

Alternatively, the correcting module 804 specifically includes:

A delay difference obtaining unit, configured to obtain the uplink and downlink interleaving delay difference Delay _ilv of the interleaver;

An offset acquisition unit, configured to, according to the first transmission time information Tm1, the first reception time information Ts1, the second transmission time information Ts2, the second reception time information Tm2, the uplink and downlink of the interleaver Interleaving delay difference Delay _ilv and the formula Offset=(Ts1+Ts2-Tm1-Tm2-Delay _ilv )/2 to obtain the time offset Offset;

The time adjustment unit is configured to adjust the clock of the receiving end according to the time offset Offset obtained by the offset obtaining unit, so that the clock of the receiving end and the clock of the sending end achieve time synchronization.

The time synchronization device provided by the present embodiment, when the uplink and downlink time delay between the PMD layer of the receiving end and the PMD layer of the sending end is equal, the receiving end receives the detection bit of the first detection data sending unit sent by the sending end at the DTU deframer When the first receiving time information is obtained, the receiving end obtains the second sending time information when sending the detection bit of the second detection data sending unit to the sending end, and receives the first sending time information and the second receiving time information sent by the sending end ; Then, perform time synchronization adjustment according to the first sending time information, the first receiving time information, the second sending time information and the second receiving time information. Therefore, a simple time synchronization mechanism can be used in the xDSL system to achieve precise time synchronization between the clock at the sending end and the clock at the receiving end, meeting the needs of mobile services for time synchronization accuracy. Therefore, it is possible to achieve high-precision time synchronization while reducing the cost of the mobile bearer network.

Corresponding to the above-mentioned device, an embodiment of the present invention also provides a time synchronization device, as shown in FIG. 9 , including:

A data sending unit framing module 901, configured to send the first detection data sending unit to the receiving end, and send the first sending time information and the second receiving time information acquired by the clock acquisition module to the receiving end;

The data sending unit parses the frame module 902, configured to receive the second detection data sending unit sent by the receiving end;

A clock acquiring module 903, configured to acquire first sending time information, where the first sending time information is the time information when the data sending unit framing module 901 sends the detection bits of the first detected data sending unit; or, Acquire second receiving time information, where the second receiving time information is time information when the data sending unit parsing frame module 902 receives the detection bits of the second detected data sending unit.

Further, the data sending unit framing module 901 specifically includes:

A generating data unit is used to generate a first detection data sending unit or a first information-carrying data sending unit or a second information-carrying data sending unit or a third information-carrying data sending unit according to preset settings, the first information-carrying data sending unit The sending unit includes the first sending time information, the second information-carrying data sending unit includes the second receiving time information, and the third information-carrying data sending unit includes the first sending time information and the second receiving time information. 2. Receive time information;

The sending data unit is configured to send the first detection data sending unit or the first information-carrying data sending unit or the second information-carrying data sending unit or the third information-carrying data sending unit generated by the generating data unit to the receiving end.

Further, the sending data unit is specifically configured to send the first information-carrying data sending unit or the second information-carrying data sending unit or the third information-carrying data sending unit to the receiving end through the first delay channel.

Alternatively, the data sending unit framing module 901 specifically includes:

generating a data unit, configured to generate a first detection data sending unit according to preset settings;

a sending data unit, configured to send the first detection data sending unit generated by the generating data unit to the receiving end

a message sending unit, configured to send a first management message to the receiving end, where the first management message includes the first sending time information acquired by the clock acquisition module; or, send a second management message to the receiving end, The second management message includes the second receiving time information acquired by the clock acquisition module; or, send a third management message to the receiving end, the third management message includes the first transmission time information acquired by the clock acquisition module time information and the second received time information.

