CN112911424B - Method and device for monitoring multiple paths of different uplink wavelengths by single PD - Google Patents
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- H04Q11/0062—Network aspects
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- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
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Abstract
The invention discloses a method and a device for monitoring multiple paths of different uplink wavelengths by a single PD, and relates to the technical field of WDM-PON access. The method comprises the following steps: when each ONU is transmitted for the first time, determining the transmission starting time T1 according to a random algorithm, calculating the next transmission time T2, and adding T1 and T2 into a modulation signal for transmission; when the data is transmitted subsequently, new T2 is transmitted and calculated according to respective T2 time; when a PD in the OLT receives a modulation signal sent by a certain ONU for the first Time, learning synchronization of demodulation frequency is carried out, T1 and T2 are demodulated, and the Time PD _ Time of the next arrival of the modulation signal is calculated according to T1 and T2; when the PD _ Time Time arrives, the PD replaces the corresponding demodulation frequency to demodulate, and calculates new PD _ Time. The invention can realize the monitoring of the multipath different uplink wavelengths by using the single PD without adding an additional device at the local side, thereby reducing the process difficulty and the hardware cost and meeting the actual application requirement.
Description
Technical Field
The invention relates to the technical field of WDM-PON (Wavelength Division Multiplexing-Passive Optical Network) access, in particular to a method and a device for monitoring multiple paths of different uplink wavelengths by a single PD.
Background
With the advent of 5G technology, the demand of communication networks for transmission bandwidth has increased unprecedentedly, and dense wavelength division systems have been widely used in networks. Among them, the WDM-PON technology is the most commonly used technology for wavelength division multiplexing passive optical networks.
In the WDM-PON application, each ONU (Optical Network Unit) has two uplink and downlink wavelengths to communicate with the OLT, and the uplink and downlink wavelengths between the ONU and the OLT (Optical Line Terminal) are in a one-to-one correspondence and exclusive relationship. In general, WDM-PON is applied in that multiple different wavelengths are converged and superposed by a wavelength division multiplexing multiplexer and then externally led out, and the different wavelengths converged and superposed are separated into corresponding optical modules by the wavelength division multiplexing multiplexer at the OLT end. As shown in fig. 1, in order to monitor the upstream wavelength optical signals of each ONU, it is a common practice that each upstream wavelength is monitored by one PD (photodetector), and N different upstream wavelengths correspond to N PDs for monitoring, but this one-to-one monitoring method not only increases the process difficulty, but also increases the hardware cost. The other monitoring method is a one-to-many mode, that is, one PD monitors the uplink wavelength of multiple channels, but this method usually needs to add multiple micro control units at the PD end to analyze out each low frequency signal, and different frequencies correspond to different uplink wavelengths, thereby realizing multiple monitoring. Since this method requires a plurality of micro control units to be added to the PD side, the hardware cost is also increased.
Therefore, how to implement monitoring on multiple paths of different uplink wavelengths at low cost is an urgent problem to be solved by those skilled in the art.
Disclosure of Invention
The present invention aims to overcome the defects of the background art, and provides a method and a device for monitoring multiple paths of different uplink wavelengths by a single PD, which can realize the monitoring of multiple paths of different uplink wavelengths by using one PD without adding additional devices at the office end, so that the process difficulty and the hardware cost are reduced, and the actual application requirements are met.
In order to achieve the above object, the present invention provides a method for monitoring multiple different upstream wavelengths by a single PD, which is applied in a WDM-PON system, the WDM-PON system including an OLT and multiple ONUs with different wavelengths, wherein the OLT is provided with a PD for monitoring multiple different upstream wavelengths, and the method for monitoring multiple different upstream wavelengths by a single PD includes the following steps:
when each ONU firstly transmits the modulation signal, determining the starting transmission time T1 according to a random algorithm, calculating the next transmission time T2, and adding T1 and T2 into the modulation signal for transmission; during subsequent transmission, each ONU transmits a modulation signal according to respective T2 time, and simultaneously calculates respective new T2;
when a PD in the OLT receives a modulation signal sent by a certain ONU for the first Time, the PD and the ONU carry out learning synchronization of demodulation frequency, T1 and T2 in the modulation signal are demodulated by using the demodulation frequency, and the Time PD _ Time of the next arrival of the modulation signal is calculated according to T1 and T2; when the PD _ Time Time arrives, the PD replaces the current demodulation frequency to the corresponding demodulation frequency of the ONU for demodulation, and calculates out a new PD _ Time.
