JP2002009668A - Communication unit and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication unit that reduces the amount of arithmetic in data detection. SOLUTION: A delay profile is estimated from a received signal. Whether a level of each delay wave with the delay profile is a threshold level or higher is discriminated. A delay profile matrix is generated, with respect to delay waves from the first delay wave until the final delay wave of the delay profile, whose level is discriminated to be the threshold level or higher. Data are detected from the received signal using the delay profile matrix.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device and a detection method for reducing the amount of calculation in data detection.

[0002]

2. Description of the Related Art At present, as a third generation mobile communication system, C
The DMA system is being standardized. The CDMA (Code Division Multiple Access) method of the third generation mobile communication includes:
DS (Direct Sequence), MC (Multi Carrier), TDD
(Time Division Duplex) are considered. Among them, in the TDD system, multi-user detection is used as a detection system to cancel interference in a cell.
Joint detection (Joint Detection) has been proposed as (Multi-user Detection).

The following paper by Anja Klein, "Linear Unbias
sed Data Estimation in Mobile Radio Systems Applyi
ng CDMA ”(IEEE J. Select. Areas Communication, Vo
l. 11 pp. 1058-1066, 1993), an outline of joint detection in CDMA will be described.

Generally, in a mobile communication system, since there are a plurality of propagation paths, a received signal E is expressed by the following equation from a delay profile M of the propagation path and transmission data D. Here, the noise is ignored for the sake of simplicity. E = M × D This equation can be expressed by the following equation using a matrix.
However, the received signal E is E = {e0, e1,..., E2t},
The transmission signal D is D = {d0, d1,..., Dt}.

[0005]

(Equation 1)

Here, m0,..., Mt are a sequence representing the delay profile of the transmission line, and the first column represents each delay time (0, 0, 1).
1, 2, ..., t) represents the received power and phase shift of dt.

In the receiver, the delay profile {m0, m1,..., Mt} of the transmission path is estimated from a pilot signal and the like, and the inverse matrix of the matrix M is multiplied from the left of each term to obtain
Data can be detected.

[0008] Similarly, in the case of a plurality of users, the delay profile of the plurality of users can be expressed by a determinant. By multiplying the inverse matrix from the left, not only the signal of each user can be detected, but also interference between users can be detected. Can be removed.

In this case, the sequence E requires a term corresponding to the time that the delay profile can affect. Also, the determinant M
Is ｛(the number of symbols that can affect the delay profile x spreading factor)
+ Delay time-1} row (number of users x number of symbols that delay profile can affect) column.

[0010] In the case where such detection is performed using joint detection as multi-user detection, in order to detect a delay profile of each user,
For example, a pilot signal is used. For example, in the case of the CDMA system, a delay profile can be detected from the correlation value between the pilot signal and the received signal, and the received data can be easily detected by convolving the correlation value with a spreading code.

FIG. 1 is a block diagram showing a configuration example of a conventional communication device. The communication device illustrated in FIG. 1 includes a delay profile estimating unit 10, a determinant creating unit 20, and a data detecting unit 30. Delay profile estimating section 10 estimates a delay profile from a received signal. Determinant generator 2
0 creates a delay profile matrix from the estimated delay profile (in the case of CDMA, a delay profile matrix is created by convolving the spread code of each symbol with the delay profile). The data detector 30 detects data by multiplying the received signal by the inverse matrix of the created delay profile matrix.

[0012] When detection is performed using joint detection as multi-user detection, the radio base station can detect data of a plurality of users collectively, which is very useful. On the other hand, since the wireless mobile station device detects unnecessary data of other users, the amount of calculation is large, and it is not suitable for downsizing and low power consumption of the mobile device.

FIG. 2 is a diagram showing an example of a delay profile. In the downlink transmitted from the radio base station to the radio mobile station, since the radio base station transmits and the radio mobile station receives, the delay profile in the radio mobile station is common to all users. On the other hand, the delay profile of the uplink transmitted from the wireless mobile station to the wireless base station differs for each wireless mobile station depending on the location of the wireless mobile station transmitting.

[0014]

However, in the conventional detection method, the number of symbols and the delay time to which the delay profile of the above determinant M can affect are calculated using fixed values. Is small, the maximum matrix calculation specified by the system is performed, and the amount of calculation is the same as in the case where the variance of the delay profile is large.

