Optical line terminal, optical network unit, method, device and computer readable medium

Abstract

The embodiment of the invention relates to an optical line terminal, an optical network unit, a related method, a device and a medium. In one aspect, an optical line terminal allocates at least one subcarrier and at least one time slot to an optical network unit from a plurality of subcarriers in a frequency domain and a plurality of time slots in a time domain based on channel condition information and traffic demand information of the optical network unit. And the optical line terminal sends resource allocation information to the optical network unit, wherein the resource allocation information indicates at least one subcarrier and at least one time slot allocated to the optical network unit. The optical line terminal performs communication with the optical network unit based on the at least one subcarrier and the at least one time slot. According to the embodiment of the invention, bandwidth resources are allocated in two dimensions of frequency and time according to corresponding flow requirements and channel conditions of different optical network units, so that an optical communication system can utilize available bandwidth resources of optical fiber infrastructures to the maximum extent.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of communication technology, and more particularly to an optical line terminal, an optical network unit, related methods, related devices, and a computer-readable medium. Background Art

[0002] Driven by emerging fixed and mobile services such as 5G / 6G communication systems, virtual reality / augmented reality (VR / AR) and cloud computing, the next generation optical network has put forward higher requirements for performance such as huge bandwidth, high flexibility, high reliability and low latency. In order to adapt to this change, Digital Sub-Carrier Modulation (DSCM) technology has been proposed. DSCM technology subdivides the transmission spectrum into multiple digital sub-carriers (SC). Compared with single-carrier signals, DSCM signals have the advantages of high flexibility, high tolerance to linear and nonlinear damage, and low enhanced equalization phase noise (EEPN).

[0003] However, for optical communication systems, especially those using DSCM technology, there are still some open problems that need to be solved. Summary of the invention

[0004] In general, the example embodiments of the present disclosure relate to a technical solution for allocating bandwidth resources from an optical line terminal to an optical network unit in both frequency and time dimensions, so as to optimize the performance of a point-to-multipoint (PtMP) coherent digital subcarrier modulation (DSCM) system.

[0005] In a first aspect, an optical line terminal is provided. The optical line terminal includes: at least one processor and at least one memory, wherein the at least one memory stores instructions, and when the instructions are executed by the at least one processor, the optical line terminal at least: allocates at least one subcarrier and at least one time slot to the optical network unit from multiple subcarriers in the frequency domain and multiple time slots in the time domain based on the channel condition information and service demand information of the optical network unit; sends resource allocation information to the optical network unit, wherein the resource allocation information indicates at least one subcarrier and at least one time slot allocated to the optical network unit; and performs communication with the optical network unit based on the at least one subcarrier and at least one time slot.

[0006] In a second aspect, an optical network unit is provided. The optical network unit includes: at least one processor; and at least one memory, wherein the at least one memory stores instructions, and when the instructions are executed by the at least one processor, the optical network unit at least: receives resource allocation information from an optical line terminal, the resource allocation information indicates at least one subcarrier and at least one time slot allocated to the optical network unit from multiple subcarriers in the frequency domain and multiple time slots in the time domain; and performs communication with the optical line terminal based on the at least one subcarrier and the at least one time slot.

[0007] In a third aspect, a method is provided. The method includes: at an optical line terminal, based on channel condition information and service demand information of the optical network unit, allocating at least one subcarrier and at least one time slot to the optical network unit from multiple subcarriers in the frequency domain and multiple time slots in the time domain; sending resource allocation information to the optical network unit, the resource allocation information indicating at least one subcarrier and at least one time slot allocated to the optical network unit; and performing communication with the optical network unit based on the at least one subcarrier and at least one time slot.

[0008] In a fourth aspect, a method is provided. The method includes: receiving resource allocation information from an optical line terminal at an optical network unit, the resource allocation information indicating at least one subcarrier and at least one time slot allocated to the optical network unit from a plurality of subcarriers in a frequency domain and a plurality of time slots in a time domain; and performing communication with the optical line terminal based on the at least one subcarrier and the at least one time slot.

[0009] In a fifth aspect, a device is provided. The device includes: a component for allocating at least one subcarrier and at least one time slot to an optical network unit from multiple subcarriers in the frequency domain and multiple time slots in the time domain based on channel condition information and service demand information of the optical network unit at an optical line terminal; a component for sending resource allocation information to the optical network unit, wherein the resource allocation information indicates at least one subcarrier and at least one time slot allocated to the optical network unit; and a component for performing communication with the optical network unit based on the at least one subcarrier and at least one time slot.

[0010] In a sixth aspect, a device is provided. The device includes: a component for receiving resource allocation information from an optical line terminal at an optical network unit, wherein the resource allocation information indicates at least one subcarrier and at least one time slot allocated to the optical network unit from multiple subcarriers in the frequency domain and multiple time slots in the time domain; and a component for performing communication with the optical line terminal based on the at least one subcarrier and the at least one time slot.

[0011] In a seventh aspect, a non-transitory computer-readable medium is provided, comprising program instructions for causing an apparatus to execute at least any one of the methods of the third to fourth aspects.

[0012] In an eighth aspect, a computer program is provided. When executed by a device, the computer program causes the device to perform at least any one of the methods of the third aspect to the fourth aspect.

[0013] In a ninth aspect, an optical line terminal is provided. The optical line terminal includes: an allocation circuit configured to allocate at least one subcarrier and at least one time slot to the optical network unit from multiple subcarriers in the frequency domain and multiple time slots in the time domain based on the channel condition information and service demand information of the optical network unit; a sending circuit configured to send resource allocation information to the optical network unit, the resource allocation information indicating at least one subcarrier and at least one time slot allocated to the optical network unit; and an execution circuit configured to execute communication with the optical network unit based on the at least one subcarrier and at least one time slot.

[0014] In a tenth aspect, an optical network unit is provided. The optical network unit includes: a receiving circuit configured to receive resource allocation information from an optical line terminal, the resource allocation information indicating at least one subcarrier and at least one time slot allocated to the optical network unit from multiple subcarriers in the frequency domain and multiple time slots in the time domain; and an execution circuit configured to perform communication with the optical line terminal based on the at least one subcarrier and the at least one time slot.

[0015] It should be understood that the contents described in the Summary of the Invention are not intended to limit the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without exceeding the scope of protection required by the present application.

[0017] Figure 1A A block diagram of an example communication system is shown in which embodiments of the present disclosure may be implemented.

[0018] Figure 1B The spectrum comparison of DSCM signal and single carrier signal is shown.

[0019] Figure 1C The designed transmission capacity for DSCM subcarrier signals is shown.

[0020] Figure 1D The channel response and the corresponding actual subcarrier capacity are shown.

[0021] Figure 1E The traffic demand and the corresponding actual subcarrier capacity are shown.

[0022] Figure 2 A schematic diagram of the interaction process between an optical line terminal and an optical network unit according to an embodiment of the present disclosure is shown.

[0023] Figure 3A An example scheme of allocating bandwidth resources to an optical network unit in two dimensions of frequency and time by an optical line terminal according to an embodiment of the present disclosure is shown.

[0024] Figure 3B An example scheme of allocating bandwidth resources to optical network resources in two dimensions of frequency and time by an optical line terminal according to an embodiment of the present disclosure is shown.

[0025] Figure 4A It is shown that the optical network unit according to the embodiment of the present disclosure obtains the channel response through one-time DSP processing.

[0026] Figure 4B It is shown that the optical network unit of the embodiment of the present disclosure obtains the channel response of subcarriers at different positions group by group through coherent detection and DSP processing.

[0027] Figure 5A A block diagram of an example communication system in accordance with an embodiment of the present disclosure is shown.

[0028] Figure 5B A schematic diagram of the interaction process between an optical line terminal and an optical network unit according to an embodiment of the present disclosure is shown.

[0029] Figure 6 A block diagram of an example communication system in accordance with an embodiment of the present disclosure is shown.

