JP2003298472A - Mobile wireless terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized mobile wireless terminal with low power consumption in which the size of a RAM used for managing a path table can be reduced. <P>SOLUTION: A control section 100 which performs integrates control of each section of the mobile wireless terminal, is provided with a path search control means 100a and makes the control means control a searcher 16a to execute path searching and detect a path suitable for reception by each cell. Then the path search control means 100a applies processing of converting absolute value information to identify the detected path into relative value information and stores the resulting information to a storage section 200. Then the control section 100 reads the path information from the storage section 200 as required and assigns a received path to each of fingers 16b, 16c, and 16d on the basis of the information. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a CDMA (Code
The present invention relates to a mobile wireless terminal device that performs wireless communication by a division multiple access (SDM) method.

[0002]

2. Description of the Related Art In recent years, affinity for multimedia transmission,
In addition, as the demand for high-speed and high-capacity transmission increases, CDMA mobile radio communication systems are being researched and developed for practical use.

Soft handoff is one of the elemental technologies necessary for realizing the CDMA mobile radio communication system. This is a technology that enables line switching that occurs as a mobile terminal moves without instantaneous interruption.

Further, RAKE reception is an important elemental technology for realizing a CDMA mobile radio communication system. This is a technique for separating and synthesizing multipath components included in a received signal by using a code sequence having high autocorrelation.

Then, the soft handoff and RAKE
In order to realize reception, the mobile terminal needs to periodically detect a path with the base station and hold information on the detected path.

Many path detection methods have been proposed in the past, but in general, they are detected by a process of obtaining a correlation between a scramble code sequence and a received signal, which are previously agreed by the transmitting side and the receiving side. it can.

In this case, the detected path information is:
It can be expressed by despreading timing indicating the time when the received signal is despread using the scramble code, and the correlation power value between the scramble code and the received signal obtained by this despreading.

By the way, FIG. 7 shows a result obtained by performing a path search when the mobile terminal moves from the cell C1 to the cell C2 in a propagation environment in which two cells C1 and C2 exist around the mobile terminal. It is a time series showing the correlation level (power) of the generated multipath.

Generally, the correlation value level of a path effective in RAKE combining among a plurality of multipaths received from one cell follows a long-term fluctuation component of power proportional to the distance between the mobile terminal and the cell. To be distributed. The broken line in FIG. 7 indicates the average power of the multipath from the cell C1, and the alternate long and short dash line indicates the average power of the multipath from the cell C2.

As shown in this figure, looking at the multipath correlation value of the cell C1, the absolute average value of the correlation values greatly differs between the measurement value at time t1 and the measurement value at time t3.
It is considered that the relative power difference between multipaths tends to be relatively small.

FIG. 8 shows an example of the distribution of the despread timing and the correlation power of the paths P1 to P5 obtained as a result of the path search performed by the mobile terminal for a certain base station.

In the example of FIG. 8, paths P1 to P5 detected for a certain base station are {T1, T2, T3, T, respectively.
4, T5}, the correlation power values {A1, A2, A3, A4, A5} are detected.

The information of the path thus detected is
It is recorded in the RAM in the mobile terminal as a path table.
Since the path to the base station fluctuates according to the environmental conditions around the mobile terminal, it is necessary to periodically detect the path and update the path table.

The detection range and accuracy of the correlation power value and the occurrence time are determined by the standard of wireless communication, and for example, W-CDMA (Wideba) which is a candidate for the next generation mobile communication.
In the nd Code Division Multiple Access) method, it is necessary to detect the power in 90 dB width in 0.5 dB units.

On the other hand, it is necessary to detect the occurrence time in units of one chip with a width of 0 to 38400 chips.
Further, it is necessary to hold a maximum of 32 cells for one frequency in the path table of the peripheral base stations.

However, in the conventional path table management method as described above, a large number of RAM areas are required because the absolute value (Dold in FIG. 7) of the correlation power value of each path is held in the RAM area. There was a problem.

[0017]

In the conventional mobile radio terminal device, a large number of RAM areas are required because the absolute value of the correlation power value of each path is held in the RAM area as a path table. there were.

The present invention has been made to solve the above problems, and it is possible to provide a mobile radio terminal device which is capable of reducing the RAM size used for managing a path table and is small in size and low in power consumption. To aim.

