Method for setting equalization resources of an equalizer in a transceiver optical device

Abstract

1. A method for configuring equalization resources of an equalizer of a transceiver optical device, the equalization resources being used by the equalizer to perform equalization on optical signals received over channels of an optical line, the method comprising: acquiring environmental parameter values, the environmental parameter values ​​being values ​​of environmental data on physical parameters or derivatives affecting channels of the optical line; acquiring channel depth estimates from past experience in view of the environmental parameter values; and selectively enabling the equalization resources to perform equalization on optical signals received over channels of the optical line according to the acquired channel depth estimates.

Description

[Technical Field]

[0001] The present invention relates generally to optical communications, and more particularly to setting equalization resources of an equalizer in a transceiver optical device. Priority is claimed to European Patent Application No. 23305866.8, filed June 1, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] Optical communications are increasingly used within FTTH ("Fiber To The Home") technology deployments to provide network access (usually Internet access) to residential or office gateways or data centers. Optical communications may also be used to ensure mobile infrastructure backhaul, for example, within the deployment of 3G (third generation) or 4G (fourth generation) mobile technologies, which typically use point-to-point configurations.

[0003] Emerging 5G (fifth generation) mobile technologies are introducing fronthaul, significantly increasing the need for data rate capabilities. Reference can be made to the International Mobile Telecommunications (IMT) Recommendation ITU-R M.2083, "IMT Vision: Framework and overall objectives of the future development of IMT for 2020 and beyond," published in September 2015. In such a framework, fronthaul is achieved by moving upstream the mobile infrastructure processing functions previously performed at or near the base station for 3G or 4G mobile technologies. This is referred to as the "split option" in the specification 3GPP® TR 38.801 V 14.0.0, "Study on new radio access technology: Radio access architecture and interfaces," published in March 2017 (see Section 11 and Table A-1 for more details).

[0004] 5G mobile technology therefore has a broader set of requirements compared to the FTTH requirements that have driven the evolution of optical access technology thus far, leading to, among other things, higher nominal data rates, lower latency, and denser deployments.

[0005] Furthermore, technology trends such as the Internet of Things, edge computing, artificial intelligence, robotics, and augmented reality are highly demanding in terms of communication infrastructure, but these trends also have widely different requirements in terms of data throughput or quality of service to be supported by optical access networks.

[0006] Therefore, optical access systems should be able to carry very high data rate throughput (over 50 Gbit / s, or even hundreds of Gbit / s in the near future), as well as very low data rates, for example, to carry IoT flows today. Optical access networks should support low latency, such as fractions of a millisecond, for applications such as virtual reality or industrial applications. This requires a highly flexible and efficient optical infrastructure.

[0007] Because of this variety of applications and corresponding requirements, we may refer herein to an "optical access and aggregation network" rather than simply an "optical access network."

[0008] Furthermore, it must be taken into account that optical lines may have to deal with very different length constraints, typically ranging from a few hundred meters to 40 kilometers.

[0009] Such diverse requirements and constraints present challenges with regard to managing the time and frequency spread of optical signals.

[0010] First, chromatic dispersion varies with the length of the optical line and further depends on the modulation signal bandwidth and optical signal wavelength. For example, considering a wavelength around 1550 nm, the time expansion due to chromatic dispersion can vary from a fraction of one symbol period to up to 20 symbol periods as the optical line length varies from 1 km to 40 km at 3 dB @ 100 GHz. Furthermore, environmental temperature fluctuations also have a significant impact on chromatic dispersion in high-bit-rate optical communication systems. It should also be noted that optical access and aggregation networks are typically deployed in outdoor conditions, i.e., in temperature-uncontrolled environments.

[0011] Optical lines are usually deployed in outdoor conditions, and therefore, in addition to the aforementioned temperature fluctuations, said lines are subject to vibrations caused by wind and possibly passing vehicles. Vibrations and temperature fluctuations affect Polarization Mode Dispersion (PMD). Polarization Mode Dispersion results from the relative delay between both polarization axes when an anisotropic constraint is applied to the optical line. This relative delay depends on the square of the length of the optical line.

