Friday 26 February 2021

Samsung and Ericsson Talks Massive MIMO

Massive MIMO is a fascinating topic. First is that there is no end to learning about it and secondly, the more information I put out, the more hunger people have about it. In the recent months there have been quite a few product announcements on the topic so we thought, why not do a blog post on it. 

Before we start, why not look at Massive MIMO and Beamforming. Mpirical has a short and sweet video explaining it. It is embedded below.

The video discusses four main topic areas: Beamforming vs Spatial Multiplexing, Beam Creation and Steering, Massive MIMO and finally MIMO Panel Antennas.

Now that we have refreshed the concept, let's look at what the product announcements were. 

The first was this blog post by Ericsson on 'How to build high-performing Massive MIMO systems' where they talked about how Ericsson has mastered the Art and Science of Massive MIMO to both unleash the full capacity benefits and extend the coverage of the new 5G mid-band spectrum - bringing outstanding user experience today, and setting the stage for the advanced applications of tomorrow.

The post starts with the 101 of radio physics, then talks about “Outsmarting” physics with Massive MIMO and Beamforming and finally it talks about the secret sauce in Ericsson AAS (Advanced Antenna Systems). The tweet below shows a practical Massive MIMO antenna and how it works.

In addition, Ericsson announced an "ultra-light Massive MIMO radios and RAN Compute baseband solutions." You can read all about it on their Massive MIMO page here and in the Tweet below.

The second was a press release by Samsung announcing Massive MIMO Roadmap in New Whitepaper, which is available here.

The following video shows world's 1st commercial 5G Massive MIMO Radio by Samsung

As the deployments start ramping up, we will see more product announcements on these. The main challenge that needs solving is the huge amount of power consumption. Probably a year or two before we see a breakthrough.

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Friday 19 February 2021

Open RAN (O-RAN) RRU (O-RU) and DU (O-DU) Design

We often publish Open RAN related information on this blog. Now, Telef├│nica has just published a whitepaper providing an overview of the main technology elements that it is developing in collaboration with selected partners in the Open RAN ecosystem. 

It describes the architectural elements, design criteria, technology choices and key chipsets employed to build a complete portfolio of radio units and baseband equipment capable of a full 4G/5G RAN rollout in any market of interest. More details here and the PDF is here.

The following is a selective abstract from the paper:

Sites within Telef├│nica footprint can be broadly classified into four types, from low/medium capacity 4G to high/dense capacity 4G+5G, as illustrated in Figure 1. Each of those types correspond to a particular arrangement of DUs and RRUs whose design and dimensioning represents a key milestone that must be achieved prior to any further development. Representative frequency bands are just shown for illustration purposes, as well the number of cells that can be typically found in each site type.

3GPP defined a new architectural model in Release 15, where the gNB is logically split into three entities denoted as CU, DU and RRU. The RAN functions that correspond to each of the three entities are determined by the so-called split points. After a thorough analysis of the potential split options, 3GPP decided to focus on just two split points: so-called split 2 and split 7, although, only the former one was finally standardized. The resulting partitioning of network functions is shown in Figure 2.

The CU (Centralized Unit) hosts the RAN functions above split 2; the DU (Distributed Unit) runs those below split 2 and above split 7; and the RRU hosts the functions below split 7 as well as all the RF processing.

The O-RAN Alliance further specified a multi-vendor fronthaul interface between the RRU and DU, by introducing a specific category of split 7 called split 7-2x, whose control, data, management, and synchronization planes are perfectly defined. The midhaul interface between CU and DU is also specified by 3GPP and further upgraded by the O-RAN Alliance to work in multivendor scenarios.

The CU and DU can be co-located with the RRU (Remote Radio Unit) in purely distributed scenarios. However, the real benefit of the split architecture comes from the possibility to centralize the CU, and sometimes also the DU, in suitable data centers where all RAN functions can be fully virtualized and therefore run on suitable servers.

The infrastructure needed to build a DU is nothing else than a server based on Intel Architecture optimized to run those real-time RAN functions located below split 2, and to connect with the RRUs through a fronthaul interface based on O-RAN split 7-2x. It is the real-time nature of the DU which motivates the need to optimize the servers required to run DU workloads.

The DU hardware includes the chassis platform, mother board, peripheral devices, power supply and cooling devices.

When the DU must be physically located inside a cabinet, the chassis platform must meet significant mechanical restrictions like a given DU depth, maximum operating temperature, or full front access, among others. The mother board contains processing unit, memory, the internal I/O interfaces, and external connection ports. The DU design must also contain suitable expansion ports for hardware acceleration. Other hardware functional components include the hardware and system debugging interfaces, and the board management controller, just to name a few. Figure 3 shows a functional diagram of the DU as designed by Supermicro.

