This commit introduces the CUDA implementation of the multipath channel
model in `multipath_channel.cu`.
- Implements `multipath_channel_kernel` using shared memory for
efficient, high-performance convolution.
- Provides a C-callable wrapper, `multipath_channel_cuda`, to
orchestrate the full pipeline of data transfers and kernel
launches.
- The wrapper includes support for multiple memory models (Explicit
Copy, Unified Memory, ATS) via preprocessor directives to adapt to
different build configurations.
- Adds a `interleave_channel_output_cuda` utility to convert signal
data from the CPU's planar format to the GPU's interleaved format.
Nika Ghaderi
77d854bdf3