JPH04373320A - Multi-party communication system - Google Patents

Abstract

PURPOSE:To enable multi-party communication among plural slave stations including a master station by composing a radio line between the master station and the slave station of a TDMA system, allocating various time slots between the master station and the respective slave stations, and switching those time slots at the master station. CONSTITUTION:In the case of starting interrupted tripartite communication at a slave station 2, a master station A holds temporarily a first communication path D. The idle time slot is selected and set for a second communication path E between the master station and the slave station 2, the holding of a first communication path is canceled between the master station and the slave station 1, first and second communication paths are connected at the master station, and the tripartite communication is started among the master station, slave station 1 and 2. At this time, when the master station and the slave station 1 select a certain time slot, the master station and the slave station 2 select the next time slot. Further, the next time slot is similarly selected for the master station and the slave stations following to a slave station 3 and used so as not to be overlapped each other and by periodically repeating this operation, the plural communication paths can be set without any interference among the master station and the respective slave stations 1-3, etc.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides for one master station to
The present invention relates to a multi-party communication system in which communication between three or more stations is performed among a plurality of slave stations including a master station via a wireless line.

0002

2. Description of the Related Art FIG. 4 is an explanatory diagram of the field to which the present invention belongs, and FIGS. 2 and 3 are explanatory diagrams of examples of the prior art. FIG. 4 is an explanatory diagram of the configuration of a so-called cordless telephone, in which pairs of a master station 1 and a slave station 1, and a master station 2 and a slave station 2 are connected to each other via wireless lines. As is well known, conventional cordless telephones use frequency-divided radio waves in the wireless section, and as shown in FIG. The communication path between the two is to avoid interference with each other.
The former used radio waves with frequencies f1 and f2, and the latter used radio waves with frequencies f3 and f4, so radio waves with different frequencies were used. (Here, f1 and f2 or f3 and f4 mean the difference in frequency between the downlink (from the master station to the slave station) and the upstream (from the slave station to the master station) of the communication path, and f1 and f3 or f2 and f4 are the communication path (means the difference in frequency between)

0003

[Problems to be Solved by the Invention] By the way, as an application of the above-mentioned conventional system, a parent-child type cordless telephone has been realized, but it has the following problems. That is, in FIG. 2, a plurality of slave stations 1, 2, 3, ... are connected to a master station via wireless lines, and the master station and slave stations 1
, 2, 3... perform multiparty communication, but the master station and slave stations 1, 2...
,..., to communicate simultaneously, as shown in Figure 2, a first communication path is set up between the master station and slave station 1, and a second communication path is established between the master station and slave station 2. It is necessary to set up a communication path. (The same applies to slave stations 3 and onward, and descriptions of slave stations 3 and onwards will be omitted below.) However, as mentioned above,
Since radio waves in the wireless section are frequency-divided and used, when trying to realize a so-called parent-child type cordless telephone, as shown in FIG. It is necessary to install a transceiver 2 that transmits and receives frequencies f3 and f4, and in order to avoid interference between the first communication path and the second communication path, f1 and f
It was essential to change the operating frequencies of the transceivers 1 and 2, such as 2, f3 and f4. In addition, when adding more handsets to perform multi-party communication with three or more parties, the master station required a transmitter/receiver for each additional handset, and many radio frequencies were used simultaneously to avoid interference. . Therefore, a large number of transceivers are required in the master station, resulting in high cost, and there are also problems in size, power consumption, and power supply. Furthermore, since many communication channels among the limited communication channels are simultaneously occupied and used for this multiparty communication, there is also a problem in terms of effective frequency utilization.

Furthermore, instead of frequency-dividing the radio waves in the wireless section as shown in FIG. In order to avoid mutual interference between the communication path between 1 and the communication path between master station 2 and slave station 2, a technique was considered to communicate at timings that do not overlap with each other, but multi-party communication between three or more parties When attempting to do so, new control is required to enable simultaneous calls without mutual interference between the master station and multiple slave stations that make up the multiparty communication. A private communication system has not been realized, and only a system in which a master station and a slave station face each other independently as shown in FIG. 3 has been considered.

[0005] The present invention is characterized in that it provides a novel means for enabling multiparty communication between a master station and a plurality of slave stations.

