JP2001186204A - Digital radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide digital radio equipment which can correct required frame timing even in the case of using an antenna switch and in which the timing is not greatly shifted even when long-time transmission such as data transmission is performed. SOLUTION: This equipment has a receiver provided with a timing reproducing means for reproducing a reproduction symbol clock signal, a frame reproducing means reproducing a received frame signal, a reference oscillating means for generating a reference symbol clock signal and a reference clock signal, and a timing error detecting/correcting means for generating a transmission frame signal with corrected timing with a received signal from the reproduction symbol clock signal, the reference symbol clock signal, the reference clock signal and the received frame signal, a transmitter provided with a modulating means that constructs the transmission data frame of an information signal on the basis of the transmission frame signal and outputs a transmission signal obtained by modulating a carrier signal, and the antenna switch switching the received signal and the transmission signal. The equipment detects the error of the reference symbol clock signal when the received signal is received and corrects the timing of the transmission frame signal when the transmission signal is transmitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital radio having improved performance so as to generate a transmission frame signal that follows the accuracy of a carrier frequency, a symbol timing, and a frame timing included in a reception signal and transmit the transmission signal. It is.

[0002]

2. Description of the Related Art Digital mobile communication systems are frequently used as wireless communication means. However, the digital wireless equipment used has been significantly reduced in size and multifunctionality with the development of technology, and the usability has been improved. There is an increasing number of users of mobile communication systems, i.e. mobile radio stations. In this mobile communication system, a multiple access technology is used to enable a limited number of communication lines to be efficiently and commonly used through a common repeater or a relay base station. ing. As a main multiple access technique used in mobile communication systems, a specific frequency channel is assigned to each mobile radio station.
DMA (Frequency Division Multiple Access), a TDMA scheme (Time) in which a specific frequency channel is allocated to a plurality of mobile radio stations, and a specific time slot in a time frame is allocated to each mobile radio station. Division Multiple Access (Time Division Multiple Access system), a CDMA system (Code Division Multiple Acc) in which a specific code is assigned to a mobile radio station and the used channel is separated by comparing the code with its own code.
ess: code division multiple access system).

FIG. 3 shows a mobile communication system using an FDMA system, which is one of the multiple access systems described above.
It is a figure showing the concept of a wave duplex system. In a mobile communication system using the FDMA scheme, information signals such as voice signals and data signals transmitted and received between a radio base station 31 and a plurality of mobile radio stations (terminal stations) 32 and 33 are transmitted on a symbol-by-symbol basis. The mobile radio station 33 receives a transmission signal of the carrier frequency F1 from the radio base station 31 while the mobile radio station 33 is transmitting at the carrier frequency f1. In this case (see FIG. 3A), the transmission frame and the reception frame are transmitted and received at the same time, and transmission and reception are not temporally divided (see FIG. 3B). In addition, PDC (Personal Digital Cellula) which is one of the digital cellular phones
In the TDMA system used in (r), etc., transmission and reception are temporally divided and transmitted in a frame unit composed of a plurality of symbols obtained by dividing an information signal at a predetermined time.
Receiving.

In general, in a mobile communication system, in order to reduce the burden on a mobile radio station, a radio base station is provided with a carrier oscillator having high frequency stability and high accuracy, thereby achieving frequency stability. In general, a mobile radio station transmits a carrier signal and a symbol timing following a received signal. As described above, in order to receive the transmission signal from the radio base station and follow the received signal, in the mobile communication system of the FDMA scheme, the mobile radio station is transmitting during the synchronization for maintaining the synchronization with the radio base station. It is necessary to receive a transmission signal from a wireless base station. Therefore, for example, the mobile radio station 33 always receives the transmission signal of the carrier frequency F1 transmitted from the radio base station 31, reproduces the symbol timing and the frame timing, and extracts the transmitted information signal. When the mobile radio station 33 transmits a required transmission signal to the radio base station 31, the radio base station 3
Using the carrier frequency f1 paired with the carrier frequency F1 transmitted from No. 1, transmission is performed at a timing according to the reproduced frame timing.