The time synchronization device that this embodiment provides, by when the uplink and downlink time delay between the PMD layer of the receiving end and the PMD layer of the sending end is equal, the sending end acquires when the DTU framer sends the detection bit of the first detection data transmission unit to the receiving end The first sending time information, the sending end obtains the second receiving time information when the DTU deframer receives the detection bit of the second detection data sending unit sent by the receiving end, and notifies the receiving end of the first sending time information and the second receiving time information , so that the receiving end performs time synchronization adjustment according to the first sending time information and the second receiving time information. Therefore, a simple time synchronization mechanism can be used in the xDSL system to achieve precise time synchronization between the clock at the sending end and the clock at the receiving end, meeting the needs of mobile services for time synchronization accuracy. Therefore, it is possible to achieve high-precision time synchronization while reducing the cost of the mobile bearer network.

Corresponding to the above method and device, the embodiment of the present invention also provides a time synchronization system, as shown in FIG. 10 , including a sending end 1001 and a receiving end 1002;

The sending end 1001 is used to obtain the first sending time when sending the first detection data sending unit to the receiving end 1002 when the uplink and downlink delays between the PMD layer of the sending end 1001 and the PMD layer of the receiving end 1002 are equal Information, the first sending time information is the time information when the DTU framer of the sending end 1001 sends the detection bits of the first detection data transmission unit; it is obtained when receiving the second detection data transmission unit sent by the receiving end 1002 The second receiving time information, the second receiving time information is the time information when the local DTUdeframer receives the detection bits of the second detection data sending unit; send the first sending time information and the received data to the receiving end 1002 the second receiving time information;

The receiving end 1002 is configured to obtain first receiving time information when receiving the first detection data sending unit sent by the sending end 1001, and the first receiving time information is that the DTU deframer of the receiving end 1002 receives the first receiving time information. Time information when detecting the detection bit of the data sending unit; when sending the second detection data sending unit to the sending end 1001, the second sending time information is obtained, and the second sending time information is the DTU framer of the receiving end 1002 Time information when sending the detection bits of the second detection data sending unit; receiving the first sending time information and the second receiving time information sent by the sending end 1001; according to the first sending time information, the first The receiving time information, the second sending time information and the second receiving time information are time adjusted so that the clock of the receiving end 1002 and the clock of the sending end 1001 achieve time synchronization.

Further, the receiving end 1002 is specifically configured to: when the uplink and downlink interleaving delays of the interleaver are equal, according to the first sending time information Tm1, the first receiving time information Ts1, and the second sending time information Ts2, the second receiving time information Tm2 and the formula Offset=(Ts1+Ts2-Tm1-Tm2)/2, obtaining a time offset Offset; and adjusting the clock of the receiving end according to the time offset Offset, so that The clock of the receiving end 1002 and the clock of the sending end 1001 achieve time synchronization.

Further, the receiving end 1002 is specifically configured to acquire the uplink and downlink interleaving delay difference Delay _ilv of the interleaver; according to the first sending time information Tm1, the first receiving time information Ts1, the second sending time information Information Ts2, the second receiving time information Tm2, the uplink and downlink interleaving delay difference Delay _ilv of the interleaver and the formula Offset=(Ts1+Ts2-Tm1-Tm2-Delay _ilv )/2, to obtain the time offset Offset; according to The time offset Offset adjusts the clock of the receiving end, so that the clock 1002 of the receiving end and the clock of the sending end 1001 achieve time synchronization.

The time synchronization method, device and system provided by the embodiments of the present invention, when the uplink and downlink time delays between the PMD layer of the receiving end and the PMD layer of the sending end are equal, the sending end sends the DTUframer to the detection bit of the first detection data transmission unit The first sending time information is notified to the receiving end, and the receiving end obtains the first receiving time information when the DTU deframer receives the detection bit of the first detection data transmission unit, and the receiving end obtains the detection of the second detection data transmission unit sent by the DTU framer The second sending time information at the time of the bit, the sending end notifies the receiving end of the second receiving time information when the DTU deframer receives the detection bit of the second detection data sending unit, and then, the receiving end sends the first receiving time information according to the first sending time information. The time information, the second sending time information and the second receiving time information are time adjusted, so that the clock at the receiving end is synchronized with the clock at the sending end. Therefore, in the xDSL system, a simple time synchronization mechanism can be used to realize accurate time synchronization between the clock of the transmitting end and the clock of the receiving end, which meets the requirement of the mobile service for time synchronization accuracy. Therefore, it is possible to achieve high-precision time synchronization while reducing the cost of the mobile bearer network.

