Ultra-high-speed Fiber-wireless Transport Technology

Fiber-wireless transport technology is essential for conflguring future networks that will allow optical and radio networks to be seamlessly connected. Advanced optical flber commu- nication using high-speed digital signal processing can be diverted into wireless communication channels to increase the capacity to greater than 10Gb/s. End-to-end modulation and demodu- lation with transmission impairment compensation over the flber-wireless link showed not only a reduction in transmission latency, but also a possible reduction in the total power consumption of the network. To enhance the resilience of the network to disasters and to increase the functionality of the entire network, including optical and wireless networks, flber-wireless transport technology with seamless connectivity between optical and wireless signals is required. From the viewpoint of capacity, there is a big gap between the 100Gb/s of optical transport and the less than 1Gb/s of existing wireless services, which causes a bottleneck in signal transport. Millimeter-wave and terahertz-wave radio are possible candidates for realizing high-speed wireless signal transport. In particular, using a radio-over-flber (RoF) technique, a seamless connection between the optical and radio signals can help realize high-speed wireless transport with retaining the waveform, including the modulation format. Coherent RoF techniques, which use digital signal processing (DSP) diverted from advanced optical coherent communication, will result in advantages in terms of low latency and possible low power consumption features over the entire transmission link (1). This is because the DSP set only at the transmitter and receiver in end-to-end transmission link can mitigate transmission impairments throughout the link; that is, any DSP at an optical-to-wireless conversion or a wireless-to-optical conversion can be excluded. In the W-band (75{110GHz) and the terahertz band (> 300GHz), coherent transmission over optical flber as an optical signal and over free space as a radio signal is demonstrated with a capacity greater than 10Gb/s using a multi-level modulation and demodulation technique with the DSP. The waveform of the signal is seamlessly converted between the optical and radio links. This means that the waveform of the signal is maintained over difierent media; that is, the \waveform-over- flber" technology can realize signal transport via various transmission media using an end-to-end transmission link (2). In the talk, we will discuss a demonstration of high-speed wireless communication connected to an optical flber link using the DSP. Analog signal transmission and its characteristics using advanced optical flber communication technology will be also discussed.