JP4057826B2 - Mobile communication terminal and its path search circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention employs a code division multiple access (CDMA) system as a radio access system, and has a beam forming function in which a base station transmits a radio signal toward a limited area in a cell. The present invention relates to a mobile communication terminal used in a mobile communication system and its path search circuit.
[0002]
[Prior art]
In a mobile communication terminal of a spread spectrum wireless communication system using direct spreading, when receiving a radio signal transmitted by a base station, a multipath, that is, a RAKE receiver that combines a plurality of temporally dispersed paths may be used. Many. The RAKE receiver performs despreading for each path by a plurality of receiving circuits called fingers, and combines the outputs in phase. For this reason, in the RAKE receiver, it is necessary to specify the timing of a path to be received for each finger, and for this purpose, a circuit called a path searcher is used.
[0003]
The path searcher has a large number of detection circuits including a correlator and a power detector, and each of these detection circuits receives a known signal called a reference unit provided in the transmission signal. Then, the reception timing and reception level are detected for a large number of paths of the received reference section. Then, an appropriate path is selected from the detected many paths based on the reception level, and the reception timing of the selected path is given to the finger control unit of the RAKE receiver. The operation performed in the path searcher until the appropriate path is selected is called path search, which requires a lot of signal processing and increases power consumption.
[0004]
On the other hand, in a mobile communication system, a radio area called a cell is configured by appropriately configuring the antenna pattern for each base station. In general, the cell includes an omni cell (circular cell) configured by using an antenna having no directivity on a horizontal plane and a sector cell configured by an antenna having a fan-shaped directivity. In such cell unit communication, the number of mobile stations that can simultaneously communicate in one cell depends on the number of frequencies and the number of spreading codes. For this reason, in order to increase the capacity of each cell, it is necessary to increase the number of allocated frequencies or spreading codes. However, the number of frequencies that can be allocated is limited, and the number of spreading codes that can be used simultaneously on one frequency is limited. Since the number has an upper limit due to radio characteristics, a dramatic improvement in accommodation capacity cannot be expected.
[0005]
Therefore, a technique called beam forming is attracting attention. In the beam forming, for example, as shown in FIG. 9, a radio signal is irradiated to a limited area E in the cell Z by narrowing the directivity of the antenna of the base station BS. When beam forming is performed, the antenna gain of the base station BS is increased, so that the transmission power can be reduced. Further, since the radio signal irradiation area E is limited, interference with other areas in the cell can be reduced. it can. For this reason, it becomes possible to repeatedly use the same frequency within the same cell, and thereby the capacity of each cell can be greatly increased.
[0006]
[Problems to be solved by the invention]
However, in a system that uses both transmission for the entire cell and transmission by beamforming for a limited area, there are a reference part for a transmission signal to be transmitted to the entire cell and a reference part for a transmission signal to be transmitted by beamforming. Different spreading codes are used.
[0007]
Therefore, when a mobile communication terminal tries to receive both a transmission signal transmitted to the entire cell and a transmission signal transmitted by beam forming, the path search circuit of the mobile communication terminal transmits the entire cell. It is necessary to perform path search separately for the reference part of the transmission signal and the reference part of the transmission signal transmitted by beamforming. For this reason, when the path search circuit is configured by hardware, for example, two sets of the same circuit are provided, resulting in an increase in circuit configuration and an increase in power consumption. When the path search circuit is configured by a DSP (Digital Signal Processor) or MPU (Micro Processor Unit), the amount of signal processing required for the path search is doubled, resulting in an increase in power consumption. Such an increase in circuit configuration and an increase in power consumption are extremely undesirable for mobile communication terminals in which miniaturization and weight reduction and reduction of power consumption are one of the most important issues.
[0008]
The present invention has been made paying attention to the above circumstances, and the object of the present invention is to perform a path search for a transmission signal to the whole cell and a transmission signal by beam forming with a small circuit configuration and a small signal processing amount. It is an object of the present invention to provide a mobile communication terminal and a path search circuit for the mobile communication terminal that can perform power consumption and thereby reduce power consumption.
