Seems like the weather and road conditions would be the challenge you have identified. By "mobile carrier", I'm assuming you mean a business that is cellular or wireless communications related. So to kick off the brainstorming which you should be doing with the project team, you might want to consider some of the following:
- what are the consequences if a communications relay/tower is not put into place in a timely manner? (e.g. weather delay, travel delay to destination)
- is it possible that the signal between towers will be blocked by terrain and/or weather?
- what is the expected coverage area? how will geography and weather affect it?
- will you be able to get sufficient relays/towers in place or will geography prevent some?
- what is the expected call/signal drop rate? how will geography and weather affect it?
- what is the expected load on each tower? has geography forced the population using the service into a small area or is the population evenly distributed?
- how will the relays/towers be powered?
- how will repair teams reach the relays/towers?
- how will these challenges affect costs?
- are there safety issues in humans reaching locations where towers are to be located?
- how will the project team members reach the destinations?
- will you be able to meet face-to-face with the project team? how long will it take them to reach the meeting location?
With your specific knowledge of the project, you might start creating broad categories under which to consider these potential risks and issues (e.g. human resources, coverage, relay/tower locations, etc.). This should help you think through the things someone like me who has no knowledge of the specifics of your project won't be able to do for you.