Layered space-time codes have been designed to exploit the capacity advantage of multiple antenna systems in Rayleigh fading environments. In this paper, a new efficient decoding algorithm based on QR decomposition is presented. It needs only a fraction of computational effort compared to the standard decoding algorithm requiring the multiple calculation of the pseudo inverse of the channel matrix.Introduction: In a Rayleigh fading environment multiple antenna systems provide an enormous increase in capacity compared to single antenna systems. To take advantage of multiple antennas space-time codes (STC) have been introduced to use space as a second dimension of coding. Layered space-time (LST) codes are a special kind of STC with the advantage of a feasible decoding complexity [1]. For these LST we introduce a new, efficient way of decoding based on the QR-decomposition.

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

In this paper we present a flexible multiple input multiple output (MIMO) measurement system for communication signals in the 2.4 GHz band. We present some measurements of the digital to digital transmission channel which includes all impairments of the hardware realization.Using this system we perform a multi-layer transmission of communication signals. At the receiver side we use blind source separation (BSS) techniques as frontend processing to avoid estimation and synchronization problems. In order to improve the estimation of the channel and the symbol detection, we propose an iterative approach, which uses the knowledge of the finite symbol alphabet but does not need additional training data.

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Abstract-Wideband CDMA systems with orthogonal spreading codes suffer severely due to the loss of orthogonality by multi-path propagation. This yields Multiple User Interference (MUI), which gravely reduces the performance of classical systems with Rake-receivers. In our approach we attempt to restore orthogonality by using a modified T-equalizer. Classical T-equalizers are composed as FIR filters with equidistant delays and appropriate coefficients. Their main disadvantage is the high computational effort due to the large number of coefficients.The question arises whether we need to calculate all equally spaced coefficients, or if some of the coefficients can be neglected. The basic idea of this paper is to use only a subset of coefficients and set all others to zero. The main advantages are the reduced computational effort in calculating the filter and the decreased computational costs in using it. In this paper we will show the feasibility with some simulation results for block fading channels. In practice, we usually do not use a T-equalizer very often for time variant channels, due to its high computational costs. An adaptive algorithm is instead taken and modified accordingly. In our case we take a Least Mean Squares (LMS) algorithm for MUI-suppression in a time variant environment. In order to show the feasibility of this approach, some simulation results for channels with low Doppler frequencies are presented and compared with the classical Rake-receiver and a full version of the LMS/Griffith by [1].