[0012] 10 -7 For an outage probability of 0.05 ps / km (corresponding to a 3-second outage per year), the channel can be demonstrated to have a mean differential group delay (DGD) greater than 6 times. In optical access and aggregation networks, the mean differential group delay is typically 0.05 ps / km, as typically encountered in core networks. 0,5 from tens of picoseconds / km in harsh conditions, hundreds of times higher than typical values ​​for core networks 0.5 It can vary over a wide range of magnitudes, from 10 -7 If the stop probability is 0.05ps / km 0.5 to 10 hp / km 0.5 Considering the mean differential group delay, which can vary up to 100 Gbaud, the variation in time spread associated with polarization mode dispersion can vary from a fraction of a symbol period to almost 20 symbol periods for 30 Gbaud systems, or up to 45 symbol periods when considering 100 Gbaud systems.

[0013] Another aspect is that in uncontrolled environments, such as those encountered in optical access and aggregation networks, the nominal wavelength of a laser source or the center wavelength of an optical bandpass filter, which prevents inter-channel crosstalk, may shift. Because such devices are located in different geographic locations in optical access and aggregation network deployments, they are exposed to different environmental conditions that induce relative wavelength shifts. For example, considering a 100 GHz optical bandpass filter at 3 dB based on a Bragg grating, its time response may extend over 200 picoseconds as the carrier wavelength shifts across the passband of the optical bandpass filter. This may correspond to a time fluctuation of nearly 10 symbol periods for a 30 Gbaud system, or even 30 symbol periods for a 100 Gbaud system.

[0014] One can also add that optical access and aggregation networks use a variety of transceivers (many vendors, variable work points), which implies different types of pulse distortion, resulting in different symbol spreading behavior.

[0015] As can be seen from the foregoing, many physical phenomena affect the spreading of optical signals in optical access and aggregation networks, which may have been considered unimportant in the past because high needs in terms of data rate capabilities were only considered for core networks with controlled environments, while optical access networks in uncontrolled environments were targeted at much lower needs in terms of data rate capabilities.

[0016] Optical access and aggregation networks now have to deal with these physical phenomena, and therefore must perform equalization, a signal processing procedure aimed at mitigating inter-symbol interference (ISI) on a communication channel.

[0017] For understanding, if we consider linear equalization in the time domain, successive received symbol samples

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[0018] Equalization Coefficients

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[0019] As optical link dimensioning, equalization resource dimensioning needs to be defined according to the worst-case spreading case. In view of the foregoing, a large amount of information must be retrieved from the channel, and a large number of symbols must be processed to perform equalization in the worst-case spreading case, which means a large number of equalization coefficients must be calculated, and further means that once the equalization coefficients are properly determined, a large number of computational resources must be dedicated to optical signal equalization.

[0020] However, relying on the worst spreading case to operate the equalization resources is not efficient in terms of equalization resource usage, particularly in terms of hardware block allocation, in terms of equalization signaling overhead and therefore computational resource usage, and in terms of energy consumption. It is therefore desirable to provide an energy-efficient solution suitable for optical access and aggregation networks, and it is desirable to provide a solution that is as simple as possible. [Prior art documents] [Non-patent literature]

[0021] [Non-Patent Document 1] International Mobile Telecommunications (IMT) Recommendation ITU-R M.2083 "IMT Vision: Framework and overall objectives of the future development of IMT for 2020 and beyond" [Non-patent document 2] Specification 3GPP (registered trademark) TR 38.801 V 14.0.0 "Study on new radio access technology: Radio access architecture and interfaces" Summary of the Invention [Means for solving the problem]

[0022] To that end, the present specification provides a method for configuring equalization resources of an equalizer of a transceiver optical device, the equalization resources being used by the equalizer to perform equalization on optical signals received over channels of an optical line, the method comprising the steps of: acquiring environmental parameter values, the environmental parameter values ​​being values ​​of environmental data on physical parameters or derivatives affecting channels of the optical line; acquiring channel depth estimates from past experience in view of the environmental parameter values; and selectively enabling the equalization resources to perform equalization on optical signals received over channels of the optical line according to the acquired channel depth estimates.

[0023] Thus, the operation of the equalization resources is improved in terms of the use of equalization resources, in particular in terms of the allocation of hardware blocks, in terms of the equalization signaling overhead and therefore in terms of the use of computational resources, and in terms of energy consumption.

[0024] In a particular embodiment, to obtain a channel depth estimate from past experience, the method includes the steps of searching in a lookup table to determine whether the lookup table includes channel-related information associated with an environmental parameter value, and if the lookup table includes channel-related information associated with an environmental parameter value, using a channel depth estimate included in the channel-related information included in the lookup table, and if the lookup table does not include channel-related information associated with an environmental parameter value, using a channel depth estimate as in the worst case.

