Retiming device, signal transmission system and signal transmission method

Abstract

The invention relates to the technical field of communication, and relates to a retiming device, a signal transmission system and a signal transmission method. The retiming device comprises a first data module corresponding to a first link and a second data module corresponding to a second link. The first data module comprises a first receiving module, a first data transmission module and a first sending module, and the first data transmission module comprises a first transmission path; the second data module comprises a second receiving module, a second data transmission module and a second sending module, the second data transmission module comprises a first transmission path and a second transmission path, and the delay of the first transmission path is smaller than that of the second transmission path. In the application, the first data transmission module is only provided with the first transmission path, the first transmission path does not contain a data processing module, the received data is not subjected to data processing operation, and only the received data is subjected to transmission operation, which is equivalent to that the first data module is fixed in a low-delay mode, so that the delay is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a retiming device, a signal transmission system and a signal transmission method. Background Art

[0002] The Peripheral Component Interconnect Express (PCIe) bus is a high-speed bus that connects the processor to peripheral devices in a computer system. With the increase in PCIe signal rate and the increasing application of PCIe bus, the use of retimers with timing recovery function between two PCIe devices is increasing.

[0003] Since retimers have delays, each additional level of retimer will increase the delay, which will cause system performance loss, which is unacceptable in some application scenarios. In addition, according to the PCIe specification, there can generally be two retimers in a given link.

[0004] Figure 1 The dual timer mode schematic diagram according to an exemplary embodiment includes device 1, device 2, and retimer 1 and retimer 2 located between device 1 and device 2 and electrically connected. The link in which data is transmitted from device 1 to device 2 via retimer 1 and retimer 2 is a downlink, and the link in which data is transmitted from device 2 to device 1 via retimer 2 and retimer 1 is an uplink. Regardless of the uplink or downlink, retimer 1 and retimer 2 include modules such as elastic buffer, descrambling / decoding circuit, scrambling / encoding circuit, etc. for data processing. The introduction of these modules will cause higher delay, so how to reduce the delay while ensuring the retimer capacity is a problem that needs to be solved. Summary of the invention

[0005] The present invention provides a retiming device, a signal transmission system and a signal transmission method. The technical solutions disclosed in the present invention are as follows:

[0006] According to a first aspect of an embodiment of the present disclosure, there is provided a retiming device, comprising:

[0007] The first data module corresponding to the first link is used to receive electrical signal data from a device; the first data module includes a first receiving module, a first data transmission module and a first sending module; the first data transmission module includes a first transmission path;

[0008] The second data module corresponding to the second link is used to send the received electrical signal data to the device; the second data module includes a second receiving module, a second data transmission module and a second sending module; the second data transmission module includes a first transmission path and a second transmission path;

[0009] The delay of the first transmission path is smaller than the delay of the second transmission path.

[0010] According to a second aspect of an embodiment of the present disclosure, there is provided a signal transmission system, comprising: a first retiming device along a link transmission direction, an optical transmission system, and a second retiming device;

[0011] The first retiming device includes a first data transmission module corresponding to the downlink and a second data transmission module corresponding to the uplink; the first data transmission module includes a first transmission path; the second data transmission module includes a first transmission path and a second transmission path;

[0012] The second retiming device includes a third data transmission module corresponding to the downlink and a fourth data transmission module corresponding to the uplink; the third data transmission module includes a first transmission path and a second transmission path; the fourth data transmission module includes the first transmission path;

[0013] The delay of the first transmission path is smaller than the delay of the second transmission path.

[0014] According to a third aspect of an embodiment of the present disclosure, a signal transmission method is provided, which is applied to a signal transmission system, including:

[0015] Acquiring a service signal from a root device through a first retiming device;

[0016] transmitting the service signal to a second retiming device through an optical transmission system;

[0017] In the first signal transmission state, the service signal is transmitted to the endpoint device through the second path in the second retiming device.

[0018] According to a fourth aspect of an embodiment of the present disclosure, a signal transmission device is provided, which is applied to a signal transmission system, including:

[0019] an acquisition unit, configured to acquire a service signal from a root device through a first retiming device;

[0020] A first transmission unit, configured to transmit the service signal to a second retiming device via an optical transmission system;

[0021] The second transmission unit is used to transmit the service signal to the endpoint device through the second path in the second retiming device in the first signal transmission state.

[0022] According to the fifth aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided. When instructions in the computer-readable storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute any method in the third aspect of the embodiment of the present disclosure.

[0023] The technical solution provided by the embodiments of the present disclosure brings at least the following beneficial effects:

[0024] The retiming device of the present invention has a first data module corresponding to the first link, which is used to receive electrical signal data from a device. The first data module includes a first receiving module, a first data transmission module and a first sending module. The first data transmission module includes a first transmission path. The second data module corresponding to the second link is used to send the received electrical signal data to the device. The second data module includes a second receiving module, a second data transmission module and a second sending module. The second data transmission module includes a first transmission path and a second transmission path. The delay of the first transmission path is less than the delay of the second transmission path. The first data transmission module only sets the first transmission path, and the first transmission path does not contain a data processing module. No data processing operation is performed on the received data, and only a transmission operation is performed on the received data, which is equivalent to fixing the first data module to a low-latency mode. Compared with the existing retiming device, the delay is greatly reduced.

[0025] The retiming device of the present invention can adapt to the phase deviation between the two clock domains by arranging phase aligners in the first link and the second link to align data and / or de-skew between two synchronous clocks with different phase shifts.

[0026] The signal transmission system of the present application connects two retiming devices through an optical connection, so that dynamic equalization is not required before the data is transmitted to the optical transmission system. Therefore, in the uplink and downlink, the data does not need to be processed before it passes to the optical transmission system. Only the first transmission path is set in the first data transmission module of the downlink and the fourth data transmission module of the uplink, and the first transmission path does not include a data processing module. Only the transmission operation is performed on the received data, which is equivalent to canceling the retiming logic in the first data transmission module of the downlink and the fourth data transmission module of the uplink. At this time, the two retiming devices are approximately regarded as one retiming device. Furthermore, the delay required by the retiming device in the present application is half of that of the dual timing device system in the prior art. When performing long-distance PCIe information transmission, other retiming devices can be added as needed at other locations of the transmission path.

