JP2011082696A - Device, method and program for estimating interference power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To estimate interference power with high accuracy in random access transmission of a radio communication system. <P>SOLUTION: An interference power estimation part 104 uses a sample signal of the outside X'(n) of a search window which is not yet detected by a user and a sample signal extracted from the inside of the search window X(n) which is not yet detected by the user to estimate the interference power σ<SP>2</SP>based on user detection information to be notified from a user detection part 105 outside the search window and a user detection part 106 in the search window. Then, procedures of interruption power estimation processing from user detection processing in the user detection part 105 outside the search window and the user detection part 106 in the search window to estimation processing of the interference power σ<SP>2</SP>in the interference power estimation part 104 are repeated for predetermined arbitrary frequencies. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radio communication system including a transmitter and a receiver, and more particularly to an interference power estimation apparatus, an interference power estimation method, and interference capable of performing interference power estimation with high accuracy in a radio system performing random access transmission. The present invention relates to a power estimation program.

  Below, the interference power estimation process in the radio | wireless communications system (for example, W-CDMA (Wideband Code Division Multiple Access)) which performs random access transmission is demonstrated. FIG. 8 is a diagram illustrating a configuration of an interference power estimation apparatus in a radio communication system using a random access transmission method, and more precisely, a diagram illustrating a configuration part of the interference power estimation apparatus provided in the receiver of the radio communication system. It is.

  Although FIG. 8 shows an example in which one transmitter 210 and one receiver 201 exist as an example, a plurality of transmitters 210 actually exist.

  The transmitter 210 transmits random access data to the receiver 201 on the time axis. The receiver 201 includes a delay profile generation unit 202, a memory unit 203, a search window interference power estimation unit 204, and an interference power estimation result unit 205.

  Random access data is input from the transmitter 210 to the delay profile generation unit 202. The delay profile generation unit 202 generates a delay profile from the input random access data, and outputs the generated delay profile to the memory unit 203. The memory unit 203 receives the delay profile from the delay profile generation unit 202, holds the input delay profile, and outputs it to the search window interference power estimation unit 204.

The search window outside interference power estimation unit 204 receives the delay profile from the memory unit 203. The search window interference power estimation unit 204 calculates the interference power σ ² using the sample outside the search window from the input delay profile, and outputs the calculated interference power σ ² to the interference power estimation result unit 205. The interference power estimation result unit 205 receives the interference power σ ² from the search window interference power estimation unit 204 and stores the input interference power σ ² .

  There is a related random access signal receiving device (see Patent Document 1). In the random access signal receiving apparatus in a mobile communication system to which W-CDMA (Wideband Code Division Multiple Access) is applied, not only the message delay profile but also the preamble information is detected. (Path phase, path correlation value, noise power, delay profile) is also used to improve the detection accuracy of the message path phase and improve the reception performance. However, the random access signal receiver of Patent Document 1 performs interference power estimation using the sample signal outside the search window in the delay profile and the sample signal extracted from the search window as in the present invention, and the interference The power estimation procedure is not repeated a predetermined number of times.

  There is also a related random access wireless communication system (see Patent Document 2). The wireless communication system of Patent Document 2 aims to improve the certainty of establishing a wireless link in a random access wireless communication system. For this purpose, the mobile station changes the transmission condition based on the reception state of the downlink physical channel signal indicating rejection of the received request, and retransmits the uplink physical channel signal. However, the wireless communication system of Patent Document 2 performs interference power estimation using a sample signal outside the search window in the delay profile and a sample signal extracted from the search window as in the present invention, and the interference power The estimation procedure is not repeated a predetermined number of times.

  There is also a related interference power estimation device (see Patent Document 3). This interference power estimation apparatus is intended to provide an interference power estimation apparatus that performs highly accurate interference power estimation. For this purpose, the interference power of the received signal is estimated by powering the difference between the pilot symbol and the reference symbol in the target slot. However, the interference power estimation apparatus of Patent Document 3 performs interference power estimation on the sample signal outside the search window in the delay profile, the sample signal extracted from the search window, and the interference power as in the present invention. The estimation procedure is not repeated a predetermined number of times.

  There are also related CDMA receiver pilot strength measurements and multipath delay searchers (see Patent Document 4). The technique of Patent Document 4 relates to measurement of signal strength in a pilot channel in a cellular communication system using spread spectrum modulation. As in the present invention, a sample signal outside a search window in a delay profile, and a search window The interference power estimation is performed based on the sample signal extracted from the inside, and the interference power estimation procedure is not repeated a predetermined number of times.

