JP2002368673A - Portable terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable terminal, in which power consumption of a reception section of the portable terminal is reduced while maintaining an intermittent reception operation. SOLUTION: The portable terminal can reduce the power consumption for an intermittent reception operation at a standby state and is provided with an analog/digital converter section 106, provided with a high resolution analog/ digital converter 106a and a low-resolution analog/digital converter 106b, a reception level measurement section 112 that measures the reception level with the timing of the intermittent reception operation, and a control section 111 that switches high-resolution analog/digital converter 106a or the low-resolution analog/digital converter 106b of the analog/digital converter section 106, on the basis of the reception level and fluctuations in the reception level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable terminal that performs an intermittent reception operation in a standby state, and more particularly, to a CDM.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile terminal that reduces power consumption of an intermittent reception operation in a standby state in a wireless communication system of an A (Code Division Multiple Access) system.

[0002]

2. Description of the Related Art As is well known, in a mobile terminal of a digital mobile radio communication system such as a mobile phone, it is important to reduce the power consumption of a transmission / reception section for extending continuous talk time and standby time. Has become one. In order to solve this problem, a mobile terminal using an intermittent reception method for intermittently receiving a paging signal from a base station in a standby state has been proposed. A mobile terminal using the intermittent reception method determines whether there is an incoming call in a paging signal reception state. On the other hand, in an idle state other than the paging signal reception state, power consumption can be reduced by stopping the transmission / reception unit.

[0003] Next, as a concrete measure for putting the transmission / reception section in a stopped state, TCXO (Temperature Compensated X ') has been proposed.
(tal Oscillators) and a method of selectively using a low-speed clock will be described as an example. The TCXO is a clock reference frequency oscillator that is used for a radio unit and a baseband unit that perform transmission / reception operations of a portable terminal and requires high accuracy. The low-speed clock is usually used for a real-time clock (RTC) for time management and a clock function of the mobile terminal.

The paging signal reception state in the intermittent reception operation uses a TCXO used for transmission / reception operation and a low-speed clock used for RTC. On the other hand, in the idle state, the TCXO used for the transmission / reception operation is stopped, and the low-speed clock used for the RTC is used. That is, this portable terminal measures the interval until the next paging signal reception timing using the low-speed clock, restarts the TCXO when the measurement time reaches the paging signal reception timing, and shifts to the reception operation. The power consumption is reduced by finely controlling the clock and power supply of each component.

Here, the CDMA system will be described.
In the CDMA system, a specific spreading code assigned to each channel on the transmitting side is used to spread the signal over a frequency band wider than the frequency band of the original signal, and multiplex and transmit the signal. Therefore, the receiving side needs to identify the channel to be received by synchronizing with the same spreading code as the transmitting side. Here, a pilot signal serving as a reference for synchronization and phase of the despreading code is used as a transmission signal from the base station. Prior to receiving control information and user data, synchronization using a pilot signal is indispensable.

[0006] Also in a CDMA wireless communication system, an intermittent reception system is applied. In the CDMA system, synchronization with the transmitting side is lost at the time of transition to an idle state using a low-speed clock. In order to receive the paging signal again, resynchronization is necessary prior to the reception of the paging signal, and a high-accuracy clock is required in the reception of the radio unit and the baseband unit.

In the CDMA system, fine power control of transmission power is performed. For example, a closed loop in which the level of a received signal is measured in a dedicated channel applied to communication of control information and user data between a base station and a mobile terminal, and dynamic control is performed so that transmission power becomes an optimum value based on the measurement result. A power control method or the like is used. However, since power control such as closed loop is not performed on a common control channel transmitted from the base station including the broadcast information to all terminals belonging to the area, the reception quality is portable. It greatly depends on the environment where the terminal is located.

As described above, in the CDMA system, high reception performance is required for the reception unit even in the intermittent reception operation.

