scholarly journals Forward and backward RLS-DDCE processing in MIMO-OFDM spatial multiplexing receivers

2010 ◽  
Vol 8 ◽  
pp. 101-107
Author(s):  
M. Muxfeldt ◽  
P. Beinschob ◽  
U. Zölzer
Keyword(s):  
Channel Estimation ◽  
Ldpc Code ◽  
Error Rates ◽  
Spatial Multiplexing ◽  
Recursive Least Squares ◽  
Likelihood Ratios ◽  
Novel Approach ◽  
Turbo Principle ◽  
Channel Information ◽  
Mimo Ofdm

Abstract. In this paper we present a novel approach in frequency domain channel estimation technique. Our proposal is based on the recursive least squares (RLS) algorithm combined with the decision making process called decision directed channel estimation (RLS-DDCE). The novelty and key concept of this technique is the block-wise causal and anti-causal RLS processing that yields two independent processing of RLS along with the associated decisions. Due to the implemented low density parity check (LDPC) code the receiver operates with soft information, which enables us to introduce a new modification of the Turbo principle as well as simple addition of the a-posteriori log-likelihood ratios (LLRs). Although the computational complexity is increased by both of our approaches, the latter is relatively less complex than the earlier. Simulation results show that these implementations outperform the simple RLS-DDCE algorithm and yield lower bit error rates (BER) and more accurate channel information.

scholarly journals Channel Estimation in MIMO-OFDM System

2014 ◽  
Vol 14 (2) ◽  
pp. 97-102
Author(s):  
SR Aryal ◽  
H Dhungana
Keyword(s):  
Channel Estimation ◽  
Mean Square Error ◽  
Minimum Mean Square Error ◽  
Multipath Fading ◽  
Spatial Multiplexing ◽  
Diversity Gain ◽  
Estimation Methods ◽  
Mean Square ◽  
Ofdm System ◽  
Mimo Ofdm

There are no limit of human desire, so day by day we need much higher data speed to facilitate our need but every physical resource like frequency band, transmit signal strength are finite. Within the given limited resource, higher data speed is accomplished by new proficiency called Multiple Input Multiple Output (MIMO), Orthogonal Frequency Division Multiplexing (OFDM) system. MIMO-OFDM fulfills the high data rate requirement through spatial multiplexing gain and improved link reliability due to antenna diversity gain. With this technique, both interference reduction and maximum diversity gain are achieved by increasing number of antennae on either side. Received signal in MIMO-OFDM system is usually distorted by multipath fading. In order to recover the transmitted signal correctly, channel effect must be estimated and repaired at receiver. In this paper the performance evaluating parameter mean square error and symbol error rate of least square error, minimum mean square error and DFT based channel estimation methods are estimated and appropriate solution is recommended. Furthermore, comparison among their characteristics is simulated in MATLAB and useful conclusion is delineated. DOI: http://dx.doi.org/10.3126/njst.v14i2.10421   Nepal Journal of Science and Technology Vol. 14, No. 2 (2013) 97-102

scholarly journals Joint Adaptive Blind Channel Estimation and Data Detection for MIMO-OFDM Systems

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Ruo-Nan Yang ◽  
Wei-Tao Zhang ◽  
Shun-Tian Lou
Keyword(s):  
Channel Estimation ◽  
Cost Function ◽  
Least Squares ◽  
Orthogonal Frequency Division Multiplexing ◽  
Blind Channel Estimation ◽  
Recursive Least Squares ◽  
Ofdm Systems ◽  
Blind Channel ◽  
Mimo Ofdm ◽  
The Cost

In order to track a changing channel in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems, it is a priority to estimate channel impulse response adaptively. In this paper, we propose an adaptive blind channel estimation method based on parallel factor analysis (PARAFAC). We used an exponential window to weigh the past observations; thus, the cost function can be constructed via a weighted least squares criterion. The minimization of the cost function is equivalent to the decomposition of a third-order tensor, which consists of the weighted OFDM data symbols. By preserving the Khatri-Rao product, we used a recursive least squares solution to update the estimated subspace at each time instant, then the channel parameters can be estimated adaptively, and the algorithm achieves superior convergence performance. Simulation results validate the effectiveness of the proposed algorithm.