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention transmits a first channel signal to a cell and performs a limited area within the cell.With a transmission power level smaller than the first channel signalIn a mobile communication terminal that performs radio communication with a base station having a function of transmitting a second channel signal, the first channel signal is subjected to reception path search by one path search means, and the first channel signal is transmitted. A plurality of paths related to the channel signal are detected. Then, the second level is set such that the reception levels of the plurality of paths related to the detected first channel signal are lower than the first threshold value for selecting the path of the first channel signal. A plurality of paths having a reception level higher than the second threshold value are selected compared with the threshold value, and a plurality of paths related to the second channel signal are detected based on reception timings of the selected plurality of paths. Is provided to the correlation power detection means as timing information for detecting the reception levels of a plurality of paths related to the second channel signal. Then, the reception levels of the plurality of paths related to the second channel signal detected by the correlation power detection means are compared with a third threshold value, and the level is selected from the plurality of paths related to the second channel signal. A plurality of paths to be received related to the second channel signal are received by selecting a plurality of paths to be received and giving information indicating the timing of the selected plurality of paths to be received to the RAKE receiving means. It is what you do.
[0010]
Therefore, according to the present invention, the path of the second channel signal is detected using the result of the path search for the first channel signal. For this reason, it is not necessary to perform a reception path search for the second channel signal. As a result, the signal processing required for the path search is compared with the case where the path search is performed for both the first channel signal and the second channel signal. The amount is reduced. In addition, it is not necessary to prepare two sets of circuits for receiving path search, thereby reducing the circuit scale. Therefore, it is possible to greatly reduce the power consumption of the terminal and extend the battery life accordingly.
[0011]
In general, the first channel signal transmitted toward the entire cell has a higher transmission level than the second channel signal by beam forming. For this reason, by performing path detection of the second channel signal using the reception path search result of the first channel signal, path detection of the second channel signal can be accurately performed with simple and few processes. It becomes.
[0012]
  furtherThis invention, Path of the second channel signalThedetectionThe correlation power detection means used for this purpose is also used as a plurality of fingers provided in the second RAKE reception means for receiving the second channel signal. When configured in this way,Second channel signal pathCorrelation power detection means for detectingThere is no need to provideRuTherefore, the circuit scale can be further reduced accordingly.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a functional configuration of a mobile phone which is an embodiment of a mobile communication terminal according to the present invention. This mobile phone employs a CDMA (Code Division Multiple Access) system as a wireless access system.
[0014]
A radio frequency signal transmitted from a base station (not shown) is received by the antenna 1 and then input to the reception circuit (RX) 3 via the antenna duplexer 2 (DUP). The reception circuit 3 mixes the radio frequency signal with the reception local oscillation signal output from the frequency synthesizer (SYN) 4 and converts the frequency into an intermediate frequency signal. The received intermediate frequency signal is orthogonally demodulated to obtain a received baseband signal. The frequency of the reception local oscillation signal generated from the frequency synthesizer 4 is instructed by a control signal SYC from the control unit 12.
[0015]
The received baseband signal is despread by the spreading code assigned to the receiving channel for each path in the RAKE receiver of the CDMA signal processing unit 6 and then synthesized by matching the phase. Received packet data is obtained. The received packet data is input to the code decoding processor 7.
[0016]
The code decoding processing unit 7 separates the received packet data output from the CDMA signal processing unit 6 for each medium by the demultiplexing unit, and performs decoding processing for each separated media data. For example, if the demodulated data includes audio data, the audio data is decoded by the speech codec. If the demodulated data includes image data, the image data is decoded by a video codec. The digital audio signal obtained by this decoding process is input to the audio signal processing unit 8 and the digital image signal is input to the control unit 12. When the demodulated data includes computer data such as mail, this computer data is input to the control unit 12.
[0017]
The audio signal processing unit 8 performs PCM decoding on the digital audio signal supplied from the code decoding processing unit 7 and outputs an analog audio signal. The analog audio signal is amplified by the receiving amplifier 9 and then output from the speaker 10 as a loud voice.
