U.S. patent application number 11/136440 was filed with the patent office on 2005-10-06 for method to divide upstream timeslots in a time division multiple access system, related line terminator and related network terminator.
This patent application is currently assigned to ALCATEL. Invention is credited to Martin, Claire, Slabbinck, Hans, Van De Voorde, Ingrid Zulma Benoit, Vetter, Peter Johannes.
Application Number | 20050220149 11/136440 |
Document ID | / |
Family ID | 8242234 |
Filed Date | 2005-10-06 |
United States Patent
Application |
20050220149 |
Kind Code |
A1 |
Van De Voorde, Ingrid Zulma Benoit
; et al. |
October 6, 2005 |
Method to divide upstream timeslots in a time division multiple
access system, related line terminator and related network
terminator
Abstract
A method to divide upstream timeslots in a multiple access
system that couples a line terminator (LT) via a tree-like network
to a plurality of network terminators (NT1, NT2, . . . , NT16) and
that distributes downstream data packets by the line terminator to
the plurality of network terminators. The method includes the
following steps: inclusion by the line terminator in a downstream
data packet at a predefined place of a grant (TEA1; TEA2; . . . ;
TEA16) being associated to one of the plurality of network
terminators and distributing that downstream packet, reacting by
the network terminator upon reception and recognition of its own
grant by transmitting an upstream data packet in a predefined
upstream timeslot. In the event when the network terminator is a
lower order network terminator and the predefined place is a
predefined first place, the upstream data packet are transmitted in
a lower order timeslot. In the event when the network terminator is
a higher order network terminator and the predefined place is a
predefined first place, the upstream data packet is transmitted in
one of a plurality of higher order timeslots, where the higher
order timeslots are subslots of a predefined number of higher order
subslots included in the predefined upstream timeslot. In the event
when the network terminator is a higher order network terminator
and the predefined place is a predefined second place, the upstream
data packet is also transmitted in such higher order timeslot.
Inventors: |
Van De Voorde, Ingrid Zulma
Benoit; (Wolvertem, BE) ; Martin, Claire;
(Ukkel, BE) ; Slabbinck, Hans; (Gent, BE) ;
Vetter, Peter Johannes; (Antwerp, BE) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
ALCATEL
|
Family ID: |
8242234 |
Appl. No.: |
11/136440 |
Filed: |
May 25, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11136440 |
May 25, 2005 |
|
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|
09737547 |
Dec 18, 2000 |
|
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6914909 |
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Current U.S.
Class: |
370/498 |
Current CPC
Class: |
H04L 2012/561 20130101;
H04J 3/22 20130101; H04L 2012/5675 20130101; H04L 2012/5615
20130101 |
Class at
Publication: |
370/498 |
International
Class: |
H04L 012/43 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 1999 |
EP |
99403274.6 |
Claims
1. Method to divide upstream timeslots in a multiple access system
that couples a line terminator (LT) via a tree-like network to a
plurality of network terminators (NT1, NT2, . . . , NT16) and that
distributes downstream data packets by said line terminator (LT) to
said plurality of network terminators (NT1, NT2, . . . , NT16),
said method including the steps of: inclusion by said line
terminator (LT) in a downstream data packet at a predefined place
of a grant (TEA1, TEA2, . . . , TEA16) being associated to one of
said plurality of network terminators (NT1, NT2, . . . , NT16) and
distributing said downstream packet, and reacting by each one of
said network terminators (NT1, NT2, NT16) upon reception and
recognition of its own grant by transmitting an upstream data
packet in a predefined upstream timeslot, characterised in that
said step of transmitting includes, in the event when said one of
said network terminators is a lower order network terminator and
said predefined place is a predefined first place, transmitting
said upstream data packet in a lower order timeslot, in the event
when said one of said network terminators is a higher order network
terminator and said predefined place is a predefined first place,
transmitting said upstream data packet in one of a plurality of
higher order timeslots, said higher order timeslots being subslots
of a predefined number of higher order subslots included in said
predefined upstream timeslot, and in the event when said one of
said network terminators is a higher order network terminator and
said predefined place is a predefined second place, transmitting
said upstream data packet in a said higher order timeslot.
