JP5793096B2 - Wireless communication terminal, impedance control method, and impedance control program - Google Patents

Description

  The present invention relates to a wireless communication terminal, an impedance control method, and an impedance control program that adaptively control the impedance of an antenna.

  In a small wireless communication terminal typified by a mobile phone, it is known that the input impedance changes depending on the surrounding environment and the usage state of the user, so that impedance mismatch occurs and transmission / reception characteristics deteriorate. Therefore, many control methods and circuit configurations have been devised in which a matching circuit capable of dynamically changing the impedance is inserted between the antenna of the terminal and the transmission / reception RF circuit, and matching is adaptively adapted to changes in the surroundings. .

  For example, the wireless device disclosed in Patent Document 1 detects reflected power due to mismatching with a directional coupler inserted between an antenna matching circuit and a transmission / reception circuit, and reduces the impedance of the antenna matching circuit so as to minimize reflection loss. Control adaptively.

  On the other hand, the wireless communication terminal described in Patent Document 2 is based on a channel response obtained by performing channel estimation in a terminal device having a plurality of antennas corresponding to MIMO (Multiple Input Multiple Output) transmission. Get correlation characteristics. The antenna impedance is controlled so that the throughput value predicted from these values or the transmission capacity value calculated from the estimated channel matrix is increased.

Japanese Patent Laid-Open No. 7-7357 Japanese Patent No. 4198552

  However, in the impedance control method as described in Patent Document 1, insertion efficiency of the directional coupler occurs, so that power efficiency is deteriorated. In addition, when a directional coupler is inserted into a plurality of antennas at a terminal that supports MIMO transmission using a plurality of antennas, the circuit scale increases. Furthermore, even if the impedance is controlled so as to minimize the reflection loss of all antennas, the quality of MIMO transmission is not always improved from the viewpoint of inter-element coupling and inter-antenna correlation.

  The impedance control method described in Patent Document 2 can optimize the reception characteristics of a communication system using MIMO transmission, but uses a different frequency band for transmission and reception as in a frequency division duplex (FDD) system. In a communication system, there is a possibility that transmission performance is degraded when the frequency characteristics of antenna transmission and reception are different.

  In this case, transmission power for satisfying required reception power on the base station side increases, and as a result, power consumption of the terminal increases. Although it is considered that the performance of both transmission and reception can be compensated to some extent by combining the method described in Patent Document 1 and the method described in Patent Document 2, a clear control index is not shown, and a directional coupler is inserted. Power loss occurs or the circuit scale increases.

  The present invention has been made in view of such circumstances, and even when the situation differs between transmission and reception, the antenna impedance is adaptively set, and a wireless communication terminal, an impedance control method, and an impedance that do not cause extra power loss An object is to provide a control program.

  (1) In order to achieve the above object, a wireless communication terminal according to the present invention is a wireless communication terminal having a plurality of antennas and capable of wireless communication using a frequency division duplex method, Based on the transmission quality information acquisition unit to be acquired and the transmission quality information of the acquired transmission quality information, the impedance of the first antenna group is controlled, and the reception quality of the acquired transmission quality information And an impedance control unit that controls the impedance of the second antenna group configured with antennas that do not belong to the first antenna group based on the information.

  As described above, the wireless communication terminal of the present invention controls the impedance of a plurality of antennas separately for each antenna group by using either transmission / reception quality information as an index, so that transmission / reception can be performed even when the situation differs between transmission and reception. The impedance mismatch effect can be alleviated simultaneously in the band, the transmission power can be reduced, and the reception throughput can be improved. Further, there is no need to insert a directional coupler, and no extra power loss occurs. In addition, it is possible to provide a wireless communication terminal particularly suitable for MIMO.

  (2) Moreover, the wireless communication terminal of the present invention is characterized in that the impedance control unit sets the impedance of the second antenna group in a state where the impedance of the first antenna group is fixed. Thus, after setting the impedance of the antenna of the first group, the impedance of the antenna of the second group is set, so that it is possible to increase the throughput while giving priority to the reduction of transmission power.

  (3) In the wireless communication terminal of the present invention, the impedance control unit fixes the impedances of the first and second antenna groups, and the transmission / reception quality information acquisition unit The impedance control unit obtains a change amount of the transmission quality information among the transmission / reception quality information obtained with the time interval set to a first threshold. When it exceeds, the impedance of the first antenna group is controlled again. Among the acquired transmission / reception quality information, when the amount of change in the reception quality information exceeds a second threshold, the second antenna group The impedance is controlled again.

  In this way, by setting the search trigger for each antenna by two-step threshold comparison, dynamic impedance control according to the situation becomes possible, and unnecessary search processing can be reduced. The power consumption required for switching the variable capacitance circuit can be reduced, and stable transmission and reception quality can be ensured.

