U.S. patent application number 17/233996 was filed with the patent office on 2021-08-05 for bandwidth allocation apparatus and bandwidth allocation method.
This patent application is currently assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION. The applicant listed for this patent is NIPPON TELEGRAPH AND TELEPHONE CORPORATION. Invention is credited to Daisuke HISANO, Tatsuya SHIMADA, Hiroyuki UZAWA.
Application Number | 20210243127 17/233996 |
Document ID | / |
Family ID | 1000005523497 |
Filed Date | 2021-08-05 |
United States Patent
Application |
20210243127 |
Kind Code |
A1 |
HISANO; Daisuke ; et
al. |
August 5, 2021 |
Bandwidth Allocation Apparatus And Bandwidth Allocation Method
Abstract
A bandwidth allocation apparatus includes: a traffic starting
position detection unit that detects a start timing of burst
traffic on the basis of the traffic information; a traffic
information extraction unit that extracts information on a traffic
amount of each of a plurality of traffic allocation periods from
the traffic information extracted for each lower-level apparatus; a
traffic amount estimation unit that calculates an average value of
the traffic amount in the traffic allocation periods on the basis
of the information on the traffic amount that the traffic
information extraction unit has extracted for each lower-level
apparatus; and a bandwidth allocation unit that allocates a first
bandwidth which is an allocation bandwidth based on the average
value calculated by the traffic amount estimation unit to the
terminating apparatus from the start timing detected by the traffic
starting position detection unit.
Inventors: |
HISANO; Daisuke;
(Yokosuka-shi, JP) ; UZAWA; Hiroyuki; (Atsugi-shi,
JP) ; SHIMADA; Tatsuya; (Yokosuka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIPPON TELEGRAPH AND TELEPHONE CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
NIPPON TELEGRAPH AND TELEPHONE
CORPORATION
Tokyo
JP
|
Family ID: |
1000005523497 |
Appl. No.: |
17/233996 |
Filed: |
April 19, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16483763 |
Aug 6, 2019 |
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PCT/JP2018/003168 |
Jan 31, 2018 |
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17233996 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 5/0064 20130101;
H04L 5/0094 20130101; H04L 47/22 20130101 |
International
Class: |
H04L 12/815 20060101
H04L012/815; H04L 5/00 20060101 H04L005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 13, 2017 |
JP |
2017-024284 |
Claims
1.-9. (canceled)
10. A relay transmission system that accommodates a communication
system configured to perform radio communication according to a TDD
scheme, the relay transmission system comprising: a traffic
information acquisition unit configured to acquire traffic
information indicating a traffic amount of communication that a
lower-level apparatus performs via a terminating apparatus; a
traffic amount estimation unit configured to calculate a surplus
bandwidth in an uplink from the traffic information; and a
newly-connected terminating apparatus authentication unit
configured to set an activation window in which a signal for
allowing a newly-connected terminating apparatus to send an
authentication request to a terminal station apparatus is
transmitted in the surplus bandwidth in the uplink.
11. The relay transmission system according to claim 10, wherein
the traffic amount estimation unit is configured to calculate the
surplus bandwidth in the uplink based on a test pattern transmitted
from the communication system.
12. The relay transmission system according to claim 10, further
comprising a traffic starting position detection unit configured to
search for only a starting position of burst traffic from the
communication system and determine existence or non-existence of
the burst traffic, wherein if the traffic starting position
detection unit has determined the non-existence of the burst
traffic, the traffic amount estimation unit calculates a bandwidth
in which the burst traffic is nonexistent as the surplus bandwidth
in the uplink.
13. The relay transmission system according to claim 11, further
comprising a traffic starting position detection unit configured to
search for only a starting position of burst traffic from the
communication system and determine existence or non-existence of
the burst traffic, wherein if the traffic starting position
detection unit has determined the non-existence of the burst
traffic, the traffic amount estimation unit calculates a bandwidth
in which the burst traffic is nonexistent as the surplus bandwidth
in the uplink.
14. A relay transmission system that accommodates a communication
system configured to perform radio communication according to a TDD
scheme, the relay transmission system comprising: a traffic
information acquisitor configured to acquire traffic information
indicating a traffic amount of communication that a lower-level
apparatus performs via a terminating apparatus; a traffic amount
estimator configured to calculate a surplus bandwidth in an uplink
from the traffic information; and a newly-connected terminating
apparatus authenticator configured to set an activation window in
which a signal for allowing a newly-connected terminating apparatus
to send an authentication request to a terminal station apparatus
is transmitted in the surplus bandwidth in the uplink, wherein each
of the traffic information acquisitor, the traffic amount
estimator, and the newly-connected terminating apparatus
authenticator is implemented by: i) computer executable
instructions executed by at least one processor, ii) at least one
circuit, or iii) a combination of computer executable instructions
executed by at least one processor and at least one circuit.
15. The relay transmission system according to claim 14, wherein
the traffic amount estimator is configured to calculate the surplus
bandwidth in the uplink based on a test pattern transmitted from
the communication system.
16. The relay transmission system according to claim 14, further
comprising a traffic starting position detector configured to
search for only a starting position of burst traffic from the
communication system and determine existence or non-existence of
the burst traffic, wherein if the traffic starting position
detector has determined the non-existence of the burst traffic, the
traffic amount estimator calculates a bandwidth in which the burst
traffic is nonexistent as the surplus bandwidth in the uplink, and
the traffic starting position detector is implemented by: i)
computer executable instructions executed by at least one
processor, ii) at least one circuit, or iii) a combination of
computer executable instructions executed by at least one processor
and at least one circuit.
17. The relay transmission system according to claim 15, further
comprising a traffic starting position detector configured to
search for only a starting position of burst traffic from the
communication system and determine existence or non-existence of
the burst traffic, wherein if the traffic starting position
detector has determined the non-existence of the burst traffic, the
traffic amount estimator calculates a bandwidth in which the burst
traffic is nonexistent as the surplus bandwidth in the uplink, and
the traffic starting position detector is implemented by: i)
computer executable instructions executed by at least one
processor, ii) at least one circuit, or iii) a combination of
computer executable instructions executed by at least one processor
and at least one circuit.
18. A relay transmission method in a relay transmission system that
accommodates a communication system configured to perform radio
communication according to a TDD scheme, the relay transmission
method comprising: acquiring traffic information indicating a
traffic amount of communication that a lower-level apparatus
performs via a terminating apparatus; calculating a surplus
bandwidth in an uplink from the traffic information; and setting an
activation window in which a signal for allowing a newly-connected
terminating apparatus to send an authentication request to a
terminal station apparatus is transmitted in the surplus bandwidth
in the uplink.
Description
TECHNICAL FIELD
[0001] The present invention relates to a bandwidth allocation
apparatus and a bandwidth allocation method.
[0002] This application claims priority to and the benefit from
Japanese Patent Application No. 2017-024284, filed on Feb. 13,
2017, the contents of which are hereby incorporated by reference
into the present application.
BACKGROUND ART
[0003] A radio communication system in which an antenna unit
(remote radio head: RRH) and a signal-processing unit (baseband
unit: BBU) of a radio base station are separate is known. In this
radio communication system, an RRH and a BBU are connected by an
optical device and an optical fiber and this optical segment is
called a mobile front haul (MFH). FIG. 11 is a diagram illustrating
a configuration example of an MFH.
[0004] In recent years, in order to reduce the cost of an MFH,
research on accommodating RRHs using a time-division
multiplexing-passive optical network (TDM-PON) system (for example,
see Non-Patent Document 1) has been conducted (for example, see
Non-Patent Document 2). In a TDM-PON system, a time-division
multiple-access (TDMA) scheme is used for transmitting signals from
an optical terminating apparatus (ONU: optical network unit) to an
optical terminal station apparatus (OLT: optical line terminal).
There is a proposed method of estimating the amount of traffic
transmitted to MFHs on the basis of traffic information between
RRHs and radio terminals and dynamically changing a bandwidth
allocated from an optical terminal station apparatus to an optical
terminating apparatus when RRHs are accommodated using TDM-PON (for
example, see Non-Patent Document 2).
