JPH0366232A - Transmitter-receiver for on-vehicle communication - Google Patents

Abstract

PURPOSE:To decrease the loss of a transmission signal and a reception signal by selecting a band pass filter having a large gradient in the attenuation in the FDMA system and applying the transmission and reception at a separate time, and selecting a band pass filter having a small loss and a small gradient in the attenuation in the TDMA system. CONSTITUTION:Band pas filters 41, 51 with many number of stages are employed for the use of the FDMA system to increase the gradient in the attenuation near the border of transmission and reception frequencies and band pass filters 42, 52 with less number of stages are employed for the use of the TDMA system to decrease the loss. A signal is sent/received in a time slot assigned to a transmitter-receiver in the TDMA system, the signal is sent through an incoming line by a transmission reception antenna via the band pass filter 42 and a transmission reception changeover switch 64 and the signal is received through an outgoing line by the transmission reception changeover switch 64 and the band pass filter 52 and inputted to a demodulator 23.

Description

[Detailed Description of the Invention] [Summary] Regarding a transmitting/receiving device used in a mobile communication system, it is capable of supporting a system in which both a time division multiple access method and a frequency division multiple access method coexist, and is capable of supporting a time division multiple access method and a frequency division multiple access method. The aim is to provide a transmitting/receiving device with low loss in the connection method and with little leakage of transmitted signals to the receiving section in the frequency division multiple access method.The transmitting signal is mounted on a mobile object and output from the transmitting section to the transmitting/receiving antenna. , and a received signal input from the transmitting/receiving antenna to the receiving unit is transmitted and received via a first band-pass filter on the transmitting unit side and a second band-pass filter on the receiving unit side, which extract frequency components of each signal. The transmitting/receiving device is switchably connected to the first band-pass filter and the second band-pass filter, and the slope of the frequency characteristic of the attenuation is adjusted to the first and second bands near the boundary between the transmitting frequency and the receiving frequency. In the frequency division multiple access system, transmission and reception are performed via the first and second band pass filters, and a third band pass filter and a fourth band pass filter smaller than the fI pass filter and a communication method are used. In the division multiple access system, a control section is provided which performs transmission and reception at different times and performs control so that transmission and reception are performed via the third and fourth bandpass filters.

[Industrial application field]

The present invention relates to a transmitting/receiving device used in a mobile communication system.

In conventional mobile communication systems, frequency division multiple access (hereinafter referred to as FDMA) has been widely used. This is a multiple access system that allocates a downlink (information signal transmitted by a base station) band and an uplink (information signal transmitted by a mobile station) band to each of a large number of mobile stations. However, because the number of communication lines that can be allocated is limited, it has become difficult to cope with the recent increase in communication volume. Therefore, in order to improve frequency efficiency and cope with the increase in communication volume, the uplink and downlink each use one or a small number of frequencies.
Time division multiple access (hereinafter referred to as TDMA), in which one frequency is divided and allocated to a large number of mobile stations at different times for transmission and reception.
method) is gradually being adopted. But still F
Since the DMA system is also widely used, there is a desire for a transmitter/receiver installed in a mobile station that can support a mobile communication system in which both FDMA and TDMA systems coexist, and that can operate with high performance in the TDMA system. There is.

[Conventional technology]

FIG. 2 is an explanatory diagram of frequency attenuation characteristics of a bandpass filter used in a transmitting/receiving device. In the figure, the frequency attenuation characteristics of the band-pass filters on the transmitter side and the receiver side used in the transmitter/receiver in each communication system are shown by a solid line for the FDMA system, and by a dashed-dotted line for the TDMA system.

FIG. 8(a) shows an example of the configuration of a transmitting/receiving device in a conventional FDMA system. In the figure, 1 is a transmitting section in the transmitting/receiving device, 2 is a receiving section, and 3 is a transmitting/receiving antenna. 8 duplexers are connected to the transmitting section 1, the receiving section 2, and the transmitting/receiving antenna 3. used. The duplexer 8 includes band pass filters 81 and 82 and a circulator 83.