[0025] Therefore, an improved operation of the equalization resource is easily achieved.

[0026] In certain embodiments, the lookup table is populated at least in part by monitoring the equalization performance of the equalizer to determine channel training data, time-stamping the channel training data, obtaining environmental training data that reflects actual environmental conditions of the optical line, time-stamping the environmental training data, and associating the environmental training data with the channel training data using the time-stamp information.

[0027] Thus, the look-up tables are populated and their contents are improved along with the experience gained by the transceiver optical device.

[0028] In certain embodiments, the lookup table is at least partially populated by obtaining training data for other channels having similar deployment conditions of optical lines.

[0029] Thus, the look-up table is populated and its contents are improved using experience gained on different optical lines.

[0030] In a particular embodiment, the method further includes adding a predetermined depth margin to the channel depth estimate.

[0031] Therefore, channel variations and estimation errors can be easily compensated for.

[0032] In certain embodiments, the predetermined depth margin depends on the time of coherence of the channel and / or the actual equalization performance and / or the time elapsed since the last update of the actual knowledge of the channel characteristics.

[0033] Therefore, the depth margin can be optimized depending on the situation.

[0034] In particular embodiments, the equalization resources include hardware blocks used to perform equalization on optical signals received over channels of an optical line.

[0035] Therefore, power consumption improvements for hardware resources can be achieved.

[0036] In a particular embodiment, the equalization resource includes equalization overhead in an optical signal received over a channel of the optical line, and the method includes transmitting equalization-related information indicating a size of equalization overhead used to transmit said optical signal to another transceiver optical device that transmits said optical signal over a channel of the optical line.

[0037] Therefore, improved computational resources and improved latency can be achieved to handle equalization overhead such as preambles.

[0038] In a particular embodiment, the method further comprises defining a size of an equalization overhead for another optical signal transmitted from the transceiver optical device to said another transceiver optical device according to the obtained channel depth estimate.

[0039] Therefore, the other transceiver optical device can also benefit from this improvement in view of the reciprocal channel.

[0040] In certain embodiments, the environmental data is predicted environmental data for a future time point, and the use of equalization resources is scheduled to be enabled when the future time point in question is reached.

[0041] Thus, the use of equalization resources can be scheduled and improvements can be expected.

[0042] Further proposed herein is a transceiver optical device including an equalizer for performing equalization on optical signals received over channels of an optical line, wherein the transceiver optical device is configured to set equalization resources of the equalizer, the equalization resources being used by the equalizer to perform equalization on optical signals received over channels of the optical line, and the transceiver optical device comprises an electronic circuit configured to obtain environmental parameter values, which are values ​​of environmental data on physical parameters or derivatives affecting channels of the optical line, obtain a channel depth estimate from past experience in view of the environmental parameter values, and selectively enable the equalization resources to perform equalization on optical signals received over channels of the optical line according to the obtained channel depth estimate. [Brief explanation of the drawings]

[0043] The characteristics of the invention will emerge more clearly from a reading of the following description of at least one example of embodiment, said description being produced with reference to the accompanying drawings, in which: [Figure 1] 1 is a diagram that schematically illustrates the layout of an optical communication system in which the present invention may be implemented; [Figure 2] 1 is a diagram illustrating a schematic arrangement of a transceiver optical device in an optical communication system. [Figure 3] FIG. 2 is a schematic representation of an equalization presetter arrangement; [Figure 4] FIG. 2 is a diagram that schematically illustrates an algorithm for selectively enabling equalization resources in accordance with one embodiment of the present invention. [Figure 5]FIG. 2 is a diagram that schematically illustrates an algorithm for selectively enabling equalization resources in accordance with a particular embodiment of the present invention. [Figure 6] FIG. 10 is a diagram illustrating an algorithm for feeding a look-up table in accordance with a specific embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0044] It should be noted that wavelength and frequency are linked to one another through a direct inverse relationship, and therefore these two terms are used interchangeably by those skilled in the art as they refer to the same concept.

[0045] FIG. 1 shows a schematic diagram of an optical communication system 100 arrangement in which the present invention may be implemented.

[0046] The optical communication system 100 is part of an optical access and aggregation network.

[0047] The optical communication system 100 comprises at least a first transceiver optical device T1 111 and a second transceiver optical device T2 112 that communicate with each other using an optical line 121 .

