JPH07131408A - Transmission/reception circuit - Google Patents

Abstract

PURPOSE:To provide the transmission/reception circuit which adjusts the transmission processing start time to an optimum timing in the communication system where a base station transmits a time as the reference to a terminal and the terminal performs time management based on the received time. CONSTITUTION:Transmission data processing means 9, 12, and 13 which perform the transmission data processing and can adjust the transmission processing start time, a modulating means 11 which modulates transmission data sent from these means and converts the frequency, a switch means which is switched by the signal from a control part 13, a demodulating means 3 which converts the frequency of the reception signal inputted from an antenna 1 or the modulating means to demodulate it, and delay time detecting means 5, 12, and 13 which detect the delay time for frequency conversion and demodulation of the reception signal from the modulating means are provided, and a time adjusting means 13 is provided which uses the delay time detected by delay time detecting means to adjust the transmission processing start time of transmission data processing means.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Industrial Application Conventional Technology (FIGS. 2 to 4) Problem to be Solved by the Invention Means for Solving the Problem (FIGS. 1 and 2) Action (FIGS. 1 and 2) Example (FIGS. 1 to 2) Figure 3) Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception circuit, and in particular, it is applied to a communication terminal of a wireless communication system in which a base station transmits a reference time to a terminal and the terminal manages time based on the received time. And is suitable.

[0003]

2. Description of the Related Art Conventionally, as a wireless communication system in which a base station transmits a reference time to a terminal and the terminal manages time based on the received time, a code division multiple access (CDMA) is used. )) There is a cellular telephone system. A communication terminal in the CDMA cellular telephone system is configured as shown in FIG.

That is, first, on the receiving side, the antenna 1
The received signal obtained in 1 is frequency-converted / demodulated by the frequency converter / demodulator 3 through the duplexer 2 to become a baseband signal. This baseband signal is converted into a digital signal by the analog digital conversion unit (A / D) 4 and despread / decoded by the despreading / decoding unit 5, resulting in a voice code. This voice code is a voice code decoding / voice circuit unit 6
Is converted into voice and is output as received voice from the speaker 7.

On the other hand, on the transmitting side, the voice input from the microphone 8 is encoded into a voice code by the voice code decoding / voice circuit section 6. This voice code is coded / spread by a coding / spreading unit 9, and a digital analog conversion unit (D / A) 10
Is converted into an analog signal. This analog signal is converted into a high frequency signal by the modulation / frequency conversion unit 11 and output from the antenna 1 as a transmission signal.

In the CDMA cellular telephone system, the transmission time of the terminal is defined by the antenna end.
Therefore, the transmission signal must match the reference time at the antenna end. The reference time is sent from a base station (not shown), and the terminal is defined to receive it and operate based on the time at the receiving antenna end.

The time relationship between the base station and the terminal is shown in FIG.
As shown. That is, the reference time X at the base station
Of the signal arrives at the antenna end of the terminal at time X ′ after the elapse of the radio propagation delay time D1. After that, the signal is subjected to signal processing as described above, and the despreading / decoding unit 5 obtains the information of time X instead of the voice code at time X ″, and sets the clock 12 at time X. Frequency conversion at this time / Demodulation unit 3, A / D conversion unit 4, and despreading / decoding unit 5
The delay time due to the circuit is D2.

Therefore, the terminal operates by regarding the time X "as the reference time X. However, the time that the terminal must use as a reference when transmitting is when the time X reaches the antenna end of the terminal. When the transmission signal reaches the end of the antenna at time X ′, the spreading code used for spreading the signal must be at the reference time X.

Assuming that the delay time due to the circuits of the encoding / spreading unit 9, the D / A conversion unit 10 and the modulation / frequency conversion unit 11 is D3, the spreading operation of the encoding / spreading unit 9 is D3 from time X '. It must be done at an early time Y using the spreading code at time X. Since the clock 12 of the terminal itself actually indicates the time X at the time X ″, the spreading operation of the coding / spreading unit 9 is performed by obtaining the time Y as a time earlier by D2 + D3 than that. ing.

