JP2002164817A - Mobile radio terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile radio terminal which can reduce the calculational load on path detecting process without deterioration in receiving characteristics. SOLUTION: In this terminal, a control part 100 provides a path search control means 100a having two timer functions, a path search is performed controlling a searcher 16a by this means, that is, in the path search control by the pass search control means 100a, as a path detection process A1 the searcher 16a is controlled so that the maximum numbers m of path suitable for reception are detected by performing path search over one symbol interval every time when a long period Ta elapses, and after the process, every time when a short period Tb shorter than the long period Ta elapses, as a path following process B1 a path search is performed to ±N chips centering inverse of spread timings T1 to Tm corresponding to the paths detected by the path search, as a result the searcher 16a is controlled to follow the paths suitable for reception.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio terminal used in a mobile communication system using a direct spread-spread spectrum system as a communication system.

[0002]

2. Description of the Related Art As is well known, a mobile radio terminal adopting a direct spread-spectrum spread method as a communication method detects a plurality of paths suitable for reception and uses these paths by a plurality of despreaders. Despreading is performed, and the result is rake-combined and received.

[0003] As described above, a mobile radio terminal adopting the direct spread / spread spectrum method receives radio signals through a plurality of paths and combines them to improve the fading resistance.

The above-described process of detecting a path suitable for reception is generally called a path search, and is conventionally performed by a process as shown in FIG.
When the power of the mobile radio terminal is turned on, first, step 15
The timer is reset at step a, and the timer is started at step 15b to start counting.
Move to

In step 15c, the count value of the timer is compared with a preset value relating to a path detection cycle set in advance, and it is determined whether or not a path detection cycle has arrived. Here, if the path detection cycle has arrived, the process proceeds to step 15d, while if the path detection cycle has not yet arrived, the arrival of the path detection cycle is monitored in step 15c.

In step 15d, a process for detecting a plurality of paths suitable for reception is executed. Specifically, for example, a wide range of about one symbol section is sampled with a predetermined width from the received signal, and a correlation value between the sampling result and the spread code is obtained.

[0007] Then, among the obtained correlation values, a plurality of large correlation values are obtained, and the path detection is performed by setting the sampling timing corresponding to this as the despread timing of the path suitable for reception.

[0008] The reception timings of a plurality of paths detected in this way are respectively assigned to a plurality of despreaders. On the other hand, the despreader despreads the received signal at the timing assigned to itself, and receives paths suitable for reception.

[0009] Thereafter, in step 15e, it is determined whether or not a request to turn off the power has occurred. If this request has occurred, the process is terminated. On the other hand, if the request has not occurred, step 15a is determined. Then, the process of detecting a path suitable for reception is repeatedly executed at a predetermined cycle. However, the conventional path detection processing as described above has a problem that a calculation load is large and a great amount of power consumption is required.

[0010]

The conventional mobile radio terminal has a problem that the calculation load of the path detection processing is large and a large amount of power is required. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a mobile radio terminal capable of reducing the calculation load of the path detection processing without deteriorating reception characteristics.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a mobile radio terminal used in a mobile communication system using a direct spread-spectrum spread communication system. Digital conversion means for converting the converted signal into a digital signal, and sequentially despreading the digital signal obtained by the digital conversion means for a predetermined period starting from the timing based on the chip rate, and raked from the correlation level of the despread result. Path detecting means for detecting a plurality of paths suitable for performing reception, and a predetermined number of continuous chip timings based on despreading timings corresponding to the paths detected by the path detecting means as starting points. The obtained digital signal is despread and received from the correlation level of the despread result. A path tracking means for performing path tracking processing for detecting paths suitable for and adapted to configure and control means for selectively operating the path detecting means and the path tracking means.

According to a fourth aspect of the present invention, there is provided a mobile radio terminal used in a mobile communication system using a direct spread / spread spectrum system as a communication system, a digital conversion means for converting a received signal into a digital signal,
A path for sequentially despreading a digital signal obtained by the digital conversion means starting from a timing based on a chip rate over a predetermined period, and detecting a plurality of paths suitable for performing rake reception from a correlation level of the despread result. Starting from a predetermined number of consecutive timings based on the despreading timing corresponding to the path detected by the detecting means and the path detected by the path detecting means, respectively, to despread the digital signal obtained by the digital conversion means; Path following means for performing path following processing for detecting a path suitable for reception from the correlation level of the path, control means for selectively operating the path detecting means and the path following means, and correlation of the paths detected by the path detecting means. Timing density setting means for varying the density of a predetermined number of consecutive timings according to the level. It was to be constructed by.

In the mobile radio terminal having the above configuration, for example, the digitized received signal of one symbol section (256 chips) is sequentially despread starting from the timing corresponding to each chip, and the rake is determined from the correlation level of the despread result. Path detection processing for detecting a plurality of paths suitable for performing reception,
Starting from a predetermined number of consecutive (chip) timings based on the despreading timing corresponding to the path detected in this path detection processing, the digitized received signal is despread, and received from the correlation level of the despread result. And a path follow-up process for detecting a path suitable for the above are selectively performed under the control of the selection means.