[0027] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 is a schematic diagram of a dual timer mode according to an exemplary embodiment;

[0030] Figure 2 is a schematic diagram showing the internal structure of a retiming device according to an exemplary embodiment;

[0031] Figure 3 is a schematic diagram showing the internal structure of a retiming device according to another exemplary embodiment;

[0032] Figure 4 is a schematic diagram showing the internal structure of a retiming device according to another exemplary embodiment;

[0033] Figure 5 is a schematic diagram of a signal transmission system according to an exemplary embodiment;

[0034] Figure 6 is a schematic diagram of another signal transmission system according to an exemplary embodiment;

[0035] Figure 7 is a schematic diagram of another signal transmission system according to an exemplary embodiment;

[0036] Figure 8 is a schematic diagram of another signal transmission system according to an exemplary embodiment;

[0037] Fig. 9 is a flow chart of a signal transmission method according to an exemplary embodiment;

[0038] Fig.10 The figure is a block diagram of a signal transmission device according to an exemplary embodiment. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar first objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0041] The retiming device in this application is described below:

[0042] First embodiment

[0043] See also Figure 2 , Figure 2 is a schematic diagram showing the internal structure of a retiming device according to an exemplary embodiment. Figure 2 As shown, it includes a first data module 1000 corresponding to the first link, which is used to receive electrical signal data from a device, the first data module 1000 includes a first receiving module 103, a first data transmission module 101 and a first sending module 104 along the link transmission direction, and a second data module 1001 corresponding to the second link, which is used to send the received electrical signal data to the device, and the second data module 1001 includes a second receiving module 105, a second data transmission module 102 and a second sending module 106 along the link transmission direction.

[0044] The first data transmission module 101 includes a first transmission path 1011, and the second data transmission module 102 includes a first transmission path 1021 and a second transmission path 1022, wherein the delay of the first transmission paths 1011 and 1021 is less than the delay of the second transmission path 1022. It can be seen that the second data transmission module 102 supports two transmission paths, thereby allowing the system to work on the first transmission path 1021 (also referred to as a low-latency path) or the second transmission path 1022 (also referred to as a normal path).

[0045] Optionally, the first transmission paths 1011 and 1021 do not include a data processing module, and do not perform data processing operations on the received data, but only perform transmission operations on the received data. The first transmission path 1011 in the first data transmission module 101 does not include a data processing module, and performs transmission operations on the received data. Therefore, the first data transmission module is fixed in a low latency mode.

[0046] Optionally, the second transmission path 1022 includes a data processing module, which performs data processing operations including polarity inversion, channel reversal, block alignment, decoding, descrambling, channel delay compensation, training set modification, encoding, and scrambling on the received data. The first transmission path 1021 in the second data transmission module 102 does not include a data processing module, and performs transmission operations on the received data.

[0047] Optionally, when the first device corresponds to a root device in a link, the first link corresponds to a downlink, and the second link corresponds to an uplink.

[0048] Optionally, when the first device corresponds to an endpoint device in a link, the first link corresponds to an uplink, and the second link corresponds to a downlink.

[0049] In a preferred embodiment, the first data module 1000 further includes a first phase aligner 107. Figure 2 As shown, a first phase aligner 107 is also provided between the first receiving module 103 and the first data transmission module 101. Specifically, an input end of the first phase aligner 107 is connected to the first receiving module 103, and an output end of the first phase aligner 107 is connected to the first transmission path 1011 in the first data transmission module 101.

[0050] In a preferred embodiment, the second data module 1001 further includes a second phase aligner 108. Figure 2 As shown, a second phase aligner 108 is provided between the second receiving module 105 and the second data transmission module 102. Specifically, the input end of the second phase aligner 108 is connected to the second receiving module 105, and the output end of the second phase aligner 108 is connected to the first transmission path 1021 and the second transmission path 1022 in the second data transmission module 102, respectively.

[0051] Among them, the first phase aligner 107 and the second phase aligner 108 are both used to align data between two synchronous clocks with different phase shifts. Taking the first phase aligner 107 as an example, when the clock recovered by the first receiving module 103 is not completely phase-aligned with the output of the clock of the first transmitting module 104, the first phase aligner 107 is needed to solve the changes generated in the short duration in the clock. Phase alignment does not need to add or delete characters from the data stream like an elastic buffer. The phase aligner writes data using one clock and then reads the same data from a small part of the one clock using a synchronous out-of-phase clock. Optionally, the phase aligner can also support path-to-path de-skew by increasing the delay of the data read on the channel that arrives in advance. When the recovered receiver clock (recovered from the data stream) is not completely phase-aligned with the output of the phase-locked loop PLL transmitter clock, a phase aligner is also needed to align the data.

[0052] In some preferred embodiments, Figure 2 As shown, the first sending module 104 includes an electrical signal sending module and an optical signal driving module. The input end of the electrical signal sending module is connected to the first transmission path 1011 in the first data transmission module 101, the output end of the electrical signal sending module is connected to the input end of the optical signal driving module, and the output end of the optical signal driving module is connected to an optical sending module to drive the electrical-optical conversion unit in the optical sending module to load the received electrical signal into the optical wave to form an optical signal.

[0053] In some preferred embodiments, Figure 2 As shown, the second receiving module 105 includes a transimpedance amplifier and an electrical signal receiving module. The input end of the electrical signal receiving module is connected to the output end of the transimpedance amplifier, and the output end of the electrical signal receiving module is connected to the second phase aligner 108. Among them, the input end of the transimpedance amplifier is connected to an optical receiving module to receive the electrical signal output by the optical receiving module.

[0054] In some preferred embodiments, Figure 2 As shown, the second data module 1001 also includes a multiplexer, whose input end is respectively connected to the output end of the first transmission path 1021 and the output end of the second transmission path 1022 in the second data transmission module 102, and the output end of the multiplexer is connected to the input end of the second sending module 106.

[0055] like Figure 2 The retiming device shown is suitable for working in a common reference clock mode, in which the retiming device and the devices at both ends work with the same common reference clock signal. The retiming device preferably also has a third link 1003 for transmitting the common reference clock signal.

[0056] The input end of the third link 1003 is connected to a device, and the output end of the third link 1003 is connected to an optical transmission module to transmit the common reference clock signal obtained from the root device in the devices at both ends. Alternatively, the input end of the third link 1003 is connected to an optical receiving module, and the output end of the third link 1003 is connected to the endpoint device in the devices at both ends to transmit the received common reference clock signal to the endpoint device.

[0057] like Figure 2As shown, the retiming device further includes at least one link training state machine, and the at least one link training state machine is used to perform link training operations. Each of the at least one link training state machine is respectively connected to the first transmission path 1011 in the first data transmission module 101 and the second transmission path 1022 in the second data transmission module 102. Preferably, a data preprocessing module (not shown in the figure) is arranged between the link training state machine and the first transmission path 1011 in the first data transmission module 101, and the data copy of the first transmission path 1011 of the first data transmission module 101 is subjected to polarity inversion, channel reversal, block alignment, decoding, descrambling, and channel delay compensation before being transmitted to the link training state machine. The data copy in the second transmission path 1022 in the second data transmission module 102 is subjected to polarity inversion, channel reversal, block alignment, decoding, descrambling, and channel delay compensation before being transmitted to the link training state machine.

