The global navigation satellite system (GNSS) provides outstanding positioning services for outdoor activities with sufficient accuracies, but it has poor indoor performance. Indeed, indoor positioning is also expected to achieve the outdoor positioning level to cater to an even higher volume of user demands. A pseudolite (PL), also called a pseudosatellite, is a ground-based positioning system that offers flexible deployment and accurate “orbits”. The PL system can carry on the role of the GNSS to provide precise positioning for indoor users. The clock differences originating from ground-based transmitters cause unsynchronized timing issues and impede attempts to fix the integer ambiguity. Numerous studies have been conducted with an emphasis on time synchronization to obtain this ambiguity-fixed solution by employing multiple transceivers in transmitter-receiver combinations for self-calibration inside a regional network of the ground-based system. However, this process requires a large investment and complicates the positioning owing to its intricate implementation. Actually, time synchronization can easily be achieved with a transmitter-only PL system at a low cost once the clock bias between transmitters is properly handled. Thus, we propose and present indoor precise point positioning (iPPP) and indoor PPP-real-time kinematic (iPPP-RTK) to handle the PL clock bias efficiently. Experiments demonstrate that the transmitter-only PL system can be time-synchronized without high cost or complicated operations and that centimeter level indoor precise positioning can be reliably achieved with our proposed methods.

全球导航卫星系统（GNSS）为具有足够精度的户外活动提供了出色的定位服务，但室内性能却很差。实际上，室内定位也有望达到室外定位水平，从而满足更大数量的用户需求。伪卫星（PL），也称为伪卫星，是一种基于地面的定位系统，可提供灵活的部署和准确的“轨道”。PL系统可以充当GNSS的角色，为室内用户提供精确的定位。源自地面发射器的时钟差异会导致不同步的时序问题，并会阻止尝试修复整数歧义。已经进行了许多研究，重点是时间同步，以便通过在发射器-接收器组合中采用多个收发器，在基于地面的系统的区域网络内进行自校准，来获得这种解决歧义的解决方案。然而，由于其复杂的实施，该过程需要大量投资并且使定位复杂化。实际上，一旦正确处理了发射器之间的时钟偏差，就可以使用低成本的仅发射器PL系统轻松实现时间同步。因此，我们提出并提出了室内精确点定位（iPPP）和室内PPP实时运动学（iPPP-RTK），以有效处理PL时钟偏差。