JP2010283510A - Communication apparatus, and communication quality measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain communication apparatus for calculating a CINR (Carrier to Interference and Noise power Ratio) more precisely than ever before. <P>SOLUTION: The communication apparatus including a communication system for repeating an identical frequency by cell or by sector includes: a control unit 4 for acquiring information on a pilot signal system used by an adjacency cell or adjacency sector from an adjacency base station being a base station managing the adjacency cell or adjacency sector; and a baseband portion 3 for measuring communication quality on the basis of a measurement result of signal power and interference power and information about a pilot signal system acquired. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication apparatus and a communication quality measurement method of a wireless communication system that repeatedly uses the same frequency band for each cell (or sector).

  In recent years, mobile WiMAX (Worldwide interoperability for Microwave Access), which is high-speed mobile communication, has attracted attention as a new communication network. In mobile WiMAX, high mobility is realized by constructing a multi-cell environment. In addition, communication using OFDMA (Orthogonal Frequency Division Multiple Access) is standardized in the uplink and downlink, and the frequency utilization efficiency is improved by repeatedly using the same frequency band in each cell and sector. Is realized. When the same frequency band is used repeatedly, interference occurs between cells, sectors, and users. In this system, measures are taken to suppress the influence (interference) by performing link adaptation such as adaptive modulation and power control. . In these technologies, control using a signal power-to-interference and noise power ratio (CINR), which is generally a measure of communication quality, is performed (see Non-Patent Document 1 below). ).

  In a system to which mobile WiMAX is applied, CINR is measured using a signal sequence known between a base station and a terminal station called a pilot signal. Also, in this system, a random sequence is used as a pilot signal, and when measuring CINR, first, based on the pilot signal, received signal power including interference power and noise power (total received signal power), interference power, The signal power not including noise power is obtained, and interference and noise power are calculated for each frequency by subtracting the signal power from the total received signal power. Then, the power (signal power, interference and noise power) calculated at each frequency is averaged with the assigned frequency bandwidth, and the CINR of each user is calculated based on each average value obtained as a result. Non-Patent Document 1 below also describes an example of a CINR averaging method.

  Patent Document 1 below discloses a technique for accurately estimating CINR using the similarity of adjacent subcarriers.

JP-A-2005-204307

IEEE P802.16Rev2 / D9, “Part16: Air Interface for Broadband Wireless Access Systems”, January 2009,

  However, when the conventional measurement method is used, there is a problem that CINR cannot be measured with high accuracy. Hereinafter, this reason will be described.

  For example, when a sufficient number of pilot signals cannot be secured in the time direction, the interference power measurement accuracy deteriorates, and accordingly, the CINR measurement accuracy deteriorates. In addition, when a sufficient number of pilot signals cannot be secured in the frequency direction, noise power measurement accuracy deteriorates, and accordingly, CINR measurement accuracy deteriorates.

  In a communication system using OFDMA such as the WiMAX system, the frequency band used by each user is changed over time in order to obtain a frequency diversity effect. As a result, the time for the same user to use the same frequency is shortened, and the pilot signal cannot be increased. Also in an actual WiMAX system uplink, CINR is calculated using the power (signal power, interference and noise power) of each frequency calculated using only two pilot signals transmitted at the same frequency. The code patterns of these two pilot signals are defined as pilot patterns. In the desired cell (the cell in which the communication device is accommodated) and the interference cell (such as a cell adjacent to the desired cell, communication in the cell causes interference of communication in the desired cell), a random pilot pattern ( When a random sequence is applied and the pilot patterns are orthogonal to each other, it is possible to separate an interference component from a signal including a noise component and an interference component. In other words, interference components cannot be separated if they are not orthogonal. Since the pilot signal is BPSK modulated and a pilot pattern is formed by two pilot signals at one frequency, there are two types of orthogonal patterns and two types of non-orthogonal patterns for one pilot pattern. . Therefore, the pilot patterns of all three or more cells and sectors are not orthogonal to each other. At a frequency where the pilot pattern is non-orthogonal, the interference component cannot be separated from the received signal. Therefore, the interference component is included in the signal component, and the interference power and the signal power cannot be measured correctly. As described above, CINR is calculated by averaging signal power, interference, and noise power calculated at each frequency, but the power calculation result at a frequency at which interference components cannot be separated as described above includes an error. Therefore, averaging is performed including this, and the obtained CINR has a large error.