A conventional digital radio used as a mobile radio station will be described with reference to a block diagram shown in FIG. FIG. 4 shows only those components necessary for explaining the conventional digital radio, and omits other components. The transmission signal of the carrier frequency F1 which is constantly transmitted from the wireless base station to each digital wireless device is received by the antenna 41 of the digital wireless device to become a received signal, and is received via the duplexer 49 of the antenna. Is input to The receiving high-frequency unit 42 is connected to the duplexer 4 by the antenna 41.
After removing unnecessary components from the reception signal input via the input signal 9, high-frequency amplification is performed to a required signal level, frequency conversion and amplification to an intermediate frequency signal are performed, and the intermediate frequency signal is transmitted to the reception detector 43 and symbolized. To the timing reproduction unit 45 of the above. The timing recovery section 45 converts the intermediate frequency signal input from the reception high-frequency section 42 into a symbol timing signal which is recovered based on a reference signal of a required frequency separately input from the reference oscillator 46.
3 and the frame reproducing unit 44.

The reception detecting section 43 detects the intermediate frequency signal input from the receiving high frequency section 42 in accordance with the symbol timing signal reproduced by the timing reproducing section 45,
The detection signal is output to the frame reproducing unit 44. The frame reproduction unit 44 detects a synchronization word (SW) portion, which is predetermined fixed data, from the detection signal input from the reception detection unit 43 according to the symbol timing signal reproduced by the timing reproduction unit 45. The frame data is extracted and the frame timing signal is reproduced. The frame data is output to another circuit as reproduced data, and the frame timing signal is output to the modulator 48 for use as the transmission frame timing of the mobile radio station. . The modulating unit 48 includes the frame reproducing unit 44
A transmission data frame is formed on the basis of a frame timing signal input from the base station, a carrier signal having a frequency f1 is modulated with an information signal such as a voice signal and a data signal to be transmitted, and a transmission output signal having a carrier frequency f1 is shared. Output to the antenna 41 via 49. The antenna 41 transmits a transmission output signal of the carrier frequency f1 output from the modulator 48 via the duplexer 49 to the radio base station.

[0007]

As described above, a digital radio device according to the prior art requires a duplexer for an antenna because it is necessary to simultaneously perform transmission and reception. However, in general, the lower the carrier frequency of the transmission signal passing through the duplexer, the larger the duplexer becomes, which is disadvantageous in terms of miniaturization, and
Compared to an antenna switch that switches between a transmission signal and a reception signal, it is expensive and expensive and disadvantageous in terms of cost reduction. If transmission and reception are not performed at the same time, reception cannot be performed during transmission, and the transmission operates with the oscillation frequency signal of the reference oscillator of the local station. ), The frame timing shifts over time due to the frequency difference between the oscillation frequency signal and the reference wireless base station symbol transmission clock frequency signal. There is a disadvantage that the synchronization must be re-established when returning from transmission to reception. The present invention, in order to solve the above problems, it is possible to correct the required frame timing at the time of transmission even using an antenna switch,
It is an object of the present invention to provide a digital wireless device that can be downsized and reduced in price without a large shift in timing even when data is transmitted for a long time such as data transmission.

[0008]

In order to achieve the above object, a digital radio according to the present invention comprises a timing reproducing means for reproducing a reproduced symbol clock signal of a received signal, and a frame for reproducing a received frame signal of the received signal. Reproducing means; reference oscillating means for generating a reference symbol clock signal and a reference clock signal; and timing of a reception signal from the reproduction symbol clock signal, the reference symbol clock signal, the reference clock signal, and the reception frame signal. A receiver including timing error detection / correction means for generating a corrected transmission frame signal, and a modulation for forming a transmission data frame of an information signal based on the transmission frame signal and outputting a transmission signal obtained by modulating a carrier signal A transmitter having a means, a reception signal input to the receiver, and an output from the transmitter. And an antenna switch for switching the transmission signal to detect an error of the reference symbol clock signal upon reception of the received signal, and corrects the timing of the transmission frame signal at the time of transmission of the transmission signal.

