JP4031680B2 - Search window control method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention is a search window control method.And equipmentMore specifically, a search window control method for detecting a received signal path in a CDMA cellular systemAnd equipmentAbout. Under the CDMA cellular system, S / N is improved by RAKE combining signals of a plurality of reception paths.
[0002]
[Prior art]
FIG. 15 is a diagram for explaining the prior art, and FIG. 15 (A) shows a CDMA cellular radio propagation environment. In the figure, 10 is a base station (BTS) that performs a wireless connection service in its own cell (cell radius R), and 30a and 30b are mobile stations (MS) located in the cell.
[0003]
The mobile station 30a is substantially stopped, for example, and the upstream radio wave from the mobile station 30a passes through the paths (2) and (3) that are reflected directly through the path (1) and on the building or the like. The base station 10 is reached indirectly via On the other hand, the mobile station 30b is moving at a speed v, and the upstream radio wave (direct wave) from the mobile station 30b is transmitted to the base station 10 according to the relative speed vr (= v · cos θ) with the base station 10. It is getting closer every moment.
[0004]
Under such circumstances, the base station 10 obtains delay profile data (correlation power) corresponding to the cell radius by taking the correlation between the received signal and the despreading code for the mobile station 30a while shifting the timing. At the same time, so-called RAKE reception is performed by collecting the reception signals of the paths {circle around (1)} to {circle around (3)} that provide a high correlation (peak). The same applies to the mobile station 30b.
[0005]
FIG. 15B is a diagram showing a graph image of delay profile data corresponding to the cell radius. The horizontal axis represents path timing (chip timing), and the vertical axis represents path level (correlation power). Assuming that the base station 10 starts reception (correlation calculation) at the system reference timing T0, the radio wave emitted near the base station 10 at the same timing T0 is received by the base station 10 near the timing T0. In addition, the radio wave emitted near the cell radius (boundary) R at the same timing T0 is received by the base station 10 in the last direction. In this state, the uplink radio wave from the mobile station 30a is received by the base station 10 at an intermediate timing, and the path {circle around (1)} of the mobile station 30a is a direct wave. Has a relatively large amplitude (power). On the other hand, since the paths {circle over (2)} and {circle around (3)} are indirect waves, they reach the base station 10 with a delay and their amplitude is relatively small. On the other hand, since the mobile station 30b is moving at the speed v, its path timing also moves momentarily according to the relative speed vr.
[0006]
Under such circumstances, by setting a search window 50 having a relatively narrow width w with respect to the delay profile data obtained in the base station 10, a received signal path useful for RAKE reception is set in the search window 50. Detection is performed with a small search process.
[0007]
[Problems to be solved by the invention]
However, in the above conventional method, since the window width w is fixed, the actual radio propagation environment is not reflected in the window width w, and therefore, an efficient and reliable reception path cannot be detected. . That is, if the window width w is too wide compared to the actual radio propagation environment, an extra search process for the reception path is required, and if the window width w is too narrow, there is a possibility that a useful reception path is lost. In addition, as the mobile station 30 moves, the radio propagation state also changes variously. Therefore, it has been difficult to perform a reception path search that is consistently efficient and reliable with the conventional method.
[0008]
  The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to provide a search window control method capable of efficiently setting / updating a search window having a position / width according to the actual radio propagation environment.And equipmentIs to provide.
[0012]
[Means for Solving the Problems]
  According to the first aspect of the inventionA search window control method is a search window control method for detecting a received signal path in a CDMA cellular system, the step of detecting a predetermined effective path from delay profile data covering its own cell, and the detected effective path Extracting the earliest and most delayed effective paths in the medium;A search window is obtained by calculating an average interval between the detected predetermined effective paths, and adding the calculated average interval before and after the extracted first path and the most delayed effective path.Steps.
[0013]
  The present inventionAccording to this, it is possible to set (initialize) the search window 50 of the position / width according to the actual radio propagation environment without excess or deficiency based on the timing information of the specific effective path in the delay profile data covering the own cell. Become. Accordingly, it is possible to omit a useless search process for the reception path due to the search window width w being too wide, and to prevent a loss of a useful reception path due to the search window width being too narrow.
[0015]
  Also,The present inventionAccording to the above, before and after the earliest and most delayed effective paths P1 and P2, the actual radio propagation environment (in general, Iave is small in an environment where direct waves easily reach, and Iave is large in an environment where direct waves are difficult to reach). It is possible to secure an optimum margin Iave according to the tendency).
