JP3370865B2 - Soft handover method and mobile station - Google Patents

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 (hereinafter abbreviated as CDMA) mobile communication system in which a mobile station performs a soft handover in which a mobile station moves from a handover source base station to a handover destination base station. Relates to a different frequency soft handover method, a base station apparatus and a mobile station apparatus in a CDMA mobile communication system using different frequency bands.

[0002]

2. Description of the Related Art In a CDMA mobile communication system, a mobile station is used as a handover source radio line between a handover source base station and a mobile station when performing a soft handover for shifting from a handover source base station to a handover destination base station. If the handover target base station does not support the same frequency band as the existing frequency band, or if the handover target base station has no available wireless channel capacity, it is used in the handover source wireless line. It is necessary to set up a wireless link in a frequency band different from the frequency band used between the handover destination base station and the mobile station to perform soft handover.

[0003]

As described above, in order to perform a different frequency soft handover by setting a radio line in a frequency band different from that of the handover source radio line between the handover destination base station and the mobile station, It is sufficient to allow the mobile station to simultaneously transmit and receive the above frequencies, but in order for the mobile station to transmit and receive multiple frequencies at the same time, it is necessary to equip the mobile station with multiple radio units, and the hardware configuration of the mobile station is large. Therefore, there is a problem that it is difficult to downsize and it is uneconomical.

The present invention has been made in view of the above,
It is an object of the present invention to provide a mobile communication system, a base station apparatus and a mobile station apparatus in a CDMA mobile communication system which can realize different frequency soft handover with only one radio unit in the mobile station and can achieve miniaturization and economy. To do.

[0005]

In order to achieve the above object, the present invention according to claim 1 is based on a code division multiple access system.
In a mobile communication system, the mobile station
A soft handset that moves from the base station to the handover destination base station
The mobile station is a
In the first radio frame using the first frequency band in
The step A of communicating with the handover source base station,
Destination base station cannot use the first frequency band
In this case, the mobile station and the handover destination base station are
The second frequency band that can be used by the handover destination base station
Step B of selecting, and the mobile station is configured to use the first radio frame.
At a timing not used for information transmission
In a second radio frame using the second frequency band,
Handover source base station and handover destination base station
The handover source base station by communicating with
And the step C of migrating to the handover destination base station
And summarized in that that.

According to the first aspect of the present invention, since the frequency band that can be used by the handover destination base station in the unused portion of the handover source wireless circuit frame is used as the handover destination wireless line,
Different frequency soft handover can be performed with one radio unit without increasing the radio unit of the mobile station apparatus according to each frequency, and downsizing and power saving can be achieved.

The present invention according to claim 2 is directed to code division.
In a multiple access mobile communication system, a mobile station
Transition from handover source base station to handover destination base station
In the soft handover method, the mobile station
All timings set on the first physical channel
In the first radio frame using the first frequency band in
The step A of communicating with the handover source base station,
Destination base station cannot use the first frequency band
In this case, the mobile station and the handover destination base station are
The second frequency band that can be used by the handover destination base station
Step B of selecting, the mobile station and the handover source base
The second physical channel is set up with the ground station, and the second physical channel is set.
Step C of setting a second radio frame on the physical channel
And the mobile station uses the first radio frame or the first radio frame.
A technique for assigning information to be transmitted to both of the two wireless frames
Step D, the mobile station selects the first radio frame and the previous
Note that the second wireless frame is used for the information transmission.
Used for information transmission using the first frequency in
The second frequency band is used at the timing not
And the mobile station is configured in the step E.
The first wireless frame and the second wireless frame
In the frame, the handover source base station and the handover
By communicating with the destination base station.
The process of migrating from the source base station to the handover destination base station
The point is to have F.

According to the second aspect of the present invention, a new physical channel is set in addition to the current physical channel, the transmission information amount is divided on both physical channels, and the frequency is switched at each divided time. , The same frequency is handled by both physical channels at the same time, and the information of each frequency channel is transmitted across both physical channels. Therefore, the radio unit of the mobile station device does not increase according to each frequency, and Different frequency soft handover can be performed as it is, and downsizing and power saving can be achieved.

Furthermore, the present invention according to claim 3 provides the invention according to claim 1.
Or the invention according to 2, wherein the handover source base station
Spread from the station to the handover destination base station
The gist is to make the code phase continuous .