Therefore, according to the mobile radio terminal having the above configuration, the number of data processes in the path follow-up process can be set to be significantly smaller than the number of data processes in the path detection process by setting the predetermined number. In comparison with the case where only a path detection process is repeatedly performed to detect a path suitable for reception, the number of data processes can be efficiently reduced, and the path detection process and the path following process are selectively performed. Therefore, the reception quality does not deteriorate.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.
1 shows a configuration of a CDMA mobile radio terminal according to the embodiment of the present invention. In this embodiment, the reception system according to the present invention will be mainly described.

The transmitting device 12 modulates transmission data such as digitized voice and data by a digital modulation method such as PSK modulation, spreads the modulated data using a spreading code, and generates a wideband base signal. Convert to band signal.

The transmitting apparatus 12 up-converts the spread baseband signal into a radio frequency signal and inputs the signal to the antenna 10 through the duplexer 11. The input radio frequency signal is transmitted to the antenna 10
It is radiated further into space and transmitted to a base station (not shown).

On the other hand, the radio signal transmitted from the base station is received by the antenna 10 and input to the receiving device 13 through the duplexer 11. The receiving device 13 is a wireless circuit 1
4, an intermediate frequency circuit 15, and a rake (rake) receiver 16.

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

The signal down-converted to the intermediate frequency is input to an intermediate frequency circuit 15 and amplified to a predetermined level by an amplifier 15a. The result of the amplification is input to a band-pass filter (BPF) 15b, from which only a desired band passes and input to a mixer 15c.

In the mixer 15c, the bandpass filter 1
The signal that has passed through 5b is mixed with the signal generated by frequency synthesizer 15d, and is converted into a baseband signal.

This baseband signal is converted into a digital signal by an A / D converter (A / D) 15e, and Ra
Input to the ke receiver 16. The sampling rate in the A / D converter 15e is set to a frequency that is several times the spreading rate on the transmitting side.

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

The searcher 16a includes a control unit 100 described later.
The digital signal is despread by multiplying the digital signal by various spreading codes at various timings. Based on the result of the despreading, the digital signal is suitable for receiving a signal transmitted from the base station to its own terminal. Multiple detected paths.

Then, the searcher 16a notifies the control unit 100 of the spreading code corresponding to the detected path and the timing of despreading as path information suitable for reception (hereinafter referred to as path information).

The fingers 16b, 16c and 16d perform despreading processing on the digital signal with the despreading timing and spreading code assigned by the control unit 100. The symbol combiner 16e includes the fingers 16b, 16
The multipath symbols obtained by the despreading processes c and 16d are symbol-synthesized in consideration of the despreading timing assigned to each of the fingers 16b, 16c and 16d.

The signal that has been symbol-synthesized by the symbol synthesizer 16e is subjected to demodulation processing corresponding to digital modulation on the transmission side in a signal processing unit 17 at the subsequent stage, and received data is reproduced.

The control unit 100 includes a CPU, a ROM and an R
AM, etc., wherein the CPU is the RO
In accordance with a control program and control data stored in M, each unit of the mobile wireless terminal device is controlled in an integrated manner.

The control unit 100 includes a path search control unit 100a having two timer functions. The control unit 100 controls the searcher 16a to perform a path search unique to the present application.

That is, the path search control means 100
In the path search control by “a”, as shown in FIG. 2, as the path detection processing A1, a normal path search over one symbol interval is performed every time the long period Ta elapses, and at most m paths suitable for reception are obtained. To detect, the searcher 16
control a.

Thereafter, each time a short period Tb shorter than the long period Ta elapses, a path following process B1 is executed.
The path search is performed for ± N chips around the despread timings T1 to Tm corresponding to the paths detected by the path search, and the searcher 16a is controlled so as to detect a path suitable for reception.

The storage unit 200 is a recording medium such as a ROM and a RAM, and has an area for storing various information such as telephone directory data which can be arbitrarily recorded by a user. Has an area for storing the despread timings T1 to Tm of the path suitable for reception, which is obtained by the path search control according to the above. The information stored in this area is updated by the path search control means 100a.

Although not shown in FIG. 1, there is a power supply section which supplies a power for operating the above-described sections and has a battery which can be repeatedly charged and discharged, as a component of the apparatus.

Next, the path search operation of the mobile radio terminal having the above configuration will be described. FIG. 3 is a flowchart showing the processing at the time of this operation. This processing is performed by the path search control means 100a.

First, when the power is turned on, in step 3a, two timers, ie, a path detection timer Tii1 and a path follow-up timer Tii2, are reset, counting is started, and the process proceeds to step 3b.

In step 3b, the searcher 16a is controlled to execute the path detection processing A1. In this path detection processing A1, as shown in FIG. 2, a normal path search over one symbol (256 chips) section is performed to detect at most m paths suitable for reception, and inverse paths corresponding to these paths are detected. The diffusion timings T1 to Tm are obtained, and the timings are recorded in the storage unit 200.

Then, among the plurality of paths detected,
The despreading timing corresponding to the top three reception power levels that are large and suitable for reception is determined by the fingers 16b and 16b.
c, 16d, and then proceeds to step 3c.

Thus, the fingers 16b, 16c, 1
Reference numeral 6d despreads the digital signal from the A / D converter 15e at despread timings corresponding to the upper three paths suitable for reception.