[0030] Figure 7 The graph shows the variation curve of the calculated bit error rate (BER) versus spectral efficiency (SE) of different optical network units according to the embodiments of the present disclosure.

[0031] Figure 8 An example process of reallocating subcarriers when the service demand of an optical network unit changes according to an embodiment of the present disclosure is shown.

[0032] Fig. 9 A schematic diagram of a process executed by an optical line terminal according to some embodiments of the present disclosure is shown.

[0033] Fig.10 A schematic diagram of a process executed by an optical network unit according to some embodiments of the present disclosure is shown.

[0034] Fig.11 A simplified block diagram of an electronic device suitable for implementing embodiments of the present disclosure is shown.

[0035] Fig.12 A schematic diagram of a computer-readable medium suitable for implementing an embodiment of the present disclosure is shown.

[0036] Throughout the drawings, the same or similar reference numerals refer to the same or similar elements. DETAILED DESCRIPTION

[0037] The principles and spirit of the present disclosure will be described below with reference to several exemplary embodiments shown in the accompanying drawings. It should be understood that these specific embodiments are described only to enable those skilled in the art to better understand and implement the present disclosure, and are not intended to limit the scope of the present disclosure in any way.

[0038] As used herein, the term "including" and similar terms should be understood as open inclusion, i.e., "including but not limited to". The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0039] As used herein, the term "determine" covers a variety of actions. For example, "determine" may include operation, calculation, processing, export, investigation, search (e.g., search in a table, a database or another data structure), ascertain, etc. In addition, "determine" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. In addition, "determine" may include parsing, selecting, selecting, establishing, etc. As used herein, "at least one of the following: " and "at least one of " and similar expressions, wherein a list of two or more elements is connected by "and" or "or", means at least any one of these elements, or at least any two or more of these elements, or at least all of them.

[0040] As used herein, the term "circuitry" refers to one or more of: (a) hardware circuit implementations only (such as implementations of analog and / or digital circuits only); and (b) combinations of hardware circuits and software, such as (where applicable): (i) a combination of analog and / or digital hardware circuits and software / firmware, and (ii) any portion of a hardware processor with software (including a digital signal processor, software, and memory that work together to enable an apparatus such as a radio frequency device or other computing device to perform various functions); and (c) hardware circuits and / or processors, such as a microprocessor or portion of a microprocessor, that require software (e.g., firmware) for operation, but may be without software when software is not required for operation.

[0041] The definition of circuitry applies to all uses of this term in this application, including in any claims. As another example, the term "circuitry" as used herein also covers an implementation of a hardware circuit or processor (or multiple processors), or a portion of a hardware circuit or processor, or accompanying software or firmware. For example, the term "circuitry" also covers a baseband integrated circuit or a processor integrated circuit or similar integrated circuit in other computing devices if applicable to the particular claim notation.

[0042] Digital Sub-Carrier Multiplexing (DSCM) is a modulation technology in the field of optical fiber communication. It multiplexes multiple low-rate optical signals into a high-speed signal in the frequency domain to achieve higher bandwidth utilization in optical fiber transmission. DSCM technology uses digital signal processing technology to subdivide the transmission spectrum into multiple digital sub-carriers (SC), modulate different signals on different sub-carrier frequencies for transmission, and the receiving end separates these optical signals through demodulation.

[0043] On the other hand, in optical transmission systems, reducing the cost per bit (CpB) is a goal that operators are constantly pursuing. In this strategy, improving the spectral efficiency (SE) of the already deployed fiber channels is an important method to postpone the deployment of expensive new optical fibers. In recent years, some novel technologies have been proposed and demonstrated, some of which have been rapidly adopted by the industry. For example, the 100G Flexible Passive Optical Network (FLCS-PON), in which appropriate modulation and coding parameters are assigned to each user group, thus avoiding the network-wide speed limit inherent in all previous PONs. Overall, the coherent DSCM scheme is a potential solution for achieving flexible high-SE optical networks because it can dynamically and finely divide the spectrum into multiple sub-bands and efficiently aggregate / decompose them while having high time synchronization tolerance.

[0044] The embodiments of the present disclosure propose a technical solution in which an optical line terminal determines and sends subcarrier signal resources and time slot resource information, and the optical line terminal and the optical network unit communicate based on the subcarrier signal resources and time slot resource information. The solution adopts a two-dimensional frequency and time allocation scheme to maximize the throughput of optical communication systems, such as point-to-multipoint (PtMP) coherent DSCM systems.

[0045] Figure 1A 1 shows a block diagram of an example communication system in which embodiments of the present disclosure may be implemented. Figure 1AAs shown, the communication system 100 includes an optical line terminal 110 and at least one optical network unit 120, such as optical network units 120-1, 120-2...120-8. The optical line terminal 110 includes, for example, an optical line terminal (OLT) in a passive optical network, a central processing unit (CPU) in a wireless backhaul network, etc., which includes components such as a digital subcarrier input interface, a coherent demodulator, a digital signal processor, a DSCM signal output interface, a controller, a memory, etc., to achieve reception and demodulation of DSCM signals.

[0046] The optical network unit 110 includes an optical network unit (ONU) in a passive optical network (PON), an access point (AP) in a wireless backhaul network, and a device for converting a wired network into a wireless network to connect wireless terminal devices such as computers, mobile phones, and tablets to the network, such as a wireless router, a wireless access point, and a wireless gateway. At least one optical network unit 120 sends a digital subcarrier signal modulating effective information to the optical line terminal 110, which synthesizes a DSCM signal. Compared with the solution of a point-to-point (PtP) coherent DSCM system, the PtMP structure has the advantages of low cost, low energy consumption, easy aggregation / deaggregation, and high statistical multiplexing gain, and has the potential for wide application in optical access networks or optical fronthaul networks that need to connect a large number of terminals.

[0047] Figure 1B Figure 2 shows the frequency domain waveform comparison between DSCM signal and single carrier signal. Figure 1B As shown, compared with single-carrier signals, DSCM signals have many advantages. The coherent DSCM system can flexibly allocate different modulation formats, subcarrier numbers and bandwidths, signal powers, etc. to different access devices, thereby being able to solve the problem of flexible slicing of transmission signals. Figure 1B The digital carrier signal (single carrier signal) has a baud rate of 1*50GBaud / s, while the DSCM digital subcarrier signal has a baud rate of 8*6.25GBaud / s. Compared with the single carrier signal, the DSCM digital subcarrier signal has the advantages of high bandwidth utilization, strong multiple access capability, high tolerance to linear and nonlinear damage, and low enhanced equalization phase noise (EEPN). However, it also has the problems of high complexity and low peak power to average power ratio (PAPR).

[0048] Specifically, assume that in a traditional optical network system, data from eight optical network units are aggregated in an optical line terminal using coherent DSCM technology. DSCM technology flexibly aggregates multiple low-speed signals from different endpoints at different locations into high-speed DSCM signals. For example, the optical line terminal sends DSCM signals to three different optical network units respectively. The channel conditions between the three optical network units and the optical line terminal, such as different communication distances, and the traffic required by each optical network unit are also different, which will cause a waste of DSCM resources.

[0049] In more detail, there may be two types of mismatches. First, the subcarrier capacity required by each optical network unit (end user) does not match the actual allocated subcarrier capacity. Figure 1C As shown in FIG. 1 , each subcarrier is designed to transmit a 25 Gb / s signal, and initially 8 subcarriers transmit a total of 200 Gb / s signals. In actual operation, the actual capacity of each single subcarrier is actually determined by the channel response of a single end user. Figure 1D Three hypothetical channel responses and actual subcarrier capacities are plotted (where the numbers represent the actual maximum capacity transmitted to a specific optical network unit). In general, the actual maximum achievable transmission capacity is not a fixed 25Gb / s, but varies, due to differences in fiber length, power ratio, equipment frequency response, and other factors.