JP 2003-218740 A JP 2007-134946 A JP 2008-141313 A Japanese translation of PCT publication No. 2002-518873

  In the interference power estimation unit 204 outside the search window in the interference power estimation apparatus (receiver 201) shown in FIG. 8, as shown in FIG. 6, X '(n) outside the search window (n is an integer, window number). Interference power estimation is performed using only samples.

  FIG. 9 is a diagram for explaining problems in the interference power estimation process. FIG. 9 shows how the width of the search window changes depending on the propagation delay amount. The width of the search window X1 (n) when the propagation delay in FIG. 9B is large needs to be larger than the width of the search window X0 (n) when the propagation delay in FIG. 9A is small. . For this reason, the width of the search window increases in proportion to the propagation delay, and the number of samples outside the search window used for interference power estimation decreases. As a result, when the propagation delay is large, the number of samples used for interference power estimation is reduced and the averaging effect is reduced, so that the interference power estimation accuracy is deteriorated.

  In addition, the side lobe of the peak signal in the adjacent search window leaks to the sample outside the search window, and the peak signal of the asynchronous user exists outside the search window. There is also a problem that is estimated.

  A main problem of the present invention is to estimate interference power with high accuracy in random access transmission of a wireless communication system.

  In the interference power estimation apparatus according to the present invention, a delay profile having a predetermined period generated by a random access signal transmitted from a transmitter in a wireless communication system is divided into a plurality of search windows and areas outside the search window on the time domain. The interference power is estimated based on the sample signal outside the search window and the sample signal extracted from the search window.

In the interference power estimation apparatus of the present invention, interference power is estimated using a sample signal outside the search window X ′ (n) that has not been detected by the user and a large number of sample signals extracted from within the search window X (n).
Thereby, interference power can be estimated with high accuracy using a large number of sample signals in the search window X (n) and the search window outside X ′ (n) that have not been detected by the user.

It is a figure which shows the basic composition of the interference electric power estimation apparatus of this invention. It is a figure which shows the structure of the interference electric power estimation apparatus concerning embodiment of this invention. 3 is a flowchart for explaining the operation of the interference power estimation apparatus shown in FIG. It is a flowchart which shows the flow of the interference power estimation process in a search window & search window outside interference power estimation part. It is a figure which shows an example of a delay profile (demodulation signal) in case a user exists. It is a figure for demonstrating the interference power estimation method in the search window interference power estimation part. It is a figure which shows the extraction method of the sample signal from the user undetected search window X (n). It is a figure which shows the general structure of an interference electric power estimation apparatus. It is a figure for demonstrating the problem in the interference electric power estimation apparatus shown in FIG.

  An object of the present invention is to provide an interference power estimation apparatus capable of improving interference power estimation accuracy in random access transmission of a wireless communication system. Embodiments of the present invention will be described below with reference to the drawings.

[Overview]
FIG. 1 is a diagram illustrating a basic configuration of an interference power estimation apparatus according to the present invention. More precisely, FIG. 1 is a diagram illustrating components of the interference power estimation apparatus in the receiver 100 of the wireless communication system. Note that the specific configuration and detailed operation of the interference power estimation apparatus of the present invention will be described in the description of the interference power estimation apparatus shown in FIG. 2, so here, the outline of the interference power estimation apparatus of the present invention will be described. Just explain.

  In FIG. 1, a transmitter 210 transmits random access data to the receiver 100 on a time axis. The receiver 100 includes a control unit 101, a delay profile generation unit 102, a search window setting unit 103, a search window user detection unit 105, and a search window user detection unit 106.

  The control unit 101 is a control unit including a CPU (Central Processing Unit) and the like, and is a control unit that controls the operation of each processing unit in the receiver 100 in an integrated manner. The delay profile generation unit 102 receives random access data from the transmitter 210. The delay profile generation unit 102 generates a delay profile Prof on the time axis from the input random access data. The delay profile prof generated by the delay profile generation unit 102 is output to the search window setting unit 103, the interference power estimation unit 104, the search window user detection unit 105, and the search window user detection unit 106.

  The search window setting unit 103 sets a plurality of search windows X (n) (see FIG. 6) in the time domain for the delay profile Prof based on the input delay profile Prof, and searches for the delay profile Prof. A distinction is made between the window X (n) and the area outside the search window X ′ (n). This search window setting information is output to interference power estimation section 104, search window outside user detection section 105, and search window inside user detection section 106.