[0009]

In the case of the intermittent reception operation as in the above-mentioned prior art, a configuration assuming the worst environment in both the synchronization characteristics and the reception characteristics of the common control channel including the paging channel is used. Necessary for mobile terminals. However, if a high bit resolution is required for an AD converter that performs AD conversion of a reception signal from a radio unit, a despreading unit including a plurality of fingers, and the like, a problem arises in that it is difficult to reduce power consumption.

[0010] The present invention has been made in view of the above-described problems, and has as its object to provide a portable terminal that reduces power consumption of a receiving unit of the portable terminal while maintaining intermittent reception operation.

[0011]

In order to achieve the above object, a portable terminal according to the present invention is a portable terminal that performs an intermittent receiving operation in a standby state, and performs A / D conversion at a plurality of different resolutions. AD conversion means that can be performed, a reception level measurement unit that measures a reception level at the timing of the intermittent reception operation, and a control unit that switches the resolution of the A / D conversion means based on the measurement result. It is characterized by the following. Here, the A / D converter may be configured by a plurality of A / D converters having different resolutions,
Alternatively, a single A / D converter having a plurality of resolutions may be used. Then, the control unit may switch the plurality of A / D converters according to their resolutions, or may switch the plurality of resolutions in one A / D converter.

According to such a configuration, by switching the resolution of the AD converter according to the reception level,
The battery consumption of the portable terminal during standby can be reduced while maintaining the intermittent reception operation, and the standby time can be extended.

Further, in the portable terminal according to the present invention, the control unit calculates a variation of the reception level based on a current result and a past result of the measurement, and calculates the current result and the variation. The resolution is switched based on the following.

According to such a configuration, by switching the resolution of the AD converter based on the variation of the reception level, an appropriate resolution can be used even when the variation of the reception level is large.

In the embodiment of the present invention, an antenna unit for receiving a radio signal, a radio unit for converting the output of the antenna unit from a high frequency to a baseband, and an output of the radio unit from an analog signal An AD converter unit for converting to digital; a synchronizing unit for detecting a peak timing of each path using an output of the AD converter unit; Means, a channel decoder unit for performing error correction and decoding on the output of the demodulation unit, a reception level measurement unit for measuring the reception level of the output of the demodulation unit, and based on the output of the reception level measurement unit. A portable terminal comprising a control unit for switching the resolution of the AD converter unit, wherein the AD converter unit is a high-resolution AD converter. Comprising a motor and a low-resolution AD converter performs measurement of reception level at the timing of the intermittent reception operation in the standby state is the reception level measuring unit,
The control unit may be, for example, a mobile phone that switches between the high-resolution AD converter and the low-resolution AD converter based on a current reception level and a reception level fluctuation amount calculated by comparing the reception level and a past reception level. Is explained.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the outline of the receiving operation in the mobile terminal of the present invention will be described.

In the CDMA system, a base station constantly transmits a common control channel, a pilot channel, a timing detection channel, etc., which are control information unique to each system or base station and common to each terminal. After the power is turned on, the mobile terminal detects the radio frame timing of the reference base station using the timing detection channel. At the same time, the mobile terminal detects the spreading code transmitted from the base station, measures the reception level of each base station, and selects an optimal base station.

After performing the cell selection processing, the portable terminal performs the location registration processing. The location registration process is a process for causing the system to recognize that the mobile terminal is located in the service area of the base station selected by the cell selection process. After performing the location registration processing, the mobile terminal shifts to a standby state, that is, an intermittent reception operation of a paging signal from the base station, and continuously detects whether there is an incoming call.

Here, a paging method in the standby state will be described. In the standby state, the mobile terminal first determines whether or not there is a paging signal by using a PIC.
H (Paging Indicator Channel) intermittent reception operation is performed. When the mobile terminal determines that there is a paging signal from the information included in the PICH, the mobile terminal receives the paging channel transmitted along with the PICH. With the individual information elements included in this paging channel, the mobile terminal shifts to the incoming call operation. The above is the outline of the receiving operation in the portable terminal of the present invention.

