Let's see... i dont have any papers on the topic but i think i can give you a general view of the subjet.
Diversity is used to reduce noise on the receptor, there are two kinds of diversity, frequency and antenna diversity.
Using frecuency diversity, you use two carrier frecuencies to transmit the data and with antenna diversity you use two antennas to recieve the data.
The antennas must be separated aproximately one wavelenght (or it's half wavelenght) from each other since that is the signal gets it maximun power and it's minimal power on those points, is like the sum of a wave in the sea, there are points where the waves come together and double its altitude and there are places where the wave distroy themself. So the idea here is to have always one antenna that captures the best signal possible, the you just pick that antenna to complete the trasnmission, that way you reduce the effect of noise in the transmission.
Try searching for some info on google or yahoo.
Hope this helped