OFDM-BOC: A Broadband Multicarrier Navigation Modulation-Based BOC for Future GNSS
Lingyu Deng, Yikang Yang, Jiangang Ma, Yanxiang Feng, Lvyang Ye, Hengnian Li
Abstract
The global navigation satellite system (GNSS) is a critical infrastructure for positioning, navigation, and timing. Recently, vigorous implementation of low earth orbit (LEO) communication satellites has provided a new opportunity for developing GNSS. However, most of the existing navigation modulations are only applicable for narrow bandwidths; hence, broadband navigation modulation with good compatibility and scalability is needed. This paper presents a new broadband multicarrier navigation modulation, namely orthogonal frequency division multiplexing with binary offset carriers (OFDM-BOC), which uses orthogonal BOC signals as subcarriers. First, we derive the analytical expressions of the autocorrelation function (ACF) and power spectral density (PSD) based on the proposed signal model. Then, we discuss the relationship between the OFDM-BOC parameters and their time-frequency properties. This modulation can update existing BOC-like signals without affecting the original receiver. In addition, OFDM-BOC has a similar transmitter and receiver scheme to traditional modulation, so the update process only needs minor changes for the original navigation equipment. Compared with some representative navigation modulations such as AltBOC, BOC(10,5), and OFDM, the analysis reflects that OFDM-BOC has a flatter PSD main lobe, lower PSD maximum value, and smaller false lock probability. Moreover, it is shown that OFDM-BOC also has better spectrum efficiency, tracking performance, and anti-interference. Due to the excellent compatibility and navigation performance, OFDM-BOC provides a broadband modulation scheme for the next generation of navigation signals.