JP4770467B2 - Receiving device, receiving method thereof, and control program - Google Patents

Description

  The present invention relates to a receiving apparatus, a receiving method thereof, and a control program, and more particularly to an LMMSE (Linear Minimum Square Error) receiver for realizing an optimum operation in a WCDMA (Wideband-Code Division Multiple Access) system. Relates to the control method.

  In a WCDMA system, an LMMSE receiver receives a conventional rake (hereinafter referred to as “RAKE”) in a multipath channel state (a state in which many paths exist) and a high SNR (Signal to Noise power Ratio) reception state. It is known that a higher performance gain than that of the apparatus can be obtained.

  On the other hand, the LMMSE receiver cannot fully perform its performance in a state where the number of paths is small (for example, a state where only one path exists) and a low SNR, and the performance gain is lower than that of the RAKE receiver. It is also known.

  In addition, if the LMMSE receiver allows a circuit to be complicated and large, it is possible to cope with a path that exists in a wide delay time range (delay spread). However, an actual LMMSE receiver only supports paths that exist in a limited delay time range in order to avoid circuit complexity and increase in size. Therefore, it is preferable to use a RAKE receiver for a path exceeding the limited delay time range.

  Therefore, there is a demand for a receiving apparatus that operates optimally under all receiving conditions, that is, a receiving apparatus that has two modes of LMMSE and RAKE and can switch modes appropriately according to the receiving condition.

  On the other hand, as an example of this type of prior art, a receiving apparatus that performs adaptive signal processing when the propagation path environment is multipath and performs selective diversity signal processing when other propagation path environments are disclosed (for example, Patent Document 1).

  As another example, a RAKE receiver is disclosed that performs waveform equalization processing using an adaptive equalizer on an input baseband signal (see, for example, Patent Document 2).

  As another example, a receiver using hypertrophic finger assignment and RAKE finger assignment is disclosed (for example, see Patent Document 3).

Japanese Patent Laying-Open No. 2002-232385 (paragraphs 0011 and 0037, FIG. 2) JP 2003-244027 A (paragraph 0015, FIG. 1) JP 2005-518132 A (summary)

  However, none of the above-mentioned patent documents discloses an LMMSE receiver that can be applied to a path that exists in a wide delay time range that the conventional LMMSE receiver cannot handle.

  Accordingly, an object of the present invention is a receiving apparatus including two receiving apparatuses, that is, an LMMSE receiving apparatus and a RAKE receiving apparatus, and the circuit is complicated and large even for a path exceeding the delay time range of the LMMSE receiving apparatus. It is an object of the present invention to provide a receiving apparatus, a receiving method thereof, and a control program that can be used without being converted.

  In order to solve the above-described problem, a receiving apparatus according to the present invention includes two receiving apparatuses, an LMMSE (Linear Minimum Square Error) receiving apparatus and a RAKE receiving apparatus, and switches to one of the two receiving apparatuses. A receiving device including control means for performing reception, wherein the control means is configured to determine whether the received multipath is within the time window range of the LMMSE receiving device; And calculating means for calculating a total power of a plurality of paths in each time window by setting a plurality of different time windows having a time range equal to the time window range of the LMMSE receiver in the absence of each other. And switching between the LMMSE receiver and the RAKE receiver based on the calculation result in the calculation means Characterized in that it comprises a switching means that.

  The receiving method according to the present invention includes two receiving apparatuses, an LMMSE (Linear Minimum Square Error) receiving apparatus and a RAKE receiving apparatus, and performs a control step of switching to one of the two receiving apparatuses and performing reception. The receiving method includes a determination step for determining whether or not the received multipath is within the time window range of the LMMSE receiving device, and when the received multipath is not within the time window range. Calculating a total power of a plurality of paths in each time window by setting a plurality of different time windows having a time range equal to the time window range of the LMMSE receiver, and calculating the total power of a plurality of paths in each time window; Based on the calculation result in the step, the LMMSE receiver and the RAKE receiver Characterized in that it comprises a switching step of switching to or deviation.

  In addition, a control program according to the present invention includes two receiving apparatuses, an LMMSE (Linear Minimum Square Error) receiving apparatus and a RAKE receiving apparatus, and a receiving method for performing reception by switching to one of the two receiving apparatuses. A control program for executing a determination step for determining whether or not the received multipath is within the time window range of the LMMSE receiver; and A calculation step of setting a plurality of different time windows having a time range equal to the time window range of the LMMSE reception device by shifting them on the time axis, and calculating a total power of a plurality of paths in each time window; Between the LMMSE receiver and the RAKE receiver based on the calculation result in Characterized in that to execute a switching step of switching to or deviation.

