U.S. patent application number 11/357242 was filed with the patent office on 2006-07-13 for atm communication apparatus and bandwidth control method of the same.
Invention is credited to Yoshihiro Ashi, Hiroshi Hashimoto, Atsushi Iwamura, Noriko Saitoh.
Application Number | 20060153234 11/357242 |
Document ID | / |
Family ID | 26584603 |
Filed Date | 2006-07-13 |
United States Patent
Application |
20060153234 |
Kind Code |
A1 |
Iwamura; Atsushi ; et
al. |
July 13, 2006 |
ATM communication apparatus and bandwidth control method of the
same
Abstract
An ATM communication apparatus and a bandwidth control method
guarantee the minimum cell rate and limit the upper-limit for each
of subscriber terminals, dynamically and fairly distribute the
shared bandwidth based on the register status, and are easily
applied to the system this is already operating the actual service.
A traffic supervisory unit supervises traffic situations of
upstream ATM cells, and a bandwidth controller controls an access
bandwidth of each of the optical network units 3-1 to 3-n based on
receiving of effective ATM cells transmitted by a plurality of the
optical network units 3-1 to 3-n that the traffic supervisory unit
detects. A control table of permission transmits an upstream cell
for maintaining the access bandwidth judged by the bandwidth
controller. A generator of permission to transmit an upstream cell
for generating permission to transmit an upstream cell according to
the access bandwidth judged by the bandwidth controller.
Inventors: |
Iwamura; Atsushi; (Yokohama,
JP) ; Saitoh; Noriko; (Yokohama, JP) ;
Hashimoto; Hiroshi; (Yokohama, JP) ; Ashi;
Yoshihiro; (Yokohama, JP) |
Correspondence
Address: |
MATTINGLY, STANGER, MALUR & BRUNDIDGE, P.C.
1800 DIAGONAL ROAD
SUITE 370
ALEXANDRIA
VA
22314
US
|
Family ID: |
26584603 |
Appl. No.: |
11/357242 |
Filed: |
February 21, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09774715 |
Feb 1, 2001 |
|
|
|
11357242 |
Feb 21, 2006 |
|
|
|
Current U.S.
Class: |
370/468 |
Current CPC
Class: |
H04Q 11/0478 20130101;
H04L 2012/5632 20130101; H04L 2012/5675 20130101; H04L 2012/561
20130101; H04L 2012/5605 20130101 |
Class at
Publication: |
370/468 |
International
Class: |
H04J 3/22 20060101
H04J003/22; H04J 3/16 20060101 H04J003/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 1, 2000 |
JP |
2000-023513 |
Jan 26, 2001 |
JP |
2001-017942 |
Claims
1. A communication apparatus, which determines sizes of
communication bandwidths which are permitted to a plurality of
respective user terminals, issues a permission of transmission of
data to the respective user terminals according to the sizes of the
communication bandwidths, and receives data from the respective
user terminals according to the issued permission of transmission
of data, the communication apparatus comprising: a bandwidth
controller which dynamically determines the communication
bandwidths which are permitted to the respective user terminals; a
bandwidth supervisory unit which supervises the data received from
the respective user terminals, and supervises the communication
bandwidths which the respective user terminals actually use; a
transmission permission issuing unit which respectively issues the
transmission permission to the respective user terminals according
to the communication bandwidths which are permitted to the
respective user terminals, wherein the bandwidth controller, with
respect to the arbitrary user terminal determines: an amount of
bandwidth assigned to the arbitrary user terminal out of a shared
bandwidth which is shared by the plurality of user terminals based
on the communication bandwidth which is permitted to the arbitrary
user terminal by the permission of transmission issued previous
time and the communication bandwidth which the arbitrary user
terminal actually uses and is supervised by the bandwidth
supervisory unit, and a calculated bandwidth which is obtained by
adding the shared bandwidth which is determined to be assigned to
the arbitrary user terminal and a basic bandwidth which is
guaranteed to the arbitrary user terminal as the communication
bandwidth which is permitted to the arbitrary user terminal next
time.
2. A communication apparatus according to claim 1, wherein the
bandwidth controller, with respect to the arbitrary user terminal,
judges whether the arbitrary user terminal requires a communication
bandwidth larger than the communication bandwidth which is
permitted to the arbitrary user terminal according to the
permission of transmission previously issued, by comparing the
communication bandwidth which is permitted to the arbitrary user
terminal according to the permission of transmission issued
previous time with the supervised actually used communication
bandwidth.
3. A communication apparatus according to claim 2, wherein, when
the bandwidth controller judges that the arbitrary user terminal
requires the larger communication bandwidth, the bandwidth
controller determines to assign a portion of the shared bandwidth
which is the communication bandwidth shared by the plurality of
user terminals with the arbitrary user terminal.
4. A communication apparatus according to claim 1, wherein the
bandwidth controller, with respect to the arbitrary user terminal:
calculates an amount of bandwidth which is assigned to the
arbitrary user terminal out of the shared bandwidth, compares the
calculated shared bandwidth with an upper-limit bandwidth which is
an upper-limit value of a size of the shared bandwidth which is
assigned to the arbitrary user terminal, and determines the size of
the shared bandwidth as the shared bandwidth to be assigned to the
arbitrary user terminal when the calculated shared bandwidth is
smaller than the upper-limit bandwidth, and determines the
upper-limit bandwidth as the shared bandwidth to be assigned to the
arbitrary user terminal when the calculated shared bandwidth is
larger than the upper-limit bandwidth.
5. A communication apparatus according to claim 4, wherein the
bandwidth controller, with respect to the arbitrary user terminal:
calculates a sum of the upper-limit bandwidths of the user
terminals to which a portion of the shared bandwidth is assigned,
calculates a rate that the upper-limit bandwidth of the arbitrary
user terminal occupies with respect to the sum of the upper-limit
bandwidths, and calculates a portion of the shared bandwidth which
corresponds to the calculated rate as the shared bandwidth to be
assigned to the arbitrary user terminal.
