KR19980064194A - Terminal equipment and receiving method of portable telephone system - Google Patents

Abstract

The external power supply detection circuit of the terminal apparatus according to the present invention detects whether external power is supplied from the external power supply terminal. In the standby state, signals are received intermittently from the base station. When the internal battery is used, the timing at which the terminal device enters the reception mode becomes longer. When the external power supplied from the external power terminal is used, the timing at which the terminal apparatus enters the reception mode becomes shorter.

Description

Terminal equipment and receiving method of portable telephone system

The present invention relates to a terminal apparatus of a mobile telephone system suitable for a CDMA (code division multiple access) type portable telephone system.

In recent years, the CDMA type mobile telephone system has attracted interest. In the CDMA-type mobile telephone system, pseudorandom codes are used as spread codes. The carrier wave of the transmission signal is spread spectrum. In the code sequence, the pattern and phase of each spreading code are changed to perform multiple access.

In the CDMA scheme, a spread spectrum method is used. In the spread spectrum scheme, when data is transmitted, the carrier is first modulated with the transmitted data. The primary modulated carrier is also multiplied by PN (Pseudorandom Noise) code. Thus, the carrier is modulated with a PN code. As an example of the primary modulation method, a balanced QPSK modulation method is used. Since the PN code is a random code, the frequency spectrum is extended when the carrier is modulated by the PN code.

When data is received, the received data is multiplied by the same PN code as modulated at the transmitting side. When this same PN code is multiplied and the phases match, the received data is despread and thereby primary modulation data is obtained. When the primary modulated data is demodulated, the original data is obtained.

In the spread spectrum method, in order to despread the received signal, the same PN code as the pattern and phase modulated on the transmitting side is required. Therefore, when the pattern and phase of the PN code are changed, multiple connections can be made. The CDMA method relates to a method of changing the pattern and phase of each spreading code in a code sequence and thereby performing multiple accesses.

As the mobile telephone system, FDMA (frequency division multiple access) and TDMA (time division multiple access) have been used. However, the FDMA method and the TDMA method cannot handle a significant increase in the number of users.

In other words, in the FDMA scheme, multiple accesses are made to different frequency channels. In analog cell phone systems, the FDMA scheme is commonly used.

However, in the FDMA scheme, since the frequency utilization efficiency is poor, a significant increase in the number of users can cause a shortage of channels. When the channel spacing narrows due to an increase in the number of channels, adjacent channels conversely interfere with each other, thereby degrading sound quality.

In the TDMA scheme, the transmission data is compressed on a time base, so that the usage time is divided and thereby the same frequency is distributed. The TDMA method has been widely used as a digital cellular phone method. In the TDMA scheme, the frequency utilization efficiency is improved compared to the simple FDMA scheme. By the way, in the TDMA scheme, the number of channels is limited. Thus, when the number of users is greatly increased, the number of channels is insufficient.

On the other hand, the CDMA method has excellent interference resistance. Thus, in the CDMA scheme, adjacent channels do not interfere with each other. As a result, the frequency utilization efficiency is improved and more channels can be obtained.

In the FDMA and TDMA schemes, signals tend to be affected by fading due to multipath.

In other words, as shown in FIG. 4, a signal is sent from the base station 201 to the portable terminal 202 through a number of paths. In addition to the path P1 through which the radio wave of the base station 201 is directly transmitted to the portable terminal device 202, there are a path P2, a path P3, and the like. In path P2, radio waves of base station 201 are reflected by building 203A and sent to portable terminal 202. In path P3, radio waves of base station 201 are reflected by building 203B and sent to portable terminal 202.

The radio waves reflected by the buildings 202A and 203B and sent to the portable terminal 202 via the paths P2 and P3 are transmitted to the radio waves sent directly from the base station 201 to the portable terminal 202 via the path P1. Is delayed. Thus, as shown in FIG. The signals S1, S2, S3 arrive at the portable terminal 202 via paths P1, P2, P3 at different times, respectively. Fading occurs when signals S1, S2, S3 through paths P1, P2, P3 interfere with each other. In the FDMA and TDMA schemes, multipath allows the signal to be affected by fading.

