JP2009239464A - Radio communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication device for reducing power consumption by entering an operation mode selected by a user when a battery is low. <P>SOLUTION: The radio communication device of a CDMA system includes: a path search part for searching a path on the basis of a search parameter for specifying at least one of a path search interval and the number of base stations to be searched; a register for storing a default first search parameter and a second search parameter corresponding to the limiting condition of a user moving speed selected by the user; and a determination part for asserting an output signal when detecting that the battery is reduced to a threshold or less. In response to the assertion of the output signal from the determination part, the search parameter to be used for the path search is changed from the first search parameter to the second search parameter. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present disclosure generally relates to a wireless communication device, and more particularly to a wireless communication device with reduced power consumption.

  In a small wireless communication device such as a mobile phone, it is required to reduce power consumption in order to extend the operation time. For the purpose of such power consumption reduction, a countermeasure specially designed when the remaining battery level is low has been proposed.

  In Patent Document 1, according to the remaining battery level, by controlling the operation mode of the codec hierarchical encoding (switching the number of quantization bits), the function and performance are reduced to reduce the power consumption and extend the operating time. I am trying. In Patent Document 2, the corresponding service is switched so as to limit the image transmission mode to the audio mode according to the remaining battery level, and accordingly, the operation time is extended by controlling the codec encoding and quantization operation modes. I am trying.

  In Patent Document 3, power consumption is reduced while performance is reduced by controlling the number of fingers according to the remaining battery level. In Patent Document 4, the remaining battery level is not seen, but the number of repetitions of the turbo decoder is optimized with reference to a table linked with the SIR, thereby reducing power consumption and delay time.

All of the above techniques are closed control in the baseband unit or control for automatically switching a single mode visible to the user, and the user has no selection right. Therefore, for example, it is difficult to respond to a specific request such that high-speed downloading of data may be disabled, but it is desired to ensure only a long talk time.
JP 2002-135127 A WO96 / 27987 JP 2004-266487 A JP 2001-186024 A

  In view of the above, a wireless communication device that reduces power consumption by shifting to an operation mode selected by the user when the remaining battery level is low is desired.

  The CDMA wireless communication apparatus includes a path search unit that performs a path search based on a search parameter that specifies at least one of a path search interval and the number of search target base stations, a default first search parameter, and a user selection A register for storing a second search parameter corresponding to a restriction condition for the user moving speed, and a determination unit that asserts an output signal when it is detected that the remaining battery level has decreased below a threshold value. In response to the assertion of the output signal, a search parameter that is a basis of the path search is changed from the first search parameter to the second search parameter.

  According to at least one embodiment, the wireless communication device can reduce power consumption by shifting to the operation mode selected by the user when the remaining battery level is low.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram illustrating an example of a configuration of a wireless communication device that shifts to an operation mode selected by a user when the remaining battery level is low. 1 includes an A / D converter 11, an automatic gain controller (AGC) 12, a decimation unit 13, a decimation control unit 14, a path search unit 15, a path search control unit 16, a finger unit 17, Finger control unit 18, channel estimation control unit 19, rake receiver 20, turbo decoder 21, and error correction / decoding unit 23 including turbo decoder control unit 22, arithmetic bit number control unit 24, protocol control unit 25, application A CPU 26, a display screen & operation unit 27, a threshold determination unit 28, a threshold remaining amount measuring device 29, and a setting register 30 are included.

  The reception signal received by the antenna is demodulated into a baseband signal by the reception circuit, and this baseband signal is converted into a digital reception signal by the A / D converter 11. The automatic gain controller 12 controls the gain of the digital reception signal output from the A / D converter 11. The decimation unit 13 operates under the control of the decimation control unit 14 and thins out the number of samples of the digital reception signal according to the decimation rate specified by the decimation control unit 14. The path search unit 15 operates under the control of the path search control unit 16 and detects a plurality of paths having different propagation times from the base station to the radio communication apparatus 10 by detecting the timing of the pilot signal in the digital reception signal. To detect. The finger unit 17 operates under the control of the finger control unit 18 and the channel estimation control unit 19. A plurality of N finger units 17 having the same configuration performs despreading processing and channel estimation processing on each of the plurality of paths detected by the path search unit 15 to generate detected received symbols. Received symbols for a plurality of paths output by a plurality of N finger units 17 are combined by the rake receiver 20 at the same timing.

