JP5772433B2 - Wireless communication system, wireless communication apparatus, and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication system, a wireless communication apparatus, and a wireless communication method that perform wireless communication.

  In recent years, development of LTE (Long Term Evolution), which is one of high-speed data communication specifications for mobile phones, has been underway. In the LTE radio communication system, when a mobile station and a radio base station are connected, control for establishing a radio link called random access is performed.

  When establishing a radio link, first, an access signal is transmitted from the mobile station to the radio base station. In LTE random access, the access signal is referred to as a random access signal (RACH Preamble: Random Access Channel Preamble).

  The random access signal is received by the radio base station, and communication is started between the mobile station and the radio base station by connecting the random access signal and the mobile station by the radio base station.

  As a conventional technique, a technique for automatically setting parameters of a random access channel has been proposed.

JP 2009-55356 A

  However, conventionally, there has been a problem that the radio base station may erroneously detect a random access signal due to the influence of multipath or noise in the communication environment surrounding the mobile station and the radio base station.

  The erroneous detection of a random access signal means that a random access signal is erroneously detected even though transmission of the random access signal is not performed on the mobile station side recognized by the radio base station.

  When the radio base station detects the random access signal, the radio base station secures radio resources for performing communication with the mobile station to be communicated. However, when a random access signal is erroneously detected, an unnecessary radio resource is actually secured even though no random access signal is transmitted from any mobile station. Then, since radio resources cannot be used for other mobile stations, throughput characteristics are deteriorated.

  In recent high-speed wireless communication systems, further improvement in transmission quality is required. For this reason, there is a demand for a technique for appropriately recognizing a mobile station that has transmitted an access signal when establishing a radio link, identifying the mobile station, and accurately detecting the access signal transmitted from the mobile station. ing.

  The present invention has been made in view of these points, and provides a radio communication system that identifies a mobile station that has transmitted an access signal and suppresses erroneous detection of the access signal transmitted from the mobile station. For the purpose.

  Another object of the present invention is to provide a radio communication apparatus that identifies a mobile station that has transmitted an access signal and suppresses erroneous detection of the access signal transmitted from the mobile station.

  In order to solve the above problems, a wireless communication system is provided. A wireless communication system includes a mobile station that transmits an access signal for establishing a wireless link, a storage unit that stores reception timing of the access signal, and a detection determination unit that performs detection determination of the access signal. A radio base station having a communication device, wherein the detection determination unit receives a first difference that is a difference between a reception timing of the access signal received last time and a processing reference timing, and reception of the access signal received this time A second difference that is a difference between the timing and the processing reference timing is determined, and the mobile station is identified according to the comparison result, and the access signal transmitted from the identified mobile station is identified. It is determined that the access signal is detected according to the number of continuous receptions of the access signal exceeding the threshold level.

  It is possible to identify the mobile station that has transmitted the access signal and to suppress erroneous detection of the access signal transmitted from the mobile station.

It is a figure which shows the structural example of a radio | wireless communications system. It is a figure which shows the network structural example. It is a figure which shows the sequence of random access. It is a figure for demonstrating the pattern matching of a random access signal. It is a figure which shows a delay profile. It is a figure which shows the structural example of a random access signal reception process part. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows a threshold value table. It is a figure which shows the relationship between a detection threshold value and a completion rate. It is a figure which shows the operation | movement flow of a random access signal processing part. It is a figure which shows the update operation | movement flow of a detection threshold value. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows a threshold value table. It is a figure which shows the relationship between a detection threshold value and a measurement level. It is a figure which shows the update operation | movement flow of a detection threshold value. It is a figure for demonstrating power ramping. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows the operation | movement flow of a random access signal processing part. It is a figure which shows the adjustment flow of a continuous reception frequency | count threshold value. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows a threshold value table. It is a figure which shows the relationship between a continuous reception frequency | count threshold value and a measurement level. It is a figure which shows the update operation | movement flow of a continuous reception frequency threshold value. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows the operation | movement flow of a random access signal processing part. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows the operation | movement flow of a random access signal processing part. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows a detection threshold value. It is a figure which shows the operation | movement flow of a random access signal processing part. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows the operation | movement flow of a random access signal processing part. It is a figure which shows the structural example of a random access signal processing part. It is a figure which shows the operation | movement flow of a random access signal processing part. It is a figure which shows the block structural example of the hardware of the baseband signal processing part inside a wireless base station. It is a figure which shows the block structural example of the hardware of a mobile station.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a wireless communication system. The radio communication system 1 includes a mobile station Ms and a radio base station Bs. The radio base station Bs includes a radio communication device 1-1, and the radio communication device 1-1 includes a storage unit 1-1a and a detection determination unit 1-1b.

  The mobile station Ms transmits an access signal for establishing a radio link to the radio base station Bs. The storage unit 1-1a stores access signal reception timing. The detection determination unit 1-1b performs detection determination of the access signal.

  Here, the detection determination unit 1-1b receives the first difference which is the difference between the reception timing of the access signal received last time and the processing reference timing inside the wireless communication apparatus 1-1, and the reception of the access signal received this time. A second difference that is a difference between the timing and the processing reference timing is obtained and compared. When the comparison result can be regarded as a match, the mobile station Ms is identified by recognizing that the access signal is transmitted from the same mobile station Ms.

  If the number of times of continuous reception of an access signal exceeding the threshold level is equal to or greater than the threshold of continuous reception times for the access signal transmitted from the specified mobile station Ms, it is determined that the access signal is detected.

  Thus, in the wireless communication system 1, the mobile station Ms that transmitted the access signal is specified from the difference information between the reception timing of the access signal and the processing reference timing. Then, when the access signal exceeding the threshold level is continuously received from the identified mobile station Ms for the set number of times or more, it is determined that the access signal is detected.

  As a result, the mobile station Ms that has transmitted the access signal can be appropriately identified, and it is possible to suppress erroneous detection of the access signal transmitted from the mobile station Ms. In addition, since the access signal is detected with high accuracy, radio resources can be used effectively, and the throughput characteristics of the entire system can be improved. 1 will be described later with reference to FIGS. 24 and 25.

  Next, an example of an LTE network configuration to which the wireless communication system 1 is applied will be described. FIG. 2 is a diagram illustrating a network configuration example. The communication network 100 includes wireless areas 101 and 102 and a core network 103.

  A radio base station Bs1 and mobile stations Ms1 to Ms4 are arranged in the radio area 101, and the radio base station Bs1 communicates with the mobile stations Ms1 to Ms4. In addition, a radio base station Bs2 and mobile stations Ms5 to Ms8 are arranged in the radio area 102, and the radio base station Bs2 communicates with the mobile stations Ms5 to Ms8.

  The core network 103 and the radio base stations Bs1 and Bs2 are connected to a wired transmission line called an S1 interface. Further, the wireless base stations Bs1 and Bs2 are connected to a wired transmission line called an X2 interface.

  Next, an LTE random access sequence will be described. FIG. 3 is a diagram showing a random access sequence. Hereinafter, the access signal is referred to as a random access signal.

[S1] The mobile station Ms0 transmits the RACH message # 1 to the radio base station Bs0. The RACH message # 1 corresponds to a random access signal (RACH preamble).
[S2] When the radio base station Bs0 detects a random access signal, it returns a RACH message # 2 to the mobile station Ms0. RACH message # 2 corresponds to a response signal (RACH response).

  [S3] Upon receiving the response signal, the mobile station Ms0 transmits a RACH message # 3 to the radio base station Bs0. The RACH message # 3 includes information necessary for communication such as a user ID and upper layer application information.

[S4] When receiving the RACH message # 3, the radio base station Bs0 returns the RACH message # 4. Thereafter, a predetermined random access process is performed.
Here, the signal pattern of the random access signal will be described. In LTE, a Zadoff-Chu sequence is usually used as a random access signal. The Zadoff-Chu sequence is a signal pattern generated by cyclically shifting one sequence. Since the Zadoff-Chu sequence has a feature that the cross-correlation between cyclic sequences is small, a plurality of random access signals can be generated from one sequence.

