Optical/electrical two‐step heterodyne technique for 60‐GHz Radio‐On‐Fiber downlink

Abstract

AbstractIn order to economically realize a Gbit/s class downlink using 60‐GHz millimeter waves, the authors have previously proposed an optical/electrical two‐step heterodyne system, based on the Radio‐On‐Fiber (ROF) transmission technique, in which millimeter‐wave filters at the wireless base station and a millimeter‐wave local oscillator at the wireless terminal are unnecessary. In this paper, for four types of three‐wave/four‐wave optical transmission method realizing the proposed scheme, the CNR of the IF signals obtained at the wireless terminal is analyzed and an optimization method is found for optical power distribution to each of multiple wavelength optical signals. The analytical results are compared to show that the scheme for generating three‐wave millimeter‐wave signals from four‐wave optical signals has excellent characteristics for application to either a feed or a nonfeed base station. At the wireless terminal, deterioration can be reduced to about 6.5 dB and about 4.8 dB in comparison with the conventional scheme using a millimeter‐wave local oscillator. Further, the output from a single optical source is optically modulated with two‐wave 30‐GHz‐band signals, and then the above optical transmission system generating the four optical signals is used for generation of the 1.0 Gbit/s‐BPSK millimeter‐wave/IF signal and for demodulation by synchronous detection. It is demonstrated that a BER of less than 10−9 can be obtained for a PD input optical power of −11 dBm even in 10‐km SMF transmission. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(3): 9–20, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20337