CN1340250A - Method and device for synchronizing a receiver with a transmitter - Google Patents

Abstract

The invention relates to a method and a device for temporally synchronizing a receiver with a transmitter in a telecommunication system, especially a mobile radio system. Synchronization takes place if a predetermined requirement is met, using at least two physical channels of the telecommunication system in parallel by making separate correlation evaluations in said channels.

Description

Make receiver follow the synchronous method and apparatus of transmitter

The present invention relates to a kind of especially for making in the digital carrier system of mobile radio system receiver follow that transmitter/synchronous method transmits, wherein said method has a kind of by adopting at least one to carry out the step that tuning filter is implemented time synchronized by predetermined synchronous code, the invention still further relates to the device of this method of execution in addition.

Be known in and adopted physical channel to come transport communication information and synchrodata in the information transmission system.By adopting this physical channel, can from transmitting station to receiving platform, especially use wireless method from first radio station to second radio station's transmission of digital message and the synchronizing signal.

In transmission or communication system according to DS-CDMA principle (direct sequential encoding spread-spectrum principle) work, the digital information signal of low bandwidth is to utilize the high frequency bit stream of high bandwidth to modulate.This bit stream utilizes the extended code generator to produce.In receiver, produce a kind of code sequence identical, as it is used to modulate in transmitter with this extended code sequence.In order to ensure the correct working method of receiver, the code sequence of this receiver side must be synchronous with described transmitter.So, by separating the information signal that the mediation integration obtains " de-spread ".In signal acquisition phase, described synchronous most important task is to detect the time location and the phase place of synchronizing signal.In addition, working method and agreement according to digital carrier system, also have some other important tasks in addition, undertaken in the system of work by introducing time division multiplexing or TDMA (time division multiple access) viewpoint, described other task especially also comprises slot synchronization and frame synchronization.

In system UMTS/WCDMA-FDD (Universal Mobile Telecommunications System/Wideband Code Division Multiple Access (WCDMA)-Frequency Division Duplexing (FDD)) in the future, suggestion adopts three level methods to carry out in acquisition phase synchronously in existing standard class.When beginning to search the sub-district, search that minimum base station of loss by travelling carriage.Primary synchronization channel (PSCH=primary synchronization channel) and secondary synchronization channel (SSCH=secondary synchronization channel) have been defined for this reason.In the first step, for obtaining to adopt described PSCH with the strongest base station synchronization.By one independent, carry out tuning filter according to Primary Synchronisation Code cp (all is common to all base stations) and measure the peak value that is positioned at each base station within the travelling carriage sphere of action.This position finding to the highest peak value can provide the timing strong basis station, the mould slot length.In order to improve reliability, the output of described tuned filter is carried out adding up on some time slots irrelevantly.

In second step of synchronizing process, for the base station of finding in the first step forms frame synchronization and code group identification, and they are carried out by adopting SSCH.To this, with the received signal of secondary synchronization code cs position be that possible all (being 17 herein) secondary synchronization code are carried out relevant according to system protocol.According to given relation, the details of this step is the same with third step to have only less important meaning, and wherein said third step is to discern the what is called " scrambler " that adopt described determined base station.In system documentation " ETSI STC SMG2 UMTS-L1163/98, the explanation of UTRA/FED physical layer ", once told about the details of these steps for the system that is known as embodiment.

Can draw, for time synchronized has been set a kind of special physical channel that is PSCH.

The present invention based on task be to provide a kind of article to start the method for described type, wherein can utilize the energy of received signal better for time synchronization process, and be that described synchronizing process reduces Measuring Time and current drain thus, another task of the present invention provides a kind of device of carrying out this method.

Aspect described method, this task is realized by the method with the described characteristic of claim 1, and aspect its device, this task is realized by the device with the described characteristic of claim 11.

The present invention includes following basic technical theory, be at least one additional physical channel that time synchronized is used the information transmission system.Come in receiver, to improve energy utilization, the minimizing time consumption of received signal thus and reduce current drain.At this, physical channel is interpreted as such channel, it is characterized in that its frequency, extended code, the time window position or spatial multiplexing state or the like.

Time synchronized especially comprises slot synchronization, but also comprises frame synchronization or sign synchronization.

In a preferred embodiment of the invention, be used as described time synchronized purpose set the synchronizing channel that is used for other purpose by the host-host protocol of the information transmission system.In the system of above being described, this is meant described secondary synchronization channel (SSCH).If, then can put into effect with lower computational costs by utilizing so-called Hadamard sequences to obtain the code word of described secondary synchronization channel from the code of described primary synchronization channel or from other known code.Then,, can analyze, also promptly realize this analysis by so-called " hadamard fast " conversion to the correlation in the described secondary synchronization channel for time synchronized.

But say in principle, also can utilize at least one control channel of system or data channel to carry out time synchronized in addition.This need establish some channel standard.

