Communications: electrical – Continuously variable indicating – With meter reading
Reexamination Certificate
1995-07-13
2001-10-30
Cuchlinski, Jr., William A. (Department: 3661)
Communications: electrical
Continuously variable indicating
With meter reading
C340S870030, C340S870030, C370S349000
Reexamination Certificate
active
06310558
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a selective calling system, and more specifically to a format of a transmission signal, a method associated with transmitting and receiving the transmission signal and a receiver for receiving the transmission signal.
2. Related Art
As to a selective calling receiver which is usually taken on the road, the life of a battery as a power supply is a fundamental performance category. Especially, with the miniaturization of the receiver includes in recent years, a smaller battery is increasingly demanded. Therefore, how to make the battery life long becomes a more important technical problem.
The battery life is determined by two main parameters: the amount of the power consumption of the receiver and the intermittent receiving interval. Since a considerable portion of the power consumption is made in a radio frequency system, so far as a receiving operation is performed, one can not hope for a drastic improvement of the power consumption. Then, a method of making the intermittent receiving interval longer is proposed to reduce an average power consumption. In order to make the intermittent receiving interval longer, a synchronous system is under consideration in place of an asynchronous system (for example, POCSAG system) which is used widely at present. One example of the synchronous system is ERMES (European Radio Message System).
ERMES employs the following method. A frame number is given to each time division frame in advance and a base station transmits a calling signal with the frame number which a certain receiver should receive. This method allows the intermittent receiving interval to be lengthened dramatically as compared with the asynchronous system.
A transmitting signal of ERMES is comprised of a synchronization field, an address field and a message field. The message field is further comprised of a message and a message header indicating attributes of the message. Since the message header indicates which address the message belongs to, the transmission order of the message can be determined arbitrarily regardless of its address. For example, a paging system which is disclosed in Japanese Patent Unexamined Publication No. 63-158924 (publication date: Jul. 1st, 1988) employs a method for lengthening a receiving internal by designating the frame number which should be received.
However, the conventional selective calling system mentioned above needs a complicated system configuration. Further, a lot of additional bits are required in a transmission message signal, resulting in increased overhead of the message signal, which causes the message transmission efficiency to be reduced. Therefore, even though a high-speed transmission system is adopted, the expected increase of the subscriber capacity cannot be achieved.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a data communication method which achieves an improved transmission efficiency, a larger capacity of subscribers and lower power consumption of a subscriber receiver.
Another object of the present invention is to provide a receiving method which achieves high reliability of receiving message signals with simple steps.
Still another object of the present invention is to provide a selective calling data which achieves receiving of message signals with high reliability, simple structure and lower power consumption.
A transmission signal format according to the present invention is as follows. A specific time period is divided into a plurality of frames. Each the frame is comprised of a synchronization field, an address field, and a message field. The address field is comprised of a plurality of addresses associated with the subscriber's receivers, respectively. The message field is comprised of a plurality of messages corresponding to the addresses, respectively. A message is comprised of a message and a message header which includes a transmitting sequence number of the address corresponding to that message.
A base station transmits the transmission signals to the receivers. The receiver receives a frame of each transmission signal intermittently. When receiving the frame, the receiver sequentially searches the address field for an ID address of the receiver itself while incrementing a receiving sequence count at each address. When the ID address is found, the receiver stores the receiving sequence count at that time. Subsequently, the receiver searches the message field for the message corresponding to the ID address by comparing the receiving sequence count stored with the transmitting sequence number included in the message. When the transmitting sequence number is coincident with the receiving sequence count, the message data addressed to the receiver is detected from the message field.
The address field is preferably terminated by a predetermined word. The receiver stops searching the address field when the predetermined word is found, and then back to the receiving step.
More specifically, the message header is further comprised of a first field for containing a message header indicator, a second field for containing the transmitting sequence number, a third field for containing a message type, and a fourth field for containing a message length. In this case, the receiver detects a message header from the message field when comparing the receiving sequence count stored with the transmitting sequence number included in the message header. And, the message addressed to the receiver itself is input using the message type and the message length when the receiving sequence count stored is coincident with the transmitting sequence number.
As described above, the communication method according to the present invention provides the relationship between a transmission order of each address in an address field and an address transmission number of each message header in a message field in each message frame. Therefore, a message is defined by a short message header even when a synchronous system is employed.
In addition, the selective calling receiver according to the present invention stores the transmission order of its own address in the address field of the message frame received. When the transmission order stored is coincident with the transmission sequence number of the message header, the receiver selects the message data following the message header as a message addressed to the receiver itself. Therefore, high reliability can be realized with a simple structure.
REFERENCES:
patent: 4479124 (1984-10-01), Rodriguez et al.
patent: 4668949 (1987-05-01), Akahori et al.
patent: 5089813 (1992-02-01), DeLuca et al.
patent: 5315635 (1994-05-01), Kane et al.
patent: 5363090 (1994-11-01), Cannon et al.
patent: 2114343 (1983-08-01), None
patent: 63158924 (1988-07-01), None
Beaulieu Yonel
Cuchlinski Jr. William A.
NEC Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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