  The error correction / encoding unit 23 performs error correction / decoding on the received symbol output from the rake receiver 20. The error correction / decoding unit 23 includes a turbo decoder 21 and a turbo decoder control unit 22. The turbo decoder 21 operates under the control of the turbo decoder control unit 22 and executes a turbo decoding process on the received symbol. The protocol control unit 25 executes processing for handling data according to the protocol. The arithmetic bit number control unit 24 controls the number of bits used by arithmetic units such as the path search unit 15, the finger unit 17, and the error correction / decoding unit 23.

  The application CPU 26 is a CPU that executes various applications, and provides an interface with the user via the display screen & operation unit 27. The application CPU 26 displays various screens on the display screen & operation unit 27 and receives instructions according to operations such as key input by the user. The threshold remaining amount measuring device 29 detects the remaining amount of the battery built in the wireless communication device 10 based on the output voltage of the battery. The threshold determination unit 28 compares the battery remaining amount detected by the threshold remaining amount measuring device 29 with a predetermined threshold, and asserts an output signal when detecting that the detected battery remaining amount is equal to or less than the threshold. The output signal of the threshold remaining amount measuring device 29 is sent to each control unit (decimation control unit 14, path search control unit 16, finger control unit 18, channel estimation control unit 19, turbo decoder control unit 22, To the arithmetic bit number control unit 24). The output signal of the threshold remaining amount measuring device 29 is also supplied to the application CPU 26.

  The setting register 30 stores a setting table in which various control parameters are defined for different transmission rate values and different moving speed limit values. The control parameters are the number of oversamples referred to by the decimation control unit 14, the path search interval and number of search target base stations referred to by the path search control unit 16, the number of fingers referred to by the finger control unit 18, and the channel estimation control unit 19 The number of average symbols (channel estimation accuracy) to be performed, the number of repetitions of turbo decoding calculation referred to by the turbo decoder control unit 22, and the number of calculation bits of each calculation unit referred to by the calculation bit number control unit 24. Each control unit (decimation control unit 14, path search control unit 16, finger control unit 18, channel estimation control unit 19, turbo decoder control unit 22, arithmetic bit number control unit 24, etc.) is stored in the setting table of the setting register 30. The operation is controlled according to specified control parameters.

  The setting register 30 stores information for specifying the transmission rate selected by the user and / or the limit value of the user moving speed selected by the user. When the remaining battery level is sufficient, each control unit controls the operation based on a default control parameter corresponding to a default transmission rate condition. When the remaining battery level falls below the threshold value, in response to the assertion of the output signal from the threshold value determination unit 28, each control unit selects a parameter that is the basis for operation control from the default control parameter, and the transmission rate selected by the user. And / or change to a control parameter corresponding to the limit value of the user movement speed.

  FIG. 2 is a diagram illustrating an example of a screen displayed on the display screen & operation unit of the wireless communication device when the remaining battery level is low. When the remaining battery level decreases below the threshold value, the application CPU 26 displays a screen as shown in FIG. 2 on the display screen & operation unit 27 in response to the assertion of the output signal from the threshold determination unit 28. The displayed screen displays a selectable transmission rate and speed limit value, and the remaining operation time possible with the current battery level. The remaining operation time is indicated for each displayed transmission rate and speed limit value. For example, in the case of the current default transmission rate (384 kbps), it is indicated that the wireless communication device 10 can be used only for the remaining 30 minutes.

  When the screen as shown in FIG. 2 is displayed, the user operates the operation unit 27b of the display screen & operation unit 27, and a desired transmission rate and / or moving speed limit value used in a state where the remaining battery level is low. Enter the key. At this time, a default transmission rate of 384 kbps may be selected. Information specifying the input transmission rate and / or moving speed limit value is stored in the setting register 30 by the application CPU 26 via the CPU bus. For example, when the user selects the speed limit value 4 km / h, data indicating the speed limit value 4 km / h is stored in the setting register 30. That is, the setting register 30 stores information indicating that the speed limit value selected by the user is 4 km / h. In this case, the remaining operating time is an estimated 35 minutes. For example, when the user selects a transmission rate of 64 kbps, data indicating the transmission rate of 64 kbps is stored in the setting register 30. That is, the setting register 30 stores information indicating that the transmission rate selected by the user is 64 kbps. In this case, the remaining operating time is an estimated 40 minutes.

