JP2001358614A - Cdma signal receiver and telephone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently detect reception power in a CDMA(code division multiple access) signal receiver. SOLUTION: CDMA signals are respectively received by antennas 1 and 2, and gain is regulated by AGC circuits 14 and 16. The received CDMA signals are respectively inversely diffused by a plurality of fingers 18, the signal of the antenna 1 is RAKE synthesized by a RAKE synthesizer 30, and the signal of the antenna 2 is RAKE synthesized by a RAKE synthesizer 32. The output destination of an inverse diffusion signal is switched by a changeover switch 19 according to a command from a controller 28. The synthesizers 30 and 32 detect received powers from the synthesized signals. Since the received power is detected, not by respective fingers but by the synthesizers after the synthesis, circuit configuration can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CDMA signal receiving apparatus and a telephone, and more particularly to a CDMA signal receiving power detection.

[0002]

2. Description of the Related Art Methods of transmitting a plurality of channel data include FDMA (frequency multiplexing), TDMA (time division multiplexing), CDMA (code division multiplexing), and the like. Of these, CDMA performs the orthogonal transform using orthogonal codes spread in the same time-frequency space to perform the division of each channel, and can easily change the data rate and weight for each channel. It is used for mobile phones and the like.

[0003] In the CDMA system, reception is generally performed by RA.
This is performed by KE reception. RAKE reception is a reception method unique to a spread spectrum communication system, and is a method of processing a direct wave from which a transmission wave from a transmission side directly reaches a reception side and a reflected wave which is reflected by a building or the like and reaches a reception side. . Since there can be many paths of reflected waves, multipath reflected waves are received, and these received signals have respective delay times due to the paths. In a received signal that has been spread by a PN code, if it is shifted in time, it will not be possible to make a correlation. Therefore, a plurality of despreading units on the receiving side are provided for each path, and despreading can be performed by giving a phase offset corresponding to the delay time in each path and performing despreading. A demodulated signal can be obtained.

FIG. 3 shows a schematic configuration of a conventional CDMA signal receiving apparatus. In the drawing, it is assumed that the CDMA signal is received by a plurality of antennas, and that the higher strength of the CDMA signals is adopted, or that the two are combined and output, and diversity reception is performed.

In FIG. 1, two antennas 1 and 2 for diversity reception are provided, and C antennas received by each antenna are provided.
The DMA signals are output to AGC circuits 14 and 16, respectively. The AGC circuits 14 and 16 adjust the gain of the received CDMA signal by an amount necessary for the subsequent processing, thereby increasing the signal strength. Generally, since the reception strengths of the two antennas 1 and 2 are different, the gain adjustment rate (referred to as α) in the AGC circuit 14 and the gain adjustment rate (referred to as β) in the AGC circuit 16 are different. Gain-adjusted CDMA
The signal is provided to a plurality of fingers 18.

[0006] The plurality of fingers 18 are used for the CDMA of each path.
This is for despreading a signal, and is usually provided in plural (for example, about 20). These fingers
ger-1, Finger-2, ..., Finger
-N. Finger-1 has an input section for inputting a CDMA signal from antenna 1 or 2;
A multiplication unit for multiplying and despreading by an N code and a power detection unit for detecting the reception power of the CDMA signal are provided. Other Fing
er has the same configuration. The CDMA signal despread by each Finger is output to the RAKE combiner 20 and subjected to maximum ratio combining. The demodulated signal obtained by the synthesis is output to the upper processing layer.

The path search section 22 detects the position of each component including the delayed wave and outputs the detected position to the control section 28. The control unit 28
A timing signal is output to each Finger to select a communication base station with which the mobile phone communicates. Path search unit 2
2 acquires the new cell information of the transfer destination. The delay profile unit 26 acquires the current follow-up of the reception path position.
In each Finger, receive CD of either antenna 1 or 2
The control unit 28 determines whether to despread the MA signal.

The received power detected by each finger is added, for example, by the control unit 28 and transmitted to the communication base station as the total received power. As a result, the communication base station can know the reception power on the receiving device side, and can dynamically increase or decrease the transmission power to secure communication quality.

[0009]

SUMMARY OF THE INVENTION As described above, CDMA
In communication, communication quality can be improved by detecting reception power on the reception side and feeding it back to the transmission side, and controlling transmission power on the transmission side.However, in a configuration in which the reception power is detected for each finger, In addition, it is necessary to provide a power detection circuit (including a multiplier) for each finger, and there is a problem that the configuration is redundant and complicated, and the cost is increased.

