CN101098208A - TD-SCDMA associated detection technology based channel estimation method - Google Patents

Abstract

The invention provides a channel evaluation method based on TD-SCDMA coupled check technique, comprising that weighting and combining the channel impact response of all windows of the user at initial evaluation, according to the weighting and combining result, confirming the modified channel impact response of each window or code channel, wherein the result can be used as the modified impact response of each window or code channel. According to the weighting and combining result, the invention can confirm the modified channel impact response, comprising that averaging the result, reducing the amplitude of the averaged result, and using the result after amplitude reduction as the modified channel impact response.

Description

Channel estimation method based on TD-SCDMA joint detection technology

Technical Field

The invention relates to a joint detection technology of TD-SCDMA, in particular to a channel estimation improvement method based on the joint detection technology of TD-SCDMA.

Background

In the current TD-SCMDA system, a joint detection technology is one of the characteristic schemes, a channel estimation technology is a very important link of the joint detection technology, and the accuracy of the channel estimation directly influences the effect of the joint detection.

In TD-SCDMA systems, joint detection techniques are mainly directed to time slots. A TDMA (time division multiple access) frame length defined by 3GPP (3rd Generation Partnership Project) is 10ms, in order to implement fast power control, timing advance calibration and support for some new technologies in TD-SCDMA systems, a 10ms frame is divided into two subframes with identical structures, each subframe has a duration of 5ms, each subframe with a duration of 5ms is composed of 3 special time slots and 7 normal time slots, a relationship between a time slot and a radio frame is shown in fig. 1, where the 3 special time slots are DwPTS (downlink pilot time slot), GP (guard time slot) and UpPTS (uplink pilot time slot), and the 7 normal time slots are TS0-TS 6.

Fig. 2A and fig. 2B are schematic diagrams of a special timeslot and a conventional timeslot structure, respectively. As shown in fig. 2A, DwPTS is used to transmit SYNC _ DL (cell synchronization code) and UpPTS is used to transmit UpPTS (uplink pilot time slot). As shown in fig. 2B, located between two Data Symbols is a training sequence, also called Midamble code, which is used as channel estimation in channel decoding, and has a length of 144 chips (chips), and is transmitted directly with baseband processed and spread Data without baseband processing and spreading. The length of the basic Midamble code is 128 chips, and the Midamble codes used by different channels in the same time slot are all obtained by cyclic shifting the basic Midamble code.

The binary form of the basic Midamble code is as follows:

m_p＝(m₁，m₂，…，m_P)

from the above formula we can get the elements in the basic Midamble code in complex formm _iThe calculation method of (2):

m _i＝(j)ⁱ·m_i i＝1，...P，j²＝-1

m _p＝( m ₁， m ₂，…， m _P)

wherein P is 128, the Midamble codes used in practice are all obtained by basic Midamble code period extension, and the maximum length of the extension is:

i_max＝L_m+(K-1)W

L_m: the TD-SCDMA system is fixed to 144;

w: defined as | P/K |, the value of which can represent the window length of the wireless channel impulse response;

k: the maximum number of midambles in a slot, i.e. the maximum number of windows contained in this slot.

Thus, we can also get a new sequence:

<math> <mrow> <munder> <mi>m</mi> <mo>&OverBar;</mo> </munder> <mo>=</mo> <mrow> <mo>(</mo> <msub> <munder> <mi>m</mi> <mo>&OverBar;</mo> </munder> <mn>1</mn> </msub> <mo>,</mo> <msub> <munder> <mi>m</mi> <mo>&OverBar;</mo> </munder> <mn>2</mn> </msub> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <msub> <munder> <mi>m</mi> <mo>&OverBar;</mo> </munder> <msub> <mi>i</mi> <mi>max</mi> </msub> </msub> <mo>)</mo> </mrow> <mo>=</mo> <mrow> <mo>(</mo> <msub> <munder> <mi>m</mi> <mo>&OverBar;</mo> </munder> <mn>1</mn> </msub> <mo>,</mo> <msub> <munder> <mi>m</mi> <mo>&OverBar;</mo> </munder> <mn>2</mn> </msub> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <msub> <munder> <mi>m</mi> <mo>&OverBar;</mo> </munder> <mrow> <msub> <mi>L</mi> <mi>m</mi> </msub> <mo>+</mo> <mrow> <mo>(</mo> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>)</mo> </mrow> <mi>W</mi> </mrow> </msub> <mo>)</mo> </mrow> </mrow> </math>

mfirst P elements and vectors inm _PThe first 128 elements in the series are identical, and the following n ═ i (128+1) to i_maxEach element is repeatedm _PThe Midamble codes in different windows are truncated according to the length of W on the basis of the extended Midamble codes.

The Midamble code in each window only corresponds to the offset of one basic Midamble code, the number of code channels in each window is determined by the value of K, and a plurality of code channels in one window correspond to the same offset of the Midamble code. According to the protocol specification of 3GPP, there are several values of K, 2, 4, 6, 8, 10, 12, 14, and 16, and under the Default allocation mode, the number of code channels included in each window is determined by the value of K. See, in particular, the detailed description in 3GPP TS 25.221.

Taking K as 4 as an example, the corresponding relationship between the basic Midamble code and the code channel is shown in fig. 3. As can be seen in fig. 3, c⁽¹⁾、c⁽²⁾、c⁽³⁾、c⁽⁴⁾Corresponding to Midamble⁽¹⁾(i.e., m)⁽¹⁾)，c⁽⁵⁾、c⁽⁶⁾、c⁽⁷⁾、c⁽⁸⁾Corresponding to Midamble⁽²⁾(i.e., m)⁽²⁾)，c⁽⁹⁾、c⁽¹⁰⁾、c⁽¹¹⁾、c⁽¹²⁾Corresponding to Midamble⁽³⁾(i.e., m)⁽³⁾)，c⁽¹³⁾、c⁽¹⁴⁾、c⁽¹⁵⁾、c⁽¹⁶⁾Corresponding to Midamble⁽⁴⁾(i.e., m)⁽⁴⁾) The 4 code channels corresponding to the offset of the same Midamble code are located in the same window, m⁽¹⁾、m⁽²⁾、m⁽³⁾、m⁽⁴⁾Respectively, obtained by cyclic shifting of the basic Midamble code.

