U.S. patent application number 14/656099 was filed with the patent office on 2016-08-11 for bandwidth optimization and hitless transport in dynamic free space optical communications networks.
The applicant listed for this patent is The Boeing Company. Invention is credited to John Meier, Ronald Ward Sackman, Scott Charles Sullivan.
Application Number | 20160233958 14/656099 |
Document ID | / |
Family ID | 54143063 |
Filed Date | 2016-08-11 |
United States Patent
Application |
20160233958 |
Kind Code |
A9 |
Sackman; Ronald Ward ; et
al. |
August 11, 2016 |
BANDWIDTH OPTIMIZATION AND HITLESS TRANSPORT IN DYNAMIC FREE SPACE
OPTICAL COMMUNICATIONS NETWORKS
Abstract
A system for optical communications may include a multiplicity
of optical communications relay platforms that each move above a
surface of the earth. Each relay platform may include a relay link
for communications between adjacent relay platforms. The system may
also include a plurality of ground stations. Each ground station
may be configured to communicate with another of the ground
stations through at least one of the relay platforms. Each ground
station may include an optical communications link for optical
communications with successive relay platforms. The optical link of
each ground station may be configured for handover connections
between the successive relay platforms as the relay platforms move
relative to the earth. The system may additionally include a
network operations center having a link controller. The link
controller may be configured to control switching of the
communications links for hitless transmission between the ground
stations.
Inventors: |
Sackman; Ronald Ward;
(Mountain View, CA) ; Sullivan; Scott Charles;
(Pasadena, CA) ; Meier; John; (St. Charles,
MO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Boeing Company |
Chicago |
IL |
US |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20150270897 A1 |
September 24, 2015 |
|
|
Family ID: |
54143063 |
Appl. No.: |
14/656099 |
Filed: |
March 12, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61968471 |
Mar 21, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04J 14/022 20130101;
H04J 14/0271 20130101; H04B 10/118 20130101; H04J 14/0282
20130101 |
International
Class: |
H04B 10/118 20060101
H04B010/118 |
Claims
1. A system for optical communications, comprising: a multiplicity
of optical communications relay platforms that each move relative
to earth and above a surface of the earth, each optical
communications relay platform comprising a relay link for
communications between adjacent optical communications relay
platforms; a plurality of ground stations at different locations on
the surface of the earth, wherein each ground station is configured
to communicate with another of the ground stations through at least
one of the multiplicity of optical communications relay platforms,
each ground station comprising an optical communications link for
optical communications with successive optical communications relay
platforms, the optical communications link of each ground station
being configured for handover connections between the successive
optical communications relay platforms as the optical
communications relay platforms move relative to the earth; and a
network operations center comprising a link controller, the link
controller being configured to control switching of the optical
communications links and relay links for hitless transmission of
communication signals.
2. The system of claim 1, wherein controlling switching by the link
controller for hitless transmission of communications signals
between the ground stations comprises: implementation of the
optical communications link of each ground station and the handover
connection between the ground stations and the successive optical
communications relay platforms; and implementation of the relay
link between successive optical communications relay platforms, the
link controller switching between the optical communications links
and the relay links in response to movement of the optical
communications relay platforms relative to the earth and
degradation of the optical communication link caused by at least
one factor, the at least one factor comprising weather.
3. The system of claim 2, wherein the handover connection from the
ground stations between successive optical communication relay
platforms comprises a make before break connection.
4. The system of claim 1, wherein each of the multiplicity of
optical communications relay platforms comprises a laser
communications relay platform.
5. The system of claim 1, wherein each of the multiplicity of
optical communications relay platforms comprises one of a low earth
orbit satellite, a medium earth orbit satellite and an unmanned
aerial vehicle.
6. The system of claim 1, further comprising a variable speed
lambda network comprising a plurality of variable speed wavelength
division multiplexing (WDM) lambdas, wherein the link controller is
further configured to control functions comprising: admission of a
variable speed WDM lambda to the variable speed lambda network;
modification of a speed of a particular variable speed WDM lambda;
and optimization of bandwidth of the variable speed WDM
lambdas.
7. The system of claim 6, wherein the variable speed lambda network
further comprises: a provider optical add-drop multiplexer (ADM); a
customer optical ADM, wherein the plurality of variable speed WDM
lambdas provide communications between the provider optical ADM and
the customer optical ADM; and a customer optical ring coupled to
the customer optical ADM.
8. The system of claim 6, wherein the link controller comprises an
algorithm configured to perform a method comprising: receiving a
new request from a customer, the new request comprising one of a
request for a new variable speed WDM lambda or a speed change
request for an existing variable speed WDM lambda; retrieving an
active topology map of the variable speed lambda network from a
database; executing a multi-commodity network flow optimization
based on the active topology map of the variable speed lambda
network; configuring network elements to support the new request in
response to the new request being admitted based on the
multi-commodity network flow optimization, the network elements
comprising a provider optical ADM and the plurality of variable WDM
lambdas; updating bandwidth parameters of a link of the network
topology graph associated with the customer; and notifying the
customer that the new request has been granted and provisioned.
9. The system of claim 1, wherein the optical communication link
comprises a laser communications uplink and each ground station
further comprises: an optical switch for sending and receiving
optical signals from the laser communications uplink; a router for
sending and receiving the optical signals from the optical switch;
and a sensor for detecting an environmental change, wherein the
optical communication link is handed over to a next optical
communications relay platform in response to the environmental
change degrading communications between the ground station and a
current optical communications relay platform below a predetermined
link quality threshold.