6. A communication apparatus according to claim 4, wherein the
bandwidth controller: calculates differentials which are values
obtained by subtracting the upper-limit bandwidth from the
calculated shared bandwidth with respect to the user terminals in
which the calculated shared bandwidth is larger than the
upper-limit bandwidth which is set as an upper-limit value of the
size to the shared bandwidth to be assigned, calculates the sum of
the calculated differentials as a surplus bandwidth, and assigns
the surplus bandwidth to the user terminals which require the
further communication bandwidth.
7. A communication apparatus according to claim 1, wherein the
communication apparatus further includes: a timer which measures a
predetermined time and notifies the bandwidth controller each time
the predetermined time elapses, wherein the bandwidth controller,
upon receiving the notification from the timer, newly determines
the communication bandwidths to be permitted next time to the
respective user terminals.
Description
[0001] The present application is a continuation of application
Ser. No. 09/774,715, filed Feb. 1, 2001, the contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an ATM communication
apparatus and a bandwidth control method thereof. More
particularly, the present invention relates to an ATM communication
apparatus and a bandwidths control method thereof that, in a
point/multi-point transmission system, can communicate effectively
by dynamically altering bandwidth assignment among optical network
units according to upstream traffic situation in an optical line
interface in the case where burst signals sent by subscriber
terminals connected to the optical network units respectively have
originated in a Time Division Multiple Access (TDMA) control
technique in which a plurality of the optical network units sends
ATM cells according to permission to transmit an upstream cell
issued by the optical line interface, the ATM communication
apparatus and the bandwidth control method thereof are preferable
for application to the point/multipoint transmission system in
which the optical line interface provides the subscriber terminals
with a plurality of quality of service such as a constant bit rate
service, a best effort service or the like. Note that the present
invention is not limited to the TDMA technique but can be also
applied to the other appropriate multiplex techniques.
[0003] As a prior art of the TDMA control method that performs
bandwidth assignment, for example, a technology is known that is
described in Japanese Patent Laid-Open No. Hei 11(1999)-341037
gazette or the like. This technology is the point/multi-point
transmission system in which the optical line interlace and a
plurality of the opposing optical network units are connected via a
splitter and each of the optical network units transmits cells
respectively with the time division multiple access control of the
optical line interface.
[0004] This dynamical bandwidth sharing technique is characterized
as described below.
(1) In each of the optical network units, the stored cell quantity
of the sending cell buffers and the transmission permit signals of
each of the optical network units are transmitted respectively.
(2) The optical line interface periodically supervises the stored
quantity of the sending cell buffers and the transmission permit
signals of each of the optical network units respectively.
[0005] (3) The optical line interface distributes unused
transmission domains within transmission frames in accordance with
the stored quantity of the sending cell buffers based on the stored
quantity of the sending cell buffers and the transmission permit
signals notified by each of the optical network units respectively
in addition to transmission capacity assigned to the optical
network units that require more transmission capacity.
[0006] In earlier technology, the above-described dynamical
bandwidth sharing control technique allows the service classes with
a high burst such as a personal computer communication or the like
to use transmission capacity effectively.
SUMMARY OF THE INVENTION
[0007] In the foregoing TDMA control technique (the bandwidth
control technique) according to the earlier technology, the
following problems to be solved are further cited.
(1) With Regard to a Distribution Theory 1: the Necessity of a
Minimum Cell Rate
[0008] In the earlier technology, a distribution ratio is decided
only by cell buffer situation of the optical network units. This,
for example, leads to biasedly assigning many bandwidths to the
optical network units that demand extremely many transmission
requests and is thus the technology in which the bandwidth is not
guaranteed depending upon usage situation of other optical network
units. When an actual service operation is taken into
consideration, each of the optical network units does not always
provide only the best effort services such as a personal computer
data communication or the like. In the case where a plurality of
the subscriber terminals are connected to the optical network units
and, for example, a plurality of the classified quality services
are provided simultaneously such as a constant bit rate services
e.g. a leased line or the like, the relatively high-priority best
effort service that transmits voice/image in real time and with
high quality and the relatively low-priority best effort service
e.g. a personal computer data communication or the like, the
minimum cell rate for a constant bit rate service needs to be
guaranteed to each of the optical network units respectively.
Additionally, in the best effort services, there exists what is
called a minimum-cell-rate-guaranteed type of the best effort
service in which the minimum cell rate needs to be guaranteed. The
minimum cell rate for it needs to be guaranteed as well.
(2) With Regard to a Distribution Theory 2: the Necessity of a Peak
Cell Rate and a Fair Distribution Theory
[0009] Furthermore, since in the technique of the earlier
technology, a distribution ratio is decided only by cell buffer
situation, thus it is the technique that does not take any contract
of the optical network units into consideration. In the case where
the best effort service is offered, it is necessary to decide the
charges at the time when the contracts are made with users.
However, in the case of the technology that can freely use the
usable free domain bandwidths like the prior art, it becomes
difficult to curb a tariff inexpensively, which is contrary to
bandwidth efficiency, because differentiation is impossible among
the users. Accordingly, the ATM communication apparatus and the
bandwidth control method thereof are required that can register the
usable peak cell rate that can be used at its maximum as a traffic
parameter and furthermore comprises a fair distribution theory by
weighting in consideration of the contracted quantity with the
users.
(3) With Regard to a Shared Bandwidth:
[0010] The shared bandwidth distributed in the earlier technology
becomes an entire transmission domain within the transmission frame
at its maximum. In the case of offering the best effort services
with different qualities to every optical network unit, even if
there is a quality difference among the best effort services, it is
impossible to differentially distribute each of qualities.
Accordingly, the ATM communication apparatus and the bandwidth
control method thereof are required that comprises the distribution
theory of the shared bandwidth that allows bandwidth sharing to be
performed among the specific optical network units.
(4) Convenience in Introducing the Technology:
[0011] In the foregoing earlier technology, it is preconditioned
that each of the optical network units comprises a function of
transmitting the cell stored quantity of the sending cell buffers
and the transmission permit signals of the optical network units
respectively. In the case of applying of this prior art to the
system that is operating the actual service already, not only the
optical line interface that exists in the station office but also
the optical network units, which are more numerous than the optical
line interface because they are n-multipoint and besides possibly
installed in the users' houses and in buildings, need to be
updated. Therefore, the ATM communication apparatus and the
bandwidth control method thereof are required that can materialize
the bandwidth sharing only by updating the optical line
interface.