On the other hand, in the CDMA scheme, with the diversity RAKE scheme, fading due to multipath can be relaxed and the S / N ratio can be improved.

In the diversity RAKE scheme, as shown in FIG. 6, receivers 221A, 221B, and 221C, which receive signals S1, S2, and S3 via paths P1, P2, and P3, are disposed respectively. The timing detector 222 detects the sign received through each path. The sign is set in the receivers 221A, 221B and 221C corresponding to the paths P1, P2 and P3, respectively. Receivers 221A, 221B, and 221C demodulate signals received through paths P1, P2, and P3. The reception output signals of the receivers 221A, 221B, and 221C are synthesized by the combining circuit 223.

In a spread spectrum scheme, signals received through different paths are prevented from interfering with each other. The signals received over the paths P1, P2, P3 are separated and demodulated. When the demodulated output signals received through each path are synthesized, the signal strength is increased and the S / N ratio is improved. In addition, the effects of fading due to multiple paths can be mitigated.

In the above example, for the sake of simplicity, the diversity RAKE scheme is illustrated with three receivers 221A, 221B, 221C and timing detector 222. By the way, in the diversity RAKE type mobile phone terminal device, as shown in Fig. 7, the fingers 251A, 251B, 251C, the searcher 251, and the data synthesizer 253 are arranged. Fingers 251A, 251B, and 251C obtain a demodulation output signal for each path. The searcher 252 detects the signal through multiple paths. The synthesizer 253 synthesizes demodulation data for each path.

In FIG. 7, the received signal as the spread spectrum signal converted to the intermediate frequency is supplied to the input terminal 250. This signal is supplied to quasi-synchronous detection circuit 255. This quasi-synchronous detection circuit 255 is composed of a multiplication circuit. The quasi-synchronous detection circuit 255 multiplies the signal received from the input terminal 250 by the output signal of the PLL synthesizer 256. The output signal of the PLL synthesizer 256 is controlled by the output signal of the frequency synthesizer 257. The quasi-synchronous detection circuit 255 performs orthogonal detection on the received signal.

The output signal of the quasi-synchronous detection circuit 255 is supplied to the A / D converter 258. The A / D converter 258 converts an input signal into a digital signal. At this point, the sampling frequency of the controller 254 is much higher than the frequency of the spread spectrum PN code. In other words, the input signal of the A / D converter 258 is oversampled.

The output signal of the controller 254 is supplied to the fingers 251A, 251B, and 251C. In addition, the output signal of the controller 254 is supplied to the searcher 252. Fingers 251A, 251B, and 251C despread the signals received through each path, synchronize the signals, obtain synchronization of the received signals, demodulate the data of these signals, and detect the frequency error of the signals. .

The searcher 252 obtains the sign of the received signal and assigns the sign of the path to the fingers 251A, 251B, and 251C. In other words, the searcher 252 has a despreading circuit that multiplies the received signal by the PN code and despreads the signal. In addition, the searcher 252 shifts the phase of the PN code and obtains a correlation with the received code under the control of the controller 254. By the correlation between the designation code and the reception code, the sign of each path is determined.

The output signal of the searcher 252 is supplied to the controller 254. The controller sets the phase of the PN code for the fingers 251A, 251B, and 251C in response to the output signal of the searcher 252. Fingers 251A, 251B, and 251C despread the received signal and demodulate the received signal through each phase corresponding to the set phase of the PN code.

This demodulated data is supplied from the fingers 251A, 251B, and 251C to the data synthesizer 253. The data synthesizer 253 synthesizes the received signals received through each path. This synthesized signal is obtained from the output terminal 259.