  The search window user detection unit 105 detects the user for each search window X ′ (n) based on the delay profile Prof and the setting information of the search window X ′ (n) input from the search window setting unit 103. Calculate information. The search window user detection unit 106 calculates user detection information for each search window X (n) based on the delay profile Prof and the search window setting information input from the search window setting unit 103.

  Further, the interference power estimation unit 104 receives the delay profile Prof, is notified of user detection information for each X ′ (n) outside the search window from the search window user detection unit 105, and is also included in the search window user detection unit 106. The user detection information for each search window X (n) is notified.

  In the above configuration, the interference power estimation unit 104 performs interference power estimation processing based on the delay profile Prof and the user detection information notified from the search window user detection unit 105 and the search window user detection unit 106. .

In this interference power estimation processing, based on the user detection information notified from the search window user detection unit 105 and the search window user detection unit 106, the sample signal of the search window X ′ (n) not detected by the user is detected. Then, the interference power σ ² is estimated using the sample signal extracted from the search window X (n) where the user has not been detected.

In addition, the procedure of the interference power estimation process from the user detection process in the search window user detection unit 105 and the search window user detection unit 106 to the estimation process of the interference power σ ² in the interference power estimation unit 104 is determined in a predetermined arbitrary manner. Repeat for a number of times.

  As described above, in the interference power estimation apparatus of the present invention, the number of samples used for interference power estimation is variable according to the user detection information calculated by the search window user detection unit 105 and the search window user detection unit 106. . In this case, in the interference power estimation process of the interference power estimation unit 104, control is performed so that the number of sample signals used for interference power estimation is maximized according to the number of detected users. Thereby, in the interference power estimation apparatus according to the present invention, the sample signal outside the search window X ′ (n) not detected by the user and the sample signal extracted from the search window X (n) not detected by the user are high. The interference power can be estimated with accuracy.

  In FIG. 1, the interference power estimation apparatus of the present invention corresponds to a component (each processing unit in the receiver 100) of the interference power estimation apparatus provided in the receiver 100. The transmitter corresponds to the transmitter 210. In addition, the search window setting unit 103 corresponds to the search window setting unit of the present invention. The delay profile generation unit of the present invention corresponds to the delay profile generation unit 102, and the interference power estimation unit corresponds to the interference power estimation unit 104. The first user detection unit of the present invention corresponds to the search window user detection unit 105, and the second user detection unit of the present invention corresponds to the search window user detection unit 106.

Then, in the interference power estimation apparatus (receiver 100) shown in FIG. 1, a plurality of delay profiles Prof having a predetermined period generated by a random access signal transmitted from the transmitter 210 in the wireless communication system are displayed on the time domain. The search window X (n) and the outside of the search window X ′ (n) are distinguished from each other, and based on the sample signal outside the search window X ′ (n) and the sample signal extracted from within the search window X (n). Next, the interference power is estimated.
Thereby, interference with high accuracy is achieved by a large number of sample signals using the sample signal outside the search window X ′ (n) not detected by the user and the sample signal extracted from the search window X (n) not detected by the user. Power estimation can be performed.

In the interference power estimation apparatus, in the receiver 100, the delay profile generation unit 102 generates a delay profile Prof on the time axis based on the random access signal transmitted from the transmitter 210. The search window setting unit 103 distinguishes the delay profile Prof into a plurality of search window X (n) and outside search window X ′ (n) areas in the time domain. The search window user detection unit 105 calculates user detection information for each search window X ′ (n) based on the delay profile Prof. The search window user detection unit 106 calculates user detection information for each search window X (n) based on the delay profile Prof. The interference power estimation unit 104, based on the user detection information calculated by the search window user detection unit 105 and the search window user detection unit 106, a sample signal of the search window X ′ (n) that has not been detected by the user, Interference power estimation processing is performed based on the sample signal extracted from the search window X (n) not detected by the user based on a predetermined reference. Then, the process for estimating the interference power is repeatedly performed for a predetermined number of times, and in the first interference power estimation process, the process for calculating the interference power is performed by using the sample signal outside the search window X ′ (n), and continues. In the second and subsequent interference power estimation processes, based on the user detection information calculated by the search window user detection unit 105 and the search window user detection unit 106, the user's undetected search window X ′ (n). A process for calculating interference power is performed by using the sample signal and the sample signal extracted from the search window X (n) that has not been detected by the user.
Thereby, interference with high accuracy is achieved by a large number of sample signals using the sample signal outside the search window X ′ (n) not detected by the user and the sample signal extracted from the search window X (n) not detected by the user. Power estimation can be performed.

