JPH01231446A - Bit error rate measuring instrument for tdma channel - Google Patents

Abstract

PURPOSE:To measure the bit error rate by comparing and collating a pseudo random signal included in a data part of a burst signal received and inputted by a reception station with a generated pseudo random signal bit by bit. CONSTITUTION:A transmission station sends the plural kinds of burst signals comprising each set of plural kinds of start signals and plural kinds of pseudo random (PN) signals corresponding one by one to them from data generating sections 1-3. In detecting the start signals of plural kinds by start signal detectors 101-103, the reception station uses PN signal generators 111-113 generate plural kinds of PN signals corresponding one by one to the plural kinds of start signals and compares and collates the received PN signals. Thus, even with the presence of hardware constitution generating a bit error in a specific bit pattern as a reception station equipment, the effect is minimized. Thus, it is possible to measure a bit error rate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides information on bits of a TDMA line used to evaluate the transmission quality of a TD, MA line that transmits information using a time division multiple access (TDMA) method. The present invention relates to an error rate measuring device.

(Prior Art) As is well known, the transmission quality of a digital wireless line is evaluated by the bit error rate (BER), but the BER measurement in a PCM line is performed using a pseudo-random signal (P
an output of a PN signal generator provided on the receiving side that generates the same PN signal as that on the transmitting side;
This is done by comparing and collating the received PN signal reproduced on the receiving side and counting the number of bit errors during a certain period of time (number of bits).

By the way, in recent years, not only satellite communications but also terrestrial communication systems have been using time division multiple access (time division multiple access) such as multidirectional multiplex wireless communication lines.
Wireless lines using the TDMA (TDMA) system are becoming widespread,
It is necessary to evaluate the line quality of such TDMA lines.

In a TDMA line, one transmission frame consists of a plurality of time slots as shown in FIG. 3, and a transmitting station inserts a burst signal into the time slots and transmits the signals. The burst signal consists of a preamble section P used for carrier recovery and bit synchronization, and a start code section S into which a start signal (also called a unique word) consisting of a specific code string for confirming synchronization and identifying the transmitting station is inserted. and,
Normally, the receiving station detects and confirms the start signal, then sends the contents of the data section to the receiving output, where the information to be transmitted (data burst) is inserted.
The device is configured not to send out the reception output when the start signal is not detected correctly.

In other words, when measuring the BER of a TDMA line, if the method used in the PCM line described above is followed as is, if an error occurs in the start signal of a certain burst signal at the receiving station, the following data burst will be completely lost, and the data will be lost. There is a problem in that even if there is no abnormality in the burst, it is counted as having many errors. This means that large fluctuations occur in the measured data even if there is almost no change in the condition of the radio link, and this is inappropriate for the purpose of evaluating the quality of the radio link.

Therefore, in the conventional TDMA line bit error rate measurement method, a transmitting station sequentially transmits a burst signal in which a pseudo-random signal of the same pattern is inserted into the data portion in a predetermined time slot of each transmission frame. 1. An exclusion means is provided at the receiving station to exclude data bursts in the data portion of burst signals whose start signals have not been correctly detected from the measurement target, in order to adapt to the actual situation of the TDMA line.

(Problem to be Solved by the Invention) However, in the conventional bit error rate measurement method for TDMA lines, the data portion of each burst signal is a pseudo-random signal consisting of the same pattern, so the form of bit error occurrence is This may depend on the hardware configuration of the receiving station device.

In this case, the error rate measurement value from the test will be different from that during actual communication, and there is a problem that the transmission quality of the TDMA line cannot be accurately determined.

The present invention has been made in view of these conventional problems, and its purpose is to provide a TDMA system that can measure the bit error rate in accordance with the actual situation by reducing the dependence on the hardware configuration of the receiving station device. An object of the present invention is to provide a line hit error rate measuring device.

(Means for Solving the Problems) In order to achieve the above object, a bit error rate measuring device for a TDMA line according to the present invention has the following configuration.

That is, in the TDMA line bit error rate measuring device of the present invention, the transmitting station includes a start signal generating means for generating each of a plurality of types of start signals; pseudo-random signal generating means for generating each of a plurality of types of pseudo-random signals: a burst signal consisting of a preamble part, a start code part, and a data part in the order of time, which is a burst signal among the plurality of types of start signals; One of the burst signals is inserted into the start code part and one pseudo-random signal corresponding to the start signal is inserted into the data part, and multiple types of burst signals are sent to the time slot of the TDMA (time division multiple access) line in any order. and a start signal detection means for detecting one of the plurality of types of start signals from each received burst signal; clock signal generating means for generating a clock signal having the same frequency as the operating clock of the transmitting station in response to the output;
Pseudo-random signal generating means for generating a pseudo-random signal corresponding to the detected start signal, which is the same as that generated at the transmitting station, in response to the detection output of the start signal detecting means, in accordance with the clock signal; ;
Comparing means for performing a bit-by-bit comparison between a pseudo-random signal included in the data portion of each received burst signal and the generated pseudo-random signal: operating in accordance with the clock signal and outputting the output of the comparing means. Bit error number counting means for counting the number of bit errors; Clock counting means for counting the number of clocks of the clock signal;
It is characterized by having the following.

