JPH0530056A - Tdma receiver - Google Patents

Abstract

PURPOSE:To improve the quality of data by providing a selector selecting equalizer output data corresponding to the maximum correlation value. CONSTITUTION:A TDMA (Time Division Multiple Access) controller 140 separates a reception TDMA signal 125 selecting a user slot decided in advance from one among the received time slots in multiple. In short, the specific user message is selected from other user messages. Correlators 150, 160, and 170 with different data input timing after synchronizing the reception slot and correlators 210, 220, 230 performing the correlation calculation on the equalizer output such as sync words to be used for the channel estimation are provided. A selector 250 selects the equalizer of input timing with the maximum correlation calculation output of the equalizer output and imparting output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to TD in wireless communication.
The present invention relates to an MA receiving device.

[0002]

2. Description of the Related Art FIG. 3 shows a united state, for example.
s Patent 4,852,090 (Jul. 2
5 is a block diagram showing a conventional equalizer in the receiving station shown in FIG. In the figure, 300 is TDMA
Receiving station, 110 is an antenna, 120 is a receiver, 1
30 is a data buffer, 140 is a TDMA controller, 150 is an equalizer, and 115, 125, 135,
141, 142, 145, and 255 are signal lines.

Next, the operation will be described. In FIG. 3, first, the TDMA signal is received by the antenna 110,
The signal is supplied to the receiver 120 via the signal line 115. The receiver 120 receives the RF carrier and demodulates it by a method suitable for the system. Received TDMA at 125
The signal is supplied to the data buffer 130 and the TDMA controller 140. The data buffer 130 is utilized to store at least a particular user message according to the control signal 141 for further processing.

Generally, it is common in systems where only one (or some of many) timeslots are received by a particular receiving station. If the adaptive equalization process is performed in non-real time, that is, in the time slot next to the time slot of a specific user, any specific receiving station performs low data rate signal processing. be able to. The data buffer 130 is a storage device including a shift register and a RAM.
If the "non-real-time processing" is not performed, the received TDM
The data buffer 130 may be deleted so that the A signal 125 is directly sent to the equalizer 150.

Since the TDMA controller 140 selects a predetermined user slot from one (or some of many) of the received time slots,
The received TDMA signal 125 is demultiplexed. That is, a specific user message is selected from the user messages. TD of the particular user trying to utilize on signal 145
TDMA sync1 corresponding to MA sync1 signal
-By receiving N words, the TDMA controller 14
0 outputs clock 1 to the signal line 141 and clock 2 to the signal 142. Clock 1 141 receives TDMA during a time slot suitable for data buffer 130.
At least the sync word and user message portions of the signal are clocked in. A clock 2 142 is a clock input for data input from the data buffer 130 to the equalizer 150. User data (user message) is retrieved at 255.

The equalizer 150 has a 135 (or receive TD
Equalize the time delay spread of the stored user message in the MA signal 125). Then, a specific user data word (user message) excluding the sync word at the beginning is output at 255. Here, the equalizer sync word portion of a particular time slot is used by the equalizer to compensate for the multipath characteristics of the channel. The equalizer uses TDMA signals 141 and 142 for accurate channel estimation and equalization. The equalizer operates adaptively only while the TDMA controller 140 detects the presence of the desired equalizer syncword or while buffer data is being read into the equalizer.

In this way, the equalizer 150 compensates for the distortion due to intersymbol interference and Rayleigh fading of the received signal by measuring the continuous multipath characteristics using the information obtained from the equalizer sync word. Then, the received signal is equalized according to these characteristics.

For the sake of caution, the synchronization establishment will be mentioned. Generally, various methods for establishing synchronization of a frame composed of several time slots are outside the scope of the present application, but various methods have been considered. JP-A-2-17233
2 proposes an idea of referring to a PN correlation signal to select an optimum equalization characteristic from a plurality of equalizers and establishing synchronization. However, this is one method for establishing frame synchronization in the present application.
A sync signal 145 is obtained. In such a case, the method of taking a correlation is common. Although obtained in another way herein, the subject matter of this application is not related to frame synchronization.

[0009]

Since the conventional TDMA receiver is configured as described above, if the data in the received time slot is subjected to multipath propagation distortion and intersymbol interference, the received time is The timing detected by correlating with the sync word for synchronizing in the slot,
Since the timings of the channel estimation of the equalizer and the adaptive equalization process (the beginning of each sync word and the beginning of the user message are the same) do not match, equalization may not be performed correctly. There was a problem called.

The present invention has been made to solve the above problems, and an object of the present invention is to perform good data transmission even when there are multiple wave propagation distortion and intersymbol interference. Note that, as described above, the present application is not an apparatus for establishing frame synchronization. This TDMA receiver does not consider cases where synchronization cannot be achieved due to sync words due to multipath propagation distortion and intersymbol interference. When synchronization is achieved in some way, it is intended for those that give better timing to the equalizer even if the timing deviates by several symbols from the timing of normal channel estimation and adaptive equalization processing from the synchronization timing. .. TDMA
For synchronization in communication, see, for example, Yamamoto and Kato “T”.
DMA Communication "The Institute of Electronics, Information and Communication Engineers (1989) p34-5
5 are mentioned.

