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Two cars (mapper and navigator) were equipped with the cellular CDMA navigation receiver discussed in Section 38.5.2. The receivers were tuned to the cellular carrier frequency 882.75 MHz, which is a channel allocated to the US cellular provider Verizon Wireless. The mapper was stationary and was estimating the clock biases of the 3 BTSs via a WLS estimator as discussed in Section 38.4.1. The BTSs’ positions were known to the mapper, and the position states were expressed in a local 3D frame whose horizontal plane passes through the three BTSs and is centered at the mean of the BTSs’ positions. The height of the navigator was known and constant in the local 3D frame over the trajectory driven and was passed as a constant parameter to the estimator. Hence, only the navigator’s 2D position and its clock bias were estimated through the WNLS described in Section 38.4.1. The weights of the WNLS were calculated using Eq. (38.17) with s. For the first pseudorange measurement, the WNLS iterations were initialized by setting the navigator’s initial horizontal position states at the origin of the 3D local frame and the initial clock bias to zero. For each subsequent pseudorange measurement, the WNLS iterations were initialized at the solution from the previous WNLS. The experimental hardware setup, the environment layout, and the true and estimated navigator trajectories are shown in Figure 38.24. The ground‐truth trajectory was obtained from the GRID GPS SDR [58]. It can be seen from Figure 38.24 that the navigation solution obtained from the cellular CDMA signals closely follows the navigation solution obtained using GPS signals.

Figure 38.22 BTS environment, true trajectory, and experimental hardware setup for the ground vehicle experiment. Map data: Google Earth (Khalife et al. [12]).

Source: Reproduced with permission of IEEE.

Figure 38.23 Variation in pseudoranges and the variation in distances between the receiver and two cellular CDMA BTSs for the ground vehicle experiment (Khalife et al. [12]).

Source: Reproduced with permission of IEEE.