According to the present invention of claim 3, the hand is
Frequency band that can be used by the overdestination base station (second frequency
Band) to use as a handover destination wireless line
The spreading code phase is continuous,
Since it is not necessary to establish spread code synchronization after switching the wave number,
The reason is simplified.

The present invention according to claim 4 is the code division.
In a multiple access mobile communication system,
Software that moves from the source base station to the handover destination base station
A mobile station that implements a handover,
Communicate with the source base station and the handover destination base station.
In the radio frame, with the handover source base station
The timing of the first frequency band used between
Second frequency band used with the handover destination base station
Corresponding to the timing of the first frequency band or the
Modulation and demodulation processing and spreading processing are performed in the second frequency band respectively.
The gist is to perform frequency switching control as described above.

According to the present invention of claim 4, a mobile station
The device is assigned to the wireless link with the handover source base station
Timing of the allocated frequency band (first frequency band) and
The frequency assigned to the wireless link with the handover destination base station
Corresponding to the timing of the wave number band (second frequency band)
Modulation / demodulation processing and spreading processing are performed at each frequency
Mobile station device
Does not increase the number of radio units for each frequency
Different frequency soft handover can be performed without changing the radio part
It is possible to achieve downsizing and power saving.

The present invention according to claim 5 is the code division.
In a multiple access mobile communication system,
Software that moves from the source base station to the handover destination base station
A mobile station that implements a handover,
Between the source base station and the handover destination base station,
Set a first physical channel and a second physical channel,
On the first physical channel and the second physical channel
A first wireless frame and a second wireless frame configured respectively.
In the line frame, the handover source base station and the handover
To communicate with the handover target base station,
And in each of the second radio frame
The first frequency used with the handover source base station
Between several timings and the handover destination base station
Corresponding to the timing of the second frequency band used in
In the first frequency band or the second frequency band, respectively
Frequency switching to perform modulation / demodulation processing and spreading processing
The gist is to have a control means for controlling.

The present invention according to claim 6 provides the invention according to claim 4.
Alternatively, in the invention described in the paragraph 5, the handover source base station
Spread from the station to the handover destination base station
The gist is to make the code phase continuous.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are block diagrams showing the configurations of main parts of a mobile station apparatus and a base station apparatus for implementing a different frequency soft handover method in a CDMA mobile communication system according to an embodiment of the present invention.

The mobile station apparatus shown in FIG. 1 has an antenna 1 for receiving a radio signal from a base station and transmitting a radio signal to the base station, and the signal from the base station received by the antenna 1 is transmitted and received. The signal is supplied to the demodulation circuit 7 via the distribution circuit 3 and the reception circuit 5, and normal demodulation and despreading are performed.
The signal thus demodulated and despread is the decoding circuit 13
Decrypted by and supplied to the man-machine interface.

A transmission signal such as a voice signal from the man-machine interface is coded by the coding circuit 15, primary-modulated and spread by the modulation circuit 19, and then transmitted through the transmission circuit 21 and the transmission / reception distribution circuit 3 to the antenna. 1 to the base station.

Further, the mobile station apparatus shown in FIG. 1 has a frequency switching control circuit 23 and an oscillation circuit 25, and the oscillation circuit 2
Reference numeral 5 supplies a signal of frequency F1 or F2 to the modulation circuit 19 and the demodulation circuit 7 according to the frequency switching control voltage V1 or V2 supplied from the frequency switching control circuit 23, and the modulation circuit 19 and the demodulation circuit 7 at the frequency. Control the modulation and demodulation in.

On the other hand, the base station apparatus shown in FIG. 2 has an antenna 31 for receiving a radio signal from a mobile station and transmitting a radio signal to the mobile station, and the signal from the mobile station received by the antenna 31 is received. The transmission / reception distribution circuit 33 and the reception circuit 35
To the demodulation circuit 37, where despreading using a spreading code and normal demodulation are performed. Then, the demodulated signal is decoded into a transmission signal and a control signal by the decoding circuit 39, the control signal is supplied to the control circuit 41, and the transmission signal is transmitted to the higher-order combining station via the wired line transmission circuit 49. It

A signal from the combining station to the base station is received by the wired line receiving circuit 51, decomposed into a transmission signal and a control signal, the control signal is supplied to the control circuit 41, and the transmission signal is sent from the control circuit 41. With the control signal of
After being coded by, the modulation circuit 45 performs primary modulation and spread modulation using a spreading code, and then is transmitted from the antenna 31 to the mobile station via the transmission circuit 47 and the transmission / reception distribution circuit 33.