  Next, pattern matching of random access signals will be described. The LTE radio base station Bs0 notifies a set of random access signals (random access signal group) to the mobile station Ms0 in advance.

  The radio base station Bs0 specifies a random access signal by performing pattern matching based on correlation calculation between a random access signal assumed to be received and the actually received random access signal.

FIG. 4 is a diagram for explaining pattern matching of a random access signal.
[S11] The radio base station Bs0 notifies the mobile station Ms0 of the random access signal group.

[S12] The mobile station Ms0 selects an arbitrary random access signal from the random access signal group, and transmits the selected random access signal to the radio base station Bs0.
[S13] The radio base station Bs0 calculates a correlation value by performing a correlation calculation between a random access signal (random access signal replica) expected to be received and a random access signal actually received.

  [S14] The radio base station Bs0 recognizes the random access signal transmitted by the mobile station Ms0 based on the magnitude of the correlation value (the correlation value is large if the correlation is high and the correlation value is small if the correlation is low).

Next, a delay profile obtained by correlation calculation will be described. FIG. 5 is a diagram showing a delay profile. The vertical axis represents the reception level (or correlation value), and the horizontal axis represents time.
Since the radio base station Bs0 performs correlation calculation of digital processing, a discretely sampled delay profile Pr is generated. Time ts in the figure is a digital sampling time (sampling resolution).

  It can be recognized from the information of the delay profile Pr whether or not the mobile station Ms0 has transmitted an assumed random access signal. Furthermore, when the random access signal is transmitted, the propagation delay time between the mobile station Ms0 and the radio base station Bs0 can be measured.

  Whether or not the assumed random access signal is transmitted from the mobile station Ms0 is normally transmitted when the reception level of the random access signal exceeds the level of a previously prepared threshold (hereinafter also referred to as a detection threshold). Judge that there was.

  The propagation delay time can be obtained by measuring a difference (delay time) from the processing reference timing inside the radio base station Bs0. For example, it is assumed that the time tr in the figure is the processing reference timing in the radio base station Bs0, and the radio base station Bs0 wants to receive the signal transmitted from the mobile station Ms0 at the time tr.

  Furthermore, time t1 is the time when a random access signal transmitted from the mobile station Ms0 is received. In this case, the propagation delay time is obtained by measuring the difference between the time tr and the time t1 (generally, measuring the difference with the largest reception level in the delay profile Pr).

  Also, the radio base station Bs0 includes the propagation delay time information as a TA (Timing Advance) command in the response signal (RACH message # 2) shown in FIG. 3, and notifies the mobile station Ms0 of feedback.

  The mobile station Ms0 extracts the TA command from the received response signal, recognizes the transmission timing of the signal to be transmitted to the radio base station Bs0 based on the content of the TA command, and adjusts the timing. In this example, the mobile station Ms0 transmits the signal earlier than the radio base station Bs0 by a delay time (= t1-tr) so that the signal arrives at the time tr.

Next, erroneous detection of a random access signal will be described. Depending on the communication environment surrounding the mobile station Ms0 and the radio base station Bs0, erroneous detection of a random access signal may occur.
In this case, if the detected random access signal is actually transmitted from the mobile station Ms0 and the random access signal is regarded as being detected, the radio base station Bs0 determines that the random access signal as shown in FIG. Try to start a sequence of processes.

  Therefore, even if erroneous detection is performed, the radio base station Bs0 transmits a response signal on the downlink, and further attempts to receive the RACH message # 3 transmitted from the mobile station Ms0 on the uplink.

  The radio base station Bs0 performs reception processing using radio resources assigned to the RACH message # 3. At this time, if it is determined that the RACH message # 3 has not been correctly received using error correction such as CRC (Cyclic Redundancy Checking), the RACH message # 3 is retried for the maximum number of retransmissions defined by the system.

  In the case of erroneous detection of a random access signal, the mobile station Ms0 that transmits the RACH message # 3 does not exist, so the RACH message # 3 is not received. For this reason, reception processing for the maximum number of retransmissions of RACH message # 3 is performed.

  Such an operation unnecessarily occupies radio resources that should be usable for other mobile stations, and in the case of frequent misdetections, the uplink side of the entire system The throughput characteristics will be greatly reduced.

  The present technology has been made in view of such a point, and provides a wireless communication system, a wireless communication device, and a wireless communication method that are intended to suppress erroneous detection of random access signals.

  Next, the configuration of the radio communication apparatus 1-1 included in the radio base station Bs shown in FIG. 1 will be described. FIG. 6 is a diagram illustrating a configuration example of a random access signal receiving unit. The wireless communication device 1-1 includes a random access signal reception unit 1a-1.

  The random access signal receiver 1a-1 includes an RF (Radio Frequency) processor 21a, an A / D converter 21b, a demodulation processor 21-1, and a random access signal processor 10.

  The demodulation processing unit 21-1 includes an FFT (Fast Fourier Transform) unit 21-1a, a demapping unit 21-1b, and an IDFT (Inverse Discrete Fourier Transform) unit 21-1c.

  The random access signal processing unit 10 includes a correlation calculation processing unit 11 and a detection processing unit 12. Furthermore, the correlation calculation processing unit 11 includes a correlation value calculator 11a, a power converter 11b, and a peak detector 11c.

  The RF processing unit 21a down-converts the random access signal transmitted from the mobile station Ms from the radio frequency band to the baseband frequency band. The A / D converter 21b converts the analog baseband signal into digital data. The digital data is subjected to baseband signal processing by the demodulation processing unit 21-1 and the random access signal processing unit 10 in the subsequent stage.

  The demodulation processing unit 21-1 performs digital data demodulation processing. Here, in the modulation process on the transmission side, DFT (Discrete Fourier Transform) processing is performed on the digital data, mapping processing for mapping the processing result on the frequency axis is performed, and mapping data is further processed by IFFT (Inverse FFT) processing. The modulation process is performed.

  Therefore, in the demodulation processing unit 21-1, as a reverse process, the FFT unit 21-1a performs a demapping process in which the digital data is FFT processed, and the demapping unit 21-1b demaps the processing result from the frequency axis. Do. Further, the IDFT section 21-1c performs IDFT processing on the demapping data, so that the digital data is demodulated.

The demodulated signal (uplink reception data) is input to the random access signal processing unit 10, and the uplink calculation data is subjected to correlation calculation processing by the correlation calculation processing unit 11.
The correlation value calculator 11a performs correlation calculation (autocorrelation calculation) between uplink reception data and a random access signal replica that is a correlation detection signal prepared in advance.

  The power conversion unit 11b converts the amplitude of the correlation value output from the correlation value calculator 11a into a power signal. This power signal corresponds to the delay profile Pr shown in FIG. The peak detector 11c detects the peak value having the highest level from the power signal.

  The correlation calculation result (peak value) output from the correlation calculation processing unit 11 is input to the detection processing unit 12. The detection processing unit 12 performs a random access signal detection process from the correlation calculation result.

  Here, when the assumed random access signal is received, the highest autocorrelation peak appears, and the presence or absence of the random access signal is determined by finding this. When there are a plurality of random access signals that may be transmitted, the correlation value calculation process is performed for all of them.

  Note that a matched filter can be applied as one method of correlation calculation in the correlation value calculator 11a. The matched filter detects the correlation between the received data and the correlation detection signal (random access signal replica). The power conversion unit 11b converts the obtained correlation value to a power signal by squaring.

  In LTE, as described above, a Zadoff-Chu sequence is used as a random access signal. As a feature of this sequence, there is a feature that a cross-correlation with a state where a cyclic shift is performed is low. That is, the correlation between a sequence subjected to a certain cyclic shift and a sequence subjected to another cyclic shift is low.

  Therefore, in the correlation value calculator 11a, when the heads of the received sequences are compared and coincident with each other, a high correlation may be obtained, and the result is obtained as a delay profile Pr as shown in FIG. Will appear.