The circulator 83 outputs the transmission signal for the uplink to the transmitting/receiving antenna, and also outputs the signal received on the downlink by the transmitting/receiving antenna to the receiving section.The transmitting signal is sent to the receiving section, and the received signal is sent to the transmitting section. It is set not to be output. However, the insulation is not perfect, and some amount of the transmitted signal leaks to the receiving section. Therefore, it is necessary for the bandpass filter 8182 to increase the slope of the attenuation amount near the boundary between the transmission frequency and the reception frequency (between the two broken lines), as shown by the solid line in FIG. Generally, to increase the amount of attenuation, the number of stages of the band-pass filter is increased, so a band-pass filter with a large number of stages (5 to 6 stages) is used. However, FDMA A bandpass filter used in this method, in which the slope of the attenuation amount is increased by increasing the number of stages, etc., has a large loss as shown by the solid line in FIG.

On the other hand, the transmitting and receiving equipment for both TDMA is basically FD.
Similar to the MA method, the configuration shown in FIG. 8(a) is used. Figure 3 shows the frame and slot I of a TDMA signal.
・This is a conceptual diagram of the configuration. In the 'T' DMA system, when each slave station transmits, one frame, which is a basic period, is time-divided, and a time portion (time slot) for each slave station to transmit is allocated within the frame.

Also, for reception, a time slot for each slave station to receive is assigned in the same way as for transmission. In this case, as shown in FIG. 3, the transmission time and the reception time do not need to be the same.

Therefore, by changing the transmission time and reception time, the transmission signal will not leak at the reception time, so the bandpass filter of this transmitter/receiver is the same as that of the FDMA transmitter/receiver described above, as shown by the dashed line in Fig. 2. It is not necessary to increase the slope of the attenuation amount of the bandpass filter. Therefore, by using an IF pass filter with a small number of stages, the loss can be further reduced.
A stage bandpass filter is used. Although such a band-pass filter with a small number of stages has a small slope of attenuation, it can be used for the above-mentioned reason.

Furthermore, in the TDMA system, as shown in FIG. 8(b), a changeover switch 84 may be provided at the connection between the transmitting/receiving antenna, the transmitting section, and the receiving section without using a circulator. This is connected to the contact a side at the sending time,
At the time of reception, the transmitter and receiver are completely isolated by connecting to the contacts, so there is no leakage of the transmit signal to the receiver at any time, so the slope of the attenuation is reduced to reduce loss. It becomes easier to use a bandpass filter with a small value.

[Problem to be solved by the invention]

A transmitter/receiver mounted on a mobile body used in a system in which both TDMA and FDMA power type communications are mixed uses the configuration shown in Figure 8(a) and has a transmitter inside which transmits the signal to the modulator. In addition, a method has been considered in which the receiver is provided with means for switching the signal from the demodulator. However, if a bandpass filter with a large attenuation slope for the FDMA system is used in a transmitting/receiving device compatible with both communication systems, the loss will become unnecessarily large in the TDMA system. Furthermore, if a bandpass filter with low loss and a small slope of attenuation is used for the TDMA system, the influence of leakage of the transmission signal to the receiving section becomes large in the FDMA system.

An object of the present invention is to provide a transmitting/receiving device that can support a system in which both TDMA and FDMA communication systems coexist, has little loss in the TDMA system, and has little leakage of transmitted signals to the receiving section in the FDMA system. do.

[Means to solve the problem]

0 FIG. 1 is a diagram explaining the principle of the present invention.

In the figure, 1 is a transmitting section, 2 is a receiving section, and 3 is a transmitting/receiving antenna. Reference numeral 4 denotes a band-pass filter section for a path (hereinafter referred to as a transmission side path) for outputting a transmission signal from the transmitting section 1 to the transmitting/receiving antenna 3, and 5 inputs a received signal from the transmitting/receiving antenna 3 to the receiving section. This is the bandpass filter section of the path (hereinafter referred to as the receiving side path).

The bandpass filter sections 4 and 5 on the transmitting side and the receiving side include a first bandpass filter 41 and a second bandpass filter, respectively.
bandpass filter 51, and bandpass filter 41.
The configuration is such that the third band-pass filter 42 and the fourth band-pass filter 52, which have a smaller slope of attenuation than the band-pass filter 51, are switched and connected.

