From LTE perspective: + https://github.com/srsLTE/srsLTE + https://github.com/acetcom/nextepc + https://github.com/tudo-cni/tinyLTE

srsLTE and tinyLTE whitepapers are worth looking into as well. The whitepapers describe the infrastructure and hardware to purchase. All in all, these are surprisingly simple to get working together. After that, it is up to you what to hack on. MEC paradigm is something specifically relevant to software engineers.