Simplified processing for high spectral efficiency wireless communication employing multi-element arrays

TLDR

The study explores robust high‑scattering wireless links using multi‑element antenna arrays at both ends and proposes a simplified, spectrally efficient space‑time processing scheme. The scheme maps the user bit stream to a vector of independently modulated equal‑rate components transmitted simultaneously, and employs a multi‑user‑detection‑style algorithm in white Gaussian noise; a 1.9 GHz testbed with up to 16 QAM transmitters and 16 receivers implements this architecture. With many antennas the architecture can deliver up to about 40 % more capacity than a simple design; under ideal 18 dB SNR with 12 transmit and 16 receive antennas the theoretical spectral efficiency reaches 36 bit/s/Hz (≈200 billion constellation points at 5 % BLER), compared to the Shannon limit of 71.1 bit/s/Hz.

Abstract

We investigate robust wireless communication in high-scattering propagation environments using multi-element antenna arrays (MEAs) at both transmit and receive sites. A simplified, but highly spectrally efficient space-time communication processing method is presented. The user's bit stream is mapped to a vector of independently modulated equal bit-rate signal components that are simultaneously transmitted in the same band. A detection algorithm similar to multiuser detection is employed to detect the signal components in white Gaussian noise (WGN). For a large number of antennas, a more efficient architecture can offer no more than about 40% more capacity than the simple architecture presented. A testbed that is now being completed operates at 1.9 GHz with up to 16 quadrature amplitude modulation (QAM) transmitters and 16 receive antennas. Under ideal operation at 18 dB signal-to-noise ratio (SNR), using 12 transmit antennas and 16 receive antennas (even with uncoded communication), the theoretical spectral efficiency is 36 bit/s/Hz, whereas the Shannon capacity is 71.1 bit/s/Hz. The 36 bits per vector symbol, which corresponds to over 200 billion constellation points, assumes a 5% block error rate (BLER) for 100 vector symbol bursts.