JP2001156752A - Mobile wireless terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile wireless terminal of a CDMA system that ensures stable communication quality even under a radio wave environment with rapid fading. SOLUTION: A control section 100 is provided with a reception energy discrimination means 100a that discriminates an Ec/Io of a received signal to realize a new control function and with a switch changeover control means 100b that selects an antenna, temporarily receives the signal through the remaining antenna when the Ec/Io of the signal received through the selected antenna is lower than a preset level at sending and receiving or at a speech to detect the Ec/Io and uses the antenna with the excellent Ec/Io for the reception.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a code division multiple access (CDMA) used in a mobile radio communication system such as an automobile telephone system and a portable telephone system.
ivision Multiple Access) system.

[0002]

2. Description of the Related Art As is well known, a mobile radio communication system employing a CDMA system has recently been receiving attention. This system employs a spread spectrum communication system as a communication system. Here, a conventional mobile radio terminal device in the mobile communication system will be described with reference to FIG. In particular, here, the reception system according to the present invention will be mainly described.

The transmitting device 12 modulates transmission data such as digitized voice and data by a digital modulation method such as PSK modulation, and converts the modulated data into a wideband baseband signal using a spreading code. Convert. Then, the spread signal is up-converted into a radio frequency signal, input to the first antenna 10 through the duplexer 11, radiates the signal into space from the first antenna 10, and transmits the signal to a base station (not shown). Sent to

On the other hand, a radio signal transmitted from the base station is received by a first antenna 10 and input to a receiving device 13 through a duplexer 11. The receiving device 13 includes a radio circuit 14, an intermediate frequency circuit 15, and a Rake (rake) receiver 16.

First, in the radio circuit 14, a radio signal received from the duplexer 11 is input to an attenuator 14a.
It is attenuated by a preset amount. The signal that has passed through the attenuator 14a is amplified to a predetermined level by an amplifier 14b, mixed with a signal generated by a frequency synthesizer 14d by a mixer 14c, and down-converted to an intermediate frequency.

[0006] The signal down-converted to the intermediate frequency is input to an intermediate frequency circuit 15 and amplified to a predetermined level by an amplifier 15a. The result of the amplification is obtained by passing only a desired band through a band-pass filter (BPF) 15b and using a frequency synthesizer 15d by a mixer 15c.
The signal is mixed with the signal generated in step (1) and converted into a baseband signal. This baseband signal is converted into a digital signal by an A / D converter (A / D) 15e,
It is input to the Rake receiver 16.

[0007] The Rake receiver 16 includes a searcher 16a.
, Fingers 16b, 16c, 16d, and a symbol combiner 16e. The digital signal is input to the searcher 16a and the fingers 16b, 16c, 16d, respectively.

The searcher 16a detects a signal arriving on the terminal from the base station via a plurality of paths, that is, a so-called multipath, and performs despreading using the same spreading code used for spreading on the transmitting side. Then, for each despread result, Ec / Io (Io is the energy of all the received signals, Ec is the signal level of the desired wave) and the delay time difference (delay profile) between them is obtained. Then, the reception timing (despread timing) of the path is obtained based on these, and the obtained timing is assigned to each of the fingers 16b, 16c, and 16d.

The fingers 16b, 16c and 16d despread the digital signal at the despreading timing assigned by the searcher 16a using the same spreading code used for spreading on the transmitting side.

The symbol combiner 16e includes a finger 16
The multipath components despread by b, 16c, and 16d are symbol-synthesized in consideration of the despread timing assigned to each of the fingers 16b, 16c, and 16d. The signal that has been symbol-synthesized by the symbol synthesizer 16e is subjected to demodulation corresponding to the digital modulation on the transmission side in the subsequent signal processing unit 17, and the received data is reproduced.

In this mobile radio terminal device, a control unit (not shown) performs control for handoff in accordance with Ec / Io of the pilot signal obtained by searcher 16a. In this control, when intermittent reception is performed in the standby reception state, the Ec / Io becomes (1) lower than a specified value, (2) is reduced to a specified value or more compared to the previous reception, or (3) ) If the difference from Ec / Io of the neighboring base station is within a specified value or the like, in order to perform handoff, Ec / Io of a pilot signal from another base station is required.
Is measured. Then, E of the pilot signal of another base station is
When c / Io becomes larger than the specified value, handoff to another base station is performed.