[0050] The second mismatch is the mismatch between the subcarrier capacity and traffic demand of each end user. The traffic demand of the end user varies over time, and in most cases, the allocated subcarriers cannot be fully utilized. For example, the required capacity of the ONU is 12Gb / s, while the maximum transmission capacity of the SC actually used is 35Gb / s. Obviously, this leads to inefficient utilization of the SC bandwidth. Figure 1E As shown in Figure 1, incorrect subcarrier allocation underestimates the capacity of the DSCM system and causes huge bandwidth waste due to multiple mismatches of subcarrier capacity.

[0051] In some embodiments, Figure 1A The optical line terminal 110 in the optical network is called an optical line terminal (OLT), a processing unit (CPU), and a relay point according to its function; the optical network 120 can be called an optical network unit (ONU), an access point (AP), and an endpoint. According to the connection relationship and topological structure between the optical network unit 110 and the optical line terminal 120, in some embodiments, the optical network unit 110 can also be called a spoke device, and the optical line terminal 120 can also be called a hub device. The optical network unit and the optical line terminal upload and download optical signals via optical transmission media such as optical fiber. Figure 1AThe connection structure between the optical network unit 110 and the optical line terminal 120 is only schematically shown, and the number of the optical network unit 110 and the optical line terminal 120 in the embodiment of the present disclosure is not limited to the above example.

[0052] Figure 2 A schematic diagram of the interaction process between an optical line terminal and an optical network unit according to some embodiments of the present disclosure is shown. Figure 1A , taking the optical line terminal 110 as the optical line terminal in process 200 and the optical network unit 120 as the optical network unit in process 200 as an example. Figure 2 In the example process 200, first, the optical line terminal 110 allocates (210) at least one subcarrier and at least one time slot to the optical network unit 110 from multiple subcarriers in the frequency domain and multiple time slots in the time domain based on the channel condition information and service demand information of the optical network unit 120. The channel condition information includes, for example, the optical fiber length between the optical line terminal 110 and the optical network unit 120, the power ratio (splitting ratio), the device frequency response of the optical network unit, etc., and the service demand information includes, for example, the flow demand of the optical network unit 120, etc. In order to make full use of the subcarrier resources in the frequency domain and the time slot resources in the time domain, the optical line terminal 110 allocates subcarrier resources and time slot resources to each optical network unit 120 based on the channel condition information and service demand information of each optical network unit 120, so as to integrate the bandwidth utilization in the two dimensions of frequency and time.

[0053] Then, the optical line terminal 110 sends (220) resource allocation information 205 to the optical network unit 120, and the resource allocation information 205 indicates at least one subcarrier and at least one time slot allocated to the optical network unit 120. In some embodiments, the optical line terminal 110 sends a full-bandwidth DSCM signal to the optical network unit 120, and includes information indicating at least one subcarrier in the resource allocation information 205; in other embodiments, the resource allocation information 205 indicates the position, bandwidth, modulation format, signal power and other information of at least one subcarrier on the spectrum, and the optical network unit 120 prepares at least one subcarrier signal for use; in other embodiments, the resource allocation information 205 may include at least one subcarrier, for example, the optical line terminal 110 sends at least one subcarrier for use to the optical network unit 120. The optical network unit 120 receives (240) the resource allocation information 205 from the optical line terminal 110, obtains at least one subcarrier by adjusting the local oscillator frequency of the receiving device based on the resource allocation information 205, or prepares at least one subcarrier signal for use based on the resource allocation information 205. Those skilled in the art will readily understand that the resource allocation information 205 may also include other information indicating how the optical network unit 120 utilizes the optical channel and frequency domain and time domain resources. These implementations are all within the protection scope of the present invention.

[0054] Then, the optical line terminal 110 performs (230) communication with the optical network unit 120 based on at least one subcarrier and at least one time slot. The optical network unit 120 performs (250) communication with the optical line terminal 110 based on at least one subcarrier and at least one time slot. In some embodiments, the optical network unit 120 modulates the valid information to be transmitted onto at least one subcarrier to generate a modulated optical signal, and sends the modulated optical signal to the optical line terminal 110 in a time division multiplexing manner based on at least one time slot indicated in the resource allocation information 205. The optical line terminal 110 receives the modulated optical signal sent by the optical network unit 120 based on at least one time slot, and combines the modulated optical signal with the modulated optical signals sent by other optical network units based on at least one subcarrier specified to the optical network unit 120 in the resource allocation information 205 to generate a DSCM signal for communication.

[0055] In the interaction scheme between the optical line terminal and the optical network unit provided in the embodiments of the present disclosure, bandwidth resources can be allocated in two dimensions, frequency and time, according to the corresponding traffic requirements and channel conditions of different optical network units. By adopting the embodiments provided by the present disclosure, optical communication systems, such as coherent DSCM systems, can maximize the use of available bandwidth resources of optical fiber infrastructure, which is a promising method to support the widespread application of coherent DSCM systems in future ultra-high-speed optical access networks, such as PON, 5G / 6G xhaul and data centers.

[0056] In some embodiments of the present disclosure, the resource allocation information 205 sent by the optical line terminal 110 further indicates a probability shaping quadrature amplitude modulation (PS-QAM) parameter corresponding to a subcarrier in the at least one subcarrier 205. As used herein, probability shaping (PS) may refer to a technique for improving spectrum efficiency, which may adapt the probability distribution of symbols in a constellation to channel conditions, thereby improving the channel spectrum efficiency SE.

[0057] The optical line terminal 110 allocates at least one subcarrier and at least one time slot to the optical network unit 120 based on the channel information and traffic demand to make full use of the optical channel; the optical line terminal 110 also allocates appropriate probability shaping quadrature amplitude modulation (PS-QAM) parameters to each subcarrier, and the optical network unit 120 modulates the subcarrier using the probability shaping quadrature amplitude modulation (PS-QAM) format and sends the modulated optical signal to the optical line terminal 110 to maximize the spectrum efficiency (SE) of the optical fiber channel. Optionally, the bandwidth resource allocation scheme and the probability shaping quadrature amplitude modulation (PS-QAM) parameters should be reasonably designed by the operator.

[0058] In some embodiments, the optical line terminal 110 receives a modulated signal generated by modulating the subcarrier based on the PS-QAM parameters from the optical network unit 120 based on one or more time slots associated with the subcarrier. Correspondingly, the optical network unit 120 modulates the subcarrier based on the PS-QAM parameters, and after generating the modulated signal, sends the modulated signal to the optical line terminal 110 based on one or more time slots associated with the subcarrier.

[0059] In some embodiments of the present disclosure, the frequency domain position of at least one subcarrier allocated to the optical network unit 120 in at least one time slot is fixed. Figure 3A As shown in (left side), the optical line terminal 110 allocates bandwidth resources to the optical network unit 120 based on the business needs of the optical network unit 120 and the channel conditions between the two. The allocable bandwidth resources are shown in the two-dimensional plane composed of the frequency axis and the time axis in the left figure, where the solid box represents that the bandwidth of the corresponding spectrum position and time slot has been allocated or used, and the hollow box represents that the bandwidth of the corresponding spectrum position and time slot has not been allocated, and the number in the box represents the spectrum efficiency after PS-QAM modulation.

[0060] like Figure 3A As shown in (right side), the optical line terminal 110 sends data to the optical network unit 120 via the optical fiber channel, such as resource allocation information. The allocation scheme is shown in the two-dimensional plane composed of the frequency axis and the time axis in the figure on the right, where the solid boxes without numbers represent that the bandwidth of the corresponding spectrum position and time slot has been allocated or used; the hollow boxes represent that the bandwidth of the corresponding spectrum position and time slot has not been allocated, and the numbers in the boxes represent the spectrum efficiency after PS-QAM modulation; the solid boxes with numbers represent the bandwidth resources of the corresponding spectrum position and time slot allocated to the optical network unit 120, and the numbers in the boxes represent the spectrum efficiency after PS-QAM modulation. Figure 3A In the figure, the six bandwidth resources in the two-dimensional plane composed of the frequency axis and the time axis allocated to the optical network unit 120 occupy two consecutive positions on the spectrum. The optical network unit 120 can obtain the bandwidth resource through the local oscillator (LO) frequency of the receiving device Rx.

