Radio paging system

Details Radio paging system Radio paging system

1999-01-19

2002-03-12

Chin, Stephen (Department: 2634)

Pulse or digital communications

Spread spectrum

C375S141000, C340S870030

Reexamination Certificate

active

06356579

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a two-way paging system capable of calling users carrying pagers by radio, and allowing them to send messages from their pagers to base stations. In the following description, a signal from a pager to a base station is referred to as an “upward signal”.
BACKGROUND ART
FIG. 1
is a block diagram showing a two-way paging system, which applies a direct sequence spread spectrum scheme to transmit upward signals from pagers to base stations. The paging system comprises a central station
3
connected to a communications network
2
; a plurality of (n) base stations
7
-
1
-
7
-n connected to the central station
3
; and pagers
8
-
1
and
8
-
2
capable of carrying out radio communications with the base stations
7
-
1
-
7
-n.
The central station
3
comprises an accepting unit
10
, encoder
11
, spreading code assigner
12
and line terminal unit
13
. The accepting unit
10
is connected to the communications network
2
, receives paging request signals from the communications network
2
, and supplies them to the encoder
11
. The encoder
11
converts the paging request signals and code notification signals into paging signal sequences. The code notification signals are output from the spreading code assigner
12
to notify the pagers of spreading codes for the upward signals. The line terminal unit
13
delivers the paging signal sequences to corresponding base stations. The line terminal unit
13
also receives the upward signals sent from the pagers through the base stations, collects them, and supplies them to the accepting unit
10
. Thus, the accepting unit
10
notifies the telephone
1
or computer terminal
9
of a paging response through the communications network
2
.
The base stations
7
-
1
-
7
-n each comprise a line terminal unit
20
, transmitter
21
, spreading code memory
25
and receiver
24
. The line terminal unit
20
receives the paging signal sequences from the central station
3
, and transfers them to the transmitter
21
. The transmitter
21
converts them to radio signals (electromagnetic waves), and transmits them at a frequency F
1
. The receiver
24
in each of the base stations
7
-
1
-
7
-n receives the upward signals from the called pagers that are detecting the paging signals addressed thereto. The receiver
24
uses a plurality of spreading codes prestored in the spreading code memory
25
for despreading these upward signals. The received upward signals are transmitted through the line terminal unit
20
to the central station
3
, so that it sends the response information to the telephone
1
or computer terminal
9
via the communications network
2
.
Next, the operation will be described for paging the pager
8
-
1
or
8
-
2
from the fixed telephone
1
or computer terminal
9
. The user inputs to the telephone
1
or computer terminal
9
the called number of the pager
8
-
1
or
8
-
2
, and a message if there is any. The input information is sent to the central station
3
through the communications network
2
as a paging request signal. In the central station
3
, the encoder
11
converts into the paging signal sequence the paging request signal from the accepting unit
10
and the code notification signal supplied from the spreading code assigner
12
to notify the called pager of the spreading code. The line terminal unit
13
transmits it to the base stations
7
-
1
-
7
-n. The base stations
7
-
1
-
7
-n each convert it to a radio signal (electromagnetic wave), and transmit it simultaneously to their own radio zones
5
-
1
-
5
-n at the same frequency F
1
. The pagers
8
-
1
and
8
-
2
each receive the radio signal at the predetermined frequency F
1
, and informs the user of the pager when they detect the paging signal calling them. After that, the pager
8
-
1
or
8
-
2
sends to the base stations a paging response it produces by the direct sequence spread spectrum modulation using the spreading code that is defined by the code notification signal received in conjunction with the paging signal. The base station in the radio zone in which the pager is located despreads the upward signal using the spreading code prestored in the spreading code memory
25
, and transmits it to the central station
3
(in the example as shown in
FIG. 1
, the base station
7
-
1
receives the upward signal transmitted from the pager
8
-
1
, and the base station
7
-
2
receives the upward signal transmitted from the pager
8
-
2
). Thus, the central station
3
notifies the telephone
1
or computer terminal
9
via the communications network
2
that the pager accepts the call.
FIG. 2
illustrates a structure of the paging signal sequence sent from the base stations. The paging signal sequence is based on the signal structure shown in the RCR STD-43 standard worked out by Association of Radio Industries and Businesses in Japan. In this signal structure, the paging signal sequence consists of frame sequences each of which includes m successive frames as shown in FIG.
2
(
a
). Each frame has a signal length of Tf, and consists of a synchronization signal and p subframes as shown in FIG.
2
(
b
) which illustrates the i-th frame (1≦i≦m) as an example, which will be called “frame i” from now on. Here, p represents the number of times of transmissions of the same paging signal. Each subframe of the frame i includes an address field, vector field and message field: The address field consists of qji (1≦j≦p) address signals; the vector field consists of qji vector signals corresponding to the address signals; and the message field consists of qji message signals corresponding to the address signals as shown in FIG.
2
(
c
) which illustrates the p-th subframe. A vector signal k (1≦k≦qji) indicates the start point and end point of a message signal k corresponding to an address signal k. With such a signal structure, the code notification signal is affixed to an initial position of each message signal in the message field.
Thus, the subframe p in the frame i in the paging signal sequence has qpi paging signals inserted thereinto, wherein k-th (1≦k≦qpi) paging signal is provided with the code notification signal Cuk indicative of the spreading code used for generating the upward signal by the direct sequence spread spectrum modulation. When the pager, to which the frame i is assigned to be received, detects its own paging signal in the frame i during the transmission period Tf beginning from time t
0
, it starts to transmit the response upward signal corresponding to the paging signal from time t
0
+Tf at the earliest. FIG.
2
(
d
) illustrates an example in which it transmits the upward signal during time t
0
+2Tf-t
0
+3Tf considering the processing delay and the like required for receiving and transmitting the signal.
FIG. 3
is a block diagram illustrating a configuration of the pager. It comprises a receiver
30
, controller
31
, speaker
32
, driver
33
, display
34
and transmitter
35
. The transmitter
35
is a direct sequence spread spectrum modulation transmitter. The receiver
30
is brought into a receiving state only during a receiving period of one or more preassigned frames among the paging signal sequences transmitted from the base station, and receives the frames. This technique, which is called an intermittent receiving method, can prolong the life of the battery of the pager. The controller
31
checks whether its own paging signal is present or not in the received frame, and notifies, if it is detected, the user that a call takes place, by a beep from the speaker
32
or some other alarms. If the paging signal includes a message, the controller
31
displays it on the display
34
via the driver
33
. Then, the controller
31
supplies the transmitter
35
with a response upward signal corresponding to its own paging signal detected, together with a spreading code uniquely determined by the code notification signal contained in the paging signal. The transmitter
35
carries out, using the spreading code fed from the controller
31
, the d

Affiliated with

Also associated with

Rating

Radio paging system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Radio paging system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radio paging system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2838689