CN102123111B - Channel estimating method and device - Google Patents
Channel estimating method and device Download PDFInfo
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- CN102123111B CN102123111B CN201010022644.2A CN201010022644A CN102123111B CN 102123111 B CN102123111 B CN 102123111B CN 201010022644 A CN201010022644 A CN 201010022644A CN 102123111 B CN102123111 B CN 102123111B
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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 Modern wireless communication field, relate in particular to a kind of method and apparatus of channel estimating.
Background technology
In TD SDMA (Time Division-Synchronous Code Division MultipleAccess, TD-SCDMA) system, in order to reduce multiple access, disturb, adopt associated detection technique dividing multi-user.In associated detection technique, channel estimating is basis, and the order of accuarcy of channel estimating directly affects the performance of joint-detection.In TD-SCDMA system, by the training sequence midamble code sending, carry out channel estimating, the method needs sign synchronization accurately, and synchronous precision is better, and channel estimating is just more accurate.But under actual communication environment, due to the impact of the factors such as multipath fading, conventionally can produce synchronous error, this synchronous error can have a strong impact on the accuracy of channel estimating, and then systematic function is produced to considerable influence.
In order to overcome the impact of synchronous error on channel estimating, prior art adopts the method receive in advance signal to improve the accuracy of channel estimating.
In realizing process of the present invention, 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 the long 16chips of being of window of case2, reception signal, if adopt the scheme that receives in advance signal, the signal in the 3rd footpath of case2 will exceed the window that receives signal, make the signal that receives inaccurate, thereby make the channel estimating of carrying out with this signal also inaccurate.
Summary of the invention
Embodiments of the invention provide a kind of method and apparatus of channel estimating, can in any channel circumstance, carry out channel estimating more accurately.
For achieving the above object, embodiments of the invention adopt following technical scheme:
A method for channel estimating, comprising:
According to the code length setting in advance, receive in advance signal;
From the described signal receiving in advance, parse the training sequence and the non-training sequence that receives in advance signal that receive in advance signal;
According to described training sequence and the described non-training sequence that receives in advance signal that receives in advance signal, calculate respectively corresponding the first channel impulse response and second channel impulse response;
According to the selection rule setting in advance, from described the first channel impulse response and second channel impulse response, choose a channel impulse response that conduct is final.
A device for channel estimating, comprising:
Receiving element, for receiving in advance signal according to the code length setting in advance;
Resolution unit, parses training sequence and the non-training sequence that receives in advance signal that receives in advance signal for the signal from being received in advance by described receiving element;
Computing unit, for calculating respectively corresponding the first channel impulse response and second channel impulse response according to the training sequence that receives in advance signal being obtained by described resolution unit and the described non-training sequence that receives in advance signal;
First chooses unit, for choosing a channel impulse response that conduct is final according to the selection rule setting in advance from the 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 present invention provides, by obtaining training sequence and the non-training sequence that receives in advance signal that receives in advance signal the signal from receiving in advance, and obtain corresponding channel impulse response by described training sequence, from described channel impulse response, select a final channel impulse response, make to adopt while shifting to an earlier date reception programme, can choose channel impulse response more accurately according to actual channel circumstance.Solved in prior art owing to only obtaining channel impulse response by receiving in advance the training sequence of signal, made in the situation that channel circumstance is case2 the inaccurate problem of channel estimating.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.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is some embodiments of the present invention, for those of ordinary skills, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.
The method flow diagram of the channel estimating that Fig. 1 provides for the embodiment of the present invention;
Fig. 2 is the method flow diagram that in the flow chart shown in Fig. 1, step 104 is chosen channel impulse response;
The apparatus structure schematic diagram of the channel estimating that Fig. 3 provides for the embodiment of the present invention;
Fig. 4 is the first structural representation of choosing unit 304 in the apparatus structure schematic diagram shown in Fig. 3.
Fig. 5 is that channel circumstance is in case2, the type of service situation that is 12.2kbps, the curve chart of the system block error rate BLER that different channels method of estimation is corresponding;
Fig. 6 is that channel circumstance is in case2, the type of service situation that is 12.2kbps, and system corresponding to different channels method of estimation is without the curve chart of the bit error rate RawBER of chnnel coding.
Embodiment
For making object, technical scheme and the advantage of the embodiment of the present invention clearer, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not paying the every other embodiment obtaining under creative work prerequisite, belong to the scope of protection of the invention.