On the basis of the technical scheme, the method for determining the starting sending time T1 according to a random algorithm specifically comprises the following steps: the transmission frequency and the system current time are used as random seeds, and a random function is adopted to calculate the starting transmission time T1.
On the basis of the technical scheme, when each ONU calculates the next sending time T2, the following calculation formula is adopted:
T2＝T1+△P+△R+△t；
in the formula, Δ P is the time consumed for transmitting a complete modulation signal frame, Δ R is the time required for the modulation signal to reach the PD, and Δ t is the time value calculated by using a random function with the current transmission frequency and the current time as random seeds.
On the basis of the technical scheme, the value of the delta R is an amplified preset empirical value, and the amplified preset empirical value is calculated according to the following formula:
△R＝[(Rmin–Rmax)/(Omax-Omin)]×optRx+Rmax；
wherein Rmin is a preset shortest time, Rmax is a preset longest time, Omax is a preset strongest received optical power, Omin is a preset minimum received optical power, and optRx is a current actual received optical power obtained at any time.
On the basis of the technical scheme, the calculated T1 and T2 meet the following conditions: T2-T1 is more than or equal to the time when the transmission of the whole modulation signal is completed.
On the basis of the above technical solution, the frame structure of the modulation signal sent by each ONU includes: idle field Idle, start bit start, start transmission time T1, next transmission time T2, modulation content, end bit end.
On the basis of the above technical solution, calculating the Time PD _ Time of the next arrival of the modulation signal according to T1 and T2 specifically includes:
calculating the ranging time delta n from the ONU to the PD according to the current time currentTime and the demodulated T1 time, wherein the calculation formula is currentTime-T1;
and calculating the Time PD _ Time of the next arrival of the modulation signal according to the ranging Time delta n and the demodulated T2 Time, wherein the calculation formula is that PD _ Time is T2+ delta n.
On the basis of the above technical solution, after calculating the Time PD _ Time of the next arrival of the modulation signal according to T1 and T2, the method specifically includes the following operations:
the PD judges whether the calculated PD _ Time Time of the current ONU generates signal collision or not according to the PD _ Time Time of other ONUs, if so, when the calculated PD _ Time Time of the current ONU arrives, the signal with collision is discarded, and demodulation is not carried out;
otherwise, when the calculated PD _ Time Time of the current ONU arrives, the current demodulation frequency is replaced to be the demodulation frequency corresponding to the ONU for demodulation, whether error codes occur is judged, and if yes, the learning synchronization of the new demodulation frequency and the analysis of the modulation signal are carried out again; if not, calculating the new PD _ Time of the ONU.
On the basis of the above technical solution, when a PD in the OLT initially receives a modulation signal sent from a certain ONU, the method further includes the following operations: and the PD and the ONU carry out time correction and synchronize the system time of the PD and the ONU.
The invention also provides a device for monitoring multiple paths of different uplink wavelengths by a single PD based on the method, which comprises an OLT and multiple paths of ONUs (optical network units) which are communicated with the OLT and have different wavelengths;
a time calculation module and a signal sending module are arranged in the ONU; the time calculation module is configured to: when the modulation signal is transmitted for the first time, determining the starting transmission time T1 according to a random algorithm, and calculating the next transmission time T2; when in subsequent transmission, calculating new next transmission time T2; the signal sending module is configured to: when the transmission time arrives, adding T1 and T2 into the modulation signal for transmission;
the OLT is internally provided with a PD for monitoring multiple paths of different uplink wavelengths, and the PD comprises a demodulation frequency learning synchronization module and a demodulation processing module; the demodulation frequency learning synchronization module is configured to: when a modulation signal sent by a certain ONU is received for the first time, the demodulation frequency is learned and synchronized with the ONU; the demodulation processing module is configured to: when a modulation signal sent by a certain ONU is received for the first Time, demodulating T1 and T2 in the modulation signal by using the demodulation frequency synchronized by learning, and calculating the Time PD _ Time of the next arrival of the modulation signal according to T1 and T2; and when the PD _ Time comes, the current demodulation frequency is replaced to be the demodulation frequency corresponding to the ONU for demodulation, and a new PD _ Time is calculated.
