CN113316036B - Dynamic wavelength bandwidth allocation method - Google Patents

Dynamic wavelength bandwidth allocation method Download PDF

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Publication number
CN113316036B
CN113316036B CN202110401360.2A CN202110401360A CN113316036B CN 113316036 B CN113316036 B CN 113316036B CN 202110401360 A CN202110401360 A CN 202110401360A CN 113316036 B CN113316036 B CN 113316036B
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onu
time
determining
preemption
retransmission
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CN113316036A (en
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张佳玮
刘笑竹
纪越峰
梁明慧
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Beijing University of Posts and Telecommunications
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Beijing University of Posts and Telecommunications
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q11/0067—Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0086—Network resource allocation, dimensioning or optimisation

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Abstract

The invention provides a dynamic wavelength bandwidth allocation method, which is applied to a time division wavelength division multiplexing passive optical network (TWDM-PON), wherein the TWDM-PON comprises an Optical Line Terminal (OLT) and a plurality of Optical Network Units (ONU), the ONU which is seized and the ONU which is seized are determined, and the seizing time and the retransmission time are determined, so that the ONU which is seized transmits fronthaul service at the seizing time, and the ONU which is seized retransmits the service which occupies bandwidth resources at the retransmission time.

Description

Dynamic wavelength bandwidth allocation method
Technical Field
The present disclosure relates to the field of electronic information technologies, and in particular, to a dynamic wavelength bandwidth allocation method.
Background
In the scenario of convergence of fixed and mobile networks, two DWBAs (wavelength bandwidth allocation), SR-DWBA and CO-DWBA, are usually combined to meet different traffic (fixed and mobile) requirements.
In the same TWDM-PON (time and wavelength division multiplexed passive optical network) system, effective cooperation of two DWBA schemes is very important, and the cooperation is related to the DWBA cycle. The SR-DWBA period is influenced by the PON transmission distance and the number of the ONUs and is generally not less than 1 ms. And the period of the CO-DWBA is related to the radio frame length. In a 4G LTE network, the frame length/frame period, also called TTI, is 1 ms. The UE may obtain the wireless bandwidth grant information 4 TTIs (4ms) in advance. As can be seen from the above description, the OLT also obtains uplink data information 4ms in advance, and allocates uplink bandwidth in the PON in advance. Since 4ms is larger than the period of SR-DBWA, there is no allocation conflict for 4G forward traffic.
However, 3GPP defines a new air interface (5G NR) of a 5G mobile network, and proposes a mini-slot concept, which is similar to the TTI concept in LTE and represents a basic frame structure and a scheduling period in a wireless network. The mini-slots specify more subcarrier spacings, e.g., 15, 30 and 60kHz, and fewer OFDM symbol numbers, e.g., 2, 4, 7. The length of the mini-slot is smaller than that of the LTE TTI (1ms), and the method is more suitable for 5G low-delay service.
The correlation technology is carried out under the condition that the TTI length is 1ms in a 4G network, because the mini-slot shortening is provided in the 5G NR, the wireless scheduling period of the CO-DWBA in the original scheme is not matched with the SR-DWBA polling authorization period, the OLT only receives the mobile scheduling information of part of the mobile data within the period length (1ms) when authorizing the FTTH, and the subsequent mobile data has no predictability, so that no idle wavelength bandwidth resource can be distributed in the OLT to generate extra waiting time delay, and the requirement of low-time-delay transmission time delay of the mobile forward-transmission service cannot be met. That is, the wavelength bandwidth allocation scheme in the related art causes too high transmission delay of the forwarding traffic.
Disclosure of Invention
In view of the above, the present disclosure is directed to a dynamic wavelength bandwidth allocation method.
Based on the above object, the present disclosure provides a dynamic wavelength bandwidth allocation method, wherein the method is applied to a time division wavelength division multiplexing passive optical network TWDM-PON; the TWDM-PON comprises an optical line terminal OLT and a plurality of optical network units ONU; the OLT is connected with a plurality of ONU; the TWDM-PON comprises a plurality of wavelengths for transmitting service information;
the method comprises the following steps:
the OLT determines a first ONU and a second ONU; the second ONU is the ONU which is allocated with bandwidth corresponding to any wavelength; the first ONU is the ONU which is to preempt the bandwidth of the wavelength distributed by the second ONU;
the OLT determines a preemption moment and a retransmission moment;
the OLT generates a preemption instruction according to the preemption moment and sends the preemption instruction to the first ONU; the preemption instruction is used for enabling the first ONU to carry out service transmission at the preemption moment;
the OLT generates a retransmission instruction according to the retransmission moment and sends the retransmission instruction to the second ONU; and the retransmission instruction is used for enabling the second ONU to carry out service transmission at the retransmission moment.
