U.S. patent application number 14/609145 was filed with the patent office on 2015-05-21 for communication apparatus, integrated circuit, and communication method.
The applicant listed for this patent is PANASONIC CORPORATION. Invention is credited to Stefano GALLI, Nobutaka KODAMA, Hisao KOGA, Akio KUROBE.
Application Number | 20150139247 14/609145 |
Document ID | / |
Family ID | 40379748 |
Filed Date | 2015-05-21 |
United States Patent
Application |
20150139247 |
Kind Code |
A1 |
GALLI; Stefano ; et
al. |
May 21, 2015 |
COMMUNICATION APPARATUS, INTEGRATED CIRCUIT, AND COMMUNICATION
METHOD
Abstract
In communication method for communicating via a transmission
channel to which first communication apparatuses communicating
based on a first communication system, second communication
apparatuses communicating based on a second communication system,
and third communication apparatuses communicating based on a third
communication system are connected, a data transmission domain and
a notification domain for notifying a data transmission within the
data transmission domain are allocated to the first communication
apparatuses, the second communication apparatuses, and the third
communication apparatuses, respectively. In the communication
method, notices of the data transmission for each of the first
communication apparatuses, the second communication apparatuses and
the third communication apparatuses are transmitted within the
notification domain, and the data transmission domain is
reallocated in accordance with the notices transmitted from the
first, second and third communication apparatuses.
Inventors: |
GALLI; Stefano; (Morristown,
NJ) ; KUROBE; Akio; (Osaka, JP) ; KOGA;
Hisao; (Fukuoka, JP) ; KODAMA; Nobutaka;
(Fukuoka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PANASONIC CORPORATION |
Osaka |
|
JP |
|
|
Family ID: |
40379748 |
Appl. No.: |
14/609145 |
Filed: |
January 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14218459 |
Mar 18, 2014 |
8971422 |
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14609145 |
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14032521 |
Sep 20, 2013 |
8711911 |
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14218459 |
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13403855 |
Feb 23, 2012 |
8565292 |
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14032521 |
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12249109 |
Oct 10, 2008 |
8139626 |
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13403855 |
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Current U.S.
Class: |
370/458 |
Current CPC
Class: |
H04L 12/407 20130101;
H04B 3/544 20130101; H04B 3/542 20130101; H04B 2203/5454 20130101;
H04B 2203/5408 20130101; H04J 3/1694 20130101; H04B 3/54
20130101 |
Class at
Publication: |
370/458 |
International
Class: |
H04J 3/16 20060101
H04J003/16; H04B 3/54 20060101 H04B003/54 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 12, 2007 |
JP |
2007-266950 |
Claims
1. A communication apparatus for communicating based on a first
communication system, via a transmission channel to which another
communication apparatus communicating based on a second
communication system is connected, wherein a first notification
domain for notifying a first data transmission implemented by the
communication apparatus within a data transmission domain is
allocated to the communication apparatus and a second notification
domain for notifying a second data transmission implemented by the
another communication apparatus is allocated to the another
communication apparatus, the communication apparatus, comprising: a
transmitter which transmits a first notice rotated by a first phase
vector via the transmission channel within the first notification
domain; a detector which detects a second notice, which is rotated
by a second phase vector and transmitted from the another
communication apparatus, via the transmission channel within the
second notification domain; and a controller which allocates the
first data transmission within the data transmission domain on the
basis of the first notification domain and the second notification
domain.
2. The communication apparatus according to claim 1, wherein the
controller allocates the data transmission domain in a
predetermined allocation order in accordance with the first notice
and the second notice.
3. The communication apparatus according to claim 1, wherein in
case that the first notice is transmitted, while the second notice
from the another communication apparatus is not detected, the
controller reallocates a data transmission domain for the another
communication apparatus to the communication apparatus.
4. The communication apparatus according to claim 1, further
comprising: a memory for previously storing the allocation order of
the data transmission domain for the communication apparatus in
correspondence with the transmission of the first notice or the
second notice, wherein the controller allocates the data
transmission domain in accordance with the allocation order stored
in the memory.
5. The communication apparatus according to claim 1, wherein the
first notification domain is periodically allocated to the first
communication system, wherein the second notification domain is
periodically allocated to the second communication system.
6. A communication method of a communication apparatus for
communicating based on a first communication system, via a
transmission channel to which another communication apparatus
communicating based on a second communication system is connected,
wherein a first notification domain for notifying a first data
transmission implemented by the communication apparatus within a
data transmission domain is allocated to the communication
apparatus and a second notification domain for notifying a second
data transmission implemented by the another communication
apparatus is allocated to the another communication apparatus, the
communication apparatus, comprising: transmitting a first notice
rotated by a first phase vector via the transmission channel within
the first notification domain; detecting a second notice, which is
rotated by a second phase vector and transmitted from the another
communication apparatus, via the transmission channel within the
second notification domain; and allocating the first data
transmission within the data transmission domain on the basis of
the first notification domain and the second notification
domain.
7. The communication method according to claim 6, wherein in
allocating process, the data transmission domain is allocated in a
predetermined allocation order in accordance with the first notice
and the second notice.
8. The communication method according to claim 6, wherein in case
that the first notice is transmitted, while the second notice is
not detected, a data transmission domain for the another
communication apparatus is reallocated to the communication
apparatus.
9. The communication method according to claim 6, wherein the first
notification domain is periodically allocated to the first
communication system, wherein the second notification domain is
periodically allocated to the second communication system.
Description
[0001] This is a continuation application of application Ser. No.
12/249,109 filed Oct. 10, 2008, which is based on Japanese
Application No. 2007-266950 filed Oct. 12, 2007, the entire
contents of each of which are incorporated by reference herein.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention is related to a communication
apparatus, a communication method, a circuit module and an
integrated circuit, which perform multi-carrier communication
operations among a plurality of communication apparatuses, while
these communication apparatuses are connected to a transmission
channel and share a communication band.
[0004] 2. Background Art
[0005] Since transmission systems such as the OFDM (Orthogonal
Frequency Division Multiplexing) system using a plurality of
sub-carriers have such a great merit that high quality
communications can be carried out even in a severe transmission
channel, these transmission systems are utilized not only in
wireless communications, but also in wired communications such as
power line communications. Generally speaking, frequency bands from
2 MHz to 30 MHz are used as the frequency bands of the power line
communications (refer to, for example, Patent Publication 1). In
addition, technical ideas capable of utilizing broadband covering
higher frequency bands than the above-described frequency band are
recently considered.
