failed to execute ‘./modules/bts/mbts’
and then a segmentation fault when you tried to load the ybts module.
Using ./modules/bts/mbts indicates that you try to run from the source directory. This is possible, but not documented, as it involves making a number of symlinks:
ln -s path/to/yate-bts/ybts.yate modules/bts/
ln -s path/to/yate-bts/mbts/apps/mbts modules/bts/
ln -s path/to/yate-bts/mbts/TransceiverRAD1/transceiver-rad1 modules/bts/transceiver
ln -s path/to/yate-bts/mbts/TransceiverRAD1/ezusb.ihx modules/bts/
ln -s path/to/yate-bts/mbts/TransceiverRAD1/fpga.rbf modules/bts/
If you install Yate and YateBTS (even in /usr/local), the components of YateBTS will appear in the correct directory.
The segfault may indicate that you have several versions of Yate libraries on your system and the wrong one is used. Please check this.
Note that if you have Yate installed (with devel libraries), the linker will find and link those libraries instead of the correct ones when you build either Yate or YateBTS.