10. The system of claim 1, wherein the network operations center
further comprises: a network performance manager polling at least
the plurality of ground stations for a change in quality of the
optical communications link, and to poll at least one external
sensor associated with each ground station for an environmental
change, and the network performance manager further generating a
threshold notification in response to at least one of the change in
quality of the optical communications link exceeding a link quality
threshold and the environmental change exceeding an environmental
threshold; a database configured to receive an environmental change
notification from the at least one external sensor in response to
the environmental change, and to receive a link quality change
notification from a particular ground station in response to the
change in link quality of the optical communications link
associated with the particular ground station, and to receive a
notification in response to the network performance manager
generating the threshold notification; and a correlation engine
associated with the database, the correlation engine transmitting a
signal to the link controller to initiate a link decision process
for switching at least one of the optical communications links and
the relay links in response to a correlation policy match based on
at least one of the change in quality of the communications link,
the environmental change and the threshold notification.
11. The system of claim 10, further comprising an out-of-band
management network for communications between the network
operations center and the ground stations.
12. A system for optical communications, comprising: a variable
speed lambda network, the variable speed lambda network comprising:
a provider optical add-drop multiplexer (ADM); a customer optical
ADM; a plurality of variable speed wavelength division multiplexing
(WDM) lambdas, wherein the plurality of variable speed WDM lambdas
provide communications between the provider optical ADM and the
customer optical ADM; and a link controller, wherein the link
controller is configured to control functions comprising: admission
of a variable speed WDM lambda to the variable speed lambda
network; modification of a speed of a particular variable speed WDM
lambda; and optimization of bandwidth of the variable speed WDM
lambdas.
13. The system of claim 12, wherein the link controller comprises
an algorithm configured to perform a method comprising: receiving a
new request from a customer, the new request comprising one of a
request for a new variable speed WDM lambda or a speed change
request for an existing variable speed WDM lambda; retrieving an
active topology map of the variable speed lambda network from a
database; executing a multi-commodity network flow optimization
based on the active topology map of the variable speed lambda
network; configuring network elements to support the new request in
response to the new request being admitted based on the
multi-commodity network flow optimization, the network elements
comprising a provider optical ADM, a customer optical ADM and the
plurality of variable WDM lambdas; updating bandwidth parameters of
a link of the network topology graph associated with the customer;
and notifying the customer that the new request has been granted
and provisioned.
14. The system of claim 12, further comprising: a multiplicity of
optical communications relay platforms that each move relative to
earth and above a surface of the earth, each optical communications
relay platform comprising a relay link for communications between
adjacent optical communications relay platforms; a plurality of
ground stations at different locations on the surface of the earth,
wherein each ground station is configured to communicate with
another of the ground stations through at least one of the
multiplicity of optical communications relay platforms, each ground
station comprising an optical communications link for optical
communications with successive optical communications relay
platforms, the optical communications link of each ground station
being configured for handover connections between the successive
optical communications relay platforms as the optical
communications relay platforms move relative to the earth; and a
network operations center comprising the link controller, the link
controller being further configured to control switching of the
optical communications links and relay links for hitless
transmission of communication signals.
15. The system of claim 14, wherein controlling switching by the
link controller for hitless transmission of communications signals
between the ground stations comprises: implementation of the
optical communications link of each ground station and the handover
connection between the ground station and the successive optical
communications relay platforms, and implementation of the relay
link between the successive optical communications relay platforms,
the link controller switching between the optical communications
links and the relay links in response to movement of the optical
communications relay platforms relative to the earth and
degradation of the optical communication link.
16. The system of claim 14, wherein the optical communication link
comprises a laser communications uplink and each ground station
further comprises: an optical switch for sending and receiving
optical signals from the laser communications uplink; a router for
sending and receiving the optical signals from the optical switch;
and a sensor for detecting an environmental change, wherein the
optical communication link is handed over to a next optical
communications relay platform in response to the environmental
change degrading communications between the ground station and a
current optical communications relay platform below a predetermined
link quality threshold.
17. The system of claim 14, wherein the network operations center
further comprises: a network performance manager polling at least
the plurality of ground stations for a change in quality of the
optical communications link, and polling at least one external
sensor associated with each ground station for an environmental
change, and the network performance manager further generating a
threshold notification in response to at least one of the change in
quality of the optical communications link exceeding a link quality
threshold and the environmental change exceeding an environmental
threshold; a database configured to receive an environmental change
notification from the at least one external sensor in response to
the environmental change, and to receive a link quality change
notification from a particular ground station in response to the
change in link quality of the optical communications link
associated with the particular ground station, and to receive a
threshold notification in response to the network performance
manager generating the threshold notification; a correlation engine
associated with the database, the correlation engine being
configured to transmit a signal to the link controller to initiate
a link decision process for switching at least one of the optical
communications links and the relay links in response to a
correlation policy match based on at least one of the change in
quality of the communications link, the environmental change and
the threshold notification.
18. A method for admission control and bandwidth optimization in a
variable speed lambda network, comprising: receiving, by a
processor, a new request from a customer, the new request
comprising one of a request for a new variable speed WDM lambda or
a speed change request for an existing variable speed WDM lambda;
retrieving, by the processor, an active topology map of the
variable speed lambda network from a database; executing, by the
processor, a multi-commodity network flow optimization based on the
active topology map of the variable speed lambda network;
configuring, by the processor, network elements to support the new
request in response to the new request being admitted based on the
multi-commodity network flow optimization, the network elements
comprising a provider optical ADM, a customer optical ADM and the
plurality of variable WDM lambdas; updating, by the processor,
bandwidth parameters of a link of the network topology graph
associated with the customer; and notifying, by the processor, the
customer that the new request has been granted and provisioned.
