This thesis mainly focuses on the integration of Space-Time Block Coding (STBC) and Complementary Code based CDMA system. Our proposed integration systems have not only the merit of complementary code but also the extra advantage of diversity gain from STBC. Especially, when the different frequency channel gain has strong correlation, the complementary code will cancel most of interference. We also present a lot of improved structures for our proposed systems. We utilize special filters in receiver such as Zero-Forcing filter and Turbo Filter to assist complementary code in canceling interference.

In thesis, we design a new orthogonal complementary codes- columnwise complementary codes. Its advantage is: (1)As traditional orthogonal complementary codes, it has perfect orthogonal complementary property of auto-correlation and cross-correlation. (2)We can choose different type of columnwise complementary codes to restrain frequency selective fading and time selective fading. (3)Compared with complete complementary codes, it can support more users. (4)The generating method of columnwise complementary codes is easy to understand. (5)It can be used in multi-rate transmission system. (6)The generality: complete complementary codes and 2D OVSF codes are subsets of columnwise complementary codes. We also discuss its bit error rate in a frequency selective Rayleigh fading channel and a time selective fading channel by computer simulation.

Differential space time block coding is a technology that combining traditional space time block coding and differential coding. Differential space time block coding could exploit full spatial diversity gain where the channel state information is not known. Each user in CC-CDMA system is assigned a fold of codes which sent via different carriers to reconstruct perfect auto-correlation and cross-correlation function. Complete Complementary codes could offer MAI-free and MI-free operation for DS-spreading. In this thesis we combine differential space time block coding and CC-CDMA, and discuss the character of the system.

Zugl.: Erlangen, Nürnberg, Univ., Diss., 2008

Orthogonal frequency division multiplexing (OFDM) due to the robustness to the effect of multipath fading and having high spectral efficiency, it has become a good candidate of wireless communications systems. The block transmission of signal-blocks through the channel will suffer from the inter-block interference (IBI) and inter-symbol interference (ISI). Usually in the transmitter of the OFDM systems, redundancy (or guard interval), such cyclic prefix (CP) or zero padding (ZP), with sufficient length, is inserted in the transmitted block to avoid the IBI. In this thesis, we propose a novel pseudo random cyclic postfix (PRCP-) OFDM system configuration, which adopts the PRCP as redundancy and combines with multiple antennas. In fact, the multiple transmit antenna and multiple receive antenna, which exploits the spatial diversity, can be used to further enhance the channel capacity and achieve high data-rate. The main property of PRCP-OFDM modulation is that it exploits the cyclic-postfix sequences to estimate channel information with a low complexity method. Compared with CP-OFDM, it overcomes the channel null problem. For ZP-OFDM, it uses the additional information to estimate channel which is replaced by zero samples in ZP-OFDM. Moreover, PRCP-OFDM avoids the interference of signals to the desired postfix when we estimate channel impulse response (CIR) and which is different from pseudo random postfix (PRP-) OFDM [8]. Thus, as SNR grows, PRCP-OFDM can have better performance than PRP-OFDM. With the help of [9], [12] and [13], we extend the PRCP-OFDM to the MIMO case with space-time block coding. Via computer simulation, we verify that the performance is improved, in terms of the accuracy of channel estimation and symbol error rate (SER).

To effectively combat MAI and MI in wireless networks, we exploit complementary code technique in this thesis. Terminals in cooperative communication system are not only doing the transmission or relaying, but also involve a novel strategy "network coding" which has been investigated widely. In our work, we aim to combine network coding into the conventional cooperative communication system, but we face certain problems in it. Cooperative system has diversity at the destination, but when network coding operation involved, theoretically, it violate the rules of diversity, since the new signals transmitted by relay are no longer as same as the signals from sources. However, we discover a method to solve this problem, which is using the multiplier in relay nodes to replace the conventional network coding operation- XOR. After creating the network coding-based system, our goal is to achieve diversity in cooperative communication system. In this work, we use MRC (maximum ratio combining) for the performance analysis, which is the optimal strategy. Many math works will be shown in the following chapters.