In this CDMA cellular telephone terminal, the frequency conversion / demodulation unit 3 and the modulation / frequency conversion unit 1
1, the duplexer 2 is configured as shown in FIG. That is, first, on the receiving side, the received signal (824 to 849 [MHz]) obtained from the antenna 1 is a band pass filter (BPF) 21, a low noise amplifier 22, a BPF.
After passing through 23, a mixer 24
L) 38 is multiplied by the oscillation frequency f _{LO of the} PLL 38 that has passed through the BPF 39. The output of the mixer 24 is the amplifier 2
5. The signal goes to the BPF 26 and becomes an intermediate frequency signal of a constant frequency f _IF . Further, this intermediate frequency signal is level-adjusted by an automatic gain adjustment amplifier (AGC) 27 and divided by an output divider (P / D) 28.

The oscillation frequency f _IF generated by the PLL 35 is multiplied by the signal of the output divider 28 in the mixer 29, passes through the low pass filter (LPF) 30, and becomes an in-phase demodulation output.
It is output to the / D conversion unit 4. The output of the PLL 35 is
The phase is delayed by π / 2 in the π / 2 phase shifter 34, multiplied by the signal of the output divider 28 in the mixer 33, and becomes a quadrature demodulation output through the LPF 32 and is output to the A / D conversion unit 4.
Further, the in-phase / quadrature demodulation output is detected by a detector (det) 31 and used for controlling the AGC amplifier 27, and an output correction signal sent as a transmission output control signal from the control unit 13 by the power combiner 36. They are added to control the variable gain amplifier 52.

On the other hand, on the transmitting side, the in-phase baseband signal input from the D / A converter 10 is passed through the LPF 43 and the mixer 44, where the oscillation frequency f _IF +45 from the PLL 50 is transmitted.
It is modulated at [MHz]. Similarly, the quadrature baseband signal input from the D / A conversion unit 10 passes through the LPF 45 and is mixed by the mixer 46 in the oscillation frequency f _IF +45 from the PLL 50.
The phase is delayed by [pi] / 2 by the [pi] / 2 phase shifter 48 to modulate [MHz].

The outputs of the mixers 44 and 46 are the adder 4
It is added by 7 and passes through the LPF 51 to become a modulated signal. Further, the variable gain amplifier 52 controls the output, and the mixer 53 multiplies the oscillation frequency f _LO from the PLL 38 through the BPF 40. Then, through the BPF 54, the radio frequency signal (8
69 to 894 [MHz]). This is the high power amplifier 5
5, output to the antenna 1 via the isolator 56 and the BPF 57.

The TCXO 42 is a reference clock of the terminal and is controlled by the frequency error signal generated by the despreading / decoding unit 5. In addition, the above-mentioned PLL35, PLL38, PLL
Each of the 50 PLLs is locked in phase with the clock of the TCXO 42.

[0015]

The above-mentioned CD
In a system such as the MA cellular telephone system in which the transmission time is defined at the antenna end, the delay time in the above-mentioned circuits D2 and D3 is set at each part of the circuit in order to comply with the time definition. Is measured in advance when designing / evaluating, and signal processing is performed in advance of that time.

However, there is no problem if the measured delay time is sufficiently accurate as compared with the stipulation of time, but delay time variation is expected to some extent due to variations in parts,
If it exceeds the specified range of time, the terminal 1
You have to measure and adjust the delay time for each unit,
There was a problem that the adjustment man-hour increased when the terminal was mass-produced.

The present invention has been made in consideration of the above points. When the base station transmits the reference time to the terminal and the terminal manages the time based on the received time, the transmission process is started. An attempt is made to propose a transmission / reception circuit that can adjust the time to an optimum timing.