When the mobile radio terminal is in a call state, Ec / Io of the pilot signal of the currently connected base station becomes lower than a specified value, and Ec / Io of the pilot signal of a neighboring base station. Is larger than a prescribed value, handoff is performed while performing communication with a plurality of base stations including a base station satisfying a predetermined condition.

The advantages of the CDMA system as described above include (1) excellent confidentiality of communication because the spread spectrum technique is used, (2) high fading resistance by using the Rake reception method, and (3) communication. Stable handoff without instantaneous interruption, so-called soft handoff is possible.

However, in the conventional mobile radio terminal of the CDMA system, since the multipath resolution of the searcher 16a is determined by the reciprocal of the chip rate, if the spread of the multipath delay time is smaller than this resolution, as described above. To the fingers 16b, 16c, 16
Symbol combination cannot be performed separately at d.

That is, the fingers 16b, 16c, 16
The multipath (direct wave, first reflected wave, second reflected wave) received at d has a small delay time spread and cannot be rake-received unless delayed by the reciprocal of the chip rate.

As described above, depending on the delay time difference between the multipaths, the reflected wave delayed from the direct wave cannot be reproduced, so that there is a problem that the fading resistance is reduced and stable communication quality cannot be secured. . Note that this problem occurs more remarkably in a low-speed movement such as walking or in a stationary state than in a high-speed movement.

[0017]

In addition, the conventional CDMA
In the mobile radio terminal of the system, there is a problem that stable communication quality may not be ensured in a radio wave environment in which intense fading occurs.

The present invention has been made in order to solve the above-described problem, and is a CD capable of ensuring stable communication quality even under a radio wave environment in which intense fading occurs.
An object of the present invention is to provide a mobile radio terminal device of the MA system.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a wireless communication method for connecting to a plurality of wireless base stations connectable to a communication network by a CDMA system, thereby enabling communication with a communication station on the communication network. In a mobile radio terminal device, two antennas, an antenna selecting means for selecting one of the two antennas as an antenna to be used in accordance with a control signal, and an antenna received through the antenna selected by the antenna selecting means Receiving energy determining means for obtaining a ratio Ec / Io of a total power spectral density Ec in a receiving band to pilot energy Io accumulated over one PN chip period of a signal; and a radio base station which receives an incoming signal from the radio base station. If the reception quality is below a predetermined value when transmitting a transmission signal to the mobile station or during communication through the wireless base station, the control signal is canceled. The antenna to be used is given to the antenna selection means, and the antenna to be used is replaced with the remaining antenna in place of the antenna currently selected by the antenna selection means, and reception is performed. The ratio obtained by the reception energy determination means before and after this switching is obtained. By comparing Ec / Io, the ratio Ec / Io
And an antenna switching control means for providing a control signal for selecting an antenna having a larger value to the antenna selection means.

In the mobile radio terminal having the above-described configuration, the reception quality is determined when the incoming signal is received from the radio base station, when the transmission signal is transmitted to the radio base station, or during communication through the radio base station. If the value is equal to or less than the value, the control signal is given to the antenna selection means, and the antenna to be used is switched to the other antenna instead of the antenna currently selected by the antenna selection means, and reception is performed. And the ratio Ec /
By comparing Io, the antenna with the larger ratio Ec / Io is selected.

Therefore, according to the mobile radio terminal device having the above-described configuration, even when a strong fading occurs at the time of outgoing / incoming call or communication, even under a poor radio wave environment, the mobile radio terminal device can perform the E-mail communication.
Since the antenna with the larger c / Io is selected, stable communication quality can be ensured.

