U.S. patent application number 15/474890 was filed with the patent office on 2017-07-20 for wavelength configuration method and apparatus for multi-wavelength passive optical network, and multi-wavelength passive optical network system.
The applicant listed for this patent is Huawei Technologies Co., Ltd.. Invention is credited to Bo GAO, Jianhe GAO, Huafeng LIN, Fei YE.
Application Number | 20170207876 15/474890 |
Document ID | / |
Family ID | 49757423 |
Filed Date | 2017-07-20 |
United States Patent
Application |
20170207876 |
Kind Code |
A1 |
GAO; Bo ; et al. |
July 20, 2017 |
WAVELENGTH CONFIGURATION METHOD AND APPARATUS FOR MULTI-WAVELENGTH
PASSIVE OPTICAL NETWORK, AND MULTI-WAVELENGTH PASSIVE OPTICAL
NETWORK SYSTEM
Abstract
The present application provides a wavelength configuration
method for a multi-wavelength passive optical network, which
includes: scanning, by an ONU, a downstream receiving wavelength,
and receiving, downstream wavelength information of each downstream
wavelength channel that is broadcast by an OLT separately through
each downstream wavelength channel of a multi-wavelength PON
system; establishing, by the ONU, a downstream receiving wavelength
mapping table, where an entry of the downstream receiving
wavelength mapping table includes downstream receiving wavelength
information, drive current information of a downstream optical
receiver and receiving optical physical parameter information of
the ONU; selecting, by the ONU, one downstream wavelength from the
downstream wavelength information broadcast by the OLT, and
setting, according to the drive current information of the
downstream optical receiver recorded in a related entry of the
downstream receiving wavelength mapping table, an operating
wavelength of the downstream optical receiver to the selected
downstream wavelength.
Inventors: |
GAO; Bo; (Wuhan, CN)
; LIN; Huafeng; (Shenzhen, CN) ; GAO; Jianhe;
(Wuhan, CN) ; YE; Fei; (Shenzhen, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Huawei Technologies Co., Ltd. |
Shenzhen |
|
CN |
|
|
Family ID: |
49757423 |
Appl. No.: |
15/474890 |
Filed: |
March 30, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14569682 |
Dec 13, 2014 |
9647791 |
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15474890 |
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PCT/CN2012/076848 |
Jun 13, 2012 |
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14569682 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B 10/27 20130101;
H04J 14/025 20130101; H04J 14/0252 20130101; H04J 14/0258 20130101;
H04J 14/0246 20130101; H04J 14/0247 20130101; H04J 14/0257
20130101; H04J 14/0282 20130101; H04J 14/0267 20130101; H04J
14/0232 20130101; H04J 14/0269 20130101; H04J 14/0275 20130101 |
International
Class: |
H04J 14/02 20060101
H04J014/02; H04B 10/27 20060101 H04B010/27 |
Claims
1. A wavelength configuration method for a multi-wavelength passive
optical network PON, comprising: scanning, by an optical network
unit ONU, a downstream receiving wavelength; receiving, during the
process of scanning the downstream receiving wavelength, downstream
wavelength information of each downstream wavelength channel that
is broadcast by an optical line terminal OLT separately through
each downstream wavelength channel of a multi-wavelength PON
system; and establishing, by the ONU, a downstream receiving
wavelength mapping table according to the downstream wavelength
information, wherein an entry of the downstream receiving
wavelength mapping table comprises downstream receiving wavelength
information, drive current information of a downstream optical
receiver, and a receiving optical physical parameter of the
ONU.
2. The wavelength configuration method according to claim 1,
wherein the establishing, by the ONU, a downstream receiving
wavelength mapping table according to the downstream wavelength
information comprises: detecting, by the ONU, a receiving optical
current of the ONU, or receiving optical power of the ONU, or a
received signal strength indication RSSI during the process of
scanning the downstream receiving wavelength, and searching for a
peak value of the receiving optical current of the ONU, or a peak
value of the receiving optical power of the ONU, or an RSSI peak
value; and when the peak value of the receiving optical current of
the ONU, or the peak value of the receiving optical power of the
ONU, or the RSSI peak value is searched out, recording, by the ONU,
a current drive current of the downstream optical receiver and
downstream wavelength information of a downstream wavelength
channel corresponding to the peak value of the receiving optical
current of the ONU, or the peak value of the receiving optical
power of the ONU, or the RSSI peak value, and establishing a
downstream receiving wavelength mapping entry according to the
foregoing three parameters.
3. The wavelength configuration method according to claim 2,
further comprising: scanning, by the ONU, an upstream sending
wavelength, and sending a registration request to the OLT in a
registration authorization timeslot allocated by the OLT; and
determining whether an ONU identifier allocation message sent by
the OLT is received, and if the ONU identifier allocation message
sent by the OLT is not received, sending, in a next registration
authorization timeslot allocated by the OLT, the registration
request to the OLT again until the ONU identifier allocation
message is successfully received.
4. The wavelength configuration method according to claim 3,
wherein the scanning, by the ONU, an upstream sending wavelength,
and sending a registration request to the OLT in a registration
authorization timeslot allocated by the OLT comprises: selecting,
by the ONU, one boundary value from a value range of drive currents
supported by an upstream optical transmitter of the ONU as an
initial current value, and adjusting a drive current of the
upstream optical transmitter by using a preset variation so as to
perform a progressive increase or decrease; and sending, by the ONU
and within the registration authorization timeslot provided by the
OLT for the ONU, the ONU registration request to the OLT according
to an upstream sending wavelength corresponding to a drive current
value to which the drive current of the upstream optical
transmitter is currently adjusted.
5. The wavelength configuration method according to claim 4,
further comprising: detecting, by the ONU according to the
downstream receiving wavelength mapping table, whether a drift
occurs on a downstream receiving wavelength of the downstream
optical receiver of the ONU, and calibrating the downstream
receiving wavelength when the drift occurs.
6. The wavelength configuration method according to claim 1,
further comprising: receiving, by the ONU, an upstream sending
wavelength adjustment instruction sent by the OLT, and fine-tuning
an upstream sending wavelength of an upstream optical transmitter
according to the upstream sending wavelength adjustment
instruction, so that the OLT detects a receiving optical physical
parameter of the OLT and establishes an upstream receiving
wavelength mapping table, wherein an entry of the upstream
receiving wavelength mapping table comprises upstream receiving
wavelength information, ONU sequence number information, and the
receiving optical physical parameter of the OLT.
7. The wavelength configuration method according to claim 6,
further comprising: receiving, by the ONU, upstream receiving
wavelength information delivered by the OLT after the upstream
receiving wavelength mapping table is established, and establishing
an upstream sending wavelength mapping table according to the
upstream receiving wavelength information, wherein the upstream
sending wavelength mapping table comprises upstream sending
wavelength information and drive current information of the
upstream optical transmitter.
8. The wavelength configuration method according to claim 1,
further comprising: selecting, by the ONU, one downstream
wavelength from the downstream wavelength information broadcast by
the OLT, and setting, according to the drive current information of
the downstream optical receiver recorded in a related entry of the
downstream receiving wavelength mapping table, an operating
wavelength of the downstream optical receiver to the selected
downstream wavelength
9. The wavelength configuration method according to claim 6,
further comprising: monitoring, by the OLT according to the
upstream receiving wavelength mapping table, whether a drift occurs
on an upstream sending wavelength of the ONU, and instructing the
ONU to calibrate the upstream sending wavelength when the drift
occurs.