  When the speed limit value is set by the user, it is not necessary to guarantee normal communication when the user (that is, the wireless communication device 10) moves at a speed higher than the set speed limit. In other words, it is only necessary to guarantee normal communication only for a moving speed that is less than or equal to the set speed limit. In the case of a low movement speed, the frequency and possibility of handover between base stations is reduced, so that the path search interval (time interval) in the path search operation can be shortened and the number of search target base stations can be reduced. . As a result, the power consumption in the path search process can be reduced and the operation time can be extended.

  The transmission rate can be changed, for example, by making the code speed (chip rate) constant and the spreading code length variable. Alternatively, the transmission rate can be changed by making the number of data within a predetermined time variable. The higher the transmission rate, the more difficult it is to receive due to the influence of noise, so it is necessary to execute a higher-accuracy reception process. On the other hand, when communication is performed at a low transmission rate because the remaining battery level is low as described above, a relatively simple and low-accuracy reception process may be executed by changing the control parameter. Since the power consumption of the simple and low-accuracy reception processing is small, the operation time can be extended.

  When the remaining battery level is low and a screen as shown in FIG. 2 is displayed, the user may change the transmission rate and add a speed limit. That is, both a desired transmission rate and a speed limit value may be selected. In this case, for example, when the transmission rate 64 kbps is selected, the remaining operation time is estimated 40 minutes, but when the transmission rate 64 kbps and the speed limit value 4 km / h are selected, an additional 5 minutes is added to 40 minutes. The remaining operating time is 45 minutes.

  The operation of displaying the selectable transmission rate and speed limit value and selecting the desired transmission rate and / or speed limit value as described above may be executed in advance before the remaining battery level becomes low. . That is, when the user inputs an instruction via the operation unit 27b of the display screen & operation unit 27, a selectable transmission rate and speed limit value (a table excluding the remaining working time portion shown in FIG. 2) is displayed. It is displayed on the display screen 27 a of the screen & operation unit 27. While viewing the displayed table, the user operates the operation unit 27b of the display screen & operation unit 27 to key-in a desired transmission rate and / or moving speed limit value. Information specifying the input transmission rate and / or moving speed limit value is stored in the setting register 30 by the application CPU 26 via the CPU bus.

  FIG. 3 is a diagram illustrating an example of a setting table stored in the setting register. In the setting table shown in FIG. 3, various control parameters are defined for different transmission rate values and different moving speed limit values. For example, when the transmission rate of 96 kbps is selected, the number of operating fingers of the finger unit 17 is 7, the number of repetitions of the turbo decoder 21 is 7, the path search interval of the path search unit 15 is 100 ms, the number of search target base stations is 8, and the finger unit 17 The average number of symbols in the channel estimation process is 10 and the number of oversamples in the decimation unit 13 is 4. The number of calculation bits is also as shown in the table. Further, for example, when the speed limit value 4 km / h is selected, the number of operating fingers 6 of the finger unit 17, the number of repetitions 8 of the turbo decoder 21, the path search interval 150 ms of the path search unit 15, and the number of search target base stations 6 The average number of symbols in the channel estimation process of the finger unit 17 is 8, and the number of oversamples of the decimation unit 13 is 2. The number of calculation bits is also as shown in the table.

  Although omitted in FIG. 3, each control parameter may be defined for a combination of each transmission rate and each moving speed limit value. Thereby, it is possible to cope with a case where both a desired transmission rate and a desired speed limit value are selected.

  Hereinafter, processing of each unit of the wireless communication device 10 illustrated in FIG. 1 will be described in detail.

  FIG. 4 is a diagram illustrating an example of the configuration of the path search control unit 16. In FIG. 4, the path search unit 15 includes an MF unit 31, a power generation unit 32, an adder 33, an integration RAM 34, a peak detector 35, and a result register 36. Each part of the path search unit 15 operates under the control of the path search control unit 16. The MF unit 31 detects the position of the pilot signal in the received signal by matched filter processing.

  FIG. 5 is a diagram illustrating an example of the configuration of the MF unit 31. The MF unit 31 is provided with a matched filter for detecting correlation for each of the I component and Q component of the received signal. FIG. 5 shows the configuration of the MF unit 31 corresponding to the I component of the received signal. The configuration of the MF unit 31 for the Q component of the received signal is the same. In FIG. 5, the reception data I stored in the 256-bit shift register 41 is multiplied by the code Code_0 to Code_255 bit by bit by the computing unit 42, and the multiplication results for each bit are summed by the computing unit 43 to obtain a correlation value. It becomes. Here, codes Code_0 to Code_255 are products of a pilot signal and a spreading code, and are equal to an ideal signal pattern of a pilot signal portion in a received signal.