[0016]
  According to the second aspect of the inventionThe search window control method is a search window control method for detecting a received signal path in the CDMA cellular system. The search window control method uses a predetermined effective path (indicated by circled numerals 1 to 4 in the figure) based on delay profile data covering the own cell. And a step of obtaining an average interval Iave between the detected effective paths, dividing the entire delay profile data into a plurality of regions A to O at the average interval Iave, and each of the divided regions A Obtaining the power σA to σO of delay profile data for ˜O, and extracting the regions D and G of the earliest σ1 and the most delayed σ2 among the powers σA to σO exceeding a predetermined threshold σth; And a step of setting a search window 50 in a portion surrounded by the first and most delayed areas D and G.
[0017]
  Note that the delay profile data covering the own cell means, for example, delay profile data covering the cell radius. In addition, the predetermined effective path means each path level (locally) detected in time series (locally) among path levels (correlation power) exceeding a predetermined threshold Pth for delay profile data corresponding to the cell radius (in the figure). Equivalent to circled numbers 1 to 4).
  The present inventionThis search window control method can be easily executed by size comparison using a computer and four arithmetic operations, so that a search window having a position and width corresponding to the actual radio propagation environment can be set (initialized) efficiently. Once such a search window is set, the radio wave propagation environment (for example, average interval Iave) does not change greatly unless the mobile station moves violently. There is no need to set this, and thereafter, tracking of the reception path can be performed with a simple process of changing the position and width of the search window in units of the same area.
[0018]
  A search window control apparatus according to a second aspect of the present invention is a search window control apparatus for detecting a received signal path in a CDMA cellular system, and detects a predetermined effective path from delay profile data covering its own cell. Obtaining an average interval between the detected effective path and the detected effective path, and dividing means for dividing the entire delay profile data into a plurality of regions at the average interval; and determining the power of the delay profile data for each divided region; Extraction means for extracting the earliest and the most delayed areas of the power exceeding a predetermined threshold, and setting means for setting a search window in a portion surrounded by the extracted earliest and the most delayed areas Is.
  Preferably,For example, as shown in FIGS. 13 and 14, there is a search window control method for detecting a received signal path in a CDMA cellular system, the step of setting a search window based on delay profile data covering the own cell, and the setting Or a step of changing the position and / or width of the search window based on delay profile data in the changed search window, which will be described later, and the setting and change rate of the search window according to the relative speed and / or simultaneous processing channel of the mobile station apparatus. And controlling according to the number.
[0019]
  in this way,By combining search window setting (initialization) processing and processing load change (update) processing that is light in load, reception path acquisition and tracking processing can be greatly reduced. In addition, by controlling the ratio between the search window setting process and the change process according to the relative speed of the mobile station apparatus and / or the number of simultaneous processing channels, it is possible to effectively prevent missed reception paths.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings. FIG. 2 is a diagram for explaining a base station receiving unit according to the embodiment, and FIG. 2A shows a block diagram of the receiving unit. 11 is an antenna, 12 is an A / D converter (A / D), 13 is a call channel controller for controlling a plurality of call channels (ch), 14 is a synchronous detector for despreading and detecting received data, 15 is a matched filter unit (MF) that obtains delay profile data (correlation power) of a specific channel signal by performing a correlation operation between the received signal and a known despreading code while shifting the timing (chip timing or the like); 16 is a memory for storing delay profile data, 17 is a microprocessor (MPU) that performs main control and processing of the receiving unit, 18 is a search window determining unit that sets / updates the position and width of the search window based on the delay profile data, 19 is a mobile body speed calculation unit for obtaining a relative speed between the base station and the mobile station, and 20 is a predetermined effective value in the delay profile data. It is a path detection unit that detects the scan.
[0021]
The received signal from the antenna 11 is amplified by an amplifying unit (not shown), and then sent to the matched filter unit 15 via the A / D conversion unit 12 and the speech channel control unit 13, where the received signal and a specific mobile station The delay profile data (correlation power) for the cell radius is obtained by storing the correlation with the despreading code while shifting the timing, and these are stored in the memory 16.
[0022]
FIG. 2B shows how the delay profile data is stored. Correlation data for each path timing (for example, chip timing) obtained by the MF 15 is stored in correspondence (order) of memory addresses. Then, the MPU 17 transfers the delay profile data to the search window determination unit 18, the mobile body speed calculation unit 19, and the path detection unit 20 as necessary, and also obtains search window information and path information obtained by each unit. By sending it to the synchronous detector 14 via the MPU 17, it is used for the despreading / detection processing of the received data. The search window setting / updating process according to the embodiment will be specifically described below.
[0023]
3 and 4 are diagrams (1) and (2) for explaining the search window setting process according to the first embodiment. The delay profile data corresponding to the cell radius is divided into a plurality of areas, and the power for each area is obtained. This shows a case where the search window is set (initialized) based on an area that exceeds the predetermined threshold.