10. A wavelength configuration apparatus for a multi-wavelength
passive optical network PON, comprising: a receiving module,
configured to scan a downstream receiving wavelength, and receive,
during the process of scanning the downstream receiving wavelength,
downstream wavelength information of each downstream wavelength
channel that is broadcast by an optical line terminal OLT
separately through each downstream wavelength channel of a
multi-wavelength PON system; a wavelength mapping table
establishing module, configured to establish a downstream receiving
wavelength mapping table according to the downstream wavelength
information, wherein an entry of the downstream receiving
wavelength mapping table comprises downstream receiving wavelength
information, drive current information of a downstream optical
receiver, and a receiving optical physical parameter of an ONU.
11. The wavelength configuration apparatus according to claim 10,
wherein the wavelength mapping table establishing module comprises:
a peak value searching unit, configured to search for a peak value
of a receiving optical current of the ONU, or a peak value of
receiving optical power of the ONU, or an RSSI peak value from
detected receiving optical current of the ONU, or receiving optical
power of the ONU, or received signal strength indication during the
process of scanning the downstream receiving wavelength; and an
entry establishing module, configured to: when the peak value
searching unit searches out the peak value of the receiving optical
current of the ONU, or the peak value of the receiving optical
power of the ONU, or the RSSI peak value, record a current drive
current of the downstream optical receiver and downstream
wavelength information of a downstream wavelength channel
corresponding to the peak value of the receiving optical current of
the ONU, or the peak value of the receiving optical power of the
ONU, or the RSSI peak value, and establish a downstream receiving
wavelength mapping entry according to the foregoing three
parameters.
12. The wavelength configuration apparatus according to claim 11,
further comprising: a sending module, configured to scan an
upstream sending wavelength, and send a registration request to the
OLT in a registration authorization timeslot allocated by the OLT;
and a control module, configured to: determine whether the
receiving module receives an ONU identifier allocation message sent
by the OLT; and if the receiving module does not receive the ONU
identifier allocation message sent by the OLT, control the sending
module to send the registration request to the OLT again in a next
registration authorization timeslot allocated by the OLT, until the
receiving module successfully receives the ONU identifier
allocation message.
13. The wavelength configuration apparatus according to claim 12,
wherein the sending module comprises: a drive current adjusting
unit, configured to select one boundary value from a value range of
drive currents supported by an upstream optical transmitter as an
initial current value, and adjust a drive current of the upstream
optical transmitter by using a preset variation so as to perform a
progressive increase or decrease; and a sending unit, configured to
send, within the registration authorization timeslot provided by
the OLT for the ONU, an ONU registration request to the OLT
according to an upstream sending wavelength corresponding to a
drive current value to which the drive current of the upstream
optical transmitter is currently adjusted.
14. The wavelength configuration apparatus according to claim 13,
further comprising: a wavelength calibrating module, configured to
detect, according to the downstream receiving wavelength mapping
table, whether a drift occurs on a downstream receiving wavelength
of the downstream optical receiver of the ONU, and calibrate the
downstream receiving wavelength when the drift occurs.
15. The wavelength configuration apparatus according to claim 13,
wherein, the receiving module is further configured to receive an
upstream sending wavelength adjustment instruction sent by the OLT;
and the sending module is further configured to fine-tune the
upstream sending wavelength of the upstream optical transmitter
according to the upstream wavelength adjustment instruction, so
that the OLT detects a receiving optical current of the OLT and
establishes an upstream receiving wavelength mapping table.
16. The wavelength configuration apparatus according to claim 15,
wherein, the receiving module is further configured to receive
upstream receiving wavelength information delivered by the OLT
after the upstream receiving wavelength mapping table is
established; and the wavelength mapping table establishing module
is further configured to establish an upstream sending wavelength
mapping table according to the upstream receiving wavelength
information, wherein the upstream sending wavelength mapping table
comprises upstream sending wavelength information and drive current
information of the upstream optical transmitter.
17. The wavelength configuration apparatus according to claim 16,
wherein, the receiving module is further configured to: when the
downstream wavelength information broadcast by the OLT is received,
receive upstream wavelength information that is broadcast by the
OLT separately through each downstream wavelength channel and is
available for ONU registration.
18. The wavelength configuration apparatus according to claim 10,
wherein the apparatus further comprises: a wavelength configuration
module, configured to select one downstream wavelength from the
downstream wavelength information broadcast by the OLT, and set,
according to the drive current information of the downstream
optical receiver recorded in a related entry of the downstream
receiving wavelength mapping table, an operating wavelength of the
downstream optical receiver to the selected downstream
wavelength.
19. A multi-wavelength passive optical network PON system,
comprising at least one optical line terminal OLT and multiple
optical network units ONUs, wherein the at least one OLT is
connected to the multiple ONUs in a point-to-multipoint manner by
using an optical distribution network, and the ONUs comprise the
wavelength configuration apparatus for a multi-wavelength PON,
wherein the wavelength configuration apparatus comprises: a
receiving module, configured to scan a downstream receiving
wavelength, and receive, during the process of scanning the
downstream receiving wavelength, downstream wavelength information
of each downstream wavelength channel that is broadcast by an
optical line terminal OLT separately through each downstream
wavelength channel of a multi-wavelength PON system; a wavelength
mapping table establishing module, configured to establish a
downstream receiving wavelength mapping table according to the
downstream wavelength information, wherein an entry of the
downstream receiving wavelength mapping table comprises downstream
receiving wavelength information, drive current information of a
downstream optical receiver, and a receiving optical physical
parameter of an ONU.
20. The wavelength configuration apparatus according to claim 19,
wherein the apparatus further comprises: a wavelength configuration
module, configured to select one downstream wavelength from the
downstream wavelength information broadcast by the OLT, and set,
according to the drive current information of the downstream
optical receiver recorded in a related entry of the downstream
receiving wavelength mapping table, an operating wavelength of the
downstream optical receiver to the selected downstream wavelength.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/569,682, filed on Dec. 13, 2014, which is a
continuation of International Application No. PCT/CN2012/076848,
filed on Jun. 13, 2012. All of the afore-mentioned patent
applications are hereby incorporated by reference in their
entireties.
TECHNICAL FIELD
[0002] The present application mainly relates to optical
communications technologies, and in particular, to a wavelength
configuration method and apparatus for a multi-wavelength passive
optical network (Passive Optical Network, PON), and a
multi-wavelength passive optical network system.
BACKGROUND
[0003] A passive optical network (PON) technology is currently a
main broadband access technology. A conventional PON system is a
point-to-multipoint network system based on a time division
multiplexing (TDM) mechanism. Referring to FIG. 1, the PON system
generally includes an optical line terminal (OLT) located on a
central office side, multiple optical network units (ONU) located
on a user side, and an optical distribution network (ODN) between
the OLT and the ONUs. The ODN is used to distribute or multiplex
data signals between the OLT and the ONUs so that the multiple ONUs
can share an optical transmission path. In the PON system based on
the TDM mechanism, a direction from the OLT to the ONUs is called
downstream, the OLT broadcasts a downstream data stream to all the
ONUs in a TDM manner, and each ONU receives only data that carries
an identifier of the ONU; a direction from the ONUs to the OLT is
called upstream. Because all the ONUs share the optical
transmission path, in order to prevent a conflict of upstream data
between the ONUs, the PON system uses a Time Division Multiple
Access (TDMA) manner in the upstream direction. That is, the OLT
allocates a timeslot to each ONU, and each ONU sends upstream data
in strict accordance with the timeslot allocated by the OLT.