  Next, a first embodiment of the wireless communication device 1-1 will be described. FIG. 7 is a diagram illustrating a configuration example of the random access signal processing unit. The random access signal processing unit 10-1 includes a correlation calculation processing unit 11 and a detection processing unit 12-1. The detection processing unit 12-1 includes a completion rate calculation unit 12-1a, a threshold value determination unit 12-1b, and a determination unit 12-1c.

  When the wireless communication device 1-1 receives the random access signal, the completion rate calculation unit 12-1a transmits the response signal (RACH message # 2) transmitted to the mobile station Ms, and the mobile station Ms responds. The number of successful receptions of the message signal (RACH message # 3) to be transmitted to the radio base station Bs when receiving the signal is measured.

  Then, a completion rate obtained from the reception probability of the RACH message # 3 responded from the mobile station Ms to the transmission of the response signal (RACH message # 2) is calculated. The completion rate is calculated by the following equation (1).

Completion rate = (Number of successful receptions of RACH message # 3) / (Number of transmissions of RACH message # 2) (1)
The threshold value determination unit 12-1b has a threshold value table described later, and determines a detection threshold value based on the completion rate registered in the threshold value table. The determination unit 12-1c uses the detection threshold determined by the threshold determination unit 12-1b, and determines that the random access signal is detected if the reception level of the random access signal is equal to or higher than the detection threshold.

  The determination result is transferred to the subsequent processing unit. In the subsequent processing unit, when a determination result indicating that the random access signal is detected is received, a response signal is generated. The response signal is transmitted to the mobile station Ms after being subjected to transmission processing in the transmission system in the radio base station Bs.

  FIG. 8 shows a threshold table. The threshold table T1 is a table in which a correspondence relationship between the completion rate and the detection threshold is registered. The detection threshold is uniquely determined based on the registered contents of the threshold table T1.

  FIG. 9 is a diagram showing the relationship between the detection threshold and the completion rate. The vertical axis represents the detection threshold, and the horizontal axis represents the completion rate. If the value of the completion rate is small, the possibility of occurrence of erroneous detection increases. Therefore, in order to avoid erroneous detection, in the threshold value table T1 shown in FIG. 8, values are set such that the detection threshold value increases as the completion rate decreases, as shown in the graph g1.

  Next, the operation of the random access signal processing unit 10-1 will be described using a flowchart. FIG. 10 is a diagram showing an operation flow of the random access signal processing unit. Note that the following operations are performed in units of IDs of random access signals (that is, performed for all different random access signal patterns).

[S21] The correlation calculation processing unit 11 performs a correlation calculation process on the uplink received data.
[S22] The determination unit 12-1c determines whether the peak exceeds the variably set detection threshold. If it exceeds, go to step S23. Note that the detection threshold is changed according to the completion rate.

  [S23] The determination unit 12-1c determines that a random access signal is detected. When it is determined that a random access signal is detected, a response signal is transmitted from the radio base station Bs to the mobile station Ms.

  FIG. 11 is a diagram showing a detection threshold update operation flow. The detection threshold update process described below is continued until a request for stopping the update process is received from the upper application to the wireless communication apparatus 1-1.

[S31] The threshold determination unit 12-1b determines whether there is a detection threshold update processing start request from an upper application or the like. If there is an update processing start request, the process goes to step S32.
[S32] The completion rate calculator 12-1a initializes the number of successful receptions of the RACH message # 3 and the number of transmissions of the response signal (RACH message # 2), and starts counting.

[S33] The threshold determination unit 12-1b initializes a threshold update timer and starts time counting.
[S34] The threshold determination unit 12-1b determines whether or not the timer value is equal to or greater than the update period. If the timer value is greater than or equal to the update period, the process goes to step S35.

[S35] The completion rate calculator 12-1a calculates a completion rate.
[S36] The threshold determination unit 12-1b selects a detection threshold corresponding to the completion rate from the threshold table T1.

[S37] The completion rate calculator 12-1a initializes the number of successful RACH message # 3 receptions and the number of RACH message # 2 transmissions, and restarts counting.
[S38] The threshold determination unit 12-1b initializes the timer value of the threshold update timer and restarts the time count.

  [S39] The threshold determination unit 12-1b determines whether or not there is an update processing stop request from an upper application or the like. If there is an update process stop request, the process ends. If not, the process returns to step S34.

  As described above, in the first embodiment, the detection threshold for the random access signal is variably set based on the completion rate. Thereby, since an appropriate detection threshold can be set flexibly according to the communication environment between the mobile station Ms and the radio base station Bs, it is possible to suppress erroneous detection of random access signals.

  Next, a second embodiment will be described. In the second embodiment, the detection threshold is variably set according to the level measurement value. FIG. 12 is a diagram illustrating a configuration example of a random access signal processing unit. The random access signal processing unit 10-2 includes a correlation calculation processing unit 11 and a detection processing unit 12-2. The detection processing unit 12-2 includes a level measurement unit 12-2a, a threshold value determination unit 12-2b, and a determination unit 12-2c.

  The level measurement unit 12-2a measures the reception level or interference level of the uplink reception data. The threshold value determination unit 12-2b has a threshold value table described later, and determines a detection threshold value based on the level measurement result registered in the threshold value table.

  The determination unit 12-2c uses the detection threshold determined by the threshold determination unit 12-2b, and determines that the random access signal is detected if the reception level of the random access signal is equal to or higher than the detection threshold.

  FIG. 13 shows a threshold table. The threshold table T2 is a table in which the correspondence relationship between the measurement level and the detection threshold is registered. The detection threshold is uniquely determined based on the registered contents of the threshold table T2.

  FIG. 14 is a diagram showing the relationship between the detection threshold and the measurement level. The vertical axis represents the detection threshold, and the horizontal axis represents the measurement level. In the threshold value determination based on the measurement level, if the measurement level is outside the target level range in the design, erroneous detection increases.

  Therefore, in order to avoid erroneous detection, the threshold value table T2 is set so that the detection threshold value becomes higher when the measurement level is outside the target level range in the design as shown in the graph g2. Is set.

  FIG. 15 is a diagram showing a detection threshold update operation flow. The detection threshold update process described below is continued until a request for stopping the update process is received from the upper application to the wireless communication apparatus 1-1.

[S41] The threshold determination unit 12-2b determines whether or not there is a detection threshold update processing start request from an upper application or the like. If there is an update processing start request, the process goes to step S42.
[S42] The level measurement unit 12-2a initializes the measurement level and starts level measurement.

[S43] The threshold determination unit 12-2b initializes a threshold update timer and starts time counting.
[S44] The threshold value determination unit 12-2b determines whether or not the timer value is equal to or greater than the update period. If the timer value is greater than or equal to the update period, the process goes to step S45.

[S45] The level measurement unit 12-2a performs level measurement.
[S46] The threshold determination unit 12-2b selects a detection threshold corresponding to the measurement level from the threshold table T2.

[S47] The level measurement unit 12-2a initializes the measurement level and restarts the level measurement.
[S48] The threshold determination unit 12-2b initializes the timer value of the threshold update timer and restarts the time count.

  [S49] The threshold determination unit 12-2b determines whether or not there is an update processing stop request from an upper application or the like. If there is an update process stop request, the process ends. If not, the process returns to step S44.

  As described above, in the second embodiment, the detection threshold of the random access signal is variably set based on the measurement level value. Thereby, since an appropriate detection threshold can be set flexibly according to the communication environment between the mobile station Ms and the radio base station Bs, it is possible to suppress erroneous detection of random access signals.

  Next, a third embodiment will be described. In the third embodiment, the detection threshold is a fixed value. Then, it is determined whether or not the random access signal exceeds the detection threshold value by a preset number of consecutive times, and the detection determination of the random access signal is performed.

  Before describing the details, power ramping performed by the mobile station Ms will be described. FIG. 16 is a diagram for explaining power ramping. The vertical axis is the reception level, and the horizontal axis is the time. In LTE, when the mobile station Ms transmits a random access signal, a power ramping process is performed in the mobile station Ms.

  In power ramping, when a random access signal is transmitted from the mobile station Ms, if there is no response from the radio base station Bs, transmission power is increased compared to the previous transmission at the transmission timing of the next random access signal. And transmitting.

