Background technology
In wireless communication system, UE (User Equipment, user terminal) and need between the base station some the repeater, driedly put, tower is put etc., and signal that the radiofrequency signal multiplying arrangement comes to be sent UE or base station strengthens and transmit, to guarantee the coverage and the signal quality of communication network.In the construction of mobile communications network, the repeater, driedly put, that tower is put is convenient with its low price, addressing, dispose simple advantage, wide area cover and indoor distribution on obtained a large amount of application.
In FDD (Frequency Division Duplex, Frequency Division Duplexing (FDD)) system, uplink and downlink works is in different frequency ranges.The repeater, driedly put, tower puts and uses uplink and downlink two cover radio systems simultaneously, downlink system amplifies the signal of base station to UE, up-link is amplified UE to signal of base station.This two covers radio system is operated on the different separately frequency ranges simultaneously.
And in the TDD system, uplink and downlink works is in same frequency range.In the repeater, driedly put, in the radiofrequency signal multiplying arrangement such as tower is put, must in the uplink and downlink time slot, the uplink and downlink signal be strengthened respectively and transmit.A kind of method of this mode of operation needs realizes the time synchronized between UE on the transmission link, radiofrequency signal multiplying arrangement, the base station.Have only and realized the precise synchronization between each equipment on the transmission link, could guarantee that the time-division change action of each equipment is consistent, thereby on whole transmission link, realize two-way normal amplification uplink and downlink signals.Otherwise self-excitation can take place and cause system to use in uplink and downlink signals.
In the prior art, adopt two kinds of methods to carry out the time synchronized of TDD system.First kind be base station and repeater, driedly put, the tower place system carries out synchronously with the system clock of GPS (Global Positioning System, global positioning system) respectively, thereby realize base station and repeater, driedly put, between the tower place system synchronously; Second kind be in the repeater, driedly put, the UE or the terminal module of tower place system internal configurations TDD system, by UE or terminal module base station signal decoded and to realize the repeater, driedly put, tower place system and base station synchronously.
The shortcoming of these two kinds of methods is need be in the repeater, driedly put, configuration is used for time synchronized in the tower place system GPS module, UE or terminal module, these modules cost an arm and a leg, and are unfavorable for the repeater, driedly put, the cost control of tower place system.
Summary of the invention
The present invention will solve be need be in the prior art in the repeater, driedly put, problem that the expensive module of tower place system configuration is carried out time synchronized.
The method for synchronous of tdd communication systems of the present invention may further comprise the steps:
Detect the temporal signatures of radio frequency signal;
Detected temporal signatures and synchronous sequence sample are mated, and described synchronous sequence sample is for unique in the minimum period property time quantum of this tdd communication systems and have a temporal signatures of fixed time sequence;
When the match is successful, calibrate local sequential according to the fixed time sequence of synchronous sequence sample.
Preferably, described method also comprises: when coupling is unsuccessful, keep local sequential.
Preferably, described fixed time sequence according to the synchronous sequence sample is calibrated local sequential and is specially:
According to fixed time sequence and the time delay expense of the synchronizing process current sequential of determining system of synchronous sequence sample in the minimum period property time quantum of tdd communication systems;
Local sequential is set to the current sequential of system.
Preferably, described temporal signatures comprises the lasting duration of radio frequency transmissions, duration and/or the combination of the two at interval.
Preferably, described detected radio frequency signal is the base station down signal.
Preferably, the temporal signatures of described base stations detected downstream signal is specially;
The base station down radiofrequency signal is carried out power detection;
Compare according to power detection result and setting threshold, generation can be used for the temporal signatures that compares with the synchronous sequence sample.
The present invention also provides a kind of synchronizer of tdd communication systems, comprises radio-frequency signal detection unit, synchronous sequence sample unit, matching unit and alignment unit, wherein;
The radio-frequency signal detection unit is used for detecting the temporal signatures of radiofrequency signal;
Synchronous sequence sample unit is used for being provided with and storage synchronous sequence sample, and described synchronous sequence sample is for unique in the minimum period property time quantum of this tdd communication systems and have a temporal signatures of fixed time sequence;
Matching unit is used for the temporal signatures and the synchronous sequence sample of the output of radio-frequency signal detection unit are compared, and sends synchronic command to alignment unit when the two mates;
Alignment unit is used for calibrating local sequential according to the fixed time sequence of synchronous sequence sample after receiving synchronic command.
Preferably, described temporal signatures comprises the lasting duration of radio frequency transmissions, duration and/or the combination of the two at interval.