[0024]
FIG. 3A shows a flowchart of search window setting processing according to the first embodiment. In step S11, a predetermined effective path is detected based on delay profile data corresponding to the cell radius. FIG. 3B shows an image of the process in step S11. The path detection unit 20 detects a plurality of paths that exceed a predetermined threshold value Pth for delay profile data corresponding to the cell radius, and for each of the peak levels detected in time series (locally) for a predetermined time. Valid path. In the example of FIG. 3B, predetermined effective paths {circle around (1)} to {circle around (4)} are detected at the respective timings of T1 to T4.
[0025]
In step S12, an average interval Iave between adjacent effective paths is obtained, and the entire delay profile data is divided into a plurality of regions at the interval Iave. FIG. 4A shows an image of the processing in step S12. When each path timing of the effective paths (1) to (4) is T1 to T4, an average interval Iave between adjacent effective paths is
Iave = {(T2-T1) + (T3-T2) + (T4-T3)} / 3
Ask for. In the example of FIG. 4A, the entire delay profile data for the cell radius is divided into, for example, 15 areas A to O by the average interval Iave. If a fractional area appears, the fractional part may be included in the last area O. In general, in a radio wave propagation environment where the average interval Iave of the effective path is narrow (that is, the line of sight is good or the direct wave is easy to reach), the region division width Iave is narrowed, so that the setting resolution of the search window is increased. Conversely, in a radio wave propagation environment in which the average interval between effective paths is wide (that is, the line of sight is bad or indirect waves are dominant), the area division width Iave is widened, so the processing amount is reduced. The
[0026]
In step S13, the power σ of the delay profile data for each region_A~ Σ_OAsk for. Power of each region σ_A~ Σ_OIs easily obtained from the area (cumulative addition value) of the delay profile data in the region. Furthermore, the power σ of each region_A~ Σ_OAmong those exceeding the predetermined threshold σth, the earliest σ1 and the earliest σ2 are extracted, and the search window 50 is set in a portion surrounded by these regions. FIG. 4B shows an image of the process in step S13. In the example shown in the figure, a search window 50 is set in a portion sandwiched between the earliest region D and the most delayed region G (that is, regions D to G).
[0027]
If it is desired to avoid the influence of interference power on each delay profile data, a value obtained by subtracting the average interference power from the power of each path may be used as the delay profile data. The interference power in this case can be easily obtained by dividing the total area (cumulative addition value) of the delay profile data for the cell radius by the number of path samples. The same applies to other embodiments described below.
[0028]
According to the first embodiment, the state of the radio wave propagation environment from the mobile station 30 is accurately grasped by the predetermined effective paths (1) to (4) and the average interval Iave between the effective paths. (Specific) Yes. In addition, since each calculation for realizing this can be performed only by simple four arithmetic operations and size comparison, the processing load on the MPU 17 is small. Furthermore, once the characteristics (Iave, etc.) of the radio wave propagation environment are captured, the radio wave propagation environment from the mobile station 30 does not change abruptly unless the mobile station 30 moves at high speed. This determination process does not necessarily have to be performed every time. That is, there is no need to detect the above-mentioned predetermined effective paths (1) to (4) and to obtain the average interval Iave between them, and the intermediate window control is performed several times, that is, only the process of step S13, Power σ of delay profile data for each divided area A to O_A~ Σ_OAnd the appropriate search window 50 can be reset (initialized) only by a simple process of determining the threshold value by σth.
[0029]
FIGS. 5 and 6 are diagrams (1) and (2) for explaining the search window setting process according to the second embodiment. Information on predetermined effective paths (amplitude, path) included in the delay profile data corresponding to the cell radius. This shows another case where the search window is set (initialized) based on (timing). Note that the window width w in the second embodiment is fixed, so that the processing load for determining the window width w is reduced.
[0030]
FIG. 5A shows a flowchart of search window setting processing according to the second embodiment. In step S21, a predetermined effective path is detected from the delay profile data corresponding to the cell radius in the same manner as in the first embodiment. In the following drawings, such a predetermined effective path is indicated by a thick arrow. In step S22, for each detected effective path, the earliest and most delayed effective paths P1, P2 or the largest effective path Pm is extracted. In step S23, the position of the search window 50 is set (initialized) on the basis of the timing information T1, T2 or Tm of the extracted effective path P1, P2 of the earliest and the most delayed path or the maximum effective path Pm. . There are several methods for setting the position of the search window 50, and these will be specifically described below.
