Signaling And Signal Design Techniques For High Spectral Efficiency Digital Communications

High data rate is the common base to meet multiple communication requirements today. Since the bandwidth resource is expensive and scarce especially wireless spectrum resource, high spectral efficiency is needed to achieve high data rate. The problem of achieving high spectral efficiency reliable communications with lower cost is paid widely attention in the researches of modern digital communications. Based on overlapped multiplexing and access techniques, this thesis studies signaling techniques and signal design techniques for high spectral efficiency digital communications, includes zero correlation signal design and application, space zero correlation window pilot signal design in mnltiantenna OFDM systems and application, and the loss of the capacity caused by space zero correlation window pilot signal.Chapter II considers the zero-correlation signal design techniques and their applications in detection and estimation. In a wireless channel, the signals among multiple users interferes each other. Multipath introduces differences among times of arrival. So the orthogonal spread codes of traditional CDMA lose their orthogonality. Zero correlation codes can keep their orthogonality in multipath wireless channels, which achieves real interference-free transmission. The interference-limited system is then becomes noise-limited system and the complexity of detection is reduced. The thesis reviews the basic approach of zero correlation signals, and discusses the CDMA techniques based on zero correlation signals. This gives some base onⅢ the next chapter.Chapter III is a key part of this thesis. This chapter studies the space zero correlation window pilot signal design in multiantenna OFDM systems. This is a special application of zero correlation signals. But this also extend the meaning of zero correlation, i.e. from time zero correlation to space zero correlation. We introduces space zero correlation window to achieve pilot reuse in cellular networks to solve the problems of large number and cost of pilots in multiple antenna OFDM systems. We design a cyclic repeat structure of pilot, which limits the subcarrier occupied by the pilots to a small subset and the cost is minimized. Numerical results demonstrate that the pilot scheme is practical. Chapter IV applies the pilot scheme of Chapter III to LTE system, and introduces multiple practical design schemes. The performace of these schemes have very low MSE which is smaller than the existing schemes.Chapter V considers the loss of the capacity caused by space zero correlation window pilot signal. The overhead on the degree of freedom and power is an indirect measure of the cost of channel estimation. The direct measure, however, is the channel capapcity. We give the capacity loss caused by space zero correlation window pilot signal and its asymptotic behavior. At last, chapter VI reviews the thesis and gives some perspectives on future research.