[0018]
The control unit 12 displays the digital image signal supplied from the code decoding processing unit 7 on the display unit 15 via the video memory. Computer data such as mail is stored in the storage unit 13 and displayed on the display unit 15. For example, when the absence setting is made in the input unit 14, the audio data and the image data before being decoded in the code decoding processing unit 7 are taken in and stored in the storage unit 13.
[0019]
If an external information terminal such as a personal digital assistant (PDA) or a notebook personal computer is connected to the mobile phone, the data before being decoded by the encoding / decoding processing unit 7 is stored. It is also possible to transfer from the control unit 12 to the external information terminal via an external interface (not shown).
[0020]
On the other hand, the voice signal of the speaker input to the microphone 11 during communication is amplified to an appropriate level by the transmission amplifier 18 and then subjected to PCM encoding processing by the audio signal processing unit 8 to obtain a digital voice signal. And input to the code decoding processing unit 7. An image signal captured by a camera (not shown) is digitized by the control unit 12 and input to the code decoding processing unit 7. Computer data such as mail data created in the control unit 12 is also input from the control unit 12 to the code decoding processing unit 7.
[0021]
The code decoding processing unit 7 detects the energy amount of the input voice from the digital voice signal output from the audio signal processing unit 8, and determines the transmission data rate based on the detection result. The digital audio signal is encoded into a signal having a format corresponding to the transmission data rate to generate transmission audio data. Further, the digital image signal supplied from the control unit 12 is encoded to generate image data. Then, the audio data and the image data are multiplexed into packets according to a predetermined transmission format by the demultiplexing unit and output to the CDMA signal processing unit 6. Even when computer data such as mail is output from the control unit 12, the computer data is multiplexed into the packet.
[0022]
The CDMA signal processing unit 6 performs spread spectrum processing on the transmission packet output from the code decoding processing unit 7 using the spreading code assigned to the transmission channel. Then, the output signal is output to the transmission circuit (TX) 5. The transmission circuit 5 modulates the spectrum spread signal using a digital modulation method such as a QPSK method. Then, the transmission signal generated by the digital modulation is combined with the transmission local oscillation signal generated from the frequency synthesizer 4 and converted into a radio frequency signal. Then, the radio frequency signal is amplified at a high frequency so that the transmission power level instructed by the control unit 12 is obtained. The amplified transmission radio frequency signal is supplied to the antenna 1 via the antenna duplexer 2, and transmitted from the antenna 1 to the connected base station.
[0023]
In addition to the dial keys, the input unit 14 is provided with a group of function keys such as a call key, a power key, an end key, a volume control key, and a mode designation key. The display unit 15 is provided with an LCD display and an LED lamp. As described above, the LCD display displays the transmission / reception image data and the mail data, and further displays the phone book, the telephone number of the communication partner terminal, the transmission / reception history, the operation state of the terminal itself, and the like. The LED lamp is used for notifying incoming calls and displaying the discharge state of the battery 16. Reference numeral 17 denotes a power supply circuit, which generates a predetermined operating power supply voltage Vcc based on the output of the battery 16 and supplies it to each circuit unit.
[0024]
By the way, in a mobile communication system adopting a W-CDMA FDD (Wideband-Code Division Multiple Access Frequency Division Duplex) system as a radio access system, as a transmission mode of the base station, as shown in FIG. An all-cell transmission mode for transmitting a signal and a beamforming transmission mode for irradiating a limited area E in the cell Z with a radio signal are defined.
[0025]
A radio signal transmitted in the all-cell transmission mode and a radio signal transmitted in the beamforming transmission mode can be separated by the mobile station by making the spreading code different at the same frequency. A reference part received when the mobile station performs a path search is inserted into the radio signal in any mode. A common pilot channel (CPICH) is used as the reference section, the common pilot channel in the all-cell transmission mode is called P-CPICH, and the common pilot channel in the beamforming transmission mode is called S-CPICH.