  In addition, in the uplink of the WiMAX system, the terminal station performs communication only within the band assigned to the base station. Therefore, CINR is measured within this band. It is well known that noise has a Gaussian distribution with an average of 0. Therefore, noise power measurement is relatively easy when the number of samples is large. However, accurate noise power measurement becomes difficult when the allocated bandwidth is small and there are few samples. If the noise power cannot be accurately measured, the CINR calculation accuracy naturally deteriorates.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a communication device and a communication quality measurement method that calculate communication quality (CINR) with high accuracy.

  In order to solve the above-described problems and achieve the object, the present invention is a communication apparatus constituting a communication system that repeatedly uses the same frequency for each cell or sector, and manages adjacent cells or adjacent sectors Pilot signal sequence information acquisition means for acquiring information on pilot signal sequences used in adjacent cells or adjacent sectors from adjacent base stations that are base stations, measurement results of signal power and interference power in pilot signals, and the acquisition Communication quality measuring means for measuring the communication quality based on the pilot signal sequence information.

  According to the present invention, the communication apparatus obtains information on a pilot signal sequence used in an adjacent cell (or sector) managed by another surrounding base station, and the signal power in this information and the pilot signal and Since the communication quality is measured based on the measurement result of the interference power, the communication quality can be measured with higher accuracy than before.

FIG. 1 is a diagram illustrating an example of a communication system assumed by the communication apparatus according to the first embodiment. FIG. 2 is a diagram of a configuration example of the communication apparatus according to the first embodiment. FIG. 3 is a diagram illustrating a correspondence relationship between pilot patterns that can be used by the communication apparatus and orthogonal pilot patterns. FIG. 4 is a diagram illustrating an operation in which each base station acquires information on a pilot signal sequence used in another base station. FIG. 5 is a diagram illustrating an example of a functional block that performs CINR measurement in the baseband unit. FIG. 6 is a flowchart illustrating an example of determination processing performed by the interference determination unit. FIG. 7 is a diagram for explaining the CINR calculation operation in the averaging unit. FIG. 8 is a diagram for explaining the CINR calculation operation in the averaging unit. FIG. 9 is a diagram illustrating an example of a determination result in the interference determination unit. FIG. 10 is a diagram illustrating an example of a determination result in the interference determination unit. FIG. 11 is a diagram illustrating an example of a determination result in the interference determination unit. FIG. 12 is a diagram illustrating an example of a determination result in the interference determination unit. FIG. 13 is a diagram showing how a pilot signal sequence is scheduled. FIG. 14 is a diagram illustrating an operation in which each base station acquires information on a user use band in another base station.

  Embodiments of a communication apparatus and a communication quality measuring method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
In the present embodiment and each embodiment described later, as an example, an operation when measuring uplink communication quality (CINR), that is, an operation when a base station measures CINR will be described. However, the communication quality measurement operation described below can also be applied in the downlink direction.

  FIG. 1 is a diagram illustrating an example of a communication system assumed by the communication apparatus according to the present embodiment. As shown in the figure, in this embodiment, an interference source for communication between a base station whose communication quality (CINR) is to be measured and its communication partner (desired terminal # 0) is other than the desired sector in the sector cell (3 sectors). This will be described assuming that there are only two sectors. This is a limitation for simplifying the explanation and does not limit the invention itself. Interference terminals # 1 and # 2 with respect to desired sector # 0 perform communication by interfering terminals # 1 and # 2, respectively, and interfere with communication in desired sector # 0 (communication between base station and desired terminal # 0) And In the present embodiment, a case where the communication system is a WiMAX system will be described.