19. A method for dynamically changing free space optical
communication links for hitless transmission, the method
comprising: polling at least a ground station for a change in
quality of an optical communications link from the ground station
to an optical communications relay platform; transmitting a link
quality change notification from a ground station to a database in
response to the change in quality of the optical communications
link; polling at least one external sensor associated with the
ground station for an environmental change; transmitting an
environmental change notification from the at least one external
sensor to the database in response to the environmental change;
generating a notification in response to at least one of the change
in quality of the optical communications link exceeding a link
quality threshold and the environmental change exceeding an
environmental change threshold; transmitting the threshold
notification to the database; and switching at least one of the
optical communications link and a relay link between the optical
communications relay platform and a successive optical
communications relay platform in response to at least one of the
change in quality of the communications link, the environmental
change and the threshold notification.
20. The method of claim 19, further comprising: determining a
correlation policy match based on at least one of the change in
quality of the communications link, the environmental change and
the threshold notification; and transmitting a signal to initiate a
link decision process for switching the at least one of the optical
communications link and the relay link in response to the
correlation policy being matched.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/968,471, filed Mar. 21, 2014.
FIELD
[0002] The present disclosure relates to wireless communications,
and the like, and more particularly to a system and method for
bandwidth optimization and hitless transport in dynamic free space
optical communication networks.
BACKGROUND
[0003] Optical communications channels or links in optical
communications networks may use wavelength division multiplexing
(WDM) lambdas or lambda circuits for carrying multiple two-way
communications simultaneously. Traditionally, WDM lambdas have
defined discrete speeds such as 2.5, 10, 40 and 100 gigabits per
second (Gbps). The use of these discrete values is due to
technology standards and legacy Synchronous Optical Networks
(SONET). Accordingly, there is a need to provide an optical network
capable of variable speed lambdas, i.e. lambdas that can be tuned
to arbitrary speeds such as 3, 11, 42, and 103 Gbps, and a solution
to control and optimize these variable speed lambdas.
[0004] Additionally, free space optical communications (FSOC)
links, that may be used with optical communications networks or may
be part of an optical communications network, are subject to
degradation or loss of communications by weather conditions or
other events. This can be particularly challenging in systems such
as medium/low earth satellites and unmanned aerial vehicles where
the optical link platforms move with respect to the surface of the
earth. Accordingly there is also a need to provide a solution for
hitless communications in an FSOC environment, i.e., bit or packet
loss in the FSOC environment does not perceptibly impact end user
performance
SUMMARY
[0005] In accordance with an embodiment, a system for optical
communications may include a multiplicity of optical communications
relay platforms that each move relative to earth and above a
surface of the earth. Each optical communications relay platform
may include a relay link for communications between adjacent
optical communications relay platforms. The system may also include
a plurality of ground stations at different locations on the
surface of the earth. Each ground station may be configured to
communicate with another of the ground stations through at least
one of the multiplicity of optical communications relay platforms.
Each ground station may include an optical communications link for
optical communications with successive optical communications relay
platforms. The optical communications link of each ground station
may be configured for handover connections between the successive
optical communications relay platforms as the optical
communications relay platforms move relative to the earth. The
system may further include a network operations center that
includes a link controller. The link controller may be configured
to control switching of the optical communications links and relay
links for hitless transmission of communication during handover
between optical communications relay platforms and ground station
link changes.
[0006] In accordance with another embodiment, a system for optical
communications may include a variable speed lambda network. The
variable speed lambda network may include a provider optical
add-drop multiplexer (ADM) and a customer optical ADM. The system
may also include a plurality of variable speed wavelength division
multiplexing (WDM) lambdas. The variable speed WDM lambdas provide
optical communications between the provider optical ADM and the
customer optical ADM. The system may also include a link
controller. The link controller may be configured to control
functions which may include admission of a variable speed WDM
lambda to the variable speed lambda network; modification of a
speed of a particular variable speed WDM lambda; and optimization
of bandwidth of the variable speed WDM lambdas.
[0007] In accordance with an additional embodiment, a method for
admission control and bandwidth optimization in a variable speed
lambda network may include receiving, by a processor, a new request
from a customer. The new request may include one of a request for a
new variable speed WDM lambda or a speed change request for an
existing variable speed WDM lambda. The method may also include
retrieving, by the processor, an active topology map of the
variable speed lambda network from a database and executing a
multi-commodity network flow optimization based on the active
topology map of the variable speed lambda network. The method may
additionally include configuring, by the processor, network
elements to support the new request in response to the new request
being admitted based on the multi-commodity network flow
optimization. The network elements may include a provider optical
ADM, a customer optical ADM and the plurality of variable WDM
lambdas which provide an optical communication link between the
provider optical ADM and the customer optical ADM. The method may
additionally include updating, by the processor, bandwidth
parameters of a link of the network topology graph associated with
the customer. The method may further include notifying, by the
processor, the customer that the new request has been granted and
provisioned.
[0008] In accordance with a further embodiment, a method for
dynamically changing free space optical communication links for
hitless transmission may include polling a ground station for a
change in quality of an optical communications link from the ground
station to an optical communications relay platform. The method may
also include transmitting a link quality change notification from a
ground station to a database in response to the change in quality
of the optical communications link. The method may also include
polling at least one external sensor associated with the ground
station for an environmental change and transmitting an
environmental change notification from the at least one external
sensor to the database in response to the environmental change. The
method may additionally include generating a threshold notification
in response to at least one of the change in quality of the optical
communications link exceeding a link quality threshold and the
environmental change exceeding an environmental change threshold.