A dotted line waveform in the figure indicates a response signal that is not transmitted to the mobile station Ms because the radio base station Bs cannot detect a random access signal.
In the figure, if the mobile station Ms does not receive a response signal within a certain period, the mobile station Ms increases the transmission power by ΔP and transmits a random access signal. Further, since the reception level of the random access signal exceeds the detection threshold in the third transmission, the random access signal is detected on the radio base station Bs side, and the response signal is transmitted to the mobile station Ms.

  Next, a random access signal processing unit in the third embodiment will be described. FIG. 17 is a diagram illustrating a configuration example of a random access signal processing unit. The random access signal processing unit 10-3 includes a correlation calculation processing unit 11 and a detection processing unit 12-3. The detection processing unit 12-3 includes a completion rate calculation unit 12-3a, a continuous reception number threshold determination unit 12-3b, a continuous threshold excess number counter 12-3c, and a determination unit 12-3d.

  The completion rate calculation unit 12-3a calculates the completion rate based on the above equation (1). Based on the calculation result of the completion rate, the continuous reception frequency threshold value determination unit 12-3b determines how many times the reception level of the random access signal exceeds the detection threshold value with respect to the currently set detection threshold value. A threshold value (continuous reception frequency threshold value) for the number of times that the continuous threshold value is exceeded, that is, whether the detection is a random access signal is determined.

  The continuous threshold value exceeding counter 12-3c counts how many times the reception level of the random access signal exceeds the detection threshold level continuously. The determination unit 12-3d uses the continuous reception number threshold determined by the continuous reception number threshold determination unit 12-3c. If the number of times that the random access signal exceeds the continuous threshold is equal to or greater than the continuous reception number threshold, the determination unit 12-3d It is determined that there is a detection.

When counting the number of times that the random access signal exceeds the continuous threshold, the count is performed at a timing in consideration of the transmission cycle by power ramping.
Further, the number of times that the continuous threshold value is exceeded is measured for each random access signal ID, and when the value reaches the continuous reception number threshold value, it is determined that the random access signal is detected for each random access signal ID. If it is not detected halfway, reset the counter and start counting again.

  Next, the operation of the random access signal processing unit 10-3 will be described using a flowchart. FIG. 18 is a diagram showing an operation flow of the random access signal processing unit. The operation described below is performed for each ID of the random access signal.

[S51] The correlation calculation processing unit 11 performs a correlation calculation process on the uplink received data.
[S52] The determination unit 12-3d determines whether or not the peak exceeds the detection threshold. If it does not exceed, go to step S53, otherwise go to step S54.

[S53] The continuous threshold value exceeding counter 12-3c clears the count value. The operation flow ends.
[S54] The determination unit 12-3d determines whether a random access signal is detected at the previous reception timing of the random access signal. If it is not detected at the previous reception timing, the process goes to step S55, and if it is detected, the process goes to step S56.

[S55] The continuous threshold value exceeding counter 12-3c starts counting. The operation flow ends.
[S56] The continuous threshold value exceeding counter 12-3c counts up the continuous threshold value exceeding number.

[S57] The determination unit 12-3d determines whether or not the count value is equal to or greater than the continuous reception frequency threshold. If it is equal to or greater than the continuous reception frequency threshold, the process goes to step S58, and if not, the process ends.
[S58] The determination unit 12-3d determines that a random access signal is detected.

[S59] The continuous threshold value exceeding counter 12-3c clears the count value.
FIG. 19 is a diagram showing a flow of adjusting the continuous reception frequency threshold.
[S61] The completion rate calculator 12-3a calculates a completion rate.

  [S62] The continuous reception frequency threshold value determination unit 12-3b determines whether or not the completion rate is within the target value range. If it is out of the target value range, go to step S64, and if it is within the target value range, go to step S63.

[S63] The continuous reception number threshold determination unit 12-3b maintains the current continuous reception number threshold. Go to step S67.
[S64] The continuous reception frequency threshold determination unit 12-3b determines whether the completion rate is higher than the target value range. If so, go to step S65; otherwise, go to step S66.

[S65] The continuous reception number threshold determination unit 12-3b subtracts 1 from the continuous reception number threshold (if the original continuous reception number threshold is 1, it remains as it is).
[S66] The continuous reception number threshold determination unit 12-3b adds 1 to the continuous reception number threshold.

[S67] The completion rate calculator 12-3a initializes the number of successful RACH message # 3 receptions and the number of RACH message # 2 transmissions, and restarts counting.
[S68] The continuous reception number threshold determination unit 12-3b initializes the timer value of the threshold update timer and restarts the time count.

  As described above, in determining the continuous reception frequency threshold, the target completion rate is determined within a certain range (target value ± several%), and the reception frequency is increased or decreased until the range is satisfied. However, in order to respond to changes in the surrounding environment, the completion rate is periodically checked and the threshold for the continuous reception number is adjusted.

  As described above, in the third embodiment, the continuous reception frequency threshold is determined based on the completion rate. Then, the number of times that the received random access signal level exceeds the continuous threshold value is measured with respect to the fixed level detection threshold value, and if the number of times the continuous threshold value is exceeded is equal to or greater than the continuous reception number threshold value, it is determined that the random access signal is detected. Made the configuration. Thereby, detection accuracy can be improved, and it becomes possible to suppress erroneous detection of random access signals.

  Next, a fourth embodiment will be described. In the third embodiment, the continuous reception frequency threshold is determined based on the completion rate, but in the fourth embodiment, the continuous reception frequency threshold is determined based on the measurement level value.

  FIG. 20 is a diagram illustrating a configuration example of a random access signal processing unit. The random access signal processing unit 10-4 includes a correlation calculation processing unit 11 and a detection processing unit 12-4. The detection processing unit 12-4 includes a level measurement unit 12-4a, a continuous reception number threshold determination unit 12-4b, a continuous threshold excess number counter 12-4c, and a determination unit 12-4d.

  The level measurement unit 12-4a measures the reception level or interference level of the uplink reception data. Based on the result of level measurement, the continuous reception frequency threshold value determination unit 12-4b is random if the reception level of the random access signal continuously exceeds the detection threshold value with respect to the currently set detection threshold value. A threshold for the number of continuous receptions for determining whether an access signal is detected is determined.

  The continuous threshold exceeded number counter 12-4c counts how many times the reception level of the random access signal exceeds the detection threshold level continuously. The determination unit 12-4d uses the continuous reception number threshold determined by the continuous reception number threshold determination unit 12-4b, and if the number of times that the random access signal exceeds the continuous threshold is equal to or greater than the continuous reception number threshold, It is determined that there is a detection.

  FIG. 21 shows a threshold table. The threshold table T3 is a table in which the correspondence relationship between the measurement level and the continuous reception frequency threshold is registered. The continuous reception frequency threshold is uniquely determined based on the registered contents of the threshold table T3.

  FIG. 22 is a diagram showing the relationship between the continuous reception frequency threshold and the measurement level. The vertical axis represents the detection threshold, and the horizontal axis represents the measurement level. In determining the threshold for the number of consecutive receptions based on the measurement level, if the measurement level is outside the target level range in the design, false detection increases.

  Therefore, in order to avoid erroneous detection, in the threshold value table T3, as shown in the graph g3, when the measurement level is outside the target level range in the design, the continuous reception frequency threshold value is increased. A value is set for.

  Here, an example of setting the continuous reception frequency threshold will be described. For example, when the false detection probability at the measurement level A is 0.1%, the false detection probability at the measurement level B is 1%, and the false detection probability at the measurement level C is 10%, the system is “3GPP TS36.104 ( (Ver8.11.0) 8.4.1 PRACH False alarm probability ”As specified in the case of setting the target to be a false detection probability of 0.1% or less.

  The detection process of the random access signal depends only on the instantaneous reception data at the reception processing timing, and the past reception data is not combined and used. For this reason, the probability of consecutive false detections when continuously received can be considered to be obtained by multiplying the false detection probability at each reception opportunity by the number of consecutive receptions.

