Analysis and Simulation of a Digital Mobile Channel Using Orthogonal Frequency Division Multiplexing

TLDR

The study analyzes and simulates an OFDM‑based technique to mitigate multipath propagation and cochannel interference in narrow‑band digital mobile channels, employing interpolated pilots for heavily frequency‑selective environments. The method employs a DFT‑based OFDM system that orthogonally multiplexes many low‑rate subchannels into a high‑rate channel, using interpolated pilots and a frequency‑offset reference scheme to counter frequency‑selective fading and cochannel interference. Pilot‑based correction significantly mitigates flat Rayleigh fading, yields a 6 dB SIR improvement over bursty Rayleigh channels, and the low‑rate subchannels offer additional protection against delay spread.

Abstract

This paper discusses the analysis and simulation of a technique for combating the effects of multipath propagation and cochannel interference on a narrow-band digital mobile channel. This system uses the discrete Fourier transform to orthogonally frequency multiplex many narrow subchannels, each signaling at a very low rate, into one high-rate channel. When this technique is used with pilot-based correction, the effects of flat Rayleigh fading can be reduced significantly. An improvement in signal-to-interference ratio of 6 dB can be obtained over the bursty Rayleigh channel. In addition, with each subchannel signaling at a low rate, this technique can provide added protection against delay spread. To enhance the behavior of the technique in a heavily frequency-selective environment, interpolated pilots are used. A frequency offset reference scheme is employed for the pilots to improve protection against cochannel interference.