CN103326967B - Channel estimation methods and device - Google Patents

Abstract

The present invention relates to a channel estimation method and device. The method includes: performing initial channel estimation on a received signal to obtain an initial channel estimation value, the initial channel estimation value including a K×W channel impulse response; according to The initial channel estimation value is to perform activation window detection on K windows in a time slot to obtain N activation windows in the time slot; channel impulse responses for paths in which the N activation windows are located at the same position Perform cumulative averaging to obtain an average channel estimate; use the average channel estimate to replace the initial channel estimate at the same position corresponding to the N activation windows, and output it as a channel estimate. The invention can effectively suppress noise and improve the performance of system channel estimation.

Description

Channel estimation method and device

technical field

The present invention relates to the technical field of mobile communication, in particular to a channel estimation method and device.

Background technique

Code Division Multiple Access (CDMA) is a wireless communication technology based on spread spectrum. Compared with the Global System for Mobile Communications (GSM), CDMA has many advantages such as broadband, large capacity, and strong anti-fading and interference capabilities, and has become the basic technology of 3G mobile communications. At present, 3G mobile communication commercial networks based on CDMA are widely used all over the world. There are three technical standards: Wideband Code Division Multiple Access (WCDMA), CDMA2000 and Time Division-Synchronous Code Division Multiple Access (Time Division-Synchronous Code Division Multiple Access). Access, TD-SCDMA).

Coherent demodulation in CDMA system needs to estimate the channel impulse response. Channel estimation is based on pilots. For WCDMA, CDMA2000 and TD-SCDMA systems, there are respective pilot patterns. For example, in TD-SCDMA system, pilots are called midambles. The frame structure of the TD-SCDMA system is shown in Figure 1. A 10ms radio frame consists of 2 5ms subframes, each with 7 regular time slots (TS0-TS6) and 3 special time slots (DwPTS, GP, UpPTS). The conventional time slot structure is shown in Figure 2. The middle training sequence is placed in the middle 144 chips of each regular time slot, and there are 352 chips at both ends of the middle training sequence, which are used to place data. There is a guard interval (Gap Period, GP) of 16 chips at the end of the regular time slot. The midamble codes used by different users in the same time slot are generated by cyclically shifting the basic midamble codes with a length of 128.

The channel estimation in the TD-SCDMA system is generally B.Steiner algorithm to obtain the initial channel estimation (references Steiner B, Baier P W.Low cost channel estimation in the uplink receiver of CDMA mobile radio systems.Frequenz,1993,47(11 /12):292-298.), to get the initial channel impulse response with a length of 128, which consists of K windows. In the existing TD-SCDMA system, after the initial channel estimation is obtained, each activation window is generally processed independently, and the processing between different activation windows is rarely involved.

When more than 2 code channels are allocated to a user in a time slot, that is, more than one window, it is difficult to effectively suppress noise, resulting in loss of channel estimation performance. It is a common situation in TD-SCDMA systems that the number of code channels allocated to users exceeds 2 in one time slot.

Contents of the invention

The purpose of the present invention is to provide a channel estimation method and device with good performance gain, which can effectively suppress noise and improve the performance of system channel estimation when multiple windows are allocated to users in one time slot.

To achieve the above object, the first aspect of the present invention provides a channel estimation method, the method comprising:

Perform initial channel estimation on the received signal to obtain an initial channel estimation value, the initial channel estimation value includes a K×W channel impulse response, where K represents the number of windows included in a time slot, and W represents the number of paths included in a window;

According to the initial channel estimation value, perform active window detection on K windows in a time slot to obtain N active windows in the time slot, where N is the number of active windows, and N≤K;

Accumulating and averaging the channel impulse responses of the paths where the N activation windows are located at the same position, to obtain an average channel estimation value;

The average channel estimation value is used to replace the initial channel estimation value corresponding to the same position of the N activation windows as a channel estimation value output.

With reference to the first aspect, in a first possible implementation manner of the first aspect, the channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimation value, including:

According to the formula Accumulating and averaging the channel impulse responses of the paths with the N activation windows at the same position to obtain an average channel estimate value of the paths at the same position;

Among them, h _k,j is the channel impulse response of the j-th path of the k-th window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N.

