I have this exact idea for my 4x game I have been working on the game design for. In my game, the communications signal actually has to travel to wherever it is going to. The command units (fleets and people on planets) would be responsible for carrying out the details through their own AI. The player could tell them to do things by setting a goal. For example, a fleet could be told to patrol a given area. They would patrol that given area until they either A, were running low on supplies and were at the point of no return and decided to go resupply (this could be overridden by telling them that they would be resupplied in space, or by telling them they had no choice in which case the loyalty and obedience of your men would be tested to see if they would follow your orders).
In my game, each turn was a week of in game time. My plan was to calculate the distance from the signal origin, IE where the player is currently located in the world (the player has an actual avatar in the world and can move around from place to place if that place is 'right'). If a fleet were 3 days away for a communication signal, the fleet would take 3/7's of a turn to receive the order, and would spend the other 4/7's of the turn working to carry it out. They would send back a weekly update where they would say "this is where we are and this is our status". The player would get two sets of location info for the fleet; last reported location and projected location based on calculating how fast they were going in their last update and which direction they were heading.
Now, I also have it planned for communications to be able to be intercepted, in which case they could be decoded and someone else could learn valuable information (information gathering is also a key focus in my 4x game, the players access to intel on things is extremely limited and the player has to work to learn things, but that's another topic entirely). The communications can also deteriorate over distance since over a distance, the signal focus will dissipate. They would also suffer from interference by natural phenomena, such as a regular radio signal getting too close to a blackhole for example that is casting out it's own radio waves. The radio waves from the blackhole could distort the signal. It would then be up to the receiving unit to properly understand the order. The player would also have to build communication relays which would be able to receive and resend the signal to maintain signal integrity over distance and could go around known sources of interference.
It would also be possible to jam communications. An enemy fleet could jam the communications of one of the players fleets, take it out, and the player would not know about the fleet's predicament until they did not receive the fleet's status report. In which case, the player would need to investigate and figure out what happened to their fleet. They would have the last known location and the last projected location and path.
The player would also be able to upgrade their communications to faster methods of communication, such as using tachyons to transmit the signal, or subspace signals, hyperspace signals (many different ways to do the same thing each with their own properties and requirements) quantum entanglement communications, etc. They would also be able to upgrade their enrcyption algorithms to make their signals more secure against being read by unwanted parties.
There is no 'communications range' that is a hard set number. There is just the time it takes for a communication to reach your command unit and there is also dissipation from travel distance (which has ways of being mitigated through research and development). That's how it works in real life for the most part. You send a signal out and it goes until it stops. It will lose focus over time as the wave loses coherency and it will get mixed up with other waves along the way (which is what causes white noise, multiple radio waves getting jumbled together and creating just noise on the receiver).
- In tv series such as, say, Star Trek, when a ship is beyond the range of their central command, they have sufficient leadership aboard to make clever decisions. The issue here is that, its very hard to grasp that from the standpoint of the player if he is playing the collective counsciousness of high management. On the one hand, I don't want the player to lose control of his ships just because they are out of range, but then, if I don't do something drastic, communication ranges won't mean anything.
I had planned for the player to set mission goals for their fleets. They can set any number of goals and reactions and give them priority ranking. For example, if a ship is sent to patrol an area, they could tell the fleet to either just report on movement in that area, engage to drive off unwanted visitors, destroy unwatned visitors, destroy unwanted visitors at any and all costs and pursue them if necessary. They can also set the thresh hold for returning for repair and/or resupply. The fleet admiral AI would take that into account and the AI system would also take into account the psychology and a lot of other factors to make the decisions. If a ship were out of 'communication range' the ship AI would have the ability to return to nearest port if they needed to. I don't think it is really hard to grasp for a player playing the high management. It's just delegating tasks for your subordinates to fulfill, just like any other real management job.
- Similarly, I don't want to limit the range. I think its important for the player to be able to send a ship very far in exploration, and a communication range would just prevent this. Likewise, it would suck to be unable to retaliate on an enemy just because he's destroyed one of your bases and has come out of your range.
You can have a ship/fleet act as a communication relay. You can have your ships deploy communication relays, You could build a permanent communication relay station.