In addition, when the sending end and the receiving end have multiple delay channels, the above-mentioned DTU framer and DTU deframer can be set on only one delay channel between the sending end and the receiving end, and the clock of the sending end and the clock of the receiving end can be synchronized. Time synchronization. Thus, high-precision time synchronization is realized with a small number of devices.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented through computer programs to instruct related hardware, and the programs can be stored in a computer-readable storage medium. During execution, it may include the processes of the embodiments of the above-mentioned methods. Wherein, the storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM) or a random access memory (Random Access Memory, RAM), etc.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (18)

1. A time synchronization method, characterized in that, comprising: When the uplink and downlink delays between the physical medium-related PMD layer of the receiving end and the PMD layer of the sending end are equal, when receiving the first detection data sending unit sent by the sending end, the first receiving time information is obtained, and the first receiving time information is obtained. The receiving time information is the time information when the data sending unit of the receiving end parses the frame module DTU framer and receives the detection bits of the first detection data sending unit; When sending the second detection data sending unit to the sending end, the second sending time information is obtained, and the second sending time information is that the data sending unit framing module DTU framer of the receiving end sends the second detection data sending The time information when the bit is detected by the unit; Receive the first sending time information and the second receiving time information sent by the sending end, the first sending time information is the time information when the DTU framer of the sending end sends the detection bits of the first detection data sending unit, The second receiving time information is the time information when the DTU deframer at the sending end receives the detection bits of the second detection data transmission unit; Perform time adjustment according to the first sending time information, the first receiving time information, the second sending time information and the second receiving time information, so that the clock of the receiving end and the clock of the sending end reach the same time Synchronize. 2. The time synchronization method according to claim 1, wherein the receiving the first sending time information and the second receiving time information sent by the sending end comprises: receiving the first information-carrying data sending unit sent by the sending end; Acquiring first sending time information from the first information-carrying data sending unit; receiving the second information-carrying data sending unit sent by the sending end; acquiring second receiving time information from the second information-carrying data sending unit; The first information-carrying data sending unit or the second information-carrying data sending unit is transmitted through a first delay channel. 3. The time synchronization method according to claim 1, wherein the receiving the first sending time information and the second receiving time information sent by the sending end comprises: receiving the third information-carrying data sending unit sent by the sending end; acquiring first sending time information and second receiving time information from the third information-bearing data sending unit; The third information-carrying data sending unit is transmitted through the first delay channel. 4. The time synchronization method according to claim 1, wherein the receiving the first sending time information and the second receiving time information sent by the sending end comprises: receiving a first management message sent by the sending end; Acquiring first sending time information from the first management message; receiving a second management message sent by the sending end; Acquiring second reception time information from the second management message; The receiving the first sending time information and the second receiving time information sent by the sending end includes: receiving a third management message sent by the sending end; Obtain the first sending time information and the second receiving time information from the third management message. 5. The time synchronization method according to claim 1, wherein, according to the first sending time information, the first receiving time information, the second sending time information and the second receiving time The time adjustment of the information so that the clock of the receiving end and the clock of the sending end achieve time synchronization includes: When the uplink and downlink interleaving delays of the interleaver are equal, according to the first sending time information Tm1, the first receiving time information Ts1, the second sending time information Ts2, the second receiving time information Tm2 and the formula Offset=(Ts1+Ts2-Tm1-Tm2)/2, to obtain the time offset Offset; Adjusting the clock of the receiving end according to the time offset Offset, so that the clock of the receiving end and the clock of the sending end achieve time synchronization. 6. The time synchronization method according to claim 1, wherein, according to the first sending time information, the first receiving time information, the second sending time information and the second receiving time The time adjustment of the information so that the clock of the receiving end and the clock of the sending end achieve time synchronization includes: Obtain the uplink and downlink interleaving delay difference Delay _ilv of the interleaver; According to the first sending time information Tm1, the first receiving time information Ts1, the second sending time information Ts2, the second receiving time information Tm2, the uplink and downlink interleaving delay difference Delay _ilv of the interleaver and the formula Offset=(Ts1+Ts2-Tm1-Tm2-Delay _ilv )/2, to obtain the time offset Offset; Adjusting the clock of the receiving end according to the time offset Offset, so that the clock of the receiving end and the clock of the sending end achieve time synchronization. 