With reference to the first aspect, in a second possible implementation manner of the first aspect, when the number of configured code channels is an odd number, the channel impulse responses of the paths whose N activation windows are located at the same position are performed Accumulate the average to get the average channel estimate, including:

According to the formula The channel impulse responses of the paths at the same position in the first N-1 activation windows are accumulated and averaged to obtain the average channel estimation value of the paths at the same position in the first N-1 activation windows;

According to the formula Obtain the average channel estimation value of each path in the Nth activation window;

Among them, h _k,j is the channel impulse response of the j-th path of the k-th window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N.

With reference to the first aspect, in a third possible implementation manner of the first aspect, when the number of configured code channels is an odd number, the channel impulse responses of the paths whose N activation windows are located at the same position are performed Accumulate the average to get the average channel estimate, including:

According to the formula The channel impulse responses of the paths at the same position in the first N-1 activation windows are accumulated and averaged to obtain the average channel estimation value of the paths at the same position in the first N-1 activation windows;

According to the formula Obtain the average channel estimation value of each path in the Nth activation window;

Among them, h _{k, j} is the channel impulse response of the j-th path of the k-th window before the cumulative average, hj is the average channel estimation value of the j-th path, j=1,...,W, k= 1,...,N.

With reference to the first possible implementation manner, the second possible implementation manner, or the third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, in the obtaining the average channel estimate After the value, also include:

According to the formula Perform weighting processing on the average channel estimation value of the path where the N activation windows are located at the same position, wherein, i=1,...,N, Factor _i,j is the weighting factor of the jth path of the i-th activation window , is the average channel estimate of the jth path, is the average channel estimation value of the i-th activation window j-th path after weighting;

Said using said average channel estimated value to replace said initial channel estimated value corresponding to said same position of said N activation windows as a channel estimated value output, comprising:

The weighted average channel estimation value is output as the channel estimation value instead of the initial channel estimation value corresponding to the same position of the N activation windows.

With reference to the fourth possible implementation manner of the first aspect, in the fifth possible implementation manner of the first aspect, the weighting factor Factor _{i, j} is the path signal-to-noise ratio of the jth path of the ith activation window ;

Alternatively, the weighting factors Factor _{i, j} are valued according to a preset effective path interval.

With reference to the first aspect, in a sixth possible implementation manner of the first aspect, the method further includes:

Detecting the physical channel type in the time slot;

When multiple types of physical channels are included in the time slot, the channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimation value, including: respectively for different types is a physical channel, the channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimation value.

With reference to the first aspect, in the seventh possible implementation manner of the first aspect, after obtaining the activation window in the time slot, the method further includes:

Set the active window flag for the window whose detection result is the active window;

The channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimation value, including:

According to the active window flag, the channel impulse responses of the N active windows at the same position are accumulated and averaged to obtain an average channel estimation value.

In the second aspect, the present invention also provides a channel estimation device, which includes: an initial channel estimation unit, an active window detection unit, an accumulation and averaging unit, and an output unit;

The initial channel estimation unit is configured to perform initial channel estimation on the received signal to obtain an initial channel estimation value, and the initial channel estimation value includes a channel impulse response of K×W diameter, where K represents The number of included windows, W represents the number of paths included in a window;

The active window detection unit is configured to perform active window detection on K windows in one time slot according to the initial channel estimation value obtained by the initial channel estimation unit, to obtain N active windows in the time slot , where N is the number of activation windows, N≤K;

The accumulative average unit is configured to perform accumulative average on the channel impulse responses of the N active windows located at the same position obtained by the active window detection unit, to obtain an average channel estimation value;

The output unit is configured to use the average channel estimate obtained by the accumulative average unit to replace the initial channel estimate corresponding to the same position of the N activation windows as a channel estimate output.

With reference to the second aspect, in a first possible implementation manner of the second aspect, the accumulative average unit is based on the formula Accumulate and average the channel impulse responses of the paths with the N active windows at the same position obtained by the active window detection unit to obtain the average channel estimated value of the paths at the same position; where h _{k, j} are cumulative averaged The channel impulse response of the j-th path of the k-th window, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N.

With reference to the second aspect, in a second possible implementation manner of the second aspect, when the number of configured code channels is an odd number, the accumulative averaging unit according to the formula Accumulating and averaging the channel impulse responses of the paths with the same position of the first N-1 active windows obtained by the active window detection unit to obtain an average channel estimate value of the paths at the same position in the first N-1 active windows; and According to the formula Obtain the average channel estimate value of each path in the Nth active window obtained by the active window detection unit; wherein, _hk,j is the channel impulse response of the jth path of the kth window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N.