In step 3c, the path detection timer Tii
It is determined whether or not the count value of 1 has reached the long cycle Ta. If the count value of the path detection timer Tii1 has not reached the long cycle Ta, the process proceeds to step 3d.

On the other hand, if the count value of the path detection timer Tii1 has reached the long cycle Ta, the process proceeds to step 3a, where the path detection timer Tii1 and the path following timer Tii1 are set.
After restarting Step 2, the path detection processing A1 is executed again in Step 3b.

In step 3d, it is determined whether or not an operation for turning off the power is performed. Here, if the above operation is performed, the process is terminated, while if the above operation is not performed, the process proceeds to step 3e.

In step 3e, the path following timer Tii
It is determined whether or not the count value of 2 has reached the short period Tb. If the count value of the path following timer Ti2 has not reached the short cycle Tb, the process proceeds to step 3c. On the other hand, when the count value of the path following timer Ti2 has reached the short period Tb, the process proceeds to step 3f. In step 3f, after the path following timer Ti2 is reset, counting is started, and the process proceeds to step 3g.

In step 3g, the searcher 16a is controlled to execute the path following processing B1. The path follow-up processing B1 follows the fluctuating timing of up to m despread timings T1 to Tm stored in the storage unit 200.

First, the despreading timings T1 to Tm stored in the storage unit 200 are read out, and, as shown in FIG. 2, a path search is performed for a section of ± N chips centering on these timings. Thus, ±± for each path of the despread timings T1 to Tm.
A path suitable for reception is detected from the section of N chips, new despreading timings T1 to Tm corresponding to this path are obtained, and this timing is recorded in the storage unit 200.

Then, among the plurality of paths detected,
The despreading timing corresponding to the top three reception power levels that are large and suitable for reception is determined by the fingers 16b and 16b.
c, 16d, and then proceeds to step 3c.

Thus, the fingers 16b, 16c, 1
Reference numeral 6d despreads the digital signal from the A / D converter 15e at despread timings corresponding to the upper three paths suitable for reception.

As described above, in the mobile radio terminal having the above configuration, as the path detection processing A1, a normal path search over one symbol section is performed every time the long period Ta elapses, and a path suitable for reception is detected. After that, every time a short period Tb shorter than the long period Ta elapses, a path following process B1 is performed around the despread timing corresponding to the path detected by the path search.
A path search is performed for N chips, and processing for detecting a path suitable for reception is performed.

For this reason, for example, the short cycle Tb is changed to the long cycle Ta
, The following window width N in the path following process B1 is set to 2, and the maximum number of detected paths m is set to 4, the required data processing amount is compared with the conventional case.

In this case, as shown in FIG. 4, when viewed in the 2 × Ta period, conventionally, the pass detection processing A1 is performed four times to process 4 × 256 chips, that is, 1024 data. On the other hand, the mobile radio terminal having the above configuration performs two path detection processes A1 and six path follow-up processes B1, so that 2 × 256 + 6 × 5 × 4 chips, that is, 632 pieces of data are used. Will be processed.

Therefore, according to the mobile radio terminal having the above configuration, the number of data processes is reduced, and the path detection processing A1 and the path tracking processing B1 are selectively performed, so that a path suitable for reception can be efficiently established. Since the detection is performed, the calculation load of the path detection processing can be reduced without lowering the reception characteristics.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the following window width N of the path following process B1 has been described as a fixed value, but it may be variably controlled according to the situation.

For example, a case will be described in which the value of the following window width N is varied according to the moving speed to execute the path following process B1. In this case, the mobile radio terminal includes a speed detection circuit 18 in addition to the configuration shown in FIG. 1 described above, and is configured as shown in FIG.

Path follow-up processing B with this configuration
1 will be described. This processing is performed by the path search control means 100b according to a flowchart as shown in FIG.

First, in step 6a, the speed detection circuit 1
8, information V indicating the moving speed of the own terminal is acquired, and the process proceeds to step 6b. The speed detection circuit 18 detects the moving speed based on, for example, the fading pitch of the received signal.

In step 6b, it is determined whether or not the moving speed information V is larger than a threshold value Vth1. Here, when the moving speed information V is higher than the threshold value Vth1, the process proceeds to step 6d. On the other hand, when the moving speed information V is not larger than the threshold value Vth1, the process proceeds to step 6c.

In step 6b, it is determined whether or not the moving speed information V is larger than a threshold value Vth2 (<Vth1). Here, when the vehicle travels at medium speed where the moving speed information V is larger than the threshold value Vth2, the process proceeds to step 6e. On the other hand, when the vehicle travels at a low speed where the moving speed information V is not greater than the threshold value Vth2, the process proceeds to step 6f.

In step 6d, the following window width N is set to the maximum value N.
In step 6e, the tracking window width N is set to N.
2 (<N1). In step 6f, the tracking window width N is set to the minimum value N3. When the following window width N is set in this way, the process proceeds to step 6g.

In step 6g, first, the despread timing stored in the storage unit 200 is read out, and a path search is performed for a section of ± N chips centering on this timing to obtain the path of the despread timing. Each time, a path suitable for reception is detected from the section of ± N chips, a despread timing corresponding to this path is obtained, and this timing is recorded in the storage unit 200.