As can be seen from the above description, the dynamic wavelength bandwidth allocation method provided by the present disclosure is applied to a time division wavelength division multiplexing passive optical network TWDM-PON, where the TWDM-PON includes an optical line terminal OLT and a plurality of optical network units ONU, and the preempted ONU are determined, and the preemption time and the retransmission time are determined, so that the preempted ONU preempts the fronthaul service at the time, and the preempted ONU retransmits the service occupying the bandwidth resource at the retransmission time, and by using the preemptive wavelength bandwidth allocation method, the transmission delay of the fronthaul service is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the present disclosure or related technologies, the drawings needed to be used in the description of the embodiments or related technologies are briefly introduced below, and it is obvious that the drawings in the following description are only embodiments of the present disclosure, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic diagram of a fused DWBA scheme in the related art provided by an embodiment of the present disclosure;
FIG. 2 is a schematic diagram illustrating that a mini-slot provided in an embodiment of the present disclosure causes bandwidth allocation in a CO-DWBA and SR-DWBA fusion scheme in the related art to conflict;
fig. 3 is a schematic flow chart of a dynamic wavelength bandwidth allocation method according to an embodiment of the present disclosure;
fig. 4 is a schematic view of a scenario of a dynamic wavelength bandwidth allocation method according to an embodiment of the present disclosure;
fig. 5 is a flowchart illustrating a method for determining a second ONU according to an embodiment of the present disclosure;
fig. 6 is a flowchart illustrating a method for determining a third ONU according to an embodiment of the present disclosure;
fig. 7 is a more specific scenario diagram of a dynamic wavelength bandwidth allocation method according to an embodiment of the present disclosure;
fig. 8 is a schematic flowchart illustrating that a first ONU performs preemption according to an embodiment of the present disclosure;
fig. 9 is a flowchart illustrating that the second ONU performs retransmission according to an embodiment of the present disclosure.
Detailed Description
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
It is to be noted that technical terms or scientific terms used in the embodiments of the present disclosure should have a general meaning as understood by those having ordinary skill in the art to which the present disclosure belongs, unless otherwise defined. The use of "first," "second," and similar terms in the embodiments of the disclosure is not intended to indicate any order, quantity, or importance, but rather to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used only to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
The patent is directed to a time and wavelength division multiplexing passive optical network (TWDM-PON) system under a scene of convergence of fixed and mobile networks. The TWDM-PON comprises an Optical Line Terminal (OLT) and a plurality of Optical Network Units (ONU), wherein the OLT is connected with the ONU. The TWDM-PON has 4 wavelengths to transmit in the up and down directions; the OLT has a receiver/transmitter capable of receiving and transmitting a plurality of wavelengths; the ONU has a tunable transmitter that can modulate to any 1 of the 4 wavelengths upstream and a tunable receiver that can receive any 1 of the 4 wavelengths downstream.
A Dynamic Wavelength Bandwidth Allocation (DWBA) method in the related art is divided into a low delay scheme and a high bandwidth utilization scheme. For fixed access service, the traditional dynamic wavelength bandwidth allocation scheme (SR-DWBA) based on request authorization is mainly adopted, that is, polling periods are divided in the uplink transmission process, the ONU requests uplink bandwidth to the OLT according to the cache data in each period, and after the OLT collects the bandwidth requests of all ONUs, the uniform authorization is performed in the next round of training periods. The mechanism based on 'request-authorization' can effectively improve the utilization efficiency of the bandwidth in the PON. And aiming at the mobile access service, adopting a dynamic wavelength bandwidth allocation scheme (CO-DWBA) based on cooperation. The principle is that information interaction is introduced between a mobile processing unit (CU/DU) and an OLT (optical line terminal), and wireless and optical cooperation is realized, namely, in each wireless scheduling period (TTI), the CU/DU sends wireless bandwidth authorization information to mobile user UE (user equipment) and simultaneously sends corresponding information to the OLT. In this way, the OLT may obtain upstream bandwidth information of a mobile ONU (an ONU connected to the mobile base station, called a mobile ONU) in advance, and grant the upstream bandwidth of the mobile ONU based on the information. The scheme can greatly reduce the signaling transmission time delay required by the request-authorization of the SR-DWBA and meet the requirement of mobile forward transmission on low time delay.