  FIG. 2 is a diagram illustrating a configuration example of the communication apparatus according to the present embodiment. The communication apparatus amplifies an input signal and outputs the input signal, and performs predetermined signal processing on the input signal. If the input signal is a high-frequency signal, it is converted to a burst band signal. Conversely, if a baseband signal is input, the radio unit 2 converts it to a high-frequency signal, and a base including CINR measurement processing described later. A berth band unit 3 that performs band processing and a control unit 4 that performs communication control are provided.

  FIG. 3 is a diagram illustrating a correspondence relationship between a pilot pattern that can be used by the communication apparatus according to the present embodiment and a pilot pattern orthogonal to the pilot pattern (hereinafter referred to as an orthogonal pilot pattern). As already described, the pilot pattern is a code pattern (combination) of two pilot signals transmitted at the same frequency. As shown in FIG. 3, there are four types of pilot patterns, and there are two types of orthogonal pilot patterns for each pilot pattern. For example, orthogonal pilot patterns for pilot patterns {(−1,0), (−1,0)} are {(−1,0), (1,0)} and {(1,0), (−1, 0)}. The remaining {(−1,0), (−1,0)} and {(1,0), (1,0)} are non-orthogonal pilot patterns.

  Subsequently, a characteristic operation of the communication apparatus according to the present embodiment will be described. Here, for convenience of explanation, it is assumed that desired sector # 0, interference sector # 1, and interference sector # 2 shown in FIG. 1 are managed by different base stations # 0, # 1, and # 2, respectively. Each base station has the same configuration and performs the same operation. An operation example of the base station # 0 managing the desired sector # 0 will be described.

  Each base station constituting the communication system of the present embodiment is used by the base station from other surrounding base stations that manage sectors that interfere with the sector that it manages. Obtain pilot signal sequence information. Then, when measuring CINR, measurement accuracy is improved by taking into account pilot signal sequences used by other base stations. FIG. 4 is a diagram illustrating an operation in which each base station acquires pilot signal sequence information used in other base stations by exchanging pilot signal sequence information with other base stations. In the present embodiment, it is assumed that communication in each of the three sectors shown in FIG. 1 gives interference to each other. Therefore, base stations # 0, # 1, and # 2 managing these sectors. However, as shown in FIG. 4, the information on the pilot signal sequences being used is exchanged.

  By exchanging information on the pilot signal sequence used by each base station in this way, the relationship between pilot patterns at each frequency becomes known at each base station. As a result, for example, the base station # 0 adds both the interference measured from the pilot signal arranged at each frequency whether the interference is the interference of the interference sector # 1 or the interference of the interference sector # 2 in FIG. It is possible to know in advance whether it is interference or neither is measured. The pilot signal sequence information is exchanged between base stations (obtained from other base stations) at the time of initial setting, once, periodically, and when exchanging some information between base stations It is possible to notify. In addition, different conditions may be provided for each base station, and notification may be made when this condition is satisfied or a notification request may be made to another base station.

  The operation for exchanging information of the pilot signal sequence is performed by the control unit 4 (see FIG. 2). When the control unit 4 acquires information on a pilot signal sequence used by another base station, the control unit 4 notifies the baseband unit 3 of the information. The baseband unit 3 holds the notified pilot signal sequence information and uses it in the subsequent CINR measurement operation. That is, the control unit 4 operates as a pilot signal sequence information acquisition unit, and the baseband unit 3 operates as a communication quality measurement unit.

  A specific operation of CINR measurement will be described. FIG. 5 is a diagram illustrating an example of a functional block that performs CINR measurement in the baseband unit 3. This functional block includes a signal power measurement unit 31, a received signal power measurement unit 32, a noise power measurement unit 33, subtractors 34 and 35, an averaging unit 36, and an interference determination unit 37. In addition, a pilot signal extracted from the received signal is input to the signal power measuring unit 31 and the received signal power measuring unit 32 as a received pilot signal. The interference determination unit 37 includes other information on the pilot signal sequence (pilot pattern for reducing the desired signal) transmitted by the desired terminal # 0 in its own sector (desired sector # 0) and the control unit 4 (see FIG. 2). “Information on pilot signal sequence used by other base station” (pilot pattern of interference source) acquired from the base station is input.

