In this paper, we propose a multicarrier spread spectrum (MC-SS) waveform for high data rate UWB applications, taking into account the American and the European UWB contexts. This new waveform for UWB is presented as an evolution of the well known Multiband OFDM Alliance (MBOA) solution and does not increase the system complexity significantly. First, we optimize the number of spreading codes to maximize the system range for a fixed QPSK constellation. Secondly, we use variable constellation orders and we propose a low-complexity resource allocation algorithm that maximizes the system throughput. We show that our adaptive MC-SS system transmits information at much higher attenuation levels and with higher throughput compared to the MBOA solution, and can be advantageously exploited for UWB applications.Index Terms -Multiband OFDM, multicarrier spreadspectrum (MC-SS), resource allocation, UWB.

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International audienceIn this paper, we investigate the use of multiple-input multiple-output (MIMO) techniques with a linear precoded orthogonal frequency division multiplexing (LP-OFDM) waveform, known as spread-spectrum multicarrier multiple-access (SS-MC-MA), for high data rate ultra-wideband (UWB) systems. This scheme is an evolution of the well-known multiband OFDM (MB-OFDM) solution supported by the WiMedia Alliance. The aim of this paper is to improve the UWB system range while not significantly increasing the system complexity compared to the WiMedia solution. Firstly, an analytical study of the single-input single-output (SISO) LP-OFDM waveform allows to find how to efficiently precode an OFDM signal in order to improve the system range. To go further and exploit the available spatial diversity, a MIMO component is added and a new geometric statistic MIMO channel model is considered. Secondly, a global MIMO LP-OFDM system study is led to highlight the benefits of combining MIMO and LP techniques for UWB applications. The analytical and simulation results show that the joint use of MIMO and LP-OFDM leads to a significant range improvement compared to the WiMedia solution

Abstract-Ultra-wideband (UWB) is a fast emerging technology that has attracted considerable interest in short range, high data rate wireless personal area networks (WPAN) applications. One of the main candidates for WPAN standardization is the multiband orthogonal frequency division multiplexing (MB-OFDM), supported by the Multiband OFDM Alliance (MBOA). In this paper, we propose a new lowcomplexity resource allocation algorithm applied to a spread spectrum multicarrier multiple-access (SS-MC-MA) waveform, which is new for high data rate UWB applications. The proposed scheme aims at maximizing the system's throughput while taking into consideration the WPAN environment and respecting the OFDM parameters of the MBOA solution. The adaptive allocation algorithm applied to OFDM and SS-MC-MA leads to roughly double the throughput compared to the MBOA solution at low attenuation levels. Furthermore, at high attenuation levels, SS-MC-MA outperforms the adaptive OFDM. Hence, we conclude that the proposed adaptive SS-MC-MA can especially be advantageously exploited for high attenuation UWB applications.Index Terms-Information theory, multicarrier codedivision multiple-access (MC-CDMA), resource allocation, spread spectrum, ultra-wideband technology, wireless communications.

Abstract-In this paper, we investigate the use of multipleinput multiple-output (MIMO) techniques with linear precoded orthogonal frequency division multiplexing (LP-OFDM) waveform for high data rate ultra-wideband (UWB) systems. This scheme is an evolution of the multiband OFDM (MB-OFDM) solution supported by the WiMedia Alliance. The aim of this paper is to obtain a very high data rate of around one gigabit for home access networks (HAN) and to improve the system range for lower data rates, while not significantly increasing the system complexity compared to the WiMedia solution. Firstly, a singleinput single-output (SISO) LP-OFDM system study is led to highlight the benefits of adding a precoding function to an OFDM signal in the UWB context. In an analytical study, different system choices and parameterization strategies are proposed in order to minimize the mean bit-error-rate (BER) and consequently improve the system range. Secondly, a MIMO scheme is added and global system simulations are performed on a proposed new geometric statistic MIMO channel model. We show that the proposed system can considerably improve the system range at low data rates, and can reach very high data rates up to 1 Gbit/s with comparable BER performances to WiMedia.