CN1037480C - Method and apparatus for contending for access to a communication channel - Google Patents
Method and apparatus for contending for access to a communication channel Download PDFInfo
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- CN1037480C CN1037480C CN93107408A CN93107408A CN1037480C CN 1037480 C CN1037480 C CN 1037480C CN 93107408 A CN93107408 A CN 93107408A CN 93107408 A CN93107408 A CN 93107408A CN 1037480 C CN1037480 C CN 1037480C
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Abstract
The present invention relates to a method for contending for communication channels and a device communicating on the communication channels, such as a supervisory control and data acquisition (SCADA) device. The contention is coordinated by time delay before a communication channel using request. When one unit (16) has successful contention, a long time delay is introduced before next contention; a short delay is introduced when the unit has an unsuccessful contention.
Description
The present invention relates to the method for contention communication channel and the communicator of using at this channel communication, obtain (SCADA) device such as monitoring and data.
In recent years, for Speech Communication and data communication, it is very jammed that radio channel has become.
In communication system such as the SCADA system, can there be several to be positioned at different local main control units, they are all attempted on same radio frequency, even through same radio relay station commonly used, inquiry respective remote terminal unit (RTU), this situation is common in alarm control system (siren control system).Figure 1 illustrates a this system.In this figure, a master controller 11 is arranged, it sends to several RTU16 and station, regional center (RC) 13,14 and 15 in the very big zone to warning start-up control signal by a public relay station 12, and wherein each RTU 16 all has the siren 17 that interrelates with it.The task at station, regional center (RC) is the data from a group alarm device of collecting after control.Its alarm must be inquired in each station, regional center (RC) after startup, start to understand whether problem is arranged, and they all will do these things through same public relay station 12.Common this situation has the possibility that can cause confusion on radio channel, because all stations, regional center (RC) will begin inquiry simultaneously, recall signal can in time be received from its alarm in station, neither one regional center (RC) as a result.
Perhaps may set up a fixing queuing order, station, some regional center (RC)s in these stations, regional center (RC) is always the first one inquires its RTU thereby make, always second at another station, regional center (RC), or the like.But this possible solution has shortcoming, and the operator at the station, regional center (RC) of last inquiry that Here it is always the result occurs on warning start-up control signal and monitoring screen the phase is wanted equal long time during this period of time.This delay is unacceptable.Lack actual circuit between the station, regional center (RC), meaning does not have the simple method of each central station synchronously, so that the operator of all regions central station can obtain upgrading in the time that equates.
Need a kind of communication system, it allows contention channel regularly, and reason is not introduced undue delay from the response of any discrete cell.
According to the present invention, a kind of method of contention communication channel is provided, it comprises the following steps: to receive an instruction with the beginning contention; From one group of time-delay, select a time-delay; After choosing was delayed time down, transfer channel used request; If receive that it just is that contention is chosen the longest time-delay that channel is authorized instruction next time, if do not receive that it just is that contention is chosen short time-delay that channel is authorized instruction next time.
In this way, one circulative time-delay is provided, wherein the unit of contention success has arrived tail of the queue owing to having introduced the longest time-delay before the contention once more at it, and the not successful unit of contention has shifted to an earlier date its position in formation owing to contention time-delay next time is short.
The length of time-delay is relevant with the position in formation, because between time delay, has than other unit of short time delay request of having an opportunity and uses channel.
In another aspect of this invention, a kind of communication unit is provided, be used for through a channel and another unit communication, this unit comprises the device that is used for contention channel, is used for the device that receive channel is authorized the device of instruction and be used for transmitting to other unit signals when being received this instruction, the device that wherein is used for contention comprises postpones contention from the deferred mount of one period time of delay that one group of time-delay is selected, and wherein be right after after once successful contention, for the selected time-delay of contention next time then is elder in one group of time-delay; And after unsuccessful contention once, be that next contention is selected short time-delay wherein.
Two or more this unit (station, regional center (RC)) can be provided, and the time-delay in one group of time-delay of one of them unit has departed from the time-delay of the time-delay group of second (other are arranged) unit, and is interspersed between it.
Below with reference to accompanying drawings, most preferred embodiment of the present invention is only described by way of example.
Fig. 1 has showed the general SCADA communication system according to prior art, and it is suitable for improving according to the present invention.
Fig. 2 has showed the center cell (" station, regional center (RC) ") 13 of Fig. 1, and it has comprised according to improvement of the present invention.
Fig. 3 A and 3B have showed the algorithm of the center cell that is used to realize Fig. 2.