The control circuit 41 synchronizes with the receiving circuit 35 and the transmitting circuit 47 in order to perform the transmitting / receiving operation at the timing corresponding to the switching timing of the frequency and the switch by the frequency switching control circuit 23 in the mobile station shown in FIG. To control.

Next, with reference to FIG. 3, the different frequency soft handover processing of the present embodiment configured as described above will be described.

In the present embodiment, when the mobile station performs a soft handover in which the handover source base station moves to the handover destination base station, the handover destination base station uses the same frequency band as that used for the handover source radio channel. If the same frequency band is not available at the handover destination base station due to lack of radio capacity in the handover destination base station, etc., the frequency of the handover destination wireless line As a band, a frequency band different from the frequency band used for the handover source radio line is selected to perform the different frequency soft handover. In this case, the mobile station has one transmission / reception circuit 5 as shown in FIG. , 21 etc., the frequency of the handover source radio line Ndooba destination 2 of the frequency of the radio channel
It enables transmission and reception of one frequency.

Specifically, as shown by the solid line on the left side of FIG. 3, the mobile station communicates with the handover source base station using the frequency F1 in the handover source radio circuit frame, and in this case, the handover source radio channel. It is assumed that the portion used for information transmission in the line frame has the information only for half the time or less of the radio line frame, such as the part indicated by frequency F1.

In such a state, when the mobile station attempts a soft handover, the same frequency F1 as the frequency F1 used in the handover source radio channel for setting the radio channel with the handover destination base station is handed over to the handover destination. If an attempt is made to select for the wireless line, but the frequency F1 cannot be selected, and another different frequency F2 is selected as usable, the same diagram as that used by the handover source base station as the handover destination wireless line. 3 shows the selected frequency F as shown by the dotted line in the unused portion in the wireless circuit frame shown by the solid line.
2 is set to configure a handover destination radio link frame. That is, by switching the frequency between F1 and F2, the handover source radio channel frame and the handover destination radio channel frame are configured by one radio channel frame, whereby the mobile station can make both the handover source base station and the handover destination base station. On the other hand, by switching the frequencies F1 and F2, communication is simultaneously performed by one common wireless line frame.

Switching of the frequencies F1 and F2 for this purpose is achieved by the frequency switching control circuit 23 shown in FIG. 1 in the mobile station, and in the base station, the receiving circuit 35 and transmission by the control circuit 41. This is achieved by the timing switching control for the circuit 47.

As described above, the frequency F2 is selected for the handover destination radio channel, the frequency F2 is set to the unused portion of the handover source radio channel, and the handover source radio channel frame and the handover destination radio channel frame are set to 1 In the case where the mobile station is composed of one radio circuit frame, the mobile station controls the frequency F1 according to the timing of the frequencies F1 and F2 shown by the dotted lines in FIG. 3 to control the frequency F1 to the demodulation circuit 7 and the modulation circuit of the mobile station device. 19
To communicate with the handover source base station, while supplying the frequency F2 to the demodulation circuit 7 and the modulation circuit 19 to communicate with the handover destination base station, thereby communicating with the mobile station, the handover source base station and the handover destination base station. Soft handover can be implemented with the station. Further, in the handover source base station, the control circuit 41 controls the reception circuit 35 and the transmission circuit 47 at the timing of the frequency F1 shown by the dotted line in FIG. 3, and in the handover destination base station, the control circuit 41 controls the control circuit 41. At the timing of frequency F2 shown by the dotted line in FIG.
5 by controlling the transmission circuit 47 and the transmission circuit 47, it is possible to communicate with the mobile station and implement a soft handover.

With the above-described configuration, one radio unit does not have to separately provide a plurality of radio units that form a transmission / reception circuit such as an amplifier and a frequency filter of a mobile station device, but one radio unit can provide different frequencies. Although soft handover can be performed, the wireless unit is relatively large in terms of mounting space, is difficult to miniaturize, and consumes relatively large amount of power. Therefore, it is very preferable that the number can be reduced to one. Further, it is possible to use different spreading codes for the handover source base station and the handover destination base station. In that case, the modulation circuit 19 and the demodulation circuit 7 of the mobile station are used.
In, the spreading code may be switched in synchronization with the frequency switching.

