Millimeter wave cell density and building penetration
LONDON—Millimeter wave frequencies will be a central part of delivering the ultra high capacity data throughput associated with 5G, but, given its unique propagation characteristics, putting high-band spectrum to work is a challenge.
During a keynote session at 5G World, Samsung Networks VP and Head of Technology Strategy Group Wonil Roh, highlighting a number of test scenarios, set to work separating fact from fiction when it comes to millimeter wave.
First up, Roh took on the cell density required to provide millimeter wave coverage in a congested, outdoor, urban area. Because millimeter waves don’t travel near as far as their sub-6 GHz counterparts, there’s something of a notion that providing coverage will require incredibly dense networks. Not so, Roh said.
“In downtown Seoul, we colocated 28 GHz 5G base stations with LTE base stations; 29 of them total. Our result in terms of outdoor coverage, we achieved 99% of the coverage we achieved with LTE if we use the outdoor CPE.” In a mobile use case with a 5G-compatible table, “We have about 94% coverage as we have done for LTE. The speed, the data rate, is a lot faster than LTE. Using 28 GHz spectrum, we achieved 1 Gbps—so same coverage, but 100-times faster, same number of base stations. Now we are confident that at least for covering the urban area outdoor, we can expect a similar number of base stations for millimeter wave as we have done for LTE.”
Roh said Samsung is developing a software tool to help customers optimize their cell planning process and reduce the total number of base stations in a given area.
Next he took on millimeter wave for outdoor-to-indoor penetration. “This could be an issue,” Roh said, particularly given modern construction materials like low emissivity glass, which is notorious for hindering an outdoor-in approach to in-building coverage.
Working with Verizon in the U.S., which is planning to commercialize 5G fixed wireless in four cities later this year, Roh said, “We have achieved a reasonably good speed” with the CPE placed both inside the building and in the window. He rolled a Verizon video showing a CPE located inside a building (but not in the window) tallying speeds in the 800 Mbps range. And, if that’s not enough, Roh said Samsung has devised an alternative installation option wherein the CPE is physically located on a building’s exterior.