The method may also include transmitting the threshold notification
to the database. The method may further include switching at least
one of the optical communications link and a relay link between the
optical communications relay platform and a successive optical
communications relay platform in response to at least one of the
change in quality of the communications link, the environmental
change and the threshold notification.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS
[0009] The following detailed description of embodiments refers to
the accompanying drawings, which illustrate specific embodiments of
the disclosure. Other embodiments having different structures and
operations do not depart from the scope of the present
disclosure.
[0010] FIG. 1 is a block schematic diagram of an example of a
variable speed lambda network in accordance with an embodiment of
the present disclosure.
[0011] FIG. 2 is an example of a method for admission control and
bandwidth optimization in a variable speed lambda network in
accordance with an embodiment of the present disclosure.
[0012] FIG. 3 is a block schematic diagram of an example of a free
space optical communications network including a system for hitless
transmission in accordance with an embodiment of the present
disclosure.
[0013] FIG. 4 is a block schematic diagram of an example of an
out-of-band management network that may be associated with the free
space optical communications network of FIG. 3 in accordance with
an embodiment of the present disclosure.
[0014] FIG. 5 is an example of an implementation for hitless
transmission over a free space optical communications network or
system in accordance with an embodiment of the present
disclosure.
[0015] FIGS. 6A-6C (collectively FIG. 6) are an example of a method
of operation for hitless transmission of the free space optical
communications network of FIG. 3 in accordance with an embodiment
of the present disclosure.
[0016] FIG. 7 is an example of a method of operation of a link
controller for hitless transmission during communications link
changes in accordance with an embodiment of the present
disclosure.
DETAILED DESCRIPTION
[0017] The following detailed description of embodiments refers to
the accompanying drawings, which illustrate specific embodiments of
the disclosure. Other embodiments having different structures and
operations do not depart from the scope of the present disclosure.
Like reference numerals may refer to the same element or component
in the different drawings.
[0018] FIG. 1 is a block schematic diagram of an example of a
variable speed lambda network 100 in accordance with an embodiment
of the present disclosure. The variable speed lambda network 100
may include one or more provider optical add-drop multiplexers
(ADM) 102 and one or more customer optical ADMs 104. A plurality of
variable speed wavelength division multiplexing (WDM) lambdas 103
may provide optical communications between each of the provider
optical ADMs 102 and the customer optical ADMs 104. A customer
optical ring 106 may be coupled to each customer optical ADM 104.
End users or customers 108a-108c may be coupled to the variable
speed lambda network 100 by the customer optical ring 106.
[0019] A link controller 110 or other device may be provided and
may be configured to perform bandwidth optimization and admission
control within the variable speed lambda network 100 or system.
Accordingly, the variable speed lambda network 100 may be
configured to allow a customer 108 to purchase and utilize lambda
bandwidth on a "pay as you grow" basis. For example, the customer
108a may initially start with .lamda..sub.1 which may run at 10
Gbps. After a period of time, the customer 108a may decide to
increase bandwidth to 13 Gbps to support traffic growth in his own
network. The customer 108a would initially connect to the variable
speed lambda network 100 using equipment capable of supporting the
upper bound of his desired or anticipated speed range (e.g. 40 Gbps
or 100 Gbps). However, the customer 108a would pay for only the
speed that he is currently using (e.g. 13 Gbps). The speed would be
controlled or throttled in the variable speed lambda network 100 by
the link controller 110. The link controller 110 may be a processor
or other computer device configured to perform the functions and
operations described herein.
[0020] Referring also to FIG. 2, FIG. 2 is an example of a method
200 for admission control and bandwidth optimization in a variable
speed lambda network in accordance with an embodiment of the
present disclosure. The method 200 may be embodied in and performed
by the link controller 110 in FIG. 1. In block 202, the link
controller, which may also be referred to as an admission
controller, may be initiated in response to receiving a new request
from a customer. The new request may either be a request for a new
lambda or a request for a change in speed of an existing lambda. In
block 204, the new request that is received is a request from the
customer for admission of a new lambda to the variable speed WDM
lambda network. Alternatively, in block 206, the new request is a
speed change request or speed modification request for an existing
variable speed WDM lambda.
[0021] In block 208, an active topology map of the variable speed
lambda network may be retrieved from a database associated with the
link controller 110 or network 100. The active topology map of the
variable speed lambda network may include a representation of each
of the current variable speed lambdas that form the network, the
lambda speed or link bandwidth parameter (gigabits per second)
associated with each lambda and any other parameters associated
with each lambda for admission control of new lambdas and bandwidth
optimization of the variable speed lambdas in the network as
described herein. The active topology map of the variable speed
lambda network may be similar to the exemplary variable speed
lambda network illustrated in FIG. 1.
[0022] In block 210, a multi-commodity network flow optimization
based on the active topology map of the variable speed lambda
network may be executed. Network flow models, such as
multi-commodity network flow optimization and constraint based
routing algorithms, are used for traffic engineering of
communications networks and can assist in determining routing
decisions. Multi-commodity network flow optimization considers
multiple demand pairs with positive demand volumes (i.e. user
traffic) and supports a series of objective functions to achieve
different goals (e.g. minimum cost routing, average delay, etc.).
