Abstract:
In this paper, we introduce a novel multiple access
scheme based on a combination of a multi-levelled modem and
multi-carrier techniques with the use of complete complementary
codes. This modulation technique combines a multi-dimensional
code division multiple access (CDMA) modem with recent designs
of perfectly complete complementary orthogonal codes.
The rotational properties of the spreading codes are further
exploited to improve the modulation technique, throughput,
spectral efficiency, and capacity. Additionally, the system is
extended by making use of multiple carrier frequencies as in
OFDM, with the additional benefits of being able to spread
data in frequency and/or in time. The modem offers multiple
access interference MAI-free and multipath interference MI-free
operation in both asynchronous and synchronous communication,
due to perfect autocorrelation and zero cross-correlation properties
of the spreading codes. The unique multi-levelled multiple
access modulation technique together with the integration of
complete complementary codes, produces a spectrally efficient
output signal with high data throughput rates, better noise
tolerances in harsh channel conditions and an increased user
capacity.