[0026]
Each base station transmits the P-CPICH and the common control channel (PCCPCH) in the all-cell transmission mode, while transmitting the S-CPICH and the dedicated channel (DPCH) in the beamforming transmission mode.
[0027]
In the cellular phone of this embodiment, the CDMA signal processing unit 6 includes a circuit for corresponding to each transmission mode. FIG. 2 is a block diagram showing the configuration.
[0028]
That is, the CDMA signal processing unit 6 includes a RAKE receiver 70 for a common channel and a RAKE receiver 80 for a dedicated channel, and further, a path search used in common for these RAKE receivers 70 and 80. Part 60 is provided.
[0029]
The path search unit 60 includes a path searcher 60a for a common channel, a correlation power detector 60b for an individual channel, and a path timing selection circuit 60c.
[0030]
The common channel path searcher 60a detects a plurality of paths by performing a reception path search for the common pilot channel P-CPICH transmitted from the base station in the all-cell transmission mode. For example, as shown in FIG. Section 61, a number of correlators 621 to 62n, power detectors 631 to 63n, and first and second path selection sections 64 and 65.
[0031]
That is, in each correlator 621 to 62n, the correlation between the received baseband signal and the spreading code is obtained at the timing fixedly set by the timing control unit 61. The power detectors 631 to 63n detect the power values of the correlation outputs of the correlators 621 to 62n, respectively. The first path selection unit 64 compares each correlation power value detected by the power detectors 631 to 63n with the first threshold value TH1. A signal having a correlation power value equal to or higher than the first threshold value TH1 is selected as a path, and the timing of the selected path is set as common channel path timing information PCS to the common channel RAKE receiver 70. give.
[0032]
The second path selection unit 65 compares each correlation power value detected by the power detectors 631 to 63n with the second threshold value TH2. Then, a signal having a correlation power value equal to or greater than the second threshold TH2 is selected as a path, and the reception timing of the selected path is used as timing information SPS for detecting the path of the dedicated channel. This is given to the correlation power detector 60b.
[0033]
The dedicated channel correlation power detector 60b includes, for example, a number of correlators and power detectors corresponding to the maximum number of paths to be detected for the common pilot channel S-CPICH for dedicated channels. Then, according to the path timing information SPS given from the second path selection unit 65, the correlator and the power detector detect the power value of each path of the common pilot channel S-CPICH.
[0034]
The path timing selection circuit 60c compares the power value of each path of the common pilot channel S-CPICH detected by the dedicated channel correlation power detector 60b with a threshold value TH3. Then, the path whose power value is less than the threshold value TH3 is removed, and the reception timing of the remaining path is given to the RAKE receiver 80 for dedicated channels as path timing information SCS for dedicated channels.
[0035]
The common channel RAKE receiver 70 receives the common channel radio signal transmitted by the base station in the all-cell transmission mode according to the path timing information PCS given from the common channel path searcher 60a of the path search unit 60. To do. FIG. 4 is a diagram showing the circuit configuration.
[0036]
That is, the RAKE receiver 70 for the common channel includes a plurality of fingers 721 to 72m, a finger control unit 71 that controls the fingers 721 to 72m, and a signal synthesis unit 73. Of these, the fingers 721 to 72m include a correlator 72a and a decoder 72b, and the correlator 72a includes a spread code generator 72c, a multiplier 72d, and an integrator 72e. The spreading code generator 72c generates a spreading code for the common control channel.
[0037]
The finger control unit 71 designates the generation phase and the integration period of the spread code for the spread code generator 72c and the integrator 72e of each finger 721 to 72m according to the given path timing information PCS. Each of the fingers 721 to 72m performs spectrum despreading on the received baseband signal of the common control channel to obtain a received signal of the path, and the received signal of each path is decoded by the decoder 72b and then to the signal synthesis unit 73. Output. The signal synthesis unit 73 symbol-synthesizes the received data of each path output from each of the fingers 721 to 72m, and supplies the synthesized received data to the code decoding processing unit 7 as a RAKE reception signal.