Preferably, described radio-frequency signal detection unit comprises RF envelope detecting circuit and thresholding comparison circuit, wherein:
The RF envelope detecting circuit is used for radiofrequency signal is carried out power detection;
The thresholding comparison circuit is used for the power detection result of RF envelope detecting circuit is compared with the threshold value of presetting, and output characterizes the transistor-transistor logic TTL binary signal that has or not radio frequency transmissions.
Preferably, described matching unit is a waveform analysis device;
Described temporal signatures with radio-frequency signal detection unit output compares with the synchronous sequence sample and is specially: lasting duration, interval duration and/or the combination of the two that waveform analysis device draws radio frequency transmissions by the TTL binary signal of analyzing the output of thresholding comparison circuit compare with the corresponding time sequence feature of synchronous sequence sample.
Preferably, described alignment unit is the cycle counter in cycle for the minimum period property time quantum with tdd systems;
Described fixed time sequence according to the synchronous sequence sample is calibrated local sequential and is specially: cycle counter is set to the pairing count value of time delay expense that fixed time sequence adds synchronizing process.
The present invention utilizes the periodicity sequential of tdd communication systems to arrange, be chosen in only occur once in the minimum period property chronomere and the temporal signatures with fixed time sequence as the synchronous sequence sample, the sequential that obtains communication system in view of the above is to realize synchronously.The present invention directly extracts synchronizing information from radiofrequency signal, do not need GP configuring S module or UE module that synchronous base is provided, do not need radiofrequency signal is decoded and signalling analysis yet, simple in structure and accuracy is high, and reduced the repeater, driedly put, the manufacturing cost of radio frequency signal amplifying device such as tower place system.
Embodiment
In the TDD communication system, radio frequency transmissions is divided into periodic time quantum on time domain, and each time quantum is connected according to fixing sequential organization by some time slots and forms.Different TDD communication systems has different minimum period property time quantums, and the length of each time slot in the minimum period property time quantum and front and back order are by the agreement regulation of TDD communication system.Time slot generally includes the interval and protection interval of radio-frequency transmissions, and the radio-frequency transmissions interval is used for transmitting, and protection makes a distinction the radio frequency transmissions of two time slots at interval.Time slot is divided into ascending time slot and descending time slot, carries out up emission of radio frequency signals in the radio-frequency transmissions interval of ascending time slot, carries out the downlink radio-frequency signal emission in descending time slot radio-frequency transmissions interval, and radiofrequency signal then often is a noise signal in protection at interval.
In each minimum period property time quantum of TDD communication system; some radio-frequency transmissions intervals, protection interval or its combination occur and only occur once; have simultaneously fixing time domain skew in minimum period property time quantum, these radio-frequency transmissions intervals, protection interval or its combination can be used for demarcating the sequential of current TDD communication system.Can carry out according to the sequential of demarcating synchronously.
With the TD-SCDMA system is example, and its minimum period property time quantum is a subframe, and length is 6400chips (chip), i.e. 5ms (millisecond).Figure 1 shows that the subframe structure of TD-SCDMA system and the corresponding interval and protection interval of radio-frequency transmissions thereof; subframe comprises that length is DwPTS (descending pilot frequency time slot), the GP (main protection time slot) that length is 96chips, UpPTS (uplink pilot time slot) and 7 time slot TS0, TS1 to TS6 that length is 160chips of 96chips (chip), and each slot length is 864chips.In 7 time slots, time slot TS0 regulation is distributed to down link, and the TS1 regulation is distributed to up link, and TS2 to TS6 can be set at the upstream or downstream time slot as required.
Time slot TS0, TS1 to TS6 are made of at interval the radio-frequency transmissions interval of 848chips and the protection of 16chips; DwPTS is by the protection interval of 32chips and interval composition of radio-frequency transmissions of 64chips, and wherein the radio-frequency transmissions interval of 64chips is used for transmitting downlink synchronous sequence SYNC-DL; GP is the protection interval of 96chips; UpPTS is made of at interval the protection interval and 32chips of the radio-frequency transmissions of 128chips, and wherein the radio-frequency transmissions interval of 128chips is used for transmitting uplink synchronous sequence SYNC-UL.
As seen; the time domain interval of the 48chips that the protection of 32chips is formed at interval among the protection of 16chips interval and the DwPTS among the TS0 occurs in each subframe and only occurs once; and this time domain is interval fixedly to be appeared between the 848chips and 896chips of subframe, thereby can choose this time domain interval as the synchronous sequence sample.Can be used as the radio-frequency transmissions interval that also has 64chips among the DwPTS of synchronous sequence sample equally, can choose radio-frequency transmissions combination interval and the protection interval in addition and be used as the synchronous sequence sample.