[0011]

TDMA according to the present invention
The receiving device, after the synchronization of the receiving slot is established, a plurality of equalizers having different data input timings, a correlator for performing a correlation operation on the equalizer output such as a sync word used for the channel estimation, and the correlation value A selector is provided to select the output data of the equalizer corresponding to the largest one.

[0012]

In the TDMA receiver according to the present invention, after the synchronization of the receiving slots is established, the equalizer having the input timing at which the correlation operation output of the equalizer output is maximum is selected and the output is given.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In TDMA communication, detection of the leading symbol of a user message and the leading symbol of a training sequence used by an equalizer is stored in advance in the receiver together with the sync word in each slot received by the receiver. This is done by taking a correlation with the sequence that is set. Due to the presence of multipath propagation distortion in the transmission path, the received syncword portion causes waveform distortion due to the delayed wave. The equalizer operates so as to remove this waveform distortion, but at the beginning of the operation of the equalizer, the unknown transmission path is estimated by the training sequence. At this time, a sync word is usually used. By the way, since the correlation in the sync word determines these timings, a gate called an aperture is used to protect it so that noise does not cause correlation. The position where the correlation is established differs depending on the level relationship with the wave. (Or, due to delay distortion, the correlation result does not exceed the threshold value, and a pseudo correlation pulse is generated at the same position as the previous slot.) At this time, the equalizer equalizes because the training start timing is shifted. Bit error rate characteristics are deteriorated due to divergence of the operation of the measuring device and a large estimation error.

The present invention is intended to remedy such characteristic deterioration. By using a plurality of equalizers having the same characteristics and changing the reception signal input timing, the equalizers in the slots are equalized. Correlation between the training parts of the equalizer outputs and the sync word stored in advance in the receiver so that the optimization can be performed optimally, and by selecting the one with the maximum correlation among them, the above characteristic deterioration Is to be relieved. The correlation calculation of the training portion is continuously performed and corrected every time it is estimated that there is a change.

Based on the above general description, one embodiment of the present invention will be specifically described below with reference to the drawings. In FIG. 1, 100 is a TDMA receiving station, 110 is an antenna, 120 is a receiver, and 130 is a data buffer 1, 14.
Reference numeral 0 is a TDMA controller, and 150 is an equalizer 1.
The new components are: 160 is the equalizer 1
An equalizer 2, 170 for delaying only one symbol from 150 and inputting data, is an equalizer 3 for delaying one symbol from 160 and inputting data.
180, 190, and 200 are data buffers 2,
3 and 4, 210, 220 and 230 are correlators 1, 2, 3 and 240 are maximum value detectors, 250 is a selector, 115, 125, 135, 141, 142 and 14 respectively.
3, 144, 145, 155, 165, 175, 18
5, 195, 205, 215, 225, 235, 24
5, 255 are signal lines.

Next, the operation will be described. Figure 1 TDM
In the A receiving station 100, the TDMA signal is first received by the antenna 110 and supplied to the receiver 120 via the signal line 115. The receiver 120 receives the RF carrier and demodulates it by a method suitable for the system. The received TDMA signal at 115 is provided to data buffer 1 130 and TDMA controller 140. The data buffer 130 controls the control signal 14 for further processing.
2 is used to store at least a particular user message.

Generally, only one (or some of the many) timeslots are received by a particular receiving station. If the adaptive equalization process is processed in non-real time, that is, in the time slot next to the time slot of a specific user, any specific receiving station performs low data rate signal processing. be able to. The data buffer 130 is a storage device including a shift register, a RAM, and the like. If this "non-real time processing" is not performed, the data buffer 130 may be deleted so that the received TDMA signal 125 is directly sent to the equalizers 150, 160 and 170. The TDMA controller 140 demultiplexes the received TDMA signal 125 to select a predetermined user slot from one of the received time slots (or some of many). That is, a specific user message is selected from other user messages.

The TDMA sync corresponding to the TDMA sync signal of the specific user who intends to use the signal 145.
Upon receiving the nc1-N words, the TDMA controller 140 outputs clock 1 for signal 141, clock 2 for signal 142, clock 3 for signal 143, and clock 4 for signal 144. Clock 1 141 receives T during the time slot suitable for data buffer 130.
At least the sync word and the user message portion of the DMA signal are clocked. The clock 2142 is output from the data buffer 130 to the equalizers 150, 160, 170.
Input the clock to input data to. A clock 3 143 is input as a clock from the equalizers 150, 160, 170 to the data buffer 2 180, the data buffer 3 190, and the data buffer 4 200 in order to input the equalized data. The clock 4 144 inputs a clock for inputting the sync word used for channel estimation of the equalizer output to the correlator 1 210, the correlator 2 220, and the correlator 3 230.