[0019]

In order to achieve the above object, the present invention uses a code spread received signal in a mobile radio terminal apparatus that performs radio communication by a CDMA system by using various code sequences. Despread at various timings to obtain the correlation level between the received signal and the code sequence,
As a result, the path detection means for detecting a plurality of paths suitable for reception, and the despreading timing information corresponding to the plurality of paths detected by the path detection means, respectively Corresponding to any one of the plurality of paths, the first conversion means for converting the information into relative information based on the timing of diffusion and the information of the correlation level respectively corresponding to the plurality of paths detected by the path detection means. Second conversion means for converting the correlation level into relative information, reference timing information obtained by the first conversion means, reference timing information, and second conversion means The storage means for storing the relative correlation level information and the reference correlation level information in association with a plurality of paths respectively, and the timing information and the correlation level stored in the storage means. Based on the Le information were to be configured by including a receiving means for receiving a path suitable for reception.

In the mobile radio terminal apparatus having the above-mentioned configuration, the information of the despreading timing and the correlation level thereof are detected as the information of the path which is the candidate for reception, and this is converted into a relative value and recorded in the storage means. A path suitable for reception is selected and received based on the information stored in this storage means.

Therefore, according to the mobile radio terminal device having the above-mentioned configuration, the information converted from the absolute value to the relative value is recorded in the storage means, so that the data can be significantly larger than the case where the absolute value is recorded. Since the amount is reduced, the storage capacity of the storage means can be reduced, which contributes to downsizing and low power consumption.

[0022]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a CDMA mobile radio terminal according to an embodiment of the present invention. In particular, the receiving system according to the present invention will be mainly described here.

In the transmitter 12, the transmission data such as digitized voice and data is modulated by a digital modulation method such as PSK modulation, and the modulated data is spread by using a spreading code to obtain a wide band base. Convert to band signal.

Then, the transmitter 12 up-converts the spread base band signal into a radio frequency signal and inputs it to the antenna 10 through the duplexer 11. The input radio frequency signal is transmitted to the antenna 10
It is radiated 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 includes a wireless circuit 14, an intermediate frequency circuit 15, and a 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 preset amount. The signal passing through the attenuator 14a is amplified to a predetermined level by the amplifier 14b, then mixed by the mixer 14c with the local oscillation signal generated by the frequency synthesizer 14d, and down-converted to an intermediate frequency.

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

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

This baseband signal is converted into a digital signal by an A / D converter (A / D) 15e and Ra
It is input to the ke receiver 16. The sampling rate in the A / D converter 15e is set to a frequency that is several times higher than 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 fingers 16b, 16c, 16d, respectively.

The searcher 16a is provided with a plurality of correlators, and in accordance with an instruction from the control unit 100, despreading in which the correlator is used to multiply the digital signal with various spreading codes at various timings. By performing the processing, a plurality of paths suitable for receiving the signal transmitted from the base station to the own terminal are detected from the despreading result.

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

The fingers 16b, 16c and 16d are despreading timings and spreading codes assigned by the control unit 100, and perform despreading processing on the digital signals. Each of them has a DLL (Delay locked Loop) function and spreads. It is possible to automatically correct a reception timing error of about ± 1 chip.

The symbol combiner 16e includes a finger 16
The symbols of the multipath obtained by the despreading processing of b, 16c, and 16d are assigned to the fingers 16b, 16c, and 16b, respectively.
Symbol combination is performed in consideration of the despreading timing assigned to d.

The signal combined by the symbol combiner 16e is demodulated by the signal processor 17 in the subsequent stage to correspond to the digital modulation on the transmitting side, and the received data is reproduced.

The control unit 100 includes a CPU, ROM and R
The CPU has an AM and the like, and the CPU has the RO
In accordance with a control program and control data stored in M, each unit of the mobile radio terminal device is centrally controlled.

The control section 100 is also provided with a path search control means 100a, which controls the searcher 16a to carry out a path search to detect a path suitable for reception for each cell.

Then, the path search control means 100a is
The path information for identifying the detected path is subjected to a predetermined conversion process and recorded in the storage unit 200, the control unit 100 reads out the path information from the storage unit 200 as necessary, and based on this, Each finger 16b, 16c, 16
The received path is assigned to d.

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 the user, and also the path search control means 100a. The path search control means 100a has a path table for storing the path information obtained by the path search control by the.

Although not shown in FIG. 1, as a component of the present apparatus, there is a power supply unit having a battery which supplies electric power for operating the above-mentioned units and which can be repeatedly charged and discharged.

Next, the path search operation of the mobile radio terminal having the above configuration will be described. FIG. 2 is a flowchart illustrating the operation of the path search control performed by the path search control means 100a.

First, in step 2a, the searcher 16a
Control is performed to detect a path suitable for reception for each cell, and the process proceeds to step 2b. In the following explanation,
The case where the paths P1 to P5 shown in FIG. 3 are detected will be described as an example.