Then, among the plurality of paths detected,
The despreading timings corresponding to the top three signals suitable for reception are assigned to the fingers 16b, 16c and 16d.
Thus, the fingers 16b, 16c, and 16d perform the despreading process on the digital signal from the A / D converter 15e at the despreading timing corresponding to the upper three paths suitable for reception.

Even in the case of the above configuration, the number of data processing is reduced, and the path detection processing A1 and the path following processing B
1 selectively detects a path suitable for reception efficiently, without deteriorating reception characteristics.
Since the calculation load of the path detection processing can be reduced, and the follow-up window width N is varied according to the moving speed, the calculation load of the path detection processing can be reduced more efficiently.

In another embodiment, for example, the path search control means 100a can vary the value of the following window width N according to the received power level of each path to perform the path following processing B1. .

In this case, as shown in FIG.
In the path detection processing A1 of step b or the path following processing B1 of step 3g, the reception power level P1 of each path is associated with the despread timings T1 to Tm of the paths suitable for reception up to m obtained in each processing. To Pm are recorded in the storage unit 200 as path information.

The received power levels P1 to Pm are P
For a path equal to or greater than th1, a ± N1 chip centered on the despreading timing (T1 to Tm) of the path is set as the tracking window width N. For a path equal to or greater than Pth2 and less than Pth1, the despreading timing of the path ( The following window width N is defined as ± N2 (<N1) chips centered on T1 to Tm).
Then, as for a path smaller than Pth2, ± N3 (<N) around the despread timing (T1 to Tm) of the path.
N2) The despreading timing of the path suitable for reception is updated with the chip as the tracking window width N.

Even in the case of the above configuration, the number of data processing is reduced, and the path detection processing A1 and the path following processing B
1 selectively detects a path suitable for reception efficiently, without deteriorating reception characteristics.
The computational load of the path detection processing can be reduced, and the follow-up window width N is varied according to the reception power level of the path. Therefore, the computational load of the path detection processing is more efficiently focused on paths suitable for reception. Can be reduced.

Next, a CDMA mobile radio terminal according to a second embodiment of the present invention will be described. FIG.
Shows the configuration of the mobile radio terminal. However,
8, the same parts as those of the mobile radio terminal according to the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and here, a different part, that is, a path search control unit 100c will be described.

The control unit 100 includes a CPU, a ROM and an R
AM, etc., wherein the CPU is the RO
In accordance with a control program and control data stored in M, each unit of the mobile wireless terminal device is controlled in an integrated manner.

The control unit 100 includes a path search control unit 100c having two timer functions. The control unit 100 controls the searcher 16a to perform a path search unique to the present application.

That is, the path search control means 100
In the path search control by c, as shown in FIG. 9, as the path detection processing A2, a normal path search over one symbol section is performed every time the long period Ta elapses, and at most m paths suitable for reception are obtained. Then, based on the threshold value Pth, the priority levels Δ1 and Δ2 corresponding to the received power are set.

Thereafter, each time the short period Tb shorter than the long period Ta elapses, the path following processing B21, B2
As No. 2, a path search is performed for ± N chips around the despread timings T1 to Tm corresponding to the path detected by the path search, and a path suitable for reception is detected.

In the path following process B21, a path search is performed for only ± N chips centered on the despread timings T1 to Tm to perform the path following only the paths for which the high priority Δ1 is set. Path following processing B2
In the case of No. 2, for the paths for which the priorities Δ1 and Δ2 have been set,
A path search is performed for ± N chips around the despread timings T1 to Tm to follow the path.

The storage section 200 is a recording medium such as a ROM and a RAM, and has an area for storing various information such as telephone directory data which can be arbitrarily recorded by a user, and a path search control section 100c. Despreading timings T1 to Tm of paths suitable for reception and their corresponding priorities Δ1 and Δ2 obtained by path search control according to
Is stored in this area, and the information stored in this area is updated by the path search control unit 100c.

Next, the path search operation of the mobile radio terminal having the above configuration will be described. FIG. 10 is a flowchart showing the processing at the time of this operation. This processing is performed by the path search control means 100c.

First, when the power is turned on, step 10a
After resetting two timers, that is, a path detection timer Ti1 and a path following timer Ti2, counting is started. Then, the flag is set to “0”, and Step 1
0b.

At step 10b, the searcher 16a is controlled to execute the path detection processing A2. In this path detection processing A2, as shown in FIG. 9, a normal path search over one symbol (256 chips) section is performed to detect a maximum of m paths suitable for reception, and inverse paths corresponding to these paths are detected. The diffusion timings T1 to Tm are obtained.

Then, a high priority Δ1 is set for a path whose received power level is equal to or higher than a preset threshold Pth, and a path whose received power level is lower than the threshold Pth is set for the path obtained. Low priority Δ2
Set.

The despreading timings T1 to Tm
And the priority Δ1 or Δ2 of the corresponding path is stored in the storage unit 200 in association with each other. Further, among the plurality of paths detected, despreading timings corresponding to the top three reception power levels that are high and suitable for reception are assigned to the fingers 16b, 16c, and 16d, and the process proceeds to step 10c.

