To meet the anticipated future demand for optical wireless high data rates, our study proposed a deep learning model-based adaptive digital pre-equalization scheme for visible light communication (VLC) channels is proposed to increase the data rate. We established the deep learning model to predict pre-equalization parameter (PEP) which is adaptive for various VLC channels. The proposed system is flexible and adaptive for commercial light emitting diode with different channel conditions. It improves the bandwidth of different VLC channels up to 125 MHz and has been validated on a 250-Mbps testbed. Based on the experimental results, the PEP update time is at most 5.1 s, and the bit error ratio is always <1 × 10 − 6 while using the PEP in the deep learning network. Meanwhile, the predicted and optimal values of the PEP correspond at 250 Mbps, and the maximum error between the predicted and optimal values of the PEP are only 7 for various channel conditions, including optical power, data rate, send distance, and send angle. The adaptive pre-equalization capability of the proposed system would be a universal digital solution for high-speed access in 6G scenarios combined with the VLC spectrum.
In order to improve the system bandwidth and realize high-speed real-time visible light communication, this paper proposed an analog pre-emphasis method based on a red LED, which equalized the high-frequency signal of the red LED in the frequency domain. A field programmable gate array (FPGA) generated non-return-to-zero on-off keying (NRZ-OOK) modulated signal, which was pre-emphasized by an analog pre-emphasis circuit and then emitted by a red LED. The experimental results show that the proposed method achieves a communication rate of 246Mbps and a BER of 0 under the experimental conditions of a communication distance of 3m, LED power of 0.3W, and a real-time communication duration of 1 hour.
We propose an artificial neural network-embedded visible light positioning (VLP) scheme based on a conventional monitoring system in which the transmitter and receiver comprise a single illuminating LED and two standard surveillance cameras, respectively. Experimental results show that this simple system achieved millimeter-level positioning accuracy and exhibited good antitilt ability and robustness. The VLP system achieved high-precision three-dimensional positioning with a mean positioning error (MPE) of 0.76 cm, even if the object was inclined at different angles. Moreover, the MPEs of the single-light system were only 0.65 and 0.67 cm when the tilt angle was 15 deg and −15 deg, respectively. This scheme is a low-cost solution for accurate positioning that could be applied in marine vessel operations, mining operations, shopping center, supermarket, factories, and warehouses where monitoring systems presently exist.
We propose a Visible light positioning (VLP) system which can satisfy the requirements in the places where monitors are required to grasp the location of multiple people or vehicles, such as unmanned supermarkets, warehouses, factories, and other large buildings with safety issues. Which means when the security cameras capturing images, the coordinates of the objects can be obtained and displayed at the same time. This novel Multiple Input Multiple Output (MIMO) VLP system which can monitor multiple objects at the same time provides accurate and high-speed multiple objects indoor positioning based on the Space Division Multiple (SDM), Wavelength Division Multiplexing (WDM) and the under-sampled phase shift ON-OFF keying (UPSOOK). The experimental results show that the proposed system achieves accuracy of 10cm with the range of tilting angle degree is 0° to 45°. The result means the system does well in robustness and accuracy.
KEYWORDS: Receivers, Ultraviolet radiation, Telecommunications, Signal to noise ratio, Scattering, Signal processing, Signal detection, Monte Carlo methods, Lithium, Signal attenuation
The experiment is designed and taken to measure the link gain in a single-input multiple-output ultraviolet (UV) communication system with diversity reception, and the correlation of multichannel is also taken into account. Theoretical and experimental research on the multireceiver UV communication system suggests that diversity reception is an effective way to gain high BER performance even if the link gain correlation is non-negligible (with normal level correlation coefficient). The link gain of diversity reception is compared particularly with the gain from expanding the detecting area to find its boundary for performance improvement and the distance limit between receivers. The experimental results provide more reliable guidelines for receiver design in UVC systems and other scattering wireless optical communication channels with diversity reception applied such as multiple-input multiple-output.