(For Salary) Next, the operation of the TDMA line bit error rate measuring device of the present invention configured as described above will be explained.

The transmitting station inserts a different pseudorandom signal into the data portion of each burst signal and transmits the signal. Pseudo-random signals can be identified by the contents of the start signal that precedes them, so the receiving station detects the start signal from the burst signal it receives and generates a pseudo-random signal corresponding to the detected start signal. generate a signal. The clock frequency of this pseudo-random signal is the same as that on the transmitting side. Note that if the start signal is not detected, the above operation is not performed; this is done in consideration of the actual situation of the TDMAUiJ line. Then, at the receiving station, the pseudorandom signal included in the data part of the received burst signal and the generated pseudorandom signal are compared bit by bit, and each of the bit error number counting means and the clock counting means The bit error rate is obtained from the ratio of the outputs.

Here, since the receiving station handles multiple types of pseudo-random signals, even if the receiving station equipment has a hardware configuration that causes bit errors in a specific bit pattern, the influence of this can be suppressed to a minimum and the TDMA line Therefore, the bit error rate can be measured in accordance with the actual situation.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the configuration of a transmitting station according to an embodiment of the present invention;
The figure shows an example of the configuration of a receiving station according to an embodiment of the present invention.

In FIG. 1, 1 is a first data generator, 2 is a second data generator, 3 is an N-th data generator, and 4 is an OR (O
R) circuit, 5 is a control circuit, 6 is a timing generation circuit, and N data generators (1°2, . . . , 3) are the first
(2nd to Nth) start signal generators (11, 21, .
..., 31) and the first (second to Nth) PN signal generator (
12, 22, ..., 32).

Timing generation circuit 6 generates a timing signal indicating a predetermined time slot TSN of one transmission frame shown in FIG. 3, and supplies it to control circuit 5.

In response to the timing signal, the control circuit 5 controls the N data generators (1, 2, . . . , 3) to transmit signals in numerical order or in random order. In each data generator, the start signal generator is first driven near the start position of the preamble portion P of the burst signal, and then the PN signal generator is driven at a predetermined position of the data portion of the burst signal. Start signal generator (1
1, 21, . . . , 31) generate a signal to be inserted into the preamplifier section P and a start signal to be inserted into the start code section S. In addition, the PN signal generator (12, 22, ・
, 32) generates a PN signal of a predetermined code length.

That is, each data generator generates a burst signal consisting of a preamble section P, a start code section S, and a data section at the timing of a predetermined time slot TSN designated by the control section 5. This burst signal is sent to the transmission system via the OR circuit 4.

Thus, the predetermined time slot TSN of every transmission frame
A burst signal for bit error rate measurement will be transmitted. Therefore, the timing generation circuit 6 and the control circuit 5
and OR circuit 4 collectively constitute transmission control means.

Here, the start signals generated by each of the N start signal generators have different contents.

Specifically, each of the N start signals is a fixed code that is different from each other and has a sufficient inter-symbol distance to prevent each other from being mistakenly detected at the receiving station and affecting the bit error rate measurement. This is a long signal. The PN signal generator uses an m-sequence linear code generator consisting of, for example, seven stages of shift registers, and outputs a (2'-1) bit code with 1 bit "0" (or "1"). ”) is generated by repeating a 128-bit code, but N PN signal generators (12, 22, . . .
. , 32) also have different contents.

The start signal generated by the first start signal generator 11 has a one-to-one correspondence with the PN signal generated by the first PN signal generator 12, and this relationship holds true for N data generation. The same is true for vessels.

Next, in FIG. 2, 101 is a first start signal detector, 102 is a second start signal detector, 103 is an N-th start signal detector, 111 is a first PN signal generator, and 112 is a first start signal detector. a second PN signal generator, 113 is the Nth P
N signal generator, 121 is an OR circuit, 122 is an exclusive OR circuit as comparison means, 123 is a bit error counter, 124 is an OR circuit, 125 is a clock signal generator, 126 is a clock It is a counter.

The received burst signal 100 is sent to the exclusive OR circuit 1
22, and also serves as an input to N start signal detectors (101, 102, . . . , 103).

N start signal detectors (101, 102°...,
103) detects the corresponding start signal inserted in the start code part of the burst signal 100, and when the start signal is correctly detected, the corresponding PN signal generator (111, 112, . . . , 113)
At the same time, these N activation signals are input to the clock signal generator 125 via the OR circuit 124.

The clock signal generator 125 receives the N activation signals, generates a clock signal having the same frequency as the operating clock on the transmitting side, and transmits the clock signal to the N PN signal generators <111, 112 .
..., 113) is output to the bit error counter.

In other words, in the clock signal generator 125, when all of the N start signal detectors (10f, 102, . . . , 103) can correctly detect the start signal, the predetermined time slot TSN of each consecutive transmission frame is However, if the start signal cannot be detected correctly, the clock signal is not generated at the corresponding predetermined time slot TSN.