[0006] Also, other technical ideas capable of equalizing levels of
time waveforms in order not produce peaks and capable of
suppressing interference and the like are proposed in multi-carrier
communications with employment of a plurality of sub-carriers. In
the above-described peak suppressing technical ideas, in such a
case that a large peak is not present in time waveforms, phases of
respective sub-carriers are rotated by using a default phase
vector, whereas in such a case that a large peak may be monitored,
a phase vector is changed so as to search such a phase vector by
which the peak is not produced. Then, the phases of the respective
sub-carriers are rotated by the searched phase vector (refer to,
for example, Non-patent Publication 1). In multi-carrier
communications, such peak suppressing technical ideas constitute
essential techniques to decrease a difficulty in design of power
amplifiers.
[0007] In the case that a plurality of different logic networks are
formed by employing communication apparatuses such as power line
communication apparatuses connected to transmission channels,
security among these different networks is maintained by employing
network keys and the like. In general, technical specifications of
these communication apparatuses connected to the respective
networks are identical to each other. In other words, phase vectors
which are employed in order to suppress peaks are also identical to
each other. With employment of the above-described technical ideas,
even among the networks which are different from each other in
physical layer levels of communication apparatuses, signals of the
respective networks can be sensed (carrier sensing is available);
if the CSMA (Carrier Sense Multiple Access) technique and the like
are utilized, then it is possible to suppress collisions of
signals; and even when the different networks are present
relatively close to each other, communications can be smoothly
carried out.
[0008] The technical idea described in the Patent Publication 1 has
the following purpose: That is, even in such a case that the plural
sorts of communication apparatuses whose communication systems are
different from each other are connected to the shared transmission
channel, the collisions of the signals are avoided without
executing the demodulating process operation and the like which may
cause relatively heavy loads, and signals outputted from other
communication apparatuses can be readily sensed. In accordance with
this technical idea, such a condition for indicating whether or not
a communication request signal of a control period is present may
change a slot allocation of a data period subsequent to the control
period. Then, since a communication request signal is rotated by a
phase vector, the communication request signal can be firmly
sensed. However, a detailed description is not made of a slot
allocation of a data domain. Thus, in this technical idea, there
are some possibilities that data capable of satisfying a required
delay time cannot be firmly transmitted. [0009] [Patent Publication
1] JP-A-2007-135180 [0010] [Non-patent Publication 1] Denis J. G.
Mestdagh and Paul M. P. Spruyt, "A Method to Reduce the Probability
of Clipping in DMT-Based Transceivers", IEEE Transactions on
Communications, Volume 44, No. 10, pages 1234 to 1238, in 1996
SUMMARY
[0011] The present invention has been made to solve the
above-described problems, and therefore, has an object to provide a
communication apparatus, a communication method, a circuit module
and an integrated circuit, by which even when plural sorts of
communication apparatuses whose communication systems are different
from each other are connected to a shared transmission channel,
while limit of delays in response to data which are tried to be
transmitted by the respective communication apparatuses can be
satisfied, signals can be transmitted in a higher efficiency by
avoiding collisions of signals. Also, another object of the present
invention is to provide a communication method, a communication
apparatus and a communication system, which are capable of reducing
processing workloads for allocating slots executed by the
communication apparatuses in order to avoid collisions of the
signals.
[0012] According to the invention, there is provided a
communication apparatus for communicating based on a first
communication system, via a transmission channel to which a first
other communication apparatus communicating based on the first
communication system, second other communication apparatuses
communicating based on a second communication system, and third
other communication apparatuses communicating based on a third
communication system are connected, wherein a data transmission
domain and a notification domain for notifying a data transmission
within the data transmission domain are allocated to the
communication apparatus and the first other communication
apparatus, the second other communication apparatuses, and the
third other communication apparatuses, respectively,
[0013] the communication apparatus, including:
[0014] a detector which detects a notice transmitted from the
first, second and third other communication apparatuses within the
notification domain;
[0015] a transmitter which transmits a notice for the data
transmission within the notification domain; and
[0016] a controller which reallocates the data transmission domain
in accordance with the notice transmitted from the first, second
and third other communication apparatuses and the notice
transmitted from the transmitter.
[0017] According to the invention, there is provided a
communication method of a communication apparatus for communicating
based on a first communication system, via a transmission channel
to which a first other communication apparatus communicating based
on the first communication system, second other communication
apparatuses communicating based on a second communication system,
and third other communication apparatuses communicating based on a
third communication system are connected, wherein a data
transmission domain and a notification domain for notifying a data
transmission within the data transmission domain are allocated to
the communication apparatus and the first other communication
apparatus, the second other communication apparatuses, and the
third other communication apparatuses, respectively,
[0018] the communication method, including:
[0019] detecting a notice transmitted from the first, second and
third other communication apparatuses within the notification
domain;
[0020] transmitting a notice for the data transmission within the
notification domain; and
[0021] reallocating the data transmission domain in accordance with
the notice transmitted from the first, second and third other
communication apparatuses and the notice transmitted from the
transmitter.
[0022] According to the invention, there is provided a circuit
module of a communication apparatus for communicating based on a
first communication system, via a transmission channel to which a
first other communication apparatus communicating based on the
first communication system, second other communication apparatuses
communicating based on a second communication system, and third
other communication apparatuses communicating based on a third
communication system are connected, wherein a data transmission
domain and a notification domain for notifying a data transmission
within the data transmission domain are allocated to the
communication apparatus and the first other communication
apparatus, the second other communication apparatuses, and the
third other communication apparatuses, respectively,
[0023] the circuit module, including:
[0024] a coupler for interfacing with the transmission channel;
[0025] a detector which detects a notice transmitted from the
first, second and third other communication apparatuses within the
notification domain via the coupler;
[0026] a transmitter which transmits a notice for the circuit
module within the notification domain; and
[0027] a controller which reallocates the data transmission domain
in accordance with the notice transmitted from the first, second
and third other communication apparatuses and the notice
transmitted from the transmitter.