[0018]

In order to solve such a problem, according to the present invention, a base station transmits a reference time to a terminal, and the terminal manages time based on the time. In the transmission / reception circuit of the communication terminal, the transmission data processing means 9, 12, 13 capable of performing transmission data processing and adjusting the transmission processing start time
And a modulation means 11 for modulating and frequency-converting the transmission data sent from the transmission data processing means 9, 12, and 13.
And switch means 41, 4 for switching the transmission output frequency.
9, demodulation means 3 for frequency-converting and demodulating the received signal input from the antenna 1 or the modulation means 11, and the modulation means 1
The delay time detecting means 5, 12, 13 for detecting the delay time when frequency-converting and demodulating the received signal from 1 are provided.

Further, in the present invention, the time for adjusting the transmission processing start time of the transmission data processing means 9, 12, 13 for performing the transmission data processing using the delay time detected by the delay time detecting means 5, 12, 13. The adjusting means 13 is provided.

[0020]

The switching output frequencies of the transmission data modulated and frequency-converted by the modulation means 11 by the switching means 41, 49 are input to the demodulation means 3, and the demodulation means 3 modulates the transmission data.
By performing the frequency conversion and demodulation of the received signal input from 1, the delay time detecting means 5, 12, 13 detects the delay time when the received signal from the modulating means 3 is frequency converted and demodulated. The transmission processing start time can be detected and adjusted without using an additional measuring device.

Further, the time adjustment means 13 adjusts the transmission processing start time of the transmission data processing means 9, 12, 13 for performing the transmission data processing by using the delay times detected by the delay time detection means 5, 12, 13. By doing so, the transmission processing start time can be adjusted to an optimum timing.

[0022]

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 in which parts corresponding to those in FIG.
Shows the overall configuration of the duplexer 2, frequency conversion / demodulation unit 3 and modulation / frequency conversion unit 11 in which the present invention is applied to the CDMA cellular telephone terminal shown in FIG.
In addition to the above configuration, 3 is switched by a signal from the control unit 13.
Two switches 37, 41 and 49 are added.

That is, by switching the switch 41, the TCXO 42 is controlled so as to oscillate at a fixed frequency and is not controlled by the frequency error signal. Further, the switch 37 switches so that the gain of the variable gain amplifier 52 is switched so that a signal of a small level that can be received by the receiving side is output. Further, when the switch 49 is switched, the carrier wave to be modulated is switched from the frequency f _IF +45 [MHz] to f _IF .

By these operations, the frequency of the modulated signal becomes equal to the demodulation frequency on the receiving side, the gain of the variable gain amplifier 52 is limited, and the attenuation of the frequency outside the band of the BPF 57 is used. By absorbing the gap between the transmission level and the reception level, a loop from the transmission circuit to the reception circuit is configured. At this time BPF
The difference between the delay time within the 57 band and the delay time outside the 57 band is sufficiently small and can be ignored.

In this way, a loop from the transmitting side to the receiving side is constructed, and in the CDMA cellular telephone terminal shown in FIG. 2, the input data of the encoding / spreading unit 9 is first set to "0" by the control unit 13. , Output only spread code. The modulation / frequency conversion unit 11 also switches the internal switches 37, 41 and 49 by the control unit 13 so that the transmission output is returned to the frequency conversion / demodulation unit 3 through the duplexer 2. At this time, the frequency conversion / demodulation unit 3, the A / D conversion unit 4, and the despreading / decoding unit 5 operate normally.

In practice, the time at the beginning of the despreading code when the despreading / decoding unit 5 obtains "0" data is
The signal from the decoding unit 5 and the clock 12 are obtained and compared with the time at the beginning of the spreading code of the coding / spreading unit 9, so that the coding / spreading unit 9 passes through the duplexer 2 to the despreading / decoding unit 5. It is designed to find the delay time it took to arrive. Since this delay time is the delay time D2 + D3 described above with reference to FIG. 3, the adjustment ends by setting the spreading operation start time of the coding / spreading unit 9 to a time earlier by the delay time D2 + D3. The control unit 13 also calculates the delay time and sets the spreading operation start time.