FIG. 3 is a diagram showing an example of a delay profile. In FIG. 3, the variance of the delay profile is smaller than in the example of FIG. In such a case, it is considered that the amount of calculation can be reduced by reducing the delay time of the determinant indicating the propagation path and the number of symbols that can affect the delay profile.

An object of the present invention is to reduce the amount of calculation in data detection.

[0017]

According to one aspect of the present invention, there is provided a communication apparatus, comprising: a delay profile estimating means for estimating a delay profile from a received signal; Threshold determination means for determining whether or not each delay wave is equal to or higher than a threshold level; and a delay profile for a delay wave including a delay wave from a first delay wave to a last delay wave of the delay profile determined to be equal to or higher than the threshold level. A delay profile matrix creation unit for creating a matrix; and a detection unit for detecting data from the received signal using the delay profile matrix.

According to a second aspect of the present invention, there is provided a communication apparatus, comprising: a delay profile estimating means for estimating a delay profile from a received signal; and a threshold for determining whether or not each delay wave of the delay profile is equal to or higher than a threshold level. Determining means, a delay profile matrix creating means for creating a delay profile matrix for a delay wave including a delay wave of the delay profile determined to be equal to or higher than the threshold level, and detecting data from the received signal using the delay profile matrix And a detecting means for performing the detection.

According to a third aspect of the present invention, there is provided a communication apparatus, comprising: broadcast information collecting means for collecting broadcast information from a received signal; delay profile estimating means for estimating a delay profile from the received signal; A delay profile matrix creating unit that determines a maximum delay time based on the delay profile, and creates a delay profile matrix for a delay wave including a delay wave up to the maximum delay time in the delay profile, and the reception signal using the delay profile matrix. And a detecting means for detecting data from the data.

According to a fourth aspect of the present invention, there is provided the communication apparatus according to any one of the first to third aspects, wherein the communication apparatus is a wireless mobile station.

According to a fifth aspect of the present invention, there is provided the communication apparatus according to any one of the first to third aspects, wherein the communication apparatus is a radio base station.

According to a sixth aspect of the present invention, there is provided a detection method, wherein a delay profile estimating step of estimating a delay profile from a received signal, and a threshold for determining whether or not each delay wave of the delay profile is equal to or higher than a threshold level A determining step, a delay profile matrix creating step of creating a delay profile matrix for a delay wave including a delay wave from a first delay wave to a last delay wave of the delay profile determined to be equal to or higher than the threshold level; and A detection step of detecting data from the received signal using a matrix.

According to a seventh aspect of the present invention, in the detection method, there is provided a delay profile estimating step of estimating a delay profile from a received signal, and a threshold for determining whether or not each delay wave of the delay profile is equal to or higher than a threshold level. A determining step, a delay profile matrix creating step of creating a delay profile matrix for a delay wave including the delay wave of the delay profile determined to be equal to or higher than the threshold level, and detecting data from the received signal using the delay profile matrix And performing a detection step.

[0024] The invention according to claim 8 is a detection method, comprising: a broadcast information collecting step of collecting broadcast information from a received signal; a delay profile estimating step of estimating a delay profile from the received signal; A delay profile matrix creating step of creating a delay profile matrix for a delay wave including a delay wave up to the maximum delay time in the delay profile, and determining the reception signal using the delay profile matrix And a detection step of detecting data from the data.

According to the above configuration, the amount of calculation in data detection can be reduced.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 4 is a block diagram showing a configuration example of a communication device according to a first embodiment of the present invention. The communication device according to the present embodiment includes a delay profile estimating unit 110, a determinant creating unit 120, a data detecting unit 13
0 and a threshold determination unit 140. The communication device according to the present embodiment can take the form of a wireless mobile station or a wireless base station, and performs joint detection using a pilot signal in a CDMA system.

The delay profile estimating section 110 detects a correlation between a received signal and a pilot signal and estimates a delay profile (channel estimation). The threshold determination unit 140 detects a delayed wave equal to or more than the threshold from each delayed wave (each estimated value) of the delay profile.

FIG. 5 is a diagram showing an example of the delay profile. In the example of FIG. 5, the delayed waves (a1) and (a2) are the delayed waves having the threshold or more.

Conventionally, the calculation is performed based on profile information for the maximum delay time (maximum allowable time) inherent in the system, but by providing a threshold as shown in FIG. 5, the profile used for the calculation can be reduced. it can.

