CN1223761A - Process and arrangement for operation of time division multiple access (TDMA) radio systems - Google Patents
Process and arrangement for operation of time division multiple access (TDMA) radio systems Download PDFInfo
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- CN1223761A CN1223761A CN 97195862 CN97195862A CN1223761A CN 1223761 A CN1223761 A CN 1223761A CN 97195862 CN97195862 CN 97195862 CN 97195862 A CN97195862 A CN 97195862A CN 1223761 A CN1223761 A CN 1223761A
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Abstract
The invention relates to a process and an arrangement for interference-free operation of TDMA radio systems, in particular for cordless communication systems in accordance with the DECT standard. An interference occurring in a first TDMA radio system which is caused by a lack of synchronism of the time bases of the first and at least one other TDMA radio system, is initially detected. The interference is subsequently suppressed according to the invention in that the time bases of the asynchronous TDMA systems affecting each other mutually are automatically synchronised. For this purpose, the frequency of the time base of at least one of the two TDMA radio systems contributing to the interference is adapted in such a manner that the time bases of the TDMA radio systems operate in synchronism. Firstly, the time overlap of the time zones associated with each established connection is eliminated by the single shifting of the TDMA frames (F1, F2), relative to one another, associated with the frequence adaptation, and consequently the resulting interference suppressed. Secondly, a further time drift of the associated TDMA frames (F1, F2) towards each other is eliminated by the automatic synchronisation and consequently the cause of possible further interference removed from the start. Said process is also advantageous in that changing the channel frequently, and disadvantages associated therewith, can be avoided.
Description
The present invention relates to a kind of TDMA of being used for wireless communication system, especially in wireless communication system according to dect standard, the method and apparatus of trouble-free operation.
Demand in the present information transmission system is to require minimum frequency bandwidth to transmit the language and the data message of maximum economically.As wireless communication system, such requirement has special meaning.Because just must limit their width and can use frequency spectrum especially economically technically for such requirement.In many cases, therefore people use said multiple transmission method, and making with this method becomes possibility by a common transmission channel with multiplex telephony and the common transmission of multiple data stream.
To this, people are divided into two kinds of multiple transmission methods in principle, frequency division multiplexing method and time-division multiplex transmission method.
Frequency division multiplexing FDM is based on a plurality of identical frequency ranges (channel) and segments existing frequency band.Thereby each frequency range can be used as such as one tunnel phone transmission.The FDM method is mainly used in transmission of analogue signal.
Time-division multiplex transmission TDM method is only applicable to digital signal antithesis.To this, with a plurality of as being merged into a common transmission channel such as the single channel that transmits by a cable or wireless communication line, the digital data stream of at this moment waiting in each single channel is subdivided into individual data bag (position hardwood Bitrahmen), and these different single pass positions hardwoods are integrated into transmission hardwood (uebertragungsrahmen) separately, with its serial, promptly on transmission line, transmit one by one then.For this reason, in each transmission hardwood, give single channel time slot of fixed allocation separately, and utilizing the corresponding single pass position of transmission hardwood under all available at any time frequency bandwidth therein.In receiver, more single receive path is selected and distributed to data from the time slot of transmission hardwood.
Use these two kinds to be called multiplex techniques and can to make the communication port number increase several times, thereby and improved its economy as transmission line.In addition, in wireless communication system, generally also requirement adopts the passage of multiple transmission method to use for number of users as much as possible by one.For this reason, use said multiple access " multiple access ", it both can also can be in TDM in FDM.Corresponding system is referred to as FDMA system and tdma system (frequency division multiple access and time-division multiple access (TDMA)).Only relate to below tdma system or complexity by the corresponding TDMA level in the multistage wireless communication system of forming with different multiplex techniques (for example, at the DECT wireless communication system).
For example, a TDMA wireless communication system moves near the tdma system of another use same frequency band in the cellular communications system that a higher level is made of a plurality of such systems, will produce the phase mutual interference so.The infringement of the transmission quality of wanting to avoid such, will be when setting up a new communication, in a subsystem, constantly select a TDMA passage, its time slot in TDMA transmission hardwood uses single pass time slot to stagger for the while at another TDMA subsystem in time, and does not therefore disturb fully.
