A novel multi-parameter sensor has been proposed based on the W-type leaky fibre grating. The resonant wavelength for different mode in the reflection spectra has the same temperature sensitivity of ~9.13 pm/oC, but the reflection intensity has no dependence upon the temperature. The resonant wavelength of different mode linearly varies a little with refractive index increasing, however, its reflection intensity follows the negative exponential decay. The resonant wavelength for each mode almost linearly responds to the displacement, giving out a displacement sensitivity of 99.94 pm/mm. However, the reflection response to the displacement varies a lot. Based on these results, simple and compact multi-parameter fibre sensors are proposed based on W fibre grating.
We propose and experimentally demonstrate a simple directional bending sensor based on an in-line Mach-Zehnder interference structure of the single mode fiber (SMF)-multimode fiber (MMF)-asymmetrical twin-core fiber (ATCF)- MMF-SMF. Due to the asymmetric structure in twin-core fiber, this sensor can discriminate different bending directions. The interference spectrum shifts with the change of curvature. Furthermore, the sensor exhibits a linear response with a maximum bending sensitivity of 33.48 and -38.72 nm/m-1 in the curvature range from 0 to 3.01 m-1 for bending directions at -x (180°) and +x (0°) directions, respectively. The proposed fiber sensor has great potential in the future Internet of Things (IoT) due to its advantages, such as low cost, compactness, and high bending sensitivity.
Resource allocation management is the key issue to improve the performance of visible light communication (VLC) / WiFi hybrid network. This paper proposes an improved resource allocation algorithm based on proportional fairness (PF) algorithm. Its main idea is to compensate users, and then establish a VLC / WiFi hybrid network model to simulate the traditional algorithm and the improved algorithm respectively, It is verified that the improved algorithm has better fairness and higher throughput than the traditional algorithm.
In order to solve the problem of joint resource management algorithm of visible light communication (VLC) and WiFi heterogeneous network, this paper studies different resource scheduling algorithms, and finally chooses improved proportional fair (PF) algorithm to improve the system in different regions of the user access to resources, and optimize the utilization of resources. The simulation results show that the optimized scheduling algorithm can improve the system throughput, fairness and access delay probability (ADP).
KEYWORDS: Telecommunications, Optical fibers, Extremely high frequency, Wireless communications, Radio over Fiber, Eye, Networks, Signal attenuation, Optical networks, Modulation
In order to meet the high bandwidth requirements of next generation access network, this paper combine the advantages of radio over fiber (RoF) and wavelength division multiplexing passive optical network (WDM-PON), and propose the RoF-WDM-PON system architecture. MZM modulation technology is adopted to realize the signal transmission from the center station to the base station, which can meet the demand of high bandwidth and realize the low loss transmission of 20km in the meantime. Simulation results verify the effectiveness and reliability of the proposed scheme.
The increasing demand of mobile network communication bandwidth requires more information in the limited bandwidth. In this paper, a novel bidirectional transmission system architecture based on RoF-PON system and PWoF system is proposed, and the transmission performance of the hybrid system is simulated. In RoF-based mobile networks, the use of PWoF realizes the centralize power in CO, providing a more cost effective installation method for communication networks, as well as ease of operation and maintenance. The simulation results of the system verify the reliability and feasibility of the system, which proves that the hybrid transmission system of PWoF and RoF-PON can realize the bidirectional transmission of energy and wireless signals.
In the heterogeneous network of visible light communication and WiFi, the fairness index of users is a key index when allocating resource bandwidth. In order to improve the fairness of the system, the average request rate of users and the distance from the wireless access point are mainly considered, and a new weight-based multi-team resource allocation algorithm is proposed to judge the priority of users based on these two indexes. First, the request rates of users are ranked in order, and the first and last two users are formed into a queue, and the first allocation is made according to the weight of the queue, and then the second allocation is made according to the respective weights of the users in the queue. The simulation results show that the fairness index is improved and the improved algorithm can be applied to resource allocation in heterogeneous networks.
We report a simple refractive index (RI) sensor based on a twin-hole fiber (THF). The THF is fused with the single-mode fiber to realize sensing by the multimode interference. The mode transmission characteristics in the THF are numerically investigated. In the sensing experiment, when the surrounding RI changes, the wavelength shift of the transmission spectrum shows approximate linearity in the low RI region and nonlinearity in the high RI region. When a THF with the length of 10 mm is used, the highest sensitivity can be up to 1351 nm / RIU in the RI range from 1.430 to 1.445. Moreover, the effect of the temperature on the transmission spectrum relative to the RI is much smaller when the external temperature changes from 30°C to 80°C.
KEYWORDS: Modulation, WDM-PON, Signal detection, Wavelength division multiplexing, Radio over Fiber, Passive optical networks, Optical networks, Broadband telecommunications, Radio optics
This work reports the integration and experimental performance analysis of wavelength division multiplexing passive optical network (WDM-PON), compatible with radio over fiber (RoF) technology. Fixed mobile convergence has been discussed, focusing on how to use available fixed and mobile access infrastructures to meet the requirements of future broadband networks. The proposed architecture enables to simultaneously transport RF and baseband signals through a single-mode fiber (SMF). Optical carrier suppression (OCS) modulation scheme has been proposed to improve the spectral efficiency. Bit error ratio (BER) of 10-4 has been obtained at 1 Gb/s date rate under the transmission of 25km.
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