The invention has the beneficial effects that:
in the invention, when each ONU sends a modulation signal, the starting sending time T1 and the calculated next sending time T2 are added into the modulation signal together and sent to the OLT; the PD in the OLT can calculate the time of the next arrival of the modulation signal according to the T1 and the T2 in the modulation signal; when the modulation signal comes next time, the PD can timely replace the current demodulation frequency with the corresponding demodulation frequency of the ONU which is learned and synchronized in advance for demodulation, so that the PD can demodulate the modulation signals with different demodulation frequencies, and the purpose that one PD monitors a plurality of paths of ONU optical signals with different uplink wavelengths is further realized.
Compared with the prior art, the invention can monitor the optical signals of the ONU with the plurality of different uplink wavelengths by using one PD, and can distinguish different modulation signals without adding an additional device at a local side or a wavelength division multiplexing multiplexer side, thereby completing the monitoring and management of the optical signals with the plurality of different uplink wavelengths.
Drawings
Fig. 1 is a diagram illustrating an application networking of a conventional WDM-PON system;
fig. 2 is a system networking diagram of a single PD monitoring multiple different uplink wavelengths in an embodiment of the present invention;
fig. 3 is a flowchart of a method for monitoring multiple different uplink wavelengths by a single PD according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a frame format of a modulated signal transmitted by an ONU in the embodiment of the present invention;
fig. 5 is a schematic diagram of the time when each ONU-modulated signal reaches the PD according to the embodiment of the present invention.
Detailed Description
The method aims at solving the problems of high process difficulty and high hardware cost in the prior art by adopting a method of respectively monitoring N paths of different uplink wavelengths by N PDs; however, the method of monitoring different wavelengths of multiple channels by using one PD also has the problem of high hardware cost because a plurality of micro control units need to be added at the PD end. The invention aims to provide a method and a device for monitoring multiple paths of different uplink wavelengths by using a single PD (photo-detector), which can realize the monitoring of the multiple paths of different uplink wavelengths by using one PD on the premise of not increasing additional devices, not only has low process difficulty, but also can reduce hardware cost and meet the requirement of practical application.
The main design concept is as follows: when each ONU firstly transmits a modulation signal, determining the starting transmission time T1 according to a random algorithm, and calculating the next transmission time T2; adding T1 and T2 into the modulation signal for transmission; during subsequent transmission, each ONU transmits a modulation signal according to respective T2 time, and simultaneously calculates respective new T2;
when a PD in the OLT receives a modulation signal sent by a certain ONU for the first Time, the PD and the ONU carry out learning synchronization of demodulation frequency, T1 and T2 in the modulation signal are demodulated by using the demodulation frequency, and the Time PD _ Time of the next arrival of the modulation signal is calculated according to T1 and T2; when the calculated PD _ Time Time arrives, the PD replaces the current demodulation frequency to the corresponding demodulation frequency of the ONU for demodulation, and calculates a new PD _ Time.
In the scheme, when each ONU sends the modulation signal, the starting sending time T1 and the calculated next sending time T2 are added into the modulation signal together and sent to the OLT; the PD in the OLT can calculate the Time PD _ Time of the next arrival of the modulation signal according to T1 and T2 in the modulation signal; when the modulation signal comes next time, the PD can timely replace the current demodulation frequency with the corresponding demodulation frequency of the ONU which is learned and synchronized in advance for demodulation, so that the PD can demodulate the modulation signals with different demodulation frequencies, and the purpose that one PD monitors a plurality of paths of ONU optical signals with different uplink wavelengths is further realized. By using the method of the scheme, different modulation signals can be distinguished without adding additional devices such as a microcontroller and the like at a local side or a wavelength division multiplexing multiplexer side, so that monitoring and management of multiple paths of optical signals with different uplink wavelengths are completed.
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.
However, it should be noted that: the examples to be described next are only some specific examples, and are not intended to limit the embodiments of the present invention necessarily to the following specific steps, values, conditions, data, orders, and the like. Those skilled in the art can, upon reading this specification, utilize the concepts of the present invention to construct more embodiments than those specifically described herein.
