How to get cell tower signal from 4th floor to ground floor?
A powerful cell phone signal booster kit with an exterior antenna installed outside window against the building wall or preferably on the roof would transmit the cellular signal via cable in the kit. Choose any of the kits listed at link below ensuring that the longest cable included in the kit you choose is long enough to span four floors. All kits listed at link below have the strongest and the most powerful on-building Log Periodic antenna that can catch maximum signals from your higher floor and pass them along via coax cable to amplifier unit on main floor which then amplifies those signals. In-building antenna(s) included in the kit then broadcasts those amplified signals throughout the ground level floor.