From the early days of computing, the concept of virtualization was created with the scope to efficiently (virtually) use all types of computer platforms, storage and network resources. Nowadays, a new concept called NFV (Network Functions Virtualization) has been introduced. NFV uses virtualization technologies to virtualize entire classes of network communication functions into blocks that may connect together to create a variety of communication services.
Virtualized Network Functions (VNFs) are software implementations of network functions that can be deployed on an NFV Infrastructure (NFVI).
Virtualization concepts can provide a greater degree of flexibility even to the LTE RAN by moving functions of the BBU away from the base station implementing them as virtual machines in a centralized data center, thus providing intelligent scaling of computing resources, while decreasing energy consumption and capital expenditure.
Considering that the centralization of RAN functions demands high-bandwidth and low-latency between the base station and data center, a suitable trade-off is needed to provide the optimal performance. Based on this, Azcom Technology is focused on identifying the LTE RAN functional splits to determine the viability of virtualization options in the RAN.
LTE RAN Functional Split
Functional split within the LTE RAN architecture was introduced in the series 38 of the 3GPP specifications (dedicated to “Radio technology beyond LTE”). This split moves the upper part of the LTE eNodeB Protocol Stack away from the Base Band Unit (BBU) to a new unit called Central Unit (CU), meant to be deployed inside cloud-based datacenters. The lower part of the Protocol Stack, down to the RF, is instead localized in a Distributed Unit (DU). Furthermore, the CU might be further divided to provide separation between Control Plane and User Plane traffic. This in illustrated in the Figure below. This is one of the main architectural concepts introduced in 5G.
Azcom has executed different feasibility studies on virtualizing LTE User Plane using GPU, virtualized infrastructures and proprietary eNodeB.
Network Function Virtualization (NFV) is globally considered a key enabler of 5G infrastructure and facilitates solution use-cases for companies like Azcom Technology.
Azcom Technology is looking to participate in DU module development along with providing interfaces to interop with the CU module. LTE RAN functional split makes possible the adoption of a hierarchical RAN approach, where a single CU controls more than one DUs, thus providing efficient load balancing and radio coordination of several DUs and increasing its geographical coverage. This simplifies network management and enables resource pooling and coordination of radio resources. New features can be introduced without affecting the performance and capacity of the DUs. Number of X2 interfaces also reduce, leading to faster handover procedures, fewer handover failures and lower network control signaling in complicated network environments.