  (4) Further, in the radio communication terminal of the present invention, the transmission / reception quality information acquisition unit uses a conversion table associating wideband channel quality information (Wideband CQI) with frequency utilization efficiency to transmit a base station transmission code as the transmission / reception quality information. The frequency utilization efficiency corresponding to wideband channel quality information (WidebandCQI) defined for each word is acquired, and the impedance control unit controls the impedance of the second antenna group based on the acquired frequency utilization efficiency. It is characterized by that. As described above, by using the frequency utilization efficiency for the broadband channel quality information, it is possible to control the impedance by eliminating the influence of the dynamic frequency allocation by the base station.

  (5) In the wireless communication terminal of the present invention, the transmission / reception quality information acquisition unit acquires a transmission power value of an antenna belonging to the first antenna group as the transmission / reception quality information, and the impedance control unit The impedance of the first antenna group is controlled based on the transmission power value of the antenna belonging to the first antenna group. Thereby, a transmission power value can be reduced by controlling to an appropriate impedance.

  (6) Further, in the radio communication terminal according to the present invention, the impedance control unit is based on the transmission power value of at least one of the uplink control channel and the data channel as the transmission power value of the antenna belonging to the first antenna group. And controlling the impedance of the first antenna group. Thereby, when only the transmission power value of either the uplink control channel (PUCCH) or the data channel (PUSCH) can be acquired, or when the transmission power values of both channels are controlled by the base station using different control techniques. Can also respond.

  (7) In the wireless communication terminal of the present invention, the transmission / reception quality information acquisition unit acquires a downlink path loss value of an antenna belonging to one of the first or second antenna group as the transmission / reception quality information, The impedance control unit controls the impedance of the one antenna group based on the acquired downlink path loss value. Thereby, an impedance with a small downlink path loss value can be selected.

  (8) In the wireless communication terminal of the present invention, the transmission / reception quality information acquisition unit acquires an RSRP value or an RSSI value of an antenna belonging to one of the first or second antenna group as the transmission / reception quality information, The impedance control unit controls the impedance of the one antenna group based on the acquired RSRP value or RSSI value. Thereby, an impedance with a large RSRP value or RSSI value can be selected.

  (9) Further, in the radio communication terminal of the present invention, the transmission / reception quality information acquisition unit uses the downlink path loss value of an antenna belonging to the first antenna group and the transmission power control command from the base station as the transmission / reception quality information. An addition result with a specified multiple of the closed loop control power increase is acquired, and the impedance control unit controls the impedance of the antenna group based on the acquired addition result. Thereby, it is possible to select an impedance for reducing the transmission power value.

  (10) In the wireless communication terminal of the present invention, the transmission / reception quality information acquisition unit acquires the addition result using different values for the uplink control channel and the data channel as the constant times the constant. It is said. Thereby, even in a situation where the transmission power values of both channels are controlled separately from the base station, an appropriate impedance can be selected at high speed using the quality information of both channels.

  (11) In the wireless communication terminal according to the present invention, the impedance control unit includes the transmission / reception quality information acquired from the controllable impedances of the antennas belonging to one of the first or second antenna groups. A first candidate is extracted based on the first transmission quality information, and the impedance is determined based on the second transmission quality information among the acquired transmission / reception quality information from the extracted candidates. It is said. Accordingly, the impedance of the corresponding antenna group can be appropriately selected by evaluating the impedance of the corresponding antenna group in two stages from different viewpoints.

  (12) In addition, the wireless communication terminal of the present invention is characterized in that, when extracting the candidates, the first transmission / reception quality information extracts candidates within a predetermined range from a reference value. Thereby, the evaluation result of transmission / reception quality information can be narrowed down to candidates within a preferable range, and the impedance can be appropriately selected. Thereby, the evaluation result of transmission / reception quality information can be narrowed down to candidates within a preferable range, and the impedance can be appropriately selected.

  (13) Further, in the wireless communication terminal of the present invention, the impedance control unit divides the impedance of the first antenna group into a plurality of groups, and the first transmission quality information is included in the acquired transmission / reception quality information. And selecting a candidate group from the plurality of groups, fixing the selected candidate group, and determining an impedance within the group based on second transmission quality information of the acquired transmission / reception quality information In this way, the impedance candidates are extracted and determined.

  Thereby, the impedance can be grouped and the impedance of each antenna can be evaluated in two stages from different viewpoints. For example, an appropriate capacity can be determined using a variable parallel capacitance circuit and a series capacitance circuit connected to the first antenna group.

  (14) In the wireless communication terminal of the present invention, the impedance control unit determines the impedance based on the transmission power value of at least one of an uplink control channel and a data channel as the second transmission quality information. It is characterized by that. Thereby, when only the transmission power value of either the uplink control channel (PUCCH) or the data channel (PUSCH) can be acquired, or when the transmission power values of both channels are controlled by the base station using different control techniques. Can also respond.

  (15) Further, in the radio communication terminal of the present invention, the impedance control unit uses the downlink transmission loss value of the antenna belonging to the first antenna group and the transmission power control from the base station as the second transmission quality information. The impedance is determined based on the addition result with a constant multiple of the amount of increase in the closed loop control power specified by the command. Thereby, it is possible to select an impedance that reduces not only the downlink path loss value but also the amount of increase in the closed loop control power.