[0012] The object of the present invention, in order to solve the
foregoing problems, is to provide the ATM communication apparatus
and the bandwidth control method thereof that comprise the
distribution theory of guaranteeing the minimum cell rate for each
of the subscriber terminals respectively, allowing the bandwidth
control that limits an upper-limit bandwidth, dynamically and
fairly distributing the shared bandwidth based on the register
status, and performing the bandwidth sharing among the specific
optical network units, and that can be easily applied to the system
that is operating the actual service already.
[0013] In accordance with a first solving means, the present
invention provides an ATM communication apparatus comprising:
[0014] a traffic supervisory unit for supervising traffic situation
of upstream ATM cells sent from a plurality of the optical network
units, the traffic supervisory unit having a supervisory unit of a
receiving bandwidth for detecting the receiving bandwidth of ATM
cells transmitted by optical network units and a supervisory unit
of cell overflow situation for detecting a sending buffer in the
optical network units;
[0015] a bandwidth controller having a basic bandwidth assigner for
assigning the basic bandwidth, a shared bandwidth assigner for
assigning a shared bandwidth based on an upper-limit bandwidth and
a receiving bandwidth and cell overflow situation that were
supplied from the traffic supervisory unit and the shared bandwidth
memory for maintaining the assigned shared bandwidth; and
[0016] a generator of permission to transmit an upstream cell for
generating permission to transmit an upstream cell to the optical
network units according to the shared bandwidth assigned by the
bandwidth controller.
[0017] Furthermore, in accordance with a second solving means, the
present invention provides a bandwidth control method that issues
permission to transmit an upstream cell to a plurality of optical
network units, comprising:
[0018] supervising traffic situation of an upstream ATM cells sent
from a plurality of the optical network units;
[0019] detecting receiving bandwidth status and overflow situation
of the ATM cells, which were transmitted from a plurality of the
optical network units;
[0020] judging an access bandwidth of each of the optical network
units according to the receiving bandwidth status and the cell
overflow situation, which were detected, and a basic bandwidth and
an upper-limited bandwidth;
[0021] guaranteeing the basic bandwidth determined for each of the
optical network units;
[0022] distributing the shared bandwidth in the range of the
upper-limit bandwidth where bandwidth distribution is judged to be
necessary for the optical network units that are in the overflow
situation or for the optical network units to which a shared
bandwidth is set beyond the basic bandwidth based on the detected
receiving bandwidth and the cell overflow situation.
[0023] The present invention provides the TDMA control technique
(the ATM communication apparatus and the bandwidth control method
thereof) that consists of: an optical line interface that issues
instruction for permission to transmit an upstream cell to a
plurality of optical network units according to upstream
transmission bandwidths set by each of the optical network units
respectively that the supervisory controller determined; a
plurality of the optical network units that send the ATM cells
according to the permission to transmit an upstream cell issued by
the optical line interface; a plurality of the subscriber terminals
connected to a plurality of the optical network units respectively;
and a supervisory controller that registers each of the
transmission bandwidths of a plurality of the optical network units
for the optical line interface, the optical line interface and a
plurality of the opposing optical network units being connected via
a splitter,
[0024] the optical line interface comprising: an access line
interface unit that receives the ATM cells sent from a plurality of
the optical network units and multiplexed in the splitter; and a
network interface unit that transmits the received ATM cells to the
network,
[0025] the access line interface unit comprising: a transmission
signal terminal that receives the ATM cells sent from a plurality
of the optical network units; and a TDMA controller that issues the
permission to transmit an upstream cell according to the
transmission bandwidth to each of the optical network units that
were set in the supervisory controller,
[0026] the TDMA controller being applied to the point/multi-point
transmission system, which is constituted of: a traffic supervisory
unit for supervising traffic situation of the upstream ATM cells
sent from a plurality of the optical network units; a bandwidth
controller for judging the access bandwidth of each of the optical
network units respectively based on the receiving bandwidth status
and the cell overflow situation of the effective ATM cells
transmitted by a plurality of the optical network unit that the
traffic supervisory unit detected and furthermore according to the
basic bandwidth and the upper-limit bandwidth set by the
supervisory controller; a control table for permission to transmit
an upstream cell for maintaining the access bandwidth judged by the
bandwidth controller; a generator of permission to transmit an
upstream cell for generating permission to transmit an upstream
cell according to the access bandwidth judged by the bandwidth
controller; and a supervisory periodical timing generator for
generating a timing at which judgment processing on the bandwidth
is made in the bandwidth controller according to the predetermined
supervisory period,
[0027] the traffic supervisory unit consisting of: a supervisory
unit of a receiving bandwidth for detecting the receiving bandwidth
of the effective ATM cells transmitted by the optical network
units; and a supervisory unit of cell overflow situation for
detecting cell overflow situation of the sending buffer in the
optical network units,
[0028] the bandwidth controller comprising: a basic bandwidth
assigner for assigning the basic bandwidth set from the supervisory
controller; a basic bandwidth memory for maintaining the basic
bandwidth set from the supervisory controller; an upper-limit
bandwidth memory for maintaining the upper-limit bandwidth set from
the supervisory controller; a shared bandwidth assigner for
assigning the shared bandwidth based on the upper-limit bandwidth
set from the supervisory controller and the receiving bandwidth and
the cell overflow situation sent by the traffic supervisory unit;
and a shared bandwidth memory for maintaining the assigned shared
bandwidth.
[0029] In addition, in the present invention, the shared bandwidth
assigner comprises: a bandwidth fair distributor for assigning the
shared bandwidth based on the receiving bandwidth and the cell
overflow situation sent by the traffic supervisory unit; and an
upper-limit bandwidth limiter for limiting the upper-limit
bandwidth based on the upper-limit bandwidth set from the
supervisory controller.