Thus, the fingers 16b, 16c, 1
Reference numeral 6d despreads the digital signal from the A / D converter 15e at despread timings corresponding to the upper three paths suitable for reception.

In step 10c, the path detection timer Ti
It is determined whether or not the count value of 1 has reached the long cycle Ta. If the count value of the path detection timer Ti1 has not reached the long cycle Ta, the process proceeds to step 10d.

On the other hand, if the count value of the path detection timer Ti1 has reached the long cycle Ta, the operation proceeds to step 10a, where the path detection timer Ti1 and the path following timer Ti2 are restarted, and then the operation returns to step 10b. To execute the path detection processing A2.

At step 10d, it is determined whether or not an operation for turning off the power is performed. Here, if the above operation has been performed, the process is terminated, while if the above operation has not been performed, the process proceeds to step 10e.

In step 10e, the path following timer Ti
It is determined whether or not the count value of 2 has reached the short period Tb. If the count value of the path following timer Ti2 has not reached the short cycle Tb, the process proceeds to step 10c. On the other hand, when the count value of the path following timer Ti2 has reached the short period Tb, the process proceeds to step 10f.

At step 10f, the path following timer Ti
After resetting 2, counting is started, and step 10 is started.
Go to g. In step 10g, it is determined whether the value set in the flag is “0”. Here, when the value set in the flag is “0”, the process proceeds to step 10h, and when the value set in the flag is not “0”, the process proceeds to step 10j.

At step 10h, the searcher 16a is controlled to execute the path following processing B21. This path follow-up processing B21 is the maximum
Of the despreading timings T1 to Tm, the timing at which the priority Δ1 is set follows the fluctuating timing.

First, of the despreading timings T1 to Tm stored in the storage unit 200, the timing at which the priority level Δ1 is set is read out. Is performed, a path suitable for reception is detected from the section of ± N chips for each path of the despread timing for which the priority Δ1 is set, and a new despread timing corresponding to this path is obtained. The timing is recorded in the storage unit 200.

Then, of the paths for which the despread timing has been newly obtained in this way, the despread timings corresponding to the three higher-order ones suitable for reception having a higher received power level are determined by the fingers 16b, 16c and 16d. And proceeds to step 10i.

Thus, the fingers 16b, 16c, 1
Reference numeral 6d despreads the digital signal from the A / D converter 15e at despread timings corresponding to the upper three paths suitable for reception.

On the other hand, in step 10j, the searcher 16
a is controlled to execute the path following process B22. This path following processing B22 is stored in the storage unit 200.
With respect to a maximum of m despreading timings T1 to Tm, that is, timings at which the priorities Δ1 and Δ2 are set, the timings fluctuate.

First, the despreading timings T1 to Tm stored in the storage unit 200 are read out, and a path search is performed for each of the sections of ± N chips centered on these timings. ± N
A path suitable for reception is detected from the section of the chip, a new despread timing corresponding to this path is obtained, and this timing is set as despread timings T1 to Tm.
To record.

Then, of the paths for which the despreading timing is newly obtained in this manner, the despreading timings corresponding to the top three reception power levels which are large and suitable for reception are determined by the fingers 16b, 16c and 16d. And the process proceeds to step 10k.

Thus, the fingers 16b, 16c, 1
Reference numeral 6d despreads the digital signal from the A / D converter 15e at despread timings corresponding to the upper three paths suitable for reception.

At step 10i, "1" is set as the flag.
Is set, and the routine goes to Step 10c. On the other hand, in step 10k, “0” is set as a flag,
Shift to 0c.

As described above, in the mobile radio terminal having the above configuration, as the path detection processing A2, a normal path search over one symbol section is performed every time the long period Ta elapses, and a path suitable for reception is detected. After that, every time the short period Tb shorter than the long period Ta elapses, the path following processes B21 and B22 are performed around the despread timing corresponding to the path detected by the path search. A path search is performed for N chips, and processing for detecting a path suitable for reception is performed.

In the path follow-up processing B21, only the paths for which the high priority Δ1 has been set in the path detection processing A2 have ±
A path search is performed for N chips to perform path following. On the other hand, in the path following processing B22, priority levels Δ1, Δ2
Despreading timings T1 to T
A path search is performed for ± N chips centered at m to follow the path. That is, in the processing relating to path following, for a path having a low received power level, the number of data processing is reduced by reducing the frequency of the path following processing.

Therefore, according to the mobile radio terminal having the above configuration, the number of data processes is reduced while emphasizing a path suitable for reception, and the path detection processing A2 and the path following processing B21 or B22 are selectively performed. By implementing,
Since a path suitable for reception is efficiently detected, the calculation load of the path detection processing can be reduced without lowering reception characteristics.

The present invention is not limited to the above embodiment. For example, fingers 16b, 16c, 1
6d follows a DLL (Dela) that follows an appropriate despread timing based on the despread timing assigned to itself.
(y LockedLoop) function, in the path detection process A2 in step 10b, as shown in FIG. 11, a low priority Δ2 is set for the despread timing assigned to the fingers 16b, 16c, and 16d, and the remaining priority remains. Among the despread timings, a high priority Δ1 is set for a path having a reception power level equal to or higher than a preset threshold Pth, and a low priority Δ2 is set for a path having a reception power level lower than the threshold Pth.