  When performing CINR measurement, in the baseband unit 3, the signal power measurement unit 31 and the reception signal power measurement unit 32 respectively input the signal power that is the power of the pilot signal component based on the received reception pilot signal. The total received signal power, which is the power of the received signal (received pilot signal including pilot signal component, interference component and noise component), is measured. When measuring the signal power, the signal power measurement unit 31 extracts the pilot signal component from the input signal and measures the signal power. When the signal pattern included as the interference component and the pilot pattern are non-orthogonal, The interference component cannot be removed. That is, the measurement result of the signal power includes an error (power of the interference component that could not be removed).

  When the measurement of the signal power and the total received signal power is completed, the subtractor 34 then receives the signal power and the total received signal power, subtracts the signal power from the total received signal power, and generates interference and noise power (interference power and interference power). The power obtained by adding the noise power) is calculated.

  Then, the subtractor 35 receives the calculation result (interference and noise power) in the subtractor 34 and the noise power measured and held in advance by the noise power measuring unit 33, and the noise power is calculated from the calculation result in the subtractor 34. The interference power is calculated by subtraction. A method by which the noise power measurement unit 33 measures noise power will be described later. When the power value calculated by the subtracter 35 is 0 or less, it means that the received pilot signal contains no interference component and only a noise component. Also, as shown in the description of the signal power measurement unit 31, when the signal pattern and the pilot pattern included as interference components are non-orthogonal, the signal power measurement result includes an error, so the signal power including the error is used. The interference power calculated in this way naturally includes an error.

  The signal power measuring unit 31, the received signal power measuring unit 32, the subtractor 34, and the subtractor 35 execute the above processing for all frequencies to which all pilot signals are allocated, and calculate the signal power and the interference power. obtain. The obtained signal power and interference power are passed to the averaging unit 36 as needed.

  When measurement of signal power and calculation of interference power are completed for all frequencies to which pilot signals are allocated, based on all the signal power and interference power obtained as a result and the determination result in the interference determination unit 37, The averaging unit 36 calculates CINR.

Here, the operation of the interference determination unit 37 will be described. When the interference determination unit 37 receives the pilot pattern of the desired signal source and the pilot pattern control unit 4 of the interference source described above, the interference determination unit 37 performs the determination process illustrated in FIG. Thus, the interference power from which interference source can be measured at each frequency to which the pilot signal is assigned, that is, the interference power measurement result from which interference source is included in the interference power measurement result at each frequency. To determine whether or not In FIG. 6, P _{r, a} represents the a-th pilot signal transmitted from the interference source r, and I _{r, a} represents the interference power due to P _{r, a} . In the example shown in FIG. 6, the interference determination unit 37 first confirms whether P _{0, a} is orthogonal to P _{1, a} (step S1), and further, P _{0, a} is P _{2, a} . It is confirmed whether or not they are orthogonal (steps S2 and S3). When P _{0, a} is orthogonal to P _{1, a} and P _{2, a} (step S1-Yes, step S2-Yes), the interference determination unit 37 determines from pilot signals a to I _{1, a} and I _{2, It} is determined that the interference power obtained by adding _a can be measured. When P _{0, a} is orthogonal to only P _{1, a} (step S1-Yes, step S2-No), it is determined that the interference power I _{1, a} can be measured from the pilot signal a. When P _{0, a} is orthogonal to only P _{2, a} (step S1-No, step S3-Yes), it is determined that the interference power I _{2, a} can be measured from the pilot signal a. In other cases (step S1-No, step S3-No), it is determined that the interference power cannot be measured from the pilot signal a.

