CHANNEL-ALLOCATION SYSTEM FOR A CHANNEL-ADDRESSING MULTIPLE-ACCESS TELECOMMUNICATION SYSTEM

• US 3,634,627 A
• Filed: 07/21/1970
• Issued: 01/11/1972
• Est. Priority Date: 07/23/1969
• Status: Expired due to Term

• Current Assignee: Italtel SPA (Italtel Group SPA)
• Original Assignee: Nicola Velentini
• Inventors: Velentini, Nicola
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Stewart, David L.
• Application Number:
  US05/056,765
• Time in Patent Office: 539 Days
• Field of Search: 179/15BM,15BA,41A 325/4
• US Class Current: 370/442
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 84/047 using dedicated repeater stations
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems
• CPC Class Codes: H04W 84/14 WLL [Wireless Local Loop]; RLL [Radio Local Loop]

Abstract

In a channel-addressing multiple-access telecommunication system, a channel-allocation system is disclosed in which all stations scan the available channels. An available channel is seized by transmitting on that channel one of two channelsupervisory indications and the address of the called station. Receipt of said one channel-supervisory indication causes all stations to arrest scanning on the seized channel. The called station, upon reception and recognition of its own address transmits the other of said two channel-supervisory indications and its own address as an acknowledgement. Upon receipt of the acknowledgement, the calling station switches from transmission of said one to transmission of the other of said two channelsupervisory indications. A repeater embodiment is also disclosed.

Claims

1. In a system for the selective establishment of two-way communication between a multiplicity of staTions over a lesser number of communication channels each adapted to carry supervisory signals along with message and address information between any two communicating stations, the improvement wherein each station comprises:

receiving means for retrieving address information, individual to the respective station, and supervisory signals from any channel connected thereto;

scanning means for repetitively connecting said receiving means to each channel in succession for examining the busy/idle status of same;

transmitting means synchronized with said receiving means for periodically gaining access to the channels concurrently examined by the latter;

signal-generating means connected to said transmitting means for feeding either of two types of outgoing busy signals to a channel accessible thereto, said types of busy signals including a request signal and an engagement signal;

monitoring means connected to said receiving means for ascertaining the availability of a channel under examination from the absence of corresponding types of incoming busy signals thereon, said monitoring means further being responsive to a locally generated readiness signal for arresting said scanning means and for actuating said signal-generating means to emit an outgoing request signal calling for a response from a remote station, thereby seizing such available channel;

switch means controlled by said monitoring means upon detection of an incoming request signal originating from a remote station on a channel under examination for arresting said scanning means on said channel under examination and operating said signal-generating means to emit an outgoing engagement signal over the seized channel; and

disconnect means controlled by said monitoring means for restarting said scanning means to release a seized channel upon nonreception of an incoming engagement signal from a remote station.

2. The improvement defined in claim 1 wherein each station identified by an individual address comprises register means connectable to said transmitting means, under the control of said monitoring means upon detection of said incoming request signal, for accompanying the emission of said outgoing engagement signal with a readout of the address of the local station over the seized channel.

3. The improvement defined in claim 2 wherein each station comprises selector means for entering, upon the inception of an outgoing call, the address of a called station in said register means for readout together with said outgoing request signal over a channel seized in response to said readiness signal, said register means being operative to emit a recognition signal upon detecting the address of the local station together with said incoming request signal, each station further comprising storage means connected to said receiving means for temporarily registering the address of a remote station responding over the seized channel and comparison means for generating an identity signal upon ascertainment of a match between the addresses in said register means and said storage means, said monitoring means being responsive to the absence of said recognition signal for releasing a channel seized upon detection of said incoming request signal and being further responsive to the presence of said identity signal for modifying the operation of said signal-generating means to emit said outgoing engagement signal in lieu of said outgoing request signal while terminating the transmission of the address readout from said register means.

4. The improvement defined in claim 3 wherein each station comprises timing means synchronized with said scanning means and controlled by said monitoring means for measuring a period sufficient to receive address information accompanying said incoming request signal on a channel seized by a remote station, said monitoring means maintaining said disconnect means inoperative during periods sufficient to establish two-way communication between a local station and a remote statioN.