[0048] As exemplarily shown in the optical communication system 100 of FIG. 1, a first transceiver optical device T1 111 may communicate with other transceiver optical devices T3 113, T4 114 using respective optical lines 122, 123.

[0049] An optical line is an optical path between transceiver optical devices. The optical line includes optical fibers, but may further include power splitters, spectral splitter devices for performing WDM (wavelength division multiplexing), optical termination outlets, optical termination connectors, etc.

[0050] For example, the first transceiver optical device T1 111 is an OLT (Optical Line Terminal) device, and the second transceiver optical device T2 112, as well as the other transceiver optical devices T3 113, T4 114 are ONU (Optical Network Unit) devices.

[0051] 2 is a schematic representation of the placement of transceiver optical devices in the optical communication system 100. It is assumed that FIG. 2 is a schematic representation of the placement of a second transceiver optical device T2 112.

[0052] The second transceiver optical device T2 112 comprises a receive chain and a transmit chain.

[0053] The receive chain comprises a receive analog stage 211 including a photodiode for capturing the optical signal transmitted by the first transceiver optical device T1 111 via the optical line 121. The receive chain further comprises a receive digital stage RDS 212 for performing digital processing on the captured optical signal. The digital processing in the receive chain typically includes demodulation, equalization, and removal of equalization overhead, which may be understood as a cyclic prefix and / or a cyclic suffix in the frequency domain or a preamble in the time domain, depending on the modulation / demodulation used. The receive chain further comprises a receive data processing stage RDPS 213 for unpacking the data to be processed by the application APP 230.

[0054] The transmit chain comprises a transmit data processing stage TDPS 223 for packing data provided by the application APP 230. The transmit chain further comprises a transmit digital stage TDS 222 for performing digital processing on the packed data. The digital processing in the transmit chain typically includes modulation and equalization overhead insertion. The transmit chain further comprises a transmit analog stage 221 including a laser for transmitting an optical signal via the optical line 121 to the first transceiver optical device T1 111.

[0055] 2 , the receive digital stage RDS 212 may communicate equalization-related information to the transmit digital stage TDS 222 to set the size of the equalization overhead for inserting it into the transmit chain of the second transceiver optical device T2 112, and / or to provide feedback information to the first transceiver optical device T1 111 so that the first transceiver optical device T1 111 can perform its own equalization configuration accordingly, and / or to provide feedback information to the first transceiver optical device T1 111 so that the first transceiver optical device T1 111 can adjust the size of the equalization overhead of the optical signal transmitted to the second transceiver optical device T2 112 accordingly. In a variant, this communication of equalization-related information from the receive chain to the transmit chain may be performed via the receive data processing stage RDPS 213 and the transmit data processing stage TDPS 223 to facilitate information packing into the first transceiver optical device T1 111.

[0056] 3 shows a schematic representation of an equalization presetter 300. The equalization presetter 300 is part of the receive digital stage RDS 212 of the arrangement of FIG.

[0057] The equalization presetter 300 comprises a learning agent 310 configured to feed a look-up table (LUT) 320 that is subsequently used by a resource manager 330 to estimate the channel depth. The estimated channel depth is used to set the appropriate equalization resources via a hardware (HW) block selector 351 and an overhead presetter 352.

[0058] The hardware block selector 351 is configured to selectively enable / disable hardware blocks (logic cells, registers, multipliers, storage devices) used to perform equalization and indicate to the equalizer 360 which hardware blocks are available to perform equalization, thereby reducing energy consumption by disabling hardware blocks that are not required to perform equalization given the estimated channel depth.

