Frequency Domain Composite OFDM Modulation Method For Communication And Navigation Integrated Signal

With the rapid development of society,Location Based Service have gradually developed into one of the basic needs of people and it has huge market prospects.At present,powerful countries are constantly developing and perfecting their own satellite positioning systems to achieve high-precision outdoor positioning services,such as the US GPS,China's Beidou and so on.However,the satellite navigation signals arrived at the ground are very weak and cannot meet the positioning needs of indoor and other human active places.Terrestrial wireless communication is ubiquitous and has a very similar technical basis with wireless navigation,it is a cost-effective technical way to realize ubiquitous positioning service based on signal level integration.This paper studies the fusion method of communication and navigation signals from the perspective of signal modulation.Different from traditional navigation signals,the proposed method applies spread spectrum sequences to frequency domain modulation and combines with OFDM in communication systems to achieve good compatibility.Since the composite process of the navigation signal spreading sequence and the communication symbol is performed in the frequency domain,the method proposed in this paper is called frequency domain composite OFDM modulation.First,the paper describes a similar solution TC-OFDM as a reference for performance analysis.Then,the basic principle and generation method of frequency composite OFDM modulation are described in detail,and it analyzed the compatibility between communication signal components and navigation signal components theoretically.The theoretical analysis contain the equivalent carrier-to-noise ratio of the navigation signal under the communication signal interference condition and the influence of the navigation signal on the demodulation error rate of the communication signal.Finally,the signal receiving method is given and compared and verified by simulation and reference scheme.Aiming at the new navigation signal components,it proposed three receiving modes which are time domain correlation method,forced level conversion method and frequency domain correlation method and then the frequency domain correlation method is taken as an example for simulation analysis.The communication signal component receiving mode is exactly the same with the traditional OFDM signal.The results show that the navigation signal and communication signalcomponents can be received normally in the frequency domain composite OFDM modulated signal.Under the condition of equal power allocation,the compatibility of the method is obviously improved compared with the reference method.