  Details of the operation in which the averaging unit 36 calculates CINR will be described. Since the operation of the base station is described in the present embodiment, the averaging unit 36 first measures the interference in each block for the frequency block of the user minimum band shown in FIG. 7 in the CINR measurement. Calculate power. The user minimum band is a minimum unit when a base station allocates a band to a user, and the base station allocates one or more user minimum bands to a subordinate terminal station (desired terminal). In FIG. 7, q is the user minimum band number, and m is the number of pilot signals in the user minimum band. However, the CINR calculation accuracy that is finally obtained is improved by, for example, excluding the interference power of the same block that includes a larger error than the others from the processing target. Which one is excluded (which one is used for processing) is determined with reference to the determination result in the interference determination unit 37. How to determine what to exclude and how to calculate the interference power after exclusion will be described separately. When the calculation of the interference power for each block is completed, the averaging unit 36 further calculates the interference power by averaging the interference power obtained in the user minimum band over the entire band as shown in FIG. To do.

Then, the averaging unit 36 calculates the average signal power of all pilot signals, and uses this average signal power and the interference power calculated in the above procedure to calculate CINR according to the following equation (1). C _a is the signal power obtained from the a-th subcarrier, and I _q is the average interference power in the user minimum band #q. N _Power is noise power, and the power measured by the noise power measuring unit 33 is acquired in advance.

  Hereinafter, a method by which the averaging unit 36 calculates the interference power in the user minimum band will be described. When calculating the interference power in the user minimum band, the averaging unit 36 uses a method according to the determination result in the interference determination unit 37.

  First, when the determination result in the interference determination unit 37 corresponds to the case shown in FIG. 9, that is, when there is even one pilot pattern that is simultaneously orthogonal to all interference sectors (from each interference source). If the interference power can be measured by adding the interference power), obtain the average interference power of the frequency where the pilot pattern that is orthogonal to all the interference sectors is arranged, and this is the average interference power of the user's minimum band. To do.

  In the case shown in FIG. 9, there are pilot patterns that are simultaneously orthogonal to all interfering sectors, and there are pilot patterns that are orthogonal to each interfering sector at different frequencies (interference sources at a certain frequency). The interference power from # 1 can be measured, and the interference power from the interference source # 2 can be measured at other frequencies. Therefore, the following calculation method can also be used. That is, the average interference power X of the pilot pattern frequency that is orthogonal to all the interference sectors is obtained, and the average interference power of only the interference sector # 1 and the average interference power of only the interference sector # 2 are added. Y is obtained, and the average of X and Y is obtained, and this average value is set as the average interference power of the user minimum band.

  Next, when the determination result in the interference determination unit 37 corresponds to the case shown in FIG. 10, that is, there is no pilot pattern that is orthogonal to all the interference sectors at the same time, but orthogonal to each interference sector at different frequencies. If there is a relationship, the average interference power of only the interference sector # 1 and the average interference power of only the interference sector # 2 are obtained, and the sum of these is set as the average interference power of the user minimum band.

  Further, when the determination result in the interference determination unit 37 corresponds to the case shown in FIG. 11, that is, when there is a sector whose pilot pattern does not have an orthogonal relationship, the following (1) to (3) Do one of the processes.

(1) The interference power calculated within this user minimum band as not being valid data is not used for CINR calculation (the average interference power is not calculated in this user minimum band).
(2) A threshold is determined, and if there is interference power that exceeds the threshold even with only the interference power of one of the interference sectors, the average interference power in the user's minimum band is calculated using this. calculate.
(3) If there is interference power larger than the average interference power of other user minimum bands, the average interference power of the user minimum band is calculated using this.

  Further, when the determination result in the interference determination unit 37 corresponds to the case shown in FIG. 12, that is, when there is no orthogonal pilot pattern, it is determined that the data is not valid data and is within this user minimum band. The interference power calculated in is not used for CINR calculation.

