JPH07221684A - Mobile terminal for mobile communication - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the call quality and the associated usability when one mobile communication wireless terminal device can be used in two different radio frequency bands. [Structure] Receiving means 111 for radio frequency band of 1.5 GHz
To 115, the transmission / reception means 121 to 125 and 131 to 135 in the radio frequency band of 900 MHz, and 900M
Receiving means 211 to 215 in the radio frequency band of Hz,
Transmitting / receiving means 221 to 2 in the radio frequency band of 1.5 GHz
25 and 231-235, two transmitting / receiving antennas 1, 2, an antenna changeover switch 3 for connecting the transmitting / receiving antenna 1 to either 111 or 121, and a transmitting / receiving antenna 2 for connecting to either 211 or 221. The antenna changeover switch 4 is included.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication wireless terminal device such as a car phone and a mobile phone, and more particularly to a wireless terminal device using a plurality of wireless frequency bands.

[0002]

2. Description of the Related Art In the field of mobile communication, particularly automobile phones and mobile phones using a cellular system, the spread of wireless terminal devices to general users is progressing due to the progress of miniaturization and weight reduction, and at the same time, the number of users is increasing. Accordingly, the shortage of the number of channels in the conventional analog cellular system has become a problem. In order to solve this problem, a new service based on the digital cellular system using a radio frequency band of 900 MHz has been started. For the method, refer to "Radio System Development Center, Digital Car Telephone System Standard (RCR STD-27B), December 1992.
"Revision on 0th" (abbreviated as "first document" below), and regarding the configuration of wireless terminal devices, see Isao Shimizu (4 others), Mobile Technology for Digital Mobile Communications (NTT R & D vo).
l. 40 No. 10 p. 1320 1991) "
(Hereinafter, abbreviated as the second document).

[0003]

The content described in the above-mentioned second document is a case of a wireless terminal device using one wireless frequency band. Further, as described in the above-mentioned first document, in order to solve the shortage of the number of channels, the service by the digital cellular system using the radio frequency band of 1.5 GHz band will be started soon. Here, when two wireless terminal devices that use different frequency bands are connected via a base station, it is common to convert both 900 MHz and 1.5 GHz radio frequency bands on the base station side.

Now, in one wireless terminal device, 900M
When making it possible to use in both radio frequency bands of Hz and 1.5 GHz, there is a problem that the number of components such as circuits increases, but in particular, in the case of an in-vehicle device, the application aspect is expanded by using two radio frequency bands. , You can expect improved usability. However, there was a problem that the specific content was not disclosed.

[0005]

In order to solve the above problems, in the most typical embodiment of the present invention, both a first radio frequency band and a second radio frequency band different from the radio frequency band are used. In a wireless terminal device for mobile communication capable of transmitting and receiving in a wireless communication system, a receiving unit in a first wireless frequency band, a transmitting and receiving unit in a first wireless frequency band, a receiving unit in a second wireless frequency band, Transmitting and receiving means in the second radio frequency band;
A transmitting / receiving antenna, a second transmitting / receiving antenna, a first transmitting / receiving antenna for receiving means in a first radio frequency band,
Selectively connecting to any of the transmitting / receiving means in the second radio frequency band, connecting to the transmitting / receiving means in the second radio frequency band during standby, receiving signals during transmission / reception, or from the base station side during transmission When the response signal sent is received, the first
When the reception state of the first radio frequency band is better than the reception state of the second radio frequency band, the first radio frequency band is compared with the reception state of the second radio frequency band. Antenna changeover switch connected to the receiving means in the second radio frequency band and connected to the transmitting and receiving means in the second radio frequency band when the reception state of the second radio frequency band is better than that of the first radio frequency band. And a second transmission / reception antenna selectively connected to either the transmission / reception means in the first radio frequency band or the reception means in the second radio frequency band. When connected to the transmitting / receiving means and receiving a reception signal during transmission / reception or a response signal transmitted from the base station side during transmission, the reception state of the first radio frequency band and the reception state of the second radio frequency band By comparison, the first radio frequency When the band is in a better reception state than the second radio frequency band, it is connected to the transmitting / receiving means in the first radio frequency band, and the second radio frequency band is received more than the first radio frequency band. A second antenna changeover switch connected to the receiving means in the second radio frequency band when the condition is good, and further when the first radio frequency band is in the better reception condition than the second radio frequency band. A first radio frequency band receiving means or a transmitting / receiving means in the first radio frequency band, whichever has a better reception state;
Diversity switch, and when the receiving condition of the second radio frequency band is better than that of the first radio frequency band, the transmitting / receiving unit in the second radio frequency band and the receiving unit in the second radio frequency band And a second diversity switch that selects whichever of the two has a better reception state;
And a channel switching switch that follows the selection of the second antenna switching switch at any time and selects either the output of the first diversity switch or the output of the second diversity switch.

