Interleaved FDMA — A New Spread-Spectrum Multiple-Access Scheme

In this paper, a new spread-spectrum multiple-access scheme applicable for both the uplink and the downlink of a mobile radio communications system is proposed, which is termed “Interleaved Frequency-Division MultipleAccess”. This new scheme can be viewed as a special kind of a multicarrier spread-spectrum multiple-access scheme, since each user is assigned a different set of orthogonal frequencies. The orthogonality between the different users is maintained at the receiver, even in time-dispersive channels. Thus, there is no multiple-access interference. However, the cost to avoid multiple-access interference is to allow for intersymbol interference and therefore an equalization is required at the receiver. This article describes the new spread-spectrum multiple-access scheme as well as the optimum receiver structure.