Estimation of Semi-Blind Channel for Two-Way Relay by Using CRB: Pilot-based and Random Pilot-based

Abstract

The main purpose of semi-blind channel estimation scheme is for frequency-selective channel estimation, for multi-input and multi-output (MIMO) on relay networks, for using high bandwidth efficient use of spectrum. This scheme motivate to the low complexity of system to allow exchange information users to users by using an intermediate relay node. Because of superposition of signals at the relay node, section receiving signal at the user terminals is affected by multiple impairments, i.e., channel gains, timing offsets, throughput, modulation error rate and carrier frequency offsets that need to be estimated and compensated in the channel section. We derived semi-blind estimator which is based on the Gaussian maximum likelihood (GML) criterion using of CRBs based and random pilot, and using data symbols for Gaussian-distributed nuisance parameters. In estimation of the individual channels, we adopt a superimposed pilot symbols strategy on a relay. Main estimation is designed for pilot-based vectors of the terminal section and Cramer-Rao bounds on relay to optimize the estimating performance. Furthermore, we derived the semi-blind and pilot-based Cramer-Rao bounds (CRBs) to characterize the mean squared error (MSE) performance of semi-blind channel estimation schemes and comparison between both CRB and random pilot-based. Finally, we demonstrate simulation result to show that the proposed method provides substantial improvements in estimation accuracy over the conventional pilot-based estimation and that it approaches the semi-blind CRB and random pilot-based estimation. Simulation results show that the performance of the proposed estimators is very close to the derived semi-blind CRLBs and random pilot-based achieves significantly lower MSE compared to other estimation.

Keywords: MIMO (multiple-input multiple-output), CRB (Cramer-Rao bounds), GML (Gaussian maximum likelihood), MSE (mean squared error), TWRN (two-way relaying network)

Cite this Article
Hemant Gavaskar, Neetendra Singh Dhakad. Estimation of Semi-Blind Channel for Two-Way Relay by using CRB: Pilot based and Random Pilot Based. Current Trends in Signal Processing. 2017; 7(2): 22–31p.