  (16) In the wireless communication terminal of the present invention, the impedance control unit may determine the impedance candidate based on any one of a downlink path loss value, an RSRP value, and an RSSI value of the antennas belonging to the first antenna group. It is characterized by extracting. Thereby, it is possible to select an appropriate impedance stepwise by combining evaluation of any one of the downlink path loss value, the RSRP value, and the RSSI value.

  (17) Further, the impedance control method of the present invention is an impedance control method used for a radio communication terminal having a plurality of antennas and capable of radio communication by a frequency division duplex method, Acquiring reception quality, controlling the impedance of the first antenna group based on the first transmission / reception quality information of the acquired transmission / reception quality information, and out of the acquired transmission / reception quality information And controlling the impedance of the second antenna group composed of antennas not belonging to the first antenna group based on the second transmission / reception quality information.

  Thereby, even when the situation differs between transmission and reception, it is possible to alleviate the influence of impedance mismatch in the transmission and reception bands at the same time, reduce transmission power, and improve reception throughput. Further, there is no need to insert a directional coupler, and no extra power loss occurs. In addition, it is possible to provide a wireless communication terminal particularly suitable for MIMO.

  (18) The impedance control program of the present invention is an impedance control program installed in a wireless communication terminal having a plurality of antennas and capable of wireless communication using a frequency division duplex method. A process for acquiring reception quality, a process for controlling the impedance of the first antenna group based on the first transmission / reception quality information of the acquired transmission / reception quality information, and the acquired transmission / reception quality information Based on the second transmission / reception quality information, a process for controlling the impedance of the second antenna group composed of antennas not belonging to the first antenna group and a computer are executed.

  Thereby, even when the situation differs between transmission and reception, it is possible to alleviate the influence of impedance mismatch in the transmission and reception bands at the same time, reduce transmission power, and improve reception throughput. Further, there is no need to insert a directional coupler, and no extra power loss occurs. In addition, it is possible to provide a wireless communication terminal particularly suitable for MIMO.

  According to the present invention, it is possible to adaptively control the impedance of a plurality of antennas using the transmission / reception quality of the antenna as an index without adding a directional coupler or the like. Impedance mismatch effects can be alleviated simultaneously in the transmission / reception band without causing extra power loss, and transmission power can be reduced. In addition, it is possible to provide a wireless communication terminal excellent in MIMO reception performance.

It is a block diagram which shows the structural example of the radio | wireless communication terminal of this invention. It is a flowchart which shows the basic operation example of the radio | wireless communication terminal of this invention. 5 is a flowchart illustrating an example of processing of a first capacity search (first embodiment). It is a flowchart which shows the process example of a 2nd capacity | capacitance search (1st Embodiment). It is a flowchart which shows the process example of a 1st capacity search (2nd Embodiment). It is a flowchart which shows the process example of a 1st capacity search (2nd Embodiment). 10 is a flowchart illustrating a processing example of a first capacity search (third embodiment).

  Next, embodiments of the present invention will be described with reference to the drawings. In order to facilitate understanding of the description, the same reference numerals are given to the same components in the respective drawings, and duplicate descriptions are omitted.

[First Embodiment]
(Configuration of wireless communication terminal)
FIG. 1 is a block diagram illustrating a configuration example of the wireless communication terminal 100. The radio communication terminal 100 corresponds to the frequency division duplex system, has two antennas 110 and 120, and variable capacitance circuits 111 and 121 are connected to both antenna ends as impedance variable means, respectively. As described above, the wireless communication terminal 100 includes impedance varying means between at least one antenna and the transmission / reception RF circuit.

  In the wireless communication terminal 100, the antenna 110 (first antenna group) is used as a transmission / reception antenna, and the antenna 120 (second antenna group) is used as a reception antenna. That is, the antenna 110 connected to the variable capacitance circuit 111 is connected to the transmission RF circuit 114 and the reception RF circuit 115 via the frequency duplexer 113, and the antenna 120 connected to the variable capacitance circuit 121 is connected to the reception RF circuit 125. Has been.

  Each of the variable capacitance circuits 111 and 121 has a finite number of capacitors connected in series and in parallel in the circuit. The antenna impedance can be changed by switching this capacitor according to the instruction signal from the impedance control unit 123. Note that the capacitance may be changed by another configuration such as controlling the voltage applied to the variable capacitance diode instead of the capacitor. A baseband signal processing circuit 130 connected to each of the RF circuits 114, 115, and 125 performs data modulation / demodulation, encoding, and decoding processing.

  Transmission / reception quality information acquisition section 140 acquires transmission / reception quality information of the terminal based on information received from baseband signal processing circuit 130. For example, transmission / reception quality information for each state of the variable capacity circuits 111 and 121 from downlink control information obtained when decoding the downlink control channel (PDCCH) and uplink control information calculated on the terminal side and fed back to the base station To extract.

