Electronics and Telecommunications Research Institute

Young Wha Kim

Seong Rag Kim

Sung Ho Cho

In-Kyeong Choi

In Kyeong Choi

A method for parallel type interference cancellation in a CDMA receiver, wherein minimum processing delay time is required while ensuring performance of an interference cancellation device, and space for embedding hardware for implementing the method can be reduced. The method for parallel type interference cancellation in a CDMA receiver, comprising: (a) when an over sample position of a received signal reaches the end of a symbol of a user, completing temporary detecting and recovering the symbol of the user; (b) generating a residual signal by using the recovered signal of the user and received signal state; and (c) detecting symbol information by obtaining an interference cancelled signal by adding the residual signal to the recovered signal of the user.

Method for parallel type interference cancellation in code division multiple access receiver

The present invention relates to a receiver applicable to a code division multiple access system having multiple transfer rates. In a CDMA system, when performing a de-spreading process to extract information from received data in which various terminal signals or multiple path signals are asynchronously mixed, interference between a plurality of users or paths tends to occur. The present invention proposes an interference canceller for effectively canceling the interference between the users or paths. For this, the present invention implements a parallel interference canceller for estimating in parallel interference signals from asynchronously received signals and canceling the estimated interference signals from the received signals. In the present invention, when implementing a parallel interference canceller for asynchronously received signals, as bit information of the received signals is not aligned in the same time frame, the following conditions are considered. First, the accuracy of interference cancellation is maintained. Second, the time delay of signal processing is minimized to minimize the time delay of the entire system. In the present invention, in order to achieve these objects, reproduction of interference signals and the subtraction operation are optimized based on the arrival points and end points based of the fastest signal and the latest signal among the asynchronously received signals.

Apparatus for cancelling interference in CDMA system using multiple transfer rates and method thereof

An apparatus and method for performing circular group-wise parallel interference cancellation in a multi-rate DS-CDMA system that reduce the multiple access interference in a CDMA system are disclosed. The invention provide a method of grouping received signals, which improves the interference cancellation efficiency of the signal receiver. The method of the invention groups a plurality of signals according to the magnitude of signals, and sequentially performs interference cancellation with respect to the groups in order of the signal magnitude. The apparatus and method determine the signal rank by using both the power estimation value of the received signal of each finger and the soft bit decision value being the output value of the maximal ratio combiner, perform grouping of the fingers selected by a finger selector, and finally perform interference cancellation. The soft bit decision value is independent of channel, and has the bit information at the time of signal transmission. Accordingly, this soft bit decision value is employed along with the power estimation value of the received signal, to allow more accurate grouping of signals.

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Taejon, South Korea

Young Wha Kim