Routing of voice communication at a cell site in a land mobile radio system

• US 5,557,606 A
• Filed: 06/10/1994
• Issued: 09/17/1996
• Est. Priority Date: 06/10/1994
• Status: Expired due to Term

• Current Assignee: Uniden America Corporation (Cornwall Capital Management LP)
• Original Assignee: Uniden America Corporation (Cornwall Capital Management LP)
• Inventors: Nguyen, Cap V., Moon, Billy G.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): BLUM, RUSSELL
• Application Number:
  US08/258,751
• Time in Patent Office: 830 Days
• Field of Search: 370/58.1, 370/58.2, 370/66, 370/95.3, 370/24, 370/31, 379/58-60, 455/33.1, 455/34.1, 455/34.2, 455/53.1, 455/54.1
• US Class Current: 370/296
• CPC Class Codes: H04W 4/10 Push-to-Talk [PTT] or Push-On-Call services
• CPC Class Codes: H04W 76/45 for Push-to-Talk [PTT] or Push-to-Talk over cellular [PoC] services
• CPC Class Codes: H04W 84/08 Trunked mobile radio systems

Abstract

A land mobile radio communication system has a plurality of cell sites, each of which typically has a plurality of repeaters. The over-the-air radio communications between the cell site repeaters and the mobile radios in the system include both a voice component and a data component. The data component is carried as low-frequency subaudible information. Communication channels are provided between the radio users at each site as well as between users at different sites and between mobile radio users and the public telephone network. Within a cell site, the transmitted and received communications are digitized and passed through serial buses in a time multiplex fashion. The digitized voice is transferred between time slots to provide the required switching function. The system includes operational software to provide direct inward dial telephone number recognition, automatic voice prompts for a user entering a new cell, call priority override, fraud control for radio fleets and a dynamic control channel.

Claims

1. A method for routing voice communications at a cell site in a land mobile radio communication system wherein the cell site has a plurality of repeaters each having a transmitter and a receiver, the method comprising the steps of:

producing a receive signal from each of a plurality of said receivers,

digitizing at least a voice component of each said receive signal to produce a plurality of serial digital receive signals corresponding respectively to said receivers,

combining said serial digital receive signals to produce a multiplex serial receive signal which has a plurality of time slots assigned respectively to said receivers,

switching the data between said time slots of said serial digital receive signal to produce a multiplex serial transmit signal which has a plurality of time slots which are assigned respectively to said receivers,

extracting the data from time slots of said multiplex serial transmit signal to produce a plurality of respective serial digital transmit signals corresponding respectively to said transmitters,

converting each of said serial digital transmit signals into a corresponding analog transmit signal, and

providing said analog transmit signals to the corresponding respective ones of said transmitters.

2. A method for routing voice communications at a cell site in a land mobile radio communication system in which radio transmissions have a voice component and a data component and wherein the cell site has a plurality of repeaters each having a transmitter and a receiver, comprising the steps of:

producing a receive signal from each of a plurality of said receivers,

extracting said data component from each of said receive signals,

digitizing at least said voice component of each said receive signal to produce a plurality of respective digitized receive signals,

combining a receive data unit related to each extracted data component with the corresponding one of said digitized receive signals to produce a plurality of serial digital receive signals corresponding respectively to said receivers,

extracting said receive data unit from each of said serial digital receive signals and providing said data units to a central processor unit,

combining said serial digital receive signals to produce a multiplex serial receive signal which has a plurality of time slots assigned respectively to said repeaters,

switching the voice component data in said time slots of said multiplex serial digital receive signal to produce a multiplex serial transmit signal which has a plurality of time slots which are assigned respectively to said repeaters,

extracting the voice component data from time slots of said multiplex serial transmit signal to produce a plurality of respective serial digital transmit signals corresponding respectively to said transmitters,

converting each of said serial digital transmit signals into a corresponding analog transmit signal,

combining each of said analog transmit signals with a transmit data unit provided by said central processing unit to produce a plurality of combined analog transmit signals, and

providing said combined analog transmit signals to the transmitters of the corresponding respective ones of said repeaters.

3. Cell site apparatus for a land mobile radio system which has a plurality of repeaters, each having a transmitter and receiver, connected to an antenna and the cell site serves a plurality of mobile radio users, comprising:

an analog to digital converter connected to the output of each of said repeater receivers to produce a serial digital receive signal for each of said repeaters,

a matrix switch connected to receive said serial digital receive signals and supply the digital data in said serial digital receive signals as a multiplex serial receive signal which has a plurality of time slots which correspond respectively to said repeaters,

a switch connected to receive said multiplex serial receive signal and interchange the data in the slots to produce a multiplex serial transmit signal which has a plurality of time slots which correspond to said repeaters,

a matrix switch connected to receive said multiplex serial transmit signal and distribute the data in the time slots thereof into a plurality of serial digital transmit signals which correspond respectively to said repeaters, and

a digital to analog converter for each of said transmitters, the input of each digital to analog converter connected to receive the corresponding serial digital transmit signal and the output thereof connected to the corresponding one of said transmitters.

4. Cell site apparatus for a land mobile radio system as recited in claim 3 including a respective data recovery circuit connected to the output of each repeater receiver and having the output thereof coupled to a half duplex link controller.