[0005] FIG. 12 is a block diagram illustrating a configuration of a
conventional terminal station apparatus.
[0006] A traffic information acquisition unit acquires uplink
signals or downlink signals in respective bandwidth allocation
periods. Here, a bandwidth allocation period is a period in which a
terminal station apparatus (for example, an OLT) transmits a signal
containing information to provide uplink transmission permission to
a terminating apparatus (for example, ONU). A traffic information
extraction unit separates and extracts the amount of traffic
acquired by the traffic information acquisition unit in respective
arbitrary periods. Separate periods are defined as traffic periods.
A traffic amount estimation unit calculates, in each traffic
period, an average value .mu. and a standard deviation .sigma. of
the amounts of traffic in a plurality of bandwidth allocation
periods included in the traffic period.
[0007] As illustrated in FIG. 13, an RRH connected to a terminating
apparatus buffers radio signals transmitted from radio terminals
for a predetermined period only and performs a demodulation and
decoding operation at once. In this way, signals arriving at the
terminating apparatus (ONU) from the RRH are burst traffic. As
illustrated in FIG. 14, this burst traffic arrives at the
terminating apparatus (ONU) while maintaining a constant time
interval called as a transmission time interval (TTI). A TTI
indicates the smallest unit of radio scheduling. The time length of
a TTI is equal to the length of one sub-frame. In the case of LTE,
since the radio scheduling period is 1 ms, the time length of one
TTI is 1 ms. Shortening of the TTI has been considered in the fifth
generation mobile communication system (5G), which is a future
mobile access scheme.
[0008] A traffic starting position detection unit detects a
starting position of each item of burst traffic by referring to the
traffic information transmitted from the traffic information
acquisition unit. The traffic starting position detection unit
transmits information on the detected starting position to a
bandwidth allocation amount calculation unit. The bandwidth
allocation amount calculation unit calculates a bandwidth
allocation amount and an allocation timing on the basis of the
information transmitted from the traffic amount estimation unit and
the traffic starting position detection unit. HG 15 illustrates a
conventional allocation scheme in the bandwidth allocation amount
calculation unit. As illustrated in Equation (1), the bandwidth
allocation amount calculation unit starts bandwidth allocation from
the starting position of a TTI and determines a bandwidth
allocation amount B of each terminating apparatus on the basis of
an average value .mu. and a standard deviation .sigma..
[Math. 1]
B=.mu.+n.sigma. (1)
[0009] Here, n is a constant calculated from a hazard rate.
Moreover, when a terminating apparatus having obtained transmission
permission in an i.sup.th order is ONU #i, a bandwidth allocation
amount B, an average value .mu., and a standard deviation .sigma.
of the ONU #i will be denoted by a bandwidth allocation amount
B.sup.(i), an average value .mu..sup.(i), and a standard deviation
.sigma..sup.(i), respectively. Moreover, FIG. 16 is a flowchart
illustrating a bandwidth allocation process of a conventional
bandwidth allocation amount calculation unit.
CITATION LIST
Patent Literature
[0010] Non-Patent Document 1: "NTT Technical Journal, Basic
Technology Course [GE-PON Technology], Part 1: PON", [online],
2005, Nippon Telegraph and Telephone Corporation, [Retrieved on May
21, 2015], Internet <URL
http://www.ntt.co.jp/journal/0508/files/jn200508071.pdf> [0011]
Non-Patent Document 2: T. Kobayashi, H. Ou, D. Hisano, T. Shimada,
J. Terada, and A. Otaka, "Bandwidth Allocation scheme based on
Simple Statistical Traffic Analysis for a TDM-PON based Mobile
Fronthaul," in Proc. of OFC 2016, paper W3C. 7, 2016
SUMMARY OF INVENTION
Technical Problem
[0012] In a TDM-PON, when a plurality of ONUs are connected, an OLT
gives transmission permission sequentially to respective ONUs
within a bandwidth allocation period. Due to this, an ONU #N having
obtained transmission permission in an N.sup.th order or later
remains in a waiting state until ONU #1 to ONU #(N-1) having
obtained transmission permission in first to (N-1).sup.th orders
finish transmission of signals. The longer waiting period, the more
likely it is to cause a delay.
[0013] When conventional bandwidth allocation is used, a long
transmission permission period is applied to traffic generated. For
example, when an average throughput .mu. of uplink signals is 100
Mbps (megabits per second), a standard deviation .sigma. is 20
Mbps, and the constant n is 6, an allocation bandwidth is
calculated as B=100+6.times.20=220 Mbps by Equation (1). However,
when concentration of a traffic occurrence distribution near an
average throughput is taken into consideration, 120 Mbps is
allocated in order to cope with abruptly increasing traffic. An ONU
having obtained the next transmission opportunity remains in a
transmission waiting state until a bandwidth allocation of 220 Mbps
is completed.
[0014] Moreover, there is a possibility that an ONU which issues a
new connection request may be present while a bandwidth allocation
operation is being performed. In a TDM-PON, a window called an
activation window is provided in each predetermined period. In a
period in which an activation window is provided, the
newly-connected ONU can transmit an authentication request signal
to an OLT. Bandwidth allocation is stopped during the activation
window period in order to prevent interference between the signal
transmitted for the authentication and the signals transmitted by
already-connected ONUs. Due to this, an instantaneous delay
corresponding to the activation window period occurs in the
already-connected ONUs.
[0015] With the foregoing in view, an object of the present
invention is to provide a bandwidth allocation apparatus and a
bandwidth allocation method in which a bandwidth is able to be
allocated such that a delay in terminating apparatuses connected to
a terminal station apparatus according to time-division
multiple-access is prevented.
Solution to Problem
[0016] A bandwidth allocation apparatus according to a first aspect
of the present invention includes: a traffic information
acquisition unit configured to acquire traffic information
indicating the traffic of communication that each lower-level
apparatus performs via a respective terminating apparatus for each
lower-level apparatus connected to the respective terminating
apparatus; a traffic starting position detection unit configured to
detect a start timing of burst traffic on the basis of the traffic
information; a traffic information extraction unit configured to
extract information on a traffic amount of each of traffic
allocation periods from the traffic information extracted for each
lower-level apparatus; a traffic amount estimation unit configured
to calculate, for each lower-level apparatus, an average value of
the traffic amount in the traffic allocation periods on the basis
of the information on the traffic amount that the traffic
information extraction unit has extracted; and a bandwidth
allocation unit configured to allocate a first bandwidth which is
an allocation bandwidth based on the average value calculated by
the traffic amount estimation unit to each terminating apparatus
from a start of the bandwidth allocation period, the start timing
detected by the traffic starting position detection unit being used
as the start timing of the bandwidth allocation period.
[0017] According to a second aspect of the present invention, in
the bandwidth allocation apparatus according to the first aspect,
the traffic amount estimation unit is configured to calculate, for
each lower-level apparatus, a standard deviation of the traffic
amount in the traffic allocation periods on the basis of the
information on the traffic amount extracted by the traffic
information extraction unit, and the bandwidth allocation unit is
configured to allocate a second bandwidth which is an allocation
bandwidth based on the standard deviation calculated by the traffic
amount estimation unit to each terminating apparatus after the end
of allocation of the first bandwidth and allocate a surplus
bandwidth which is the first bandwidth and the second bandwidth
subtracted from an allocatable bandwidth in the bandwidth
allocation period to each terminating apparatus in a surplus
bandwidth allocation period which is a period from the end of
allocation of the second bandwidth to the end of the bandwidth
allocation period.
[0018] According to a third aspect of the present invention, in the
bandwidth allocation apparatus according to the second aspect, the
bandwidth allocation unit is configured to calculate the first
bandwidth to be allocated to each terminating apparatus according
to a ratio of the average value in a relevant terminating apparatus
to a sum of the average values in all terminating apparatuses, and
the bandwidth allocation unit is configured to calculate the second
bandwidth to be allocated to each terminating apparatus according
to a ratio of the standard deviation in a relevant terminating
apparatus to a sum of the standard deviations in all terminating
apparatuses.