In general, the number of fingers is often provided in excess of the number of paths to be considered (this is one in consideration of the standby or simultaneous reception of a plurality of channels). In this case, the power detection circuit is not used. Therefore, there is a problem that the circuit configuration is wasted.

Further, since each finger is connected to two antennas, and which signal is assigned to the finger changes from time to time, a power detection circuit provided for each finger requires a corresponding antenna. AGC circuit 1
It is necessary to consider the gain adjustment ratios of 4 and 16 each time, and the configuration of the power detection circuit itself is complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to provide an apparatus that can easily and efficiently detect the reception power of a received CDMA signal. is there.

[0013]

To achieve the above object, the present invention provides a CDMA signal receiving apparatus for demodulating a CDMA signal received by an antenna, comprising: The CDM
It is characterized by having detecting means for detecting the reception power of the A signal. Rather than detecting the received power in the despreading process by the despreading means (fingers), the received power is detected based on the synthesized signal after RAKE synthesis, so that only the number of despreading means (fingers) is detected. A power detection circuit is not required, and the detection can be efficiently performed by detecting the reception power collectively after the combination. Note that the reception power is power before the gain is adjusted when the gain of the CDMA signal received by the antenna is adjusted.

The present invention also relates to a CD received by an antenna.
A CDMA signal receiving apparatus for demodulating an MA signal, comprising: gain adjusting means for adjusting a gain of a CDMA signal received by the antenna; and a plurality of despreading means for despreading the CDMA signal gain-adjusted by the gain adjusting means. Synthesizing means for RAKE-combining the CDMA signals despread by the plurality of despreading means, and detecting means for detecting the reception power of the CDMA signal synthesized by the synthesizing means according to the gain of the gain adjusting means. It is characterized by having. Rather than detecting the received power in the despreading process by the despreading means (fingers), the received power is detected based on the synthesized signal after RAKE synthesis, so that only the number of despreading means (fingers) is detected. The power detection circuit becomes unnecessary. When the gain of the CDMA signal received by the antenna is adjusted, the received power is power before the gain is adjusted. ) Is detected.

In one embodiment of the present invention, a plurality of the antennas are provided to perform diversity reception. In this case, the gain adjusting means exists for each of the plurality of antennas, the combining means performs RAKE combining for each of the plurality of antennas, and the detecting means detects received power for each of the plurality of antennas. By performing RAKE combining for each antenna,
The gain adjustment rate (determined for each antenna) of the combined CDMA signal can be collectively processed, and the detection unit can easily detect the received power. That is, conventionally, in each despreading means (each finger), signals from a plurality of antennas are mixed and processed.
If the received power cannot be detected after the combination (the signals from a plurality of antennas are mixed, the gain adjustment rate is also mixed, and the correction by the gain adjustment rate becomes impossible),
Although it is necessary to calculate the power in each despreading unit (finger) before combining, according to the present invention, since RAKE combining is performed for each antenna, that is, for each gain adjustment, it is possible to detect received power after combining.

Here, C despread by the despreading means is used.
The image processing apparatus may further include a switching unit that switches a DMA signal for each of the plurality of antennas and outputs the DMA signal to the combining unit. Thus, the switching means, which can surely perform RAKE combining for each antenna, may be added as a function of the despreading unit.

The present invention also provides a plurality of antennas, a gain control means connected to each of the plurality of antennas for adjusting the intensity of a CDMA signal received by the antennas, and a plurality of antennas connected to the gain adjustment means. A plurality of fingers for despreading the CDMA signal received by the antenna and switching the despread CDMA signal for each of the plurality of antennas and a CDMA signal output from the switching means for each of the plurality of antennas. A plurality of combining means for combining and detecting received power for each of the plurality of antennas using a gain adjustment rate in the gain adjusting means, and a re-synthesizing means for re-synthesizing a combined signal from the plurality of combining means. It is characterized by having.

The CDMA signal receiving apparatus of the present invention can be mounted on a telephone such as a portable telephone.

[0019]

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

FIG. 1 shows a configuration of a CDMA signal receiving apparatus according to the present embodiment. This CDMA signal receiving device can be integrated into an IC and mounted on a mobile phone.
In the figure, two antennas 1 and 2 are provided, and CDMA signals received from antennas 1 and 2 are transmitted to AGC circuits 14 and 1.
6 is output. The AGC circuits 14 and 16 adjust the gain to the intensity required for the subsequent processing. The gain adjustment rates are α and β, respectively. Different reception locations have different reception intensities, so α and β usually take different values.