[0004] However, the PON system is affected by a time division
characteristic of the TDM mechanism, and available bandwidth of a
user is generally restricted. In addition, available bandwidth of a
fiber itself cannot be effectively used. Therefore, emerging
broadband network application service requirements cannot be
satisfied. To solve such a problem and in view of compatibility
with an existing PON system, a hybrid PON system that integrates a
wavelength division multiplexing (WDM) technology and the TDM
technology is put forward in the industry. In the hybrid PON,
multiple wavelength channels are used between an OLT on a central
office side and ONUs on a user side to receive and send data. That
is, the hybrid PON system is a multi-wavelength PON system.
[0005] In the multi-wavelength PON system, the OLT supports data
sending and receiving performed simultaneously by using multiple
wavelength channels. Each ONU works on one of the wavelength
channels separately. In the downstream direction, the OLT uses a
downstream wavelength corresponding to each wavelength channel to
broadcast downstream data to multiple ONUs that work on the
wavelength channel; in the upstream direction, an ONU on each
wavelength channel may send, in a timeslot allocated by the OLT,
upstream data to the OLT through an upstream wavelength of the
wavelength channel. In order to reduce warehousing costs, the ONU
generally uses a wavelength-tunable optical transceiver component.
Therefore, an operating wavelength needs to be configured for the
ONU during initialization. However, if a downstream receiving
wavelength or an upstream sending wavelength configured by the ONU
is not supported by the OLT, the ONU cannot register
successfully.
SUMMARY
[0006] The present application provides a wavelength configuration
method for a multi-wavelength passive optical network, where the
method can effectively ensure normal ONU registration. In addition,
based on the wavelength configuration method, the present
application further provides a multi-wavelength passive optical
network system and a wavelength configuration apparatus for the
multi-wavelength passive optical network system.
[0007] A wavelength configuration method for a multi-wavelength
passive optical network includes: scanning, by an ONU, a downstream
receiving wavelength, and receiving, during the process of scanning
the downstream receiving wavelength, downstream wavelength
information of each downstream wavelength channel that is broadcast
by an OLT separately through each downstream wavelength channel of
a multi-wavelength passive optical network system; establishing, by
the ONU, a downstream receiving wavelength mapping table according
to the downstream wavelength information, where an entry of the
downstream receiving wavelength mapping table includes downstream
receiving wavelength information, drive current information of a
downstream optical receiver, and a receiving optical physical
parameter of the ONU; and selecting, by the ONU, one downstream
wavelength from the downstream wavelength information broadcast by
the OLT, and setting, according to the drive current information of
the downstream optical receiver recorded in a related entry of the
downstream receiving wavelength mapping table, an operating
wavelength of the downstream optical receiver to the selected
downstream wavelength.
[0008] A wavelength configuration apparatus for a multi-wavelength
passive optical network includes: a receiving module, configured to
scan a downstream receiving wavelength, and receive, during the
process of scanning the downstream receiving wavelength, downstream
wavelength information of each downstream wavelength channel that
is broadcast by an OLT separately through each downstream
wavelength channel of a multi-wavelength passive optical network
system; a wavelength mapping table establishing module, configured
to establish a downstream receiving wavelength mapping table
according to the downstream wavelength information, where an entry
of the downstream receiving wavelength mapping table includes
downstream receiving wavelength information, drive current
information of a downstream optical receiver, and a receive optical
physical parameter of an ONU; and a wavelength configuration
module, configured to select one downstream wavelength from the
downstream wavelength information broadcast by the OLT, and set,
according to the drive current information of the downstream
optical receiver recorded in a related entry of the downstream
receiving wavelength mapping table, an operating wavelength of the
downstream optical receiver to the selected downstream
wavelength.
[0009] A multi-wavelength passive optical network system includes:
at least one OLT and multiple ONUs. The at least one OLT is
connected to the multiple ONUs in a point-to-multipoint manner
through an optical distribution network. The ONU includes the
foregoing wavelength configuration apparatus for a multi-wavelength
passive optical network.
[0010] In the wavelength configuration method and apparatus for a
multi-wavelength PON and the multi-wavelength PON system provided
in the present application, an ONU scans a wavelength and interacts
with an OLT during an initialization process, establishes a
corresponding wavelength mapping table, so as to ensure that a
transceiver wavelength configured by the ONU is within a wavelength
range supported by the OLT, thereby implementing normal
initialization of the ONU transceiver wavelength.
BRIEF DESCRIPTION OF DRAWINGS
[0011] To describe the technical solutions in the embodiments of
the present invention or in the prior art more clearly, the
following briefly introduces the accompanying drawings required for
describing the embodiments. Apparently, the accompanying drawings
in the following description show merely some embodiments of the
present invention, and a person of ordinary skill in the art may
still derive other drawings from these accompanying drawings
without creative efforts.
[0012] FIG. 1 is a schematic diagram of a network architecture of a
passive optical network system based on a time division
multiplexing mechanism;
[0013] FIG. 2 is a schematic diagram of a network architecture of a
multi-wavelength passive optical network system according to an
embodiment of the present application;
[0014] FIG. 3 is a flowchart of a wavelength switching method for a
multi-wavelength passive optical network according to a first
embodiment of the present application;
[0015] FIG. 4 is a schematic diagram in which an XGTC frame is used
to carry wavelength information in the wavelength switching method
for a multi-wavelength passive optical network shown in FIG. 3;
[0016] FIG. 5 is a schematic diagram in which a PLOAM message is
used to carry wavelength information in the wavelength switching
method for a multi-wavelength passive optical network shown in FIG.
3; and
[0017] FIG. 6 is a schematic structural diagram of a wavelength
switching apparatus for a multi-wavelength passive optical network
according to an embodiment of the present application.
DESCRIPTION OF EMBODIMENTS
[0018] The following clearly describes the technical solutions in
the embodiments of the present invention with reference to the
accompanying drawings in the embodiments of the present invention.
Apparently, the described embodiments are merely a part rather than
all of the embodiments of the present invention. All other
embodiments obtained by a person of ordinary skill in the art based
on the embodiments of the present invention without creative
efforts shall fall within the protection scope of the present
invention.
[0019] Refer to FIG. 2, which is a schematic diagram of a network
architecture of a multi-wavelength passive optical network system
100 according to an embodiment of the present application. The
multi-wavelength PON system 100 includes at least one optical line
terminal (OLT) 110, multiple optical network units (ONU) 120, and
one optical distribution network (ODN) 130, where the OLT 110 is
connected to the multiple ONUs 120 in a point-to-multipoint manner
by using the ODN 130, and the multiple ONUs 120 share an optical
transmission medium of the ODN 130. The ODN 130 may include a
feeder fiber 131, an optical splitter module 132, and multiple drop
fibers 133, where the optical splitter module 132 may be disposed
at a remote node (RN). The optical splitter module is connected to
the OLT 110 by using the feeder fiber 131 on the one hand and
connected to the multiple ONUs 120 separately by using the multiple
drop fibers 133 on the other hand.