  In other words, in an environment with many false detections, it is possible to reduce the false detection probability by considering the continuous reception result.Considering this property, the number of consecutive receptions is less than the target false detection probability. To decide.

  In the case of the above example, in order to satisfy the target false detection probability of 0.1%, it is necessary to perform continuous reception once at measurement level A, twice at measurement level B, and three times at measurement level C. This value is registered in the threshold value table T3 in FIG.

  Note that, as in the third embodiment, when the number of times that the random access signal exceeds the continuous threshold is counted, it is counted at a timing that considers the transmission cycle by power ramping.

  For each random access signal ID, the number of times that the continuous threshold value is exceeded is measured, and when the value reaches the continuous reception frequency threshold value, it is determined that a random access signal has been detected. If it is not detected halfway, reset the counter and start counting again.

  FIG. 23 is a diagram showing an operation flow for updating the continuous reception frequency threshold. The update process of the continuous reception frequency threshold shown below is continued until a request for stopping the update process is received from the upper application to the wireless communication apparatus 1-1.

  [S71] The continuous reception number threshold determination unit 12-4b determines whether or not there is a continuous reception number threshold update processing start request from a higher-level application or the like. If there is an update processing start request, the process goes to step S72.

[S72] The level measurement unit 12-4a initializes the measurement level and starts level measurement.
[S73] The continuous reception number threshold determination unit 12-4b initializes a threshold update timer and starts time counting.

[S74] The continuous reception frequency threshold determination unit 12-4b determines whether or not the timer value is equal to or greater than the update period. If the timer value is greater than or equal to the update cycle, the process goes to step S75.
[S75] The level measurement unit 12-4a performs level measurement.

[S76] The continuous reception frequency threshold determining unit 12-4b selects the continuous reception frequency threshold corresponding to the measurement level from the threshold table T3.
[S77] The level measurement unit 12-4a initializes the measurement level and restarts the level measurement.

[S78] The continuous reception number threshold determination unit 12-4b initializes the timer value of the threshold update timer and restarts the time count.
[S79] The continuous reception frequency threshold value determination unit 12-4b determines whether or not there is an update process stop request from an upper application or the like. If there is an update process stop request, the process ends. If not, the process returns to step S74.

  As described above, in the fourth embodiment, the continuous reception frequency threshold is determined based on the measurement level value. Then, the number of times that the received random access signal level exceeds the continuous threshold value is measured with respect to the fixed level detection threshold value, and if the number of times the continuous threshold value is exceeded is equal to or greater than the continuous reception number threshold value, it is determined that the random access signal is detected. Made the configuration. Thereby, detection accuracy can be improved, and it becomes possible to suppress erroneous detection of random access signals.

Next, a fifth embodiment will be described. The fifth embodiment corresponds to the random access signal detection operation described above with reference to FIG.
FIG. 24 is a diagram illustrating a configuration example of a random access signal processing unit. The random access signal processing unit 10-5 includes a correlation calculation processing unit 11 and a detection processing unit 12-5. The detection processing unit 12-5 includes a completion rate calculation unit 12-5a, a continuous reception number threshold determination unit 12-5b, a continuous threshold excess number counter 12-5c, a reception result storage unit 12-5d, and a determination unit 12-5e. .

The reception result storage unit 12-5d has the function of the storage unit 1-1a in FIG. 1, and the determination unit 12-5e has the function of the detection determination unit 1-1b in FIG.
The completion rate calculation unit 12-5a calculates the completion rate based on the above equation (1). Based on the calculation result of the completion rate, the continuous reception frequency threshold value determination unit 12-5b determines how many times the reception level of the random access signal exceeds the detection threshold value with respect to the currently set detection threshold value. A threshold for the number of consecutive receptions for determining whether a random access signal is detected is determined.

  The continuous threshold exceeded number counter 12-5c counts how many times the level of the received random access signal exceeds the detection threshold level continuously. The reception result storage unit 12-5d stores the ID of the random access signal and the reception timing when the random access signal is received.

  The determination unit 12-5e uses the continuous reception number threshold determined by the continuous reception number threshold determination unit 12-5b, and if the number of times that the random access signal exceeds the continuous threshold is equal to or greater than the continuous reception number threshold, It is determined that there is a detection.

  In the reception result storage unit 12-5d, the timing when data is stored is after the determination processing of the random access signal is completed in the determination unit 12-5e, and the random access signal detected as the previous reception result is stored. The ID and its reception timing are stored. This result is stored for a certain period, erased at a timing when it is no longer used by the determination unit 12-5e, and a new reception result is overwritten.

  Here, the identification process of the mobile station Ms will be described. The random access signal ID transmitted from the mobile station Ms during power ramping of the random access signal is not always the same and may be different.

  Therefore, the determination unit 12-5e performs a process (mobile station specifying process) for determining whether or not the random access signals are transmitted from the same mobile station Ms. Whether or not the received random access signal is transmitted from the same mobile station Ms is determined using the fact that the distance between the radio base station Bs and the mobile station Ms hardly changes.

  Even if the mobile station Ms transmits with different IDs from the same mobile station Ms during power ramping, the distance between the radio base station Bs and the mobile station Ms hardly changes. This means that the difference between the reception timing t1 of the random access signal shown in FIG. 5 and the processing reference timing tr in the wireless communication apparatus 1-1 hardly changes.

  Accordingly, the determination unit 12-5e compares the difference between the processing reference timing calculated for the newly detected random access signal and the difference of the previously detected random access signal. If there is something that can be regarded as the same value (a range may be provided in consideration of a measurement error due to a wireless environment), it is recognized that a random access signal is transmitted from the same mobile station Ms.

  Next, the operation of the random access signal processing unit 10-5 will be described using a flowchart. FIG. 25 is a diagram showing an operation flow of the random access signal processing unit. The operation described below is performed for each ID of the random access signal.

[S80] The correlation calculation processing unit 11 performs a correlation calculation process on the uplink received data.
[S81] The determination unit 12-5e determines whether or not the peak exceeds the detection threshold. If it does not exceed, go to step S89, otherwise go to step S82.

  [S82] The determination unit 12-5e performs mobile station identification processing. That is, the difference between the reception timing of the random access signal received last time and the difference between the processing reference timing inside the apparatus, the reception timing of the random access signal received this time, and the processing reference timing. The second difference is obtained and compared. If the comparison result can be regarded as a match, the mobile station Ms is identified by recognizing that a random access signal is transmitted from the same mobile station Ms.

[S83] The determination unit 12-5e determines whether there is a detection that seems to be the same mobile station Ms at the previous reception timing. If there is, go to step S85, otherwise go to step S84.
[S84] The continuous threshold value exceeding counter 12-5c clears the count value and then starts counting. Go to step S89.

[S85] The continuous threshold value exceeding counter 12-5c counts up the continuous threshold value exceeding number.
[S86] The determination unit 12-5e determines whether or not the count value is equal to or greater than the continuous reception frequency threshold. If it is equal to or greater than the continuous reception frequency threshold value, go to step S87, otherwise go to step S89.

[S87] The determination unit 12-5e determines that a random access signal is detected.
[S88] The continuous threshold value exceeding counter 12-5c clears the count value.
[S89] The reception result storage unit 12-5d stores the reception result.

  As described above, in the fifth embodiment, the mobile station Ms is identified from the difference information between the random access signal reception timing and the processing reference timing. In addition, the continuous reception frequency threshold is determined based on the completion rate.

  Then, the number of times that the continuous threshold is exceeded with respect to the detection threshold of the random access signal transmitted from the specified mobile station Ms is measured. Made the configuration.

  Thereby, it is possible to appropriately specify the mobile station Ms that has transmitted the random access signal, and to suppress erroneous detection of the random access signal transmitted from the specified mobile station Ms.

  Next, a sixth embodiment will be described. The operation of the sixth embodiment is basically the same as that of the fifth embodiment. In the fifth embodiment, the continuous reception frequency threshold is determined based on the completion rate. However, in the sixth embodiment, the continuous reception frequency threshold is determined based on the measurement level value.

