Backup Link Research Articles

A Novel Hybrid FSO-mm Wave System for Enhanced Mobile Network Capacity and Reliability

The ever-growing demand for high-bandwidth communication in mobile networks necessitates innovative solutions that provide exceptional capacity and reliability. This paper introduces a novel dual hop hybrid system model that leverages the complementary strengths of free space optics (FSO) and millimeter-wave (mm W) communication, while incorporating a direct mm W link for added robustness. This paper analyzes the comprehensive performance of the proposed hybrid system using a single threshold selection combining. We consider a scenario where the channel state for the FSO link adheres to a Log-Normal distribution under conditions of weak turbulence. For the millimeter wave link, we assume it follows a Nakagami-m distribution, which encompasses a broad range of commonly encountered radio frequency (RF) fading distributions. The proposed system's performance is analyzed by deriving analytical expressions for average bit error rate (ABER) and outage probability (OP). The theoretical results of the proposed system, which are verified using Monte-Carlo simulations, unveil that under turbulence and adverse weather conditions, the performance of the proposed system over a standalone FSO system is improved significantly due to mm W backup link.

Double-link-failure-tolerant shared protection for fully coupled/half-split switchable point-to-multipoint coherent optical systems

Beyond 5G, the next-generation wireless communication standard requires an optical communication network with a more reliable point-to-multipoint system. A highly reliable, futuristic point-to-multipoint coherent optical system must update wavelength-division-multiplexing-based passive optical networks to a more disaster-resistant architecture that can switch between bypass and backup links. We propose, to our knowledge, a novel link-pair shared protection that can respond locally to double-link failures that result from a significant disaster. We validate the high availability of several network configurations, assuming a double-link disconnection, can be obtained irrespective of the transmission distance of the feeder fiber. We experimentally demonstrate link-pair shared protection with bidirectional wavelength pre-assignment for two of the four feeder fiber failures and validate a penalty of less than 2 dB for double-link failures. Furthermore, we prove that reconnection can be performed with a penalty of at most 2 dB in an experiment with shared protection with a single-link broadcast-and-select function that can manage partial double-link failures using a simple configuration.

Galileo E3 Total Time Delay Calibration in NTSC Time and Frequency Comparison

In order to improve the reliability of the time transfer link, Bureau International des Poids et Mesures (BIPM) has offcially taken the Galileo time comparison as the backup link for UTC calculation since 2020. Therefore, Galileo calibration of receiver is a necessary work for all timekeeping labs around the world to participate in the UTC link. Taking the GPS link calibrated by Physikalisch-Technische Bundesanstalt (PTB) and the National Time Service Center (NTSC) as reference, this paper sets PT09 as reference station to calibrate and verify the Galileo E3 (E1&E5a) total delay of NT02 and NT05 receivers from NTSC. The results show that the Galileo E3 total delay of NT02 and NT05 are 74.6 ns and 46.5 ns, respectively, the calibration uncertainty is 3.5 ns, and the calibration delay is relatively stable. After calibration, GPS P3 and Galileo E3 Common View results between NT02/NT05 and calibrated receivers of other timekeeping labs are basically consistent. Taking the GPS P3 links comparison results as reference between NTP3 and receivers from other labs, the average deviation is less than 1.5 ns, which is within the calibration uncertainty range.

Adaptive Coordinated Direct and Multi-RIS Transmissions for Ultrareliable Terahertz Systems

This paper investigates the outage probability of an adaptive coordinated direct and multi-RIS transmission for TeraHertz (THz) communication systems. Specifically, to tackle the connection loss due to pointing errors and severe attenuation in THz band, we propose two schemes that make use of a multi-RIS communication as a backup link to improve the reliability of the direct one. Invoking the two multi-RIS schemes, namely, the cooperative RIS (CR) and the opportunistic RIS (OR) schemes, exact and asymptotic outage expressions are obtained while accounting for small scale fading and non-zero boresight pointing errors. The accuracy of the analytical results is validated with Monte-Carlo simulations. The obtained results recognize a clear advantage of the proposed system compared with conventional standalone direct THz link. Thus, with carefully planned networks, enabling direct and multi-RIS cooperation for THz wireless systems can maintain sufficient coverage in sixth-generation (6G) networks.

Evaluating the Hybrid Multi-Protocol Label Switching (MPLS) on the Enhanced Interior Gateway Routing Protocol (EIGRP)

The development of technology and communication is expanding rapidly. In this case, the internet has become a vital necessity in globalization. Technological innovations are required to create a seamless, fast, and secure communication system. This research aims to evaluate the Enhanced Interior Gateway Routing Protocol (EIGRP) implementation by applying the Multiprotocol Label Switching (MPLS) technology. This study adhered to several stages in the Network Development Life Cycle (NDLC) method. The results of the two technology combinations, EIGRP and MPLS, demonstrated MPLS network simulation testing in several dynamic routing systems: EIGRP and OSPF, identified through the Quality of Service (QoS) value. It revealed that the best performance was EIGRP with a throughput of 2152.5 bps, delay of 335.6 ms, and jitter of 411 ms. Furthermore, MPLS and EIGRP network redundancy was better applied in the mesh topology with a multi or backup link than in the linear topology with a single link.