[0038]
The dedicated channel RAKE receiver 80 also has the same circuit configuration as the common channel RAKE receiver 70. Then, the plurality of paths of the dedicated channel signal transmitted by the base station in the beamforming transmission mode, respectively, for the dedicated channel according to the dedicated channel path timing information SCS given from the path timing selection circuit 60c of the path search unit 60. The spectrum is despread by the spreading code. Then, the despread received signal of each path is decoded and symbol-synthesized, and the combined received data is supplied to the code decoding processing unit 7 as a RAKE received signal of a dedicated channel.
[0039]
Next, a path search processing operation performed in the CDMA signal processing unit 6 of the mobile phone configured as described above will be described. FIG. 5 is a flowchart showing the processing procedure and processing contents.
[0040]
When a path search instruction is input from the control unit 12, a common channel reception path search is first performed in the common channel path searcher 60a of the path search unit 60 (step 5a). This common channel reception path search is performed for the common pilot channel P-CPICH. Then, in the first path selection unit 64, the correlation power values of a large number of paths detected by the reception path search are respectively compared with the first threshold value TH1, and the correlation power value is set to the first threshold value TH1. The above path is selected (step 5b).
[0041]
For example, assume that a large number of paths as shown in FIG. 6 are detected by the reception path search. In this case, a plurality of paths with a correlation power value equal to or higher than the first threshold value TH1 among the many paths detected by the first path selection unit 64, that is, reception timings t1 and t4. , T5, t6, t7 are selected.
[0042]
The reception timings of the selected plurality of paths are given to the common channel RAKE receiver 70 as the common channel path timing information PCS (step 5c). As a result, in the common channel RAKE receiver 70, each finger performs despread processing on each of the selected paths in accordance with the common channel path timing information PCS, and the despread received data on each path. Are combined with each other and then supplied to the code decoding processing unit 7 as a RAKE reception signal of a common channel.
[0043]
On the other hand, when the reception path search result of the common channel is obtained in the common channel path searcher 60a, the second path selection unit 65 sets the correlation power value to the second value from the detected many paths. A plurality of paths having a threshold value TH2 or more are selected (step 5d). For example, in the example shown in FIG. 6, the paths at the reception timings t1, t2, t3, t4, t5, t6, t7, and t8 are selected. The reception timings of the selected plurality of paths are given to the dedicated channel correlation power detector 60b as path timing information SPS for detecting the dedicated channel path.
[0044]
The dedicated channel correlation power detector 60b detects the correlation power values of the plurality of paths selected for the dedicated channel in accordance with the path timing information SPS given from the second path selection unit 65 (step 5e). ). This path detection is performed for the common pilot channel S-CPICH. Only the multipath related to the radio signal of the dedicated channel is detected by the detection processing of the correlation power value for the dedicated channel. For example, assuming that a multipath as shown in FIG. 8 is generated between the base station BS and the mobile communication terminal MS, the path detection process of the dedicated channel correlation power detector 60b is an obstacle. The path Pa reflected by A is not detected, and only the path Pb reflected by the obstacle B is detected.
[0045]
When the correlation power values of the plurality of paths related to the dedicated channel are detected, the path timing selection circuit 60c compares the detected correlation power values of the plurality of paths with the threshold value TH3. By this comparison processing, a path whose correlation power value is less than the threshold value TH3 is deleted, and only a path having a sufficiently large correlation power value is selected (step 5f). For example, assuming that the correlation power values of a plurality of paths as shown in FIG. 7 are detected by the individual channel path detection process, the paths at the reception timings t1, t3, and t4 are selected from these paths. Then, information SCS indicating the reception timing of each selected path is provided to the RAKE receiver 80 for dedicated channels (step 5g).
[0046]
In the dedicated channel RAKE receiver 80, each finger performs despreading processing on each of the selected paths in accordance with the dedicated channel path timing information SCS, and the received data of each despread path is subjected to symbol synthesis. After that, it is supplied to the code decoding processing unit 7 as a RAKE reception signal of a dedicated channel.