Further, in order to achieve the above object, the present invention provides a plurality of radio base stations connectable to a communication network by CDM.
In a mobile wireless terminal device that is wirelessly connected by the A method and is capable of communicating with a communication station on a communication network, an antenna selection that selects one of the two antennas as one of two antennas according to a control signal Means for determining the ratio Ec / Io of the total power spectral density Ec in the receiving band to the pilot energy Io accumulated over one PN chip period of the signal received through the antenna selected by the antenna selecting means; At the time of waiting for an incoming call, prior to signal reception from the radio base station at the reception timing assigned to the own device by the radio base station, the two antennas are sequentially switched to perform reception, and before and after the switching, the reception energy determining means is determined. By comparing the ratio Ec / Io obtained in the above, the antenna having the larger ratio Ec / Io is selected. A control signal that has been so configured by including an antenna switch control means for providing the antenna selection means.

In the mobile radio terminal having the above configuration, when waiting for an incoming call, two antennas are sequentially switched prior to signal reception from the radio base station at the reception timing assigned to the radio base station by the radio base station, and reception is performed. And the ratio Ec / Io obtained by the received energy determination means before and after the switching is compared, and the antenna having the larger ratio Ec / Io is selected.

Therefore, according to the mobile radio terminal having the above-described configuration, the antenna with the larger Ec / Io is selected during standby for incoming calls even in a radio wave environment in which intense fading occurs. Quality can be ensured.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a CDMA mobile radio terminal according to an embodiment of the present invention. However, in FIG. 1, the conventional CDM
The same parts as those in FIG. 6 showing the configuration of the mobile radio terminal apparatus of the A system are denoted by the same reference numerals, and here, the description will be focused on the receiving system according to the present invention.

The transmitting device 12 modulates transmission data such as digitized voice and data by a digital modulation method such as PSK modulation, and converts the modulated data into a wideband baseband signal using a spreading code. Convert. Then, the spread signal is up-converted into a radio frequency signal, input to the first antenna 10 through the duplexer 11, radiates the signal into space from the first antenna 10, and transmits the signal to a base station (not shown). Sent to

On the other hand, the radio signal transmitted from the base station is received by the first antenna 10 and input to the receiving device 13a through the duplexer 11. Receiver 13a
Is a switch 20, a radio circuit 14, and an intermediate frequency circuit 1
5 and a Rake (rake) receiver 16.

First, the switch 20 receives a received signal input from the duplexer 11 and a received signal received by the second antenna 18 and limited to a desired band by a band-pass filter (BPF) 19. Then, switching control is performed by a control unit 100 described later, and one of the two received signals is input to the wireless circuit 14. The second antenna 18 is provided inside the housing of the mobile wireless terminal device.

In the radio circuit 14, the radio signal received from the duplexer 11 is input to the attenuator 14a, where it is attenuated by a predetermined amount. The signal that has passed through the attenuator 14a is amplified to a predetermined level by an amplifier 14b, then mixed with a local oscillation signal generated by a frequency synthesizer 14d by a mixer 14c, and down-converted to an intermediate frequency.

The signal down-converted to the intermediate frequency is input to the intermediate frequency circuit 15 and is amplified to a predetermined level by the amplifier 15a. The result of the amplification is obtained by passing only a desired band through a band-pass filter (BPF) 15b and using a frequency synthesizer 15d by a mixer 15c.
The signal is mixed with the signal generated in step (1) and converted into a baseband signal. This baseband signal is converted into a digital signal by the A / D converter 15 e and input to the Rake receiver 16.

The rake receiver 16 includes a searcher 16a
, Fingers 16b, 16c, 16d, and a symbol combiner 16e. The digital signal is input to the searcher 16a and the fingers 16b, 16c, 16d, respectively.

The searcher 16a detects a signal arriving from the base station to the terminal via a plurality of paths, that is, a so-called multipath, and performs despreading using the same spreading code used for spreading on the transmitting side. Then, Ec / Io is obtained for each despread result, and the delay time difference (delay profile) is obtained. Then, the reception timing (despread timing) of the path is obtained based on these, and the obtained timing is assigned to each of the fingers 16b, 16c, and 16d.

The fingers 16b, 16c, and 16d perform the despreading process on the digital signal at the despreading timing assigned by the searcher 16a using the same spreading code used for spreading on the transmitting side.