Need to prove that in all examples of the present invention and embodiment, all the starting point with TS0 is the starting point of TD-SCDMA subframe.
Figure 2 shows that the flow process of method for synchronous of the present invention.At step S210, determine the synchronous sequence sample.Select in the minimum period property time quantum of tdd communication systems unique and temporal signatures with fixed time sequence as the synchronous sequence sample.
At step S220, detect the temporal signatures of radiofrequency signal.Detection to the radiofrequency signal temporal signatures is carried out according to selected synchronous sequence sample, for example in the TD-SCDMA system, in selecting by TS0 the protection of 16chips at interval and the time domain interval of the 48chips that the protection of 32chips is formed at interval among the DwPTS during as the synchronous sequence sample, the interval duration between can transmitting to base station down detects; And when the radio-frequency transmissions interval of 64chips is as the synchronous sequence sample in selecting DwPTS, then can the lasting duration that base station down transmits be detected; When selecting radio-frequency transmissions interval and protection combination at interval as the synchronous sequence sample, then to detect the lasting duration and the interval duration of radio frequency transmissions simultaneously, and built-up sequence.
At step S230, judge whether detected temporal signatures and selected synchronous sequence sample mate, if, execution in step S240; If not, keep local sequential.
Matching detection to temporal signatures and synchronous sequence sample carry out according to the temporal signatures that the synchronous sequence sample is had equally; it should be noted that; when the synchronous sequence sample is the combination at radio-frequency transmissions interval and protection interval; whether not only will mate the lasting duration and the interval duration of radio frequency transmissions, it is consistent with the synchronous sequence sample with the order of interval duration also will to mate lasting duration.
Because radio frequency transmissions can be interfered, thereby when coupling, can set certain error range, in error range, then think the two coupling.
At step S240, calculate the current sequential of TDD communication system according to the fixed time sequence of synchronous sequence sample.
Because the synchronous sequence sample has fixed time sequence in minimum period property time quantum, so the sequential that the synchronous sequence sample occurs promptly is its fixed time sequence in the TDD communication system.Consider that the current sequential of TDD communication system is the time delay expense that the fixed time sequence of synchronous sequence sample adds synchronizing process from detecting the needed time delay expense of the synchronous sequence sample synchronizing process that the match is successful.
Computational methods the present invention of synchronizing process time delay expense adopts method same as the prior art, repeats no more herein.
At step S250, be current sequential with local timing alignment.
Below be example with the TD-SCDMA system, a kind of embodiment of method for synchronous of the present invention is described.
Choose two downlink radio frequencies transmit between by the protection of 16chips among the TS0 at interval and 48chips/37.5us (microsecond) the time domain interval that the protection of 32chips is formed at interval among the DwPTS as the synchronous sequence sample; this synchronous sequence sample occurs in each subframe and only occurs once; and fixed-site is between the 848chips/662.5us and 896chips/700us of 5ms subframe, and promptly the synchronous sequence sample ends at the 700us place of whole subframe.
The base station down signal is carried out power detection, the result and the setting threshold of power detection compared, obtain the gap length of per twice downlink radio frequency between transmitting.When the result of power detection is higher than setting threshold, exist downlink radio frequency to transmit; When being lower than setting threshold, then has only noise signal.
Be the permissible error of the match settings ± 2.5us of synchronous sequence sample, the gap length that transmits when twice downlink radio frequency is between the 35us to 40us the time, and the match is successful, and this is spaced apart the time domain interval of above-mentioned 48chips in the subframe.
According to this fixed time sequence of time domain interval in subframe, the interval time that finishes of this time domain is the 700us of subframe as can be known, and then the current sequential of base station is (700us+ Δ t), and wherein Δ t is the time delay expense of synchronizing process.Local sequential is set to (700us+ Δ t), has promptly finished subsynchronous with the base station.
Under the unsuccessful situation of coupling, on last once synchronous basis, keep local sequential.
Figure 3 shows that the structure chart of synchronizer of the present invention.Matching unit 330 is connected with alignment unit 340 with radio-frequency signal detection unit 310, synchronous sequence sample unit 320 respectively.
Synchronous sequence sample unit 320 can allow the user that selected synchronous sequence sample is set, and stores set synchronous sequence sample.