Currently, as shown in fig. 4, a method for performing channel estimation by using a training sequence calculates a channel impulse response corresponding to each Midamble code offset by using a Midamble code in step S401; step S402 is entered, and channel impulse responses corresponding to the offset of each Midamble code are intercepted; and finally, in step S403, obtaining the channel impulse response corresponding to each code channel according to the corresponding relationship between the Midamble code offset and the code channel, wherein the channel impulse response is called as the preliminarily estimated channel impulse response. When several code channels of a user correspond to multiple Midamble code offsets, theoretically, the channel impulse responses corresponding to these different Midamble code offsets are the same, but the above method does not utilize this characteristic, so the accuracy of the estimated channel impulse response is not very high, especially when the noise or interference is very strong, the accuracy is very low.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a channel estimation improvement method based on TD-SCDMA joint detection technology to improve the accuracy of channel estimation.

In order to solve the above technical problem, the present invention provides a channel estimation method based on TD-SCDMA joint detection technology, comprising: weighting and combining the preliminarily estimated channel impulse responses of all the windows of the user; and determining the improved channel impulse response of each window or code channel according to the result of the weighted combination processing.

The channel impulse responses of all the windows of the user which are preliminarily estimated are weighted and combined by the following formula:

<math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mo>[</mo> <msub> <mi>G</mi> <mi>i</mi> </msub> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> </math>

wherein,

denotes the result of the weighted combining process, K_mIndicates the number of all windows of the user,

for preliminary estimation of channel impulse response, G, of the ith window of the user_iAre weighting factors and satisfy the condition that,

$\frac{G_i}{G_j}=\frac{N_j}{N_i}\sqrt{\frac{P_i}{P_j}},$ i＝1，2，...，K_m， i＝1，2，...，K_m

wherein N is_iAnd N_jRespectively representing the variance, P, of the additive Gaussian noise of the ith and j windows_iAnd P_jThe window powers of the ith and jth windows are indicated, respectively.

The channel impulse responses of all the windows of the user which are preliminarily estimated are weighted and combined by the following formula:

<math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mo>[</mo> <msub> <mi>G</mi> <mi>i</mi> </msub> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> </math>

wherein,

denotes the result of the weighted combining process, K_mIndicates the number of all windows of the user,

channel impulse of ith window of user for preliminary estimationResponse, G_iAre weighting factors and satisfy the condition that,

$\frac{G_i}{G_j}=\sqrt{\frac{P_i}{P_j}},$ i＝1，2，...，K_m，j＝1，2，...，K_m

wherein, P_iAnd P_jThe window powers of the ith and jth windows are indicated, respectively.

The channel impulse responses of all the windows of the user which are preliminarily estimated are weighted and combined by the following formula:

<math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mo>[</mo> <msub> <mi>G</mi> <mi>i</mi> </msub> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> </math>

wherein,

denotes the result of the weighted combining process, K_mIndicates the number of all windows of the user,

for preliminary estimated ith window of userChannel impulse response, G_iAre weighting factors and satisfy the condition that,

$\frac{G_i}{G_j}=\sqrt{\frac{m_i}{m_j}},$ i＝1，2，...，K_m， i＝1，2，...，K_m

wherein m is_iAnd m_jThe number of code channels of the ith and j windows respectively.

And determining the result of the weighted combination processing as the improved channel impulse response of each window or code channel.

The step of determining the improved channel impulse response of each window or code channel according to the result of the weighted combining process includes: carrying out average operation processing on the result of the weighted combination processing; respectively carrying out amplitude reduction processing on the results of the average operation processing; and determining the result of the amplitude reduction processing as the improved channel impulse response of the corresponding window.

Performing an averaging operation on the result of the weighted combination process by the following formula:

<math> <mrow> <mi>A</mi> <mo>=</mo> <mfrac> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mi>&eta;</mi> </mfrac> </mrow> </math>

wherein, <math> <mrow> <mi>&eta;</mi> <mo>=</mo> <msqrt> <munderover> <mi>&Sigma;</mi> <mrow> <mi>g</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>W</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msubsup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> <mrow> <mo>(</mo> <mi>g</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> </msqrt> </mrow> </math> or

To represent

W- * P/K *, P-128, K representing the maximum number of windows contained in a slot, m_iIndicating the number of code channels, P, of the ith window_iRepresenting the window power of the ith window.

When in use <math> <mrow> <mi>&eta;</mi> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <msub> <mi>m</mi> <mi>i</mi> </msub> </mrow> </math> Then, a is determined as the improved channel impulse response of each code channel.

The results of the averaging operation are respectively subjected to amplitude reduction processing by the following formulas:

<math> <mrow> <msub> <mi>h</mi> <mrow> <mi>av</mi> <mo>,</mo> <mi>n</mi> </mrow> </msub> <mo>=</mo> <msqrt> <msub> <mi>m</mi> <mi>n</mi> </msub> </msqrt> <mo>&CenterDot;</mo> <mi>A</mi> </mrow> </math> or <math> <mrow> <msub> <mi>h</mi> <mrow> <mi>av</mi> <mo>,</mo> <mi>n</mi> </mrow> </msub> <mo>=</mo> <msqrt> <msub> <mi>P</mi> <mi>n</mi> </msub> </msqrt> <mo>&CenterDot;</mo> <mi>A</mi> <mo>,</mo> </mrow> </math> n＝1，2，...，K_m

Wherein h is_av，nRepresenting the improved channel impulse response for the nth window.

The P is_iObtained from the following equation:

<math> <mrow> <msub> <mi>P</mi> <mi>i</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>g</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>W</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msubsup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>,</mo> </mrow> </math> i＝1，2，...，K_m，g＝1，2，...，W

wherein,is composed of

The t-th element of (1).

