SU1450122A2 - Arrangement for control of data transmission via radio channel - Google Patents

Abstract

This invention relates to radio. The purpose of the invention is to reduce the likelihood of collisions of requests from different subscribers. The device contains prohibitions 1 and 5, formers 2, 4 and 7 impulses, electrons of ШШ 3, el-I 6, el-8 delays, triggers 9, 10 and 11, synchronizer 12 ,. the counter 13 of the collision signals, the decoder 14, the sensor 15 random numbers and the block of fixed delays (BFZ) 16. When a collision signal arrives at the counter 13, it records the number of collisions and, in accordance with its contents, the decoder 14 records the corresponding weighting coefficient of 15. The more the counter 13 reads, the more the interval of numbers taken from the sensor 15 is set, and the longer the time before the retransmission begins, the BFZ 16, i.e. if the channel is busy, then this fact is detected, the terminals perform a random time interval and make a new attempt to occupy the channel. With a random and independent mechanism for the emergence of requests at different stations, the likelihood of their collisions due to the simultaneous activity of some transmitters decreases, and consequently, the stability of the system increases. 1 il. s $ l

Description

The invention relates to techniques for transmitting discrete information, can be used in the construction of data transmission networks based on broadcast packet radio communications and is an improvement of the invention by author; No. 1162057.

The aim of the invention is to reduce the likelihood of collisions of requests from different subscribers.

The drawing shows a structural electrical diagram of a device for controlling the transmission of data over the air. fifteen

The device contains the first inhibit element 1, the first impulse driver 2, the OR element 3, the second impulse driver 4, the second inhibit element 5, the And 6 element, the third £ 0 impulse driver 7, the delay element 8, the first 9, the second 10 and the third 11 triggers, synchronizer 12, counter 13 collision signals, decoder 14, sensor 15 random 25 numbers, block 16 fixed delays.

The device operates as follows.

In the initial state, the presence of an external carrier signal at the first input of the first trigger 9 is monitored. When this signal appears, which indicates the beginning of transmission to other subscribers, the first trigger 9 is set to a state in which the output signal of the first inhibit element 1 is blocked. After resetting the external carrier signal, a signal appears at the output of the third pulse shaper 7, which, after a time determined by the delay elements 8, sets the first trigger 9 to its original state. Moreover, the amount of delay $ provided by the element. 8 delay, equal to the maximum propagation time of the radio signal between subscribers.

If it is necessary to start transmission, the subscriber submits a transmission request signal to the third input 50 of the first prohibition element 1. The operation of the first prohibition element 1 is clocked by pulses arriving at the second input of the prohibition element 1 from the synchronizer 55 12 with a repetition period equal to the maximum propagation time of the radio signal between subscribers.,

If the signal from the first trigger 9 arrives at the first input of the first inhibit element 1, then the subscriber, without lowering the request signal, expects the first trigger 9 to be set to its original state. After resetting the first trigger 9, as well as when the request signal arrives, it is in the initial state, according to the clock pulse from the synchronizer 12 at the output. the first inhibit element 1, a signal appears, and therefore, a signal with a duration equal to twice the pulse repetition period of the synchronizer 12 appears at the output of the first pulse shaper 2. This signal, through the block 16 of fixed delays and the element OR 3, is supplied to the first output of the device and ensures the transmitter is switched on for a while its duration. If one of the stations starts transmitting, then after a time interval ΐ. The carrier signal appears at the input of the other station. Up to this point, the channel for another station is considered free and it has the right to begin its transmission. Therefore, the signal duration taken from block 16 is a multiple of 2 ΐ „Synchronizers 12 in all devices generate pulses synchronously. In the general case, the indicated signal gives out several devices simultaneously. Then, on the trailing edge, the signal from the output of the block 16 of fixed delays at the first input of the And 6 element contains a carrier signal for the maximum propagation time of the radio signal between subscribers who turned on their transmitters at that time. This circumstance makes it possible to recognize a collision situation when trying to transmit. Why, on the trailing edge of the signal from the output of the first pulse shaper 2, a signal appears at the output of the second pulse shaper 4, and therefore a signal appears at the output of element K 6, which sets trigger 11 to a state in which a collision signal appears at the second output of the device, to which the subscriber removes the request signal from the input of the device and postpones the attempt to transmit. The collision signal enters the counter 13 collisions, which records the number of collisions. In accordance with the contents of counter 13 of table 3, decoder 14 fixes the corresponding weight coefficients of random number sensor 15. The more the counter displays the collisions, the larger the interval of numbers taken from the random number sensor is set, and the longer the time interval before the start of retransmission is provided by the block 16 fixed delays, jg If the channel is busy, this is a fact, the terminals work out a random time interval and make a new one attempt to occupy the channel. Moreover, the larger the collision counter readings are, the greater the time interval before the start of retransmission due to the large weighted coefficients of the random number sensor. In the case of random and independent mechanisms of the occurrence of ₂ θ queries at different stations, the probability of their collisions due to the simultaneous activity of some transmitters decreases, and therefore, the stability of the system increases.

After removing the request signal, its trailing edge, arriving at the second input of the third trigger 11, sets βΓΟ IN THE INITIAL STATE. gg

In the case where only one device knew how to turn on the transmitter, then at the moment of the first input of the second element 5, the signal is disabled from the output of the second pulse train at the second input of the ban element 5, there is no external signal, and therefore, the output of this ban element is a signal setting the second trigger 10 to a state in which a transmit enable signal appears at the output of the device. In this case, the signal from the output of the second trigger 10 is fed to the second input of the OR 3 element, which leads to the appearance of a signal at its output, which means that the transmitter turn-on signal appears at the output of the device. After the end of the data transfer, the subscriber removes the request signal from the input of the device, which leads to the initialization of the second trigger 10.

Claims (1)

Claim A device for controlling the transmission of data over a radio channel through auto No. 1 162057, characterized in that, in order to reduce the likelihood of collision of requests from various subscribers, the output of the first pulse shaper is connected to the input of the second pulse shaper and to the first input of the OR element through the input block of fixed delays, and between the output of the third trigger and the control input of the block of fixed delays included in series are connected collision signal counter, decoder and random number sensor.