Multiplex communications – Communication over free space – Signaling for performing battery saving
Reexamination Certificate
1997-08-28
2001-07-10
Nguyen, Chau (Department: 2663)
Multiplex communications
Communication over free space
Signaling for performing battery saving
C370S509000, C455S039000
Reexamination Certificate
active
06259681
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method and an apparatus for reducing the power consumption of a battery operated transceiver in standby mode, particularly a mobile telephone station, wherein successive word blocks are received by the receiver of the transceiver on a forward control channel, each word block consisting of a predetermined number of bits forming a dotting sequence, a word synchronization sequence and a predetermined number of word repeats.
BACKGROUND
A mobile telephone station in standby mode must monitor the appropriate control channel of the system in which it is located in a manner such that the mobile telephone station receives all system control messages addressed to it. This necessarily requires that the mobile telephone station monitors the control channel during any time periods within which control messages directed to that mobile telephone station could possibly be transmitted.
In systems such as the EIA/TIA-553 system (AMPS), the Total Acccess Communications System (TACS), and the D-AMPS IS-136 system, a mobile telephone station in standby mode, receives successive word blocks on a forward control channel (FOCC). Each word block consists of a 10-bit dotting sequence, an 11-bit word synchronization sequence, and ten word repeats each containing 40 bits. The word repeats are separated into two time-multiplexed data streams, the A stream and the B stream, each consisting of five word repeats. Depending on the last digit of the subscriber number, a mobile telephone station in standby mode listens to either the A stream or the B stream.
In the above systems, when the mobile telephone station monitors the forward control channel, the receiver is constantly on in that all five repeats of a word within a word block, are received, whereupon a majority decision is made, and BCH (Bose-Chaudhuri-Hocquenqhem) decode operations and parity check operations are performed. Thus, battery power is consumed in a mobile telephone station also in the standby mode. Moreover, this power consumption of the receiver of the mobile telephone station, when the mobile telephone station is monitoring the forward control channel, is a significant percentage of the total power consumption of the mobile telephone station.
SUMMARY
The object of the invention is to bring about a method and an apparatus for reducing the power consumption of a mobile telephone station in standby mode.
This is attained by the method according to the invention in that the receiver is switched off after a word repeat in a word block has been validly received, and the receiver is switched on to receive a word repeat in the next successive word block.
According to the invented method, the receiver is switched on in that time pulses are generated, said time pulses corresponding to bits that should have been received, had the receiver not been switched off, that said time pulses are counted, and that the receiver is switched on when the number of time pulses counted corresponds to the number of bits between the end of a word repeat in one word block and the beginning of a word repeat in the next word block.
According to the invented method, said time pulses are generated by a clock generator in a free-running mode, said clock generator being brought into said free-running mode from a tracking mode, in which the clock generator tracks the bits received, when the receiver is switched off.
According to the invented method the receiver is switched off after a word repeat in a word block has been validly received, and the receiver is switched on again to receive the same word repeat in the next word block.
According to the invented method, the receiver is switched off after the first word repeat in a word block has been validly received, and the receiver is switched on again to receive the first word repeat in the next word block.
According to the invented method, valid reception of a word repeat is determined by performing a parity check of its parity field.
The above object is also attained by the apparatus according to the invention in that a switching means is adapted to switch off the receiver after a word repeat in a word block has been validly received, and to switch on the receiver to receive a word repeat in the next successive word block.
According to the invented apparatus, said switching means is adapted to switch on said receiver upon receipt of a control signal from a counting means, said counting means being adapted to count time pulses corresponding to bits that should have been received,-had the receiver not been switched off, and to generate the control signal when the number of time pulses counted corresponds to the number of bits between the end of a word repeat in one word block and the beginning of a word repeat in the next word block.
According to the invented apparatus, a clock generator is adapted, in a free running mode, to generate said time pulses corresponding to bits that should have been received, had the receiver not been switched off, and, in a tracking mode, to track the bits received by the receiver, said clock generator being brought into said free running mode from said tracking mode by said switching means when the receiver is switched off.
According to the invented apparatus, said switching means is adapted to switch off the receiver after a word repeat in a word block has been validly received, and to switch on the receiver to receive the same word repeat in the next word block.
According to the invented apparatus, said switching means is adapted to switch off the receiver after the first word repeat in a word block has been validly received, and to switch on the receiver to receive the first word repeat in the next word block.
According to the invented apparatus, said switching means is adapted to determine valid reception of a word repeat in a word block by performing a parity check of the parity field of the word repeat.
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Kolev Iavor
Thimansson Jan Rolf Erling
Burns Doane Swecker & Mathis L.L.P.
Hyun Soon-Dong
Nguyen Chau
Telefonaktiebolaget LM Ericsson
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