The channel estimation method of the present invention further comprises: for the primary estimated own userWeighting and combining the channel impulse responses of all the activated windows; and determining the improved channel impulse response of each active window or active code channel according to the result of the weighted combination processing. At this time, K_mIndicating the number of all active windows of the user.

Before the average operation processing is performed on the result of the weighted combination processing, the method further comprises the following steps: and estimating the number of the active code channels of the last active window of the user.

The step of estimating the number of active code channels of the last active window of the user comprises the following steps:

the average code power p of all the active windows except the last active window is obtained by the following formula_av，

<math> <mrow> <msub> <mi>p</mi> <mi>av</mi> </msub> <mo>=</mo> <mfrac> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>p</mi> <mi>i</mi> </msub> </mrow> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>m</mi> <mi>i</mi> </msub> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

The number m of the active code channels of the last active window is obtained by the following formula_Km，

$m_{K_m}=\mathrm{round}\left(\frac{P_{K_m}}{P_{\mathrm{av}}}\right)$

Wherein k is_mIndicating the number of active windows owned by the user, P_iWindow power, m, representing the ith active window_iThe number of code channels for the ith active window,

presentation pair

Rounded values are taken.

The channel impulse responses of all the windows of the user which are preliminarily estimated are weighted and combined by the following formula:

<math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mo>[</mo> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> </math>

wherein,

represents the result of the weighted combination process,

indicating the channel impulse response of the ith or active window, K_mThe number of all windows or active windows of the user is represented, the weighting factor is 1, and the improved value of each window is obtained by the following formulaChannel impulse response:

<math> <mrow> <msub> <mi>h</mi> <mi>av</mi> </msub> <mo>=</mo> <mfrac> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <msub> <mi>K</mi> <mi>m</mi> </msub> </mfrac> </mrow> </math>

wherein h is_avImproved channel impulse response for each window or activation window.

The channel impulse responses of all the windows of the user which are preliminarily estimated are weighted and combined by the following formula:

<math> <mrow> <msub> <mi>h</mi> <mi>av</mi> </msub> <mo>=</mo> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>m</mi> </msub> </mrow> </math> m＝1，2，...，K_m

wherein h is_avFor each window of improved channel impulse response,

represents the channel impulse response of the window with the largest window power among all the windows,

the corresponding weighting factor is 1 and the weighting factors corresponding to the other windows are 0.

The invention carries out weighting combination processing on the preliminarily estimated channel impulse response based on the theory that the channel impulse responses corresponding to different Midamble code offsets of a plurality of code channels of the same user are the same, and can completely improve the accuracy of channel estimation.

The weighting factors used when the weighted average processing is carried out on the channel impulse response can meet certain conditions, and the weighting factors meeting the conditions can maximize the gain after the channel impulse response is combined, namely the signal-to-noise ratio.

The invention needs to obtain the average impulse response of all code channels, so all activated code channel numbers need to be obtained, but in practical application, the last activation window is not necessarily configured according to the code channels issued by the network side, which may cause the default activated code channel number not to accord with the actual activated code channel number.

Drawings

FIG. 1 is a frame structure diagram of a TD-SCDMA system;

FIG. 2A is a diagram of a special timeslot structure;

FIG. 2B is a diagram of a conventional timeslot structure;

FIG. 3 is a diagram illustrating a mapping relationship between an offset and a code track of a Midamble code;

FIG. 4 is a flow chart of a method for performing channel estimation using training sequences;

FIG. 5 is a flow chart of a first embodiment of the present invention;

FIG. 6 is a block diagram of an implementation of preliminary channel estimation;

fig. 7 is a block error rate performance curve respectively adopting the first embodiment of the present invention and the conventional channel estimation method under the AWGN channel condition and when a single timeslot includes 8 windows and 8 code channels;

fig. 8 is a block error rate performance curve respectively adopting the first embodiment of the present invention and the conventional channel estimation method under the CASE1 channel condition and when a single time slot includes 8 windows and 8 code channels;

fig. 9 is a block error rate performance curve respectively adopting the first embodiment of the present invention and the conventional channel estimation method under the CASE3 channel condition and when a single time slot includes 8 windows and 8 code channels;

fig. 10 is a block error rate performance curve respectively adopting the first embodiment of the present invention and the conventional channel estimation method under the AWGN channel condition and when a single timeslot includes 8 windows and 7 code channels;

fig. 11 is a block error rate performance curve respectively adopting the first embodiment of the present invention and the conventional channel estimation method under the CASE1 channel condition and when a single time slot includes 8 windows and 7 code channels;

fig. 12 is a block error rate performance curve respectively adopting the first embodiment of the present invention and the conventional channel estimation method under the CASE3 channel condition and when a single timeslot includes 8 windows and 7 code channels;

fig. 13 is a block error rate performance curve for a single timeslot including 2 windows and 9 code channels under AWGN channel conditions, respectively using the first embodiment of the present invention and the conventional channel estimation method;

fig. 14 is a block error rate performance curve when a single timeslot includes 2 windows and 9 code channels under the CASE1 channel condition and the first embodiment of the present invention and the conventional channel estimation method are respectively adopted;

fig. 15 is a block error rate performance curve for a CASE3 channel condition, where a single timeslot includes 2 windows and 9 code channels, respectively, when the first embodiment of the present invention and the conventional channel estimation method are used.

Detailed Description

The following detailed description of the preferred embodiments of the present invention will be made with reference to the accompanying drawings. It is to be noted at first that the meanings of terms, words and claims used in the present invention are not limited to only the literal and ordinary meanings thereof, but also include meanings and concepts conforming to the technology of the present invention because we, as the inventor, appropriately give definitions of terms in order to describe our invention most appropriately. Accordingly, the arrangements shown in the present specification and drawings are only preferred embodiments of the invention and are not intended to list all of the technical features of the invention. It will be appreciated that there are a variety of equivalents and modifications which may be substituted for those of our scheme.

The invention carries out weighting combination processing on the preliminarily estimated channel impulse response on the basis of the traditional channel estimation method, and obtains the improved channel impulse response according to the result of the weighting combination processing.