[0019] According to a fourth aspect of the present invention, the
bandwidth allocation apparatus according to the second or third
aspect further includes: a newly-connected terminating apparatus
authentication unit configured to set an authentication period for
detecting a newly-connected terminating apparatus in the surplus
bandwidth allocation period, and the bandwidth allocation unit is
configured not to allocate a bandwidth to the terminating apparatus
in the authentication period notified from the newly-connected
terminating apparatus authentication unit.
[0020] According to a fifth aspect of the present invention, the
bandwidth allocation apparatus according to the second or third
aspect further includes: a traffic excess determination-processing
unit configured to instruct the bandwidth allocation unit to
perform bandwidth allocation again when a traffic amount of an
uplink signal transmitted from the terminating apparatus using the
second bandwidth exceeds a threshold.
[0021] According to a sixth aspect of the present invention, the
bandwidth allocation apparatus according to the second or third
aspect further includes: a traffic excess determination-processing
unit configured to instruct the bandwidth allocation unit to
perform bandwidth allocation again when an uplink signal which uses
the surplus bandwidth is transmitted from the terminating
apparatus.
[0022] According to a seventh aspect of the present invention, in
the bandwidth allocation apparatus according to the first aspect,
the bandwidth allocation unit is configured to calculate, for each
lower-level apparatus, a bandwidth by multiplying a bandwidth
allocatable to each lower-level apparatus by a ratio of the average
value in a relevant lower-level apparatus to a sum of the average
values calculated by the traffic amount estimation unit, and the
bandwidth allocation unit is configured to allocate a bandwidth
indicated by a first threshold to the lower-level apparatus in
which the calculated bandwidth exceeds the first threshold and
evenly distribute a non-allocated bandwidth within the allocatable
bandwidth to the lower-level apparatus in which the calculated
bandwidth is equal to or smaller than the first threshold.
[0023] According to an eighth aspect of the present invention, in
the bandwidth allocation apparatus according to the seventh aspect,
the bandwidth allocation unit is configured to allocate a bandwidth
indicated by the first threshold to the lower-level apparatus in
which the calculated bandwidth exceeds the first threshold,
allocate a bandwidth indicated by a second threshold to the
lower-level apparatus in which the calculated bandwidth is equal to
or smaller than the first threshold and is equal to or larger than
the second threshold, which is smaller than the first threshold,
and allocate a non-allocated bandwidth within the allocatable
bandwidth to the lower-level apparatus in which the calculated
bandwidth is equal to or smaller than the second threshold.
[0024] According to a ninth aspect of the present invention, a
bandwidth allocation method performed by a bandwidth allocation
apparatus includes: a traffic information acquisition step of
acquiring traffic information indicating the traffic of
communication that each lower-level apparatus performs via a
respective terminating apparatus for each lower-level apparatus
connected to the respective terminating apparatus; a traffic
starting position detection step of detecting a start timing of
burst traffic on the basis of the traffic information; a traffic
information extraction step of extracting information on a traffic
amount of each of traffic allocation periods from the traffic
information extracted for each lower-level apparatus; a traffic
amount estimation step of calculating, for each lower-level
apparatus, an average value of the traffic amount in the traffic
allocation periods on the basis of the information on the traffic
amount extracted; and a bandwidth allocation step of allocating a
first bandwidth which is an allocation bandwidth based on the
calculated average value to each terminating apparatus from a start
of the bandwidth allocation period, the detected start timing of
the burst traffic being used as the start timing of the bandwidth
allocation period.
Advantageous Effects of Invention
[0025] According to the present invention, it is possible to
allocate a bandwidth so as to reduce a delay in terminating
apparatuses connected to a terminal station apparatus according to
time-division multiple-access.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a diagram illustrating a configuration of an
access network system according to a first embodiment of the
present invention.
[0027] FIG. 2 is a functional block diagram illustrating a
configuration of a terminal station apparatus according to the
first embodiment.
[0028] FIG. 3 is a flowchart illustrating a bandwidth allocation
process of the terminal station apparatus according to the first
embodiment.
[0029] FIG. 4 is a diagram illustrating bandwidth allocation to a
terminating apparatus according to the first embodiment.
[0030] FIG. 5 is a functional block diagram illustrating a
configuration of a terminal station apparatus according to a second
embodiment.
[0031] FIG. 6 is a functional block diagram illustrating a
configuration of a terminal station apparatus according to a third
embodiment.
[0032] FIG. 7 is a functional block diagram illustrating a
configuration of a terminal station apparatus according to a
seventh embodiment.
[0033] FIG. 8 is a flowchart illustrating a bandwidth allocation
process of the terminal station apparatus according to the seventh
embodiment.
[0034] FIG. 9 is a functional block diagram illustrating a
configuration of a terminal station apparatus according to an
eighth embodiment.
[0035] FIG. 10 is a flowchart illustrating a bandwidth allocation
process of the terminal station apparatus according to the eighth
embodiment.
[0036] FIG. 11 is a diagram illustrating a configuration example of
an MFH according to a conventional technology.
[0037] FIG. 12 is a diagram illustrating a configuration of a
terminal station apparatus according to a conventional
technology.
[0038] FIG. 13 is a diagram illustrating an example of a traffic
model in which a burst signal occurs.
[0039] FIG. 14 is a diagram illustrating an example of traffic
flowing through an MFH.
[0040] FIG. 15 is a diagram illustrating bandwidth allocation to a
terminating apparatus according to a conventional technology.
[0041] FIG. 16 is a flowchart illustrating a bandwidth allocation
process of a terminal station apparatus according to a conventional
technology.
DESCRIPTION OF EMBODIMENTS
[0042] Hereinafter, embodiments of the present invention will be
described with reference to the drawings.
First Embodiment
[0043] FIG. 1 is a diagram illustrating a configuration of an
access network system 8 according to a first embodiment. The access
network system 8 has a configuration in which a relay transmission
system having a terminal station apparatus 1, a terminating
apparatus 2, and an optical splitter 3 accommodates a communication
system having an upper-level apparatus 5 and a lower-level
apparatus 6. A system accommodating a communication system means
that the system relays the communications in the communication
system.
[0044] A relay transmission system is an optical relay transmission
system such as a passive optical network (PON) system, for example.
When the relay transmission system is a PON system, the terminal
station apparatus 1 is an optical terminal station apparatus (OLT)
and the terminating apparatus 2 is an optical terminating apparatus
(ONU). The direction from the terminal station apparatus 1 to the
terminating apparatus 2 is downlink and the direction from the
terminating apparatus 2 to the terminal station apparatus 1 is
uplink. The optical splitter 3 distributes
time-division-multiplexed (TDM) optical signals transmitted by one
optical fiber 41 from the terminal station apparatus 1 to optical
fibers 42 connected to a plurality of terminating apparatuses 2.
Moreover, the optical splitter 3 combines time-division
multiple-access (TDMA) optical signals transmitted from the optical
fibers 42 connected to the plurality of terminating apparatuses 2
and outputs a combined optical signal to the optical fiber 41. The
terminal station apparatus 1 has the function of a bandwidth
allocation apparatus that allocates bandwidth to the respective
terminating apparatuses 2 and executes a bandwidth allocation
method.
[0045] The communication system is a mobile network, for example.
When the communication system is a mobile network, the upper-level
apparatus 5 is a signal-processing unit (BBU) of a radio base
station and the lower-level apparatus 6 is an antenna unit (RRH) of
a radio base station. An RRH performs radio communication with a
mobile radio terminal according to a TDD scheme. The relay
transmission system can accommodate a plurality of communication
systems.