[0058] Optionally, on the second data module 1001 side, link training and equalization can occur in the second transmission path 1022. After the system status is locked, it can switch to the first transmission path 1021 for operation. However, at this time, the second transmission path 1022 can still exist to monitor the link disconnection business or whether to request equalization. In this way, on the basis of the first data transmission module 101 only including the first transmission path 1011 for operation, the delay of the signal transmission system is further reduced.

[0059] Second embodiment

[0060] See also Figure 3 , Figure 3 is a schematic diagram showing the internal structure of a retiming device according to another exemplary embodiment. Figure 3 As shown, the first data module 1000 corresponding to the first link is used to receive electrical signal data from a device, and the first data module 1000 includes a first receiving module 103, a first data transmission module 101 and a first sending module 104, and the first data transmission module 101 includes a first transmission path 1011. The second data module 1001 corresponding to the second link is used to send the received electrical signal data to the first device, and the second data module 1001 includes a second receiving module 105, a second data transmission module 102 and a second sending module 106, and the second data transmission module 102 includes a first transmission path 1021 and a second transmission path 1022, wherein the delay of the first transmission path 1021 is less than the delay of the second transmission path 1022. Optionally, the second data transmission module 102 supports two transmission paths, thereby allowing the system to work on the first transmission path 1021 (also referred to as a low-latency path) or the second transmission path 1022 (also referred to as a normal path).

[0061] Optionally, when the device corresponds to a root device in a link, the first link corresponds to a downlink, and the second link corresponds to an uplink.

[0062] Optionally, when the device corresponds to an endpoint device in a link, the first link corresponds to an uplink, and the second link corresponds to a downlink.

[0063] In a preferred embodiment, Figure 3 As shown, the first data module 1000 further includes a first phase aligner 107, the input end of the first phase aligner 107 is connected to the first receiving module 103, and the output end of the first phase aligner 107 is connected to the first transmission path 1011 in the first data transmission module 101. The second data module 1001 further includes a second phase aligner 108, the input end of the second phase aligner 108 is connected to the second receiving module 105, and the output end of the second phase aligner 108 is respectively connected to the first transmission path 1021 and the second transmission path 1022 in the second data transmission module 102.

[0064] Among them, the first phase aligner 107 and the second phase aligner 108 are both used to align data between two synchronous clocks with different phase shifts. Taking the first phase aligner 107 as an example, when the clock recovered by the first receiving module 103 is not completely phase-aligned with the output of the clock of the first transmitting module 104, the first phase aligner 107 is needed to solve the changes generated in the short duration in the clock. Phase alignment does not need to add or delete characters from the data stream like an elastic buffer. The phase aligner writes data using one clock and then reads the same data from a small part of the clock using a synchronous out-of-phase clock. Optionally, the phase aligner can also support path-to-path de-skew by increasing the delay of the data read on the channel that arrives in advance. A phase aligner is required when the recovered receiver clock (recovered from the data stream) is not completely phase-aligned with the output of the phase-locked loop PLL transmitter clock.

[0065] In some preferred embodiments, Figure 3 As shown, the first sending module 104 includes an electrical signal sending module and an optical signal driving module, the input end of the electrical signal sending module is connected to the first transmission path 1011 in the first data transmission module 101, the output end of the electrical signal sending module is connected to the input end of the optical signal driving module, the output end of the optical signal driving module is connected to the optical sending module in the optical transmission system, and the electrical-optical conversion unit in the optical sending module is driven to load the received electrical signal into the light wave to form an optical signal.

[0066] like Figure 3As shown, the second receiving module 105 includes a transimpedance amplifier and an electrical signal receiving module, the input end of the electrical signal receiving module is connected to the output end of the transimpedance amplifier, and the output end of the electrical signal receiving module is connected to the second phase aligner 108. The input end of the transimpedance amplifier is connected to the optical receiving module in the optical transmission system to receive the electrical signal output by the optical receiving module.

[0067] like Figure 3 As shown, the retiming device also includes at least one link training state machine, at least one link training state machine is used to perform link training operations, and each link training state machine in the at least one link training state machine is respectively connected to the first transmission path 1011 in the first data transmission module 101 and the second transmission path 1022 in the second data transmission module 102. Preferably, a data preprocessing module (not shown in the figure) is arranged between the link training state machine and the first transmission path 1011 in the first data transmission module 101, and the data copy of the first transmission path 1011 of the first data transmission module 101 is processed by polarity inversion, channel reversal, block alignment, decoding, descrambling, and channel delay compensation before being transmitted to the link training state machine. The data copy in the second transmission path 1022 in the second data transmission module 102 is processed by polarity inversion, channel reversal, block alignment, decoding, descrambling, and channel delay compensation before being transmitted to the link training state machine. Further, an asynchronous buffer is arranged between the link training state machine and the data preprocessing module, so that the observed data on the path is asynchronously crossed to the clock area of ​​another path where the link training state machine is located. The retiming apparatus of this embodiment is applicable to an independent reference non-spreading mode and an independent reference spreading mode.

[0068] In the embodiment of the present application, the second transmission path 1022 in the second data transmission module 102 is used for data transmission during training and regular data transmission, and the first transmission path 1021 in the second data transmission module 102 is used for data transmission in the low-latency mode after training. Among them, the second transmission path 1022 in the second data transmission module 102 performs operations including polarity inversion, channel reversal, block alignment, decoding, descrambling, channel delay compensation, training set modification, encoding, and scrambling on the received data. The first transmission path 1021 in the second data transmission module 102 does not include a data processing module and performs a transmission operation on the received data.

[0069] In a preferred embodiment, Figure 3 As shown, the second data module 1001 also includes a multiplexer, whose input end is respectively connected to the output end of the first transmission path 1021 and the output end of the second transmission path 1022 in the second data transmission module 102, and the output end of the multiplexer is connected to the input end of the second sending module 106.