Note that the clock signal generated here is counted by a clock counter 126.

N PN signal generators (111, 112, . . .

113) each generates a PN signal with the same content as the one with the same name on the transmitting side.

For example, the first PN signal generator 111
When a drive signal is input from the start signal detector 101, the first PN signal, which is the same as that on the transmitting side, is generated in accordance with the clock signal from the clock signal generator 125. These N
PN code generators (111, 112,..., 113
) is sent to the exclusive OR circuit 1 via the OR circuit 121.
This is the other input of 22.

The exclusive OR circuit 122 performs a bit-by-bit comparison between the PN signal included in the data portion of each received burst signal 100 and the generated PN signal, and if the two differ. Generates a “1” pulse. The number of "°1" pulses generated here is the number of bit errors and is counted by a bit error number counter 123.

In this way, if we calculate the ratio of the count output of the bit error number counter 123 and the count output of the clock counter 1.26, we get B.
A measurement of ER is obtained.

As is clear from the above explanation, when a bit error occurs in the start signal, the clock signal generator 125 does not operate, so the data section in which the apparent bit error occurs is excluded, the bit errors are counted, and the bit errors are further transmitted. Multiple types of burst signals sent from the station can be received at the receiving station in any order, bit errors can be counted, and the BER that reflects the actual condition of the wireless link can be measured.

Regarding the structure of the start signal, if multiple types of start signals with different contents are used for each unit of a certain code length (as in the above-mentioned embodiment), the certain code length is divided into two and the bit pattern of the front part is Various configuration methods can be considered, such as if the same bit pattern at the end is used as a code to specify the PN signal, or if the bit pattern with a constant code length is the same and a code to specify the PN signal is added to it. It will be done.

(Effects of the Invention) As described in detail above, according to the TDMA line bit error rate measuring device of the present invention, the transmitting station receives multiple types of start signals and multiple types of pseudo-random signals that correspond one-to-one to these. A plurality of types of burst signals consisting of each pair with a signal are transmitted, and when a plurality of types of start signals are detected at a receiving station, a plurality of types of pseudo-random signals are generated in one-to-one correspondence with the plurality of types of start signals, Since the configuration is configured to compare and match this with the received pseudorandom signal, even if the receiving station equipment has a hardware configuration that causes bit errors in a specific bit pattern, the influence of this can be minimized and the TDMA line This has the effect of making it possible to measure the bit error rate in accordance with the actual situation.

[Brief explanation of the drawing]

FIGS. 1 and 2 show TDMA according to an embodiment of the present invention.
A radio line bit error rate measuring device is shown, in which Figure 1 is a block diagram of the configuration of a transmitting station, Figure 2 is a block diagram of the configuration of a receiving station, and Figure 3 is a format of a burst signal inserted into a time slot of a TDMA line. It is a diagram. 1...First data generator, 2...
2nd data generator, 3... Nth data generator, 4... OR circuit, 5...
...control circuit, 6...timing generation circuit,
11...First start signal generator, 1
2...First PN signal generator, 21...
...Second start signal generator, 22...Second
31... Nth start signal generator, 32... Nth PN signal generator, 100... Received input burst signal,
101...First start signal detector, 102
...Second start signal detector, 103.
...Nth start signal detector, 111...
...first PN signal generator, 112...second PN signal generator, 113...third PN
Signal generator, 121...OR circuit,
122...Exclusive OR circuit, 123...
... Bit error number counter, 124 .... OR circuit, 125 .... Clock signal generator, 126 .... Clock counter. Agent Patent Attorney Yoshihiro Hachiman / FigureTDMA time, each 4AIJJJ-+=Kamiiri Shiniru burst signal configuration Ijitsubaki 3 Figure

Claims (1)

[Claims] The transmitting station includes a start signal generating means that generates each of a plurality of types of start signals; and a pseudorandom signal generator that generates each of a plurality of types of pseudorandom signals that are in one-to-one correspondence with each of the plurality of types of start signals. Means: A burst signal consisting of a preamble part, a start code part, and a data part in the order of time, one of the plurality of types of start signals is inserted into the start code part and corresponds to the start signal. a transmission control means for transmitting multiple types of burst signals in which one pseudo-random signal is inserted into the data part in a time slot of a TDMA (time division multiple access) line in an arbitrary order; Start signal detection means for detecting one of the plurality of types of start signals from each input burst signal; and a clock signal having the same frequency as the operating clock of the transmitting station in response to the detection output of the start signal detection means. a clock signal generating means for generating a clock signal; in response to the detection output of the start signal detecting means, a pseudo random signal corresponding to the detected start signal, which is the same as that generated at the transmitting station, is generated as the clock signal; a pseudo-random signal generating means that generates a pseudo-random signal according to the clock signal; A TDMA line comprising: bit error number counting means for counting the number of bit errors which is an output of the comparing means; and clock counting means for counting the number of clocks of the clock signal. bit error rate measuring device.