Disrupting Telco Access rollouts through Open and Dis-aggregated RAN Networks

“Open, Intelligent, virtualized and fully interoperable”

O-RAN alliance

Source: O-RAN

During the last decade the Disaggregation movement which was initially started to address only a handful of business requirements have come far and delivered results. This early success has enabled many verticals to build the robust architectures through which we can solve both current and future business requirements to define a new momentum in a global Post COVID-19 economy.

For CSP and TMT industry specially we have seen Cloud movement is taking full momentum and hence it is becoming more prominent that we can only reap the real advantages from this transformation if the technology building block Lego’s are aligned with new principles to build infrastructure and networks. The list of such principles can be big and daunting however an Architect can start by breaking this list to Top important initiatives viz. 

• New Business models (To expand from Traditional B2C to B2B and Future B2B 2X (SaaS) offerings
• NE coding principles towards Cloud Native
• Focus towards Enterprise offerings
• Automation and efficiency
• Any Access
• Converged Transport and Finally
• Dis-aggregated and Open  RAN

All of these initiatives are inter mingled and has to be achieved along the transformation journey however there are some initiatives which have profound impact on CSP’s   investment and CAPEX/OPEX spending portfolio of which RAN comes to be on the top of list.

RAN(Radio Access Network)  networks which directly connects the subscriber to large Telco Infrastructure encompass to cover more than 5 Billion users  and define 1 Trillion $ Annual global revenue is certainly believed to be the most important infrastructure that we need to modernize and cloudify in an efficient manner .RAN has  historically proved to be a big cash cow for the Telco Industry . Infact  as per our analysis this piece is swallowing at least 70% of Operator CAPEX . So the traditional manner to build RAN networks by building a complete Radio/TXN Network using proprietary is neither attractive to the CFO nor is it scalable to deliver future requirements for new services in the 5G world. In this Paper I will try to share my view point how to start and build Dis-aggregated RAN Networks

How to build the Remote and Edge Clouds

We believe that in future every 5G new site will be an Edge Site which makes it necessary to build both Edge and RAN infrastructure on common and share Cloud Infrastructure. When it comes to define characteristics of this shared infrastructure the most important piece will be the operations and manageability of this large and scalable infrastructure.

Next the most important piece will be the networking primarily because we CSP’s traditionally have been doing this stuff for decades which is to ensure to wire and connect all solutions to offer them as a service to our customer. We have already seen some vendors bringing their commercial offerings to address these points, For example Vmware NSX-T 3.0 and Juniper 2.0 with unified SDN and analytics for all Core, Metro, Edge and Public Clouds. RedHat is another such vendor whose massively scaler AMQB based Openstack and Kubevirt based containerized platform support vision of complete automated infrastructure that is provisioned and managed by a central controller.

Future Disaggregated Hardware

Proponents of Closed RAN (at least from RU to DU) often claims the open X-86 hardware can not compete with high processing and performance required for a real time RAN however with the arrival of O-RAN (Open RAN alliance)  open interfaces , advancements in Silicon and collaborative community driven efforts such as in TIP driven Open RAN has really made it possible to open up the entire network and to build it using common principles using EOM offerings from a diverse suppliers .There are many advances in hardware that need to be carefully tailored to make successful Open RAN like ASICS specially for Network, GPU ,FPGA , NPU according to priorities for time-to-market, cost-performance, and reconfigurability, as well as scalability and SW ecosystem in making decision. Parallel processing-based accelerator can easily handle the performance of OFDMA and massive MIMO. In addition, the use of AI in edge computing is fueling the emergence of new AI processors beyond GPU, with TPU or spatial processor.

One of such recent advancements is Intel P-Series Atom Processor that is best suited to build Open RAN solutions , similarly to converge hardware at the sites Intel has announced the C-series Atom processors primarily which are used to deploy Edge and SD-WAN CPE’s , such a convergence is vital for industry to achieve vision of truly open and converged networks at the Edge and last mile networks .