According to the above configuration, a loop is formed from the transmission side to the reception side, the input data of the coding / spreading unit 9 is set to "0" by the control unit 13 and only the spreading code is output, and this transmission is performed. The output is returned to the frequency conversion / demodulation unit 3, and the time of the beginning of the despreading code when the despreading / decoding unit 5 obtains “0” data is calculated from the signal from the despreading / decoding unit 5 and the clock 12. By obtaining the delay time from the coding / spreading unit 9 to the despreading / decoding unit 5 by comparing with the time at the beginning of the spreading code of the coding / spreading unit 9, the additional time can be obtained. It is possible to detect and adjust the transmission processing start time without using a different measuring device.

In this way, the adjustment of the spreading operation start time of the coding / spreading section 9 can be automated by adding a few circuits and slightly changing the control method, and the number of adjustment steps during mass production can be greatly reduced. . Furthermore, since the design can be performed without worrying about the adjustment man-hours, it is possible to reduce the cost of the circuit parts, that is, to use the parts having a large tolerance.

In the above-described embodiment, the upper harmonic wave is used as the frequency of the carrier wave to be modulated in order to form a loop from the transmitting side to the receiving side. However, instead of this, the lower harmonic wave is used. Even if the above is used, the same effect as that of the above-described embodiment can be obtained.

In the above embodiment, the present invention is C
The case where the present invention is applied to the DMA type cellular telephone terminal has been described, but the present invention is not limited to this, and the base station transmits the reference time to the terminal, and the terminal performs time management based on the received time. It is suitable for application to communication terminals of various wireless communication systems.

[0032]

As described above, according to the present invention, when a base station transmits a reference time to a terminal and the terminal manages time based on the received time, an additional measuring device is provided. It is possible to realize a transmission / reception circuit that can adjust the transmission processing start time to an optimum timing without using it.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a duplexer, a frequency conversion / demodulation unit, and a modulation / frequency conversion unit of a CDMA cellular telephone terminal to which a transmission / reception circuit according to the present invention is applied.

FIG. 2 is a block diagram showing a configuration of a CDMA cellular telephone terminal.

FIG. 3 is a timing chart showing a time relationship between a base station and a terminal in a CDMA cellular telephone system.

FIG. 4 is a block diagram showing a configuration of a duplexer, a frequency conversion / demodulation unit, and a modulation / frequency conversion unit of a conventional CDMA cellular telephone terminal.

[Explanation of symbols]

1 ... Antenna, 2 ... Deplexer, 3 ... Frequency conversion / demodulation section, 4 ... Analog / digital conversion section, 5 ...
... Despreading / decoding unit, 6 ... Voice codec / voice circuit, 7 ...
... speaker, 8 ... microphone, 9 ... encoding / spreading unit, 1
0 ... Digital analog converter, 11 ... Modulation / frequency converter, 12 ... Clock, 13 ... Controller.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location H04L 7/00 B 7741-5K H04J 13/00 G

Claims (2)

[Claims] 1. A transmission / reception circuit in a communication terminal of a wireless communication system in which a base station transmits a reference time to a terminal, and the terminal manages time based on the time. At the same time, transmission data processing means that can adjust the transmission processing start time, modulation means that modulates the frequency of the transmission data sent from the transmission data processing means, and frequency conversion, switch means that switches the transmission output frequency, antenna or the above It is characterized by comprising demodulation means for frequency-converting and demodulating the received signal input from the modulating means, and delay time detecting means for detecting a delay time when frequency-converting and demodulating the received signal from the modulating means. Transmitter / receiver circuit. 2. The time adjusting means for adjusting the transmission processing start time of the transmission data processing means for performing the transmission data processing by using the delay time detected by the delay time detecting means. The transmission / reception circuit according to Item 1.