  As described above, the communication apparatus (base station) according to the present embodiment acquires information on pilot signal sequences respectively used in cells or sectors managed by other surrounding base stations, and uses this information as the information. On the basis of which interference power that can be measured at each frequency where the pilot signal sequence is arranged is determined from which interference source, and when measuring communication quality (CINR), the interference power selected according to the determination result is It was decided to use it to calculate CINR. This makes it possible to measure CINR with higher accuracy than in the past.

  The CINR calculation method shown in this embodiment can be expected to have a great effect when the number of pilot signals per frequency is small. That is, when the number of pilot signals is small, the influence of the power measurement result with low measurement accuracy (including a large error) may increase and the CINR measurement accuracy may be greatly degraded. Since the power measurement result with low accuracy is not used, the CINR measurement accuracy can be greatly improved. Of course, it is effective even when the number of pilot signals is large (measurement accuracy can be improved).

Embodiment 2. FIG.
In the first embodiment, the case where a random signal sequence is used for the pilot signal has been described. However, the pilot signal sequence is scheduled so that the number of pilot patterns orthogonal to each interference source is maximized within the user minimum band. You may make it do (refer FIG. 13). As shown in FIG. 13, it is possible to efficiently measure the interference power of each interference sector by scheduling a pilot signal sequence. Scheduling is performed by, for example, the control unit 4 after exchanging information on the used pilot signal sequence with another base station, and notifies the baseband unit of the result. Further, when information on a pilot signal sequence used by another base station (a pilot pattern of an interference source) is notified from the control unit 4, the interference determination unit 37 of the baseband unit 3 may perform the information. The second embodiment is the same as the first embodiment except that scheduling is performed.

  As a result, the pilot patterns in the orthogonal relationship can be intentionally increased and the deviation of the pilot pattern orthogonal probability within each user minimum band can be reduced, so that interference is further increased as compared with the case of the first embodiment. The measurement accuracy of electric power can be improved, and the measurement accuracy of CINR can be improved.

  When exchanging information with the same base station a plurality of times, such as periodically exchanging information of pilot signal sequences between base stations, each base station performs scheduling each time it is exchanged If this is done, there is no point in performing scheduling, so each base station performs only once at the time of initial setting (when power is turned on).

Embodiment 3 FIG.
In each of the previous embodiments, the average of the power (signal power and interference power) is determined for each user minimum band. However, as shown in FIG. 14, the base station is connected to other base stations. Then, the information on the band allocated to each user (terminal station) is also exchanged, and the CINR measurement result at each frequency (frequency at which the pilot signal is arranged) is determined based on this information and pilot signal sequence information (FIG. 6). Reference). That is, the determination process shown in FIG. 6 is performed on each power measurement result in the band assigned to each user to evaluate each power measurement result, and those (power in the band assigned to each user are evaluated). It is determined to which case of FIG. 9 to FIG. Other parts are the same as those in the first or second embodiment.

  As a result, it is possible to take the average for each user instead of the average within the user minimum band, and the number of samples increases. Therefore, the above evaluation results are shown in FIG. 9 compared to the case of the first and second embodiments. The possibility of falling into the case shown or the case shown in FIG. 10 increases. As a result, the measurement accuracy of the interference power can be further improved and the CINR measurement accuracy can be improved as compared with the case of the first and second embodiments.

Embodiment 4 FIG.
In the previous embodiments, in the WiMAX system, an example in which there are two interference sources for a certain base station, that is, the number of pilot signals arranged in one frequency is the same as the number of interference sources has been described. However, even if the number of pilot signals arranged at one frequency is smaller than the number of interference sources, it is possible to measure CINR with higher accuracy than before.

  When the number of pilot signals arranged at one frequency is smaller than the number of interference sources, data (power calculation results) calculated by constructing an orthogonal relationship with a plurality of pilots is calculated for all interference powers. The interference power within the user minimum band is calculated by calculating to be the sum. This is the same operation as the interference power calculation operation in the case of FIG. 10 described in the first embodiment. Other parts are the same as those of the first embodiment.