[0059] The overhead presetter 352 is configured to indicate to the equalization overhead agent 380 of the receive digital stage RDS 212 what the appropriate size of the equalization resources should be, meaning how many equalization resources should be processed to perform equalization. Consequently, the equalization overhead agent 380 configures the equalizer 360. The equalization overhead agent 380 may also be configured to indicate to the feedback agent 390 what the appropriate size of the equalization resources should be. This allows the feedback agent 390 to inform the transmit digital stage TDS 222 about the appropriate size of the equalization resources, so that the transmit digital stage TDS 222 can adjust the size of the equalization overhead (preamble, cyclic prefix, cyclic suffix) when transmitting an optical signal to the first transceiver optical device T1 111 via the optical line 121. This is particularly applicable when the channel is reciprocal (substantially the same channel in both directions on the optical line 121). This limits the equalization overhead in the direction from the second transceiver optical device T2 112 to the first transceiver optical device T1 111, thereby limiting the use of computational resources and energy consumption. It may further be noted that from the perspective of the first transceiver optical device T1 111, the delay time is improved (e.g., a shortened preamble compared to the worst case). This allows the transmit chain to inform the first transceiver optical device T1 111 about the appropriate size of the equalization resource, so that the first transceiver optical device T1 111 can adjust the size of the equalization overhead (preamble, cyclic prefix, cyclic suffix) when transmitting an optical signal to the second transceiver optical device T2 112 via the optical line 121. This limits the equalization overhead in the direction from the first transceiver optical device T1 111 to the second transceiver optical device T2 112, thereby limiting the use of computational resources and energy consumption.From the perspective of the second transceiver optical device T2 112, it may further be noted that the delay time is improved (eg, a shortened preamble compared to the worst case).

[0060] In the receive digital stage RDS 212, the equalizer 360 includes or is connected to a channel estimator 370. The channel estimator 370 is configured to estimate the response of the optical line 121 so that the equalizer 360 can determine appropriate values ​​for the equalization coefficients (taps in the time domain). The channel estimation can be non-data-aided or data-aided. The channel estimator 370 is further configured to monitor the equalization performance, the rate of change of the channel, and the channel coherence time. The channel coherence time is defined as the duration during which the channel has a constant or monotonic behavior. The channel estimator 370 may also be configured to monitor the signal-to-noise ratio (SNR), which is an indicator of equalization performance.

[0061] The learning agent 310 is configured to receive environmental learning data Env_Ld. The environmental learning data Env_Ld is data related to environmental conditions of the optical line 121. Environmental data such as the environmental learning data Env_Ld is environmental information about physical parameters or derivatives that affect the channels of the optical line 121 and thus cause fluctuations in the channels of the optical line 121, and may include temperature information (as provided by temperature sensors along the optical line 121, potentially at the locations of the first transceiver optical device T1 111 and the second transceiver optical device T2 112), a rate of temperature change (e.g., due to passing clouds), wind strength information, etc. The environmental learning data Env_Ld is time-stamped for processing by the learning agent 310 to appropriately feed into the lookup table 320.

[0062] The learning agent 310 is also configured to receive channel learning data Ch_Ld. The channel learning data Ch_Ld is data related to the channel depth, the rate of change of the channel, and the coherence time of the channel. If several channels are available (e.g., in the case of the first transceiver optical device T1 111 of FIG. 1 for communicating with various transceiver optical devices T2 111, T3 113, and T4 114), the channel learning data Ch_Ld is associated with a channel identifier ChID. The channel learning data Ch_Ld is time-stamped so that it can be processed by the learning agent 310 to appropriately feed into the lookup table 320. The channel learning data Ch_Ld may be provided by the channel estimator 370, as already described.

[0063] The learning agent 310 is configured to associate the channel learning data Ch_Ld and the environment learning data Env_Ld by relying on the timestamp information of the channel learning data Ch_Ld and the timestamp information of the environment learning data Env_Ld matching each other. The associated learning data Ch_Ld and the environment learning data Env_Ld are input into the lookup table 320. Thus, from the environment data considered as Env_tbc, the resource manager 330 can obtain the corresponding channel data, such as channel depth information.

[0064] The channel learning data Ch_Ld and the environmental learning data Env_Ld may be provided by setup. In this case, the channel learning data Ch_Ld and the environmental learning data Env_Ld are time-stamped identically so that they can be associated by the learning agent 310. In a first embodiment, the channel learning data Ch_Ld and the environmental learning data Env_Ld are simulation results. In a second embodiment, the channel learning data Ch_Ld and the environmental learning data Env_Ld are data acquired for other channels having similar deployment conditions of the optical line. For example, if the transceiver optical device T3 113 is located near the second transceiver optical device T2 112, the channel learning data Ch_Ld acquired by the transceiver optical device T3 113 can be used as setup data for the second transceiver optical device T2 112 under the same environmental conditions (i.e., the same environmental learning data Env_Ld).