In the example shown above, the Central Processing Unit (CPU) is an Intel Xeon SP system that performs the main baseband processing tasks. To make the processing more efficient, an ASIC based acceleration card, like Intel’s ACC100, can be used to assist with the baseband workload processing. The Intel-based network cards (NICs) with Time Sync capabilities can be used for both fronthaul and midhaul interfaces, with suitable clock circuits that provide the unit with the clock signals required by digital processing tasks. PCI-e slots are standard expansion slots for additional peripheral and auxiliary cards. Other essential components not shown in the figure are randomaccess memory (RAM) for temporary storage of data, flash memory for codes and logs, and hard disk devices for persistent storage of data even when the unit is powered-off.

An Open RAN Remote Radio Unit (RRU) is used to convert radio signals sent to and from the antenna into a digital baseband signal, which can be connected to the DU over the O-RAN split 7-2x fronthaul interface.

For illustration, the reference architecture of an Open RAN RRU from Gigatera Communications is shown in Figure 7. It shows the functional high-level diagram of the RRU containing the following components:

  • Synchronization and Fronthaul Transport Functional Block
  • Lower PHY Layer Baseband Processing Functional Block
  • Digital Front End (DFE) Functional Block
  • RF Front End (RFFE) Functional Block

For more details, check out the whitepaper here.

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Friday 12 February 2021

Small Cells World Summit Open RAN Webinar

Small Cell Forum hosted an open industry Small Cells World Summit webinar, on December 9, 2020, on the topic of Small Cell Open RAN. It included panelists from companies across the global Small Cell eco-system - Qualcomm Technologies, Inc., Radisys, Reliance Jio and Picocom. The panel shared insight into SCF’s FAPI and Option 6 open interfaces and their applications within 3GPP and O-RAN frameworks.

The video of the webinar as follows:

Agenda and speakers:

  1. Julius Robson, Chief Strategy Officer, SCF - Small Cell Open RAN specifications:  5G FAPI and Option 6 
  2. Andrei Radulescu, Senior Staff Engineer, Qualcomm - FAPI: MAC/PHY interface for Small and Macro Cells
  3. Ganesh Shenbagaraman, Head of Integrated Products and Ecosystems, Radisys  - Network FAPI deployment scenarios and O-RAN alignment
  4. Ravi Sinha, Director, TechDev and Solutions (4G, 5G & MEC Solutions), Reliance Jio - Building the small cell  ecosystem around FAPI components and Option6 interfaces
  5. Vicky Messer, Director Product Management, Picocom - nFAPI test support
  6. Summary, next steps and Q&A

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Friday 5 February 2021

SK Telecom’s 5G MEC Status and Plan


Back in December, at '5G Connected Edge Cloud for Industry 4.0 Transformation – 2020 Spotlight Series', Kang-Won Lee, Vice President, 5GX Cloud Labs, SK Telecom gave a talk on SK Telecom’s 5G MEC Status and Plan. 

It was interesting to see that while the industry has changed the definition of MEC to Multi-access Edge Computing, SKT still refers to it as Mobile Edge Cloud. As SKT has now crossed over 10 million 5G subscribers, they have noticed a lot of demand for Edge compute capability. While there is a demand, enterprises, factories, buildings, etc. are not interested in managing their own infrastructure. They would rather somebody else provides the services. This is where SK Telecom sees new business opportunities in the future. Along with the high throughput, high capacity and low latency, security and privacy is very important as well. 

As the services move to edge, there is more predictibility on QoE and the latecny can be reduced to as low as 1ms which is a huge benefit to critical applications. While they are not there yet, they are moving towards that goal. There is also a huge opportunity for public cloud providers here.

SKT has 2 main deployment models as can be seen. The public edge where they have data centres distributed throughout the country and can hence provide MEC services to 5G users nationwide. On the other hand, On-site edge is useful for providing private MEC services to enterprise and government users. Ideal for smart factories, smart hospitals, offices, etc. In both cases, SKT are open to collaborate with the users, communities, open source, big companies, etc.

Finally, SKT MEC Architecture can be seen in the picture above. The 5G network and 5G-MEC gateway can be seen which is connected with the compute and storage resources which are in turn connected to SKT tech assets or other operator platform or public cloud platform as required. The video provides more details including the SKT MEC Architecture details.

The slides are available to the registered users here and the talk is embedded as follows:

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