JP4601862B2 - Wireless communication terminal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio communication terminal used in a mobile communication system adopting, for example, a CDMA (Code Division Multiple Access) system.
[0002]
[Prior art]
In general, in a mobile communication system employing a CDMA system, a base station intermittently transmits synchronization establishment data at a predetermined cycle, and the synchronization establishment data is based on a reception target timing generated by the mobile communication terminal itself. And synchronization with the base station is established based on the reception timing. In this way, even when the mobile communication terminal is operating with an asynchronous clock independent of the base station, multipath fading occurs in which the synchronization state between the base station and the mobile communication terminal occurs on the wireless transmission path. Even in the case of being affected by the above, it is possible to maintain the synchronization state between the mobile communication terminal and the base station.
[0003]
By the way, in order to reduce power consumption, the mobile communication terminal adopts a so-called intermittent reception method in which the reception system is operated only during the arrival period of the data for establishing synchronization and inactive during other periods during standby. is doing. However, the timing at which this intermittent reception is performed is controlled based on a clock generated independently by the mobile communication terminal, and therefore may be shifted from the timing of synchronization establishment data coming from the base station. If this shift in reception timing becomes large, the data for establishing synchronization cannot be accurately received, and in the worst case, the synchronization is lost, which is very undesirable.
[0004]
Therefore, conventionally, a sufficiently wide reception period is set in consideration of the predicted amount of intermittent reception timing deviation.
FIG. 8 is a timing chart showing an example. As shown in the figure, the mobile communication terminal obtains the margin Tm in consideration of the timing error Tb between the reception target timing t2 generated by the terminal itself and the actual reception timing t1 of the synchronization establishment data DS. The margin Tm is added before and after the data length Ta of the synchronization establishment data DS to obtain a reception period (Ta + 2Tm), and the reception system is operated only from the reception start timing t3 during the reception period (Ta + 2Tm). . In this way, it is possible to normally receive the synchronization establishment data DS even if the reception target timing t2 is slightly shifted due to a difference in clock accuracy.
[0005]
[Problems to be solved by the invention]
However, in general, in a mobile communication terminal, in order to reduce power consumption as much as possible, during the standby period, the operation of the high-speed clock oscillator with high power consumption is stopped and the low-speed clock oscillator is operated. The reception target timing t2 and the reception period (Ta + 2Tm) are also generated based on this low-speed clock.
[0006]
In general, low-speed clock oscillators are prioritized for low cost and low power consumption, and an inaccurate oscillator having no temperature compensation function is used. For this reason, the amount of deviation of the intermittent reception timing becomes large, and in order to absorb this amount of deviation, it is necessary to set the margin Tm further large and sufficiently increase the reception period (Ta + 2Tm).
[0007]
However, if the reception period is set longer in this way, the operation time of the reception system becomes longer correspondingly, resulting in an increase in power consumption, and the effect of reducing power consumption due to intermittent reception cannot be obtained sufficiently.
[0008]
The present invention has been made paying attention to the above circumstances, and its purpose is to accurately receive data for establishing synchronization without increasing power consumption during standby even when a low-accuracy clock oscillator is used. Accordingly, an object of the present invention is to provide a wireless communication terminal having high synchronization holding performance, low power consumption, and low cost.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention receives data for establishing synchronization intermittently transmitted from a wireless transmission device at a predetermined cycle, and synchronizes with the wireless transmission device based on the reception timing. In the wireless communication terminal to be established,
Receiving target timing generating means for generating a receiving target timing in a period corresponding to the transmission period of the synchronization establishment data based on a reference clock generated by the clock oscillator, and each receiving target generated by the receiving target timing generating means In addition to receiving means for setting the receiving period of a predetermined width on the basis of the timing and performing the receiving operation of the data for establishing synchronization in this receiving period, temperature detecting means for detecting the ambient temperature of the clock oscillator, And timing correction means.
[0010]
In this timing correction means, an error between the reception target timing generated by the reception target timing generation means and the actual reception timing of the synchronization establishment data received by the reception means is obtained. The reception target timing generated by the reception target timing generation means is corrected based on this error and the temporal change in the ambient temperature of the clock oscillator detected by the temperature detection means.