  Note that the base station may schedule the pilot signal sequence so that the number of pilot patterns orthogonal to each interference source within the user minimum band is maximized, as in the second embodiment. Furthermore, as in Embodiment 3, the base station may acquire information on the bandwidth allocated to each user from other base stations, and take an average for each user based on the acquired information.

  As described above, the CINR measurement operation described in the first to third embodiments can be applied to a case where the number of interference sources is larger than the number of pilot signals arranged at one frequency.

Embodiment 5 FIG.
In the present embodiment, a method for measuring noise power in the noise power measuring unit 33 (see FIG. 5) will be described.

  When the noise power measurement unit 33 measures the noise power, for example, the base station first communicates with all other base stations (the base station managing the interference cell or the interference sector) for a certain period of time. The noise power is requested to be not used, and the result of the power measurement performed by the noise power measuring unit 33 during this fixed period is defined as noise power. Alternatively, all other base stations in the surrounding area are requested not to transmit a pilot signal for a certain period, and the result of power measurement by the noise power measuring unit 33 during this certain period is defined as noise power.

  Since the noise power measurement accuracy is improved by measuring the noise power in this way, the calculation accuracy of the interference power in the subtractor 35 shown in FIG. 5 is also improved, and as a result, the CINR measurement accuracy is improved. The operations other than the noise power measurement operation in the noise power measurement unit 33 are as described in the previous embodiment.

  The noise power can also be measured as follows. In the interference power measurement shown in the first embodiment, a pilot pattern that is non-orthogonal with all interference sources cannot be used. However, if all the interference sources and the pilot patterns are non-orthogonal, the power measured other than the signal power is only noise power. Therefore, the noise power measurement unit 33 can use this for noise power measurement. That is, the noise power can be measured using the power measurement result at the frequency where “measurable interference” shown in FIGS. 9 to 12 is “0 (none)”. Since noise does not depend on the band, data of all users can be used. As a result, the number of samples increases, and the measurement accuracy is improved. Further, the efficiency can be improved by not creating a useless pilot signal.

  Furthermore, when measuring the noise power using the power measurement result of the pilot pattern that cannot be used in the interference power measurement described above, a pilot that is not orthogonal to any interference source is intentionally created by scheduling, and the noise power is measured. Measurement may be performed. In such a case, the measurement accuracy of noise power can be improved by increasing the number of samples.

  In this specification, the WiMAX system is described as a specific example, but the present invention can be applied to any communication system similar to this. Moreover, although the operation when the base station measures the uplink communication quality (CINR) has been described, the present invention can also be applied to the case where the terminal station measures the downlink communication quality. In this case, when the base station acquires pilot signal sequence information from other surrounding base stations, the base station notifies the acquired terminal station of the acquired information. The operation when the terminal station measures CINR is the same as the operation when the base station measures CINR.

  As described above, the communication device according to the present invention is useful for a communication system that repeatedly uses the same frequency band for each cell or sector, and in particular, link adaptation according to communication quality measured using the number of pilot signals. Suitable for communication devices that perform

DESCRIPTION OF SYMBOLS 1 Amplifier part 2 Radio | wireless part 3 Baseband part 4 Control part 31 Signal power measurement part 32 Received signal power measurement part 33 Noise power measurement part 34,35 Subtractor 36 Averaging part 37 Interference determination part

Claims (15)

