CN102123111A - Channel estimating method and device - Google Patents
Channel estimating method and device Download PDFInfo
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- CN102123111A CN102123111A CN2010100226442A CN201010022644A CN102123111A CN 102123111 A CN102123111 A CN 102123111A CN 2010100226442 A CN2010100226442 A CN 2010100226442A CN 201010022644 A CN201010022644 A CN 201010022644A CN 102123111 A CN102123111 A CN 102123111A
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Abstract
The embodiment of the invention discloses a channel estimating method and device and relates to the field of modern wireless communication so as to solve the problem of inaccurate channel estimation under the condition that the channel environment is case 2 in the specification in the prior art. In a technical scheme provided by the invention, the method comprises the following steps of: receiving signals in advance according to a preset code length; analyzing a training sequence of the signals received in advance and the training sequence of signals which are not received in advance from the signals received in advance; respectively calculating a first channel impulse response and a second channel impulse response correspondingly according to the training sequence of the signals received in advance and the training sequence of the signals which are not received in advance; and selecting one of the first channel impulse response and the second channel impulse response to be used as a final channel impulse response according to preset selection rules. The technical scheme provided in the invention can be applied in the technical field of the channel estimation in a TD-SCDMA (Time Division-Synchronization Code Division Multiple Access) system.
Description
Technical field
The present invention relates to the Modern wireless communication field, relate in particular to a kind of method and apparatus of channel estimating.
Background technology
(Time Division-Synchronous Code Division MultipleAccess TD-SCDMA) in the system, disturbs in order to reduce multiple access, adopts the associated detection technique dividing multi-user in TD SDMA.In associated detection technique, channel estimating is the basis, and the order of accuarcy of channel estimating directly influences the performance of joint-detection.In the TD-SCDMA system, carry out channel estimating by the training sequence midamble sign indicating number that sends, this method needs sign synchronization accurately, and synchronous precision is good more, and channel estimating is just accurate more.But under the communication environment of reality, because the influence of factors such as multipath fading can produce synchronous error usually, this synchronous error can have a strong impact on the accuracy of channel estimating, and then systematic function is produced considerable influence.
In order to overcome the influence of synchronous error to channel estimating, prior art adopts the method that shifts to an earlier date received signal to improve the accuracy of channel estimating.
In realizing process of the present invention, the inventor finds, because the time delay in the 3rd footpath of channel circumstance case2 is approximately 16 chip lengths, be 16chips, when channel circumstance is that the window of case2, received signal is long during for 16chips, if adopt the scheme of received signal in advance, the signal in the 3rd footpath of case2 will exceed the window of received signal, make that the signal that receives is inaccurate, thereby make that the channel estimating of carrying out with this signal is also inaccurate.
Summary of the invention
Embodiments of the invention provide a kind of method and apparatus of channel estimating, can carry out channel estimating more accurately in any channel circumstance.
For achieving the above object, embodiments of the invention adopt following technical scheme:
A kind of method of channel estimating comprises:
Shift to an earlier date received signal according to the code length that sets in advance;
From the described signal that receives in advance, parse the training sequence and the non-training sequence of received signal in advance of received signal in advance;
Training sequence and the described non-training sequence of received signal in advance according to described received signal in advance calculate corresponding first channel impulse response and second channel impulse response respectively;
From described first channel impulse response and second channel impulse response, choose a channel impulse response that conduct is final according to the selection rule that sets in advance.
A kind of device of channel estimating comprises:
Receiving element is used for shifting to an earlier date received signal according to the code length that sets in advance;
Resolution unit is used for parsing the training sequence and the non-training sequence of received signal in advance of received signal in advance from the signal that is received in advance by described receiving element;
Computing unit is used for calculating corresponding first channel impulse response and second channel impulse response respectively according to the training sequence and the described non-training sequence of received signal in advance of the received signal of being obtained by described resolution unit in advance;
First chooses the unit, is used for choosing a channel impulse response that conduct is final according to the selection rule that sets in advance from first channel impulse response and the second channel impulse response that are obtained by described computing unit.
The method and apparatus of the channel estimating that the embodiment of the invention provides, by from the signal that receives in advance, obtaining the training sequence and the non-training sequence of received signal in advance of received signal in advance, and obtain corresponding channel impulse response by described training sequence, from described channel impulse response, select a final channel impulse response, make and adopt when shifting to an earlier date reception programme, can choose channel impulse response more accurately according to the channel circumstance of reality.Solved in the prior art owing to only obtain channel impulse response, made that at channel circumstance be under the situation of case2, the inaccurate problem of channel estimating by the training sequence of received signal in advance.The method and apparatus of the channel estimating that embodiments of the invention provide can carry out channel estimating more accurately in any channel circumstance.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below, apparently, accompanying drawing in describing below is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
The method flow diagram of the channel estimating that Fig. 1 provides for the embodiment of the invention;
Fig. 2 chooses the method flow diagram of channel impulse response for step 104 in the flow chart shown in Figure 1;
The apparatus structure schematic diagram of the channel estimating that Fig. 3 provides for the embodiment of the invention;
Fig. 4 is first structural representation of choosing unit 304 in the apparatus structure schematic diagram shown in Figure 3.
