JP2003273780A - Cdm receiver and method for improving reception quality thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transit to the signal of an always optimal coverage by constantly monitoring a receiving state. <P>SOLUTION: A reception quality detection circuit 14 calculates the quality of a received signal at a moment from a Euclidean distance between a transmission signal regulating point and received signal point obtained as the error of a CDM demodulation signal by an error correction circuit 13 and transmits the calculated result to a reception quality parameter deciding circuit 15 to decide a reception quality parameter value by integrating the calculated value of the quality of the received signal for a fixed period. It is outputted to a CDM re-synchronization circuit 17 via a feedback value control 16 to re- synchronize a CDM circuit 12 on the basis of a reception quality parameter value to automatically carry out reception switch to the optimal coverage. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a CDM transmission system.
The present invention relates to a CDM receiving apparatus that employs a (Code Division Multiple) method and that is mainly used in a communication or broadcasting system for mobile units and that receives and demodulates a CDM radio signal and a method for improving the reception quality thereof.

[0002]

2. Description of the Related Art Conventionally, mainly in mobile communication or broadcasting systems, a CDM system using a spread spectrum technique has been used as one of transmission systems. Also, the mobile satellite digital broadcasting system for mobiles, which is currently being developed, has been decided to adopt the CDM method, and its receiving terminal device (hereinafter, CDM receiving device).
Is being developed in parallel.

In the mobile satellite digital broadcasting system, a gap filler (retransmission repeater) is installed in order to enable reception even in a range where the broadcast wave from the satellite does not reach, and the broadcast wave from the satellite is covered by the range. Adopt the method of re-sending to. That is, the CDM receiver on the mobile side receives and demodulates the satellite broadcast wave in the area where the satellite broadcast wave is received, and when the repeat relay wave of the gap filler is received when the radio wave of the satellite broadcast wave becomes weak, The retransmitted relay wave is received and demodulated.

However, in the case of reception via the coverage between the satellite and the gap filler or the coverage between the gap filler and the gap filler, the CDM receiver continues to capture the signal of the coverage with the poor reception signal state and the reception state. A phenomenon occurs in which a signal with good coverage cannot be immediately transitioned, which causes a problem that reception quality is temporarily degraded.

[0005]

As described above, the conventional CDM receiving apparatus continues to capture the signal of the coverage which is poor in the receiving state even though there is another signal of the coverage which is receiving in the good state. Therefore, there arises a problem that the reception quality temporarily deteriorates at the coverage edge.

The present invention has been made in consideration of the above circumstances, and provides a CDM receiving apparatus capable of constantly monitoring the reception state and making a transition to a signal having an optimum coverage and a method of improving the reception quality thereof. The purpose is to

[0007]

In order to achieve the above object, a CDM receiving apparatus according to the present invention has a demodulation means for demodulating a CDM signal from a received signal of the radio signal and an error in the demodulated signal of the demodulation means. Error correction means for making a correction, parameter extraction means for extracting a parameter indicating a reception state from the error correction result obtained by the error correction means, and the demodulation means based on the reception state parameters extracted by the parameter extraction means And a synchronization control means for resetting and resynchronizing.

Further, the method for improving the reception quality of the CDM receiving apparatus according to the present invention extracts the parameter indicating the reception state from the result of the error correction, and the reception state parameter of the control channel with high power is equal to or higher than the specified value (good). , The reception status parameter of the low power information channel is below the specified value (deterioration)
In this case, the demodulation is reset and resynchronized to shift to reception of optimum coverage.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the configuration of a CDM receiving apparatus according to the present invention. A CDM radio signal received by an antenna 10 is received and detected by a tuner 11 and then supplied to a CDM demodulation circuit 12. The CDM demodulation circuit 12 measures the transmission line response characteristic of the input reception signal to obtain an effective path,
The transmission signal is demodulated by performing code despreading and RAKE combining of each path. The demodulated signal is an error correction circuit (FE).
The error correction processing is performed by C) 13 and is output to a reproduction processing system (not shown).

In contrast to the above basic structure, in this embodiment,
The following circuit configuration is added, that is, the reception quality detection circuit 14, the reception quality parameter determination circuit 15, the feedback control circuit 16, and the CDM resynchronization circuit 17.

The reception quality detection circuit 14 calculates the instantaneous reception signal quality from the Euclidean distance between the transmission signal regulation point and the reception signal point, which is obtained as an error in the error correction circuit 13, and the calculation result is the reception quality parameter determination circuit. Transmit to 15. In this reception quality parameter determination circuit 15,
The calculated value of the reception signal quality is integrated for a certain period of time to determine the reception quality parameter value, which is output to the CDM resynchronization circuit 17 via the feedback control circuit 16. The CDM resynchronization circuit 17 uses the CDM circuit 1 based on the reception quality parameter value.
Resync 2

Here, in the reception quality parameter determination circuit 15, the time integration circuit 151 integrates the calculated value of the reception signal quality for a certain period of time to determine the reception quality parameter value, and outputs this determination value. The parameter values thus created are sequentially stored in the parameter storage circuit 152 as a history. Then, the control circuit 153 detects the variation of the reception quality parameter from the storage result of the storage circuit 152, and controls the time integration width of the time integration circuit 151 according to the variation. As a result, it is possible to adaptively select the time until the variation state of the received signal due to the transmission path variation stabilizes.