[0046] FIG. 2 is a functional block diagram illustrating a
configuration of the terminal station apparatus 1 and extracts and
illustrates functional blocks related to the first embodiment. The
terminal station apparatus 1 includes an upper-level transceiving
functional unit 11, a lower-level transceiving functional unit 12,
a traffic information acquisition unit 13, a traffic information
extraction unit 14, a traffic amount estimation unit 15, a traffic
starting position detection unit 16, and a bandwidth allocation
amount calculation unit 17. The functions of the upper-level
transceiving functional unit 11, the lower-level transceiving
functional unit 12, the traffic information acquisition unit 13,
the traffic information extraction unit 14, the traffic amount
estimation unit 15, and the traffic starting position detection
unit 16 are similar to those of the conventional terminal station
apparatus illustrated in FIG. 12.
[0047] The upper-level transceiving functional unit 11 is an
interface that performs transmission/reception of data to and from
the upper-level apparatus 5. The upper-level transceiving
functional unit 11 outputs a downlink signal addressed to the
lower-level apparatus 6 received from the upper-level apparatus 5
to the lower-level transceiving functional unit 12. Moreover, the
upper-level transceiving functional unit 11 transmits an uplink
signal addressed to the upper-level apparatus 5 from the
lower-level apparatus 6, received from the lower-level transceiving
functional unit 12, to the upper-level apparatus 5.
[0048] The lower-level transceiving functional unit 12 is an
interface that performs transmission/reception of data to and from
the terminating apparatus 2. The lower-level transceiving
functional unit 12 converts the downlink signal output from the
upper-level transceiving functional unit 11 and a control signal
output from the bandwidth allocation amount calculation unit 17
from an electrical signal into an optical signal and outputs the
optical signal to the terminating apparatus 2. Moreover, the
lower-level transceiving functional unit 12 converts the uplink
signal received from the terminating apparatus 2 from an optical
signal into an electrical signal and outputs the electrical signal
to the upper-level transceiving functional unit 11. The electrical
signal that the lower-level transceiving functional unit 12 outputs
to the upper-level transceiving functional unit 11 includes the
uplink signal addressed to the upper-level apparatus 5 from the
lower-level apparatus 6. Furthermore, the lower-level transceiving
functional unit 12 transmits the uplink signal converted into the
electrical signal to the traffic information acquisition unit 13.
The lower-level transceiving functional unit 12 may output only a
main signal of the uplink signal to the traffic information
acquisition unit 13.
[0049] The traffic information acquisition unit 13 acquires the
uplink signals from each terminating apparatus 2 in each bandwidth
allocation period and stores traffic information indicating a
traffic amount of the uplink signals in each bandwidth allocation
period. The bandwidth allocation period is a period in which the
terminal station apparatus 1 transmits a signal containing
information to give uplink transmission permission to the
terminating apparatus 2.
[0050] The traffic information extraction unit 14 separates and
extracts the traffic information acquired by the traffic
information acquisition unit 13 in each arbitrary period. The
arbitrary period may be defined such that N seconds of traffic is
evenly divided by M and N/M is one period, or alternatively, N
seconds of traffic is separated into different time lengths such as
M.sub.1, M.sub.2, . . . , M.sub.i rather than dividing evenly and
each separate period is one period. The separate periods are
traffic periods. One traffic period includes a plurality of
bandwidth allocation periods. The traffic information extraction
unit 14 transmits the extracted traffic information in each traffic
period to the traffic amount estimation unit 15.
[0051] The traffic amount estimation unit 15 acquires, in each
traffic period, the traffic amount in each of a plurality of
bandwidth allocation periods included in the traffic period from
the traffic information with respect to each terminating apparatus
2 and calculates an average value .mu. and a standard deviation
.sigma. of the traffic amount. The traffic amount estimation unit
15 transmits the calculation result of the average value .mu. and
the standard deviation .sigma. of the traffic amount in each
traffic period of each terminating apparatus 2 to the bandwidth
allocation amount calculation unit 17.
[0052] The traffic starting position detection unit 16 detects the
starting position of each item of burst traffic and outputs
information indicating the detected starting position to the
bandwidth allocation amount calculation unit 17. The starting
position of the burst traffic corresponds to the start of TTI, for
example. The bandwidth allocation amount calculation unit 17
calculates a bandwidth allocation amount and an allocation timing
of each terminating apparatus 2 in the bandwidth allocation period
on the basis of the information transmitted from the traffic amount
estimation unit 15 and the traffic starting position detection unit
16.
[0053] FIG. 3 is a flowchart illustrating the operation of the
terminal station apparatus 1.
[0054] First, the bandwidth allocation amount calculation unit 17
of the terminal station apparatus 1 allocates a fixed bandwidth to
each terminating apparatus 2 in each dynamic bandwidth allocation
(DBA) period in order to collect traffic. The DBA period is a
period in which bandwidth is allocated to the terminating apparatus
2. The lower-level transceiving functional unit 12 notifies each
terminating apparatus 2 of the fixed bandwidth allocated by the
bandwidth allocation amount calculation unit 17 as the allocation
bandwidth of each DBA period. Each terminating apparatus 2
transmits uplink data received from the lower-level apparatus 6 to
the terminal station apparatus 1 according to the allocated fixed
bandwidth (step S105). The traffic information acquisition unit 13
of the terminal station apparatus 1 acquires the uplink signal
received by the lower-level transceiving functional unit 12 over a
plurality of periods in each bandwidth allocation period and stores
the traffic amount of the uplink signals acquired by the respective
terminating apparatuses 2 as traffic information (step S110).
[0055] After a traffic monitor period ends, the traffic starting
position detection unit 16 detects the starting position of each
item of burst traffic by referring to the traffic information and
outputs information indicating the detected starting position to
the bandwidth allocation amount calculation unit 17 (step S115).
The traffic information extraction unit 14 extracts the traffic
information acquired by the traffic information acquisition unit 13
in each traffic period and transmits the extracted traffic
information to the traffic amount estimation unit 15. The traffic
amount estimation unit 15 calculates an average value .mu. and a
standard deviation .alpha. of the traffic amount in the DBA period
of each terminating apparatus 2 in each traffic period on the basis
of the traffic information transmitted from the traffic information
extraction unit 14 and transmits the calculation result to the
bandwidth allocation amount calculation unit 17 (step S120).
[0056] The bandwidth allocation amount calculation unit 17 performs
the following processes of steps S125 to S150 in each bandwidth
allocation period.
[0057] The bandwidth allocation amount calculation unit 17 reads
the average value .mu. and the standard deviation .sigma. of the
traffic amount of each terminating apparatus 2 in a traffic period
corresponding to a target bandwidth allocation period in which
bandwidth allocation is performed from the traffic amount
estimation unit 15 (step S125). The bandwidth allocation amount
calculation unit 17 allocates a bandwidth B.sub.avg based on the
average value .mu. of a previous traffic amount to each terminating
apparatus 2 as illustrated in Equation (2) (step S130). The
superscript (i) indicates an i.sup.th terminating apparatus 2 among
the plurality of terminating apparatuses 2 connected to the
terminal station apparatus 1. The traffic period used in step S125
is a predetermined number of traffic periods immediately before a
target bandwidth allocation period, for example.
[Math. 2]
B.sub.avg.sup.(i)=.mu..sup.(i) (2)
[0058] FIG. 4 is a diagram illustrating allocation of bandwidth to
each terminating apparatus 2. As illustrated in FIG. 4, when a
bandwidth allocation target-terminating apparatus 2 is three ONUs
of ONU #1 to ONU #3, the bandwidth allocation amount calculation
unit 17 allocates bandwidths B.sub.avg(1) to B.sub.avg(3) to ONU #1
to ONU #3, respectively, sequentially from the start of the DBA
period.
[0059] When allocation of the average-base bandwidth B.sub.avg
based on Equation (2) to all terminating apparatuses 2 is completed
(step S135), as illustrated in Equation (3), the bandwidth
allocation amount calculation unit 17 allocates a variance-base
bandwidth B.sub.var which uses the standard deviation .sigma. of
traffic amount sequentially to the respective terminating
apparatuses 2 (step S140). Here, n is a constant calculated from a
hazard rate, and the lower the hazard rate, the larger becomes the
value n.