The control unit 6 is FDMA system or T I) M A
detect which communication method is being used,
It switches each of the band-pass filters described above and controls the transmitter and receiver for performing transmission and reception in accordance with the communication method.

The transmitter/receiver according to the present invention switches and connects the bandpass filters in the bandpass filter sections 4 and 5, so that when the communication system is the FDMA system, the transmission/reception device connects the bandpass filters through the first and second bandpass filters 41 and 51. When the communication system is TDMA, transmission and reception is performed via the third and fourth band pass filters 42 and 52.

In the present invention, when transmitting and receiving data using the TDMA system, transmission and reception are performed at different times as shown in FIG. This prevents the transmitted signal from leaking to the receiving section at the reception time, making it possible to use a bandpass filter with little loss and a small slope of attenuation.

[Function] In the present invention, the control unit detects the communication mode, and in the FDMA system, by connecting to the band pass filter side with a large attenuation slope, there is less leakage of the transmitted signal to the receiving unit, and in the TDMA system, the control unit detects the communication form. By performing transmission and reception at different times and connecting to the side of a band-pass filter with a small number of stages, which has a small loss and a small slope of attenuation, a transmitting/receiving device with low loss of the transmitted signal and the received signal can be realized.

[Embodiments] (a) Description of the transmitting/receiving device of the first embodiment FIG. 4 is a block diagram of the first embodiment of the transmitting/receiving device according to the present invention.

In the figure, the same parts as those shown in FIG. 1 are indicated by the same symbols. FIG. 5 is an explanatory diagram of a method of transmitting a switching instruction signal and an information signal (audio signal) in the downlink. Note that this embodiment deals with audio signals from telephone calls and the like.

The transmitter 1 includes an encoder 11 that converts an analog audio signal into a digital signal, a signal processor 12 that performs signal processing on the output of the encoder 11, and an input audio signal and signal processor 12.
Selector switch 1 that switches between and outputs the output signal of
4. Modulate the output signal of the changeover switch 14 and mixer 1
It is configured to include a modulator 13 that converts the frequency and outputs the frequency at 3a.

The receiving section 2 includes a demodulator 23 that frequency-converts and demodulates the received signal with a mixer 23a, and a signal processing section 2 that converts the output signal of the demodulator 23 into a demodulator 23.
2 and bandpass filters 25 and 26 for output, a bandpass filter 25 that extracts a switching instruction signal from the output signal of the changeover switch 24 and outputs it to the control unit 61 in the FDMA system, and audio. A band pass filter 26 that extracts and outputs a signal, and a signal processing unit 2 that processes the output signal of the changeover switch 24 in the TDMA system and outputs a switching instruction signal to the control unit 61 and an information signal to the decoder 21.
2. The apparatus includes a decoder 21 that converts the information signal, which is a digital signal, into an audio signal, which is an analog signal.

The synthesizer 7 generates a local oscillation signal for frequency conversion and sends it to the mixers 13a and 23a, and the frequency can be changed by a control signal from the control section 61.

61 follows the switching instruction signal of the master station (base station) 3 4 This is a control unit that controls conversion of new communication methods.

In addition, 62 is 6-curator 6 in the FDMA system.
3, in the TDMA system, it is a communication system changeover switch that switches to the transmission/reception changeover switch 64 and connects to the transmission/reception antenna 3; in the FDMA system, 63 is the bandpass filter 41 on the transmitter side and the .11 on the receiver side.
This is a circulator that prevents the transmission signal from being transmitted to the receiving section side at the connection part with the F-pass filter 51, and 64 is a TDMA
In this method, at the transmission time, the bandpass filter 4 on the transmitting side
2, at other times, the bandpass filter 5 on the receiving side
This is a transmit/receive changeover switch that connects to 2.

Since the band-pass filter 41 on the transmitter side and the band-pass filter 51 on the receiver side are used in the FDMA system, the number of stages is large (5 ~6 steps) are used. On the other hand, the bandpass filter 42 on the transmitter side and the ;:i(pass filter 52 on the receiver side) are used in the TDMA system, so the slope of the attenuation may be small, and the number of stages is small to reduce loss. (2 to 3 steps)
using things.

