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This section evaluates the pseudorange obtained by the receiver discussed in Section 38.6.2. To this end, the pseudorange variation from GPS is compared with the pseudorange variation due to (i) only tracking the SSS and (ii) aiding the SSS tracking loops with the CRS. The receiver was mounted on a ground vehicle and was tuned to the carrier frequencies of 1955 and 2145 MHz, which are allocated to the US LTE providers AT&T and T‐Mobile, respectively [63]. The transmission bandwidth was measured to be 20 MHz. The vehicle‐mounted receiver traversed a total trajectory of 2 km while listening to the 2 eNodeBs simultaneously as illustrated in Figure 38.49. The position states of the eNodeBs were mapped beforehand. Figures 38.50 and 38.51 show (a) the change in the pseudoranges between the receiver and the 2 eNodeBs, (b) the error between the GPS pseudorange and the LTE pseudoranges, and (c) the distance error cumulative distribution function (CDF) of the LTE pseudoranges.

Figure 38.49 LTE environment layout and experimental hardware setup. Map data: Google Earth (Shamaei et al. [63]).

Source: Reproduced with permission of Z. Kassas (International Technical Meeting Conference).

Figure 38.50 (a) Estimated change in pseudorange and estimated CIR at t = 13.04 s for eNodeB 1. The change in the pseudorange was calculated using (1) SSS pseudoranges, (2) SSS+CRS pseudoranges, and (3) true ranges obtained using GPS. (b) Pseudorange error between (1) GPS and SSS and (2) GPS and SSS+CRS. (c) CDF of the error in (b) (Shamaei et al. [63]).

Source: Reproduced with permission of Z. Kassas (International Technical Meeting Conference).

Figure 38.51 (a) Estimated change in pseudorange and estimated CIR at t = 8.89 s and t = 40.5 s for eNodeB 2. The change in the pseudorange was calculated using (1) SSS pseudoranges, (2) CRS pseudoranges, and (3) true ranges obtained using GPS. (b) Pseudorange error between (1) GPS and SSS and (2) GPS and SSS+CRS. (c) CDF of the error in (b) (Shamaei et al. [63]).

Source: Reproduced with permission of Z. Kassas (International Technical Meeting Conference).

The error in the pseudorange obtained by tracking the SSS is mainly due to multipath. The estimated CIR at t = 13.04 s for eNodeB 1 and t = 8.89 s and t = 40.5 s for eNodeB 2 show several peaks due to multipath, which are dominating the line‐of‐sight (LoS) peak. These peaks contributed a pseudorange error of around 330 m at t = 13.04 s for eNodeB 1 and around 130 m at t = 8.89 s for eNodeB 2. These results highlight the importance of utilizing the CRS signals to correct for multipath‐induced errors.