[0065] The channel learning data Ch_Ld may be provided by the channel estimator 370 by monitoring the operation of the receive chain, more particularly by monitoring the channel response. Thus, once channel data are determined in real-world conditions by the channel estimator 370, these channel data can be used later when similar environmental conditions are met. The corresponding environmental learning data Env_Ld may be provided in real time, for example, by receiving measurements from a sensor or from an environmental data server responsible for collecting environmental measurements for the optical communication system 100.

[0066] Thanks to the learning agent 310's provision of the lookup table 320, the resource manager 330 can obtain an estimate of the channel depth, and potentially other channel-related information, from the environmental data considered as Env_tbc. This allows the resource manager 330 to determine (and potentially anticipate) equalization resource needs in light of the provided environmental data Env_tbc. From the channel depth information contained in the lookup table 320, the resource manager 330 may apply a predetermined depth margin to address potential time variations in the channel characteristics. The depth margin may be fixed or may vary according to a predetermined criterion. Such a predetermined criterion may be the channel coherence time and / or the actual equalization performance (e.g., as indicated by the signal-to-noise ratio (SNR)) and / or the time elapsed since the last update of the actual knowledge of the channel characteristics. In this latter case, more margin is used when the channel coherence time becomes shorter and / or the signal-to-noise ratio deteriorates and / or when a time greater than a predetermined threshold has elapsed since the last update of the actual knowledge of the channel characteristics.

[0067] The resource manager 330 may include or be connected to a scheduler 340 configured to schedule subsequent configuration of equalization resources via the hardware block selector 351 and the overhead presetter 352. This allows for anticipated changes in channel characteristics. For example, the resource manager 330 receives environmental data, considered Env_tbc, which is predicted environmental data (e.g., an impending storm) having time data Time_d (a future point in time). The resource manager 330 can program the scheduler 340 with a predicted channel depth corresponding to the time data. When the scheduler 340 detects that the future point in time in question has been reached, the scheduler 340 is configured to instruct the resource manager 330 to configure the hardware block selector 351 and the overhead presetter 352 according to the predicted channel depth. As previously mentioned, a depth margin can be applied, for example, as a function of the time elapsed since the scheduler 340 was programmed.

[0068] Figure 4 illustrates a schematic representation of an algorithm for selectively enabling equalization resources in accordance with one embodiment of the present invention. The algorithm of Figure 4 is implemented by the receive chain of the transceiver optical device shown in Figure 2, and more specifically, by the receive digital stage RDS 212 thereof. In view of Figure 3, the algorithm of Figure 4 is implemented by the equalization presetter 300.

[0069] In step S401, the transceiver optical device obtains environmental parameter values, which are environmental information about physical parameters or derivatives that affect the channel and thus generate channel fluctuations (such as temperature, vibration, etc.).

[0070] In step S402, the transceiver optical device obtains channel depth information from past experience in consideration of the environmental parameter value. The past experience is preferably the channel depth that the transceiver optical device encounters under the same environmental conditions reflected by the environmental parameter value. The past experience may be obtained by simulation or for another channel having similar deployment conditions of the optical line.

[0071] In step S403, the transceiver optical device selectively enables equalization resources according to the acquired channel depth. The equalization resources are hardware blocks (logic cells, registers, multipliers, storage devices) used to perform equalization. The equalization resources may also be equalization overhead (i.e., cyclic prefixes and / or cyclic suffixes in the frequency domain, or preambles in the time domain).

[0072] Figure 5 illustrates a schematic representation of an algorithm for selectively enabling equalization resources in accordance with a specific embodiment of the present invention. The algorithm of Figure 5 is implemented by the receive chain of the transceiver optical device shown in Figure 2, and more specifically, by the receive digital stage RDS 212 thereof. In view of Figure 3, the algorithm of Figure 5 is implemented by the equalization presetter 300.

[0073] In step S501, the transceiver optical device acquires environmental parameter values ​​(environmental data considered as Env_tbc within the scope of FIG. 3). The environmental parameter values ​​are environmental information about physical parameters or derivatives that affect the channel and thus generate channel fluctuations (temperature, vibration, etc.).

[0074] In step S502, the transceiver optical device searches the lookup table 320 to determine whether the lookup table 320 contains channel-related information associated with an environmental parameter value. The transceiver optical device may search for a particular channel associated with a channel identifier ChID.

[0075] In step S503, the transceiver optical device determines whether such channel-related information is found (potentially for the problematic channel identifier ChID) in the lookup table 320. If found, it means that past experience can be used to pre-configure the equalization resources, and step S506 is executed. If not, it means that the default settings of the equalization resources should be used, and step S504 is executed.