Next, the operation of the transmitting/receiving apparatus shown in FIG. 4 in each communication method will be explained.

The control unit 61 sends control signals to the changeover switches 14, 24, and 62 using a communication method.

When the communication system is an FDMA system, it is connected to the contact a side of each changeover switch, and when the communication system is a TDMA system, it is switched to the contact side.

In the FDMA system, an audio signal to be transmitted is directly input to the modulator 13, converted to a transmission frequency by the mixer 13a, and transmitted as an uplink from the transmitting/receiving antenna 3 via the bandpass filter 41 and circulator 63. Further, the downlink reception signal received by the transmitting/receiving antenna 3 is transmitted to the circulator 63. Bandpass filter 5
1 to the demodulator, the mixer 13a performs frequency conversion, and the received signal is extracted. As shown in FIG. 5(a), the switching instruction signal is assigned to a frequency band lower than the band of the audio 5 6 signal in the received signal, and is extracted by the band pass filter 25 and sent to the control section 61. be done. -Power 111j Report ζ Sho(', t'75"1
No. 11) is extracted by the bandpass filter 26 and output.

On the other hand, in both TDMA, an audio signal to be transmitted is converted into a digital signal by an encoder 11, and a transmitting side signal processing unit 12 compresses the signal and synchronizes the transmission timing for transmission in a time slot assigned to the transmitter/receiver. and sends it to the modulator 23. The transmission signal whose frequency has been converted by the mixer 23a is passed through the bandpass filter 42.
．． The signal is transmitted as an uplink via the transmitting/receiving switch 64 by the transmitting/receiving antenna 3. Further, the downlink reception signal received by the transmitting/receiving antenna 3 is inputted to the demodulator 23 via the transmitting/receiving changeover switch 64 and the band pass filter 52 .

The reception signal frequency-converted by the mixer 23a is synchronized with the reception timing by the time slot assigned to the transmitting/receiving device by the receiving section side signal processing section 22, and is received as shown in FIG. 5(b). The switching instruction signal inserted at the beginning of the time slot of the signal is extracted and sent to the control section 61, and the information signal that becomes the audio signal is expanded and sent to the decoder 21. The decoder 21 converts an information signal, which is a digital signal, into an audio signal, which is an analog signal, and outputs the converted signal.

(b) Description of communication system of first embodiment An example of the operation of a communication system including a mobile station equipped with a transmitter/receiver according to this embodiment will be described below.

FIG. 6 is a flow diagram regarding control of communication zone change in the communication system according to the present invention. Of these, Figure 6 (
FIG. 6(a) is a flow diagram regarding transmission of a switching instruction from a base station (station m) to a mobile station (slave station), and FIG. FIG. 2 is a flow diagram illustrating the operation of the stacked transmitting/receiving devices according to the present embodiment.

Note that this embodiment assumes voice communication such as telephone communication.

First, the control of communication zone change 7 8 of the base station shown in FIG. 6(a) will be explained. In addition, in this explanation, mobile station C
6(a) is related to base station A. The flow shown in FIG. 6(a) is related to base station A.

(2) Monitor the reception level of the transmitted signal of mobile station C to determine whether it has moved to the communication zone of an adjacent base station.

(2) When it is determined that mobile station C has moved to the communication zone of another base station, it inquires of each adjacent base station about the received signal level of the transmitted signal of mobile station C, and determines which adjacent base station to communicate with.

(2) When determining that the mobile station has moved to base station B, it inquires of base station B about communication information regarding mobile station C.

The communication information is composed of the following information i to iv.

i) Zone switching instruction to notify you that you have entered the communication zone of base station B ii) Communication method of base station B % formula% iv) If base station B uses the TDMA method, allocated time slots for transmission and reception■ The communication information from i to iv inquired of base station B is transmitted to mobile station C as a switching instruction signal.

This switching instruction signal is included in the downlink information signal (voice signal) of both FDMA and TDMA communication systems and is transmitted to the mobile station. As described above, in the FDMA system, as shown in FIG. 5(a), the method for transmitting this switching instruction signal is to allocate a band below the voice band (0.3 to 3 kHz) to the switching instruction signal and simultaneously transmit it. On the other hand, TDM
In method A, the corresponding mobile station (
The switching instruction signal is transmitted by inserting a switching instruction signal at the beginning of the signal of the uplink time slot assigned to mobile station C).