Example one
The embodiment provides a method for monitoring multiple paths of different uplink wavelengths by a single PD, which is applied to a WDM-PON system, where the WDM-PON system includes an OLT and multiple paths of ONUs with different wavelengths, where each ONU has two uplink and downlink wavelengths to communicate with the OLT. Referring to fig. 2, in practical application, optical signals of each ONU are superimposed by an external wavelength division multiplexing multiplexer and then transmitted to the OLT; the OLT distinguishes the superposed optical signals with different wavelengths through an internal wavelength division multiplexing wave combiner and transmits the superposed optical signals to the uplink optical modules corresponding to the ONU. In this embodiment, the OLT is further provided with a PD for monitoring multiple paths of different uplink wavelengths, and the method for monitoring multiple paths of different uplink wavelengths by a single PD specifically includes the following steps, as shown in fig. 3:
step A, when each ONU sends a modulation signal for the first time, determining the starting sending time T1 according to a random algorithm, and calculating the next sending time T2; adding T1 and T2 into the modulation signal for transmission; in the subsequent transmission, each ONU transmits a modulated signal at a time T2, and calculates a new time T2.
It can be understood that since multiple ONUs with different wavelengths are connected to different fiber channels (channels, hereinafter referred to as "ch") of an external wdm multiplexer, when each ONU is connected to different ch, the frequency of the transmitted modulation signal should be different (may be different by human design). That is, in this embodiment, ONUs with different wavelengths transmit modulation signals with different frequencies.
Although ONUs with different wavelengths can send modulation signals with different frequencies, in practical application, the frame structures of the modulation signals sent by the ONUs can be designed to be the same, so that the subsequent PDs can perform analysis operation conveniently; and, the modulation information coding sent can adopt redundant codes, such as Hamming codes, and can correct errors in time when demodulating. Specifically, as an alternative implementation, referring to fig. 4, a frame structure of a modulation signal transmitted by each ONU includes:
idle: a free field, which is used as a redundant field and can be discarded;
and (3) start: is a start bit;
t1: to start the transmission time; when the transmission is the initial transmission, the T1 value is determined according to a random algorithm, and when the transmission is the non-initial transmission, the T1 value is the next transmission time T2 calculated when the transmission is the last time;
t2: the calculated next sending time;
modulation content: is the information content to be transmitted;
end: an end bit. The order of the Idle field, the start field and the end field is fixed, and the order of other fields is adjustable.
In addition, it can be understood that, in order to ensure that the modulation signal can be transmitted completely, T1 and T2 need to satisfy the following conditions: T2-T1 is more than or equal to the time when the transmission of the whole modulation signal is completed, i.e. the time difference between T2 and T1 is calculated to be at least larger than the time when the transmission of the whole modulation signal is completed.
Further, as an optional implementation manner, in step a, determining the transmission start time T1 according to a random algorithm specifically includes the following operations: the transmission frequency and the system current time are used as random seeds, and a random function is adopted to calculate the starting transmission time T1. For example, taking the example of seeding the random number generator used by the function rand with the void srand (unknown int seed) function in C language, taking the current time and the frequency of the transmitted modulation signal as random seeds, the operation is as follows: srand ((signaled) time (null) + transmission frequency); where time () is the resulting current system time. Then, a random function rand is adopted for calculation, and then the sending time is rand ()% 101+ the current system time; wherein rand ()% 101 is random number of 0-100, unit is millisecond. It can be understood that, in this embodiment, when the start transmission time T1 when each ONU transmits the modulation signal for the first time is determined, a random algorithm is adopted, and the transmission frequency and the current time of the system are used as random seeds to increase the randomness of the modulation signal, so that more than two ONUs avoid transmitting the modulation signal at the same time as much as possible, thereby avoiding the occurrence of signal collision during the initial transmission process, and ensuring the accuracy and effectiveness of subsequent PD analysis.