A communication device constituting a communication system that repeatedly uses the same frequency for each cell or sector,
Pilot signal sequence information acquisition means for acquiring information of a pilot signal sequence used in the adjacent cell or the adjacent sector from the adjacent base station that is a base station that manages the adjacent cell or the adjacent sector;
Communication quality measuring means for measuring communication quality based on measurement results of signal power and interference power in a pilot signal and information on the acquired pilot signal sequence;
A communication apparatus comprising: The communication quality measuring means includes
Signal power measuring means for measuring the signal power of the received pilot signal;
Noise power measuring means for measuring noise power;
Interference power calculating means for calculating interference power of the received pilot signal based on the signal power and the noise power;
Based on the information of the pilot signal sequence, pilots arranged at the same time at the same frequency as to whether the pilot signal used in each adjacent cell or sector and the pilot signal used in its own cell are orthogonal Interference determination means for determining for each signal;
Calculating means for calculating communication quality based on the signal power, the interference power, and a determination result in the interference determining means;
The communication apparatus according to claim 1, further comprising: The calculating means includes
The interference power is calculated using a pilot signal that is orthogonal to all pilot signals transmitted at the same time at the same frequency among pilot signals used in adjacent cells or adjacent sectors. The communication apparatus according to claim 2, wherein the communication quality is determined based on the determination result and, if included, the communication quality is calculated using the interference power. . The calculating means includes
The interference power is calculated using a pilot signal that is orthogonal to all pilot signals transmitted at the same time at the same frequency among pilot signals used in adjacent cells or adjacent sectors. If it is not included, it is transmitted at the same time of the same frequency in each pilot signal used in the adjacent cell or the adjacent sector. The communication quality according to claim 2, wherein if there is interference power calculated using a pilot signal that is orthogonal to one or more pilot signals, the communication quality is calculated using the interference power. apparatus. The calculating means includes
Predetermined amount of interference power calculated using pilot signals that are not orthogonal to any pilot signal transmitted at the same time at the same frequency among pilot signals used in adjacent cells or sectors The communication apparatus according to claim 4, wherein interference power exceeding 1 is used for calculation of communication quality. The calculating means includes
An average value of the signal power is calculated, an average value of the interference power is calculated using the interference power selected based on the determination result among the interference powers, and further, based on each of these average values. Communication quality is calculated. The communication apparatus as described in any one of Claims 2-5 characterized by the above-mentioned. When operating as a base station of the communication system,
The calculating means calculates an average value of interference power for each user minimum band, which is a minimum unit for assigning a band to a user, and further calculates for each user minimum band in the operation for calculating the average value of interference power. The communication device according to claim 6, wherein a final average value of the interference power is calculated by averaging each average value over the entire band. When operating as a base station of the communication system,
In the average power calculation operation, the calculation unit first calculates an average interference power for each band allocated to each user, and further calculates each average value calculated for each band allocated to the user. The final average value of the interference power is calculated by averaging over the entire band. The communication apparatus according to claim 6. When the noise power measuring means measures noise power,
Ask the neighboring base station not to communicate for a certain period of time,
The communication apparatus according to any one of claims 2 to 8, wherein the noise power measurement unit measures noise power by performing power measurement during the predetermined period. When the noise power measuring means measures noise power,
Ask the neighboring base station not to transmit a pilot signal for a certain period of time,
The noise power measurement unit measures noise power by performing power measurement at each frequency for transmitting a pilot signal during the certain period of time. Communication device. The noise power measuring means includes
Interference calculated by the interference power calculation means using a pilot signal that is not orthogonal to any pilot signal transmitted at the same time at the same frequency among pilot signals used in adjacent cells or adjacent sectors The communication apparatus according to claim 2, wherein noise power is measured using power. When operating as a base station of the communication system,
further,
Scheduling means for scheduling a pilot signal sequence used by the own station based on information on the pilot signal sequence;
The communication apparatus according to claim 1, further comprising:   The communication apparatus according to claim 1, wherein the communication quality is CINR.   The communication apparatus according to claim 1, wherein the communication apparatus operates as a communication apparatus of a WiMAX system. A communication quality measurement method executed by a communication apparatus constituting a communication system that repeatedly uses the same frequency for each cell or sector,
A pilot signal sequence information acquisition step for acquiring information of a pilot signal sequence used in the adjacent cell or adjacent sector from an adjacent base station that is a base station that manages the adjacent cell or adjacent sector;
A power measurement step for measuring signal power and interference power in the pilot signal;
A communication quality measurement step of measuring communication quality based on the acquired pilot signal sequence information and the measured signal power and interference power;
A communication quality measurement method comprising:

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