[0031]
FIG. 5B shows a case where a predetermined point (for example, the center point) Tc of the search window 50 is aligned with the midpoint (center of gravity) between the effective paths P1 and P2 of the earliest and the most delayed. In the radio wave propagation environment in which the distance between the first and the most delayed effective paths P1 and P2 is wide (that is, the direct wave is difficult to reach or the distance between the direct wave and the indirect wave is wide), It is preferable to capture the received signals of the effective paths P1 and P2 without omission. Therefore, the predetermined point Tc of the search window 50 is adjusted to the timing (T1 + T2) / 2 of the midpoint (center of gravity) of the effective paths P1 and P2. This method can be automatically adopted, for example, by determining (T2−T1)> α (predetermined threshold).
[0032]
FIG. 6A shows a case in which the magnitudes of the path levels (correlation powers) P1 and P2 of the earliest and the most delayed are taken into consideration in addition to the case of FIG. 5B. The earliest path (direct wave) in a radio wave propagation environment where the distance between the earliest and most delayed effective paths P1 and P2 is narrow (that is, the direct wave is easy to reach or the distance between the direct wave and the indirect wave is narrow). It is preferable to capture the signal of P1 mainly. Therefore, first, the predetermined point Tc of the search window 50 is adjusted to the timing (T1 + T2) / 2 of the midpoint (center of gravity) of the effective paths P1 and P2 as described above. Next, the predetermined point Tc is Tc ′,
Tc ′ = w × P1 / (P1 + P2)
The search window 50 is shifted to a position where In this case, the search window 50 normally has a relationship of capturing the first path P1 side preferentially (that is, in a wide range) rather than the relationship of power P1> P2.
[0033]
First, the predetermined point Tc ′ in the search window 50 is
Tc ′ = w × P1 / (P1 + P2)
Then, the predetermined point Tc ′ may be adjusted to the timing (T1 + T2) / 2 of the midpoint (center of gravity) between the effective paths P1 and P2. In any case, this method can be automatically adopted by, for example, discrimination of (T2−T1) ≦ α (predetermined threshold value).
[0034]
FIG. 6B shows a case where the predetermined point Tc of the search window 50 is adjusted to the maximum power path Pm. In a radio wave propagation environment where the amplitude of the maximum path Pm is large (the direct wave Pm is easy to reach), the search window 50 is set so as to focus on capturing the signal of the maximum path Pm. That is, the predetermined point Tc of the search window 50 is matched with the timing Tm of the maximum path Pm. This method can be automatically adopted by, for example, discriminating (Pm−Pi)> β (predetermined threshold value). However, Pi is the amplitude of another effective path having the second largest amplitude, for example.
[0035]
FIG. 7 is a diagram for explaining the search window setting process according to the third embodiment. The search window setting process includes predetermined effective path interval information included in the delay profile data corresponding to the cell radius and the timing information of the earliest and most delayed paths. In this example, the position and width of the search window are set (initialized) based on the search window.
[0036]
FIG. 7A shows a flowchart of search window setting processing according to the third embodiment. In step S31, a predetermined effective path is detected from the delay profile data corresponding to the cell radius. In step S32, an average interval Iave between the detected effective paths is obtained. In step S33, the first and most delayed effective paths P1 and P2 are extracted from the detected effective paths. In step S34, the position and width of the search window 50 are set (initialized) based on the extracted timing information T1 and T2 of the earliest and most delayed effective paths P1 and P2 and the obtained average interval Iave of the effective paths. )
[0037]
FIG. 7B shows an image of search window setting processing according to the third embodiment. According to the third embodiment, the start position of the search window 50 is (T1-Iave), the end position is (T2 + Iave), and the search window width w is (T2-T1 + 2Iave). Accordingly, the search window 50 having an appropriate margin can be set under any radio wave propagation environment, and the path can be reliably captured.
[0038]
FIGS. 8 to 10 are diagrams (1) to (3) for explaining search window setting processing according to the fourth embodiment, in which delay profile data corresponding to the cell radius is cumulatively added (moving averaged) for a predetermined number of times. This shows the case where the set search window 50 is stabilized (improved reliability).
[0039]
FIG. 8B shows a situation where the setting of the search window 50 becomes unstable. In mobile communication, effective paths appear and disappear due to fading. In particular, the most delayed path P2 that repeats reflection is easily affected by fading. Assuming that the search window at the time when the most delayed path P2 is detected is 50, the search window at the next time is moved to 50 'because the latest delayed path P2' is newly detected at the next time. Thus, in this way, it cannot be said that a highly reliable effective path is necessarily captured. Therefore, in the fourth embodiment, a search window that always captures a highly reliable effective path is set by cumulatively adding (moving average) delay profile data for the cell radius.