[0006]

The communication quality can be improved by selecting one of the first and second radio frequency bands, whichever has a better reception state, by the antenna changeover switch and the channel changeover switch.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a circuit block diagram showing a first embodiment of the present invention. In the drawing, only the circuit of the wireless transmission / reception unit of the wireless terminal device is shown, and the audio signal processing circuit in the baseband unit is omitted. 1, 1 and 2 are transmitting and receiving antennas that can be used in both radio frequency bands of 900 MHz and 1.5 GHz, and 3 and 4 are 9
An antenna changeover switch for changing over the radio frequency bands used in both the radio frequency bands of 00 MHz and 1.5 GHz at any time, 5 is a channel changeover switch for changing over the selection of the antenna changeover switches in 3 and 4 at any time, and 6 is For example, when a certain signal is received in each of the radio frequency bands of 900 MHz or 1.5 GHz, a diversity switch that selects the better reception state, 7 is an output terminal of the received signal, and 8 is the first in the 900 MHz radio frequency band. 1 Input terminal of a frequency conversion carrier for converting to an intermediate frequency, 9 is an input terminal of a frequency conversion carrier for converting to a first intermediate frequency in a radio frequency band of 1.5 GHz, 10 is a radio frequency band of 900 MHz Input end of transmission carrier in , 11 are input terminals of a transmission carrier in a radio frequency band of 1.5 GHz, 12A and 12B are input terminals of modulated signals I and Q from a baseband unit for performing quadrature modulation, and 111 is a radio frequency band of 1.5 GHz. , A branching filter having a filter for passing only the vicinity of the receiving frequency band at 221 and having a filter for passing only the vicinity of the receiving frequency band at the time of reception and passing only the vicinity of the transmission frequency band at the time of transmission in the radio frequency band of 1.5 GHz , 112 and 222 are low noise amplifiers for amplifying a received signal with low distortion in a radio frequency band of 1.5 GHz, 113 and 223 are reception SAW filters for passing only near the reception frequency band in the radio frequency band of 1.5 GHz, 114 and 224 is the reception frequency in the 1.5 GHz radio frequency band as the first intermediate frequency Mixer for converting, 115 and 225, the 114 and 22
An IF demodulation circuit that passes only the vicinity of the first intermediate frequency in the received signal output from No. 4, demodulates and outputs the demodulated signal, 121 is a 900 MHz radio frequency band, and transmits only near the receiving frequency band when receiving, and transmits Sometimes, a duplexer having a filter that passes only the vicinity of the transmission frequency band, 211 is a receiver filter that passes only the vicinity of the reception frequency band in the 900 MHz radio frequency band,
22 and 212 are low noise amplifiers that amplify the received signal level with low distortion in the radio frequency band of 900 MHz,
Reference numerals 123 and 213 denote reception SAW filters that pass only the vicinity of the reception frequency band in the radio frequency band of 900 MHz, and 124 and 214, mixers for converting the reception frequency in the radio frequency band of 900 MHz into the first intermediate frequency, 125 and 215 is the above 124 and 214
The IF demodulation circuit that passes only the vicinity of the first intermediate frequency in the reception signal output from the IF demodulation circuit and outputs the demodulation signal, 131 represents the transmission carrier input from the 10 in the radio frequency band of 900 MHz,
Modulation signals I and Q from the baseband section input from B
A quadrature modulation circuit which modulates and outputs by 132,
The burst switch 133 operates such that the transmission signal output from 1 is always transmitted in the transmission time slot and is not transmitted in the other time slots to prevent signal leakage. A variable gain amplifier capable of amplifying a transmission signal output from the output and changing its gain.
Is a transmission SAW filter that passes only the vicinity of the transmission frequency band in the 900 MHz radio frequency band, and 135 is 90
A power amplifier 231 that amplifies the transmission signal output from the 134 to a specified transmission output level in a radio frequency band of 0 MHz and outputs the amplified transmission signal is supplied to the transmission carrier input from the eleven in the radio frequency band of 1.5 GHz. Quadrature modulator circuit that modulates and outputs the modulated signals I and Q from the baseband unit input from 12A and 12B, 2
Reference numeral 32 denotes a burst switch that operates to transmit the transmission signal output from the above-mentioned 231 at all transmission time slots and does not transmit at other time slots to prevent signal leakage. 233 is a 1.5 GHz radio A variable gain amplifier capable of amplifying the transmission signal output from the above-mentioned 232 in the frequency band and varying the gain thereof. A transmission SAW filter for passing only the vicinity of the transmission frequency band in the radio frequency band of 1.5 GHz, 234. Reference numeral 235 is a power amplifier that amplifies the transmission signal output from the aforesaid 234 to a prescribed transmission output level in the radio frequency band of 1.5 GHz and outputs it.

