YateUCN, the EPC cloud

The YateUCN is an LTE EPC that unifies all the functions of a conventional LTE core network into a single server. A single YateUCN unit combines the MME, SGW, PGW, PCEF and PCRF functions. A pool of YateUCN servers provide seamless horizontal redundancy, scalability and load balancing in the LTE core network. The YateUCN also replaces the latest core network approaches to design and management, such as network function virtualization (NFV) that virtualizes the functions of the network’s nodes in software or software-defined networking (SDN) that splits the control plane from the user plane.

A conventional LTE core network has many components and each requires a back-up node for redundancy. To ensure load balancing, operators need to deploy load balancers and external servers, which only add to the complexity count.

The YateUCN servers that form the EPC cloud have a many-to-many relationship with the eNodeBs, are equal at application lever, and eliminate the single point of failure between the RAN and the core network. All these characteristics allow for horizontal redundancy, load balancing, easy management and an overall simplicity within the network.


Redundant EPC

In conventional LTE networks, all core network components (MME, SGW, PGW, PCEF, PCRF) need to be duplicated to ensure redundancy and synchronization in case of failure. With a YateUCN-based core network, operators add extra servers to the existing pool to increase the network’s overall capacity.

To achieve redundancy, subscribers get assigned to random servers from the YateUCN pool. If a YateUCN fails, all the devices served by that unit are automatically re-assigned to other available YateUCN servers, as seen in the diagram.yucn_redund_epc_2015-11-18_version1.3

LTE core network cloud

A cluster of YateUCN servers act as an LTE core network cloud, providing all the EPC services: mobility, authentication, quality of service, routing upload and download IP packets, IP address allocation and more. Mobile operators eliminate the occurrence of a single point of failure between the RAN and the core network because YateUCN servers are equal at application level, and have a many-to-many relationship with the eNodeBs.

By removing the single point of failure possibility, mobile carriers can build scalable and considerably leaner core networks, while also providing load balancing for enhanced flexibility.

Each YateUCN core network server is implemented in off-the-shelf servers commodity software (Linux), offering a shorter lead time, more servicing options and faster replacement time.

Integration in existing LTE networks

The entire LTE EPC layer is implemented in a single YateUCN unit, meaning that it replaces the MME, the SGW, the PGW, the PCEF and the PCRF units of conventional networks.

The YateUCN is compatible with any generic LTE RAN and core network component. It supports the S1-AP and GTP interfaces between its MME and SGW functions and the eNodeBs. The YateUCN uses Diameter (S6a) to connect to an existing generic Home Subscriber Server (HSS). The unified server can connect to external PGW and SGW via the S5/S8 interface. To link to an existing IMS, to the Internet or to an MMS service, the YateUCN uses the SGi interface. Finally, to interrogate an external Equipment Identity Register (EIR) about blacklisted IMEIs, the YateUCN uses S13 over Diameter.

Additionally, the YateUCN also implements the IMS functions necessary for deploying VoLTE, but this will be detailed in a future article. In the meantime, previous blog posts have detailed the YateUCN’s VoLTE call with an iPhone 6 or how the YateUCN handles SRVCC.

A few final words

A unified core network server that delivers redundancy, scalability, load balancing and flexibility allows mobile operators to tap new core network equipment innovations and reduce their CAPEX. Easily integrated in an existing LTE network, the YateUCN makes it possible for mobile carriers to optimize their networks and replace solutions typically characteristic to the recent mobile LTE deployments, such as NFV or SDN.

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