One key point when we view Hardware modernization for Open RAN is to look advantages of Software e.g DPDK itself, For example the DPDK recent release DPDK19.05 only require 1-2 CPU cores per server so value coming from Smart NICs are declining as industry is reaching a new efficiency on the software. Again the latest offerings from intel chip set is a good example where latest Cascade Refresh is adding 30~40% power at the same cost which will make is possible not only to virtualize the RAN but to run AI and Data science processing at the Edge and RAN itself .

Having said this the hardware profile standardization of Open RAN components is already in full momentum with first release Beta coming in 2020 Feb and we expect to have a GA offer ready by end of 2020. So we can expect a commercial ready and GA  solutions of Open RAN to be ready by Q1 2021 .

Cost Efficiency of Open RAN and 5G Transport Networks

Although operators have gained early experience with 5G but obviously the cost to deploy the networks is quite high , it is primarily that still the RAN networks are not fully virtualized making transmission options possible that require a lot of transmission over heads . For example, based on our trials in middle East most vendors are coming with C-RAN delivery models only supporting Option 2-4 which waster more than 20% of transmission sources. Open RAN will make it possible to apply Option-7 to split the resources at RF and Lower Physical layers . The Open RAN lead network trails  will enable Cross-Layer network modeling to assess various scenarios

Understanding O-RAN , Open RAN , 3GPP

In the recent workshops with customers I have seen even a senior engineers sometimes confuse O-RAN , Open RAN and 3GPP itself , one common example is when some RAN teams claim that O-RAN is not 3GPP compliance and vice versa which obviously is  a wrong comparison  so it is important to share some thoughts of  how exactly it works

O-RAN:

As a matter of principle every O-RAN divides the whole RAN architecture in in RT-RIC (Real time  -RAN intelligent controller) , O-CU-CP(Open RAN CU control) , O-CU-IP (Open RAN CU user),O-DU (Open RAN DU) and O-RU (Open RAN RU) , the whole system view interconnected by interfaces is as follows

Source: O-RAN alliance

A1:The interface between RIC elements primary for policy control and implement AI/ML at the RAN side

O1:The O&M and monitoring interface

O2:The interface through which Orchestration layer control and provision the RAN Cloud components

E2 Interface:The interface that connects all the E2 nodes to the RT RIC , these E2 Nodes cane be CU-CP ,CU-UP ,DU or even an 4G O-eNb . As CUs are placed between RIC and DU, the location of CU will be left for decision of RAN vendors – either co-located with RIC or co-located with DU. Such choice will be an important for both telcos and vendors along the choice of open fronthaul. What is your choice?

Open Front Haul Interface:The interface between DU and RU

3GPP and its relation with O-RAN:

Primary body who defined the System Architecture and interfaces for horizontal services integration and specifications. 3GPP also defines a number of interfaces in O-RAN starting from 3GPP Release 15 where a nice description of interfaces can be found in 3GPP TS 31.905

The following interfaces are defined and managed by 3GPP and O-RAN is fully aligned with it as user or consumer of these interfaces these are

1. EI
2. FI
3. NG
4. X2
5. Xn
6. Uu

Open RAN:

Open RAN which is a TIP lead initiative is the complete E2E validation of O-RAN defined RAN architecture that also includes other components like Cloud ,Orchestration , Testing and validation of the full stack  The details can be found here https://telecominfraproject.com/openran/

“Open RAN Project Group is an initiative to define and build RAN solutions using a general purpose vendor neutral hardware and software defined technology “.

The flexibility of multivendor solutions enables a diverse ecosystem for operators to choose best-of-breed options for their 2G/3G/4G and 5G deployments. Solutions can be implemented on bare metal as well as on virtualized or containerized platforms.

One of the most important direction for Open RAN is to cover all 2G ,3G,4G and 5G NR solutions. Seeing Market in middle east as many operators will shutdown 2G by 2022 it is important specially to look for Open RAN solutions for 5G and 4G and in cases with 3G networks. Such pilots and network blue printing will be vital when we need to deploy such solutions in the brown fields.

