I just wanted to elaborate on who should observe Counting of Omer. Let's take a look:
YLT Lv 23:10 'Speak unto the sons of Israel, and thou hast said unto them, When ye come in unto the land which I am giving to you, and have reaped its harvest, and have brought in the sheaf, the beginning of your harvest unto the priest,As you can see, the Written Torah clearly states that Counting of Omer is ONLY for SONS of Israel AND Counting of Omer is ONLY observed in the Land of Canaan.
Also, Torah seems to imply that Counting of Omer is only for those who actually have crops, otherwise there would be nothing to wave and count.
Another point is that 50th of Omer is a Holy Meeting, which means that everyone counted Omer at the same time.