Here, the path from the receiving section filter 111 to the IF demodulation circuit 115 is a sub-channel for diversity reception in the radio frequency band of 1.5 GHz. The path from the demultiplexer 121 to the IF demodulation circuit 125 is 900 MHz.
It is the main channel for diversity reception in the z radio frequency band. The path from the quadrature modulation circuit 131 to the demultiplexer 121 is a transmission channel in the radio frequency band of 900 MHz. In addition, from the reception unit filter 211 to the IF demodulation circuit 2
The route to 15 is a sub-channel for diversity reception in the 900 MHz radio frequency band. In addition, the duplexer 221
From the IF demodulation circuit 225 is the main channel for diversity reception in the radio frequency band of 1.5 GHz. The path from the orthogonal modulation circuit 231 to the demultiplexer 221 is a transmission channel in the radio frequency band of 1.5 GHz.

A feature of the embodiment shown in FIG. 1 is that a radio frequency band having a better reception condition is selected and used from two different radio frequency bands. Therefore, there is an effect that quality can be improved during transmission and reception.

Next, the operation of each section will be described.

First, the reception will be described. At this time, the antenna changeover switches 3 and 4 are both connected to the lower contacts in the drawing and stand by for reception in both radio frequency bands of 900 MHz and 1.5 GHz.

For example, when a signal to be received is sent to a wireless terminal device, the base station side first receives 900 MHz and 1.5G.
The same signal is transmitted in both radio frequency bands of Hz,
On the side of the wireless terminal device, first, 900 MHz, 1.5
The main channel for diversity reception of the antenna changeover switches 3, 4 and 900 MHz is performed by simultaneously performing reception in both radio frequency bands of GHz and 1.5.
The main channel for diversity reception in the radio frequency band of GHz is demodulated to the path, and the demodulation output is judged by the error rate and the like, and the radio frequency band in which the reception state is good is selected and signal processing is performed.

For example, assume that the reception condition in the radio frequency band of 1.5 GHz is good.

The signal received by the transmission / reception antenna 2 is input to the demultiplexer 221 via the antenna changeover switch 4 to remove noise outside the reception frequency band, and then the low noise amplifier 222 is suitable for signal processing in the subsequent stage. It is amplified to the level. Then receive SAW filter 223
After the noise outside the reception frequency band is further removed at, in the mixer 224, the signal is converted into a signal of the first intermediate frequency and becomes a signal of a constant frequency that does not depend on the reception channel, and then demodulated by the IF demodulation circuit 225 and demodulated signal. Is output (the above is used as the 1.5 GHz band reception main channel path).

On the other hand, when it is determined that the reception condition is better in the radio frequency band of 1.5 GHz, the antenna changeover switch 3 is changed over to the upper contact in the drawing. Therefore, the same signal received by the transmission / reception antenna 1 is subjected to the same signal processing as that of the aforementioned 1.5 GHz band reception main channel path through the reception section filter 111, low noise amplifier 112, reception SAW filter, 113 mixer 114, and IF demodulation circuit 115. (The above is the reception sub-channel path for the 1.5 GHz band).

The demodulated signals output from the IF demodulation circuits 225 and 115 are input to the diversity switch 6 in the 1.5 GHz band reception main channel path, 1.5 GHz.
Diversity reception is performed by selecting the signal in the band reception sub-channel path that has the better reception condition.

When it is judged that the reception condition is better in the radio frequency band of 1.5 GHz, the channel changeover switch 5 is connected to the upper side in the drawing. Therefore, the output of the channel changeover switch 5 is directly output to the output terminal 7.