First, a first embodiment of the present invention will be described with reference to fig. 5.

As shown in fig. 5, in step S501, a channel impulse response of each window is obtained by using a conventional channel estimation method.

The conventional channel estimation method is shown in FIG. 6, and assumes that the received Midamble code vector ise＝( e ⁽¹⁾， e ⁽²⁾， e ⁽³⁾，...， e ⁽¹⁴⁴⁾) Intercepting the first 128chip constructse′＝( e′⁽¹⁾， e′⁽²⁾，...， e′⁽¹²⁸⁾) For channel estimation, as can be seen from fig. 6, the result of the channel estimation

Comprises the following steps:

<math> <mrow> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mo>=</mo> <mi>IFFT</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <mi>FFT</mi> <mrow> <mo>(</mo> <msup> <munder> <mi>e</mi> <mo>&OverBar;</mo> </munder> <mo>&prime;</mo> </msup> <mo>)</mo> </mrow> </mrow> <mrow> <mi>FFT</mi> <mrow> <mo>(</mo> <munder> <mi>m</mi> <mo>&OverBar;</mo> </munder> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>)</mo> </mrow> </mrow> </math>

wherein, <math> <mrow> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mo>=</mo> <mrow> <mo>(</mo> <msup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msup> <mo>,</mo> <msup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msup> <mo>,</mo> <msup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mrow> <mo>(</mo> <mn>3</mn> <mo>)</mo> </mrow> </msup> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mrow> <mo>(</mo> <mn>128</mn> <mo>)</mo> </mrow> </msup> <mo>)</mo> </mrow> </mrow> </math> mrepresenting basic Midamble code, FFT representing fast Fourier transform, IFFT representing inverse fast Fourier transform, and using the cyclic correlation of Midamble code, according to the channel response window length corresponding to each window, sequentiallyAnd taking out the channel impulse response of the corresponding window.

Step S502 is entered, and activation detection is performed on all windows of the user, so as to determine all activated windows of the user. The channel impulse response obtained in step S501 may include channel impulse responses of other user windows, and in order to obtain the channel configuration situation of the user, the network side may notify the UE (user equipment) through signaling. In practical applications, not all windows will be activated, and if the inactive window and the active window are considered simultaneously in the channel estimation process, the accuracy of the estimation result will be reduced, so the present embodiment adds an activation detection step to detect which windows are activated.

Step S503 is entered, and the window power of each active window, the window power P, is obtained according to the channel impulse response obtained in step S501_iCan be calculated by the following formula:

<math> <mrow> <msub> <mi>P</mi> <mi>i</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>g</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>W</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msubsup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> <mrow> <mo>(</mo> <mi>g</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>,</mo> </mrow> </math> i＝1，2，...，K_m，g＝1，2，...，W

wherein,

satisfy the requirement of <math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>=</mo> <mrow> <mo>(</mo> <msubsup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <mo>,</mo> <msubsup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msubsup> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msubsup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> <mrow> <mo>(</mo> <mi>W</mi> <mo>)</mo> </mrow> </msubsup> <mo>)</mo> </mrow> <mo>,</mo> </mrow> </math>

Indicating the channel impulse response of the ith activation window, which may be obtained in step S501, W indicates the window length of the channel impulse response, and W is * P/K *, P is 128, and K indicates the maximum number of windows included in one slot.

The process proceeds to step S504, where the number of active channels in the last active window is estimated. In practical application, code channel allocation is performed according to a mode of allocating a low timeslot number and a low code channel number first, so that after activation detection, it is only possible that the last activation window in a plurality of activation windows of the user is smaller than the number of already allocated code channels, and generally, all activation windows except the last activation window are considered to be full code channel configuration, and the number of activation code channels is defaulted to the number of high-level configuration, that is, the number of configuration issued by a network side through signaling, and since the last activation window is not possible to be full code channel configuration, it is necessary to estimate the number of activation code channels of the last activation window in order to improve accuracy of channel estimation. It should be noted that, if the number of code channels used in practice is the same as the number of code channels configured in the signaling sent by the network side, we will refer to full code channel configuration here, and after activation detection, it is only possible that the last activation window in the multiple activation windows of the user will have a smaller number of code channels than that already allocated, so that it is only necessary to confirm the number of the activation code channels in the last activation window of the user.

This embodiment estimates the number of active code channels for the last active window beforeFirstly, the average code channel power p of all the active windows except the last active window is obtained according to the following formula_av：

<math> <mrow> <msub> <mi>p</mi> <mi>av</mi> </msub> <mo>=</mo> <mfrac> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>p</mi> <mi>i</mi> </msub> </mrow> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>m</mi> <mi>i</mi> </msub> </mrow> </mfrac> </mrow> </math>

Then the number m of the active code channels of the last active window is obtained by the following formula_Km，

$m_{K_m}=\mathrm{round}\left(\frac{P_{K_m}}{P_{\mathrm{av}}}\right)$

Wherein, K_mIndicating the number of active windows owned by the user, P_iWindow power, m, representing the ith active window_iThe number of code channels for the ith active window,presentation pairRounded values are taken.

And step S505, carrying out weighted average processing on the channel impulse responses of all the activation windows of the user to obtain the average impulse responses of all the activation code channels.

Generally, the key factor for weighted average processing should be a weighting factor, i.e. the weighting factor G in this embodiment_iAs long as the following conditions are satisfied:

$\frac{G_i}{G_j}=\frac{N_j}{N_i}\sqrt{\frac{P_i}{P_j}},$ i＝1，2，...，K_m， i＝1，2，...，K_m

wherein N is_iAnd N_jRepresents the variance, P, of the additive Gaussian noise of the i and j activation windows, respectively_iAnd P_jRespectively representing the window power of the ith and the j activation windows, and satisfying the weighting factor G of the formula_iCan be that

If N is considered to be_i＝N_jThen the above formula can be simplified to

$\frac{G_i}{G_j}=\sqrt{\frac{P_i}{P_j}}$

The weighting factor G satisfying the above formula_iCan be thatIf P is_i∝m_i，P_j∝m_jThen the above formula can be converted into

$\frac{G_i}{G_j}=\sqrt{\frac{m_i}{m_j}}$

The weighting factor G satisfying the above formula_iCan be that

This example adopts

As a weighting factor.

