Implementation Strategies for a Universal Acquisition and Tracking Channel Applied to Real GNSS Signals

Abstract

This paper presents a universal GNSS receiver channel capable of tracking any civil GNSS signal. This fundamentally differs from dedicated channels, each customized for a given signal. A mobile device could integrate fewer universal channels to harvest all available signals. This would allow securing signal availability, while minimizing power consumption and chip size, thus maximizing battery lifetime. In fact, the universal channel allows sequential acquisition and tracking of any chipping rate, carrier frequency, FDMA channel, modulation, or constellation, and is totally configurable (any integration time, any discriminator, etc.). It can switch from one signal to another in 1.07 ms, making it possible for the receiver to rapidly adapt to its sensed environment. All this would consume 3.5 mW/channel in an ASIC implementation, i.e., with a slight overhead compared to the original GPS L1 C/A dedicated channel from which it was derived. After extensive surveys on GNSS signals and tracking channels, this paper details the implementation strategies that led to the proposed universal channel architecture. Validation is achieved using GNSS signals issued from different constellations, frequency bands, modulations and spreading code schemes. A discussion on acquisition approaches and conclusive remarks follow, which open up a new signal selection challenge, rather than satellite selection.

Area-Efficient Universal Code Generator for GPS L1C and BDS B1C Signals

“…Lastly, Legendre sequence-based codes show excellent correlation characteristics, and they have recently been used in GPS L1C and BDS B1C signals. As the fields of the application of the GNSS have expanded along with the recent development of the industries, studies to provide high precision and additional functions of GNSS receivers have been extensively conducted [8][9][10][11][12][13][14][15][16][17]. In addition to the simple role of receiving signals and performing navigation calculations, advanced signal technologies, such as anti-jamming [8] and anti-spoofing [9], are applied, and studies on multiconstellation and multi-frequency receivers [10][11][12] are being conducted for high-precision high-reliability location calculations.…”

“…In addition to the simple role of receiving signals and performing navigation calculations, advanced signal technologies, such as anti-jamming [8] and anti-spoofing [9], are applied, and studies on multiconstellation and multi-frequency receivers [10][11][12] are being conducted for high-precision high-reliability location calculations. Especially, studies on single code generators that support various codes are actively conducted for the implementation of multi-constellation and multi-frequency receivers so that single receivers can support multiple codes [13][14][15][16][17]. As shown in Table 1, since LFSR-based code generation is the most widely applied, studies on LFSR-based codes have been steadily conducted [10][11][12][13].…”

“…However, there are not so many studies on the Legendre-based code generator structure so far. As representative Legendre-based generator structures, authors of [14,15] proposed general code generators that use memory to store and read Legendre-based codes. The authors of [16] proposed a code generator structure where Legendre sequences are generated on the fly to generate PRN codes and to the authors of [17] proposed a Weil-generation code generator structure where Legendre sequences are stored in the ROM and Weil sequences are generated on the fly.…”

“…The authors of [16] proposed a code generator structure where Legendre sequences are generated on the fly to generate PRN codes and to the authors of [17] proposed a Weil-generation code generator structure where Legendre sequences are stored in the ROM and Weil sequences are generated on the fly. Although previous studies [14][15][16][17] succeeded in generating multiple Legendre-based codes using single hardware, they still use a lot of unnecessary hardware resources to universally generate Legendre-based codes. Therefore, this paper proposes an area-efficient code generator structure where many Legendre sequence-based codes can be generated using a single universal code generator by removing redundant used hardware resources within a range where the overall system performance is not degraded.…”

Energy Efficient GNSS Signal Acquisition Using Singular Value Decomposition (SVD)

“…The truncation of PRN sequences leads to a reduction in the correlation of the GPS signals and may not be an appropriate solution. Fortin and Landry identified GNSS signal characteristics and addressed them by a universal acquisition and tracking channel, proposing an architecture that allows sequential acquisition and tracking of any chipping rate, carrier frequency, FDMA channel, modulation—i.e., BPSK(q) or QPSK(q), sin/cos BOC(p, q), CBOC(r, p, Pr ), and TMBOC(r, p, )—or constellation, where a mobile device could integrate fewer universal channels, securing signal availability and minimizing power consumption and chip size, the results showing a 66% increase in power consumption compared with the established reference [ 18 ]. The design principles align very well with this research in the sense that they identify the need to design new receivers to accommodate the increasing demands of new GNSS signals.…”