JPS6324735A - Multi-accessing method - Google Patents

Abstract

PURPOSE:To efficiently perform an allocation, by generating a probability reference value at a control station, generating a random number at a slave station, allowing the slave station having a generated random number less than the probability reference value to issue a channel allocation requesting signal, and decreasing or increasing the probability reference value sequentially. CONSTITUTION:First of all, the control station 1 issues a certain probability reference value signal Pa(0<Pa<1), and the slave stations 21-2n generate the different random numbers above zero and less than one independently. The control station selects the slave station generating the random number less than the probability reference value Pa out of the random numbers generated by the slave stations, and makes the slave station issue the channel allocation requesting signal. When two or more slave stations generate the random number less than the Pa, the control station issues the probability reference value Pb (0<Pb<Pa) at the next stage, and makes all of the slave stations requesting data channel allocation generate the random numbers. Thus, by decreasing the probability reference value which becomes reference to select the random number gradually, either one of slave stations can probably be selected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-access method for efficiently performing channel allocation work in LAN (Local Area Network) and satellite communications.

[Prior art]

In LAN and satellite communications, when an unspecified number of slave stations issue channel allocation requests at unscheduled times, a multi-access protocol is used to efficiently carry out the allocation work.

However, in the conventional protocol, when a large number of slave stations transmit data packets at the same time, packet collisions occur and packet retransmissions occur frequently, resulting in an extremely low transmission efficiency.

In addition, there have been cases where the system has become unable to transmit data at all.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to avoid the above-mentioned collisions and to perform efficient allocation even when a large number of slave stations request channel allocation at the same time.

[Structure of the invention]

To this end, the present invention generates a probability standard value in a control station that performs channel assignment work, and generates a random number greater than zero and less than 1 in a slave station requesting channel assignment, and the generated random number is set to meet the probability standard value. A slave station having a value smaller than the control station is made to issue a channel allocation request signal, and the probability reference value generated at the control station is sequentially decreased or increased to select one slave station requesting channel assignment. .

〔Example〕

Examples of the present invention will be described below. FIG. 1 is an explanatory diagram of the embodiment. In this embodiment, first, one control station 1 is provided and is assigned to perform tasks such as data transmission scheduling and channel allocation. 21 to 2° are n slave stations, which transmit data according to commands from the control station 1.

Now, assume LAN or satellite communication. It is also assumed that the transmission path is divided into m independent channels by frequency division, time division, or other methods. One of the channels is used for control, and the remaining channels are used for data transmission.

Now, slave station 2. 21 sends to the control station 1 a request signal for allocating a data transmission channel for transmitting data to the control channel.

When the control station 1 receives this request, it allocates a channel and sends channel allocation information to the corresponding slave station through the control channel, which causes the slave station to send a data bucket to the data transmission channel. I'll do what I do.

By the way, slave station 2. When a very large number of stations .about.2n output channel allocation request signals on the control channel, the signals collide on the control channel, making it impossible for control station 1 to receive this request signal from the slave station.

Therefore, in this embodiment, in such a case, the control station 1 first outputs a certain probability reference value signal Pa (0<Pa<1),
A random number generator (not shown) generates different random numbers independently for each of the slave stations 21-21. In this case, naturally, not all of the slave stations 2-27 generate random numbers, and only the slave stations that desire channel assignment generate random numbers.

Then, among the random numbers generated by each slave station, a slave station that has generated a random number less than or equal to the probability reference value Pa described above is selected, and the slave station is caused to issue a channel allocation request signal. As a result, if only one slave station has issued the request signal, channel allocation is scheduled with that slave station.

However, if there are two or more slave stations that have generated random numbers less than or equal to Pa, the request signals will collide, so the control station
Next, a probability standard value of Pb (0<Pb<Pa) is determined, and random numbers are generated again for all slave stations that wish to be assigned data channels.

As a result, if only one slave station generates a random number less than the probability reference value pb, that station is caused to issue a channel allocation request signal, and channel allocation is scheduled with that station.

If there are two or more slave stations that have generated random numbers less than pb,
Even lower probability standard value P c (0< P c < P
b) to generate random numbers again for all slave stations that wish to allocate data channels.

As mentioned above, the probability standard value, which is the basis for selecting random numbers, gradually decreases (for example, 0.5 → 0.25 → 0.125...)
By doing so, any one slave station will be selected with probability.

However, as a result of doing this, if there are no allocation requests at a certain stage, then by gradually increasing the above numerical value, it is possible to select one of the slave stations.

By the above method, channel allocation can be performed efficiently.

Note that when generating random numbers, it is necessary to ensure that no slave station generates random numbers of the same series at the same time, but this can be achieved in the following manner.

For example, if the probability standard value signal set at control station 1 is 3
If it is a 2-bit number, a different 32-bit station number is also assigned to slave stations 21-2 in advance. And control station 1
A 32-bit random number initial value setting value is generated in the random number generator within the controller. Then, this initial value setting value and the slave station 2. ~
By performing an exclusive OR with the station number of 2°, all slave stations will be set to different random number generation initial values, and will all issue different random number sequences over time.

In addition, if you want to lower the priority of a slave station that has finished transmitting for a while, the slave station should multiply the random number generated by that slave station by h (h>1) and access the control σ channel. If set, the random number will be multiplied by h in this case, so the priority will be lowered to 1/h.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to efficiently perform channel assignment work.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

Claims (1)

[Claims] (1) A control station that performs channel assignment work generates a probability standard value, a slave station that requests channel assignment generates a random number greater than zero and less than 1, and the generated random number is less than the probability standard value. A multi-access method in which one slave station requesting channel assignment is selected by causing the slave stations of the same value to issue a channel allocation request signal, and by sequentially decreasing or increasing the probability reference value generated at the control station. .