Article ID: | iaor20052004 |
Country: | Netherlands |
Volume: | 133 |
Issue: | 1 |
Start Page Number: | 249 |
End Page Number: | 264 |
Publication Date: | Jan 2005 |
Journal: | Annals of Operations Research |
Authors: | Nordholm Sven, Nordberg Jrgen, Dam Hai Huyen, Zepernick Hans-Jrgen |
Keywords: | programming: mathematical |
The performance of a code division multiple access system depends on the correlation properties of the employed spreading code. Low cross-correlation values between spreading sequences are desired to suppress multiple access interference and to improve bit error performance. An auto-correlation function with a distinct peak enables proper synchronization and suppresses intersymbol interference. However, these requirements contradicted each other and a trade-off needs to be established. In this paper, a global two dimensional optimization method is proposed to minimize the out-of-phase average mean-square aperiodic auto-correlation with average mean-square aperiodic cross-correlation being allowed to lie within a fixed region. This approach is applied to design sets of complex spreading sequences. A design example is presented to illustrate the relation between various correlation characteristics. The correlations of the obtained sets are compared with correlations of other known sequences.