[0030] Furthermore, the present invention comprises a plurality of
sub-shared bandwidth memories divided further in the shared
bandwidth memory, and the shared bandwidth assigner comprises a
shared bandwidth selector for selecting any one of a plurality of
the sub-shared bandwidths memories for each of the optical network
units respectively.
[0031] In addition, as means for a detecting cell overflow
situation in the supervisory unit of cell overflow situation, the
present invention can comprise means for detecting cell overflow
that compares the receiving bandwidths of the effective cells
received from each of the optical network units respectively and
judges that the cell is in the overflow situation in the case where
the access bandwidth judged by the band controller and the cell
receiving bandwidths of each of the optical network units are the
same or approximate. Alternatively, as means for detecting cell
overflow situation in the supervisory unit of cell overflow
situation, the present invention can comprise means for detecting
invalid cells received from each of the optical network units
respectively and means for detecting cell overflow to judge that
the cell is in the overflow situation in the case where the invalid
cell was not detected.
[0032] Furthermore, the present invention provides the ATM
communication apparatus and the bandwidth control method thereof
consisting of: an optical line interface that issues instruction of
permission to transmit an upstream cell to a plurality of optical
network units according to upstream transmission bandwidths set by
each of the optical network units respectively that the supervisory
controller determined; a plurality of the optical network units
that feed ATM cells according to permission to transmit an upstream
cell issued by the optical line interface; a plurality of the
subscriber terminals connected to a plurality of the optical
network units respectively; and a supervisory controller that
registers each of the transmission bandwidths of a plurality of the
optical network units for the optical line interface, the optical
line interface and a plurality of the opposing optical network
units being connected via the splitter,
[0033] the optical line interface comprising: an access line
interface that receives the ATM cells sent from a plurality of the
optical network units and multiplexed in the splitter; and a
network interface that transmits the received ATM cells to the
network, the access line interface receiving the ATM cells sent
from a plurality of the optical network units and performing TDMA
control to issue the permission to transmit an upstream cell to
each of the optical network units set in the supervisory controller
according to the transmission bandwidth,
[0034] the TDMA control technique being applied to the
point/multi-point transmission system, and comprising the bandwidth
management means, wherein traffic situation of the upstream ATM
cells sent from a plurality of the optical network units is
supervised, the receiving bandwidth status and the cell overflow
situation of the effective ATM cells transmitted by a plurality of
optical network units are detected, and the access bandwidth of
each of the optical network units is judged respectively according
to the receiving bandwidth status and the cell overflow situation
of the effective ATM cells and furthermore the basic bandwidth and
the upper-limit bandwidth set by the supervisory unit,
[0035] the TDMA controlling technique, which makes judgment on the
bandwidth in the bandwidth controller according to the
predetermined supervisory period as its operation timing for
managing the bandwidth, comprising the theory of: guaranteeing the
basic bandwidth that has been determined for each of the optical
network units set from the supervisory controller respectively as
its bandwidth judgment theory, and distributing the shared
bandwidth in the range of the upper-limit bandwidth set from the
supervisory controller; judging the necessity of the bandwidth
distribution for each of the optical network units respectively,
weighting according to the upper-limit bandwidth set from the
supervisory controller and performing distribution as the
distribution theory of the shared bandwidth; and judging that the
bandwidth distribution is necessary for the optical network unit
that is in the cell overflow situation based on the receiving
bandwidth and the cell overflow situation were sent by the traffic
supervisory unit or for the optical network units to which the
shared bandwidth is set beyond the basic bandwidth set from the
supervisory unit as its judgment theory of the necessity of the
bandwidth distribution on every optical network unit.
[0036] Since the receiving bandwidth and the cell overflow
situation transmitted by each of the optical network units are
supervised in the traffic supervisory unit, the present invention
can be applied to a system only by updating the optical line
interface that exists in the station office without updating the
optical network units, in the case of applying the present
invention to the system that is operating the actual service
already. Moreover, the minimum cell rate of each of the optical
network units can be guaranteed by assigning the access bandwidth
to each of the optical network units according to the basic
bandwidth set from the supervisory controller, and the access
bandwidth of each of the optical network units cab be limited by
limiting the access bandwidth to each of the optical network units
according to the upper-limit bandwidth that has been set from the
supervisory controller. In the bandwidth controller, the shared
bandwidth can be dynamically assigned to each of the optical
network units respectively by distributing the shared bandwidth
based on the receiving bandwidth and the cell overflow situation of
the ATM cells at every given period.
[0037] Furthermore, the shared bandwidth can be distributed fairly
based on the register status by assigning the shared bandwidth
according to the receiving bandwidth and the cell overflow
situation of the ATM cells, the basic bandwidth and the upper-limit
bandwidth that were set from the supervisory controller in the
bandwidth fair distributor. The sub-shared bandwidth is
corresponded to a Quality of Service (QoS) by dividing the shared
bandwidth memory to select the sub-shared bandwidth for each of the
optical network units, which enables the QoS to share the bandwidth
among the same optical network units. Additionally, in the case
where a plurality of the QoS are accommodated by one optical
network unit, selection of a plurality of the sub-shared bandwidths
for each of the optical network units allows the bandwidth to be
shared among the optical network units that accommodate the QoS to
which the relative sub-shared bandwidth corresponds.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] For a more complete understanding of the present invention
and the advantages thereof, reference is now made to the following
description taken in conjunction with the accompanying
drawings.
[0039] FIG. 1 is a block diagram showing a system configuration in
accordance with a first embodiment of the present invention.
[0040] FIG. 2 is a block diagram showing a first embodiment of
means for supervising cell overflow at supervisory units of cell
overflow situation 120-1 to n.
[0041] FIG. 3 is a block diagram showing a second embodiment of
means for supervising cell overflow at a supervisory unit of cell
overflow situation 120.
[0042] FIG. 4 is a block diagram showing a multi-divided type of
bandwidth assignment technique comprising a shared bandwidth memory
divided into multi-shared bandwidths.
[0043] FIG. 5 schematically illustrates the concept on transmission
bandwidth segments that are segmented in distributing the access
bandwidths to each of the optical network units in accordance with
the present invention.
[0044] FIG. 6 is a flowchart (1) showing a bandwidth assignment
control of a bandwidth controller 1100.