FIG. 26 is a diagram illustrating a configuration example of a random access signal processing unit. The random access signal processing unit 10-6 includes a correlation calculation processing unit 11 and a detection processing unit 12-6.
The detection processing unit 12-6 includes a level measurement unit 12-6a, a continuous reception number threshold determination unit 12-6b, a continuous threshold excess number counter 12-6c, a reception result storage unit 12-6d, and a determination unit 12-6e.

  The level measurement unit 12-6a measures the reception level or interference level of the uplink reception data. Based on the level measurement result, the continuous reception frequency threshold value determination unit 12-6b randomly determines the number of times the reception level of the random access signal exceeds the detection threshold value with respect to the currently set detection threshold value. A threshold for the number of continuous receptions for determining whether an access signal is detected is determined.

  The continuous threshold exceeded number counter 12-6c counts how many times the level of the received random access signal is continuously exceeded with respect to the level of the detection threshold. The reception result storage unit 12-6d stores the ID of the random access signal and the reception timing when the random access signal is received.

  The determination unit 12-6e uses the continuous reception number threshold determined by the continuous reception number threshold determination unit 12-6b, and if the number of times that the random access signal exceeds the continuous threshold is equal to or greater than the continuous reception number threshold, It is determined that there is a detection.

Since the operation is the same as that of the fifth embodiment except that the continuous reception frequency threshold is determined based on the measurement level, the description is omitted.
As described above, in the sixth embodiment, the mobile station Ms is specified from the difference information between the random access signal reception timing and the processing reference timing. Further, the continuous reception frequency threshold is determined based on the measurement level value.

  Then, the number of times that the continuous threshold is exceeded with respect to the detection threshold of the random access signal transmitted from the specified mobile station Ms is measured. Made the configuration.

  Thereby, it is possible to appropriately recognize the mobile station Ms that has transmitted the random access signal, and to suppress erroneous detection of the random access signal transmitted from the mobile station Ms.

  Next, a seventh embodiment will be described. In the seventh embodiment, the amount of power increase due to power ramping of the mobile station Ms is recognized, and the processing time required for detection determination of the random access signal is shortened.

  FIG. 27 is a diagram illustrating a configuration example of a random access signal processing unit. The random access signal processing unit 10-7 includes a correlation calculation processing unit 11 and a detection processing unit 12-7. The detection processing unit 12-7 includes a reception result storage unit 12-7a and a determination unit 12-7b.

  The reception result storage unit 12-7a stores the ID, reception timing, and reception level of the random access signal. The determination unit 12-7b calculates the difference between the reception level of the random access signal received this time exceeding the detection threshold level and the reception level of the random access signal received last time. When this difference can be regarded as an increase in power due to power ramping performed on the mobile station Ms side, it is determined that a random access signal has been detected.

  Next, the operation of the random access signal processing unit 10-7 will be described using a flowchart. FIG. 28 is a diagram illustrating an operation flow of the random access signal processing unit. The operation described below is performed for each ID of the random access signal.

[S91] The correlation calculation processing unit 11 performs a correlation calculation process on the uplink received data.
[S92] The determination unit 12-7b determines whether or not the peak exceeds the detection threshold. If it does not exceed, go to step S96, otherwise go to step S93.

[S93] The determination unit 12-7b calculates the power difference between the random access signal received last time and the random access signal received this time.
[S94] The determination unit 12-7b determines whether or not the power difference is within a range of ΔP ± α (α is a margin). If the power difference is within the set range, go to step S95, and if not within the set range, go to step S96.

[S95] The determination unit 12-7b determines that a random access signal is detected.
[S96] The reception result storage unit 12-7a stores the reception result.
As described above, in the seventh embodiment, when the currently received random access signal is equal to or greater than the detection threshold, the determination unit 12-7b determines the reception level of the currently received random access signal and the previously received random access. The difference between the signal reception level and the signal reception level is calculated. The reception level of the random access signal received last time is stored in the reception result storage unit 12-7a.

  When the power difference is recognized as an increase in ΔP, which is an increase in power in power ramping, it is recognized as a random access signal transmitted by power ramping from the same mobile station Ms, and the random access signal is detected. judge. In the above description, the increase in power is set to ΔP ± α in consideration of propagation loss and measurement error due to the wireless environment.

  Here, in the first to sixth embodiments described above, it is determined that there is detection when the reception level of the random access signal exceeds the detection threshold, or random access signals exceeding the detection threshold are continuously used. When it is received, the operation of determining that there is a detection is performed.

  In this case, it may take time from the start of transmission of the random signal from the mobile station Ms to the detection of the random access signal. On the other hand, in the seventh embodiment, when it is recognized that the currently received random access signal exceeding the detection threshold is transmitted from the mobile station Ms with increased power in the power ramping, the random access signal is immediately detected. It is determined that there is.

  Thereby, it is possible to suppress erroneous detection of the random access signal, and further, it is possible to shorten the response time from the transmission start of the random access signal to the response signal transmission.

Next, an eighth embodiment will be described. In the eighth embodiment, two detection thresholds are provided to perform a random access signal detection process.
FIG. 29 is a diagram illustrating a configuration example of a random access signal processing unit. The random access signal processing unit 10-8 includes a correlation calculation processing unit 11 and a detection processing unit 12-8. The detection processing unit 12-8 includes a reception result storage unit 12-8a and a determination unit 12-8b.

  The reception result storage unit 12-8a stores the ID, reception timing, and reception level of the random access signal. The determination unit 12-8b has a first detection threshold and a second detection threshold having a level lower than the first detection threshold.

When the random access signal received this time exceeds the first detection threshold level, it is immediately determined that the random access signal has been detected.
Further, when the random access signal received this time does not exceed the level of the first detection threshold but exceeds the level of the second detection threshold, the same operation as that of the seventh embodiment is performed.

  That is, the difference between the reception level of the random access signal received this time and the reception level of the random access signal received last time is calculated, and this difference can be regarded as an increase in power due to power ramping performed on the mobile station Ms side. Determines that a random access signal is detected.

  FIG. 30 is a diagram showing detection threshold values. The determination unit 12-8b has two detection threshold values. The detection threshold th2 (second detection threshold) is, for example, a level equivalent to the detection threshold used in the seventh embodiment. The detection threshold th1 (first detection threshold) is a threshold having a level larger than the detection threshold th2.

  When the reception level of the random access signal is equal to or higher than the detection threshold th1, it is determined that the mobile station Ms is surely transmitting the random access signal, it is immediately determined that the random access signal is detected, and the response Shift to signal transmission processing.

  In addition, when the reception level of the random access signal is less than the detection threshold th1 and is equal to or higher than the detection threshold th2, the random access signal may be transmitted from the mobile station Ms. Therefore, the same processing as in the seventh embodiment is performed. To implement.

  Next, the operation of the random access signal processing unit 10-8 will be described using a flowchart. FIG. 31 is a diagram showing an operation flow of the random access signal processing unit. The operation described below is performed for each ID of the random access signal.

[S101] The correlation calculation processing unit 11 performs a correlation calculation process on the uplink received data.
[S102] The determination unit 12-8b determines whether the peak exceeds the detection threshold th1. If not, go to step S103, otherwise go to step S106.

[S103] The determination unit 12-8b determines whether the peak exceeds the detection threshold th2. If not, go to step S107, otherwise go to step S104.
[S104] The determination unit 12-8b calculates a power difference between the random access signal received last time and the random access signal received this time.

  [S105] The determination unit 12-8b determines whether the power difference is within a range of ΔP ± α. If the power difference is within the set range, go to step S106, and if not within the set range, go to step S107.

[S106] The determination unit 12-8b determines that a random access signal is detected.
[S107] The reception result storage unit 12-8a stores the reception result.
As described above, in the eighth embodiment, two detection thresholds th1 and th2 are provided, and when the received random access signal exceeds the detection threshold th1, it is immediately determined that the random access signal is detected.