[Math. 3]
B.sub.var.sup.(i)=n.sup.(i).sigma..sup.(i) (3
[0060] In the bandwidth allocation illustrated in FIG. 4, after
bandwidths B.sub.avg(1) to B.sub.avg(3) are allocated to the three
ONUs of ONU #1 to ONU #3, respectively, variance-base bandwidths
B.sub.var(1) to B.sub.var(3) are allocated. The bandwidth
allocation based on these equations (2) and (3) may be subdivided
further.
[0061] After allocation of the bandwidth B.sub.var based on
Equation (2) to all terminating apparatuses 2 is completed (step
S145), the bandwidth allocation amount calculation unit 17
allocates a surplus bandwidth B.sub.surplus in the DBA period to
the terminating apparatus 2. The traffic amount estimation unit 15
calculates the surplus bandwidth B.sub.surplus according to
Equation (4).
[Math. 4]
B.sub.surplus=B.sub.all-.SIGMA..sub.iB.sub.avg.sup.(i)-.SIGMA..sub.iB.su-
b.var.sup.(i) (4)
[0062] Here, B.sub.all indicates all bandwidth usable in the DBA
period of TDM-PON. For example, in the case of 10G-PON, B.sub.ail
is 10 gigabits per second (Gbps) when an overhead is not taken into
consideration.
[0063] The bandwidth allocation amount calculation unit 17
allocates bandwidth to each terminating apparatus 2 using the
surplus bandwidth B.sub.surplus calculated by the traffic amount
estimation unit 15 (step S150). In allocation of the surplus
bandwidth B.sub.surplus, a fixed bandwidth may be allocated equally
to each terminating apparatus 2, or a bandwidth allocation amount
may be changed for respective terminating apparatuses 2 depending
on a type such as priority. The surplus bandwidth B.sub.surplus may
be used as a bandwidth for accommodating other services in addition
to being allocated to each terminating apparatus 2. In the surplus
bandwidth B.sub.surplus period, the terminal station apparatus 1
and each terminating apparatus 2 may perform a sleep operation. In
the bandwidth allocation illustrated in FIG. 4, in a period from
the end of bandwidth allocation of the variance-base bandwidth
B.sub.var to the end of the DBA period, bandwidths b(1) to b(3)
obtained by dividing the surplus bandwidth B.sub.surplus are
allocated to ONU #1 to ONU #3, respectively.
[0064] Here, the order of performing bandwidth allocation to the
terminating apparatuses 2 according to Equations (2) to (4) may not
be the same. The bandwidth allocation amount calculation unit 17
performs bandwidth allocation based on the average value .mu. of
the traffic amount calculated for each terminating apparatus 2 and
performs bandwidth allocation based on the standard deviation
.sigma. of the traffic amount calculated for each terminating
apparatus 2. The terminal station apparatus 1 performs these
allocation operations sequentially whereby a waiting period
(communication delay) until each terminating apparatus 2 obtains a
communication chance can be reduced.
Second Embodiment
[0065] In the first embodiment, a surplus bandwidth which is not
allocated to any terminating apparatus after the terminal station
apparatus 1 allocates the average-base bandwidth and the
variance-base bandwidth is distributed to respective terminating
apparatuses. In the second embodiment, a surplus bandwidth or a
variance-base allocation bandwidth and a surplus bandwidth is used
in an activation window in which a signal for allowing a
newly-connected terminating apparatus to send an authentication
request to a terminal station apparatus is transmitted. In this
manner, a terminal station apparatus of the second embodiment
provides an activation window in only a period in which bandwidth
is allocated according to Equation (3) or (4) described in the
first embodiment whereby the influence of delay on
already-connected terminating apparatuses can be suppressed.
[0066] The terminal station apparatus of the second embodiment
calculates an average value and a standard deviation of the traffic
amount on the basis of uplink traffic information and estimates a
bandwidth allocation amount of each terminating apparatus using the
average value and the standard deviation. Therefore, a bandwidth
allocated on the basis of the surplus bandwidth B.sub.surplus
calculated by Equation (4) is a bandwidth which is not used
basically. Due to this, even if an activation window is provided in
this period, there is no influence of delay on a mobile system.
[0067] FIG. 5 is a block diagram illustrating a configuration of a
terminal station apparatus 1a according to the second embodiment.
In FIG. 5, the same portions as those of the terminal station
apparatus 1 according to the first embodiment illustrated in FIG. 2
will be denoted by the same reference numerals and the description
thereof will be omitted. A difference between the terminal station
apparatus 1 illustrated in FIG. 5 and the terminal station
apparatus 1 of the first embodiment is that the terminal station
apparatus 1 illustrated in FIG. 5 further includes a
newly-connected terminating apparatus authentication unit 18. The
newly-connected terminating apparatus authentication unit 18
acquires a period in which bandwidth allocation using Equation (4)
described in the first embodiment is performed from the traffic
amount estimation unit 15 or the bandwidth allocation amount
calculation unit 17. The newly-connected terminating apparatus
authentication unit 18 notifies the bandwidth allocation amount
calculation unit 17 that an activation window is provided in this
period only. The bandwidth allocation amount calculation unit 17
provides an activation window such that bandwidth is not allocated
to the terminating apparatus 2 in the period notified from the
newly-connected terminating apparatus authentication unit 18 within
the period in which the bandwidth allocation of Equation (4)
described in the first embodiment is performed.
[0068] The newly-connected terminating apparatus authentication
unit 18 may further acquire a period in which bandwidth allocation
using Equation (3) is performed and notify the bandwidth allocation
amount calculation unit 17 that an activation window is provided in
this period. The bandwidth allocation amount calculation unit 17
provides an activation window in the period such that bandwidth is
not allocated to the terminating apparatus 2 in the period notified
from the newly-connected terminating apparatus authentication unit
18 within the period in which bandwidth allocation of Equation (3)
described in the first embodiment is performed.
[0069] The terminal station apparatus 1a provides an activation
window in a period in which the possibility that each terminating
apparatus 2 transmits an uplink signal is low. By providing an
activation window in this manner, the possibility that a signal
related to authentication of a newly-connected terminating
apparatus interferes with an uplink signal of each terminating
apparatus 2 can be suppressed and delay of transmission of an
uplink signal can be suppressed.
Third Embodiment
[0070] In a third embodiment, a terminal station apparatus corrects
a bandwidth allocation amount when traffic which significantly
exceeds an estimation result occurs from a terminating
apparatus.
[0071] FIG. 6 is a block diagram illustrating a configuration of a
terminal station apparatus 1b according to a third embodiment. In
FIG. 6, the same portions as those of the terminal station
apparatus 1 according to the first embodiment illustrated in FIG. 2
will be denoted by the same reference numerals and the description
thereof will be omitted. A difference between the terminal station
apparatus 1b illustrated in FIG. 6 and the terminal station
apparatus 1 of the first embodiment is that the terminal station
apparatus 1b further includes a traffic determination time
threshold-processing unit 19.
[0072] An arbitrary time threshold t.sub.th is set in the traffic
determination time threshold-processing unit 19. When the terminal
station apparatus 1 receives an uplink signal transmitted by the
bandwidth allocation performed on the basis of Equation (3), the
traffic information acquisition unit 13 notifies the traffic
determination time threshold-processing unit 19 of a data amount of
the uplink signal. The traffic determination time
threshold-processing unit 19 compares the data amount of the uplink
signal with the time threshold t.sub.th and instructs the bandwidth
allocation amount calculation unit 17 to reset to fixed bandwidth
allocation when it is determined that the data amount of the uplink
signal exceeds the time threshold t.sub.th. For example, when the
traffic information acquisition unit 13 monitors traffic at a
predetermined monitor period, the traffic determination time
threshold-processing unit 19 can compare the time threshold with
the data amount of the uplink signal expressed by the number of
monitor periods. Alternatively, the traffic determination time
threshold-processing unit 19 may convert the data amount of the
uplink signal notified from the traffic information acquisition
unit 13 to a reception time of the uplink signal and compare the
reception time with the time threshold t.sub.th. Alternatively, the
traffic determination time threshold-processing unit 19 may convert
the time threshold t.sub.th to a data amount receivable in the same
period as the time threshold t.sub.th and compare the receivable
data amount with the data amount of the uplink signal notified from
the traffic information acquisition unit 13.