Furthermore, since the frequency of the transmission modulation signal of each ONU is fast and slow, and collision of multiple signals is inevitably generated after a long time, it is necessary to avoid that two or more ONUs transmit modulation signals at the same time in the initial transmission process, and it is necessary to avoid that two or more ONUs transmit modulation signals at the same time in the subsequent transmission process as much as possible. Therefore, as a preferred embodiment, when each ONU calculates the next transmission time T2, the following calculation formula is used:
T2＝T1+△P+△R+△t；
wherein, Δ P: the time consumed for transmitting the complete modulation signal frame can be calculated according to the transmitted frequency and the number of bytes;
Δ R: the time required for the modulated signal to reach the PD, namely the ranging time value from the ONU to the OLT; ideally, the value of Δ R is an actual time required by the modulation signal to reach the PD, but since the actual time value is too small and can be ignored with respect to a time required for sending a complete modulation signal frame (in practice, since the light speed is fast, the ranging time value from the ONU to the OLT is small, usually in a nanometer scale, and can be almost ignored), if the actual time value is used as a random seed, the randomness influence is not large, and therefore, in practical application, the value of Δ R is an amplified preset empirical value to increase the randomness of the T2 time;
more specifically, in this embodiment, the time value for ranging is determined according to the intensity of the optical power, and the stronger the optical power, the smaller the time value for ranging is; and the amplified preset empirical value is calculated according to a calculation formula of ═ DeltaR [ (Rmin-Rmax)/(Omax-Omin) ] × optRx + Rmax; wherein Rmin is a preset shortest time (usually preset to 1ms), Rmax is a preset longest time (usually preset to 10ms), Omax is a preset strongest received optical power, Omin is a preset minimum received optical power, and optRx is a current actual received optical power obtained at any time;
Δ t: taking the current sending frequency and the current moment as random seeds, and adopting a random function to calculate a time value; the Δ T is also to increase the randomness of the time T2 and avoid collision of the transmission time.
When the PD in step B, OLT receives the modulation signal sent by an ONU for the first Time, the PD performs learning synchronization of demodulation frequency with the ONU, demodulates T1 and T2 in the modulation signal by using the demodulation frequency, and calculates the Time PD _ Time of the next arrival of the modulation signal according to T1 and T2; when the calculated PD _ Time Time arrives, the PD replaces the current demodulation frequency to the corresponding demodulation frequency of the ONU for demodulation, and calculates a new PD _ Time.
It can be understood that, whenever a PD in the OLT receives a modulation signal sent by a certain ONU for the first time, the PD performs a learning synchronization process of a demodulation frequency (clock frequency) with the ONU, so that a sampling demodulation frequency (clock frequency) of the PD matches with a frequency of a received ONU optical signal, and records a corresponding demodulation frequency of the ONU, so that the next time the modulation signal of the ONU arrives, the PD can be replaced with the corresponding demodulation frequency for demodulation, so that one PD can demodulate modulation signals of different demodulation frequencies, and further, the purpose that one PD monitors multiple ONU optical signals of different uplink wavelengths is achieved. More preferably, in order to ensure that the time used between the OLT and each ONU is the same and thus ensure the accuracy of time calculation, each time the PD in the OLT initially receives a modulated signal from a certain ONU, the PD also performs timing with the ONU and synchronizes the system time of the two ONUs.
Further, as a preferred implementation manner, in step B of this embodiment, the Time PD _ Time of the next arrival of the modulation signal is calculated according to T1 and T2, and the specific process includes:
(1) calculating the ranging time delta n from the ONU to the PD according to the current time currentTime and the demodulated T1 time, wherein the calculation formula is currentTime-T1;
(2) and calculating the Time PD _ Time of the next arrival of the modulation signal according to the ranging Time delta n and the demodulated T2 Time, wherein the calculation formula is that PD _ Time is T2+ delta n. For example, the Time PD _ Time when the modulation signal of each ONU reaches the PD is shown in fig. 5.
Further, although the way of calculating T1 and T2 in step a is adopted, it has been largely avoided that more than two ONUs transmit modulated signals at the same time, preventing collision of multiple signals. However, in practical applications, since the transmission frequency and the optical power of each ONU are set to be different, it is inevitable that signal collision occurs after a long time. Besides the collision problem, in practical application, errors may occur during demodulation, and for the reason of the errors, collision may occur in multiple signals, or a modulated signal with an unknown new frequency may come in the current system. Therefore, in order to better deal with the problems of collision and error, as a preferred embodiment, the step B of this embodiment specifically includes the following operations after calculating the Time PD _ Time when the next modulated signal arrives:
according to the calculated PD _ Time Time of other ONUs, judging whether the calculated PD _ Time Time of the current ONU generates signal collision or not (if the PD _ Time of other ONUs is the same as the PD _ Time of the current ONU, the PD _ Time Time is considered to generate signal collision), if so, discarding the collision signal when the calculated PD _ Time Time of the current ONU arrives, and not demodulating;
otherwise, the PD will change the current demodulation frequency to the corresponding demodulation frequency of the ONU for demodulation, and judge whether the error code occurs, if yes, consider the unknown new frequency modulation signal access, will re-execute step B, carry on the new demodulation frequency study synchronization and modulation signal analysis; if not, monitoring of the optical signal sent by the ONU is realized, and a new PD _ Time is calculated for continuous monitoring in the following.