[0076] In step S504, the transceiver optical device defines the channel depth as the worst case. The worst case may be different for each optical line, i.e., for each channel identifier ChID. In fact, the worst case may be more severe, for example, if an optical line includes a longer optical fiber than another optical line.

[0077] In step S505, the transceiver optical device may optionally begin learning to provide channel-related data corresponding to the environmental parameter values ​​(environmental conditions) in question to the look-up table 320. This is particularly true when the environmental parameter values ​​reflect current environmental conditions (not for later scheduling). A specific embodiment is disclosed hereinafter with respect to FIG. 6. Step S508 is then performed.

[0078] In step S506, the transceiver optical device defines the channel depth as indicated in the look-up table 320 in relation to the environmental parameter values ​​obtained in step S501. Thus, past experience is used to estimate the channel depth.

[0079] In step S507, the transceiver optical device preferably adds a depth margin to the channel depth obtained in step S506 from the lookup table 320. Step S508 is then performed. The depth margin allows for addressing potential time variations in channel characteristics and for compensating for some inaccuracy in the channel depth estimation.

[0080] In step S508, the transceiver optical device determines the amount of equalization resources to be used as a function of the channel depth. The equalization resources are hardware blocks (logic cells, registers, multipliers, storage devices) used to perform equalization. The equalization resources may also be equalization overhead (i.e., cyclic prefixes and / or cyclic suffixes in the frequency domain, or preambles in the time domain).

[0081] As already mentioned, various equalization techniques may be used by the transceiver optical device, and for each equalization technique, it is known that there is a deterministic correspondence between the channel depth and the amount of equalization resources (hardware blocks, equalization overhead).

[0082] In step S509, the transceiver optical device uses the determined amount of equalization resources for equalization (on the optical signal received via the optical line 121 for the second transceiver optical device T2 112). In other words, the transceiver optical device selectively enables equalization resources according to the obtained channel depth (potentially for transmission via the channel associated with the channel identifier ChID in question). Thus, the equalization resources in use are defined according to the worst case only if no past experience is recorded in the look-up table 320; otherwise, the equalization resources in use are defined according to said past experience, and thus energy consumption is reduced compared to the worst case.

[0083] It should be noted that the use of equalization resources in step S509 can refer to immediate use, where the environmental parameter values ​​(environmental data considered as Env_tbc within the scope of FIG. 3) reflect current environmental conditions, or future use (via scheduler 340 of FIG. 3) where the environmental parameter values ​​reflect future environmental conditions (associated with time data Time_d within the scope of FIG. 3). In this latter case, the environmental data is predicted environmental data for a future point in time, and the use of equalization resources is scheduled to be enabled when the future point in time in question is reached.

[0084] Figure 6 illustrates a schematic representation of an algorithm for feeding lookup table 320 in a particular embodiment of the present invention. The algorithm of Figure 6 is performed by the receive chain of the transceiver optical device shown in Figure 2, and more specifically by receive digital stage RDS 212 thereof. In view of Figure 3, the algorithm of Figure 6 is performed by equalization presetter 300.

[0085] In step S601, the transceiver optical device receives an optical signal (e.g., via the optical line 121 for the second transceiver optical device T2 112). The optical signal may be received via a channel associated with a channel identifier ChID.

[0086] In step S602, the transceiver optical device determines the equalization coefficients using the actual available equalization resources, so that the channel estimator 370 can monitor the performance of the equalization.

[0087] In step S603, the transceiver optical device determines the highest equalization coefficient and obtains a convergence time for finding the equalization coefficient. The highest equalization coefficient is defined as a coefficient that exceeds a predetermined threshold. The convergence time is the time after which the refinement of the equalization coefficient does not change beyond a predetermined threshold ratio of the magnitude of the coefficient.

[0088] In step S604, the transceiver optical device determines the actual channel depth and time (number of symbols) required to set up the channel equalization, respectively (from the top-order equalization coefficient and convergence time). In fact, the top-order equalization coefficient directly provides the optical signal spreading that should be taken into account so that the symbols of the optical signal can be recovered from consecutive symbols. In addition, the time required to set up the channel equalization directly provides the size of the equalization overhead (size of the preamble / cycle prefix / cyclic suffix).