  If the level of the detection threshold th1 does not exceed the level of the detection threshold th2, the difference between the reception level of the random access signal received this time and the reception level of the random access signal received last time is calculated. When this difference can be regarded as an increase in power due to power ramping performed on the mobile station Ms side, it is determined that a random access signal is detected.

  Thereby, it is possible to suppress erroneous detection of the random access signal, and further, it is possible to shorten the response time from the transmission start of the random access signal to the response signal transmission.

  Note that, for example, the mobile station Ms that has returned from shadowing may already have transmitted a signal with power that is sufficient to communicate with the radio base station Bs. Therefore, by providing the detection threshold th1, a response signal can be transmitted immediately to such a mobile station Ms, and the response time can be shortened.

  Next, a ninth embodiment will be described. In the ninth embodiment, the mobile station specifying process described in the fifth embodiment is performed, and the operation of the seventh embodiment is executed for the specified mobile station Ms.

  FIG. 32 is a diagram illustrating a configuration example of a random access signal processing unit. The random access signal processing unit 10-9 includes a correlation calculation processing unit 11 and a detection processing unit 12-9. The detection processing unit 12-9 includes a reception result storage unit 12-9a and a determination unit 12-9b.

  The reception result storage unit 12-9a stores the ID, reception timing, and reception level of the random access signal. The determination unit 12-9b performs a process for identifying the mobile station Ms from the difference information between the reception timing of the random access signal and the processing reference timing. Then, when it is recognized that the random access signal received this time exceeding the detection threshold is transmitted to the identified mobile station Ms with increased power in power ramping, it is immediately determined that the random access signal has been detected. To do.

  Next, the operation of the random access signal processing unit 10-9 will be described using a flowchart. FIG. 33 is a diagram showing an operation flow of the random access signal processing unit. The operation described below is performed for each ID of the random access signal.

[S111] The correlation calculation processing unit 11 performs a correlation calculation process on the uplink received data.
[S112] The determination unit 12-9b determines whether or not the peak exceeds the detection threshold. If not, go to step S118, otherwise go to step S113.

[S113] The determination unit 12-9b performs a process for identifying the mobile station Ms.
[S114] The determination unit 12-9b determines whether there is a detection that seems to be the same mobile station Ms at the previous reception timing. If there is, go to step S115, otherwise go to step S118.

[S115] The determination unit 12-9b calculates a power difference between the previously received random access signal and the currently received random access signal.
[S116] The determination unit 12-9b determines whether the power difference is within a range of ΔP ± α. If the power difference is within the set range, go to step S117, and if not within the set range, go to step S118.

[S117] The determination unit 12-9b determines that a random access signal is detected.
[S118] The reception result storage unit 12-9a stores the reception result.
As described above, in the ninth embodiment, the mobile station Ms is identified from the difference information between the random access signal reception timing and the processing reference timing.

  Then, when it is recognized that the random access signal received this time exceeding the detection threshold is transmitted to the identified mobile station Ms with increased power in power ramping, it is immediately determined that the random access signal has been detected. It was set as the structure to do.

  Thereby, it is possible to suppress erroneous detection of the random access signal, and further, it is possible to shorten the response time from the transmission start of the random access signal to the response signal transmission.

  Next, a tenth embodiment will be described. The tenth embodiment performs the determination process based on the two detection thresholds described in the eighth embodiment and the mobile station specifying process described in the fifth embodiment, and further specifies the specified mobile station Ms. On the other hand, the operation of the seventh embodiment is executed.

  FIG. 34 is a diagram illustrating a configuration example of a random access signal processing unit. The random access signal processing unit 10-10 includes a correlation calculation processing unit 11 and a detection processing unit 12-10. The detection processing unit 12-10 includes a reception result storage unit 12-10a and a determination unit 12-10b.

  The reception result storage unit 12-10a stores the ID, reception timing, and reception level of the random access signal. The determination unit 12-10b has detection thresholds th1 and th2. If the random access signal received this time exceeds the level of the detection threshold th1, it is determined that the random access signal has been detected.

  Further, when the random access signal received this time does not exceed the level of the detection threshold th1 but exceeds the level of the detection threshold th2, the mobile station Ms determines from the difference information between the reception timing of the random access signal and the processing reference timing. Perform specific processing. Then, when it is recognized that the random access signal received this time exceeding the detection threshold is transmitted to the identified mobile station Ms with increased power in power ramping, it is immediately determined that the random access signal has been detected. To do.

  Next, the operation of the random access signal processing unit 10-10 will be described using a flowchart. FIG. 35 is a diagram showing an operation flow of the random access signal processing unit. The operation described below is performed for each ID of the random access signal.

[S121] The correlation calculation processing unit 11 performs a correlation calculation process on the uplink received data.
[S122] The determination unit 12-10b determines whether or not the peak exceeds the detection threshold th1. If not, go to step S123, otherwise go to step S128.

[S123] The determination unit 12-10b determines whether the peak exceeds the detection threshold th2. If not, go to step S129, otherwise go to step S124.
[S124] The determination unit 12-10b performs a process for identifying the mobile station Ms.

  [S125] The determination unit 12-10b determines whether there is a detection that seems to be the same mobile station Ms at the previous reception timing. If there is, go to step S126, otherwise go to step S129.

[S126] The determination unit 12-10b calculates a power difference between the random access signal received last time and the random access signal received this time.
[S127] The determination unit 12-10b determines whether the power difference is within a range of ΔP ± α. When the power difference is within the setting range, the process goes to step S128, and when it is not within the setting range, the process goes to step S129.

[S128] The determination unit 12-10b determines that a random access signal is detected.
[S129] The reception result storage unit 12-10a stores the reception result.
As described above, in the tenth embodiment, when the random access signal received this time exceeds the level of the detection threshold th1, it is determined that the random access signal has been detected.

  Further, when the random access signal received this time does not exceed the level of the detection threshold th1 but exceeds the level of the detection threshold th2, the mobile station Ms determines from the difference information between the reception timing of the random access signal and the processing reference timing. Perform specific processing. Then, when it is recognized that the random access signal received this time exceeding the detection threshold is transmitted to the identified mobile station Ms with increased power in power ramping, it is immediately determined that the random access signal has been detected. To do.

  Thereby, it is possible to suppress erroneous detection of the random access signal, and further, it is possible to shorten the response time from the transmission start of the random access signal to the response signal transmission.

Next, the hardware configuration of the radio base station Bs and the mobile station Ms will be described. FIG. 36 is a diagram illustrating a hardware block configuration example of the baseband signal processing unit in the radio base station.
The baseband signal processing unit 30 in the radio base station Bs includes an FPGA (Field-Programmable Gate Array) / ASIC (Application Specific Integrated Circuit) 31, a switch 32, a CPU (Central Processing Unit) / MPU (Micro Processing Unit) 33, DSPs (Digital Signal Processors) 33-1 to 33-n and memories 34-1 to 34-m are provided.

The FPGA / ASIC 31 performs baseband signal processing and interface processing with other processing units. The CPU / MPU 33 performs control related to baseband signal processing.
The DSPs 33-1 to 33-n perform baseband processing such as digital modulation / demodulation processing. The memories 34-1 to 34-m are used for temporarily saving processing results. The switch 32 connects the FPGA / ASIC 31, the CPU / MPU 33, and the DSPs 33-1 to 33-n.

The function of the wireless communication apparatus 1-1 is mainly realized by the DSPs 33-1 to 33-n, and the memories 34-1 to 34-m are used for storing the reception results.
FIG. 37 is a diagram illustrating a hardware block configuration example of a mobile station. The mobile station Ms includes a baseband signal processing unit 40, a D / A conversion unit 4a-1, a transmission RF unit 4a-2, a reception RF unit 4b-1, and an A / D conversion unit 4b-2. The baseband signal processing unit 40 includes a transmission unit 41, a control unit 42, and a reception unit 43.

  In the transmission process, the transmission unit 41 performs digital modulation of transmission data. The D / A converter 4a-1 converts a digital signal into an analog signal. The transmission RF unit 4a-2 up-converts the analog baseband signal to a radio frequency band. The amplifier-converted signal is transmitted to the radio base station through the antenna.

