The processing at Base stations level can be done by baseband
processing units (BBUs) and analog radio access units (remote
radio heads RRHs) separately. The BBU part can be moved
to a pool, or more generally to the cloud, to mutualize and
thus optimize resources.The transmission of radio signal is
then performed by RRHs based on computed signals from the
cloud. The BBU pool is a virtualized cluster connected to the
core network through the backhaul. Cloud based computation
makes RRHs cheaper and simpler, allowing more scalability
and densification opportunities. It also reduces delay for intercell
coordination and permits more joint optimization of processing, e.g. for cooperative interference management ,
scheduling, coordinated multipoint (CoMP), etc. [46]