Digital Signal Processing in the Cloud Radio Access Network (C-RAN)

We are still waiting for the real entrance of the multi-core Digital Signal Processing (DSP) into the mobile networks. The reason why we are still waiting for the real breakthrough of virtualized DSP is basically laying in the type of mobile network functions suitable to be located on the multi-core DSP chips, as the high timing requirements are imposed by the rest of the network. This directly depends on which of the functions are processed on the side of a Distributed Unit (at the antenna side) and which DSP functions are in the Centralized Unit (at the cloud or mobile edge side). From the other side the complexity of the network connecting DUs with CU, named fronthaul network, is getting much more complex when this paradigm of shared DSP processing resources in the mobile network is introduced. The general flexibility of this so called functional split, which determines DU and CU functions, is already supported by the new generation of remote unit hardware, which is being developed with the Software Defined Radio (SDR) components. Furthermore, as the cloud computational units (Mobile Edge Computing units) are getting closer to the users, the infrastructural requirements for the full deployment of virtualized DSP in C-RAN are becoming satisfied. In addition, the 5G standard has already specified the DU and CU units for the C-RAN deployment in 5G, leaving the place for its deployment in the future uses, but still the full paradigm of Centralized RAN is still not introduced. For sure this will be one of the important pillars of creating “green” communications in the beyond 5G technologies as it is improving the utilization of infrastructure, increasing spectral efficiency and reducing the deployment and maintaining costs of the network. Yet it is needed to wait to see what will happened in the future regarding the virtualized DSP of the mobile networks.