Successful Demonstration Experiment to Improve Outdoor Communication Environment Through Low-E Glass

NTT Docomo Inc. (hereinafter, Docomo) and AGC Inc. (hereinafter, AGC) have conducted a demonstration experiment (hereinafter, this demonstration) to verify improvements in outdoor communication quality through building windows in commercial service areas. This was achieved by combining the radio wave transmissible glass antenna "WAVEATTOCH®*1 (hereinafter, glass antenna)" jointly developed by both companies with AGC's radio wave transparent processing technology*2. In this demonstration, radio wave transparent processing was applied to existing Low-E glass*3 in a building on-site, and the glass antenna was installed on the indoor surface of the glass. As a result, it was confirmed that even through Low-E glass, outdoor 5G communication signals were strengthened, leading to an approximate 10dB improvement in received power (approximately 10 times the power ratio). Figure 1. Image of this demonstration Docomo and AGC have been working on "turning windows into base stations" since October 2019 by jointly developing a glass antenna capable of radio wave transmission and reception, which is attached to the indoor side of building windows to expand outdoor communication areas (service areas).*4 On the other hand, Low-E glass, which is increasingly adopted due to the trend of energy saving in recent years, is coated with a metal film on its surface, and has characteristics that make it particularly difficult for high-frequency radio waves such as 5G to penetrate. For this reason, it has been a challenge that the glass antenna cannot exhibit its original performance even when attached. In this demonstration, AGC's developed radio wave transparent processing technology was applied to existing Low-E glass through on-site construction, and the glass antenna was installed on the glass surface. As a result, compared to conventional Low-E glass without radio wave transparent processing, it was confirmed that the area where outdoor 5G services can be used has expanded.*5 It has also been confirmed through laboratory tests that Low-E glass with radio wave transparent processing has no impact on its energy-saving performance, strength, or durability. Figure 2. Confirmation results of this demonstration Docomo and AGC will continue to explore the utilization of glass antennas and work on improving communication quality in locations where installing base station antennas is difficult. *1 "WAVEATTOCH" is a product name of AGC. *2 A surface treatment technology that imparts radio wave transparency without altering the energy-saving performance, durability, strength, etc., of Low-E glass, and is characterized by its on-site application to building windows. *3 Glass coated with a metal film for energy saving. High-frequency radio waves such as 5G may have difficulty penetrating due to the metal film. *4 October 1, 2019, NTT Docomo Inc. and AGC Inc. Press Release (Notice) "Docomo and AGC Start Providing Service Area Using 'Glass Antenna that Turns Windows into Base Stations'" *5 AGC is also working on improving radio wave improvement in the Outdoor-to-Indoor (O2I) direction, in addition to the Indoor-to-Outdoor (I2O) direction demonstrated in this experiment, and has conducted prior demonstrations. The radio wave transparent processing technology developed by our company can contribute to improving the communication environment in both I2O and O2I directions and is a technology that can process building windows on-site. We will continue to conduct various demonstration experiments and consider the commercialization of radio wave transparent processing technology. Appendix Overview of this Demonstration 1. Objective To confirm that the glass antenna can achieve its conventional performance through Low-E glass by applying radio wave transparent processing. 2. Overview of this Demonstration Using a real building in Kyoto Prefecture, we verified how communication quality improves with the glass antenna, with and without radio wave transparent processing. This demonstration was conducted in two configurations, which were installed in the same location for comparison. ■ Configurations for this Demonstration (1) Low-E glass + glass antenna (2) Low-E glass (with radio wave transparent processing) + glass antenna 3. Results of this Demonstration For each of the two configurations in this demonstration, we compared the outdoor signal strength. Compared to the configuration of "Low-E glass + glass antenna" (without radio wave transparent processing), the configuration of "Low-E glass (with radio wave transparent processing) + glass antenna" showed an improvement in signal strength of approximately 10dB in the median cumulative distribution, confirming an expansion of the outdoor communication coverage area. The combination of radio wave transparent processing and the glass antenna demonstrated that building windows can be utilized as antennas while maintaining the insulating and energy-saving performance of Low-E glass. ■ Demonstration Scene Low-E glass (with radio wave transparent processing) and glass antenna used in the demonstration experiment. ■ Demonstration Results Using the cumulative distribution of received signal strength from the glass antenna outdoors, a before-and-after comparison was conducted in the same area. The measurement results after radio wave transparent processing confirmed an approximate 10dB improvement in received signal strength at the median (cumulative distribution of 0.5). These results confirmed the realization of radio wave improvement from the indoor to outdoor direction, even with Low-E glass, through the radio wave transparent processing technology.