[Description of Configuration of Interference Power Estimation Device of the Present Invention]
FIG. 2 is a diagram illustrating a configuration of the interference power estimation apparatus according to the embodiment of the present invention, and more precisely, a diagram illustrating a configuration part of the interference power estimation apparatus provided in the receiver 100. In the example shown in FIG. 2, one transmitter 210 and one receiver 100 are shown, but there are actually a plurality of transmitters 210.

  The transmitter 210 transmits random access data to the receiver 100 on the time axis. The receiver 100 includes a control unit 101, a delay profile generation unit 102, a search window setting unit 103, a search window user detection unit 105, a search window user detection unit 106, a search window interference power estimation unit 107, a search window & It includes a search window interference power estimation unit 108, a threshold calculation unit 109, a memory unit 110, an interference power estimation result unit 111, and a user detection information storage unit 112.

  The delay profile generation unit 102 receives random access data from the transmitter 210. The delay profile generation unit 102 generates a delay profile Prof on the time axis from the input random access data. The generated delay profile Prof is output to the memory unit 110.

  The memory unit 110 receives the delay profile Prof from the delay profile generation unit 102. The input delay profile Prof is held over a period during which interference power estimation processing is performed. The held delay profile Prof includes search window setting section 103, search window user detection section 105, search window user detection section 106, search window interference power estimation section 107, and search window & search window interference power estimation. Is output to the unit 108.

  The search window setting unit 103 sets a plurality of search windows X (n) in the time domain for the delay profile Prof based on the input delay profile Prof, and sets the delay profile Prof as the search window X (n). A distinction is made into regions outside the search window 'X (n) (see FIG. 6). The search window setting information is output to the search window user detection unit 105, the search window user detection unit 106, the search window interference power estimation unit 107, and the search window & search window interference power estimation unit 108. .

The search window outside interference power estimation unit 107 receives the delay profile Prof from the memory unit 110. The search window interference power estimation unit 107 calculates the interference power σ ² using the sample signal outside the search window X ′ (n) in the input delay profile Prof. The calculated interference power σ ² is output to the threshold value calculation unit 109.

The threshold calculation unit 109 receives the interference power σ ² from the search window interference power estimation unit 107 or the search window & search window interference power estimation unit 108. The threshold calculation unit 109 calculates a path detection threshold THRdet used for user detection from the input interference power σ ² . The calculated path detection threshold THRdet is output to the search window user detection unit 105 and the search window user detection unit 106.

  The search window user detection unit 105 receives the delay profile Prof from the memory unit 110 and the path detection threshold THRdet from the threshold calculation unit 109. This path detection threshold value THRdet is corrected by the search window user detection unit 105, and the search window path detection threshold value THR'det is calculated. The search window user detection unit 105 performs user detection for each search window X ′ (n) using the search window path detection threshold THR′det and the delay profile Prof, and for each search window X ′ (n). The user detection information at the time is calculated. The calculated user detection information at the corresponding time for each X ′ (n) outside the search window is notified to the intra-search window & outside search window interference power estimation unit 108 and is also stored in the user detection information storage unit 112.

  The search window user detection unit 106 receives the delay profile Prof from the memory unit 110 and the path detection threshold THRdet from the threshold calculation unit 109. The search window user detection unit 106 performs user detection for each search window X (n) using the delay profile Prof and the path detection threshold value THRdet, and calculates user detection information at that time for each search window X (n). . The calculated user detection information at the corresponding time for each search window X (n) is notified to the intra-search window & outside search window interference power estimation unit 108 and is also stored in the user detection information storage unit 112.

In the search window & outside search window interference power estimation unit 108, the delay profile Prof is input from the memory unit 110, and the search window setting information is input from the search window setting unit 103. Also, the search window user detection unit 105 is notified of the user detection information at the corresponding time for each X ′ (n) outside the search window from the search window user detection unit 105 to the search window & search window interference power estimation unit 108. The unit 106 is notified of the user detection information at that time for each search window X (n). The interference power estimation unit 108 in the search window & outside the search window calculates the interference power σ ² from the input delay profile Prof and the user detection information of the notified time. The calculated interference power σ ² is output to the threshold calculation unit 109 and the interference power estimation result unit 111.

  The search window sample extraction unit 108A in the search window & search window interference power estimation unit 108 is a processing unit for extracting a sample signal from the search window X (n) that has not been detected by the user. The operation will be described later.

The interference power estimation result unit 111 receives the interference power σ ² from the search window & search window interference power estimation unit 108. The interference power estimation result unit 111 stores the input interference power σ ² .

  In the above configuration, in the first interference power estimation process described later, the search window interference power estimation unit 107 uses only the sample signal outside the search window.