, for example based on dect standard, nonsynchronous TDMA wireless communication system has such shortcoming, promptly aspect the traverse accuracy, as the time base of the single tdma system of clock signal generator have permissible error (in DECT, for+/-5ppm).Therefore, produce the TDMA hardwood structure relative time drift each other of two systems usually.So actually mark moves and can cause, beginning independently, be to set up communication in the interference-free time zone of TDMA hardwood, can be gradually arrive the time zone that has used, and can cause in this system interference thus respective communication by another tdma system.This interference yet can involve other wireless communication in other wireless communication systems according to situation.
Conventional method (as in DECT) is to identify when disturbing, and as if possible, tdma system is avoided by replacing wireless communication (" transfer ").But to this, it is essential continuously having a untapped wireless communication of not disturbed.In addition, if do not produce interruption for the user does not perceive the replacing passage, changing passage has another shortcoming, promptly needs two wireless communication simultaneously for short time replacing passage.Therefore, can cause load peak through frequent the replacing very soon when passage occupies wireless communication together, and cause causing that passage blocks.Yet existing is not a communication of being disturbed continues conducting on an interference-free passage possibility, in this case even can cause communication disruption.
Task of the present invention is, a kind of method that is used for the trouble-free operation of TDMA wireless communication system that overcomes above-mentioned shortcoming is provided.
This task is finished by a kind of method of alleged feature that is included in the claim 1.The device that is used to implement this method is that claim 8 is described.
With different in traditional TDMA wireless communication system, in that system, stand foregoing shortcoming, by on another wireless communication, continuing to be subjected to interfere with communications, avoid passage interference, being used for TDMA wireless communication system operation method characteristics according to the present invention is to have eliminated the cause of disturbing.
To this, identify at first in present first TDMA wireless communication system by this first and at least another TDMA wireless communication system the time base the interference that causes of shortage synchronization.For instance, in the DECT system, the identification of " conflict of sliding " of being called like this is relevant with standard, and a hardwood that is transmitted in tdma slot has specific field separately, compares the staggered drift that can discern different system TDMA hardwood at receiver by it.
Then, remove interference according to the present invention, wherein, with the time basic forced synchronism of interactional nonsynchronous tdma system.For this reason, at least one the frequency in per two tdma systems that relate to interference is so adapted to, though the TDMA wireless communication system the time base synchronously.At first, the TDMA hardwood by system with respect to another, single move relevant with frequency adaptation, eliminate and distribute to the time-interleaving that each oneself has the time period of communication, and therefore get rid of the interference that has taken place.Secondly, also eliminate the relative further time drift of TDMA hardwood of subordinate by forced synchronism, and therefore from beginning to have eliminated the cause of said possible other interference.
In addition, the advantage of this method is, overcome saidly to change relevant shortcoming with passage.
According to Claim 8, the tdma system that is used to implement the inventive method comprise one as the time timer that has variable frequency of base and one be used for determining the checkout gear of the TDMA hardwood structure of this system with respect to the time drift of the TDMA hardwood structure of another TDMA wireless communication system.Interference in the TDMA wireless communication system is by means of checkout gear identification, and this interference is that the time drift by the TDMA hardwood of the TDMA wireless communication system of relative one the 2nd a TDMA wireless communication system causes.The correspondent frequency of the time generator by system changes to make and system synchronization in other words, makes the coadaptation of corresponding timebase frequency phase.At this, this is realized by suitable method when confirming to relate to the system mutual time drift of interference synchronously automatically.And can by by in per two systems at least one the time base frequency shift reach.
Preferential other construction and devices of the present invention are described by dependent claims.
According to first kind of structure-claim 2-of the present invention at least one such TDMA wireless communication system, according to the destruction of the last position of a position hardwood that in tdma slot, transmits/last several, identification by one first and at least one another TDMA wireless communication system the time base the shortage synchronization and produce interference.Thus, might assert " conflict of sliding " early, in this conflict, the time slot of the TDMA hardwood structure of a system that by chance uses thrusts one's way on the TDMA of another system that takies equally hardwood structure time slot, because at first in " slower " system, always will destroy the last position of in disturbed time slot, transmitting the position hardwood.