Fingers 251A, 251B, and 251C detect frequency error. This frequency error is fed to frequency synthesizer 257. By the output of this frequency synthesizer 257, the oscillation frequency of the PLL synthesizer 256 is controlled.

In a cellular telephone system, termination call information, base station information, and the like are sent from a base station. In order to receive such information from the base station, the portable terminal of the cellular telephone system enters the reception mode intermittently in the standby state.

It is more preferable that the timing at which the terminal apparatus enters the reception mode intermittently is short so as to reliably receive information from the terminal station. By the way, since the portable terminal of the portable telephone system is usually driven by an internal battery, power consumption is reduced to prolong the battery's duration. When the timing at which the terminal apparatus enters the reception mode is short, power consumption increases. Therefore, in order to suppress the power consumption, it is more preferable that the timing at which the terminal apparatus enters the reception mode is increased.

In some portable terminal devices of cellular telephone systems, an external power supply terminal is provided for driving the terminal device to an external power source. In this case, power is supplied from a cigarette lighter or the like to an external power supply terminal of the portable terminal device. When the external power supply as described above is used, unlike the case of the internal power supply, there is no need to suppress the power consumption. In this case, it is preferable to reliably receive information from the base station instead of suppressing power consumption.

It is therefore an object of the present invention to provide a terminal device of a portable telephone system, which reduces power consumption when an internal battery is used and ensures that information is received from a base station when an external battery is used. .

Fig. 1 is a block diagram showing the overall structure of a CDMA cellular phone terminal apparatus according to the present invention.

2 is a flowchart for explaining a CDMA mobile phone terminal device according to the present invention.

3A and 3B are timing charts for explaining a CDMA mobile phone terminal device according to the present invention.

4 is a schematic diagram illustrating a multipath.

5 is a block diagram illustrating a multipath.

6 is a block diagram for explaining a diversity RAKE method.

7 is a block diagram illustrating an example of a receiver of a diversity RAKE method.

* Explanation of symbols on the main parts of the drawings

29. Controller 41. Internal battery

42. External power terminal 45. External power detection circuit

The first aspect of the present invention provides an external power supply detecting means for detecting whether external power is supplied, and a power supply for switching the receiving mode between a normal receiving mode and a low power consumption receiving mode in response to an output signal of the external power detecting means. A terminal device of a mobile telephone system including control means.

The second aspect of the present invention comprises the steps of (a) detecting whether external power is supplied and (b) switching the reception mode between a normal reception mode and a low power consumption reception mode according to whether the external power is supplied. A receiving method for a terminal device of a mobile phone system.

When the internal battery is used, since the terminal device is in the reception mode at a relatively long time interval, power consumption can be reduced. Thus, the duration of the internal battery can be extended. When the terminal apparatus is driven by the external power source received from the external power supply terminal, the terminal apparatus enters the reception mode at a relatively short time interval, so that information from the base station can be reliably received.

The above and other objects, features, and advantages of the present invention will become more apparent in light of the following detailed description of the most preferred embodiments of the present invention, as shown in the accompanying drawings.

An embodiment of the present invention will be described with reference to the accompanying drawings. 1 is a block diagram showing an example of a portable terminal used in a CDMA cellular telephone system according to the present invention. The portable terminal uses the diversity RAKE method as a reception method. In the diversity RAKE scheme, signals are received simultaneously from a plurality of paths. This received signal is synthesized.

In Fig. 1, in the transmission mode, a voice signal is input to the microphone 1. The audio signal is supplied to the A / D converter 2. The A / D converter 2 converts analog voice signals into digital voice signals. The output signal of the A / D converter 2 is supplied to the audio compression circuit 3. The speech compression circuit 3 compresses and encodes the digital speech signal. As an example of the compression encoding scheme, various types have been proposed. For example, a method such as QCELP encoding (Qualcomm Code Excited Linear Predictive Coding) may be used. In QCELP, a plurality of coding rates may be used depending on the characteristics of the user's voice and the congestion situation of the communication path. In this case, four coding rates (9.6 kbps, 4.8 kbps, 2.4 kbps and 1.2 kbps) may be selected. To maintain call quality, data can be encoded at the lowest rate. Of course, the voice compression method is not limited to the QCELP method.

