Frequency Octupling Radio over Fiber System with Multiple Remote Antenna Units

WiMAX is considered for the last mile wireless connectivity to provide flexible broadband services to end users. And Radio over Fiber (RoF) system has attracted industry and research interest to extend the wireless cell coverage and reduce the cost by using the distributed remote antenna units (RAUs). Here, the performance of WiMAX RoF system will be characterized. Results show that the effective RoF transmission fiber length can be limited due to the time division duplex (TDD) framing in the connection using standard WiMAX signal generated by a commercial WiMAX bias station. WiMAX RoF performances of throughput and packet-loss at different link lengths are investigated and analyzed. Besides, a robust TDD switch architecture used in each RAU will be proposed for the WiMAX RoF system.

This paper shows and experimentally demonstrates bidirectional radio over fiber (RoF) using a double-clad fiber (DCF) for optically powered remote antenna units (RAUs). The DCF for an RoF link has a single mode (SM) core and a multimode inner cladding; the SM core is used for simultaneous downlink and uplink transmissions of the optical RoF data signals, whereas the inner cladding is used for optical power delivery to the RAU. The aim of this approach is to optically power the RAU in such a way that external electrical power supplies, such as batteries or public power lines, are not required. The feasibility of the technique is demonstrated by bidirectional RoF transmission over a 100-m DCF optically feeding with 4.0 W. We successfully achieved high downlink and uplink transmission performance in terms of error vector magnitude measurements, which are based on the IEEE 802.11g wireless local area network (WLAN) standard at a carrier frequency of 2.45 GHz.

The development of reconfigurable and high throughput architectures is the utmost target for researchers in the field of Radio over Fiber (RoF). In this paper, we developed a cognitive radio over fiber system lined up with Software Defined Networking owing to improve the quality of transport using a pre-equalization technique. The pre-equalization technique is based on Least Mean Square (LMS) algorithm. It is used to compensate the optical link performance degradation in the RoF system. The simulation results of the overall Bit Error Rate (BER) and the Q factor attest of high system performance improvement.

A radio over fibre (RoF) system is designed to be in an integrated fiber-wireless access network using the millimeter-wave (mm-wave) as a wireless transmission carrier. The design employs the dual-sideband optical carrier suppression (DSB-OCS) technique for mm-wave carrier generation purpose. A dual-electrode Mach-Zehnder modulator (DE-MZM) is used in this technique to generate 40 GHz carrier in order to distribute 1.25 Gbps data via direct modulation (DM) over a 20km RoF system. The link budget shows that Gigabit-per-second (GBps) wireless transmission of 1.4m distance can be achieved using direct modulation laser diode (DMLD) with the bit error rate (BER) of 10−9 and wireless transmit power of −12.38 dBm. The proposed system is able to upgrade existing passive optical network (PON) system to carry high capacity wireless signal for future high speed GBps distribution system.

In this paper, a simplified optical millimeter-wave generated by two optical sidebands beating together in a 60 GHz radio over fiber (RoF) system with 10 Gbit/s 4-pulse amplitude modulation (4 PAM) transmission signal is proposed and simulated. 10 Gbit/s electrical 4 PAM signals modulated are conveyed over the length of 40 km standard single mode fiber (SMF) and recovered via the self-mixing technique after detecting directly at the receiver. Graphs of time-domain wave, frequency-domain and optical spectrum are measured out in different period, and the comparison of error vector magnitude curves of NRZ and 4 PAM signals under the different length of fiber is accomplished. The capacity of 4 PAM modulation is higher, though NRZ performs better than 4 PAM selected in RoF system within 80 km of fiber length as shown in the simulation results.

