The ";" is a punctuation mark called the "semicolon." It is not used very often in English. If you see it in written English, it will be used to connect two complete statements (dependent clauses) that are very closely related to each other without being already joined by a conjunction. It is often used when the flow of the text is damaged by expressing both statements as sentences by themselves because the length of both statements is very short.
I personally think that using the ";" in your example is incorrect, because both statements before and after the semicolon are long enough that each could be its own sentence. Also, the way it is written, the second statement is not a dependent clause, because it still relies on the first statement to get its full meaning. You could express it in a single sentence without the semicolon as :
It is well known that increasing the number of anchor nodes gives rise to better localization, although the greater expense may prove this to be an unfeasible solution due to the extra hardware requirements.