With reference to the second aspect, in a third possible implementation manner of the second aspect, when the number of configured code channels is an odd number, the accumulative averaging unit according to the formula Accumulating and averaging the channel impulse responses of the paths with the same position of the first N-1 active windows obtained by the active window detection unit to obtain an average channel estimate value of the paths at the same position in the first N-1 active windows; and According to the formula Obtain the average channel estimate value of each path in the Nth active window obtained by the active window detection unit; wherein, _hk,j is the channel impulse response of the jth path of the kth window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N.

With reference to the first possible implementation manner or the second possible implementation manner or the third possible implementation manner of the second aspect, in a fourth possible implementation manner of the second aspect, the device further includes: weighting unit, the weighting unit is connected to the accumulative average unit for according to the formula Perform weighting processing on the average channel estimation value of the N activation windows located at the same position obtained by the accumulation and averaging unit, wherein, i=1,...,N, Factor _{i, j} is the i-th activation window The weighting factor for the jth path, is the average channel estimate of the jth path, is the average channel estimation value of the i-th activation window j-th path after weighting;

The output unit outputs the average channel estimation value weighted by the weighting unit instead of the initial channel estimation value at the same position corresponding to the N activation windows as the channel estimation value.

With reference to the fourth possible implementation manner of the second aspect, in the fifth possible implementation manner of the second aspect, the weighting Factor _i,j in the weighting unit is the path of the jth path of the ith activation window SNR;

Alternatively, the weighting factors Factor _{i, j} are valued according to a preset effective path interval.

With reference to the second aspect, in a sixth possible implementation manner of the second aspect, the device further includes: a channel type detection unit connected to the accumulation and averaging unit for detecting the The type of physical channel in the time slot; when the channel type detection unit detects that multiple types of physical channels are included in the time slot, the accumulation and averaging unit activates the N channels for different types of physical channels The channel impulse responses of paths with windows at the same position are accumulated and averaged to obtain the average channel estimate.

With reference to the second aspect, in a seventh possible implementation manner of the second aspect, after the activation window in the time slot is obtained by the activation window detection unit, it is further configured to set an activation window whose detection result is an activation window. window sign;

The accumulative average unit performs accumulative average on the channel impulse responses of the paths with the N active windows at the same position according to the active window flag, to obtain an average channel estimation value.

In the channel estimation method and device provided by the present invention, for the case of assigning multiple windows to a user in one time slot, the paths at the same position in multiple activation windows in the same time slot are accumulated and averaged to replace the original channel The estimated value can effectively suppress noise and improve the performance of channel estimation in TD-SCDMA system.

Description of drawings

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

Fig. 2 is a schematic diagram of a conventional time slot structure of a TD-SCDMA system;

FIG. 3 is a flowchart of a channel estimation method provided in Embodiment 1 of the present invention;

FIG. 4 is a schematic diagram of a channel estimation device provided by Embodiment 2 of the present invention.

detailed description

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

The flow chart of the channel estimation method provided by the embodiment of the present invention is applicable to a TD-SCDMA system, and can also be applied to a system similar to the TD-SCDMA system with the cyclic shift characteristic of the training sequence.

Embodiment one

Fig. 3 is a flow chart of the channel estimation method provided in this embodiment, as shown in Fig. 3, the method of the present invention includes:

S101. Perform initial channel estimation on a received signal to obtain an initial channel estimation value.

In the embodiment of the present invention, but not limited to, the initial channel estimation can be obtained through the B. Steiner algorithm, so as to obtain the initial channel impulse response with a length of P=128, which consists of K windows.

In general, the received signal model of the intermediate training sequence part is:

y=Gh+n

Among them, the matrix G is a P*KW order matrix obtained by cyclically shifting the intermediate training sequence codes of K users:

$\mathrm{<span\; class="notranslate">\; G</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{ccccccccccccc}{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& <span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&CenterDot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& <span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&CenterDot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}}& <span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}}& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}& <span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&CenterDot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>\\ <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>\\ <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&CenterDot;</span>& <span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& <span\; class="notranslate">\; \&Center\; Dot;</span>\\ {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; W</span>}}& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}}& <span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>& {\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}\end{array}\right]$

h=[h _1,1 ,h _1,2 ...,h _1,W ,h _2,1 ,h _2,2 ...,h _2,W ,...,h _K,1 ,h _K,2 ...,h _{K , W} ] ^T is the vector formed by the channel impulse responses of K users arranged together, W is the length of each user's channel impulse response, and P=128 is the length of the basic mid-training sequence in TD-SCDMA. Usually P=KW, then G is a circulant matrix of order 128*128. According to the B.Steiner algorithm, the least squares estimate of h is h Due to the cyclic shift characteristic of midamble code in TD-SCDMA system, can be simplified to: $\hat{h}=\mathrm{IFFT}(\mathrm{FFT}\left(\mathrm{the\; y}\right)/\mathrm{FFT}\left(m\right)),$ Among them: m is the first column of matrix G.