As demand volumes dynamically change (e.g. new service requests,
re-route due to weather, etc.), inputs and network constraints are
modified to determine routing decisions to achieve the desired
goal.
[0023] The multi-commodity network flow optimization may use one of
several constraint-based optimization formulations. Examples of
constraint-based optimization formulation or techniques that may be
used may include but is not necessarily limited to shortest
path-based routing flow (see below for formula) which is a minimum
cost routing case; average delay optimization which minimizes
average packet delay; link utilization optimization which minimizes
link utilization; Equivalent capacity (see below for formula) which
increases network resource utilization while sustaining an
acceptable quality of service.
[0024] An example of a formulation for minimum cost routing with
non-splittable multi-commodity flow is as follows:
minimize { u } F = k = 1 K p = 1 P k .xi. kp h k u kp ##EQU00001##
subject to p = 1 P k u kp = 1 , k = 1 , 2 , , K ##EQU00001.2## k =
1 K p = 1 P k .delta. kpl h k u kp .ltoreq. c l , l = 1 , 2 , , L
##EQU00001.3## u kp = 0 or 1 , p = 1 , 2 , p k ##EQU00001.4## k = 1
, 2 , K ##EQU00001.5##
[0025] Where K is the number of demand pairs with positive demand
volume; L is the number of links; h.sub.k is the demand volume of
demand identifier k=1, 2, . . . , K; c.sub.l is the capacity of
link t=1, 2, . . . , L; P.sub.k is the number of candidate paths
for demand k, k=1, 2, . . . , K; .delta..sub.kpl is the link path
indicator which is set to 1 if path p for demand pair k uses the
link 1, 0 otherwise; .delta..sub.kp is the nonnegative unit cost of
flow on path p for demand k; and u.sub.kp is the binary decision to
choose a path, where p=path and k=demand pair.
[0026] An example of an equivalent capacity algorithm may include
an admission controller algorithm and customer demand calculation
to reserve bandwidth to keep the loss bounded by a specified
probability such that loss occurs when the number of active
sources, k, transmitting at R bps is such that k*R>C, where C is
the allocated capacity. This example assumes an ON/OFF traffic
model. For N customers, the probability that k customers are active
is given by a binomial distribution, where P.sub.on is the
probability the customer is active:
Binominal Distribution = P ( X = k ) = ( N k ) P on k ( 1 - P on )
N - k ##EQU00002##
[0027] For peak bandwidth allocation, k*R bps would be required to
support k customers. Loss would occur if k+1 customers were
transmitting and k*R bps capacity is available. Peak bandwidth
allocation clearly does not take advantage of statistical
multiplexing by exploiting the OFF period of a customer. Quality of
Service (QoS) can be defined in terms of the probability of
exceeding the available capacity, which must be less than some
defined P.sub.loss value as follows:
QoS Probability=P(k*R>C)<P.sub.loss or
P.sub.looss=Pr(X>k)
[0028] In other words, the probability of k*R being greater than
the allocated capacity must be less than some defined P.sub.loss
value, which is the same as saying P.sub.loss is equal to the
probability of k+1 active customers.
[0029] Referring back to FIG. 2, in block 212, a determination may
be made whether the new variable speed lambda is to be admitted or
the speed of the existing lambda changed based on the
multi-commodity network flow optimization. For example, the new
lambda may not be admitted or granted if there is no capacity for
another lambda or the requested speed is unavailable for some
reason.
[0030] If the new variable speed lambda is not admitted or the
speed change is not permitted, the method 200 may advance to block
214. In block 214, the customer may be notified that the new lambda
request or speed change request was not admitted or granted. The
customer may also be notified of the reason for the request not
being granted. The customer may also be notified of acceptable
parameters in the event the customer may want to reapply. For
example, the customer may have requested a speed increase from 10
Gbps to 20 Gbps; however, the variable speed lambda network may
only be able to support an increase to 13 Gbps.
[0031] If the request for the new variable speed lambda or speed
change is admitted or granted in block 212, the method 200 may
advance to block 216. In block 216, network elements to support the
request for the new variable speed WDM lambda or lambda speed
change may be configured based on the multi-commodity network flow
optimization. The network elements may include the provider optical
ADM 102 in FIG. 1, customer optical ADM 104, the variable WDM
lambda circuit 103 of the customer and any components of these
elements that may need to be configured for the new WDM lambda or
increase in lambda speed.
[0032] In block 218, the link bandwidth parameter associated with
the lambda of the customer may be updated in the network topology
graph. In block 220, the customer may be notified that the new
request has been granted and provisioned. The method 200 may end at
termination 222.
[0033] FIG. 3 is a block schematic diagram of an example of a free
space optical communications network 300 including a system 302 for
hitless transmission in accordance with an embodiment of the
present disclosure. The network 300 may include a multiplicity of
optical communications relay platforms 304 that each move relative
to earth and above a surface of the earth. Each optical
communications relay platform 304 may include a relay link 306 or
cross-link for communications between adjacent optical
communications relay platforms 304.
[0034] The network 300 may also include a plurality of ground
stations 308 at different locations on the surface of the earth.
Each ground station 308 may be configured to communicate with
another of the ground stations 308 through at least one of the
multiplicity of optical communications relay platforms 304 or
simply relay platforms 304. Each ground station 308 may include an
optical communications link 310 or links for optical communications
with the relay platforms 304. The optical communications link 310
may be established by a laser communications device in the ground
station 308. The optical communications link 310 may also be
referred to as a lasercom link, lasercom uplink or lasercom up/down
link. The optical communications link 310 of each ground station
308 may be configured for handover connections between successive
optical communications relay platforms 304 as the relay platforms
304 move relative to the earth and come into view of the ground
station 308 above the horizon of the earth. One or more provider
optical ADMs 102 may be coupled to each ground station 308.