As another embodiment of the present invention, in the above-mentioned embodiment, when a portion which is not used in the handover source radio line cannot realize a transmission rate necessary for communicating with the handover destination base station, for example, FIG. As shown in (a), a considerable part of more than half of the handover source radio channel frame is occupied by the information of the frequency F1,
When another frequency F2 of the handover destination radio line cannot be set in the remaining unused portion as shown by the dotted line in FIG. 3, the soft handover is started and the frequency shown in FIG.
As shown in (b), a new physical channel is set, the amount of transmission information is divided between the old and new physical channels, the frequency is switched at each divided time, and the same frequency is handled by both the old and new physical channels at the same time. It is intended to transmit the information of the frequency channel across both the old and new physical channels.

That is, the frequency F1 used in the handover source radio line frame is divided into half, and the frequency F1 shown in FIG.
As shown in (b), both the old and new physical channels are set in half, and the frequency F2 used in the handover destination radio channel is also divided in half, and the new and old physical channels are set in half to set each frequency. Information is transmitted across both old and new physical channels.

Even if the number of physical channels is increased by one in this way, since the same frequency is handled at the same time, one more baseband unit such as a demodulation unit for processing the increased physical channels is required. However, the number of wireless units can be one. In particular, the baseband unit can be integrated, and even if it is increased by one, the size and price do not increase so much. On the other hand, the radio unit requires an amplifier, a frequency filter, etc. In addition, since it is relatively large, it is difficult to miniaturize, and it consumes relatively large power, it is very preferable that it can be suppressed to one without increasing.

Further, as another embodiment of the present invention, in the first embodiment described above, a wireless line that can realize a communication speed that is a maximum number of times of the maximum soft handover of the required communication speed is provided between the mobile station and the base station. Set as a wireless line between. Then, as described above, when the different frequency soft handover is activated, another different frequency for each handover destination radio line is set in the unused portion of the radio line at the same time as the first embodiment. By configuring the handover destination wireless link frame within the same wireless link frame as the handover source wireless link frame, and switching each frequency corresponding to each wireless link frame, the mobile station can set each base of the handover source base station and the handover destination base station. It is possible to simultaneously communicate with a station by using one common wireless circuit frame.

With such a configuration as well, at the same time as the above-described embodiment, the number of the wireless unit can be one as it is, which is very preferable in terms of mounting space and power consumption.

Further, as another embodiment of the present invention, when the frequency band is switched to a frequency band usable by the handover destination base station and is used as the handover destination wireless line, the spreading code phase is continuous. This makes it unnecessary to establish spread code synchronization after frequency switching.

[0036]

As described above, according to the present invention,
Since the frequency band that can be used by the handover destination base station is switched to an unused portion in the handover source wireless link frame and used as the handover target wireless link, the wireless unit of the mobile station device should be increased according to each frequency. Instead, the different frequency soft handover can be performed with one radio unit, and downsizing and power saving can be achieved.

Further, according to the present invention, a new physical channel is set in addition to the current physical channel, the transmission information amount is divided by both physical channels, the frequency is switched at each divided time, and both physical channels are simultaneously changed. Since the same frequency is handled by the channels and the information of each frequency channel is transmitted across both physical channels, different frequency software remains as it is without increasing the radio section of the mobile station device according to each frequency. Handover can be performed, and downsizing and power saving can be achieved.

Further, according to the present invention, a wireless line capable of realizing a communication speed that is several times the maximum soft handover of the required communication speed is set, and the handover destination is set in the unused portion of the handover source wireless line frame. Since the frequency band that can be used by the base station is used as a handover destination radio line, the radio unit of the mobile station device does not increase in accordance with each frequency, and different frequency soft handover is performed with one radio unit. Therefore, it is possible to achieve downsizing and power saving.

Further, according to the present invention, the spreading code phase is continuous when switching to a frequency band that can be used by the handover destination base station and using it as a handover destination wireless line, so spreading code synchronization after frequency switching is performed. Establishing is not necessary and the process is simplified.

Further, according to the present invention, the mobile station device can handle the timing of the frequency band assigned to the wireless channel with the handover source base station and the timing of the frequency band assigned to the wireless channel with the handover destination base station. Since the frequency switching control is performed so that the modulation / demodulation processing and the spreading processing are performed at the corresponding frequencies respectively, the mobile station device does not increase the number of radio units according to each frequency, and the mobile station device does not increase the number of radio units as different frequency software. Handover can be performed, and downsizing and power saving can be achieved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a mobile station apparatus that implements a different frequency soft handover method in a CDMA mobile communication system according to an embodiment of the present invention.

