Wide-band millimeter-wave/optical-network applications in Japan

Abstract

This paper describes work on wide-band millimeterwave (MMW)/optical-network applications in Japan-in particular, projects being pursued at the Advanced Telecommunications Research Institute (ATR). Digital-signal transmission at 118 Mb/s was tested. Results of the experiments demonstrate that highspeed digital-signal transmission, with a total carrier-to-noise ratio (C/N) degradation of less than 1.2 dB from a modem at a BER of 10 06 , is feasible. Similarly, analog FM-signal transmission with a weighted S/N of more than 45 dB is also feasible at a signal bandwidth of 18 MHz and FM carrier frequency of 43.75 GHz. Based on these results, a demonstration system was constructed, and the feasibility of the system was confirmed. Several key technologies for system construction such as an MMW optical modulator and an MMW high-speed p-i-n detector and some related technologies are also described. In addition, an advanced system considered suitable for future high-speed mobile communications is proposed. This system employs an optical signal-processing multibeam antenna, where the direction of each sharp beam can be adaptively controlled.Index Terms-Beamforming network, millimeter wave, millimeter wave/optical interaction, millimeter-wave subcarrier system, mobile communication system, optical signal-processing antennas.

Optical subcarrier multiplexing transmission for base station with adaptive array antenna

“…The LO signals of the BS can be written as (4) Here, their angular frequencies are as follows: (5) After mixing and , the two antenna output signals can be expressed as follows: (6) and (7) where (8) is the converted angular frequency for the two weight-modified signals due to the frequency conversions. The phase rotation depending on the arrival time is in common with all antenna branches, and is given by (9) Different phase rotations depending on the IFs via the optical fiber are cancelled due to the frequency conversion with the LO signals . Therefore, the relative phase among antenna branches can be maintained independently of the arrival time .…”

“…This technique makes it possible to process complicated operations in a center station (CS), such as modulation/demodulation and weight controllers. Among several optical-fiber links for transmitting antenna output signals from the CS to the BS or antenna input signals from the BS to the CS, optical-fiber-parallel (OFP) transmission [7], [8] and wavelength-division-multiplexing (WDM) transmission [9], [10] have been proposed. These transmissions require as many optical transmitters/receivers as antenna branches.…”