  The transmission / reception quality information acquisition unit 140 has a conversion table that indexes the corresponding frequency use efficiency from the wideband channel quality information (WidebandCQI). Then, wideband channel quality information (WidebandCQI) defined for each transmission codeword of the base station is acquired as reception quality information, and the total value of frequency utilization efficiency corresponding to this can be calculated.

  The impedance control unit 123 includes capacitance value setting units 123a and 123b, a quality fluctuation amount acquisition unit 123c, and a capacitance value / quality information storage unit 123d. The capacitance value setting unit 123a sets the capacitance value of the variable capacitance circuit 111 based on the transmission quality information (first capacitance search). That is, the impedance of the antenna 110 is set. The capacity value setting unit 123b sets the capacity value of the variable capacity circuit 121 based on the reception quality information (second capacity search). That is, the impedance of the antenna 120 is set.

  The quality variation acquisition unit 123c acquires the amount of change in the transmission / reception quality information at a specific interval after fixing the impedance by the first and second capacity searches. It is preferable to acquire periodically at predetermined time intervals. When the variation amount of the transmission quality exceeds the threshold value, the capacity value setting unit 123a searches the capacity value of the antenna 110 again. When the variation amount of the reception quality exceeds the threshold value, the capacity value setting unit 123b searches for the capacitance value of the antenna 120 again.

(Transmission / reception quality information and processing example)
Although details will be described later, the transmission / reception quality information and the processing associated therewith can be variously adopted as follows. The transmission / reception quality information acquisition unit 140 can acquire the downlink path loss value of the antenna belonging to the antenna 110 as the transmission / reception quality information. The capacitance value setting unit 123a can search for a variable capacitance value that minimizes the path loss value.

  The transmission / reception quality information acquisition unit 140 can also acquire a reference signal received power (RSRP) value or a received signal strength (RSSI) value of an antenna belonging to the antenna 110 as the transmission / reception quality information. The capacitance value setting unit 123a searches for a variable capacitance value that maximizes the acquired value.

  In this case, the transmission / reception quality information acquisition unit 140 acquires, as the transmission / reception quality information, the downlink path loss value of the antenna belonging to the antenna 110 and the closed loop control power increase amount specified by the transmission power control command from the base station. You can also.

  The capacity value setting unit 123a uses the addition result of the downlink path loss value of the antenna belonging to the antenna 110 and the constant multiple of the increase amount of the closed loop control power specified by the transmission power control command from the base station, and minimizes the addition result. Search for variable capacitance values to be converted. In that case, it is preferable to use different values for the uplink control channel (PUCCH) and the data channel (PUSCH) as constants.

  The capacity value setting unit 123a can set the capacity value using the downlink path loss value, the reference signal received power (RSRP) value, or the received signal strength (RSSI) value as the first quality information. Further, as the second transmission quality information, the transmission power of at least one of the uplink control channel (PUCCH) and the data channel (PUSCH), the closed path control power specified by the downlink path loss value and the transmission power control command from the base station An addition result with a constant multiple of the increase amount can be used.

(Basic operation example)
FIG. 2 is a flowchart showing a basic operation example of impedance control. The basic operation is started from the time when the wireless communication terminal 100 detects an initial search trigger issued when the connection with the base station is completed. The operation after the initial trigger detection will be described with reference to FIG.

  First, the capacitance value of the variable capacitance circuit 121 is fixed, and the capacitance value of the variable capacitance circuit 111 is searched based on the transmission quality information (step S1). Then, after selecting an appropriate capacitance value as the capacitance value of the variable capacitance circuit 111, the capacitance value of the variable capacitance circuit 111 is fixed (step S2).

  Next, the capacitance value of the variable capacitance circuit 121 is searched based on the reception quality information (step S3), and after selecting an appropriate capacitance value, the capacitance value of the variable capacitance circuit 121 is fixed (step S4). The transmission / reception quality information used for the search and a specific search method for each variable capacitance circuit will be described later. In the above example, the search based on the reception quality information is performed after the search based on the transmission quality information. This is preferable in terms of implementation, but the search based on the transmission quality information may be performed after the search based on the reception quality information. Is possible.

Next, when the capacitance values of the variable capacitance circuits 111 and 121 are determined, transmission / reception quality reference data is acquired (step S5), and the variation amount of the transmission / reception quality information is determined with the capacitance value fixed based on this value. The fluctuation amount acquisition unit 123c periodically measures (step S6). Then, it is determined whether or not the variation amount of the reception quality information is smaller than the set value λ ₂ (step S7). If the variation amount is smaller than the set value λ ₂ , the variation amount of the transmission quality information is further set to the set value λ 2. _It is determined whether or not it is smaller than ₁ (step S8). If the amount of change set value lambda ₁ is smaller than the flow returns to step S1. That is, when the amount of fluctuation in the quality information for both transmission and reception is larger than a threshold set in advance for each quality parameter, the process returns to the initial state and the search for the variable capacitance circuits 111 and 121 is started.