2. A line terminator (LT) for realising division of upstream
timeslots in a time division multiple access system that couples
said line terminator (LT) via a tree-like network to a plurality of
network terminators (NT1, NT2, . . . , NT16) and wherein said line
terminator (LT) distributes downstream data packets to said
plurality of network terminators (NT1, NT2, . . . , NT16) said line
terminator (LT) comprising: inclusion means (INC) adapted to
include in a downstream data packet at a predefined first place a
grant (TEA1; TEA2; . . . ; TEA16) associated to one of said
plurality of network terminators, characterized in that said
inclusion means (INC) is further adapted in the event when one of
said plurality of network terminators (NT3) is a higher order
network terminator to include at a predefined second place of said
downstream data packet a grant (TEA3) being associated to said one
of said plurality of network terminators (TEA3).
3. A network terminator (NT3) for use in a time division multiple
access system that couples a line terminator (LT) via a tree-like
network to a plurality of network terminators (NT1, NT2, . . . ,
NT16) including said network terminator (NT3) said network
terminator (NT3) comprising: recognition means (REC) to recognise
its own grant (TEA3) in a downstream packet sent from said line
terminator (LT) to said network terminator (NT3), and transmitting
means (TR) to transmit a data packet in a predefined upstream
timeslot upon recognition of said own grant (TEA3) characterised in
that said network terminator (NT3) is adapted to transmit upstream
data packets at a higher order data packet rate and that therefor
said recognition means (REC) is further adapted to recognise its
own grant (TEA3) at a predefined first place and that said
transmitting means (TR) is adapted, upon recognition by said
recognition means (REC) of said own grant (TEA3) at said predefined
first place to transmit data packet in one of a plurality of higher
order timeslots, said higher order timeslots being a subslot of a
predefined number of higher order subslots included in said
predefined upstream timeslot, and said recognition means (REC)
being further adapted to recognise its own grant (TEA3) at a
predefined second place and that said transmitting means (TR) is
further adapted, upon recognition by said recognition means (REC)
of said own grant (TEA3) at said predefined second place, to
transmit said data packet in a said higher order timeslot.
4. Method according to claim 1, characterized in that said time
division multiple access system is a Passive Optical Network (PON)
system and that said downstream data packets are Physical Layer
Operation and Maintenance (PLOAM) cells.
5. Method according to claim 4, characterized in that said first
predetermined place is a location within said Physical Layer
Operation and Maintenance (PLOAM) cells reserved for so-called
non-idle grants as specified in the ITU-T Recommendation G.983.1,
whereas said second predetermined place is a location within said
Physical Layer Operation and Maintenance (PLOAM) cells reserved to
idle grants as specified in the ITU-T Recommendation G.983.1.
Description
BACKGROUND OF THE INVENTION
[0001] This is a continuation of application Ser. No. 09/737,547
filed Dec. 18, 2000. The entire disclosure of the prior
application, application Ser. No. 09/737,547 is hereby incorporated
by reference.
[0002] The present invention relates to a method to divide upstream
timeslots in a time division multiple access system and to a
related line terminator and a related network terminator.
[0003] Similar methods and related network and line terminators are
already known in the art, e.g., from the "ITU-T Recommendation
G.983.1 (10/98) section 8.3.5". Therein, it is explained how grants
should be included in Physical Layer Operation and Maintenance
(PLOAM) cells for sending from a line terminator in a Passive
Optical Network (PON) system to a plurality of network terminators
of the system to indicate to the network terminators what upstream
time slot they can use for transmission of data to the line
terminator. The systems described in the recommendation are more
specifically 155/155 Mbit/sec and 622(downstream)/155 Mbit/sec
systems wherein upon recognition of its associated identity in a
received grant, a network terminator can use a 155 Mbit/s frame to
send upstream data.