[0040]
FIG. 8A shows a flowchart of search window setting processing according to the fourth embodiment. In step S41, a moving average for a predetermined number of times is obtained for the delay profile data for the cell radius. Note that the cumulative addition for a predetermined number of times may be simply performed, but in this case, an equivalent power threshold value may be set. In any case, the path level of the path timing at which the amplitude becomes unstable due to the influence of fading by this cumulative addition process is relatively small, and conversely the path of the path timing at which the amplitude is stable. The level is relatively large. FIG. 9A shows an image of the moving average profile data thus obtained.
[0041]
In step S42, a predetermined effective path is detected from the obtained moving average profile data. In other words, a path that exceeds the predetermined threshold ρth is detected at each path timing, and each path that is peak-detected in the time series is set as a predetermined effective path. In step S43, the earliest and the most delayed or largest effective path ρ1, ρ2, or ρm among the detected effective paths is extracted. In step S44, the search window 50 is set (initialized) based on the extracted timing information T1, T2 or Tm of the earliest and most delayed or maximum effective path ρ1, ρ2 or ρm. For the setting process in step S44, a method similar to that of the second embodiment described with reference to FIGS. 5B, 6A, and 6B can be applied. Although not shown, the moving average profile data according to the fourth embodiment may be applied to the search window setting process described in the third embodiment in FIG.
[0042]
By the way, the process of obtaining the moving average profile data corresponding to the cell radius is not necessarily a light process. Therefore, a device for reducing this processing will be described below. In FIG. 9B, a window 60 having a relatively narrow width before and after the timing Tm when a predetermined effective path (for example, a stable maximum path Pm) is detected.₁, 60₂Are alternately opened as shown in FIG.₁, 60₂The moving average (cumulative addition) of the delay profile data included in each is obtained. Then, by combining the moving average profile data of each region, moving average profile data over a desired range in total can be efficiently obtained.
[0043]
FIG. 10 shows another method for acquiring moving average profile data. When the delay profile data acquisition period is long, or when the mobile station 30 is moving at a relatively high speed, it is difficult to obtain sufficient moving average profile data within a short time. In this case, weighted addition of delay profile data is performed. That is, as shown in the figure, when a path level exceeding the high threshold value Pth4 is detected, there is a high possibility that the path is a stable effective path. Therefore, a large weight value (for example, 4) is added to the detected path level. ) And cumulatively add. On the other hand, when a path level that exceeds the lower threshold value Pth1 and does not exceed the next higher threshold value Pth2 is detected, it is unlikely that the path is a stable valid path. Is cumulatively multiplied by a small weight value (for example, 1). Thus, a moving average (cumulative addition) for a predetermined number of times is obtained. In this way, a highly reliable path and a low-reliability path can be distinguished from each other even with a relatively small number of cumulative additions. Therefore, highly reliable moving average profile data can be obtained efficiently.
[0044]
FIGS. 11 and 12 are diagrams (1) and (2) for explaining the search window update processing according to the embodiment. The position of the next search window is determined based on information on a predetermined effective path included in the current search window. The case of updating (changing) is shown. Since this search window update process only needs to process the delay profile data included in the current search window, the processing load is greatly reduced and the setting (initial stage) is set according to the first to fourth embodiments. It is suitable for updating (changing) the position (and width if necessary) of the search window.
[0045]
FIG. 11A shows a flowchart of search window update processing according to the embodiment. In step S51, a predetermined effective path is detected from the delay profile data in the current search window. That is, a plurality of paths exceeding the predetermined threshold value Pth are detected for the delay profile data in the current search window, and those for each peak level detected in time series (locally) are determined as predetermined effective paths. And In step S52, for each of the detected predetermined effective paths, the effective paths P1 and P2 that are the earliest and the most delayed in the current search window or the effective path Pm that is the maximum are extracted. In step S53, the next search window is updated (changed) based on the timing information T1, T2 or Tm of the extracted effective path P1, P2 of the earliest and the most delayed path or the maximum effective path Pm. Note that there are several possible search window update (change) methods in step S53, which will be described in detail below.
[0046]
FIG. 11B shows a case where the predetermined point Tc of the search window is matched with the timing of the midpoint (center of gravity) of the earliest and most delayed effective paths P1 and P2 detected this time. This search window 50₁The path timings of the earliest and most delayed effective paths P1 and P2 detected in T1 and T2 (however, the search window 50₁Relative search timing), the next search window 50₂The predetermined point Tc is adjusted to the timing (T1 + T2) / 2 of the midpoint (center of gravity) between the effective paths P1 and P2.
[0047]
Note that this alignment may be changed all at once for the timing of the new midpoint (center of gravity) detected each time, but this increases the movement of the search window and makes it unstable. It can be. Therefore, preferably, this alignment is performed with a limit of several chips (or several oversamples) in the direction in which the deviation is detected. Alternatively, the actual movement amount may be reduced by gradually multiplying the obtained movement amount of Tc by a predetermined number (<1). Therefore, the movement of the predetermined effective paths P1 and P2 can be stably followed by a simple process.
