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This paper is focusing on the performance of the proposed exponentially weight recursive least square (EW-RLS) and normalized least mean square (NLMS) channel estimator using simulations, in the context of the communication system with MIMO antenna operating in outdoor environments. Different training rates and different Doppler frequencies are used to track time-variations of the channel. Three adaptive...
In this paper, we present the efficient pilot patterns and channel estimations for a high-rate multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) system. In particular, we propose the scattered pilot (SP), edge pilot (EP), and continuous pilot (CP) by exploiting a basic orthogonal property of a unitary matrix. From the orthogonal property, we then propose the efficient...
Based on our previously developed signal perturbation free (SPF) transmit scheme, a new linear prediction (LP)-based channel estimation algorithm with ill condition identification is proposed for MIMO-OFDM systems. Based on the estimated correlation matrix of the received signal without signal perturbation error by employing the SPF transmit scheme, a SPF LP-based MIMO-OFDM channel estimation algorithm...
This paper studies the computation of postprocessing signal-to-interference plus noise ratio (SINR) for maximum likelihood detector (MLD) in multiple-input and multiple output (MIMO)-orthogonal frequency division multiplexing (OFDM) spatial multiplexing systems. We derive an effective post-MLD SINR for each spatial stream, which is computed as post minimum mean-squared error (MMSE) SINR plus gain...
In this paper, we propose an ordered selection technique to improve the performance of the decision-directed RLS adaptive channel tracking algorithm in 2 ?? 2 spatial-multiplexing MIMO-OFDM systems under high mobility. The proposed technique uses the decision of high reliability order during MIMO signal detection and then selectively activates the RLS adaptation only when less interference and error...
Orthogonal frequency division multiplexing (OFDM) offers high data rates and robust performance in frequency selective channels by link adaptation utilizing information about the channel quality. Combined with multiple-input multiple-output (MIMO) technique it provides improved link reliability and increased data rate. A crucial parameter required for adaptive transmission is the signal-to-noise ratio...
The second-order statistics (SOS) of the received signal are very often used in blind and semi-blind channel estimation. In this paper, an analysis of signal perturbation in SOS of the received signal is first conducted, revealling that, even in the noise-free case, some SOS-based blind and semi-blind algorithms are subject to a signal perturbation error. Based on the analysis, a very efficient transmit...
The combination of multi-input multi-output (MIMO) with orthogonal frequency division multiplexing (OFDM) is regarded as a promising technique for the future wireless communications. However, the performance of MIMO OFDM systems is very sensitive to carrier frequency offset (CFO) which introduces inter-carrier-interference (ICI). Consequently, CFO estimation plays a key role in MIMO OFDM systems....
In this paper, simultaneous channel estimation, carrier frequency offset (CFO) estimation, and data decision are considered for multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. It is shown that the expectation maximization (EM) approach is complementary to the Kalman filter (KF) approach where the latter provides poor CFO estimation but good channel estimation...
In multiple-input multiple-output (MIMO) communications systems, a crucial role is played by channel estimation as the accuracy of estimation will have a substantial effect on the overall system performance. In this paper we consider designing precoding matrices and blind channel estimation algorithms for MIMO single carrier with frequency domain equalization (MIMO-SC-FDE) systems. By deriving the...
Orthogonal frequency division multiplexing (OFDM) is the modulation scheme of choice for digital video broadcasting-handheld (DVB-H), which is required to operate under high mobility conditions resulting in significant Inter-carrier Interference (ICI). To mitigate ICI, several cancellation schemes have been proposed but they require reliable channel information at the receiver which is quite challenging...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
Orthogonal frequency division multiplexing (OFDM) is the modulation scheme of choice for digital video broadcasting-handheld (DVB-H) which is required to operate under high mobility conditions resulting in significant Inter-Carrier Interference (ICI). Under these conditions, the conventional one-tap per subcarrier channel estimation and equalization is suboptimal since it does not account for ICI...
Effects of improved channel estimation are studied for a proposed IEEE 802.11n OFDM MIMO system. Three channel estimation methods are considered: maximum likelihood (ML), time-domain truncation (TDT) and model-based (MB). TDT and MB are particularly useful when the channel delay spread is short. For an MMSE receiver, MB shows a 1-2.5 dB improvement over ML on the packet error rate performance for...
In this paper, we consider a new channel probing scheme for opportunistic scheduling in the uplink of orthogonal frequency division multiplexing (OFDM)-based wireless systems. To reduce signaling overhead for the probing, we consider a two-step channel probing process; called pre-probing and mainprobing. Good subchannels are first estimated through the pre-probing process using a probing signal transmitted...
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