The output signal of the speech compression circuit 3 is supplied to the convolutional coding circuit 4. The convolutional coding circuit 4 adds an error correction code to the transmission data as the convolutional code. The output signal of the convolutional coding circuit 4 is supplied to the interleave circuit 5. The interleave circuit 5 interleaves the transmission data. The output signal of the interleave circuit 5 is supplied to the spectrum spreading circuit 6.

The spread spectrum circuit 6 primarily modulates the carrier wave and spreads the resulting signal in the PN code. On the other hand, the spread spectrum circuit 6 primarily modulates the transmission data corresponding to, for example, the balanced QPSK modulation method. Further, the resultant signal is multiplied by the PN code. Since the PN code is a random code, when the PN code is multiplied, the frequency band of the carrier becomes wider. Thus, the carrier is spread spectrum. As an example of a modulation method for transmission data, a balanced QPSK modulation method is used. However, other modulation methods may be used among the various methods proposed.

The output signal of the spread spectrum circuit 6 is supplied to the D / A converter 8 via the band pass filter 7. The output signal of the D / A converter 8 is supplied to the RF circuit 9.

The local oscillation signal is supplied from the PLL synthesizer 11 to the RF circuit 9. The RF circuit 9 multiplies the output signal of the D / A converter 8 by the local oscillation signal of the PLL synthesizer 11, thereby converting the frequency of the transmission signal to a predetermined frequency. The output signal of the RF circuit 9 is supplied to the transmission amplifier 10. After the power of the transmission signal is amplified, the signal is supplied to the antenna 12. Radio waves are sent from the antenna 12 to the base station.

In the reception mode, radio waves transmitted from the base station are received by the antenna 12. Since the radio wave from the base station is reflected by the building or the like, the radio wave reaches the antenna of the mobile terminal via the multipath. When the portable terminal is used in an automobile or the like, the frequency of the received signal may be changed by the Doppler effect.

The output signal of the antenna 12 is supplied to the RF circuit 20. The RF circuit 20 receives a local oscillation signal from the PLL synthesizer 11. The RF circuit 20 converts the received signal into an intermediate frequency signal of a predetermined frequency.

The output signal of the RF circuit 20 is supplied to the semi-synchronous detection circuit 22 via the intermediate frequency circuit 21. The output signal of the PLL synthesizer 23 is supplied to the quasi-synchronous detection circuit 22. The frequency of the output signal of the PLL synthesizer 23 is controlled by the output signal of the frequency synthesizer 32. The quasi-synchronous detection circuit 22 orthogonally detects the received signal.

The output signal of the quasi-synchronous detection circuit 22 is supplied to the A / D converter 24. The A / D converter 24 digitizes the output signal of the quasi-synchronous detection circuit 22. At this time, the sampling frequency of the A / D converter 24 is higher than the frequency of the spectrum-spread PN code. That is, the input signal of the A / D converter is oversampled. The output signal of the A / D converter 24 is supplied to the fingers 25A, 25B, 25C. In addition, the output signal of the A / D converter 24 is supplied to the searcher 28.

As described above, in the receive mode, the signal is received via multipath. To inversely spectralize the received signal, the fingers 25A, 25B, 25C multiply the signal received via a multipath with the PN code. Fingers 25A, 25B, and 25C also output the levels of signals received via multipath and the frequency error of these multipath.

The searcher 28 obtains a plurality of codes of the received signal and assigns the plurality of codes to the plurality of paths. In other words, the searcher 28 includes a despreading circuit that multiplies the received signal by each PN code and despreads the received signal. The searcher 28 shifts the phase of the PN code under the control of the controller 29 and obtains a correlation with the received code. The code of each path is specified by the correlation value between the designated code and the reception code. The code designated by the controller 29 is supplied to the fingers 25A, 25B, 25C.