[0045] FIG. 7 is a flowchart (2) showing a bandwidth assignment
control of the bandwidth controller 1100.
[0046] FIG. 8 is a block diagram showing a configuration of a
point/multipoint transmission system.
[0047] FIG. 9 is a flowchart showing assignment of a bandwidth to a
basic bandwidth and a sub-shared bandwidth in a bandwidth
controller 1100.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0048] Hereinafter, the embodiments of the present invention will
be described in detail with reference to the accompanying drawings.
First, a related technology of the present invention will be
explained.
[0049] FIG. 8 is a block diagram showing a configuration of the
point/multi-point transmission system. Hereinafter, referring to
this drawing, the TDMA bandwidth control method will be described.
In the drawing, this system comprises an optical line interface 1,
a supervisory controller 2, optical network units 3-1 to 3-n,
subscriber terminals 4-1-1 to 4-n-k and a splitter 5. Furthermore,
a constant bit rate register status 520 that the supervisory
controller 2 registers for an access line interface 10,
transmission buffer status 540 that the optical network units 3-1
to 3-n send to the optical line interface 1 and permission to
transmit an upstream cell 560 are shown.
[0050] In the point/multi-point transmission system, the optical
line interface 1 and a plurality of the opposing optical network
units 3-1 to 3-n are connected via the splitter 5. The optical line
interface 1 comprises the access line interface 10 and a network
interface 13. The access line interface 10 comprises a transmission
signal terminal 11 and a TDM controller 550. Furthermore, the TDM
controller 550 includes a generator of permission to transmit an
upstream cell 120, a supervisory unit of transmission request 500
and a bandwidth controller 510. The optical network units 3-1 to
3-n comprise cell transmission buffers 30-1 to 30-n and TDMA
controllers 530-1 to n.
[0051] In the optical line interface 1, permission to transmit an
upstream cell 560 is issued to each of the subscriber terminals in
the generator of a permission to transmit an upstream cell 120
according to the constant bit rate register status 520 that the
supervisory controller 2 registered for the access line interface
10. The optical network units 3-1 to 3-n send upstream signals
according to the permission to transmit an upstream cell 560.
Moreover, the optical network units 3-1 to 3-n notify the optical
line interface 1 of the stored quantity of transmission buffers 30
as transmission buffer status 540. The supervisory unit of
transmission request 500 periodically supervises transmission
buffer status 540, sums up the transmission buffer status 540 sent
from each of the optical network units 3-1 to 3-n, assigns the
shared bandwidth and notifies the generator of the permission to
transmit an upstream cell 120 of an assignment result.
[0052] Next, FIG. 1 is a block diagram showing a system
configuration in accordance with a first embodiment of the present
invention.
[0053] This system comprises an optical line interface 1, a
supervisory controller 2, optical network units 3-1 to 3-n,
subscriber terminals 4-1-1 to 4-n-k and a splitter 5. The optical
line interface 1 comprises an access line interface 10, a network
interface 13, a transmission signal terminal 11 and a TDMA
controller 12. The TDMA controller 12 further comprises a generator
of permission to transmit an upstream cell 120, a control table of
permission to transmit an upstream cell 130, a supervisory
period-timing generator 170, a basic bandwidth assigner 1160, a
basic bandwidth memory 1170, a shared bandwidth memory 1150 and an
upper-limit bandwidth memory 1180. Additionally, what are shown
are: register status 21 of a basic bandwidth/an upper-limit
bandwidth that the supervisory controller 2 registers for the
access line interface 10; upstream cells 140-1 to n sent from each
of the optical network units; receiving bandwidths of upstream
cells 161-1 to n sent from each of the optical network units that a
traffic supervisory unit; cell overflow situation 162-1 to n of
each of the optical network units that the traffic supervisory unit
sent; and a supervisory period timing 171 that the supervisory
period timing generator generated. A traffic supervisory unit 100
includes supervisory units of receiving bandwidths 110-1 to n for
supervising receiving bandwidths of upstream cells sent from each
of the optical network units and supervisory units of cell overflow
situation 120-1 to n for supervising cell overflow situation of
each of the optical network units. Moreover, a bandwidth controller
1100 includes an upper-limit bandwidth limiter 1110 and a fair
distributor of a bandwidth 1120. The optical network units 3-1 to
3-n include cell transmission buffers 30-1 to n.
[0054] In this embodiment, the traffic supervisory unit 100
supervises traffic situation of upstream ATM cells 140-1 to n sent
from a plurality of the optical network units. The bandwidth
controller 1100 judges the access bandwidth of each of the optical
network units based on receiving bandwidth status 161-1 to n and
cell overflow situation 162-1 to n of the effective ATM cells
transmitted by a plurality of the optical network units, which were
detected by the traffic supervisory unit 100, and moreover
according to the basic bandwidth/the upper-limit bandwidth 21 set
by the supervisory controller 2. The control table 130 of
permission to transmit an upstream cell maintains the access
bandwidth judged by the bandwidth controller 1100. The generator
120 of permission to transmit an upstream cell generates permission
to transmit an upstream cell according to the access bandwidth
judged by the bandwidth controller 1100. A supervisory
period-timing generator 170 generates a supervisory period timing
171 according to the predetermined supervisory period timing at
which judgment processing on the bandwidth is performed in the
bandwidth controller 100. The traffic supervisory unit 100
comprises: a supervisory units of a receiving bandwidth 110 for
detecting a receiving bandwidth 161 of the effective ATM cells 140
transmitted by the optical network units 3; and a supervisory unit
of cell overflow situation 120 for detecting cell overflow
situation 162 of sending buffers 30 in the optical network units
3.