The operation of Fig. 1 system is as follows.Main center cell 11 sends an instruction to all RTU16, makes them start their alarm.This instruction is through relay station 12 communications and directly pass to all RTU16 from relay station.One receives this instruction, and alarm 17 is entry into service.Simultaneously, station, regional center (RC) 13,14 and 15 is 12 these instructions of reception through the repeater, and beginning demand operating process, altogether between all RTU in 13 their respective regions of inquiry of station, regional center (RC), and if alarm just take appropriate measures at station, regional center (RC) 13 when failing to start.For example, adequate measures can be display alarm this facts that lost efficacy on the monitor at station, regional center (RC) 13, urge operator this alarm location of sending someone to go to give the alarm to the also people in district that will warn by hand.Station, regional center (RC) 13 can be reported back the result of their interrogator to main center cell 11.Below in conjunction with Fig. 3 interrogator is described in more detail.
Referring to Fig. 2, shown station, regional center (RC) 13 comprises transmitter part 20, receiver part 21, microprocessor 22, RAM memory 23 and ROM memory 24.Data are sent to antenna 25 from microprocessor 22 through transmitter part 20, and are received by remote processor 22 through this antenna and receiver part 21.Receiver part 21 has a channel monitoring device output 30, and it receives microprocessor 22.Move under the control of the program of microprocessor 22 in being stored in ROM memory 24, and RAM memory 23 is read and write to data.
This RAM memory comprises several registers, table etc.Shown two tables in these tables among the figure, they are RTU table 27 and delay selection device (SEC) table 28.For a more detailed description below in conjunction with Fig. 3 to these features.
RAM memory 23 also comprises following setup parameter, and they are set in each station, regional center (RC):
Inquiry length of window-WWWW (such as 10 seconds);
The number at the station, regional center (RC) in the system :-CCCC (such as 3).
In step 201, the alarm enabled instruction of receiving from main center cell 11 via relay station 12 start Fig. 3 A and the 3B shown in algorithm.In all regions central station 13,14 and 15, side by side start with Fig. 3 A and 3B in identical algorithm.Before describing this algorithm in detail, its overall operation is: the each department central station must will be waited for the different delayed time of empty RF channel (not having transmission on this radio channel) earlier before it can begin its interrogator.When interrogator begins, the each department central station only inquire it in preset time (be called inquiry " window "---one of several RTU inquiry circulation) so much RTU that can inquire.Yet in this inquired between window phase, the each department central station is the empty channel of competition before transmitting by inspection channel monitoring device 30.When channel was empty, its RTU was inquired and one by one without any delay in station, a regional center (RC).After time, the regional center (RC) stands in it can inquire that window continues must wait for once more before the minimum time-delay of empty RF channel with another in inquiry " window ".The total time of inquiring all RTU can take several windows.
When certain areas's central station just had been operated on the same radio channel, the time-delay at each station, given regional center (RC) can dynamically change after each inquiry window, so the inquiry window of each unit changes.
As an example, will describe a system, it has the window time (being enough to inquire the time of 4 to 5 RTU) of station, three regional center (RC)s and 10 seconds.
In order to eliminate as far as possible in the conflict that may begin with identical time-delay between the regional center (RC), the delay selection before inquiry circulation beginning is as follows: for station, first regional center (RC) 13, be selected from the group of 1.0,2.0 and 3.0 seconds formations; To station, second regional center (RC), be selected from the group of 1.1,2.1 and 3.1 seconds formations; To station, the 3rd regional center (RC), be selected from 1.2,2.2 and 3.2 groups of forming.What four, station, the 5th regional center (RC) can have other in the same manner may the time-delay group.These accurate time-delays only provide as an example.The experienced professional in this area should understand certainly time-delay do not leave no choice but from table " selecting " can not, but can realize by increasing or reduce numerical value with appropriate intervals.This principle of optimal algorithm requires that each station, regional center (RC) is had at least " n " individual delay cycle, and number " n " equals to be in station, the regional center (RC) number of same frequency.The corresponding delay of each department central station should stagger each other with the time-delay at other stations, regional center (RC) at interval.
These time-delays are as shown in table 1.
