Digital portable telephone device

Details Digital portable telephone device Digital portable telephone device

1997-12-10

2002-01-29

Hunter, Daniel (Department: 2684)

Telecommunications

Transmitter and receiver at same station

Radiotelephone equipment detail

C455S168100, C455S188100

Reexamination Certificate

active

06343221

ABSTRACT:

BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to digital portable telephone devices in which frequency-division multiple access (FDMA) is carried out by using a signal within either one of an analog frequency band and a digital frequency band.
Marketing of digital portable telephones by new business ventures in Japan has started in April 1995, and low-cost digital portable telephones have come to be available to the users. The number of digital portable telephone subscribers is remarkably increasing.
Because of the rapid growth in demand for portable telephone services, the available transmission capacity in some areas is frequently saturated, eroding customer satisfaction. Currently, there is a need for increasing the capacity of the available channels in order to reduce the occurrences of busy conditions in transmission lines.
As one of the measures for satisfying the need, introduction of a dual-rate standard, in addition to the existing full-rate standard, started in December 1995. When a dual-rate system is placed in operation, switched operations of a full-rate codec and a half-rate codec are performed.
A further increase in the number of portable telephone subscribers in the future is expected. New digital portable telephone systems which enable the capacity of the available channels to be increased by allocating the frequency bands for the existing analog systems to the frequency bands for the digital systems will be introduced to practical use.
(2) Description of the Related Art
FIG. 1A
shows analog receiving/transmitting frequency bands used by existing digital portable telephone devices, and
FIG. 1B
shows digital receiving/transmitting frequency bands used by the existing digital band portable telephone devices.
As shown in
FIG. 1A
, the existing digital portable telephone devices use receiving frequencies of 870 MHz-885 MHz (which will be called analog receiving frequencies) and transmitting frequencies of 925 MHz-940 MHz (which will be called analog transmitting frequencies). The difference between the receiving frequencies and the transmitting frequencies for the existing digital portable telephone devices is about 55 MHz.
As shown in
FIG. 1B
, the existing digital portable telephone devices use receiving frequencies of 810 MHz-826 MHz (which will be called digital receiving frequencies) and transmitting frequencies of 940 MHz-956 MHz (which will be called digital transmitting frequencies). The difference between the receiving frequencies and the transmitting frequencies for the existing digital portable telephone devices is about 130 MHz.
FIG. 2
shows a basic configuration of a conventional digital portable telephone device which uses both the analog and the digital frequency bands. As shown in
FIG. 2
, the conventional digital portable telephone device generally has a receiver section and a transmitter section.
The receiver section comprises a receiving antenna (ANT
0
), a switch (SW
1
), a switch (SW
3
), a digital-band radio-frequency receiver (RX
1
) unit
12
, an analog-band radio-frequency receiver (RX
2
) unit
14
, a switch (SW
5
), an intermediate-frequency (IF) unit
16
, and a demodulator (DEM) unit
18
. The switch SW
1
is provided to select a diversity mode in which a switching between the receiving antenna ANT
0
and a transmitting antenna (ANT
1
) is performed. The switch SW
3
is provided to select one of an input of the RX
1
unit
12
and an input of the RX
2
unit
14
for the receiver section. The switch SW
5
is provided to connect one of an output of the RX
1
unit
12
and the RX
2
unit
14
to an input of the IF unit
16
.
In order to cover the analog and digital receiving bands, the digital-band RX
1
unit
12
and the analog-band RX
2
unit
14
are separately provided in the receiver section, and the IF unit
16
is provided in common for the RX
1
unit
12
and the RX
2
unit
14
.
In the conventional digital portable telephone device of
FIG. 2
, a control unit, including a time division multiple access (TDMA) unit
20
, a coder/decoder (CODEC) unit
22
and an audio-frequency amplifier (AUDIO) unit
24
, is provided in common for the receiver section and the transmitter section. An input/output interface (I/O) unit
34
is connected to the TDMA unit
20
, the CODEC unit
22
and the AUDIO unit
24
in the control unit. Further, in the control unit, a central processing unit (CPU)
30
and memory devices
32
(ROM, RAM) are provided. A speaker (SPK)
26
is connected to the AUDIO unit
24
and constitutes an element of the receiver section. A microphone (MIC)
28
is connected to the AUDIO unit
24
and constitutes an element of the transmitter section.
Further, the transmitter section of the conventional digital portable telephone device comprises a transmitting antenna (ANT
1
), a switch (SW
2
), a switch (SW
4
), a radio-frequency modulator (RF MOD
1
) unit
38
, a digital-band transmitter (PA
1
) unit
40
, a radio-frequency modulator (RF MOD
2
) unit
42
, an analog-band transmitter (PA
2
) unit
44
, and a base-band modulator (MOD BB) unit
36
. The switch SW
2
is provided to select one of the receiver section and the transmitter section. The switch SW
4
is provided to connect one of an output of the PA
1
unit
40
and an output of the PA
2
unit
44
to the transmitting antenna ANT
1
.
In order to cover the analog and digital transmitting bands, the digital-band PA
1
unit
40
(including the RF MOD
1
unit
38
) and the analog-band PA
2
unit
44
(including the RF MOD
2
unit
42
) are separately provided in the transmitter section, and the MOD BB unit
36
is provided in common for the PA
1
unit
40
and the PA
2
unit
44
.
In the conventional digital portable telephone device of
FIG. 2
, a voice signal received at the receiving antenna “ANT
0
” is delivered to either one of the digital-band RX
1
unit
12
and the analog-band RX
2
unit
14
via the switches SW
1
and SW
3
. The signal from one of the RX
1
unit
12
and the RX
2
unit
14
is delivered to the TDMA unit
20
through the switch SW
5
, the IF unit
16
and the DEM unit
18
.
The TDMA unit
20
generates a reproduction signal by using a demodulated signal from the DEM unit
18
, and separates a demultiplexed signal from the reproduction signal. The CODEC unit
22
converts the demultiplexed signal from the TDMA unit
20
into a decoded signal. The decoded signal from the CODEC unit
22
is amplified by the AUDIO unit
24
. The speaker
26
is driven in accordance with the amplified signal from the AUDIO unit
24
.
On the other hand, a voice signal supplied from the microphone
28
is processed in a reverse manner. A digital signal processed by the TDMA unit
20
in response to the voice signal is sent to the MOD BB
36
. A modulated signal from the MOD BB unit
36
is passed through one of the digital-band transmitter (the RF MOD
1
unit
38
and the PA
1
unit
40
) and the analog-band transmitter (the RF MOD
2
unit
42
and the PA
2
unit
44
). A transmitting signal from one of the digital-band transmitter and the analog-band transmitter is sent to the transmitting antenna ANT
1
via the switches SW
4
and SW
2
. This signal is transmitted from the transmitting antenna ANT
1
.
Next,
FIG. 3
shows a detailed structure of the conventional digital portable telephone device. A description will now be given of an operation of the receiver section of the conventional digital portable telephone device with reference to FIG.
3
.
As shown in
FIG. 3
, in the conventional digital portable telephone device, a switch SW
61
is provided to select the diversity mode, a switch SW
62
is provided to select one of the receiver section and the transmitter section, a switch SW
63
is provided to select one of the digital-band receiver and the analog-band receiver, and a switch SW
64
is provided to connect one of the digital-band transmitter and the analog-band transmitter to the transmitting antenna ANT
1
.
When a radio-frequency signal within the digital receiving frequencies of 810 MHz-826 MHz is received at the r

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