JPH0611139B2 - Multi-access method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multi-access method for efficiently performing channel assignment work in a LAN (local area network) or satellite communication, and particularly, a random number initial value different for all slave stations. Regarding how to allocate.

[Prior art]

There is a multi-access protocol as an arrangement for efficiently performing the assignment work when an unspecified number of slave stations issue a channel assignment request at an undefined time in LAN or satellite communication.

However, the conventional protocol has a problem in that when a large number of slave stations transmit data packets at the same time, packet collisions occur, packet retransmissions frequently occur, and transmission efficiency is extremely reduced. Further, there are cases where transmission cannot be performed at all.

Therefore, a network is formed by one control station and a plurality of slave stations, a probability reference value is generated in that control station, and a random number is generated by a random number generator in each slave station,
A multi-access method is conceivable in which one slave station is selected and accessed by comparing the random number and the probability reference value.

In this case, it is necessary to set an initial value in the random number generator of each slave station.One way to do this is to set a fixed random number in each slave station in advance and use the initial value setting command from the control station. , Each slave station may be configured to set an initial value.

However, although this method can make the initial values of the respective slave stations different from each other, and thus the random numbers generated by the respective slave stations can be prevented from matching at the same time,
As for each slave station, since it starts with the same initial value every time, there is a problem that the priority order of network access is fixed.

[Object of the Invention]

An object of the present invention is to enable different initial values to be set for each slave station each time initial values are set, so that no priority is given to network access and fair access is performed. is there.

[Structure of Invention]

To this end, the present invention performs data transmission by receiving one control station and one data transmission channel assigned from the plurality of data transmission channels by the control station via the control channel. A plurality of slave stations, wherein one or more slave stations requesting allocation of a data transmission channel among the slave stations generate random numbers different from each other, and generate random numbers through the control channel; It is taken in by the control station, a probability reference value is generated in the control station, and this is compared with the random number. Request the allocation of the data transmission channel by using the numerical value obtained by performing the arithmetic processing of the station number and the common numerical value in each slave station as the initial value of the random number. Until the slave station is narrowed down to one in which the probability reference value and the random number have a specific relationship, the probability reference value is sequentially changed, and the random number generation in the slave station is started and changed from the initial value. Then, a specific data transmission channel is assigned to one slave station narrowed down by the comparison via the control channel.

〔Example〕

Examples of the present invention will be described below. FIG. 1 is an explanatory view of the embodiment. In the present embodiment, first, one control station 1 is provided to perform data transmission scheduling, channel assignment work, and the like. 2 _{1 to} 2 _n are n slave stations, which transmit data in response to a command from the control station 1.

Now, assume LAN and satellite communication. Further, it is assumed that the transmission path is divided into m independent channels by frequency division, time division, or another method. Then, one of the channels is used for control, and the remaining channels are used for data transmission.

When any of the slave stations 2 _{1 to} 2 _n transmits data from the slave station 2 _{1 to} 2 _n , a request signal for data transmission channel allocation for transmitting data to the control channel is sent to the control station 1. put out. Then, when the control station 1 receives this request, it performs channel allocation, and to that effect, channel allocation information is sent to the corresponding slave station through the control channel, whereby the specific data transmission channel to which the slave station is allocated is transmitted. To send data packets to.

By the way, when a very large number of the slave stations 2 _{1 to} 2 _n output a channel allocation request signal to the control channel, the signals collide with each other on the control channel, and the control station 1 receives the signal from the slave station. The request signal cannot be received.

Therefore, in such a case, in the present embodiment, the control station 1 first outputs a certain probability reference value signal Pa (0 <Pa <1), and the slave stations 2 ₁ to 2 _n each independently generate a different random number. It was generated from a generator (not shown). In this case, naturally, not all of the slave stations 2 ₁ to 2 _n generate random numbers, and only the slave stations desiring channel allocation generate random numbers.

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

However, when there are two or more slave stations that have generated the above random number Pa or less, the request signals collide, so the control station 1
Then, a probability reference value of Pb (0 <Pb <Pa) is output, and a random number is generated again for all slave stations desiring to allocate a channel for data transmission.

As a result, when there is only one slave station that has generated a random number equal to or smaller than the probability reference value Pb, the station is caused to issue a channel allocation request signal and the channel allocation is scheduled with that station.

If there are two or more slave stations that generated random numbers less than Pb,
By issuing a lower probability reference value Pc (0 <Pc <Pb),
Random numbers are generated for all slave stations desiring to allocate data transmission channels again.

As described above, by gradually decreasing the probability reference value serving as a reference for selecting a random number (for example, 0.5 → 0.25 → 0.125 ...), any one of the slave stations is stochastically selected.

However, as a result of doing so, if there is no allocation request at a certain stage, then any of the slave stations can be selected by conversely gradually increasing the above value.

The above method enables efficient channel allocation.

Now, it is necessary to generate random numbers so that none of the slave stations simultaneously generate random numbers of the same sequence. In the present embodiment, this was realized as follows.

For example, if the signal of the probability reference value set in the control station 1 is 3 bits for simplicity, the slave stations 2 ₁ to 2 _n also have 3 bits.
Assign station numbers with different bits in advance. FIG. 2 shows this example, and the slave stations are 7 stations 2 ₁ to 2 ₇ , and their station numbers are “001” to “111”.

Then, the random number generator in the control station 1 generates a random number “101” as a common 3-bit numerical value and delivers it to each slave station. Next, if the exclusive OR of the random number delivered from the control station 1 and the station number of the station is taken in each slave station, as shown in the figure, the slave stations 2 ₁ to 2 ₇ are different from each other. The numerical value is obtained.

Therefore, by setting this value as the initial value of the random number generator of the slave station 2 ₁ to 2 _7, because the initial value random number generation from starts, continue to change with time, at the same time in each slave station The same random number will not be generated.

Therefore, if the common numerical value delivered from the control station 1 is made different each time, the initial value will be made different every time, and the priority order of access will not occur in the slave station.

When lowering the priority of a slave station that has completed transmission for a while, set the slave station to access the control channel by multiplying the random number generated by that slave station by h (h> 1). In this case, since the random number is multiplied by h in this case, the priority is lowered to 1 / h.

〔The invention's effect〕

As described above, according to the present invention, the random numbers generated in each slave station always have mutually different values, and the initial value can be changed every time, so that fair access can be performed to each slave station.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of random number initial value setting of each slave station.

Claims (3)

[Claims] Claim: What is claimed is: 1. A control station, and a plurality of data transmission channels, each of which receives one data transmission channel from a plurality of data transmission channels by the control station via the control channel. A slave station, wherein one or more slave stations requesting allocation of a data transmission channel among the slave stations generate mutually different random numbers, and the random numbers are generated through the control channel to the control station. The control station generates a probability reference value and compares it with the random number.At this time, a different station number is assigned to each slave station in advance, and a common numerical value from the control station is assigned to each slave station. A mobile station that has requested the allocation of the data transmission channel by using the numerical value obtained by calculating the station number and the common numerical value by each slave station as an initial value of the random number Until the probability reference value and the random number are narrowed down to one having a specific relationship, the probability reference value is sequentially changed, and the random number generation in the slave station is started and changed from the initial value. A multi-access method in which a specific data transmission channel is assigned to one slave station narrowed down by the control channel via the control channel. 2. The station number and the common numerical value are binary numbers having the same number of bits.
The multi-access method described in the section. 3. The multi-access method according to claim 1, wherein the arithmetic processing is processing for taking an exclusive OR.