When the priorities are set in this way, the despreading timing assigned to the fingers 16b, 16c and 16d is followed by the DLL function of each finger, and the fingers 16b, 16c and 16d are followed. Of the despread timings that have not been assigned, only those that are promising as reception paths will be preferentially followed.

That is, in the processing relating to path following, the received power level is low, and the fingers 16b, 16c,
For the despreading timing not allocated to 16d, the frequency of the path following processing is reduced, and the number of data processing is reduced.

Therefore, according to the mobile radio terminal having the above-described configuration, while emphasizing the path suitable for reception, the path followed by the DLL function of each finger is neglected, and the number of data processing is further reduced. And the path detection processing A2
By selectively performing the path follow-up processing B21 or B22, a path suitable for reception is efficiently detected, so that the calculation load of the path detection processing can be reduced without lowering the reception characteristics.

Further, as in the first embodiment, the speed detection circuit 18 shown in FIG. 5 is provided, and the value of the following window width N in the path following process B21 or B22 according to the speed detected by the speed detecting circuit 18 is provided. May be changed. With such a configuration, the following window width N can be varied according to the moving speed, and the calculation load of the path detection processing can be reduced more efficiently.

Further, similarly to the first embodiment, as shown in FIG. 7, the path search control means 100c changes the value of the tracking window width N according to the reception power level of each path to perform the path tracking. It is also possible to carry out the processing B21 or B22.

According to this, since the follow-up window width N is varied according to the reception power level of the path, it is possible to focus on a path suitable for reception and reduce the calculation load of the path detection processing more efficiently. .

Next, a CDMA mobile radio terminal according to a third embodiment of the present invention will be described. FIG.
Shows the configuration of the mobile radio terminal. However,
12, the same parts as those of the mobile radio terminal according to the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and are different here.
Will be described.

The control unit 100 includes a CPU, a ROM and an R
AM, etc., wherein the CPU is the RO
In accordance with a control program and control data stored in M, each unit of the mobile wireless terminal device is controlled in an integrated manner.

The control unit 100 includes a path search control unit 100c having two timer functions. The control unit 100 controls the searcher 16a to perform a path search unique to the present application.

That is, the path search control means 100
In the path search control according to d, as shown in FIG.
A normal path search over a symbol section is performed to detect a maximum of m paths suitable for reception.

Thereafter, every time a short period Tb shorter than the long period Ta elapses, a path following process B3 is performed.
A path search is performed for ± N chips around despread timings T1 to Tm corresponding to the path detected by the path search, and a path suitable for reception is detected.

In the path follow-up processing B3, for the path having the highest received power level (T2 in FIG. 13), ± N chips centered on the despread timing corresponding to this path are passed at a density α. The path is followed by searching, while for the other remaining paths, ± N chips centered on the despread timing corresponding to each path are subjected to a path search with a density β (> α) to perform path following.

The storage unit 200 is a recording medium such as a ROM and a RAM, and has an area for storing various information such as telephone directory data that can be arbitrarily recorded by the user, and also has a path search control unit 100d. Has an area for storing the despread timings T1 to Tm of the path suitable for reception, the set value of the following window width N, and the set values of the densities α and β obtained by the path search control according to. The information is updated by the path search control unit 100d.

Next, a path search operation of the mobile radio terminal having the above configuration will be described. FIG. 14 is a flowchart showing the processing at the time of this operation, and this processing is performed by the path search control means 100d.

First, when the power is turned on, step 14a
After resetting the two timers, that is, the path detection timer Ti1 and the path following timer Ti2, the counting is started and the process proceeds to step 14b.

In step 14b, the searcher 16a is controlled to execute the path detection processing A3. In this path detection processing A3, as shown in FIG. 13, a normal path search over one symbol (256 chips) section is performed to detect at most m paths suitable for reception, and inverse paths corresponding to these paths are detected. The diffusion timings T1 to Tm are obtained, and the timings are recorded in the storage unit 200. At this time, for the path having the highest received power level, identification information indicating that is recorded in association with the corresponding despread timing.

Then, among the plurality of paths detected,
The despreading timing corresponding to the top three reception power levels that are large and suitable for reception is determined by the fingers 16b and 16b.
c, 16d, and then proceeds to step 14c.

Thus, the fingers 16b, 16c, 1
Reference numeral 6d despreads the digital signal from the A / D converter 15e at despread timings corresponding to the upper three paths suitable for reception.

In step 14c, the path detection timer Ti
It is determined whether or not the count value of 1 has reached the long cycle Ta. If the count value of the path detection timer Ti1 has not reached the long cycle Ta, the process proceeds to step 14d.

On the other hand, if the count value of the path detection timer Ti1 has reached the long cycle Ta, the operation proceeds to step 14a, where the path detection timer Ti1 and the path following timer Ti2 are restarted, and then the operation returns to step 14b. To execute the path detection processing A3.

In step 14d, it is determined whether or not an operation to turn off the power has been performed. Here, if the above operation has been performed, the process is terminated, while if the above operation has not been performed, the process proceeds to step 14e.