  FIG. 6 is a diagram illustrating a specific configuration of the power generation unit 32, the adder 33, the integration RAM 34, the peak detector 35, and the result register 36. The power generation unit 32 squares the correlation value of the I component and the correlation value of the Q component generated by the MF unit 31 by the multipliers 44 and 45, respectively, and adds the square values by the adder 46. Thereby, a correlation power value is obtained. The adder 33 adds the past correlation power value and the current correlation power value stored in the integration RAM 34 by the calculator 47 and selects either the addition result or the current correlation power value by the selector 48. And stored in the integration RAM 34. By switching the selection of the selector 48 by the output of the N counter 49, the correlation power value stored in the integration RAM 34 becomes a value obtained by accumulating N times. The peak detector 35 compares the peak value of the already detected correlation power stored in the result register 36 with the current correlation power value stored in the integration RAM 34. If the current correlation power value is larger, the past peak is replaced with the current correlation power value. By this update operation, the top M correlation power values detected up to now are detected as peaks. Information indicating the positions of the detected M peaks is supplied to the finger unit 17 as synchronization position information for the M paths.

  FIG. 7 is a diagram for explaining the update of the path search result. The upper part of FIG. 7 is the previous path search result, and four paths 1 to 4 are detected. The horizontal axis shows temporal timing, and the vertical axis shows the correlation power value. The lower part of FIG. 7 shows the current path search result, and four paths 1 to 4 are detected. In the current path search result with respect to the previous path search result, the previous path 1 disappears and a new path 1 appears. Also, the previous path 4 disappears and a new path 4 appears. Since the timing difference between the previous path 3 and the current path 3 is smaller than the reference timing (1/4 chip), it follows that it is the same path. That is, for the path 3, the despreading process is executed at the same timing in the previous time and this time. Note that the path 1 and the path 4 are treated as path disappearance and generation as described above because the distance between the current path timing and the closest previous path timing is equal to or greater than the reference timing.

  FIG. 8 is a diagram illustrating the path search interval and the number of path search target base stations. In FIG. 8, the horizontal axis represents time. (A) shows an operation control signal that defines the operation timing of the path search, and (b) shows a search target base station and a search operation. The path search is sequentially executed only while the operation control signal is HIGH. In this example, the path search is executed once every 100 ms. This one pass search period is 80 ms. The search for one base station is completed in 10 ms, and eight base stations BS # 1 to BS # 8 are searched in a path search period of 80 ms. At this time, in the search for each base station, the path search unit 15 described above detects a plurality of paths for one base station. The synchronous position information supplied to the finger unit 17 is only for the currently communicating base station.

  The path search control unit 16 controls the path search operation of the path search unit 15 in accordance with the operation control signal shown in FIG. Specifically, when the operation control signal rises, path search for a plurality of search target base stations is sequentially executed, and when the operation control signal falls, the path search is interrupted.

  FIG. 9 is a diagram illustrating an example of a configuration of an interval / base station number control unit that is a part of the path search control unit 16. The interval / base station number control unit 16A includes a timer value conversion circuit 51, an adder 52, a coincidence comparison circuit 53, a set value reflection register 54, a search time counter 55, and an operation control signal generation unit 56. At the start of operation, the path search control unit 16 takes in a default path search interval value and the number of search target base stations from the setting register 30. The path search interval value is converted into a timer value by the timer value conversion circuit 51 and stored in a register inside the timer value conversion circuit 51. The number of search target base stations is stored in the set value reflection register 54.

  The timer value indicating the path search interval stored in the timer value conversion circuit 51 is added to the global timer value GTM at that time by the adder 52 at the initial timing. The addition result is held at the same value until the adder 52 is instructed to re-add. This addition result is a counter value indicating the timing after the path search interval from the initial timing. The coincidence comparison circuit 53 compares the current global timer value GTM with the addition result. When the two match, the match comparison circuit 53 asserts an output signal. In response to the assertion of the output of the coincidence comparison circuit 53, the operation control signal generator 56 changes the operation control signal from LOW to HIGH. As described above, in response to the rising of the operation control signal to HIGH, the path search unit 15 starts the path search operation, and sequentially executes the path search for each base station.

  Further, the search time counter 55 starts the time counting operation by the counter in response to the assertion of the output of the coincidence comparison circuit 53. When the counter value reaches a value corresponding to the number of base stations indicated by the set value reflection register 54, the search time counter 55 asserts a count end signal. That is, for example, as in the example of FIG. 8, when the number of base stations to be searched is 8, the search time counter 55 asserts a count end signal when 80 ms elapses.

