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LENA – FIRE LTE testbeds for open experimentation


LENA: LTE Edge Network Enhancement



What is it?

  • The LENA experimentation project runs on the FLEX LTE testbed with the aim to combining existing eNBs with an execution infrastructure.
  • It enhances FLEX with Network Function Virtualization (NFV) Point-of-Presence, for deploying core functionalities as Virtual Network Functions (VNF) at network’s edge.
  • LENA deploys and tests EPC S-GW migration as VNF, for increased responsiveness and reduced traffic load at core network.
  • The experiment proceeds to validate the vS-GW, the traffic edge balancing towards core LTE network, and the migration of vS-GW to suitable locations.


What are the benefits for the virtualization S-GW?

  • High number of user requires better placement of S-GW.  S-GW may be duplicated and relocated at the edge, balancing traffic towards Core Network.
  • Shift of users’ traffic requires the migration in more suitable location, where the overall network traffic load gets minimized.

What are potential use cases envisaged by LENA?

Many scenarios can benefit from multiple S-GW VNF instance deployments, as proposed by LENA. Here are two of them:

  • Moving crowds/flash events – Moving vehicles or crowds generate capacity variation. Mobile Network Operators should provide dynamic and real-time capacity for these areas, in accordance to change in demand.
  • Diurnal Changes – Variation of demand during morning/evening rush-hours (i.e., mass movement of UEs from one environment type to another, e.g., suburban to/from dense-urban), causing congestion in border areas.


What is the architecture proposed in LENA?

The implementation of the enhanced experimentation infrastructure, tailored to the current FLEX LTE network platform, is shown in Figure 1.

Figure 1 Implementation of an enhanced experimentation infrastructure, tailored to the current FLEX LTE network platform.


The starting point of LENA will be the enhancement of the LTE eNB with an execution infrastructure, capable to execute core network services. LENA will build upon the existing LTE infrastructure of FLEX, providing an agile environment for proper VNF execution. The instantiation environment of VNFs will be dispersed at the edge of the network footprint, which is what is referred by ETSI as Network Function Virtualisation Point-of-Presence (NFV-PoPs). The composed services provisioned over these infrastructures impose a number of challenges to be addressed. They can be composed of several functions, each of which is developed for a specific purpose, executed in a combined manner over a shared infrastructure that may experience continuous workload variations.


As shown in the left-hand side of Figure 1, LENA incorporates existing FLEX experimentation tools. The experiment will be imported and monitored through the Experiment Controller module. The controller interfaces the Aggregate Manager that is in charge of collecting the measurements, providing storage capabilities and also storing a list of the available resources. The Aggregate Manager also interacts with the Resource Controller which allocates and coordinates the platform resources and the Measurement Library, which is in charge of communicating the outcomes of the experiment to the Measurement Collection module, inside the FLEX Aggregate Manager.


For the experimentation part, LENA integrates a hierarchical architecture, which is fully compliant with the ETSI NFV concepts, terminology and recommendations. On top it implements the Experiment Orchestrator (which will be based on T-NOVA Orchestrator “TENOR”), a management layer to enable orchestration of experiments that encompasses the NFV Orchestrator (NFVO). Furthermore, the Element Management System of the LTE network and the Monitoring module for the ongoing experiment are include here. The LENA Experiment Orchestrator is in charge of the overall experiment lifecycle, i.e., it handles and interacts with existing resource control modules, as well as to the underlying NFVI. It also enables efficient orchestration and performance-related evaluations of the experimentation testbed VNF synchronization and qualification in a reliable manner. The NFVO will be in charge of realizing network services on the virtualized infrastructure and will include interfaces to interact with the existing system for high level service management (e.g., exchange of network service descriptors).


The NFVO coordinates groups of VNF instances that jointly realize more complex functions. To that end, the NFVO uses the services exposed by the VNF Manager, which will be in charge of the instantiation, update, query, scaling and termination of the VNFs. The Element Management System (EMS) is the provider of the Fault, Configuration, Accounting, Performance and Security (FCAPS) functionalities of the LTE network and it consists the framework for handling the network elements. Finally, the Monitoring mechanism will provide a framework especially tailored for NFV services, offering validation of the accuracy and precision of the monitoring data.


For the NFV layers of the architecture, LENA will exploit work performed under other NFV-oriented research initiatives (such as, e.g., FP7 ICT T-NOVA and H2020 5G-PPP SESAME projects), which will need to be adapted in a degree in order to match LENA needs. Figure 1 shows an indicative breakdown of a testbed architecture. The Edge Server provides the execution environment for the VNFs attached to the LTE eNBs (through Gb Ethernet – GbE –). The NFVI is organized in several NFVI-PoPs (Points-of-Presence in line with ETSI terminology). Also, each NFV-PoP is managed by the Virtual Infrastructure Manager (VIM), which is the architectural component controlling the network and IT resources. The VIM is responsible for the allocation and management of the computing and storage resources for the instantiation of the Virtual Machines (VMs) that host the VNFs as well as the allocation of network resources and internetworking.


What are the results expected by LENA ?

LENA will investigate and quantify:

  • whether virtualization reduces number of packets that S-GW can handle
  • how beneficial are some advanced network Input/Output (I/O) techniques (Single Root I/O Virtualization SR-IOV) and Data Plane Development Kit (DPDK) to LTE setting.


What are the Baseline and Advanced setup of vSG VNF ?

Baseline Setup of vSG VNF


Baseline Setup of vSG VNF

  • Packets are copied to the Operating System user space by passing through the kernel.
  • More processing time.
  • Network I/O API (New API) is going to be used.









Advanced setup of vSG VNF



Advanced setup of vSG VNF

  • Single Route Input/Output Virtualization (SR-IOV) bypass kernel.
  • SR-IOV creates a fast path between the PCI bus and NIC directly to the VM.
  • Virtual NIC is loaded with DPDK driver. This enables faster NIC-user space communication








What is the experimental set-up of LENA ?

LENA is going to benchmark different implementation of S-GW VNFs. For this reason, ORION will deploy and migrate S-GW VNF at network edge (see Figure 2 and Figure 3). The S-GW instantiation will be triggered by high load, that may also result to S-GW VNF migration to other PoP(s).

Figure 2 The preferred software tool is the open source Open Air Interface OAI with highly configurable functionalities.


Figure 3 Network topology with S-GW splitting and ORION LTE testbed.


LENA incorporates with existing FLEX experimentation testbend. Due to scalability of tests and RF indoor isolated platform, the NITOS infrastructure in University of Thessaly (UTH), had been chosen.