JPH10210541A - Signal transmission method in cdma mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the signal transmission method in the CDMA mobile communication system in which production of a hearing aid is prevented by providing a spread rate smaller to each radio frame as a transmission information amount of temporary transmission information is smaller and sending continuously the frame with a smaller transmission power. SOLUTION: Once normal transmission information and transmission and temporary transmission information being components of transmission data have been given to a radio frame configuration section 3 and a transmission information amount detection section 1, the transmission information amount detection section 1 detects the information transmission amount of the temporary transmission information and gives the detection result to a control section 2. The control section 2 controls the radio frame configuration section 3, a spread section 5 and an amplifier section 6 so as to decrease a smaller bit number in a radio frame, to increase a higher spread rate and to apply a smaller amplification factor rate in a radio frame with respect to the information for a prescribed period as the information amount for a prescribed period is smaller based on the detection result of the information transmission amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a signal transmission method in a code division multiple access (hereinafter abbreviated as CDMA) system in mobile communication.

[0002]

2. Description of the Related Art In a CDMA system, transmission power must be reduced as much as possible in order to increase the number of users who can use the CDMA system. As a technology to suppress transmission power, VOX (voice Operated Trans
mission) Transmission control. By using this method, transmission power can be suppressed. However, even during silence, it is necessary to periodically transmit some information to maintain synchronization or control transmission power. Figure 1 shows a transmission example
0 is shown.

[0003] As shown in FIG. 10A, a transmission signal is constituted by repeating a radio frame composed of constantly transmitted information and occasionally transmitted information. The constant transmission information is information necessary for maintaining synchronization or controlling transmission power. The occasional transmission information is information in which the amount of transmission information such as voice information fluctuates with time. FIG. 10 shows a case where the transmission information is audio information at any time and there is audio information to be transmitted.
As shown in (b), it is always transmitted. When there is no voice information to be transmitted by the VOX transmission control, as shown in FIG. 10C, only the transmission information is constantly transmitted, and the transmission information is not transmitted at any time. In this case, periodic transmission of the transmission information results in periodic intermittent transmission.

[0004]

When periodic intermittent transmission is performed, a nearby audio device (for example, a telephone handset) is used.
In contrast, a phenomenon (hearing aid) in which abnormal noise is generated from a speaker due to electromagnetic induction may occur. In a time division multiple access (TDMA) system, which is used worldwide as a second generation mobile communication system, a hearing aid is generated because periodic intermittent transmission is performed, which is a problem. As mentioned earlier, CDMA
Even in the system, intermittent transmission is achieved by using VOX control. In addition to VOX control, even when the transmission information is control information at any time, intermittent transmission is performed when the transmission information is stopped as needed when there is no control information. Therefore, CD
Similarly, in the case of the MA system, there is a problem that a hearing aid may occur.

[0005] The present invention has been made in view of the above,
The purpose is to increase the spreading factor as the transmission information amount of the transmission information is reduced as needed for each radio frame, reduce the transmission power, and continuously transmit, thereby preventing the occurrence of hearing aid. It is to provide a signal transmission method in a mobile communication system.

[0006]

In order to achieve the above object, the present invention according to claim 1 repeatedly transmits a radio frame composed of constantly transmitted information and occasionally transmitted information whose transmitted information amount changes with time. In a signal transmission method in a CDMA mobile communication system, the gist is to increase the spreading factor and reduce the transmission power as the amount of transmission information of the transmission information decreases as needed in each radio frame.

According to the first aspect of the present invention, the smaller the transmission information amount of the transmission information at any time for each radio frame, the larger the spreading factor and the lower the transmission power. By transmitting continuously even if the number decreases, it is possible to prevent the occurrence of a hearing aid as in the related art.

