Ring signal generator

Details Ring signal generator Ring signal generator

1997-01-27

2001-06-05

Ton, Dang (Department: 2732)

Multiplex communications

Communication techniques for information carried in plural...

Combining or distributing information via time channels

C375S364000

Reexamination Certificate

active

06243399

ABSTRACT:

This invention relates to a communication system station power consumption control method and apparatus in which control is exercised to different degrees in the different states of operation of the station.
BACKGROUND OF THE INVENTION
There has long been a strong interest in containing electric power consumption in electronic circuits which may depend upon limited power sources such as batteries or solar panels. Interest has been particularly acute for radiotelephone system stations that are either portable or located in a geographical area not adequately served by electric power distribution facilities. Such a station is herein usually called a subscriber station unit, or simply a subscriber unit. This interest has become even more sharply focused as concerns have grown about the need to contain pollution of various kinds.
In the radiotelephone field several types of efforts have been made to limit power consumption. Voice operated transmitters (VOX) are well-known wherein the presence or absence of an actual voice signal turns a transmitter power supply ON or OFF, and one example is the D. R. Bolgiano et al. U.S. Pat. No. 4,130,731. Otherwise a subscriber unit including such a transmitter is fully powered during all states of operation. A number of power conservation efforts have resorted to periodically enabling at least the receiving circuits of a subscriber unit while the unit is in a standby mode awaiting the availability of a channel or awaiting initiation of a call, and some examples are the U.S. Pat. No. 4,272,650 to D. R. Bolgiano et al., and U.S. Pat. No. 5,203,020 to H. Sato et al. Subscriber unit circuits in these latter systems are otherwise fully powered during actual call signal processing.
The term “call signal processing” refers to operations such as, e.g., amplification, filtering, encoding/decoding, interpolating, or modulating with respect to signals of any type for communication between stations.
In the Sato et al. patent, when a subscriber unit in a mobile telecommunication system is in a location where it is unable to be served on any channels of the system, it is powered up periodically to check for the availability of an appropriate channel; and otherwise all components except a timer are powered down. When an available channel has been found, and while awaiting the start of a call, the central processing unit (CPU) and a timer are continuously powered up while the remainder of the unit is periodically powered up to check for the start of a call. Finally, during a call connection, the entire subscriber unit is continuously powered up.
In another group of systems, subscriber units are powered up or down as a group and special arrangements are provided to power up a subscriber unit if necessary when others are powered down. Some examples include U.S. Pat. No. 4,964,121 to M. A. Moore, U.S. Pat. No. 4,509,199 to M. Ichihara, and U.S. Pat. No. 4,577,315 to S. Otsuka. Similarly, in U.S. Pat. No. 4,713,809 to Y. Mizota, a relay station for a time division multiple access (TDMA) system is powered up in only those TDMA time slots in which a subscriber unit served by it is active.
Subscriber units for radiotelephone systems, such as the subscriber unit of the U.S. Pat. No. 5,008,900 to D. N. Critchlow et al., have included means for powering down a certain relatively high power consumption component at a selected time determined by the subscriber unit function being performed at such time. For example, in that Critchlow et al. patent a processor chip, included in the unit for controlling the various unit components as well as performing certain signal processing functions, is temporarily powered down when there is no phone call in progress. The powering down occurs in response to execution of an idle instruction in the unit's program of operation. Normal operation is temporarily resumed in response to an interrupt signal, and if there is no service routine to be performed the processor returns to the powered down state. Otherwise the subscriber unit components appear to be fully powered.
In the U.S. Pat. No. 4,675,863 to E. Paneth et al. a modem is operated in a half-duplex mode in a subscriber unit that functions in a TDMA environment. In that mode, the receiving demodulation section and the transmitting modulation section of the modem operate at different times; so the radio frequency (RF) section power amplifier is active for no more than half of the time. Other subscriber unit components appear to operate continuously.
Subscriber units in relatively difficult to reach locations often are equipped with a backup power supply using batteries supported by solar panels or an alternating current charger. In spite of efforts of the type described above, some subscriber units in wireless TDMA communication systems, which have the capability of being operated by backup battery power with appropriate charging facility, have had to use multiple backup batteries to supply the needed power. In some such units a pair of 15 ampere-hour 12-volt batteries and a charging source of four to six solar panels have been employed.
SUMMARY OF THE INVENTION
In accordance with the present invention, certain circuit components of a TDMA radiotelephone system subscriber unit are recurrently powered down during a call connection. The portions powered down during different time slots of each recurring TDMA time frame are not required for signal processing operation in the respective time slots of the frame. In other words, there is a changing tessellation of subscriber unit active circuit portions that are powered up and powered down from time slot to time slot to limit dynamically the power consumption of the unit.
According to one aspect of the invention, the need for special circuits to distribute power consumption control signals is reduced by employing existing control or call signal paths, where appropriate, to distribute power consumption control commands. Several control implementation techniques are employed for reducing the need for specialized power consumption control circuitry. Those techniques include, illustratively, controllably switching the power supply current path to a circuit component, or remotely controlling the frequency of a clock source output to certain clocked circuit components which are implemented in a semiconductor technology in which power consumption is affected by clocking rate, or reducing input signal to a circuit which consumes less power when responding to little or no input signal, or reducing bias current supplied to an amplifier, or distributing command signals to commercially available circuit components which are normally provided with a power down input connection.
In one embodiment, the subscriber unit circuitry includes a line interface unit to couple the subscriber unit signal processing circuit components to a subscriber communication instrument such as a telephone station set. The subscriber unit also includes, on a single circuit board along with the line interface unit and other subscriber unit circuit components, an expansion slot; or header connector, to provide line interfacing functions for additional services of the same or different types to share utilization of the subscriber unit circuits.
A subscriber unit in accordance with the invention operates in a TDMA system which includes a network station that provides a radio control channel (RCC) for communicating with activated subscriber units that are not engaged in a call connection. The subscriber unit utilizes the TDMA system time slots and frame clocking arrangements for periodically powering up primarily only those circuit components needed to sample the RCC to determine whether or not there is call traffic for the unit. In one embodiment, no more than one time slot per TDMA frame is utilized for that purpose on the RCC channel. In some applications, it is possible further to utilize only one time slot in every second, or less frequently occurring, frame.
Additional power is conserved by limiting the subscriber loop circuit between the serving subscriber unit and any s

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