The channel impulse response of the kth user can be expressed as Where k=1,...,K, K is the number of windows included in a time slot (the maximum number of users), which is obtained by high-level signaling configuration, Usually h ^(k) is called the channel impulse response of the kth window.

The task of channel estimation is to estimate the channel impulse response of all K windows (corresponding to K users) from the received signal. Therefore, the initial channel estimation value obtained by the B. Steiner algorithm includes the channel impulse of K×W diameter Response, where K represents the number of windows included in a time slot, and W represents the number of paths included in a window, that is, the window length of channel estimation.

S102. According to the initial channel estimation value, perform active window detection on K windows in a time slot to obtain N active windows in the time slot, where N is the number of active windows, and N≤K.

The detection of the activation window can be performed but not limited to by setting a threshold value. The setting of the threshold value can be calculated by taking the modulus (that is, the square of the real part plus the square of the imaginary part) to obtain the power of 128 paths, from Select the path with the strongest power from the 128 paths, multiply the power of the strongest path by a factor (for example, 1/16) as the set threshold value, and then judge whether there is a path exceeding the threshold value in a window. The number of paths, and the windows whose number meets certain requirements are detected as active windows.

Alternatively, select a window with the strongest power from the 128 paths, multiply the power of the window by a factor as a set threshold value, and detect a window whose power exceeds the threshold value as an active window, and so on.

Optionally, obtaining N active windows in the time slot at S102 further includes: setting an active window flag for a window whose detection result is an active window.

S103. Accumulate and average the channel impulse responses (that is, calculate the average value) of the channel impulse responses of the N activation windows located at the same position, to obtain an average channel estimation value.

Optionally, according to the active window flag set in S102, the channel impulse responses of the N active windows at the same position are accumulated and averaged to obtain an average channel estimation value.

Specifically, according to the formula Accumulating and averaging the channel impulse responses of the paths with the N activation windows at the same position to obtain an average channel estimation value of the paths at the same position.

Among them, h _k,j is the channel impulse response of the j-th path of the k-th window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N.

In a typical scenario of a TD-SCDMA system, if the number of code channels M configured by high-level signaling for the user is an odd number, then the first (M-1)/2 windows are all allocated with 2 code channels, and the last window is allocated one yard track.

Optionally, for the case where the number of code channels configured for the user by high-level signaling is an odd number, the formula The channel impulse responses of the paths at the same position in the first N-1 activation windows are accumulated and averaged to obtain the average channel estimate of the paths at the same position in the first N-1 activation windows; and according to the formula Obtain the average channel estimation value of each path in the Nth activation window; where, h _{k, j} is the channel impulse response of the jth path of the kth window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N. That is to say, the last activation window does not participate in the process of cumulative averaging.

Or, for the case where the number of code channels configured for the user by high-level signaling is an odd number, it can also be based on the formula The channel impulse responses of the paths at the same position in the first N-1 activation windows are accumulated and averaged to obtain the average channel estimate of the paths at the same position in the first N-1 activation windows; according to the formula Obtain the average channel estimation value of each path in the Nth activation window; where, h _{k, j} is the channel impulse response of the jth path of the kth window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N. That is to say, the last activation window also participates in the process of cumulative averaging.

In addition, considering that multiple types of physical channels may be included in the same time slot, in this case, the method in the embodiment of the present invention may further include: a step of detecting the type of the physical channel in the time slot.

When multiple types of physical channels are included in the time slot, S103 is to accumulate and average the channel impulse responses of the paths with the N activation windows at the same position for different types of physical channels to obtain an average channel estimate value.

S104. Use the average channel estimation value to replace the initial channel estimation value corresponding to the same position of the N activation windows as a channel estimation value output.

Optionally, after the average channel estimation value is obtained in S103, it also includes:

According to the formula Perform weighting processing on the average channel estimation value of the path where the N activation windows are located at the same position, wherein, i=1,...,N, Factor _i,j is the weighting factor of the jth path of the i-th activation window , is the average channel estimate of the jth path, is the average channel estimation value of the j-th path of the i-th activation window after weighting.

