Abstract
Orthogonal frequency division multiplexing (OFDM) plays an important role in power-line communications (PLC), due to its robustness to frequency-selective channels. Nevertheless, it also presents some persistent drawbacks over the years, some of them related to the synchronization and channel estimation and equalization, whose features are a key aspect in the global performance of the medium access technique. This work presents a novel timing synchronization and channel estimation method for OFDM under PLC conditions. Typical joint fine synchronization and channel estimation techniques for OFDM make use of the cross correlation from a transmitted pilot symbol with suitable correlation properties. However, these proposals often present the drawback of having a high computational load, sometimes reducing the feasibility of later practical implementations. Our proposal takes advantage of the properties of complementary pairs of sequences, as they provide good correlation properties, as well as efficient algorithms for generation and correlation. Furthermore, some practical thresholds for synchronization are derived, which adapt the system to the current signal-to-noise ratio and channel conditions. Finally, all the theoretical proposals have been validated by simulation, including an analysis of the performance achieved.
Highlights
Power-Line Communication (PLC) is an alternative that makes use of the existing mains as a communication channel, as a solution for In-Home data services and Smart Grids development [1]
The channel coefficients are assumed to remain constant during each burst, and 200,000 channel realizations are simulated for each signal-to-noise ratio (SNR) condition
This paper is focused on the synchronization problem in Orthogonal frequency division multiplexing (OFDM) systems for power-line communications
Summary
Power-Line Communication (PLC) is an alternative that makes use of the existing mains as a communication channel, as a solution for In-Home data services and Smart Grids development [1]. M. Colombo et al.: Low-Complexity Joint Time Synchronization and Channel Estimation for OFDM-Based PLC Systems techniques have been developed by exploiting some correlation properties of well-designed pilot symbols [11], either by computing an auto correlation (AC) of the received signal or by cross correlation (CC) between the received signal and a template of the known pilot symbols [12], [13]. In AC-based techniques the pilot symbols present symmetrical parts, a normalized timing metric is defined, and the synchronization point is obtained from its maximum [14]–[16] They present low complexity, as recursive formulas are used for their computation.
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