Apparatus and method for adapting a digital radiotelephone system to increased subscriber traffic

• US 5,649,299 A
• Filed: 10/27/1993
• Issued: 07/15/1997
• Est. Priority Date: 10/27/1993
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Battin, John W., Laird, Kevin M., Lynk, Charles N. Jr.
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/144,166
• Time in Patent Office: 1,357 Days
• Field of Search: 455/33.1, 455/34.1, 455/34.2, 455/38.3, 455/54.1, 455/72, 455/63, 455/89, 379/59, 375/8, 370/84, 370/94.1, 370/347, 370/349, 370/311
• US Class Current: 455/62
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: H04J 3/1688 the demands of the users being taken into account after redundancy removal, e.g. by predictive coding, by variable sampling reducing bandwidth of signals in general H04B1/66; in PCM-systems H04B14/046; removal of redundancy in telegraph communication H03M7/30
• CPC Class Codes: H04W 88/181 Transcoding devices; Rate adaptation devices

Abstract

A digital radiotelephone system employs vocoders to convert between analog speech and a digital format suitable for transmission via radio. Under most circumstances, the highest data rate is selected for optimum audio quality. When the system occupancy exceeds a particular threshold, as detected at the fixed site of the system, some or all of the vocoders are instructed to switch to a lower data rate to provide for an increase in the number of communication channels. Further, a portable subscriber unit may autonomously change its vocoder data rate depending upon the charge state of its battery.

Claims

1. A subscriber unit for a digital radiotelephone system having a fixed station with at least one radio transceiver and a first vocoder to convert a first analog signal to a digital signal at a first predetermined data rate to provide service to a plurality of subscriber units within a radio coverage area of the fixed station, each of the plurality of subscriber units employing a second vocoder to convert a second analog signal to a digital signal at the first predetermined data rate, the subscriber unit comprising:

a battery state of charge detector, whereby a battery state characteristic of the subscriber unit is monitored and a signal generated when a predetermined threshold is crossed; and

a resource controller which receives said signal from said battery state of charge detector and which generates an instruction to at least one of the first and second vocoders to change from the first predetermined data rate to a second predetermined data rate.

2. A digital radiotelephone system including a fixed station having a radio transceiver and a first vocoder to convert a first analog signal to a digital signal at a first predetermined data rate, for transmitting to and receiving from a radio coverage area to provide service to a plurality of subscriber units within the radio coverage area, each subscriber unit employing a second vocoder to convert a second analog signal to a digital signal at the first predetermined data rate, comprising:

a first group of subscriber units predeterminedly assigned a priority level;

a system occupancy detector, coupled to the radio transceiver, which provides an output signal related to a number of the plurality of subscriber units actively receiving service from the digital radiotelephone system in the radio coverage area;

a subscriber priority list and list scanner which selects said first group of subscriber units; and

a threshold detector which monitors said output signal and generates an instruction to at least one of the first and second vocoders of a selected first priority subscriber unit to change from the first predetermined data rate to a second predetermined data rate.

3. A method of adaptation of a subscriber unit employed in a digital radiotelephone system having a fixed station with at least one radio transceiver and a first vocoder to convert a first analog signal to a digital signal at a first predetermined data rate, the fixed station providing service to a plurality of subscriber units within a radio coverage area of the fixed station, each of the plurality of subscriber units employing a second vocoder to convert a second analog signal to a digital signal at the first predetermined data rate, the method comprising the steps of:

detecting battery state of charge of the subscriber unit, whereby a battery state characteristic is monitored and a signal generated when a predetermined threshold is crossed; and

generating, in response to said signal, an instruction to at least one of the first and second vocoders to change from the first predetermined data rate to a second predetermined data rate.