In fixed and mobile network convergence scenarios, two DWBAs (SR-DWBA and CO-DWBA) are often combined to meet different traffic (fixed and mobile) requirements. In the same TWDM-PON system, the effective cooperation of the two DWBA schemes is very important, and the cooperation is related to the DWBA cycle. The SR-DWBA period is influenced by the PON transmission distance and the number of the ONUs and is generally not less than 1 ms. And the period of the CO-DWBA is related to the radio frame length. In a 4G LTE network, the frame length/frame period, also called TTI, is 1 ms. The UE may obtain the wireless bandwidth grant information 4 TTIs (4ms) in advance. As can be seen from the above, the OLT also obtains upstream data information 4ms in advance, and allocates upstream bandwidth in the PON in advance. Since 4ms is larger than the period of SR-DBWA, there is no allocation conflict for 4G forward traffic.
The 3GPP defines a new air interface (5G NR) of a 5G mobile network, and proposes a concept of a micro slot mini-slot, which is similar to a TTI concept in LTE and represents a basic frame structure and a scheduling period in a wireless network. The mini-slots specify more subcarrier spacings, such as 15, 30 and 60kHz, and fewer OFDM symbols for orthogonal frequency division multiplexing techniques, such as 2, 4, 7. The length of the mini-slot is smaller than that of the LTE TTI (1ms), and the method is more suitable for 5G low-delay service. However, the mini-slot-based 5G NR can cause the CO-DWBA and the SR-DWBA to collide in the resource allocation process, thereby increasing the time delay of the mobile forward traffic.
Specifically, in a TWDM-PON system facing fixed-moving fusion, an OLT realizes the access of an optical fiber-to-home ONU (FTTH ONU) and a fronthaul ONU (frontaul ONU) by combining two DWBA (SR-DWBA and CO-DWBA) modes.
As shown in fig. 1 (a), the CO-DWBA period depends on the TTI length, which is 1ms in 4G LTE, and for a wireless data packet 1 of one TTI to be uploaded in RU, the OLT receives radio resource grant information (e.g., mobile-info information in the figure) sent by the DU 4 TTIs (4ms) in advance, and thus performs wavelength bandwidth allocation on the ONU in advance. And then, the OLT issues an authorization to the allocation result before the ONU receives the data uploaded by the RU, so that the period of the CO-DWBA is less than 4ms (the upper bound of the period of the CO-DWBA) to ensure that the wireless data reaching the ONU does not need to wait for direct uploading.
As shown in fig. 1 (b), SR-DWBA scheduling is based on a conventional polling method of request grant, and the period depends on the maximum ONU round trip distance RTT max . OLT at t of SR-DWBA period i-1 i-1 And uniformly distributing the bandwidth after constantly collecting all the ONU request messages, and issuing the result to each ONU through an authorization message. And after receiving the authorization, the ONU uploads the data according to the authorized window size at the authorized transmission starting moment. To ensure that the OLT collects all ONU request information before the start of period i, the period length should be larger than RTT max . In addition, in order to meet the requirement of the number of ONUs carried by the OLT, the SR-DWBA period is generally not less than 1ms, for example, set to 2 ms.
Because of the different cycle length requirements of CO-DWBA and SR-DWBA, the real DWBA cycle is typically divided into a number of small grant cycles, which are combined to provide virtual CO-DWBA and SR-DWBA cycles. In the existing scheme, the length of the CO-DWBA period is equal to the length of one TTI (e.g. TTI in (a) of FIG. 1), and the length of the SR-DWBA period is equal to the length of the real periodThe degrees are all set to be the same as the TTI length in 4G LTE (as in SR-DWBA cycle in (b) in fig. 1). The cooperation of two DWBA is performed in real cycle when SR-DWBA at t i-1 When the bandwidth request is received at the moment, the CO-DWBA already receives mobile scheduling information (mobile-info) related to the total amount information of mobile data arriving in the SR-DWBA period i in advance, so that when the SR-DWBA is carried out, the front part bandwidth on each wavelength in the period can be reserved for the upcoming forwarding service, and then the residual bandwidth on each wavelength in the period is distributed according to the bandwidth request of the FTTH ONU. The scheme combines the advantages of the CO-DWBA and the SR-DWBA, can meet the low-delay transmission of the fronthaul service, and improves the resource utilization efficiency of the PON, but the precondition is that the CO-DWBA obtains the bandwidth request information earlier than the SR-DWBA, namely the period of the CO-DWBA is larger than that of the SR-DWBA.