KEYWORDS: Ultraviolet radiation, Telecommunications, Receivers, Transmitters, Antennas, Non-line-of-sight propagation, Signal to noise ratio, Optical communications, Error analysis, Monte Carlo methods
The Alamouti code can obtain the diversity gain utilizing the transmitting signal orthogonally without the use of a complicated decoding scheme. The modified Alamouti code for the ultraviolet (UV) communication system is studied in theoretical analysis, MATLAB® simulation, and offline experiment. The theoretical analysis and simulation results indicate that the usage of the Alamouti code in the UV communication system can achieve a higher diversity gain and reduce the system bit error rate more effectively than the single-input single-output and single-input multiple-output technologies. The experiments were performed to verify the simulation results. Next, we analyzed the discrepancy between the simulation results and the experimental results. These studies are helpful for UV multiple-input multiple-output communication system design and implementation.
Polarization mode dispersion (PMD) is one of the major obstacles in high-speed (above 100 Gbits rate)
and long-haul optical communication system. In order to meet the requirements of high-sped optical
communication quality, some PMD compensation and mitigation schemes had been developed. Forward error
correction (FEC) is useful to increasing the system margin. The combination of distributed fast polarization
scrambler (D-FPS) and FEC is an effective method to improving the optical system's PMD tolerance. The
fundamental reason is that D-FPS can accelerate the redistribution of the link PMD to enable FEC to be more
effective during the periods that would otherwise have PMD outages. Another advantage of this scheme is that it
can mitigate the influence of PMD in multichannel system without feedback control and compensation based on
each channel. The principle and performance of scrambling is introduced in this paper and the fundamental idea of
improving PMD mitigation by using D-FPS combined with FEC is proposed. Some key factors such as scrambling
speed and the number of scrambler which affecting the performance of this scheme are also introduced. Finally,
proposing an assumption that the impact for system performance caused by the style of FPSs is distributed along
the fiber link, and the mathematical estimation model is established. The combination of D-FPS and FEC would be
a promising approach for performance improvement in ultra-high-speed optical communication system.
A routing architecture based on PCE has been designed for the large, multi-layer and multi-domain optical networks, and
a PCE-based fast reroute algorithm has been proposed for multi-failures in multi-domain optical networks.
In WDM networks, when a session request is received by the network, the problem of establishing light-paths by
routing and assigning a wavelength to this connection session is called the Routing and Wavelength Assignment (RWA)
problem. The selection of routing algorithm and wavelength assignment method is the key point to solve this problem.
And the flooding technique is always used for those routing algorithms to get the resource status and topology
information. In this paper, we propose a novel routing algorithm, Rank Total wavelengths and Available wavelengths
(RTAW), which dramatically reduces the flooding frequency while guaranteeing a low blocking rate. Compared with
other algorithms, the simulations results prove the benefits of this algorithm.
A novel multi-domain L1VPN provisioning architecture is proposed based on service plane of the adaptive multiservices
provisioning platform. It can provide the inter-domain L1VPN services flexibly, and can establish different
L1VPNs by analyzing different service characteristics and constraints. Moreover, the architecture we proposed was
experimentally demonstrated in our AMSON testbed.
We developed a framework for constraint routing in multi-domain optical network which combines PCE with service
plane. With the distributed routing computation characteristic of PCE and the adaptability of service plane for service
attributes, the framework provides an optimal SLA-based constraint routing strategy. Experiment results verify our
framework and strategy.
The implementation of Cloud Computing over optical networks faces many challenges and opportunities. A cloud
computing architecture over optical networks is proposed based on the service plane. And the validity of the architecture
we proposed was experimentally demonstrated in our Adaptive Multi-Service Optical Network testbed.
