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This study proposes a soft ordered successive interference cancellation (OSIC) receiver accompanied by a simplified log-likelihood ratio calculation method for a dual-polarised multiple-input multiple-output (MIMO) digital video broadcasting-second generation terrestrial system. The future terrestrial transmission systems will be required to provide high data rates for ultra-high definition television...
Turbo equalization schemes based on minimum mean square error (MMSE) criteria available in the literature for multiple-input multiple-output (MIMO) systems are computationally expensive, as they require a relatively large matrix inversion. In this paper, we propose a low complexity turbo equalization (TE) scheme with successive interference cancellation for orthogonal frequency division multiplexing...
In this paper, we study adaptive nonlinear turbo equalization to model the nonlinear dependency of a linear minimum mean square error (MMSE) equalizer on soft information from the decoder. To accomplish this, we introduce piecewise linear models based on context trees that can adaptively choose both the partition regions as well as the equalizer coefficients in each region independently, with the...
A new layered frequency-domain turbo equalization (LFDTE) scheme is proposed for single carrier (SC) multiple-input multiple-output (MIMO) systems. The proposed scheme combines the respective advantages of layered detection and turbo equalization to further lower the bit error rate (BER) for high-data-rate communications. Different from the traditional frequency-domain turbo equalization (FDTE) method...
This paper focuses on turbo packet combining strategies for multi-relay-assisted systems operating over multiple-input-multiple-output (MIMO) broadband channel. We propose a frequency domain minimum mean square error (MMSE)-based turbo packet combining scheme where all slots received signals and their corresponding channel frequency responses (CFR)s are used to decode the data packet. We also provide...
A novel adaptive Turbo equalization algorithm based on the serious inter-symbol interference (ISI) in wireless channel is proposed. The channel characteristics are estimated through combining iterative recursive least square (RLS) with least mean square(LMS) and channel's changes are traced; and the soft interference cancellation (SIC) algorithm for Turbo equalization and the iterative calculations...
Recently, a block spreading code division multiple access (BS-CDMA) technique was presented whereby user-specific preceding along with orthogonal spreading codes are used to achieve multi-user interference (MUI) free when all users arrive at the base station simultaneously. In practice however, imperfect synchronization destroys the orthogonality among users and MUI occurs. This paper investigates...
It is well-known that, the cyclic prefix (CP) protects orthogonal frequency-division multiplexing (OFDM) system from inter-block interference (IBI), but it also reduces the spectral efficiency. In this paper, a low-complexity turbo equalization algorithm is proposed for multiple input multiple output (MIMO) OFDM system without CP. In our algorithm, tail cancellation is performed firstly by using the...
A novel Frequency Domain Turbo Equalization (FD-TE) is proposed in multiple input multiple output (MIMO) systems, in which equalization is executed on Single Frequency Tone (SFT). It is proposed that received data from all receive antennas on one frequency tone are considered jointly, and then minimum mean square error (MMSE) equalization is implemented. This algorithm can reduce the calculation complexity...
A communication system using multilayer coded modulation is introduced to detail the basic principles of hierarchical combined equalization based on linear minimum mean square error (MMSE) algorithm. A simplified hierarchical equalizer's extrinsic information of base-layer for 4-QAM multilayer coded modulation is presented. A new hierarchical equalization method of base layer is applied to multilayer...
This paper proposes a bit-selective iterative processing scheme for turbo equalization. We consider convolutionally coded and turbo coded transmissions over inter-symbol interference (ISI) channels. The receiver starts with conventional iterative channel equalization and decoding. After each iteration, bit convergence status is measured via cross-entropy. Short windows are then applied around unconverged...
This paper treats the digital design of a probabilistic energy equalizer for impulse radio (IR) UWB receiver in high data rate (100 Mbps). The aim of this study is to bypass certain complex mathematical function as a chi-squared distribution and reduce the computational complexity of the equalizer for a low cost hardware implementation. As in Sub-MAP algorithm, the max* operation is investigated for...
A maximum likelihood sequence estimation (MLSE) combined equalizer and decoder with soft-decision decoding performance, that has a computational complexity superior to that of conventional MLSE equalization, is proposed. Its performance is compared to a system containing a soft-output Viterbi MLSE equalizer followed by a soft-decision Viterbi MLSE decoder. It is shown via computer simulation that...
An a posteriori probability (APP) detector for multiple antenna channels has presented in . It has the high advantage of providing good performance but has an NP complexity, we studied near capacity and near outage performance over multiple antenna channels thanks to optimized bit interleaved coded modulations (BICM) . We will now present a sub-optimal soft-input soft-ouput (SISO) detector based on...
In this paper we analyze low complexity turbo equalization that combines interference canceling and soft-input soft-output (SISO) decoding. We derive a new, exact MMSE solution for the equalization part taking into account the cross-correlation between the linear equalizer output and the soft decisions in the turbo equalization feedback loop as well as the auto-correlation function of the decoder...
Quadrature OFDMA (Q-OFDMA) systems have been recently proposed to reduce the complexity and peak-to-average power ratio (PAPR), and improve carrier frequency offset (CFO) robustness for OFDMA systems. However, Q-OFDMA receiver obtains frequency diversity at the cost of noise enhancement. This paper proposes an iterative (turbo) equalization in conjunction with channel estimation for Q-OFDMA systems...
We consider the problem of soft-input soft-output detection over channels affected by intersymbol interference. In particular, we introduce a novel (cyclic) factor graph describing the channel and, by applying the sum-product algorithm to it, we derive some detection schemes that can provide impressive complexity reductions with respect to the optimal algorithm. Simulation results are reported which...
Turbo equalizer exhibits dramatic performance improvement comparing with conventional equalizers by combining equalization and decoding, where soft information is iteratively exchanged between the equalizer and decoder. However, turbo equalization is much more complex and hence precludes practical implementation when considering multilevel modulations over highly dispersive channels. In this letter,...
Currently, 3GPP standardizes an evolved UTRAN (E-UTRAN) within the Release 8 Long Term Evolution (LTE) project. Targets include higher spectral efficiency, lower latency, higher peak data rate when compared to previous 3GPP air interfaces. The air interface of E-UTRAN is based on OFDMA and MIMO in downlink and on SCFDMA in uplink Main challenges for a terminal implementation include efficient realization...
This paper proposes an efficient turbo frequency domain equalizer (FDE) for single carrier systems with cyclic-prefix (CP). At each iteration, the proposed algorithm performs soft inter-symbol interference (ISI) cancellation and symbol-wise minimum mean-square error (MMSE) filtering both in the frequency domain to minimize the performance degradation caused by frequency-selective channels. After the...
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