JP2002077102A - Base-station equipment and method for radio communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To receive an RACH preamble by reducing the quantity of operation. SOLUTION: The results of correlative operation by means of a matched filter 1071 are outputted to a mean value calculating circuit 1072 and the circuit 1072 calculates the mean value of the results and transmits the mean value to a RACH preamble detecting circuit 1073 which detects the RACH preamble. When the circuit 1073 detects the RACH preamble (for example, when the mean value exceeds or reaches a prescribed threshold), the circuit 1073 outputs a control signal indicating the detection of the preamble to the mean value calculating circuit 1072.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital radio communication system, and more particularly to a W-CDMA (Wideband-Code Division).
The present invention relates to a base station device and a wireless communication method used in Multiple Access).

[0002]

2. Description of the Related Art Conventionally, a random access channel (RACH) is used for transmitting an uplink signal in call origination of a communication terminal such as a mobile station and packet transmission with a small transmission amount. In this RACH, for example, after transmitting a preamble portion (known signal) having a length of about 4096 chips once or a plurality of times and receiving a transmission permission from a base station, for example, a message having a length of about 10 ms is obtained. Part is to be sent.

[0003] The success or failure of the reception of the base station in the preamble portion of the RACH is notified to the communication terminal by the presence or absence of transmission of the downlink AICH. That is, the communication terminal transmits the preamble portion to the base station on the RACH, for example, at the time of calling, and upon receiving the preamble portion, immediately transmits a control signal for confirmation to the communication terminal by AICH. If reception is not possible, transmission of AICH is not performed. AICH corresponding to own preamble part
Is not received within the specified time, the communication terminal generally increases the transmission power and transmits the pull amble portion again. As described above, until the AICH is received, after transmitting the preamble portion a plurality of times, the communication terminal:
The message part is transmitted to the base station by RACH.

[0004] The operation of the base station receiving the preamble portion of the RACH will be described with reference to FIG. When the base station receives the preamble portion of the RACH, the matched filter 601 performs despreading processing on the preamble portion transmitted from the communication terminal using the RACH preamble code (replica signal). The output (correlation value) of the matched filter (MF) 601 is input to the delay profile creation circuit 602. The delay profile creation circuit 602 creates a delay profile using the input correlation value. Despread timing is obtained from the created delay profile.

The delay profile created by the delay profile creation circuit 602 is sent to the level detection circuit 603. The level detection circuit 603 detects the level of the correlation peak from the delay profile, and outputs information of the detected level to the RACH preamble detection circuit 604. R
The ACH preamble detection circuit 604 detects the RACH preamble based on the result of the level detection. For example, if the detection level is equal to or higher than a set threshold, it is determined that the RACH preamble has been received.

[0006]

SUMMARY OF THE INVENTION As described above, RACH
When detecting the level based on the correlation value between the received signal (the RACH preamble portion from the communication terminal) and the RACH preamble code in the reception of the preamble portion, the correlation value is determined over a predetermined period, and the correlation value is determined for a predetermined period. And store the correlation value in the memory.
The maximum value of the integration result is detected. However, when a correlation value is obtained over a predetermined period and the correlation values are integrated, there is a problem that the amount of calculation increases and the load on the device increases.

[0007] The present invention has been made in view of the above points, and has as its object to provide a base station apparatus and a radio communication method capable of receiving a RACH preamble with a reduced amount of calculation.

[0008]

According to the present invention, there is provided a base station apparatus comprising:
Average value calculation means for averaging a correlation operation result between a known signal in the random access channel signal from the communication terminal and the replica signal of the known signal to obtain an average value,
Detecting means for detecting reception of a known signal of a random access channel signal using the average value.

According to this configuration, the result of the correlation operation between the received signal and the RACH preamble code is averaged, and the RACH preamble is detected using the average value.
For this reason, the amount of calculation can be reduced as compared with the conventional method in which a correlation value is obtained over a predetermined period, the correlation value is integrated, and the RACH preamble is detected using the maximum value.