The method of above-mentioned suggestion comprises: carry out correlation analysis dividually in being used to the channel of time synchronized, and next the analysis result logic being connected into a time synchronized designator.If described system protocol does not have to set fixing reference phase at the interchannel that is used for time synchronized, then described logic connects and can realize irrelevantly.Especially preferredly be, set one during this period and especially be+/-90 ° fixing and/or the reference phase determined, and when launching according to system protocol, also adopt described two channels identical antenna as far as possible, can realize that logic connects by coherent accumulation like this, and realize a kind of irrelevant detection that adds up that is better than thus.

In addition, the preferred version of being advised also provides following possibility, promptly the intermediate object program that is obtained in the described time synchronized step is stored, and uses it for other step, for example is used to discern described scrambler.

The method of above-mentioned suggestion can be nonvolatil, or use according to satisfying predetermined condition, can use-for example can be expressed as especially that signal amplitude surpasses a certain threshold value, the bit error rate surpasses a certain threshold value or the like according to the signal analyticity in the described channel that can be used for time synchronized in principle.

The device of carrying out the inventive method especially is suitable for and is used in the travelling carriage of mobile radio telephone by installing.This device comprises a plurality of correlator levels that are used to analyze and a computing unit that is used to calculate, and described computing unit is according to coming to calculate the time synchronized designator by the selected irrelevant or coherent accumulation algorithm of system protocol from the output of each correlator level.The output signal of described correlator level utilizes linear combination to carry out the logic connection.Can draw following incoherent accumulation method at this:

● balanced combination

● square combination

● system of selection or relevant adding up.

In addition, the advantage of solution of the present invention and profitability thereof can be from dependent claims with hereinafter by drawing the accompanying drawing description of a preferred embodiment thereof.

Accompanying drawing is a kind of schematic diagram, and it will both be used to set forth the embodiment of described method hereinafter, is used to set forth the preferred embodiment of carrying out described method again.

There is shown the device 1 that is used for time synchronized, it can be used as assembly and is installed in according to the UMTS/WCDM-FDD standard carries out in (all not drawing) travelling carriage of work.Received signal x (k) analyzes in primary synchronization channel PSCH and secondary synchronization channel SSCH synchronously.In described primary synchronization channel PSCH, be provided with a correlator level 3.

Described correlator level 3 is that described primary synchronization channel PSCH calculates correlation function (correlation) according to following relational expression: $y_p\left(\mathrm{\κ}\right)=\frac{1}{N}\·\underset{k=1..2560}{\mathrm{\Σ}}{x}^{*}(k+\mathrm{\κ})\·c_p\left(k\right)----\left(1\right),$

Wherein:

N is normalization constants (herein being 2560)

x ^*(k) be the input signal of conjugate complex number

c _pFor (at this, except 256 chips of regulation, other chip in 2560 chips has c corresponding to the Primary Synchronisation Code of UMTS/WCDMA-FDD standard 256 chips _p=0).

Described input signal (stipulates) to be imported into 17 correlators according to the agreement that the hour of log-on point has been done in secondary synchronization channel SSCH, these correlators are to indicate with reference number 5 uniformly in the accompanying drawings.These correlators can be determined described correlation y according to following formula _S ¹(κ) ... y _S ¹⁷(κ), ${y_S}^i\left(\mathrm{\κ}\right)=\frac{1}{N}\·\underset{k=1..2560}{\mathrm{\Σ}}{x}^{*}(k+\mathrm{\κ})\·c_S^i\left(k\right)---\left(2\right),$

Be fit to above to symbol N and x herein ^*(k) explanation also is suitable for simultaneously:

c _s ⁱFor (at this, except 256 chips of regulation, other chip in 2560 chips has c corresponding to one of 17 secondary synchronization code of UMTS/WCDMA-FDD standard 256 chips _s ⁱ=0), according to synchronous code, i=1 ... 17.

Described correlator 3 and 5 output signal be imported into analyze and computing unit 9 in, this analysis and computing unit 9 are according to relational expression $z\left(\mathrm{\κ}\right)=\underset{i}{\max }|y_p\left(\mathrm{\κ}\right)+k\left(y_S^i\left(\mathrm{\κ}\right)\right){|}^2---\left(3\right)$ Coherently or according to relational expression $z\left(\mathrm{\κ}\right)={\left|y_p\left(\mathrm{\κ}\right)\right|}^2+k|\underset{i}{\max }\left(y_S^i\left(\mathrm{\κ}\right)\right){|}^2---\left(4\right)$ Or $z\left(\mathrm{\κ}\right)=\left|y_p\left(\mathrm{\κ}\right)\right|+k\left|\underset{i}{\max }\left(y_S^i\left(\mathrm{\κ}\right)\right)\right|---\left(5\right)$ Calculate overall relevancy z (k) as the time synchronized designator, wherein k is real constant irrelevantly.Described time synchronized designator after carry out adding up of mould slot length in the AG 9 that connects, and in maximum value detector 11, carry out maximum subsequently and detect, consequently synchronous settling time with " the best " base station of mobile radio system.

