SU1741150A1 - Device for simulating communication systems - Google Patents

Abstract

This invention relates to specialized computer and communications equipment. The purpose of the invention is to expand the functionality. To achieve the goal, a second random pulse generator, a matching unit, an erase counter, an adjacent retransmission counter, a failure counter, and an adder are entered into the device. The device allows the characteristics of a wide class of communication systems to be recorded both with reshoot and erasure, as well as with a limited number of reshoot. 1 z.p f-ly, 2 ill.

Description

The invention relates to specialized computer and communication equipment and can be used in the development of simulation models of adaptive communication systems.

A device for simulating communication systems is known, comprising a pulse generator, a message multiplication counter, a random pulse flow generator, an NOT element and an AND element, as well as a correctly received message counter and a pulse counter.

A disadvantage of the prior art is the narrow functionality.

The closest in technical essence to the present invention is a device for modeling communication systems comprising a pulse generator, a counter of correctly received messages, a message multiplicity counter, a trigger, a random generator

pulse flow, NOT element, two AND elements, OR element, comparison circuit and reversible counter

The disadvantage of this device is narrow functionality, which does not allow to model communication systems with erasures and with a limited number of questioning.

The purpose of the invention is to enhance the functionality by simulating an erasure-related communication system with a limited number of questioning.

The goal is achieved in that a device for modeling communication systems, comprising a pulse generator, a first random pulse stream generator, a message multiplicity counter, an error counter, a comparison circuit, a counter of transmitted messages, a counter of correctly received messages, a retransmission counter and generator code impulH | B

SL O

It is connected to the counter input of the message multiplicity counter, the overflow output of which is connected to the error counter read enable input, the counter of the transmitted messages count input and the comparison circuit resolution enable input, the inputs of the first group of which are the device installation inputs, the Outputs and the Less than or equal to comparison circuit connected to the counting inputs, respectively, of the retransmission counter and the counter of correctly received messages; a second generator of a random stream of pulses was introduced; A counter, erase counter, an adjacent retransmission counter, a fault counter and an adder, the outputs of the pulse generator, the first and second generators of a random pulse flow are connected to the first, second and third inputs of the matching unit, the first and second outputs of which are connected to the counter inputs of the counter, respectively error and erase counter, overflow output of the message multiplicity counter is connected to the read enable input of the erase counter, error counter and connection erase counter outputs They are respectively with the first and second groups of inputs of the adder, the outputs of which are connected to the second group of inputs of the comparison circuit, the outputs of which are More or Less than or equal to which are connected respectively to the counting input and the reset input of adjacent retransmissions, the overflow output of which is connected to the counting input of the fault counter.

In addition, the matching unit contains the first and second triggers, the first and second elements AND, and the installation inputs of the first and second triggers are the second and third inputs of the unit, respectively, the reset inputs of the trigger are combined and connected to the first inputs of the first and second elements AND are the first input of the block, the direct output of the first trigger is connected to the second input of the first element And, the direct and inverse outputs of the second trigger are connected respectively to the second input of the second element And and to the third input of the first and second the first elements and are respectively the first and second outputs of the matching unit,

FIG. 1 shows a block diagram of a device for modeling communication systems; in fig. 2 is a block diagram of the matching unit.

A device for simulating communication systems (Fig. 1) comprises a pulse generator 1, a matching unit 2, first and second generators 3 and 4 of a random pulse stream, an error counter 5, an erase counter 6, a message multiplication counter 7, a counter 8

retransmissions, counter 9 correctly received messages, counter 10 transmitted messages, counter 11 related retransmissions, counter 12 failures, adder 13, comparison circuit 14 and block 15

0 indications. The group 16 of the installation inputs of the device is connected to one group of inputs of the circuit 14.

Block 2 matching (Fig. 2) contains the first and second triggers 17 and 18, the first and

5 second elements And 19 and 20.

The device works as follows.

The initial state of all counters and device triggers is zero.

0 The pulse generator 1 generates a sequence of pulses simulating a transmitted message consisting of n elements. Each message element is modeled by a single generator pulse.

5 1. The pulses from the generator 1 are fed to the counting input of the counter 7 of the multiplicity of messages, designed to simulate the length of the message. The message length is specified by the recalculation module of counter 7 (for communications of length n, its recalculation module is n-1). The number of overflows of counter 7, recorded in counter 10, determines the number of messages transmitted over the communication channel.

5Generators 3 and 4 generate, respectively, random pulses corresponding to errors and erasures, which are statistically independent of each other.