  In the reception process, the signal transmitted from the radio base station is input through the antenna, and the reception RF unit 4b-1 down-converts the radio frequency band to the baseband signal. The A / D converter 4b-2 converts the down-converted analog signal into a digital signal. The receiving unit 43 performs detection / demodulation processing of the digital baseband signal. The control unit 42 controls the transmission unit 41 and the reception unit 43.

  As described above, according to the present technology, it is possible to reduce erroneous detection of a random access signal, and it is possible to use radio resources more effectively than in the past. As a result, it is possible to improve the throughput characteristics of the entire system.

  As mentioned above, although embodiment was illustrated, the structure of each part shown by embodiment can be substituted by the other thing which has the same function. Moreover, other arbitrary structures and processes may be added.

DESCRIPTION OF SYMBOLS 1 Wireless communication system 1-1 Wireless communication apparatus 1-1a Storage part 1-1b Detection determination part Ms Mobile station Bs Wireless base station

Claims (14)

A mobile station that transmits an access signal for establishing a radio link;
A radio base station having a radio communication device including a storage unit that stores the reception timing of the access signal, and a detection determination unit that performs detection determination of the access signal;
With
The detection determination unit
A first difference that is a difference between the reception timing of the access signal received last time and a processing reference timing; a second difference that is a difference between the reception timing of the access signal received this time and the processing reference timing; Compare for
According to the comparison result, identify the mobile station,
With respect to the access signal transmitted from the identified mobile station, it is determined that the access signal is detected according to the number of continuous receptions of the access signal exceeding a threshold level.
A wireless communication system. The wireless communication device
Measures the number of transmissions of a response signal transmitted to the mobile station when the access signal is received and the number of successful receptions of a message signal transmitted to the radio base station when the mobile station receives the response signal A completion rate calculating unit that calculates a completion rate that is a ratio between the number of transmissions and the number of successful receptions;
Based on the completion rate, and the continuous reception frequency threshold determination unit that determines the consecutive number of times of receiving threshold,
The wireless communication system according to claim 1, further comprising: The wireless communication device
A level measuring unit for measuring the level of a signal transmitted from the mobile station;
A threshold table storage unit in which a correspondence relationship between a measurement level and a continuous reception frequency threshold is registered;
Based on the measured level by the level measuring unit, further have a, a continuous reception frequency threshold determination unit configured to determine the continuous reception frequency threshold specified from the registered correspondence to the threshold table storage unit,
The detection determination unit determines that the access signal is detected when the number of continuous receptions of the access signal exceeding the threshold level exceeds the continuous reception number threshold determined by the continuous reception number threshold determination unit. The wireless communication system according to claim 1. In a wireless communication device,
A storage unit for storing the reception timing of an access signal transmitted from the mobile station for establishing a radio link;
A detection determination unit that performs detection determination of the access signal;
With
The detection determination unit
A first difference that is a difference between the reception timing of the access signal received last time and a processing reference timing; a second difference that is a difference between the reception timing of the access signal received this time and the processing reference timing; Compare for
According to the comparison result, identify the mobile station,
With respect to the access signal transmitted from the identified mobile station, it is determined that the access signal is detected according to the number of continuous receptions of the access signal exceeding a threshold level.
A wireless communication apparatus. In the wireless communication method,
Stores the reception timing of the access signal sent from the mobile station to establish a radio link,
A first difference that is a difference between the reception timing of the access signal received last time and a processing reference timing; a second difference that is a difference between the reception timing of the access signal received this time and the processing reference timing; Compare for
According to the comparison result, identify the mobile station,
With respect to the access signal transmitted from the identified mobile station, it is determined that the access signal is detected according to the number of continuous receptions of the access signal exceeding a threshold level.
A wireless communication method. When an access signal transmitted from a mobile station for establishing a radio link is received, the number of times a response signal is transmitted to the mobile station and when the mobile station receives the response signal A completion rate calculating unit that measures the number of successful receptions of a message signal and calculates a completion rate that is a ratio of the number of transmissions and the number of successful receptions;
A threshold level determination unit that determines a threshold level based on the completion rate;
When the access signal exceeding the determined threshold level is received, a detection determination unit that determines that the access signal is detected;
A wireless communication apparatus comprising: A level measurement unit for measuring the level of a signal transmitted from the mobile station;
A threshold level determination unit that determines the threshold level based on the measurement level;
Transmitted from the mobile station, to the access signal for establishing a wireless link, in accordance with the consecutive number of times of reception of the access signal exceeding the determined threshold value level, it detected there and determines detection of the access signal A determination unit;
A wireless communication apparatus comprising: A continuous reception number threshold determining unit for determining a continuous reception number threshold;
When an access signal transmitted from a mobile station for establishing a radio link has a continuous reception count exceeding the threshold level of the access signal equal to or greater than the continuous reception count threshold, it is determined that the access signal is detected. A detection determination unit to perform,
A wireless communication apparatus comprising: Measures the number of transmissions of a response signal transmitted to the mobile station when the access signal is received and the number of successful receptions of a message signal transmitted to the radio base station when the mobile station receives the response signal. A completion rate calculating unit that calculates a completion rate that is a ratio between the number of transmissions and the number of successful receptions;
The continuous reception number threshold determination unit determines the continuous reception number threshold based on the completion rate;
The wireless communication apparatus according to claim 8. A level measuring unit for measuring the level of a signal transmitted from the mobile station ;
A threshold table storage unit in which a correspondence relationship between a measurement level and the continuous reception frequency threshold is registered;
Further comprising
The continuous reception number threshold determination unit determines the continuous reception number threshold specified from the correspondence registered in the threshold table storage unit based on a measurement level by the level measurement unit ;
The wireless communication apparatus according to claim 8. A storage unit for storing a reception level and a reception timing of an access signal transmitted from a mobile station for establishing a radio link;
A difference between the reception level of the access signal received this time exceeding a threshold level and the reception level of the access signal received last time is calculated, and the difference is an increase in power due to power ramping performed on the mobile station side. The access signal is detected and the response signal to the mobile station is transmitted to the detected access signal, and the difference is an increase in power due to power ramping performed on the mobile station side. If it cannot be considered, a detection determination unit that determines that the access signal is not detected and does not transmit a response signal to the mobile station for the access signal ;
A wireless communication apparatus comprising: The detection determination unit
A first threshold and a second threshold having a level lower than the first threshold;
If the access signal received this time exceeds the first threshold level, it is determined that the access signal is detected,
When the access signal received this time does not exceed the first threshold level but exceeds the second threshold level, the reception level of the access signal received this time and the access signal received last time When the difference with the reception level is calculated and the difference can be regarded as an increase in power due to power ramping performed on the mobile station side, it is determined that the access signal is detected,
The wireless communication apparatus according to claim 11. The detection determination unit
A first difference that is a difference between the reception timing of the access signal received last time and a processing reference timing; a second difference that is a difference between the reception timing of the access signal received this time and the processing reference timing; Compare for
According to the comparison result, identify the mobile station,
For the access signal transmitted from the identified mobile station, the difference between the reception level of the access signal received this time exceeding the threshold level and the reception level of the access signal received last time is calculated, and the difference is If it can be regarded as an increase in power due to power ramping performed on the mobile station side, it is determined that the access signal is detected,
The wireless communication apparatus according to claim 11. The detection determination unit
A first threshold and a second threshold having a level lower than the first threshold;
If the access signal received this time exceeds the first threshold level, it is determined that the access signal is detected,
When the access signal received this time does not exceed the first threshold level but exceeds the second threshold level,
A first difference that is a difference between the reception timing of the access signal received last time and a processing reference timing; a second difference that is a difference between the reception timing of the access signal received this time and the processing reference timing; Compare for
According to the comparison result, identify the mobile station,
For the access signal transmitted from the identified mobile station, a difference between the reception level of the access signal received this time and the reception level of the access signal received last time is calculated, and the difference is calculated as the mobile station If it can be regarded as an increase in power due to power ramping performed on the side, it is determined that the access signal is detected,
The wireless communication apparatus according to claim 11.

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