[0061] In some other embodiments of the present disclosure, at least one subcarrier allocated to the optical network unit 120 has a higher spectral efficiency than other subcarriers for the optical network unit 120 in at least one time slot. Figure 3BAs shown in (left side), the optical line terminal 110 allocates bandwidth resources to the optical network unit 120 based on the business needs of the optical network unit 120 and the channel conditions between the two. The allocable bandwidth resources are shown in the two-dimensional plane composed of the frequency axis and the time axis in the left figure, where the solid box represents that the bandwidth of the corresponding spectrum position and time slot has been allocated or used, and the hollow box represents that the bandwidth of the corresponding spectrum position and time slot has not been allocated, and the number in the box represents the spectrum efficiency after PS-QAM modulation.

[0062] like Figure 3B As shown in (right side), the optical line terminal 110 sends data to the optical network unit 120 via the optical fiber channel, such as resource allocation information. The allocation scheme is shown in the two-dimensional plane composed of the frequency axis and the time axis in the figure on the right, where the solid boxes without numbers represent that the bandwidth of the corresponding spectrum position and time slot has been allocated or used; the hollow boxes represent that the bandwidth of the corresponding spectrum position and time slot has not been allocated, and the numbers in the boxes represent the spectrum efficiency after PS-QAM modulation; the solid boxes with numbers represent the bandwidth resources of the corresponding spectrum position and time slot allocated to the optical network unit 120, and the numbers in the boxes represent the spectrum efficiency after PS-QAM modulation. Figure 3B In the embodiment, the six bandwidth resources in the two-dimensional plane composed of the frequency axis and the time axis allocated to the optical network unit 120 have the highest spectrum efficiency (SE) among the bandwidths available for allocation in the two-dimensional plane of frequency and time.

[0063] Combination Figure 3A , Figure 3B , it can be seen that Figure 3A In the allocation method, two unused subcarriers at fixed spectrum positions are allocated to new users, which has a higher spectrum efficiency (SE). The optical network unit 120 can obtain the allocated bandwidth resources through the local oscillator (LO) frequency of the receiving device (Rx), thereby improving the receiving efficiency. Figure 3B The allocation method is based on the perspective of maximizing spectrum efficiency, that is, the new user uses the two unused subcarriers with the highest spectrum efficiency (SE) in all time slots, which requires the optical network unit 120 to reasonably adjust the local oscillator (LO) frequency of the receiving device (Rx) to obtain the allocated bandwidth resources. Figure 3B The allocation scheme can maximize the channel SE, but the operator should consider the speed of adjusting the LO center frequency at Rx and the time spent on reallocating subcarriers and adjusting the LO frequency.

[0064] In some embodiments of the present disclosure, the optical line terminal 110 measures the channel condition of the optical network unit 120 based on determining that the optical network unit 120 is connected to the optical line terminal 110 for the first time (optionally, the optical network unit 120 is a new user accessing for the first time) to obtain channel condition information of the optical network unit 120, and records the channel condition information in a lookup table.

[0065] In some embodiments, the optical line terminal 110 sends a full-bandwidth digital subcarrier modulation (DSCM) signal including at least one subcarrier to the optical network unit 120, and then the optical line terminal 110 receives channel condition information from the optical network unit 120, wherein the channel condition information includes the frequency response or signal-to-noise ratio of multiple subcarriers of the full-bandwidth DSCM signal at the optical network unit 120. It is easy for those skilled in the art to understand that the channel condition information may also include other indicators or information indicating the channel condition between the optical line terminal 110 and the optical network unit 120, and this information can be collected and fed back to the optical line terminal 110 by the optical network unit 120, and this information belongs to the protection scope of the present invention. The optical line terminal 110 measures the channel condition by sending a full-bandwidth DSCM signal to the optical network unit 120 that is accessed for the first time. After the DSCM signal is received and digitally signal processed (DSP), the optical network unit 120 feeds back the channel information to the optical line terminal 110.

[0066] In some embodiments, the optical network unit 120 obtains the full bandwidth channel response of the full bandwidth DSCM signal at one time. Figure 4A As shown, the transmit-receive device (TRx) bandwidths of the optical line terminal 110 and the optical network unit 120 are the same, and the optical network unit 120 can obtain the channel response through a one-time DSP processing.

[0067] In some other embodiments, the optical network unit 120 obtains the channel response of the subcarrier signal of the full-bandwidth DSCM signal through multiple coherent detections by adjusting the local oscillator frequency of the receiving device. Figure 4B As shown, the capacity of the transmitting-receiving device (TRx) of the optical network unit 120 is smaller than that of the transmitting-receiving device (TRx) of the optical line terminal 110. By adjusting the center frequency of the local oscillator (LO) of the receiving device (Rx) of the optical network unit 120, the channel responses of different subcarriers are obtained group by group through coherent detection and DSP processing in the optical network unit 120.

[0068] In some other embodiments of the present disclosure, the optical line terminal 110 obtains the channel condition information of the optical network unit 120 from a lookup table for recording channel condition information of multiple optical network units 120 based on determining that the optical network unit 120 is not connected to the optical line terminal 110 for the first time.

[0069] In some embodiments of the present disclosure, the channel condition information obtained by measurement is recorded / updated in a lookup table (LUT) of the optical line terminal 110. The lookup table LUT is updated when a new user accesses the optical line terminal 110 for the first time. In addition, in some embodiments, the optical line terminal 110 periodically remeasures the channel condition information of the optical network unit 120 at preset time intervals and updates the lookup table. Optionally, in the case of aging of the equipment, it should be updated regularly at pre-designed time intervals. In some other embodiments, the optical line terminal 110 updates the lookup table based on determining that one or more subcarriers of the full-bandwidth DSCM signal have bit errors for one or more optical network units in multiple optical network units. That is, when errors occur in certain subcarriers for certain users (such as bit error rates exceeding a threshold), the corresponding channel condition measurements should be re-performed.

[0070] In some embodiments of the present disclosure, before receiving the resource allocation information 205 , the optical network unit 120 uses a control channel between the optical network unit 120 and the optical line terminal 110 to complete a registration process.

[0071] In some embodiments, the control channel may include at least one digital subcarrier among a plurality of digital subcarriers in a communication spectrum between the optical network unit 120 and the optical line terminal 110 , or include at least one wavelength in the communication spectrum.

[0072] In some embodiments of the present disclosure, before sending the resource allocation information 205 , the optical line terminal 110 receives service demand information from the optical network unit 120 .

[0073] like Figure 5A As shown, the optical line terminal 501 allocates resources in frequency and time dimensions to multiple different optical network units 502 based on channel conditions (such as the optical fiber length shown in the figure) and business requirements (such as the traffic requirements shown in the figure). The bandwidth allocation method is shown in the DSCM signal distribution diagram composed of the time coordinate axis and the frequency coordinate axis in the figure.

[0074] Combine the following Figure 5B Description Figure 5A The interaction process between the optical line terminal 110 and the optical network unit 120 in FIG.

[0075] like Figure 5B As shown, the new user end 502 accesses the optical line terminal 501 through the control channel and completes registration (510). The control channel can be a dedicated wavelength or a dedicated subcarrier (SC). This step includes some normal operations, such as sequence number reporting and ranging.

[0076] The optical line terminal 501 measures (520) the channel condition by sending a full-bandwidth DSCM signal to the new user end 502. After the DSCM signal is received and digitally signal processed (DSP), the new user end 502 feeds back the channel information to the optical line terminal 501. The channel information may include the frequency response and signal-to-noise ratio (SNR) of the subcarrier.

[0077] The measured channel condition information is recorded / updated (530) in a lookup table (LUT) in the optical line terminal 501. This LUT is updated when a new user 501 first accesses the optical line terminal 502. In addition, in the case of equipment aging, it should be regularly updated at pre-designed time intervals. Of course, when some subcarriers (SC) have errors for some users, the corresponding channel condition measurement should be re-performed.

