University of Oulu

Performance of multi-rate equalizer with lte standard turbo code

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Author: Du, Dongyang1
Organizations: 1University of Oulu, Faculty of Information Technology and Electrical Engineering, Department of Communications Engineering, Communications Engineering
Format: ebook
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 11.2 MB)
Persistent link: http://urn.fi/URN:NBN:fi:oulu-201405291605
Language: English
Published: Oulu : D. Du, 2014
Publish Date: 2014-06-02
Physical Description: 64 p.
Thesis type: Master's thesis (tech)
Tutor: Juntti, Markku
Reviewer: Juntti, Markku
Bayramoglu, Fatih
Description:

Abstract

In the uplink channel of the 3GPP long term evolution (LTE) and LTE-Advanced (LTE-A) systems, signal carrier frequency-division multiplexing access (SC-FDMA) transmission scheme is employed instead of orthogonal frequency-division multiplexing (OFDM) to reduce the peak-to-average power ratio (PAPR). However, compared to OFDM, SC-FDMA has lower channel throughput, since it suffers from inter-symbol interference (ISI). Multi-rate equalizer (MRE) is a novel low complexity and non-linear equalizer which can increase the channel throughput.

The basic idea of the MRE is that it first decomposes the single ISI channel into two parallel sub-channels by employing multi-rate signal processing and successive interference cancellation (SIC). Then, this decomposition procedure can be executed recursively to further increase the number of sub-channels. The ISI decreases as the number of sub-channels increases. Meanwhile, since the MRE does not require pre-coding, it does not increase PAPR. The practical implementation of the MRE is not straightforward. An algorithm, which can recursively call each function block in the MRE and execute the entire decomposition processes is required.

In this thesis, an algorithm is developed based on the construction pattern of the MRE to enable its realization. An LTE standard-compliant turbo code is simulated to evaluate the practical performance gains of the MRE concept. MATLAB is selected as the simulation environment. According to the simulation results, the channel throughput can be increased by employing the MRE together with LTE turbo code indeed. One time-invariant and one time-varying channel model are employed. Three kinds of MRE with binary modulation are considered. Those are the MRE with two, four and eight sub-channels. The increase in throughput is at least 25% and can reach 80% in highly frequency selective scenarios.

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