Further, when it is the variation amount set value lambda ₂ or more in step S7, the amount of variation of the transmission quality information to determine whether the set value lambda ₁ is smaller than (step S9), and the amount of variation of the transmission quality information if the set value lambda ₁ or more, the process returns to step S6.

On the other hand, when the fluctuation amount is set value lambda ₁ is smaller than the transmission quality information, performs a first capacitor search (step S10), and fixing the capacitance value of the antenna 110 (step S11), and transmission quality reference data Is acquired (step S12), and the process returns to step S6. That is, when only the amount of change in the transmission quality information exceeds the threshold, only the capacity search of the variable capacitance circuit 111 is performed again, and the reference data for the transmission quality information is updated.

On the other hand, when the amount of transmission quality variation is set value lambda ₁ or step S8, the second performs capacity search (step S13), and by fixing the capacitance value of the antenna 120 (step S14), and reception quality Reference data is acquired (step S15). That is, when the variation amount of only the reception quality information exceeds the threshold value, only the variable capacitance circuit 121 is searched and the reception quality reference data is updated.

  In this way, unnecessary search processing can be reduced by setting the search trigger individually for each variable capacitance circuit by comparing the threshold values in two steps. As a result, it is possible to reduce power consumption required for switching the variable capacitance circuit and to secure stable transmission / reception quality.

(Index setting)
In the basic operation example shown in FIG. 2, the radio communication terminal 100 uses transmission power set as a result of transmission power control by the base station in the capacity search of the variable capacitance circuit 111. It is expected that the transmission power value is minimized when the antenna 110 is matched with the variable capacitance circuit 111.

Therefore, the transmission / reception quality information acquisition unit 140 extracts transmission power information, and sets the capacitance value index ka of the variable capacitance circuit 111 that minimizes the transmission power value from among all the capacitance value candidates as shown in the following formula (1). select. Note that k represents a capacitance value index of the variable capacitance circuit 111, and P ₁ (k) represents an average value in a predetermined subframe section of the power of the signal transmitted from the antenna 110 when k is set in the capacitance circuit. When targeting a plurality of antennas, the minimum value of the total transmission power values is obtained.

FIG. 3 is a flowchart illustrating an example of processing of the first capacity search. K represents the total number of candidates that can be selected by the variable capacitance circuit 111. First, the capacitance value index of the variable capacitance circuit 111 is initialized by setting k = 0 (step T1), and the capacitance value index of the variable capacitance circuit 111 is set to k (step T2). Next, average transmission power P ₁ (k) for the number of N _SF subframes is calculated (step T3), and it is determined whether or not k + 1 is equal to or greater than K (step T4). If the result of determination is that k + 1 is not greater than or equal to K, k is incremented by 1 (step T5) and the process returns to step T2. When k + 1 is equal to or greater than K, the capacity value setting unit 123a extracts k that minimizes the transmission power value P ₁ (k) (step T6), and ends the process.

In the above example, the capacity value index that minimizes the transmission power is detected, but when the uplink transmission power of the radio communication terminal 100 is controlled from the base station by a different transmission power control method depending on the channel type, Even if the variable capacity value that minimizes the transmission power is determined without distinguishing between both channels, the determined capacity value does not always result in the least amount of mismatch in the uplink band. For example, LTE (Long Term Evolution), which is one of the 3GPP standards, employs different transmission power control methods for the physical uplink control channel (PUCCH) and the physical uplink shared channel (PUSCH). In this case, a configuration using the following parameters instead of the uplink transmission power may be used.
-PUCCH transmission power-PUSCH transmission power-Path loss value and the sum of a constant multiple of the offset value specified by the closed loop control command from the base station

(Set different constant values in advance for PUCCH and PUSCH)
In the capacitance search of the variable capacitance circuit 121, the following equation is used so that the average frequency use efficiency in a predetermined subframe section is maximized under the condition that the capacitance value of the variable capacitance circuit 111 is fixed among all the variable capacitance values. A capacitance value index ka of the variable capacitance circuit 121 that satisfies (2) is selected. In this way, the capacity value setting unit 123b searches for a variable capacity value that maximizes the average value (total value) of frequency utilization efficiency.

Here, k represents a capacitance value index of the variable capacitance circuit 111, and Eff (CQI _{cw_l} (k)) represents frequency utilization efficiency corresponding to CQI _{cw_l} (k) which is the Wideband CQI of the _lth codeword when k is set. λ represents a forgetting factor. The index is performed based on the conversion table illustrated in Table 1, for example. Table 1 shows an example of broadband channel quality information and a frequency utilization efficiency conversion table.