FIG. 2 illustrates a different frequency soft handover method in a CDMA mobile communication system according to an exemplary embodiment of the present invention.
3 is a block diagram showing a configuration of a base station apparatus that is implemented together with the mobile station apparatus shown in FIG.

FIG. 3 is a diagram showing a configuration of a wireless line frame for explaining different frequency soft handover processing in the embodiments shown in FIGS.

FIG. 4 is a diagram showing a structure of a radio channel frame for explaining a different frequency soft handover method in a CDMA mobile communication system according to another embodiment of the present invention.

[Explanation of symbols]

3 Transmission / reception distribution circuit 5 Mobile station receiver circuit 7 Mobile station demodulation circuit 13 Mobile Station Decoding Circuit 15 Mobile station coding circuit 19 Mobile station modulation circuit 21 Mobile station transmitter circuit 23 Frequency switching control circuit for mobile stations 25 Mobile Station Oscillator 35 Base station receiver circuit 41 Base station control circuit 47 Base station transmitter circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04B ^7/ 24-7/26 102 H04Q ^7/ 00-7/38

Claims (6)

(57) [Claims] 1. A soft handover method in which a mobile station moves from a handover source base station to a handover destination base station in a code division multiple access mobile communication system, wherein the mobile station performs a first handover at all timings. Step A of communicating with the handover source base station in a first radio frame using the first frequency band, and if the handover destination base station cannot use the first frequency band, the mobile station and the handover A step B in which the destination base station selects a second frequency band that can be used in the handover destination base station; and the mobile station in the second radio frame when the second frequency band is not used for information transmission in the first radio frame. By communicating with the handover source base station and the handover destination base station in the second radio frame using the frequency band of Soft handover method characterized by the Dooba source base station and a step C of transition to the handover destination base station. 2. A soft handover method for moving a mobile station from a handover source base station to a handover destination base station in a code division multiple access mobile communication system, wherein the mobile station is on a first physical channel. And a step A of communicating with the handover source base station in a first radio frame which is set to all times and uses the first frequency band, and the handover destination base station uses the first frequency band. If impossible, the step B in which the mobile station and the handover destination base station select a second frequency band usable in the handover destination base station, and between the mobile station and the handover source base station. , Second
Step C of setting the physical channel of the second radio channel and setting the second radio frame on the second physical channel, and the mobile station transmits to both the first radio frame and the second radio frame. Process D for allocating information
And the mobile station uses the first frequency at the timing when the first radio frame and the second radio frame are used for information transmission, and the first frequency at the timing when the mobile station is not used for information transmission. Step E configured to use the frequency band of 2, and the mobile station in the first radio frame and the second radio frame configured in Step E, the handover source base station and the handover destination. A step F of transitioning from the handover source base station to the handover destination base station by communicating with the base station. 3. The soft handover method according to claim 1, wherein when the handover source base station is shifted to the handover destination base station, the spreading code phase is made continuous. 4. A mobile station that implements a soft handover in which a handover source base station moves to a handover destination base station in a code division multiple access mobile communication system, the handover source base station and the handover destination base station. In a radio frame for communicating with the handover source base station, in correspondence with the timing of the first frequency band used with the handover source base station and the timing of the second frequency band used with the handover destination base station. The mobile station is characterized by performing frequency switching control so as to perform modulation / demodulation processing and spreading processing in the first frequency band or the second frequency band, respectively. 5. In a mobile communication system of a code division multiple access system, a mobile station that realizes soft handover from a handover source base station to a handover destination base station, the handover source base station and the handover destination base station. And a first physical channel and a second physical channel are set between the first physical channel and the second physical channel, and a first radio frame and a second radio frame configured on the first physical channel and the second physical channel, respectively. And communicating with the handover source base station and the handover destination base station, and in each of the first radio frame and the second radio frame, a first radio frame used between the handover source base station and the handover source base station. Corresponds to the timing of the frequency band and the timing of the second frequency band used with the handover destination base station Te, the first frequency band or the second
A mobile station comprising control means for performing frequency switching control so as to perform modulation / demodulation processing and spreading processing in the respective frequency bands. From wherein said handover source base station at the time of transition to the handover destination base station, the mobile station according to claim 4 or 5, characterized in that the spreading code phase continuous.