  In response to the assertion of the count end signal from the time counter 55, the operation control signal generator 56 switches the operation control signal from HIGH to LOW. Thereby, the path search operation of the path search unit 15 ends. That is, the path search unit 15 ends the path search operation after searching the number of base stations designated by the number of search target base stations fetched from the setting register 30.

  In response to the assertion of the output of the coincidence comparison circuit 53, the adder 52 adds the timer value indicating the path search interval of the timer value conversion circuit 51 and the global timer value GTM, and compares the addition result with a coincidence comparison. This is supplied to the circuit 53. The addition value output from the adder 52 is held at the same value until the output from the coincidence comparison circuit 53 is asserted next time and re-addition is instructed. The next time the output of the coincidence comparison circuit 53 is asserted is the timing after the pass search interval from the current assertion, and in response to this asserted state, the operation control signal rises to HIGH as described above. Therefore, the path search unit 15 executes the path search operation at an interval specified by the path search interval value fetched from the setting register 30.

  The value of the timer value conversion circuit 51 and the value of the set value reflection register 54 are updated every time the output of the coincidence comparison circuit 53 is asserted. At this time, normally, since the default path search interval value and the number of search target base stations are fetched from the setting register 30, the path search interval and the number of search target base stations do not change.

  As described above, the output of the threshold determination unit 28 shown in FIG. 1 is supplied to the path search control unit 16. When the remaining battery level decreases below the threshold value and the output signal from the threshold value determination unit 28 is asserted, the path search control unit 16 responds to the assertion by the path search control unit 16 from the setting register 30 according to the user-selected path search interval value and search target. Capture the number of base stations. That is, the path search interval value and the number of search target base stations corresponding to the user moving speed restriction condition selected by the user are captured. The path search interval value is converted into a timer value by the timer value conversion circuit 51 and stored in a register inside the timer value conversion circuit 51. The number of search target base stations is stored in the set value reflection register 54. As a result, when the remaining battery level falls below the threshold value, the path search is executed from the next path search with the path search interval and the number of search target base stations corresponding to the user-specified speed limit.

  Note that it is not always necessary to be able to change both the path search interval and the number of search target base stations, and it may be configured such that either one of the path search interval or the number of search target base stations can be changed. That is, as a search parameter (control parameter) corresponding to the user moving speed limit condition, both the path search interval and the number of search target base stations are not specified, but the path search interval and the number of search target base stations are not specified. One may be specified. Of course, both of the path search interval and the number of search target base stations may be specified as the search parameters (that is, both the parameter specifying the path search interval and the parameter specifying the number of search target base stations are specified. May be good).

  FIG. 10 is a diagram illustrating an example of the configuration of the finger unit 17. FIG. 10 shows one of a plurality of finger portions 17 corresponding to a plurality of paths. The finger unit 17 includes code generators 61 and 62, computing units 63 and 64 for accumulation, computing units 65 and 66 for addition, selectors 67 and 68, buffers 69 and 70, a despreading control unit 71, a register 72, and for addition. The computing unit 73, the complex conjugate unit 74, and the integrating computing unit 75 are included. The input received data is supplied to a data signal path and a pilot signal path. The register 72, the arithmetic unit 73, the complex conjugate unit 74, the arithmetic unit 75, and the like constitute a channel estimation unit 76.

  In the data signal path, the spread code generated by the code generator 61 is added to the received data (digital received signal) by the counter 63 to perform despreading. At this time, the timing for multiplying the codes is the timing at which the synchronization position information detected by the path search unit 15 instructs the path processed by the finger unit 17. The addition computing unit 65 adds the past despread data value stored in the buffer 69 and the current despread data value. Either the addition result or the current data value after despreading is selected by the selector 67 and stored in the buffer 69. By switching the selection of the selector 67 by the despreading control unit 71, the data value integrated for a period equal to the data symbol length is stored in the buffer 69. This integration process suppresses noise components having a period shorter than the data period. The restored data restored by the despreading process is supplied from the buffer 69 to the calculator 75 of the channel estimation unit 76.

  In the pilot signal path, the code generator 62, the integration computing unit 64, the addition computing unit 66, the selector 68, the buffer 70, and the despreading control unit 71 execute the same processing as the above data signal path. To do. As a result, a value obtained by canceling a known pilot pattern and extracting a transmission line component is stored in the buffer 70 as a normalized pilot symbol independent of the pilot pattern. This pilot symbol is supplied to the register 72 of the channel estimation unit 76.