Fig. 5 is that case2, type of service are under the situation of 12.2kbps for channel circumstance, the curve chart of system's block error rate BLER of different channels method of estimation correspondence;
Fig. 6 is that case2, type of service are under the situation of 12.2kbps for channel circumstance, and the system of different channels method of estimation correspondence is without the curve chart of the bit error rate RawBER of chnnel coding.
Embodiment
For the purpose, technical scheme and the advantage that make the embodiment of the invention clearer, below in conjunction with the accompanying drawing in the embodiment of the invention, technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not paying the every other embodiment that is obtained under the creative work prerequisite.
In order to solve prior art is under the situation of case2 at channel circumstance, the inaccurate problem of channel estimating, and the embodiment of the invention provides a kind of method and apparatus of channel estimating.
As shown in Figure 1, the method for the channel estimating that the embodiment of the invention provides comprises:
In the present embodiment, adopt 4 chip lengths in advance, promptly the method for 4chips is come received signal.Owing under the communication environment of reality, signal can produce synchronous error, moves with synchronous right avertence comprising synchronous left avertence and moves.Wherein, synchronous left avertence is moved the accuracy influence of channel estimating bigger, and right avertence is moved the accuracy influence of channel estimating less synchronously.Therefore, in the communication environment of reality, consider factors such as multipath number and multidiameter delay, can adopt the method for 4chips in advance to overcome synchronous left avertence and move influence channel estimation accuracy.Adopting the method that shifts to an earlier date received signal in most of the cases can both obtain the good channel impulse response, is case2 but work as channel circumstance, and performance severe exacerbation can occur on the contrary.This is because the time delay in the 3rd footpath of case2 is 12000ns, and the signal transmitting speed is 1.28 * 10
6Chips/s, therefore the time delay in the 3rd footpath is approximately 16chips.When the window length of received signal also is 16chips, if still adopt the scheme that receives in advance, the 3rd footpath will exceed the window of received signal, can have a strong impact on the accuracy that signal receives.And in the practical communication, receiving terminal does not also know it is which kind of channel circumstance at this moment, therefore still adopts the scheme that receives in advance, and the signal that receives is in advance obtained channel impulse response more accurately through subsequent treatment.
In the present embodiment, described training sequence is the midamble sign indicating number.The midamble sign indicating number is the same with pilot signal, is used for distinguishing many community users, and is used to carry out channel estimating, promptly comes the calculating channel impulse response with it.From the signal that receives in advance, can obtain the midamble sign indicating number and the pairing data division of described midamble sign indicating number of each sub-district, represent with Midamble_ahead and Data_ahead respectively; By the signal that receives in advance, can also parse non-midamble sign indicating number and its corresponding data division of each sub-district when receiving in advance, represent with Midamble and Data respectively.
In the present embodiment, calculate a channel impulse response, represent with H_original_a according to the midamble sign indicating number Midamble_ahead that shifts to an earlier date received signal; Calculate the one other channel impulse response according to the non-midamble sign indicating number Midamble of received signal in advance, represent with H_original.
In the present embodiment, adopt the size of the noise power that compares two channel impulse response correspondences to choose optimum channel impulse response.As shown in Figure 2, the method for specifically choosing optimum channel impulse response comprises:
In the present embodiment, described noise power is without the noise power of eliminating burr in this sub-district.Calculate corresponding noise power respectively by H_original_a and the H_original that is obtained in the step 103, be called first noise power and second noise power.
In the present embodiment, the size of noise power reflects the order of accuarcy of channel impulse response, and the channel impulse response of choosing a less correspondence of noise power is represented with H_original_use as final channel impulse response.The pairing data division of this final channel impulse response is represented with Data_use.Joint-detection and relevant follow-up computing just can have been carried out with H_original_use that gets access to and Data_use.
Fig. 5 and Fig. 6 are the case2 channels in type of service is test result under the 12.2kbps.Wherein, Fig. 5 is the curve chart of system's block error rate BLER of different channels method of estimation correspondence; Fig. 6 is the curve chart of the system of different channels method of estimation correspondence without the bit error rate RawBER of chnnel coding.Three curves 1 among two width of cloth figure, the performance curve of 2,3 systems when expression no synchronous error normal received signal is carried out channel estimating respectively, the performance curve of system when shifting to an earlier date the performance curve of 4chips received signal system when carrying out channel estimating and adopting technical scheme of the present invention to carry out channel estimating.