[0011]
Therefore, according to the present invention, even if the clock oscillator has temperature characteristics, the temperature change is detected and the detection result is reflected in the determination of the reception target timing of the next period. For this reason, it becomes possible to generate a reception target timing compensated for temperature, thereby reducing a margin for absorbing a timing error between the reception target timing and the actual reception timing and shortening the reception period. Become. As a result, it is possible to reduce the power consumption of the reception system related to the intermittent reception operation while keeping the reception quality of the data for establishing synchronization high, thereby enabling the radio communication terminal to have high synchronization holding performance and low power consumption. Can be provided.
[0012]
The following two configurations can be considered as the timing correction means.
That is, first, the first configuration is the actual reception timing of the synchronization establishment data received during the reception period set with reference to the reception target timing in the current period generated by the reception target timing generation means. And the temperature difference between the ambient temperature in the current cycle detected by the temperature detection means and the ambient temperature one cycle before that is calculated. Then, based on the calculated timing error and temperature difference, the reception target timing generation means corrects the reception target timing generated in the next cycle.
[0013]
On the other hand, in the second configuration, the reception target timing in the current period generated by the reception target timing generation means and the actual reception timing of the synchronization establishment data received in the reception period set with reference to the reception target timing. While calculating the error, the transition of the ambient temperature of the clock oscillator in the period from the reception target timing one cycle before to the reception target timing in the current cycle is obtained based on the detection output of the temperature detection means. Based on the calculated timing error and temperature transition, the reception target timing generation means corrects the reception target timing generated in the next cycle.
[0014]
According to the first configuration, the temperature compensation can be performed only by detecting the ambient temperature of the clock oscillator at each reception target timing, so that it can be realized by a relatively simple process.
[0015]
On the other hand, according to the second configuration, since the temperature transition between the reception target timings is reflected in the determination of the reception target timing in the next cycle, it is possible to compensate for the influence of complicated temperature fluctuations that occur between the reception target timings. Thus, more accurate temperature compensation can be realized.
[0016]
According to the present invention, in the timing correction means, at least one of an upper limit value and a lower limit value of the correction amount of the reception target timing is set. Then, the correction amount of the reception target timing calculated based on the error between the reception target timing and the actual reception timing of the data for establishing synchronization and the temporal change of the ambient temperature detected by the temperature detecting means is set as described above. Compare with the upper or lower limit. As a result of this comparison, if the calculated correction amount exceeds the upper limit value or falls below the lower limit value, the reception target timing of the next cycle is corrected based on the upper limit value or lower limit value. Also features.
[0017]
In general, the error between the target reception timing and the actual reception timing of the data for establishing synchronization includes components due to multipath fading temporarily generated on the wireless transmission path in addition to components due to accuracy and temperature characteristics of the clock oscillator itself. included. For this reason, if the calculated value of the error becomes an abnormal value, if this error is corrected as it is, the temporary error component due to the multipath fading or the like is erroneously corrected as a stationary error. In other words, the reception target timing and the reception period in the next period are erroneously set, which is extremely undesirable.
[0018]
In contrast, in the present invention, as described above, when the correction amount calculated based on the error exceeds the preset upper limit value or falls below the lower limit value, the cause is other than the accuracy and temperature characteristics of the clock oscillator itself. And the correction amount is set to the above upper limit value or lower limit value. For this reason, a problem that a temporary error component due to multipath fading or the like is corrected as a steady error component is prevented, and thus it is possible to always set the reception target timing and the reception period in the next cycle correctly.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 is a circuit block diagram showing a configuration of a CDMA mobile communication terminal which is a first embodiment of a radio communication terminal according to the present invention.
[0020]
A radio signal transmitted from a base station (not shown) is received by the antenna 11 and then input to the radio unit 1. The radio unit 1 inputs the radio signal to the reception circuit (RX) 13 through the antenna duplexer 12 (DUP), and mixes it with the reception local oscillation signal output from the frequency synthesizer (SYN) 14 in the reception circuit 13. The frequency is converted to an intermediate frequency signal. The frequency of the reception local oscillation signal generated from the frequency synthesizer 14 is set by a control signal SYC output from the control unit 5.
[0021]
The received intermediate frequency signal is input to the CDMA signal processing unit 2. The CDMA signal processing unit 2 first despreads the received intermediate frequency signal using a spreading code assigned to the receiving channel, and then performs quadrature demodulation corresponding to, for example, a QPSK (Quadriphase Phase Shift Keying) modulation method. The demodulated data is converted into a predetermined format corresponding to the data rate. The converted demodulated data is input to the compression / decompression processing unit 3.