For the UMTS/WCDMA-FDD system of telling about as embodiment, if by utilizing so-called Hadamard sequences to obtain the code word of described secondary synchronization channel from the code of described primary synchronization channel PSCH or from other known code, calculating when then carrying out correlation analysis in described secondary synchronization channel SSCH will be very simple, wherein said Hadamard sequences is once at the meeting contribution of Ericsson, ETSI SMG2 UMTS L1 outlet group, meeting #6, Helsinki, FI, 8.-1998 advised in September 10.Can adopt fast hadamard transform in this case, and this conversion was told about in above-mentioned publication also.

Embodiment of the present invention are not limited to described these embodiment, but all right-with the form of the corresponding coupling of each system protocol-be applied in very important other digital carrier system of time synchronized of its received signal.

Claims (14)

1. make receiver follow transmitter or the synchronous method that transmits in the information transmission system, the described information transmission system especially is a mobile radio system, and wherein said method has the step of a time synchronized,

It is characterized in that:

For synchronously, adopted at least two physical channels of the described information transmission system mutually concurrently, and carried out correlation analysis dividually, subsequently the analysis result (y of described channel _p(κ), y _S ¹(κ) ... y _S ¹⁷(κ)) logic connects into a time synchronized designator.

2. the method for claim 1 is characterized in that:

Adopt that at least one is established for other purpose, as to have the known at least in part sequence that transmits channel to be used for synchronously.

3. method as claimed in claim 1 or 2 is characterized in that:

Described channel with the known at least in part sequence that transmits is the control channel or the data channel of the described information transmission system.

4. method as claimed in claim 2 is characterized in that:

Described channel with the known at least in part sequence that transmits is the synchronizing channel that is particularly useful for the upper level frame structure.

5. the described method of one of claim as described above is characterized in that:

By utilizing Hadamard sequences to modulate to set up the known codes word of second channel, and carry out correlation analysis in the described second channel by fast hadamard transform.

6. the described method of one of claim as described above is characterized in that:

The agreement of the described information transmission system does not have the fixing reference phase of regulation at the described interchannel that is used for time synchronized, and connects by the incoherent logic that realizes described Multiple Channel Analysis result that adds up.

7. the described method of one of claim as described above is characterized in that:

The agreement of the described information transmission system has been stipulated reference phase fixing or that determine at the described interchannel that is used for time synchronized, and especially also stipulate to launch this channel, and connect by the relevant logic that realizes described Multiple Channel Analysis result that adds up by identical antenna.

8. the described method of one of claim as described above is characterized in that:

The result who is obtained in the described time synchronized step is stored, and use it for other synchronizing step, in particular for frame synchronization.

9. the described method of one of claim as described above is characterized in that:

For parameter, especially signal amplitude or the bit error rate of the signal analyticity that characterizes respective channel, be defined as predetermined condition surpassing or being lower than its threshold value.

10. the described method of one of claim as described above is characterized in that:

According to the parameter of the signal analyticity that characterizes respective channel, especially according to signal amplitude or bit error rate, the analysis result to described channel before described logic connects is weighted.

11. be used to carry out the device of the described method of one of aforementioned claim, it especially is used in the travelling carriage of mobile radio telephone, described device has a receiving unit that is used for some channel, and described channel is used to carry out time synchronized,

It is characterized in that:

(PSCH SSCH) is respectively allocated to a few correlator level (3,5), so that determine the correlation (y of received signal by channel to give the channel of described use _p(κ), y _S ¹(κ) ... y _S ¹⁷(κ)), and after on the described correlator level, connect a kind of computing unit (7), so that calculate time synchronized designator (z (κ)).

12. device as claimed in claim 11 is characterized in that:

It is characterized in that:

Described device is configured to determine and analyzes the interior correlation of primary synchronization channel, so that achieve frame is synchronous or sign synchronization, and be used for determining and the interior correlation of analysis secondary synchronization channel, so that carry out synchronously and/or discern other parameter according to the upper level frame structure, for example identification is by one or more differences but the scrambler group that known code word is formed.

13. device as claimed in claim 12 is characterized in that:

After be connected on AG that is used to add up (9) on the described computing unit (7) and the maximum value detector (11) that links to each other with the output of described AG.

14., it is characterized in that as the described device of one of claim 11～13:

Described computing unit (7) is configured to the output signal (y of relevant or the irrelevant ground described correlator level (3,5) that adds up _p(κ), y _S ¹(κ) ... y _S ¹⁷(κ)).

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