can i use one piece of TP-Link CPE510 for 100 meter

Yes, the TP-Link CPE510 is a wireless outdoor access point designed for point-to-point and point-to-multipoint operations. It is capable of covering distances significantly greater than 100 meters, with a typical range of several kilometers in ideal conditions, depending on environmental factors and obstacles. If you want to use one TP-Link CPE510 to provide coverage for a distance of 100 meters, it should work well, as long as the line of sight is clear and there are no significant obstacles (like buildings or trees) blocking the signal. For optimal performance, make sure to follow the manufacturer's guidelines for installation and alignment. If you are connecting multiple devices or need to extend the coverage range further, consider setting up additional units in a point-to-multipoint configuration.