Raymond Knopp

This talk will provide an overview of the evolution of OAI architecture to cater to distributed software radio systems, in particular those characteristics of upcoming cellular networks.

This talk was moved forwards 1 hour from its original timeslot (16:45).

The evolution of radio communication networks will soon include by so-called “CloudRAN” technologies which refer to centralized radio-access infrastructure deployed in data-centers. Although exhibiting important differences in the type of processing they perform, the compute and storage architecture of these data-centers, as well as many of the software technologies, are very much modelled by those used by internet-based industries for information content management and distribution.

The future network architecture is comprised of three segments, the so-called fronthaul network, the CloudRAN data-centers and the main data-centers. The fronthaul network links the radio nodes at the extremities with the CloudRAN. These interconnection networks are typically optical links over very large distances (10-20 km) when the CloudRAN resides in the central office of an operator. Various technologies are envisaged including analog (radio-over-fiber) PON (passive optical network), TDM and WDM PON and carrier grade optical Ethernet. Other solutions will also exist for indoor networks (e.g. airports, shopping malls, large administrations, private enterprise networks, etc.) using both optical and copper-based fronthaul networks.

The software architecture of OpenAirInterface (OAI) is currently being evolved to cater to these distributed processing environments. In particular the infrastructure processing elements in OAI are being split at various places to allow them to be distributed between the central cloud processing units (RCC), the so-called radio-aggregation units (RAU) which perform centralized signal processing and switching and the network of remote-radio units (RRU). OAI now comprises two such processing splits which will be detailed along with examples of how to build simple ethernet-based RRU with low-cost commodity radio equipment (e.g. USRP B2x0, LimeSDR, etc.) and embedded PCs or ARM-based computers. In addition, The current architecture for deploying OAI in a data-center environment will be described.

A short live demonstration of networked-signal processing for 4G will be provided comprising a USRP-based RRU running on an UPBoard, an ethernet fronthaul and a mini radio-cloud-center housing the access protocol stack and a small core network.

Overview of 5G, network slicing, and OpenAirInterface

One of the interesting aspects of the 4G/5G era is confluence between the open-source software-defined networking technologies used in mainstream fixed networks and the closed-source technologies used the access and core components of cellular networks. This poses significant challenges from a legal standpoint because of the required mix of the two software technologies in common data centers. This conflictual relationship is aggravated further with the emergence of mobile edge computing. Once the legal issues are ultimately resolved, as it seems to be the case, the main issue will be that of satisfying real-time processing constraints for the radio-access network functions. These stem from the latency requirements of cellular systems when the radio-access procedures are executed on commodity servers. Moreover, when network function virtualization is put into the picture to allow for techniques such as network slicing to descend down in the radio-access network, the situation becomes even more challenging from a real-time perspective.

This talk will provide an overview of the evolution of 4G networks towards 5G and some of he new applications and industries that will be enabled by it. We also cover the role of the OpenAirInterface Software Alliance and how it is trying to soften the blow of clash between open and closed-source communities in radio-access and core networks along with its relationship with some of the other related open-source communities. The talk will also cover some technical aspects related to the difficulties in virtualizing radio-access network functions on commodity servers when it comes to real-time requirements, orchestration and management.

We provide an overview of the OpenAirInterface.org (OAI) 3GPP LTE SDR MODEM and protocol stack for x86-based systems. We focus on the objectives, some of the history of the project and its primary technical aspects. We also provide information regarding the newly created Software Foundation around OAI to encourage open-source development for 5G radio systems in conjunction with the imminent standardization phase.

OpenAirInterface today

OpenAirInterface (OAI) currently provides a standard-compliant implementation under a GNU GPLv3 license of a subset of Release 10 LTE for terminal (UE), basestation (eNodeB), and core network (EPC - MME, HSS, SGw and PGw) on standard Linux-based computing equipment (Intel x86 PC architectures). It can be used in conjunction with standard RF laboratory equipment available in many labs (i.e. National Instruments/Ettus USRP and soon PXIe platforms) in addition to custom RF hardware provided by EURECOM to implement these functions to a sufficient degree to allow for real-time interoperation with commercial devices. Some industrial users have reported working OAI-based systems integrated with commercially-deployable remote radio-head equipment and have provided demonstrations at major industrial tradeshows (Mobile World Congress Asia 2014, Mobile World Congress Barcelona in 2013, IMIC 2013). The current major industrial users of OpenAirInterface for collaborative projects are Agilent, China Mobile, IBM, Alcatel-Lucent, Thales, National Instruments and Orange. The primary future objective is to provide an open-source reference implementation which follows the 3GPP standardization process starting from Rel-13 and the evolutionary path towards 5G and that is freely-available for experimentation on commodity laboratory equipment.

We detail some of the inner workings of OAI, in particular SIMD optimizations for real-operation and efficient numerical simulation of radio systems as well as information regarding tools used in the development of the protocol stack. We also provide some use cases of OAI experimental research as well as some the methodologies used for proof-of-concept design (simulation, testing and deployment).

A bit on the need for open-source tools for 5G cellular evolution

Open-source has made a very significant impact in the extremities of current networks, namely in the terminals due to the Android ecosystem and in cloud infrastructure due, in part, to the OpenStack ecosystem. The OpenAirInterface Software Foundation aims to provide a similar ecosystem for the core (EPC) and access-network (EUTRAN) of 3GPP cellular systems with the possibility of interoperating with closed-source equipment in either portion of the network. In addition to the huge economic success of the open-source model, the Foundation will be a tremendous tool used by both industry and academia. More importantly it will ensure a much-needed communication mechanism between the two in order to bring academia closer to complex real-world systems which are controlled by major industrial players in the wireless industry. In the context of the evolutionary path towards 5G, there is clearly the need for open-source tools to ensure a common R&D and prototyping framework for rapid proof-of-concept designs.

About the Foundation

The Foundation is a non-profit organization ("Fonds de Dotation") founded by EURECOM, a world-renowned research institute in telecommunications and creator of OAI. EURECOM has been encouraged by the European Commission to extend OpenAirInterface to help in the definition of 5G systems. To this end, the Foundation will help drive innovation in 5G by following the standard as it is being drafted and, through quick interaction with 3GPP, will leverage the crowdsourcing effect both from industrial and academic users. It strives to make OpenAirInterface become the de facto reference implementation for new 3GPP standards through its open-source policy starting from Release 13 LTE. The resulting development can be used in both publicly-funded collaborative projects as well as industry-driven initiatives aiming to demonstrate 5G features at the earliest possible stage. Moreover, the results can be replicated in several locations independently through the combination of open-source and commodity hardware. This then becomes a truly distributed experimental facility with a very large number of potential contributors.