The symbol combiner 16e includes a finger 16
The multipath components despread by b, 16c, and 16d are symbol-synthesized in consideration of the despread timing assigned to each of the fingers 16b, 16c, and 16d. The signal that has been symbol-synthesized by the symbol synthesizer 16e is subjected to demodulation corresponding to the digital modulation on the transmission side in the subsequent signal processing unit 17, and the received data is reproduced.

The control unit 100 includes a CPU, a ROM and an R
AM, etc., wherein the CPU is the RO
In accordance with a control program and control data stored in M, each unit of the mobile wireless terminal device is generally controlled, and for example, control relating to handoff is performed.

The control unit 100 includes a reception energy determination unit 100a and a switch switching control unit 100b in order to realize a new control function. The reception energy determining means 100a is provided with the searcher 16a and the finger 16
b, 16c, 16d, it is determined which one of the first antenna 10 and the second antenna 18 has a larger Ec / Io based on the Ec / Io of the received signal obtained respectively. . The switch switching control means 100b includes:
The switch 20 is switched and controlled according to the result of the determination by the reception energy determining means 100a. Although not shown, there is a power supply unit having a battery for supplying power for operating the above-described units as a component of the present apparatus.

Next, the antenna switching control operation of the mobile radio terminal having the above configuration will be described. This control operation is performed by the control unit 100. First, the antenna switching control operation at the time of calling or receiving will be described. FIG. 2 is a flowchart of the operation, in which a user makes a transmission request through a user interface (not shown), receives an incoming signal from a base station, and continuously receives a signal from the base station through a paging channel.
This control operation is started.

In step 2a, a signal from the base station is continuously received through the paging channel, Ec / Io of the pilot channel is detected, and the process proceeds to step 2b. At this time, either one of the first antenna 10 and the second antenna 18 is selected by the switch 20, and a reception signal from the selected antenna is used in the receiving device 13a.

In step 2b, the reception energy determination means 100a determines whether Ec / Io detected in step 2a is less than a preset threshold. Here, if Ec / Io detected in step 2a is less than the threshold, the process proceeds to step 2c, and if Ec / Io is equal to or greater than the threshold, the process proceeds to step 2g.

At step 2c, the switch switching control means 100b controls the switching of the switch 20 and selects one of the first antenna 10 and the second antenna 18 from step 2c.
Switch to the antenna that was not selected in a, and proceed to step 2d.

In step 2d, a signal from the base station is continuously received through the paging channel by the antenna selected in step 2c and the pilot channel E is received.
c / Io is detected, and the routine goes to step 2e.

In step 2e, Ec / Io detected in step 2d is compared with Ec / Io detected in step 2a. Here, Ec / Io detected in step 2d
If is larger, the process proceeds to step 2g.
If Ec / Io detected in step 2d is not larger, the process proceeds to step 2f.

In step 2f, the switch switching control means 100b controls the switching of the switch 20 and selects one of the first antenna 10 and the second antenna 18 from step 2f.
Switch to the antenna selected in step a, step 2
Go to g.

In step 2g, it is determined whether or not the transmission or the incoming call has been completed, which has started the processing. Here, if the processing has been completed, the process is terminated. On the other hand, if the processing has not been completed, the process proceeds to step 2a.

Next, an operation for controlling antenna switching during a call will be described. FIG. 3 is a flowchart of the control operation when a communication link is established with the base station to start a call and when signals from the base station are continuously received through a traffic channel.

In step 3a, a signal from the base station is continuously received through the traffic channel, Ec / Io of the pilot channel is detected, and the process proceeds to step 3b. At this time, either one of the first antenna 10 and the second antenna 18 is selected by the switch 20, and a reception signal from the selected antenna is used in the receiving device 13a.

In step 3b, the reception energy determination means 100a determines whether Ec / Io detected in step 3a is less than a preset threshold. Here, if Ec / Io detected in step 3a is less than the threshold, the process proceeds to step 3c, while if Ec / Io is equal to or greater than the threshold, the process proceeds to step 3g.

