Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
2000-05-19
2004-04-13
Kizou, Hassan (Department: 2662)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S345000, C370S465000, C709S230000
Reexamination Certificate
active
06721338
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communication apparatus, synchronous communication system, communication interference suppress method and computer-readable recording medium recorded with a communication interference suppress program. Particularly, the present invention relates to a communication apparatus, synchronous communication system, communication interference suppress method and computer-readable recording medium recorded with a communication interferences suppress program to suppress interference caused by a plurality of synchronous communication systems present in the same space.
2. Description of the Background Art
FIGS. 5A and 5B
are diagrams to describe the background of the present invention. Referring to
FIG. 5A
, a plurality of wireless communication systems (simply referred to as “system” hereinafter) are present simultaneously in the same space. Communication of respective systems are effected independently. The signals issued from respective systems during the communication interfere with each other (bold arrow in
FIG. 5A
) and disturb communication therebetween.
Specifically in
FIG. 5A
, two systems SY
1
and SY
2
are present at the same time in the same space. System SY
1
includes a host H
1
and peripherals P
11
-P
13
. System SY
2
includes a host H
2
and peripherals P
21
-P
23
.
FIG. 5A
schematically shows that the signal issued by the communication of system SY
1
affects system SY
2
to disturb the communication between host H
2
and peripheral P
22
, and also that the signal issued from the communication of system SY
2
affects system SY
1
to disturb the communication between host H
1
and peripheral P
13
.
Definition of “the same space” is set forth in the following. In the case where a signal issued from a system affects another system when a plurality of systems are operated adjacent to each other at the same time, i.e., interference occurs by the signal, the plurality of systems are located in the same space.
Definition of a host and a peripheral is set forth in the following. In a 1-N communication system where communication is to be carried out between one host and N (N≧1) peripherals, the host is a control station to control communication in that system whereas a peripheral is a controlled station subjected to communication-operation under control of the host.
In order to suppress the effect of interference caused by a signal from another system, control must be provided to assign a communication processing time for each system by time-division method and carry out the communication process only during the communication processing time assigned to respective systems.
In order to operate simultaneously a plurality of systems that carry out 1-N communications, a centralized control system or a decentralized control system can be employed. In the centralized control system, a station that is a third party is provided to directly control the host that carries out centralized control in each system. By time-dividing and applying the aforementioned communication processing time which is the communication executable time with respect to each system, arbitration of the communication process between the systems is provided. In the decentralized control system, the host in each system adjusts the processing time applied to its own system in an autonomous distributed method.
In the centralized control system, a third party station to provide arbitration of the communication process between the systems must be prepared to provide control of respective hosts. Also, the control procedure employed between the hosts and the station that carries out arbitration must be defined. It is to be noted that this system to provide control of the hosts is not required all the time. Provision of such a station is effective only in the case where there are a plurality of systems at the same time in the operating environment of that station. In an operating environment where there is only a single system, the station will not provide any function and the feature to control the host will not be used efficiently. Thus, many resources will be wasted.
The IrDA Control Specification ((Formerly IrBus) Final Specification—Final Revision 1.0, Jun. 30, 1998) is known as one distributed communication system. According to the this specification, transmission/reception control is effected in a centralized manner between the host and a plurality of peripherals to support communication between one host and a plurality of peripherals. By shifting the communication timing between the plurality of 1-n communication systems in a predetermined band tolerance, the plurality of systems can be operated simultaneously.
Details will be described hereinafter with reference to
FIGS. 5B and 6
.
FIG. 5B
shows the control in the IrDA (Infrared Data Association) Control communication system where two peripherals are registered for one host. A synchronous communication system is set forth in the following. Control of each peripheral is administered at a constant time interval (referred to as “cycle” hereinafter). The host issues a control packet for a relevant peripheral at every cycle. The peripheral receives the control packet issued from the host. In the case where there is transmission data or the like to the host, a response packet is transmitted following the control packet reception. Thus, data is transferred.
In cycle TC
1
starting at time T
1
in
FIG. 5B
, the host first transmits to one peripheral (peripheral
1
) a control packet H
111
(the packet from the host to peripheral
1
at time T
1
). If peripheral
1
has data to be transferred to the host at the current stage, peripheral
1
transmits the transmission data through a packet P
1
in response to control packet H
111
from the host. Following transmission of the control packet to peripheral
1
, the host transmits a control packet H
121
to the other peripheral (peripheral
2
) within the same cycle TC
1
. Peripheral
2
determines the presence of transfer data, and sends it, if any, through a packet P
121
in response to control packet H
121
.
After the elapse of cycle TC
1
, a new cycle TC
2
starts at time T
2
. The host carries out a control process similar to that of cycle TC
1
during cycle TC
2
with respect to the two registered peripherals.
In cycle TC
2
, the host provides control with respect to peripheral
1
(control and response through packets H
112
and P
112
), and then sends control packet H
122
during control of peripheral
2
. If peripheral
2
has no data prepared to be transmitted to the host, a response does not have to be issued with respect to packet H
122
.
FIG. 6
is a flow chart of the dithering algorithm which is the frame to shift the communication execution timing defined in the IrDA control specification.
When there is no response of a packet from a peripheral (referred to as “no-packet response” hereinafter) during the normal cycle process of
FIG. 5B
, or when an error is encountered during communication, the host increments a variable “error_count”. At the same time, a variable “lastcycle_error_count” is also incremented. The value of variable “lastcycle_error_count” is used as the counter to detect no-packet response and also communication error during the immediately-proceeding single cycle. The value of variable “error_count” is employed as a counter to count the no-packet response and communication error during a plurality of cycles starting from the previous determination process to proceed to the dithering process up to the determination process to proceed to the next dithering process. The processes for these variables are executed at an arbitrary cycle to be used as the basis of determining whether dithering determination is to be carried out or not.
Following the communication cycle processes that are sequentially executed, control proceeds to step S
61
where determination is made to move to the determination phase of executing a dithering process or not. Since the dithering process is executed at an elapse of a con
Kizou Hassan
Levitan Dmitry
Sharp Kabushiki Kaisha
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