[0028] According to the invention, there is provided an integrated
circuit of a communication apparatus for communicating based on a
first communication system, via a transmission channel to which a
first other communication apparatus communicating based on the
first communication system, second other communication apparatuses
communicating based on a second communication system, and third
other communication apparatuses communicating based on a third
communication system are connected, wherein a data transmission
domain and a notification domain for notifying a data transmission
within the data transmission domain are allocated to the
communication apparatus and the first other communication
apparatus, the second other communication apparatuses, and the
third other communication apparatuses, respectively,
[0029] the integrated circuit, including:
[0030] a detector which detects a notice transmitted from the
first, second and third other communication apparatuses within the
notification domain via a coupler for interfacing with the
transmission channel;
[0031] a transmitter which transmits a notice for the data
transmission within the notification domain via the coupler,
and
[0032] a controller which reallocates the data transmission domain
in accordance with the notice transmitted from the first, second
and third other communication apparatuses and the notice
transmitted from the transmitter.
[0033] According to the invention, there is provided a
communication method for communicating via a transmission channel
to which first communication apparatuses communicating based on a
first communication system, second communication apparatuses
communicating based on a second communication system, and third
communication apparatuses communicating based on a third
communication system are connected, wherein a data transmission
domain and a notification domain for notifying a data transmission
within the data transmission domain are allocated to the first
communication apparatuses, the second communication apparatuses,
and the third communication apparatuses, respectively,
[0034] the communication method, including:
[0035] transmitting notices of the data transmission for each of
the first communication apparatuses, the second communication
apparatuses and the third communication apparatuses within the
notification domain; and
[0036] reallocating the data transmission domain in accordance with
the notice transmitted from the first, second and third
communication apparatuses.
[0037] According to the invention, even when plural sorts of
communication apparatuses whose communication systems are different
from each other are connected to a shared transmission channel,
while limit of delays in response to data which are tried to be
transmitted by the respective communication apparatuses can be
satisfied, signals can be transmitted in a higher efficiency by
avoiding collisions of signals. Also, it is possible to provide a
communication apparatus for reducing processing workloads for
allocating slots executed by the communication apparatuses in order
to avoid collisions of the signals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The above objects and advantages of the present invention
will become more apparent by describing in detail preferred
exemplary embodiments thereof with reference to the accompanying
drawings, wherein like reference numerals designate like or
corresponding parts throughout the several views, and wherein:
[0039] FIG. 1 is a diagram for schematically showing an example of
an arrangement of a power line communication system for realizing a
communication method and a communication system of the present
invention;
[0040] FIGS. 2A and 2B are diagrams for representing outer
appearances of a PLC modem according to an embodiment of the
present invention;
[0041] FIG. 3 is a block diagram for indicating one example as to
hardware of the PLC modem according to the embodiment of the
present invention;
[0042] FIG. 4 is a block diagram for indicating another example as
to hardware of the PLC modem according to the embodiment of the
present invention.
[0043] FIG. 5 is a diagram for showing one example as to a
communication cycle in the power line communication system
according to the embodiment of the present invention;
[0044] FIGS. 6A and 6B are diagrams for indicating examples as to a
control signal domain in the power line communication system
according to the embodiment of the present invention;
[0045] FIG. 7 is a diagram for indicating another example as to a
control signal domain in the power line communication system
according to the embodiment of the present invention;
[0046] FIG. 8 is a diagram for indicating another example as to a
control signal domain in the power line communication system
according to the embodiment of the present invention;
[0047] FIG. 9 is a diagram for indicating another example as to a
control signal domain in the power line communication system
according to the embodiment of the present invention;
[0048] FIG. 10 is a diagram for showing one example as to an
allocation of data slots in the power line communication system
according to the embodiment of the present invention;
[0049] FIG. 11 is a diagram for representing one example as to
notification signals in the power line communication system
according to the embodiment of the present invention;
[0050] FIG. 12 is a diagram for showing one example as to
notification signals and data slots in the power supply
communication system according to the embodiment of the present
invention;
[0051] FIG. 13 is a diagram for showing another example as to
notification signals and data slots in the power supply
communication system according to the embodiment of the present
invention;
[0052] FIG. 14 is a diagram for showing another example as to
notification signals and data slots in the power supply
communication system according to the embodiment of the present
invention;
[0053] FIG. 15 is a diagram for showing another example as to
notification signals and data slots in the power supply
communication system according to the embodiment of the present
invention;
[0054] FIG. 16 is a diagram for showing a table indicative of a
communication systems which is allocated to notification signals
and data slots of a control cycle "T" in the power line
communication system according to the embodiment of the present
invention;
[0055] FIG. 17 is a diagram for representing one example as to a
binary table for indicating whether or not notification signals and
data slots of the control cycle "T" can be used in the power line
communication system according to the embodiment of the present
invention;
[0056] FIG. 18 is a diagram for showing another table indicative of
a communication systems which is allocated to notification signals
and data slots of a control cycle "T" in the power line
communication system according to the embodiment of the present
invention;
[0057] FIG. 19 is a diagram for showing another example as to
notification signals and data slots in the power supply
communication system according to another embodiment of the present
invention; and
[0058] FIG. 20 is a diagram for showing another table indicative of
a communication systems which is allocated to notification signals
and data slots of a control cycle "T" in the power line
communication system according to the embodiment of the present
invention.
DETAILED DESCRIPTION
[0059] Referring now to drawings, a description is made of various
embodiments of the present invention. It should be understood that
although both a power line communication apparatus and a power line
communication system will be exemplified in the below-mentioned
descriptions, the present invention may be similarly applied to
other communication apparatuses and other communication systems
such as wireless LANs (Local Area Networks).
[0060] FIG. 1 is a diagram for schematically showing one example as
to an arrangement of a power line communication system which
realizes the communication method and the communication system,
according to an embodiment of the present invention. The power line
communication system of FIG. 1 is equipped with a plurality of PLC
(Power Line Communication) modems 10A1, 10A2, 10B1, 10B2, 10C1,
10C2, and 10C3, which are connected to a power line 1A. In the
below-mentioned descriptions, when individual PLC modems are
referred to, the PLC modems 10A1, 10A2, 10B1, 10B2, 10C1, 10C2, and
10C3 are described respectively, whereas when a PLC modem is
generally referred to, a PLC modem 10 is simply described.
[0061] In FIG. 1, the power line 1A is illustrated by employing a
single line. However in an actual case, the power line 1A is made
of two, or more pieces of conducting lines, and the PLC modem 10 is
connected to two conducting lines among these conducting lines.
[0062] As will be later described in detail, the PLC modems 10
contain LAN modular jacks such as RJ45. A telephone set 51 equipped
with a display device, a door interphone 52, televisions (TV) 53
and 56, a video server 54, a personal computer (PC) 55, and a
broadband router (BB router) 57 are connected to these modular
jacks, while the broadband router 57 is connected to the Internet
58.