In step 3c, the switch switching control means 100b controls the switching of the switch 20 and selects one of the first antenna 10 and the second antenna 18 from step 3c.
Switch to the antenna that was not selected in a, and proceed to step 3d.

In step 3d, a signal from the base station is continuously received through the traffic channel by the antenna selected in step 3c and the pilot channel E is received.
c / Io is detected, and the routine goes to Step 3e.

In step 3e, Ec / Io detected in step 3d is compared with Ec / Io detected in step 3a. Here, Ec / Io detected in step 3d
If is larger, the process proceeds to step 3g.
If Ec / Io detected in step 3d is not larger, the process proceeds to step 3f.

In step 3f, the switch switching control means 100b controls the switching of the switch 20 and selects one of the first antenna 10 and the second antenna 18 from step 3f.
Switch to the antenna selected in a, step 3
Go to g.

In step 3g, it is determined whether or not the call has ended, which has led to the start of the process. here,
If the processing has been completed, the process is terminated, while if not completed, the process proceeds to step 3a.

Next, a description will be given of an antenna switching control operation when waiting for an incoming call. FIG. 4 is a flowchart thereof. At the time of waiting for an incoming call, a signal from the base station is intermittently received through a paging channel as shown in FIG.

In the Idle section shown in this figure, the paging channel is received, while in the Sleep section, the power of the receiving device 13a is turned off. Further, the Idle section includes a warm-up period until the operation of the receiving device 13a, to which power is turned on, is stabilized, and a reception section for monitoring an incoming signal.

First, in step 4a, it is determined whether or not the current timing is a warm-up period. Here, in the case of the warm-up period, the process proceeds to step 4b. On the other hand, in the case of not the warm-up period, the process returns to step 4a and waits for the arrival of the warm-up period.

In step 4b, the switch switching control means 100b controls the switching of the switch 20, detects Ec / Io of the pilot channel of the paging channel through the first antenna 10 during the warm-up period, and proceeds to step 4c. I do.

In step 4c, the switch switching control means 100b switches the switch 20, detects Ec / Io of the pilot channel of the paging channel through the second antenna 18 during the warm-up period, and proceeds to step 4d. I do.

In step 4d, the reception energy determining means 100a detects Ec / Io by the first antenna 10 detected in step 4b, and detects Ec / Io in step 4c.
It is determined which of Ec / Io by the second antenna 18 is larger.

Here, the first detected at step 4b is
If Ec / Io by the antenna 10 is larger,
The process proceeds to step 4e. On the other hand, if Ec / Io by the second antenna 18 detected in step 4c is larger, the process proceeds to step 4f.

In step 4e, the switch switching control means 100b switches the switch 20 to perform reception through the first antenna 10 in order to perform reception in a reception section, and proceeds to step 4g.

In step 4f, the switch switching control means 100b switches the switch 20 to perform reception in the reception section so as to perform reception through the second antenna 18, and shifts to step 4g.

In step 4g, it is determined whether there is an outgoing call request from the user or whether an incoming signal has been received from the base station. Here, when there is an outgoing call request from the user or when an incoming signal is received from the base station, the process is terminated, and when these do not occur, the process proceeds to step 4a.

As described above, in the mobile radio terminal device having the above-described configuration, during transmission / reception, or during a call, if the Ec / Io of the received signal through the selected antenna drops below a preset level, the signal remains. Ec / Io is detected by temporarily receiving through one antenna, and then Ec / Io is detected.
/ Io uses a good antenna for reception.

In other words, when outgoing / incoming calls or during a call, if Ec / Io is temporarily reduced due to multipath fading and stable communication quality cannot be ensured, Ec / Io is good. The receiving is performed using the other antenna.

Since the reflected wave that lags behind the direct wave does not delay more than a specified value (the reciprocal of the chip rate),
When rake reception cannot be performed and reproduction is not possible, the reflected wave or a signal from another base station becomes an interference wave, and Ec / Io decreases.