scholarly journals Spatial Multiplexing MIMO-OFDM Systems Over Frequency Selective Channel

2019 ◽  
Vol 9 (1) ◽  
pp. 3128-3131
Keyword(s):  
Channel Estimation ◽  
Spatial Multiplexing ◽  
Ofdm Systems ◽  
Time Zone ◽  
Pilot Symbols ◽  
Channel Conditions ◽  
Selective Channel ◽  
Mimo Ofdm ◽  
Frequency Selective ◽  
Space Approach

Pilot symbols are huge utilized in countless functions what's more, principles. In conventional methodologies, Pilot images are multiplexed among actualities stream, bolstered friend uncommon example, on every single transmitter radio wire. Beginning evaluation channel is gotten by methods for pilot helped Least rectangular (LS) channel estimation the utilization of recurrence space approach. Recouped images are acquainted with enrich the channel gauge through time zone approach. The general execution proposed authority is incontestable utilizing contraption reproductions that are distributed below totally extraordinary channel conditions.

scholarly journals A Novel Multiuser Detection and Channel Estimation Method for Uplink Communication in MIMO-OFDM IDMA System

2019 ◽  
Vol 8 (12S) ◽  
pp. 934-938
Keyword(s):  
Channel Estimation ◽  
Multiuser Detection ◽  
Communication Systems ◽  
High Speed ◽  
Estimation Method ◽  
Cellular Communication ◽  
Communication Performance ◽  
Novel Approach ◽  
Reliable Performance ◽  
Mimo Ofdm

Demand of wireless cellular communication systems has grown rapidly which necessitates high speed and reliable communication for various multimedia applications. Several technologies have been introduced to meet the desired communication requirements such as 1G, 2G, 3G and 4G but these techniques suffer from multiple-access and interference issues. Hence in this work, we focus on these challenges to improve the cellular communication performance. The main objective of this work is to develop a novel approach for multiuser detection and introducing a new architecture of channel estimation. However, several techniques are present to achieve these objectives but computational complexity and reliable performance still remains an issue. Moreover, interference remains a challenging task. Hence, in order to overcome these issues, we present a joint approach of multiuser detection where we compute the LLRs, find the Gaussian distribution and measure the mean and variance of this distribution. Similarly, in next phase, channel estimation is performed with the help of ESE and DEC. The performance of proposed approach is measured in terms of BER for varied simulation configurations. The experimental analysis reported significant improvement in the performance of MIMO-OFDM IDMA system.

Improving Space-Time-Frequency MIMO-OFDM with ICI Self-Cancellation Scheme using Least Square Error Estimator

2015 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
Nur Farahiah Ibrahim ◽  
Zahari Abu Bakar ◽  
Azlina Idris
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Symbol Error Rate ◽  
Space Time ◽  
Least Square ◽  
Error Estimator ◽  
Frequency Diversity ◽  
Time Frequency ◽  
Mimo Ofdm ◽  
Subcarrier Mapping

Channel estimation techniques for Multiple-input Multiple-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) based on comb type pilot arrangement with least-square error (LSE) estimator was investigated with space-time-frequency (STF) diversity implementation. The frequency offset in OFDM effected its performance. This was mitigated with the implementation of the presented inter-carrier interference self-cancellation (ICI-SC) techniques and different space-time subcarrier mapping. STF block coding in the system exploits the spatial, temporal and frequency diversity to improve performance. Estimated channel was fed into a decoder which combined the STF decoding together with the estimated channel coefficients using LSE estimator for equalization. The performance of the system was compared by measuring the symbol error rate with a PSK-16 and PSK-32. The results show that subcarrier mapping together with ICI-SC were able to increase the system performance. Introduction of channel estimation was also able to estimate the channel coefficient at only 5dB difference with a perfectly known channel.

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