In the above description, the case where the re-synchronization process by the reception quality parameter is realized by the hardware configuration has been described, but this process can be similarly realized by the software configuration. FIG. 2 shows the processing procedure, which will be described below.

In FIG. 2, first, the Euclidean distances between the transmission signal regulation point and the reception signal point are sequentially acquired from the error correction circuit 13, and the respective instantaneous reception signal qualities are calculated (step S1). Next, it is judged whether or not the integration period is specified (step S2), and if not specified, the initial value is set as the integration period (step S3), and if specified, the specified value is set to the integration period (step S4). ).

After setting the integration period, the received signal quality calculated value is integrated for a set time to determine a received quality parameter value (step S5). The determined reception quality parameter is stored as a history (step S6), and the presence or absence of variation in reception quality is detected from the stored parameter value (step S6).
7). If there is fluctuation, the fluctuation amount is calculated, the corresponding time integration width is obtained, and the value is returned to step S2 as the designated value of the integration period for step S4 (step S2).
8).

On the other hand, the reception quality parameter value determined in step S5 is compared with a specified value (step S9),
If the reception quality parameter value is greater than or equal to the specified value, synchronization is maintained (step S10), and if it is less than the specified value, the CDM
The demodulation circuit 12 is reset and resynchronized (step S11). Hereinafter, the process is repeated from step S1.

As described above, according to the configuration of this embodiment,
Instantaneous reception quality is detected using the error detection result in the error correction process, and the detection result is time-integrated to determine the reception quality parameter. If this parameter value is below the specified value, the CDM demodulation is reset. Then resync. As a result, when the reception quality is degraded at the coverage edge, it is possible to detect this and switch to reception of another good coverage.

In the above embodiment, the resynchronization is controlled by the reception quality of the entire reception channel.
When the radio signal is multiplexed with the information channel and the control channel, even if the parameter value indicating the reception quality of the control channel is greater than or equal to the specified value, the parameter value indicating the reception quality of the information channel is less than or equal to the specified value. Should force a resync. As a result, before the loss of information due to the deterioration of the reception quality of the information channel occurs, another good coverage by resynchronization is set,
It is possible to improve (return) the reception quality.

[0020]

As described above, according to the CDM receiving apparatus of the present invention, there are provided a CDM receiving apparatus capable of constantly monitoring the reception state and making a transition to a signal having optimum coverage and a method of improving the reception quality thereof. Can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a CDM receiving apparatus according to the present invention.

FIG. 2 is a flowchart showing the flow of processing of the above embodiment.

[Explanation of symbols]

10 ... Antenna 11 ... Tuner 12 ... CDM demodulation circuit 13 ... Error correction circuit (FEC) 14 ... Reception quality detection circuit 15 ... Reception quality parameter determination circuit 16 ... Feedback control circuit 17 ... Resynchronization circuit

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5K014 AA01 BA01 FA10 HA10                 5K022 EE02 EE36                 5K067 AA21 CC10 DD44 HH21 HH25

Claims (5)

[Claims] 1. A CDM receiving apparatus for receiving a radio signal according to a CDM (Code Division Multiplexing) transmission system, a demodulation means for demodulating a CDM signal from a received signal of the radio signal, and an error correction for the demodulated signal of the demodulation means. Error correction means to be applied, parameter extraction means for extracting a parameter indicating a reception state from the error correction result applied by the error correction means, and the demodulation means is reset based on the reception state parameters extracted by the parameter extraction means. And a synchronization control means for resynchronizing the CDM receiving apparatus. 2. The reception state parameter extraction means sets the Euclidean distance corresponding to the error between the specified signal point and the reception signal point obtained by the error correction means as the reception state parameter. CDM receiver. 3. A history storage means for storing a history of parameters extracted by the reception state parameter extraction means, and a parameter time integration means for time integration of the reception state parameters extracted by the reception parameter extraction means, And a time integration width control means for controlling a time integration width of the parameter time integration means in accordance with the detected variation of the reception state parameter from the storage result stored by the history storage means. C according to claim 1.
DM receiver. 4. When the radio signal is multiplexed with an information channel and a control channel, the synchronization control means indicates a reset process for the demodulation means and indicates a reception state of the control channel obtained by the parameter extraction means. The CDM receiving apparatus according to claim 1, wherein when the parameter value is equal to or greater than a specified value and the parameter value indicating the reception state of the information channel is equal to or less than the specified value, the CDM receiving apparatus is performed. 5. A CDM receiving apparatus that receives a radio signal according to a CDM (Code Division Multiplexing) transmission method, demodulates the CDM signal, and performs error correction on the demodulated signal to obtain transmission information. The parameter indicating the reception state is extracted from the error correction result, and when the reception state parameter of the control channel with high power is equal to or higher than the specified value and the reception state parameter of the information channel with low power is equal to or lower than the specified value, the demodulation is reset. A method for improving the reception quality of a CDM receiving apparatus, characterized by performing resynchronization to shift to reception of optimum coverage.