Correspondingly, other device-claims 3-according to the present invention conforms with purpose, and each position hardwood that transmits in tdma slot comprises a field at its end, and it only contains redundant information and/or to the valid data unwanted information of communicating by letter.For example, this has made corresponding regulation for the DECT system in standard.
In another device of the present invention-adaptation of claim 4-TDMA wireless communication system timebase frequency repeats with small step mutually.Wherein, by such re-adjustments frequency change, the difference on the frequency of base when promptly eliminating on the one hand; Then, related on the other hand system realizes neither the transition compensation but greatly degree synchronously.In addition, prevent the unexpected desynchronize of transmitter and receiver in the TDMA wireless communication system by stepping ground frequency adaptation, and with this prevent the interruption of respective communication, in short-term interrupt or at least passage change.For example, in the DECT system, continuing under the prerequisite of communicating by letter between base station and the moving device, can realize the frequency change that repeats, and having only when once bigger frequency jump, moving device just must set up and new the getting in touch of a base station in order to continue by communication.
Equally, in order to prevent information dropout, suitable is-always carry out the frequency change according to claim 5-at time window, wherein, in related tdma system, do not carry out transfer of data.General this time window is provided between the single single channel of TDMA hardwood by alleged guard time (guard space).
If another priority structure-claim 6-makes the mutual interference of TDMA wireless communication system phase owing to employed TDMA wireless communication is overlapping according to the present invention, when the synchronously required frequency change value of the time base of disturbed TDMA wireless communication system surpasses the limiting value of regulation, then relate in the system at a quilt at least, transfer to another enough not disturbed wireless communication from disturbed wireless communication.Therefore, with assigned frequency foregoing frequency adaptation is limited in desirable, the frequency range that can realize and stipulate, and prevents to cause frequency change out of control and hopeless elimination is disturbed such as the influence that causes by any one external disturbance to tdma system.
During another constitutes in the present invention-claim 7-finishes each radio communication in the TDMA wireless communication system after, the frequency that changes of base is returned to its original value before the frequency adaptation more at that time.Get rid of whereby, continue selected frequency to one such as the tdma system of regulating with maximum authorized frequency correction value, this consequence that can cause is, for further frequency adaptation leeway in adjacent system can be restricted widely, and make that therefore the synchronous possibility of a plurality of systems also is restricted greatly in selected frequency system scope.
Below in conjunction with accompanying drawing, be that example further specifies the present invention with the DECT system.
Fig. 1 is according to the structure of dect standard at the time slot meta hardwood of a TDMA hardwood;
Fig. 2 schematically illustrates the formation of " conflict of sliding ";
Fig. 3 is used for handling the flow chart of " conflict of sliding " according to method of the present invention.
In dect standard, by arranging frequency band segmentation, by means of 10 branch frequency bands of FDMA definition, and to this minute frequency band segment again, each defines 24 passages by means of TDMA, defines 240 passages altogether.Thereby each TDMA hardwood (transmission hardwood) is made of 24 time slots.For two-way communication, comprehensively be a full-duplex channel with per two passages, produced 120 full-duplex channels so altogether.Calling the DECT multiframe by the time last level structure that forms that is arranged in rows by the TDMA hardwood that will transmit successively.
In Fig. 1,,, the structure of a position hardwood that transmits has been described in the time slot of TDMA hardwood with alleged full-time crack mode, operational mode that the DECT system is the most general as the DECT system.Transmit position hardwood 416 μ s, and length is 480.The synchronization field S that is included in 32 of beginnings regains with synchronously with the clock pulse of every the hardwood receiver of opposing.The header field A that follows 64 bit lengths thereafter comprises and sends signal data and control data.Valid data field B with 320 bit lengths transmits actual valid data.As the present invention, at first meaningfully add field X and the Z that has 4 bit lengths separately.The end of every hardwood also is connected guard time GS, and in DECT, it is 50 μ s.X field is determined by special parity, is called the position acquisition that " cyclic redundancy check " selected from the B field, and at this point with the indicating device of doing the defective transmission of B field.By X field doubled to form the Z field.It comprises foregoing redundant data and is used for the nonsynchronous DECT of identification system on every side.Therefore, the content with the X field of the content of Z field and prospect in receiver compares, and this is checked by deviation is added up repeatedly.If system deviation occurs, so just think and discerned " conflict of sliding ", and begin to use the measure of disturbing of eliminating.The present invention in conjunction with Fig. 2 and Fig. 3 description will further relate to below for this point.Except X field and Z field, they are used for outside the end point detection interference of hardwood on the throne, and the S field of beginning place of each hardwood also can be used for disturbing in the detection at the beginning of hardwood.
