Intersymbol and Intercarrier Interference in OFDM Transmissions Through Highly Dispersive Channels

Abstract

This work quantifies, for the first time, intersymbol and intercarrier interferences induced by very dispersive channels in OFDM systems. The resulting achievable data rate for suboptimal OFDM transmissions is derived based on the computation of signal-to-interference-plus-noise ratio for arbitrary length finite duration channel impulse responses. Simulation results point to significant differences between data rates obtained via conventional formulations, for which interferences are supposed to be limited to two or three blocks, versus the data rates considering the actual channel dispersion.

Formulation and Performance Analysis of Broadband and Narrowband OFDM-Based PLC Systems

“…The functional blocks of this Figure are characterized by matrices, which are described in Table 2 and formulated below. The proposed matrix description is based on [ 27 , 28 ], and it includes some novelties, such as the phase shifting stage or the tone mask block. To the best of the authors’ knowledge, they have not been previously formulated using matrices, as well as their application to NB and BB PLC systems.…”

“…The conveyed signal is transmitted over the PLC channel, and becomes contaminated by PLC noise. The number of transmitted data vectors that affect the received signal is [ 27 , 28 ], where …”

“…Then, the received signal is given by where has entries [ 27 , 28 ] with , , , and represents the channel noise.…”

“…This input–output relation is used in our computer simulations to obtain the BER. Furthermore, considering the analysis presented in [ 27 ], and including the matrices that distinguish the windowed PLC system from the conventional OFDM, it is possible to calculate the powers of the signal, interference and noise, and from the previous ones, the signal-to-interference-plus-noise ratio and the achievable data rate.…”

“…The aim of this article is to formulate the digital front-end blocks of the PHY detailed in [ 16 , 17 ] and, in addition, to analyse and to compare the performance of four possible implementations (detailed in Table 1 ). Based on [ 27 ], we first provide a general matrix description of the windowed OFDM, but also including specific blocks defined in PLC systems that make the formulation applicable to BB and NB transceivers. As case studies, we provide the values of each matrix following the parameters defined in the PHY specifications of the BB and NB standards.…”