[0070] In a preferred embodiment, the retiming device further includes a third link 1003 and a fourth link 1004. The input end of the third link 1003 is connected to the first receiving module 103 to receive the first clock signal separated and recovered from the service signal in the first receiving module 103, and the output end of the third link 1003 is connected to an optical transmission module 3031 to transmit the first clock signal. In this embodiment, a branch of the third link 1003 is also provided to transmit a copy of the first clock signal to the first transmission module 104. The input end of the fourth link 1004 is connected to an optical receiving module 3043 to receive the second clock signal, and the output end of the fourth link 1004 is connected to the second transmission module 106 to transmit the second clock signal to the second transmission module 106. In this embodiment, since the first link and the second link are located in separate clock domains, the observation data on the first link must be asynchronously crossed to the clock region of the second link where the link training state machine LTSSM is located. Therefore, an asynchronous buffer is provided on the mode to synchronize the data on the first link and the second link.

[0071] Third embodiment

[0072] In another alternative embodiment, Figure 4 is a schematic diagram showing the internal structure of a retiming device according to another exemplary embodiment. Figure 4 As shown, its structure is basically the same as that of the second embodiment.

[0073] The difference from the second embodiment is that the input end of the third link 1003 is connected to the first receiving module 103 to receive the first clock signal separated and recovered from the service signal in the first receiving module 103, and the output end of the third link 1003 is connected to the first sending module 104 to transmit the first clock signal. The input end of the fourth link 1004 is connected to the second receiving module 105 to receive the second clock signal separated and recovered from the service signal in the second receiving module 105, and the output end of the fourth link 1004 is connected to the second sending module 106 to transmit the second clock signal. In this mode, the clock signal in the fourth link 1004 is also separated and recovered from the service signal of the second receiving module 105, and there is no path for transmitting the clock signal with an external device or other retiming device, which simplifies the arrangement of the external link. The retiming device of this embodiment is suitable for an independent reference non-spread spectrum mode and an independent reference spread spectrum mode.

[0074] The data transmission module of the first link of the retiming device of the present invention is only provided with a low-latency first transmission path, that is, the link training and data transmission path between the device and the optical transmission module are fixed to a low-latency mode, and the delay is greatly reduced compared with the existing retiming device. By providing a phase aligner in the first link and the second link to align data and / or de-skew between two synchronous clocks with different phase shifts, the phase deviation between the two clock domains can be adapted.

[0075] The above-mentioned low-latency retiming device of the present invention can be used to send CXL / PCIe protocol data between two devices at a long distance through optical devices, by connecting the devices to the retiming device at one end of each of the two devices, and performing photoelectric / electro-optical conversion and optical fiber / optical fiber array data transmission in the middle through optical devices. In this mode, the two retiming devices implement a retimer logic during operation, and in the PCIE specification, there can usually be a maximum of two retimers in a given link. The implementation of the retiming device of the present invention allows additional retiming devices to be added to motherboard designs with very long routing lengths. Exemplary applications are described below.

[0076] See also Figure 5 , Figure 5 is a schematic diagram of a signal transmission system according to an exemplary embodiment. Figure 5 As shown, the signal transmission system includes a first retiming device 100, an optical transmission system 300 and a second retiming device 200 along the link transmission direction. The link corresponding to the signal transmitted through the first retiming device 100, the optical transmission module 300 and the second retiming device 200 can be a downlink, and the link corresponding to the signal transmitted through the second retiming device 200, the optical transmission module 300 and the first retiming device 100 is an uplink. The first retiming device 100 and the second retiming device 200 are any of the retiming devices in Embodiments 1 to 3.

[0077] In an optional embodiment, if Figure 5 As shown, the first retiming device 100 includes a first data transmission module 101 corresponding to a downlink and a second data transmission module 102 corresponding to an uplink. The first data transmission module 101 includes a first transmission path 1011, and the second data transmission module 102 includes a first transmission path 1021 and a second transmission path 1022. Optionally, the delay of the first transmission paths 1011 and 1021 is less than the delay of the second transmission path 1022.

[0078] In an optional embodiment, if Figure 5As shown, the second retiming device 200 includes a third data transmission module 201 corresponding to the downlink and a fourth data transmission module 202 corresponding to the uplink. The third data transmission module 201 includes a first transmission path 2011 and a second transmission path 2012, and the fourth data transmission module 202 includes a first transmission path 2021. Optionally, the delay of the first transmission paths 2011 and 2021 is less than the delay of the second transmission path 2012.

[0079] In some possible embodiments, the first retiming device 100 and the second retiming device 200 on both sides of the optical transmission system 300 are symmetrically arranged with the same structure, then the first data transmission module 101 in the first retiming device 100 and the fourth data transmission module 202 in the second retiming device 200 are symmetrical, and the second data transmission module 102 in the first retiming device 100 and the third data transmission module 201 in the second retiming device 200 are symmetrical.

[0080] In the embodiment of the present application, the signal transmission system also includes devices located at both ends. Figure 6 , Figure 6 is a schematic diagram of another signal transmission system according to an exemplary embodiment.

[0081] like Figure 6 As shown, different from the electrical transmission path between two retiming devices in some technical solutions, in the embodiment of the present application, the transmission system between the first retiming device 100 and the second retiming device 200 is an optical transmission system 300. The optical transmission system 300 includes a first optical transmission subsystem corresponding to the downlink and a second optical transmission subsystem corresponding to the uplink.

[0082] Optionally, the first optical transmission subsystem includes a first optical transmission module 3011, a first optical path 3012 and a first optical receiving module 3013 along the link transmission direction. The input end of the first optical transmission module 3011 is connected to the first retiming device 100, and is used to convert the electrical signal from the first retiming device 100 into an optical signal, and transmit it from the output end of the first optical transmission module 3011 to the first optical path 3012, and transmit it to the first optical receiving module 3013 through the first optical path 3012. The first optical receiving module 3013 converts the optical signal from the first optical path 3012 into an electrical signal, and transmits it to the second retiming device 200.

[0083] Preferably, the first optical path 3012 may be an optical fiber, or an optical fiber array consisting of a plurality of optical fibers.

[0084] Optionally, the second optical transmission subsystem includes a second optical transmission module 3021, a second optical path 3022 and a second optical receiving module 3023 along the link transmission direction. The input end of the second optical transmission module 3021 is connected to the second retiming device 200, and is used to convert the electrical signal from the second retiming device 200 into an optical signal, and transmit it from the output end of the second optical transmission module 3021 to the second optical path 3022, and transmit it to the second optical receiving module 3023 through the second optical path. The second optical receiving module 3023 converts the optical signal from the second optical path 3022 into an electrical signal, and transmits it to the first retiming device 100.

[0085] Optionally, the first optical transmitting module 3011 and the second optical transmitting module 3021 may be electro-optical converters, and the first optical receiving module 3013 and the second optical receiving module 3023 may be photoelectric converters. In long-distance transmission, optical fiber can effectively increase data transmission speed and reduce latency.

