In Differential GNSS (DGNSS) positioning, differencing measurements between a user and a reference station suppresses common-mode errors but also introduces reference-station noise, which fundamentally limits accuracy. This limitation is minor for high-grade stations but becomes significant when using reference infrastructure of mixed quality. This paper investigates how large-scale user cooperation can mitigate the impact of reference-station noise in conventional (non-cooperative) DGNSS systems. We develop a unified estimation framework for cooperative DGNSS (C-DGNSS) and cooperative real-time kinematic (C-RTK) positioning, and derive parameterized expressions for their Fisher information matrices as functions of network size, satellite geometry, and reference-station noise. This formulation enables theoretical analysis of estimation performance, identifying regimes where cooperation asymptotically restores the accuracy of DGNSS with an ideal (noise-free) reference. Simulations validate these theoretical findings.

翻译：在差分GNSS（DGNSS）定位中，通过用户与参考站之间的测量值差分可抑制共模误差，但同时也引入了参考站噪声，这从根本上限制了定位精度。对于高等级参考站，该限制影响较小，但在使用质量参差不齐的参考基础设施时，其影响变得显著。本文研究了大规模用户协作如何能在传统（非协作）DGNSS系统中减轻参考站噪声的影响。我们为协作式DGNSS（C-DGNSS）与协作式实时动态（C-RTK）定位建立了统一的估计框架，并推导了其费舍尔信息矩阵的参数化表达式，该表达式是网络规模、卫星几何构型及参考站噪声的函数。此公式化表述使得估计性能的理论分析成为可能，从而识别出协作能渐近恢复理想（无噪声）参考站条件下DGNSS精度的运行区间。仿真验证了这些理论发现。