7. The time synchronization method according to any one of claims 1-6, further comprising: Obtain the uplink and downlink delay between the PMD layer of the receiving end and the PMD layer of the sending end; When the uplink and downlink time delay between the PMD layer of the receiving end and the PMD layer of the sending end is not equal, the uplink and downlink time delay between the PMD layer of the receiving end and the PMD layer of the sending end is adjusted by means of compensation The delays are equal. 8. A time synchronization device, characterized in that, comprising: The data sending unit parses the frame module, configured to receive the first detection data sending unit sent by the sending end; or receive the first sending time information and the second receiving time information sent by the sending end, the first sending time information is The time information when the framing module of the data sending unit at the sending end sends the detection bit of the first detection data sending unit, and the second receiving time information is the time information when the frame analysis module of the data sending unit at the sending end receives the second Time information when detecting the detection bit of the data transmission unit; A data sending unit framing module, configured to generate a second detection data sending unit, and send the second detection data sending unit to the sending end; The clock acquisition module is used to acquire the first receiving time information, the first receiving time information is the time information when the data sending unit parses the frame module to receive the detection bit of the first detection data sending unit; or, acquire the second 2. Sending time information, the second sending time information is the time information when the framing module of the data sending unit sends the detection bits of the second detection data sending unit; Correction module, for when the uplink and downlink delays between the PMD layer of the receiving end and the PMD layer of the sending end are equal, according to the first receiving time information and the second sending time information obtained by the clock acquisition module, the data sending unit Time adjustment is performed on the first sending time information and the second receiving time information received by the frame analysis module, so that the clock of the receiving end is synchronized with the clock of the sending end. 9. The time synchronization device according to claim 8, wherein the data sending unit parses the frame module comprising: An analysis frame data receiving unit, configured to receive the first detection data sending unit or the first information-carrying data sending unit or the second information-carrying data sending unit or the third information-carrying data sending unit sent by the sending end; An analysis frame time acquisition unit, configured to acquire first sending time information from the first information-bearing data sending unit received by the analysis frame data receiving unit; or, from the second information-bearing data received by the analysis frame data receiving unit Acquiring the second receiving time information from the sending unit; or acquiring the first sending time information and the second receiving time information from the third information-carrying data sending unit received by the parsing frame data receiving unit. 10. The time synchronization device according to claim 8, characterized in that, the data sending unit parsing frame module comprises: An analysis frame data receiving unit, configured to receive the first detection data sending unit sent by the sending end; a message receiving unit, configured to receive the first management message or the second management message or the third management message sent by the sending end; An analysis frame time obtaining unit, configured to obtain first sending time information from the first management message received by the message receiving unit; or obtain second receiving time information from the second management message received by the message receiving unit; Or, acquire the first sending time information and the second receiving time information from the third management message received by the message receiving unit. 11. The time synchronization device according to claim 10, wherein the parsing frame data receiving unit is specifically configured to receive the first information-bearing data sending unit or the second information-bearing data sending unit through a first delay channel The sending unit or the third information-carrying data sending unit. 12. The time synchronization device according to any one of claims 8-11, wherein the correction module comprises: An offset acquisition unit, configured to, when the uplink and downlink interleaving delays of the interleaver are equal, according to the first transmission time information Tm1, the first reception time information Ts1, the second transmission time information Ts2, the The second time information Tm2 is received, and the time offset Offset is obtained; The time adjustment unit is configured to adjust the clock of the receiving end according to the time offset Offset obtained by the offset obtaining unit, so that the clock of the receiving end and the clock of the sending end achieve time synchronization. 