In order to solve prior art in the situation that channel circumstance is case2, the inaccurate problem of channel estimating, the embodiment of the present 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 present invention provides, comprising:
In the present embodiment, adopt 4 chip lengths in advance, the method for 4chips receives signal.Due under actual communication environment, signal can produce synchronous error, comprising synchronous left avertence, moves with synchronous right avertence and moves.Wherein, synchronous left avertence is moved the accuracy impact of channel estimating larger, and synchronously right avertence is moved the accuracy impact of channel estimating less.Therefore, in actual communication environment, consider the factors such as multipath number and multidiameter delay, can adopt in advance the method for 4chips to overcome synchronous left avertence and move the impact on channel estimation accuracy.Adopting the method that receives in advance signal in most of the cases can obtain good channel impulse response, is case2 but work as channel circumstance, and performance there will be severe exacerbation on the contrary.This is because the time delay in the 3rd footpath of case2 is 12000ns, and the speed of signal transmission is 1.28 * 10
6chips/s, therefore the time delay in the 3rd footpath is approximately 16chips.When the window length of reception signal is also 16chips, if still adopt the scheme receiving in advance, the 3rd footpath will exceed the window that receives signal, can have a strong impact on the accuracy that signal receives.And in practical communication, receiving terminal does not also know it is now which kind of channel circumstance, therefore still adopt the scheme receiving in advance, the signal receiving is in advance obtained to channel impulse response more accurately through subsequent treatment.
In the present embodiment, described training sequence is midamble code.Midamble code is the same with pilot signal, is used for distinguishing many community users, and for carrying out channel estimating, with it, calculates channel impulse response.Midamble code and the corresponding data division of described midamble code that from the signal receiving in advance, can obtain each community, represent with Midamble_ahead and Data_ahead respectively; By the signal receiving in advance, can also parse non-midamble code and its corresponding data division of each community while receiving in advance, with Midamble and Data, represent respectively.
In the present embodiment, according to the midamble code Midamble_ahead that receives in advance signal, calculate a channel impulse response, with H_original_a, represent; According to the non-midamble code Midamble that receives in advance signal, calculate one other channel impulse response, with H_original, represent.
In the present embodiment, adopt the size of the noise power that two channel impulse responses of comparison are corresponding 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, in described noise power Wei Zhe community without the noise power of eliminating burr.By H_original_a and the H_original obtaining in step 103, calculate respectively corresponding noise power, be called the first noise power and the second noise power.
In the present embodiment, the size of noise power reflects the order of accuarcy of channel impulse response, chooses a corresponding channel impulse response that noise power is less as final channel impulse response, with H_original_use, represents.The corresponding data division of this final channel impulse response represents with Data_use.With the H_original_use getting and Data_use, joint-detection and relevant follow-up computing just can have been carried out.
Fig. 5 and Fig. 6 are that case2 channel is the test result under 12.2kbps in type of service.Wherein, Fig. 5 is the curve chart of system block error rate BLER corresponding to different channels method of estimation; Fig. 6 is that system corresponding to different channels method of estimation is without the curve chart of the bit error rate RawBER of chnnel coding.Three curves 1 in two width figure, the performance curve of 2,3 systems while indicating respectively normally to receive signal and carry out channel estimating without synchronous error, performance curve and the performance curve of system while adopting technical scheme of the present invention to carry out channel estimating of system when 4chips receives signal and carries out channel estimating in advance.
The method of the channel estimating that the embodiment of the present invention provides, by obtaining training sequence and the non-training sequence that receives in advance signal that receives in advance signal the signal from receiving in advance, and obtain corresponding channel impulse response by described training sequence, from described channel impulse response, select a final channel impulse response, make to adopt while shifting to an earlier date reception programme, can choose channel impulse response more accurately according to actual channel circumstance.Solved in prior art owing to only obtaining channel impulse response by receiving in advance the training sequence of signal, made in the situation that channel circumstance is case2 the inaccurate problem of channel estimating.
As shown in Figure 3, the embodiment of the present invention also provides a kind of device of channel estimating, comprising:
Receiving element 301, for receiving in advance signal according to the code length setting in advance;
First chooses unit 304, for choosing a channel impulse response that conduct is final according to the selection rule setting in advance from the 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, for obtaining respectively corresponding the first noise power and the second noise power according to the first channel impulse response being calculated by described computing unit 303 and described second channel impulse response;
Second chooses unit 3042, for the first noise power from being obtained by described acquiring unit 3041 and the second noise power, chooses the noise power that numerical value is less;
The 3rd chooses unit 3043, for choosing by described second, chooses channel impulse response corresponding to noise power that numerical value that unit 3042 obtains is less as final channel impulse response.
