Moving from engineering to sociocultural anthropology is possible. Some anthropological training would be better than none. In my opinion you should start figuring out what you want to study and do research on. Because you have a background in Electronics and Communication Engineering I think it might be worth looking into folks who are doing research on infrastructure and telecommunications. The anthropology of infrastructure seems like a sexy topic right now and you could use this to your advantage with your background. I would do a lot of reading on your possible future research topics that way when you write your SOP you clearly know what you want to do research on and which schools are a good fit because you have a clear idea of what you want to do. Read, read, read, read, read, read and familiarize yourself with the discipline. Knowing what you want to do as an Anthropologist is the first step in answering many of your questions. Remember, that depending on how you sell yourself your background could be an asset rather than a obstacle to overcome.
These might helpful readings: http://www.culanth.org/curated_collections/11-infrastructure
http://blog.castac.org/2014/03/dominic-boyer-on-the-anthropology-of-infrastructure/