In the second and subsequent interference power estimation processing, the interference power estimation unit 108 within the search window & outside the search window is selected by referring to the user detection information at the time notified from the user detection unit 105 outside the search window. User undetected search window X (n) selected with reference to the sample signal outside the search window X ′ (n) where the user has not been detected and the user detection information at the time notified from the user detection unit 106 within the search window. The interference power σ ² is estimated using the sample signal extracted from (1).

Subsequently, a path detection threshold THRdet is calculated by the threshold calculation unit 109 based on the interference power σ ² calculated by the in-search window & outside search window interference power estimation unit 108, and the search window user detection unit 105 and the search window user The detection unit 106 performs user detection. Thereafter, the interference power estimation process from the estimation process of the interference power σ ² in the search window & search window interference power estimation unit 108 to the user detection process in the search window user detection unit 105 and the search window user detection unit 106 will be described. The procedure is repeated for any given number of times.

[Description of Operation of Interference Power Estimation Device shown in FIG. 2]
In the following description, processing of the receiver 100 in random access transmission when there is one transmitter 210 and one receiver 100 as an example will be described.

  FIG. 3 is a flowchart showing the operation of interference power estimation processing in the present invention. FIG. 4 is a flowchart showing the flow of interference power estimation processing in the interference power estimation unit 108 in the search window & outside the search window. FIG. 5 is an example of a delay profile (demodulated signal) when the user is detected. FIG. 6 shows an interference power estimation method in the search window outside interference power estimation unit 107. FIG. 7 is a diagram illustrating a method of extracting a sample signal from the search window X (n) where the user has not been detected in the search window sample extraction unit 108A.

Hereinafter, the random access data reception process (interference power estimation process) in the receiver 100 will be described with reference to FIGS.
First, the memory unit 110 holds the delay profile generated by the delay profile generation unit 102 (step S100). Then, it is determined whether or not it is the first time. If it is the first time (step S101: Yes), the interference power σ ² estimation process is performed by the search window interference power estimation unit 107 (step S102).

Here, as shown in FIG. 5, the delay profile when the user exists (when the user is detected) is a waveform having a peak in the time domain. In the search window interference power estimation unit 107, as shown in FIG. 6, there are N delay profiles (N is an integer and the number of search windows) search windows X (n) and search window outside X ′ (n). Distinguish. Here, when a user is detected, a peak appears in the search window X (n). Therefore, since the search window X (n) is used for user detection, the sample of the search window X (n) is not used for interference power estimation. The interference power σ ² is calculated by performing addition processing and further averaging processing on the sample signal outside the search window X ′ (n) (step S102).

In the case of interference power estimation in the first iteration, the threshold calculation unit 109 uses the interference power σ ² input from the search window interference power estimation unit 107 (steps S101, S102, and S103). On the other hand, in the case of interference power estimation in the second and subsequent iterations, the interference power σ ² input from the intra-search window & out-search window interference power estimation unit 108 is used (steps S101, S109, S110). The path detection threshold THRdet is calculated from the equation (1) using the input interference power σ ² (step S103).

THRdet = THRrelative × σ ² (1)
Here, THRrelative indicates a relative path detection threshold for interference power that can be arbitrarily set as a parameter.

The search window user detection unit 106 compares the delay profile with the path detection threshold THRdet for each search window X (n) (step S104).
If the delay profile is equal to or greater than the path detection threshold THRdet in the search window X (n) (step S104: Yes), it is determined that the user is detected in the search window X (n) (step S105-1). Here, the user detection information at the time up to the current repetition time is stored in the user detection information storage unit 112, and the information detected by the user in the search window X (n) obtained this time and the sample exceeding the threshold The number Z (n) is additionally recorded in the user detection information at the time.

  If the delay profile is less than the path detection threshold THRdet (step S104: No), it is determined that no user is detected in the search window X (n) (step S105-2). Here, the user detection information at the time up to the current repetition time is stored in the user detection information storage unit 112, and information that has not been detected in the search window X (n) obtained this time is stored as the user at the time. Add additional records to the detection information.

  On the other hand, the search window outside user detection unit 105 calculates the search window outside path detection threshold THR′det from the equation (2) using the input path detection threshold THRdet (step S106).

THR'det = THRdet × α (2)
Here, α represents a search window path detection threshold value correction coefficient for the path detection threshold value THRdet whose value can be arbitrarily set as a parameter.