The received data for each path is supplied to the data synthesizer 30 by the fingers 25A, 25B, and 25C. The data synthesizer 30 synthesizes the received data for each path. The output signal of the data synthesizer 30 is supplied to the AGC circuit 33.

Fingers 25A, 25B, and 25C find the strength of the signal received over each path. The strength of the signal received via each path is supplied to the RSSI synthesizer 31 from the fingers 25A, 25B, 25C. The RSSI synthesizer 31 synthesizes the strengths of the signals received through each path. The output signal of the RSSI synthesizer 31 is supplied to the AGC circuit 33. In order to keep the signal level of the received data constant, the gain of the AGC circuit 33 is controlled.

Frequency error for each path is supplied to the frequency synthesizer 32 from the fingers 25A, 25B, 25C. Frequency synthesizer 32 synthesizes the frequency error for each path. The output signal of the frequency synthesizer 32 is supplied to the PLL synthesizers 11 and 23. Corresponding to the resulting frequency error, the frequencies of the PLL synthesizers 11 and 23 are controlled.

The output signal of the AGC circuit 33 is supplied to the deinterleave circuit 34. The deinterleave circuit 34 deinterleaves the received data interleaved at the transmitting side. The output signal of the deinterleave circuit 34 is supplied to the Viterbi decoding circuit 35. The Viterbi decoding circuit 35 decodes the convolution code by the soft decision processing and the maximum likelihood decoding process. The Viterbi decoding circuit 35 performs an error correction process. The output signal of the Viterbi decoding circuit 35 is supplied to the voice expansion circuit 36.

The speech expansion circuit 36 expands the speech signal compressed by the QCELP method, for example, and decodes the digital speech signal. The digital voice signal is supplied to the D / A converter 37. The D / A converter 37 restores the digital voice signal to an analog voice signal. An analog audio signal is supplied to the speaker 38.

The cellular phone terminal device can be driven by an external power source received from the internal battery 41 and the external power terminal 42. Power from the internal battery 41 is supplied to the terminal 43A of the switch circuit 43. Power from the external power supply terminal 42 is supplied to the terminal 43B of the switch circuit 43. An external power supply detection circuit 45 for detecting whether power is supplied to the external terminal 42 is provided. The external power supply detection circuit 45 controls the switch circuit 43. The output signal of the switch circuit 43 is supplied to the power supply circuit 44.

When no external power is supplied, the switch circuit 43 is placed at the position of the terminal 43A. Power of the internal battery 41 is supplied to the power supply circuit 44. When no external power is supplied to the external power terminal 42, the switch circuit 43 is placed in the position of the terminal 43B. Therefore, power from the external power supply terminal 42 is supplied to the power supply circuit 44. The power supply circuit 44 generates power required for each circuit portion of the cellular phone terminal device. This generated power is supplied to each circuit portion of the cellular phone terminal device.

Therefore, since the cellular phone terminal apparatus has an external power supply terminal 42, the cellular phone terminal device can be driven by an external power source received from the external power terminal 42. As a result, when the cellular phone terminal device is used in a car, the power of the battery of the car can be supplied to the external power supply terminal 42 by a cigarette lighter or the like. When the cellular phone terminal device is driven by an external power source, the user can use it without worrying about the capacity of the internal battery 41.

End call information, base station information, and the like are sent from the base station to the cellular phone terminal of the cellular telephone system. In order to receive information from the base station, the cellular phone terminal apparatus enters the reception mode intermittently in the standby state, thereby saving power consumption. The timing at which the cellular phone terminal apparatus enters the reception mode is preferably short in order to reliably receive information from the base station. However, when the timing at which the cellular phone terminal device enters the reception mode is short, power consumption increases. Thus, the duration of the battery 41 is shortened. By the way, when the external power supply terminal 42 is installed, power can be supplied from the external power supply terminal 42 of the cellular phone terminal device to a cigarette lighter or the like of the car, so that the user can carry it without worrying about the capacity of the internal battery. Telephone terminal devices can be used. In addition, when the timing at which the cellular phone terminal apparatus enters the reception mode becomes short, information can be reliably detected from the base station.