In order to serve the explosive demands of triple play services or multimedia services with high quality of data transmission in Fifth Generation (5G) communication systems which has availability of large spectrum unlike Fourth Generation (4G), low latency, improved transmission, and increased reliability, an access networks with optical fiber distribution network and wireless enabled technology is urgently needed and therefore, a prominent technology known as Radio over Fiber (RoF) is suggested by researcher/Scientists due to a perfect blend of flexible fiber technology and wireless mobility. RoF technology is helping the data transmission systems from last thirty years with great success and has numerous advantages such as scalability, transparency, antenna site complexity reduction, low installation cost, accessibility of radio carrier by diverse antenna sites dynamically. Millimeter waves (Mm waves) integration in 5G wireless RoF systems comes out to be an encouraging candidate to cater the bandwidth hungry current as well as future generation internet application such as high definition TV (HDTV), online games, video conferencing, and voice over IP (VoIP) etc. For the prolonged reach, economical installations, and improved performance, optimal Mm wave generation methods should be incorporated in 5G such as employing multi carrier generation technique (MCG). Deployment of single mode fiber (SMF) in 5G offers high speed, large capacity, improved security, etc., but also has a prominent limitation of nonlinear effects and it is unwanted phenomenon which degrade the system performance by introducing intermodulation distortion, distortion of signal phase, harmonic distortion, and interference in the neighbouring channels. Minimum modifications of architecture and minimum cost should be spent on the compensation of nonlinear effects or Kerr’s effects in RoF systems and recently mode division multiplexing has emerged as an ultimate solution. In this review article, detailed discussion of an evolutionary technology, i.e., RoF is presented with a literature review, present evaluations, and future challenges. Our utmost goal is to enrich the young researchers with precious aspects for RoF technology on single platform and also encourage them to conduct the technology advancement research works in various fields such as nonlinear compensation, Mm wave generation, dispersion compensation, cost reduction, complexity reduction, and security enhancements for 5G RoF systems.

In this paper, the performance of a 60 GHz radio over fiber (RoF) system with 4/16/64 quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) downstream signals is studied. Delivery of 10 Gbit/s M-ary QAM (MQAM) OFDM signals through the 20-km-long single-mode fiber (SMF) is complicated in terms of intensity modulation and direct detection (IM/DD). Using self-homodyne method, the beating of two independent light waves generating the millimeter-wave at the photodetector can be down-converted to baseband in the electrical domain. Meanwhile, three kinds of sub-carrier arrangement schemes are compared and discussed, and the simulation results show that lower peak-to-average power ratio (PAPR) can be obtained adopting the adjacent scheme. At bit error rate (BER) of 10-3, the receiver sensitivity using 4QAM-OFDM sub-carrier signal is almost enhanced by 4 dB and 9 dB compared with those of 16QAM-OFDM signal and 64QAM-OFDM signal.

In this paper, we present an evaluation of railway communications system based on 5G-RoF technology and millimeter wave band. Filter Bank MultiCarrier (FBMC) modulation is used in this work to generate the 5G waveform, and Radio over Fiber (RoF) technology is used to transport the Radio Frequency (RF) signal from Central Station (CS) to Base Stations (BSs). RoF system is based on Single Side Band (SSB) and Optical Carrier Suppression (OCS) modulations. For railway environment, we have considered the mobile radio channel taking into consideration a high velocity of receiver (train), which is characterized by Doppler effect. We have evaluated, by simulation, the performance of this system in terms of Bit Error Rate (BER) and Error Vector Magnitude (EVM). The simulations show that the length of optical link decreases by increasing the velocity of receiver, and the maximum length of railway track, that can be covered by each CS, is approximately 76 km for a velocity up to 300 km/h.

Radio over fiber (RoF) system is the most appropriate combination of fiber optic link and radio waves. Orthogonal frequency division multiplexing (OFDM)-RoF system can increase the capacity of modulation radio frequency (RF) access with high speed data transmission. The purpose of this paper is modeling and simulation an OFDM-RoF system for fiber length up to 100 km by using 16-quadrature amplitude modulation (16-QAM). OptiSystem 13 software is used for simulation. The proposed model of OFDM-RoF system uses two low pass cosine roll off filter (LP-CROF) as filter at the OFDM stage output and two LiNb-Mach Zehnder modulator (LiNb-MZM) as optical modulator. The results of simulation include the spectrum signal visualizers at the OFDM output, RF to optical upconventer (RTO) output as well as 16-QAM received constellation. The results of simulation have shown that increasing of roll off factor value, it will be broadening in filter band transition. The proposed of RoF-OFDM system is able to achieve fiber length up to 100 km uses 16 QAM sequence bit, the received power is 71.617 dBm with electrical and optical amplifications by using 10 Gbps data signal.

