Combination of OFDM and spread spectrum for high data rate UWB: optimization of the spreading length

Emeric Guéguen (1) , Matthieu Crussière (2) , Jean-François Hélard (2)

1 IETR - Institut d'Electronique et de Télécommunications de Rennes
2 IETR - Institut d'Électronique et des Technologies du numéRique

In this paper we investigate a new waveform based on Spread Spectrum Multi-Carrier Multiple Access (SS-MC-MA) for Ultra Wide Band (UWB) systems obtained by the combination of Orthogonal Frequency Division Multiplexing (OFDM) and Code Division Multiple Access (CDMA). This system is a great solution to combat frequency selectivity and narrowband interferers, and to manage the coexistence of several users and piconets. It also brings an interesting degree of freedom since the spreading codes of SS-MC-MA allow to optimize jointly the assignment of the number of used codes and the coding rates. We proposed methods to limit the Self-Interference (SI) between the spreading sequences by a judicious positioning of the subcarriers which carry spread data, and a selection of the spreading codes. The effect of the spreading code length is studied and shows that the code length has to be increased when the code rate gets higher to optimize the system performance. Through simulations it is demonstrated that the new UWB system outperforms the well known Multi-Band OFDM Alliance (MBOA) one.

Mots clés: UWB; MB-OFDM; SS-MC-MA; spreading length optimization; self-interference

Domaines: Traitement du signal et de l'image [eess.SP]; Traitement du signal et de l'image [eess.SP]

Emeric Guéguen, Matthieu Crussière, Jean-François Hélard. Combination of OFDM and spread spectrum for high data rate UWB: optimization of the spreading length. 2007 IEEE International Conference on Ultra-WideBand, Sep 2007, Singapour, Singapore. pp.889-894, ⟨10.1109/ICUWB2007.4381070⟩. ⟨hal-00189219⟩