More specifically, in the digital radio according to the present invention, the timing error detecting / correcting means includes a first counter for counting a reproduced symbol clock signal, a second counter for counting a reference symbol clock signal,
A comparison control unit that controls start and stop of counting by the first counter and the second counter;
And a frequency error detection unit for obtaining a frequency error from a difference between count values output from the second counter and the second counter, and dividing the frequency of the reference clock signal based on the frequency error signal input from the frequency error detection unit. A frequency division ratio control unit that outputs a frequency division ratio control signal to be controlled, a frequency divider that divides the reference clock signal based on the frequency division ratio control signal, and counts a received frame signal based on the frequency-divided clock signal. A frame counter that outputs a transmission frame signal, counts the reproduced symbol clock signal and the reference symbol clock signal for a predetermined time, and obtains a frequency error from a difference between the count values. In the digital radio of the present invention, a receiver generates a reference clock signal, divides the reference clock signal to generate a reference symbol clock signal, and outputs the reference clock signal and the reference symbol clock signal. A reference oscillation means is provided, and the timing error detection / correction means adjusts the timing of the transmission frame signal generated by controlling the frequency division ratio of the reference clock signal based on the frequency error signal.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a digital radio according to the present invention will be described with reference to FIGS. FIG.
2 shows a block diagram of a digital radio according to the present invention, and FIG. 2 shows a detailed block diagram of a timing error detection / correction unit used in the digital radio shown in FIG. FIG. 1 shows only those components necessary for the description of the digital radio according to the present invention, and omits other components. In FIG. 1, 1
Is an antenna that receives a transmission signal of the carrier frequency F1 transmitted from the radio base station or transmits a transmission signal of the carrier frequency f1 to the radio base station.
The antenna switch 2 for switching the received signal of the carrier frequency F1 output to the receiver or the transmission signal of the carrier frequency f1 output from the transmitter to the antenna 1 is switched by the antenna switch 9 to the input of the carrier frequency f1. A receiving high-frequency section 6 for removing unnecessary components, high-frequency amplification to a required signal level, frequency conversion to an intermediate frequency signal, and the like for the received signal; 6 is a reference clock signal and a reference symbol clock signal generated based on the reference clock signal 5 is a timing reproducing unit that reproduces a reproduced symbol clock signal from the intermediate frequency signal based on the reference clock signal, and 3 detects the intermediate frequency signal according to the reproduced symbol clock signal and outputs a detected signal. The receiving detector 4 converts the detected signal into a reproduced symbol clock signal. A frame reproducing unit 7 for extracting frame data and reproducing a frame signal, detects a frequency error from the reproduced symbol clock signal and the reference symbol clock signal, divides the frequency of the reference clock signal based on the frequency error, and A timing error detection / correction unit that counts the received frame signal with the clock signal and outputs the transmitted frame signal; 3 shows a modulator of a transmitter that modulates a carrier signal of frequency f1. The timing error detection / correction unit 7 includes a counter 7-1, a counter 7-2, a comparison control unit 7-3, a frequency error detection unit 7-4, and a frequency division ratio control unit 7.
-5, an N / M frequency divider 7-6, and a frame counter 7-7.

Hereinafter, a digital radio according to the present invention will be described.
A description will be given of a two-wave simplex method as an example. First, the operation when a transmission signal from a wireless base station is received will be described. In the receiving state, the contact point c and the contact point b of the antenna switch 9 are connected, and the antenna 1 is connected to the receiver. The state has been switched to The transmission signal of the carrier frequency F1 which is constantly transmitted from the wireless base station to each digital wireless device (mobile wireless station) is received by the antenna 1 of the digital wireless device and becomes a received signal, and is transmitted from the contact c of the antenna switch 9 The signal is input to the reception high frequency unit 2 through the contact b. The reception high-frequency unit 2 removes unnecessary components from the reception signal input from the antenna 1 via the antenna switch 2, performs high-frequency amplification to a required signal level, and further performs frequency conversion and amplification to an intermediate frequency signal. The frequency-converted intermediate frequency signal is output to the reception detection unit 3 and the symbol timing recovery unit 5. The timing reproduction unit 5 reproduces a reproduced symbol clock signal from the intermediate frequency signal input from the reception high frequency unit 2 based on a reference symbol clock signal separately input from the reference oscillator 6, and converts the reproduced reproduction symbol clock signal into
The signals are output to the reception detection unit 3, the frame reproduction unit 4, and the timing error detection / correction unit 7.

The reception detection unit 3 detects the intermediate frequency signal input from the reception high-frequency unit 2 according to a reproduction symbol clock signal separately input from the timing reproduction unit 5, and outputs the detection signal to the frame reproduction unit 4. I do. The frame reproducing unit 4 detects a synchronous word (SW) portion, which is fixed data predetermined according to a reproduced symbol clock signal input from the timing reproducing unit 5, separately from the detection signal input from the reception detecting unit 3. Then, the frame data is extracted and the frame signal is reproduced. The frame data is output to another circuit as the reproduction data, and the reproduced received frame signal is output to the timing error detection / correction unit 7.

