T. Kanesan, W. P. Ng, Z. Ghassemlooy, and C. Lu, "Experimental Demonstration of the Compensation of Nonlinear Propagation in LTE RoF system with Directly Modulated Laser," in Communications (ICC), IEEE International Conference on, Budaphest, Hungary, pp. 1-4, 09-13 June, 2013. (original) (raw)

IEEE ICC 2013

This paper reveals that nonlinear propagation is a critical problem for the long term evolution (LTE) technology based on the radio-over-fibre (RoF) system. Therefore, a direct modulation based frequency dithering (DMFD) method is proposed for nonlinear propagation compensation, namely the self phase modulation (SPM) and stimulated brillouin scattering (SBS). We found that DMFD method operates substantially different in RoF systems. The major difference is that DMFD signal frequency fd has to be much smaller than the RoF carrier frequency fRF; thus the condition of {fd << fRF} has to be stringently obeyed. Analysis of the optical launch power (OLP) with DMFD method reveals that the SBS threshold is above ~6 dBm for LTE-RoF system. In addition, we also unfold that DMFD method does not induce an additional distortion for the linear and optimum OLP regions, which are frequency chirp dependent. Hence the proposed method improves the LTE-RoF system without any shortcoming. Finally, at OLP values of 8 dBm and 10 dBm, LTE-RoF system exhibits an average error vector magnitude (EVM) improvement of ~4.32% and ~6.18%, respectively, for the 50 km transmission span.

Optimization of Optical Modulator for LTE RoF in Nonlinear Fibre Propagation

2012

This letter proposes an optimized launch power for the direct detection of optical orthogonal frequency-division multiplexing (DD-OOFDM) for radio-over-flber (RoF). The aim is to optimize the physical layer connectivity for the third generation partnership program-long-term evolution employing RoF technologies. We also analytically derive an expression for the distributed-feedback laser, laser-induced positive frequency chirping, incorporating the phenomena that induce phase distortion at the receiver, and explicitly explain the transient chirp of DD-OOFDM. Results show that transmission at the optimized launch power of -4 dBm improves the system power efficiency of 16-quadrature amplitude modulation (QAM) DD-OOFDM by ~20% and ~37%, 64-QAM DD-OOFDM by ~21% and ~35% compared to launch powers in the linear and nonlinear regions, respectively.

T. Kanesan, W. P. Ng, Z. Ghassemlooy, and C. Lu, "Impact of Optical Modulators in LTE RoF System with Nonlinear Compensator for Enhanced Power Budget," in Optical Fiber Communication Conference/National Fiber Optic Engineers Conference (OFC/NFOEC) 2013, Anaheim, California, 2013, pp. 1-3.

OFC/NFOEC 2013, IEEE/OSA

Nonlinear propagation compensation for LTE-RoF system is experimentally demonstrated with proposed DMFD and EMFD methods. We discovered that the RoF dithering frequency requirement have to be much smaller with an average improvement of ~5.35 dB.

Solution to reduce nonlinearity in LTE RoF system for an efficient DAS topology: A brief review (Invited)

2016 10th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP), 2016

In this paper, a review on radio-over-fiber (RoF) technology is conducted to support the exploding growth of mobile broadband. An RoF system will provide a platform for distributed antenna system (DAS) as a fronthaul of long term evolution (LTE) technology. A higher splitting ratio from a macrocell is required to support large DAS topology, hence higher optical launch power (OLP) is the right approach. However, high OLP generates undesired nonlinearities, namely the stimulated Brillouin scattering (SBS). Three different aspects of solving the SBS process are covered in this paper, where the solutions ultimately provided an additional 4 dB link budget.

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T. Kanesan, W. P. Ng, Z. Ghassemlooy, and C. Lu, "FFT size optimization for LTE RoF in nonlinear fibre propagation," in Communication Systems, Networks & Digital Signal Processing (CSNDSP), IEEE 8th International Symposium on, 2012, Poznan, Poland, pp. 1-5.

IEEE CSNDSP 2012