For this reason, as described above, when Ec / Io decreases and there is a possibility that stable communication quality cannot be ensured, the better Ec / Io (for example, different directivity) is obtained.
Reception using an antenna increases the possibility of capturing a reflected wave that is delayed from the direct wave by the specified value or more.

Therefore, according to the mobile radio terminal having the above-described configuration, stable communication quality can be ensured even in a radio wave environment in which intense fading occurs during outgoing / incoming calls or during a call.

In the mobile radio terminal having the above configuration,
At the time of waiting for an incoming call, prior to the reception in the reception section, the two antennas are switched and received during the warm-up period to detect Ec / Io, respectively. Is used for reception.

Therefore, according to the mobile radio terminal having the above configuration, stable communication quality can be ensured during standby for incoming calls even in a radio wave environment in which intense fading occurs.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, when the Ec / Io of the received signal through the selected antenna drops below a preset level during outgoing / incoming calls or during a call, the signal is temporarily received through the remaining antenna. To detect Ec / Io.

However, instead of this, when the handoff condition is satisfied, when the base station cannot be acquired, or when a predetermined number of frame errors continue, reception is temporarily performed through the remaining antenna to obtain Ec. The same effect can be obtained by detecting / Io and then using an antenna with good Ec / Io for reception. It goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0072]

As described above, according to the present invention, when an incoming signal is received from a radio base station, when an outgoing signal is transmitted to the radio base station, or during communication through the radio base station, reception is performed. If the quality is equal to or less than a predetermined value, a control signal is given to the antenna selection means, and the antenna to be used is
In place of the antenna selected by the antenna selecting means, reception is performed by switching to the remaining antenna, and the ratio Ec obtained by the reception energy determining means before and after this switching is performed.
By comparing / Io, the antenna with the larger ratio Ec / Io is selected.

Therefore, according to the present invention, the antenna with the larger Ec / Io is selected even in a poor radio wave environment due to intense fading at the time of transmission / reception or at the time of communication. A mobile radio terminal device capable of ensuring the communication quality as described above can be provided.

Also, according to the present invention, when waiting for an incoming call,
Prior to signal reception from the radio base station at the reception timing allocated to the own device by the radio base station, the two antennas are sequentially switched to perform reception, and the ratio Ec obtained by the reception energy determination means before and after this switching. / Io
And the antenna with the larger ratio Ec / Io is selected.

Therefore, according to the present invention, the antenna with the larger Ec / Io is selected even in a radio wave environment in which intense fading occurs when waiting for an incoming call, so that stable communication quality can be ensured. A mobile wireless terminal device capable of performing the above can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration of an embodiment of a mobile wireless terminal device according to the present invention.

FIG. 2 is a flowchart for explaining an antenna switching control operation of the mobile wireless terminal device shown in FIG.

FIG. 3 is a flowchart for explaining an antenna switching control operation of the mobile wireless terminal device shown in FIG. 1 during a call;

FIG. 4 is a flowchart for explaining an antenna switching control operation of the mobile wireless terminal device shown in FIG. 1 when waiting for an incoming call;

FIG. 5 is a diagram for explaining intermittent reception and an antenna switching control operation of the mobile wireless terminal device shown in FIG. 1 when waiting for an incoming call;

FIG. 6 is a circuit block diagram showing a configuration of a conventional mobile wireless terminal device.

[Explanation of symbols]

 Reference Signs List 10 first antenna 11 duplexer 12 transmitter 13a receiver 14 radio circuit 14a attenuator 14b, 15a amplifier 14c, 15c mixer 14d, 15d frequency synthesizer 15 intermediate frequency circuit 15b, 19 ... Band pass filter (BPF) 15e ... A / D converter 16 ... Receiver 16a ... Searcher 16b, 16c, 16d ... Finger 16e ... Symbol combiner 17 ... Signal processing unit 18 ... Second antenna 20 ... Switch 100 ... Control Unit 100a: Received energy determination unit 100b: Switch switching control unit

Claims (6)

