Research On Broadband Wireless Communication Detection Technology Based On Improved CP

Orthogonal frequency division multiplexing（OFDM）technology uses circle prefix（CP）resist inter symbol interference（ISI）and inter carrier interference（ICI）caused by multipath fading.However,the length of CP cannot be lower than the maximum delay spread,which causes the waste of spectrum resources in high rate and high delay scenarios.Therefore,in order to adapt to the development trend of high rate,high spectrum efficiency and large capacity of future wireless mobile communication,it is essential to improve the spectrum efficiency of CP.In view of the above problems,based on the objective of spectrum efficiency optimization of CP-assisted OFDM system,this thesis studies a variety of improved CP transmission methods,including serial multipath interference cancellation（SMIC）based on time domain precoding（TDP）,interference elimination based on add alignment signal（Add-AS）and interference elimination based on hybrid prefix（HP）.In addition,this thesis also introduces the idea of HP into TDP-SMIC and Add-AS algorithms,and proposes TDP based hybrid cycle prefix algorithm and Add-AS based hybrid cycle prefix algorithm,namely TDP-HCP and Add-AS-HCP algorithms.In single-antenna and multi-antenna scenarios,this thesis evaluates the above algorithms from the aspects of bit error rate performance and operation complexity: compared with TDP-SMIC and Add-AS algorithms,improves the applicability and bit error rate performance,reduces the operation complexity,and solves the error propagation problem of TDP-SIMC algorithm;compared with interference elimination algorithm based on HP,the spectrum efficiency of CP is further improved.Then,in order to relieve the shortage of frequency spectrum resources of HF communication,this thesis applies TDP-HCP algorithm to HF communication and proposes hybrid probe（HP）interference elimination algorithm based on TDP.By reducing the proportion of probe frequency by 50%,the frequency spectrum efficiency of the system is improved.In addition,in order to combat the bad multipath fading and doppler shift in HF channels,this thesis studies four Turbo equalization algorithms,and analyzes and verifies the above algorithms from the aspects of computational complexity and bit error rate performance.It is proved that the Turbo equalization algorithm based on time domain is more suitable for the bad HF channels.Finally,based on MIL-STD-188-110 C appendix D protocol,this thesis improves the traditional useless path deletion algorithm and proposes a new useless path deletion method based on statistical probability,which further reduces the influence of noise on channel estimation and improves the bit error rate performance of the system.