Zadoff-Chu Sequence Based Random Access Sequence Set Design

Zadoff-Chu(ZC)sequences are used to generate random access sequences in LTE as well as NR systems due to their desirable correlation properties.The ideal correlation property of ZC sequences is in the absence of frequency offset,however,in actual wireless communication systems,frequency offset between transceivers exists objectively and cannot be avoided.The frequency offset can have an impact on the correlation characteristics of the ZC sequences and thus on the overall performance of the random access signal based on the ZC sequences.To address the problem of frequency offset in the existing random access signal detection,this thesis first investigates the effect of frequency offset on the correlation characteristics,and for the deviation causes the receiver to receive the sequence and the local sequence correlation value of energy attenuation and energy leak problem,a detection standard with frequency offset adaptability is proposed to solve the energy fading problem and improve the detection performance of ZC sequences when frequency offset exists.At the same time,the mathematical properties of root set and cyclic shift set optimization of random access sequence set based on ZC sequence are deduced,and according to the derived mathematical properties,a concrete feasible optimization scheme of random access signal set is designed.The details of the study are as follows:(1)The influence of frequency offset on the correlation characteristics of random access signals is studied.By studying the effect of frequency offset on the correlation values of received and local sequences,it can be concluded that the frequency offset will cause energy attenuation and energy leakage of the relevant values,which affects the detection performance of random access sequences.(2)The influence of frequency offset on the detection performance of random access signals is studied.Based on the analysis of the influence of frequency offset on the relative characteristics and detection performance of random access signals,a detection standard with frequency offset adaptability is proposed.Firstly,analysis of the causes of timing errors in ZC sequences within a given timing detection window is presented,and a solution to avoid timing errors is given,i.e.,the size of the cyclic shift deviation needs to be larger than the timing detection window.Then,the interference generated by the frequency bias on the transmitted sequence is analyzed to cause the undelivered sequence to be detected,resulting in a circular shift detection ambiguity problem.Based on the proposed detection standard with frequency skew adaptability and analysis of the influence of frequency skew on the correlation value of random access signal,and the mathematical properties of the root set and cyclic shift set parameters of the set of random access sequences based on ZC sequences are derived,which effectively solve the timing and cyclic shift detection fuzzy problem.(3)The design of root value set and cyclic shift set of ZC sequence is studied,and a design scheme of random access signal set under any given frequency offset scenario is proposed According to the mathematical properties of root-value optimization and cyclic shift optimization,the concrete steps of root-value set optimization and cyclic shift set optimization are proposed in this thesis within the given delay uncertainty and frequency deviation uncertainty.