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A multi-user multiple input multiple output (MIMO) system with beamforming based on maximum ratio transmission (MRT) is analyzed in a Rayleigh fading environment. A simple closed and compact form approximate expression for the outage probability of a mobile station for the downlink of such a system is obtained by considering that all the mobile stations are power controlled by a single base station...
In this paper, we propose a simple differential space-time block code with a quasi-orthogonal structure, which can offer full rate and full diversity. At the transmitter, we divide the codes into sub-coding blocks, and combine the sub-coding blocks at the receiver to employ differential decoding by channel power estimation instead of decoding each sub-coding block separately. Our general approach...
We present a model of linear space-time block coded multiple input multiple output wireless systems for quasi-static frequency nonselective fading channels. The code is described by its set of spreading matrices. We give a condition on the spreading matrices in order not to degrade the mutual information compared to the uncoded case. The knowledge of the channel impulse response and the spreading...
This article presents a set of quasi-orthogonal space-time block codes for four transmit antennas that achieves full diversity and high coding gain whenever a square lattice constellation is adopted. From the simulation results, the new designs perform very closely to quasi-orthogonal codes with constellation rotations. Without a search of the optimal rotation angle and any constellation expansion,...
Orthogonal variable spreading factor (OVSF) codes are widely used to provide variable data rates for supporting different bandwidth requirements in wideband code division multiple access (WCDMA) systems. Many works in the literature have intensively investigated code placement and replacement schemes in OVSF code trees to reduce the code blocking probability and increase the code spectral efficiency...
The paper deals with space-time-coded transmissions in the presence of channel estimation errors. A simple transmission model is described which gives insight into the basic relations between space-time block coding schemes and the general concept of spreading. On the basis of this model, diagonal algebraic space-time (DAST) block codes are taken as an example. For maximum ratio combing and equal...
In this paper, we present an original use of Reed-Solomon (RS) codes as space-time block codes (STBCs) and compare them to orthogonal STBCs (OSTBCs). Due to their symbol structure, they can have a representation close to that of an STBC. RS codes are admittedly more complex to decode as they have no orthogonal properties. However, they offer much higher coding rates. In addition, a wide range of these...
We analyze the performance of a joint timing epoch tracking and PSAM-based channel estimation system in a frequency-flat Rayleigh fading MIMO channel. The receiver tracks a random timing drift via a timing error detector developed for nT = 2 orthogonal space-time block coded MPSK systems with an arbitrary number of receive antennas. The detector's S-curve has recently been shown to be independent...
This paper proposes performance improvement schemes for multiple-input multiple-output (MIMO) communication systems employing per transmit antenna differential encoding (PADE), which generates an independent differentially encoded sequence for each of the multiple transmit antennas by means of space-time coding and mapping. PADE can operate without channel state information (CSI) at both the transmitter...
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