The realization of the related scheme mainly depends on the OLT to advance T p Anticipating the total amount of wireless data in the current period, where T p The length of (2) is the time interval between the OLT receiving the cooperation information sent by the CU/DU and the ONU receiving the uploaded wireless data. T is p Depending on the mobile data downlink transmission delay, it is related to the slot/TTI length. As mentioned above, in 4G LTE, T p The value of (1) is 4TTI (i.e., 4ms), i.e., the OLT can predict the data amount of the forward service after 4ms, and preferentially allocate the wavelength and the bandwidth to the service.
In the 5G NR, different subcarrier intervals of 15, 30 and 60kHz are adopted, and meanwhile, the number of OFDM symbols in each time slot is changed from 14 which is originally fixed to be 2, 4 and 7 selectable in length. The higher carrier spacing and the smaller number of OFDM symbols results in a consequent reduction in slot length. As shown in fig. 2, mobile data 1 transmitted based on the mini-slot can be uploaded to the ONU without waiting for the completion of the collection of subsequent mobile data 2-n. Compared with the original method that the RU needs to receive all wireless data within the duration of 1ms TTI and then upload the wireless data to the ONU, the mini-slot-based transmission strategy can reduce the waiting time delay of the mobile forward service.
However, as the time slot is shortened, the T associated therewith p And also shortens, even less than the SR-DWBA period. Therefore, the OLT receives the mobile scheduling information (m) more than once in a real periodobile-info). But only at the time when the SR-DWBA is performed (e.g., t) i-1 ) The previously received mobile-info will be considered, and the bandwidth is reserved according to the arrival time of the mobile data carried by the mobile-info and the total amount of the mobile data. For mobile-info coming after the time when the SR-DWBA is executed, the bandwidth allocated with the CO-DWBA will conflict with the bandwidth already allocated by the SR-DWBA.
As shown in fig. 2, at t i-1 Before the moment, the OLT receives the mobile scheduling information about the mobile data 1-m-1, and the CO-DWBA allocates the first half part of the bandwidth in the period i to the mobile data 1-m-1. At t i-1 At the moment, the OLT receives a bandwidth request of the FTTH ONU, and the SR-DWBA allocates the remaining latter half bandwidth in the period i to the FTTH service. However, as can be seen from the above, the following mobile data m to n are received in the period i, and the shortened T is used as the basis p The time when the mobile scheduling information corresponding to the mobile data m to n reaches the OLT is later than t by calculation i-1 . Since OLT is at t i-1 The mobile data m-n are missed in advance, and wavelength bandwidth resources are reserved for the mobile data m-n, so that the wavelength bandwidth allocated to the mobile data m-n according to the CO-DWBA conflicts with the wavelength bandwidth allocated to the FTTH service by the SR-DWBA before. In order to avoid resource conflict, mobile data corresponding to subsequent mobile scheduling information can only be allocated to the idle bandwidth at the end of the period for uploading, which increases the waiting time delay of the forwarding service in the ONU.
In summary, the correlation scheme is performed in a 4G network under a scenario that the TTI length is 1ms, because the mini-slot shortening is proposed in the 5G NR, which results in that the CO-DWBA wireless scheduling period in the original scheme is not matched with the SR-DWBA polling authorization period, the OLT receives only the mobile scheduling information of part of the mobile data within the period length (1ms) when authorizing the FTTH, and does not have predictability for subsequent mobile data, which results in that no idle wavelength bandwidth resource in the OLT can be allocated to generate extra waiting delay, and therefore, the requirement of low-delay transmission delay of the mobile fronthaul service cannot be met. That is, the related wavelength bandwidth allocation scheme causes too high transmission delay of the forwarding traffic.
Fig. 3 is a schematic flow chart of a dynamic wavelength bandwidth allocation method according to an embodiment of the present disclosure; the dynamic wavelength bandwidth allocation method is applied to a time division wavelength division multiplexing passive optical network TWDM-PON; the TWDM-PON comprises an optical line terminal OLT and a plurality of optical network units ONU; the OLT is connected with a plurality of ONUs; there are multiple wavelengths used for transmitting traffic information in a TWDM-PON.
As an alternative embodiment, the TWDM-PON has 4 wavelengths for transmission in the uplink and downlink directions; the OLT has a receiver/transmitter capable of receiving and transmitting a plurality of wavelengths; the ONU has a tunable transmitter that can modulate to any 1 of the 4 wavelengths upstream and a tunable receiver that can receive any 1 of the 4 wavelengths downstream.