Furthermore, the weighted average channel estimation value is output as the channel estimation value instead of the initial channel estimation value at the same position corresponding to the N activation windows.

Wherein, the weighted Factor _{i, j} is the path SNR of the jth path of the i-th activation window; or, the weighted factor Factor _{i, j} is valued according to a preset effective path interval. For example, an effective path interval can be defined, and the weighting factor of paths within the effective path interval is 1; the weighting factor of paths outside the effective path interval is 0.

It should be noted that other subsequent processing may be performed on the channel estimation value to be output before the channel estimation value is output in S104, and the subsequent processing includes normalization, or filtering channel estimation values smaller than a preset threshold, etc., Output channel estimation values that meet the requirements of practical applications.

The channel estimation method provided by the present invention replaces the original channel estimation value by performing cumulative and average processing on paths at the same position in multiple activation windows of the same time slot, especially for users who allocate multiple windows in one time slot It can suppress the noise effectively and improve the channel estimation performance of TD-SCDMA system.

The above is the detailed description of the channel estimation method provided by the present invention, and the channel estimation device provided by the present invention will be described in detail below.

Embodiment two

FIG. 4 is a schematic diagram of a channel estimation device provided in this embodiment. As shown in FIG. 4 , the channel estimation device of the present invention includes: an initial channel estimation unit 10 , an active window detection unit 20 , an accumulation and averaging unit 30 and an output unit 40 .

The initial channel estimation unit 10 is configured to perform initial channel estimation on the received signal to obtain an initial channel estimation value.

The initial channel estimation unit 10 of the embodiment of the present invention may, but not limited to, obtain the initial channel estimation through the B. Steiner algorithm, so as to obtain the initial channel impulse response with a length of P=128, which consists of K windows.

The task of channel estimation is to estimate the channel impulse responses of all K windows (corresponding to K users) from the received signal. Therefore, the initial channel estimation value obtained by the initial channel estimation unit 10 through the B. Steiner algorithm includes K×W pieces The channel impulse response of the paths, where K represents the number of windows included in a time slot, and W represents the number of paths included in a window, that is, the window length of channel estimation.

The active window detection unit 20 is configured to perform active window detection on K windows in a time slot according to the initial channel estimation value obtained by the initial channel estimation unit 10, to obtain N active windows in the time slot. Among them, N is the number of activation windows, N≤K.

The active window detection unit 20 can, but is not limited to, detect by setting a threshold value. The setting of the threshold value can first be calculated by taking a modulus (that is, the square of the real part plus the square of the imaginary part) to obtain the power of 128 paths. Select the path with the strongest power from the 128 paths, multiply the power of the strongest path by a factor (for example, 1/16) as the set threshold value, and then judge whether there is a window exceeding the threshold value The number of paths, and the windows whose number meets certain requirements are detected as active windows.

Alternatively, the active window detection unit 20 selects a window with the strongest power from the 128 paths, multiplies the power of the window by a factor as a set threshold value, and detects a window whose power exceeds the threshold value as an active window ,etc.

Optionally, after obtaining the active windows in the time slot, the active window detection unit 20 is further configured to set an active window flag for a window whose detection result is an active window.

The accumulative averaging unit 30 is configured to perform accumulative averaging on the channel impulse responses obtained by the active window detection unit 20 for paths with the N active windows located at the same position, to obtain an average channel estimation value.

Optionally, the accumulative averaging unit 30 performs accumulative averaging on the channel impulse responses of the paths with the N active windows at the same position according to the active window flag set by the active window detection unit 20 to obtain an average channel estimation value.

Specifically, the accumulative average unit 30 according to the formula The channel impulse responses of the paths with the N active windows at the same position obtained by the active window detection unit 20 are accumulated and averaged to obtain an average channel estimation value of the paths at the same position.

Among them, h _k,j is the channel impulse response of the j-th path of the k-th window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N.

In a typical scenario of a TD-SCDMA system, if the number of code channels M configured by high-level signaling for the user is an odd number, then the first (M-1)/2 windows are all allocated with 2 code channels, and the last window is allocated one yard track.