[0055] The bandwidth controller 1100 comprises: a basic bandwidth
assigner 1160 for assigning the basic bandwidth set from the
supervisory controller 2; a basic bandwidth memory 1170 for
maintaining the basic bandwidth set from the supervisory controller
2; an upper-limit bandwidth memory 1180 for maintaining the
upper-limit bandwidth set from the supervisory controller 2;
[0056] a shared bandwidth assigner 1101 for assigning the shared
bandwidth based on the upper-limit bandwidth set from the
supervisory controller 2 and the receiving bandwidth 161 and the
cell overflow situation that were sent by the traffic supervisory
unit 100; and a shared bandwidth memory 1150 for maintaining the
shared bandwidth assigned. Additionally, the shared bandwidth
assigner 1101 comprises: a bandwidth fair distributor 1120 for
assigning the shared bandwidth based on the receiving bandwidth and
the cell overflow situation sent by the traffic supervisory unit
100 has fed; and an upper-limit bandwidth limiter 1110 for limiting
the upper-limit bandwidth based on the upper-limit bandwidth set
from the supervisory controller.
[0057] The traffic supervisory unit 100 detects the receiving
bandwidths 161-1 to n and the cell overflow situation 162-1 to n
from the upstream cells sent from each of the optical network units
3-1 to n respectively to send them to the bandwidth controller
1100. The shared bandwidth assigner 1101 of the bandwidth
controller 1100 detects the receiving bandwidth 161 and the cell
overflow situation 162 at the time when the supervisory period
timing generator 170 generates the supervisory period timing 171 to
judge the shared bandwidth assigned to each of the optical network
units 3-1 to n. The shared bandwidth judged in the shared bandwidth
assigner 1101 of the bandwidth controller 1100 is added to the
basic bandwidth sent by the basic bandwidth assigner 1160 and is
registered as the access bandwidth 150 in the control table of
permission to transmit an upstream cell 130. The generator 120 of
permission to transmit an upstream cell issues the permission to
transmit an upstream cell to the optical network units 3 according
to the access bandwidth of each of the optical network units 3
registered in the control table 130 of permission to transmit an
upstream cell.
[0058] In FIG. 2, the first embodiment of the means for supervising
cell overflow at the supervisory units of cell overflow situation
120-1 to n is illustrated. Herein, the supervisory unit of cell
overflow situation 120-n shows a bandwidth-comparison type of cell
overflow detection technique that compares the receiving bandwidth
with the permission to transmit an upstream cell, which was set, to
judge the overflow situation. A bandwidth comparator 121 compares
the access bandwidth to the optical network unit n, which was
already set for the control table of permission to transmit an
upstream cell 130, with the receiving bandwidth of the effective
cell 161-n input from the supervisory unit of a supervisory
receiving bandwidth 110-n to judge the overflow situation in the
case where both are the same or approximate. Note that the
bandwidth comparator 121 may perform the other appropriate
comparison processing to judge the overflow situation.
[0059] In addition, in FIG. 3, the second embodiment of the means
for supervising cell overflow in the supervisory unit of cell
overflow situation 120 is illustrated. Herein, the supervisory unit
of cell overflow 120-n shows an invalid cell detection type of
detection technique cell overflow that judges the overflow
situation by detecting the invalid cell. An invalid cell detector
122 judges the overflow situation in the case where the invalid
cell is not detected in a receiving cell 140.
[0060] Next, the second embodiment of the bandwidth controller 1100
is described. FIG. 4 is a block diagram showing a multi-divided
type of bandwidth assignment technique comprising the shared
bandwidth memory divided into multi-shared bandwidths. A
shared-bandwidth memory 1150 is constituted of a plurality of
sub-shared-bandwidths memories 1151-1 to m, furthermore a
sub-shared bandwidth selector 1140 is provided. In the drawing,
sub-shared bandwidth a selection signal 1130 is shown as a domain
register signal of a sub-shared bandwidth 23. The shared bandwidth
assigner 1101 selects any one of a plurality of the sub-shared
bandwidth memories 1151-1 to m with the sub-shared bandwidth
selection signal 1130. A bandwidth fair distributor 1120 assigns
the sub-shared bandwidth that is to be assigned to the
correspondent optical network units 3 from the sub-shared
bandwidths memories 1151-1 to m selected by the sub-shared
bandwidth selection signal 1130. The supervisory controller 2
registers designation of domain assignment for each of the
sub-shared bandwidths respectively and the optical network units
belonging to each of the sub-shared bandwidths respectively. In the
shared bandwidth assigner 1101, the bandwidth fair distributor 1120
assigns the shared bandwidth to each of the optical network units
3-1 to n to limit the upper-limit bandwidth.
[0061] Hereinafter, the bandwidth assignment technique of the
bandwidth controller 1100 including this shared bandwidth assigner
1101 and the basic bandwidth assigner 1160 is described in detail.
FIG. 5 schematically illustrates the concept on transmission
bandwidth segments segmented in distributing the access bandwidths
to each of the optical network units in the present invention. A
bandwidth division technique in accordance with the present
invention classifies a transmission bandwidth 600 into a basic
bandwidth 630 (hereinafter, referred to as BBW) and a shared
bandwidth 610 (hereinafter, referred to as SBW). The BBW 630 is the
sum total of the basic bandwidths 630-i (hereinafter, referred to
as BBW (i)) of the whole optical network units ranging from 3-1 to
3-n on each of the optical network units 3-i registered by the
supervisory controller 2. On the other hand, the shared bandwidth
610 is the domain other than the basic bandwidth BBW 630 in the
transmission bandwidth 600. The shared bandwidth SWB 610 is divided
into a plurality of the sub-shared bandwidth domains 620-1 to m
(hereinafter, referred to as SBW_1 to m), and each of the
sub-shared bandwidth domains SBW J. to m 620-1 to m include the
shared bandwidth 640-m-i (hereinafter, referred to as EBW_m (i))
that was assigned to each of the optical network units belonging
hereto.
[0062] Additionally, the dynamical assignment bandwidths of each of
the optical network units can be assigned to a plurality of the
sub-shared bandwidths respectively. For example, in the case where
the optical network unit i is assigned to two kinds of the
sub-shared bandwidths, SBW_and SBW_q, the separate dynamical
assignment bandwidths of the optical network unit i become EBW_p
(i) and EBW_q (i) respectively. EBW_p (i) shares the bandwidth with
the other separate dynamical assignment bandwidths in SBW_p. On the
other hand, EBW_q (i) shares the bandwidth with the other separate
dynamical assignment bandwidths in SBW_q. This allows the bandwidth
to be shared among the same QoSs, in the case where a plurality of
the QoSs (p and q in this example) are accommodated in the optical
network unit i.
