Reducing Phase Offset Using Novel Adaptive Cyclic Prefix Based Adaptive Sub Block Correlation for BWA Networks

Abstract

In this paper, a generic approach has been developed for the reduction of phase offset in BWA networks considering a novel Adaptive Cyclic Prefix (ACP) and Adaptive Sub Block (ASB) correlation computation for both WiMAX and LTE networks. The successive design steps along with practical assumptions and mathematical derivations are incorporated in developing the ACPASB algorithm. In comparison to the conventional Fixed Sub Block (FSB) mechanism, the ACPASB algorithm improves the correlation among the subcarriers by drastic reduction of phase offset, leading to maximum removal of Inter Symbol Interference (ISI). The index for reduction of phase offset is evaluated in terms of increased estimated correlation factor (η) for which the correlation threshold (ηth) has been determined using Pearson Product Moment formula and specific degree of freedom (df). Estimated ηth serves as an indicator of maximum ISI free region. The estimation of phase offset is accomplished by the measurement of Error Vector Magnitude (EVM) and Relative Constellation Error (RCE) with the help of Vector Signal Analyzer (VSA) incorporated in the model of WiMAX/LTE transceiver. The data transmission with such minimum ISI, guarantees the selection of highest order modulation and coding scheme (64-QAM (3/4)) even under severe degradation of the channel in a typical BWA network. It has alsobeen observed that even under severely fading channel, the selection of dynamic sub-block length inherently delivers a substantially good Raw Data Rate (RDR) under 64-QAM (3/4) modulation. Complexity analysis and simulation results show that ACPASB scheme outperforms ACPFSB thereby saving design turnaround time significantly.