In block 2, matching of the error and erasure pulses to the generator 1 pulses occurs, as well as matching the flows in accordance with the principle of operation of real communication systems: when erasing a symbol (for example, a receiver quality detector of the communication system), an error occurred or not. In block 2, the errors and erasures of triggers 17 and 18, respectively (at an arbitrary time), are set to one state. The first clock pulse received after this polls the triggers 17 and 18. If, in the period between clock pulses, the error signal is received and the signal is not erased, then

5, a pulse is formed at the output of the element 19 and is fed to the counter in the error counter. If, in the time interval between clock pulses, the signal is erased by wils, then regardless of the presence of an error signal, a pulse is formed at the output of the element

20 and is counted by an erase counter. At the same time, at the output of the element AND 19 a pulse is not formed. Thus, the absorption is carried out by erasing errors.

The same clock pulse at the input of block 2 resets the triggers 17 and 18 to the zero state and prepares for the analysis of the next message symbol. Thus, the coupling of erase and error pulses to the device clock pulses, i.e. each pulse of error (erase) affects only one character of the simulated message.

When a signal appears from the overflow output of the counter 7 of the multiplicity of messages, which fixes the end of the transmission of this message over the communication channel, error codes and erasures are read out, respectively, from counters 5 and 6 to the adder 13. The relative weight of each error is equal to twice the erasure weight. which corresponds to the results of the coding theory and, in particular, the Hamming distance required for error correction and erasures. The adder determines a number equal to the sum of the quantities of the erase and twice the number of errors in the current transmitted message. The signal from counter 7 permits comparison of the number from adder 13 with the maximum correction capacity of the system set at the request of the user (for a particular communication system), which is continuously fed to the device via inputs 16.

In this case, if the content of the adder 13 is greater than the set maximum value, the fact of an erroneously received message occurs, followed by a reshoot. The output signal from the More comparison circuit is fed to the input of the retransmission counter.

If the content of the adder is less than or equal to the code at the inputs 16, the fact of correct transmission of messages takes place, the signal from the output Less or equal to comparison circuit 14 goes to the counter of correctly received messages.

Thus, the outcomes of receiving individual messages are modeled. Then the counters 5 and 6 are reset.

A simulation of a communication system with a limited number of reseals is carried out as follows.

Re-request signal from the output of the More comparison circuit 14 is fed to the counting input of the counter 11 of contiguous retransmissions, in which the re-interrogations of the same message are made. The number of questioning (limited) of the same

the same message is set by the counting module of the counter 11. If, for any intermediate content of the counter 11, the current message is transmitted in the correct order, the output signal is less than or equal to the comparison circuit 14 resets the counter 11. If the number of resendings of the same message reaches the maximum allowed and surpasses it

0, the overflow signal of the counter 11 is fed to the counter of the failures and resets the counter 11 to the zero state, registering the failure of the system from receiving the current message. Thus, the proposed device allows to record the characteristics of communication systems with erasures and with a limited number of questionings, which expands the functionality.

Claims (2)

Invention Formula 0 1. Device for modeling communication systems, comprising a pulse generator, the first random pulse generator, a message multiplication counter, an error counter, a comparison circuit, a counter 5 transmitted messages, a counter of correctly received messages, a retransmission counter, with the output of the pulse generator connected to the counting input of the counter of the multiplicity of messages, the overflow output 0 which is connected to the read enable input, an error counter, to the counting input of the transmitted message counter and to the comparison enable input of the comparison circuit whose inputs of the first group are 5 installation inputs of the device, outputs More and Less than or equal to the comparison circuit are connected to the counting inputs of the retransmission counter and the counter of correctly received messages, respectively, characterized in that, in order to extend the functionality by simulating a communication system with erase and limited number of questioning, a second random pulse flow generator, a matching unit, an erase counter, an adjacent retransmission counter, a failure counter and an adder, and generator outputs are entered into it. pulses, first and second 0 generators of a random stream of pulses are connected respectively to the first, second and third inputs of the matching unit, the first and second outputs of which are connected respectively to the counting 5 inputs of the error counter and the erase counter, the output of the overflow counter of the message multiplicity is connected to the read resolution input of the erase counter, the outputs of the error counter and the erase counter are connected respectively to the first and the second groups of inputs of the adder, the outputs of which are connected to the second group of inputs of the comparison circuit, the outputs of More and Less than or equal to which are connected respectively to the counting input and the reset input of the counter of repeated retransmissions, the overflow output of which is connected to the counting input of the failure counter. 2. Device pop. 1, characterized in that the matching unit contains the first and second triggers, the first and second elements AND, and the installation inputs of the first and second triggers are respectively Respectively, the second and third inputs of the block, the reset inputs of the triggers, are combined and connected to the first inputs of the first and second elements AND, and are. the first input of the unit, the direct output of the first trigger is connected to the second input of the first element And, the direct and inverse outputs of the second trigger are connected respectively to the second input of the second element And and to the third input of the first element And, the outputs of the first and second elements And are respectively the first and the second outputs of the matching unit, I V SL Phie. one