[0063] The PLC modems 10A1, 10A2, 101, 10B2, 10C1, 10C2, and 10C3,
which constitute the power line communication system of FIG. 1,
perform communication operations based upon three different sorts
of communication systems, namely, the PLC modems 10A1 and 10A2
perform communication operations based upon a communication system
"A"; the PLC modems 10B1 and 10B2 perform communication operations
based upon a communication system "B"; and the PLC modems 10C1,
10C2 and 10C3 perform communication operations based upon a
communication system "C." It should be understood that although the
above-described communication systems "A" to "C" indicate various
sorts of specifications such as protocols, modulation systems, and
frequency bands, these communication systems "A" to "C" correspond
to the same communication systems in view of such an operation that
the multi-carrier communication of the OFDM (Orthogonal Frequency
Division Multiplexing) system is carried out. Since the power line
communication system corresponds to one example of communication
systems capable of realizing the communication system according to
the present invention, other communication systems such as wireless
LANs may be alternatively employed in order to realize the
above-described communication method.
[0064] Next, a concrete structural example of the PLC modem 10 is
shown in FIG. 1. FIGS. 2A and 2B are diagrams for illustratively
showing outer appearances of a PLC modem 10; concretely speaking,
FIG. 2A is an outer appearance perspective view for representing a
front plane of this PLC modem 10; and FIG. 2B is a rear view of the
PLC modem 10. The PLC modem 10 shown in FIG. 2 contains a housing
100, and an indicator 23 is provided on a front plane of the
housing 100. As indicated in FIG. 2A, the indicator 23 is
constituted by LEDs (Light Emitting Diodes) 23A, 23B and 23C. Also,
as represented in FIG. 2B, a power supply connector 21 and a LAN
(Local Area Network) modular jack 22 such as RJ45 are provided on a
rear plane of the housing 100. A power supply cable 1B is connected
to the power supply connector 21; and a LAN cable (which is not
indicated in FIG. 2) is connected to the modular jack 23. It should
also be understood that while a D-Sub (D-subminiature) connector
may be provided in the PLC modem 10, a D-Sub cable may be
alternatively connected to this D-Sub connector.
[0065] FIG. 3 is a block diagram for representing one example as to
hardware of the PLC modem 10. As shown in FIG. 3, the PLC modem 10
is equipped with a circuit module 30 and a switching power supply
20. The switching power supply 20 is employed in order to apply
various sorts of voltages (for example, +1.2 V, -3.3 V, and +12 V)
to the circuit module 30. The switching power supply 20 contains,
for example, a switching transformer, and a DC/DC converter (both
elements are not shown). Electric power is supplied to the
switching power supply 20 from a power supply connector 21 via an
impedance upper 27 and an AC/DC converter.
[0066] In a circuit module 30, a main IC (Integrated circuit) 11,
an AFE.cndot.IC (Analog Front End IC) 12, a low-pass filter (LPF)
13, a driver IC 15, a coupler 16, a band-pass filter (BPF) 17, a
memory 18, an Ethernet PHY.cndot.IC (Physical layer-Integrated
Circuit) 19, and an AC cycle detcctor 60 are provided. The coupler
16 is connected to the power supply connector 21, and is further
connected to the power line 1A via the power line 1B, the power
supply plug 25, and an outlet 2. Also, the indicator 23 is
connected to the main IC 11, and a LAN cable 26 is connected to the
modular jack 22 in order to be connected to an electric appliance
such as a personal computer. It should also be noted that the main
IC 11 functions as a communication control unit in such a case that
the main IC 11 performs a power line communication.
[0067] The main IC 11 is constituted by a CPU (Central Processing
Unit) 11A, PLC.cndot.MAC (Power Line Communication/Media Access
Control layer) blocks 11C1 and 11C2, and PLC.cndot.PHY (Power Line
Communication/Physical layer) blocks 11B1 and 11B2. The CPU 11A
implements a 32-bit RISC (Reduced Instruction Set Computer)
processor. The PLC.cndot.MAC block 11C2 manages a MAC layer (Media
Access Control layer) of a transmission signal, and the
PLC.cndot.MAC block 11C1 manages a MAC layer of a reception signal.
Also, the PLC.cndot.PHY block 11B2 manages a PHY layer (Physical
layer) of the transmission signal, and the PLC.cndot.PHY block 11B1
manages a PHY layer of the reception signal. The AFE.cndot.IC 12 is
arranged by a D/A converter (DAC) 12A, an A/D converter (ADC) 12D,
and variable gain amplifiers (VGA) 12B and 12C. The coupler 16 is
constituted by a coil transformer 16A and coupling capacitors 16B
and 16C. It should also be understood that the CPU 11A controls
operations of the PLC.cndot.MAC blocks 11C1, 11C2 and the
PLC.cndot.PHY blocks 11B1, 11B2, and also, controls the entire
operations of the PLC modem 10 by utilizing data stored in the
memory 18.
[0068] In FIG. 3, while the PLC.cndot.MAC blocks 11C1 and 11C2 and
the PLC.cndot.PHY blocks 11B1 and 11B2 are provided to be employed
for transmission and reception, respectively. Alternatively, while
a PLC.cndot.MAC block 11C and a PLC.cndot.PHY block 11B (not shown)
may be provided to share in transmission and reception
operations.
[0069] Similar to a general modem, the main IC 11 is an electric
circuit (LSI) which performs signal process operations including a
basic control operation and modulating/demodulating operations so
as to execute data communication operations. In other words, the
main IC 11 modulates reception data outputted from a communication
terminal such as a PC (Personal Computer), and then, outputs the
modulated data as a transmission signal (transmission data) to the
AFE.cndot.IC 12. Further, the main IC 11 demodulates a signal which
is inputted from the side of the power line 1A via the AFE.cndot.IC
12, and then, outputs the demodulated signal as a reception signal
to the communication terminal such as the PC.
[0070] The AC cycle detector 60 produces such a synchronization
signal which is required in order that the respective PLC modems 10
execute control operations at common timing. The AC cycle detector
60 is arranged by a diode bridge 60a, resistors 60b and 60c, a DC
power supply unit 60e, and a capacitor 60d. The diode bridge 60a is
connected to the resistor 60b. The resistor 60b is connected series
to the resistor 60c. Both the resistors 60b and 60c are connected
parallel to one terminal of the capacitor 60d. The DC power supply
unit 60e is connected to the other terminal of the capacitor 60d.
