HK1007246B - Handshaking system for a time division duplex channel - Google Patents

Description

The present invention relates to a transmission system comprising at least two remote and near subscriber devices connected to at least one base station designed to handle at least the relationships between devices exchanging alternating information by means of a time-type multiplex in which control intervals are provided.

Such a system has important applications, particularly when radio-connections are made.

The invention also concerns a subscriber device suitable for such a system.

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When systems of the kind mentioned in the preamble are used as private systems (as opposed to public systems), radio resources (frequency channels with reduced bandwidth) are distributed sparingly.

The problem arises when two or more subscribers simultaneously request to speak, and the communication is at risk of being lost.

To address this problem, a system such as that mentioned in the preamble is remarkable in that for communication between a remote subscriber device and a nearby subscriber device, at least one control interval is assigned to the transmission of a speech request made by one of the subscribers, and that this speech request received by the other subscriber is used to prevent it from transmitting.

The following description, made in relation to the drawings annexed, is given as a non-limiting example to give a clear understanding of how the invention can be realized.

Figure 1 shows a diagram of the transmission system.

Figure 2 shows the distribution of control intervals within a time multiplex.

Figure 3 shows the diagram of a subscriber connection station.

Figure 4 shows the protocol of the alternate control.

The system is a set of STB, STM1 and STM2 broadcast-receiving stations. It is clear that the number of stations can be any number. STB is a basic broadcast-receiving station, STM1 and STM2 are satellite stations, i.e. managed by the base station. In practice the base station is a fixed station while the STM1 and STM2 stations are portable or embedded in mobile stations.

In general, the FBM channel is used by communications from the STB base to the STM1 and STM2 mobiles and the FMB channel by communications from the mobile stations to the base.

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Figure 3 shows the diagram of the mobile stations STM1 and STM2 with the same structure.

Each station consists of a transmitter-receiver set 10 controlled by a pair of reference oscillators 12 oscillating at FMB and FBM frequencies respectively. This set adapts to a TDMA frame by means of a frame manager 17. A duplex switch 22 controlled by the manager 17 allows, on the same antenna 24, both to transmit on an FMB frequency and to receive on an FBM frequency, different or not from FMB. To this switch 22 are connected a transmitter amplifier 25 and a receiver amplifier 26.

The set 10 consists of a transmission part 40 cooperating with a filter 41, centred on an intermediate frequency FI, and a modulator 42. The modulator 42 centers on the FMB carrier frequency the information provided by part 40. Part 40 arranges the information to be transmitted according to the commands established by the manager 17, the phase, frequency or amplitude information on an intermediate frequency FI. This manager 17 also allows the retrieval of the various information contained in the TDMA frame received by a receiving set 44. The input of this set is connected to the output of a filter 46,The voice information, which has been digitally encoded in advance, is transmitted in one of the time intervals of the frame transmitted by the FMB carrier, this time interval being affected by the manager 17. Similarly, the voice information from the remote subscriber, transmitted in one of the time intervals of the frame transmitted by the FBM, is returned to the receiver,But Manager 17 makes sure that all XCCHs can be received.

According to the invention, such a system has means to transmit a speech request information to a remote subscriber in an XCCH interval, means to detect this speech request to the remote subscriber, and means to deny access to the remote subscriber's program.

The means of requesting a statement may be made by a 70 alternator pedal connected to part 40 in a time interval XCCH allocated to the near-distant subscriber link.

The means of detecting this voice request for the remote subscriber is by receiving the XCCH interval allocated to the communication by means of a voice request receiver 72 acting on the manager 17.

The means of prohibiting access to the programme may be a light indicating to the remote subscriber that he cannot speak because the manager 17 prevents this command or by automatically switching on the remote subscriber.

Figure 4 shows the procedure for allowing the alternating communications to be carried out satisfactorily.

Initially, it is assumed that an XCCH is assigned by the STB station for the connection of subscriber A1 to subscriber B1. At time t1 subscriber A1, by pressing pedal 70, informs the STB station of its request to broadcast for subscriber B1 in the interval XCCH.At time t2, the STB station, after verifying that this is possible while avoiding simultaneity conflicts, authorizes subscriber A1 to broadcast.STM1 is set to position T (broadcast -in relation to speech).At time t3 (which can be confused with moment t2) STB sends this request back to station STM2.At time t4 the STM2 station has received this signal, which puts it in the receiving position R.At time t5, the A1 station has transmitted its alternate pedal, this is confused with time t2.B, the receiving signal from the STM station can be relayed to the station STB (time t2.B).

This procedure can be further simplified as needed, for example by removing the times t2, t5, t6, t7, and simply giving priority to the last issuer (t1, t3, t4).

Claims (3)

1. A transmission system comprising at least a remote and a near subscriber device connected to at least one base station provided for managing at least the connections between the devices exchanging information signals in the simplex mode by means of time multiplex signals in which control time intervals are provided, which system is characterized in that for a communication between a remote subscriber device and a near subscriber device, at least one control time interval is allocated to the transmission of a request to transmit or speak made by one of the subscribers, and in that this request to speak received by the other subscriber is used for preventing him from transmitting.
2. A transmission system as claimed in Claim 1, in which a base station is provided by which the information signals between the remote and near subscriber devices are transmitted, characterized, in that at least one control time interval is allocated to said communication for the connection between one of the subscribers and the base station and a control time interval is allocated for the connection between the other subscriber and the base station.
3. A subscriber device for a transmission system comprising at least a remote and a near subscriber device connected to at least one base station provided for managing at least the connections which occur between stations that have to transmit information signals in the simplex mode by means of time multiplex signals in which control time intervals are provided, which device is characterized in that it comprises means for transmitting in at least one of said control time intervals a request to transmit or speak signal when a request for communication is required, means for receiving control intervals coupled to detecting means for detecting the presence of a request-to-speak signal in an ensemble of at least one control interval and means for initiating the transmission when the detecting means have detected the presence of a request to transmit or speak.