  The search window user detection unit 105 compares the delay profile with the search window path detection threshold THR′det for each search window X ′ (n) (step S107). If the delay profile is greater than or equal to the search window path detection threshold THR′det in the search window outside X ′ (n) (step S107: Yes), it is determined that the user is detected outside the search window X ′ (n) (step S107). S108-1). On the other hand, when the delay profile is less than the search window path detection threshold value THR′det (step S107: No), it is determined that no user is detected in the search window outside X ′ (n) (step S108-2).

  Here, FIG. 4 shows the flow of the interference power estimation process (step S109) performed in the search window & search window interference power estimation unit 108. As shown in the flowchart of FIG. 4, for the search window outside X ′ (n), reference is made to the user detection information at that time for each of the search window outside X ′ (n) at the current repetition time (step S200).

Then, the interference power σ _{0, n} ² is calculated for each X ′ (n) outside the search window by adding only N ′ samples outside the search window X ′ (n) that have not been detected by the user (step S201). . Subsequently, the interference power σ ₀ ^{2 of} all the search windows X ′ (n) is calculated by the equation (3) (step S202).

  On the other hand, for the search window X (n), first, a user undetected search window X (n) is selected with reference to the user detection information at that time for each search window X (n) at the current repetition time. (Step S203).

  Further, as shown in FIG. 7, the user detection information at the corresponding time for each search window X (n) in the past repetition is referred to (step S204), and it is determined whether or not the information detected by the user is recorded. (Step S205).

  When user detection information is recorded (step S205: Yes), Y (n) sample signals around the sample signal (number Z (n)) exceeding the threshold value are not used for interference power estimation. (Step S206). Here, the number of samples Y (n) around the sample signal (number Z (n)) not used for interference power estimation can be given an arbitrary value for each search window X (n) as a parameter.

Further, regarding user detection information at the corresponding time for each search window X (n) in the past iteration, Y ′ (n) obtained by weighting Y (n) according to the number of iterations when the user is detected in the past is represented by Y It can also be used instead of (n). As an example, assuming that the current iteration is the M _0th iteration and the user is detected in the M _1st iteration, Y ′ (n) is calculated according to Equation (4).

Y ′ (n) = Y (n) × W (m) (m = M ₀ −M ₁ , M ₀ ≧ M ₁ ) (4)

  Here, in Expression (4), W (m) is a weighting coefficient obtained by referring to the weighting coefficient table, and m is an index for referring to the weighting coefficient table. Furthermore, it is possible to set an arbitrary value as a parameter for the weighting coefficient table.

Then, in the N search windows X (n) not detected by the user at the current repetition time, the interference power σ for each search window X (n) is added by adding to the samples selected as described above. _1, ^{n 2} calculates the (step S207). Next, the interference power σ ₁ ^{2 of} all search windows X (n) is calculated from the equation (5) (step S208).

Returning to the flowchart of FIG. 3, the interference power sigma ₁ ² interference power sigma ₀ ² and the search window X of search window outside X'(n) (n), the interference power sigma ² is calculated from Equation (6) ( Step S109).

σ ² = (σ ₀ ² + σ ₁ ² ) / Ntotal (6)
Here, Ntotal indicates the total number of samples added in X (n) within the search window and X ′ (n) outside the search window.

The interference power estimation result unit 111 determines whether to continue or end the interference power estimation process with reference to the repetition number of interference power estimation (step S110). Here, the number of repetitions of interference power estimation can be set to an arbitrary number as a parameter. When the interference power estimation process is continued, the interference power σ ² is output to the threshold value calculation unit 109. On the other hand, when the interference power estimation process is terminated, the interference power σ ² is stored as the interference power estimation result.

As described above, the first effect of the present invention is that the averaging effect in the interference power estimation accuracy can be improved.
The reason is that interference power estimation is performed using samples outside and within the search window, and the number of samples in the search window is maximized by repeating interference power estimation and user detection an arbitrary number of times. This is because the number of samples used for interference power estimation is increased and the averaging effect is enhanced as compared with the conventional case where interference power estimation is performed using only samples outside the search window.

The second effect is that it is possible to suppress erroneous estimation with higher accuracy than the actual estimation in the interference power estimation accuracy.
The reason is that the user detection is performed for each outside of the search window even when the peak signal component of the asynchronous user exists outside the search window or when the side lobe component of the peak signal of the search window leaks outside the search window. This is because the frequency of interference power estimation using samples outside the search window is reduced, which reduces the increase in the interference power estimate.

The third effect is that the accuracy of user detection can be improved.
This is because the accuracy of the threshold used for user detection is improved with the improvement of the interference power estimation accuracy, and the accuracy of user detection is also improved.