As can be seen from the above steps a and B, when each ONU transmits a modulation signal in this embodiment, the transmission start time T1 and the calculated next transmission time T2 are added to the modulation signal together and transmitted to the OLT; the PD in the OLT can calculate the Time PD _ Time of the next arrival of the modulation signal according to T1 and T2 in the modulation signal; when the modulation signal comes next time, the PD can timely replace the current demodulation frequency with the corresponding demodulation frequency of the ONU which is learned and synchronized in advance for demodulation, so that the PD can demodulate the modulation signals with different demodulation frequencies, and the purpose that one PD monitors a plurality of paths of ONU optical signals with different uplink wavelengths is further realized. In addition, in the embodiment, by designing the calculation modes of T1 and T2, it is avoided that more than two ONUs transmit modulation signals at the same time to a great extent, and collision of multiple signals is prevented; moreover, the method can well process the situations of signal collision, error code generation and the like, so that the reliability and the applicability of the method are further improved, and the actual use requirement is met.
Example two
Based on the same inventive concept, the embodiment of the invention also provides a device for monitoring multiple paths of different uplink wavelengths by a single PD based on the method, which comprises an OLT and multiple paths of ONUs (optical network units) which are communicated with the OLT and have different wavelengths.
The ONU is provided with a time calculation module and a signal transmission module. A time calculation module to: when the modulation signal is transmitted for the first time, determining the starting transmission time T1 according to a random algorithm, and calculating the next transmission time T2; at the time of subsequent transmission, a new next transmission time T2 is calculated. A signal sending module for: when the transmission time (T1 or T2) arrives, T1 and T2 are added to the modulated signal for transmission.
And a PD for monitoring multiple paths of different uplink wavelengths is arranged in the OLT, and the PD comprises a demodulation frequency learning synchronization module and a demodulation processing module. A demodulation frequency learning synchronization module to: when a modulation signal sent by a certain ONU is received for the first time, the demodulation frequency is learned and synchronized with the ONU. A demodulation processing module for: when a modulation signal sent by a certain ONU is received for the first Time, demodulating T1 and T2 in the modulation signal by using the demodulation frequency synchronized by learning, and calculating the Time PD _ Time of the next arrival of the modulation signal according to T1 and T2; and when the PD _ Time comes, the current demodulation frequency is replaced to be the demodulation frequency corresponding to the ONU for demodulation, and a new PD _ Time is calculated.
It should be noted that various changes and specific examples in the foregoing method embodiments are also applicable to the apparatus of the present embodiment, and the detailed description of the foregoing method is clear to those skilled in the art, so that the detailed description is omitted here for the sake of brevity.
Note that: the above-described embodiments are merely examples and are not intended to be limiting, and those skilled in the art can combine and combine some steps and devices from the above-described separately embodiments to achieve the effects of the present invention according to the concept of the present invention, and such combined and combined embodiments are also included in the present invention, and such combined and combined embodiments are not described herein separately.
Advantages, effects, and the like, which are mentioned in the embodiments of the present invention, are only examples and are not limiting, and they cannot be considered as necessarily possessed by the various embodiments of the present invention. Furthermore, the foregoing specific details disclosed herein are merely for purposes of example and for purposes of clarity of understanding, and are not intended to limit the embodiments of the invention to the particular details which may be employed to practice the embodiments of the invention.