Similarly, when it is judged that the reception state is better in the 900 MHz radio frequency band, the antenna changeover switch 3 is on the lower side of the drawing, the antenna changeover switch 4 is on the upper side of the drawing, and the channel changeover switch 5 is in the drawing. Are respectively connected to the lower side in the drawing. The path from the demultiplexer 121 to the IF demodulation circuit 125 functions as a 900 MHz band reception main channel path, and the path from the reception unit filter 211 to the IF demodulation circuit 215 functions as a 900 MHz band reception sub channel path. The same processing is performed as in the case of processing the received signal in the radio frequency band.

Next, the operation during transmission will be described.

First, the antenna changeover switches 3 and 4 are connected to the lower side in the drawing, and the input terminals 12A and 12B.
Modulation signals I and Q from the baseband section input by
Is the input terminal 1 in the quadrature modulation circuits 131 and 231.
Modulates the transmission carriers input from 0 and 11 to 9
The variable gain amplifier 13 becomes a transmission signal in both radio frequency bands of 00 MHz and 1.5 GHz and is input to the burst switches 132 and 232 only during the transmission time slot.
3, 233 are input. Here, the transmission signal is amplified and input to the reception SAW filters 134 and 234 to remove noise outside the transmission frequency band, and then the power amplifier 13
In 5, 235, the transmission signal is amplified and output up to the specified transmission output level. After that, the duplexers 121,2
After the noise outside the transmission frequency band is further removed at 21, the transmission / reception antennas 1 and 2 are used to generate 900 MHz each.
Transmission signals are transmitted in both the radio frequency bands of z and 1.5 GHz. In this way, 900 MH even during transmission
Transmitting in both z and 1.5 GHz radio frequency band,
The radio frequency band in which the reception state of the response signal sent from the loopback base station is good is selected.

As described above, according to the transmission / reception method of the wireless terminal device in the first embodiment of the present invention, the received signal to be received sent from the base station side or the response sent from the return base station side. The state of the signal is judged based on, for example, the error rate after demodulation, and the radio frequency band in a good state is selected. That is, the states of the demodulation outputs in the 1.5 GHz band reception main channel path and the 900 MHz band reception main channel path described above are compared, and a radio frequency band in a good state is selected for transmission / reception.

If the radio frequency band of 1.5 GHz is selected, the antenna changeover switch 3 and the channel changeover switch 5 are connected to the upper side in the drawing, and the antenna changeover switch 4 is connected to the lower side in the drawing, and 900
If the radio frequency band of MHz is selected, the antenna switch 3 and the channel switch 5 are
On the lower side, the antenna changeover switch 4 is connected to the upper side in the drawing.

After selecting one of the radio frequency bands, the unused circuit parts (transmission / reception channels on the side to which the antenna changeover switches 3 and 4 are not connected) are turned off so as not to operate. (Hereinafter, abbreviated as the first means), or while still operating, the states of demodulation outputs of two radio frequency bands may be constantly compared with each other, and a good radio frequency band may be selected and switched at any time. (Hereinafter, it is abbreviated as the second means). In the case of the above-mentioned first means, it becomes possible to allocate the channel of the side not selected by the base station side to another user. In the case of the above-mentioned second means, it becomes easy to maintain a good reception state.

Next, a second embodiment of the present invention will be described with reference to the circuit block diagram of FIG.

2 is different from FIG. 1 in that 900 MHz, 1.
It only has a main channel for transmission / reception in both radio frequency bands of 5 GHz, and the transmission / reception antennas 1 and 2 are directly connected to the demultiplexer 12 without an antenna changeover switch.
1 and 221 are connected.

Since all the components that make up the circuit are the same as those numbered in FIG. 1, detailed description of their operation will be omitted.

In FIG. 2, 900 MHz, 1.5 GH
There is no sub-channel for diversity reception in both radio frequency bands of z. At the time of both reception and transmission, only the operation of selecting a good radio frequency band in either of the 900 MHz and 1.5 GHz radio frequency bands is always performed, and the effect of diversity reception is substantially obtained. is there. Therefore, the channel selector switch 5
This also serves as the function of the diversity switch 6 in FIG. As in the embodiment shown in FIG. 1, the call quality may not be the best as compared with the one in which a channel with a good condition is selected in each radio frequency band of 900 MHz or 1.5 GHz. There is a merit that it can be realized. Of course, similarly to the above-described embodiment of FIG. 1, after selecting any one of the radio frequency bands, the unused circuit part may be turned off or otherwise not operated, or may be operated. Alternatively, the states of the demodulation outputs of the two radio frequency bands may be constantly compared with each other, and the radio frequency band may be selectively switched to a good one at any time.