Table 1
| Function | Station, regional center (RC) 13 (the 1st central station) | Station, regional center (RC) 14 (the 2nd central station) | Station, regional center (RC) 15 (the 3rd central station) | Step |
| Time-delay before first circulation | 1.0 | 1.1 | 1.2 | 101 |
| Operation | Inquiry | Wait for | Wait for | 102 |
| Time-delay before second circulation | 3.0 | 1.1 | 1.2 | 103 |
| Operation | Wait for | Inquiry | Wait for | 104 |
| Time-delay before the 3rd circulation | 2.0 | 3.1 | 1.2 | 105 |
| Operation | Wait for | Wait for | Inquiry | 106 |
| Time-delay before the 4th circulation | 1.0 | 2.1 | 3.2 | 107 |
| Operation | Inquiry | Wait for | Wait for | 108 |
| Time-delay before the 5th circulation | 3.0 | 1.1 | 2.2 | 109 |
| Operation | Wait for | Inquiry | Wait for | 110 |
| Time-delay before the 6th circulation | 2.0 | 3.1 | 1.2 | 111 |
| Operation | Wait for | Wait for | Inquiry | 112 |
| Time-delay before the 7th circulation | 1.0 | 2.1 | 3.2 | 113 |
| Operation | Inquiry | Wait for | Wait for | 114 |
| Time-delay before the 9th circulation | 3.0 | 1.1 | 2.2 | 115 |
Receive inquiry during sign on when station, regional center (RC) 13,14 and 15 from main center cell 11, they all start their back off timer (step 101 in the table 1).Station, first regional center (RC) 13 with time-delay of 1 second will be first interrogator that begins its RTU (step 102 and following referring to Fig. 3).Detect second and station, the 3rd regional center (RC) 14 and 15 of the activity of radio channel, will wait for and do not begin its interrogator.At 10 seconds the time of (station, first regional center (RC) inquiry " window ") afterwards, first also district center station 13 finish its inquiries and 3 seconds (step 103) changed in its time-delay (table 28 among Fig. 2).Second delay cycle begins, and after 1.1 seconds, station, second regional center (RC) 14 will begin its inquiry window (step 104).When finishing in this step, station, second regional center (RC) 14 is changed into maximum to its time-delay--and 3.1 seconds (step 105).Simultaneously, the time-delay at station, first regional center (RC) 13 has been changed into 2 seconds, because go and the activity at other center cell stations of broadcasting has been detected at station, first regional center (RC) 13 greater than 0.7 second window time-out, and these activities have stoped it to begin another inquiry window.After station, second regional center (RC) 14 stops its inquiry, the time-delay at station, the 3rd regional center (RC) 15 will be the shortest--1.2 seconds (step 105), thus it will begin its inquiry window (step 106).After its inquiry window was finished at station, the 3rd regional center (RC) 15, it changed into 3.2 seconds (step 107) to its oneself time-delay, and simultaneously, station, first regional center (RC) its time-delay is changed into 1 second and station, second regional center (RC) 14 has become 2.1 seconds to its time-delay.Like this, what the next one will begin another interrogator is station, first regional center (RC) 13 (108), and the rest may be inferred.
If only there is in the station, three regional center (RC)s one to wish the beginning interrogator, it will wait for three seconds (being maximum delay) and will continue inquire its all RTU in the window that links to each other successively between each inquiry window so.
Referring to Fig. 3, it has shown the interrogator of carrying out in each department central station 13,14 and 15.Program is beginning by receiving the sign on of coming autonomous center cell 11 (preferably with the same instruction that alarm is opened advise) at relevant station, regional center (RC).In step 202, RTU questionnaire 27 (Fig. 2) is reset, and in step 203, according to the step 101 in the table 1, beginning first time-delay.Between this time delay, the radio frequency (204) of the receiving system 21 supervisory channel activities at station, regional center (RC).If this channel is empty, and the first time-delay end (205), this area's central station begins its window time WWWW (206) so.It checks free channel monitoring device (step 207) once more, and if channel is empty, an inquiry request (step 208) is sent to a RTU in station, regional center (RC) 13.The station, regional center (RC) waits for that one answers (step 209), and is receiving from the answer (210) of a RTU afterwards, and the station, regional center (RC) checks that whether it is last RTU (step 212) on the table.If it does not receive answer (step 210), the regional center (RC) stands in RTU inefficacy mechanism of experience in the step 224,223,211 and 225 so.If received answer in step 210, and it is not last RTU (212) on the table, and so, the station, regional center (RC) makes the pointer on the RTU table 27 advance to as yet the not next RTU (step 213) of inquiry.The station, regional center (RC) checks whether " window " timer WWWW finishes (step 214), if do not finish, it is without the next RTU of time-delay ground from the step 207 beginning questionnaire.After having inquired some RTU, " window " timer will finish and the time-delay of this area's central station will become maximum (step 215).This also is shown in the row 103 of table 1 to station, first regional center (RC) 13.The station, regional center (RC) starts window timing device (216) and new back off timer (217).The station, regional center (RC) checks whether it receives what on channel between new time delay, and has received activity really as if it, so the length of its Survey Operations.If this length greater than 0.7 " window " time (218), is just being carried out its inquiry circulation just represent another station, regional center (RC), therefore, one " window " finished at relevant 13 other stations, regional center (RC) (as 14) of wait, station, regional center (RC).In view of the above, channel becomes empty (221), and this area's central station is with its oneself the back off timer interval (222) (shown in the row in the table 1 105) that shortens.Another judges circulation from step 216 beginning at station, regional center (RC) 13, but its back off timer is shorter specifically.If in step 217 new shorter time-delay is arranged, the station, regional center (RC) just can not receive any other unit so, and it continues through step 218 and 219 to 220, and begins its a new inquiry circulation.