A dynamic wavelength bandwidth allocation method, comprising:
s310, the OLT determines a first ONU and a second ONU.
For each ONU, any one of a plurality of wavelengths of the TWDM-PON can be used for transmitting service, wherein the second ONU is the ONU which is allocated with bandwidth corresponding to any wavelength; the first ONU is an ONU which is to preempt the bandwidth of the wavelength distributed by the second ONU.
When a first ONU needs to use a wavelength of a TWDM-PON to transmit a fronthaul service, the fronthaul service is a high-priority service, and in order to ensure that the fronthaul service can complete transmission as early as possible, it is obvious that the fronthaul service cannot be queued to wait for transmission according to an existing transmission sequence, the first ONU may select to preempt wavelengths and bandwidths on the wavelengths that have been allocated to other ONUs, and the preempted ONU is denoted as a second ONU. The first ONU and the forwarding service information are known, and specifically, the forwarding service information includes a transmission start time and a bandwidth requirement preset by the forwarding service, and the transmission end time can be calculated according to the transmission start time and the bandwidth requirement.
And the first ONU transmits the request for transmitting the fronthaul service and the information of the fronthaul service to the OLT, and the OLT determines the preempted ONU, namely the second ONU according to the information of the fronthaul service.
The ONU sends the information to the OLT through a REPORT message; the OLT sends the information to the ONUs via GATE messages. Optionally, the ONU sends the service information in the ONU, such as the forwarding service information, to the OLT through a REPORT message. The REPORT message is a feedback mechanism used by the ONU to communicate local conditions (such as buffer occupancy, which can be understood as the bandwidth requirement of the ONU in this disclosure) to the OLT, and is used to help the OLT allocate time slots. Correspondingly, the GATE message is sent from the OLT to a single ONU for allocating a time slot for transmission to the ONU, where a time slot is represented by three values, namely the transmission wavelength, the transmission start time and the transmission window length. The GATE message and the REPORT message are both MAC control frames used in the TWDM-PON message interaction protocol.
And S320, the OLT determines the preemption time and the retransmission time.
And taking the transmission starting moment of the second ONU as the preemption moment. The second ONU is an ONU to which a bandwidth is allocated corresponding to any wavelength, that is, the transmission start time of the second ONU is known.
Wherein, according to the preemption time, the retransmission time can be calculated.
The retransmission time instant can be calculated by:
t re ＝t pre +t date +t guard ；
wherein, t re Is the retransmission time, t pre To preempt time, t date Duration of transmission of traffic for the first ONU, t guard Is a guard interval.
And S330, the OLT generates a preemption instruction according to the preemption moment and sends the preemption instruction to the first ONU.
The preemption instruction is used for enabling the first ONU to perform service transmission at the preemption moment.
And S340, the OLT generates a retransmission instruction according to the retransmission time and sends the retransmission instruction to the second ONU.
And the retransmission instruction is used for enabling the second ONU to carry out service transmission at the retransmission moment.
Optionally, the OLT sends the instruction to the ONU through a GATE message.
The GATE message is sent from the OLT to a single ONU for assigning a time slot for transmission to the ONU, a time slot being represented by three values, a transmission wavelength, a transmission start time and a transmission window length.
Fig. 4 is a scene schematic diagram of a dynamic wavelength bandwidth allocation method according to an embodiment of the present disclosure(ii) a Wherein λ is k Is wavelength k, TX is transceiver, t pre To preempt time, t realloc1 、t realloc2 And t realloc3 Is 3 retransmission time instants.
The dynamic wavelength bandwidth allocation method is implemented by an optical line terminal OLT for performing preemption decision, a forwarding ONU for receiving a preemption command and a fiber-to-the-home ONU for receiving the preempted command. The forwarding ONU and the fiber-to-the-home ONU correspond to a first ONU and a second ONU respectively. For purposes of uniform presentation, the present disclosure will be described with a first ONU and a second ONU (where the first ONU refers to the preempting ONU, i.e. the forwarding ONU, and the second ONU refers to the preempted ONU, i.e. the fiber-to-the-home ONU). Optionally, the OLT comprises a DWBA controller and a receiver/transmitter λ capable of receiving and transmitting a plurality of wavelengths k TX. The DWBA controller executes a Wavelength Bandwidth Allocation (WBA) decision, determines a first ONU and a second ONU, and a preemption time and a retransmission time, generates a preemption instruction according to the preemption time and sends the preemption instruction to the first ONU, and generates a retransmission instruction according to the retransmission time and sends the retransmission instruction to the second ONU. Before the preemption moment, the second ONU transmits fiber-to-the-home data. And the first ONU transmits the forwarding service at the preemption moment. The second ONU retransmits the interrupted traffic at the retransmission moment.
