Multi-Carrier and Spread Spectrum Systems describes and analyses the basic concepts of the combination of multi-carrier transmission with spread spectrum (MC-SS). The various architectures and the different detection strategies are examined in some depth. Techniques for capacity and flexibility enhancement of multi-carrier systems such as diversity techniques and space-time/frequency coding (STC, STFC) are also analysed.
Since 1993 different multiple access concepts based on the MC-SS combination for mobile and wireless indoor communications called OFDM/CDMA or MC-CDMA and MC-DS-CDMA, have been proposed. The main differences between these schemes are in the spreading, frequency mapping, and detection strategies. Meanwhile, other alternative hybrid schemes such as OFDM/OFDMA, MC-TDMA, etc. have been deeply studied that benefit from the advantages of multi-carrier transmission.
The common feature of the next generation wireless technologies will be the convergence
of multimedia services such as speech, audio, video, image, and data. This implies that
a future wireless terminal, by guaranteeing high-speed data, will be able to connect to
different networks in order to support various services: switched traffic, IP data packets
and broadband streaming services such as video. The development of wireless terminals
with generic protocols and multiple-physical layers or software-defined radio interfaces is
expected to allow users to seamlessly switch access between existing and future standards.
The rapid increase in the number of wireless mobile terminal subscribers, which currently
exceeds 1 billion users, highlights the importance of wireless communications in
this new millennium. This revolution in the information society has been happening, especially
in Europe, through a continuous evolution of emerging standards and products by
keeping a seamless strategy for the choice of solutions and parameters. The adaptation of
wireless technologies to the user’s rapidly changing demands has been one of the main
drivers of this revolution. Therefore, the worldwide wireless access system is and will
continue to be characterized by a heterogeneous multitude of standards and systems. This
plethora of wireless communication systems is not limited to cellular mobile telecommunication
systems such as GSM, IS-95, D-AMPS, PDC, UMTS or cdma2000, but also
includes wireless local area networks (WLANs), e.g., HIPERLAN/2, IEEE 802.11a/b and
Bluetooth, and wireless local loops (WLL), e.g., HIPERMAN, HIPERACCESS, and IEEE
802.16 as well as broadcast systems such as digital audio broadcasting (DAB) and digital
video broadcasting (DVB).