Next, the operation of the transmitter/receiver shown in FIG. 4 installed in the mobile station C which received the switching instruction signal (2) will be explained using FIG. 6).

■ The control unit 61 of the transmitter/receiver receives the downlink information signal (
The switching instruction signal included in the audio signal) is received.

90 ■ According to the communication method of base station B, the control section 61 issues a switching command to the communication signal changeover switch 14 of the transmitting section, the communication signal changeover switch 24 of the reception section, and the communication method changeover switch 62 of the control signal switching means. The communication method of each switch is set to FD according to a switching instruction command.
The communication method is selected by connecting II and 1° of the MA power type to the contact a side of each switch in FIG. 4, and connecting to the contact side in the case of the 1° DMA system.

When the communication system changeover switch 62 is connected to the contact a side, the bandpass filter 41.51 with a large number of stages is connected via the circulator 63, and when the communication system changeover switch 62 is connected to the contact a side, the transmission/reception switching is performed. switch 64
The slope of the frequency characteristic of the attenuation amount is smaller than that of the band-pass filter 41.51 near the boundary between the transmitted signal and the received signal, and the loss is smaller than that of the band-pass filter 41.51 on the transmitter side and the receiver side through the It will be connected to a band pass filter 42.52 with a small number of stages.

(2) The control unit 61 sends a command to the synthesizer 7 to instruct conversion to the allocated frequency. The synthesizer changes the frequency of the local oscillation signal to the mixer 13a on the modulator 13 side and the mixer 23a on the demodulator 23 side.

(2) When the communication method is the FDMA method, the transmitting/receiving device of mobile station C starts communication according to (1) and (2) above.

On the other hand, when using the TDMA system, the control unit 61 of the transmitting/receiving device
The transmitting side signal processing section 12 and the receiving side signal processing section 22
Instructs transmission and reception timing, and
Communication is performed by controlling the transmission/reception changeover switch 64 to be connected to the contact a side at the transmission time and to the contact side at other times.

In addition to voice signals, the base station sends out control signals to control call origination, call reception, etc., and is not used when the communication zone changes during communication as described above, but when the transmitting/receiving device is turned on. When the mobile station is not talking, the mobile station compares the levels of these control signals, receives the control signal with the highest level, and waits. When making or receiving a call, the mobile station The frequency used for the audio signal is determined by the control signal of this base station.
When the communication system and TDMA system are used, the allocated time slot is input to the control section and transmission and reception are started.

(c) Description of other embodiments In the first embodiment, examples of system configurations such as the form of information exchange between base stations and the form of a switching instruction signal issued from a base station to a mobile station are shown. Various modifications are possible according to the main idea. For example, in the first embodiment, the old base station (base station A) that was communicating gave instructions for allocating frequency allocation and time slot allocation for both TDMA transmission and reception. The base station (base station B) may perform this.

Furthermore, the configuration of the transmitting/receiving device can be modified in various ways according to the spirit of the present invention. A second embodiment of the invention is shown in FIG. In the figures, the same parts as those shown in FIGS. 1 and 4 are indicated by the same symbols.

In the second embodiment, switches 66 and 67 are provided on the transmitter side and the receiver side for bandpass filters in which the slope of the attenuation amount of the frequency characteristic differs near the boundary between the transmit signal and the receive signal. Regardless of the communication method, the only connection part with the transmitting/receiving antenna is a circulator 63, and in the first embodiment, a transmitting/receiving switch 64 is used to switch the connection between the transmitting side and the receiving side when performing TDMA transmitting/receiving. does not have. In addition to controlling the switching of the changeover switches 66 and 67, the control unit 65 of the second embodiment also controls the signal processing units 12 and 22 of the transmitter and receiver and the changeover switch 14, as in the first embodiment. 24, controls the synthesizer 7; The system configuration, such as the form of information exchange between base stations and the form of a switching instruction signal sent from a base station to a mobile station, is basically the same as in the first embodiment, so a description thereof will be omitted.