[0022]
The compression / decompression processing unit 3 performs a decompression process on the demodulated data output from the CDMA signal processing unit 2 according to the reception data rate notified from the control unit 5, and then performs a decoding process using Viterbi decoding or the like In addition, error correction decoding processing is performed to reproduce baseband received voice data or received packet data. The received voice data is output to the PCM code processing unit 4, and the received packet data such as e-mail is output to the control unit 5.
[0023]
The PCM code processing unit 4 performs PCM decoding on the received voice digital data output from the compression / decompression processing unit 3 and outputs an analog received signal. The analog reception signal is amplified by the reception amplifier 41 and then output from the speaker 42.
[0024]
The control unit 5 depackets the received packet data such as e-mail output from the compression / decompression processing unit 3 and stores it in the storage unit 53, and also reads out and displays the received packet data from the storage unit 53 according to the display operation of the user by the input unit 51. Displayed on the unit 52. When a personal computer such as a notebook personal computer is connected to the mobile communication terminal, the received packet data can be output to the personal computer via an external interface (not shown).
[0025]
On the other hand, the speaker's input voice signal input to the microphone 43 during voice communication is amplified to an appropriate level by the transmission amplifier 44, and then subjected to PCM encoding processing by the PCM code processing unit 4 to transmit the transmission voice. The data is input to the compression / decompression processing unit 3 as data. Further, packet data such as e-mail created by the control unit 5 is input from the control unit 5 to the compression / decompression processing unit 3.
[0026]
At the time of voice communication, the compression / decompression processing unit 3 detects the energy amount of the input voice from the transmission voice data output from the PCM code processing unit 4, and determines the data rate based on the detection result. Then, the transmission audio data is compressed into a signal of a format corresponding to the data rate, and further subjected to error correction coding processing, and then output to the CDMA signal processing unit 2. On the other hand, at the time of packet data transmission, the transmission packet data output from the control unit 5 is subjected to error correction coding processing and output to the CDMA signal processing unit 2.
[0027]
The CDMA signal processing unit 2 performs, for example, QPSK modulation on the carrier signal with the transmission data compressed in the compression / decompression processing unit 3, and uses the PN code assigned to each transmission channel for the modulated carrier signal. Apply spread spectrum processing. Then, the spread coded transmission signal is output to the transmission circuit (TX) 15 of the radio unit 1.
[0028]
The transmission circuit 15 synthesizes the spread coded transmission signal with a transmission local oscillation signal generated from the frequency synthesizer 14 and converts the frequency into a radio frequency signal. Then, the transmission circuit 15 amplifies only the effective portion of the radio frequency signal based on the transmission data rate notified by the control unit 5 and outputs it as a transmission radio frequency signal. The transmission radio frequency signal output from the transmission circuit 15 is supplied to the antenna 11 via the antenna duplexer 12, and is transmitted from the antenna 11 toward the connected base station.
[0029]
The input unit 51 is provided with a key group such as a dial key, a call key, a power key, an end key, a volume control key, and a mode designation key. The display unit 52 is provided with an LCD display and an LED lamp. The LCD display displays the telephone number of the communication partner terminal, the operating state of the terminal itself, and sent / received mails. The LED lamp is used to display the discharge state of the battery 71. Reference numeral 7 denotes a power supply unit. The power supply circuit 72 generates a predetermined operating power supply voltage Vcc based on the output of the battery 71 and supplies it to each circuit unit.
[0030]
The mobile communication terminal also includes a timing circuit 6. The timing circuit 6 generates a reference clock having a predetermined speed, and supplies the reference clock to each circuit unit in the terminal that requires an operation clock including the control unit 5.
[0031]
By the way, this mobile communication terminal has a function for establishing and maintaining synchronization with a base station while performing an intermittent reception operation during a standby period. FIG. 2 is a circuit block diagram showing a configuration for realizing the synchronization establishment maintaining function. The same parts as those in FIG. 1 are denoted by the same reference numerals.
[0032]
The CDMA signal processing unit 2 includes a reception timing generation unit 21, and the control unit 5 includes a timing error adjustment unit 54 and a temperature information management unit 55. The timing circuit 6 includes a high-speed clock oscillator 61, a low-speed clock oscillator 62, and a temperature detector 63.