Optionally, for the case where the number of code channels configured for the user by high-level signaling is an odd number, the accumulation and averaging unit 30 can be based on the formula The channel impulse responses of the paths at the same position in the first N-1 activation windows obtained by the activation window detection unit 20 are accumulated and averaged to obtain the average channel estimate of the paths at the same position in the first N-1 activation windows; and according to formula The average channel estimation value of each path in the Nth active window obtained by the active window detection unit 20 is obtained. Among them, h _k,j is the channel impulse response of the j-th path of the k-th window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N.

Or, for the situation that the number of code channels configured by the high-level signaling for the user is an odd number, the cumulative average unit 30 can also be based on the formula The channel impulse responses of the paths at the same position in the first N-1 activation windows obtained by the activation window detection unit 20 are accumulated and averaged to obtain the average channel estimate of the paths at the same position in the first N-1 activation windows; and according to formula The average channel estimation value of each path in the Nth active window obtained by the active window detection unit 20 is obtained. Among them, h _k,j is the channel impulse response of the j-th path of the k-th window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N.

In addition, considering that the same time slot may contain multiple types of physical channels, in this case, the channel estimation device in this embodiment may further include: a channel type detection unit (not shown in the figure), the channel The type detection unit is connected with the cumulative average unit 30, and is used for detecting the type of the physical channel in the time slot.

When the channel type detection unit detects that multiple types of physical channels are included in the time slot, the accumulation and averaging unit 30 calculates the channels of the N activation windows at the same position for different types of physical channels. The excitation responses are accumulated and averaged to obtain the average channel estimate.

The output unit 40 is configured to replace the initial channel estimation values at the same positions corresponding to the N activation windows with the average channel estimation value obtained by the accumulative averaging unit 30 and output it as a channel estimation value.

Optionally, the channel estimation device in the embodiment of the present invention further includes: a weighting unit (not shown in the figure), the weighting unit is connected to the cumulative average unit 30, and is used to Perform weighting processing on the average channel estimation value of the N activation windows obtained by the cumulative averaging unit 30 at the same position, wherein, i=1,...,N, Factor _{i, j} is the ith activation window weighting factor for j diameters, is the average channel estimate of the jth path, is the average channel estimation value of the j-th path of the i-th activation window after weighting.

The output unit 40 replaces the initial channel estimation values at the same positions corresponding to the N activation windows with the average channel estimation value after the weighting process by the weighting unit, and outputs as the channel estimation value.

Wherein, the weighted Factor _{i, j} in the weighting unit is the signal-to-noise ratio of the jth path of the i-th activation window; or, the weighted factor Factor _{i, j} is valued according to a preset effective path interval. For example, an effective path interval can be defined, and the weighting factor of paths within the effective path interval is 1; the weighting factor of paths outside the effective path interval is 0.

It should be noted that, before outputting the channel estimation value, the output unit 40 may also perform other subsequent processing on the channel estimation value to be output, and the subsequent processing includes normalization, or filtering channel estimation values smaller than a preset threshold, etc. , and output channel estimation values that meet the requirements of practical applications.

The channel estimation method and device provided by the invention can improve the channel estimation performance of a CDMA system (especially a TD-SCDMA system). In particular, when more than 2 code channels are allocated in one time slot, that is, more than one window, noise can be effectively suppressed, with obvious performance gain. For CDMA systems, the improvement of channel estimation performance is manifested in the following aspects: 1) For dedicated traffic channels, the block error rate can be reduced; 2) For HSPA/HSPA+ traffic channels, system throughput can be improved; 3) For control channel, which can reduce the block error rate and improve the reliability of signaling.

Each unit in the device mentioned in this embodiment can be implemented by a logic integrated circuit and integrated on an integrated circuit substrate.

Professionals should further realize that the units and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the relationship between hardware and software Interchangeability. In the above description, the components and steps of each example have been generally described according to their functions. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be implemented by hardware, software modules executed by a processor, or a combination of both. Software modules can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other Any other known storage medium.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (16)