In step 14e, the path following timer Ti
It is determined whether or not the count value of 2 has reached the short period Tb. If the count value of the path following timer Ti2 has not reached the short cycle Tb, the process proceeds to step 14c. On the other hand, when the count value of the path following timer Ti2 has reached the short period Tb, the process proceeds to step 14f.
In step 14f, the counting is started after resetting the path following timer Ti2, and the process proceeds to step 14g.

In step 14g, the searcher 16a is controlled to execute the path following processing B3. The path follow-up processing B3 follows the fluctuating timing of up to m despread timings T1 to Tm stored in the storage unit 200.

First, the despreading timings T1 to Tm stored in the storage unit 200 are read out, and a path search is performed in each of the ± N chip sections centered on the despreading timings T1 to Tm. A path suitable for reception is detected from a section of ± N chips for each of the paths from Tm to Tm, new despread timings T1 to Tm corresponding to the paths are obtained, and these timings are recorded in the storage unit 200.

However, at this time, the despreading timing to which the identification information is added, that is, the despreading timing corresponding to the path having the highest received power level in the path detection processing A3 is centered on the despreading timing. The path tracking is performed by performing a path search on the ± N chips with the density α. As for the remaining paths, ± N chips centered on the despread timing corresponding to each path are assigned a density β (>
Perform path search by performing a path search in α).

Then, of the plurality of paths detected in this way, the despreading timings corresponding to the three higher-order paths suitable for reception having a higher reception power level are determined by:
Assigned to the fingers 16b, 16c, 16d, and proceed to step 14c.

Thus, the fingers 16b, 16c, 1
Reference numeral 6d despreads the digital signal from the A / D converter 15e at despread timings corresponding to the upper three paths suitable for reception.

As described above, in the mobile radio terminal having the above configuration, as the path detection processing A3, a normal path search over one symbol section is performed every time the long period Ta elapses, and a path suitable for reception is detected. After that, every time a short period Tb shorter than the long period Ta elapses, as a path follow-up process B3, a de-spreading timing centered on the despread timing corresponding to the path detected by the path search is performed.
A path search is performed for N chips, and processing for detecting a path suitable for reception is performed.

In the path following process B3, for the path having the highest received power level, a path search is performed by searching for ± N chips centered on the despread timing corresponding to this path with the density α. On the other hand, for the remaining paths, path tracking is performed by performing a path search of ± N chips centered on the despread timing corresponding to each path with a density β (> α).

Therefore, according to the mobile radio terminal having the above configuration, the accuracy of path following is varied according to the reception power level of the path suitable for reception, so that the number of data processing is reduced and the efficiency is improved. A path suitable for reception can be detected well, and the calculation load of the path detection processing can be reduced without lowering reception characteristics.

Note that the present invention is not limited to the above embodiment. For example, in the above embodiment, only the path having the highest received power level is followed by the path with a low density α. Alternatively, for example, a path having a received power level equal to or higher than a preset threshold Pth may be used. About, follow the path at a low density α,
The remaining paths may be followed at a high density β.

As in the first embodiment, the speed detecting circuit 18 shown in FIG. 5 is provided to change the value of the following window width N in the path following process B3 according to the speed detected by the speed detecting circuit 18. You may make it. With such a configuration, the following window width N can be varied according to the moving speed, and the calculation load of the path detection processing can be reduced more efficiently.

Further, similarly to the first embodiment, as shown in FIG. 7, the path search control means 100d changes the value of the tracking window width N according to the reception power level of each path, and It is also possible to carry out the process B3.

According to this, since the follow-up window width N is varied according to the reception power level of the path, it is possible to focus on the path suitable for reception and reduce the calculation load of the path detection processing more efficiently. .

In the above description, the path following processing B
In each of the processes B1, B21, B22, and B3, the following description has been made on the assumption that the tracking window N is set around the despread timings T1 to Tm corresponding to the paths suitable for reception. However, the present invention is not limited to this. It is not always necessary to be the center. It goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0131]

As described above, according to the present invention, a digitized received signal of, for example, one symbol period (256 chips) is sequentially despread starting from the timing corresponding to each chip, and the result of the despread result is obtained. A path detection process for detecting a plurality of paths suitable for performing rake reception based on the correlation level, and a predetermined number of continuous (chip) timings based on despreading timings corresponding to the paths detected in the path detection process, respectively. A path follow-up process of despreading the digitized received signal and detecting a path suitable for reception from the correlation level of the despread result is selectively performed by the control of the selection means.

Therefore, according to the present invention, the number of data processes in the path following process can be set to be significantly smaller than the number of data processes in the path detection process by setting the above-mentioned predetermined number. Compared with the case of repeatedly executing only a path suitable for reception, the number of data processing can be reduced efficiently, and
Since the path detection processing and the path follow-up processing are selectively performed, a mobile radio terminal that does not cause deterioration in reception quality can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration of a first embodiment of a mobile radio terminal according to the present invention.

FIG. 2 is a view for explaining a path detection operation of the mobile radio terminal shown in FIG. 1;

FIG. 3 is a flowchart for explaining a path detection operation of the mobile wireless terminal shown in FIG. 1;

FIG. 4 is a diagram for comparing a data processing amount of the mobile radio terminal shown in FIG. 1 with a conventional mobile radio terminal in a path detection operation.