The present invention according to claim 2 repeatedly transmits a radio frame composed of transmission information and random transmission information in which the transmission information amount changes with time, and the transmission signal includes an in-phase component and a quadrature component. In the signal transmission method in the CDMA mobile communication system, the spreading factor is increased as the transmission information amount of the transmission information is reduced as needed in each radio frame in at least one of the in-phase component and the quadrature component. The gist is to reduce the transmission power.

According to the second aspect of the present invention, at least one of the in-phase component and the quadrature component, the spreading factor increases as the amount of transmission information of the transmission information decreases as needed for each radio frame, and the transmission power of the component increases. In order to reduce the transmission information, the transmission information is transmitted continuously even if the amount of transmission information is reduced as needed, thereby making it possible to prevent the occurrence of a hearing aid as in the related art.

Further, the present invention according to claim 3 provides the present invention as claimed in claim 2.
In the described invention, the gist is that the transmission information is always transmitted using a component that increases the spreading factor and reduces the transmission power as the transmission information amount of the transmission information decreases as needed in each radio frame.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the constant transmission information includes a pilot symbol for synchronous detection and / or a transmission power control bit. I do.

Further, the present invention described in claim 5 is based on claim 1.
In the invention described in (2), the point-to-time transmission information includes control information and / or user information.

[0013] Further, the present invention according to claim 6 is based on claim 2.
In the invention described above, the point is that the occasional transmission information includes user information and control information, and the user information and control information are transmitted with different components.

According to a seventh aspect of the present invention, in the second aspect of the invention, the occasional transmission information includes user information and control information, and the control information is transmitted in one of an in-phase component and a quadrature component. The gist is that information is transmitted across both components.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are block diagrams showing a basic configuration of a transmitting unit and a receiving unit for implementing a signal transmission method in a CDMA mobile communication system according to one embodiment of the present invention.

First, the configuration of the transmitting section shown in FIG. 1 will be described. In the transmission unit shown in FIG. 1, the transmission data is constituted by the constantly transmitted information and the occasionally transmitted information and inputted, the constantly transmitted information is supplied to the radio frame construction unit 3, and the occasionally transmitted information is supplied to the transmission information amount detection unit 1. Is done. Transmission information amount detection unit 1
Detects the information transmission amount of the transmission information at any time, and supplies the detection result to the control unit 2.

Based on the detection result of the information transmission amount of the transmission information as needed, the control unit 2 reduces the number of bits in the radio frame for the information in the predetermined period and increases the spreading factor as the information amount in the predetermined period decreases. Calculate the number of bits in the radio frame, the spreading factor, and the amplification factor so as to reduce the amplification amount,
These pieces of information are supplied to the radio frame forming unit 3, the spreading unit 5, and the amplifying unit 6, respectively, and control the number of bits, the spreading factor, and the gain, respectively.

The radio frame forming unit 3 includes a control unit 2
The wireless frame is configured based on the number of bits in the wireless frame specified by. The data of the radio frame thus configured is primary-modulated in the modulator 4 and then spread-modulated in the spreader 5. In this case, the spread-modulation in the spreader 5 is performed by the control unit every predetermined period. This is performed at the spreading factor specified in 2. Thus, the signal spread-modulated by the spreading unit 5 is amplified by the amplification unit 6 at the amplification factor specified by the control unit 2 and transmitted from the transmission antenna 7. Note that the spreading factor is the ratio of the spreading chip rate to the information bit rate as described in FIG.

Next, the configuration of the receiving section shown in FIG. 2 will be described. In the receiving section shown in FIG. 2, the signal received by the receiving antenna 8 is subjected to despreading by a plurality of despreading sections 9, and the despread signals are sent to a plurality of level measuring sections 10 and selecting sections 12. Supplied. The plurality of level measurement units 10 measure each signal level, and the measurement results are supplied to the level comparison unit 11. The level comparison unit 11 compares the measurement results of the level measurement units 10 and instructs the selection unit 12 to select the signal having the highest signal level. The selecting unit 12 selects the specified signal from a plurality of despread signals and supplies the selected signal to the demodulation unit 13, assuming that the specified signal is a signal spread with a correct spreading factor. The demodulation unit 13 performs data demodulation for primary modulation.