5. The improvement defined in claim 4 wherein said timing means includes a source of periodic clock pulses for stepping said scanning means at a predetermined rate, circuit means forming a pair of parallel paths for said clock pulses between said source and said scanning means, gate means in one of said paths blockable by said monitoring means in the presence of an incoming engagement signal, and counting means in the other of said paths for delaying the passage of a clock pulse for a predetermined number of clock pulse cycles.

6. The improvement defined in claim 4 wherein said timing means comprises monostable means triggerable by said locally generated command upon seizure of a channel for measuring an interval greater than that required for operation of said selector means and transmission of the selected address with inhibition of said disconnect means during said interval.

7. The improvement defined in claim 4 wherein said channels are radiolinks, said timing means comprising monostable means triggerable by the complement of an incoming engagement signal for measuring an interval greater than the normal fading time of a radio signal with inhibition of said disconnect means during said interval.

8. The improvement defined in claim 4 wherein each station is provided with call means responsive to said recognition signal for attracting the attention of an operator, said timing means comprising monostable means triggerable by said recognition signal for measuring an interval sufficient for generation of said readiness signal by the operator and for actuating said disconnect means in the absence of said readiness signal at the end of said interval.

9. The improvement defined in claim 4 wherein said register means has an output generating a counting pulse upon every readout of an address stored therein, said timing means including counter means for said counting pulses operative to enable said disconnect means upon generation of a predetermined number of said counting pulses.

10. The improvement defined in claim 9 wherein said timing means further includes logical circuitry connected to an output of said counting means for enabling said disconnect means after said predetermined number of counting pulses in the presence of said readiness signal and in the absence of said identity signal.

11. The improvement defined in claim 10 wherein said switch means comprises first bistable means settable by said readiness signal alternately in the absence of an incoming busy signal and in the presence of said recognition signal for generating a seizure signal maintaining said scanning means inoperative, said first bistable means being alternately resettable by the complement of said readiness signal and by the concurrent absence of incoming and outgoing busy signals;

said signal-generating means comprising second bistable means settable by said seizure signal for producing an outgoing request signal and a readout signal for said register means, third bistable means settable concurrently with said first bistable means by the joint presence of said readiness and recognition signals and also settable independently of said first bistable means by the joint presence of said identity signal and an incoming engagement signal for resetting said second bistable means and producing an outgoing engagement signal, and fourth bistable means settable by said recognition signal for producing said readout signal and said outgoing request signal, said second bistable means being also resettable by said logical circuitry under the control of said counting means and by the complement of said seizure signal, said third bistable means being resettable by the complement of said seizure signal, said fourth bistable means being resettable by an alternate output of said counting means after a number of counting pulses substantially less than said predetermined number.

12. The improvement defined in claim 3 wherein said stations include a multiplicity of terminal stations and a pair of repEater stages interconnected by a coupling network, the receiving means of each repeater stage being operative to emit said recognition signal upon detecting the address of any terminal station accessible via a channel monitored by the other repeater stage.

13. The improvement defined in claim 12 wherein one of said repeater stages is provided with gating means connected to receive, via said coupling network, a call signal derived from a recognition signal generated at the other repeater stage, said gating means rendering ineffectual a recognition signal generated at said one of said repeater stages, thereby giving precedence to said other repeater stage upon substantially concurrent detection of incoming request signals by both repeater stages.

14. The improvement defined in claim 12 wherein said coupling network comprises cross connections between said register means and said storage means of said repeater stages for transferring an incoming address from the storage means of one repeater stage to the register means of the other repeater stage.

15. The improvement defined in claim 14 wherein each repeater stage is provided with circuit means controlled by said monitoring means, upon exploration of an idle channel, for operating said switch means to seize such channel and for reading out an address transferred from the other repeater stage together with an outgoing request signal in response to a readiness signal generated at said coupling network by a call signal derived from a recognition signal at said other repeater stage.

16. The improvement defined in claim 12 wherein said channels are divided into first and second branches, said first branches being accessible to the transmitting means of said terminal stations and to the receiving means of said repeater stages, said second branches being accessible to the receiving means of said terminal stations and to the transmitting means of said repeater stages.

17. The improvement defined in claim 12 wherein said channels are grouped in a first set, accessible to some of said terminal stations and one of said repeater stages, and a second set, accessible to the remaining terminal stations and the other of said repeater stages.