[0033]
The high-speed clock oscillator 61 generates a high-accuracy and high-frequency clock CLK1 having a temperature compensation function, and supplies the high-speed clock CLK1 to the reception timing generation unit 21, the timing error adjustment unit 54, and the temperature information management unit 55, respectively. To do. The high-speed clock oscillator 61 is highly accurate but consumes a large amount of power.
[0034]
On the other hand, the low-speed clock oscillator 62 generates a clock CLK2 having a lower frequency and lower accuracy than the high-speed clock oscillator 61. The low-speed clock CLK2 is generated by the reception timing generation unit 21, the timing error adjustment unit 54, and the temperature information management unit. 55 respectively. The low-speed clock oscillator 62 does not have a temperature compensation function and has a lower accuracy than the high-speed clock oscillator 61, but has low power consumption and low price, and always operates.
[0035]
The temperature detector 63 is provided for detecting the ambient temperature of the low-speed clock oscillator 62 and supplies the temperature detection data TM to the temperature information management unit 55.
[0036]
The temperature information management unit 55 takes in the temperature detection data from the temperature detector 63 when the reception start timing notification RS is given from the reception timing generation unit 21. Then, a temperature difference between the detected temperatures is calculated based on the temperature detection data acquired in the current cycle and the temperature detection data acquired in the previous cycle, and the calculated temperature difference data is used as temperature change information TC. The timing error adjustment unit 54 is notified.
[0037]
In response to the arrival of the synchronization timing information ST from the radio unit 1, the timing error adjustment unit 54 receives the reception timing error based on the temperature change information TC and the temperature characteristics of the temperature detector 63 itself stored in advance. An upper limit value and a lower limit value are calculated.
[0038]
Also, calculate the error between the target reception timing and the actual reception timing (synchronization timing) of the data for establishing synchronization, and determine whether this timing error is within the range between the upper limit value and the lower limit value. To do. If it falls within the range, the timing error is directly supplied to the reception timing generator 21 as timing error information TG. On the other hand, this upper limit value is selected when the upper limit value is exceeded, and this lower limit value is selected when it is below the lower limit value, and this is given to the reception timing generation unit 21 as timing error information TG.
[0039]
In response to the arrival of the synchronization timing information ST from the radio unit 1, the reception timing generation unit 21 receives the synchronization target data reception target timing of the next period based on the synchronization timing, reception period information, and timing error information TG. To decide. Then, the reception start timing is determined from the reception target timing and the reception period. Thereafter, the reception timing generation unit 21 monitors whether or not the reception start timing has been reached by mainly counting the low-speed clock CLK2, and notifies the radio unit 1 of the reception start timing information RS when the reception start timing is reached. At the same time, by adding a predetermined margin to the data length for synchronization establishment, a reception period serving as a reception window for the data for synchronization establishment is set, and this reception period is notified to the radio unit 1 as reception period designation information RW.
[0040]
Next, a synchronization establishment maintaining operation and a reception timing control operation for the synchronization establishment operation in the mobile communication terminal configured as described above will be described.
[0041]
First, when the wireless unit 1 shifts to the intermittent reception mode in the standby state, the wireless unit 1 performs the intermittent reception operation as follows. FIG. 3 is a flowchart showing the procedure and contents. The intermittent reception operation is continuously performed until the intermittent reception mode is canceled.
[0042]
That is, when the wireless reception unit 1 shifts to the intermittent reception mode, the wireless unit 1 normally stops the reception operation and waits for reception start timing information RS from the reception timing generation unit 21 in this state (step ST301). Then, when the reception start timing information RS is notified from the reception timing generation unit 21, the reception period specification information RW notified from the reception timing generation unit 21 is fetched, a timer is started in step ST302, and this reception period specification information is received. The timing of the reception period indicated by RW is started. Thereafter, in step ST303, the reception operation of the synchronization establishment data SD is started. In addition, the wireless unit 1 monitors the timer time-up in step ST304 while performing the reception operation. When the timer expires, it is determined that the reception period has ended, and the reception operation is stopped (step ST305).
[0043]
In step ST306, after the reception operation is stopped, the wireless unit 1 calculates the reception timing (start timing) of the data for establishing synchronization based on the reception result in the current cycle, and receives the synchronization timing information ST indicating the reception timing as the reception timing. It outputs to the production | generation part 21 and the timing error production | generation part 54 (step ST307). When the output of the synchronization timing information ST is completed, the radio unit 1 ends the processing related to the reception timing in this cycle, and returns to step ST301.