New RoF-PON architecture using polarization multiplexed wireless MIMO signals for NG-PON

현재 이동통신망에서 요구되는 많은 통신량을 수용하기 위해서 새로운 주파수 대역을 사용하는 5G New RAT(: Radio Access Technology) 에 대한 연구가 활발히 진행되고 있다. 하지만, 이러한 새로운 New RAT 기술이 이동통신에 적용되었을 때에 이를 유선 이동통신망에서 수용할 수 있을지에 대해서는 제대로 연구된 바가 없다. 따라서, 본 연구에서는 이러한 New RAT 기술을 RoF(: Radio over Fiber) 기술로 이동통신망의 Fronthaul에서 수용이 가능한지에 대한 연구를 진행하였다. 본 연구에서는 New RAT 의 기술로 밀리미터파 통신기술, 테라헤르츠파 통신기술, 무선 광통신 기술 등을 고려하고, 이들 각각에 대한 RoF 기술의 응용 가능성을 연구하였다. 연구의 결론을 요약하면, 10 년 이내의 범위에서 세 가지 New RAT 기술 중에 밀리미터파 통신기술에 대해서만 RoF 수용성을 고려하면 되는 것으로 판단되며, 빔포밍을 사용하는 경우에는 밀리미터파 통신기술의 요구 전송 대역폭이 너무 많아 Fronthaul 에서 RoF 기술로도 수용이 쉽지 않은 것으로 결론이 내려졌다. 5G New Radio Access Technology(: RAT) is studied by many researchers because the current radio frequency is insufficient to accommodate the increased mobile communication data traffic. However, there are few researches to study on the issue whether the wired mobile network can accommodate the new RAT. Therefore, in the paper, the study on the issue whether the Radio over Fiber(: RoF) system can accommodate the new RATs such as millimeter wave communication, terahertz communication, and optical wireless communication. As a result of the study, only millimeter wave communication deserve to be considered in ten years and even RoF system may not support the increased bandwidth of the millimeter wave communication when beamforming is used.

Future communication needs to be ubiquitous, broadband, convergent, and seamless. Radio over fiber (RoF) technology is one of the most important enabler in access network for the technologies. Adoption of RoF faces bottleneck in optoelectronics, that they are still expensive, high power consumption, and limited in bandwidth. To solve the problem, transceiver in remote antenna unit (RAU) is developed, i.e. electroabsorption transceiver (EAT) and asymmetric FabryPerot modulator (AFPM). This paper compares their coverage range and cost in providing WCDMA and WLAN services. Needed gain of RF amplifier for supporting picocell is also discussed.

In the advancing era of technology the need of fast, reliable and affordable data communication links are the threads weaving this huge world wide web. The biggest challenge for communication engineers is to handle a bulky traffic effectively so that the result is low cost communication. Till the second generation evolution of communication system the network was mostly RF based but with the evolution towards 3G the use of optical spectrum was also inherited. But, the after 3G technologies i.e. 4G onwards the communication network has adopted the optical networks along with the existing RF network to deliver fast and economical communication services with the efficient use of RoF (Radio over Fiber) systems. Through this paper we have studied the performance evaluation of as RoF (Radio of Fiber) system if we used WCDMA-RF signals to be sent over an optical fiber using a TSSB SCM technique. The results obtained shows the effects of various types of interferences on ENR (Energy per bit calculated under the effect of total interference to noise ratio) of the dedicated channel for traffic transmission in WCDMA-RoF systems.

Performance of a 60 GHz RoF system employing Single-Carrier signal modulation was evaluated in a typical laboratory environment to understand the impact of channel characteristics. Broadband channel characteristics were measured using a channel sounding technique, and the resulting impact of the characteristics on the performance of the multi-Gb/s RoF system was assessed experimentally. Varying performance degradation for wireless transmission data-rates ranging from 600 Mb/s to 7 Gb/s was observed as a result of inter-symbol interference caused by signal multi-path effects.

Radio over fiber (RoF) systems use a large number of base stations (BSs) and a number of central stations (CSs), which are interlinked together to form the network. RoF systems use multiple wavelengths for communication between CSs or between CSs and BSs to facilitate the huge amount of data traffic due to the multiple services for a large number of users. When erbium-doped fiber amplifiers (EDFAs) are used as amplifiers in such wavelength-division multiplexed systems, the nonuniform gain spectrum of EDFAs causes instability to some of the channels while providing faithful amplification to other channels. To avoid this inconsistency, the gain spectrum of the amplifier needs to be uniform along the whole usable range of wavelengths. A gain contouring technique is proposed to provide uniform gain to all channels irrespective of wavelength. Optical add/drop multiplexers (OADMs) and different lengths of erbium-doped fibers are used to create such a gain contouring mechanism in the optical domain itself. The effect of a cascade of nonuniform gain amplifiers is studied, and the proposed system mitigates the adverse effects caused due to nonuniform gain-induced channel instability effectively.