Concretely speaking, the synchronization signal is processed in
accordance with the below-mentioned manner. That is, the AC cycle
detector 60 detects zero cross points of an AC power waveform AC of
a commercial power supply, which is applied to the transmission
channel 1A, namely, such zero cross points of AC voltage waveform
constructed of a sine wave having a frequency of 50 Hz, or 60 HZ.
Then, the AC cycle detector 60 produces a synchronism signal while
the timing for detecting the zero cross points is defined as a
reference. As one example of the above-described synchronization
signal, a rectangular wave may be conceived which is constituted by
a plurality of pulses synchronized with the zero cross points of
the AC power waveform. The AC cycle detector 60 is not necessarily
required. In this alternative case, the synchronization among these
PLC modems 10 may be established by employing a synchronization
signal contained in a communication signal.
[0071] A communication operation by the PLC modem 10 shown in FIG.
3 is roughly carried out as follows: That is, data inputted from
the modular jack 22 is supplied via the Ethernet PHY.cndot.IC 19 to
the main IC 11 and the supplied data is digitally processed, so
that a digital transmission signal is produced which is
D/A-converted into an analog signal by the D/A converter (DAC) 12A
of the AFF.cndot.IC 12, and then, the analog signal is outputted to
the power line 1A via the low-pass filter 13, the driver IC 15, the
coupler 16, the power supply connector 21, the power supply cable
1B, the power supply plug 25, and also, the outlet 2.
[0072] A signal received from the power line 1A is supplied via the
coupler 16 to the band-pass filter 17, and then, a gain of the
supplied signal is adjusted by the variable gain amplifier (VGA)
12C of the AFE.cndot.IC 12. Thereafter, the gain-adjusted signal is
A/D-converted by the A/D converter (ADC) 12D into a digital signal,
and then, the digital signal is supplied to the main IC 11 so as to
be digitally processed, so that the inputted analog signal is
converted into the digital data. Then, this digital data is
outputted via the Ethernet PHY.cndot.IC 19 from the modular jack
22.
[0073] FIG. 4 is a block diagram for showing another example as to
the hardware of the PLC modem 10. As represented in FIG. 4, a PLC
modem 10 contains two sets of hardware used to perform
communication process operations, and other arrangements identical
to the arrangements of the PLC modem 10 shown in FIG. 3. That is,
while the PLC modem 10 of FIG. 4 contains both a circuit module 30
and a switching power supply 20, a power supply voltage is applied
from the power supply connector 21 via the impedance upper 27 and
the AC/DC converter 24 to the switching power supply 20.
[0074] A circuit module 30 is equipped with one hardware which is
arranged by a main IC (Integrated Circuit) 31, an AFE.cndot.IC
(Analog Front End/Integrated Circuit) 32, a low-pass filter (LPF)
33, and a driver IC 35 in order to perform one set of a
communication process operation. The circuit module 30 is further
equipped with another hardware which is arranged by a sub-IC 41, an
AFE.cndot.IC 42, a low-pass filter 43, and a driver IC 45 in order
to perform one set of a communication process operation. Since two
sets of the above-described hardware are basically identical to the
above-described main IC 11, AFE.cndot.IC 12, low-pass filter 13,
and driver IC 15 of the PLC modem 10 shown in FIG. 3, detailed
descriptions thereof will be omitted. Also, such a technical
structure that a coupler 16, a band-pass filter (BPF) 17, a memory
18, and a Ethernet PHY.cndot.IC 19 are provided in the PLC modem 10
of FIG. 4 is identical to that of the PLC modem 10 of FIG. 3. The
main 1C 31 may also function a communication control operation in
such a case that a power line communication operation is carried
out. Also, the memory 48 stores thereinto data which is used by the
sub-IC 41.
[0075] The power line communication system indicated in FIG. 1
performs a communication operation by such a manner that the PLC
modem 10 connected to the power line 1A transmits a control signal
for controlling communication operations among the PLC modems 10
within a control signal domain, and also, transmits data within a
data signal domain subsequent to the above-described control signal
domain. A signal domain for combining one control signal domain
with a data signal domain subsequent to this control signal domain
will be referred to as a communication cycle. As a consequence, a
control signal domain is present at a head of each of these
communication cycles.
[0076] A data signal domain corresponds to a time domain in which a
plurality of control cycles are continuously provided, while each
of the respective control cycles contains a plurality of data
slots. A data slot corresponds to such a time domain that data
supplied from a specific PLC modem are grouped, and then, the
grouped data is transmitted. Since a control signal domain is
provided at a head of a communication cycle, both a control cycle
of the head of the communication cycle, and a head data slot of the
head control cycle are made short by the control signal domain. A
data slot is a data slot formed by the TDM (Time Division
Multiplexing) system, and however, may contain a data slot formed
by the FDM (Frequency Division Multiplexing).
[0077] A control signal which is transmitted within a control
signal domain contains such a notification signal within a data
signal domain subsequent to this control signal domain, while the
notification signal notifies that data is transmitted from a PLC
modem which has transmitted the above-described control signal.
Within a data signal domain after a notification signal is
transmitted, a data signal is transmitted from the PLC modem which
has transmitted the above-described notification signal by a
plurality of data slots which uniquely correspond to at least this
notification signal. The data slots which uniquely correspond to
the notification signal contains a plurality of data slots among
data slots which constitute each of control cycles, so that data
from a PLC modem are transmitted without having a large interval
within a data signal domain. As a consequence, while limits of
delays in response to data which are tried to be transmitted by the
respective communication apparatuses can be satisfied, data signals
can be transmitted in a higher efficiency by avoiding collisions of
data signals.
[0078] FIG. 5 represents one example of a communication cycle
conducted in the power line communication system according to the
embodiment of the present invention. A single communication cycle
"H" is constituted by a plurality (namely, 8 pieces) of control
cycles "T0" to "T7" (refer to (a) in FIG. 5), and each of control
cycles "T" is constituted by a plurality (namely, 10 pieces) of
data slots "S0" to "S9" (refer to (b) in FIG. 5). A head portion of
the head data slot "S0" of the control cycle "T0" is secured as a
control signal domain "C." As a result, this data slot "S0" is made
slightly narrower, as compared with other data slots.
[0079] In the example of FIG. 5, a control cycle "T" corresponds to
two time periods (namely, 40 msec in case of 50 Hz) of the power
supply, and a communication cycle "H" corresponds to 40*8=320 msec.
Also, a width of a single data slot corresponds to 40/10=4
msec.