FIG. 4 is a flowchart illustrating a processing example of the second capacity search. K represents the total number of candidates that can be selected by the variable capacitance circuit 121. First, the capacitance value index of the variable capacitance circuit 121 is initialized with k = 0 (step P1), and the capacitance value index of the variable capacitance circuit 121 is set to k (step P2). Next, the average frequency use efficiency DLFE (k) for the number of N _SF subframes is calculated (step P3). Next, it is determined whether or not k + 1 is equal to or greater than K (step P4). If the result of determination is that k + 1 is not greater than or equal to K, k is incremented by 1 (step P5), and the process returns to step P2. If k + 1 is equal to or greater than K, k that maximizes the average frequency utilization efficiency DLFE (k) is extracted (step P6), and the process ends.

[Second Embodiment]
In the above embodiment, the capacitance value index is determined in one step by one transmission / reception quality information in the capacitance search of the variable capacitance circuit 111, but the capacitance value index is determined in two steps using two quality information. Also good. The present embodiment is the same as the first embodiment except for the capacitance search of the variable capacitance circuit 111.

  In this case, the capacity value setting unit 123a includes all of the capacity value candidates that can be changed using the first transmission / reception quality information of the antennas 110 belonging to the first antenna group in the first capacity search process. The number of specific candidates determined in advance is extracted from (first search step). Then, an appropriate capacity value is determined from the candidates extracted using the second transmission / reception quality information of the antennas 110 belonging to the first antenna group (second search step).

FIG. 5 is a flowchart illustrating a processing example of the first capacity search. First, K represents the total number of candidates that can be selected by the variable capacitance circuit 111. First, the capacitance value index of the variable capacitance circuit 111 is initialized by setting k = 0 (step Q1), and the capacitance value index of the variable capacitance circuit 111 is set to k (step Q2). Next, path loss values corresponding to the number of N _SF1 subframes are acquired (step Q3). Next, it is determined whether or not k + 1 is greater than or equal to K-1 (step Q4). If the result of determination is that k + 1 is not equal to or greater than K-1, k is incremented by 1 (step Q5) and the process returns to step Q2. If k + 1 is greater than or equal to K-1, M candidates are extracted for k with a small path loss value (step Q6).

Next, as m = 0 (step Q7), it sets the capacitance value index of the variable capacitance circuit 111 _{k m} (step Q8). Then, the transmission power corresponding to the number of N _SF2 subframes is acquired (step Q9), and it is determined whether m is M−1 or more (step Q10). If m is not greater than or equal to M−1 as a result of the determination, m is increased by 1 (step Q11), and the process returns to step Q8. If m is greater than or equal to M−1, km that minimizes the transmission power is obtained, the capacity value is fixed (step Q12), and the process is terminated.

This process is divided into two steps. In the first search step, the path loss value is averaged over a predetermined number of subframes N _SF1 for each variable capacitance value, and M candidates having a small path loss value are extracted. In the second search step, the average transmission power is calculated over a predetermined number of subframes N _SF2 for each of the extracted M candidates, and the capacitance value of the variable capacitance circuit 111 is extracted by extracting the candidate with the smallest transmission power. To decide.

  Instead of narrowing down to the number M of candidates fixed in the first search step, the minimum value of path loss is detected, and the difference from the minimum value is narrowed down to candidates that fall within the preset offset value α. May be. In this case, the capacity value setting unit 123a minimizes or maximizes the first transmission / reception quality information among all capacity value candidates that can be changed using the first transmission / reception quality information of the antenna 110 in the capacity search. Candidates and candidates whose difference amount based on the minimum or maximum value is smaller than a preset threshold value are extracted (first search step). Then, using the second transmission / reception quality information, an appropriate capacitance value is determined from the extracted candidates for the antenna belonging to the first group (second search step).

FIG. 6 is a flowchart illustrating a processing example of the first capacity search. First, K represents the total number of candidates that can be selected by the variable capacitance circuit 111. First, k = 0 is initialized to initialize the capacitance value index of the variable capacitance circuit 111 (step R1), and the capacitance value index of the variable capacitance circuit 111 is set to k (step R2). Next, path loss values corresponding to the number of N _SF1 subframes are acquired (step R3). Next, it is determined whether or not k + 1 is greater than or equal to K-1 (step R4). As a result of the determination, if k + 1 is not K−1 or more, k is increased by 1 (step R5), and the process returns to step R2. If k + 1 is equal to or greater than K−1, Ma candidate extraction is performed for k where the path loss value PL (k) satisfies the path loss value PL (k _MIN ) + α (step R6).

Next, (step R7) as m = 0, sets the capacitance value index of the variable capacitance circuit 111 _{k m} (step R8). Then, transmission power corresponding to the number of N _SF2 subframes is acquired (step R9), and it is determined whether m is equal to or greater than Ma−1 (step R10). If m is not greater than or equal to Ma-1 as a result of the determination, m is increased by 1 (step R11), and the process returns to step R8. If m is greater than or equal to Ma−1, km that minimizes the transmission power is obtained, the capacity value is fixed (step R12), and the process ends.

  Note that the reference signal received power (RSRP) or the received power (RSSI) of the target band may be used instead of the path loss value. In this case, the difference from the M candidate or maximum value that increases RSRP or RSSI is α. Extract candidates within.

