A microwave link is much lower bandwidth than the optical fiber that already exists to connect the two points (you can't rely solely on microwave, you need fibe

A microwave link is much lower bandwidth than the optical fiber that already exists to connect the two points (you can't rely solely on microwave, you need fiber to back it up when it rains or is cloudy, etc.). Also, depending on the market, you're only trading 8 or so hours a day. You can just send the pad during the 16 hours of the day while the link is otherwise unused.