The equalizer 150 equalizes the time delay spread of the user message stored in the data buffer 135 (or of the received TDMA signal 125). Then, the sync word and the specific user message are output to the signal line 155. Here, the equalizer sync word portion of a specific time slot is used by the equalizer to estimate the multipath characteristics of the channel. The equalizer uses the TDMA signals 141, 142, 142 in order to accurately perform channel estimation and equalization.
143 and 144 are used. The equalizer operates adaptively only while the TDMA controller 140 detects the presence of the desired equalizer syncword or while buffer data is being read into the equalizer.

The output of the equalizer 150 is the sync word used for channel estimation and the equalized data. Here, a part of the sync word is consumed in the process of channel estimation. However, some of them are output with the multipath delay distortion removed. The sync word and the equalized data portion are input to the data buffer 2 180, and only the sync word is input to the correlator 1 210.

The equalizer 2 160 is an equalizer having a flip-flop in front of the equalizer 1 150. If the equalizer operates at symbol intervals, the equalizer 2 160 will be equalizer 1. Data is input with a delay of one symbol compared to 150. Similarly, the equalizer 3 170 is equalizer 2 1
An equalizer with a flip-flop in front of 60,
If the equalizer operates at symbol intervals, equalizer 2 1
Data is input with a delay of one symbol compared to 60. Both the equalizer 2 160 and the equalizer 3 170 operate similarly to the equalizer 1 150. In this way, the equalizer 1
Each of 150, equalizer 2 160, and equalizer 3 170 compensates for distortion due to intersymbol interference or Rayleigh fading of the received signal by measuring continuous multipath characteristics using information obtained from the equalizer syncword. .. Then, the received signal is equalized according to these characteristics.

The correlator 1 210 performs a correlation operation between the input syncword and a known syncword (called a training sequence). As a result, if only K is correct in the sync word N, the correlator 1 210 outputs the value K. Correlator 2220 Correlator 3 230
Is also the same. The data buffer 2 180 outputs only equalized data according to the TDMA controller control signal.
The output of the data buffer 2180 is input to the selector 250 via the signal 185. Similarly, the data buffer 3190 and the data buffer 4200 each have a signal line 19 respectively.
It is input to the selector 250 via 5, 205. The correlation values on the signal lines 215, 225, and 235 are input to the maximum value determiner 240, and the maximum correlation value is determined here.
Then, the selector 25 outputs the control signal 245 for selecting the data buffer output corresponding to the maximum correlator output.
Enter 0. As described above, the selector 250 selects the equalizer output data from the one having the maximum correlation of the syncword of the equalizer output. User data is taken out by the signal line 255 of the selector output.

If necessary, the control signal 245 is sent to the TDM.
By inputting it to the A controller 140, it is possible to power down those other than the one having the maximum sync word correlation value. For example, if the syncword correlation output of the equalizer 2 160 is the maximum, the equalizer 1 1 1
50, equalizer 3 170, data buffer 2 180,
The data buffer 4 200, the correlator 1 210, the correlator 2 220, and the correlator 3230 may be powered down.

With the above configuration, channel estimation and adaptive equalization of the equalizer can be correctly performed even in the presence of multipath fading and Rayleigh fading. This will be explained below. For example, in a transmission without multipath fading or Rayleigh fading, the propagation characteristic is as shown in FIG. 2A, and at this time, the output of the equalizer 2 160 is selected by the above operation. When the transmission line has undergone multipath fading as shown in FIG. 2B, the impulse response at t and the impulse response at t + Δ are overlapped and received at the time t at the receiver. If the power of t + Δ is small to some extent, the TDMA sync 145 is output at the time t.

However, when the power at time t is small and the power at time t + Δ is large as shown in FIG. 2C, TDMA is performed.
It is considered that the sync 145 is adjusted to the time t + Δ. Even if the equalizer has a propagation characteristic as shown in FIG.
It may be better to output the TDMA sync 145 according to the above. In this case, the equalizer 1 should be selected. Since the equalizer operates so as to increase the impulse at time t and cancel the impulse at time t + Δ, the equalizer can be correctly moved with the above configuration.

[0026]

As described above, according to the present invention, since the best equalizer is selected, it is possible to obtain good quality data even if propagation distortion occurs. There is.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a TDMA receiver according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating receiver input of a TDMA receiver according to an embodiment of the present invention.

FIG. 3 is a block diagram of a conventional TDMA receiver.

[Explanation of symbols]

 100 TDMA receiving station 140 TDMA controller 150 Equalizer 1 160 Equalizer 2 170 Equalizer 3 180 Data buffer 2 190 Data buffer 3 200 Data buffer 4 210 Correlator 1 220 Correlator 2 230 Correlator 3 240 Maximum value judgment Vessel 250 selector

Claims (1)

Claim: What is claimed is: 1. A TDMA controller for supplying a timing for extracting data from a received time slot, a plurality of equalizers having different data input timings, and a same number of data buffers as the equalizers. A correlator, a maximum value detector that detects a value with the highest degree of correlation from the output of each correlator, and a TDMA (Time Div) that includes a selector that selects the output of the data buffer according to the output of the maximum value detector.
ssion Multiple Access) receiving device.