Here, the timing error detection / output shown in FIG.
The operation of the timing error detection / correction unit will be described with reference to a detailed block diagram of the correction unit 7. The timing error detection / correction unit 7 includes a counter 7-1 for counting a reproduced symbol clock signal input from the timing recovery unit 5, a counter 7-2 for counting a reference symbol clock signal input from the reference oscillator 6, and a counter 7 -1 and a comparison control section 7-3 for controlling the start and stop of the count of the counter 7-2, and a frequency error detection section for obtaining a frequency error signal from a difference between count values output from the counter 7-1 and the counter 7-2. 7-4, Reference oscillator 6 based on frequency error signal
A frequency division ratio control unit 7-5 for outputting a frequency division ratio control signal for controlling the frequency division of the reference clock signal input thereto, and dividing the reference clock signal input from the reference oscillator 6 based on the frequency division ratio control signal An N / M frequency divider 7-6, and a frame counter 7-7 which counts a received frame signal input from the frame reproducing unit 4 based on a clock signal obtained by dividing the reference clock signal and outputs a transmitted frame signal. I have.

The counter 7-1 counts the reproduction symbol clock signal input from the timing reproduction unit 5 for a predetermined period in accordance with the control signal input from the comparison control unit 7-3, and outputs the count value to the frequency error detection unit 7. Output to -4.
The counter 7-2 counts the reference symbol clock signal input from the reference oscillator 6 for a predetermined period according to the control signal input from the comparison control unit 7-3, and outputs the count value to the frequency error detection unit 7-4. I do. Frequency error detector 7
-4 finds a difference between the count value of the reproduced symbol clock signal input from the counter 7-1 and the count value of the reference symbol clock signal input from the counter 7-2. Here, the difference between the count values of the symbol clock signal in a predetermined period is the symbol rate AHz,
Assuming that counting is performed for X seconds with reference to the reference clock signal of the reference oscillator 6 and the K count is different, K /
AX frequency error. For example, A = 8000 Hz,
If X = 200 seconds, ± 0.62 per ± 1 count
There will be a 5 ppm frequency error. The frequency error detector 7-4 stores the detected frequency error.

Next, the operation when a transmission signal is transmitted from the digital radio will be described. In the transmission state, the contact c and the contact a of the antenna switch 9 are connected and the antenna 1 transmits the signal. The state has been switched to the connection with the device. In the case of transition to the transmission state, the frame counter 7-7 is inputted from the N / M frequency divider 7-6 with reference to the phase of the received frame signal reproduced in the reception state inputted from the frame reproducing section 4. It counts with a clock signal, generates a transmission frame signal, and outputs it to the modulator 8 of the transmitter. The frequency division ratio controller 7-5 controls the frequency division ratio of the N / M frequency divider 7-6 based on the frequency error in the reception state stored in the frequency error detector 7-4. . The N / M frequency divider 7-6 receives a reference clock signal N times as large as the reference symbol clock signal as an input signal, and normally generates a frequency division ratio based on a control signal input from the frequency division ratio controller 7-5. When operating at N, when correcting the frequency division ratio, M is set to N-
Change to 1 or N + 1. The division ratio switching interval is X / K
Every N seconds. When the count value output from the counter 7-1 is smaller than the count value output from the counter 7-2, the division ratio is set to M = N-1, and when the count value is larger, the division ratio is set to M. = N + 1. By performing the above operation, the digital wireless device can follow the reference frame of the wireless base station even during transmission.

When the dividing ratio is used as M = N-1, the symbol clock timing and the frame period both become shorter by 1 / AM second, and the frame timing is corrected. When the frequency division ratio is used as M = N + 1, both the symbol clock timing and the frame period become longer by 1 / AM second, and the frame timing is corrected. Thus, based on the frame timing of the transmission frame signal output from the timing error detection / correction unit 7, the modulation unit 8 of the wireless device configures a transmission data frame of the information signal to be transmitted, Modulates the signal. The transmission signal of the carrier frequency f1 output from the modulator 8 is supplied to the antenna 1 from the contact a to the contact c of the antenna switch 9 and transmitted to the radio base station. As described above, the digital radio of the present invention can perform required frame timing correction at the time of transmission even when an antenna switch is used, so that the digital radio can be reduced in size and cost. Since the timing of the wireless base station can be maintained even during transmission, the wireless base station can be used as a digital wireless device of a two-wave simplex system following the wireless base station.

