Hpsk Modulation Technology Improved

As the development of communications technology and mobile communication, modulation techniques are also constantly updated development. There has appeared a variety of new modulation techniques, From the traditional ASK, FSK, PSK, DPSK, QPSK to laterπ/4QPSK, DQPSK, QAM, OQPSK and so on. The HPSK modulation technique newly proposed which is based on a variety of modulation techniques has the advantages of traditional modulations and overcome its shortcomings. HPSK modulation technology will not only reduce the signalπphase transition, reducing the signal PAPR, but also can transmit multiple signals, it uses Walsh code as the channel address code, spreading spectrum signals, using a complex scrambling code to reduceπphase transition, the last method using QPSK to modulate complex scrambling code. This method is widely used in CDMA2000 reverse link.QPSK has characteristics of a strong anti-interference ability, low bit error rate, and higher spectrum efficiency, and OQPSK completely eliminateπphase transition, and has small signal envelope fluctuations and small power spectral density of sidelobes and other features. In this text, these two methods were simulated and compared. Although OQPSK can eliminateπphase transition of signal, it can only transmit a single signal. HPSK uses walsh code as the channel address code, settling this problem, and reduce the probablity ofπphase transtion. The second section of this text analyses the method of reducing theπphase transtion.Based on this, in addition this text introduces the concept of smoothing filter in order to further optimize the performance of the system, and improve the utilization of the spectrum. Smoothing filter is divided of time domain filter and frequency domain filter, the methods to these are filter method and smooth function method. In this texe, we have done some simulations of the two methods, and compared them from waveform, power spectral density and BER. Then we conclude that the smooth function method is more excellent than filter method.In addition, we have done some study of complex scrambling code, analysing the theory of walsh code, introducing the concept of orthogonal matrix, and lead the theory to HPSK modulation technology. We also introduced PN sequence, and proposed an improved method of PN sequence for HPSK modulation.This method further reduced the probablity of 0 phase transtion and n phase transtion, which makes the further reduction of PAR, and the function of HPSK modulation will be more excellent.At last, we have introduced FPGA and the usage of quartus, in addition, we have also do some simply simulations of HPSK based on FPGA.