  According to the present invention, by including the above-described configuration, it is possible to cope with a path exceeding the delay time range of the LMMSE receiver without complicating and increasing the size of the circuit, and a receiving method thereof, A control program is obtained.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following embodiments, a CE (time domain equalizer) LMMSE receiver will be described. However, other LMMSE receivers, for example, a frequency domain equalizer (FLM equivalent receiver) LMMSE receiver In addition, the present invention can be applied.

  FIG. 1 is a configuration diagram of an example of a receiving apparatus according to the present invention. The receiver shown in the figure operates as a CE LMMSE receiver (hereinafter referred to as a CE receiver) in some cases and as a RAKE receiver in other cases.

  Referring to FIG. 1, an example of a receiving apparatus according to the present invention includes a multipath despreading unit 1, a weighting calculation unit 2, a FIR (Finite Impulse Response) filter 3, a multicode despreading unit 4, and a TX ( A transmission) diversity processor 5, an input sampling buffer (hereinafter referred to as “buffer”) 6, a DSP (Digital Signal Processor) controller 7, and a memory 8.

  The input signal 11 is input to the TX diversity processor 5 via the multipath despreading unit 1, the weighting calculation unit 2, the FIR filter 3, and the multicode despreading unit 4, and the TX diversity processor 5 performs predetermined processing. Thereafter, the output signal 12 is output.

  On the other hand, the input signal 11 is also output to the FIR filter 3 via the buffer 6.

  The DSP controller 7 is connected to the control interface 13 and controls the multipath despreading unit 1, the weight calculation unit 2, the FIR filter 3, the multicode despreading unit 4, the TX diversity processor 5 and the buffer 6.

  The memory 8 stores a control program for a receiving method, which will be described later, and the DSP controller 7 reads the control program from the memory 8 and controls the above-described units based on the control program.

  The input signal 11 is usually a 4 × chip rate I / Q sample. The output signal 12 is a data symbol of a different physical channel used for further processing. The control interface 13 supplies path timing and other control information to the DSP controller 7.

  Next, an example of the operation of this receiving apparatus as a CE receiving apparatus will be described below.

The multipath despreading unit 1 receives the input signal 11 and despreads the pilot signal at different path timings. The despread signal can be used for channel estimation of each path.
The weighting calculation unit 2 performs calculation of a channel estimation weight vector (channel estimation weight vector calculation).

  The FIR filter 3 performs the same process as a known FIR filter.

  The buffer 6 buffers information necessary for calculating the delay in the weighting calculation process.

  The multicode despreading unit 4 despreads a plurality of data channels.

  The TX diversity processor 5 performs a predetermined process when TX diversity is used. When TX diversity is not used, the input signal is output as it is.

  Next, an example of the operation of this receiving apparatus as a RAKE receiving apparatus will be described below.

  The multipath despreading unit 1 receives the input signal 11 and despreads the pilot signal at different path timings. The despread signal can be used for channel estimation of each path.

  The weight calculation unit 2 performs channel evaluation and calculation of a shape weight vector. Here, the shape weight vector is expressed by the following equation (1).

Here, h ₁ , h ₂ ,. . . . , H _L represent the complex channel estimates of the first to Lth paths.

    The FIR filter 3 performs a calculation represented by the following equation (3) in order to generate a chip represented by the following equation (2).

  Here, r (m) in the equation (3) is expressed by the following equation (4).

  Since r (m) is a vector of received samples, chip r (m) corresponds to the timing of the first path.

  The buffer 6 buffers information necessary for calculating the delay in the weighting calculation process.

  The multicode despreading unit 4 despreads a plurality of data channels.

  The TX diversity processor 5 performs a predetermined process when TX diversity is used. When TX diversity is not used, the input signal is output as it is.

  Therefore, switching between the CE receiving device and the RAKE receiving device basically switches the weighting calculation mode of the weighting calculation unit 2.

  The DSP controller 7 controls switching between the CE receiver and the RAKE receiver according to the flowchart shown below.

  FIG. 2 is a flowchart showing an example of the receiving method of the receiving apparatus according to the present invention. The DSP controller 7 controls the following processing steps.

  Referring to the figure, first, a path timing (delay profile) is input to the DSP controller 7 every N frames from an external device (not shown) (step S1).

  The DSP controller 7 evaluates the path strength and the path shape (geometry) based on the pilot SNR by using the signal input from the multipath despreading unit 1 (the pilot signal after despreading) and other available signals ( Step S2).

  The DSP controller 7 checks whether or not the delay profile (the time range in which the path exists) is within a time window (effective window) that can be handled by the CE receiver (step S3).