[0086] Preferably, the second optical path 3022 may be a single optical fiber, or an optical fiber array consisting of a plurality of optical fibers.

[0087] like Figure 6 As shown, in addition to the first retiming device 100, the optical transmission system 300 and the second retiming device 200 along the link transmission direction, it also includes a root device 400 and an endpoint device 500 on both sides. Among them, the first retiming device 100 and the second retiming device 200 adopt the retiming device of embodiment 1. Among them, the first retiming device 100 is located between the root device and the optical transmission system 300, and the second retiming device 200 is located between the optical transmission system 300 and the endpoint device.

[0088] like Figure 6 As shown, the first retiming device 100 includes a first receiving module 103, a first phase aligner 107, a first data transmission module 101 and a first sending module 104 corresponding to the downlink along the link transmission direction; and a second receiving module 105, a second phase aligner 108, a second data transmission module 102 and a second sending module 106 corresponding to the uplink along the link transmission direction. The second retiming device 200 includes a third receiving module 203, a third phase aligner 207, a third data transmission module 201 and a third sending module 204 corresponding to the downlink along the link transmission direction, and a fourth receiving module 205, a fourth phase aligner 208, a fourth data transmission module 202 and a fourth sending module 206 corresponding to the uplink along the link transmission direction.

[0089] Among them, phase aligners are used to align data between two synchronous clocks with different phase shifts. When the clock recovered by the receiving module is not completely phase-aligned with the output of the transmitting module clock, a phase aligner is needed to resolve the changes generated in the clock for a short duration. Phase alignment does not require adding or deleting characters from the data stream like an elastic buffer. The phase aligner writes data using one clock and then reads the same data from a small fraction of a clock using a synchronous out-of-phase clock. Optionally, the phase aligner can also support path-to-path de-skew by increasing the delay of the data read out on the channel that arrives in advance. A phase aligner is required when the recovered receiver clock (recovered from the data stream) is not completely phase-aligned with the output of the phase-locked loop PLL transmitter clock.

[0090] exist Figure 6 In the illustrated embodiment, in the downlink, the first data transmission module 101 in the first retimer 100 only includes the first transmission path 1011, and the third data transmission module 201 in the second retimer 200 includes the first transmission path 2011 and the second transmission path 2012, wherein the first transmission path 2011 / 2011 does not include a data processing module, does not perform data processing operations on received data, and only performs transmission operations on received data, therefore, in the downlink, the first data transmission module 101 is fixed to the low latency mode. In the uplink, the fourth data transmission module 202 in the second retimer 200 only includes the first transmission path 2021, and the second data transmission module 102 in the first retimer 100 includes the first transmission path 1021 and the second transmission path 1022, wherein the first transmission path 2021 / 1021 does not include a data processing module, does not perform data processing operations on received data, and only performs transmission operations on received data, therefore, in the uplink, the third data transmission module 101 is fixed to the low latency mode.

[0091] In the embodiment of the present application, since the two retiming devices are connected by optical connection, that is, by the optical transmission system 300, dynamic equalization is not required. Therefore, in the uplink and downlink, before the data is passed to the optical transmission system 300, it is not necessary to process the data. Therefore, only the first transmission path is set in the first data transmission module of the downlink and the fourth data transmission module of the uplink, and the first transmission path does not contain a data processing module. No data processing operation is performed on the received data, and only the transmission operation is performed on the received data, which is equivalent to canceling the retiming logic in the first data transmission module of the downlink and the fourth data transmission module of the uplink. In this way, in the entire uplink and downlink process, the two retiming devices can be approximately regarded as one retiming device working, and then, the delay required by the retiming device in the present application is half of the double timing device system in the prior art. Since the above two retiming devices are equivalent to one retiming device logic during operation, when performing long-distance information transmission, other retiming devices can be added as needed at other locations of the transmission path. In the embodiment of the present application, in the signal transmission system, the transmission of the reference clock signal is also involved. Preferably, the retiming devices on both sides of the optical link use a common reference clock signal for operation. In an optional embodiment, the transmission of the clock signal may rely on a new optical transmission subsystem in the optical transmission system 300. Optionally, the number of the new optical transmission subsystems may be determined according to the source of the clock system.

[0092] like Figure 6 As shown, the optical transmission system 300 also includes a third optical transmission subsystem. The third optical transmission subsystem includes a third optical transmission module 3031, a third optical path 3032 and a third optical receiving module 3033 along the link transmission direction, wherein the third optical transmission module 3031 is used to obtain a reference clock signal, and convert the reference clock signal from an electrical signal into an optical signal, and transmit it to the third optical path 3032, and the third optical receiving module 3033 is used to convert the reference clock signal from the third optical path 3032 into an electrical signal.

[0093] Preferably, the third optical path 3032 may be a single optical fiber, or may be an optical fiber array consisting of a plurality of optical fibers.

[0094] In an optional embodiment, the clock signal may be a reference clock signal derived from the root device 400, which is used by the retimer device in the link and the endpoint device 500 along the entire path. The root device 400 is electrically connected to the third optical transmission module through the first electrical path in the third link 1003, for transmitting the reference clock signal from the root device 400, and transmitting the reference clock signal to the first transmission module 104 and the second transmission module 106 through the branch of the first electrical path. The third optical receiving module is electrically connected to the endpoint device 500 through the second electrical path in the third link 1003, for transmitting the reference clock signal to the endpoint device 500, and transmitting the reference clock signal to the third transmission module 204 and the fourth transmission module 206 through the branch of the second electrical path.

[0095] Specific reference Figure 6 , the root device 400 sends the reference clock information to the third optical sending module 3031 through the electrical link, during which the reference clock information is sent to the first sending module 104 and the second sending module 106 respectively, so that the first retiming device 200 uses the reference clock signal, the third optical receiving module 3033 receives the reference clock signal sent from the third optical sending module 3031, and sends the received reference clock signal to the endpoint device 500 through the electrical link, during which the reference clock signal is sent to the third sending module 204 and the fourth sending module 206 respectively, so that the second retiming device 200 and the endpoint device 500 use the reference clock signal.

[0096] Optionally, since the reference clock signal is a clock signal from the root device 400, it is transmitted to the retimer device and the endpoint device 500 in the entire link. That is, the two devices and the two retimers use the same reference clock signal, so the mode working under this reference clock signal can be called a common clock mode.