[0080] The control signal domain "C" corresponds to a time domain
which is provided at a head of a communication cycle "H", and
contains at least a notification signal domain "R" during which the
above-described notification signal is transmitted (refer to (c) in
FIG. 5). In the example of (c) in FIG. 5, while the notification
signal domain "R" contains three request slots, the respective
request slots are provided in order to transmit a notification
signal ".PHI.A" of the communication system "A", a notification
signal ".PHI.B" of the communication system "B", and a notification
signal "(C" of the communication system "C." A width of each of the
request slots is, for example, 80 .mu.sec. A guard time of 80
.mu.sec is provided before and after each of the request slots. As
a consequence, the notification signal domain "R" of FIG. 5 which
has the three request slots is equal to 720 .mu.sec as an entire
time.
[0081] FIGS. 6A and 6B show detailed contents of the
above-described control signal domain "C." As indicated in FIGS. 6A
and 6B, a control signal is a multi-carrier signal which utilizes a
plurality of sub-carriers having frequencies from 2 MHz to 30 MHz,
and corresponds to such a signal that known data (for example, all
of data are "1") are rotated by a predetermined phase vectors. A
rotating process operation based upon a phase vector may be carried
out by the PLC.cndot.PHY blocks of FIG. 3 and FIG. 4, for instance,
as shown in the Patent Publication 1, so that descriptions thereof
will be omitted. Also, as will be discussed later, a notification
signal of the control signal domain "C" is utilized so as to
determine a data transmission slot, and also, a detection of a
control signal is also carried out by the PLC.cndot.PHY blocks. It
should also be understood that in such a PLC modem (namely, PLC
modems 100 of FIG. 3 and FIG. 4) equipped with a plurality of
PLC.cndot.PHY blocks, a transmission of a control signal is carried
out by one PLC.cndot.PHY block (namely, PLC.cndot.PHY block 11 B2
shown in FIG. 3, and PLC.cndot.PHY block 42D indicated in FIG. 4).
As represented in FIGS. 6A and 6B, in such a case that the
notification signals corresponding to the different communication
systems are transmitted by employing the respective different
request slots, such notifications which are rotated by the
respective different phase vectors may not be used.
[0082] FIG. 6A indicates an example having slots which are employed
in order to transmit a synchronization signal "S" as a control
signal, and also to transmit notification signals ".PHI.A",
".PHI.B", ".PHI.C" corresponding to the communication systems "A",
"B", "C", respectively. FIG. 6B indicates another example having
slots which are employed in order to transmit the notification
signals, ".PHI.A", ".PHI.B", ".PHI.C", corresponding to the
communication systems "A", "B", "C", without the synchronization
signal "S." Alternatively, not only the control signal, the
synchronization signal and the notification signals are
transmitted, but also other control signals may be transmitted.
Furthermore, with respect to the notification signals, not only the
request slots for transmitting three sorts of the above-described
notification signals ".PHI.A", ".PHI.B", ".PHI.C" are secured, but
also other request slots for transmitting four sorts, or more sorts
of notification signals may be alternatively secured.
[0083] FIG. 7 shows another example as to a control signal domain
"C." In the example of FIG. 7, only a single notification signal
can be transmitted within a single control domain "C." In other
words, in communication cycles "H0" and "H3", the notification
signal ".PHI.A" corresponding to the communication system "A" can
be transmitted by request slots allocated thereto; in a
communication cycle "H1", the notification signal ".PHI.B"
corresponding to the communication system "B" can be transmitted by
a request slot allocated thereto: and, in a communication cycle
"H2", the notification signal ".PHI.C" corresponding to the
communication system "C" can be transmitted by a request slot
allocated thereto. When the above-described idea of the control
signal domain "C" is employed, a decision for decide whether or not
a notification signal is present can be made by merely detecting
whether or not a single control signal is present within a single
control signal domain. As a result, the process for detecting the
notification signal can be simplified, and the arrangement of the
communication apparatus can be made simple. It should be understood
that, as indicated in FIG. 7, since the communication systems "A"
to "C" with respect to the respective communication cycles ".PHI.A"
to ".PHI.C" are allocated in a periodic manner, the detecting
process for the notification signals can be simplified.
[0084] FIG. 8 is another example as to notification signals within
a control signal domain "C" (note that in FIG. 8 and succeeding
drawings, only communication cycle "H0" is described). This example
of FIG. 8 corresponds to such a case that there is one request slot
for transmitting a notification signal corresponding to a
communication system, and as to the respective notification
signals, such notification signals are employed which are rotated
by phase vectors different from each other. In other words, in
communication cycles "H0" and "H3", the notification signal
".PHI.A" corresponding to the communication system "A" is
transmitted; in communication cycles "H1" and "H4", the
notification signal ".PHI.B" corresponding to the communication
system "B" is transmitted; and in a communication cycle "H2", the
notification signal ".PHI.C" corresponding to the communication
system "C" is transmitted. When the above-described idea of the
control signal domain "C" is employed, since only a single
notification signal is transmitted within a single control signal
domain, one corresponding phase vector is merely detected from a
plurality of different phase vectors within a single control slot.
As a result, the arrangement of the communication apparatus can be
made simple. Also, a control domain can be made narrow, so that a
communication efficiency can be improved. In the above case, since
only one notification signal is contained in each request slot, low
precision of the AC cycle detector 60 which is provided in the
communication apparatus for receiving the notification signals
".PHI.A", ".PHI.B" and ".PHI.C", for detecting the zero-cross point
of AC power waveform may be accepted. Accordingly, a low-cost AC
cycle detector can be used in this case.
[0085] FIG. 9 is another example as to notification signals within
a control signal domain "C." That is, in the example of FIG. 9, two
sets of request slots are provided which are employed in order to
transmit notifications corresponding to three sorts of
communication systems. In this example, as to notification signals
".PHI.A" and ".PHI.B", such notification signals are employed which
are rotated by phase vectors different from each other. In other
words, when both the notification signals ".PHI.A" and ".PHI.B" are
transmitted, this communication system corresponds to the
above-described communication system "A", whereas when only the
notification signal ".PHI.A", or the notification signal ".PHI.B"
is transmitted, this communication system corresponds to either the
communication system "B" or the communication system "C." In such a
case that both the notification signals ".PHI.A" and ".PHI.B" are
transmitted, other communication systems may be alternatively set
based upon a signal transmission order. For example, when the
notification signals .PHI.A and .PHI.B are transmitted in this
order, TDM of the communication system "A" may be set, whereas when
the notification signals .PHI.B and .PHI.A are transmitted in this
order, FDM of the communication system "A" may be set. With
employment of this notification signal transmission method, even
when transmission slots of notification signals are located
adjacent to each other, the notification signals can be firmly
detected, and the communication efficiency can be improved by
narrowing the control signal domains. Also, the communication
systems can be discriminated from each other by combining the
plurality of notification signals with each other. As a result, the
communication efficiency can be furthermore improved by narrowing
the control signal domain.