In the above embodiment, a plurality of spreading factors specified by the control unit 2 in FIG. 1 are determined in advance, for example, 64, 128, 256, and a spreading factor suitable for the information transmission amount is determined. You may select and send. In this case, FIG.
In the receiving unit shown in (1), the same number of despreading units 9 and level measuring units 10 as the number of spreading factors may be prepared. For example, when three spreading factors are prepared, three despreading units 9 and three level measuring units 10 may be provided.

In the receiving section shown in FIG. 2, a plurality of despreading sections 9 and level measuring sections 10 are used. Despreading unit 9 and level measuring unit 1
A method of processing 0 in a time-sharing manner can be similarly performed.

FIG. 3 shows a radio frame configuration output from the radio frame configuration unit 3 in the transmission unit of FIG.
And the transmission power after being amplified by the amplification unit 6.

In FIG. 3, section (a) is a case where a radio frame is composed of A bits by combining transmission information and transmission information at all times, and section (b) is a section where the information amount of transmission information is section at any time. (A) less than
The case where the radio frame is composed of B bits (B <A) is shown. In either case, the speed of the spreading code used in the spreading unit 5 is the same as shown in FIG.

As shown in the section (a), when one radio frame is composed of A bits, the control unit 2 spreads one bit to the spreading unit 5 at the spreading factor of the spreading code X chip.
The amplifier 6 is caused to transmit at the transmission power P as shown in FIG. If the information amount of the transmission information changes at any time and one radio frame is composed of B bits as shown in the section (b), the control unit 2 does not change the spread signal speed to the spread unit 5;
One bit is spread at the spreading factor of the XA / B chip, and the amplifier 6 transmits the bit at the transmission power PB / A.

In the above description, one radio frame is B
The reason why the transmission power can be set to P · B / A in the case of using bits is described below. The reception quality on the receiving side is determined by the transmission power and spreading factor on the transmitting side. The spreading factor is also called a spreading gain, and the larger the value is, the better the reception quality is. When one radio frame is composed of A bits and one bit is spread by X chips, the spreading factor, that is, the spreading gain is X. When the amount of transmission information decreases as needed, one radio frame is composed of B bits, and when one bit is spread by an XA / B chip, the spreading gain is XA / B. Therefore, when one radio frame is composed of B bits, the spreading gain can be made A / B times, and the reception quality is also made A / B times as compared with the case where one radio frame is composed of A bits. be able to. The reception quality improvement by this spreading gain
A margin is given to the required reception quality. This margin can be allocated to the reduction of the transmission power. That is, the transmission power when one radio frame is composed of B bits can be reduced to B / A times as compared with the case where one radio frame is composed of A bits. Even if the transmission power is reduced, the reception quality does not change due to the improvement in the spreading gain.

As described above, continuous transmission can be performed even when the transmission information amount of the transmission information decreases as shown in the section (b), so that the occurrence of hearing aid can be prevented.

FIGS. 4 and 5 are block diagrams showing a basic configuration of a transmission unit and a reception unit for implementing a signal transmission method according to another embodiment of the present invention.

First, the configuration of the transmitting section shown in FIG. 4 will be described. In the transmitting unit shown in FIG. 4, similarly to the transmitting unit shown in FIG. 1, the transmission data is constituted by the constantly transmitted information and the occasionally transmitted information and inputted, and the constantly transmitted information is transmitted by the radio frame composing unit 1.
6 and the transmission information is supplied to the transmission information amount detector 14 as needed. The transmission information amount detection unit 14 detects the information transmission amount of the transmission information at any time, and supplies the detection result to the control unit 15.