[0028]

According to the present invention, in a wireless terminal device such as a mobile phone that uses a plurality of radio frequency bands, it is possible to improve the call quality and the usability thereof.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit block diagram showing a second embodiment of the present invention.

[Explanation of symbols]

1, 2 ... Transmitting / receiving antenna, 3, 4 ... Antenna changeover switch, 5, ... Channel changeover switch, 6 ... Diversity switch, 7 ... Output terminal, 8, 9, 10, 11, 12A, 12B, ... Input terminal, 111, 211 ... Receiving unit filter, 121, 221, ... Demultiplexer, 112, 122, 212, 222 ... Low noise amplifier, 113, 123, 213, 223 ... Receiving SAW filter, 114, 124, 214, 224, ... Mixer, 115, 125, 215, 225 ... IF demodulation circuit, 131, 231 ... Quadrature modulation circuit, 132, 232 ... Burst switch, 133, 233 ... Variable gain amplifier, 134, 234 ... Transmission SAW filter, 135, 235 ... Power amplifier.

Claims (2)

[Claims] 1. A wireless terminal device for mobile communication capable of transmitting and receiving in both a first radio frequency band and a second radio frequency band different from the first radio frequency band, and receiving means in the first radio frequency band. A transmitting / receiving means in the first radio frequency band, a receiving means in the second radio frequency band, a transmitting / receiving means in the second radio frequency band, a first transmitting / receiving antenna, and a second transmitting / receiving antenna And selectively connecting the first transmission / reception antenna to either the reception means in the first radio frequency band or the transmission / reception means in the second radio frequency band, and in the standby state, in the second radio frequency band. When connected to the transmitting / receiving means and receiving a reception signal during transmission / reception or a response signal transmitted from the base station side during transmission, the reception state of the first radio frequency band and the reception state of the second radio frequency band By comparison, the first radio frequency band Is connected to the receiving means in the first radio frequency band when the reception state is better than the second radio frequency band, and the reception state in the second radio frequency band is better than that in the first radio frequency band. In that case, the first antenna changeover switch connected to the transmitting / receiving means in the second radio frequency band, the second transmitting / receiving antenna in the first radio frequency band, and the receiving / receiving means in the second radio frequency band Selectively connecting to any of the means, connecting to the transmitting / receiving means in the first radio frequency band during standby, receiving a reception signal during transmission / reception, or receiving a response signal sent from the base station side during transmission , Comparing the reception state of the first radio frequency band and the reception state of the second radio frequency band, and when the reception state of the first radio frequency band is better than that of the second radio frequency band, Transmission / reception means in the radio frequency band A second antenna changeover switch connected to the receiving means in the second radio frequency band when the second radio frequency band is in a better reception state than the first radio frequency band. When the radio frequency band is better than the second radio frequency band in the reception state, the reception state of either the reception means in the first radio frequency band or the transmission / reception means in the first radio frequency band A first diversity switch for selecting a better one; and a transmitting / receiving means in the second radio frequency band and a second radio frequency band when the second radio frequency band has a better reception condition than the first radio frequency band. A second diversity switch for selecting one of the receiving means in the radio frequency band having a better reception state, and the selection of the first and second antenna changeover switches at any time, Diver City switches and wireless terminal apparatus of a mobile communication, characterized in that a channel selection switch for selecting either the output of the second diversity switch. 2. A wireless terminal device for mobile communication capable of transmitting and receiving in both a first radio frequency band and a second radio frequency band different from the first radio frequency band, and transmitting and receiving means in the first radio frequency band. A transmitting / receiving means in the second radio frequency band, a first transmitting / receiving antenna directly connected to the transmitting / receiving means in the first radio frequency band, and a transmitting / receiving means in the second radio frequency band. A second transmitting / receiving antenna and a receiving signal at the time of transmitting / receiving or a response signal sent from the base station side at the time of transmitting, receiving state of the first wireless frequency band and receiving of the second wireless frequency band By comparing the states, when the reception state of the first radio frequency band is better than that of the second radio frequency band, the output of the transmission / reception means in the first radio frequency band is selected, and the second radio frequency band is selected. Is the first radio frequency band Remote reception state when good mobile communication of the wireless terminal apparatus characterized by comprising a channel selector switch for selecting the output of the transmitting and receiving means in the second radio frequency band.