The U.S. Department of Defense, faced with increased demand for satellite based communications, has decided it cannot afford sufficient satellites to meet all this demand. The commsats cost at least $250 million each. But recent experiments have shown that there's a cheaper way to handle all that demand; weather balloons and stowaway transponders. The high altitude balloons are based on existing weather balloon designs, but carrying communications gear instead of weather sensors. As long as you can pick up and broadcast the same kind of signals commsats handle, you can put the equipment in a high altitude (up to 100,000 feet) balloon, or even a bomber or tanker that spends hours circling the battlefield. Much of the satellite communications needed by combat troops is to other people in the same general area. So the commsat replacement (a balloon or B-52) can do the job, passing off the long distance stuff to the real commsat.
A balloon can cover troops needs for about a thousand kilometers in all directions. A B-52 or KC-135 tanker can deal with a smaller area, but is even cheaper than $6,000-$25,000 balloon, which is often only good for a few missions. Once launched, the balloon turns on its battery powered transponder when it has reached the proper altitude, maintaining its position like a hot air balloon, using computerized controls. It acts like a very low flying satellite until the battery runs out after 8-12 hours. Then the balloon deflates, a parachute brings it to earth in one piece, and a GPS beacon makes it possible for the equipment to be recovered for reuse.
One of the more useful aspects of balloons is that they are easy to carry, and can be inflated and launched by a Special Forces team out in the middle of nowhere. Special Forces recon teams often want to send back live video of whoever they are keeping an eye on. These balloon sats make that easier.
The major cause of more commsat use is live video being generated by the increasing number of vidcams on the battlefield. These vids are being exchanged by the units cooperating in an operation. Since that's all local, a "satellite substitute" (a balloon, or aircraft carrying the comm. Gear) will work. To that end, there are even plans to put the comm gear in UAVs, including special UAVs that just fly circles high in the sky, acting as satellite substitutes.