[0035] The ground stations 308 may be configured to form an optical
ring 311 or optical rings. The ground stations 308 that form the
optical ring 311 may communicate with one another via the optical
ring 311. Communications between the ground stations 308 within an
optical ring may utilize WDM. Two optical rings 311 running WDM are
shown in the exemplary optical communications network 300 in FIG.
3.
[0036] Each ground station 308 may be capable of establishing
optical communication links or lasercom uplinks 310 to one or more
the optical communications relay platforms 304 which may be
lasercom relay platforms moving relative to the earth. The optical
communications relay platforms 304 may be airborne, for example
unmanned aerial vehicles (UAVs) or space borne, for example low
earth orbit (LEO) satellite or medium earth orbit (MEO) satellites.
In an exemplary embodiment were the optical communications relay
platforms 304 are LEO or MEO satellites, each ground station 308
may include an optical switch 312 such as a reconfigurable optical
add drop multiplexer (ROADM), a router 314, one or more external
sensors 316, such as all sky weather cameras, and lasercom uplink
equipment 310. Multiple lasercom uplinks 310 may reside at each
ground station 308 to facilitate make-before-break optical
communication connections for handover. An individual ground
station 308 is capable of making a connection with a next or
successive optical communications relay platform 304 in the
orbiting constellation of relay platforms 304 as the next or new
relay platform 304 comes over the horizon and into view of the
ground station 308. The connection to a previous relay platform 304
is maintained with the moving relay constellation and is
subsequently broken after the new optical communications connection
to the next or successive optical communication relay platform
308.
[0037] Lasercom links 310 are sensitive to weather patterns. If a
weather pattern interferes with transmission from one ground node
or ground station 308, the system 302 is capable of making a
connection from a different ground station 308 at a physically
diverse location. The lasercom uplink 310 from the previous ground
station 308 may be broken after the new lasercom uplink connection
from the different ground station 308 to the relay platform 304 is
made. The solid lines, uplink link 305, cross-link 306 and uplink
307 represent an active optical communication links in FIG. 3.
Broken or dashed lines, uplink 309 and uplink 319 represent a
make-before-break communications link. The switch in communications
links may be because of a weather pattern 313 or other degradation
or obstruction of the optical transmission path.
[0038] All link changes are coordinated by a link controller 318.
The link controller 318 may be configured to control switching or
changes of the optical communications links or lasercom uplinks 310
and relay links or cross-links 306 for hitless transmission of
communication signals as described herein. The link controller 318
and forming the make-befire break optical communication links may
define the system 302 for hitless optical communications as
described herein. The link controller 318 may be running at an
operations center 402, with out-of-band connectivity to all devices
in the network 300 as shown in FIG. 4.
[0039] FIG. 4 is a block schematic diagram of an example of an
out-of-band management network 400 that may be associated with the
free space optical communications network 300 of FIG. 3 in
accordance with an embodiment of the present disclosure. Ground
stations 308 may be accessible to the operations center 402 via the
out-of-band network 400 that is separate from the network that
carries end user or customer communications traffic. The operations
center 402 may include the link controller 318, a network event
database 404, a correlation engine 406, and a network performance
management system 408. Operation of these components and other
components of the system 300 in coordination with one another for
hitless communications will be described in more detail with
reference to FIGS. 6A-6C.
[0040] The link controller 318 may be for example a software
defined networking platform such as Floodlight controller operating
on a processor or computing device. Floodlight is open source
software for building software-defined networks. Floodlight is a
trademark of Big Switch Networks. Inc. in the United States other
countries or both.
[0041] The event database 404 may be a commercial platform such as
IBM Tivoli Omnibus or similar database. The correlation engine 406
may be a commercial platform such as IBM Impact or other system.
The performance manager 408 may be a commercial platform such as
IBM Tivoli Network Performance Manager or the like. The operations
center may be instantiated at a single site, or at multiple sites.
IBM, Tivoli Omnibus, IBM Impact and Tivoli Network Performance
Manager are trademarks of International Business Machines
Corporation in the Unites States, other countries or both.
[0042] FIG. 5 is an example of an implementation for hitless
transmission over a free space optical communications network or
system 500 in accordance with an embodiment of the present
disclosure. The network or system 500 may be the same as the
network 300 and system 302 in FIG. 3. The exemplary network or
system 500 includes a constellation consisting of six MEO
satellites 502a-502f moving with respect to the earth's surface.
The satellites 502a-502f provide lasercom links 504-514 to connect
terrestrial WDM rings 516a-516f. Each ring 516a-516f may include a
plurality of ground stations 518. The solid lines 504a-504b,
506a-506c and 508a-508c represent currently active optical links or
connections. The dashed or broken lines 510a-510b, 512a-512c and
514a-514c represent make-before-break optical links or handover
connections. The connection between rings 516a and 516b is serviced
by a single satellite 502f. For example, this might be a link
connecting physically diverse rings in a single continent such as
Australia. The connections between rings 516c-516d and rings
516e-516f span multiple satellites 502, traversing satellite cross
links 506b and 508b. The handover links 510a-510b, 512a-512c and
514a-514c may be established to the same ground stations 518 as
their preceding links 504a-504b, 506a-506c and 508a-508c,
respectively, as in the case of the connection between rings 516e
and 516f. Alternatively the handover links may be established using
different ground stations than their preceding links, as shown for
the connections between rings 516a and 516b and rings 516c and
516d. Handover links may connect to different ground stations than
their preceding links in response to weather patterns or other
changing conditions.