[0078] The new user terminal 502 sends (540) flow demand information to the optical line terminal 501 according to the service demand.

[0079] The optical line terminal 501 allocates (550) bandwidth resources such as subcarriers (SC) and time slots to the new user end 502 according to the LUT and traffic demand information to fully utilize the optical channel. Here, an appropriate probability shaping quadrature amplitude modulation (PS-QAM) format is allocated in each subcarrier (SC) to increase the spectral efficiency (SE) of the channel as much as possible. In addition, the bandwidth resource allocation scheme should be reasonably designed by the operator.

[0080] The optical line terminal 110 informs (560) the new user end 502 of the allocation information, including the subcarrier (SC) number and position and the probability shaped quadrature amplitude modulation (PS-QAM) parameters. It then carries the payload on the allocated subcarrier (SC). At the receiving end, the user will use digital signal processing (DSP) to retrieve the required data based on the received control message.

[0081] For the common user terminal 503, when the common user terminal 503 is powered on (570), the terminal access and registration (575) are completed first, and the traffic demand information is sent (580) to the optical line terminal 501. The optical line terminal 501 performs resource allocation operation (585) based on the lookup table and the received service demand information, notifies (590) the common user terminal 503 of the allocation information and transmits the effective load. For the common user terminal 503, it is not necessary to measure the channel condition again, and the recorded channel information can be read from the lookup table (LUT).

[0082] The two-dimensional time-frequency allocation scheme using probability shaping technology provided by one or more embodiments of the present disclosure solves the problem that the subcarrier capacity required by each optical network unit (end user) does not match the actual allocated subcarrier capacity, and / or the subcarrier capacity of each end user does not match the traffic demand, thereby maximizing the throughput of the optical access network and thus improving the resource utilization of the optical network. The interactive scheme provided by one or more embodiments of the present disclosure is applicable to Figure 5A The ultra-high-speed PON system based on coherent DSCM technology or other PtMP application scenarios such as xhaul and data center are shown in the figure. The workflow of downstream DSCM signal transmission is as follows: Figure 5B As shown, it is worth noting that the provided solution can also be used for transmission of uplink optical signals.

[0083] The following describes some specific implementations of the present disclosure in conjunction with the application of the two-dimensional time-frequency allocation solution provided by the present disclosure in a 400G-related PON system.

[0084] like Figure 6 As shown, the coherent PON system has an OLT 610 and three ONUs (620-1, 620-2, and 620-3, respectively), which are connected through optical fibers and couplers. Due to different optical fiber links, the received optical power (ROP) of ONU_G1, ONU_G2, and ONU_G3 is approximately -15.4dBm, -25.3dBm, and -29.3dBm, respectively. In addition, the length of the optical fiber from the OLT to the three ONUs is also different, which is 10km, 20km, and 15km, respectively.

[0085] The PON system uses the DSCM modulation format and coherent detection, where the number of subcarriers (SC) is 8, and each SC has an 8GHz bandwidth (as shown in the figure). Assuming the spectrum efficiency is 4bit / s / Hz, the total capacity of 8 SCs is 512Gb / s. Considering 20% ​​forward error correction (FEC), the design capacity of the PON system is about 400Gb / s.

[0086] Two PS encoders are used to generate PS-QAM symbols with certain spectral efficiency for both x-polarization and y-polarization. After the PS-QAM signal is generated, the DSP module inserts the header into the beginning of the signal to achieve frame synchronization, frequency offset estimation and channel equalization on the Rx side. The header includes a total of 636 symbols, of which 60 binary phase shift keying (BPSK) symbols, 48 ​​quadrature phase shift keying (QPSK) symbols and 528 8-phase shift keying (8PSK) symbols are used for the above three functions. Then, in this module, the PS-QAM symbols are filtered using the RRCF raised root cosine filter and divided into 8 groups, which are multiplexed together through frequency division multiplexing (FDM). The roll-off factor of the RRCF is 0.1, and each SC occupies 10GHz bandwidth.

[0087] The generated symbols are then output by four digital-to-analog converters (DACs) and amplified by electrical amplifiers. Two IQ modulators are used to convert the electrical signals into dual-polarization DSCM signals. After modulation, the optical signals are amplified by an erbium-doped fiber amplifier (EDFA), and the amplifier spontaneous emission (ASE) noise is filtered out by an optical filter. Finally, the optical signal is launched into the trunk fiber.

[0088] In this embodiment, according to the traffic requirements of ONU_G1, ONU_G2 and ONU_G3, 2 SCs on the left, 4 SCs in the middle and 2 SCs on the right are allocated to ONU_G1, ONU_G2 and ONU_G3 respectively, and the initial traffic is approximately 120Gb / s, 250Gb / s and 95Gb / s respectively.

[0089] 200 / 100G coherent DSCM Rx has almost the same coherent DSCM Rx and DSP algorithm, except for the different device bandwidth and frequency shift in DSP. ONU_G1 and ONU_G3 have smaller Rx bandwidth and can only detect 2 SCs in DSCM signal, while ONU_G2 can detect 4 SCs. In ONU, coherent receiver is used to receive signals carried on two optical polarizations. Four analog-to-digital converters (ADC) sample the electrical signal after balanced photodetector (BPD).

[0090] Next, the corresponding simulation is implemented in the VPI software using the DSP algorithm in Python language. This includes frequency shift, dispersion (CD) compensation, digital filtering, data-aided frequency domain equalization (FDE) and carrier phase recovery. In this embodiment, the LO frequencies in ONU_G1 and ONU_G3 are appropriately adjusted to detect the left and right SCs in the DSCM signal. Under the 4-dimensional BER measurement module (BER4D), the recovered symbols are compared with the original transmission signal to calculate the bit error rate (BER).

[0091] Figure 7 The spectral efficiency of the three ONUs varies with BER at -15.4dBm, -25.3dBm and -29.3dBm ROP (solid line). Here, we assume that the FEC threshold is 2e -2 , FEC overhead accounts for 20% of the total overhead. Due to the receiving edge SC and relatively low receiving power, the spectrum efficiency of ONU_G3 receiving PS-QAM signals can reach up to 3.9bit / s / Hz, and the spectrum efficiency of ONU_G2 and ONU_G1 are 5bit / s / Hz and 5.2bit / s / Hz respectively, which can meet the service requirements of three ONUs at 95Gb / s, 250Gb / s and 120Gb / s.

[0092] Figure 8 The SC reallocation process of ONU_G2 and ONU_G3 when the service demand changes at time T1 is described. At time T1, the capacity demand of ONU_G3 rises to 120Gb / s, while the capacity demand of ONU_G2 drops to 160Gb / s. Therefore, according to the channel conditions, the central SC is allocated to ONU_G3, increasing the total capacity from 95Gb / s to 120Gb / s. The increase in SE of ONU_G3 mainly comes from the different frequency responses of the central SC and the edge SC in the downstream DSCM signal. For ONU_G2, the last 3 SCs are used to transmit signals of about 160Gb / s. The LO frequency at the Rx in ONU_G2 and ONU_G3 should be adjusted accordingly to receive the reallocated SC.

[0093] In the embodiments of the present disclosure, a two-dimensional frequency and time allocation scheme using probabilistic shaping technology is proposed for the first time to maximize the throughput of the PtMP coherent DSCM system. The scheme allocates bandwidth resources to different terminals according to their respective traffic requirements and channel conditions. With this scheme, the coherent DSCM system can maximize the use of available bandwidth resources of the optical fiber infrastructure. Therefore, we believe that this is a promising approach to support the widespread application of coherent DSCM systems in future ultra-high-speed optical access networks, such as PON systems, 5G / 6G xhaul, and data centers.