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating an example of a configuration of a mobile terminal according to the present embodiment. As shown in FIG. 1, the mobile terminal includes an antenna unit 101, a wireless unit 1
02, a DA converter 103, a modulator 104, a channel encoder 105, and an AD converter 106
, Demodulation section 108, synchronization section 109, channel decoder 110, control section 111, reception level measurement section 112
, A display unit 113, and an operation unit 114.

Here, the AD converter unit 106 will be described. The AD converter unit 106 can change the resolution by inputting a resolution control signal from the outside. As an example, the AD converter unit 106 in FIG. 1 is realized by including a high-resolution AD converter 106a, a low-resolution AD converter 106b, and a resolution switching terminal, and has a high resolution according to a resolution control signal from the control unit 111. AD converter 106
a and the low-resolution AD converter 106b.

Next, the transmission operation in the portable terminal of the present invention will be described in detail. The operation unit 114 outputs control data, character data, voice data, and the like input by the user to the control unit 111. The control unit 111 outputs character data, audio data, and the like as transmission data to the channel encoder 105 according to the control data, and controls the display unit 113 and the operation unit 114 for a user interface. The display unit 113 displays control data, character data, voice data, guidance regarding input, and the like, according to the control of the user interface.

The channel encoder 105 performs coding such as error correction on the transmission data and framing processing for generating a radio frame, and outputs the result to the modulation section 104 as a coded signal.

The modulation section 104 performs spreading processing and modulation processing of the coded signal using a specific spreading code specified for each communication channel and each terminal, and outputs the result to the DA converter 103 as a modulation signal. .

The DA converter 103 converts the digital of the modulated signal into an analog signal, and outputs it to the radio section 102 as a transmission baseband signal. Radio section 102 frequency-converts the transmission baseband signal from baseband to high frequency, and outputs the signal to antenna section 101 as a transmission signal. Antenna section 101 outputs a transmission signal to the outside.

Next, the receiving operation in the portable terminal of the present invention will be described in detail. First, the base station spreads and modulates a transmission signal using a spreading code, and transmits the signal. The spreading code used here is assigned to each transmission channel and each base station.

The antenna unit 101 includes at least one antenna, receives a radio signal from the outside, and outputs the result to the radio unit 102 as a reception signal. Radio section 102 converts the frequency of the received signal from high frequency to baseband using a local oscillator,
A component, that is, a quadrature component and an in-phase component, is separated by a filter, and unnecessary band components other than the desired wave are removed.
Output to 6.

The AD converter unit 106 includes a control unit 111
Converts the received baseband signal from analog to digital by using an AD converter having the resolution specified by, and converts the result to a demodulation unit 108 as a received digital signal.
And output to the synchronization unit 109.

Here, the received baseband signal input to the AD converter unit 106 is a signal having a chip rate in the spreading process, and the sampling rate in the AD converter unit 106 is usually four times the chip rate.
About twice the frequency is required. For example, if the chip rate is 3.84 MHz, the sampling rate is 15.3 MHz.
A high frequency of 6 MHz is required. Further, the word tone of the received digital signal after AD conversion, that is, the resolution of the AD converter is, for example, a high-resolution AD converter 106.
a is about 8 bits.

The synchronizing unit 109 performs a despreading process and a demodulation process on the received digital signal by the demodulation unit 108,
A correlation operation with the spread reception digital signal is performed, multipath is detected by multipath fading of the propagation path, and the peak timing of each path is output to the demodulation unit 108.

The demodulation section 108 performs a despreading process on each path of the received digital signal, detects a despread signal of each path obtained as a result, and detects a detected signal of each path obtained as a result. The combining processing is performed in accordance with the peak timing, and the resulting demodulated signal is output to channel decoder 110 and reception level measuring section 112. Here, the synthesis processing for the detection result of each path is represented by R
It is called AKE synthesis.

Here, the demodulation unit 108 will be described in detail. The demodulation unit 108 in the spread spectrum such as the CDMA system includes a plurality of fingers. The finger is a circuit that performs despreading for each path of the received digital signal.

