Wideband Time Frequency Coding

TL;DR

This paper introduces wideband time frequency coding, a novel modulation scheme that achieves near-capacity rates without channel state information by combining impulsive frequency shift keying and pulse position modulation, and demonstrates its robustness and superior performance in wideband channels.

Contribution

The paper proposes a new wideband modulation scheme that does not require channel state information and outperforms existing schemes in the wideband regime.

Findings

Achieves rates close to AWGN capacity without channel state information.

Robust to shadowing and fading channels.

Outperforms traditional modulation schemes in wideband regimes.

Abstract

In the wideband regime, the performance of many of the popular modulation schemes such as code division multiple access and orthogonal frequency division multiplexing falls quickly without channel state information. Obtaining the amount of channel information required for these techniques to work is costly and difficult, which suggests the need for schemes which can perform well without channel state information. In this work, we present one such scheme, called wideband time frequency coding, which achieves rates on the order of the additive white Gaussian noise capacity without requiring any channel state information. Wideband time frequency coding combines impulsive frequency shift keying with pulse position modulation, which allows for information to be encoded in both the transmitted frequency and the transmission time period. On the detection side, we propose a non-coherent decoder based on a square-law detector, akin to the optimal decoder for frequency shift keying based signals. The impacts of various parameters on the symbol error probability and capacity of wideband time frequency coding are investigated, and the results show that it is robust to shadowing and highly fading channels. When compared to other modulation schemes such as code division multiple access, orthogonal frequency division multiplexing, pulse position modulation, and impulsive frequency shift keying without channel state information, wideband time frequency coding achieves higher rates in the wideband regime, and performs comparably in smaller bandwidths.