Analytical computation of the correlation of spreading sequences for nonlinear OQPSK-type modulations

• Autor(a) principal: Dinis, Rui
• Data de Publicação: 2012
• Outros Autores: Afonso, Daniel, Cercas, Francisco, Rodrigues, Rui, Luz, Ângelo
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/11144/3728
• topic: PN sequences; Nonlinear modulations; Correlation behavior

In this paper we study the behavior and correlation properties of some spreading sequences when applied to a system using nonlinear offset quadrature phase-shift keying-type modulations. These signals, which include as special cases continuousphase modulation schemes, can be designed to have very low envelope fluctuations or even a constant envelope, making them compatible with a very low-cost and power-efficient grossly nonlinear amplification. We use an analytical method to derive the correlation of those signals. The resulting expressions are then applied to maximum-length sequences, Kasami, and Tomlinson, Cercas, Hughes sequences. It is shown that Tomlinson, Cercas, Hughes sequences have better correlation properties than other spreading sequences.