More than the concrete methods of realizing of device can, referring to described in step 101 as depicted in figs. 1 and 2～104, step 201～203, repeat no more herein.
The device of the channel estimating that the embodiment of the present invention provides, by obtaining training sequence and the non-training sequence that receives in advance signal that receives in advance signal the signal from receiving in advance, and obtain corresponding channel impulse response by described training sequence, from described channel impulse response, select a final channel impulse response, make to adopt while shifting to an earlier date reception programme, can choose channel impulse response more accurately according to actual channel circumstance.Solved in prior art owing to only obtaining channel impulse response by receiving in advance the training sequence of signal, made in the situation that channel circumstance is case2 the inaccurate problem of channel estimating.
Technical scheme provided by the invention can be applied in TD-SCDMA system, carry out in the technical field of channel estimating.
One of ordinary skill in the art will appreciate that all or part of step realizing in above-described embodiment method is to come the hardware that instruction is relevant to complete by program, described program can be stored in a computer-readable recording medium, as ROM/RAM, magnetic disc or CD etc.
The above; be only the specific embodiment of the present invention, but protection scope of the present invention is not limited to this, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; can expect easily changing or replacing, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion by the described protection range with claim.
Claims (6)
1. a method for channel estimating, is characterized in that, comprising:
According to the code length setting in advance, receive in advance signal;
From the described signal receiving in advance, parse the training sequence and the non-training sequence that receives in advance signal that receive in advance signal;
According to described training sequence and the described non-training sequence that receives in advance signal that receives in advance signal, calculate respectively corresponding the first channel impulse response and second channel impulse response;
According to the selection rule setting in advance, from described the first channel impulse response and second channel impulse response, choose a channel impulse response that conduct is final.
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 the first channel impulse response and second channel impulse response:
According to described the first channel impulse response and described second channel impulse response, obtain respectively corresponding the first noise power and the second noise power;
From described the first noise power and the second noise power, choose the noise power that numerical value is less;
Choose channel impulse response corresponding to noise power that described numerical value is less as final channel impulse response.
3. the method for channel estimating according to claim 1, is characterized in that, described in the code length that sets in advance be 4 chip lengths.
4. the method for channel estimating according to claim 1, is characterized in that, described training sequence is midamble code.
5. a device for channel estimating, is characterized in that, comprising:
Receiving element, for receiving in advance signal according to the code length setting in advance;
Resolution unit, parses training sequence and the non-training sequence that receives in advance signal that receives in advance signal for the signal from being received in advance by described receiving element;
Computing unit, for calculating respectively corresponding the first channel impulse response and second channel impulse response according to the training sequence that receives in advance signal being obtained by described resolution unit and the described non-training sequence that receives in advance signal;
First chooses unit, for choosing a channel impulse response that conduct is final according to the selection rule setting in advance from the 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 unit comprises:
Acquiring unit, for obtaining respectively corresponding the first noise power and the second noise power according to the first channel impulse response being calculated by described computing unit and described second channel impulse response;
Second chooses unit, for the first noise power from being obtained by described acquiring unit and the second noise power, chooses the noise power that numerical value is less;
The 3rd chooses unit, for choosing by described second, chooses channel impulse response corresponding to noise power that numerical value that unit obtains is less as final channel impulse response.
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| KR101784979B1 (en) | 2013-09-27 | 2017-10-20 | 후아웨이 디바이스 (둥관) 컴퍼니 리미티드 | Method and user equipment for transmitting direct connection communication signals of user equipment |
| CN107071889B (en) | 2014-03-21 | 2020-10-09 | 华为终端有限公司 | Method for detecting device-to-device signal and user equipment |
| 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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| CN101217300A (en) * | 2007-12-28 | 2008-07-09 | 清华大学 | A channel estimation method for transmit diversity system |
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| CN101547019A (en) * | 2008-03-25 | 2009-09-30 | 卓胜微电子（上海）有限公司 | Method for evaluating channel in DTMB system and device realizing same |
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| WO2008156313A1 (en) * | 2007-06-19 | 2008-12-24 | Sk Telecom Co., Ltd. | Method and system for estimating adaptive combined channel in cdma system base on time division duplex system |
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| CN101217300A (en) * | 2007-12-28 | 2008-07-09 | 清华大学 | A channel estimation method for transmit diversity system |
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