In addition it will make possible for co-deployment and re-use of scarce spectrum resource’s between all access technologies.

RIC and Deployment Blue Prints for Open RAN Deployments

RAN intelligent controller (RIC) provides an interface between the RAN controller at the 5G core and the access network, enabling policy-driven closed-loop automation. The RIC is the interface piece that concatenates the RU, DU, and CU into the Open RAN (Full Functional Solution) through software programming and agile service delivery.

Introduction of many horizontal as well as vertical interfaces means more complexity to deploy and manage the Open RAN networks which requires a standard blue print manner to deploy such networks as provided by the Linux foundation Akraino Stack by abstracting the Infrastructure as a standard API and to be available Via standard API’s that can be consume d by the upper layers .RIC as depicted below deploy an east and flexible way to MANAGE Open RAN and having following characteristics

• Built from reusable components of the “Telco Appliance” blueprint family
• Automated Continuous Deployment pipeline testing the full software stack (bottom to top, from firmware up to and including application) simultaneously on chassis based extended environmental range servers and commodity datacenter servers
• Integrated with Regional Controller (Akraino Feature Project) for “zero touch” deployment of REC to edge sites

Orchestration of Open RAN

O-RAN Physical NF and O-Cloud represented by O-RAN architecture depicts the future RAN network comprise of many NE’s (As VNF’s or CNF’s) that will be part of standard Cloud -Cloud to be deployed on an X-86 hardware. This hardware will have standard acceleration support as may be required by each f the RAN NF and is responsible to de-couple each layer of the hardware from the software. However such a solution not only require standard deployment like Akraino but complete orchestration for both Day1 and Day 2 as supported by ICN (integrated Cloud Native network) . The standard orchestration is a key as it will not only orchestrate RAN functions but also other Functions like 5G CN along with provision of E2E Network slices and services.As the future Disaggregated networks split network in to layers so from both business perspective and technology view point we need to common set of tools to orchestrate the whole solution thus ensuring we  can provision any 5G and future business cases on the fly ranging from Remote Factory , e-health , video streaming , VGS broadcast etc .The latest Guilin release already consider how ONAP will power the Open RAN networks with future enhancement like REC blueprint automation and validation ,testing , FCAPS and running ML/AI streams based on Radio Network information are the features coming in next Honolulu release .

Summary

In summary O-RAN and related Open RAN solutions offer new architecture solutions for Telco industry that will make the Full disaggregation of networks possible. In addition to its alignment with Cloud and other related SDO’s mean the future networks can be al define, managed and operated suing same principles. For example, disaggregation means real value coming from deployment of singe transport infrastructure like IPV6 SRV+ where we can divide the single physical network in many logical networks that can serve both existing and new verticals. Similarly, Akraino /StarlingX and Airship installers will offer opportunity to deploy all stack using same principle and blue prints. Finally use of common orchestration platforms and futuristic networking slicing capabilities will open new business opportunities for Telco’s that was not possible before.

As we understand the overall mobility market is changing and coexistence of many access technologies including Wifi means dis aggregated , resource sharing and validated design is the need of the hour .It will not only help us unify the RAN but enable to really monetize the data from RAN like through AI and ML processing . It will also be fully beneficial for industry as a whole as fully open interfaces means  we can expand different components independently and validate it using open tools .s

This is therefore an important era to start the Open RAN journey and to take the early mover advantage in Disrupting the Networks  

Source: Linux Foundation

References:

1. https://www.5gtechnologyworld.com/5g-breaks-from-proprietary-systems-embraces-open-source-rans/
2. ONAP Guilin Release
3. Thought leadership recipes from Alex Jing
4. Akraino integrated cloud-native icn blueprint
5. https://docs.o-ran-sc.org/en/latest/architecture/architecture.html
6. Core analysis blogs

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