The received CDMA signal whose gain has been adjusted by the AGC circuits 14 and 16 is output to a plurality of fingers 18, respectively. Finger 18 is a Finger-1, Fin
ger-2, ..., Finger-N,
For example, it can be 30 pieces. Each finger 18
An antenna to be subjected to signal processing is determined based on signals from the control unit 28 and a path search unit 22 (not shown), respectively.
Despread by multiplying by a PN code.

On the other hand, each finger 18 in the present embodiment
Does not have a power detection circuit, unlike the fingers 18 shown in FIG. This is because in this embodiment each finger 1
In FIG. 8, since the received power is not detected but detected after RAKE combining, the power detection circuits as many as the number of fingers 18 are unnecessary in the present embodiment.

Also, each finger 18 in the present embodiment is
Has a changeover switch 19 for switching the output destination of the despread CDMA signal, unlike FIG. The contact of the changeover switch 19 is connected to each of the two RAKE combiners 30 and 32, and the changeover of the changeover switch 19 is controlled by a signal from the control unit 28.

The two RAKE combiners 30 and 32 are combiners for antenna 1 and antenna 2, respectively.
The synthesizer 30 includes the antenna 1 among the plurality of fingers 18.
Are supplied from the fingers obtained by despreading the CDMA signal received by the CDMA signal, and the RAKE combiner 32 is supplied with a signal obtained by despreading the CDMA signal received by the antenna 2 from the plurality of fingers 18. For example, among fingers 18, Finger-1, 3, 5 have antenna 1 at a certain time.
Are despread, and if Finger-2, 4, and 6 despread the signal of antenna 2, Finger-1,
The contacts of the changeover switches 19 of 3, 5 are the RAKE combiners 30
The signal which has been switched and despread is switched to the RAKE combiner 3
0 and the contacts of the changeover switches 19 of Finger-2, 4, and 6 are switched to the RAKE combiner 32 side to supply the despread signal to the RAKE combiner 32. That is, RAKE combiner 30 always receives C
Only the DMA signals are combined, and the RAKE combiner 32 always combines only the CDMA signals received by the antenna 2.

RAKE combiners 30 and 32 combine the despread signals from the fingers by, for example, maximum ratio combining (squaring and adding the signals from each finger), and then detect the received power of the combined signal. . Here, since the RAKE combiner 30 combines the signals received by the antenna 1, the gain adjustment rate is uniform with α, so that the received power (ie, the power before the gain is adjusted by α) can be easily adjusted. ) Can be detected. Also, since the RAKE combiner 32 combines the signals received by the antenna 2, the gain adjustment rate is uniform with β, so that the received power can be easily detected. The received power detected by the RAKE combiners 30 and 32 is output to the control unit 28, and the control unit 28 adds these powers to calculate the total received power of the antennas 1 and 2. The calculated received power is transmitted to the communication base station as appropriate.

The CDMA signals combined by the RAKE combiners 30 and 32 are added and recombined by the RAKE recombiner 34, and output to the upper processing layer as a demodulated signal. Note that the functions of the path search unit 22 and the delay profile unit 26 are the same as those of the related art, and thus description thereof is omitted.

FIG. 2 shows the changeover switch 19 shown in FIG.
Is shown. As described above, the changeover switch 19 is provided for each finger, and has a contact for the RAKE combiner 30 and a contact for the RAKE combiner 32, respectively. Contact switching of the changeover switch 19 is performed by a signal from the control unit 28. The control unit 28, as described above,
Each finger determines which of the received signals of the antennas 1 and 2 is to be selected, and instructs each finger. A signal having the same content as the instruction is also supplied to the changeover switch 19.
Therefore, when a finger Finger-i processes a received signal of the antenna 1 at a certain processing timing, the contact of the changeover switch 19 is simultaneously switched to the RAKE combiner 30 side. Similarly, when processing the reception signal of the antenna 2, the contact of the changeover switch 19 is set to R
It is switched to the AKE combiner 32 side. Preferably, the RAKE combiners 30 and 32 each have as many input ports as fingers 18. This is because all fingers 18 may process the received signal of antenna 1 (or antenna 2) at a certain processing timing.