[0073] Upon receiving this instruction from the traffic
determination time threshold-processing unit 19, the bandwidth
allocation amount calculation unit 17 performs fixed bandwidth
allocation to each terminating apparatus 2. In this way, the
processes starting from step S105 in FIG. 3 are performed, and
bandwidth allocation to each terminating apparatus 2 is performed
again. By performing bandwidth allocation, the terminal station
apparatus 1b can perform bandwidth allocation according to a change
in the traffic amount of the uplink signal of each terminating
apparatus 2 and suppress delay of transmission of the uplink
signal.
Fourth Embodiment
[0074] In a fourth embodiment, unlike the second embodiment, a
terminal station apparatus receives an uplink signal transmitted
according to bandwidth allocation performed on the basis of
Equation (4). The terminal station apparatus of the first
embodiment calculates an average value and a standard deviation of
the traffic amount on the basis of the uplink traffic information
and estimates a bandwidth allocation amount on the basis of the
average value and the standard deviation. Therefore, a bandwidth
allocated on the basis of Equation (4) is a bandwidth which is not
used basically. Due to this, the fact that an uplink signal is
transmitted using the bandwidth allocation based on Equation (4)
corresponds to a case in which traffic which significantly exceeds
an estimation result occurs. The terminal station apparatus of the
fourth embodiment starts the processes starting from step S105 in
FIG. 3 and resets to the fixed bandwidth allocation and performs
re-estimation when an uplink signal transmitted from a terminating
apparatus is received in the bandwidth allocation performed on the
basis of
[0075] Equation (4).
[0076] The terminal station apparatus of the fourth embodiment can
perform bandwidth allocation according to a change in the traffic
amount of the uplink signal of each terminating apparatus 2 and
suppress delay of transmission of the uplink signal similarly to
the terminal station apparatus 1b of the third embodiment.
Fifth Embodiment
[0077] In the first to fourth embodiments, the terminal station
apparatus acquires traffic of an uplink signal to estimate traffic
information and performs bandwidth allocation on the basis of the
traffic information. A terminal station apparatus of a fifth
embodiment may acquire downlink traffic only or both uplink traffic
and downlink traffic instead of uplink traffic and perform
processes similar to those of the first to fourth embodiments using
the acquired traffic information. When the traffic amount of an
uplink signal and the traffic amount of a downlink signal are
proportional to each other, the terminal station apparatus of the
fifth embodiment can perform bandwidth allocation that suppresses
delay similarly to the terminal station apparatuses of the first to
fourth embodiments.
Sixth Embodiment
[0078] When a relay transmission system accommodates a plurality of
RRHs, a terminal station apparatus can enhance a bandwidth-reducing
effect by estimating a traffic amount of each terminating apparatus
connected to RRHs and performing the processes of the first to
fifth embodiments. Moreover, since the start of TTI is different
depending on RRH, this can be coped with by extracting information
individually. A terminal station apparatus can reduce delay from
RRH (lower-level apparatus) to BBU (upper-level apparatus) by
performing bandwidth allocation in synchronization with a TTI
period of each RRH.
Seventh Embodiment
[0079] A seventh embodiment is different from the first embodiment
in terms of a method of calculating an average-base bandwidth
allocation amount and a variance-base bandwidth allocation
amount.
[0080] FIG. 7 is a block diagram illustrating a configuration of a
terminal station apparatus 1c of the seventh embodiment. In FIG. 7,
the same portions as those of the terminal station apparatus 1 of
the first embodiment illustrated in FIG. 2 will be denoted by the
same reference numerals and the description thereof will be
omitted. The terminal station apparatus 1c illustrated in FIG. 7 is
different from the terminal station apparatus 1 of the first
embodiment in that the terminal station apparatus 1c includes a
bandwidth allocation amount calculation unit 17c instead of the
bandwidth allocation amount calculation unit 17. The operation of
the bandwidth allocation amount calculation unit 17c will be
described with reference to the flowchart illustrated in FIG.
8.
[0081] FIG. 8 is a flowchart illustrating the operation of the
terminal station apparatus 1c. In FIG. 8, the same processes as
those of the processes performed by the terminal station apparatus
1 of the first embodiment illustrated in FIG. 3 will be denoted by
the same reference numerals and the detailed description thereof
will be omitted. The terminal station apparatus 1c performs the
processes of steps S105 to S120 similarly to the terminal station
apparatus 1 of the first embodiment.
[0082] The bandwidth allocation amount calculation unit 17c
performs the following processes of steps S125 to S150 in each
bandwidth allocation period.
[0083] In a bandwidth allocation period, the bandwidth allocation
amount calculation unit 17c reads an average value .mu. and a
standard deviation .sigma. of the traffic amount of each
terminating apparatus 2 in a traffic period corresponding to a
target bandwidth allocation period in which bandwidth allocation is
performed from the traffic amount estimation unit 15 (step S125).
The bandwidth allocation amount calculation unit 17c allocates a
bandwidth B.sub.avg(i) precedently to each terminating apparatus 2
as illustrated in Equation (5) (step S130c).
[ Math . .times. 5 ] B avg ( i ) = .mu. ( i ) k .times. .mu. ( k )
.times. B avg ' .function. ( i ) ( 5 ) ##EQU00001##
[0084] Unlike the first embodiment, the bandwidth allocation amount
calculation unit 17c performs bandwidth allocation on the basis of
the ratio obtained by dividing the average value .mu. of the
traffic amount of a bandwidth allocation target-terminating
apparatus 2 by the sum of all average values of the traffic amount
calculated for the respective terminating apparatuses 2. Here,
B'.sub.avg.sup.(i) is an arbitrary bandwidth allocation amount for
an i.sup.th terminating apparatus 2 and may be the same for all
terminating apparatuses 2 and may be different for some or all
terminating apparatuses 2.
[0085] When allocation of the average-base bandwidth B.sub.avg
based on Equation (5) to all terminating apparatuses 2 is completed
(step S135), the bandwidth allocation amount calculation unit 17c
allocates the variance-base bandwidth B.sub.var which uses the
standard deviation .sigma. of the traffic amount as illustrated in
Equation (6) sequentially to the respective terminating apparatuses
2 (step S140c).
[ Math . .times. 6 ] B v .times. a .times. r ( i ) = n ( i )
.times. .sigma. ( i ) k .times. n ( k ) .times. .sigma. ( k )
.times. B va .times. r ' .function. ( i ) ( 6 ) ##EQU00002##
[0086] In the variance-base bandwidth B.sub.var, the bandwidth
allocation amount calculation unit 17c performs bandwidth
allocation on the basis of the ratio obtained by dividing the
standard deviation .sigma. of the traffic amount of a bandwidth
allocation target-terminating apparatus 2 by the sum of all
standard deviations of the traffic amount calculated for the
respective terminating apparatuses 2 similarly to the bandwidth
allocation based on Equation (5). Here, B'.sub.var.sup.(i) is an
arbitrary bandwidth allocation amount for an i.sup.th terminating
apparatus 2 and may be the same for all terminating apparatuses 2
and may be different for some or all terminating apparatuses 2.
[0087] After allocation of the B.sub.var based on Equation (6) to
all terminating apparatuses 2 is completed (step S145), the
bandwidth allocation amount calculation unit 17c distributes and
allocates the surplus bandwidth B.sub.surplus calculated on the
basis of Equation (4) to the respective terminating apparatuses 2
similarly to the first embodiment (step S150). In allocation of the
surplus bandwidth B.sub.surplus, a fixed bandwidth may be allocated
equally to each terminating apparatus 2, and a bandwidth allocation
amount may be changed for respective terminating apparatuses 2
depending on a type such as priority. The surplus bandwidth
B.sub.surplus may be used as a bandwidth for accommodating other
services in addition to being allocated to each terminating
apparatus 2. In the surplus bandwidth B.sub.surplus period, the
terminal station apparatus 1c and each terminating apparatus 2 may
perform a sleep operation. Here, the order of performing bandwidth
allocation to the terminating apparatuses 2 according to Equations
(4) to (6) may not be the same.