Fig. 2 briefly describes the formation of " conflict of sliding " and presses its removing of the present invention.
Component among Fig. 2 (a) has been showed a DECT transmission hardwood F1 who is made of 24 time slots.The time slot of being emphasized 10 just is used as the radio communication between the base station and moving device in a DECT system (as using passage 22 with moving device-base station of its relative direction, it constitutes a full-duplex channel with path 10).
In the component of Fig. 2 (b), as instant t
1, the 2nd a DECT system transmissions hardwood F around the first existing DECT system has been described
2Fragment, wherein just time slot 12 (with time slot 24) is occupied by conversation.Each of two DECT systems accounted for path 10 and 12 (with 22 and 24), and life period is not overlapping, does not therefore disturb.
In general, the DECT system the time base internal clock pulse in the margin of tolerance of regulation, have a standardized setting deviation.Two DECT systems the time can cause drift thus between the base, it has caused the TDMA hardwood structure (DECT multiframe) of two systems to move mutually.Thus, two systems in time originally the time slot of mutual dislocation cause covering on the part-time at least, thereby can produce the phase mutual interference.
This situation is described in the component (C) of Fig. 2.The clock pulse of second system takes place with the frequency of the clock pulse of a little higher than first system, reaches certain t in a flash like this
2＞t
1The time just produced path 10 and 12 time go up overlapping.In first system, destroy according to the last position of every position hardwood that in path 10, transmits, also " slide and conflict " according to the relatively identification of X field and Z field.
Component among Fig. 2 (d) and component (c) have been showed together by means of frequency adaptation of the present invention, the situation after two system's forced synchronism.Wherein, for example, can be separately to the first, promptly " slower " system carries out the frequency upgrading generation synchronously.First system is foregoing, more Zao than desynchronize immediately following synchronously nearest position hardwood (and to this, all DECT multiframes) beginning, so overlapping and interfering with each other and will get rid of thus between two system channels 10 and 12.Because base is synchronous operation to the full extent when being two now, other are overlapping to have repelled generation, are obviously to delay at least.
Fig. 3 describes the method that is used for handling " conflict of sliding " according to the present invention in detail according to flow chart.
In tdma system, in step 1, for example resemble the DECT system situation of having described in the above, by means of " conflict of sliding " the identification interference that destroys according to single position or whole field of the position hardwood that in a tdma slot, transmits.In order to distinguish " conflict of sliding " disturbed by other reasons, for example utilize the faults that occurs in a plurality of in succession position hardwoods of time slot each other added up repeatedly and test.So, the frequency shift of base when the first correction step 2 is carried out system.See situation and decide that whether the top or terminal appearance of hardwood on the throne destroy, to this, correspondingly described in the drawings or frequency descends or frequency upgrading, also produces the frequency that partly adapts to EVAC (Evacuation Network Computer Model) at least.Wherein, all frequency shifts that take place in synchronizing process are always carried out in moment.In system, do not transmit data in this moment, also in the terminal guard time of every time slot, carry out in suitable mode.In next step 3, check, the frequency correction value DF that whether accumulates through whole correction steps has surpassed the maximum DF that determines
MaxProper be to select for the first time correction less than DF
Max(in DECT, at output frequency, the suitable order of magnitude is about 1ppm) can carry out step 4 like this.Here according to the next one after correction in the position hardwood check that its single channel receives, district on the throne whether, also the quantity m of the vicious position in S field and Z field is no more than fixed threshold value S in the DECT system
1(for example select S
1=2).If it also is not like this, just also do not reach synchronously, then by turning back to step 2 beginning with another frequency correction iteration.Another situation is in step 5, by means of relatively, with other second threshold value S
2(use S
2＞S
1) quantity of the faults that also stays of test, whether there is the filtration compensation of original frequency difference.For example a faults (S ought no longer appear
2=1), just accepts such transition compensation.Then, revise in that step 6 cancellation part is last, and turn back to step 4 and carry out new check.Yet the quantity m of the faults that stays is by threshold value S
1And S
2The margin of tolerance of setting can at utmost realize desirable synchronous so at least.In step 7, the finishing cancel all that will carry out during the end of each communication in system is to avoid to adjacent system the cline frequency advantage of update the system.If confirm in step 3 modification method result, surpassed the maximum Dfmax that determines as the frequency correction of carrying out synchronously, in step 8, under the condition of cancellation all frequency corrections of carrying out hereto, passage is replaced with a still undisturbed passage (" transfer ") like this.
