NEC develops radio-over-fiber system with greater installation flexibility

Tokyo, Japan – June 6, 2016 – NEC Corporation (NEC; TSE: 6701) today announced the development of a radio-over-fiber system that makes it possible to perform high-speed and stable wireless communication in places where it is often difficult to establish wireless connections, such as high-rise buildings, underground shopping malls and factories.

The system divides wireless equipment, such as wireless LAN access points or mobile base stations, into antenna and control units that are connected with each other through a fiber optic cable. The system also employs "phase-clocking digital modulation technology," which is capable of reducing the quantization noise included in the digital radio signal by 50%. With the introduction of this technology, antenna units will no longer need digital-to-analog converters or frequency converters. This makes it possible to reduce the size of antenna units by up to 80%, realizing greater installation flexibility of antenna units.

The system ensures stable wireless communication with centralized controllability capable of choosing the optimal frequency and/or wireless access technology. This makes it possible to mitigate radio wave interference and dead zones for wireless communications, without changing or adjusting the antenna units.

With the system in use, NEC has conducted a transmission trial using LTE signals in the 2.14 GHz band. In the trial, NEC demonstrated that the system can transmit signals between antenna and control units of LTE base stations using a fiber optic cable for a distance of 18 kilometers without damaging the quality of the signals.

"The newly developed radio-over-fiber system will help introduce wireless network systems in a more flexible manner in places where it is often difficult to establish wireless connections," said Yuichi Nakamura, General Manager, System Platform Research Laboratories, NEC Corporation. "The system will also help factories equipped with a range of Internet of Things devices, such as robots and sensors, introduce wireless network systems. NEC remains committed to promoting research and development in pursuit of finding practical uses for the system."