[0020] In the multi-wavelength PON system 100, a communication link
between the OLT 110 and the multiple ONUs 120 may include multiple
upstream wavelength channels and multiple downstream wavelength
channels. In a downstream direction, the multiple downstream
wavelength channels also share the optical transmission medium of
the ODN in a wavelength division multiplexing (WDM) manner, each
ONU 120 may work on one of the downstream wavelength channels of
the multi-wavelength PON system 100, and each downstream wavelength
channel may carry downstream services of one or more ONUs 120; the
ONUs 120 that work on a same downstream wavelength channel may
share the downstream wavelength channel in a Time Division Multiple
Access (TDMA) manner. In an upstream direction, the multiple
upstream wavelength channels share the optical transmission medium
of the ODN 130 in a WDM manner, each ONU 120 may work on one of the
upstream wavelength channels of the multi-wavelength PON system
100, and each upstream wavelength channel may carry upstream
services of one or more ONUs 120; the ONUs 120 that work on a same
upstream wavelength channel may share the upstream wavelength
channel in a Time Division Multiple Access (TDMA) manner.
[0021] In this embodiment, as shown in FIG. 2, a description is
given by using an example in which the multi-wavelength PON system
100 has four upstream wavelength channels and downstream wavelength
channels. It should be understood that, in actual application, the
number of upstream and downstream wavelength channels of the
multi-wavelength PON system 100 may also be determined according to
network requirements. For ease of description, in this embodiment,
the four upstream wavelength channels of the multi-wavelength PON
system 100 are separately named an upstream wavelength channel 1
(which uses a first upstream wavelength .lamda.u1), an upstream
wavelength channel 2 (which uses a second upstream wavelength
.lamda.u2), an upstream wavelength channel 3 (which uses a third
upstream wavelength .lamda.u3), and an upstream wavelength channel
4 (which uses a fourth upstream wavelength .lamda.u4); the four
downstream wavelength channels of the multi-wavelength PON system
100 are separately named a downstream wavelength channel 1 (which
uses a first downstream wavelength .lamda.d1), a downstream
wavelength channel 2 (which uses a second downstream wavelength
.lamda.d2), a downstream wavelength channel 3 (which uses a third
downstream wavelength .lamda.d3), and a downstream wavelength
channel 4 (which uses a fourth downstream wavelength
.lamda.d4).
[0022] Each upstream wavelength channel and each downstream
wavelength channel may have a corresponding wavelength channel
identifier (for example, a channel number). That is, there is a
matching relationship between the upstream wavelength channel
identifier and an upstream wavelength of an upstream wavelength
channel identified by the upstream wavelength channel identifier,
and the OLT 110 and the ONUs 120 may learn the upstream wavelength
of the upstream wavelength channel according to the upstream
wavelength channel identifier. Similarly, there is also a
relationship between the downstream wavelength channel identifier
and a downstream wavelength of a downstream wavelength channel
identified by the downstream wavelength channel identifier, and the
OLT 110 and the ONUs 120 may learn the downstream wavelength of the
downstream wavelength channel according to the downstream
wavelength channel identifier.
[0023] In an embodiment, referring to FIG. 2, the OLT 110 may
include an optical coupler 111, a first wavelength division
multiplexer 112, a second wavelength division multiplexer 113,
multiple downstream optical transmitters Tx1-Tx4, multiple upstream
optical receivers Rx1-Rx4, and a processing module 114. The
multiple downstream optical transmitters Tx1-Tx4 are connected to
the optical coupler 111 by using the first wavelength division
multiplexer 112, the multiple upstream optical receivers Rx1-Rx4
are connected to the optical coupler 111 by using the second
wavelength division multiplexer 113, and the coupler 111 is further
connected to the feeder fiber 131 of the ODN 130.
[0024] Transmit wavelengths vary between the multiple downstream
optical transmitters Tx1-Tx4. Each of the downstream optical
transmitters Tx1-Tx4 may correspond to one of the downstream
wavelength channels of the multi-wavelength PON system 100. For
example, the transmit wavelengths of the multiple downstream
optical transmitters Tx1-Tx4 may be .lamda.d1-.lamda.d4
respectively. The downstream optical transmitters Tx1-Tx4 may use
their respective transmit wavelengths .lamda.d1-.lamda.d4 to
transmit downstream data to corresponding downstream wavelength
channels separately, so that the downstream data is received by the
ONUs 120 that work on the downstream wavelength channels.
Correspondingly, receiving wavelengths may vary between the
multiple upstream optical receivers Rx1-Rx4. Each of the upstream
optical receivers Rx1-Rx4 also corresponds to one of the upstream
wavelength channels of the multi-wavelength passive optical network
system 100. For example, the receiving wavelengths of the multiple
upstream optical receivers Rx1-Rx4 may be .lamda.u1-.lamda.u4
respectively. The upstream optical receivers Rx1-Rx4 may use their
respective receiving wavelengths .lamda.u1-.lamda.u4 to receive
upstream data sent by the ONUs 120 that work on the corresponding
upstream wavelength channels.
[0025] The first wavelength division multiplexer 112 is configured
to: perform wavelength division multiplexing processing on the
downstream data that is transmitted by the multiple downstream
optical transmitters Tx1-Tx4 and whose wavelengths are
.lamda.d1-.lamda.d4; and send the downstream data to the feeder
fiber 131 of the ODN 130 through the optical coupler 111, so as to
provide the downstream data for the ONUs 120 by using the ODN 130.
In addition, the optical coupler 111 may further be configured to
provide the second wavelength division multiplexer 113 with the
upstream data that come from the multiple ONUs 120 and whose
wavelengths are .lamda.u1-.lamda.u4, and the second wavelength
division multiplexer 113 may demultiplex the upstream data whose
wavelengths are .lamda.u1-.lamda.u4 to the upstream optical
receivers Rx1-Rx4 to perform data receiving.
[0026] The processing module 114 may be a Media Access Control
(Media Access Control, MAC) module. On the one hand, according to a
downstream wavelength channel on which an ONU 120 works, the
processing module 114 may provide downstream data that is to be
sent to the ONU 120 for a downstream optical transmitter
corresponding to the downstream wavelength channel, so that the
downstream optical transmitter transmits the downstream data to the
wavelength channel; on the other hand, the processing module 114
may also process the upstream data received by each of the upstream
optical receivers Rx1-Rx4.
[0027] Operating wavelengths (including an upstream sending
wavelength and a downstream receiving wavelength) of the ONU 120
are tunable. In a specific embodiment, the ONU 120 may include an
optical coupler 121, a downstream optical receiver 122, an upstream
optical transmitter 123, and a processing module 124. Both the
downstream optical receiver 122 and the upstream optical
transmitter 123 are wavelength-tunable components, and they may be
connected to a drop fiber corresponding to the ONU 120 by using the
optical coupler 121. On the one hand, the optical coupler 121 may
provide the drop fiber 133 of the ODN 130 with the upstream data
sent by the upstream optical transmitter 123, so as to send the
upstream data to the OLT 110 through the ODN 130; on the other
hand, the optical coupler 121 may further provide the downstream
optical receiver 122 with the downstream data sent by the OLT 110
through the ODN 130, so as to perform data receiving.
[0028] The processing module 124 may be a MAC module. On the one
hand, the processing module 124 may control, according to needs,
the downstream optical receiver 122 and the upstream optical
transmitter 123 to perform wavelength adjustment. On the other
hand, the processing module 124 may provide, in a specified
timeslot, the upstream optical transmitter 123 with the upstream
data to be sent to the OLT 110, so that the upstream optical
transmitter 123 sends the upstream data to the OLT 110 through a
corresponding upstream wavelength channel, and the processing
module 124 processes the downstream data received by the downstream
optical receiver 122.