In step 2b, the path information of the paths P1 to P5 detected in step 2a is temporarily recorded in the work area of the storage unit 200, and the process proceeds to step 2c. The path information includes the type of scramble code sequence used for despreading, time information indicating the reception timing of the path, and a power value indicating the correlation level thereof.

In step 2c, a process of converting the correlation level from an absolute value to a relative value in the path information recorded in the work area of the storage unit 200 in step 2b is performed, and the process proceeds to step 2d. Note that this processing will be described in detail later.

In step 2d, a process of converting the reception timing from the absolute value to the relative value in the path information recorded in the work area of the storage unit 200 in step 2b is executed.
The process ends. Note that this processing will be described in detail later.

Next, referring to FIG. 4, the above step 2c
The conversion processing of the correlation level performed in 1 will be described.
FIG. 4 is a flowchart for explaining this processing.

First, in step 4a, the correlation level A1 of the paths P1 to P5 recorded in the work area of the storage unit 200.
Among A5 to A5, the path having the maximum correlation level is detected, and the process proceeds to step 4b. In the example of FIG. 3, the correlation level A1 of the path P1 is the maximum.

In step 4b, the correlation levels A1 to A5 of the paths P1 to P5 recorded in the work area of the storage unit 200.
Among them, the path having the minimum correlation level is detected, and the process proceeds to step 4c. In the example of FIG. 3, the correlation level A4 of the path P4 is the minimum.

At step 4c, the average value α of the correlation level (A1) of the path detected at step 4a and the correlation level (A4) of the path detected at step 4b is obtained, and the routine proceeds to step 4d.

In step 4d, the average value α obtained in step 4c and the correlation levels A1 to A5 of the paths P1 to P5 are set.
Of the correlation level a
1, a2, a3, a4, and a5, the paths P1 to
The correlation levels A1 to A5 of P5 are converted into relative values with respect to the average value α, and the process proceeds to step 4e.

In step 4e, the correlation levels a1, a2, a3, a4, a5 obtained in step 4d are recorded in the path table in association with the corresponding path identification information, and the process ends.

Next, referring to FIG. 5, the above step 2d
The conversion processing of the timing information performed in 1 will be described. FIG. 5 is a flowchart for explaining this processing.

First, in step 5a, it is shown that the timing is the earliest among the timing information T1 to T5 of the paths P1 to P5 recorded in the work area of the storage unit 200.
The timing information of the minimum value is detected, and this is used as the reference timing τ, and the process proceeds to step 5b. In the example of FIG. 3, the timing information T1 of the path P1 becomes the reference timing τ.

In step 5b, the reference timing τ (= T1) detected in step 5a and the timings T2 to T5 of the respective paths P2 to P5 other than the path P1 at this timing.
And the timing information t2 to t is newly added.
5, the timing information T of each of the paths P2 to P5 is set.
2 to T5 are converted into a relative value with respect to the reference timing τ, and the process proceeds to step 5c.

In step 5c, the timing information T1 (= τ) detected in step 5a and the timing information t2 to t5 obtained in step 5b are recorded in the path table in association with the corresponding path identification information. The process ends.

Next, referring to FIG. 6, the fingers 16b.about.
A process of allocating the received path in 16d will be described. FIG. 6 is a flowchart for explaining this processing, which is executed by the control unit 100 as needed.

First, in step 6a, the path table of the storage unit 200 is referred to detect the paths to be assigned to the fingers 16b to 16d, and the process proceeds to step 6b. In addition,
Here, a path having a high correlation level is detected as a path to be preferentially received, excluding the paths at the reception timings already received by the fingers 16b to 16d.

In step 6b, the timing information corresponding to the path detected in step 6a is detected, and the fingers 16b to 16d, which need to change the reception path, are notified,
The process ends. Thereby, the fingers 16b to 16d to which the timing information is newly notified receive the path based on the notified timing information.

If the detected path has a relative value in step 6b, it is added to the reference timing τ of the same cell to convert the timing information into an absolute value, and the finger 1
Notify 6b to 16d.

As described above, in the mobile radio terminal device having the above configuration, when the path information suitable for reception is held in the path table, the path information is converted from absolute value information to relative value information. I try to record it.

That is, as shown in FIG. 7, for example, even if the result of the path search fluctuates with the movement of the mobile radio terminal device, conventionally, the storage unit 200 can hold information of about Dold [dB]. However, in the mobile wireless terminal device having the above configuration, the RAM area of the storage unit 200 is secured so as to hold information of about Dnew [dB] of the power detection window (w1-w2). do it.