[0004] In order to support higher rates upstream, the same
principle as described above could be used, i.e., sequential
allocation of grants in the PLOAM cells to allow network
terminators to use 622 Mbit/sec upstream timeslots. However, such a
system would not be compatible with a 622/155 Mbit/sec system since
the frame structures would not map.
SUMMARY OF THE INVENTION
[0005] An aspect of the present invention is therefore to provide a
method and a related line terminator and network terminator of the
above known type but which would allow graceful upgrade of the
existing systems to higher upstream speeds.
[0006] According to the invention, this aspect is achieved by means
of a method, a line terminator and a network terminator as
described hereunder. In accordance with the inventive method, the
line terminator includes, at predefined location in a downstream
data packet, a grant associated with one of the plurality of
network terminators and the line terminator distributes the
downstream packet. Each one of the network terminators transmits an
upstream data packet in a predefined upstream timeslot in response
to reception and recognition of its associated grant. The
transmitting step comprises transmitting an upstream data packet in
a lower order timeslot if the network terminator is a lower order
network terminator and the predefined location is a predefined
first location associated with non-idle grants. The transmitting
step further comprises transmitting an upstream data packet in one
of a plurality of higher order timeslots if the network terminator
is a higher order network terminator and the predefined location is
a predefined first location associated with non-idle grants. The
higher order timeslots comprise a predefined number of higher order
subslots included in the predefined upstream timeslot. The upstream
data packet is transmitted in the higher order timeslot if the
network terminator is a higher order network terminator and the
predefined location is a predefined second location associated with
idle grants.
[0007] The inventive line terminator distributes downstream data
packets to a plurality of network terminators and comprises an
insertion device that includes, in a downstream data packet at a
predefined first location, a grant associated with one of the
plurality of network terminators. If a network terminator is a
higher order network terminator, the insertion device includes, at
a predefined second location of the downstream data packet, a grant
which is associated with the one of the plurality of network
terminators.
[0008] The inventive network terminator comprises a detector that
recognizes the grant associated with the network terminator in a
downstream packet sent from a line terminator to the network
terminator. The network terminator further comprises a transmitter
for transmitting a data packet in a predefined upstream timeslot
upon recognition of the associated grant, wherein the network
terminator is adapted to transmit upstream data packets at a higher
order data packet rate. The detector is further adapted to
recognize the associated grant at a predefined first location in
the downstream data packet and the transmitter is adapted, upon
recognition by the deteector of the associated grant, to transmit a
data packet in one of a plurality of higher order timeslots. The
higher order timeslots comprise a predefined number of higher order
subslots included in the predefined upstream timeslot. The detector
is further adapted to recognize the associated grant at a
predefined second location in the downstream data packet and the
transmitter is further adapted, upon recognition of the associated
grant by the detector at the predefined second location in the
downstream data packet, to transmit the data packet in a the higher
order timeslot.
[0009] In the above description, network terminators transmitting
at higher speed, e.g., 622 Mbit/sec., are called higher order
network terminators and network terminators sending at lower
upstream speed, e.g., 155 Mbit/sec, are called lower order network
terminators.
[0010] Indeed, by, in case of higher order network terminators,
using in addition to the normally available grants, i.e., grants
located at a predefined first place, called non-idle grants in the
above Recommendation, additional grants, i.e., grants located at a
predefined second place, in the above Recommendation called idle
grants, and by adequately subdividing the existing upstream
timeslots in subslots, higher rates can be supported whilst still
being able to support the lower order network terminators. For
example, in the case of a combination of a 622/155 Mbit/sec and a
622/622 Mbit/sec system, the network terminators sending at the
former speed will upon receipt of a grant located at the predefined
first place (non-idle grant place) use the complete 155 Mbit/sec
upstream frame, whilst in the latter system, the network
terminators upon receipt of a grant located either at a predefined
first or at a predefined second place (idle grant place) will use a
subframe being one-fourth of the 155 Mbit/sec one.
[0011] Upstream frames used by lower order network terminators are
called lower order timeslots, whilst slots used by a higher order
network terminator are called higher order timeslots, these slots
being in fact subslots of the upstream slots having the size of
lower order timeslots.