The number of propagation paths between the transmitter and the receiver in wireless communication is not limited to one. That is, the transmission signal is received through different propagation paths due to reflection and refraction. Signals that have passed through different propagation paths are all copies of the transmission signal, but are received as multipaths having different amplitudes, phases, and arrival times. In order for the receiving side to receive a transmission signal without deterioration, it is necessary to independently receive and combine multipaths. The despreading corresponding to each path of the multipath is a finger, and the number of paths required for reception differs depending on the spreading band. In the CDMA system, a receiver uses a spreading code used on the transmission side as a despreading code. The finger corresponding to each path performs despreading using a despreading code, and outputs the result as a despread signal of each path.

When the demodulated signal is a multiplexed signal of a plurality of channels, the channel decoder 110 separates the channels, and decodes the resulting demodulated signals of the respective channels in units of frames. The result is output to control section 111 as a decoded signal. Here, decoding refers to an interleaving process on a data sequence divided in frame units and an error correction process such as Viterbi decoding or turbo decoding on convolutionally coded or turbo coded data.

The reception level measuring section 112 measures the reception level of the common control channel using the demodulated signal of the common control channel for selecting a base station and monitoring the radio condition. In addition, the reception level measurement unit 112 measures the reception level of the individual channel using the demodulated signal of the individual channel for closed-loop transmission power control using the individual channel. The obtained reception level measurement results of the common control channel and the individual channels are output to the control unit 111.

Normally, for the reception level measurement, CPICH (Common Pilot Channel) transmitted in common in the area is used.
l) RSCP (Received Signal Code Power) and E _c /
I ₀ (CP for total transmission power including interference components)
The measurement result of the received power ratio per chip of the ICH) is used. Based on the measurement result, selection of a cell to be captured first, evaluation of handover, propagation loss, and determination of an initial transmission power value when a dedicated channel is connected are performed. In the CDMA method, high precision is required for measuring the reception level in order to reduce interference and increase the capacity of the channel by finely controlling the transmission power.

The control unit 111 is constituted by a CPU, controls the resolution of the AD converter unit 106 using each reception level measurement result, and outputs a resolution control signal to the AD converter unit 10.
Output to 6. Further, the control unit 111 performs timing management based on a wireless frame, wireless protocol processing such as connection and disconnection of a line with a base station, multiplexing of data in a transmission operation, and separation of data in a reception operation. Further, the control unit 111 manages radio resources based on information on the system side, such as control information of a common control channel from a base station, for controlling the components related to the modulation and demodulation described above.

Next, a method for reducing power consumption in the standby state will be described. As described above, the portable terminal performs the intermittent reception operation of the PICH in the standby state.
Here, the PICH is a signal transmitted in common within the service area of the base station, and does not perform fine transmission power control such as an individual channel. Also, a DRX cycle (Discontinuous Reception cycling) which is a cycle of the intermittent reception operation is performed.
e) Since the length differs depending on the system, the DRX cycle length is obtained from the broadcast information transmitted from the base station, and the discontinuous reception operation is performed according to the DRX cycle length.

In this embodiment, unnecessary power consumption is reduced by switching between the high-resolution AD converter and the low-resolution AD converter of the AD converter unit 106 at the timing of intermittent reception. Specifically, the reception level measured by the reception level measurement unit 112 is used as a reference for switching.

The reception characteristics of the PICH vary depending on the propagation environment around the portable terminal. For example, in a city area or the like, reflection and interference are large, and it is expected that the reception level dynamically changes even when the portable terminal is stopped. In such an environment, in the intermittent reception operation, even if the reception level received last time is sufficient, the reception level received again after the DRX cycle is not necessarily the same as the previous time.

In order to cope with the fluctuation of the reception level due to the change of the propagation environment, the reception level measuring section 112 compares the reception level measured in the current discontinuous reception operation with the reception level measured in the previous discontinuous reception operation. By calculating the received level fluctuation amount for each DRX cycle length,
The amount of change in the reception level is also used as a reference for switching the AD converter unit 106. Here, the reception level variation indicates the magnitude of the variation of the reception level in the current propagation environment.