The average impulse response A of all code channels is obtained by the following formula:

<math> <mrow> <mi>A</mi> <mo>=</mo> <mfrac> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mo>[</mo> <msqrt> <msub> <mi>m</mi> <mi>i</mi> </msub> </msqrt> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <msub> <mi>m</mi> <mi>i</mi> </msub> </mrow> </mfrac> </mrow> </math>

wherein, K_mIndicating the number of all active windows of the user,

for the obtained channel impulse response of the ith activation window of the user, m_iThe number of code channels of the ith active window.

After step S505 is completed, step S506 is performed, and amplitude reduction processing is performed on the average impulse responses of all the code channels to obtain an improved channel impulse response. In the present embodiment, the improved channel impulse response h is obtained by the following formula_av，n：

<math> <mrow> <msub> <mi>h</mi> <mrow> <mi>av</mi> <mo>,</mo> <mi>n</mi> </mrow> </msub> <mo>=</mo> <msqrt> <msub> <mi>m</mi> <mi>n</mi> </msub> </msqrt> <mo>&CenterDot;</mo> <mi>A</mi> </mrow> </math> Or <math> <mrow> <msub> <mi>h</mi> <mrow> <mi>av</mi> <mo>,</mo> <mi>n</mi> </mrow> </msub> <mo>=</mo> <msqrt> <msub> <mi>P</mi> <mi>n</mi> </msub> </msqrt> <mo>&CenterDot;</mo> <mi>A</mi> <mo>,</mo> </mrow> </math> n＝1，2，...，K_m。

In the first embodiment described above, the weighting factor is an important factor in the channel estimation method, and the basis of the weighting factor used in the first embodiment will now be described.

Suppose that two windows correspond to a letterThe signal-to-noise ratio of the channel impulse response is SNR1 and SNR2, respectively, and the window power is P1 and P₂The additive Gaussian noise variances are respectively N1 and N2, the weighting factors of the two windows are respectively G1 and G2, and the output signal power P after coherent combination_sComprises the following steps:

$P_s=\frac{1}{2}{({\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">G</figure-callout>}}_1\sqrt{{2\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}+{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">G</figure-callout>}}_2\sqrt{{2P}_2})}^2={(G_1\sqrt{{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}+G_2\sqrt{P_2})}^2$

the noise power is:

P_n＝G₁ ²N₁+G₂ ²N₂

the output signal-to-noise ratio is:

$\mathrm{SNR}=\frac{P_s}{P_n}=\frac{{(G_1\sqrt{{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}+G_2\sqrt{P_2})}^2}{{{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">G</figure-callout>}}_1}^2{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">N</figure-callout>}}_1+{{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">G</figure-callout>}}_2}^2{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}$

to maximize the output signal-to-noise ratio, the following operations are performed:

<math> <mrow> <mfrac> <mrow> <mo>&PartialD;</mo> <mrow> <mo>(</mo> <mi>SNR</mi> <mo>)</mo> </mrow> </mrow> <msub> <mrow> <mo>&PartialD;</mo> <mi>G</mi> </mrow> <mn>1</mn> </msub> </mfrac> <mo>=</mo> <mfrac> <mo>&PartialD;</mo> <msub> <mrow> <mo>&PartialD;</mo> <mi>G</mi> </mrow> <mn>1</mn> </msub> </mfrac> <mo>[</mo> <mfrac> <msup> <mrow> <mo>(</mo> <msub> <mi>G</mi> <mn>1</mn> </msub> <msqrt> <msub> <mi>P</mi> <mn>1</mn> </msub> </msqrt> <mo>+</mo> <msub> <mi>G</mi> <mn>2</mn> </msub> <msqrt> <msub> <mi>P</mi> <mn>2</mn> </msub> </msqrt> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mrow> <msup> <msub> <mi>G</mi> <mn>1</mn> </msub> <mn>2</mn> </msup> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>+</mo> <msup> <msub> <mi>G</mi> <mn>2</mn> </msub> <mn>2</mn> </msup> <msub> <mi>N</mi> <mn>2</mn> </msub> </mrow> </mfrac> <mo>]</mo> <mo>=</mo> <mn>0</mn> </mrow> </math>

<math> <mrow> <mfrac> <mrow> <mo>&PartialD;</mo> <mrow> <mo>(</mo> <mi>SNR</mi> <mo>)</mo> </mrow> </mrow> <msub> <mrow> <mo>&PartialD;</mo> <mi>G</mi> </mrow> <mn>2</mn> </msub> </mfrac> <mo>=</mo> <mfrac> <mo>&PartialD;</mo> <msub> <mrow> <mo>&PartialD;</mo> <mi>G</mi> </mrow> <mn>2</mn> </msub> </mfrac> <mo>[</mo> <mfrac> <msup> <mrow> <mo>(</mo> <msub> <mi>G</mi> <mn>1</mn> </msub> <msqrt> <msub> <mi>P</mi> <mn>1</mn> </msub> </msqrt> <mo>+</mo> <msub> <mi>G</mi> <mn>2</mn> </msub> <msqrt> <msub> <mi>P</mi> <mn>2</mn> </msub> </msqrt> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mrow> <msup> <msub> <mi>G</mi> <mn>1</mn> </msub> <mn>2</mn> </msup> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>+</mo> <msup> <msub> <mi>G</mi> <mn>2</mn> </msub> <mn>2</mn> </msup> <msub> <mi>N</mi> <mn>2</mn> </msub> </mrow> </mfrac> <mo>]</mo> <mo>=</mo> <mn>0</mn> </mrow> </math>

a set of homodyne equations can be obtained through calculation:

$\sqrt{P_1}{N}_2{G}_2-\sqrt{P_2}{N}_1{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">G</figure-callout>}}_1=0$