[0089] In step S605, the transceiver optical device records the channel-related information (channel learning data Ch_Ld in FIG. 3) obtained in step S604 in the lookup table 320. The channel-related information may be associated with a channel identifier ChID. The transceiver optical device timestamps the channel-related information to record the moment at which the channel-related information was obtained.

[0090] In an independent process, in step S611, the transceiver optical device obtains environmental parameter values ​​(environment learning data Env_Ld of the scope in FIG. 3). The environmental parameter values ​​reflect the actual environmental conditions.

[0091] Then, in step S612, the transceiver optical device records the environmental parameter values ​​obtained in step S611 in the look-up table 320. The transceiver optical device timestamps the environmental parameter values ​​to record the moment at which the environmental parameter values ​​were obtained.

[0092] Both steps S605 and S612 are part of a learning phase that allows feeding into the lookup table 320. In step S621, by associating the channel learning data Ch_Ld and the environment learning data Env_Ld with their associated timestamp information, the transceiver optical device knows which channel depths and other channel-related information can be estimated for which environmental conditions.

Claims

1. 1. A method for configuring equalization resources of an equalizer (360) of a transceiver optical device (112), the equalization resources being used by the equalizer (360) to perform equalization on optical signals received over channels of an optical line (121), the method comprising: - a step (S401) of obtaining environmental parameter values, said environmental parameter values ​​being values ​​of environmental data on physical parameters or derivatives affecting said channels of said optical line; obtaining a channel depth estimate from past experience in view of the environmental parameter values ​​(S402); and (S403) selectively enabling the equalization resources to perform equalization on the optical signals received over the channels of the optical line according to the obtained channel depth estimate.

2. To obtain a channel depth estimate from past experience, the method includes: searching (S502) in the lookup table (320) to determine whether the lookup table (320) contains channel-related information associated with the environmental parameter value; if the lookup table (320) contains channel-related information associated with the environmental parameter value, using a channel depth estimate contained in the channel-related information contained in the lookup table (320); and if the lookup table (320) does not contain channel-related information associated with the environmental parameter value, using a channel depth estimate as in the worst case.

3. The lookup table (320) monitoring the equalization performance of the equalizer to determine channel training data; time-stamping the channel learning data; acquiring environmental learning data that reflects actual environmental conditions of the optical fiber line; time-stamping the environmental learning data; The method of claim 2 , wherein the environment learning data and the channel learning data are at least partially populated by associating the environment learning data and the channel learning data using timestamp information.

4. The method of claim 2 or 3, wherein the lookup table (320) is at least partially populated by obtaining training data of other channels having similar deployment conditions of optical lines.

5. adding a predetermined depth margin to the channel depth estimate (S507); The method of claim 1 , further comprising:

6. 6. The method of claim 5, wherein the predetermined depth margin depends on the time of coherence of the channel and / or the actual equalization performance and / or the time elapsed since the last update of the actual knowledge of the characteristics of the channel.

7. 7. The method of claim 1, wherein the equalization resource comprises a hardware block used to perform the equalization on the optical signal received over the channel of the optical line (121).

8. 8. The method of claim 1, wherein the equalization resources include equalization overhead in the optical signal received over the channel of the optical line, and the method comprises transmitting equalization-related information indicating a size of equalization overhead used to transmit the optical signal to another transceiver optical device that transmits the optical signal over the channel of the optical line.

9. 9. The method of claim 8, further comprising: defining a size of an equalization overhead for another optical signal transmitted from the transceiver optical device (112) to the other transceiver optical device (111) according to the obtained channel depth estimate.

10. 10. The method of claim 1, wherein the environmental data is predicted environmental data for a future time point, and the use of the equalization resource is scheduled to be enabled when the future time point in question is reached.

11. 1. A transceiver optical device (112) including an equalizer (360) for performing equalization on optical signals received over channels of an optical line (121), the transceiver optical device (112) being configured to set equalization resources of the equalizer (360), the equalization resources being used by the equalizer (360) to perform equalization on the optical signals received over the channels of the optical line (121), the transceiver optical device (112) being an electronic circuit comprising: Obtaining environmental parameter values ​​(S401), which are values ​​of environmental data for physical parameters or derivatives that affect the channel of the optical line (121); obtaining a channel depth estimate from past experience in view of the environmental parameter values ​​(S402); A transceiver optical device (112) comprising an electronic circuit configured to selectively enable (S403) the equalization resources to perform equalization on the optical signals received via the channels of the optical line (121) according to the obtained channel depth estimate.

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