[0044]
Now, when the synchronization timing information ST is given from the radio unit 1, the reception timing generation unit 21 performs an operation to be described later using the synchronization timing information ST as a trigger. Prior to the description of this operation, the temperature information management unit 55 and The operation of the timing error adjustment unit 54 will be described. FIG. 4 and FIG. 5 are flowcharts showing operation procedures and contents of the temperature information management unit 55 and the timing error adjustment unit 54, respectively.
[0045]
First, the temperature information management unit 55 waits for reception start timing information RS in step ST401. In this state, when the reception start timing information RS is notified, the temperature detection data TM output from the temperature detector 63 is fetched in step ST402, and this temperature detection data TM and the temperature detection data fetched in the previous cycle are taken. From TM, the temperature difference generated around the low-speed clock oscillator 62 from the reception start timing of the previous cycle to the reception start timing of the current cycle is calculated (step ST403). When the temperature difference calculation is completed, the temperature information management unit 55 returns to step ST401 and waits for a new reception start timing notification. In this standby period, the temperature information management unit 55 always outputs temperature change information TC indicating the temperature difference calculated in step ST403 to the timing error adjustment unit 54.
[0046]
On the other hand, as shown in FIG. 5, the timing error adjustment unit 54 waits for the arrival of the synchronization timing information ST from the radio unit 1 in step ST501. In this state, when the synchronization timing information ST arrives, the temperature change information TC output from the temperature information management unit 55 is captured in step ST502. Then, in step ST503, based on the captured temperature change information TC and the temperature characteristics of the low-speed clock oscillator 62 stored in advance, the reception timing generation unit 21 reflects them in the determination of the reception target timing of the next period. The upper and lower limits of the timing error are calculated.
[0047]
Next, the timing error adjustment unit 54 takes in the synchronization timing information ST from the radio unit 1 in step ST504, and receives the reception target timing information RT from the reception timing generation unit 21 in step ST505. Based on these timing information ST and RT, in step ST506, the reception target timing calculated by the reception timing generation unit 21 and the reception timing at which the radio unit 1 actually received the synchronization establishment data SD are obtained. Calculate timing error.
[0048]
Subsequently, in step ST507, the timing error adjustment unit 112 compares the calculated timing error with the upper limit value and the lower limit value calculated in step ST503, respectively. If the timing error is larger than the upper limit value, the upper limit value is selected as timing error information in step ST508. If the timing error is smaller than the lower limit value, the lower limit value is selected as timing error information in step ST509. On the other hand, if the timing error is not more than the upper limit value and not less than the lower limit value, the timing error is directly selected as timing error information in step ST510. The timing error information TG thus selected is output to the reception timing generation unit 21.
[0049]
When the calculation of the timing error information TG ends, the timing error adjustment unit 54 returns to step ST501 and waits for new synchronization timing information ST to arrive.
[0050]
The reception timing generation unit 21 normally waits for the synchronization timing information ST from the wireless unit 1 to arrive at step ST601 as shown in FIG. When the synchronization timing information ST arrives from the radio unit 1, the synchronization timing information ST that has arrived is captured in step ST602.
[0051]
Subsequently, the reception timing generation unit 21 takes in the timing error information TG output from the timing error adjustment unit 54 in step ST603, and receives the timing error information TG and the reception cycle indicated by the reception cycle information specified by the control unit 5. Based on the synchronization timing indicated by the synchronization timing information ST fetched in step ST602, the reception target timing used for receiving the synchronization establishment data SD in the next cycle is calculated (step ST604). The reception timing generation unit 21 sets a reception period by adding a predetermined margin to the data length of the synchronization establishment data SD in step ST605, and based on the reception period and the reception target timing calculated in step ST604. Then, the timing (reception start timing) for starting the reception operation of the synchronization establishment data SD in the next cycle is calculated (step ST606).
[0052]
When the reception start timing is calculated in this way, the reception timing generation unit 113 monitors the arrival of the calculated reception start timing thereafter in step ST607. The arrival monitoring of the reception start timing is mainly performed by counting the low-speed clock CLK2 generated from the low-speed clock oscillator 62, and based on the high-speed clock CLK1 generated from the high-speed clock oscillator 61 immediately before the reception start timing arrives. Is performed with high accuracy. Note that the oscillation operation of the high-speed clock oscillator 61 is stopped while the reception timing generation unit 21 does not use the high-speed clock CLK1.