[0048]
Although not shown, the next search window 50 is similar to the case of FIG.₂The predetermined point Tc ′ of
Tc ′ = w × P1 / (P1 + P2)
You may change to the position which becomes.
[0049]
FIG. 12A shows a case where the predetermined point Tc of the search window is adjusted to a position offset (delayed) by the predetermined timing ΔT from the maximum effective path Pm detected this time. Therefore, the next search window 50₂Follows the side of the maximum path Pm detected this time. In this case as well, the amount of deviation may be changed at once, but it may be preferably moved by a limit of several chips (or several oversamples).
[0050]
FIG. 12B shows the current search window 50.₁Next search window 50 so that the front and back of each of the earliest and most delayed effective paths P1 and P2 detected within a predetermined width Iave can be enclosed.₂The case where it matches to the position and width of is shown.
This predetermined width Iave is the current search window 50.₁It is calculated | required as an average space | interval between each effective path contained in.
[0051]
Although not shown, in order to suppress the influence due to fading as much as possible, the size of each effective path detected so far (particularly the most delayed path P2 that is easily affected by fading) and the distance between the first path P1 The distance and the like are stored, and if the most delayed path P2 disappears from the vicinity of the planned position, the search as shown in FIG. 11B or FIG. 12B is performed for a predetermined time. The window tracking control may not be performed.
[0052]
FIGS. 13 and 14 are diagrams (1) and (2) for explaining the search window control process according to the embodiment. The search window setting (initialization) control and update (change) control are performed at an appropriate frequency. This shows a case where a fast response and stable path detection is realized.
[0053]
FIG. 13A shows a flowchart of search window control processing according to the embodiment. This search window control process is cyclically performed for each mobile station in the simultaneous call, and which mobile station is currently controlled is identified by the mobile station index information (I). . When it is time to control the search window of a certain mobile station, it is input to this process.
[0054]
In step S61, it is determined whether or not the counter CTR (I) = 0 for determining the setting (initialization) timing of the search window 50 is satisfied. When CTR (I) = 0, it is the setting (initialization) timing of the search window 50. Therefore, in step S62, the search window 50 is set (initialized) based on the delay profile data for the cell radius. If CTR (I) ≠ 0, the search window 50 is updated (changed), so that the search window 50 of this time is displayed in step S63.₁Next search window 50 based on the delay profile data included in₂Update (change) processing is performed. In step S64, the count value of the counter CTR (I) is incremented by one.
[0055]
In step S65, the relative speed vr (I) of the mobile station (I) with respect to the base station is estimated. The relative speed of the mobile station can be estimated, for example, by monitoring the amount of motion per unit time (that is, search window update period) of the earliest, longest delay or maximum effective path included in the delay profile data. Preferably, in a radio wave propagation environment in which direct waves are easy to reach, the relative velocity vr of the mobile station is determined by the time change of the timing Tm of the maximum path Pm. Further, in a radio wave propagation environment where direct waves are difficult to reach, the relative speed vr of the mobile station is determined by the time change of the center of gravity timing (T1 + T2) / 2 of the earliest path and the delay path.
[0056]
In step S66, the number of simultaneous call channels for which the base station 10 is currently providing a connection service is extracted from the call channel control unit 13. In step S67, with reference to a table to be described later, a count limit value K of the counter CTR (I) corresponding to the obtained relative speed vr (I) of the mobile station (I) and the number of extracted simultaneous processing channels is extracted. .
[0057]
FIG. 13B is a graph showing the stored contents of the table. The horizontal axis represents the relative speed vr of the mobile station, and the vertical axis represents the count limit value K. In the figure, (1) indicates the characteristics when the number of simultaneous processing channels is small (the processing load of the MPU 17 is small). When the relative speed vr of the mobile station is small, the search window is, for example, once every seven times. When 50 is set (initialized) and the relative velocity vr of the mobile station is large, the effective path can be detected without omission (that is, following the search window) even for this fast movement, for example, four times. This indicates that the search window 50 is set (initialized) at a rate of once. As the number of simultaneous processing channels increases from medium to large, the processing load on the MPU 17 increases and the time available for control of a specific mobile station decreases. That is, the time interval (cycle) in which a specific mobile station can be controlled is inevitably increased. Therefore, in order to cover that the control is delayed as the number of simultaneous processing channels increases, characteristics {circle over (2)} and {circle over (3)} are provided to further increase the rate of setting (initializing) the search window 50. .