[0012] It should further be noticed that the term "including", used
in the claims, should not be interpreted as being limitative to the
means listed thereafter. Thus, the scope of the expression "a
device including means A and B" should not be limited to devices
consisting only of components A and B. It means that with respect
to the present invention, the only relevant components of the
device are A and B.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The above and other aspects and features of the invention
will become more apparent and the invention itself will be best
understood by referring to the following description of an
embodiment taken in conjunction with the accompanying drawings
wherein:
[0014] FIG. 1 shows a block scheme of an embodiment of a time
division multiple access network wherein the method of the
invention is used;
[0015] FIG. 2 shows a downstream frame format and an upstream frame
format used by the time division multiple access network of FIG.
1.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Referring to FIG. 1, a method to divide upstream timeslots
used in a time division multiple access network in order to support
622/155 Mbit/sec as well as 622/622 Mbit/sec will be described. The
working of the time division multiple access network will be
explained by means of a functional description of the blocks shown
in FIG. 1. Based on this description, implementation of the
functional blocks in FIG. 1 will be obvious to a person skilled in
the art and will therefor not be described in detail.
[0017] The time division multiple access network includes a line
terminator LT and a plurality of network terminators NT1, NT2, NT3,
. . . , NT15, NT16. The line terminator LT is coupled to each
network terminator NT1, NT2, NT3, . . . , NT15, NT16 via the
cascade connection of a common transmission link Lc and an
individual user link L1, L2, L3, . . . , L5, L16.
[0018] For example, the time division multiple access network could
be an optical network transporting asynchronous transfer mode ATM
cells over optical fibers from the line terminator LT to the
network terminators NT1, NT2, NT3, . . . , NT15, NT16. The time
division multiple access network broadcasts network terminator
identities, e.g., TEA1, TEA12, TEA16, TEA3, TEA7, . . . or grants
in downstream information packets from the line terminator LT to
the plurality of network terminators NT1, NT2, NT3, . . . , NT15,
NT16. Upon recognition of its associated identity, a network
terminator is allowed to transfer a predetermined amount of
upstream information packets in predetermined upstream timeslots to
the line terminator LT. For example, upon recognition by network
terminator NT3 of its associated identity TEA3 in a downstream
information packet, network terminator NT3 is allowed to send to
the line terminator upstream information packets in predetermined
timeslots.
[0019] The line terminator LT includes a packet formatting module
PFM, inclusion means INC and queuing means Q. The queuing means Q
is coupled to the inclusion means INC, which is included following
this embodiment in the packet formatting module PFM.
[0020] Each network terminator, whereof only network terminator NT3
is shown in detail in order not to overload FIG. 1, includes
recognition means REC and transmitting means TR.
[0021] The functions of each functional blocks of above will be
described in the following paragraphs.
[0022] The line terminator allocates the time slots in a flexible
and dynamically way. Indeed the upstream transfer capacity of the
time division multiple access network is shared amongst the network
terminators NT1, NT2, NT3, . . . , NT15, NT16 based on their needed
and requested upstream bandwidth to transmit upstream information.
This needed upstream bandwidth is requested by the network
terminators NT1, NT2, NT3, . . . , NT15, NT16 to the line
terminator LT. The requested bandwidth is translated by the line
terminator LT in a predetermined number of allocated timeslots.
This is realized by creating according the requested bandwidth of
the network terminators NT1, NT2, NT3, . . . , NT15, NTS16 a stream
of transmit enable addresses or grants which are called in this
application substation identities TEA1, TEA12, TEA16, TEA3, TEA7, .
. . and which correspond to the grants as specified in ITU-T
Recommendation G.983.1. It has to be remarked that the detailed
working of this allocation goes beyond the scope of this invention
and is therefore not described. A detailed description of this
working can be found in the published European patent application
with publication number 0 544 975. The aim is the use of the stream
of substation identities or grants TEA1, TEA12, TEA16, TEA3, TEA7,
. . . to inform the network terminators NT1, NT2, NT3, . . . ,
NT15, NT16 of the allocated timeslots. Following this embodiment
the stream of substation identities or grants TEA1, TEA12, TEA16,
TEA3, TEA7, . . . is provided to the inclusion means INC by the
queuing means Q.