Based on the detection result, the control unit 15 reduces the number of bits in the radio frame for the information in the predetermined period, increases the spreading factor, and reduces the amplification amount as the information amount in the predetermined period decreases. The number of bits in the radio frame,
A spreading factor and an amplification factor are calculated, and these information are transmitted to the radio frame forming unit 16, the spreading units 21 and 23, and the amplifying unit 2.
2 and 24 to control the number of bits, the spreading factor and the amplification factor, respectively.

The radio frame forming section 16 forms the in-phase component radio frame and the quadrature component radio frame based on the number of bits in the radio frame specified by the control section 15. The modulators 17 and 20 perform primary modulation on the in-phase component radio frame and the quadrature component radio frame. The carrier oscillating section 18 generates a carrier required for modulation, supplies the carrier to the modulator 17 as a carrier for the in-phase component, and passes the carrier for the in-phase component through a phase converter 19 to change the phase by π / 2, thereby making the carrier orthogonal. It is supplied to the modulator 20 as a component carrier.

After being modulated into in-phase components and quadrature components by modulators 17 and 20, respectively, spread modulation is performed by spreaders 21 and 23, respectively. The spreading factor in this case is a value specified by the control unit 15 for each predetermined period as described above.
The components spread and modulated by the spreading units 21 and 23 are amplified by the amplifiers 22 and 24 at the amplification factors specified by the control unit 15, and the combining unit 25 combines the in-phase component and the quadrature component. Sent.

The spreading factors of the spreading units 21 and 23 and the amplifying factors of the amplifying units 22 and 24 are not necessarily the same, and a value suitable for each radio frame configuration can be used.

Next, the configuration of the receiving section shown in FIG. 5 will be described. In the receiving section shown in FIG. 5, the signal received by the receiving antenna 27 is divided into two components, and despread by a plurality of despreading sections 28 and 32 for each component. In the despreading units 28 and 32, despreading is performed using the spreading codes used in the spreading units 21 and 23 of the transmitting unit, respectively.
The despread signals are supplied to a plurality of level measuring units 29 and 33 and selecting units 31 and 35. The plurality of level measuring units 29 and 33 measure the signal level of each component, and supply the measurement results to the level comparing units 30 and 34. Each of the level comparison units 30 and 34 compares the measurement levels supplied from the plurality of level measurement units 29 and 33, and designates each of the selection units 31 and 35 to select the signal having the largest signal level. Each of the selectors 31 and 35 selects each signal designated by the level comparators 30 and 34, and demodulates each of the selected signals into demodulators 36 and 37, respectively.
, Thereby generating an in-phase component radio frame and a quadrature component radio frame.

Also in this embodiment, similarly to the embodiments of FIGS. 1 and 2, a plurality of spreading factors specified by the control unit 15 are determined in advance, and a spreading factor suitable for the information transmission amount is determined. You may select and send. Also, in the receiving section of the present embodiment, a plurality of despreading sections 28 and 32 and a plurality of level measuring sections 29 and 33 are used. The units may be processed in a time sharing manner.

The radio frame constituted by the radio frame forming unit 16 includes a case where the in-phase component and the quadrature component always include the transmission information, and a case where only one of the components includes the constant transmission information.

When the transmission information is always included in both components,
3 is divided into two every two bits,
Since the S / P conversion is performed for one bit string, both components have the same configuration as that of FIG. The control method of the control unit 15 for the diffusion units 21 and 23 and the amplification units 22 and 24 is the same as described above.

A description will be given of a method of controlling the spreading units 21 and 23 and the amplifying units 22 and 24 by the control unit 15 when the transmission information is always included in only one component.

A component which always includes transmission information is an in-phase component,
When the components that are not included are quadrature components, the in-phase component radio frame configuration output from the radio frame configuration unit 16, the spreading code in the spreading unit 21, and the transmission power after amplification in the amplification unit 22 are the same as those in FIG. 3. . Also, the radio frame forming unit 16
FIG. 6 shows the configuration of the orthogonal component radio frame after output, the spreading code in spreading section 23, and the transmission power after amplification in amplification section 24.
Shown in The control method is the same as that in FIG. 3 except that there is no transmission information at all times.