Arrive this, a kind of algorithm has been described, this algorithm is to realize with software program at the each department central station on the basis of circulation time-delay, wherein the station, regional center (RC) by each other coequally interleave inquiry request be able to synchronously, thereby these center cells can upgrade their database in the time that equates.
In addition, station, a regional center (RC) can add competition at any time and with channel on other unit " synchronously " mutually, and begin its time-delay and always be different from the time-delay of delaying time in any other unit when becoming empty by starting one from channel, avoid conflict.All unit all begin their time-delay simultaneously, and all there is variable but always unique time-delay each unit.
Claims (6)
1. the method that the contention communication channel inserts is characterized in that, may further comprise the steps:
Receive the instruction of a beginning contention;
From one group of time-delay, select a time-delay;
After selected time-delay, send a channel and insert request;
If receive the channel authorization instruction, just be that contention is selected the longest time-delay next time;
If do not receive the channel authorization instruction, just be that contention is selected short time-delay next time.
2. according to the method for claim 1, it is characterized in that, further comprising the steps of: supervisory channel; Start a timer when detecting unoccupied channel, this timer has been counted the back and has been sent this channel access request in this time delay.
3. the communication unit in order to communicate with another unit on a channel is characterized in that, comprising:
Be used for the device that contention channel inserts;
The device that is used for the receive channel authorized order; And
Be used for once the device of receiving that this instruction sends to other unit,
Wherein the contention device comprises time-delay mechanism, be used for postponing contention from one group of a period of time of delaying time and selecting, wherein after being next to once successful contention, for the selected time-delay of next contention is elder in the time-delay of this group, wherein after once not successful contention, be the short time-delay of contention selection next time.
4. a communication system comprises a primary unit and first and second secondary units, and wherein first and second secondary units are in order to communicating by letter with this primary unit on a channel,
Primary unit comprises:
Be used to send a beginning contention instruction device and be used for the channel authorization instruction is sent to the device of selected secondary units;
Each secondary units comprises:
Be used to receive a device that begins the instruction of contention;
It is characterized in that;
Time-delay mechanism responds the reception of this instruction, in order to a period of time that postpones to select from one group of time-delay;
Monitoring device is used for determining whether channel is empty;
Dispensing device if it is still empty to be used for when selected delay cycle finishes channel, then sends to primary unit;
Time-delay increases device, and being used for increases the time-delay that the next one is sent when sending when taking place;
Time-delay reduces device, is used for reducing when not taking place the time-delay that the next one is sent;
Wherein the time-delay in the time-delay group of Unit first and second is different.
5. according to the system of claim 4, it is characterized in that the time-delay of the time-delay group of first module is staggered with respect to the time-delay of the time-delay group of Unit second.
6. according to the system of claim 4, it is characterized in that, also comprise each a plurality of secondary units that are associated with first and second primary units, each secondary units all is useful on the device that its corresponding relevant primary unit communicates, and main center transmitter, be used for an instruction is sent to first and second primary units and a plurality of secondary units, to open beginning action in secondary units, wherein each primary unit all is useful on the described instruction of response and sends the device of described instruction to begin to compete.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN93107408A CN1037480C (en) | 1993-06-23 | 1993-06-23 | Method and apparatus for contending for access to a communication channel |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN93107408A CN1037480C (en) | 1993-06-23 | 1993-06-23 | Method and apparatus for contending for access to a communication channel |
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| CN1096911A CN1096911A (en) | 1994-12-28 |
| CN1037480C true CN1037480C (en) | 1998-02-18 |
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| CN93107408A Expired - Fee Related CN1037480C (en) | 1993-06-23 | 1993-06-23 | Method and apparatus for contending for access to a communication channel |
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| US8243690B2 (en) * | 2008-07-09 | 2012-08-14 | Intel Corporation | Bandwidth allocation base station and method for allocating uplink bandwidth using SDMA |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2063011A (en) * | 1979-11-09 | 1981-05-28 | Philips Electronic Associated | Information transmission system |
| EP0094180A2 (en) * | 1982-05-07 | 1983-11-16 | Digital Equipment Corporation | Dual-count, round-robin distributed arbitration technique for serial buses |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2063011A (en) * | 1979-11-09 | 1981-05-28 | Philips Electronic Associated | Information transmission system |
| EP0094180A2 (en) * | 1982-05-07 | 1983-11-16 | Digital Equipment Corporation | Dual-count, round-robin distributed arbitration technique for serial buses |
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| CN1096911A (en) | 1994-12-28 |
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