[0023] Physical Layer Operation and Maintenance cells, otherwise
known as PLOAM cells, are also provided to the inclusion means INC.
The inclusion means INC inserts in the PLOAM cells the grants and
the PLOAM cells are then included in the downstream information
packets. In order to explain the subject method, assume that
network terminator NT2 is a lower order network terminator, i.e., a
network terminator sending at 155 Mbit/sec, whilst network
terminator NT3 is a higher order network terminator sending at 622
Mbit/sec and that the downstream speed is 622 Mbit/sec.
[0024] Referring to FIG. 2, the downstream frame format and the
upstream frame format used by the time division multiple access
network of FIG. 1 is shown. As it can be seen on FIG. 2, after 27
ATM cells, a PLOAM cell is inserted.
[0025] Since NT2 is a lower order network terminator, the inclusion
means INC inserts a grant TEA2 for this terminator in PLOAM 1 or
PLOAM 2 at the location of non-idle grants as specified in ITU-T
Recommendation G.983.1, version 10/98 on pages 39 and 41. It is
supposed here as shown in FIG. 2 that at a chosen point in time a
grant for NT2 is included in PLOAM 1. Grants for NT3, which is a
higher order network terminator, are included at the place of
non-idle grants and of idle grants. It is supposed here that grants
are inserted in PLOAMS 1 and 3. How many grants are included
depends as mentioned earlier on the bandwidth requested by the
network terminators. The queuing means Q provides the grants to be
included to the including means INC in a sequence that depends on
the allocated bandwidth. Since the way in which the number and
sequence of allocated grants is determined is outside of the scope
of the current invention, this is not explained in detail. Examples
of how this is done can be found in the earlier mentioned patent
application and in EPA 0854659.
[0026] The PLOAM cell, after inclusion of the network terminator
grants, is shown in FIG. 1 as PLOAM'. The PLOAM' cell is packed by
the packet formatting module PFM into the downstream frame format
and distributed to the plurality of network terminators. A network
terminator has to recognize its associated identity in a received
PLOAM cell in order to be allowed to transfer an upstream
information packet. This is realized by the recognition means REC.
The sending of the upstream information packets is done by the
transmitting means TR. In order not to overload FIG. 1, only for
network terminator NT3 are the recognition means RCE (TEA3) and the
transmitting means (TR) shown. Taking as example the downstream
frame of FIG. 2, NT2 first recognizes its associated identity in a
non-idle grant location of PLOAM 1, and being a lower order network
terminator, it then transfers an information packet in a 155
Mbit/sec timeslot. The subsequent identity transferred by the line
terminator is that of NT3, also in PLOAM 1. Upon recognition of its
associated identity in PLOAM 1 and knowing that it is an higher
order network terminator, NT3 is allowed to transfer an upstream
information packet in a subslot of an 155 Mbit/sec slot being
one-fourth thereof. In order not to have gaps in the upstream
frames, the line terminator has included a subsequent grant for NT3
in PLOAM 3 at the location of an idle grant. Upon recognition of
its identity, NT3 sends an upstream information packet in a
subsequent subslot as shown in FIG. 2. In this way, NT3 is enabled
to send upstream information packets at 622 Mbit/s, whilst NT2
sends at 155 Mbit/s, and only one frame format is used which is
suited for both speeds.
[0027] It should be noted that although the above described network
of the chosen embodiment is an asynchronous transfer mode ATM
network the application of the present invention is not restricted
to the field of ATM. Small modifications, evident to a person
skilled in the art may be applied to the above described embodiment
to adapt it to be method to divide upstream timeslots integrated in
other time division multiple access networks wherein physical layer
operation and maintenance parts are predefined in downstream
information packets.
[0028] While the principles of the invention have been described
above in connection with specific apparatus, it is to be clearly
understood that this description is made only by way of example and
not as a limitation on the scope of the invention, as defined in
the appended claims.
* * * * *