[0053]
Now, at the reception start timing, the reception timing generation unit 21 outputs the reception start timing information RS to the radio unit 1 in step ST608. At the same time, the wireless unit 1 is notified of information RW indicating the reception period previously set in step ST605. As a result, the radio unit 1 starts receiving the synchronization establishment data SD as described above. Reception timing generation section 21, after outputting reception start timing information RS in step ST608, returns to step ST601. Then, it waits for the arrival of the synchronization timing information ST output from the radio unit 1 as the reception operation result started as described above.
[0054]
As described above, in the first embodiment, the ambient temperature of the low-speed clock oscillator 62 is detected by the temperature detector 63 in synchronization with the reception start timing of each cycle, and the temperature detection data TM of the temperature detector 63 is used as the basis. Further, the temperature information management unit 55 calculates the temperature difference between the reception start timings of the respective periods. The timing error adjustment unit 54 calculates timing error information TG adjusted by reflecting the error component due to the calculated temperature difference, and the reception timing generation unit 21 calculates the next cycle based on the timing error information TG. The reception start timing and the reception period are determined, and the wireless unit 1 is caused to perform an intermittent reception operation according to these timing information.
[0055]
Therefore, according to the first embodiment, when the reception target timing in the next cycle is determined by reflecting the timing error between the reception target timing set in the cycle and the timing at which the synchronization establishment data can actually be received. In addition, the timing error is adjusted in consideration of the temperature change generated around the low-speed clock oscillator 62 from the previous cycle to the current cycle. For this reason, the temperature fluctuation of the low-speed clock CLK2 is compensated, and the accuracy of the reception target timing is increased. By reducing the error in the reception target timing in this way, it is possible to minimize the margin included in the reception period, thereby shortening the reception operation period in intermittent reception and further reducing power consumption during standby. It becomes possible.
[0056]
In the first embodiment, the timing error adjustment unit 54 determines the timing error based on the temperature change information TC fetched from the temperature information management unit 55 and the temperature characteristics of the temperature detector 63 stored in advance. An upper limit value and a lower limit value are calculated. Then, the calculated timing error is compared with the upper limit value and the lower limit value, and when the timing error exceeds the upper limit value and lower than the lower limit value, the timing error is set to the upper limit value or the lower limit value. The reception target timing is determined based on the value or the lower limit value.
[0057]
Therefore, when the timing error exceeds the upper limit value or falls below the lower limit value, it is determined that the cause is due to, for example, multipath fading other than the accuracy and temperature characteristics of the low-speed clock oscillator 62 itself, and the timing error is Set to the lower limit. For this reason, a problem that a temporary error component due to multipath fading or the like is corrected as a steady error component is prevented, and thus it is possible to always set the reception target timing and the reception period in the next cycle correctly.
[0058]
(Second Embodiment)
In the second embodiment of the present invention, when managing the change in the ambient temperature of the low-speed clock oscillator 62, the temperature transition from the time before one cycle to the current cycle is detected, and this temperature transition is adjusted for the timing error. It is made to reflect in.
[0059]
FIG. 7 is a flowchart showing the operation procedure and operation contents of the temperature information management unit in the second embodiment. In addition, since the circuit configuration of the mobile communication terminal in this embodiment is the same as that in FIG. 1 and FIG. 2 described in the first embodiment, description thereof is omitted here.
[0060]
As shown in FIG. 7, first, in step ST701, the temperature information management unit 55 takes in the temperature detection data TM output from the temperature detector 63 at a predetermined sampling interval set shorter than the intermittent reception cycle, and this temperature detection data TM. Each time the data is taken in, the statistical information of the temperature held by itself is updated based on the data in step ST702. Here, the statistical information is information that records, for example, the state of temperature change in the period of the past one cycle of the intermittent reception operation.
[0061]
The temperature information management unit 55 repeatedly executes the operations of step ST701 and step ST702 while monitoring the notification of the reception start timing information RS from the reception timing generation unit 21 in step ST703. Then, when reception start timing information RS is notified in this state, in step ST705, based on the temperature statistical information, the temperature between the reception start timing notification point one cycle before and the reception start timing notification point of the current cycle. Predict the transition.
