Theory: Creating "LPS" transmitter for GPS receivers
Search for GNSS simulators. They are widely used for testing GPS receivers, software, phones, etc. If you make GPSs, you can't just walk outside and see if it works. For a controlled test of time-to-fix or position accuracy or sensitivity you need a simulator, and they're widely available.

That said, your objective of actual navigation for many unmodified receivers probably wouldn't work. A GPS receiver knows how to predict the orbits of the transmitters based on a few orbital parameters: transmitters on poles would not be possible to model as orbits.

In summary, you can fool one GPS easily, take it on a tour. But you can't make real signals to be correctly interpreted by many unmodified receivers.