Abslmcl-The performance of an OFDM-bawd transmission system according lo IEEE 802.11g can severely sulTer from interfering Blnetmth packets. Therefore, we propose two new approaches for narrow-hand interference suppression a s conntermeasnre. At first, the presence and frequency position of interference is blindly estimated by evaluating either the magnitude variance of the received symbols or the noise power on each snbchannel. For that pnrpme, we present one algorithm baed on dimerentiation in frequency direction, and another one making use of the median filter. After detection, an interference suppression by modsying the softbit magnitudes at the input of the channel decoder leads to a significant improvement of Ihe system performance, as we will show by simulations.

Finite-Alphabet-based blind channel estimation in OFDM systems is known to be extremely complex due to an exhaustive search to be performed over a tremendous number of channel coefficient combinations. In this paper, we present a novel blind channel estimator which dramatically reduces this number of coefficient combinations to be checked without a significant deterioration in estimation quality. Hence, the new low complexity approach enables the application of blind channel estimators based on the finite alphabet set even if the transmitted data are high-rate modulated. Furthermore, we show that the performance of blind channel estimation can be improved by an iterative process based upon the capabilities of channel coding. Using bit error rates, the algorithm is tested with simulations and compared to other blind and nonblind channel estimators.

We present a multiple antenna system for industrial, scientific, and medical (ISM)-band transmission (MASI). The hardware demonstrator was developed and realized at our institute. It enables multiple-input multiple-output (MIMO)-communication applications and is capable of transmiting arbitrary signals using 8 transmit and 8 receive antennas in parallel. It operates in the 2.4 GHz ISM-band. The hardware concept is introduced and some design specifications are discussed. Using this transmission system, we present some measurement results to show the feasibility of MIMO concepts currently under discussion. The applications include transmit and receive diversity for single carrier and OFDM as well as blind source separation (BSS) techniques

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