A scalable family of unitary and differential space-time codes for ultra wideband communications. (c2014)

Abstract

Higher data rates have always been the main demand ever since the emergence of telecommunications. This quest for faster and more reliable communications has led to the evolution of numerous generations of wired and wireless communication. One of the most recent and most promising wireless technologies is the Ultra Wideband (UWB) communication. This technology, associated with the usage of Multiple Input Multiple Output (MIMO) techniques and Space Time (ST) codes, can be considered as the future for short-range wireless communications. Following from the excessive delay spreads of the UWB channels, channel estimation is rather challenging and, consequently, coherent solutions are being slowly disregarded shifting the focus to differential techniques. While the literature related to coherent ST codes for UWB is quite rich, limited contributions targeted the more challenging problem of differential ST codes. In this work, we propose a novel unipolar ST code for UWB. The proposed technique can be completely implemented in an analog manner while still ensuring full spatial diversity. Being differential and unitary, the presented system further guarantees the optimal detectability of the received signals without any need for channel estimation. The above features keep the system complexity at a minimum while ensuring full reliability. In addition, the proposed codebook can be partitioned into a number of sub-codebooks with predefined structure resulting in additional scalability capabilities that provide a compromise between data rate and decoding complexity.