[0094] Fig. 9 FIG. 1 is a schematic diagram of a process flow executed by the optical line terminal 110 according to some embodiments of the present disclosure. Figure 1A To describe Fig. 9 900. In block 910, the optical line terminal 110 allocates at least one subcarrier and at least one time slot to the optical network unit 120 from a plurality of subcarriers in the frequency domain and a plurality of time slots in the time domain based on the channel condition information and service demand information of the optical network unit 120. In block 920, the optical line terminal 110 sends resource allocation information to the optical network unit 120, and the resource allocation information indicates at least one subcarrier and at least one time slot allocated to the optical network unit 120. In block 930, based on the at least one subcarrier and at least one time slot, the optical line terminal 110 performs communication with the optical network unit 120.

[0095] In some embodiments, the resource allocation information further indicates a probability shaped quadrature amplitude modulation (PS-QAM) parameter corresponding to a subcarrier in the at least one subcarrier.

[0096] In some embodiments, the optical line terminal 110 performs communication with the optical network unit 120 by receiving a modulation signal generated by modulating a subcarrier based on a PS-QAM parameter from the optical network unit 120 based on one or more time slots associated with the subcarrier.

[0097] In some embodiments, the frequency domain position of at least one subcarrier assigned to the optical network unit 120 in at least one time slot is fixed; or at least one subcarrier assigned to the optical network unit 120 has a higher spectral efficiency for the optical network unit 120 than other subcarriers in at least one time slot.

[0098] In some embodiments, the optical line terminal 110 also measures the channel condition of the optical network unit 120 based on determining that the optical network unit 120 is connected to the optical line terminal 110 for the first time to obtain channel condition information of the optical network unit 120; or obtains the channel condition information of the optical network unit 120 from a lookup table for recording channel condition information of multiple optical network units based on determining that the optical network unit 120 is not connected to the optical line terminal 110 for the first time.

[0099] In some embodiments, the optical line terminal 110 measures the channel condition of the optical network unit 120 by: sending a full-bandwidth digital subcarrier modulation (DSCM) signal including at least one subcarrier to the optical network unit 120; and receiving channel condition information from the optical network unit 120, wherein the channel condition information includes at least one of a frequency response or a signal-to-noise ratio of multiple subcarriers of the full-bandwidth DSCM signal at the optical network unit 120.

[0100] In some embodiments, the optical line terminal 110 further updates the lookup table based on the channel condition information of the optical network unit 120 obtained through measurement.

[0101] In some embodiments, the optical line terminal 110 also periodically remeasures the channel condition information of the optical network unit 120 at preset time intervals and updates the lookup table; or updates the lookup table based on determining that one or more subcarriers of the full-bandwidth DSCM signal have bit errors in one or more optical network units 120 among multiple optical network units.

[0102] In some embodiments, the optical line terminal 110 further receives service demand information from the optical network unit 120 .

[0103] In some embodiments, at least one subcarrier is a subcarrier in a digital subcarrier modulated (DSCM) signal.

[0104] Fig.10 FIG. 1 is a schematic diagram of a process flow executed by the optical network unit 120 according to some embodiments of the present disclosure. Figure 1A To describe Fig.10 1000. In block 1010, the optical network unit 120 receives resource allocation information from the optical line terminal 110, where the resource allocation information indicates at least one subcarrier and at least one time slot allocated to the optical network unit 120 from among a plurality of subcarriers in the frequency domain and a plurality of time slots in the time domain. In block 1020, the optical network unit 120 performs communication with the optical line terminal 110 based on the at least one subcarrier and the at least one time slot.

[0105] In some embodiments, the resource allocation information further indicates a probability shaped quadrature amplitude modulation (PS-QAM) parameter corresponding to a subcarrier in the at least one subcarrier.

[0106] In some embodiments, the optical network unit 120 communicates with the optical line terminal 110 by: modulating the subcarrier based on PS-QAM parameters to generate a modulated signal; and sending the modulated signal to the optical line terminal 110 based on one or more time slots associated with the subcarrier.

[0107] In some embodiments, the frequency domain position of at least one subcarrier assigned to the optical network unit 120 in at least one time slot is fixed; or at least one subcarrier assigned to the optical network unit 120 has a higher spectral efficiency for the optical network unit 120 than other subcarriers in at least one time slot.

[0108] In some embodiments, at least one subcarrier and at least one time slot allocated to the optical network unit 120 , and parameters of the PS-QAM are determined based on channel condition information and service demand information of the optical network unit 120 .

[0109] In some embodiments, the optical network unit 120 further sends service demand information to the optical line terminal 110 .

[0110] In some embodiments, the optical network unit 120 also receives a full-bandwidth DSCM signal including at least one subcarrier from the optical line terminal 110 when the optical network unit 120 is connected to the optical line terminal 110 for the first time; determines channel condition information of the optical network unit 120 based on receiving the full-bandwidth DSCM signal, wherein the channel condition information includes at least one of a frequency response or a signal-to-noise ratio of multiple subcarriers of the full-bandwidth DSCM signal at the optical network unit 120; and sends the channel condition information to the optical line terminal 110.

[0111] In some embodiments, the optical network unit 120 determines the channel condition information of the optical network unit 120 by: obtaining the full-bandwidth channel response of the full-bandwidth DSCM signal based on a single digital signal processing of the full-bandwidth DSCM signal; or by adjusting the local oscillator frequency of the receiver of the optical network unit and obtaining the channel response of multiple subcarriers of the full-bandwidth DSCM signal through multiple coherent detections.

[0112] In some embodiments, at least one subcarrier is a subcarrier in a digital subcarrier modulated (DSCM) signal.

[0113] In some example embodiments, an apparatus capable of executing method 900 (eg, optical line terminal 110) may include a component for executing each step of method 900. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit or a software module.

[0114] The device includes: a component for allocating at least one subcarrier and at least one time slot to an optical network unit from multiple subcarriers in the frequency domain and multiple time slots in the time domain based on channel condition information and service demand information of the optical network unit at an optical line terminal; a component for sending resource allocation information to the optical network unit, the resource allocation information indicating at least one subcarrier and at least one time slot allocated to the optical network unit; and a component for performing communication with the optical network unit based on the at least one subcarrier and at least one time slot.

[0115] In some embodiments, the resource allocation information further indicates a probability shaped quadrature amplitude modulation (PS-QAM) parameter corresponding to a subcarrier in the at least one subcarrier.

[0116] In some embodiments, means for performing communication with an optical network unit includes means for receiving, from the optical network unit, a modulated signal generated by modulating a subcarrier based on PS-QAM parameters based on one or more time slots associated with the subcarrier.

[0117] In some embodiments, the frequency domain position of at least one subcarrier allocated to the optical network unit in at least one time slot is fixed; or at least one subcarrier allocated to the optical network unit has a higher spectral efficiency for the optical network unit than other subcarriers in at least one time slot.

[0118] In some embodiments, the device also includes: based on determining that the optical network unit is connected to the optical line terminal for the first time, measuring the channel condition of the optical network unit to obtain channel condition information of the optical network unit; or based on determining that the optical network unit is not connected to the optical line terminal for the first time, obtaining the channel condition information of the optical network unit from a lookup table for recording channel condition information of multiple optical network units.

[0119] In some embodiments, a component for measuring a channel condition of an optical network unit includes: a component for sending a full-bandwidth digital subcarrier modulation (DSCM) signal including at least one subcarrier to the optical network unit; and a component for receiving channel condition information from the optical network unit, wherein the channel condition information includes at least one of a frequency response or a signal-to-noise ratio of multiple subcarriers of the full-bandwidth DSCM signal at the optical network unit.

[0120] In some embodiments, the apparatus further comprises: a component for updating the lookup table based on the channel condition information of the optical network unit obtained through measurement.

[0121] In some embodiments, the device also includes: a component for periodically re-measuring the channel condition information of the optical network unit at a preset time interval and updating the lookup table; or a component for updating the lookup table based on determining that one or more subcarriers of the full-bandwidth DSCM signal have bit errors in one or more optical network units among multiple optical network units.