Therefore, according to the mobile radio terminal apparatus having the above configuration, the correlation level of each path can be expressed by a small value,
In addition, in the time information indicating the reception timing, the delay dispersion of the multipath of each cell can be expressed as 1/1000 to 1/10000 with respect to the detection range of the absolute time. Therefore, the storage unit 200 required by the path table
The capacity of the RAM area can be remarkably reduced, which contributes to downsizing and low power consumption of the device.

The present invention is not limited to the above embodiment. For example, in a CDMA mobile radio communication system, a base station may perform transmission power control for controlling the transmission power level based on a report of the reception power level from a mobile radio terminal.

Conventionally, the absolute value of the received power level is reported, but instead of this, for example, searcher 1
The received power level of the pilot signal detected in 6a is
The control unit 100 may convert the value into a relative value based on a certain reference value, and report this value to the base station via the transmission device 12.

According to this, not only the capacity of the storage unit 200 required to hold the detected received power level can be reduced, but also the amount of information when reporting to the base station is reduced.

Needless to say, the present invention can be similarly implemented even if various modifications are made without departing from the scope of the present invention.

[0067]

As described above, according to the present invention, the information of the despreading timing and its correlation level are detected as the information of the path which is the candidate for reception, and this is converted into a relative value and stored in the storage means. The data is recorded, and a path suitable for reception is selected based on the information stored in the storage means to receive the data.

Therefore, according to the present invention, since the information converted from the absolute value to the relative value is recorded in the storage means, the data amount is significantly reduced as compared with the case where the absolute value is recorded. Therefore, it is possible to provide a mobile wireless terminal device capable of reducing the storage capacity of the storage means and reducing the size and power consumption.

[Brief description of drawings]

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

FIG. 2 is a flowchart for explaining an operation of path search control of the mobile radio terminal device shown in FIG.

FIG. 3 is a diagram showing an example of a path detected by the processing shown in FIG.

FIG. 4 is a flowchart illustrating a correlation level conversion process of the process shown in FIG.

5 is a flowchart illustrating a conversion process of timing information of the process shown in FIG.

FIG. 6 is a flowchart illustrating processing for assigning a path detected by the processing shown in FIG. 2 to a finger.

FIG. 7 is a diagram showing a temporal change of a path search result when two cells exist around a mobile radio terminal device.

FIG. 8 is a diagram for explaining path search control by a conventional mobile wireless terminal device.

[Explanation of symbols]

10 ... Antenna 11 ... Sharer 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 ... Fingers 16e ... Symbol synthesizer 17 ... Signal processing unit 100 ... Control unit 100a ... Path search control means 200 ... Storage unit

Claims (3)

[Claims] 1. A CDMA (Code Division Multiple Acc)
In a mobile wireless terminal device that performs wireless communication by the ess) method, a code-spread reception signal is despread at various timings using various code sequences, and a correlation level between the reception signal and the code sequence is calculated. Obtained from this, path detection means for detecting a plurality of paths suitable for reception, and despreading timing information respectively corresponding to the plurality of paths detected by the path detection means, to any of the plurality of paths. Conversion means for converting corresponding despreading timing into relative information based on reference, and relative timing information obtained by this conversion means,
It is characterized by comprising storage means for storing reference timing information, and reception means for selecting a path suitable for reception based on the timing information stored in this storage means and performing reception. Mobile wireless terminal device. 2. A CDMA (Code Division Multiple Acc)
In a mobile wireless terminal device that performs wireless communication by the ess) method, a code-spread reception signal is despread at various timings using various code sequences, and a correlation level between the reception signal and the code sequence is calculated. Obtained from this, path detection means for detecting a plurality of paths suitable for reception, and despreading timing information respectively corresponding to the plurality of paths detected by the path detection means, to any of the plurality of paths. First conversion means for converting relative information based on the corresponding despreading timing, and correlation level information respectively corresponding to the plurality of paths detected by the path detection means, Second conversion means for converting the correlation level corresponding to either one into relative information, and the relative timing information obtained by the first conversion means and the reference timing. And a storage unit that stores the information of the relative level obtained by the second conversion unit and the information of the reference correlation level in association with each of the plurality of paths. A mobile radio terminal device, comprising: a receiving unit that selects a path suitable for reception based on the stored timing information and correlation level information and performs reception. 3. The second conversion means uses information of correlation levels respectively corresponding to the plurality of paths detected by the path detection means as a minimum correlation level and a maximum correlation level of the plurality of paths. The mobile radio terminal device according to claim 2, wherein the mobile radio terminal device is converted into relative information based on an average value of the.