[Claims] 1. A mobile wireless terminal device capable of wirelessly connecting to a plurality of wireless base stations connectable to a communication network by a CDMA (Code Division Multiple Access) method and communicating with a communication station on the communication network. An antenna selecting means for selecting one of the two antennas as an antenna in accordance with a control signal; and a signal received through the antenna selected by the antenna selecting means being accumulated for one PN chip period. Receiving energy determination means for obtaining a ratio Ec / Io of the total power spectrum density Ec within the receiving band to the pilot energy Io, and the control is performed when the reception quality is equal to or less than a predetermined value when an incoming signal is received from the radio base station. The signal is provided to the antenna selection means, and the antenna to be used is currently selected by the antenna selection means. On behalf of the antenna, performs reception is switched to one of the antenna remain, this switching said determined by said received energy determination means before and after the ratio Ec /
An antenna switching control unit for comparing the Io with the antenna selecting unit and providing the control signal for selecting the antenna having the larger ratio Ec / Io to the antenna selecting unit. 2. A mobile wireless terminal device capable of wirelessly connecting to a plurality of wireless base stations connectable to a communication network by a CDMA (Code Division Multiple Access) method and capable of communicating with a communication station on the communication network. An antenna selecting means for selecting one of the two antennas as an antenna in accordance with a control signal; and a signal received through the antenna selected by the antenna selecting means being accumulated for one PN chip period. Receiving energy determining means for determining a ratio Ec / Io of the total power spectral density Ec in the receiving band to the pilot energy Io, and if a reception quality is equal to or less than a predetermined value when a transmission signal is transmitted to the radio base station, The control signal is provided to the antenna selection means, and the antenna to be used is currently selected by the antenna selection means. In place of the present antenna, reception is performed by switching to the other antenna, and before and after the switching, the ratio Ec / Io obtained by the reception energy determination means is compared, and the antenna having the larger ratio Ec / Io is determined. Antenna switching control means for providing the control signal to be selected to the antenna selection means. 3. A mobile radio terminal device capable of wirelessly connecting to a plurality of radio base stations connectable to a communication network by a CDMA (Code Division Multiple Access) method and communicating with a communication station on the communication network. An antenna selecting means for selecting one of the two antennas as an antenna in accordance with a control signal; and a signal received through the antenna selected by the antenna selecting means being accumulated for one PN chip period. Receiving energy determining means for obtaining a ratio Ec / Io of the total power spectral density Ec within the receiving band to the pilot energy Io, and if the receiving quality is equal to or less than a predetermined value during communication through the radio base station, the control signal is transmitted to an antenna. Given to the selection means,
The antenna to be used is switched to the remaining antenna instead of the antenna currently selected by the antenna selection means, and reception is performed. The ratio Ec / Io obtained by the reception energy determination means before and after this switching is determined. An antenna switching control unit for providing the antenna selection unit with the control signal for selecting the antenna having the larger ratio Ec / Io. 4. The antenna switching control means, assuming that the reception quality is equal to or less than a predetermined value, the ratio Ec / Io
The mobile radio terminal device according to any one of claims 1 to 3, wherein the value is smaller than a preset value. 5. The antenna switching control unit according to claim 1, wherein the case where the reception quality is equal to or less than a predetermined value is a case where a predetermined number of frame errors are continuous.
The mobile wireless terminal device according to claim 3. 6. A mobile wireless terminal device capable of wirelessly connecting to a plurality of wireless base stations connectable to a communication network by a CDMA (Code Division Multiple Access) method and communicating with a communication station on the communication network. An antenna selecting means for selecting one of the two antennas as an antenna in accordance with a control signal; and a signal received through the antenna selected by the antenna selecting means being accumulated for one PN chip period. Energy determining means for determining a ratio Ec / Io of the total power spectral density Ec in the receiving band to the pilot energy Io, and a signal from the radio base station at a reception timing allocated to the radio base station by the radio base station when waiting for an incoming call. Prior to signal reception, the two antennas are sequentially switched to perform reception, respectively. Switching by comparing the ratio Ec / Io which has been determined by the received energy determination means before and after,
An antenna switching control unit that supplies the control signal for selecting the antenna having the larger ratio Ec / Io to the antenna selection unit.