The method of the channel estimating that the embodiment of the invention provides, by from the signal that receives in advance, obtaining the training sequence and the non-training sequence of received signal in advance of received signal in advance, and obtain corresponding channel impulse response by described training sequence, from described channel impulse response, select a final channel impulse response, make and adopt when shifting to an earlier date reception programme, can choose channel impulse response more accurately according to the channel circumstance of reality.Solved in the prior art owing to only obtain channel impulse response, made that at channel circumstance be under the situation of case2, the inaccurate problem of channel estimating by the training sequence of received signal in advance.
As shown in Figure 3, the embodiment of the invention also provides a kind of device of channel estimating, comprising:
Receiving element 301 is used for shifting to an earlier date received signal according to the code length that sets in advance;
First chooses unit 304, is used for choosing a channel impulse response that conduct is final according to the selection rule that sets in advance from first channel impulse response and the second channel impulse response that are obtained by described computing unit 303.
Further, as shown in Figure 4, described first chooses unit 304 comprises:
Acquiring unit 3041 is used for obtaining corresponding first noise power and second noise power respectively according to first channel impulse response that is calculated by described computing unit 303 and described second channel impulse response;
Second chooses unit 3042, is used for choosing the less noise power of numerical value from first noise power and second noise power obtained by described acquiring unit 3041;
The 3rd chooses unit 3043, is used to choose by described second choose the channel impulse response of the less noise power correspondence of numerical value that unit 3042 obtains as final channel impulse response.
More than Zhuan Zhi specific implementation method can be described referring to step 101 as depicted in figs. 1 and 2～104, step 201～203, repeats no more herein.
The device of the channel estimating that the embodiment of the invention provides, by from the signal that receives in advance, obtaining the training sequence and the non-training sequence of received signal in advance of received signal in advance, and obtain corresponding channel impulse response by described training sequence, from described channel impulse response, select a final channel impulse response, make and adopt when shifting to an earlier date reception programme, can choose channel impulse response more accurately according to the channel circumstance of reality.Solved in the prior art owing to only obtain channel impulse response, made that at channel circumstance be under the situation of case2, the inaccurate problem of channel estimating by the training sequence of received signal in advance.
Technical scheme provided by the invention can be applied to carry out in the TD-SCDMA system in the technical field of channel estimating.
One of ordinary skill in the art will appreciate that all or part of step that realizes in the foregoing description method is to instruct relevant hardware to finish by program, described program can be stored in the computer-readable recording medium, as ROM/RAM, magnetic disc or CD etc.
The above; only be the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; can expect easily changing or replacing, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion by described protection range with claim.
Claims (6)
1. the method for a channel estimating is characterized in that, comprising:
Shift to an earlier date received signal according to the code length that sets in advance;
From the described signal that receives in advance, parse the training sequence and the non-training sequence of received signal in advance of received signal in advance;
Training sequence and the described non-training sequence of received signal in advance according to described received signal in advance calculate corresponding first channel impulse response and second channel impulse response respectively;
From described first channel impulse response and second channel impulse response, choose a channel impulse response that conduct is final according to the selection rule that sets in advance.
2. the method for channel estimating according to claim 1 is characterized in that, the selection rule that described basis sets in advance is chosen a final channel impulse response of conduct and comprised from described first channel impulse response and second channel impulse response:
Obtain corresponding first noise power and second noise power respectively according to described first channel impulse response and described second channel impulse response;
From described first noise power and second noise power, choose the less noise power of numerical value;
The channel impulse response of choosing the less noise power correspondence of described numerical value is as final channel impulse response.
3. the method for channel estimating according to claim 1 is characterized in that, the described code length that sets in advance is 4 chip lengths.
4. the method for channel estimating according to claim 1 is characterized in that, described training sequence is the midamble sign indicating number.
5. the device of a channel estimating is characterized in that, comprising:
Receiving element is used for shifting to an earlier date received signal according to the code length that sets in advance;
Resolution unit is used for parsing the training sequence and the non-training sequence of received signal in advance of received signal in advance from the signal that is received in advance by described receiving element;
Computing unit is used for calculating corresponding first channel impulse response and second channel impulse response respectively according to the training sequence and the described non-training sequence of received signal in advance of the received signal of being obtained by described resolution unit in advance;
First chooses the unit, is used for choosing a channel impulse response that conduct is final according to the selection rule that sets in advance from first channel impulse response and the second channel impulse response that are obtained by described computing unit.
6. the device of channel estimating according to claim 5 is characterized in that, described first chooses the unit comprises:
Acquiring unit is used for obtaining corresponding first noise power and second noise power respectively according to first channel impulse response that is calculated by described computing unit and described second channel impulse response;
Second chooses the unit, is used for choosing the less noise power of numerical value from first noise power and second noise power obtained by described acquiring unit;
The 3rd chooses the unit, is used to choose by described second choose the channel impulse response of the less noise power correspondence of numerical value that the unit obtains as final channel impulse response.
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| CN105024957B (en) * | 2015-08-04 | 2018-03-16 | 北京理工大学 | A kind of direct sequency-code division multiple access uplink channel estimation method and device |
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