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Equalized parallel interference cancellation (EPIC) for CDMA system

A technology of interference cancellation and weighting coefficients, applied in transmission systems, electrical components, etc.

Inactive Publication Date: 2008-01-09
NOKIA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Optimal multiuser detection (MUD) methods (see: S. Verdu, "Minimum error probability for asynchronous Gaussian multiple access channels", IEEE Transactions on Information Theory, IT-32, pp. 85-96, January 1986) are able to eliminate multiple site interference (MAI), but its complexity scales exponentially with the number of users, making it almost impossible to implement

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  • Equalized parallel interference cancellation (EPIC) for CDMA system
  • Equalized parallel interference cancellation (EPIC) for CDMA system
  • Equalized parallel interference cancellation (EPIC) for CDMA system

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Embodiment Construction

[0108] The idea of ​​the present invention is to achieve more reliable data estimation combining and equalizing the hard decision outputs of rake receivers and 1-stage Parallel Interference Cancellation (PIC) detectors.

[0109] According to Fig. 4 showing the block diagram of the present invention and the weighting method based on the first embodiment, the signal z output by the rake receiver is calculated according to the following formula Rake Make a temporary hard decision to obtain the hard decision value b Rake :

[0110] [b Rake ] k =sgn{[z Rake ] k},

[0111] Where k=1, 2, . . . , K, k is a user index.

[0112] According to the following formula for the hard decision value b Rake Perform MAI regeneration processing, including parallel interference cancellation:

[0113] MAI 1 =Fb Rake , F=A H S H SA-diag) [A H S H SA] ii )

[0114] Diagonal intersection matrix.

[0115] Signal z from Rick receiver Rake The value output from the first MAI regeneration ...

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Abstract

A new multiuser detection scheme EPIC (Equalized Parallel Interference Cancellation) is disclosed. A rake receiver signal zRake output by a rake receiver is detected, which receives a spread spectrum composite signal r comprising plural user signal b1, b2,...,bk that have been spread with spreading codes. At first, first hard-decision values bRake are produced on the basis of the rake receiver outputs. Then, first parallel interference cancellation values are produced on the basis of the first hard-decision values, and second hard-decision values bPIC are produced on the basis of the first parallel interference cancellation values. After that, the first and second hard-decision values are combined for producing first combination values, and second parallel interference cancellation values are produced on the basis of the first combination values.

Description

technical field [0001] The present invention relates to the third-generation wideband code division multiple access system (3G WCDMA system), and more specifically relates to a method for detecting spread-spectrum composite signals, wherein the spread-spectrum signals include signals of different users after characteristic waveform expansion. Background technique [0002] A multi-user communication system using CDMA (Code Division Multiple Access) has a limit on the number of users in the sense that users can simultaneously communicate on one channel and each user maintains a specified performance level. This limitation is mainly caused by multiple access interference. Solutions to overcome this limitation usually utilize optimal multiuser detection or interference cancellation methods. [0003] Optimal multiuser detection (MUD) methods (see: S. Verdu, "Minimum error probability for asynchronous Gaussian multiple access channels", IEEE Transactions on Information Theory, IT...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B1/707
CPCH04B1/71075
Inventor 王海峰卜智勇乔玛·里勒伯格
Owner NOKIA CORP