  If the delay profile is not within the time window (“Yes” in step S3), the process proceeds to step S4. If the delay profile is within the time (“No” in step S3). In the case of (), the process proceeds to step S6.

  In step S4, a CE time window is set for each path in order from the first path (see FIG. 3 described later). Then, the total power of all valid paths is calculated for each time window, and the time window having the maximum total power for CE is selected.

As an example, it is assumed that there are six paths and three valid subgroups (w1 to w3) are set for these paths.

  FIG. 3 is a schematic diagram illustrating an example of the relationship between a plurality of paths and a plurality of subgroups. Referring to the figure, the vertical arrows indicate the first path p1 to the sixth path p6 and their reception levels as an example, and the horizontal arrows indicate the first subgroup w1 to the third subgroup w3 and their time as an example. The range is shown.

  The first subgroup w1 includes four paths of the first path p1 to the fourth path p4. The second subgroup w2 includes four paths, the second path p2 to the fifth path p5. The third subgroup w3 includes four paths from the third path p3 to the sixth path p6.

  Each time window w1-w3 has the same maximum length (time range) as the CE time window.

  In other words, the time range from the first path p1 to the sixth path p6 in FIG. 3 exceeds the range of the CE time window, and all these paths cannot be handled by the conventional CE receiver.

  On the other hand, in the present invention, three time windows having a time range that can be handled by the CE receiving device are provided as an example (w1 to w3), and all the paths are shifted by gradually shifting the time range that they handle. It is possible to handle p1 to p6.

  In step S5, the total power ZdB of the selected time window is compared with the total power of all paths (step S5). If the total power ZdB of the selected time window is less than the total power of all paths ( If “No” in step S5, the RAKE receiver is used (step S8). On the other hand, if the total power ZdB of the selected time window is greater than or equal to the total power of all paths (“Yes” in step S5), the process proceeds to step S7.

  In step S6, it is checked whether or not there is only one path. If only one path exists (“Yes” in step S6), the RAKE receiver is used (step S8). On the other hand, if there are two or more paths ("No" in step S6), the process proceeds to step S7.

  In step S7, it is checked whether or not the pilot SNR is less than X dB. If the pilot SNR is less than X dB (if the path shape is small) (“Yes” in step S7), the RAKE receiver is used ( Step S8). On the other hand, if the pilot SNR is greater than or equal to X dB (if the path shape is large) (“No” in step S7), the CE receiver is used (step S9).

  Next, a control program for the receiving method according to the present invention will be described. A memory 8 shown in FIG. 1 stores a control program for causing a computer (DSP controller 7) to execute the processing steps shown in the flowchart of FIG.

  The DSP controller 7 reads the control program from the memory 8 and executes switching between the RAKE receiving device and the CE receiving device according to the control program. Since the processing contents have already been described, the description thereof is omitted here.

  As described above, according to the present invention, reception using both an LMMSE type chip level equalizer (CE) receiver and a RAKE receiver in various transmission (Tx) and reception (Rx) diversity modes. An apparatus can be provided.

  Further, according to the present invention, it is possible to switch between the optimal CE receiver and the RAKE receiver according to different factors such as the reception channel SNR, the characteristics of the multipath fading channel, and the reception capability. .

It is a block diagram of an example of the receiver which concerns on this invention. It is a flowchart which shows an example of the receiving method of the receiver which concerns on this invention. It is a schematic diagram which shows an example of the relationship between a some path | pass and a some subgroup.

Explanation of symbols

1 Multipath Despreading Unit 2 Weighting Calculation Unit 3 FIR Filter 4 Multicode Despreading Unit 5 TX Diversity Processor 6 Input Sampling Buffer 7 DSP Controller 8 Memory

Claims (15)

