Space-Time Diversity Schemes with Blind Channel Estimation for TH-PPM UWB MIMO Communications

Abstract

For a time-hopping (TH) pulse position modulation (PPM) based ultra-wideband (UWB) multiantenna system, we propose four coherent space-time (ST) diversity schemes, corresponding to which the correlation template signals with blind channel estimation are also presented. First of all, the issue of channel identifiability based on first-order statistics is addressed, aspired by the singleantenna case [1]. Then, we shed light on that the determination of space-time structure is related to both channel estimation and signal detection. After that, four ST diversity structures are presented to guarantee both the feasibility of blind channel estimation and no multi-antenna interference introduced into signal detection. Finally, substantial simulations show that the proposed ST diversity schemes can significantly outperform the traditional single-antenna system especially for high signal-tonoise ratios whether channel state information is perfect or not. Index Terms-Ultra-wideband; MIMO; blind channel estimation; first-order statistics; space-time diversity; coherent detection I. INTRODUCTION Recently, it comes to light that ultra-wide band (UWB) wireless communication has been the subject of extensive research due to its unique capabilities and potential applications. The most attractive point of UWB technology is the ultra-wide bandwidth, which brings about such-and-such advantages. UWB techniques are expected to be applied extensively in practical environments, e.g., wireless personal area networks (WPANS), sensor networks, imaging systems and vehicular radar systems so on [2]. Based on the different signal formats, the candidate transmission and detection methods for the physical layer of UWB communications include three categories: the single carrier impulse radio (IR) using the direct sequence technology introduced; the multiband OFDM technology supported by Multiband OFDM Alliance; a cyclic prefixed single-carrier technique using block transmission with frequencydomain equalization [3]. However, due to the ultra-low Manuscript