Which of the following statements are correct about the indoor and outdoor positioning based on the material we have covered?

Group of answer choices

$($A$)$ GPS is a representative outdoor positioning technology.

$($B$)$ WiFi positioning is an indoor positioning technology.

$($C$)$ GPS positioning is an infrastructrure free positioning system.

$($D$)$ Combining GPS positioning and WiFi positioning will provide more robust localization capability.

$($E$)$ Leveraging multi$-$sensing capabilities on mobile phones holds the potential to improve the accuracy of GPS positioning.