The determinant creating unit 120 outputs the first delayed wave determined to be equal to or higher than the threshold level (in the example of FIG. 5, (a
A delay profile matrix is created based on delay waves including delay waves from 1)) to the last delay wave ((a2) in the example of FIG. 5). In the present embodiment, since the CDMA method is used,
A delay profile matrix is created by convolving the spread code of each symbol with the delay profile.

FIG. 6 is an enlarged view of FIG. For example, if the spreading factor is 16 and the time from the first delayed wave to the last delayed wave is 20 chips, in the present embodiment, the symbols including the delayed waves from the first delayed wave to the last delayed wave (FIG. In the example of FIG. 5, a delay profile matrix M is created for a delayed wave of two symbols). In the example of FIG. 5, a delayed wave after the last delayed wave is also somewhat considered in the delay profile matrix.

When the number of symbols affected by the delay profile required for the calculation is spread by a spreading code like CDMA, the time from the first delay wave above the threshold to the last delay wave is divided by the spreading factor. Quotient (integer)
｛(Quotient + 1) × 2｝ +1. The doubling takes into account the symbols before and after the symbol of interest, and the reason why 1 is added at the end is to include the symbol of interest itself.

For example, if the spreading factor is 16 and a delay of up to 60 chips is detected in the conventional system (maximum delay time: 60 chips), the operation of {(60 chip ÷ 16) +1} × 2 + 1 = 9 symbols is performed. On the other hand, if the time from the first delayed wave to the last delayed wave is 20 chips, then {(20 chips {16) +1} × 2 + 1 = 5 symbols. Assuming that the number of users is 8, the determinant M
Is ｛(the number of symbols that can affect the delay profile x spreading factor)
+ Delay time−1｝ row (the number of users × the number of symbols to which the delay profile can affect) column. Therefore, in the conventional example, a matrix of 203 rows × 72 columns is used. It can be a matrix of 40 columns. That is, since the number of symbols and the delay time affected by the delay profile can be reduced, the amount of matrix calculation can be reduced.

The data detector 130 detects data by multiplying the received signal by the inverse matrix of the created delay profile matrix.

In this embodiment, the case where the present invention is applied to the CDMA system has been described. However, the present invention can be applied to systems other than the CDMA system. In the case where the CDMA method is not used, the same effect can be obtained simply by setting the number of symbols affected by the delay wave to (time from the first delay wave to the last delay wave) × 2 + 1.

(Second Embodiment) FIG. 7 is a block diagram showing a configuration example of a communication device according to a second embodiment of the present invention. The communication device according to the present embodiment includes a delay profile estimating unit 210, a determinant creating unit 220, a data detecting unit 23
0, and a threshold determination unit 240. The communication device according to the present embodiment can also take the form of a wireless mobile station or a wireless base station, and performs joint detection using a pilot signal in the CDMA system. Also,
The process up to estimating the delay profile from the received signal and performing the threshold determination is the same as in the first embodiment.

FIG. 8 is a diagram showing an example of the delay profile. The determinant creation unit 220 outputs the delayed wave determined to be equal to or higher than the threshold level ((b1) and (b2) in the example of FIG. 8).
A delay profile matrix is created for a delay wave including. More specifically, a delay profile matrix is created for a delay wave of a symbol including a delay wave determined to be equal to or higher than the threshold level. As shown in FIG. 8, when delay waves equal to or more than the threshold are temporally separated, the amount of calculation is reduced according to the timing of each symbol.

In the example of FIG. 8, there are two delay waves having a threshold level or more, but even when there are three or more delay waves, a delay profile matrix is created for the delay waves of the symbols including the respective delay waves. . Note that two or more delayed waves exceeding the threshold level may belong to one symbol.

In this embodiment, the case where the present invention is applied to the CDMA system has been described. However, the present invention can be applied to systems other than the CDMA system.

(Third Embodiment) FIG. 9 is a block diagram showing a configuration example of a communication device according to a third embodiment of the present invention. The communication device according to the present embodiment includes a delay profile estimation unit 310, a determinant creation unit 320, a data detection unit 33
0, and a notification information collecting unit 350. The communication device according to the present embodiment can also take the form of a wireless mobile station or a wireless base station, and performs joint detection using a pilot signal in the CDMA system.

Broadcast information collecting section 350 collects broadcast information included in the received signal. The determinant creation unit 320 determines the maximum delay time based on the broadcast information, and creates a delay profile matrix for delay waves including delay waves up to the maximum delay time in the delay profile.