Fig. 5 is a flowchart illustrating a method for determining a second ONU according to an embodiment of the present disclosure.
And S510, judging whether the wavelength which can be distributed exists in the TWDM-PON.
In response to determining that there are allocatable wavelengths in the TWDM-PON, the earliest available wavelength is granted and bandwidth and start time are allocated. In this case, there is an idle wavelength in the TWDM-PON, and it is not necessary to determine the second ONU to preempt the wavelength bandwidth allocated to the second ONU.
In the OLT, each wavelength corresponds to the next available transmission time of the wavelength, the OLT records the next available transmission time of all the wavelengths, when the OLT allocates the wavelength to the ONU, the wavelength with the earliest current next available transmission time is selected, meanwhile, the ONU is authorized to have a transmission window on the wavelength, then, the next available transmission time of the wavelength is updated, the size of the transmission window is determined by a bandwidth allocation algorithm, and the process of bandwidth allocation is called as the authorized earliest available wavelength.
And S520, judging whether the ONU meeting the preset preempted condition exists or not.
In response to determining that there are no assignable wavelengths in the TWDM-PON, a third ONU is determined corresponding to each wavelength.
And the third ONU is the ONU which meets the preset preempted condition. In this case, if there is no idle wavelength in the TWDM-PON, it is necessary to determine the second ONU to preempt the wavelength bandwidth allocated to the second ONU. And if no ONU meeting the preset preempted condition exists, authorizing the earliest available wavelength, and allocating the bandwidth and the starting moment, namely queuing and waiting.
And S530, taking the third ONU with the earliest transmission starting time in the plurality of third ONUs as the second ONU.
The third ONU with the earliest transmission starting time is the earliest preemptible ONU, and is taken as the second ONU, so that the time delay of the first ONU for transmitting the forwarding service can be reduced.
Fig. 6 is a flowchart illustrating a method for determining a third ONU according to an embodiment of the present disclosure.
S610, determining the preset transmission starting time of the first ONU.
The preset transmission starting moment of the first ONU is the earliest moment that the first ONU can preempt.
And S620, determining a fourth ONU corresponding to each wavelength.
The fourth ONU is an ONU to which the bandwidth of the wavelength is allocated at and after the preset transmission start time of the first ONU. And if the ONU does not meet the preset preemption condition, the ONU using the wavelength to transmit the service will also become an alternative preempted target after the ONU finishes transmitting the service.
For each of the fourth ONUs, the first ONU is,
s630, whether the fourth ONU has a high priority.
And in response to determining that the fourth ONU has a high priority, emptying the preempted queue and re-determining the fourth ONU, wherein the preempted queue comprises at least one fourth ONU which does not have a high priority.
Wherein, re-determining the fourth ONU specifically includes: and taking the next ONU corresponding to the wavelength corresponding to the fourth ONU as the newly determined fourth ONU.
And S640, whether the transmission ending time of the fourth ONU is earlier than the preset transmission ending time of the first ONU.
In response to determining that the fourth ONU does not have the high priority, further determining whether the transmission end time of the fourth ONU is earlier than a preset transmission end time of the first ONU:
and in response to the fact that the transmission ending time of the fourth ONU is earlier than the preset transmission ending time of the first ONU, putting the fourth ONU into the preempted queue, and re-determining the fourth ONU. Wherein, re-determining the fourth ONU specifically includes: and taking the next ONU corresponding to the wavelength corresponding to the fourth ONU as the newly determined fourth ONU.
And in response to the fact that the transmission end time of the fourth ONU is later than the preset transmission end time of the first ONU, putting the fourth ONU into the preempted queue and taking all the ONUs in the preempted queue as a third ONU together.
Fig. 7 is a more specific scenario diagram of a dynamic wavelength bandwidth allocation method according to an embodiment of the present disclosure. In the preemption method provided in this embodiment, corresponding to the method in fig. 6, except for a high-priority service (fronthaul service), other services can be preempted, and a cross-ONU can also be preempted, so as to reduce the waiting time delay of the fronthaul service as much as possible. The preemption constraint is most friendly to the forwarding service, but causes frequent preemption and increases preemption sections.
Fig. 8 is a flowchart illustrating that the first ONU performs preemption, which includes:
receiving OLT authorization information;
in response to satisfying t pre,k Directly sending data according to the authorization information;
in response to not satisfying t pre,k Waiting for grant time to reissueAnd sending the service.
Fig. 9 is a schematic flowchart of a process of executing retransmission by a second ONU according to an embodiment of the present disclosure, where the process includes:
the preempting ONU performs block transmission at the wavelength bandwidth which is not occupied by the preempting ONU so as to avoid the conflict with the preempting ONU, and two conditions exist for the transmission mode of the preempted ONU on an uplink frame, respectively, when only one t is received realloc When the buffered data is transmitted by only one burst uploading ONU interrupt and when a plurality of t are received realloc The buffered data needs to be split into multiple bursts to upload the ONU to defer transmission.
As can be seen from the above description, the dynamic wavelength bandwidth allocation method provided by the present disclosure is applied to a time division wavelength division multiplexing passive optical network TWDM-PON, where the TWDM-PON includes an optical line terminal OLT and a plurality of optical network units ONU, and the preempted ONU are determined, and the preemption time and the retransmission time are determined, so that the preempted ONU preempts the fronthaul service at the time, and the preempted ONU retransmits the service occupying the bandwidth resource at the retransmission time, and by using the preemptive wavelength bandwidth allocation method, the transmission delay of the fronthaul service is reduced.
It should be noted that the method of the embodiments of the present disclosure may be executed by a single device, such as a computer or a server. The method of the embodiment can also be applied to a distributed scene and completed by the mutual cooperation of a plurality of devices. In such a distributed scenario, one of the devices may only perform one or more steps of the method of the embodiments of the present disclosure, and the devices may interact with each other to complete the method.
It should be noted that the above describes some embodiments of the disclosure. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments described above and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
It should be noted that the embodiments of the present disclosure can be further described in the following ways:
a dynamic wavelength bandwidth allocation method is applied to a time division wavelength division multiplexing passive optical network TWDM-PON; the TWDM-PON comprises an optical line terminal OLT and a plurality of optical network units ONU; the OLT is connected with a plurality of ONU; the TWDM-PON comprises a plurality of wavelengths for transmitting service information;
the method comprises the following steps:
the OLT determines a first ONU and a second ONU; the second ONU is the ONU which is allocated with bandwidth corresponding to any wavelength; the first ONU is the ONU which is to preempt the bandwidth of the wavelength distributed by the second ONU;
the OLT determines a preemption moment and a retransmission moment;
the OLT generates a preemption instruction according to the preemption moment and sends the preemption instruction to the first ONU; the preemption instruction is used for enabling the first ONU to carry out service transmission at the preemption moment;
the OLT generates a retransmission instruction according to the retransmission moment and sends the retransmission instruction to the second ONU; and the retransmission instruction is used for enabling the second ONU to carry out service transmission at the retransmission moment.
Optionally, the determining, by the OLT, a first ONU and a second ONU specifically includes:
determining whether the wavelengths that are allocable are present in the TWDM-PON;
determining a third ONU for each of the wavelengths in response to determining that there are no assignable wavelengths in the TWDM-PON; the third ONU meets the preset preempted condition; and the third ONU with the earliest transmission starting time in the plurality of third ONUs is taken as the second ONU.
Optionally, the determining, by the OLT, a preemption time and a retransmission time specifically includes:
taking the transmission starting moment of the second ONU as the preemption moment;
and calculating to obtain the retransmission time according to the preemption time.
Optionally, wherein, in response to determining that the assignable wavelengths do not exist in the TWDM-PON, determining a third ONU corresponding to each of the wavelengths specifically includes:
determining a preset transmission starting moment of the first ONU;
determining a fourth ONU corresponding to each of said wavelengths; the fourth ONU is the ONU to which the bandwidth of the wavelength is allocated at the preset transmission start time and later;
for each of said fourth ONUs, a first ONU,
determining whether the fourth ONU has a high priority,
responsive to determining that the fourth ONU has a high priority, flushing a preempted queue, re-determining the fourth ONU, wherein the preempted queue comprises at least one fourth ONU that does not have a high priority,
in response to determining that the fourth ONU does not have a high priority, further determining whether a transmission end time of the fourth ONU is earlier than a preset transmission end time of the first ONU,
and in response to determining that the transmission end time of the fourth ONU is earlier than the preset transmission end time of the first ONU, putting the fourth ONU in the preempted queue, re-determining the fourth ONU, and in response to determining that the transmission end time of the fourth ONU is later than the preset transmission end time of the first ONU, putting the fourth ONU in the preempted queue and taking all the ONUs in the preempted queue as the third ONU together.
