Application Research Of CAZAC Sequence In LTE

In order to maintain the future competitiveness of the Third-generation (3G) in a ten-year, the Third Generation Partnership Project(3GPP) organization passed the 3G long term evolution (LTE)scheme in the end of 2004. The fundamental targets for LTE concern increased data rates, reduced latency, improved system capacity and coverage as well as reduced operator costs.Const Amplitude Zero Auto Correlation (CAZAC) sequences have the good characteristics of ideal periodic autocorrelation function, optimum crosscorrelation functions and low PAPR.CAZAC sequences are widely used in the field of pulse compression radars, Spread spectrum communication systems (such as Synchronous Code Division Multiple Access and Multi-Carrier Code Division Multiple Access / MC-CDMA), orthogonal frequency division multiplexing (OFDM) communication system; and are very useful in the key technologies of channel estimation, synchronization and spreading codes, etc. Thus the application research of CAZAC sequence in the LTE is of great significance.This thesis focuses on the application study of CAZAC sequence in LTE.Firstly, the scheme of physical layer technology and market prospect are introduced, especially the characteristics and application fields of CAZAC sequences. Secondly, the characteristics of CAZAC sequences are analyzed. The definition of four specific CAZAC sequence are given and five characteristics of CAZAC sequences are proved, taking example of Zadoff-Chu and generalized chirp-like (GCL) sequences. The time-domain and frequency detection principles of CAZAC are introduced, and it is proved that the two detection principles are equivalent by use of discrete cycle-related signal theorem.Thirdly, the application of CAZAC sequence in LTE random access is explained in detail. The purpose and process of LTE random access, the time-domain and frequency-domain structure of random access channel (RACH), the role of RACH preamble are introduced. The application of CAZAC sequence in the preamble design of LTE random access is introduced through the analysis of RACH preamble signal characteristics. Two existing RACH preamble detection algorithms are introduced, and new RACH preamble detection algorithms are proposed. The complexity and performance between them are analyzed. A new mechanism for random access is proposed, compared with the original mechanism, it has the advantage of shorter initial access delay and the lower probability of collisions.Then, the application of CAZAC sequences in the Acknowledge/Negative (ACK/NACK) controlling signaling is researched. Three user ID identification methods of LTE uplink signaling are given: code division multiplexing (CDM), time division multiplexing (TDM) and frequency division multiplexing (FDM) and the three multiplexing schemes are simulated. Based on CAZAC sequence, the design methods in different conditions are shown. Cyclic prefix added before CAZAC sequence is put forward. The accuracy of detection is increased in the condition of non-coherent detection. Meanwhile the design and performance curves of CAZAC sequence in the ON-OFF mode are also given. Finally, the application of CAZAC sequence in the other LTE aspects are summed up.