The optical generation and transmission of microwave radio signals is important for future broadband wireless communications. For the first time, bit error ratio measurements were carried out successfully in optical multichannel and single channel transmission experiments at radio frequencies of 12 GHz and 60 GHz, respectively

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A concept is proposed for a pico-cellular network for broad-band mobile communication on a millimeter-wave basis. How microwave optical-signal-processing techniques based on mode-locked lasers (MLL's), optical modulators, and high-speed photo diodes (PD's) can advantageously be applied in the optical feeder lines of a pico-cellular network at 60 GHz is investigated. The external cavity MLL (at 81.25 GHz) used for the experiments showed an single-sideband (SSB) phase noise of 059 dBc/Hz at 100-Hz offset, when actively locked at 6.25 GHz. With the PD, and limited by the V -band mixer equipment, spectral harmonics up to 100 GHz could be detected. For the downlink configuration, a 400-MHz subcarrier is modulated with a 155-Mb/s data signal and upconverted to 62.9 GHz using an MLL and a fast PD. The upconverted sideband at 62.9 GHz was received with an optical power of 014.3-dBm at a bit-error-rate (BER) equal to 10 09 without any additional penalty due to transmitting the signal over 3 km of optical fiber. BER measurements at 155 Mb/s down to 10 011 were made. For the uplink, the digitally encoded RF signal is downconverted also by optical microwave signal processing. A 155-Mb/s data encoded 19.21-GHz signal is downconverted to 460 MHz using a mode-locked laser, an optical modulator, and a 600-MHz optical receiver front end. A receiver sensitivity of 024.5 dBm (BER equal to 10 09 ) is demonstrated with the microwave signal being transmitted over a 1-m radio link and 3 km of optical fiber.Index Terms-Fiber optics, mobile networks, optical communication, optical microwave, radio in the local loop.

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