In this paper, a dynamic impairment-aware routing and wavelength assignment (RWA) algorithm is proposed to
efficiently provide signal-quality-guaranteed connections and achieve lower blocking probability in all-optical wavelength
division multiplexing (WDM) network with high speed optical channel. In the all-optical network, optical connection is
set up to carry data signal from source node to destination node without optical-electrical-optical (OEO) conversion via
all-optical lightpath. During the travel, the signal transmitted along the lightpath must pass through a number of optical
components, such as optical amplifiers, optical crossconnect switches (OXCs) and fiber segments. While the optical signal
propagates to the destination, the impairment would accumulate along the all-optical lightpath with these components,
which makes the quality of signal degrade continuously. When the impairment accumulation comes to a serious degree,
the bit-error rate (BER) would be too high to be acceptable in the destination receiver, the good quality of service for a
connection request could not be provided in physical layer and the connect request would be rejected in control plane
because of impairment accumulation. Therefore new techniques in both physical layer and network layer are necessary for
decrease the influence of impairment accumulation. Here we investigate a new dynamic RWA algorithm to lower
blocking probability of connection. By jointly consideration of both available wavelength and wavelength dependent
impairments, the routing weight functions can be dynamically updated to accommodate between wavelength blocking and
physical layer blocking. Simulation results indicate that the proposed algorithm can achieve lower blocking probability.
A novel framework named Service Plane is put forward in transport networks on the basis of the principle of adaptive
multi-services provisioning platform. The flexible implementation of service and the expansibility of framework is what
we concern most in this kind of Service Plane. Here we raise the core algorithms of bandwidth on demand service on this
platform, simulation testbed and the implementation result are also presented in this paper.
The complexity of optical networks has been researched and some complexity laws are described here. Then
some metrics from complex networks, such as mean path length, node's degree distribution and node's
clustering coefficient have been introduced into optical networks. The invulnerability in complex optical
networks is mainly researched in this paper.
Three methods of distributed reservation named FQRP (Forward Queue Reservation Protocol), FRP-λ (Single
Wavelength Forward Reservation Protocol) and Extension of FRP in optical network are proposed in this paper. The
three methods make some improvements on the traditional FRP (Forward Reservation Protocol) and BRP (Backward
Reservation Protocol). They are described, analyzed and simulated in detail in this paper. The simulation results show
that they do have advantages over the traditional two methods. Each has its own advantage.
Transparent optical WDM networks have been expected to be the most effective solution to achieve high throughput transmission, in which a GMPLS control plane is used to manage both IP layer and the optical transport layer. However, current GMPLS does not take the influence of physical impairments during data transmission process into account. This paper proposes a signaling-based approach to implement self-adaptive transmission control (SATC) in impairment-aware transparent WDM networks. The function of standard control plane of automatic switched optical network is enhanced to realize this aim. Two evaluation schemes are proposed for the implementation of this approach. Simulations are conducted for proof of benefits gained by introducing SATC.
Two methods of reservation namely ANIR (all nodes-initiated reservation) and MSR (multi-states reservation) are proposed and compared with SIR (source-initiated reservation) and DIR (destination-initiated reservation). The four methods of reservation are simulated in NSFNET and ARPA topologies. Numeric results show that the blocking probability of ANIR is lower than SIR, but the number of packages which it generates is larger, and the blocking probability of MSR is lower than DIR and SIR under light load.
KEYWORDS: Switching, Optical switching, Optical networks, Ferroelectric LCDs, Optical testing, Signal processing, Switches, Virtual colonoscopy, Control systems, Process control
Multi-Granularity optical switching technology has only recently attracted attention from the optical networking industry for its practical importance in reducing port count, the associated control complexity, and the cost of optical cross-connects (OXC). In this paper, the advantage of MG-OXC comparing to the ordinary OXC is introduced and the Multi-Granularity Optical Switching test-bed based on ASON (Automatically Switching Optical Network) is presented. This test-bed is composed of three different plants, namely the transport plane, the control plane and the management plane. We have analyzed the architecture of MG-OXC and provided the scheme of multi-granularity optical switching node. In the end some experiments have been done. We firstly have done the experiment in the creation and release of optical path. The optical path could be a wavelength path or a waveband path. And the second experiment has been done to test the capacity of the traffic grooming in the multi-granularity optical networks. The last experiment is performed to test the protection and restoration under the conditions of the node failure, the wavelength failure and the waveband failure, etc. Finally the results are reported and they show that the test-bed can achieve the expected functions under the control of the control plane of ASON.
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