[0062]
When the temperature transition prediction process ends, the temperature information management unit 55 returns to step ST701 and repeats the temperature monitoring operation in steps ST701 and ST702, and a new reception start timing notification is issued in step S703. Wait for the arrival. Note that the temperature information management unit 55 constantly outputs the temperature change information TC indicating the temperature transition calculated in step ST705 to the timing error adjustment unit 54 during the reception monitoring timing notification.
[0063]
As described above, in the second embodiment, with respect to the timing error between the calculated reception target timing and the timing at which the synchronization establishment data SD was actually received, the temperature transition predicted based on the temperature change statistics is calculated. After making adjustments in consideration, it is reflected in the determination of the reception target timing. Therefore, it becomes possible to determine the reception target timing more appropriately, thereby further reducing the margin of the reception period and further reducing the power consumption in the intermittent reception operation.
[0064]
(Other embodiments)
In the first embodiment, the temperature detection characteristic of the temperature detector 63 itself may be taken into account when calculating the difference between the temperature detected in the current period and the temperature detected one period before. In this way, it is possible to obtain a more accurate temperature difference by correcting the nonlinearity of the temperature detection characteristic of the temperature detector 63.
[0065]
In the second embodiment, the statistical information is updated by periodically acquiring the temperature information during the monitoring period of the reception start timing. However, if this is done, power is frequently supplied to sections that require temperature detection, such as analog-to-digital converters that convert detected temperature values into digital values, which is undesirable from the viewpoint of power consumption. .
[0066]
Therefore, the temperature detection period is made to coincide with the arrival period of the reception start timing notification, and the temperature is detected every time reception is started. The temperature change during the monitoring period of the reception start timing is supplemented based on the temperature information detected at a plurality of reception start timings, and the reception target timing is determined based on the complemented temperature information. Good. In this way, it is possible to reduce the power consumption required for temperature detection and further extend the standby time of the terminal.
[0067]
In each of the above embodiments, the case where the control of the reception timing is realized by using hardware such as the temperature information management unit 55, the timing error adjustment unit 54, the reception timing generation unit 21, and the like has been described as an example. However, the present invention is not limited to this, and all operations can be executed by software. This can be realized, for example, by causing the microprocessor of the control unit 5 to be executed by a reception control program.
[0068]
In each of the above embodiments, a mobile phone terminal used in a CDMA mobile communication system has been described as an example. However, a personal digital assistant (PDA) used in a similar mobile communication system or a CDMA system is adopted. It can also be applied to an in-vehicle receiving terminal used in the broadcasting system.
[0069]
【The invention's effect】
As described above in detail, the present invention further includes a temperature detection means for detecting the ambient temperature of the clock oscillator and a timing correction means. In this timing correction means, the reception generated by the reception target timing generation means. An error between the target timing and the actual reception timing of the synchronization establishment data received by the receiving means is obtained. The reception target timing generated by the reception target timing generation means is corrected based on the timing error and the temporal change in the ambient temperature of the clock oscillator detected by the temperature detection means.
[0070]
Therefore, according to the present invention, even when a low-accuracy clock oscillator is used, it is possible to accurately receive data for establishing synchronization without increasing power consumption during standby, thereby achieving high and low synchronization holding performance. An inexpensive wireless communication terminal with low power consumption can be provided.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram showing a configuration of a mobile communication terminal which is a first embodiment of a wireless communication terminal according to the present invention.
2 is a circuit block diagram showing a configuration for realizing a synchronization establishment maintaining function of the mobile communication terminal shown in FIG. 1;
FIG. 3 is a flowchart for explaining an intermittent reception operation of a radio unit shown in FIG. 1;
4 is a flowchart for explaining a processing operation of a temperature information management unit shown in FIG. 2;
FIG. 5 is a flowchart for explaining a processing operation of a timing error adjustment unit shown in FIG. 2;
6 is a flowchart for explaining a processing operation of a reception timing generation unit shown in FIG.
FIG. 7 is a flowchart for explaining the processing operation of the temperature information management unit in the mobile communication terminal according to the second embodiment of the present invention.
FIG. 8 is a timing chart for explaining an example of a synchronization maintaining operation with intermittent reception.
