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Antennas are commonly located in near each other and there is high correlations among antennas. In such cases, there exists correlated fading among antennas, which results in worse performance for this system. This paper presents an effective soft handoff technique using Space Time Transmitter Diversity (STTD) with two base station for Multi-Carrier (MC)-CDMA to achieve high diversity gain in a wireless...
This paper proposes a new array antenna assisted Doppler spread compensator having a vehicle speed estimation function. The array antenna assisted Doppler spread compensator compensates for the Doppler spread by estimating the received signal at the stationary point with respect to the ground. However, the compensator requires the vehicle speed for compensation. The proposed vehicle speed estimator...
This paper deals with downlink time division duplex MC-CDMA system, and presents a space-frequency pre-filtering technique designed for two different receivers: a simple despread receiver without channel equalization and an EGC conventional receiver, where the base station is equipped with an antenna array. We show that the space-frequency pre-filtering approach proposed allows to format the transmitted...
The paper considers transmitter strategies for interference mitigation in the downlink of a multi-carrier CDMA system using antenna arrays. We describe typical indoor and outdoor scenarios and derive the corresponding transmitter strategy according to the channel knowledge available at the base station for each case. We show the effectiveness of multi-user space-frequency transmit filtering for the...
In this work we investigate the possibilities of combining diversity techniques with a Single Carrier System with Frequency Domain Equalization (SC/FDE), as future transmission concepts will also be judged by their possibilities to be combined with multiple antennas. Concepts of multiple antennas allow either a significant performance gain through diversity (and) or significant higher capacity based...
Multicarrier techniques are of high interest in modem communication systems due to their spectral efficiency and simplicity of channel equalization even in the case of heavily frequency selective channels. Further advantages of MC techniques include, e.g., their insensitivity to timing errors as well as to limited narrowband interference. This paper presents a comparison of MC-CDMA and OFDM with diversity...
Since the work of Foschini [1], there has been a huge interest concerning Multiple Input Multiple Output (MIMO) systems in order to exploit the capacity varying linearly with the minimum of transmit Nt and receive antennas Nr and then to exploit the diversity of these systems using Orthogonal Space Time Block Codes (OSTBC) as discovered by Alamouti [2] for Nt=2 and then generalized by Tarokh [3] for...
The performance of MMSE Single-user Detection (SD) and Multi-user Detection (MD) STBC MC-CDMA systems are analysed and compared in the case of two transmit antennas and one or two receive antennas over Rayleigh fading channels and then over the stochastic MIMO METRA channel model. With two transmit and one receive antennas, MD achieves a gain of roughly 1 dB for non-full load systems while the same...
In this paper the standard space time block coding, the selection diversity space time block coding and eigen-beamforming techniques are compared in a block fading scenario taking account the channel estimation errors at the transmitter side. The comparison criterion is the signal to noise ratio obtained to the receiver at the output of the antenna combiner. The channel is assumed to be perfectly...
This paper presents the encoding and decoding algorithms for the various codes and provides simulation results demonstrating their performance in an OFDM-MIMO environment. The system performance is examined in the presence of typical OFDM problems like timing errors, frequency errors and oscillator phase noise. It is shown that using multiple transmit/receive antennas and space-time block coding along...
Future wireless communication systems will require high data-rates in multiuser environments. Multicarrier code-division multiple-access (MC-CDMA) has emerged as an attractive technique for broadband communications, offering efficient utilization of bandwidth and robust performance in multipath channels. In this paper, coded downlink MC-CDMA is combined with the concept of LST architectures. Suboptimal...
In this paper an extension of the V-BLAST (Vertical Bell Labs Layered Space-Time) algorithm with adaptive rate and power allocation for broadband multiple-input multiple-output (MIMO) systems is considered in order to overcome the poor behavior of conventional V-BLAST in spatially correlated channels.
In this paper, the techniques for turbo detection of single user spatial division multiplexing data streams were discussed. Simulation results and complexity study shows the tradeoff between performance and complexity. It is shown that MMSE initialised PIC receiver achieves good performance complexity tradeoff when the number of transmit antennas and constellation size is large.
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