[0063] FIG. 6 and FIG. 7 illustrate the flowcharts of the bandwidth
assignment control of the bandwidth controller 1100. The bandwidth
assignment technique in accordance with this embodiment is
performed in two stages, which are called a primary distribution
and a secondly distribution respectively. Although the flow shown
in the drawings represents a division theory in the sub-shared
bandwidth SBW_m, description is made in the name of SWB in the
drawing and hereinafter. Reference symbols in the flow are
described. The optical network unit 3 is described in the name of
ONT (Optical Network Terminal) in the flow, and hereinafter the
optical network unit 3 is called ONT. BW_R[ONT] is the receiving
bandwidth received from the correspondent ONT, and 6 1[ONT] is an
identifying flag which sets a value of 1 for the ONT that requires
the primary distribution and a value of 0 for the ONT that does not
require the primary distribution. W1[ONT] represents a distribution
weight on each ONT in the primary distribution. TBW[ONT] is the
upper-limit bandwidth on each ONT set by the supervisory controller
2. Herein, the upper-limit bandwidth is the uppermost bandwidth
that can be assigned from the shared bandwidths SBW, and the
relation between TBW [ONT] and the maximum bandwidth PCR[ONT],
which can be used by the correspondent ONT under the contract, is
defined as follows. Note that the maximum bandwidth PCR[ONT] under
the contract may coincide or correspond with the transmission
bandwidth.
TBW[ONT] PCR[ONT]-BBW[ONT]
[0064] The EBW1[ONT] is the assigned shared bandwidth of the
correspondent ONT resulting from the primary distribution. a 2[ONT]
is the identifying flag which sets a value of 1 for the ONT that
requires the secondary distribution and a value of 0 for the ONT
that does not require the secondary distribution. W2[ONT]
represents a distribution weight on each ONT in the secondary
distribution. 0 EBW is the bandwidth that becomes an assignment
resource in performing the secondary distribution.
[0065] Hereinafter, an operation is described according to this
flowchart. At first, it starts at the time of generating the
supervisory period timing 171 (S000), and the receiving bandwidths
(BW_R[ONT]) and the cell overflow status of all of the ONTs are
acquired in the step S010. In the case where either cell overflow
exists or the assigned shared bandwidth EBW[ONT] assigned to the
correspondent ONT at the previous period is not 0, the primary
distribution is judged to be necessary, thus setting 1[ONT]=1, and
in the case other than this, the primary distribution is judged not
to be necessary, thus setting 5 1[ONT]=0. In the case where the ONT
that requires receiving of the primary distribution does not exist
in the step 5015, the assigned shared bandwidths EBW[ONT] regarding
all of the ONTs are set with 0 in the step 5500. In the case where
the ONT that requires receiving of the primary distribution exists,
the distribution weight W1 is calculated on each ONT respectively
in the step S020. The distribution weight W1 is distributed in
proportion to the upper-limit bandwidth TBW[ONT]. A calculating
equation for the distribution weight W1, for example, is described
as follows. W1[ONT]=TBW[ONT].times..delta.1[ONT]/.SIGMA.(TBW
[ONT].times..delta.1[ONT]) (1) .SIGMA. in the above-described
equation 1 is the total sum on all of the ONTs. The shared
bandwidth assignment to each ONT by the primary distribution
according to the W1 is as follows. EBW1[ONT]=W1[ONT].times.SBW
(2)
[0066] Here in the step S030, confirmation on the distribution
bandwidth is made. Firstly, judgment is made according to the cell
overflow situation, and the operation splits to the step 5510 in
the case where cell overflow exists and to the step 5520 in the
case where no cell overflow exists. In the step 8510, judgment is
made if the assigned shared bandwidth EBW1 [ONT] resulting from the
primary distribution exceeds the upper-limit bandwidth TBW [ONT].
In the case where EBW1[ONT] exceeds TBW [ONT], the secondary
distribution is impossible, thus the secondary distribution flag
.delta. 2[ONT] is set at 0, the surplus bandwidth distributed
excessively is set at A EBW[ONT] that is the assignment resources
in performing the secondary distribution, and the EBW1[ONT] is set
at the upper-limit value TBW[ONT]. On the other hand, in the case
where the EBW1[ONT] does not exceed the TBW[ONT], the secondary
distribution is regarded to be necessary for the correspondent ONT
in the step S830, and thus the secondary distribution flag .delta.
2[ONT] is set at 1.
[0067] On the other hand, in the step S520, the primary
distribution result EBW1[ONT]+the basic bandwidth BBW[ONT] and the
receiving bandwidth BW_R[ONT] are compared, and in the case where
the primary distribution result EBW1 [ONT]+the basic bandwidth
BBW[ONT] exceeds the receiving bandwidth BW_R[ONT], the secondary
distribution is regarded to be unnecessary, thus the secondary
distribution flag .delta. 2[ONT] is set at 0, the surplus bandwidth
distributed excessively is set at .DELTA. EBW[ONT] that is the
assignment resource in performing the secondary distribution, and
EBW1[ONT] is set at the receiving bandwidth BW_R [ONT]--the basic
bandwidth BBW[ONT]. On the other hand, in the case where the
primary distribution result EBW1 [ONT]+the basic bandwidth BBW[ONT]
does not exceed the receiving bandwidth BW_R[ONT], the secondary
distribution is regarded to be necessary for the correspondent ONT,
and thus the secondary distribution flag .delta. 2[ONT] is set at
1.
[0068] On the basis of the secondary distribution flag .delta.
2[ONT] that was judged at the above-described steps, in the case
where the ONT that receives the secondary distribution does not
exist in the step S040, the shared bandwidth EBW [ONT] as the final
result is set at the primary distribution result EBW1 [ONT] in the
step S540.
[0069] Next, in the case where the ONT that receives the secondary
distribution exists, the distribution weight W2 is calculated on
each ONT respectively in the step S050. The distribution weight W2
is distributed in proportion to the upper-limit bandwidth TBW[ONT].