$\sqrt{P_2}{N}_1{G}_1-\sqrt{P_1}{N}_2{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">G</figure-callout>}}_2=0$

and finally obtaining:

$\frac{G_1}{{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">G</figure-callout>}}_2}=\frac{N_2}{N_1}\sqrt{\frac{P_1}{{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">P</figure-callout>}}_2}}$

in fact, different windows correspond to the same channel, so the above equation can be simplified as follows:

$\frac{G_1}{{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">G</figure-callout>}}_2}=\sqrt{\frac{P_1}{{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">P</figure-callout>}}_2}}$

and P is₁∝m₁，P₂∝m₂Thus, the above equation can be converted to:

$\frac{G_1}{{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">G</figure-callout>}}_2}=\sqrt{\frac{m_1}{{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">m</figure-callout>}}_2}}$

the signal-to-noise ratio after weighted combining is:

<math> <mrow> <msub> <mrow> <mo>(</mo> <mi>SNR</mi> <mo>)</mo> </mrow> <mi>max</mi> </msub> <mo>=</mo> <mfrac> <msup> <mrow> <mo>(</mo> <msub> <mi>G</mi> <mn>1</mn> </msub> <msqrt> <msub> <mi>P</mi> <mn>1</mn> </msub> </msqrt> <mo>+</mo> <msub> <mi>G</mi> <mn>2</mn> </msub> <msqrt> <msub> <mi>P</mi> <mn>2</mn> </msub> </msqrt> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mrow> <msup> <msub> <mi>G</mi> <mn>1</mn> </msub> <mn>2</mn> </msup> <msub> <mi>N</mi> <mn>1</mn> </msub> <mo>+</mo> <msup> <msub> <mi>G</mi> <mn>2</mn> </msub> <mn>2</mn> </msup> <msub> <mi>N</mi> <mn>2</mn> </msub> </mrow> </mfrac> <msub> <mo>|</mo> <mrow> <mfrac> <msub> <mi>G</mi> <mn>1</mn> </msub> <msub> <mi>G</mi> <mn>2</mn> </msub> </mfrac> <mo>=</mo> <msqrt> <mfrac> <msub> <mi>m</mi> <mn>1</mn> </msub> <msub> <mi>m</mi> <mn>2</mn> </msub> </mfrac> </msqrt> </mrow> </msub> <mo>=</mo> <mfrac> <msup> <mrow> <mo>(</mo> <mfrac> <msub> <mi>N</mi> <mn>1</mn> </msub> <msub> <mi>N</mi> <mn>2</mn> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <msub> <mi>P</mi> <mn>1</mn> </msub> <msqrt> <msub> <mi>P</mi> <mn>2</mn> </msub> </msqrt> </mfrac> <mo>+</mo> <msqrt> <msub> <mi>P</mi> <mn>2</mn> </msub> </msqrt> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mrow> <mfrac> <msup> <msub> <mi>N</mi> <mn>2</mn> </msub> <mn>2</mn> </msup> <msub> <mi>N</mi> <mn>1</mn> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <msub> <mi>P</mi> <mn>1</mn> </msub> <msub> <mi>P</mi> <mn>2</mn> </msub> </mfrac> <mo>+</mo> <msub> <mi>N</mi> <mn>2</mn> </msub> </mrow> </mfrac> </mrow> </math>

$=\frac{{(\frac{P_1}{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}+\frac{P_2}{N_2})}^2}{\frac{P_1}{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}+\frac{P_2}{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}}=\frac{P_1}{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}+\frac{P_2}{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}={\mathrm{<figure-callout\; id="1"\; label="SNR"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">SNR</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="SNR"\; filenames="A20061008944100211.png,A20061008944100241.png"\; state="\{\{state\}\}">SNR</figure-callout>}}_2$

the reasoning results show that the weighting algorithm of the first embodiment can achieve the maximum combination effect, the accuracy of channel estimation can be improved through combination, the influence caused by multipath fading is resisted, the signal to noise ratio is maximized, and the accuracy of joint detection operation is improved.

In practical application, the channel impulse responses of multiple windows of one user are all estimation results corresponding to the same channel, and if the weighted combination processing is performed, the channel estimation results of multiple windows are actually subjected to specific processing, so that the influence of various kinds of fading on channel estimation of different windows is reduced. Different processing is performed on the channel estimation results of multiple windows, resulting in different combining gains, but the combining gain is improved compared with the conventional channel estimation result, which is the embodiment of the combining gain.

Therefore, in the first embodiment, it is also feasible to perform only the weighted combination process in step S505 and use the result of the weighted combination process as the improved channel impulse response of each window, and further, the accuracy of channel estimation can be improved by performing the weighted combination process only on the result of the conventional channel estimation until the accuracy of channel estimation is improvedThere are various ways how to determine the improved channel estimation result based on the results of the weighted combining process. For example, the average channel impulse response of all the code channels obtained in step S505 may be used as the channel impulse response of each code channel, and the subsequent amplitude reduction process is not performed. In addition, the result is in step S505

Is constant, so its inverse can be considered as a part of the weighted combination exactly if it is to be

Other constants may be possible instead, e.g. will

Instead, it is changed into

To represent

W- * P/K *, P-128, K representing the maximum number of windows contained in a slot.

In addition, the first embodiment improves the channel estimation results of all active windows of the user, and we can also improve the channel estimation results of all windows of the user without distinguishing whether the windows are active windows.

The first embodiment is a preferred embodiment for implementing the present invention, but is not the only embodiment, and the second embodiment and the third embodiment of the present invention will now be described separately.

