What are the factors that affect delay/latency between base stations?
Avoiding the debate in the comments section I'll try and answer your question as "but what effects latency?" 

With wireless communications most latency would be with the modulation and demodulation process as the signal needs to be processed. have a read off this it should help
 https://www.researchgate.net/publication/326892443_Low-latency_Networking_Where_Latency_Lurks_and_How_to_Tame_It