An improved synchronization algorithm for OFDM based powerline communication

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) is a promising technology for combating the frequency selective fading, multipath propagation, and narrowband interference in power line communication. However, OFDM systems are extremely sensitive to synchronization deviation. Slight synchronization deviation can affect the performance of OFDM systems. This paper presents a design and implementation synchronization algorithm based on constant amplitude zero auto-correlation (CAZAC) for power line communication. Matlab simulation prove that, with less computation, the proposed algorithm can complete symbol timing synchronization and frequency offset synchronization well and the performance of OFDM synchronization in power line communication is significantly improved. I. INTRODUCTION With the development of smart grid, power line communication technology has become one of the important techniques for smart grid construction. In order to improve transmission rate and reliability of the power line communication system, appropriate modulation and demodulation scheme should be used in power line communication. Orthogonal Frequency Division Multiplexing (OFDM)is an efficient modulation and multi-carrier transmission technology, and it has many advantages, such as high spectrum efficiency, excellent resistance to multipath propagation and fading ability, At the same time, it can also be effective against frequency selective fading, multipath propagation and noises in power line communication(PLC). OFDM systems not only sensitive to frequency offset and symbol timing error but also exceptionally strict orthogonality of sub-carriers. The orthogonality will be destroyed by small frequency offset; then the inter-channel interference (ICI) is introduced in the system that will cause the performance of OFDM systems sharp deterioration [1][2].The frequency offset is divided into integer frequency offset (IFO) and fractional frequency offset (FFO) by sub-carrier interval [3]. The fractional part will cause ICI, and the influence of integer part is reflected in the cyclic shift of output subcarrier [4].The data phase will be rotated when timing error exist in OFDM system, as a result, the inter-symbol interference (ISI) will be introduced. Therefore, accurate timing and frequency offset estimation are key issues in OFDM systems.

Diseño de estrategias de sincronización y estimación de canal para la mejora de comunicaciones en redes inteligentes de energía

“…En esa línea, en [Xie 2013] se propone la sincronización de un sistema OFDM-PLC a partir de una métrica AC que, recordando (2.16), se puede escribir de manera general como: Capítulo 2: Estado del arte y objetivos planteados El diseño del símbolo piloto consiste en la utilización de una secuencia ZC de longitud y el arreglo [ ], donde es la secuencia ZC, y . A partir de la estructura del símbolo piloto, se propone el cómputo la métrica :…”

“…Tanto para la etapa de sincronización como para la estimación de canal, se suelen diseñar símbolos piloto a partir del uso de secuencias con buenas propiedades de correlación (CAZAC [Xie 2013], CPS [Moya 2016b], CSS ], etc.). Si bien la problemática fue estudiada ampliamente para sistemas OFDM inalámbricos, las particularidades del canal PLC condujeron recientemente al desarrollo de estrategias de sincronización y estimación de canal específicas que atiendan a sus características.…”

“…Con respecto a la etapa de sincronización en sistemas PLC, algunos trabajos optan por técnicas de sincronización basada en autocorrelación [Xie 2013] [Liu 2013] [Wu 2014].…”