[0029] In the multi-wavelength PON system, because the OLT 110
supports multiple upstream and downstream wavelength channels and
the operating wavelengths of the ONU 120 are tunable, in order to
implement normal registration, a downstream receiving wavelength
and an upstream sending wavelength need to be first configured for
the ONU 120 according to a wavelength capability supported by the
OLT 110 during initialization. A wavelength configuration method
for a multi-wavelength PON system according to an embodiment of the
present invention can ensure correct initialization of an operating
wavelength of an ONU.
[0030] FIG. 3 is a flowchart of a wavelength configuration method
for a multi-wavelength passive optical network according to an
embodiment of the present application. The wavelength configuration
method may include:
[0031] Step S10: An OLT periodically broadcasts, on each downstream
wavelength channel of a multi-wavelength PON system, downstream
wavelength information of each downstream wavelength channel and
information of an upstream wavelength that is available for ONU
registration.
[0032] In one aspect, a MAC module of the OLT on a central office
side may provide the downstream wavelength information of each
downstream wavelength channel for corresponding downstream optical
transmitters Tx1-Tx4 separately, and control the downstream optical
transmitters Tx1-Tx4 to periodically broadcast the downstream
wavelength information to ONUs on a user side through each
downstream wavelength channel. Because each downstream wavelength
channel corresponds to a specific downstream wavelength, in an
embodiment, the downstream wavelength information broadcast by the
OLT on each wavelength channel may be channel identifier
information of the downstream wavelength channel, such as a
downstream wavelength channel number.
[0033] In another aspect, the MAC module of the OLT may further
obtain, with reference to the number of ONUs that are actually
online on each upstream wavelength channel and according to an
algorithm for balancing the numbers of ONUs on wavelength channels,
the upstream wavelength information that is available for ONU
registration, that is, available-upstream-wavelength information.
In addition, the MAC module may provide the upstream wavelength
information for the downstream optical transmitters Tx1-Tx4, so
that the downstream optical transmitters Tx1-Tx4 implement
broadcasting of the available-upstream-wavelength information
simultaneously when broadcasting the downstream wavelength through
each downstream wavelength channel.
[0034] In an embodiment, the downstream wavelength information and
the upstream wavelength information may be carried by an XGPON
transmission convergence (XGTC) frame, a GPON transmission
convergence (GTC) frame or an Ethernet frame (that is, EPON frame)
having a logic link identifier (LLID).
[0035] An example is used, in which an XGTC frame is used to carry
the downstream wavelength information and the upstream wavelength
information. Referring to FIG. 4, the XGTC frame includes an XGTC
frame header and an XGTC payload, where the XGTC frame header
includes an optical network unit identifier (ONU-ID) field, an
indication (Ind) field, a hybrid error correction (HEC) field and a
physical layer operations, administration and maintenance upstream
(PLOAMu) field, where the downstream wavelength information and the
upstream wavelength information may be carried by the Ind field.
For example, a reserved (Reserve) field of 9 bits is reserved in
the Ind field of the XGTC frame header defined in an existing XGPON
standard. In this embodiment, the downstream wavelength information
and the upstream wavelength information may be carried by the
reserved field in the Ind field of the XGTC frame header.
[0036] In another embodiment, the downstream wavelength information
and the upstream wavelength information may be carried by a
physical layer operations, administration and maintenance (PLOAM)
message, an ONT management and control interface (OMCI) message, a
Multi-Point Control Protocol (MPCP) message or an operation,
administration and maintenance (OAM) message. A specific message
format, such as a field value and a field length, may be determined
according to actual needs. Certainly, in another alternative
embodiment, the OLT 110 may also carry a downstream wavelength
switching command by a newly defined message.
[0037] An example is used, in which a PLOAM message is used to
carry the downstream wavelength information and the upstream
wavelength information. Referring to FIG. 5, FIG. 5 is a schematic
diagram of a message format of the PLOAM message. The PLOAM message
usually includes an optical network unit identifier (ONU ID) field,
a message identifier (Message ID) field, a sequence number
(Sequence No) field, a data (Data) field, and an integrity check
(Integrity Check) field. In this embodiment, the downstream
wavelength information and the upstream wavelength information may
be carried in the data field of the PLOAM message. For example, the
PLOAM message may use the format shown in the table below:
TABLE-US-00001 Byte (Octet) Content (Content) 1-2 ONU identifier
(ONU ID) 3 Message identifier (Message ID) 4 Sequence number
(Sequence No) 5-a Downstream wavelength information (OLT Tx
Wavelength) (a + 1)-b Upstream wavelength information (ONU
registration Wavelength) (b + 1)-40 Reserved (Reserved) 41-48
Message integrity check (MIC)
[0038] Step S20: An ONU scans a downstream receiving wavelength,
receives a downstream receiving optical physical parameter, and
establishes a downstream receiving wavelength mapping table, where
an entry of the downstream receiving wavelength mapping table
includes downstream receiving wavelength information, drive current
information of a downstream optical receiver, and a receiving
optical physical parameter of the ONU.
[0039] Specifically, the ONU may scan the downstream receiving
wavelength within a maximum receiving wavelength range of the
wavelength-tunable downstream optical receiver of the ONU. For
example, the ONU adjusts a drive current of the downstream optical
receiver to gradually change the downstream receiving wavelength,
and receives a downstream optical signal broadcast on each
downstream wavelength channel during the process of scanning the
downstream receiving wavelength. In addition, the tunable optical
receiver may provide a MAC module of the ONU with its received
message (such as a PLOAM message) that carries the downstream
wavelength information and the upstream wavelength information, or
a data frame (such as an XGTC frame) that carries the downstream
wavelength information and the upstream wavelength information.
[0040] In an embodiment, the receiving optical physical parameter
of the ONU may be a peak value of a receiving optical current of
the ONU (that is, a photo-generated current of the downstream
optical receiver of the ONU). The ONU detects the receiving optical
current of the ONU during the process of scanning the downstream
receiving wavelength, and searches for the peak value of the
receive optical current of the ONU. When the peak value of the
receive optical current of the ONU is searched out, the ONU may
record a current drive current of the downstream optical receiver
and downstream wavelength information that is of a downstream
wavelength channel on which the ONU is currently located and that
is extracted from a message or a data frame received from the MAC
module, and establish a downstream receiving wavelength mapping
entry according to the foregoing three parameters, that is, the
downstream receiving wavelength mapping entry includes the
downstream receiving wavelength information, the drive current
information of the downstream optical receiver, and the peak value
of the receiving optical current of the ONU.
[0041] In another embodiment, the receiving optical physical
parameter of the ONU may also be a peak value of receive optical
power of the ONU or received signal strength indication (Received
Signal Strength Indication, RSSI) information. The ONU detects the
receive optical power of the ONU or RSSI during the process of
scanning the downstream receiving wavelength, and searches for and
detects a peak value of the receive optical power of the ONU or an
RSSI peak value. When the peak value of the receive optical power
of the ONU or the RSSI peak value is searched out, the ONU may
record a current drive current of the downstream optical receiver
and downstream wavelength information that is of a downstream
wavelength channel on which the ONU is currently located and that
is extracted from a message or a data frame received from the MAC
module, and establish a downstream receiving wavelength mapping
entry according to the foregoing three parameters, that is, the
downstream receiving wavelength mapping entry includes the
downstream receiving wavelength information, the drive current
information of the downstream optical receiver, and the peak value
of the receiving optical current of the ONU or the RSSI peak value.
