Radio communication apparatus with power consumption reduced

Details Radio communication apparatus with power consumption reduced Radio communication apparatus with power consumption reduced

1999-05-05

2003-10-14

Bost, Dwayne (Department: 2681)

Telecommunications

Receiver or analog modulated signal frequency converter

With particular receiver circuit

C455S574000, C340S007340

Reexamination Certificate

active

06633753

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radio communication apparatus. More particularly, the present invention relates to an intermittent reception control in a radio communication apparatus.
2. Description of the Related Art
In a radio communication apparatus, an intermittent reception is carried out while a power supply to a radio section requiring a large quantity of electric power is controlled to be turned on and off, in order to make a life of a battery longer.
FIGS. 3A
to
3
C show an example of a format of a transmission signal received by a radio communication apparatus such as a radio selective call receiver. As shown in
FIG. 3A
, 15 cycles from 0 to 14 correspond to one hour. The 15 cycles of this one hour unit are continuously sent out for 24 hours. As shown in
FIG. 3B
, each cycle is composed of 120 transmission frames from 0 to 119. As shown in
FIG. 3C
, one transmission frame is transmitted in, for example, two seconds. The transmission frame is a basic unit of the reception. The radio communication apparatus can receive all the transmission frames.
One transmission frame is composed of a preamble
1
field of 32 bits, a sync signal
1
field of 32 bits, a preamble
2
field of 16 bits, a sync signal
2
field of 32 bits, a frame information (FI) field of 32 bits and a data field.
A preamble (PR) signal in which “1” and “0” are alternately located for 32 bits is stored in the preamble
1
field and used to correct bit synchronization. A sync signal pattern
1
as a particular pattern of 32 bits is stored in the sync signal
1
field and is used to establish word synchronization. A preamble pattern of 16 bits is again stored in the next preamble
2
field. A sync signal pattern
2
is stored in the sync signal
2
field. A data of number of a transmission frame that is being currently transmitted and a cycle number of the transmission frame are stored in the frame information (FI) field. In succession, a message corresponding to at least one identifier (ID) is stored in the data field.
There is a case that all the frames are not transmitted even in a synchronously transmitting system using transmission frames as shown in FIGS.
3
A to
3
C. Also, there is a case that a part of the transmission frames is used for a transmission using another transmission protocol. In such a case, the transmission is sometimes stopped at a unit of several transmission frames because of the mixture with the other protocol, namely, a transmission stop is carried out.
FIG. 1
shows an example of a manner of the transmission stop in such a synchronization system. Referring to
FIG. 1
, a period of the transmission stop is not constant, and the number of transmission frames continuously transmitted after the transmission stop is not always constant. The transmission stop is again performed immediately after messages accumulated in the period of the transmission stop are fully transmitted after the start of the transmission. A signal having a different signal format is transmitted during the transmission stop.
In this synchronously transmitting system, the radio communication apparatus determines that the transmission frame is the transmission stop frame, depending upon the reception result. Thus the intermittent reception operation must be carried out on the assumption that there is the transmission of the synchronous transmission frames even during the transmission stop.
A radio communication apparatus for a transmission signal having the synchronous transmission signal format shown in
FIGS. 3A
to
3
C is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 8-149542). In this cited reference, the intermittent reception control is carried out in accordance with a process flow shown in FIG.
2
.
Referring to
FIG. 2
, in a non-synchronous state after a power supply is turned on (Step ST
801
), a receiving section is turned on (Step ST
802
). Then, an operation of detecting the sync signal
1
or
2
of the transmission frame is carried out (Step ST
803
). If any one of the sync signals
1
and
2
is detected, a transmission frame number of the transmission frame is acquired from the frame information (FI) field (Step ST
804
). The transmission frame synchronization with the transmission signal is established in response to the acquisition of the transmission frame number (Step ST
806
). After the synchronous establishment, electrical power is supplied to a receiving section at the timing when a transmission start of the transmission frame is predicted (Step ST
807
), such that the receiving section is set to an ON state (Step ST
808
). Then, the detection of the sync signal is carried out as mentioned above (Step ST
809
).
When the sync signal is detected, data is received from the subsequent data field (Step ST
810
). When the radio communication apparatus determines that the reception of the effective data within this transmission frame is ended, the supply of the electrical power to the receiving section is turned off without waiting for the end of the transmission frame (Step ST
811
).
If the sync signal is not detected, the supply of the electrical power to the receiving section is stopped at the timing when the transmission end of the sync signal is predicted, and the receiving section is turned off. Then, the radio communication apparatus waits for a next transmission frame (Step ST
812
).
In the state that the synchronization with the transmission frame is established, the processes from the step ST
807
to the step ST
812
are repeated for each transmission frame. Thus, the intermittent reception is carried out. The established state of the synchronization with the transmission frame is cancelled when the transmission frame is not received for a predetermined continuous number of times. As a result, the radio communication apparatus is returned back to the non-synchronous state.
In the method shown in
FIG. 2
of carrying out the intermittent reception in the established state of the synchronization with the transmission frame, there is no problem if the transmission frames are always transmitted. However, in a case where the transmission stop periods are present, the radio communication apparatus can not discriminate a case where there is the transmission stop between the transmission frames without and a case where there is not transmission stop between the transmission frames, until actually receiving a radio signal. Thus, the receiving section must carry out the detecting operation up to 112 bits (a total bit number of a preamble (PR) field+a sync signal
1
field+a preamble (PR) field+a sync signal
2
field) in the ON state. Therefore, it is said that the conventional radio communication apparatus is not effective from the viewpoint of making the ON time of the receiving section as short as possible.
In addition to the above-mentioned conventional technique, a non-synchronous type of a radio selection call method is disclosed in Japanese Laid Open Patent Application (JP-A-Showa 63-227134). This reference describes a technique of calling a plurality of called parties with a single dial. However, it does not describe the operation of detecting the preamble pattern at all.
Japanese Laid Open Patent Application (JP-A-Heisei 2-153633) discloses a non-synchronous type of a radio selection call receiver that can detect a preamble in a short time. In this reference, a preamble detecting circuit is kept in an ON state for a certain time in a shorter period than a time corresponding to a length of a preamble field. In this reference, the preamble detecting circuit is not kept in the ON state in synchronization with the preamble field. In addition, the preamble detecting circuit is not kept in the ON state in an entire time of the preamble field. The operation of receiving the data is not carried out if the preamble is not detected in this ON time.
Japanese Laid Open Patent Application (JP-A-Heisei 4-304041) discloses a non-synchronous type of a selection call receiver. According to this reference, a

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