[0088] The seventh embodiment may be used together with the first
embodiment. That is, bandwidth allocation based on an average value
may follow the allocation according to the first embodiment, and
the bandwidth allocation based on a standard deviation may follow
the allocation according to the seventh embodiment.
[0089] Alternatively, or conversely, the bandwidth allocation based
on an average value may follow the allocation according to the
seventh embodiment, and the bandwidth allocation based on a
standard deviation may follow the allocation according to the first
embodiment. A terminal station apparatus may perform bandwidth
allocation according to this combination. The terminal station
apparatus 1c sequentially performs two allocation operations of the
bandwidth allocation based on the average value .mu. of the traffic
amount calculated for each terminating apparatus 2 and the
bandwidth allocation based on the standard deviation .sigma. of the
traffic amount calculated for each terminating apparatus 2. With
this allocation, similarly to the first embodiment, a waiting
period (communication delay) until each terminating apparatus 2
obtains a communication chance can be reduced.
Eighth Embodiment
[0090] An eighth embodiment is different from the first to seventh
embodiments in terms of a bandwidth allocation amount calculation
method. FIG. 9 is a functional block diagram illustrating a
configuration of a terminal station apparatus 1d according to the
eighth embodiment. In FIG. 9, the same portions as those of the
terminal station apparatus 1 according to the first embodiment
illustrated in FIG. 2 will be denoted by the same reference
numerals and the description thereof will be omitted. A difference
between the terminal station apparatus 1d illustrated in FIG. 9 and
the terminal station apparatus 1 of the first embodiment is that
the terminal station apparatus 1d includes a bandwidth allocation
amount calculation unit 17d instead of the bandwidth allocation
amount calculation unit 17. The operation of the bandwidth
allocation amount calculation unit 17d will be described with
reference to the flowchart illustrated in FIG. 10.
[0091] FIG. 10 is a flowchart illustrating the operation of the
terminal station apparatus 1d. In FIG. 10, the same processes as
the processes performed by the terminal station apparatus 1 of the
first embodiment illustrated in FIG. 3 will be denoted by the same
reference numerals, and the detailed description thereof will be
omitted. The terminal station apparatus 1d performs the processes
of steps S105 to S115 similarly to the terminal station apparatus
1.
[0092] The traffic amount estimation unit 15 calculates the average
value .mu. of the traffic amount on the basis of the traffic
information extracted by the traffic information extraction unit 14
for each terminating apparatus 2 (step S220). The traffic amount
estimation unit 15 may calculate the average value .mu. using the
traffic amount in a predetermined number of previous traffic
periods for each terminating apparatus 2.
[0093] The bandwidth allocation amount calculation unit 17d
performs the following processes of steps S225 to S260 in each
bandwidth allocation period.
[0094] The bandwidth allocation amount calculation unit 17d reads
an average value of the traffic amount of each terminating
apparatus 2 from the traffic amount estimation unit 15 (step S225).
The bandwidth allocation amount calculation unit 17d calculates a
bandwidth B.sub.i based on the ratio of the average value
.mu..sub.i of each terminating apparatus 2 to the sum of the
average values .mu..sub.i of the terminating apparatuses 2 as
illustrated in Equation (7) as a bandwidth allocation amount to
each terminating apparatus 2 (step S230). As illustrated in
Equation (7), the bandwidth allocation amount calculation unit 17d
calculates a bandwidth B.sub.i in which all bandwidth usable in the
DBA period are allocated to the respective terminating apparatuses
2. The bandwidth B.sub.i is calculated by multiplying the bandwidth
B.sub.all by the ratio of the average value .mu..sub.i of each
terminating apparatus 2 to the sum of the average values
.mu..sub.i. When the bandwidth allocation amount is calculated in
step S230, the surplus bandwidth B.sub.surplus is initialized to
zero.
[ Math . .times. 7 ] B i = .mu. i k .times. .mu. k .times. B a
.times. l .times. l ( 7 ) ##EQU00003##
[0095] The bandwidth allocation amount calculation unit 17d
performs the processes of steps S235 to S255 for each of the
terminating apparatuses 2 connected to the terminal station
apparatus 1d.
[0096] The bandwidth allocation amount calculation unit 17d
determines whether the bandwidth B.sub.i allocated to the i.sup.th
terminating apparatus 2 among all terminating apparatuses 2 is
larger than a predetermined threshold Th.sub.upper (step S235).
When the bandwidth B.sub.i is larger than the threshold
Th.sub.upper (step S235: YES), the bandwidth allocation amount
calculation unit 17d changes the bandwidth B.sub.i allocated to the
i.sup.th terminating apparatus 2 to the threshold Th.sub.upper and
adds a difference bandwidth (B.sub.i-Th.sub.upper) to the surplus
bandwidth B.sub.surplus (step S240).
[0097] When the bandwidth B.sub.i is equal to or smaller than the
threshold Th.sub.upper (step S235: NO), the bandwidth allocation
amount calculation unit 17d determines whether the bandwidth
B.sub.i is larger than a predetermined threshold Th.sub.lower (step
S245). The threshold Th.sub.lower is smaller than the threshold
Th.sub.upper. When the bandwidth B.sub.i is larger than the
threshold Th.sub.lower (step S245: YES), the bandwidth allocation
amount calculation unit 17d changes the bandwidth B.sub.i allocated
to the i.sup.th terminating apparatus 2 to the threshold
Th.sub.lower and adds a difference bandwidth (B.sub.i-Th.sub.lower)
to the surplus bandwidth B.sub.surplus (step S250).
[0098] When the bandwidth B.sub.i is equal to or smaller than the
threshold Th.sub.lower (step S245: NO), the bandwidth allocation
amount calculation unit 17d increases N.sub.onu indicating the
number of terminating apparatuses 2 in which the bandwidth B.sub.i
is equal to or smaller than the threshold Th.sub.lower by 1 and
adds the bandwidth B.sub.i to the surplus bandwidth B.sub.surplus
(step S255).
[0099] The bandwidth allocation amount calculation unit 17d changes
the bandwidth B.sub.i allocated to each of N.sub.onu terminating
apparatuses 2 in which the bandwidth B.sub.i is equal to or smaller
than the threshold Th.sub.lower to a bandwidth
B.sub.i(=(B.sub.surplus/N.sub.onu)) obtained by evenly dividing the
surplus bandwidth B.sub.surplus (step S260). That is, the bandwidth
allocation amount calculation unit 17d evenly distributes the
surplus bandwidth B.sub.surplus which is a non-allocated bandwidth
other than the bandwidth allocated to terminating apparatuses 2 in
which the bandwidth B.sub.i exceeds the threshold Th.sub.upper or
Th.sub.lower. The bandwidth allocation amount calculation unit 17d
allocates the bandwidth B.sub.i corresponding to each of the
terminating apparatuses 2 as a bandwidth allocation amount
sequentially from the start of the bandwidth allocation period.
[0100] After temporary allocation based on the average value .mu.
of the traffic amount of each terminating apparatus 2 is performed,
the terminal station apparatus 1d adjusts the bandwidth allocated
to each terminating apparatus 2 on the basis of the two thresholds
Th.sub.upper and Th.sub.lower. By suppressing the allocation
bandwidth exceeding the threshold Th.sub.upper to the threshold
Th.sub.upper, it is possible to suppress biased allocation of
bandwidth to partial terminating apparatuses 2. Therefore, the
terminal station apparatus 1d can reduce a waiting period
(communication delay) until each terminating apparatus 2 obtains a
communication chance.
