# A Channel Compensation Technique Based on Frequency-Hopping Binary Offset Carrier Modulated Signal
## 1 Introduction
Adopting pseudo-random noise (PRN) code is a common method to estimate Doppler shift by determining the location of correlation peak through either a serial search or parallel search [17]. The authors in [18; 19] also applied signal detection techniques based on time-frequency signal analysis to compensate Doppler shift, such as short-time Fourier transform (STFT), continuous wavelet transform (CWT), etc. Additionally, the Doppler effect in frequency also changes orthogonal frequency division multiplexing (OFDM) signal waveform, and a kind of OFDM-modulated navigation signal is proposed in [20] to provide a feasible solution. Latency is another factor diminishing the quality of the received signal, usually presented as multipath interference, which leads to the distortion of the autocorrelation function (ACF) of PRN code and then the failure of signal detection. Thus, delay mitigation and anti-interference techniques are studied in [21], where a multiple gate delay (MGD) method  
Figure 1: Practical application scenario of SAGIN construction. employing three pairs of correlators has been considered to mitigating short-delayed multipath on signals using binary offset carrier (BOC) modulation, while the author only takes multipath into consideration without a highly possible dynamic environment. Furthermore, standing in the field of integrated communication and measurement system research, where the theme naturally matches the background of space-to-air communication, scholars have conducted numerous related studies so far. Based on BOC modulation as an extend from original spread spectrum modulation offering better performance in measurement, reference [22] proposed a combination with the introduction of a frequency-hopping technique as frequency-hopping binary offset carrier (FH-BOC) modulation to strengthen anti-interference capability, where multipath interference has also been discussed as outperforming the binary phase shift keying (BPSK) signal and BOC signal in circumstances. Subsequently, reference [23] conducted a FH-BOC signal further, converting it into an efficient constant envelope multiplexing technique for easily integrating signal components, in which the results showed it possessing lower ambiguity and better multipath performance than other BOC signals designed in a constant envelope under the same conditions. Additionally, reference [24] proposed a frequency-hopping alternated BOC (AltBOC) that inherits the low probability of interception, referring to another kind of variant BOC modulation, along with considerable anti-narrowband interference. Briefly speaking, scholars have already dedicated to the exploration in BOC modulation variant designed for ambiguity problems and interference confronting performance. However, there does not exist essential communication function for getting into involved with the measurement system in this research, even though anti-interference performance has been improved considerably. The authors in [25] proposed a multifunctional signal consisting of measurement, navigation, and communication functions, based on BOC and BPSK modulation to simplify the receiver structure. Although anti-interference performance and large dynamic tracking performance are achieved in simulation, the information carrying capacity is limited to BPSK modulation, and meanwhile, the severe interference between inner signals happens at low carrier to noise ratio (CNR), leading to the downgrade of signal performance. In this paper, a wireless communication system adopting I/Q modulation is proposed, in which a OFDM signal is modulated as an in-phase component and a FH-BOC signal is modulated as a quadrature component.