A 2x2 space-time code for noncoherent ultra wideband (UWB) communication systems with M-PPM and energy detection. (c2016)

Abstract

It is all about spectrum, the electromagnetic communication frequency spectrum characterizes the distribution of all the different wireless technologies approved by the Federal Communications Commission (FCC) and their emitted radiation power in a way that minimizes the interference between two or more wireless systems. All electronic communications compel a transmission medium to transmit the information from one location (transmitter) to another (receiver). In radio frequency (RF), the medium is free space. Today most of our electronic devices use the wireless channel for communication of either voice or data. In order to overcome interference between the numerous signals hovering in free space, each communication system should process its own allocated frequency band. As the request for higher capacity and faster services increases, new improved technologies have to find their room in the crowded spectrum. Ultra-wideband (UWB) technology provides a bright solution to the over populated RF spectrum by allowing new communication systems to coexist with the present radio with almost no interference. In order to increase the capacity with UWB systems to achieve high data rates, the use of space-time coding (STC) with Multiple Input Multiple Output (MIMO) systems is considered. This can be realized by transmitting independently and simultaneously several symbols over different time intervals due to the antenna diversity introduced with MIMO systems. In this work, we present a noncoherent space-time block code based on a coherent one discussed in the literature for M-PPM modulation associated with Impulse-Radio Ultra-Wideband (IR-UWB) systems where neither the receiver nor the transmitter has knowledge of the channel’s parameters. The proposed scheme takes advantages of the Multiple Input Multiple output (MIMO) system and achieves a full transmit diversity with two transmitters at the cost of a reduced coding rate while being shape preservative and totally real. The main advantage resides in a compelling adaptability to simple energy detection bypassing involved analog to digital conversion.