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NEC Corporation (NEC) announced on March 4, 2020 the successful demonstration of bidirectional 10Gbps outdoor transmission. This was accomplished by using all-outdoor packet microwave radios with Radio Frequency (RF) IC compatible with the D-band (130-174.8GHz), and will help to meet the increasing demand for 5G networks. NEC plans to apply this advanced technology to its "iPASOLINK" series of super compact microwave radio products and aims to expand its usage into both mobile fronthaul and backhaul networks, which are required to be ultra-high capacity in order to support 5G commercialization.
As data traffic for 5G networks evolves, the transmission capacity of mobile fronthaul and backhaul is expected to reach 10Gbps ~ 100Gbps. Within this environment, the expansion of radio bandwidth or higher modulation schemes will become mandatory for wireless transmissions. Specifically, the wide bandwidth of D-band (130-174.8GHz) has recently been attracting attention.
In order to enable this 10Gbps outdoor transmission, NEC developed RF modules comprised of an RF IC chipset operational in the D-band. The RF ICs, flipchips-mounted on a quartz glass plate, have multiple functions, such as amplifying and converting frequency.
NEC successfully achieved this 10Gbps error-free outdoor transmission at a distance of 150m in D-band with Frequency Division Duplex (FDD) by using all-in-one prototype equipment. In the demonstration, the frequency points for the transmitter and the receiver were 142GHz and 157Hz respectively, the modulation scheme was 128QAM, and modulation speed was 1.6Gbaud¹.
Additional field tests were conducted throughout a 4 month period over an approximate 1km link distance as part of preparation for practical applications. Going forward, NEC is seeking to confirm parameters necessary for link design based on the recommendations of the ITU-R², such as how to expand to D-band when considering the relationship between rainfall and communication availability.
NEC aims to develop equipment applicable to mobile fronthaul and backhaul networks for 5G base stations by utilizing the D-band RF technology and the knowledge of propagation characteristics obtained from this trial.
This research and development was conducted as part of "The Research and Development Project of Orbital Angular Momentum (OAM) Mode Multiplexing Radio enabling Ultra High Capacity Transmission in Millimeter wave bands" under a contract with the Ministry of Internal Affairs and Communications, Japan.
(1) Baud: the number of symbols per second in a digital modulation system.
(2) ITU Radiocommunication Sector
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