wifi: Make Bianchi validation script obtain reference values from reference files
In !273 (merged) ns-3 code is validated against Bianchi results. Currently the reference Bianchi values (obtained through Matlab) are hardcoded in the src/wifi/examples/wifi-bianchi.cc
file. However the values are already available in src/wifi/examples/reference/bianchi_11[amendment]_[difs/eifs].txt
. Thus is would be more future-proof to make the validation script obtain the values directly from the files.