[0086] Next, a description is made of such an allocation example
that data slots are allocated within a data signal domain after a
notification signal is transmitted. FIG. 10 is a diagram for
representing one example as to an allocation of data slots. In the
example of FIG. 10, such a data slot allocation is performed that
the PLC modems which utilize three sorts of the communication
systems (communication systems A, B, C) as shown in FIG. 1 are
connected to a power line, and furthermore, such a PLC modem (not
shown in FIG. 1) which utilizes a communication system
(communication system D) having a low priority performs a
communication operation at the same time when the first-mentioned
PLC modems perform communication operations. As shown in FIG. 10,
in all of control cycles "T" within a single communication cycle
"H", the same data slots are allocated. If these data slots are
allocated, then while limits of delays in correspondence with data
which are tried to be transmitted by respective communication
apparatuses connected to the common transmission channel can be
satisfied, collisions of signals can be avoided, so that data can
be transmitted in a high efficiency.
[0087] FIG. 10 is such an exemplification that the data slots are
allocated under such a status that four sorts of notification
signals are transmitted. Alternatively, the notification signals
may be transmitted within control signal domains of the respective
allocated communication cycles, or may be transmitted within the
same control signal domain. FIG. 11 indicates an example as to
statues of these notification signals. (a) in FIG. 11 shows an
example in such a case that the notification signals are utilized
in communication cycles to which three sorts of the communication
systems (namely, communication systems, "A", "B", "C") are
allocated, and a communication system (communication system "D")
having a low priority is present. In each of the communication
cycles "H", the notification signal of the communication system
(communication system "D") having the low priority is transmitted
after the notification signals of the communication systems "A",
"B", "C", respectively. Also, (b) in FIG. 11 shows another example
in such a case that the notification signals are transmitted within
a control domain in which three sorts of the communication systems
(namely, communication systems "A", "B", "C") are identical to each
other, a communication system (communication system "D") having a
low priority is present. In each of the communication cycles "H",
the notification signal of the communication system (communication
system "D") having the low priority is transmitted after the
notification signals of the communication systems "A", "B", "C".
Similar to (a) in FIG. 11, (c) in FIG. 11 shows an example in such
a case that the notification signals are utilized in communication
cycles to which three sorts of the communication systems (namely,
communication systems "A", "B", "C") are allocated, and a
communication system (communication system "D") having a low
priority is present. However, (c) in FIG. 11 shows such a case that
the notification signals of the communication systems "A", "B", and
"C" are transmitted in accordance with the method represented in
FIG. 9. In each of the communication cycles "H", the notification
signals of the communication systems A, B, C are transmitted in
accordance with the method shown in FIG. 9 before the notification
signal of the communication system (communication system "D")
having the low priority. Also, with respect to the communication
system (communication system "D") having the low priority, the
notification signal may not always be transmitted within all of the
control domains where the notification signal can be transmitted.
It should also be noted that in this case, an interval of
transmission signals of the communication systems "D" must be
previously determined. For example, as the predetermined time
interval, a notification signal of the communication system "D"
must be transmitted one time within three control domains.
[0088] FIG. 12 indicates data slots in the case that notification
signals ".PHI.A", ".PHI.B", ".PHI.C", which correspond to the
respective communication systems "A", "B", "C" are transmitted
within a control signal domain "C" of each allocated communication
cycle "H." It is so assumed that the notification signals
corresponding to the communication system "D" are transmitted in
all of the communication cycles, as shown in FIG. (a), (b) or (c)
in 11. As represented in FIG. 12, when a notification signal can be
transmitted within an allocated communication cycle, such a
notification signal corresponding to one communication system is
effective until a communication cycle during which the same
notification signal can be transmitted at the next time. In other
words, within communication cycles subsequent to at least the
communication cycle "H2", notification signals corresponding to the
communication systems "A", "B", "C", "D" are effective. As a
result, similar to FIG. 10, the data slots are allocated to the
communication systems "A", "B", "C", and "D."
[0089] FIG. 13 is a diagram for indicating data slots under the
same condition as that of FIG. 11 except that notification signals
corresponding to the notification system "D" are not transmitted.
As apparent from FIG. 13, slots from the data slot "S1" up to the
data slot "S9" are allocated to the communication systems "A", "B",
"C" in a periodic manner. On the other hand, a slot "S0" is
allocated to a communication system corresponding to such a
notification signal which is transmitted immediately before this
slot "S0." That is, within a data domain of a communication cycle
"H2" of FIG. 13, the communication system "C" corresponding to the
notification which was transmitted immediately before the slot "S0"
is allocated to this slot "S0." Since the above-described slot
allocating method is employed, the respective communication systems
"A" to "D" can use the slot "S0" at the same ratio.
[0090] FIG. 14 shows another example of data slots. The example of
FIG. 14 indicates structures of data slots in such a case that a
notification signal corresponding to the communication system "C"
has not been transmitted within a control signal domain allocated
to the communication system "C", namely, in the case that the
notification signal has not be transmitted within a control signal
domain of a communication cycle "H2" allocated to the communication
system "C." In this case, a communication system which is allocated
to the data slots S1, S2, S4, S5, S7, and S8 is the communication
system "A" or the communication system "B." The communication
systems "A" and "B" are alternately allocated to the remaining data
slots S0, S3, S6, and S9. It should also be noted that the
communication systems are not always allocated to the data slots in
the above-described alternate manner, but may be previously
determined by considering system latency, and the like.
[0091] FIG. 15 shows another example of data slots. FIG. 15
represents such a case that only notifies signals corresponding to
the communication system "B" are transmitted. In this case, all of
the data slots are allocated to this communication system "B."
[0092] As previously described, in such a case that a notification
signal corresponding to a specific notification system is present,
data slots to be allocated in responding to this notification
signal contain such data slots which are previously and uniquely
allocated to the respective communication systems. For instance, in
the case that a notification signal of the communication system "A"
is transmitted, the data slots to be allocated thereto contains the
data slots S1, S4, S7, which are uniquely allocated to the
communication system "A". Also, in the case that a notification
signal of the communication system "B" is transmitted, the data
slots to be allocated thereto have contained the data slots S2, S5,
S8, which are uniquely allocated to the communication system "B".
