Abstract
The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.
Highlights
Generation access networks are planned to provide customers with high data rate, broadband multiple services, and flexible communication
Where Q is the number of signal levels within each branch of the constellation diagram, log2M is the amount of bits encoded into one quadrature amplitude modulation (QAM) symbol, and k is a modulation format-dependent factor giving the relationship between maximum field magnitude and average overall M field magnitudes defined by the constellation diagram for the chosen modulation format
The performance of error vector magnitude (EVM) and the bit error rate (BER) is evaluated for the 16-QAM multi-input multi-output (MIMO) signals without using forward error correction (FEC) techniques
Summary
Generation access networks are planned to provide customers with high data rate, broadband multiple services, and flexible communication. Transmission of three MIMO radio signals all with 2.44 GHz carrier frequency over an optical fiber was proposed and demonstrated using an electrical single-sideband frequency translation (ESSB-FT) technique [10]. Three wireless 16-QAM MIMO signals were proposed to be transmitted over a 20 km SMF using the optical single-sideband frequency translation (OSSB-FT) technique (which is considered as OFU technique) [11]. These wireless MIMO signals were modulated using the carrier frequency of 2.44 GHz and optically modulated using the optical doublesideband (ODSB) modulation scheme.
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