The second embodiment may use the same technical means as the first embodiment to obtain the preliminarily estimated channel impulse response, and whether activation detection is required depends on the actual situation, and it is not necessary to estimate the number of active code channels of the last active window, and the second embodiment uses the following formula to perform weighting and combining processing on the preliminarily estimated channel impulse responses of all windows of the user:

<math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mo>[</mo> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> </math>

wherein,

represents the result of the weighted combination process,

indicating the channel impulse response of the ith or active window, K_mThe number of all windows or activated windows of the user is shown, and as can be seen from the above formula, the weighting factor is 1, and then the improved channel impulse response of each window is obtained by the following formula:

<math> <mrow> <msub> <mi>h</mi> <mi>av</mi> </msub> <mo>=</mo> <mfrac> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <msub> <mi>K</mi> <mi>m</mi> </msub> </mfrac> </mrow> </math>

wherein h is_avThe improved channel impulse response for each window or active window, it can be seen that the improved channel impulse response for each window obtained by the second embodiment is the average of the channel impulse responses for all windows or active windows.

The third embodiment may also use the same technical means as the first embodiment to obtain the preliminarily estimated channel impulse response, whether activation detection is needed depends on the actual situation, and it is not necessary to estimate the number of active channels in the last active window, and the third embodiment uses the following formula to perform weighting and combining processing on the preliminarily estimated channel impulse responses in all windows of the user:

<math> <mrow> <msub> <mi>h</mi> <mi>av</mi> </msub> <mo>=</mo> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>m</mi> </msub> </mrow> </math> m＝1，2，...，K_m

wherein h is_avFor each window of improved channel impulse response,the channel impulse response of the window with the largest window power in all windows is shown, so it can be seen that the third embodiment uses the channel impulse response of the window with the largest window power in all windows as the improved channel impulse response of each window, and the weighted combining process is also a special processing mode, we can consider that,

the corresponding weighting factor is 1 and the weighting factors corresponding to the other windows are 0.

Fig. 7 to 15 illustrate comparison results of block error rates of the first embodiment of the present invention and a conventional channel estimation method under different channel conditions, where improved method represents the method of the first embodiment of the present invention, traditional method represents the conventional channel estimation method, lor \ loc represents a signal-to-noise ratio, BLER represents a block error rate, K represents the number of windows included in a single timeslot, ka represents the number of code channels included in the timeslot, awgn (additive White Gaussian noise) is additive White Gaussian noise, and CASE1, CASE2, and CASE3 are models of three channels specified in 3GPP (3rd Generation Partnership Project) protocol. As can be seen from these performance comparison diagrams, under the same snr, the block error rate of the method according to the first embodiment of the present invention is lower than that of the conventional method.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be construed as the protection scope of the present invention.

Claims (16)

1. A channel estimation method based on TD-SCDMA joint detection technology is characterized by comprising the following steps:

weighting and combining the preliminarily estimated channel impulse responses of all the windows of the user;

and determining the improved channel impulse response of each window or code channel according to the result of the weighted combination processing.

2. The channel estimation method based on TD-SCDMA combined detection technology according to claim 1, characterized in that the preliminarily estimated channel impulse responses of all windows of the user are weighted and combined by the following formula:

<math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mrow> <mo>[</mo> <msub> <mi>G</mi> <mi>i</mi> </msub> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> </mrow> </math>

wherein,

the table shows the results of the weighted combination process, K_mIndicates the number of all windows of the user,

for preliminary estimation of channel impulse response, G, of the ith window of the user_iAre weighting factors and satisfy the condition that,

$\frac{G_i}{G_j}=\frac{N_j}{N_i}\sqrt{\frac{P_i}{P_j}},i=\mathrm{1,2},...,K_m,j=\mathrm{1,2},...,K_m$

wherein N is_iAnd N_jRespectively representing the variance, P, of the additive Gaussian noise of the ith and j windows_iAnd P_jThe window powers of the ith and jth windows are indicated, respectively.

3. The channel estimation method based on TD-SCDMA combined detection technology according to claim 1, characterized in that the preliminarily estimated channel impulse responses of all windows of the user are weighted and combined by the following formula:

<math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mrow> <mo>[</mo> <msub> <mi>G</mi> <mi>i</mi> </msub> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> </mrow> </math>

wherein,denotes the result of the weighted combining process, K_mIndicates the number of all windows of the user,

for preliminary estimation of channel impulse response, G, of the ith window of the user_iAre weighting factors and satisfy the condition that,

$\frac{G_i}{G_j}=\sqrt{\frac{P_i}{P_j}},i=\mathrm{1,2},...,K_m,j=\mathrm{1,2},...,K_m$

wherein, P_iAnd P_jThe window powers of the ith and jth windows are indicated, respectively.

4. The channel estimation method based on TD-SCDMA combined detection technology according to claim 1, characterized in that the preliminarily estimated channel impulse responses of all windows of the user are weighted and combined by the following formula:

<math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mrow> <mo>[</mo> <msub> <mi>G</mi> <mi>i</mi> </msub> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> </mrow> </math>

wherein,

denotes the result of the weighted combining process, K_mIndicates the number of all windows of the user,

for preliminary estimation of channel impulse response, G, of the ith window of the user_iAre weighting factors and satisfy the condition that,

$\frac{G_i}{G_j}=\sqrt{\frac{m_i}{m_j}},i=\mathrm{1,2},...,K_m,j=\mathrm{1,2},...,K_m$

wherein m is_iAnd m_jThe number of code channels of the ith and j windows respectively.

5. The method of any of claims 1-4, wherein the result of the weighted combining process is determined as the improved channel impulse response of each window or code channel.

6. The method of any of claims 1-4, wherein the step of determining the improved channel impulse response of each window or code channel according to the result of the weighted combining process comprises:

carrying out average operation processing on the result of the weighted combination processing;

respectively carrying out amplitude reduction processing on the results of the average operation processing;

and determining the result of the amplitude reduction processing as the improved channel impulse response of the corresponding window.