[0097] See also Figure 7 , Figure 7 is a schematic diagram of another signal transmission system according to an exemplary embodiment, wherein the first retiming device 100 and the second retiming device 200 are the retiming devices in the second embodiment. Figure 7 As shown, the reference clock signal is transmitted by relying on a new optical transmission subsystem in the optical transmission system 300. That is, the optical transmission system 300 further includes a third optical transmission subsystem and a fourth optical transmission subsystem.

[0098] Among them, the third optical transmission subsystem includes a third optical sending module 3031, a third optical path 3032 and a third optical receiving module 3033 along the link transmission direction. Optionally, the fourth optical transmission subsystem includes a fourth optical sending module 3041, a fourth optical path 3042 and a fourth optical receiving module 3043 along the link transmission direction.

[0099] Preferably, the fourth optical path 3042 may be a single optical fiber, or may be an optical fiber array consisting of a plurality of optical fibers.

[0100] Optional, such as Figure 7 As shown, the first receiving module 103 is connected to the first sending module 104 and the third optical sending module 3031 respectively, and is used to transmit the first clock signal separated and recovered from the service signal in the first receiving module 103, and the third optical receiving module 3033 is connected to the third sending module 204, and is used to transmit the first clock signal. The fourth receiving module 205 is connected to the fourth sending module 206 and the fourth optical sending module 3041 respectively, and is used to transmit the second clock signal separated and recovered from the service signal in the fourth receiving module 205, and the fourth optical receiving module 3043 is connected to the second sending module 106, and is used to transmit the second clock signal.

[0101] like Figure 7 As described above, the root device 400 and the endpoint device 500 do not use the same clock as the two retiming devices, which is applicable to the independent reference non-spread spectrum mode and the independent reference spread spectrum mode. However, in the same downlink or uplink, although the two retiming devices use the same reference clock signal, Figure 7 The clock signal (first clock signal or second clock signal) in the data stream is recovered from the data stream and optically transmitted. And because the root device 400 and the endpoint device 500 are in different clock domains, the first clock signal can also be called the downlink clock signal corresponding to the downlink, and the second clock signal can also be called the uplink clock signal corresponding to the uplink.

[0102] See also Figure 8 , Figure 8 is a schematic diagram of a signal transmission system according to an exemplary embodiment, wherein the first retiming device 100 and the second retiming device 200 adopt the retiming device in the third embodiment. Figure 8 As shown, the clock signal relies on the original first optical transmission subsystem and the second optical transmission subsystem in the optical transmission system 300 for transmission.

[0103] like Figure 8As shown, in the downlink, the first receiving module 103 is connected to the first sending module 104 for transmitting the first clock signal separated and recovered from the service signal in the first receiving module 103. The third receiving module 203 is connected to the third sending module 204 for transmitting the second clock signal separated and recovered from the service signal in the third receiving module 203.

[0104] Similarly, in the uplink, the fourth receiving module 205 is connected to the fourth sending module 206 for transmitting the third clock signal separated and recovered from the service signal in the fourth receiving module 205. The second receiving module 105 is connected to the second sending module 106 for transmitting the fourth clock signal separated and recovered from the service signal in the second receiving module 105.

[0105] like Figure 8 As shown, the root device 400 and the endpoint device 500 do not use the same clock as the two retiming devices, which is applicable to the independent reference non-spreading mode and the independent reference spread spectrum mode. However, in the same downlink or uplink, although the two retiming devices use the same clock signal, Figure 8 The clock signal in Figure 7 The clock signal shown in the figure, the clock signal in the second half is recovered from the data stream of the optical receiving module.

[0106] The signal transmission system is introduced below in conjunction with the clock mode. In an optional embodiment, when operating in a common clock mode, the first transmission path in the second data transmission module 102 and the third data transmission module 201 operates, and in a non-common clock mode or during link training or equalization, the second transmission path in the second data transmission module 102 and the third data transmission module 201 operates.

[0107] In an embodiment of the present application, before the PCIe link can work normally, the root device 400 and the endpoint device 500 need to perform link training on the PCIe link to determine the optimal link speed and link width. In this process, the link training state machine LTSSM is required to control and manage the training of the data link on the PCIe bus.

[0108] Optionally, the first processing module can perform data processing such as polarity inversion, channel reversal, block alignment, decoding, descrambling, channel delay compensation, etc., the second processing module can perform data processing such as training set modification, and the third processing module can perform encoding and scrambling data processing.

[0109] In some preferred embodiments, the first sending module 104 includes an electrical signal sending module and an optical signal driving module. The input end of the electrical signal sending module is connected to the first transmission path 1011 in the first data transmission module 101, the output end of the electrical signal sending module is connected to the input end of the optical signal driving module, and the output end of the optical signal driving module is connected to the first optical sending module 3011, driving the electrical-optical conversion unit in the optical sending module to load the received electrical signal into the optical wave to form an optical signal.

[0110] In some preferred embodiments, the fourth sending module 206 includes an electrical signal sending module and an optical signal driving module. The input end of the electrical signal sending module is connected to the first transmission path 2011 in the fourth data transmission module 202, the output end of the electrical signal sending module is connected to the input end of the optical signal driving module, and the output end of the optical signal driving module is connected to the second optical sending module 3021, driving the electrical-optical conversion unit in the optical sending module to load the received electrical signal into the optical wave to form an optical signal.

[0111] In some preferred embodiments, the second receiving module 105 includes a transimpedance amplifier and an electrical signal receiving module. The input end of the electrical signal receiving module is connected to the output end of the transimpedance amplifier, and the output end of the electrical signal receiving module is connected to the second phase aligner 108. The input end of the transimpedance amplifier is connected to the second optical receiving module 3023 to receive the electrical signal output by the second optical receiving module 3023.

[0112] In some preferred embodiments, the third receiving module 203 includes a transimpedance amplifier and an electrical signal receiving module. The input end of the electrical signal receiving module is connected to the output end of the transimpedance amplifier, and the output end of the electrical signal receiving module is connected to the third phase aligner 207. The input end of the transimpedance amplifier is connected to the first optical receiving module 3013 to receive the electrical signal output by the first optical receiving module 3013.

[0113] In some preferred embodiments, the uplink also includes a multiplexer, the input end of the multiplexer is respectively connected to the output end of the first transmission path 1021 and the output end of the second transmission path 1022 in the second data transmission module 102, and the output end of the multiplexer is connected to the input end of the second sending module 106.

[0114] In some preferred embodiments, the downlink also includes a multiplexer, the input end of the multiplexer is respectively connected to the output end of the first transmission path 2011 and the output end of the second transmission path 2012 in the third data transmission module 201, and the output end of the multiplexer is connected to the input end of the third sending module 204.