The block diagrams of devices, apparatuses, systems involved in the embodiments of the present invention are only given as illustrative examples, and are not intended to require or imply that the connections, arrangements, configurations, etc. must be made in the manner shown in the block diagrams. These devices, apparatuses, devices, systems may be connected, arranged, configured in any manner, as will be appreciated by those skilled in the art. Words such as "including," "comprising," "having," and the like are open-ended words that mean "including, but not limited to," and are used interchangeably therewith. As used in connection with embodiments of the present invention, the terms "or" and "refer to the term" and/or "and are used interchangeably herein unless the context clearly dictates otherwise. The word "such as" is used in connection with embodiments of the present invention to mean, and is used interchangeably with, the word "such as but not limited to".
The flow charts of steps in the embodiments of the present invention and the above description of the methods are merely illustrative examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order presented. As will be appreciated by those skilled in the art, the order of the steps in the above embodiments may be performed in any order. Words such as "thereafter," "then," "next," etc. are not intended to limit the order of the steps; these words are only used to guide the reader through the description of these methods. Furthermore, any reference to an element in the singular, for example, using the articles "a," "an," or "the" is not to be construed as limiting the element to the singular.
In addition, the steps and devices in the embodiments of the present invention are not limited to be implemented in a certain embodiment, and in fact, some steps and devices in the embodiments of the present invention may be combined according to the concept of the present invention to conceive new embodiments, and these new embodiments are also included in the scope of the present invention.
The respective operations in the embodiments of the present invention may be performed by any appropriate means capable of performing the corresponding functions. The means may comprise various hardware and/or software components and/or modules including, but not limited to, hardware circuitry or a processor.
The method of an embodiment of the invention includes one or more acts for implementing the method described above. The methods and/or acts may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of actions is specified, the order and/or use of specific actions may be modified without departing from the scope of the claims.
The functions in the embodiments of the present invention may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions on a tangible computer-readable medium. A storage media may be any available tangible media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other tangible medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. As used herein, disk (disk) and Disc (Disc) include Compact Disc (CD), laser Disc, optical Disc, DVD (Digital Versatile Disc), floppy disk and blu-ray Disc where disks reproduce data magnetically, while discs reproduce data optically with lasers.
Accordingly, a computer program product may perform the operations presented herein. For example, such a computer program product may be a computer-readable tangible medium having instructions stored (and/or encoded) thereon that are executable by one or more processors to perform the operations described herein. The computer program product may include packaged material.
Other examples and implementations are within the scope and spirit of the embodiments of the invention and the following claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hard-wired, or any combination of these. Features implementing functions may also be physically located at various locations, including being distributed such that portions of functions are implemented at different physical locations.
Various changes, substitutions and alterations to the techniques described herein may be made by those skilled in the art without departing from the techniques of the teachings as defined by the appended claims. Moreover, the scope of the claims of the present disclosure is not limited to the particular aspects of the process, machine, manufacture, composition of matter, means, methods and acts described above. Processes, machines, manufacture, compositions of matter, means, methods, or acts, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or acts.
The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing description has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit embodiments of the invention to the form disclosed herein. While a number of example aspects and embodiments have been discussed above, those of skill in the art will recognize certain variations, modifications, alterations, additions and sub-combinations thereof. And those not described in detail in this specification are within the skill of the art.
Claims (10)
1. A method for monitoring multiple paths of different uplink wavelengths by a single PD is applied to a WDM-PON system, the WDM-PON system comprises an OLT and multiple paths of ONUs with different wavelengths, the ONU is communicated with the OLT, a PD for monitoring the multiple paths of different uplink wavelengths is arranged in the OLT, and the method for monitoring the multiple paths of different uplink wavelengths by the single PD comprises the following steps:
when each ONU firstly transmits the modulation signal, determining the starting transmission time T1 according to a random algorithm, calculating the next transmission time T2, and adding T1 and T2 into the modulation signal for transmission; during subsequent transmission, each ONU transmits a modulation signal according to respective T2 time, and simultaneously calculates respective new T2;
when a PD in the OLT receives a modulation signal sent by a certain ONU for the first Time, the PD and the ONU carry out learning synchronization of demodulation frequency, T1 and T2 in the modulation signal are demodulated by using the demodulation frequency, and the Time PD _ Time of the next arrival of the modulation signal is calculated according to T1 and T2; when the PD _ Time Time arrives, the PD replaces the current demodulation frequency to the corresponding demodulation frequency of the ONU for demodulation, and calculates out a new PD _ Time.