[0047]
As described above, the path search unit 60 according to this embodiment first performs a reception path search for the common channel by the common channel path searcher 60a, and receives a plurality of paths for receiving the common channel path based on the search result. The path timing information PCS is given to the RAKE receiver 70 for the common channel. At the same time, based on the path search result of the common channel, a plurality of paths to be received by the dedicated channel are selected, and the path timing information SPS is given to the dedicated channel correlation power detector 60b. A plurality of paths received by the dedicated channel are detected by the device 60b. Then, a path whose correlation power value is equal to or greater than the threshold TH3 is selected from the detected plurality of paths, and the path timing information SCS of each selected path is given to the RAKE receiver 70 for the dedicated channel. I am doing so.
[0048]
Therefore, the path of the individual channel transmitted from the base station BS by beam forming is detected using the common channel path search result transmitted from the base station BS to the entire cell. This eliminates the need to perform receive path search processing independently for individual channels, resulting in a significant reduction in the amount of signal processing required for path search compared to performing path searches for both common channels and individual channels. Is done. In addition, since it is not necessary to provide two path searchers, the circuit scale of the path search unit 60 can be reduced. For this reason, the power consumption of the mobile communication terminal is greatly reduced, which makes it possible to extend the battery life.
[0049]
In general, a path searcher is configured to perform a search over a wide time range using a large number of correlators and power detectors, so that the circuit configuration and the processing amount become extremely large. On the other hand, since the correlation power amplifier 60b only detects the correlation power values of a plurality of paths selected in advance, it is only necessary to include a relatively small number of correlators and power detectors. Therefore, the circuit configuration and the amount of signal processing are smaller and smaller than those of the path searcher, and as a result, an extremely large power consumption reduction effect can be achieved.
[0050]
Further, a common channel transmitted to the entire cell Z generally has a higher transmission output level than an individual channel transmitted by beamforming. Therefore, by performing path detection for individual channels using the reception path search result for the common channel, path detection processing for individual channels can be performed easily and accurately with a small amount of processing.
[0051]
The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the dedicated channel reception path detection process is performed by the dedicated channel correlation power detector 60b. However, the dedicated channel path detection process is performed by the fingers of the dedicated channel RAKE receiver 80. May be. If comprised in this way, the correlation power detector 60b for an individual channel can be made unnecessary, As a result, the circuit scale can be reduced further.
[0052]
This can be realized, for example, by operating each finger of the RAKE receiver 80 in a time-sharing manner to perform the path detection process of the individual channel in one period and to perform the RAKE reception process in the other period. In addition, the plurality of fingers provided in the RAKE receiver 80 are divided into a first group and a second group, and the first group performs path detection processing of the individual channel, and the second group performs RAKE reception processing. This can also be realized by performing
[0053]
In the above embodiment, the RAKE receiver 70 for the common channel and the RAKE receiver 80 for the dedicated channel are provided separately. However, by operating one RAKE receiver in a time division manner, The RAKE reception process and the RAKE reception process for the dedicated channel may be respectively performed. Further, instead of performing the time division operation, a plurality of fingers provided in one RAKE receiver are divided into a first group and a second group, and a RAKE reception process for a common channel is performed on the first group. Therefore, the RAKE reception process for the dedicated channel may be performed by the second group.
[0054]
In addition, the types and configurations of mobile communication terminals, path search processing procedures and contents, path selection conditions (threshold values TH1, TH2, TH3) and the like can be variously modified without departing from the scope of the present invention. Can be implemented.