The radio communication method according to the present invention comprises: an average value calculating step of averaging a correlation operation result between a known signal in a random access channel signal from a communication terminal and a replica signal of the known signal to obtain an average value; Detecting a reception of a known random access channel signal using the average value.

According to this method, the result of the correlation operation between the received signal and the RACH preamble code is averaged, and the RACH preamble is detected using the average value.
For this reason, the amount of calculation can be reduced as compared with the conventional method in which a correlation value is obtained over a predetermined period, the correlation value is integrated, and the RACH preamble is detected using the maximum value.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention is that a received signal and RA
This is to average the result of the correlation operation with the CH preamble code, detect the RACH preamble using the average value, and receive the RACH preamble with a reduced amount of calculation.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, R
In the case of receiving the preamble portion of ACH, a case will be described where the correlation value between the RACH preamble portion and the RACH preamble code from the communication terminal is averaged, and the RACH preamble is detected based on the average value.

In FIG. 1, only the reception sequence is shown and the transmission sequence is omitted. Although only one sequence is shown for the received sequence, two or more sequences may be provided.

FIG. 1 is a block diagram showing a configuration of a base station apparatus according to Embodiment 1 of the present invention. Antenna 101
The uplink signal received via the wireless communication circuit is input to the wireless reception circuit 102. In the wireless receiving circuit 102,
Predetermined wireless reception processing (down conversion, A / D conversion, etc.) is performed on the received signal. Thus, the received signal becomes a baseband signal.

The baseband signal is supplied to a despreading circuit 10
In 3, the despreading process is performed using the spreading code used in the spreading modulation process in the communication terminal that is the communication partner. The result of the despreading process is output to RAKE combining circuit 104 and to channel estimation circuit 105.

The channel estimation circuit 105 performs channel estimation based on a known signal (for example, a pilot signal) included in the received signal, and compares the channel estimation result with RAKE.
Output to the synthesis circuit 104. RAKE combining circuit 104 uses the result of despreading from despreading circuit 103 and the result of channel estimation from channel estimating circuit 105 to make RAKE
The combined signal is output to the determination circuit 106. The determination circuit 106 determines the combined signal to obtain a received signal.

For receiving the RACH preamble portion, the baseband signal is output to the RACH preamble searcher 107. The number of RACH preamble searchers 107 is equal to the number of preamble patterns. Therefore, a different R is added to the matched filter 1071 of each searcher 107 for RACH preamble.
The ACH preamble code is input.

In searcher 107 for RACH preamble, RACH preamble part in the received signal and RACH preamble part
The average value of the correlation value is obtained from the correlation value with the preamble code, and the RACH preamble is detected based on the average value.

The RA in the base station apparatus having the above configuration
The receiving operation of the CH preamble part will be described. In RACH transmission from a communication terminal, transmission is performed with a configuration as shown in FIG. Then, the communication terminal transmits the preamble portion and the message portion of the RACH to the base station device at the timing shown in FIG.

In FIG. 3, a predetermined number of uplink access slots, for example, # 0 to # 14 as shown in FIG. 4, are defined. For each access slot, as shown in FIG. Different offsets are given. Which access slot is valid in the cell to which the communication terminal belongs is broadcast on a broadcast channel.
Therefore, the communication terminal considers the offset corresponding to the broadcasted access slot, and sets the RA at that timing.
CH transmission will be performed.

When the base station apparatus according to the present invention receives the preamble portion of the RACH transmitted from the communication terminal,
The preamble portion of the ACH is sent to the RACH preamble searcher 107.

In the searcher 107 for RACH preamble, a matched filter (MF) 1071 performs a correlation operation between the preamble portion of the RACH and a known RACH preamble code, and outputs the result of the correlation operation to the average value calculation circuit 1072. The average value calculation circuit 1072 averages the result of the correlation operation for a predetermined period, for example, on a slot basis, and calculates the averaged result, that is, the average value in the RACH.
Output to the preamble detection circuit 1073.