1. A method for channel estimation, characterized in that the method comprises: Perform initial channel estimation on the received signal to obtain an initial channel estimation value, the initial channel estimation value includes a K×W channel impulse response, where K represents the number of windows included in a time slot, and W represents the number of paths included in a window; According to the initial channel estimation value, perform active window detection on K windows in a time slot to obtain N active windows in the time slot, where N is the number of active windows, and N≤K; Accumulating and averaging the channel impulse responses of the paths where the N activation windows are located at the same position, to obtain an average channel estimation value; Using the average channel estimation value to replace the initial channel estimation value corresponding to the same position of the N activation windows as a channel estimation value output; When the number of configured code channels is an odd number, the channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimate, including: According to the formula The channel impulse responses of the paths at the same position in the first N-1 activation windows are accumulated and averaged to obtain the average channel estimation value of the paths at the same position in the first N-1 activation windows; According to the formula Obtain the average channel estimation value of each path in the Nth activation window; Among them, h _k,j is the channel impulse response of the j-th path of the k-th window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N. 2. The method according to claim 1, characterized in that, after obtaining the average channel estimate, further comprising: According to the formula Perform weighting processing on the average channel estimation value of the path where the N activation windows are located at the same position, where i=1,...,N, Factor _i,j is the weighting factor of the jth path of the i-th activation window , is the average channel estimate of the jth path, is the average channel estimation value of the i-th activation window j-th path after weighting; Said using said average channel estimated value to replace said initial channel estimated value corresponding to said same position of said N activation windows as a channel estimated value output, comprising: The weighted average channel estimation value is output as the channel estimation value instead of the initial channel estimation value corresponding to the same position of the N activation windows. 3. The method according to claim 2, wherein the weighting factor Factor _i,j is the path signal-to-noise ratio of the i-th activation window j-th path; Alternatively, the weighting factors Factor _{i, j} are valued according to a preset effective path interval. 4. The method according to claim 1, wherein the method further comprises: Detecting the physical channel type in the time slot; When multiple types of physical channels are included in the time slot, the channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimation value, including: respectively for different types is a physical channel, the channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimation value. 5. A channel estimation method, characterized in that the method comprises: Perform initial channel estimation on the received signal to obtain an initial channel estimation value, the initial channel estimation value includes a K×W channel impulse response, where K represents the number of windows included in a time slot, and W represents the number of paths included in a window; According to the initial channel estimation value, perform active window detection on K windows in a time slot to obtain N active windows in the time slot, where N is the number of active windows, and N≤K; Accumulating and averaging the channel impulse responses of the paths where the N activation windows are located at the same position, to obtain an average channel estimation value; Using the average channel estimation value to replace the initial channel estimation value corresponding to the same position of the N activation windows as a channel estimation value output; When the number of configured code channels is an odd number, the channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimate, including: According to the formula The channel impulse responses of the paths at the same position in the first N-1 activation windows are accumulated and averaged to obtain the average channel estimation value of the paths at the same position in the first N-1 activation windows; According to the formula Obtain the average channel estimation value of each path in the Nth activation window; Among them, h _k,j is the channel impulse response of the j-th path of the k-th window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N. 6. The method according to claim 5, characterized in that, after said obtaining the average channel estimate, further comprising: According to the formula Perform weighting processing on the average channel estimation value of the path where the N activation windows are located at the same position, wherein, i=1,...,N, Factor _{i, j} is the weighting factor of the jth path of the i-th activation window , is the average channel estimate of the jth path, is the average channel estimation value of the i-th activation window j-th path after weighting; Said using said average channel estimated value to replace said initial channel estimated value corresponding to said same position of said N activation windows as a channel estimated value output, comprising: The weighted average channel estimation value is output as the channel estimation value instead of the initial channel estimation value corresponding to the same position of the N activation windows. 7. The method according to claim 6, wherein the weighting factor Factor _{i, j} is the path signal-to-noise ratio of the i-th activation window j-th path; Alternatively, the weighting factors Factor _{i, j} are valued according to a preset effective path interval. 8. The method according to claim 5, further comprising: Detecting the physical channel type in the time slot; When multiple types of physical channels are included in the time slot, the channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimation value, including: respectively for different types is a physical channel, the channel impulse responses of the N activation windows located at the same position are accumulated and averaged to obtain an average channel estimation value. 