[0115] See also Fig. 9 , Fig. 9is a flow chart of a signal transmission method according to an exemplary embodiment. Fig. 9 As shown, including:

[0116] S901: Acquire a service signal from a root device through a first retiming device;

[0117] S902: Transmitting the service signal to the second retiming device through the optical transmission system;

[0118] S903: In the first signal transmission state, transmit the service signal to the endpoint device through the second path in the second retiming device, or in the second signal transmission state, transmit the service signal to the endpoint device through the first path in the second retiming device.

[0119] The implementation methods involved in the above S901-903 are the implementation methods corresponding to the downlink. The implementation methods corresponding to the uplink and the implementation methods corresponding to the downlink are symmetrical and will not be described in detail here.

[0120] Optionally, the signal transmission system can obtain the service signal from the root device through the first retiming device, and transmit the service signal to the second retiming device through the optical transmission system. Specifically, the service signal is first loaded into the light wave to form an optical signal through the optical transmission module of the optical transmission system, and then the optical signal is transmitted to the optical receiving module through the optical fiber, and the optical signal is converted into an electrical signal through the optical receiving module, so that the second retiming device receives the electrical signal output by the optical receiving module.

[0121] When in the first signal transmission state, that is, in the normal mode, the service signal can be transmitted to the endpoint device through the second path in the second retiming device. Specifically, when the signal transmission system receives the "switch to normal mode" instruction, it can switch to the normal mode and transmit the service signal to the endpoint device through the second path in the second retiming device. The service signal can be data during training and regular data. The second transmission path in the second data transmission module performs operations including polarity inversion, channel reversal, block alignment, decoding, descrambling, channel delay compensation, training set modification, encoding, and scrambling on the received data.

[0122] Optionally, in the second signal transmission state, the service signal is transmitted to the endpoint device through the first path in the second retiming device. Specifically, when the signal transmission system receives the "switch to low latency mode" instruction, it can switch to the low latency mode and provide feedback to the sender of the instruction that the low latency mode is ready.

[0123] Fig.101 is a block diagram of a signal transmission device according to an exemplary embodiment. The device has the function of implementing the data processing method in the above method embodiment, and the function can be implemented by hardware or by hardware executing corresponding software. Fig.10 , the device comprises:

[0124] An acquisition unit 1001 is configured to acquire a service signal from a root device through a first retiming device;

[0125] A first transmission unit 1002, configured to transmit the service signal to a second retiming device via an optical transmission system;

[0126] The second transmission unit 1003 is used to transmit the service signal to the endpoint device through the second path in the second retiming device in the first signal transmission state.

[0127] It should be noted that the device provided in the above embodiment, when implementing its functions, only uses the division of the above functional modules as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the device and method embodiments provided in the above embodiment belong to the same concept, and the specific implementation process is detailed in the method embodiment, which will not be repeated here. .

[0128] It should be noted that the sequence of the embodiments of the present invention described above is for description only and does not represent the advantages and disadvantages of the embodiments. The above describes specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0129] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0130] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A retiming device, characterized in that: include: A first data module corresponding to the first link is used to receive electrical signal data from a device; The first data module includes a first receiving module, a first data transmission module and a first sending module; The first data transmission module includes a first transmission path; A second data module corresponding to the second link is used to send the received electrical signal data to the device; the second data module includes a second receiving module, a second data transmission module and a second sending module; the second data transmission module includes the first transmission path and the second transmission path; The delay of the first transmission path is smaller than the delay of the second transmission path.

2. The retiming device according to claim 1, characterized in that The first data module further includes a first phase aligner; an input end of the first phase aligner is connected to the first receiving module, and an output end of the first phase aligner is connected to a first transmission path in the first data transmission module; The second data module also includes a second phase aligner; the input end of the second phase aligner is connected to the second receiving module, and the output end of the second phase aligner is respectively connected to the first transmission path and the second transmission path in the second data transmission module.

3. The retiming device according to claim 2, characterized in that The first sending module includes an electrical signal sending module and an optical signal driving module; an input end of the electrical signal sending module is connected to a first transmission path in the first data transmission module, and an output end of the electrical signal sending module is connected to an input end of the optical signal driving module; The output end of the optical signal driving module is connected to an optical sending module, and the received electrical signal is loaded into the optical wave to form an optical signal.

4. The retiming device according to claim 2, characterized in that The second receiving module includes a transimpedance amplifier and an electrical signal receiving module; the input end of the electrical signal receiving module is connected to the output end of the transimpedance amplifier; the output end of the electrical signal receiving module is connected to the second phase aligner; The input end of the transimpedance amplifier is connected to a light receiving module to receive the electrical signal output by the light receiving module.

5. The retiming device according to claim 1, characterized in that The retiming device further comprises at least one link training state machine; the at least one link training state machine is used to perform a link training operation; Each link training state machine in the at least one link training state machine is respectively connected to a first transmission path in the first data transmission module and a second transmission path in the second data transmission module.

6. The retiming device according to claim 5, characterized in that The retiming device further comprises a third link connected to the device for transmitting a common reference clock signal, and the device and the retiming device operate using the common clock signal.

7. The retiming device according to claim 6, characterized in that The input end of the third link is connected to the device, and the output end of the third link is connected to an optical transmission module to transmit the common reference clock signal obtained from the device; or; The input end of the third link is connected to an optical receiving module, and the output end of the third link is connected to the device to transmit the received common reference clock signal to the device.

8. The retiming device according to claim 5, characterized in that An asynchronous buffer is arranged between the link training state machine and the first transmission path in the first data transmission module.

9. The retiming device according to claim 8, characterized in that Also includes a third link and a fourth link; The input end of the third link is connected to the first receiving module to receive the first clock signal separated and recovered from the service signal in the first receiving module, and the output end of the third link is connected to an optical sending module to transmit the first clock signal; The input end of the fourth link is connected to an optical receiving module to receive the second clock signal, and the output end of the fourth link is connected to the second sending module to transmit the second clock signal to the second sending module.

10. The retiming device according to claim 8, characterized in that It also includes a third link and a fourth link, wherein: The input end of the third link is connected to the first receiving module to receive the first clock signal separated and recovered from the service signal in the first receiving module, and the output end of the third link is connected to the first sending module to transmit the first clock signal; The input end of the fourth link is connected to the second receiving module to receive the second clock signal separated and recovered from the service signal in the second receiving module, and the output end of the fourth link is connected to the second sending module to transmit the second clock signal.

11. The retiming device according to claim 7, characterized in that The second transmission path in the second data transmission module is used for data transmission during training and regular data transmission; The first transmission path in the second data transmission module is used for data transmission in the low-latency mode after training.