  In the channel estimation unit 76, a plurality of pilot symbols stored in the register 72 are added by the computing unit 73 and averaged to generate a channel estimation value. The complex conjugate unit 74 generates a complex conjugate of the generated channel estimation value. The computing unit 75 corrects the phase shift in the transmission path by multiplying the restored data signal by the complex conjugate of the channel estimation value generated by the complex conjugate unit 74.

  The processing of the finger unit shown in FIG. 10 is executed by each of the plurality of N finger units 17 shown in FIG. The finger control unit 18 refers to the default number of fingers in the setting register 30 in the normal state, and operates the finger units 17 having the default number. When the remaining battery level decreases below the threshold and the output signal from the threshold determination unit 28 is asserted, the finger control unit 18 refers to the number of fingers selected by the user stored in the setting register 30 in response to the assertion. Then, the number of finger units 17 corresponding to the user selection is operated.

  FIG. 11 is a configuration diagram showing a detailed configuration of the channel estimation unit 76. FIG. 11 shows a configuration capable of controlling the average number of symbols when obtaining the channel estimation value. When, for example, 10 pilot symbols stored in the register 72 are added and averaged by the arithmetic unit 73, the number of symbols used in the averaging process (average symbol number) can be controlled by the mask unit 77. The mask unit 77 functions to mask some symbols supplied from the register 72 to the computing unit 73 to reduce the average number of symbols. For example, when the channel estimation control unit 19 specifies 6 as the average number of symbols, the mask unit 77 masks (cuts off) 4 out of 10 pilot symbols stored in the register 72 and the remaining 6 symbols. Only to the calculator 73.

  The channel estimation control unit 19 refers to the default average number of symbols in the setting register 30 in the normal state, and controls the mask unit 77 so as to average the symbols of this default number. When the remaining battery level decreases below the threshold and the output signal from the threshold determination unit 28 is asserted, in response to the assertion, the channel estimation control unit 19 calculates the average number of symbols selected by the user stored in the setting register 30. Referring to this, mask section 77 is controlled so as to average the number of symbols corresponding to this user selection.

  FIG. 12 is a diagram illustrating an example of the configuration of the turbo decoder 21. The turbo decoder 21 includes a decoder 81, a decoder 82, an interleaver 83, an interleaver 84, and an output control unit 85. An information bit sequence ya and check bit sequences yb and yc are transmitted from the transmission side, and after noise is superimposed on the communication path, received symbols ya, yb and yc mixed with errors are input to the turbo decoder 21.

  The decoder 81 decodes the information bit sequence ya and the check bit sequence yb based on the reliability information of the previous stage supplied from the interleaver 84 (giving an appropriate initial value for the first decoding process) and its result Output trust information. The information bit sequence ya and the reliability information obtained by the decoder 81 are rearranged by the interleaver 83 in the order of the check bit yc. The decoder 82 outputs the decoding result of the information bit sequence ya and the check bit sequence yc and the reliability information based on the information bit sequence ya and the reliability information thereof rearranged by the interleaver 83 and the check bit sequence yc. To do. The reliability information obtained by the decoder 82 is returned to the original order by the interleaver 84 and supplied to the decoder 81. After repeating this process several times, the final decoding result is output via the output control unit 85. The number of repetitions and the decoding result output are controlled by the turbo decoder control unit 22.

  The turbo decoder control unit 22 refers to the default number of repetitions of the setting register 30 in the normal state, and controls the turbo decoder 21 so as to repeat the decoding process by this default number of times and output the result. When the remaining battery level falls below the threshold value and the output signal from the threshold value determination unit 28 is asserted, in response to the assertion, the turbo decoder control unit 22 sets the number of repetitions by user selection stored in the setting register 30. Referring to this, turbo decoder 21 is controlled so that the decoding process is repeated a number of times according to this user selection and the result is output.

  FIG. 13 is a diagram showing a mechanism for controlling the number of arithmetic bits of the arithmetic unit. As shown in FIG. 13, AND circuits 92 to 95 are provided for masking the lower 2 bits of each data in a path for supplying 8-bit data D1 and D2 to the arithmetic unit 91, respectively. The upper 6 bits of each data are supplied to the calculator 91 as they are. The calculator 91 is, for example, an adder or an integrator, and outputs a result obtained by calculating the data D1 and the data D2.