FIG. 2 is a flowchart showing an example of the intermittent reception operation in the standby state. The flow starts when the power of the mobile terminal is turned on. First, the control unit 111
A DRX cycle and the like are acquired from the broadcast information transmitted from the base station (S201).

Next, the control unit 111 executes a location registration process (S
202), PICH reception (S203), and reception level measurement (S204) are sequentially performed, and the process proceeds to step S205.

Next, the control section 111 determines whether or not the measured reception level has exceeded a preset reception level threshold (S205). Here, the reception level threshold is determined by the reception characteristics of the receiver and the PIC transmitted from the base station.
H is determined by the transmission power ratio.

When the reception level does not exceed the reception level threshold value (S205, Y), the control unit 111
A resolution control signal for instructing to use the D converter 106a is output to the AD converter unit 106 (S20).
6), the process proceeds to S207. At this time, the unused low-resolution AD converter 106b is powered down.

When the reception level exceeds the reception level threshold value (S205, N), the control unit 111 calculates the reception level fluctuation amount (S211), and sets the reception level fluctuation amount to a preset reception level fluctuation amount. It is determined whether or not the amount exceeds the threshold (S212). Further, if the DRX cycle length is lengthened to reduce power consumption, the reliability of the reception level fluctuation amount decreases. Therefore, the reception level fluctuation amount threshold value is determined using a linear expression relating to the DRX cycle length.

If the received level variation does not exceed the received level variation threshold (S212, Y), the control unit 111
Determines that the signal can be stably received, and outputs a resolution control signal for instructing to use the low-resolution AD converter 106b at the time of receiving PICH after the next DRX cycle.
Output to converter section 106 (S213), and processing S20
Move to 7. At this time, the unused high-resolution AD converter 106a is powered down. On the other hand, when the reception level variation exceeds the reception level variation threshold (S2
12, N), the control unit 111 proceeds to step S206.

After the switching operation for the AD converter unit 106, the control unit 111 performs a sleep state, that is, performs a low-speed clock operation (S207), and determines whether there is an incoming call (S208). When there is no incoming call (S208,
N), the process returns to step S203, and if there is an incoming call (S20)
8, Y) ends this flow.

[0049]

As described in detail above, according to the present invention,
By switching the resolution of the AD converter to high or low according to the reception level and the amount of fluctuation of the reception level, the battery consumption of the portable terminal during standby can be reduced while maintaining the intermittent reception operation, and the standby time can be extended. It becomes possible. For example, the resolution of the high-resolution AD converter is 8 bits, and the resolution of the low-resolution AD converter is 4 bits.
In the case of it, the power consumption of this AD converter can be reduced by about 25%. Further, by switching the resolution of the AD converter based on the amount of change in the reception level, an appropriate resolution can be used even when the amount of change in the reception level is large. Further, it is possible to easily reduce the bit width in the processing of the demodulation unit and the like, and it is possible to apply the optimization of the bit width of data accompanying the output of the AD converter.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a configuration of a mobile terminal according to the present embodiment.

FIG. 2 is a flowchart illustrating an example of an intermittent reception operation.

[Explanation of symbols]

101 antenna unit, 102 radio unit, 103 DA converter, 104 modulation unit, 105 channel encoder, 106 AD converter, 108 demodulation unit, 109
Synchronization unit, 110 channel decoder, 111 control unit, 112 reception level measurement unit, 113 display unit, 11
4 Operation unit.

Claims (2)

[Claims] 1. A portable terminal that performs an intermittent reception operation in a standby state, and is capable of performing A / D conversion with a plurality of different resolutions.
/ D conversion means, a reception level measurement unit for measuring a reception level at the timing of the intermittent reception operation, and a control unit for switching the resolution in the A / D conversion means based on the result of the measurement. A mobile terminal characterized by the following. 2. The mobile terminal according to claim 1, wherein the control unit calculates a fluctuation amount of the reception level based on a current result and a past result of the measurement, and calculates the current result and the current result. A portable terminal, wherein the resolution is switched based on a variation amount.