[Third Embodiment]
In the above embodiment, the individual capacitance values are compared. However, the capacitance values can be determined for each group after the capacitance values are divided for each group and group candidates are extracted. The present embodiment is the same as the first embodiment except for the capacitance search algorithm of the variable capacitance circuit 111. Further, it is assumed that the capacitance setting value of the variable capacitance circuit 111 is divided into a plurality of groups in advance.

Table 2 shows an example in which the capacity setting values are grouped as an example of the capacity value index table. In this example, the settings of capacitor circuits having the same series capacitance value but different parallel capacitance values belong to the same group. The capacity value index is represented by k _{g, p} , g is a group index, and p is an index within the group.

  In this case, the capacitance value setting unit 123a fixes the capacitance value of the parallel capacitance circuit in the capacitance search, and the serial capacitance circuit candidate from the serial capacitance circuit candidates that can be changed using the first transmission / reception quality information of the antenna 110. Is selected (first search step). In addition, the capacitance value setting unit 123a fixes the series capacitance circuit to the selected candidate, and determines an appropriate capacitance value from among the parallel capacitance circuit candidates that can be changed using the second transmission / reception quality information of the antenna 110 (the first capacitance value). 2 search step). Note that the series capacitance circuit and the parallel capacitance circuit may be interchanged in the above processing.

  FIG. 7 is a flowchart illustrating a processing example of the first capacity search. First, G represents the total number of groups that can be selected by the variable capacitance circuit 111. The operation of this process will be described with reference to FIG. This operation is divided into two steps.

In the first search step, first, p = 0 and g = 0 are initialized (step U1), and the capacitance value index of the variable capacitance circuit 111 is set to k _{g, p} (step U2). In a state where p = 0 is fixed, the path loss value is averaged over a predetermined number of subframes N _SF1 with respect to each variable capacitance value k _{g, 0} while switching _g, and the candidate k _g that minimizes the path loss value. _{, 0} are extracted (step U3). Next, it is determined whether g + 1 is G or more (step U4). If g + 1 is not equal to or greater than G as a result of determination, g is incremented by 1 (step U5), and the process returns to step U2. If g + 1 is equal to or greater than G, g = ga that minimizes the path loss value PL (k _{g, p} ) is extracted and set to p = 1 (step U6). Then, the process proceeds to the second step.

In the second search step, the capacitance value of the variable capacitance circuit 111 is set to the index k _{ga, p} (step U7). Then, g is fixed to _ga, and the average transmission power is calculated over a predetermined number of subframes N _SF2 for each variable capacitance value k _{ga, p} while switching p (step U8). Next, it is determined whether or not p + 1 is greater than or equal to mg (step U9). If p + 1 is not greater than or equal to mg, p is incremented by 1 (step U10), and the process returns to step U7. On the other hand, if p + 1 is greater than or equal to mg, the candidate value p = pa having the smallest transmission power is extracted to determine the capacitance value _{kga, pa} of the variable capacitance circuit 111 (step U11), and the process is terminated. .

  Further, in the first search step, the reference signal received power (RSRP) or the received power (RSSI) of the target band may be used instead of the path loss value. In this case, g that maximizes RSRP or RSSI is detected. .

  Each process in the above embodiment is executed by a program. In the above embodiment, the number of antennas is two, but may be three or more. Further, although antennas 110 and 120 are representative, a set of antennas (antenna group) may be targeted. In the above embodiment, impedance control is represented by capacitance value control.

DESCRIPTION OF SYMBOLS 100 Wireless communication terminal 110 Antenna 111 Variable capacity circuit 113 Frequency duplexer 114 Transmission RF circuit 115 Reception RF circuit 120 Antenna 121 Variable capacity circuit 123 Impedance control part 123a Capacity value setting part 123b Capacity value setting part 123c Quality fluctuation amount acquisition part 123d Capacity Value / quality information storage unit 125 Reception RF circuit 130 Baseband signal processing circuit 140 Transmission / reception quality information acquisition unit

Claims (18)