[0043] FIGS. 6A-6C (collectively FIG. 6) are an example of a method
600 of operation for hitless transmission of a free space optical
communications network in accordance with an embodiment of the
present disclosure. The exemplary method 600 may be performed by
components or elements of the network 300 and system 302 in FIG. 3
and components or elements of the network operations center 402 in
FIG. 4. The method 600 is explained as being performed by the
components of the network 300 and system 302 and network operations
center 402, although the invention is not intended to be limited by
the particular exemplary architecture described and other
configurations may be possible in carrying out the functions and
operations described. The method 600 depicted in FIGS. 6A-6C is
divided into functions and operations that may be performed by the
different components or elements of the network 300 and system 302.
Accordingly, FIGS. 6A-6C illustrate functions and operations that
may be performed by external sensors 316 in FIG. 3, optical network
devices, such as components of the ground stations 308, the
performance manger 408, the event database 404 and correlation
engine 406 in FIG. 4, a human operator in FIG. 4, the link
controller 318, lasercom relay platform 304 and router 314 in FIG.
3.
[0044] In block 602, an external sensor 316, such as an all sky
camera, may detect optical link-impacting weather conditions. In
block 606, a notification may be sent by the external sensor 316 to
the event database 404. In block 620, the notification may be
inserted or stored in the database 404.
[0045] In block 608, an optical network device, such as ground
station 308, may detect degradation, such as reduced
signal-to-noise ratio or increased bit error rate, on a lasercom
uplink 310 associated with the optical network device 308. In block
612, a link quality change notification may be sent to the event
database 404 by the optical network device 308 in response to
detecting the change in the quality of the lasercom link that
exceeds a predetermined threshold value. The link quality change
may be inserted or stored in the event database 404 in block
620.
[0046] In blocks 614 and 616, the performance manger 408 may poll
system parameters at regular intervals to detect whether key
performance indicators of interest such as bit error rate, packet
loss, jitter, received signal strength, and/or latency may have
exceeded a threshold value. A threshold violation may be sent to
the event database 404 in response to detection of a performance
indicator exceeding a threshold value in block 618. Accordingly, in
block 614, the performance manager 408 may poll the optical network
device 308 at regular intervals for operating parameters and in
block 610 a response to the poll may be returned to the performance
manager 408.
[0047] In block 616, the performance manager 408 may poll external
sensors 316 at regular intervals to detect any changes in weather
conditions. In block 604, the external sensors 316 may respond to
the poll.
[0048] In block 618, a determination may be made if any of the
parameters, such as those listed above, from the polling have
exceeded a predetermined threshold value. A threshold notification
may be generated and sent to the event database 404 in response to
a parameter exceeding its threshold value.
[0049] In block 622, event processing may analyze the environmental
change information received from the external sensors 316, link
quality change parameters or information from the optical network
device 308 and threshold notification information from the
performance manager 408.
[0050] In block 624, the correlation engine may determine if there
are any correlation policy matches based on the parameters and
information processed in block 622. The method 600 may advance to
block 632 (FIG. 6B) in response to any correlation matches
indicating a change in link conditions, weather conditions or other
changes that may warrant a switch or change in optical
communications links, ground stations or relay platforms. In block
632, a link decision process may be initiated by the link
controller 318. An example of a method of operation of a link
controller to determine link changes for hitless communications
will be described with reference to FIG. 7.
[0051] In FIG. 6B, a human operator 633 may also initiate the link
decision process 630 in response to external data such as weather
reports in block 626 or maintenance schedules in block 628, or the
process may be scheduled to run at regular intervals if the process
is not started by either the event correlation process in blocks
622 and 624 or a human operator 633 within a certain interval.
[0052] In block 634 in FIG. 6C, if the link decision process by the
link controller 318 determines that a link change is required, the
link controller 318 may establish a new circuit or optical link in
the optical network device 308 in block 636 and the lasercom relay
platform 304 in block 638.
[0053] In block 640, a determination may be made by the link
controller 318 if a ground station or node change is needed. If so,
a new ground station or node circuit may be established by the link
controller 318 in the optical network device 308 in block 642 and
the lasercom relay platform 304 in block 644.
[0054] In block 646, a determination may be made whether there has
been a relay platform change, ground station change or link change.
If so, in block 650, the link controller 318 inserts forwarding
table entries in the router 314 to direct traffic to the new
circuit or link, and then tears down the old circuit or link in
block 648. The link controller 318 updates the forwarding tables,
block 650, on the router 314 to send packets over the newly
established circuit, achieving hitless transmission of packets and
any circuit emulation or pseudowire traffic the packets may be
carrying.
[0055] Assuming the system 500 in FIG. 5, these circuit updates
could be implemented for example as new satellites come into view
above the horizon. This approach can be extended to other dynamic
lasercom relay platform systems, such as UAVs and LEO satellites
among others.
[0056] FIG. 7 is an example of a method 700 of operation of a link
controller for hitless transmission during communications link
changes in accordance with an embodiment of the present disclosure.