[0058]
Returning to FIG. 13A, it is determined in step S68 whether or not CTR (I) ≧ K. If CTR (I) ≧ K, in step S69, CTR (I) = 0 (next set mode) is initialized. And exit from this process. If CTR (I) ≧ K is not satisfied, the process of step S69 is skipped and the process is exited.
[0059]
FIG. 14 shows a timing chart of the search window control process. FIG. 14A shows a case where the number of simultaneous processing channels is small and the relative speed of the mobile station is low. For example, the search window is set (initialized) at a rate of once every four times. FIG. 14B shows a case where the number of simultaneous processing channels is large and the relative speed of the mobile station is low. Even if the relative speed is low, if the number of simultaneous processing channels is large, the processing load on the MPU 17 increases, and the period T during which a certain mobile station can be repeatedly controlled increases. Therefore, in this case, for example, the search window is set (initialized) at a rate of once every three times.
[0060]
FIG. 14C shows a case where the number of simultaneous processing channels is large and the relative speed of the mobile station is high. When the relative speed of the mobile station increases, the search window is set (initialized) at a rate of once every two times in order to follow this (that is, to prevent the effective path from being removed from the search window 50). To do. FIG. 14D shows a case where the number of simultaneous processing channels is small and the relative speed of the mobile station is high. When the number of simultaneous processing channels decreases, the processing load on the MPU 17 is reduced, and the control cycle T is shortened accordingly.
[0061]
In the search window control process shown in FIG. 13A, the search window setting control and update control are controlled based on the relative speed of the mobile station and the number of simultaneous processing channels of a plurality of mobile stations. Not limited to this. For example, it may be possible to control only by the relative speed of the mobile station or by the number of simultaneous processing channels of the mobile station.
[0062]
Moreover, although several embodiment suitable for the said invention was described, it cannot be overemphasized that the structure of each part, control, a process, and these combination can be variously changed within the range which does not deviate from this invention. .
[0063]
(Supplementary Note 1) A search window control method for detecting a received signal path in a CDMA cellular system, wherein a predetermined effective path is detected from delay profile data covering its own cell, and between the detected effective paths Determining an average interval, dividing the entire delay profile data into a plurality of regions at the average interval, determining the power of the delay profile data for each of the divided regions, and the first and A method for controlling a search window, comprising: extracting each area with the longest delay; and setting a search window in a portion surrounded by the extracted first and most delayed areas.
[0064]
(Supplementary Note 2) A search window control method for detecting a received signal path in a CDMA cellular system, comprising: detecting a predetermined effective path from delay profile data covering its own cell; A search window comprising: extracting the earliest and most delayed or maximum effective path; and setting a search window based on the extracted timing information of the earliest and most delayed or maximum effective path. Control method.
[0065]
(Supplementary note 3) The search window control according to Supplementary note 2, wherein the step of setting the search window includes aligning a predetermined point of the search window having a fixed width with a midpoint position of the first path and the most delayed effective path. Method. Therefore, the first and the most effective paths can be captured with the same weighting, and each of the first and the most delayed paths can be obtained even in a radio wave propagation environment where the distance between the direct wave path and the indirect wave path is wide. A valid path can be reliably captured.
[0066]
(Supplementary Note 4) When the width of the search window is w and the amplitudes of the effective paths of the earliest and the most delayed are P1 and P2, the predetermined point Tc of the search window is
Tc = w × P1 / (P1 + P2)
The search window control method according to appendix 3, characterized in that: Therefore, in general, there is a relationship of P1> P2 with respect to the amplitudes P1 and P2 of each of the earliest and the most delayed effective paths. According to the supplementary note 4, the predetermined point Tc viewed from the front end of the search window is expressed as Tc = By setting w × P1 / (P1 + P2), the search window surrounds the periphery of the first effective path at a higher rate.
[0067]
(Supplementary note 5) The search window control method according to supplementary note 2, wherein the step of setting the search window includes aligning a predetermined point of the search window having a fixed width with the position of the maximum effective path. Therefore, the search window in this case surrounds the periphery of the maximum effective path (which is likely to be a direct wave) at a higher rate.
[0068]
(Supplementary Note 6) The method further includes a step of obtaining an average interval between the detected predetermined effective paths, and the step of setting the search window includes calculating the average interval before and after the extracted first and most delayed effective paths. The search window control method according to claim 2, wherein a search window is added to the search window.
[0069]
(Supplementary note 7) The search window according to Supplementary note 1 or 2, further comprising a step of obtaining a moving average of a predetermined number of times of delay profile data covering the own cell to obtain delay profile data covering the own cell. Control method. According to Appendix 7, the moving average (or cumulative addition value) of a stable effective path that is always detected (for example, a direct wave path) appears relatively large, and is unstable such that it is detected or disappears. Since a moving average (or cumulative addition value) of a valid path (for example, an indirect wave path) appears relatively small, a more stable valid path can be reliably captured.