[0122] In some embodiments, the apparatus further comprises: a component for receiving service demand information from an optical network unit.

[0123] In some embodiments, at least one subcarrier is a subcarrier in a digital subcarrier modulated (DSCM) signal.

[0124] In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of method 900. In some embodiments, the means comprises at least one processor and at least one memory storing computer program code. The at least one memory and the computer program code are configured to, together with the at least one processor, cause execution of the apparatus.

[0125] In some example embodiments, a device capable of performing method 1000 (eg, optical network unit 120) may include a component for performing each step of method 1000. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit or a software module.

[0126] The device includes: a component for receiving resource allocation information from an optical line terminal at an optical network unit, the resource allocation information indicating at least one subcarrier and at least one time slot allocated to the optical network unit from multiple subcarriers in the frequency domain and multiple time slots in the time domain; and a component for performing communication with the optical line terminal based on the at least one subcarrier and the at least one time slot.

[0127] In some embodiments, the resource allocation information further indicates a probability shaped quadrature amplitude modulation (PS-QAM) parameter corresponding to a subcarrier in the at least one subcarrier.

[0128] In some embodiments, the means for performing communication with an optical line terminal includes: means for modulating a subcarrier based on PS-QAM parameters to generate a modulated signal; and means for sending the modulated signal to the optical line terminal based on one or more time slots associated with the subcarrier.

[0129] In some embodiments, the frequency domain position of at least one subcarrier allocated to the optical network unit in at least one time slot is fixed; or at least one subcarrier allocated to the optical network unit has a higher spectral efficiency for the optical network unit than other subcarriers in at least one time slot.

[0130] In some embodiments, at least one subcarrier and at least one time slot allocated to the optical network unit, and parameters of the PS-QAM are determined based on channel condition information and service demand information of the optical network unit.

[0131] In some embodiments, the apparatus further comprises a component for sending service demand information to the optical line terminal.

[0132] In some embodiments, the device also includes a component for receiving a full-bandwidth DSCM signal including at least one subcarrier from an optical line terminal when the optical network unit is first connected to the optical line terminal; a component for determining channel condition information of the optical network unit based on receiving the full-bandwidth DSCM signal, wherein the channel condition information includes at least one of a frequency response or a signal-to-noise ratio of multiple subcarriers of the full-bandwidth DSCM signal at the optical network unit; and a component for sending the channel condition information to the optical line terminal.

[0133] In some embodiments, the component for determining the channel condition information of the optical network unit includes: a component for obtaining the full-bandwidth channel response of the full-bandwidth DSCM signal based on a single digital signal processing of the full-bandwidth DSCM signal; or a component for obtaining the channel response of multiple subcarriers of the full-bandwidth DSCM signal through multiple coherent detections by adjusting the local oscillator frequency of the receiver of the optical network unit.

[0134] In some embodiments, at least one subcarrier is a subcarrier in a digital subcarrier modulated (DSCM) signal.

[0135] In some embodiments, the apparatus further comprises components for performing other steps in some embodiments of method 1000. In some embodiments, the components comprise at least one processor and at least one memory storing computer program code. The at least one memory and the computer program code are configured to, together with the at least one processor, cause execution of the apparatus.

[0136] Fig.11 1 is a simplified block diagram of an electronic device 1100 suitable for implementing embodiments of the present disclosure. The device 1100 may be provided to implement an optical line terminal or an optical network unit, such as Figure 1A An optical line terminal 110 or an optical network unit 120 is shown. As shown, the device 1100 includes one or more processors 1110, one or more memories 1120 coupled to the processor 1110, and one or more communication modules 1140 coupled to the processor 1110.

[0137] The communication module 1140 is used for two-way communication. For example, the communication module 1140 may include a transmitter, a receiver, or a transceiver used in the embodiments of the present disclosure. The communication interface may represent any interface necessary for communicating with other network elements.

[0138] Processor 1110 may be of any type suitable for the local technology network and may include, but is not limited to, one or more of a general purpose computer, a special purpose computer, a microcontroller, a digital signal controller (DSP), and a controller-based multi-core controller architecture. Device 1100 may have multiple processors, such as application specific integrated circuit chips, which are time-slaved to a clock synchronized with a main processor.

[0139] The memory 1120 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 1124, erasable programmable read-only memory (EPROM), flash memory, hard disk, compact disk (CD), digital video disk (DVD), and other magnetic storage and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 1122 and other volatile memories that do not persist over the duration of a power outage.

[0140] Computer program 1130 includes computer executable instructions executed by associated processor 1110. Program 1130 may be stored in ROM 1120. Processor 1110 may perform any suitable actions and processes by loading program 1130 into RAM 1122.

[0141] The embodiments of the present disclosure can be implemented with the help of program 1130, so that the device 1100 can execute the Figure 2 Any process of the present disclosure discussed. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

[0142] In some embodiments, the program 1130 may be tangibly embodied in a computer-readable medium that may be included in the device 1100 (such as in the memory 1120) or other storage device accessible by the device 1100. The program 730 may be loaded from the computer-readable medium to the RAM 1122 for execution. The computer-readable medium may include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc.

[0143] Fig.12 An example of a computer readable medium 1200 in the form of a CD or DVD is shown. The computer readable medium has a program 1130 stored thereon.

[0144] In general, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be performed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are shown and described as block diagrams, flow charts, or using some other graphical representation, it should be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented as, by way of non-limiting example, hardware, software, firmware, dedicated circuits or logic, general purpose hardware or a controller or other computing device, or some combination thereof.

[0145] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer executable instructions, such as instructions included in a program module, which are executed in a device on a real or virtual processor of a target to perform the above-referenced Figures 9 and 10 Methods 900, 1000. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or divided between program modules as needed. Machine executable instructions for program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in local and remote storage media.

[0146] The computer program code for realizing the method of the present disclosure can be written in one or more programming languages. These computer program codes can be provided to the processor of general-purpose computer, special-purpose computer or other programmable data processing device, so that the program code, when being executed by computer or other programmable data processing device, causes the function / operation specified in flow chart and / or block diagram to be implemented. The program code can be executed completely on computer, partly on computer, as independent software package, partly on computer and partly on remote computer or completely on remote computer or server.

[0147] In the context of the present disclosure, computer program codes or related data may be carried by any appropriate carrier to enable a device, apparatus or processor to perform the various processes and operations described above. Examples of carriers include signals, computer readable media, and the like. Examples of signals may include electrical, optical, radio, acoustic or other forms of propagation signals, such as carrier waves, infrared signals, and the like.

[0148] A computer-readable medium may be any tangible medium containing or storing a program for or about an instruction execution system, device or equipment. A computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. A computer-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared or semiconductor system, device or equipment, or any suitable combination thereof. A more detailed example of a computer-readable storage medium includes an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical storage device, a magnetic storage device, or any suitable combination thereof. As used herein, the term "non-transient" or "non-transient" is a limitation on the medium itself (i.e., tangible, not a signal), rather than a limitation on the persistence of data storage (e.g., RAM and ROM).

[0149] In addition, although the operation of the method of the present disclosure is described in a particular order in the accompanying drawings, this does not require or imply that these operations must be performed in this particular order, or that all the operations shown must be performed to achieve the desired result. On the contrary, the steps depicted in the flow chart can change the order of execution. Additionally or alternatively, some steps can be omitted, multiple steps can be combined into one step for execution, and / or one step can be decomposed into multiple steps for execution. It should also be noted that the features and functions of two or more devices according to the present disclosure can be embodied in one device. Conversely, the features and functions of a device described above can be further divided into being embodied by multiple devices.