As the broadcast information, for example, transmission power information and cell radius information broadcast by the radio base station can be considered.
For example, a wireless mobile station that has collected transmission power information or cell radius information can determine the maximum delay time based on that information.

FIG. 10 is a diagram showing an example of the delay profile. By determining the maximum delay time based on the broadcast information and creating a delay profile matrix, it is considered that the amount of matrix calculation can be reduced as shown in FIG. For example, when the cell radius is small, the amount of matrix calculation can be reduced.

In this embodiment, the case where the present invention is applied to the CDMA system has been described. However, the present invention can be applied to systems other than the CDMA system.

[0046]

As described above, according to the present invention, the amount of calculation in data detection can be reduced. Therefore, power consumption in data detection can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a conventional communication device.

FIG. 2 is a diagram illustrating an example of a delay profile.

FIG. 3 is a diagram illustrating an example of a delay profile.

FIG. 4 is a block diagram illustrating a configuration example of a communication device according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of a delay profile.

FIG. 6 is an enlarged view of FIG. 5;

FIG. 7 is a block diagram illustrating a configuration example of a communication device according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of a delay profile.

FIG. 9 is a block diagram illustrating a configuration example of a communication device according to a third embodiment of the present invention.

FIG. 10 is a diagram illustrating an example of a delay profile.

[Description of Signs] 10, 110, 210, 310 Delay profile estimator 20, 120, 220, 320 Determinant generator 30, 130, 230, 330 Data detector 140, 240 Threshold determiner 350 Broadcast information collector

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shinji Uebayashi F-term (reference) 5K022 EE01 EE21 EE31 5K059 DD32 DD35 DD39 in NTT Docomo, 2-1-1 Nagatacho, Chiyoda-ku, Tokyo EE02

Claims (8)

[Claims] 1. A communication apparatus, comprising: a delay profile estimating unit for estimating a delay profile from a received signal; a threshold determining unit for determining whether each delay wave of the delay profile is equal to or higher than a threshold level; Delay profile matrix creating means for creating a delay profile matrix for a delay wave including a delay wave from a first delay wave to a last delay wave of the delay profile determined as described above, and the reception signal using the delay profile matrix And a detecting means for detecting data from the communication device. 2. A communication apparatus, comprising: a delay profile estimating unit for estimating a delay profile from a received signal; a threshold determining unit for determining whether each delay wave of the delay profile is equal to or higher than a threshold level; A delay profile matrix creating unit that creates a delay profile matrix for a delay wave including a delay wave of the delay profile determined as described above; and a detection unit that detects data from the received signal using the delay profile matrix. A communication device characterized by the above-mentioned. 3. A communication device, comprising: broadcast information collecting means for collecting broadcast information from a received signal; delay profile estimating means for estimating a delay profile from the received signal; and a maximum delay time based on the broadcast information. A delay profile matrix creating unit that determines and creates a delay profile matrix for a delay wave including a delay wave up to the maximum delay time in the delay profile; and a detection unit that detects data from the received signal using the delay profile matrix. A communication device comprising: 4. The communication device according to claim 1, wherein the communication device is a wireless mobile station. 5. The communication device according to claim 1, wherein the communication device is a wireless base station. 6. A detection method, comprising: a delay profile estimating step of estimating a delay profile from a received signal; a threshold judging step of judging whether or not each delay wave of the delay profile is equal to or higher than a threshold level; A delay profile matrix creating step of creating a delay profile matrix for a delay wave including a delay wave from a first delay wave to a last delay wave of the delay profile determined as described above, and the reception signal using the delay profile matrix A detecting step of detecting data from the data. 7. A detection method, comprising: a delay profile estimating step of estimating a delay profile from a received signal; a threshold judging step of judging whether or not each delay wave of the delay profile is equal to or higher than a threshold level; A delay profile matrix creating step of creating a delay profile matrix for a delay wave including a delay wave of the delay profile determined as described above, and a detection step of detecting data from the received signal using the delay profile matrix. A detection method characterized by the above-mentioned. 8. A detection method, comprising: a broadcast information collecting step of collecting broadcast information from a received signal; a delay profile estimating step of estimating a delay profile from the received signal; and a maximum delay time based on the broadcast information. Determining, a delay profile matrix creating step of creating a delay profile matrix for a delay wave including a delay wave up to the maximum delay time in the delay profile, and a detecting step of detecting data from the received signal using the delay profile matrix A detection method comprising: