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ABSTRACT: Layered space-time block spread CDMA (LST BSCDMA) has been previously proposed as an alternative to conventional CDMA systems for high-rate mobile communications. This paper proposes two approaches to obtain channel state information (CSI) for LST BS-CDMA system. The basic approach suffers from high computational complexity and poor performance in systems with high order of transmitter diversity due to inter-layer interference (ILI). The second approach reduces computation complexity and eliminates ILI, making it suitable for systems with higher order of transmitter diversity. The detailed simulation studies show that the highly accurate CSI obtained using the improved technique leads to considerable superior performance.
IEEE Transactions on Wireless Communications 04/2010; · 2.59 Impact Factor
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ABSTRACT: This paper studies two MIMO architectures for single-carrier CDMA system employing block spreading, namely Layered Space-Time Block Spread CDMA (LST BS-CDMA) and Space-Time Coded Block Spread CDMA (STC BS-CDMA). It is shown that under low mobility conditions, the proposed systems are virtually free from Multiple User Interference (MUI) and the block processing technique used leads to considerable reduction in the overall processing complexity. Extensive simulation was performed to study the impact of the spreading factor and Doppler frequency on the proposed systems. A new parameter called channel coherence ratio (CCR) is introduced as a key parameter in determining the performance of MIMO BS-CDMA.
IEEE Transactions on Wireless Communications 07/2008; · 2.59 Impact Factor
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ABSTRACT: This paper proposes three different channel estimation techniques for layered space-time block spread CDMA (LST BS-CDMA) systems, using different pilot patterns. The first technique applies the normal channel estimation method for VBLAST systems on each subcarrier. The second technique constructs time-domain sequences that give a set of nulls at predefined frequency and interpolates those nulled tones to obtain the full frequency response of the channel. The third technique improves on the second technique and eliminates the need for knowledge of the channel delay spread. The LST BS-CDMA system is simulated and its performance is compared when the three different channel estimation technique is used
Vehicular Technology Conference, 2006. VTC 2006-Spring. IEEE 63rd; 06/2006
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ABSTRACT: In this paper, single-carrier block spread CDMA for multiple-input-multiple-output (MIMO) systems is proposed. With block spreading and despreading, multiple-user intererence free (MUI-free) transmission with reduced processing complexity is achieved. Layered space-time transmission (LST) is employed to enhance the data rak. of the proposed system. The proposed system is studied extensively under different channel conditions and its performance is compared against conventional single-carrier and multicarrier CDMA systems
IEEE Communications Letters 03/2006; · 0.98 Impact Factor
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Vehicular Technology Conference, 2005. VTC-2005-Fall. 2005 IEEE 62nd; 10/2005