Optionally, the re-determining the fourth ONU specifically includes:
and taking the next ONU corresponding to the wavelength corresponding to the fourth ONU as the newly determined fourth ONU.
Optionally, the calculating the retransmission time according to the preemption time includes:
the retransmission time instant may be calculated by:
t re ＝t pre +t date +t guard ；
wherein, t re Is the retransmission time, t pre To preempt time, t date Duration, t, of traffic transmission for the first ONU guard Is a guard interval.
Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the present disclosure, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of brevity.
In addition, well-known power/ground connections to Integrated Circuit (IC) chips and other components may or may not be shown in the provided figures for simplicity of illustration and discussion, and so as not to obscure the embodiments of the disclosure. Furthermore, devices may be shown in block diagram form in order to avoid obscuring embodiments of the present disclosure, and this also takes into account the fact that specifics with respect to implementation of such block diagram devices are highly dependent upon the platform within which the embodiments of the present disclosure are to be implemented (i.e., specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that the embodiments of the disclosure can be practiced without, or with variation of, these specific details. Accordingly, the description is to be regarded as illustrative instead of restrictive.
While the present disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. For example, other memory architectures (e.g., dynamic ram (dram)) may use the discussed embodiments.
The disclosed embodiments are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalents, improvements, and the like that may be made within the spirit and principles of the embodiments of the disclosure are intended to be included within the scope of the disclosure.

Claims (4)

1. A dynamic wavelength bandwidth allocation method is applied to a time division wavelength division multiplexing passive optical network TWDM-PON; the TWDM-PON comprises an optical line terminal OLT and a plurality of optical network units ONU; the OLT is connected with a plurality of ONU; the TWDM-PON comprises a plurality of wavelengths for transmitting service information;
the method comprises the following steps:
the OLT determines a first ONU and a second ONU, and specifically includes:
determining whether the wavelengths that are allocable are present in the TWDM-PON;
in response to determining that the assignable wavelengths do not exist in the TWDM-PON, determining a third ONU corresponding to each of the wavelengths, specifically including:
determining a preset transmission starting moment of the first ONU;
determining a fourth ONU corresponding to each of said wavelengths; the fourth ONU is the ONU to which the bandwidth of the wavelength is allocated at the preset transmission start time and later;
for each of said fourth ONUs, a first ONU,
determining whether the fourth ONU has a high priority,
responsive to determining that the fourth ONU has a high priority, flushing a preempted queue containing at least one of the fourth ONUs that does not have a high priority, and re-determining the fourth ONU,
in response to determining that the fourth ONU does not have a high priority, further determining whether a transmission end time of the fourth ONU is earlier than a preset transmission end time of the first ONU,
emptying the preempted queue in response to determining that the transmission end time of the fourth ONU is earlier than the preset transmission end time of the first ONU, re-determining the fourth ONU,
in response to determining that the transmission end time of the fourth ONU is later than the preset transmission end time of the first ONU, placing the fourth ONU in the preempted queue and taking all the ONUs in the preempted queue together as the third ONU;
the third ONU meets the preset preempted condition; setting the third ONU with the earliest transmission start time among the plurality of third ONUs as the second ONU;
the second ONU is the ONU which is allocated with bandwidth corresponding to any wavelength; the first ONU is the ONU which is to preempt the bandwidth of the wavelength distributed by the second ONU; the OLT determines a preemption moment and a retransmission moment;
the OLT generates a preemption instruction according to the preemption moment and sends the preemption instruction to the first ONU; the preemption instruction is used for enabling the first ONU to carry out service transmission at the preemption moment;
the OLT generates a retransmission instruction according to the retransmission moment and sends the retransmission instruction to the second ONU; and the retransmission instruction is used for enabling the second ONU to carry out service transmission at the retransmission moment.
2. The method according to claim 1, wherein the OLT determines the preemption time and the retransmission time, and specifically comprises:
taking the transmission starting moment of the second ONU as the preemption moment;
and calculating to obtain the retransmission time according to the preemption time.
3. The method according to claim 1, wherein the re-determining the fourth ONU specifically comprises:
and taking the next ONU corresponding to the wavelength corresponding to the fourth ONU as the newly determined fourth ONU.
4. The method of claim 2, wherein said calculating the retransmission time based on the preemption time comprises:
the retransmission time instant may be calculated by:
t re ＝t pre +t date +t guard ；
wherein, t re For the retransmission time, t pre To preempt time, t date Duration of transmission of traffic for the first ONU, t guard Is a guard interval.
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