The control method of the control unit 15 for each of the in-phase component and the quadrature component is basically the same as described above. However, since the quadrature component is only the transmission information at any time, the bit sequence of the transmission information at any time has a predetermined period. If none of them are within
F is controlled.

As shown in FIG. 7, a fixed spreading factor can be used for the orthogonal component that is only transmission information at any time without changing the spreading factor. In this case, even if the number of bits in the predetermined period decreases as in section (b) of FIG.
Since the number of chips of the spreading code for spreading the bits does not change, the transmission power is the same as that in the section (a) of FIG.
Although the quadrature component does not result in continuous transmission, the in-phase component is transmitted continuously, so that the effect of hearing aid can be reduced. Further, the same operation can be performed in a configuration in which the component including the transmission information is always the quadrature component and the component not including the transmission information is the in-phase component.

As occasional transmission information, user information and control information can be considered. There are three types of radio frame configuration after output from the radio frame configuration unit 3 in FIG. 1 and three types in the radio frame configuration unit 16 in FIG. As the types of the radio frame configuration after output, there are four types shown in FIG. That is, when the in-phase component and the quadrature component always include transmission information, as shown in FIG. 8, (a-1) the random transmission information includes only the user information. (A-2) The random transmission information includes the user information. Includes both control information. (A-3) As occasion demands transmission information includes only control information. In addition, when the constantly transmitted information includes only one component, as shown in FIG. 9, (b-1) the component including the constantly transmitted information includes only the user information,
The component not containing contains only control information. (B-2) The component containing always transmitted information contains only user information.
A component not containing includes both user information and control information. (B-3) A component containing constantly transmitted information contains only control information, and a component not containing contains only control information. (B-4) A component containing always transmitted information contains only user information. ,
There are four types of components that do not include, but also include only user information.

In particular, in the above-mentioned a-1, a-3, and b-1, there is an advantage that the determination of the spreading factor and the transmission power for each component can be determined by either the user information or the control information transmission information amount. . In the above b-2, since the maximum transmission information amount is generally different between the user information and the control information and the control information amount is smaller, at least the control information is transmitted by either the in-phase component or the quadrature component. . Thus, there is an advantage that there is no control information and the spreading factor of the component containing the user information can be determined only by the information amount of the user information.

Also, the constantly transmitted information may include a pilot symbol for synchronous detection, a unique word for synchronous detection, and a transmission power control bit. Pilot symbols for synchronous detection are described in detail in Japanese Patent Application No. 6-140569. The unique word for maintaining synchronization is used in a digital car telephone system (PDC: Personal Digital Cellular) currently being implemented in Japan and is an existing technology. The transmission power control bit is described in detail in US Pat. No. 5,056,109.

[0045]

As described above, according to the present invention,
Since the spreading factor is increased and the transmission power is reduced as the transmission information amount of the transmission information is reduced as needed in each radio frame, even if the transmission information amount of the transmission information is reduced as needed, continuous transmission is performed. It is possible to prevent the occurrence of a hearing aid which is a problem when performing intermittent transmission.

According to the present invention, in at least one of the in-phase component and the quadrature component, the spreading factor is increased as the transmission information amount of the transmission information is reduced for each radio frame.
Since the transmission power of the component is reduced, continuous transmission is performed even if the transmission information amount of the transmission information is reduced as needed, thereby preventing the occurrence of a hearing aid which is a problem when performing periodic intermittent transmission. Can be.

Further, according to the present invention, by continuously changing the spreading factor of the component including the transmission information and performing continuous transmission,
The effect of hearing aid can be reduced even when the component of only the transmission information is not continuously transmitted at any time.

According to the present invention, the spreading factor and the transmission power for each component can be determined based on the amount of transmission information of either user information or control information.

