-To achieve high data rate Multi-Carrier Code Division Multiple Access (MC-CDMA) is a suitable choice for next generation wireless communication system. MCCDMA is the combination of CDMA and OFDM schemes along with receiver diversity including cyclic prefix and zero padding, resulting into getting the advantages of all of these schemes. Capacity improvement is one of the major issues in designi...

We investigate rotated Walsh-Hadamard spreading matrices for a broadband MC-CDMA system with robust channel estimation in the synchronous downlink. The similarities between rotated spreading and signal space diversity are outlined. In a multiuser MC-CDMA system, possible performance improvements are based on the chosen detector, the channel code, and its Hamming distance. By applying rotated sp...

The adaptation of wireless technologies to the users rapidly changing demands is one of the main drivers of the wireless access systems development. New high-performance physical layer and multiple access technologies are needed to provide high speed data rates with flexible bandwidth allocation, hence high spectral efficiency as well as high adaptability. Multi carrier-code division multiple a...

In the context of spectrum surveillance, a new method to recover the code of spread spectrum signal is presented, while the receiver has no knowledge of the transmitter’s spreading sequence. In our previous paper, we used Genetic algorithm (GA), to recover spreading code. Although genetic algorithms (GAs) are well known for their robustness in solving complex optimization problems, but nonethel...

Multi-Carrier CDMA systems appear to be a good candidate for high speed wireless data transmission. These systems avoid time domain equalization and have the capability of achieving high diversity gains over frequency selective fading channels. Orthogonal Walsh-Hadamard spreading waveforms have been commonly considered for these systems. However, reliable system performance over frequency selec...

Reverse link performance analysis in singlecode and multi-code CDMA systems is presented. Results show that the single-code system yields better performance than does the multi-code system in terms of link capacity and signal power. This improvement increases as spreading bandwidth is reduced and the number of spreading codes assigned to a user is increased. key words: link capacity, signal pow...

This dissertation research concerns a novel self-encoded spread spectrum. It provides a feasible practical implementation for random spreading codes. The traditional transmit and receive PN code generators are not needed. Instead, the spreading codes are extracted from the user's information bits itself. Comparing to conventional CDMA, SESS completely abandons the use of pseudo-random spreading...