[0006]

[Means for Solving the Problems] According to the present invention, a wireless line is divided in the time domain and a communication path consisting of a plurality of time slots is set up, and a master station and each slave station are connected using different time slots. , the master station realizes multi-party communication between the master station and multiple slave stations by connecting the communication path with each slave station via the master station by switching the time slot addressed to each slave station. It is something.

[0007]

[Embodiment] FIG. 1 is an explanatory diagram showing the configuration of an embodiment of the present invention.
FIG. 5 is an explanatory diagram showing an overview of the control flow of the embodiment of the present invention. A plurality of slave stations are connected to one master station via wireless lines. Also, time-sharing communication paths are set between the master station and each slave station. Further, the line from the master station to the slave station (so-called downlink) and the line from the slave station to the master station (so-called uplink) use different frequencies.

As shown in FIG. 1, a wireless line is divided in the time domain to establish a communication path consisting of a plurality of time slots. Here, as shown in the control flow of FIG.
i+1] (hereinafter, ti, ti+1, ti+2 represent times at fixed time intervals in order). During communication by setting up the first communication path (■ in FIG. 5), the slave station 2 attempts to start interrupt three-way communication (Figure 5
■) Once, the master station puts the first communication channel on hold and searches for vacant states of other time slots (■ in FIG. 5). During this time, slave station 1 also holds the first communication path (■ in Figure 5).
). As a result of the search, the time slot [ti+1-
ti+2] is free, this time slot is selected and set for the second communication path between the master station and slave station 2 (■ in Figure 5), and the master station and slave station 1 At the same time as releasing the hold on the communication path (■ in Figure 5), the first communication path and the second communication path are connected by the master station, and three-way communication between the master station, slave station 1, and slave station 2 is established. Start (■ in Figure 5). At this time, as shown in Figure 1, when the master station and slave station 1 select a certain time slot, the master station and slave station 2 select the next time slot, and the master station and slave stations 3 and onwards do the same. By sequentially selecting the next time slot, using them so as not to overlap each other, and repeating this periodically, it is possible to set up a plurality of interference-free communication paths between the master station and each slave station. Specifically, the connection between the first communication path and the second communication path at the master station is slot switching. In other words, when the master station transmits the signal from slave station 1 to slave station 2, it uses the time slot of [ti - ti+1] as [ti
+1 − ti+2 ] timeslot,
When transmitting the signal from slave station 2 to slave station 1, it is reversed. Also, when transmitting a signal from the terminal of the master station to slave station 2 together with a signal from slave station 1, for example, [ti+1 - ti+
2], the signal from the terminal of the master station and the signal from the slave station 2 may be transmitted alternately. The above connection control operation is performed by the communication path processing section of the master station.

[0009] The above has been described for the case of one master station, but the same applies to the case of multiple master stations.

0010

According to the present invention, one transmitter/receiver of the master station is used in a time-sharing manner, so there is no need to install a plurality of transmitters/receivers for the number of slave units in the master station as in the conventional case. Furthermore, there is no need to change frequencies between multiple communication paths between the master station and each slave station as in the past, and since the same frequency is divided and used in the time domain, effective frequency utilization can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating the technology of a conventional cordless parent-child telephone.

FIG. 3 shows an example of a conventional cordless telephone using TDMA.

FIG. 4 is a diagram illustrating the field to which the present invention belongs.

FIG. 5 is a diagram illustrating the functional operation of a master station in the present invention.

Claims (1)

[Claims] Claim 1: Having one or more master stations, the first to nth (
A plurality of slave stations (up to n is an integer of 2 or more) are connected, communication paths from the first to the nth are set between the master station and each of the slave stations, and a set of communication paths is used to communicate with the master station. In a multiparty communication system that performs communication between three or more stations among multiple slave stations, the wireless line is divided in the time domain to form a communication path consisting of multiple time slots, and the master station A specific time slot is used for the first communication path between the master station and the slave station, another time slot is used for the second communication path, and the first to nth communications between the master station and the slave station are The plurality of time slots are selected and used between each communication channel so that they do not overlap each other, and the master station uses the first communication channel set between one slave station and another slave station. A multi-party communication method characterized in that communication is performed between a master station and a plurality of slave stations by switching between a second communication path and a second communication path set between the master station and a plurality of slave stations.