Furthermore, in the case that a notification signal of the
communication system "C" is transmitted, the data slots to be
allocated thereto have contained the data slots S3, S6, S9, which
are uniquely allocated to the communication system "C". Then, such
data slots allocated to such communication systems whose
notification signals have not be transmitted are properly allocated
to other communication systems whose notification signals are
transmitted. FIG. 16 is a table for indicating notification signals
which are present (are transmitted) in a transmission channel, and
communication systems which are allocated to data slots of a
control cycle "T." While such a table is previously stored in the
PLC modem 10, a data slot capable of transmitting data is
determined based upon a notification signal present in the
transmission channel, and then, the data is transmitted by using
this determined data slot. For instance, when the own communication
system is the communication system "A", while the PLC modem 10 has
previously stored thereinto a binary table shown in FIG. 17, the
PLC modem 10 may transmit data by employing a data slot indicative
of "1" in accordance with statuses of other existing systems.
Alternatively, while the PLC modem 10 has previously prepared all
of binary tables corresponding to the communication systems "A",
"B". "C", the PLC modem 10 may switch these binary tables in
correspondence with a sequence connected to the transmission
channel. For example, in such a case that another single
communication system has already been connected to the transmission
channel at the time when the own communication system is connected
to the transmission channel, the communication system already
connected to the transmission channel is the communication system
"A"; the own communication system is the communication system "B";
and the communication system which will be thereafter connected is
the communication system "C."
[0093] It should also be noted that while the present system is not
restricted only to a total number of these communication systems,
the tables are constructed in accordance with the above-described
example in conjunction with the number of communication systems, so
that a similar effect may be expected. For example, in such a case
that the major communication system is constructed of two systems
(namely, communication systems "A" and "B"), it is sufficient to
realize such a data slot allocation table as shown in FIG. 18.
[0094] As another embodiment of the present invention, a
description is made of such a case that each of communication
systems holds a plurality of tables with reference to FIG. 19 and
FIG. 20. Although only one table was held in the above-described
embodiment, in the present embodiment, while each of the
communication systems holds a plurality of tables, a description is
made how to update the tables by using either table updating slots
or different phase vectors in response to a total number of these
tables.
[0095] In the present embodiment, a slot "X" is added by
considering two tables (alternatively, phase vector may be added in
order to share other slots). Such a case that the respective
communication systems alternately transmit notification signals
will now be considered. At this time, as represented in FIG. 19,
since a notification signal ".PHI.X" is transmitted in a slot "X"
within the same control domain as such a control domain during
which each of the communication systems transmits a notification
signal, such an event that a table to be used is updated (namely,
presently used table is switched to another table) is notified to
another communication system. In other words, in FIG. 19, the
communication system "B" transmits the notification signal ".PHI.X"
in the slot "X" of the same control domain as the control domain
for the own notification. In this case, while the communication
systems "A", "B", "C" are present, approximately 3.3 pieces of
slots are normally allocated to the communication system "B" ("3.3
pieces" is calculated by that, among 10 pieces of data slots, 3
slots are continuously secured, and S0 slot is secured only 1 time
within 3 times of communication cycle "H"). However, in FIG. 19,
since the notification signal is transmitted in the slot "X", it is
so assumed that such a fact that, for example, only 2 pieces of
slots are used without utilizing approximately 3.3 pieces of slots
is notified. As previously explained, a slot is provided within the
same control domain as the control domain for the notification
signal, and then, another notification signal (namely, notification
signal ".PHI.X" in FIG. 19) is transmitted within the provided
slot. As a result, a variation may be made in the method for taking
the fixed slots (namely, table to be utilized). In other words,
since the above-described control operation is carried out, each of
the communication systems can hold the plurality of tables, and the
respective communication systems can utilize the plurality of
tables while switching these plural tables.
[0096] FIG. 20 is one example as to a slot allocation table, namely
indicates such a table which is utilized when the communication
system "B" has transmitted signals within the same control domains
(in this example, it is so assumed that communication system "B"
has two tables shown in FIG. 16 and above example). Although tables
are actually present in other communication systems, changed tables
are described as to only the communication system "B" as a typical
example. As indicated in FIG. 20, the communication system "B" uses
only two pieces of slots (namely, slots "S2" and "S8"). Since such
a control operation is carried out, it is possible to utilize such
a table which is different from the table of FIG. 16. It should
also be noted that the table of FIG. 20 is not fixed, but is merely
one example, and therefore, may be arbitrarily set. In other words,
in the table shown in FIG. 20, as compared with the table of FIG.
16, the slots which the system "B" can utilize are deleted.
However, a plurality of completely different tables (namely, tables
having different meanings) may be formed, and these completely
different tables may be switched in response to a control signal.
As only the use condition with respect to the present invention,
the same tables are held in all of the communication systems, and
the same table is utilized by the respective communication
apparatuses in accordance with the signal of the control
domain.
[0097] Although the above-described embodiments have exemplified
such a case that the respective communication systems alternately
transmits the notification signals, other notification signal
transmitting methods may be similarly employed by employing the
table updating slot. Also, a plurality of table updating slots may
be provided, and therefore a plurality of tables can be
constructed.
[0098] As previously described, when the PLC modern 10 connected to
the power line 1A transmits the data, the PLC modem 10 transmits
the control signal, receives the control signal, transmits the data
signal, and receives the data signal. These process operations are
mainly carried out by the main IC 11.
[0099] Even when plural sorts of communication apparatuses whose
communication systems are different from each other are connected
to the shared transmission channel, the present invention is
usefully employed as a communication method, a communication
apparatus, a communication system, and the like, which can perform
the following process operations: That is, while limits of delays
in response to data which are tried to be transmitted by the
respective communication apparatuses can be satisfied, signals can
be transmitted in a higher efficiency by avoiding collisions of
signals. Also, the present invention is useful as such a
communication method, a communication apparatus, a communication
system, and the like, which are capable of reducing processing
workloads for allocating the slots executed by the communication
apparatus in order to avoid the collisions of the signals.
[0100] This application is based upon and claims the benefit of
priority of Japanese Patent Application No. 2007-266950 filed on
Oct. 12, 2007, the contents of which are incorporated herein by
reference in its entirety.
* * * * *