Abstract: There is provided a signal detecting method using constellation set grouping in a spatial multiplexing multiple input multiple output system. The signal detecting method includes dividing a set of candidate symbols, a constellation set into a plurality of subsets by grouping the constellation set; dividing a tree search process of a QR-decomposition with M-algorithm (QRDM) algorithm into a plurality of partial detection phases; and performing the plurality of divided partial detection phases in parallel or iteratively.

Abstract: The present invention relates to a system for canceling co-channel interference (CC) in a cellular orthogonal frequency division multiplexing (OFDM) system. The system canceling co-channel interference (CCI) in a cellular orthogonal frequency division multiplexing (OFDM) system comprises a mobile station (MS) receiver including a feedback generation unit for generating a feedback to a base station (BS) so as to control a transmission power of the transmitting frame of the BS, and a maximum likelihood estimation (MLE) CCI cancellation unit for canceling CCI signals arriving from neighbor cells; and a BS transmitter including a closed-loop power control unit for controlling the transmission power of the transmitting frame according to the feedback received from the MS such that received power of desired signal at the MS receiver is different from that of an interferer signal.

Abstract: There is provided a signal detecting method using constellation set grouping in a spatial multiplexing multiple input multiple output system. The signal detecting method includes dividing a set of candidate symbols, a constellation set into a plurality of subsets by grouping the constellation set; dividing a tree search process of a QR-decomposition with M-algorithm (QRDM) algorithm into a plurality of partial detection phases; and performing the plurality of divided partial detection phases in parallel or iteratively.

Abstract: A method for detecting signals in spatial multiplexing multiple-input multiple-output (MIMO) systems using a QR-decomposition with M (QRD-M) algorithm is provided. The method includes receiving signals, limiting upper and lower bounds of a complexity in a QR-decomposition with M (QRD-M) algorithm, and detecting the received signals using the QRD-M algorithm. The signal detecting method can effectively reduce the amount of operation generated while detecting signals, using the QRD-M algorithm where the upper and lower bounds of the complexity are limited.

Abstract: In this patent, we propose an efficient CCI cancellation algorithm capable of working in cellular OFDM systems in high interference environments especially for users at the cell edges. We propose modified BSs' transmitters (Txs) and MS receiver (Rx) structures. Adjacent BSs use different transmitting interleaving patterns. This leads to orthogonality in the frequency domain. Furthermore, the energy of every symbol is spread over two different subcarriers to get frequency diversity. At the MS Rx, the maximum likelihood estimator MLE CCI canceller is applied to cancel signals of interfering BSs using the same frequency band. A drawback of the MLE CCI canceller is that its performances is degraded when the received power of desired and interferer signals is nearly the same. To solve this problem, the MLE CCI canceller is assisted by a closed-loop power control (CPC) scheme. The newly proposed CPC scheme is capable of detecting and combating against the situation where the equal power is received.