13. The time synchronization device according to any one of claims 8-11, wherein the correction module comprises: A delay difference obtaining unit, configured to obtain the uplink and downlink interleaving delay difference Delay _ilv of the interleaver; An offset acquisition unit, configured to, according to the first transmission time information Tm1, the first reception time information Ts1, the second transmission time information Ts2, the second reception time information Tm2, the uplink and downlink of the interleaver Interweaving delay difference Delay _ilv to obtain the time offset Offset; The time adjustment unit is configured to adjust the clock of the receiving end according to the time offset Offset obtained by the offset obtaining unit, so that the clock of the receiving end and the clock of the sending end achieve time synchronization. 14. A time synchronization device, characterized in that it comprises: The data sending unit framing module is used to send the first detection data sending unit to the receiving end, and send the first sending time information and the second receiving time information acquired by the clock acquisition module to the receiving end; The data sending unit parses the frame module, which is used to receive the second detection data sending unit sent by the receiving end; A clock acquiring module, configured to acquire first sending time information, where the first sending time information is the time information when the data sending unit framing module sends the detection bits of the first detected data sending unit; or, acquire the second 2. Receiving time information, where the second receiving time information is the time information when the frame analysis module of the data sending unit receives the detection bits of the second detection data sending unit. 15. The time synchronization device according to claim 14, wherein the data sending unit framing module comprises: A generating data unit is used to generate a first detection data sending unit or a first information-carrying data sending unit or a second information-carrying data sending unit or a third information-carrying data sending unit according to preset settings, the first information-carrying data sending unit The sending unit includes the first sending time information, the second information-carrying data sending unit includes the second receiving time information, and the third information-carrying data sending unit includes the first sending time information and the second receiving time information. 2. Receive time information; The sending data unit is configured to send the first detection data sending unit or the first information-carrying data sending unit or the second information-carrying data sending unit or the third information-carrying data sending unit generated by the generating data unit to the receiving end. 16. A time synchronization system, comprising a sending end and a receiving end; The sending end is used to obtain the first sending time when sending the first detection data sending unit to the receiving end when the uplink and downlink delays between the PMD layer of the sending end and the PMD layer of the receiving end are equal information, the first sending time information is the time information when the DTU framer of the sending end sends the detection bits of the first detection data sending unit; when receiving the second detection data sending unit sent by the receiving end, the second detection data sending unit is obtained Two receiving time information, the second receiving time information is the time information when the DTU deframer of the sending end receives the detection bits of the second detection data sending unit; sending the first sending time information and the receiving end to the receiving end the second receiving time information; The receiving end is used to obtain first receiving time information when receiving the first detection data sending unit sent by the sending end, and the first receiving time information is that the DTU deframer of the receiving end receives the first detection data The time information when the detection bit of the sending unit; When sending the second detection data sending unit to the sending end, the second sending time information is obtained, and the second sending time information is that the DTU framer of the receiving end sends the second Detecting the time information when detecting the bit of the data sending unit; receiving the first sending time information and the second receiving time information sent by the sending end; according to the first sending time information, the first receiving time information, the Time adjustment is performed on the second sending time information and the second receiving time information, so that the clock of the receiving end is synchronized with the clock of the sending end. 17. The time synchronization system according to claim 16, wherein the receiving end is specifically configured to: when the uplink and downlink interleaving delays of the interleaver are equal, according to the first transmission time information Tm1, the second A receiving time information Ts1, the second sending time information Ts2, the second receiving time information Tm2 and the formula Offset=(Ts1+Ts2-Tm1-Tm2)/2, obtain a time offset Offset; and according to the The time offset Offset adjusts the clock of the receiving end, so that the clock of the receiving end and the clock of the sending end achieve time synchronization. 18. The time synchronization system according to claim 16, wherein the receiving end is specifically used to obtain the uplink and downlink interleaving delay difference Delay _ilv of the interleaver; according to the first transmission time information Tm1, the The first receiving time information Ts1, the second sending time information Ts2, the second receiving time information Tm2, the uplink and downlink interleaving delay difference Delay _ilv of the interleaver and the formula Offset=(Ts1+Ts2-Tm1-Tm2-Delay _ilv )/2, acquiring a time offset Offset; adjusting the clock of the receiving end according to the time offset Offset, so that the clock of the receiving end and the clock of the sending end achieve time synchronization.

Images