As described above, in the present embodiment, the received power is not detected at each finger of the plurality of fingers, but RAKE combining is performed for each antenna, and after RAKE combining, the received power is uniformly determined based on the gain adjustment rate of each antenna. Since the received power is detected at the same time, it is possible to reduce the power detection circuit, which is conventionally required for the number of fingers, to only the number of antennas. Specifically, assuming that the number of fingers 18 is 30, the number of reception power detection circuits conventionally required 30 is reduced to two. Also, the RAKE combiner 3
The power detection circuit within 0 does not need to consider both the gain adjustment rates α and β of the AGC circuit in order to cope with the reception signals of both the antennas 1 and 2, unlike the conventional power detection circuit.
Since only the gain adjustment rate α of the AGC circuit 14 needs to be considered, the configuration is also simplified. The same applies to the power detection circuit in the RAKE combiner 32. In this embodiment, the changeover switch 19 is provided for each finger. However, the configuration is extremely simple as compared with a conventional power detection circuit including a multiplier.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made. For example, in the present embodiment, the case where two antennas 1 and 2 are provided has been described, but the present invention can be similarly applied to a case where three or more antennas are used. If there are three antennas, R
What is necessary is just to provide three AKE combiners and to detect the received power in each. Furthermore, even with one antenna,
The present invention is applicable. In this case, the changeover switch 19
Is unnecessary, and instead of detecting the received power at each finger, the signals are combined by a single RAKE combiner and then a single A
What is necessary is just to detect the received power according to the gain adjustment rate in the GC circuit.

In the present embodiment, the plurality of fingers 1
Although the changeover switch 19 is provided on each finger of No. 8, the changeover switch 19 can be integrated with each finger to form a finger having a changeover function. Whether each finger processes one of the signals of the antennas 1 and 2 is determined by a command from the control unit 28, and thus the output switching function is incorporated in the finger, so that the configuration can be further simplified.

In this embodiment, the RAKE combiner 3
Although the received power is detected after the despread signals are combined for each of the antennas 1 and 2 at 0 and 32, a power detector is provided at each subsequent stage separately from the RAKE combiners 30 and 32, and It is also possible to detect the received power.

[0032]

According to the present invention, the received power can be efficiently detected with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a configuration diagram of a changeover switch in FIG. 1;

FIG. 3 is a configuration diagram of a conventional device.

[Explanation of symbols]

1 antenna, 2 antennas, 14 AGC (auto gain control), 16 AGC (auto gain control), 18 fingers, 30 RAKE combiner (for antenna 1), 32 RAKE combiner (antenna 2
), 34 RAKE resynthesizer.

Claims (6)

[Claims] 1. A CDMA signal receiving apparatus for demodulating a CDMA signal received by an antenna, comprising: detecting means for detecting the received power of the CDMA signal after RAKE combining the CDMA signal received by the antenna. CDMA signal receiving apparatus. 2. A CDMA signal receiving apparatus for demodulating a CDMA signal received by an antenna, wherein the gain adjusting means adjusts the gain of the CDMA signal received by the antenna; and the CDMA signal gain-adjusted by the gain adjusting means. A plurality of despreading means for despreading, a combining means for RAKE combining the CDMA signals despread by the plurality of despreading means, and a CDMA signal combined by the combining means according to the gain of the gain adjusting means. And a detecting means for detecting the received power of the CDMA signal. 3. The apparatus according to claim 2, wherein the plurality of antennas are provided for performing diversity reception, the gain adjusting means is provided for each of the plurality of antennas, and the combining means is provided for each of the plurality of antennas. A CDMA signal receiving apparatus, wherein the detecting means detects received power for each of the plurality of antennas. 4. The apparatus according to claim 3, further comprising: switching means for switching the CDMA signal despread by said despreading means for each of said plurality of antennas and outputting to said combining means. CDMA signal receiving apparatus. 5. A plurality of antennas, a gain control means connected to each of the plurality of antennas for adjusting the strength of a CDMA signal received by the antennas, a gain control means connected to the gain adjustment means, and reception by the plurality of antennas. A plurality of fingers for despreading the despread CDMA signal and switching and outputting the despread CDMA signal for each of the plurality of antennas, and RAKE combining the CDMA signal output from the switching means for each of the plurality of antennas, A plurality of combining means for detecting received power for each of the plurality of antennas using a gain adjustment rate of the gain adjusting means; and a re-synthesizing means for re-synthesizing combined signals from the plurality of combining means. A CDMA signal receiving apparatus characterized by the above-mentioned. 6. A telephone comprising the receiving device according to claim 1.