Certainly, it should be understood that, in another alternative
embodiment, the receiving optical physical parameter of the ONU may
also be another related receiving optical physical parameter of the
ONU. Correspondingly, the ONU detects the physical parameter during
the process of scanning the downstream receiving wavelength, and
establishes a downstream receiving wavelength mapping entry
according to the detected physical parameter.
[0042] By repeating the foregoing process, the downstream receiving
wavelength scanning of the ONU may traverse all downstream
receiving wavelengths supported by the downstream optical receiver
or the whole downstream receiving wavelength range of the
downstream optical receiver, and establish one or more downstream
receiving wavelength mapping entries. After the foregoing
downstream receiving wavelength scanning is completed, the ONU may
establish the downstream receiving wavelength mapping table
including one or more entries, and each entry therein corresponds
to different downstream receiving wavelengths.
[0043] Step S30: The ONU selects one downstream receiving
wavelength, and sets, according to the drive current information of
the downstream optical receiver recorded in a related entry of the
downstream receiving wavelength mapping table, an operating
wavelength of the downstream optical receiver of the ONU to the
selected downstream receiving wavelength.
[0044] For example, after establishing the downstream receiving
wavelength mapping table, the ONU may select one downstream
receiving wavelength according to a preset wavelength configuration
requirement or randomly, and search the downstream receiving
wavelength mapping table to obtain the drive current information of
the downstream optical receiver from an entry corresponding to the
selected downstream receiving wavelength, and adjust the drive
current of the downstream optical receiver according to the drive
current information of the downstream optical receiver, thereby
setting the downstream receiving wavelength of the downstream
optical receiver to the foregoing selected downstream receiving
wavelength.
[0045] Step S40: The ONU scans an upstream sending wavelength, and
reports a registration request to the OLT in a registration
authorization timeslot provided by the OLT.
[0046] In an embodiment, a starting condition of this step may be
set to: the ONU may correctly receive registration authorization
information broadcast by the OLT through the downstream wavelength
channel, but has not been registered normally. An ending condition
of this step may be set to: the ONU registers successfully; or, the
ONU receives an upstream sending wavelength adjustment stop
instruction delivered by the OLT.
[0047] Specifically, the ONU usually does not know a current
upstream sending wavelength of a tunable upstream optical
transmitter of the ONU during initialization, and is not sure
whether an upstream optical signal sent through the current
upstream sending wavelength can be received by the OLT normally.
Therefore, in this embodiment, the ONU may gradually change the
drive current within a value range of drive currents supported by
the upstream optical transmitter of the ONU, so as to scan the
upstream sending wavelength. For example, during the
initialization, the ONU may select one boundary value from the
value range of the drive currents as an initial current value, and
perform a progressive increase or decrease on a basis of the
initial current value by a preset variation until the drive current
value reaches the other boundary value within the value range. In
this process, the upstream sending wavelength of the upstream
optical transmitter is gradually adjusted with the progressive
increase or decrease of the drive current, thereby implementing the
scanning of the upstream sending wavelength of the upstream optical
transmitter. After the drive current value reaches the other
boundary value within the value range, if the foregoing ending
condition is not met at present, the ONU may adjust the drive
current of the upstream optical transmitter to be the original
boundary value (that is, the initial current value) again, and
continue to scan the upstream sending wavelength again.
[0048] During the process of scanning the upstream sending
wavelength, the downstream optical receiver of the ONU may receive,
through the foregoing selected downstream receiving wavelength, the
registration authorization information broadcast by the OLT through
a corresponding downstream wavelength channel. Therefore, the ONU
may notify its upstream optical transmitter that, within the
registration authorization timeslot provided by the OLT for the
ONU, an ONU registration request may be sent to the OLT according
to an upstream sending wavelength corresponding to the drive
current value to which the drive current of the upstream optical
transmitter is currently adjusted.
[0049] After the ONU registration request is sent, the MAC module
of the ONU may further determine whether an ONU identifier (ONU ID)
allocation message fed back by the OLT is received during a preset
period of time. If the ONU ID allocation message cannot be received
during the preset period of time, the MAC module may consider that
the OLT does not support the current upstream sending wavelength of
the upstream optical transmitter (that is, the ONU cannot register
normally when the upstream sending wavelength is used), and may
continue to adjust the drive current of the upstream optical
transmitter according to the foregoing scanning rule, control the
upstream optical transmitter to maintain the foregoing upstream
sending wavelength scanning, and send the ONU registration request
to the OLT again in a next registration authorization timeslot
allocated by the OLT, until the ONU ID allocation message sent by
the OLT is successfully received (that is, the ONU successfully
registers).
[0050] Step S50: The OLT delivers an upstream sending wavelength
adjustment instruction to the ONU, detects a receive optical
physical parameter of the OLT during a process of adjusting the
upstream sending wavelength of the ONU, and establishes an upstream
receiving wavelength mapping table, where an entry of the upstream
receiving wavelength mapping table includes upstream receiving
wavelength information, the receive optical physical parameter of
the OLT, and ONU sequence number information.
[0051] In a specific embodiment, the receiving optical physical
parameter of the OLT may be a peak value of a receiving optical
current of the OLT, a peak value of receiving optical power of the
OLT, or an RSSI peak value. The peak value of the receiving optical
current of the OLT is taken as an example. During the ONU
registration process, the OLT may detect a receiving optical
current of the OLT corresponding to an upstream optical signal sent
by the ONU (that is, a photo-generated current of an upstream
optical receiver of the OLT), and record the receiving optical
current of the OLT. In addition, after the ONU completes
registration, the OLT may increase the number of times of
registration of the ONU on the wavelength channel. In another
aspect, the OLT may deliver the upstream sending wavelength
adjustment instruction to the ONU, so as to instruct the ONU to
fine-tune the upstream sending wavelength according to the upstream
sending wavelength scanning rule in the foregoing step S40. The ONU
may gradually adjust the drive current of the upstream optical
transmitter, so as to implement fine-tuning of the upstream sending
wavelength, until an upstream sending wavelength adjustment stop
instruction delivered by the OLT is received.
[0052] The OLT may detect the photo-generated current for the
upstream optical signal sent by the ONU through a corresponding
upstream wavelength channel during the process of fine-tuning the
upstream sending wavelength of the ONU, thereby obtaining and
recording a value of the receiving optical current of the OLT.
Further, the MAC module of the OLT may find a peak value of the
receiving optical current of the OLT among a series of values of
the receiving optical current of the OLT recorded by the MAC
module, and establish an upstream receiving wavelength mapping
entry according to the peak value of the receiving optical current
of the OLT and upstream wavelength information corresponding to the
peak value. The upstream receiving wavelength mapping entry may
include upstream receiving wavelength information, information
about the peak value of the receiving optical current of the OLT,
and the ONU sequence number information. The upstream receiving
wavelength information may be channel identifier information (such
as a wavelength channel number) of the upstream wavelength channel
or the upstream wavelength information of the wavelength channel
when the OLT detects the peak value of the receiving optical
current, where the upstream optical signal is carried by the
upstream wavelength channel.