In RACH preamble detection circuit 1073, the R value is calculated based on the average value from average value calculation circuit 1072.
Detect ACH preamble. For example, when the average value is equal to or larger than a set threshold value, it is determined that the RACH preamble has been received. In this case, the RACH preamble detection circuit 1073 determines whether or not the RACH preamble has been received in the period (for example, slot) for the average value of the correlation operation result in the predetermined period output from the average value calculation circuit 1072.

That is, the result of the correlation operation in the matched filter 1071 is output to the average value calculation circuit 1072, the average value is calculated by the average value calculation circuit 1072, and the average value is sent to the RACH preamble detection circuit 1073, where the RACH Preamble detection is performed. More specifically, RA is determined by determining a threshold value for the average value.
The CH preamble is detected.

The RACH preamble detection circuit 1073 detects when a RACH preamble is detected (for example,
When the average value exceeds a predetermined threshold value or reaches a predetermined threshold value), a control signal indicating that fact is output to the average value calculation circuit 1072.

On the other hand, the RACH preamble detection circuit 10
73, when the RACH preamble is not detected (for example, when the average value does not reach the predetermined threshold),
No control signal is output to the average value calculation circuit 1072. Then, the average value calculation circuit 1072 continues the averaging process (average value calculation) of the correlation operation result.

As described above, in the base station apparatus according to the present embodiment, the result of the correlation operation between the received signal and the RACH preamble code is averaged, and the RAC is calculated using the average value.
The H preamble is detected. For this reason, the amount of calculation can be reduced as compared with the conventional method in which a correlation value is obtained over a predetermined period, the correlation value is integrated, and the RACH preamble is detected using the maximum value.

Next, when receiving the message portion of the RACH, the message portion of the RACH is
In 3, despreading processing is performed using the spreading code used in the communication terminal, RAKE combining is performed using the channel estimation result, and the result is determined to become received data.

For demodulation of the RACH message portion, it is also possible to use the despreading timing obtained by the RACH preamble searcher 107.
That is, R of the RACH preamble searcher 107
The despreading circuit 103 uses the despreading timing output from the ACH preamble detection circuit 1073. As a result, it is not necessary for the demodulation circuit to detect the despread timing, and the processing amount can be reduced.

[0031]

As described above, the base station apparatus and the radio communication method of the present invention average the correlation calculation result between the received signal and the RACH preamble code, and detect the RACH preamble using the average value. Do. For this reason,
The amount of calculation can be reduced as compared with the conventional method in which a correlation value is obtained over a predetermined period, the correlation value is integrated, and the RACH preamble is detected using the maximum value.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a base station apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of RACH transmission.

FIG. 3 is a diagram showing transmission / reception timings of RACH and AICH.

FIG. 4 is a diagram for explaining an access slot;

FIG. 5 is a diagram for explaining an offset of an access slot.

FIG. 6 is a block diagram showing a configuration of a conventional RACH preamble searcher.

[Explanation of symbols]

 Reference Signs List 101 antenna 102 radio reception circuit 103 despreading circuit 104 RAKE combining circuit 105 channel estimation circuit 106 determination circuit 107 searcher for RACH preamble 1071 matched filter 1072 average value calculation circuit 1073 RACH preamble detection circuit

Claims (2)

[Claims] An average value calculating means for averaging a correlation operation result between a known signal in a random access channel signal from a communication terminal and a replica signal of the known signal to obtain an average value, and using the average value. A detection unit configured to detect reception of a known signal of a random access channel signal. 2. An average value calculating step of averaging a correlation operation result between a known signal in a random access channel signal from a communication terminal and a replica signal of the known signal to obtain an average value, and using the average value. A detecting step of detecting reception of a known signal of a random access channel signal.