  In the default state, the signals M1 and M2 supplied to the AND circuits 92 to 95 are set to HIGH, and all 8 bits of the data D1 and D2 are supplied to the arithmetic unit 91. When it is desired to reduce the number of operation bits by 1, the signal M1 is set to LOW and the signal M2 is set to HIGH. Thereby, the outputs of the AND circuits 92 and 94 can be fixed to LOW, and only the upper 7 bits of the data D1 and D2 can be supplied to the arithmetic unit 91. If the number of operation bits is to be further reduced by 1, the signals M1 and M2 are set to LOW. As a result, the outputs of the AND circuits 92 to 95 can be fixed to LOW, and only the upper 6 bits of the data D1 and D2 can be supplied to the arithmetic unit 91. Since the masked bit value is fixed to LOW, the number of signal lines whose signal level transitions in the computing unit 91 can be reduced to reduce power consumption.

  Such operation bit number control is performed by the operation bit number control unit 24. Each arithmetic unit in the path search unit 15, each arithmetic unit in the finger unit 17, and each arithmetic unit in the decoder of the error correction / decoding unit 23 is provided with a mask function as shown in FIG. The number control unit 24 controls the number of calculation bits of each calculator.

  The arithmetic bit number control unit 24 refers to the default arithmetic bit number for each arithmetic unit defined in the setting register 30 in the normal state, and controls each arithmetic unit so that the arithmetic operation is performed with the default bit number. . When the remaining battery level decreases below the threshold value and the output signal from the threshold value determination unit 28 is asserted, the operation bit number control unit 24 responds to the assertion and the operation bit number stored in the setting register 30 is selected by the user. Referring to FIG. 4, each arithmetic unit is controlled so as to perform an operation with the number of bits according to the user selection. In the setting table of the setting register 30 shown in FIG. 3, the finger 1 indicates the first one of the plurality of finger units 17, and the calculators 1 to 6 of the finger 1 are the calculators 63, 64, 65, 66, 75, and 73, respectively. The path search computing units 1 to 6 correspond to the computing unit 42 and computing unit 43 in FIG. 5, the computing units 44 and 45, the computing unit 46, the computing unit 47, and the computing unit (peak detector) 35 in FIG.

  Furthermore, the radio communication apparatus 10 shown in FIG. 1 is configured to control the number of oversamples of the decimation unit 13 by the decimation control unit 14. The decimation control unit 14 refers to the default number of oversamples in the setting register 30 in the normal state, and controls the decimation unit 13 so that the number of oversamples is equal to the default number of oversamples. When the remaining battery level falls below the threshold and the output signal from the threshold determination unit 28 is asserted, in response to the assertion, the decimation control unit 14 refers to the number of oversamples selected by the user stored in the setting register 30. Then, the decimation unit 13 is controlled so that the number of oversamples according to the user selection is obtained.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the said Example, A various deformation | transformation is possible within the range as described in a claim.

The present invention includes the following contents.
(Appendix 1)
A path search unit that performs a path search based on a search parameter that specifies at least one of a path search interval and the number of base stations to be searched;
A register for storing a default first search parameter and a second search parameter corresponding to a user moving speed restriction condition selected by the user;
A determination unit that asserts an output signal when it is detected that the remaining battery level has fallen below a threshold value, and in response to assertion of the output signal from the determination unit, a search parameter that is the basis of the path search is A CDMA wireless communication apparatus, wherein the search parameter is changed from one search parameter to the second search parameter.
(Appendix 2)
A demodulator for demodulating with a predetermined first number of fingers, wherein the register stores a second number of fingers corresponding to a transmission rate value selected by the user, and the output signal from the determination unit; The wireless communication apparatus according to appendix 1, wherein the number of fingers of the demodulator is changed from the first number of fingers to the second number of fingers in response to the assertion of.
(Appendix 3)
An arithmetic unit for calculating with a predetermined first number of bits is further included. The register stores a second number of bits corresponding to the transmission rate value selected by the user, and the output signal from the determination unit The wireless communication apparatus according to appendix 1, wherein the number of bits of the computing unit is changed from the first number of bits to the second number of bits in response to the assertion.
(Appendix 4)
A turbo decoder that performs turbo decoding at a predetermined first number of iterations, wherein the register stores a second number of iterations corresponding to a transmission rate value selected by a user; The wireless communication apparatus according to appendix 1, wherein the number of repetitions of the turbo decoder is changed from the first number of repetitions to the second number of repetitions in response to assertion of the output signal.
(Appendix 5)
The wireless communication apparatus according to appendix 1, wherein the search parameter specifies both a path search interval and the number of search target base stations.
(Appendix 6)
A channel estimation unit for estimating a channel with a predetermined first channel estimation accuracy, wherein the register stores a second channel estimation accuracy corresponding to a transmission rate value selected by the user; The wireless communication apparatus according to claim 1, wherein the channel estimation accuracy of the channel estimation unit is changed from the first channel estimation accuracy to the second channel estimation accuracy in response to the assertion of the output signal.
(Appendix 7)
A decimation unit that operates at a predetermined first oversample number, wherein the register stores a second oversample number corresponding to a transmission rate value selected by a user, and the output from the determination unit; The wireless communication apparatus according to appendix 1, wherein the number of oversamples of the decimation unit is changed from the first oversample number to the second oversample number in response to signal assertion.
(Appendix 8)
The wireless communication device according to any one of appendices 1 to 7, wherein the wireless communication device is configured to display a remaining operation time in response to assertion of the output signal from the determination unit.