9. A channel estimation device, characterized in that the device comprises: an initial channel estimation unit, an active window detection unit, an accumulation and averaging unit, and an output unit; The initial channel estimation unit is configured to perform initial channel estimation on the received signal to obtain an initial channel estimation value, and the initial channel estimation value includes a channel impulse response of K×W diameter, where K represents The number of included windows, W represents the number of paths included in a window; The active window detection unit is configured to perform active window detection on K windows in one time slot according to the initial channel estimation value obtained by the initial channel estimation unit, to obtain N active windows in the time slot , where N is the number of activation windows, N≤K; The accumulative average unit is configured to perform accumulative average on the channel impulse responses of the N active windows located at the same position obtained by the active window detection unit, to obtain an average channel estimation value; The output unit is configured to use the average channel estimate obtained by the accumulative average unit to replace the initial channel estimate at the same position corresponding to the N activation windows as a channel estimate output; When the number of code channels configured is an odd number, the cumulative average unit according to the formula Accumulating and averaging the channel impulse responses of the paths with the same position of the first N-1 active windows obtained by the active window detection unit to obtain an average channel estimate value of the paths at the same position in the first N-1 active windows; and According to the formula Obtain the average channel estimate value of each path in the Nth active window obtained by the active window detection unit; wherein, _hk,j is the channel impulse response of the jth path of the kth window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N. 10. The device according to claim 9, characterized in that, the device further comprises: a weighting unit, the weighting unit is connected with the cumulative average unit, for according to the formula Perform weighting processing on the average channel estimation value of the N activation windows at the same position obtained by the accumulation and averaging unit, wherein, i=1,...,N, Factor _{i, j} is the ith activation window The weighting factor for the jth path, is the average channel estimate of the jth path, is the average channel estimation value of the i-th activation window j-th path after weighting; The output unit outputs the average channel estimation value weighted by the weighting unit instead of the initial channel estimation value at the same position corresponding to the N activation windows as the channel estimation value. 11. The device according to claim 10, wherein the weighted Factor _{i, j} in the weighting unit is the path signal-to-noise ratio of the j-th path of the i-th activation window; Alternatively, the weighting factors Factor _{i, j} are valued according to a preset effective path interval. 12. The device according to claim 9, further comprising: a channel type detection unit connected to the cumulative average unit for detecting Physical channel type; when the channel type detection unit detects that multiple types of physical channels are included in the time slot, the cumulative averaging unit is located at the same position for the N activation windows for different types of physical channels The channel impulse response of the path is accumulated and averaged to obtain the average channel estimation value. 13. A channel estimation device, characterized in that the device comprises: an initial channel estimation unit, an active window detection unit, an accumulation and averaging unit, and an output unit; The initial channel estimation unit is configured to perform initial channel estimation on the received signal to obtain an initial channel estimation value, and the initial channel estimation value includes a channel impulse response of K×W diameter, where K represents The number of included windows, W represents the number of paths included in a window; The active window detection unit is configured to perform active window detection on K windows in one time slot according to the initial channel estimation value obtained by the initial channel estimation unit, to obtain N active windows in the time slot , where N is the number of activation windows, N≤K; The accumulative average unit is configured to perform accumulative average on the channel impulse responses of the N active windows located at the same position obtained by the active window detection unit, to obtain an average channel estimation value; The output unit is configured to use the average channel estimate obtained by the accumulative average unit to replace the initial channel estimate at the same position corresponding to the N activation windows as a channel estimate output; When the number of code channels configured is an odd number, the cumulative average unit according to the formula Accumulating and averaging the channel impulse responses of the paths with the same position of the first N-1 active windows obtained by the active window detection unit to obtain an average channel estimate value of the paths at the same position in the first N-1 active windows; and According to the formula Obtain the average channel estimate value of each path in the Nth active window obtained by the active window detection unit; wherein, _hk,j is the channel impulse response of the jth path of the kth window before the cumulative average, is the average channel estimation value of the jth path, j=1,...,W, k=1,...,N. 14. The device according to claim 13, characterized in that, the device further comprises: a weighting unit, the weighting unit is connected with the cumulative average unit, for according to the formula Perform weighting processing on the average channel estimation value of the N activation windows at the same position obtained by the accumulation and averaging unit, wherein, i=1,...,N, Factor _{i, j} is the ith activation window The weighting factor for the jth path, is the average channel estimate of the jth path, is the average channel estimation value of the i-th activation window j-th path after weighting; The output unit outputs the average channel estimation value weighted by the weighting unit instead of the initial channel estimation value at the same position corresponding to the N activation windows as the channel estimation value. 15. The device according to claim 14, wherein the weighted Factor _{i, j} in the weighting unit is the path signal-to-noise ratio of the jth path of the ith activation window; Alternatively, the weighting factors Factor _{i, j} are valued according to a preset effective path interval. 16. The device according to claim 13, further comprising: a channel type detection unit connected to the cumulative average unit for detecting Physical channel type; when the channel type detection unit detects that multiple types of physical channels are included in the time slot, the cumulative averaging unit is located at the same position for the N activation windows for different types of physical channels The channel impulse response of the path is accumulated and averaged to obtain the average channel estimation value.