7. The TD-SCDMA combined detection method based on channel estimation method according to claim 6, wherein the weighted combination result is averaged by the following formula:

<math> <mrow> <mi>A</mi> <mo>=</mo> <mfrac> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mi>&eta;</mi> </mfrac> </mrow> </math>

wherein, <math> <mrow> <mi>&eta;</mi> <mo>=</mo> <msqrt> <munderover> <mi>&Sigma;</mi> <mrow> <mi>g</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>W</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msubsup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> <mrow> <mo>(</mo> <mi>g</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> </msqrt> </mrow> </math> or <math> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <msub> <mi>m</mi> <mi>i</mi> </msub> <mo>,</mo> </mrow> </math>

To represent

W- * P/K *, P-128, K representing the maximum number of windows contained in a slot, m_iIndicating the number of code channels, P, of the ith window_iRepresenting the window power of the ith window.

8. Such asThe method of claim 7, wherein the method comprises the step of estimating the channel based on TD-SCDMA combined detection technology <math> <mrow> <mi>&eta;</mi> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <msub> <mi>m</mi> <mi>i</mi> </msub> </mrow> </math> Then, a is determined as the improved channel impulse response of each code channel.

9. The TD-SCDMA combined detection method based on channel estimation method according to claim 7, wherein the average operation result is respectively processed with amplitude reduction by the following formulas:

<math> <mrow> <msub> <mi>h</mi> <mrow> <mi>av</mi> <mo>,</mo> <mi>n</mi> </mrow> </msub> <mo>=</mo> <msqrt> <msub> <mi>m</mi> <mi>n</mi> </msub> </msqrt> <mo>&CenterDot;</mo> <mi>A</mi> </mrow> </math> or <math> <mrow> <msub> <mi>h</mi> <mrow> <mi>av</mi> <mo>,</mo> <mi>n</mi> </mrow> </msub> <mo>=</mo> <msqrt> <msub> <mi>P</mi> <mi>n</mi> </msub> </msqrt> <mo>&CenterDot;</mo> <mi>A</mi> <mo>,</mo> <mi>n</mi> <mo>=</mo> <mn>1,2</mn> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>K</mi> <mi>m</mi> </msub> </mrow> </math>

Wherein h is_av，nRepresenting the improved channel impulse response for the nth window.

10. As claimed inThe TD-SCDMA combined detection technology-based channel estimation method of claim 9, wherein K is_mIndicating the number of all active windows of the user.

11. The method of claim 10, wherein before the averaging the weighted combining result, the method further comprises: and estimating the number of the active code channels of the last active window of the user.

12. The channel estimation method based on TD-SCDMA joint detection technology as claimed in claim 11, wherein the step of estimating the number of active code channels of the last active window of the current user comprises:

the average code power p of all the active windows except the last active window is obtained by the following formula_av，

<math> <mrow> <msub> <mi>p</mi> <mi>av</mi> </msub> <mo>=</mo> <mfrac> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>p</mi> <mi>i</mi> </msub> </mrow> <mrow> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>m</mi> <mi>i</mi> </msub> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

The number m of the active code channels of the last active window is obtained by the following formula_Km，

$m_{K_m}=\mathrm{round}\left(\frac{P_{K_m}}{P_{\mathrm{av}}}\right)$

Wherein, K_mIndicating the number of active windows owned by the user, P_iWindow power, m, representing the ith active window_iThe number of code channels for the ith active window, $\mathrm{round}\left(\frac{P_{K_m}}{P_{\mathrm{av}}}\right)$ presentation pair $\frac{P_{K_m}}{P_{\mathrm{av}}}$ Rounded values are taken.

13. The TD-SCDMA combined detection technology-based channel estimation method according to claim 7, characterized in that, the P is a CDMA system_iObtained from the following equation:

<math> <mrow> <msub> <mi>P</mi> <mi>i</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>g</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>W</mi> </munderover> <msup> <mrow> <mo>|</mo> <mo>|</mo> <msubsup> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </msubsup> <mo>|</mo> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mo>,</mo> <mi>i</mi> <mo>=</mo> <mn>1,2</mn> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>K</mi> <mi>m</mi> </msub> <mo>,</mo> <mi>g</mi> <mo>=</mo> <mn>1,2</mn> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <mi>W</mi> </mrow> </math>

wherein,is composed ofThe t-th element of (1).

14. The method for channel estimation based on TD-SCDMA combined detection technology according to any of the claims 1-4, characterized in that it further comprises:

carrying out weighting and merging processing on the preliminarily estimated channel impulse responses of all the activation windows of the user;

and determining the improved channel impulse response of each active window or active code channel according to the result of the weighted combination processing.

15. The channel estimation method based on TD-SCDMA combined detection technology according to claim 1, characterized in that the preliminarily estimated channel impulse responses of all windows of the user are weighted and combined by the following formula:

<math> <mrow> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <mo>=</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <msub> <mi>K</mi> <mi>m</mi> </msub> </munderover> <mrow> <mo>[</mo> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>i</mi> </msub> <mo>]</mo> </mrow> </mrow> </math>

wherein,

represents the result of the weighted combination process,

indicating the channel impulse response of the ith or active window, K_mThe number of all windows or activated windows of the user is represented, the weighting factor is 1, and the improved channel impulse response of each window is obtained by the following formula:

<math> <mrow> <msub> <mi>h</mi> <mi>av</mi> </msub> <mo>=</mo> <mfrac> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>wei</mi> </msub> <msub> <mi>K</mi> <mi>m</mi> </msub> </mfrac> </mrow> </math>

wherein h is_avImproved channel impulse response for each window or activation window.

16. The channel estimation method based on TD-SCDMA combined detection technology according to claim 1, characterized in that the preliminarily estimated channel impulse responses of all windows of the user are weighted and combined by the following formula:

<math> <mrow> <msub> <mi>h</mi> <mi>av</mi> </msub> <mo>=</mo> <msub> <munderover> <mi>h</mi> <mo>&OverBar;</mo> <mo>^</mo> </munderover> <mi>m</mi> </msub> <mo>,</mo> <mi>m</mi> <mo>=</mo> <mn>1,2</mn> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>K</mi> <mi>m</mi> </msub> </mrow> </math>

wherein h is_avFor each window of improved channel impulse response,

represents the channel impulse response of the window with the largest window power among all the windows,the corresponding weighting factor is 1 and the weighting factors corresponding to the other windows are 0.

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