An LMMSE (Linear Minimum Square Error) receiving apparatus and a RAKE receiving apparatus are provided with two receiving apparatuses, and includes a control means for switching to one of the two receiving apparatuses and performing reception.
The control means determines whether the received multipath is within the time window range of the LMMSE receiver; and
When not in the time window range, a plurality of different time windows having a time range equal to the time window range of the LMMSE receiver is set to be shifted on the time axis, and the sum of a plurality of paths in each time window is set. A calculation means for calculating electric power;
A receiving apparatus comprising switching means for switching between the LMMSE receiving apparatus and the RAKE receiving apparatus based on a calculation result in the calculating means. The calculating means includes means for selecting a time window with the largest total power;
The switching means compares the total power of the selected time window with the total power of all paths, and if the total power of the selected time window is less than or equal to the total power of all paths, the RAKE receiver The receiving device according to claim 1, wherein the receiving device is switched to The calculating means includes means for selecting a time window with the largest total power;
The switching means compares the total power of the selected time window with the total power of all paths, and if the total power of the selected time window exceeds the total power of all paths, a pilot SNR and a predetermined power 3. The receiving apparatus according to claim 1, wherein the receiving apparatus compares with a threshold value, and switches to the RAKE receiving apparatus when the pilot SNR is less than the predetermined threshold, and switches to the CE receiving apparatus when the pilot SNR is equal to or greater than the predetermined threshold. . The control means checks whether or not there is only one path when the received multipath is within the time window range, and switches to the RAKE receiving apparatus if there is only one path. The receiving device according to 1. The control means checks whether there is only one path when the received multipath is within the time window range. If there are two or more paths, the control means compares the pilot SNR with a predetermined threshold, and the pilot SNR is 5. The receiving apparatus according to claim 1 or 4, wherein when it is less than a predetermined threshold, it switches to the RAKE receiving apparatus, and when the pilot SNR is equal to or greater than a predetermined threshold, it switches to the CE receiving apparatus. A receiving method in a receiving apparatus including two receiving apparatuses, an LMMSE (Linear Minimum Square Error) receiving apparatus and a RAKE receiving apparatus, and including a control step of switching to one of the two receiving apparatuses and performing reception. ,
The control step determines whether the received multipath is within a time window range of the LMMSE receiver; and
When not in the time window range, a plurality of different time windows having a time range equal to the time window range of the LMMSE receiver is set to be shifted on the time axis, and the sum of a plurality of paths in each time window is set. A calculation step for calculating power;
A receiving method comprising: a switching step of switching between the LMMSE receiving apparatus and the RAKE receiving apparatus based on a calculation result in the calculating step. The calculating step includes selecting a time window with the largest total power;
The switching step compares the total power of the selected time window with the total power of all paths, and if the total power of the selected time window is less than or equal to the total power of all paths, the RAKE receiver 7. The receiving method according to claim 6, wherein the receiving method is switched to. The calculating step includes selecting a time window with the largest total power;
The switching step compares the total power of the selected time window with the total power of all paths, and if the total power of the selected time window exceeds the total power of all paths, a pilot SNR and a predetermined power 8. The reception method according to claim 6, wherein a comparison is made with a threshold value, and when the pilot SNR is less than a predetermined threshold value, switching to the RAKE receiving apparatus is performed, and when the pilot SNR is equal to or greater than a predetermined threshold value, switching to the CE receiving apparatus is performed . The control step checks whether only one path exists when the received multipath is within the time window range, and switches to the RAKE receiving apparatus if only one path exists. 6. The receiving method according to 6. The control step checks whether there is only one path when the received multipath is within the time window range, and if there are two or more paths, compares the pilot SNR with a predetermined threshold, and the pilot SNR is The reception method according to claim 6 or 9, characterized in that when it is less than a predetermined threshold, it switches to the RAKE receiver, and when the pilot SNR is equal to or greater than a predetermined threshold, it switches to the CE receiver . A control program for executing a reception method that includes two reception devices, an LMMSE (Linear Minimum Square Error) reception device and a RAKE reception device, and performs reception by switching to one of the two reception devices. ,
A determination step of determining whether or not the received multipath is within a time window range of the LMMSE receiver;
When not in the time window range, a plurality of different time windows having a time range equal to the time window range of the LMMSE receiver is set to be shifted on the time axis, and the sum of a plurality of paths in each time window is set. A calculation step for calculating power;
A control program for executing a switching step of switching to either the LMMSE receiver or the RAKE receiver based on a calculation result in the calculation step. The calculating step includes selecting a time window with the largest total power;
The switching step compares the total power of the selected time window with the total power of all paths, and if the total power of the selected time window is less than or equal to the total power of all paths, the RAKE receiver The control program according to claim 11, wherein the control program is switched to. The calculating step includes selecting a time window with the largest total power;
The switching step compares the total power of the selected time window with the total power of all paths, and if the total power of the selected time window exceeds the total power of all paths, a pilot SNR and a predetermined power 13. The control program according to claim 11, wherein the control program compares with a threshold value and switches to the RAKE receiver when the pilot SNR is less than a predetermined threshold, and switches to the CE receiver when the pilot SNR is equal to or greater than the predetermined threshold. . The control step checks whether only one path exists when the received multipath is within the time window range, and switches to the RAKE receiving apparatus if only one path exists. 11. The control program according to 11. The control step checks whether there is only one path when the received multipath is within the time window range, and if there are two or more paths, compares the pilot SNR with a predetermined threshold, and the pilot SNR is The control program according to claim 11 or 14, characterized in that when it is less than a predetermined threshold, it switches to the RAKE receiver, and when the pilot SNR is greater than or equal to a predetermined threshold, it switches to the CE receiver .

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