When the second embodiment is compared with the first embodiment shown in (b) above, it is advantageous in that the structure is simple, but since a circulator is also used in the TDMA system, the transmission signal leaks to the receiving section side. There are also drawbacks such as the possibility of

3 4 In short, it is sufficient to adopt a configuration in which connection is switched between band-pass filters with different frequency characteristics on each of the transmitting side and the receiving side depending on the communication method.

〔Effect of the invention〕

As explained above, the transmitting/receiving device according to the present invention has TD
Switch the use of bandpass filters with different frequency characteristics when using the MA method and FDMA method, and when using the TDAM method, use bandpass filters with gentle frequency characteristics in each of the transmitter and receiver sections. The loss is reduced due to the use of

Therefore, according to the present invention, it is possible to support a system in which both TDMA and FDMA communication systems coexist, and
Since the loss in the DMA system is reduced, it is possible to create an economically superior transmitting/receiving device that has a lower signal error rate (and requires less output from the transmitter to achieve the same signal level). realizable.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a frequency attenuation characteristic diagram of a bandpass filter, Fig. 3 is a conceptual diagram of the time division multiple access system (TDMA system), and Fig. 4 is a diagram explaining the concept of the time division multiple access system (TDMA system). Embodiment 1, FIG. 5 is an explanatory diagram of a method of transmitting a switching instruction signal, FIG. 6 is a flow diagram regarding communication zone change according to the first embodiment, FIG. 7 is a second embodiment of the present invention, FIG. The figure is an explanatory diagram of the prior art. 1 : Transmitter, ; Receiver, : Transmission/reception antenna, : Bandpass filter part on the transmitter side, : Ai) band m pass filter part in the receiver side, : First bandpass filter, 5 6 2nd a band-pass filter, a third band-pass filter, a fourth band-pass filter, and a control unit. 7. Rice

Claims (1)

[Claims] 1. A transmission signal loaded on a moving body and output from the transmitter (1) to the transmitter/receiver antenna (3), and a transmitter signal input from the transmitter/receiver antenna (3) to the receiver (2). A transmitting/receiving device that transmits and receives a received signal through a first bandpass filter (41) on a transmitting unit side that extracts frequency components of each signal and a second bandpass filter (51) on a receiving unit side, comprising: It is switchably connected to a first band-pass filter (41) and a second band-pass filter (51), and the slope of the frequency characteristic of the attenuation amount is changed to the first band-pass filter (41) and the second band-pass filter (51), respectively, in the vicinity of the boundary between the transmission frequency and the reception frequency. a third band-pass filter (42) and a fourth band-pass filter (52) smaller than the second band-pass filter (41, 51);
The communication method is determined, and in the frequency division multiple access method, transmission and reception are performed via the first and second band pass filters (41, 51), and in the time division multiple access method, transmission and reception are performed at different times. and the third and fourth
1. A transmitting/receiving device for mobile communication, characterized in that a control unit (6) is provided for controlling transmission and reception through a bandpass filter (42, 52). 2. A first switch (62) that switches and connects the transmitting/receiving antenna (3) to either the first terminal (a) or the second terminal (b), and the first band pass filter ( 41) and the input side of the second bandpass filter (51) are connected to the first switch (62).
) connected to the first terminal (a) of the circulator (63
), and the third bandpass filter (42) during transmission.
When receiving, the input side (52) of the fourth bandpass filter is connected to the output side of the first switch (62).
A second switch (6) is connected to the terminal (b) of
4); and a control unit (61) for determining a communication method and controlling the first switch. 3. The first band-pass filter (41) and the third band-pass filter (42) are provided on the output side of the transmitter (1).
), the second band-pass filter (51) and the fourth band-pass filter ( a second switch (67) that switches and connects one of the output sides of the filter (52); and the first and third bandpass filters (41, 42).
A circulator (2) to which a connection point where the output terminals of the filters are connected to each other, a connection point where the input terminals of the second and fourth bandpass filters (51, 52) are connected to each other, and a transmitting/receiving antenna (3) are connected. 63); and a control unit (65) that determines a communication method and controls the first switch (66) and the second switch (67). Transmitting/receiving device in communication.