Understanding what needs to be covered is an important part of the planning process, so do some quick calculations to better understand the situation. For indoor coverage, understand the effects of the attenuating and reflecting materials where the coverage is desired. A link budget will tell you what is practical given the environment and how to plan cells. With a link budget, one can have an estimate of how many cells will be required for the project. Tradeoffs take place between more cells and running more power.
First and Second Fresnel Zones
For an outdoor application, also consider checking the Fresnel Zone. The tradeoff between working on one long-distance shot versus two back-to-back links can be discovered by working out a few things on paper first.
Fresnel provided a means to calculate where the zones are where obstacles will cause mostly in phase and mostly out of phase reflections between the transmitter and the receiver.
Obstacles in the first Fresnel will create signals that will be 0 to 90 degrees out of phase, in the second zone they will be 90 to 270 degrees out of phase, in third zone, they will be 270 to 450 degrees out of phase and so on. Odd numbered zones are constructive and even numbered zones are destructive.
Therefore, on long-distance shots, it is necessary to take into account ground/water reflections and vertical surfaces like tall buildings.
If unobstructed, radio waves will travel in a straight line from the transmitter to the receiver. But if there are obstacles near the path, the radio waves reflecting off those objects may arrive out of phase with the signals that travel directly and reduce the power of the received signal. On the other hand, the reflection can enhance the power of the received signal if the reflection and the direct signals arrive in phase. Sometimes this results in the counterintuitive finding that reducing the height of an antenna increases the S+N/N ratio.
In fact, the contributions from adjacent zones may act to cancel each other because of their relative phase relationships. The practical situation is made even more complex because, due to the obliquity factor, higher-order zones contribute less energy than lower-order zones. The overall picture is that at the receiver the total field from all other zones is about 50% of that from the first zone alone. Thus clearance of the radiated field to the first Fresnel zone is very critical if an unobstructed transmission path is to be approximated at least at 60% of the zone radius.
To give you an example, since the majority of the transmitted power is in the first Fresnel Zone, any time the path clearance between the terrain and the line-of-sight path is less than 0.6 of the first Fresnel Zone distance, some knife-edge diffraction loss will occur. On the other hand, it is possible to gain in the signal strength at the receiver up to 3dB by having a flat surface such as a lake, a highway, or a smooth desert area at the second Fresnel Zone in such a way that the signals get reinforced at the receiver.