Non-Redundant and Redundant Post Coding in OFDM Systems

Orthogonal Frequency Division Multiplexing (OFDM) provides a viable solution to communicate over frequency selective fading channels by converting them to an equivalent collection of flat fading channels. In doing so, OFDM systems fail to reap the benefits of diversity available in multi-path fading channels. To ameliorate this shortcoming of OFDM, explicit diversity in the form of redundant or non-redundant coding is needed. Their main goal in this paper is to explore different options for low complexity encoder design and compare their performance and complexity. Specifically, in the class of non-redundant codes they discuss the use of signal space diversity codes in OFDM systems.