A wireless communication terminal having a plurality of antennas and capable of wireless communication using a frequency division duplex method,
A transmission / reception quality information acquisition unit for acquiring transmission / reception quality information of the own device;
Based on the transmission quality information of the acquired transmission / reception quality information, the impedance of the first antenna group is controlled, and based on the reception quality information of the acquired transmission / reception quality information, the first A wireless communication terminal comprising: an impedance control unit configured to control an impedance of a second antenna group including antennas not belonging to the antenna group.   The wireless communication terminal according to claim 1, wherein the impedance control unit sets the impedance of the second antenna group in a state where the impedance of the first antenna group is fixed. The impedance control unit fixes the impedance of the first and second antenna groups,
The transmission / reception quality information acquisition unit acquires the amount of change in the transmission / reception quality information of the own device after a time interval after fixing the impedance,
The impedance control unit controls again the impedance of the first antenna group when the amount of change in the transmission quality information exceeds a first threshold among the transmission / reception quality information acquired with the time interval. The impedance of the second antenna group is controlled again when the amount of change in the reception quality information of the acquired transmission / reception quality information exceeds a second threshold value. Item 3. A wireless communication terminal according to Item 2. The transmission / reception quality information acquisition unit uses, as a transmission / reception quality information, wideband channel quality information (Wideband CQI) defined for each transmission codeword of the base station by a conversion table that associates wideband channel quality information (Wideband CQI) with frequency utilization efficiency. ) To obtain the frequency usage efficiency corresponding to
4. The wireless communication terminal according to claim 1, wherein the impedance control unit controls the impedance of the second antenna group based on the acquired frequency utilization efficiency. 5. The transmission / reception quality information acquisition unit acquires transmission power values of antennas belonging to the first antenna group as the transmission / reception quality information,
The said impedance control part controls the impedance of the said 1st antenna group based on the transmission power value of the antenna which belongs to the said 1st antenna group, The Claim 1 characterized by the above-mentioned. Wireless communication terminal.   The impedance control unit controls the impedance of the first antenna group based on a transmission power value of at least one of an uplink control channel and a data channel as a transmission power value of an antenna belonging to the first antenna group. The wireless communication terminal according to claim 5. The transmission / reception quality information acquisition unit acquires a downlink path loss value of an antenna belonging to one of the first or second antenna group as the transmission / reception quality information,
5. The radio communication terminal according to claim 1, wherein the impedance control unit controls an impedance of the one antenna group based on the acquired downlink path loss value. 6. The transmission / reception quality information acquisition unit acquires an RSRP value or an RSSI value of an antenna belonging to one of the first or second antenna group as the transmission / reception quality information,
The wireless communication terminal according to any one of claims 1 to 4, wherein the impedance control unit controls an impedance of the second antenna group based on the acquired RSRP value or RSSI value. . The transmission / reception quality information acquisition unit, as the transmission / reception quality information, includes a downlink path loss value of an antenna belonging to the first antenna group and a constant multiple of a closed loop control power increase amount specified by a transmission power control command from a base station. Get the addition result,
The wireless communication terminal according to any one of claims 1 to 4, wherein the impedance control unit controls the impedance of the antenna group based on the acquired addition result.   The radio communication terminal according to claim 9, wherein the transmission / reception quality information acquisition unit acquires the addition result using different values for the uplink control channel and the data channel as the constant times the constant. The impedance control unit extracts a first candidate from the controllable impedance of the antenna belonging to the first antenna group based on the first transmission quality information among the acquired reception quality information, wherein 5. The impedance according to claim 1, wherein the impedance is determined from the extracted first candidates based on second transmission quality information among the acquired transmission / reception quality information. 6. Wireless communication terminal.   12. The wireless communication terminal according to claim 11, wherein when the candidate is extracted, the first transmission / reception quality information extracts a candidate within a predetermined range from a reference value.   The impedance control unit divides the impedance of the first antenna group into a plurality of groups, and selects a candidate group from the plurality of groups based on the first transmission quality information among the acquired transmission / reception quality information. The impedance candidate is extracted and determined by fixing the selected candidate group and determining the impedance within the group based on the second transmission quality information among the acquired transmission / reception quality information. The wireless communication terminal according to claim 1, wherein the wireless communication terminal is a wireless communication terminal.   The said impedance control part determines the said impedance based on the transmission power value of at least one of an uplink control channel and a data channel as said 2nd transmission quality information, The Claim 13 to Claim 13 characterized by the above-mentioned. A wireless communication terminal according to any one of the above.   The impedance control unit, as the second transmission quality information, is a constant multiple of a downlink path loss value of an antenna belonging to the first antenna group and a closed loop control power increase amount specified by a transmission power control command from a base station. The wireless communication terminal according to any one of claims 11 to 13, wherein the impedance is determined based on a result of the addition.   12. The impedance control unit extracts the impedance candidates based on any one of a downlink path loss value, an RSRP value, and an RSSI value of an antenna belonging to the first antenna group. The wireless communication terminal according to any one of 15. An impedance control method used for a wireless communication terminal having a plurality of antennas and capable of wireless communication using a frequency division duplex method,
A step of acquiring transmission / reception quality information of the own device;
Based on the transmission quality information of the acquired transmission / reception quality information, the impedance of the first antenna group is controlled , and based on the reception quality information of the acquired transmission / reception quality information, the first And controlling the impedance of the second antenna group composed of antennas not belonging to the antenna group. An impedance control program installed in a wireless communication terminal having a plurality of antennas and capable of wireless communication using a frequency division duplex method,
Processing to acquire the transmission / reception quality information of own machine,
Based on the transmission quality information of the acquired transmission / reception quality information, the impedance of the first antenna group is controlled , and based on the reception quality information of the acquired transmission / reception quality information, the first An impedance control program characterized by causing a computer to execute processing for controlling the impedance of a second antenna group composed of antennas that do not belong to an antenna group.

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