[0150] Although the present disclosure has been described with reference to several specific embodiments, it should be understood that the present disclosure is not limited to the specific embodiments disclosed. The present disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0151] In addition, although the operation of the method of the present disclosure is described in a particular order in the accompanying drawings, this does not require or imply that these operations must be performed in this particular order, or that all the operations shown must be performed to achieve the desired result. On the contrary, the steps depicted in the flow chart can change the order of execution. Additionally or alternatively, some steps can be omitted, multiple steps can be combined into one step for execution, and / or one step can be decomposed into multiple steps for execution. It should also be noted that the features and functions of two or more devices according to the present disclosure can be embodied in one device. Conversely, the features and functions of a device described above can be further divided into being embodied by multiple devices.

[0152] Although the present disclosure has been described with reference to several specific embodiments, it should be understood that the present disclosure is not limited to the specific embodiments disclosed. The present disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. An optical line terminal, comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the optical line terminal to at least: Based on the channel condition information and service demand information of the optical network unit, allocating at least one subcarrier and at least one time slot to the optical network unit from a plurality of subcarriers in the frequency domain and a plurality of time slots in the time domain; sending resource allocation information to the optical network unit, the resource allocation information indicating the at least one subcarrier and the at least one time slot allocated to the optical network unit; and Based on the at least one subcarrier and the at least one time slot, communication with the optical network unit is performed.

2. The optical line terminal according to claim 1, wherein the resource allocation information further indicates a probability shaped quadrature amplitude modulation (PS-QAM) parameter corresponding to a subcarrier in the at least one subcarrier.

3. The optical line terminal according to claim 2, wherein the optical line terminal is caused to perform communication with the optical network unit by: A modulation signal generated by modulating the subcarrier based on the PS-QAM parameter is received from the optical network unit based on one or more time slots associated with the subcarrier.

4. The optical line terminal according to any one of claims 1 to 3, wherein: The frequency domain position of the at least one subcarrier allocated to the optical network unit in the at least one time slot is fixed; or The at least one subcarrier allocated to the optical network unit has a higher spectrum efficiency for the optical network unit in the at least one time slot than other subcarriers.

5. The optical line terminal according to any one of claims 1 to 4, wherein the optical line terminal is further configured to: Based on determining that the optical network unit is connected to the optical line terminal for the first time, measuring the channel condition of the optical network unit to obtain the channel condition information of the optical network unit; or Based on determining that the optical network unit is not connected to the optical line terminal for the first time, the channel condition information of the optical network unit is obtained from a lookup table used to record channel condition information of multiple optical network units.

6. The optical line terminal according to claim 5, wherein the optical line terminal is caused to measure the channel condition of the optical network unit by: sending a full-bandwidth digital subcarrier modulated (DSCM) signal including the at least one subcarrier to the optical network unit; and The channel condition information is received from the optical network unit, wherein the channel condition information includes at least one of a frequency response or a signal-to-noise ratio of a plurality of subcarriers of the full-bandwidth DSCM signal at the optical network unit.

7. The optical line terminal according to claim 5 or 6, wherein the optical line terminal is further configured to: The lookup table is updated based on the channel condition information of the optical network unit obtained through measurement.

8. The optical line terminal according to claim 7, wherein the optical line terminal is further configured to at least one of the following: re-measuring the channel condition information of the optical network unit periodically at preset time intervals, and updating the lookup table; or The lookup table is updated based on determining that one or more subcarriers of the full-bandwidth DSCM signal have bit errors for one or more optical network units among the multiple optical network units.

9. The optical line terminal according to any one of claims 1 to 8, wherein the optical line terminal is further configured to: The service demand information is received from the optical network unit.

10. The optical line terminal according to any one of claims 1-9, wherein the at least one subcarrier is a subcarrier in a digital subcarrier modulation (DSCM) signal.

11. An optical network unit, comprising: at least one processor; as well as at least one memory storing instructions, which, when executed by the at least one processor, cause the optical network unit to at least: receiving resource allocation information from an optical line terminal, the resource allocation information indicating at least one subcarrier and at least one time slot allocated to the optical network unit from a plurality of subcarriers in the frequency domain and a plurality of time slots in the time domain; and Based on the at least one subcarrier and the at least one time slot, communication with the optical line terminal is performed.

12. The optical network unit of claim 11, wherein the resource allocation information further indicates a probability shaped quadrature amplitude modulation (PS-QAM) parameter corresponding to a subcarrier in the at least one subcarrier.

13. The optical network unit according to claim 12, wherein the optical network unit is caused to perform communication with the optical line terminal by: Modulating the subcarrier based on the PS-QAM parameter to generate a modulated signal; The modulated signal is transmitted to the optical line terminal based on one or more time slots associated with the subcarrier.

14. The optical network unit according to any one of claims 11 to 13, wherein: The frequency domain position of the at least one subcarrier allocated to the optical network unit in the at least one time slot is fixed; or The at least one subcarrier allocated to the optical network unit has a higher spectrum efficiency for the optical network unit in the at least one time slot than other subcarriers.

15. The optical network unit according to claim 12 or 13, wherein the at least one subcarrier and the at least one time slot allocated to the optical network unit, and parameters of PS-QAM are determined based on channel condition information and service demand information of the optical network unit.

16. The optical network unit according to claim 15, wherein the optical network unit is further configured to: The service requirement information is sent to the optical line terminal.

17. The optical network unit according to claim 15 or 16, wherein the optical network unit is further configured to: receiving, in a case where the optical network unit is connected to the optical line terminal for the first time, a full-bandwidth DSCM signal including the at least one subcarrier from the optical line terminal; determining the channel condition information of the optical network unit based on receiving the full-bandwidth DSCM signal, wherein the channel condition information comprises at least one of a frequency response or a signal-to-noise ratio of a plurality of subcarriers of the full-bandwidth DSCM signal at the optical network unit; and The channel condition information is sent to the optical line terminal.

18. The optical network unit according to claim 17, wherein the optical network unit is caused to determine the channel condition information of the optical network unit by: Obtaining a full-bandwidth channel response of the full-bandwidth DSCM signal based on a single digital signal processing of the full-bandwidth DSCM signal; or The channel responses of the multiple subcarriers of the full-bandwidth DSCM signal are obtained through multiple coherent detections by adjusting the local oscillator frequency of the receiver of the optical network unit.

19. The optical network unit according to any one of claims 11-18, wherein the at least one subcarrier is a subcarrier in a digital subcarrier modulation (DSCM) signal.

20. A method comprising: At the optical line terminal, based on the channel condition information and service demand information of the optical network unit, at least one subcarrier and at least one time slot are allocated to the optical network unit from a plurality of subcarriers in the frequency domain and a plurality of time slots in the time domain; sending resource allocation information to the optical network unit, the resource allocation information indicating the at least one subcarrier and the at least one time slot allocated to the optical network unit; and Based on the at least one subcarrier and the at least one time slot, communication with the optical network unit is performed.

21. A method comprising: At an optical network unit, receiving resource allocation information from an optical line terminal, the resource allocation information indicating at least one subcarrier and at least one time slot allocated to the optical network unit from a plurality of subcarriers in a frequency domain and a plurality of time slots in a time domain; and Based on the at least one subcarrier and the at least one time slot, communication with the optical line terminal is performed.

22. An apparatus comprising: A component for allocating at least one subcarrier and at least one time slot to the optical network unit from a plurality of subcarriers in the frequency domain and a plurality of time slots in the time domain at an optical line terminal based on the channel condition information and service demand information of the optical network unit; means for sending resource allocation information to the optical network unit, wherein the resource allocation information indicates the at least one subcarrier and the at least one time slot allocated to the optical network unit; as well as Means for performing communications with the optical network unit based on the at least one subcarrier and the at least one time slot.

23. An apparatus comprising: A means for receiving, at an optical network unit, resource allocation information from an optical line terminal, wherein the resource allocation information indicates at least one subcarrier and at least one time slot allocated to the optical network unit from a plurality of subcarriers in the frequency domain and a plurality of time slots in the time domain; as well as Means for performing communication with the optical line terminal based on the at least one subcarrier and the at least one time slot.

24. A computer-readable medium comprising program instructions, which, when executed by a device, cause the device to perform the method according to claim 20 or 21.

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