R. Stephen Spinazzola, PE, LEED AP
Shumate Engineering, PLLC
With the recognized advantages of 5G as will be discussed, and the increased speed of Wi-Fi-6, a convergence of technologies offers data center designers, owners, and operators a new high speed super-highway, with a lot less copper and fiber.
5G and Wi-Fi-6 technologies are providing individual opportunities to data center owners a quantum leap forward in the available technologies to move large amounts of data without wires. Saying without wires is bit of an oversimplification. There still will be copper and fiber in the data center.
5G is being implemented in low, mid, and high band millimeter wave, with the high band offering gigabit-per- second range. “5G can enable new services that can transform industries with the ultra-reliable, available, low-latency links like remote control of critical infrastructure.”
High band is most likely to be deployed in private data center 5G network as it offers the following:
1. 50-to-250-meter range
2. Maximum number of devices per sq. Kilometer: 1 million
3. Latency in milliseconds: 1
5G technology represents a major improvement in previous wireless technologies in 3 ways:
• Dynamic cloud-native architecture: Across the industry, communication service providers are moving away from point-to-point protocols. They are looking to build scalable cloud-native architectures such as the ones in the big web companies (GoogleTM, Facebook, Amazon) use in their hyper-scale data centers.
• More flexible, customizable networks: 5G takes telco networks a major step forward with the concept of network slicing. CPS’s will offer virtual networks tuned to specific use cases such as massive IoT installations and the ability to provide ultra-low-latency services.
• Demand for greater service and business agility: Customized services need to support a continuing evolving portfolio of novel, different use cases for both customers and enterprises.
High Density Impact: Providing cooling for this increasing in server density will push the limits of fan powered air cooling. Liquid emersion and direct-to-chip cooling are being deployed now in data centers to deal with the extreme heat dissipation of the space optimized servers.
“5G is accompanied by machine-to-machine applications and real-time data analytics driven by software defined networks (SDNs) and network virtualization, which are powered by high-density servers housed in today’s core data centers. Hyper-scale data centers and cloud facilities are purposely built to handle this network of increased computing power. Enterprise legacy data centers, on the other hand, will have to (if they haven’t already) strategize on migrating to a cloud provider or upgrading infrastructure to be able to process future 5G innovations.
5G’s impact on core data center infrastructure will remain centered around optimizing efficiency, reliability, and security while meeting increased data and network demands”.
The densification of data centers at the rack level are approaching the viability of all air cooling. The hyper-scale (HS) providers have been pushing the envelope for quite a while, and we may be reaching the tipping point for forced air cooling. The exact numbers are confidential for each HS, but suffice to say, racks average about 12 KW/ rack, and an approx. temperature rise thru the servers from the cold aisle to the hot aisle of 20 Deg. F. This will require approx. 1,900 CFM per rack.
What I have observed in the field where cold aisles and hot aisles were sufficiently sealed to prevent bypass air (air going from the cold aisle to the hot aisle without going thru a computing device) is a temperature rise of approx. 28 deg. F. Using a 28 Deg. F as the temperature rise from the cold aisle to the hot aisle would require approx. 1,350 CFM per rack. Using a 28 deg. F. temperature rise would make forced air viable for higher rack loads. For this analysis, the assumption moving forward is to use a 20 deg. F temperature rise.
When looking at cooling solutions for rack loads above 12 KW/ rack, the fan energy to move 100% of the rack load in a data center can result in the fan energy pushing the Power Utilization Effectiveness (PUE) solutions need to be considered. There are numerous solutions available that offer the ability to cool high density, three of which are being deployed as of this writing,
1. Chilled doors: the back door on a rack has a chilled water coil that circulates chilled water above the dew point that allows for a dry coil and no condensate. There are several solutions to generate chilled water. A hybrid dry cooler with an adiabatic pre-cooling in series with mechanical cooling can provide PUE values lower than forced air in high density deployments.
2. Chilled hot aisle ceiling: the ceiling of the hot aisle includes a chilled water coil that cools the hot air leaving the hot aisle to match cold aisle set point. The chilled water can be generated in a manner like the description above for chilled doors.
3. Immersion Cooling: “Also known as liquid submersion cooling. It is the practice of submerging computer components (or full servers) in a thermally, but not electrically, conductive liquid (dielectric coolant) allowing higher heat transfer performance than air and many other benefits.”
The deployment of 5G will accelerate the industry to deploy cooling systems that are not all forced air cooling, and will likely be one of the 3 cooling systems discussed above, or a hybrid using forced air for dedicated outdoor air and for humidity control in the space.
A question asked is will 5G replace wi-fi. The answer based on this research is no. The advent of Wi-Fi-6 will allow 5G to interoperate with Wi-Fi-6 using it as radio access network (RAN) allowing remotely controlled devices connection to the core network.
Wi-Fi-6 offers a network throughput rate as much as 400% greater as compared to Wi-Fi-5.
“Wi-Fi 6 can now divide a wireless channel into many sub channels. Each of these sub channels can carry data intended for a different device. This is achieved through something called Orthogonal Frequency Division Multiple Access, or OFDMA. The Wi-Fi access point can talk to more devices at once.
The new riderless standard also has improved MIMO—Multiple In/Multiple Out. This involves multiple antennas, which let the access point talk to multiple devices at once. With Wi-Fi 5, the access point could talk to devices at the same time, but those devices couldn’t respond at the same time. Wi-Fi 6 has an improved version of multi- user or MU-MIMO that lets devices respond to the wireless access point at the same time.”
There will be more micro and edge data centers: “Wi-Fi 6 will make it possible for remote offices, factories and retail outlets to run their own high-speed networks. This will change IT infrastructure, which has largely focused on the edge, in the central data center and in the cloud. Instead, we could see more internal micro data centers in individual plants and facilities.
IT workflows will be more flexible: With Wi-Fi 6, more real-time processing of data will be made possible. This will likely require IT to revise its operational workflows for more real-time processing and less nightly and intra- day batch jobs.”
One of the opportunity that this presents is the ability to use a private 5G network to very large amounts of data without a wired connection between the sites. This could provide for an opportunity for a data center operator to have a hard-wired line via available dark fiber, and have the redundant line a private 5G to provide the redundant data connection.
References
1. Qualcomm: “Everything you need to know about 5G” https://www.qualcomm.com/5g/what-is-5g
2. Hewlett Packard Technical white paper, HPE 5G Core Stack technical white paper, File name: a50002413enw.pdf
3. Hoffman, C. (2020) Wi-Fi 6: What’s Different, and Why it Matters; available at;
https://www.howtogeek.com/368332/wi-fi-6-what%E2%80%99s-different-and-why-it-matters/
4. Cudmore, G. (2021) How Data Centers Must Evolve to Enable 5G and Deliver the IoT; available at;
5. Shacklett, M. (2021) Six ways Wi-Fi 6 will change digital transformation; available at: https://www.techrepublic.com/article/six-ways-wi-fi-6-will-change-digital-transformation/
6. Motiveair; product brochure; available at:
https://www.motivaircorp.com/uploads/files/brochures/ChilledDoor%20brochure_2021.pdf
7. Integra Mission Critical; “Closed Coupled Cooling” product brochure available at https://integra-mc.com/
, patent pending. The website is under construction.
8. Submer: product brochure available at https://submer.com/immersion-cooling/