Claims (8)
1. be used for the TDMA wireless communication system, especially according to the method for the wireless communication system of dect standard operation, wherein, so be identified in and occur in the TDMA wireless communication system, and disturb by the wireless communication that the time drift with respect to the TDMA hardwood (F1) of the TDMA wireless communication system of the TDMA hardwood (F2) of the 2nd TDMA wireless communication system causes, it is characterized in that, eliminate interference by forced synchronism, wherein, timebase frequency to major general's one in two TDMA wireless communication systems so changes, promptly make two TDMA wireless communication systems the time base synchronously.
2. according to the method for claim 1, it is characterized in that according to last/last several destruction of a position hardwood that transmits, identification is disturbed in tdma slot (1 to 24).
3. according to the method for above-mentioned arbitrary claim, it is characterized in that, in the TDMA wireless communication system, the position hardwood that each transmits in tdma slot (1 to 24), at its end a field (Z) is arranged, it only contains redundancy and/or to the valid data unwanted information of communicating by letter.
4. according to the method for above-mentioned arbitrary claim, it is characterized in that the adaptation of TDMA wireless communication system timebase frequency repeats with small step mutually.
5. according to the method for above-mentioned arbitrary claim, it is characterized in that, carry out the frequency change, wherein, in related tdma system, do not carry out transfer of data at time window.
6. according to the method for above-mentioned arbitrary claim, it is characterized in that, when for make two TDMA wireless communication systems time base synchronously, when needed frequency change (DF) value surpasses the limiting value (DFmax) of regulation, in a TDMA wireless communication system, from disturbed wireless communication (10), transfer to another enough not disturbed wireless communication at least.
7. according to the method for above-mentioned arbitrary claim, it is characterized in that, in the TDMA wireless communication system, finish each wireless connections after, with at that time the base the frequency that changes be returned to its original value again.
8. be used to implement above-mentioned arbitrary claim method, especially follow the tdma system of dect standard, it is characterized in that,
-this TDMA wireless communication system comprise one as the time base timer, its frequency is at least in a restricted portion, and is variable with the frequency values of regulation;
-this TDMA wireless communication system can pass through a checkout gear, is used for determining the time drift of its TDMA hardwood structure with respect to the TDMA hardwood structure of another tdma system;
-the interference that causes by such drift by means of checkout gear identification, and by means of two systems synchronously when corresponding the mutual frequency adaptation of base eliminate this interference.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97195862 CN1223761A (en) | 1996-07-25 | 1997-06-30 | Process and arrangement for operation of time division multiple access (TDMA) radio systems |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19630048.7 | 1996-07-25 | ||
| CN 97195862 CN1223761A (en) | 1996-07-25 | 1997-06-30 | Process and arrangement for operation of time division multiple access (TDMA) radio systems |
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| Publication Number | Publication Date |
|---|---|
| CN1223761A true CN1223761A (en) | 1999-07-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 97195862 Pending CN1223761A (en) | 1996-07-25 | 1997-06-30 | Process and arrangement for operation of time division multiple access (TDMA) radio systems |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101647263B (en) * | 2007-03-16 | 2013-07-10 | 技嘉斯特通讯股份有限公司 | Device and method for controlling the creation of a user channel connection in a communication system and associated communication system, digital storage medium, computer program product, and compute program |
-
1997
- 1997-06-30 CN CN 97195862 patent/CN1223761A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101647263B (en) * | 2007-03-16 | 2013-07-10 | 技嘉斯特通讯股份有限公司 | Device and method for controlling the creation of a user channel connection in a communication system and associated communication system, digital storage medium, computer program product, and compute program |
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