Others have pointed out that signal beacons have certainly been used by many European cultures long before Tolkien, however none have explicitly mentioned what I believe is the closest thing to have been used within England to how the beacons function in LOTR.

During the mid-late part of the Anglo-Saxon period, under the reign of Alfred the Great and his descendents, in order to combat the constant Viking raids a series of burhs were constructed. The burhs were built in a network roughly 1 days march from each other with each burh connecting to at least 2 other burhs. In the event of a Viking raid the nearest burh would light a signal beacon. All connecting burhs who saw the beacon would light their own beacon then march to the burh which called for aid. Other burhs would follow the chain of beacons until eventually reaching the original burh.

Relevant article: [Lighting Anglo-Saxon beacons][1].


  [1]: https://www.ucl.ac.uk/early-medieval-atlas/news/2016/aug/lighting-anglo-saxon-beacons