[0055]
【The invention's effect】
  As described above in detail, according to the present invention, the first channel signal is transmitted to the cell and the limited area in the cell is transmitted.With a transmission power level smaller than the first channel signalIn a mobile communication terminal that performs radio communication with a base station having a function of transmitting a second channel signal, the first channel signal is subjected to reception path search by one path search means, and the first channel signal is transmitted. A plurality of paths related to one channel signal are detected. Then, the second level is set such that the reception levels of the plurality of paths related to the detected first channel signal are lower than the first threshold value for selecting the path of the first channel signal. A plurality of paths having a reception level higher than the second threshold value are selected compared with the threshold value, and a plurality of paths related to the second channel signal are detected based on reception timings of the selected plurality of paths. Is provided to the correlation power detection means as timing information for detecting the reception levels of a plurality of paths related to the second channel signal. Then, the reception levels of the plurality of paths related to the second channel signal detected by the correlation power detection means are compared with a third threshold value, and the level is selected from the plurality of paths related to the second channel signal. A plurality of paths to be received related to the second channel signal are received by selecting a plurality of paths to be received and giving information indicating the timing of the selected plurality of paths to be received to the RAKE receiving means. Like to do.
  Further, the correlation power detecting means used for detecting the path of the second channel signal is also used as a plurality of fingers provided in the second RAKE receiving means for receiving the second channel signal. I have to.
[0056]
Therefore, according to the present invention, it is not necessary to perform the reception path search for the second channel signal by performing the path detection of the second channel signal by using the path search result for the first channel signal. Therefore, a mobile communication terminal capable of performing path search for a transmission signal to the entire cell and a transmission signal by beamforming with a small circuit configuration and a small amount of signal processing, thereby enabling low power consumption. And a path search circuit thereof.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a mobile phone as an embodiment of a mobile communication terminal according to the present invention.
2 is a circuit block diagram showing a configuration of a CDMA signal processing unit in the mobile phone shown in FIG. 1;
3 is a circuit block diagram showing a configuration of a common channel path searcher provided in the CDMA signal processing section shown in FIG. 2;
4 is a circuit block diagram showing a configuration of a common channel RAKE receiver provided in the CDMA signal processing section shown in FIG. 2;
FIG. 5 is a flowchart showing the procedure and contents of a path search process performed in the CDMA signal processing unit shown in FIG. 2;
6 is a diagram showing an example of a path search output of the common channel path searcher shown in FIG. 3. FIG.
7 is a diagram illustrating an example of a path detection output of a dedicated channel correlation power detector provided in the CDMA signal processing unit illustrated in FIG. 2;
FIG. 8 is a diagram for explaining a path search processing operation performed in the CDMA signal processing unit shown in FIG. 2;
FIG. 9 is a diagram for explaining an example of an all-cell transmission mode and a beamforming transmission mode.
[Explanation of symbols]
BS ... Base station
MS ... Mobile communication terminal
Z ... cell
E ... Target area for beam forming
1 ... Antenna
2 ... Antenna duplexer (DUP)
3. Receiving circuit (RX)
4 ... Frequency synthesizer (SYN)
5 ... Transmission circuit (TX)
6 ... CDMA signal processor
7: Compression / decompression processor
8 ... PCM code processing section
9 ... Receiving amplifier
10 ... Speaker
11 ... Microphone
12 ... Control unit
13. Storage unit
14 ... Input section
15 ... Display section
16 ... Battery
17 ... Power circuit
18 ... Transmission amplifier
60 ... Path search part
61 ... Timing control section
621-62n ... Correlator
631 to 63n ... power detector
64: First path selection unit
65: Second path selection unit
60a ... Path searcher for common channel
60b ... Correlation power detector for individual channel
60c: Path timing selection circuit
70 ... RAKE receiver for common channel
71: Finger control unit
721-72m ... Finger
72a ... correlator
72b Decoder
72c ... Spreading code generator
72d ... multiplier
73 ... Signal synthesis unit
80 ... RAKE receiver for individual channel

Claims (4)

A base station having a function of transmitting a first channel signal to a cell and transmitting a second channel signal to a limited area in the cell at a transmission power level smaller than that of the first channel signal ; Mobile communication terminals that perform wireless communication between
One path search means for performing a reception path search on the first channel signal and detecting a plurality of paths related to the first channel signal;
A reception level of a plurality of paths related to the first channel signal detected by the path search means is set to a value lower than a first threshold value for selecting a path of the first channel signal. A plurality of paths having a reception level higher than that of the second threshold value, and the reception timings of the selected plurality of paths are set to a plurality of values related to the second channel signal. Path selection means for outputting as timing information for detecting a path;