It is a figure which shows an example of a structure of the radio | wireless communication apparatus which transfers to the operation mode which the user selected when the battery remaining charge decreases. It is a figure which shows an example of the screen displayed on the display screen & operation unit of a radio | wireless communication apparatus when a battery remaining charge reduces. It is a figure which shows an example of the setting table stored in a setting register. It is a figure which shows an example of a structure of a path search control part. It is a figure which shows an example of a structure of MF part. It is a figure shown about the specific structure of a power generation part, an adder, integration RAM, a peak detector, and a result register. It is a figure for demonstrating the update of a path search result. It is a figure explaining the path search interval and the number of path search target base stations. It is a figure which shows an example of a structure of the space | interval and base station number control part which is a part of path search control part. It is a figure which shows an example of a structure of a finger part. It is a block diagram which shows the detailed structure of a channel estimation part. It is a figure which shows an example of a structure of a turbo decoder. It is a figure which shows the mechanism which controls the number of calculation bits of an arithmetic unit.

Explanation of symbols

10 wireless communication device 11 A / D converter 12 automatic gain controller (AGC)
13 Decimation Unit 14 Decimation Control Unit 15 Path Search Unit 16 Path Search Control Unit 17 Finger Unit 18 Finger Control Unit 19 Channel Estimation Control Unit 20 Rake Receiver 21 Turbo Decoder 22 Turbo Decoder Control Unit 22 Correction / Decoding Unit 24 Operation Bit number control unit 25 Protocol control unit 26 Application CPU
27 Display Screen & Operation Unit 28 Threshold Determination Unit 29 Threshold Remaining Meter 30 Setting Register

Claims (5)

A path search unit that performs a path search based on a search parameter that specifies at least one of a path search interval and the number of base stations to be searched;
A register for storing a first search parameter and a second search parameter corresponding to a user moving speed restriction condition selected by the user;
A determination unit that asserts an output signal when it is detected that the remaining battery level has fallen below a threshold value, and in response to assertion of the output signal from the determination unit, a search parameter that is the basis of the path search is A wireless communication apparatus, wherein the search parameter is changed from one search parameter to the second search parameter.   A demodulator for demodulating with a predetermined first number of fingers, wherein the register stores a second number of fingers corresponding to a transmission rate value selected by the user, and the output signal from the determination unit; The radio communication apparatus according to claim 1, wherein the number of fingers of the demodulator is changed from the first number of fingers to the second number of fingers in response to assertion of.   An arithmetic unit for calculating with a predetermined first number of bits is further included. The register stores a second number of bits corresponding to the transmission rate value selected by the user, and the output signal from the determination unit 3. The wireless communication apparatus according to claim 1, wherein the number of bits of the arithmetic unit is changed from the first number of bits to the second number of bits in response to the assertion.   A turbo decoder that performs turbo decoding at a predetermined first number of iterations, wherein the register stores a second number of iterations corresponding to a transmission rate value selected by a user; 4. The radio according to claim 1, wherein the number of repetitions of the turbo decoder is changed from the first number of repetitions to the second number of repetitions in response to assertion of an output signal. 5. Communication device.   A channel estimation unit for estimating a channel with a predetermined first channel estimation accuracy, wherein the register stores a second channel estimation accuracy corresponding to a transmission rate value selected by the user; 5. The channel estimation accuracy of the channel estimation unit is changed from the first channel estimation accuracy to the second channel estimation accuracy in response to the assertion of the output signal of claim 1. The wireless communication device according to claim 1.

Images