[0101] Although a case in which all usable bandwidth B.sub.all are
proportionally distributed to respective terminating apparatuses 2
on the basis of the average value .mu. in step S230 has been
described, the average value .mu..sub.i of each terminating
apparatus 2 may be used as the allocation bandwidth N. The
bandwidth allocation amount calculation unit 17d may adjust the
allocation bandwidth using one or three or more thresholds. For
example, when the bandwidth allocation is adjusted using one
threshold, the bandwidth allocation amount calculation unit 17
performs the process of step S255 when the bandwidth B.sub.i is
equal to or smaller than the threshold Th.sub.upper (step S235:
NO).
Ninth Embodiment
[0102] In the eighth embodiment, the terminal station apparatus 1d
acquires the traffic of an uplink signal to estimate traffic
information and performs bandwidth allocation on the basis of the
traffic information. A terminal station apparatus of a ninth
embodiment may acquire downlink traffic only or both uplink traffic
and downlink traffic instead of the uplink traffic and perform the
processes similar to those of the eighth embodiment using the
acquired traffic information. When the traffic amount of an uplink
signal and the traffic amount of a downlink signal are proportional
to each other, the terminal station apparatus of the ninth
embodiment can perform bandwidth allocation that suppresses delay
similarly to the terminal station apparatus of the eighth
embodiment.
Tenth Embodiment
[0103] When a relay transmission system accommodates a plurality of
RRHs, the terminal station apparatus 1d of the eighth embodiment
can enhance a bandwidth-reducing effect by estimating a traffic
amount of each terminating apparatus 2 connected to RRHs and
performing bandwidth allocation on each terminating apparatus 2.
Moreover, since the start of TTI is different depending on RRH,
this can be coped with by extracting information individually. A
terminal station apparatus can reduce delay from RRH (lower-level
apparatus) to BBU (upper-level apparatus) by performing bandwidth
allocation in synchronization with a TTI period of each RRH.
[0104] According to the above-described embodiments, a bandwidth
allocation apparatus includes a traffic information acquisition
unit, a traffic starting position detection unit, a traffic
information extraction unit, a traffic amount estimation unit, and
a bandwidth allocation unit. Although the bandwidth allocation
apparatus is a terminal station apparatus 1, 1a, 1b, or 1c, the
bandwidth allocation apparatus may be an external apparatus
connected to a terminal station apparatus, and the bandwidth
allocation apparatus may be realized by a terminal station
apparatus and an external apparatus.
[0105] The traffic information acquisition unit acquires traffic
information indicating a traffic amount of communication that each
lower-level apparatus performs via a terminating apparatus for each
lower-level apparatus connected to the terminating apparatus. The
traffic starting position detection unit detects a start timing of
burst traffic on the basis of the traffic information. The traffic
information extraction unit extracts information on a traffic
amount of each of a plurality of traffic allocation periods from
the traffic information collected for each lower-level apparatus.
The traffic amount estimation unit calculates an average value and
a standard deviation of the traffic amount in the traffic
allocation periods on the basis of the information on the traffic
amount extracted by the traffic information extraction unit for
each lower-level apparatus.
[0106] The bandwidth allocation unit is the bandwidth allocation
amount calculation unit 17, for example. The bandwidth allocation
unit regards the start timing detected by the traffic starting
position detection unit as the start timing of the bandwidth
allocation period and allocates a first bandwidth which is an
allocation bandwidth based on the average value of the traffic
amount to the terminating apparatus from the start of the bandwidth
allocation period. The first bandwidth is calculated according to
Equation (2), for example. The bandwidth allocation unit allocates
a second bandwidth which is an allocation bandwidth based on the
standard deviation of the traffic amount to the terminating
apparatus after allocation of the first bandwidth to all
terminating apparatuses is completed. The second bandwidth is
calculated according to Equation (3), for example. The bandwidth
allocation unit distributes and allocates a surplus bandwidth which
is the first and second bandwidth which are already allocated,
subtracted from a bandwidth allocatable in the bandwidth allocation
period to each terminating apparatus in a surplus bandwidth
allocation period which is a period from the end of allocation of
the second bandwidth to all terminating apparatuses to the end of
the bandwidth allocation period.
[0107] The bandwidth allocation unit may calculate the first
bandwidth according to the ratio of the average value of the
traffic amount in a bandwidth allocation target-terminating
apparatus to the sum of average values of the traffic amount in all
terminating apparatuses as illustrated in Equation (5). Moreover,
the bandwidth allocation unit may calculate the second bandwidth
according to the ratio of the standard deviation of the traffic
amount in the bandwidth allocation target-terminating apparatus to
the sum of the standard deviations of the traffic amount in all
terminating apparatuses as illustrated in Equation (6).
[0108] The bandwidth allocation apparatus may further include a
newly-connected terminating apparatus authentication unit that sets
an authentication period for detecting a newly-connected
terminating apparatus in a surplus bandwidth allocation period. The
bandwidth allocation unit does not allocate a bandwidth to the
terminating apparatus in the authentication period notified from
the newly-connected terminating apparatus authentication unit.
[0109] Moreover, the bandwidth allocation apparatus may further
include a traffic excess determination-processing unit. The traffic
excess determination-processing unit is the traffic determination
time threshold-processing unit 19, for example. The traffic excess
determination-processing unit determines that the traffic amount is
abnormally excessive when the traffic amount of an uplink signal
transmitted from the terminating apparatus using the second
bandwidth exceeds a threshold and instructs the bandwidth
allocation unit to perform bandwidth allocation again.
Alternatively, when an uplink signal which uses a surplus bandwidth
is transmitted from the terminating apparatus, the traffic excess
determination-processing unit determines that the traffic amount is
abnormally excessive and instructs the bandwidth allocation unit to
perform bandwidth allocation again.
[0110] According to the above-described embodiments, when bandwidth
is allocated to each terminating apparatus in the bandwidth
allocation period, the period for the allocation based on an
average value and the period for the allocation based on a standard
deviation are separate. By performing bandwidth allocation
performed on the basis of an average value precedently, it is
possible to reduce the waiting period of each terminal station
apparatus.
[0111] The function of the terminal station apparatuses 1, 1a, 1b,
1c, and 1d of the above-described embodiments may be realized by a
computer. In this case, a program for realizing this function may
be recorded on a computer-readable recording medium and the program
recorded on the recording medium may be read and executed by a
processor of a computer system whereby the function is realized.
The "computer system" used herein includes an OS and hardware such
as peripheral devices. Moreover, the "computer-readable recording
medium" means a portable medium such as a flexible disk, a
magneto-optical disk, ROM, or CD-ROM and a storage device built in
the computer system, such as a hard disk. Furthermore, the
"computer-readable recording medium" also encompasses one that
dynamically retains the program for a short period of time, such as
a communication wire in the case of transmission of the program via
a network such as the Internet or a communication line such as a
telephone line, and one that retains the program for a certain
period of time, such as a volatile memory inside the computer
system that serves as a server or a client in that case.
Furthermore, the program may be one that achieves one or some of
the aforementioned functions, or may be one that can achieve the
aforementioned functions in combination with a program already
stored in the computer system.
[0112] While embodiments of the present invention have been
described with reference to the drawings, a specific structure is
not limited to the embodiments but the present invention embraces
design modifications made without departing from the spirit of the
present invention.
INDUSTRIAL APPLICABILITY
[0113] The present invention can be applied to a system that
performs communication by time-division multiple-access.
REFERENCE SIGNS LIST
[0114] 1, 1a, 1b, 1c, 1d: Terminal station apparatus [0115] 2:
Terminating apparatus [0116] 3: Optical splitter [0117] 5:
Upper-level apparatus [0118] 6: Lower-level apparatus [0119] 8:
Access network system [0120] 41, 42: Optical fiber [0121] 11:
Upper-level transceiving functional unit [0122] 12: Lower-level
transceiving functional unit [0123] 13: Traffic information
acquisition unit [0124] 14: Traffic information extraction unit
[0125] 15: Traffic amount estimation unit [0126] 16: Traffic
starting position detection unit [0127] 17, 17c, 17d: Bandwidth
allocation amount calculation unit [0128] 18: Newly-connected
terminating apparatus authentication unit
* * * * *
References