The temporal signatures of the radiofrequency signal of the 310 pairs of receptions in radio-frequency signal detection unit detects, and exports testing result to matching unit 330.Detection to the radiofrequency signal temporal signatures is carried out according to selected synchronous sequence sample, can be the lasting duration of radio frequency transmissions, duration or the combination of the two at interval.
Matching unit 330 will be compared with the synchronous sequence sample of storing in synchronous sequence sample unit 320 by the radiofrequency signal temporal signatures of radio-frequency signal detection unit 310 outputs, sends synchronic commands to alignment unit 340 when the two mates.
Alignment unit 340 according to the fixed time sequence of synchronous sequence sample, considers that the time delay expense of synchronizing process draws the current sequential of TDD system, again with the current sequential of local timing alignment to system after receiving the synchronic command that matching unit 330 sends.
Be the preferred embodiment that example illustrates the above-mentioned synchronizer of the present invention still with the TD-SCDMA system, still select among this embodiment by the protection of 16chips among the TS0 at interval and the time domain interval of the 48chips that the protection of 32chips is formed at interval among the DwPTS as the synchronous sequence sample.Therefore this time domain interval only needs downlink radio-frequency signal to the base station detect and gets final product between between the downlink radio frequency emitter region of TS0 and DwPTS.
See also Fig. 4, RF envelope detecting circuit 311 and thresholding comparison circuit 312 are used for realizing the radio-frequency signal detection unit, and wave analyzer 331 is used for realizing matching unit, and cycle counter 341 is used for realizing alignment unit.RF envelope detecting circuit 311 and thresholding comparison circuit 312 interconnect, RF envelope detecting circuit 311 received RF signals wherein, and thresholding comparison circuit 312 is connected to wave analyzer 331.
The radiofrequency signal of 311 pairs of receptions of RF envelope detecting circuit is carried out power detection, and exports the result of power detection to thresholding comparison circuit 312 with analog voltage signal.
Thresholding comparison circuit 312 will reflect that power detection result's analog voltage signal and the threshold value of presetting compare, and export a TTL (Transistor-Transistor Logic, transistor-transistor logic) voltage signal.Default threshold value is corresponding to certain radio-frequency power value, is used for distinguishing transmitting and noise.The radiofrequency signal performance number of the corresponding current input of analog voltage of RF envelope detecting circuit 311 outputs, when analog voltage is lower than this default thresholding, output TTL low level, i.e. the radiofrequency signal of current input is a noise; When being higher than this default thresholding, output TTL high level, i.e. the radiofrequency signal of current input is the downlink signal of base station.Through thresholding comparison circuit 312, the analog voltage that characterizes the radio-frequency input signals watt level is converted into and characterizes the TTL binary signal that has or not base station down to transmit.
Thresholding comparison circuit 312 exports the TTL binary signal to wave analyzer 331.Wave analyzer 311 detects the rising edge and the trailing edge of this TTL signal under the driving in local clock source, and is the low duration timing of count pulse to the TTL signal, i.e. the interval duration of calculation base station downlink signal with the local clock source.With ± 2.5us is the permissible error of coupling, and when the low duration of TTL signal was certain value between the 35us to 40us, the match is successful, and this moment, wave analyzer 331 sent a lock-out pulse as synchronic command to cycle counter 341.
Cycle counter 341 is with the minimum period property time quantum of TD-SCDMA system, and promptly the duration 5ms of its subframe carries out cycle count in the cycle, and its count pulse is the local clock source.If Δ t is the time delay expense of synchronizing process, f is the operating frequency in local clock source, and then behind the lock-out pulse of receiving wave analyzer 331, cycle counter 341 its current count values are set to (700us+ Δ t)/f, thereby realization and base station is synchronous.
The present invention utilizes the periodicity of TDD communication system signal and the temporal signatures that has thereof, and directly extracts synchronizing information by radio frequency detection mode from radiofrequency signal, does not rely on other synchronization modules and merge module, as GPS module or UE module; The present invention utilizes the time domain variation characteristic of radiofrequency signal power level, obtaining synchronizing information by Waveform Matching carries out synchronously, do not need radiofrequency signal is decoded and signalling analysis, and each minimum period property time quantum just realizes that one is subsynchronous to have very high synchronization accuracy.
The present invention can realize with software, also can realize with hardware as the preferred embodiment of synchronous device.Simultaneously, the present invention can be applied to the repeater, driedly put, on the radio frequency signal amplifying device such as tower place system.
Above-described embodiment of the present invention does not constitute the qualification to protection range of the present invention.Any any modification of being done within the spirit and principles in the present invention, be equal to and replace and improvement etc., all should be included within the claim protection range of the present invention.