[0053] It should be understood that, in another alternative
embodiment, if the receiving optical physical parameter of the OLT
uses the peak value of the receiving optical power of the OLT or
the RSSI peak value or another physical parameter, the OLT may
detect a related physical parameter during the process of
fine-tuning the upstream sending wavelength of the ONU, and the
information about the peak value of the receiving optical current
of the OLT in an upstream receiving wavelength mapping entry
correspondingly established by the OLT is replaced by the peak
value of the receiving optical power of the OLT or the RSSI peak
value or the another physical parameter.
[0054] By repeating the foregoing process, the upstream sending
wavelength scanning of the ONU may traverse all upstream sending
wavelengths supported by the upstream optical transmitter or a
whole upstream sending wavelength range of the upstream optical
transmitter. Therefore, the OLT may establish one or more upstream
receiving wavelength mapping entries. After the foregoing upstream
sending wavelength scanning is completed, the OLT may establish the
upstream receiving wavelength mapping table including one or more
entries, and each entry therein corresponds to different upstream
receiving wavelengths.
[0055] Step S60: The OLT sends the upstream receiving wavelength
information to the ONU, and the ONU establishes an upstream sending
wavelength mapping table according to the upstream receiving
wavelength information, where an entry of the upstream sending
wavelength mapping table includes upstream sending wavelength
information and drive current information of an upstream optical
transmitter.
[0056] For example, when the OLT finds that the ONU performs
registration on one same upstream wavelength channel for the second
time, the MAC module of the OLT may compare a currently detected
value of the receive optical current of the OLT with the recorded
peak value of the receive optical current of the OLT, so as to
determine whether a deviation between them is less than a preset
threshold. If the deviation is less than the threshold, it may be
considered that the current upstream sending wavelength of the ONU
is aligned with the current upstream receiving wavelength of the
OLT, and the OLT may send the upstream wavelength information that
is of the upstream wavelength channel and corresponds to the peak
value of the receiving optical current of the OLT to the ONU. After
the ONU receives the upstream wavelength information, the ONU may
establish a corresponding upstream sending wavelength mapping
table, where an entry of the upstream sending wavelength mapping
table may include the upstream sending wavelength information (that
is, the upstream wavelength information provided by the OLT) and
the drive current information of the upstream optical transmitter
of the ONU.
[0057] When the OLT finds the ONU registers at one same wavelength
channel for the third time, the OLT may consider that the ONU has
completed establishing the upstream sending wavelength mapping
table. In this case, the OLT may send the upstream sending
wavelength scanning stop instruction to the ONU, so as to instruct
the ONU to stop the foregoing upstream sending wavelength scanning.
In addition, the OLT may further reset the number of registration
times of the ONU on the upstream wavelength channel to zero.
[0058] Step S70: The ONU queries, according to the upstream
wavelength information that is broadcast by the OLT downstream and
is available for ONU registration, the drive current information of
the upstream optical transmitter recorded in a related entry of the
upstream sending wavelength mapping table, and sets an upstream
sending wavelength of the upstream optical transmitter according to
the drive current information.
[0059] After the ONU receives the upstream sending wavelength
scanning stop instruction delivered by the OLT, the ONU may query,
according to the upstream wavelength information that is parsed by
the MAC module and is available for ONU registration, the related
entry of the upstream sending wavelength mapping table established
by the ONU; obtain the drive current information of the upstream
optical transmitter recorded in the entry corresponding to the
upstream wavelength information that is provided by the OLT and is
available for ONU registration; and set the drive current of the
upstream optical transmitter according to the drive current
information. Therefore, the upstream sending wavelength of the
upstream optical transmitter is set to the upstream wavelength that
is parsed by the MAC module and is available for ONU
registration.
[0060] Optionally, in a specific embodiment, the wavelength
configuration method for a multi-wavelength passive optical network
may further include:
[0061] Step S80: The ONU detects, according to the downstream
receiving wavelength mapping table, whether a drift occurs on the
downstream receiving wavelength of the downstream optical receiver,
and calibrates the downstream receiving wavelength when the drift
occurs.
[0062] Specifically, during a normal communication process, the ONU
may monitor the receiving optical current of the ONU (or the
receiving optical power of the ONU or the RSSI), and compare a
value of the monitored receiving optical current of the ONU (or a
value of the receiving optical power of the ONU or an RSSI value)
with the peak value of the receiving optical current of the ONU (or
the peak value of the receiving optical power of the ONU or the
RSSI peak value) recorded in the related entry of the downstream
receiving wavelength mapping table. If a deviation between them is
greater than a preset threshold, it is considered that a drift
occurs on the downstream receiving wavelength of the downstream
optical receiver of the ONU. In this case, the ONU may randomly
select one direction to adjust the downstream receiving wavelength
of the downstream optical receiver, and continue to measure the
receiving optical current of the ONU (or the value of the receiving
optical power of the ONU or the RSSI value) during the adjustment
process. If the value of the measured receiving optical current of
the ONU (or the value of the receiving optical power of the ONU or
the RSSI value) is decreased, the downstream receiving wavelength
is adjusted in an opposite direction until a deviation between the
value of the measured receiving optical current of the ONU (or the
value of the receiving optical power of the ONU or the RSSI value)
and the peak value of the receiving optical current of the ONU (or
the peak value of the receiving optical power of the ONU or the
RSSI peak value) is less than the preset threshold.
[0063] Step S90: The OLT monitors, according to the upstream
receiving wavelength mapping table, whether a drift occurs on an
upstream sending wavelength of the ONU, and instructs the ONU to
calibrate the upstream sending wavelength when the drift
occurs.
[0064] Specifically, during a normal communication process, the OLT
may monitor the receiving optical current of the OLT (or the
receiving optical power of OLT or the RSSI), and compare a value of
the monitored receiving optical current of the OLT (or a value of
the receiving optical power of the OLT or an RSSI value) with the
peak value of the receiving optical current of the OLT (or the peak
value of the receiving optical power of the OLT or the RSSI peak
value) recorded in the related entry of the upstream receiving
wavelength mapping table. If a deviation between them is greater
than a preset threshold, it is considered that a drift occurs on
the upstream sending wavelength of the upstream optical transmitter
of the ONU. In this case, the OLT may deliver a wavelength
adjustment instruction to the ONU, so as to instruct the ONU to
randomly select one direction to adjust the upstream sending
wavelength of the upstream optical transmitter. The OLT continues
to measure the receiving optical current of OLT (or the value of
the receiving optical power of the OLT or the RSSI value) during
the process of adjusting the upstream sending wavelength the ONU.
If it is measured that the value of the receiving optical current
of the OLT (or the value of the receiving optical power of the OLT
or the RSSI value) is decreased, the OLT delivers the wavelength
adjustment instruction to the ONU again, so as to instruct the ONU
to adjust the upstream sending wavelength in an opposite direction,
until a deviation between the value of the measured receiving
optical current of the OLT (or the value of the receiving optical
power of the OLT or the RSSI value) and the peak value of the
receiving optical current of the OLT (or the peak value of the
receiving optical power of the OLT or the RSSI peak value) is less
than the preset threshold.
[0065] In the wavelength configuration method for a
multi-wavelength passive optical network according to the
embodiment of the present application, an ONU scans a wavelength
and interacts with an OLT during an initialization process, and
establishes a corresponding wavelength mapping table, so as to
ensure that a transmitting wavelength and a receiving wavelength
configured by the ONU are within a wavelength range supported by
the OLT, thereby implementing normal initialization of the
transmitting wavelength and the receiving wavelength of the ONU. In
another aspect, whether a drift occurs on the transmitting
wavelength and the receiving wavelength of the ONU can be monitored
in real time based on the wavelength mapping table during a normal
communication process, and auto-adjustment is performed when the
drift occurs, thereby ensuring signal receiving quality and
reducing a bit error rate.