[0017]

According to the present invention, the required frame timing can be corrected at the time of transmission even if an antenna switch is used, and the timing is greatly shifted even when a long time transmission such as data transmission is performed. It is possible to provide a digital wireless device that can be reduced in size and cost without any problem.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a digital wireless device according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a timing error detection / correction unit included in the digital wireless device of the present invention.

FIG. 3 is a diagram illustrating a conventional two-wave duplex method.

FIG. 4 is a block diagram showing a configuration of a conventional digital radio.

[Explanation of symbols]

 1, 41 antenna, 2, 42 reception high frequency section, 3, 43 reception detection section, 4, 44 frame reproduction section, 5, 45 timing reproduction section, 6, 46 reference oscillator, 7 timing error detection / correction section, 7-1 , 7-2 counter, 7-3 comparison control section, 7-4 frequency error detection section, 7-5 frequency division ratio control section, 7-6 N / M frequency divider, 7-7 frame counter, 8, 48 modulation Part, 9 antenna switch, 31 radio base station, 32, 33 mobile radio station, 49 duplexer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // H04L 7/02 H04L 7/02 Z F-term (Reference) 5K004 AA01 BA02 5K011 BA10 DA08 DA12 DA15 DA21 DA28 EA05 GA04 JA01 JA10 KA13 5K022 AA10 AA11 AA30 5K047 AA01 AA05 BB01 CC01 EE00 GG11 HH01 JJ08 MM03 MM12 MM55 MM56 5K067 BB04 CC04 CC10 DD45 EE02 EE10 EE16 EE32 KK01

Claims (4)

[Claims] An oscillating means for generating a symbol timing; a timing reproducing means for reproducing a reproduced symbol timing from a received signal; an error detecting means for detecting a frequency error between the reproduced symbol timing and the symbol timing; Means for correcting frame timing during transmission based on an error, and correcting the frame timing appropriately during transmission. 2. A timing reproducing means for reproducing a reproduced symbol clock signal of a received signal, a frame reproducing means for reproducing a received frame signal of the received signal, and a reference oscillating means for generating a reference symbol clock signal and a reference clock signal. A receiver comprising: a timing error detection / correction unit that generates a transmission frame signal in which the timing of a reception signal is corrected from the reproduction symbol clock signal, the reference symbol clock signal, the reference clock signal, and the reception frame signal. A transmitter comprising modulation means for forming a transmission data frame of an information signal based on the transmission frame signal and outputting a transmission signal obtained by modulating a carrier signal; a reception signal input to the receiver and the transmission And an antenna switch for switching between a transmission signal output from the device and a reception signal. Digital radio for detecting an error of the reference symbol clock signal, and correcting the timing of the transmission frame signal at the time of transmission of the transmission signal. 3. The digital radio according to claim 1, wherein the timing error detection / correction means includes a first counter for counting a reproduced symbol clock signal, a second counter for counting a reference symbol clock signal, and A frequency error is determined from a comparison control unit that controls start and stop of counting by the first counter and the second counter, and a difference between respective count values output from the first counter and the second counter. A frequency error detection unit, a frequency division ratio control unit that outputs a frequency division ratio control signal for controlling frequency division of the reference clock signal based on the frequency error signal input from the frequency error detection unit, and the frequency division ratio control signal A frequency divider for dividing the reference clock signal based on the received clock signal; A frame counter for outputting a frame signal, said recovered symbol clock signal and the reference symbol clock signal counts a predetermined time, digital radios and obtaining a frequency error from the difference of the count value. 4. The digital radio according to claim 1, wherein the receiver generates a reference clock signal, divides the reference clock signal to generate a reference symbol clock signal, and generates the reference clock signal. And a reference oscillation means for outputting a reference symbol clock signal. The timing error detection / correction means adjusts the timing of the transmission frame signal generated by controlling the frequency division ratio of the reference clock signal based on the frequency error signal. A digital radio device characterized by the above-mentioned.