FIG. 5 is a circuit block diagram showing a configuration of a modification of the mobile radio terminal shown in FIG.

FIG. 6 is a flowchart for explaining a path detection operation of the mobile wireless terminal shown in FIG. 5;

FIG. 7 is an exemplary view for explaining a path detection operation of the mobile radio terminal shown in FIG. 5;

FIG. 8 is a circuit block diagram showing a configuration of a second embodiment of the mobile radio terminal according to the present invention.

FIG. 9 is a diagram for explaining a path detection operation of the mobile wireless terminal shown in FIG. 8;

FIG. 10 is a flowchart for explaining a path detection operation of the mobile wireless terminal shown in FIG. 8;

FIG. 11 is a view for explaining a path detection operation of the mobile radio terminal shown in FIG. 8;

FIG. 12 is a circuit block diagram showing a configuration of a third embodiment of the mobile radio terminal according to the present invention.

FIG. 13 is a view for explaining a path detection operation of the mobile wireless terminal shown in FIG. 12;

FIG. 14 is a flowchart for explaining a path detection operation of the mobile wireless terminal shown in FIG. 12;

FIG. 15 is a flowchart for explaining a path detection operation of a conventional mobile radio terminal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Duplexer 12 ... Transmitting device 13 ... Receiving device 14 ... Wireless circuit 14a ... Attenuator 14b ... Amplifier 14c ... Mixer 14d ... Frequency synthesizer 15 ... Intermediate frequency circuit 15a ... Amplifier 15b ... Bandpass filter (BPF) 15c ... Mixer 15d ... Frequency synthesizer 15e ... A / D converter (A / D) 16 ... Receiver 16a ... Searcher 16b, 16c, 16d ... Finger 16e ... Symbol synthesizer 17 ... Signal processing unit 18 ... Speed detection circuit 100 ... Control unit 100a 100b, 100c, 100d: path search control means 200: storage unit

Claims (7)

[Claims] 1. A mobile radio terminal used in a mobile communication system using a direct spread-spread spectrum system as a communication system, a digital conversion means for converting a received signal into a digital signal, and a digital signal obtained by the digital conversion means. Are sequentially despread from a timing based on the chip rate over a predetermined period, and a plurality of paths suitable for performing rake reception are detected based on the correlation level of the despread result. Starting from a predetermined number of consecutive chip timings based on the despreading timing corresponding to the detected path, respectively, the digital signal obtained by the digital conversion means is despread, and from the correlation level of the despread result, it is suitable for reception. Path following means for performing a path following process for detecting a path; Mobile radio terminal characterized by comprising a control means for scan detecting means and said path tracking means selectively operated. 2. The apparatus according to claim 1, further comprising: priority setting means for setting a priority to each of the paths detected by the path detecting means according to a correlation level of the paths detected by the path detecting means. 2. The mobile radio terminal according to claim 1, wherein the path follow-up process for the path detected by the path detection unit is performed at a frequency corresponding to the priority set by the priority setting unit. 3. The mobile radio terminal according to claim 2, wherein the priority setting unit sets a low priority for the path used for the rake reception. 4. A mobile radio terminal used in a mobile communication system using a direct spread / spread spectrum system as a communication system, a digital conversion means for converting a received signal into a digital signal, and a digital signal obtained by the digital conversion means. Are sequentially despread from a timing based on the chip rate over a predetermined period, and a plurality of paths suitable for performing rake reception are detected based on the correlation level of the despread result. Starting from a predetermined number of consecutive timings based on the despreading timing corresponding to the detected path, the digital signal obtained by the digital conversion means is despread, and a path suitable for reception is obtained from the correlation level of the despread result. Path following means for performing a path following process for detecting Means and control means for selectively operating the path following means, and timing density setting means for varying the density of the predetermined number of consecutive timings according to the correlation level of the path detected by the path detecting means. A mobile wireless terminal, comprising: 5. A mobile radio terminal used in a mobile communication system using a direct spread-spread spectrum system as a communication system, a digital conversion means for converting a received signal into a digital signal, and a digital signal obtained by the digital conversion means. Are sequentially despread from a timing based on the chip rate over a predetermined period, and a plurality of paths suitable for performing rake reception are detected based on the correlation level of the despread result. Starting from a predetermined number of consecutive timings based on the despreading timing corresponding to the detected path, the digital signal obtained by the digital conversion means is despread, and a path suitable for reception is obtained from the correlation level of the despread result. Path following means for performing a path following process for detecting According to the correlation level of the path detected by means a mobile radio terminal, characterized in that the density of successive timing of the predetermined number; and a timing density setting means for variably. 6. A speed detecting means for detecting a speed, wherein the path following means performs the path following process by changing the predetermined number in accordance with the speed detected by the speed detecting means. The mobile radio terminal according to any one of claims 1 to 5, wherein: 7. The apparatus according to claim 1, wherein the path following means performs the path following processing by changing the predetermined number according to a correlation level of the path detected by the path detecting means. The mobile radio terminal according to claim 5.