In other words, the output signal of the external power source detection circuit 45 is supplied to the controller 29. The controller 29 performs processing according to the flowchart shown in FIG. 2 in the standby state.

As shown in Fig. 2, in the standby state, it is determined whether or not the external power supply is supplied from the external power supply terminal 42 in correspondence with the external power detection circuit 45 (in step ST1). When no external power supply is supplied from the external power supply terminal 42 (that is, when the determination result is NO in step ST1), the timing of the intermittent reception mode is set to time T ₁ (in step ST2). ). Next, it is determined whether or not the set time T ₁ has elapsed (at step ST3). When the set time T ₁ has elapsed (that is, when the determination result is YES at step ST3), the reception mode is set for a predetermined time period (at step ST4).

When the external power supply is supplied from the external power supply terminal 42, the timing of the intermittent reception mode is set to (T ₂ ) shorter than (T ₁ ) (at step ST5). Next, it is determined whether or not the set time T ₂ has elapsed (at step ST6). When the set time T ₂ has elapsed (that is, when the determination result at step ST6 is YES), the reception mode is set for a predetermined time period (at step ST4).

3A and 3B are schematic diagrams showing the operation relationship of the mobile phone terminal device in the standby state when the mobile phone terminal device is driven by the external power supplied from the internal battery 41 and the external power supply terminal 42. As shown in Fig. 3A, when the internal battery 41 is used, the cellular phone terminal device is placed in the reception mode at intervals of a longer set time T ₁ . Thus, power consumption can be reduced. On the other hand, when the cellular phone terminal device is driven by an external power source supplied from the external power supply terminal 42, the cellular phone terminal device enters the reception mode at intervals of a shorter set time T ₂ . Therefore, the cellular phone terminal apparatus can reliably receive information from the base station.

In the above embodiment, the terminal device of the CDMA cellular telephone system has been described. By the way, it should be noted that the present invention can be applied to cellular telephone terminal apparatuses of the FDMA scheme and the TDMA scheme.

According to the present invention, when the internal battery is used, the timing at which the cellular phone terminal enters the reception mode becomes longer. Thus, power consumption can be reduced. As a result, the duration of the internal battery can be extended. On the other hand, when the cellular phone terminal apparatus is driven by an external power source supplied from an external power supply terminal, the timing at which the cellular phone terminal apparatus enters the reception mode becomes shorter. Thus, the cellular phone terminal apparatus can reliably receive information from the base station.

Although the present invention has been described in terms of its most preferred embodiments, it will be apparent to those skilled in the art that the above and various other modifications, omissions, and additions in form and detail may be made without departing from the spirit and scope of the present invention. .

Claims (6)

In a terminal device of a mobile phone system, External power detecting means for detecting whether external power is supplied; Power supply control means for switching a reception mode between a normal reception mode and a low power consumption reception mode according to the output signal of the external power detection means; Terminal device, characterized in that configured to include. The method of claim 1, And when the external power is not supplied, the power supply control means switches the reception mode to the low power consumption reception mode. The method according to claim 1 or 2, And a timing at which the terminal device intermittently enters the reception mode of the low power consumption reception mode is longer than the normal reception mode. In the reception method for a terminal device of a cellular phone system, (a) detecting whether an external power source is supplied; (b) switching the reception mode to a normal reception mode or a low power consumption reception mode according to whether external power is supplied; Receiving method comprising a. The method of claim 4, wherein And when the external power is not supplied, the power supply control means switches the reception mode to the low power consumption reception mode. The method according to claim 4 or 5, And the timing at which the terminal apparatus enters the reception mode of the low power consumption reception mode is longer than the normal reception mode.