2. The method for monitoring multiple different uplink wavelengths by a single PD according to claim 1, wherein the determining the transmission start time T1 according to a random algorithm specifically includes:
the transmission frequency and the system current time are used as random seeds, and a random function is adopted to calculate the starting transmission time T1.
3. The method of claim 1, wherein each ONU calculates the next transmission time T2 according to the following calculation formula:
T2＝T1+△P+△R+△t；
in the formula, Δ P is the time consumed for transmitting a complete modulation signal frame, Δ R is the time required for the modulation signal to reach the PD, and Δ t is the time value calculated by using a random function with the current transmission frequency and the current time as random seeds.
4. The method for monitoring multiple different uplink wavelengths by a single PD according to claim 3, wherein Δ R is an amplified predetermined empirical value, and the amplified predetermined empirical value is calculated according to the following formula:
△R＝[(Rmin–Rmax)/(Omax-Omin)]×optRx+Rmax；
wherein Rmin is a preset shortest time, Rmax is a preset longest time, Omax is a preset strongest received optical power, Omin is a preset minimum received optical power, and optRx is a current actual received optical power obtained at any time.
5. The method of claim 1, wherein the calculated T1, T2 satisfies the following condition: T2-T1 is more than or equal to the time when the transmission of the whole modulation signal is completed.
6. The method of claim 1, wherein the frame structure of the modulated signal transmitted by each ONU comprises: idle field Idle, start bit start, start transmission time T1, next transmission time T2, modulation content, end bit end.
7. The method of claim 1, wherein the calculating the next Time PD _ Time of arrival of the modulation signal according to T1 and T2 comprises:
calculating the ranging time delta n from the ONU to the PD according to the current time currentTime and the demodulated T1 time, wherein the calculation formula is currentTime-T1;
and calculating the Time PD _ Time of the next arrival of the modulation signal according to the ranging Time delta n and the demodulated T2 Time, wherein the calculation formula is that PD _ Time is T2+ delta n.
8. The method of claim 1, wherein the following operation is specifically included after calculating the next Time PD _ Time of arrival of the modulation signal according to T1 and T2:
the PD judges whether the calculated PD _ Time Time of the current ONU generates signal collision or not according to the PD _ Time Time of other ONUs, if so, when the calculated PD _ Time Time of the current ONU arrives, the signal with collision is discarded, and demodulation is not carried out;
otherwise, when the calculated PD _ Time Time of the current ONU arrives, the current demodulation frequency is replaced to be the demodulation frequency corresponding to the ONU for demodulation, whether error codes occur is judged, and if yes, the learning synchronization of the new demodulation frequency and the analysis of the modulation signal are carried out again; if not, calculating the new PD _ Time of the ONU.
9. The method of claim 1, wherein the PD in the OLT further receives a modulation signal from an ONU for the first time, and further comprising the following operations: and the PD and the ONU carry out time correction and synchronize the system time of the PD and the ONU.
10. An apparatus for monitoring multiple different upstream wavelengths by a single PD based on the method of any one of claims 1-9, comprising an OLT and multiple different wavelength ONUs in communication with the OLT, wherein: the ONU is provided with a time calculation module and a signal transmission module;
the time calculation module is configured to: when the modulation signal is transmitted for the first time, determining the starting transmission time T1 according to a random algorithm, and calculating the next transmission time T2; when in subsequent transmission, calculating new next transmission time T2;
the signal sending module is configured to: when the transmission time arrives, adding T1 and T2 into the modulation signal for transmission;
the OLT is internally provided with a PD for monitoring multiple paths of different uplink wavelengths, and the PD comprises a demodulation frequency learning synchronization module and a demodulation processing module;
the demodulation frequency learning synchronization module is configured to: when a modulation signal sent by a certain ONU is received for the first time, the demodulation frequency is learned and synchronized with the ONU;
the demodulation processing module is configured to: when a modulation signal sent by a certain ONU is received for the first Time, demodulating T1 and T2 in the modulation signal by using the demodulation frequency synchronized by learning, and calculating the Time PD _ Time of the next arrival of the modulation signal according to T1 and T2; and when the PD _ Time comes, the current demodulation frequency is replaced to be the demodulation frequency corresponding to the ONU for demodulation, and a new PD _ Time is calculated.
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