[0066] Based on the wavelength configuration method for a
multi-wavelength passive optical network system according to the
foregoing embodiment, the present application further provides a
wavelength configuration apparatus. The wavelength switching
apparatus may be applied to the ONUs 120 in the multi-wavelength
passive optical network system 100 shown in FIG. 2. Referring to
FIG. 6, FIG. 6 is a schematic structural diagram of a wavelength
configuration apparatus 600 for a multi-wavelength passive optical
network system according to an embodiment of the present
application. The wavelength configuration apparatus 600 may
include:
[0067] a receiving module 610, configured to scan a downstream
receiving wavelength, and receive, during the process of scanning
the downstream receiving wavelength, downstream wavelength
information of each downstream wavelength channel that is broadcast
by an OLT separately through each downstream wavelength channel of
a multi-wavelength PON system;
[0068] a wavelength mapping table establishing module 620,
configured to establish a downstream receiving wavelength mapping
table according to the downstream wavelength information, where an
entry of the downstream receiving wavelength mapping table includes
downstream receiving wavelength information, drive current
information of a downstream optical receiver, and a receiving
optical physical parameter of an ONU; and
[0069] a wavelength configuration module 630, configured to select
one downstream wavelength from the downstream wavelength
information broadcast by the OLT, and set, according to the drive
current information of the downstream optical receiver recorded in
a related entry of the downstream receiving wavelength mapping
table, an operating wavelength of the downstream optical receiver
to the selected downstream wavelength.
[0070] In a specific embodiment, the wavelength mapping table
establishing module 620 may include:
[0071] a peak value searching unit 621, configured to search for a
peak value of a receiving optical current of the ONU (or a peak
value of receiving optical power of the ONU or an RSSI peak value)
from a detected receiving optical current of the ONU (or receiving
optical power of the ONU or RSSI) during the process of scanning
the downstream receiving wavelength; and
[0072] an entry establishing module 622, configured to: when the
peak value searching unit searches out the peak value of the
receiving optical current of the ONU (or the peak value of the
receiving optical power of the ONU or the RSSI peak value), record
a current drive current of the downstream optical receiver and
downstream wavelength information of a downstream wavelength
channel corresponding to the peak value of the receiving optical
current of the ONU (or the peak value of the receiving optical
power of the ONU or the RSSI peak value), and establish a
downstream receiving wavelength mapping entry according to the
foregoing three parameters.
[0073] Further, in an embodiment, the wavelength configuration
apparatus 600 may further include:
[0074] a sending module 640, configured to scan an upstream sending
wavelength, and send a registration request to the OLT in a
registration authorization timeslot allocated by the OLT; and
[0075] a control module 650, configured to: determine whether the
receiving module receives an ONU identifier allocation message sent
by the OLT; and if no, control the sending module to send the
registration request to the OLT again in a next registration
authorization timeslot allocated by the OLT, until the receiving
module successfully receives the ONU identifier allocation
message.
[0076] In a specific embodiment, the sending module 640 may
include:
[0077] a drive current adjusting unit 641, configured to select one
boundary value from a value range of drive currents supported by an
upstream optical transmitter as an initial current value, and
adjust a drive current of the upstream optical transmitter by using
a preset variation so as to perform a progressive increase or
decrease; and
[0078] a sending unit 642, configured to send, within the
registration authorization timeslot provided by the OLT for the
ONU, an ONU registration request to the OLT according to an
upstream sending wavelength corresponding to a drive current value
to which the drive current of the upstream optical transmitter is
currently adjusted.
[0079] In an embodiment, the wavelength configuration apparatus 600
may further include:
[0080] a wavelength calibrating module 660, configured to detect,
according to the downstream receiving wavelength mapping table,
whether a drift occurs on a downstream receiving wavelength of the
downstream optical receiver of the ONU, and calibrate the
downstream receiving wavelength when the drift occurs.
[0081] In an embodiment, the receiving module 610 may further be
configured to receive an upstream sending wavelength adjustment
instruction sent by the OLT. In addition, the sending module 640 is
further configured to fine-tune the upstream sending wavelength of
the upstream optical transmitter according to the upstream
wavelength adjustment instruction, so that the OLT detects a
receiving optical current of the OLT (or receive optical power of
the OLT or an RSSI) and establishes an upstream receiving
wavelength mapping table.
[0082] Further, the receiving module 610 is further configured to
receive upstream receiving wavelength information delivered by the
OLT after the upstream receiving wavelength mapping table is
established. In addition, the wavelength mapping table establishing
module 620 may further be configured to establish an upstream
sending wavelength mapping table according to the upstream
receiving wavelength information, where the upstream sending
wavelength mapping table includes upstream sending wavelength
information and drive current information of the upstream optical
transmitter.
[0083] Further, the receiving module 610 may further be configured
to: when the downstream wavelength information broadcast by the OLT
is received, receive upstream wavelength information that is
broadcast by the OLT separately through each downstream wavelength
channel and is available for ONU registration. In addition, the
wavelength configuration module 620 is further configured to query,
according to the upstream wavelength information that is available
for ONU registration, the drive current information of the upstream
optical transmitter recorded in a related entry of the upstream
sending wavelength mapping table, and set the upstream sending
wavelength of the upstream optical transmitter according to the
drive current information.
[0084] It should be understood that the foregoing description is
merely an overview of main functions of each function module of the
wavelength configuration apparatus 600. For a specific working
process of the function modules, reference may be made to the
wavelength configuration method in the foregoing embodiment. The
division into the function modules is mainly based on specific
functions in wavelength configuration. In a specific embodiment,
when the wavelength switching apparatus 600 is applied to the ONU
120 in the multi-wavelength passive optical network system 100
shown in FIG. 2, the receiving module 610 may be implemented by
using the downstream optical receiver 122 and a related driver
module; the sending module 640 may be implemented by using the
upstream optical transmitter 123 and a related driver module; the
wavelength mapping table establishing module 620, the wavelength
configuration module 630, the control module 650, and the
wavelength calibrating module 660 may be implemented by using the
MAC module of the ONU 120. Certainly, in another alternative
embodiment, each function module of the wavelength configuration
apparatus 600 may further be implemented by using another hardware
entity.
[0085] Based on the foregoing descriptions of the embodiments, a
person skilled in the art may clearly understand that the present
invention may be implemented by software in addition to a necessary
hardware platform or by hardware only. Based on such an
understanding, all or the part of the technical solutions of the
present invention contributing to the technology in the background
part may be implemented in the form of a software product. The
computer software product may be stored in a storage medium, such
as a ROM/RAM, a magnetic disk, or an optical disc, and includes
several instructions for instructing a computer apparatus (which
may be a personal computer, a server, or a network apparatus) to
perform the methods described in the embodiments or some parts of
the embodiments of the present invention.
[0086] The foregoing descriptions are merely exemplary specific
implementation manners of the present application, but are not
intended to limit the protection scope of the present application.
Any variation or replacement readily figured out by a person
skilled in the art within the technical scope disclosed in the
present application shall fall within the protection scope of the
present application. Therefore, the protection scope of the present
application shall be subject to the protection scope of the
claims.
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