12. The retiming device according to claim 11, characterized in that The second transmission path in the second data transmission module performs operations including polarity inversion, channel reversal, block alignment, decoding, descrambling, channel delay compensation, training set modification, encoding, and scrambling on the received data.

13. The retiming device according to claim 11, characterized in that The first transmission path does not include a processing module and performs a transmission operation on the received data.

14. The retiming device according to claim 1, characterized in that The second data module also includes a multiplexer; The input end of the multiplexer is connected to the output end of the first transmission path and the output end of the second transmission path in the second data transmission module respectively; The output end of the multiplexer is connected to the input end of the second sending module.

15. A signal transmission system, characterized in that: It includes a first retiming device, an optical transmission system and a second retiming device along the transmission direction of the link; The first retiming device includes a first data transmission module corresponding to a downlink and a second data transmission module corresponding to an uplink; the first data transmission module includes a first transmission path; the second data transmission module includes the first transmission path and a second transmission path; The second retiming device includes a third data transmission module corresponding to the downlink and a fourth data transmission module corresponding to the uplink; the third data transmission module includes the first transmission path and the second transmission path; the fourth data transmission module includes the first transmission path; The delay of the first transmission path is smaller than the delay of the second transmission path.

16. The signal transmission system according to claim 15, characterized in that: The first retiming device comprises a first receiving module, a first phase aligner, the first data transmission module and a first sending module corresponding to the downlink along the link transmission direction; and a second receiving module, a second phase aligner, the second data transmission module and a second sending module corresponding to the uplink along the link transmission direction; The second retiming device includes a third receiving module, a third phase aligner, a third data transmission module and a third sending module corresponding to the downlink along the link transmission direction, and a fourth receiving module, a fourth phase aligner, a fourth data transmission module and a fourth sending module corresponding to the uplink along the link transmission direction.

17. The signal transmission system according to claim 15, characterized in that: The optical transmission system comprises a first optical transmission subsystem corresponding to the downlink; the first optical transmission subsystem comprises a first optical transmitting module, a first optical path and a first optical receiving module along the link transmission direction; The input end of the first optical transmission module is connected to the first retiming device, and is used to convert the electrical signal from the first retiming device into an optical signal; The input end of the first optical receiving module is connected to the first optical path, and is used to convert the optical signal from the first optical path into an electrical signal; The optical transmission system includes a second optical transmission subsystem corresponding to the uplink; the second optical transmission subsystem includes a second optical sending module, a second optical path and a second optical receiving module along the link transmission direction; The input end of the second optical transmission module is connected to the second retiming device, and is used to convert the electrical signal from the second retiming device into an optical signal; The input end of the second optical receiving module is connected to the second optical path, and is used to convert the optical signal from the second optical path into an electrical signal.

18. The signal transmission system according to any one of claims 15 to 17, characterized in that: The signal transmission system also includes a root device and an endpoint device; The first retiming device is located between the root device and the optical transmission system; the second retiming device is located between the optical transmission system and the endpoint device.

19. The signal transmission system according to claim 18, characterized in that: The optical transmission system further includes a third optical transmission subsystem; The third optical transmission subsystem includes a third optical sending module, a third optical path and a third optical receiving module along the link transmission direction; The third optical sending module is used to obtain a reference clock signal, convert the reference clock signal from an electrical signal into an optical signal, and transmit the optical signal to the third optical path; The third optical receiving module is used to convert the reference clock signal from the third optical path from an optical signal to an electrical signal.

20. The signal transmission system according to claim 19, characterized in that: The first retiming device comprises a first sending module corresponding to the downlink and a second sending module corresponding to the uplink; The second retiming device comprises a third sending module corresponding to the downlink and a fourth sending module corresponding to the uplink; The root device is electrically connected to the third optical sending module through a first electrical path, for transmitting a reference clock signal from the root device, and transmitting the reference clock signal to the first sending module and the second sending module through a branch of the first electrical path; The third optical receiving module is electrically connected to the endpoint device via a second electrical path, and is used to transmit the reference clock signal to the endpoint device, and transmit the reference clock signal to the third sending module and the fourth sending module via a branch of the second electrical path.

21. The signal transmission system according to claim 19, characterized in that: The optical transmission system further comprises a fourth optical transmission subsystem; the fourth optical transmission subsystem comprises a fourth optical transmission module, a fourth optical path and a fourth optical receiving module along the link transmission direction; The first retiming device comprises a first receiving module and a first sending module corresponding to the downlink and a second sending module corresponding to the uplink; the second retiming device comprises a fourth receiving module and a fourth sending module of the uplink and a third sending module corresponding to the downlink; The first receiving module is connected to the first sending module and the third optical sending module respectively, and is used to transmit the first clock signal separated and recovered from the service signal in the first receiving module; the third optical receiving module is connected to the third sending module, and is used to transmit the first clock signal; The fourth receiving module is connected to the fourth sending module and the fourth optical sending module respectively, and is used to transmit the second clock signal separated and recovered from the service signal in the fourth receiving module; the fourth optical receiving module is connected to the second sending module, and is used to transmit the second clock signal.

22. The signal transmission system according to claim 17, characterized in that: The first receiving module is connected to the first sending module and is used to transmit a first clock signal separated and recovered from a service signal in the first receiving module; The third receiving module is connected to the third sending module and is used to transmit the second clock signal separated and recovered from the service signal in the third receiving module.

23. The signal transmission system according to claim 17, characterized in that: The fourth receiving module is connected to the fourth sending module and is used to transmit the third clock signal separated and recovered from the service signal in the fourth receiving module; The second receiving module is connected to the second sending module and is used to transmit the fourth clock signal separated and recovered from the service signal in the second receiving module.

24. A signal transmission method, characterized in that: A signal transmission system as claimed in any one of claims 15 to 23, comprising: Acquiring a service signal from a root device through the first retiming device; transmitting the service signal to the second retiming device through the optical transmission system; In the first signal transmission state, the service signal is transmitted to the endpoint device through the second path in the second retiming device.

25. The signal transmission method according to claim 24, characterized in that: After transmitting the service signal to the second retiming device through the optical transmission system, the method further includes: In a second signal transmission state, the service signal is transmitted to the endpoint device through a first path in the second retiming device.

26. A signal transmission device, characterized in that: A signal transmission system as claimed in any one of claims 15 to 23, comprising: an acquisition unit, configured to acquire a service signal from a root device through the first retiming device; a first transmission unit, configured to transmit the service signal to the second retiming device through the optical transmission system; The second transmission unit is used to transmit the service signal to the endpoint device through the second path in the second retiming device in the first signal transmission state.

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