[Explanation of symbols]
1 ... Radio section
2 ... CDMA signal processor
3. Compression / decompression processor
4 ... PCM code processing section
5. Control unit
6 ... Timing circuit
7 ... Power supply
11 ... Antenna
12 ... Antenna duplexer (DUP)
13 ... Receiving circuit (RX)
14 ... Frequency synthesizer (SYN)
15 ... Transmission circuit (TX)
21 ... Reception timing generation unit
41 ... receiver amplifier
42 ... Speaker
43 ... Microphone
44 ... Transmission amplifier
51. Input unit
52 ... Display section
53. Storage unit
54 ... Timing error adjustment section
55. Temperature information management unit
61 ... Low-speed clock oscillator
62 ... Low-speed clock oscillator
63 ... Temperature detector
71 ... Battery
72. Power supply circuit
RT: Reception cycle information
ST: Synchronization timing information
RW ... Reception period designation information
RS: Reception start timing information
TG ... Timing error information
TM ... Temperature detection data
TC ... Temperature change information
CLK1 ... High speed clock
CLK2 ... Low speed clock

Claims (5)

In a wireless communication terminal that receives synchronization establishment data that is intermittently wirelessly transmitted at a predetermined cycle from a transmission device, and establishes synchronization with the transmission device based on the reception timing,
Based on a reference clock generated by a clock oscillator, reception target timing generating means for generating a reception target timing at a period corresponding to the transmission period of the synchronization establishment data
Receiving means for setting a receiving period of a predetermined width on the basis of the receiving target timing generated by the receiving target timing generating means, and performing the operation of receiving the data for establishing synchronization during the receiving period;
Temperature detecting means for detecting the ambient temperature of the clock oscillator;
An error between the reception target timing generated by the reception target timing generation means and the actual reception timing of the synchronization establishment data received by the reception means is obtained, and this error and the ambient temperature detected by the temperature detection means A wireless communication terminal, comprising: a timing correction unit that corrects a reception target timing generated by the reception target timing generation unit based on a time change of the reception target timing. The timing correction means includes
The reception target timing in the current cycle generated by the reception target timing generation means, and the actual reception timing of the synchronization establishment data received by the reception means during the reception period set based on the reception target timing An error calculating means for calculating an error;
A temperature difference calculating means for calculating a temperature difference between the ambient temperature in the current cycle detected by the temperature detecting means and the ambient temperature of the previous cycle;
Means for correcting the reception target timing generated in the next cycle by the reception target timing generation means based on the error calculated by the error calculation means and the temperature difference calculated by the temperature difference calculation means; The wireless communication terminal according to claim 1. The timing correction means includes
The reception target timing in the current cycle generated by the reception target timing generation means, and the actual reception timing of the synchronization establishment data received by the reception means during the reception period set based on the reception target timing An error calculating means for calculating an error;
Based on the detection output of the temperature detection means, temperature transition calculation means for obtaining a transition of the ambient temperature in a period from the reception target timing one cycle before to the reception target timing in the current period;
Means for correcting the reception target timing generated by the reception target timing generation means in the next cycle based on the error calculated by the error calculation means and the transition of the ambient temperature calculated by the temperature transition calculation means; The wireless communication terminal according to claim 1, further comprising: The timing correction means includes
Upper limit setting means for setting an upper limit value of the correction amount of the reception target timing;
Based on the error between the reception target timing and the actual reception timing of the data for establishing synchronization, and the time change of the ambient temperature detected by the temperature detection means, the reception target timing generated by the reception target timing generation means Correction amount calculating means for calculating a correction amount;
The correction amount calculated by the correction amount calculation means is compared with the upper limit value set by the upper limit value setting means, and when the calculated correction amount exceeds the upper limit value, based on the upper limit value, 2. The wireless communication terminal according to claim 1, further comprising means for correcting the reception target timing generated by the reception target timing generation means. The timing correction means includes
Lower limit value setting means for setting a lower limit value of the correction amount of the reception target timing;
Based on the error between the reception target timing and the actual reception timing of the data for establishing synchronization, and the time change of the ambient temperature detected by the temperature detection means, the reception target timing generated by the reception target timing generation means Correction amount calculating means for calculating a correction amount;
Comparing the correction amount calculated by the correction amount calculation means with the lower limit value set by the lower limit value setting means, and when the calculated correction amount falls below the lower limit value, based on the lower limit value, 2. The wireless communication terminal according to claim 1, further comprising means for correcting the reception target timing generated by the reception target timing generation means.

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