A calculating equation for the distribution weight W2, for example,
is described as follows. W2[ONT]=TBW[ONT].times..delta.
1[ONT].times..delta. 2[ONT]/.SIGMA.(TBW[ONT]1[ONT].times..delta.
1[ONT]).times..delta. 2[ONT]) (3) .SIGMA. in the above-described
equation 3 is the total sum on all of the ONTs. The shared
bandwidth assignment to each ONT by the secondary distribution
according to the W2 is as follows.
EBW2[ONT]=W2[ONT].times..DELTA.EBW (4)
[0070] Here in the step S060 the primary and the secondary
distribution results are aggregated to calculate the assigned
shared bandwidth EBW[ONT] as the final result.
EBW[ONT]=EBW1[ONT]+EBW2[ONT] (5)
[0071] Finally, in the step S070, confirmation of the upper-limit
for the assigned shared bandwidth EBW[ONT] is performed with the
upper-limit bandwidth TBW[ONT] to restrain the upper limit. The
distributed shared bandwidth EBW[ONT] to the ONT calculated in the
above-described steps is set as an output of the shared bandwidth
assigner in the step S080.
[0072] The flowcharts shown in FIG. 6 and FIG. 7 illustrate the
embodiment of bandwidth distribution in specific sub-shared
bandwidths, and next, the operation will be described for assigning
a plurality of the sub-shared bandwidths.
[0073] FIG. 9 is a flowchart illustrating assignment of the
bandwidth to the basic bandwidth and the sub-shared bandwidth in
the bandwidth controller 1100. The basic bandwidth is assigned
preferentially in the step 51000. Next, the shared bandwidth is
assigned, and from the step S1010 on assignment priorities are
given among the sub-shared bandwidths so that the sub-shared
bandwidths with a higher assignment priority are assigned
preferentially and in order. Specifically, the sub-shared
bandwidths are assigned in order (S1010 to S1012) according to a
secondary priority (k=1, 2, 3 . . . ) and the processing finishes
when the assignment is completed (S1013). In this case, for
example, an appropriate memory section is provided to store a
priority in advance, and thus the bandwidth controller 1100 may be
constituted so as to refer to the priority in assigning.
[0074] The flowcharts shown in FIG. 6 and FIG. 7 illustrate the
embodiment of distributing the distribution weight in proportion to
the upper-limit bandwidth TBWIONT1. As another embodiment of the
distribution method, the bandwidth can be assigned in proportion to
the basic bandwidth BBW[ONT] in addition to proportioning it to the
upper-limit bandwidth TBW[ONT]. Additionally, it is possible to
distribute evenly without giving any priority among a plurality of
the ONTs.
[0075] Furthermore, as described above, although the technique of
assigning the bandwidth always to BBW [ONT] was shown, assignment
of the bandwidth can be related to the receiving bandwidth BW_R
[ONT] in another embodiment of BBW[ONT] assignment. Specifically,
in the step S010, in the case where the receiving bandwidth
BW_R[ONT] at the basic bandwidth BBW[ONT] or less, not the BBW[ONT]
but BW_R[ONT] is assigned, and the surplus bandwidth
BBW[ONT]-BW_R[ONT] can be utilized as the shared bandwidth. Thus
the bandwidth can be utilized effectively with the primary
distribution ISBW'=SBW+BBW [ONT]-BW_R[ONTJ J.
[0076] The distribution method proportioned to the upper-limit
bandwidth TBW[ONT] and the distribution method proportioned to the
basic bandwidth BBW[ONT] were shown in the foregoing can be
specified on each of the sub-shared bandwidths. Additionally, with
regard to the basic bandwidth BBW[ONT], the method of always
assigning the bandwidth in a fixed manner and the method of
assigning by relating to the receiving bandwidth BW_R[ONT] were
shown. On the other hand, in the present invention, a plurality of
the classes of the basic bandwidths can be provided independently
at the same time to allow the method for assigning the bandwidth to
specify on each of the basic bandwidths respectively. In this case,
assignment priorities are given among a plurality of the basic
bandwidths to assign the basic bandwidth with a higher priority
preferentially. In the case where the basic bandwidths need to be
referred to in each of the sub-shared bandwidths, a specific
bandwidth is referred to out of a plurality of the basic
bandwidths. In this case, for example, an appropriate memory
section is provided to store a priority in advance, and thus the
bandwidth controller 1100 may be constituted so as to refer to the
priority in assigning.
[0077] The flowcharts shown in FIG. 6, FIG. 7 and FIG. 9 showed an
example applied to the system in which the bandwidths are assigned
to each of the optical network units ONT, which can be applied to
the system in which a plurality of the subscriber contracts exist
in one optical network unit and a unit of assigning the bandwidth
is not assigned to each of the optical network units ONT but is
also independently assigned to each of the subscriber contracts. In
that case, it is applied to the system in which the permission to
transmit an upstream cell is not issued to the optical network unit
ONT by the unit, but issued to the subscriber contract by the unit,
and application is possible without any modification to the
foregoing flowchart. In this case, a memory section storing
appropriate data necessary for assignment of such as an attribute,
an identifier and a priority of each of the subscriber contracts is
provided in advance for one optical network unit ONT, and thus the
bandwidth controller 1100 may be constituted so as to refer to the
data in assigning.
[0078] In accordance with the present invention as described above,
it is possible to provide the ATM communication apparatus and the
bandwidth control method thereof that allows the bandwidth control
to guarantee minimum cell rate and to limit the upper-limit,
dynamically and fairly distributes the shared bandwidths based on
the register status and can be easily applied for the system that
is already operating the actual service by comprising means for:
supervising the receiving bandwidth and the cell overflow status on
each of the optical network units respectively; guaranteeing the
basic bandwidth registered by the supervisory controller;
distributing the shared bandwidth at a ratio according to the
upper-limit bandwidth registered by the supervisory controller; and
restraining with the upper-limit bandwidth.
[0079] Although the preferred embodiments of the present invention
have
[0080] Been described in detail, it should be understood that
various changes, substitutions and alternations can be made therein
without departing from spirit and scope of the inventions as
defined by the appended claims.
* * * * *