According to the present invention, since the maximum amount of transmission information is generally different between the user information and the control information and the amount of control information is smaller, at least the control information is transmitted by either the in-phase component or the quadrature component. By doing so, there is no control information, and the spreading factor of the component containing the user information can be determined only by the information amount of the user information.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a basic configuration of a transmission unit that performs a signal transmission method in a CDMA mobile communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a basic configuration of a receiving unit used together with the transmitting unit of FIG. 1 and performing a signal transmission method according to an embodiment of the present invention.

3 is a diagram showing a radio frame configuration output from a radio frame configuration unit in a transmission unit in FIG. 1, a spreading code in a spreading unit, and transmission power after being amplified by an amplification unit.

FIG. 4 is a block diagram illustrating a basic configuration of a transmission unit that performs a signal transmission method according to another embodiment of the present invention.

FIG. 5 is a block diagram illustrating a basic configuration of a receiving unit used together with the transmitting unit of FIG. 4 and performing a signal transmission method according to another embodiment of the present invention.

6 is a diagram illustrating a radio frame configuration output from a radio frame configuration unit in a transmission unit in FIG. 4, a spreading code in a spreading unit, and transmission power after being amplified by an amplification unit.

FIG. 7 shows the radio frame configuration output from the radio frame configuration unit in the transmission unit of FIG. 4 in the case where the spreading factor of the orthogonal component of only the transmission information is not changed at any time, after being amplified by the spreading code in the spreading unit and the amplification unit FIG. 3 is a diagram illustrating transmission power of the multiplexed signal;

FIG. 8 is a diagram illustrating a radio frame configuration in a case where transmission information is always included in both the in-phase component and the quadrature component.

FIG. 9 is a diagram illustrating a wireless frame configuration in a case where transmission information is always included in only one component.

FIG. 10 is a diagram showing a radio frame configuration and transmission power (TX POWER) showing a conventional signal transmission method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission information amount detection part 2 Control part 3 Radio frame formation part 5 Spreading part 6 Amplification part 9 Despreading part 10 Level measurement part 11 Level comparison part 12 Selection part 13 Demodulation part

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Seigura Onoe 2-10-1, Toranomon, Minato-ku, Tokyo Inside NTT Mobile Communication Network Co., Ltd.

Claims (7)

[Claims] 1. A signal transmission method in a CDMA mobile communication system for repeatedly transmitting a radio frame composed of constant transmission information and random transmission information whose transmission information amount changes with time, the transmission information of the random transmission information for each radio frame. A signal transmission method in a CDMA mobile communication system, characterized in that as the amount is smaller, the spreading factor is increased and the transmission power is reduced. 2. A CDMA mobile communication system in which a radio frame composed of constantly transmitted information and random transmission information whose transmission information amount changes with time is repeatedly transmitted, and a transmission signal is modulated by being divided into an in-phase component and a quadrature component. In the signal transmission method in the system, in at least one of the in-phase component or the quadrature component, the smaller the transmission information amount of the transmission information for each radio frame, the larger the spreading factor,
CDM characterized by reducing the transmission power of said component
A A signal transmission method in a mobile communication system. 3. The transmission information is always transmitted using a component that increases the spreading factor and reduces the transmission power as the transmission information amount of the transmission information decreases as needed in each radio frame. A signal transmission method in the CDMA mobile communication system according to claim 1. 4. The signal transmission method in a CDMA mobile communication system according to claim 1, wherein the constantly transmitted information includes a pilot symbol for synchronous detection and / or a transmission power control bit. 5. The signal transmission method in a CDMA mobile communication system according to claim 1, wherein the random transmission information includes control information and / or user information. 6. The signal transmission method in a CDMA mobile communication system according to claim 2, wherein the occasional transmission information includes user information and control information, and transmits the user information and control information with different components. 7. The random transmission information includes user information and control information, wherein the control information is transmitted as one of an in-phase component and a quadrature component, and the user information is transmitted across both components. A signal transmission method in the CDMA mobile communication system according to claim 2.