  Although the embodiment of the present invention has been described above, the interference power estimation apparatus (receiver 100) shown in FIGS. 1 and 2 has a computer system therein.

  A series of processes related to the above-described process is stored in a computer-readable recording medium in the form of a program, and the above-described process is performed by the computer reading and executing this program.

  That is, delay profile generation section 102, search window setting section 103, interference power estimation section 104, search window user detection section 105, search window user detection section 106, search window interference power estimation section 107, search window & search In each of the processes in the out-of-window interference power estimation unit 108 and the threshold value calculation unit 109, a central processing unit such as a CPU reads the above program into a main storage device such as a ROM or RAM, and executes information processing and arithmetic processing. By doing so, it is realized.

  Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  In FIG. 2, the interference power estimation apparatus of the present invention corresponds to a component (each processing unit in the receiver 100) of the interference power estimation apparatus provided in the receiver 100. The transmitter corresponds to the transmitter 210. The delay profile generation unit of the present invention corresponds to the delay profile generation unit 102, and the search window setting unit corresponds to the search window setting unit 103. Further, the first interference power estimation unit of the present invention corresponds to the search window interference power estimation unit 107, and the second interference power estimation unit corresponds to the search window outside search window & search window interference power estimation unit 108. The threshold value calculation unit 109 corresponds to the threshold value calculation unit. The first user detection unit of the present invention corresponds to the search window outside user detection unit 105, and the second user detection unit corresponds to the search window user detection unit 106. The search window sample extraction unit of the present invention corresponds to the search window sample extraction unit 108A, and the path detection threshold corresponds to the path detection threshold THRdet.

In the interference power estimation apparatus (receiver 100) shown in FIG. 2, the search window interference power estimation unit 107 calculates the interference power based on the sample signal outside the search window X ′ (n) in the delay profile Prof. Further, the intra-search window & outside search window interference power estimation unit 108 uses the delay profile Prof and the user detection information detected by the search window user detection unit 105 and the search window user detection unit 106 to determine whether the user The interference power is calculated from the sample signal outside the detection search window X ′ (n) and the sample signal extracted from the search window X (n) not detected by the user. Threshold calculation section 109 calculates path detection threshold THRdet from the interference power calculated by search window interference power estimation section 107 or search window & search window interference power estimation section 108.
Then, the interference power estimation process is repeated a predetermined number of times, and in the first interference power estimation process, the search window interference power estimation unit 107 calculates the interference power from the search window outside X ′ (n) sample signal. Then, the threshold calculation unit 109 calculates the path detection threshold THRdet based on the interference power calculated from the search window interference power estimation unit 107.
In the subsequent interference power estimation processing after the second time, based on the user detection information detected by the search window user detection unit 105 and the search window user detection unit 106 by the search window & search window interference power estimation unit 108. The interference power is calculated from the sample signal outside the search window X ′ (n) not detected by the user and the sample signal extracted from the search window X (n) not detected by the user, and the threshold calculation unit 109 detects the path. The threshold value THRdet is calculated based on the interference power calculated by the interference power estimation unit 108 in the search window & outside the search window.
As a result, interference power estimation is performed using sample signals outside and within the search window, and the number of samples in the search window is maximized by repeating interference power estimation and user detection an arbitrary number of times. Compared to the conventional case where interference power estimation is performed using only sample signals outside the search window, the number of samples used for interference power estimation increases and the averaging effect increases.

In addition, the search window sample extraction unit 108A refers to the user detection information for each search window X (n) in the past repetition, and the user detection information is recorded for the search window X (n) that has not been detected by the user. If there is, a process of excluding a predetermined number of sample signals around the sample signal exceeding a predetermined threshold from the interference power estimation, and the interference power estimation unit 108 within the search window and outside the search window performs the search not detected by the user. In the window X (n), interference signal estimation processing is performed by adding the sample signals selected by the search window sample extraction unit 108A.
Accordingly, it is possible to extract an appropriate sample signal from the search window X (n) that has not been detected by the user and perform interference power estimation.

  Although the embodiment of the present invention has been described above, the interference power estimation apparatus of the present invention is not limited to the illustrated example described above, and various modifications can be made without departing from the scope of the present invention. Of course. The interference power estimation apparatus of the present invention can be used effectively in a base station apparatus or mobile station apparatus in a random access radio communication system, for example, a W-CDMA (Wideband Code Division Multiple Access) radio communication system. Is.