Correlation power detection means for detecting reception levels of a plurality of paths related to the second channel signal according to the timing information output from the path selection means;
By comparing the reception levels of the plurality of paths related to the second channel signal detected by the correlation power detection means with the third threshold value, the plurality of paths related to the second channel signal are selected. Path timing selection means for selecting a plurality of paths to be received and outputting information indicating the timings of the selected paths to be received;
RAKE receiving means for receiving the plurality of paths to be received related to the second channel signal in accordance with information indicating timing output from the path timing selecting means ,
The correlation power detection means detects a plurality of paths related to the second channel signal by using a plurality of fingers provided in the RAKE reception means . A base station having a function of transmitting a first channel signal to a cell and transmitting a second channel signal to a limited area in the cell at a transmission power level smaller than that of the first channel signal ; Mobile communication terminals that perform wireless communication between
One path search means for performing a reception path search on the first channel signal and detecting a plurality of paths related to the first channel signal;
The reception levels of a plurality of paths related to the first channel signal detected by the path search means are compared with a preset first threshold value, and the reception level is higher than the first threshold value. First path selection means for selecting a plurality of paths and outputting reception timings of the selected plurality of paths as first timing information for detecting a plurality of paths related to the first channel signal;
The reception levels of a plurality of paths related to the first channel signal detected by the path search means are compared with a second threshold value set to a value lower than the first threshold value. A plurality of paths having a reception level higher than a threshold value of 2 are selected, and reception timings of the selected plurality of paths are used as second timing information for detecting a plurality of paths related to the second channel signal. Second path selection means for outputting;
Correlation power detection means for detecting reception levels of a plurality of paths related to the second channel signal in accordance with second timing information output from the second path selection means;
By comparing the reception levels of the plurality of paths related to the second channel signal detected by the correlation power detection means with the third threshold value, the plurality of paths related to the second channel signal are selected. Path timing selection means for selecting a plurality of paths to be received and outputting information indicating the timings of the selected paths to be received;
First RAKE receiving means for receiving a plurality of paths related to the first channel signal in accordance with first timing information output from the first path selecting means;
Second RAKE receiving means for receiving a plurality of paths to be received related to the second channel signal in accordance with information representing timing output from the path timing selecting means ,
The correlation power detection means detects a plurality of paths related to the second channel signal by using a plurality of fingers provided in the second RAKE reception means. Terminal. The first and second RAKE means operate one RAKE receiver in a time-division manner, so that a plurality of paths related to the first channel signal selected by the first path selection means, and the path 3. The mobile communication terminal according to claim 2, wherein each of the plurality of paths related to the second channel signal selected by the timing selecting means is received. A base station having a function of transmitting a first channel signal to a cell and transmitting a second channel signal to a limited area in the cell at a transmission power level smaller than that of the first channel signal ; Path search circuit provided in a mobile communication terminal that performs wireless communication between
One path search means for performing a reception path search on the first channel signal and detecting a plurality of paths related to the first channel signal;
A reception level of a plurality of paths related to the first channel signal detected by the path search means is set to a value lower than a first threshold value for selecting a path of the first channel signal. A plurality of paths having a reception level higher than that of the second threshold value, and the reception timings of the selected plurality of paths are set to a plurality of values related to the second channel signal. Means for outputting as timing information for detecting a path;
Correlation power detection means for detecting reception levels of a plurality of paths related to the second channel signal according to the output timing information;
By comparing the reception levels of the plurality of paths related to the second channel signal detected by the correlation power detection means with the third threshold value, the plurality of paths related to the second channel signal are selected. Means for selecting a plurality of paths to be received; and
Among the plurality of paths related to the second channel signal, information indicating the reception timing of the selected plurality of paths is received by the RAKE reception so that the RAKE receiver receives the plurality of selected reception target paths. Providing means to the machine ,
The correlation power detecting means detects a plurality of paths related to the second channel signal by using a plurality of fingers provided in the second RAKE receiving means. circuit.

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