The method 700 may be used for or as part of the link decision
process in block 632 of FIG. 6B. In block 702, the link decision
process may be initiated. In block 704, a constellation handover
configuration of the optical communications relay platforms may be
retrieved from a database, such as event database 404 in FIG. 4 or
another database associated with the system or network. The
constellation handover configuration may include a current set of
possible optical communications links between the ground stations
and optical communications relay platforms or satellites and
performance metrics associated with the links. Certain links may be
preferred based on their associated performance metrics. Examples
of performance metrics may include but are not necessarily limited
to bit error rate, packet loss, jitter, received signal strength,
total bandwidth, available bandwidth, and/or latency.
[0057] In block 706, a determination may be made whether there are
remaining handovers to determine. If there are remaining handovers
to be determined, the method 700 may advance to block 708. In block
708, for a particular optical communications relay platform, such
as relay platform M, a current optimal ground station for optical
communications with relay platform M may be determined. The current
optimal ground station may be determined based on a combination of
factors, such as for example current weather, terrestrial transport
cost, traffic flow optimization, maintenance schedules and any
other information that may be useful in selecting an optimal ground
station for communications with the relay platform M.
[0058] In block 710, a new optimal communications link, uplink or
up/down link between the ground station and the optical
communications relay platform M may be determined. Optimal links
may be selected based on one or a combination of several factors
including weather and link parameters.
[0059] In block 712, any new optimal optical cross-connect changes
to be implemented on relay platform M may be determined based on
one or a combination of several factors including lasercom relay
platform constellation configuration, available bandwidth and
ground station availability.
[0060] In block 714, the relay platform index M is incremented and
the method 700 returns to block 706. If there is another relay
platform for handover processing, the loop of blocks 708-714 may be
repeated. If there are no other relay platforms for handover
processing, the method 700 may advance to block 716.
[0061] In block 716, a determination may be made if there are
remaining ground stations for which handover may need to be
processed or determined. If there are remaining ground stations for
determining handover, the method 700 may advance to block 718. In
block 718, for a particular ground station, such as ground station
N, identified in the loop for relay platform M as being associated
with relay platform M, a particular handover lasercom head of
ground station N may be identified based on a variety of factors
such as weather and offered traffic load.
[0062] In block 720, any optical cross-connect changes necessary to
implement the selected uplink and/or cross links may be determined
and implemented. In block 722, routing table updates that may be
needed to actualize the new handover circuit in the ground station
N may be determined and entered. Accordingly, the routing table may
be updated to reroute via the new handover circuit.
[0063] In block 724, the ground station index N may be incremented
and the method 700 may return to block 716. If there is another
ground station for handover processing, the method 700 may loop
back through the blocks 718-724. If there are no other ground
stations for handover processing, the method 700 may advance to
block 726. In block 726, the constellation topology database is
updated with the new optical communications link and cross-link
(relay link) or link circuits between the ground station N and
relay platform M and between relay platform M and a next or
successive relay platform M+1. The constellation topology database
is separate from the handover configuration. The constellation
topology database includes the actual set of network links
constituting the topology of the system. The method 700 may end at
termination 728.
[0064] The exemplary method 700 may determine the optimal ground
station uplink to be implemented the next time a relay platform
comes into view over the horizon. The method 700 may also be
extended for use when a ground station optical communications link
or uplink to the same relay platform needs to be changed in near
real time in response to weather and/or other network traffic
conditions. Additionally, as an alternative to establishing a
complete end-to-end circuit prior to handover, communications
traffic may be buffered at one or more ground stations until the
circuit path change is complete.
[0065] The flowchart and block diagrams in the Figures illustrate
the architecture, functionality, and operation of possible
implementations of systems, methods, and computer program products
according to various embodiments of the present invention. In this
regard, each block in the flowchart or block diagrams may represent
a module, segment, or portion of instructions, which comprises one
or more executable instructions for implementing the specified
logical function(s). In some alternative implementations, the
functions noted in the block may occur out of the order noted in
the figures. For example, two blocks shown in succession may, in
fact, be executed substantially concurrently, or the blocks may
sometimes be executed in the reverse order, depending upon the
functionality involved. It will also be noted that each block of
the block diagrams and/or flowchart illustration, and combinations
of blocks in the block diagrams and/or flowchart illustration, can
be implemented by special purpose hardware-based systems that
perform the specified functions or acts or carry out combinations
of special purpose hardware and computer instructions.
[0066] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
embodiments of the invention. As used herein, the singular forms
"a", "an" and "the" are intended to include the plural forms as
well, unless the context clearly indicates otherwise. It will be
further understood that the terms "comprises" and/or "comprising,"
when used in this specification, specify the presence of stated
features, integers, steps, operations, elements, and/or components,
but do not preclude the presence or addition of one or more other
features, integers, steps, operations, elements, components, and/or
groups thereof.
[0067] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed. The description of the present
invention has been presented for purposes of illustration and
description, but is not intended to be exhaustive or limited to
embodiments of the invention in the form disclosed. Many
modifications and variations will be apparent to those of ordinary
skill in the art without departing from the scope and spirit of
embodiments of the invention. The embodiment was chosen and
described in order to best explain the principles of embodiments of
the invention and the practical application, and to enable others
of ordinary skill in the art to understand embodiments of the
invention for various embodiments with various modifications as are
suited to the particular use contemplated.
[0068] Although specific embodiments have been illustrated and
described herein, those of ordinary skill in the art appreciate
that any arrangement which is calculated to achieve the same
purpose may be substituted for the specific embodiments shown and
that embodiments of the invention have other applications in other
environments. This application is intended to cover any adaptations
or variations of the present invention. The following claims are in
no way intended to limit the scope of embodiments of the invention
to the specific embodiments described herein.
* * * * *