DESCRIPTION OF SYMBOLS 100 ... Receiver, 101 ... Control part, 102 ... Delay profile production | generation part, 103 ... Search window setting part, 104 ... Interference power estimation part, 105 ... Detection outside a search window user 106: search window user detection unit 107: search window interference power estimation unit 108: search window & search window interference power estimation unit 108A: search window sample extraction 109: Threshold calculation unit 110 ... Memory unit 111 ... Interference power estimation result unit 112 ... User detection information storage unit 210 ... Transmitter

Claims (7)

A delay profile of a predetermined period generated by a random access signal transmitted from a transmitter in a wireless communication system is distinguished into a plurality of search windows and areas outside the search window in the time domain, An interference power estimation apparatus that estimates interference power based on a sample signal and a sample signal extracted from the search window. The interference power estimation device comprises:
A delay profile generator for generating a delay profile on the time axis based on a random access signal transmitted from the transmitter;
A search window setting unit for distinguishing the delay profile into a plurality of search windows and areas outside the search window on the time domain;
A first user detection unit that calculates detection information of a user outside the search window by the delay profile;
A second user detection unit that calculates user detection information for each of the search windows according to the delay profile;
Based on the user detection information calculated by the first and second user detection units, based on the sample signal outside the search window not detected by the user and the sample signal extracted from the search window not detected by the user, An interference power estimation unit for performing interference power estimation processing;
With
The interference power estimation process is repeatedly performed a predetermined number of times,
In the first interference power estimation process,
A process of calculating interference power by a sample signal outside the search window is performed,
In the second and subsequent interference power estimation processing,
Based on the user detection information detected by the first and second user detection units, interference is caused by a sample signal outside the user-undetected search window and a sample signal extracted from the user-undetected search window. The interference power estimation apparatus according to claim 1, wherein a process of calculating power is performed. The interference power estimation device comprises:
A first interference power estimator that calculates interference power from a sample signal outside the search window in the delay profile;
Based on the delay profile and the user detection information detected by the first and second user detection units, sampled signals outside the user undetected search window and extracted from the user undetected search window A second interference power estimator that calculates interference power from the sample signal;
A threshold calculation unit for calculating a path detection threshold used for user detection based on the interference power calculated by the first or second interference power estimation unit;
Further comprising
The interference power estimation process is repeatedly performed a predetermined number of times,
In the first interference power estimation process,
The first interference power estimation unit performs a process of calculating interference power using a sample signal outside the search window,
The threshold calculation unit calculates the path detection threshold based on the interference power calculated by the first interference power estimation unit;
In the second and subsequent interference power estimation processing,
The second interference power estimation unit, based on the user detection information detected by the first and second user detection units, a sample signal outside the user-undetected search window, and the user-undetected search Perform processing to calculate the interference power with the sample signal extracted from the window,
The interference power estimation apparatus according to claim 2, wherein the threshold calculation unit performs a process of calculating the path detection threshold based on the interference power calculated by the second interference power estimation unit. In the second interference power estimation unit,
A search window sample extraction unit for selecting the user undetected search window X (n) and extracting a sample signal from the user undetected search window;
The search window sample extraction unit includes:
With reference to user detection information for each search window in the past iteration, when user detection information is recorded for a search window for which the user has not been detected, a predetermined number of sample signals around a predetermined threshold are exceeded. Perform processing to exclude the sample signal from interference power estimation,
The second interference power estimator is
In the search window not detected by the user, interference power estimation processing is performed by adding the sample signals selected by the sample extraction unit in the search window.
The interference power estimation apparatus according to claim 2 or claim 3, wherein The wireless communication system is a W-CDMA (Wideband Code Division Multiple Access) wireless communication system,
The interference power estimation apparatus according to claim 1, wherein the interference power estimation apparatus is used in the CDMA base station apparatus or mobile station apparatus. An interference power estimation method in an interference power estimation device installed in a receiver of a random access wireless communication system,
By the control unit in the interference power estimation device,
A procedure for distinguishing a delay profile of a predetermined period generated by a random access signal transmitted from a transmitter in the wireless communication system into a plurality of search windows and areas outside the search window on the time domain;
A procedure for estimating interference power based on a sample signal outside the search window and a sample signal extracted from the search window;
An interference power estimation method characterized in that is performed. In the computer in the interference power estimation device installed in the receiver of the wireless communication system of the random access method,
A procedure for distinguishing a delay profile of a predetermined period generated by a random access signal transmitted from a transmitter in the wireless communication system into a plurality of search windows and areas outside the search window on the time domain;
A procedure for estimating interference power based on a sample signal outside the search window and a sample signal extracted from the search window;
Interference power estimation program for executing

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