[0070]
(Supplementary Note 8) A search window control method for detecting a received signal path in a CDMA cellular system, the step of detecting a predetermined effective path from delay profile data in the search window, and a maximum in the detected effective path Extracting the first and most delayed or maximum effective path; and changing the position and / or width of the search window based on the extracted timing information of the first and most delayed or maximum effective path. Search window control method.
[0071]
(Supplementary note 9) A search window control method for detecting a received signal path in a CDMA cellular system, the step of setting a search window based on delay profile data covering its own cell, and the setting or modification described later The step of changing the position and / or width of the search window based on the delay profile data in the search window, and the setting and change rate of the search window are controlled according to the relative speed of the mobile station apparatus and / or the number of simultaneous processing channels. And a search window control method.
[0072]
(Supplementary Note 10) Setting means for setting a search window corresponding to a mobile station apparatus based on delay profile data covering the own cell in a base station apparatus capable of accommodating a plurality of mobile station apparatuses in a plurality of channels under a CDMA cellular system; Change means for changing the position and / or width of the search window based on the delay profile data in the set or changed search window, which will be described later, detection means for detecting the relative speed of the mobile station apparatus, A base station apparatus comprising control means for controlling a ratio of setting and change in accordance with a relative speed of the mobile station apparatus and / or the number of simultaneous processing channels.
[0073]
【The invention's effect】
As described above, according to the present invention, a search window having a position / width according to an actual radio propagation environment can be set / updated efficiently, so that a received signal path in the CDMA cellular system can be captured efficiently and reliably.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the principle of the present invention.
FIG. 2 is a diagram illustrating a base station receiving unit according to an embodiment.
FIG. 3 is a diagram (1) illustrating search window setting processing according to the first embodiment.
FIG. 4 is a diagram (2) for explaining search window setting processing according to the first embodiment;
FIG. 5 is a diagram (1) illustrating search window setting processing according to the second embodiment.
FIG. 6 is a diagram (2) illustrating search window setting processing according to the second embodiment.
FIG. 7 is a diagram illustrating search window setting processing according to the third embodiment.
FIG. 8 is a diagram (1) illustrating search window setting processing according to the fourth embodiment.
FIG. 9 is a diagram (2) illustrating search window setting processing according to the fourth embodiment.
FIG. 10 is a diagram (3) illustrating search window setting processing according to the fourth embodiment.
FIG. 11 is a diagram (1) illustrating search window update processing according to the embodiment.
FIG. 12 is a diagram (2) for explaining search window update processing according to the embodiment;
FIG. 13 is a diagram (1) illustrating a search window control process according to the embodiment.
FIG. 14 is a diagram (2) for explaining search window control processing according to the embodiment;
FIG. 15 is a diagram illustrating a conventional technique.
[Explanation of symbols]
10 Base station (BTS)
11 Antenna
12 A / D converter (A / D)
13 Call control unit
14 Synchronous detection section
15 Matched filter section (MF)
16 memory
17 Microprocessor (MPU)
18 Search window decision section
19 Mobile station speed calculator
20 path detector
30 Mobile station (MS)

Claims (3)

A search window control method for detecting a received signal path in a CDMA cellular system, comprising:
Detecting a predetermined effective path from delay profile data covering the own cell;
Extracting the earliest and most delayed effective paths in the detected effective paths;
Obtaining an average interval between the detected predetermined effective paths;
A search window control method comprising: a search window obtained by adding the calculated average interval before and after the extracted first path and the most delayed effective path . A search window control method for detecting a received signal path in a CDMA cellular system, comprising:
Detecting a predetermined effective path from delay profile data covering the own cell;
Obtaining an average interval between the detected effective paths, and dividing the entire delay profile data into a plurality of regions at the average interval;
Obtaining the power of the delay profile data for each of the divided areas, and extracting each area of the earliest and the most delayed among the power exceeding a predetermined threshold;
A search window control method comprising: setting a search window in a portion surrounded by each of the extracted first and most delayed areas. A search window control device for detecting a received signal path in a CDMA cellular system,
  Detecting means for detecting a predetermined effective path from delay profile data covering the own cell;
  Dividing means for obtaining an average interval between the detected effective paths and dividing the entire delay profile data into a plurality of regions at the average interval;
  Obtaining the power of the delay profile data for each of the divided areas, extracting means for extracting the first and the most delayed areas of the power exceeding a predetermined threshold;
  A search window control apparatus comprising: setting means for setting a search window in a portion surrounded by each of the extracted first and last delay areas.

Images