Performance of hybrid RF/FSO wireless communication system under low visibility

Abstract In the last ten years, there has been a significant increase in the importance of free-space optics (FSO). FSO can be a solution for the last mile, but its reliability and availability issues need to be looked into in depth before they can be fixed. Because FSO links depend so much on the weather, a number of weather-related issues reduce their availability. A hybrid network with an FSO link and a backup link in the GHz frequency band offers good availability and data speeds that are similar to those of a pure FSO network. Fog’s effects on hybrid RF/FSO systems are investigated. As a backup link, the GHz frequencies with the best complementing behavior should be used. The findings demonstrated that high temperatures had no adverse effects on the RF at 25 GHz in terms of impaired visibility. Despite the cold weather, the FSO link required excellent visibility.

Analysis of hybrid RF/FSO wireless communications links under foggy weather conditions

Abstract Terrestrial free-space optical (FSO) links are based on the fundamental idea of a light beam transporting information, enabling extremely high data rates. Fog still presents a significant obstacle to enhancing the availability and dependability of terrestrial FSO lines because the fog particles scatter the light as it travels and only significantly attenuate the signal. Using a hybrid network with an FSO link and a backup link will solve the problem. GHz offers outstanding performance in this frequency band. In this research, the attenuation caused by fog is predicted using an empirical model based on measurements of visibility and their impacts on FSO/RF links. Multiple functioning FSO and RF links operating at 1 GHz, 10 GHz, and 25 GHz, as well as visibility, were simultaneously monitored for changes in signal intensity. The bit error rate (BER) for the optical modulation formats NRZ-OOK, L-PPM, and RZ-OOK is investigated under various fog scenarios. According to the results of the simulation, RF link performance at 25 GHz is better suited for hybrid system fog weather circumstances. On the other hand, we discuss the appropriateness of fog models within these various modulation formats.

Optimizing Caching in a C-RAN With a Hybrid Millimeter-Wave/Microwave Fronthaul Link via Dynamic Programming

Placing selected content at the edge of the network close to the users, known as caching, can lower network latency and congestion in the fronthaul link. Unlike most works that assume a fixed or limited variation in file popularities, to better address user requests, we consider a time-varying popularity resulting in hidden-mode Markov decision processes. In fact, each mode captures environmental changes, and we optimize the fetching and dropping (of files) decisions to minimize a long-term network cost in a cloud radio access network. Importantly, the primary fronthaul link is a millimeter (mmWave) link with large capacity supported by a microwave backup link in case of blockage. Since caching decisions are coupled over time and can affect the future, we introduce a dynamic programming approach to solve the caching problem. We approximate the future cost of each cache state in each mode. To reduce the complexity of calculating the future cost, we introduce two approximation approaches and illustrate the accuracy of the approximations under different environmental conditions. Finally, our simulation results confirm the effectiveness of our proposed algorithm in finding effective caching and fetching decisions to lower the total network cost while dealing with time-varying popularities.

Validation of a hybrid RF/FSO communication system under foggy weather conditions

Abstract Future high-capacity data links are best suited for free space optical (FSO) communications since they have a larger bandwidth and secure transmission compared to RF links. FSO has several uses including indoor and outdoor settings. The impacts of weather are extensive, with fog being the main mitigating factor reducing link availability. The solution to the problem is to employ a hybrid network with RF/FSO and backup link. Different liquid water densities were used to analyze the performance of the hybrid RF/FSO system in foggy weather. In terms of BER, Q factor, and data rate, a comparison between RF and FSO lines is made. The findings demonstrated that in lower-medium of liquids with water density, the influence of fog weather on RF link is minimal. Under the same situations, an FSO link is useful as a backup link in higher liquid water density concentrations.

Implementation of Link Failover on Metronet Network PT. Telkom Indonesia (Persero) Based on Ipv4 and OSPF

Metro ethernet is a data communication network owned by PT. Telkom Indonesia (Persero) through distribution channels, one of which is Open Shortest Path First (OSPF). As technology develops, IPv4 is used as the core addressing protocol for every communicating network device and has the responsibility of finding the route taken by packets to reach their destination. The problem that occurs in the data communication network is the absence of stable connectivity when there are links between cities experiencing downtime, resulting in several link congestion on the data packet path. To overcome the above problems, this study analyzed IPv4-based metro ethernet networks through the OSPF routing protocol using Graphical Network Simulator-3 (GNS-3). This study implements a failover system as a backup link in the event of a Jakarta-Bogor downlink. Based on the simulation and test results, the failover link shows a success status and functions to minimize network connection breakdowns. This is because the use of OSPF routing isOSPF routing canen the main link is down, so the path will be diverted via the backup link. QoS measurements using a single link obtained an average throughput of 195 Kbps, while dual links obtained an average throughput of 258 Kbps. This is because the distance from the source to the destination router is passed by more single links than dual links. Overall, the measurement shows that having a backup link can increase the stability of the data communication network connection when it is down and tested according to ETSI standards

Performance analysis of OSPF and EIGRP convergence through IPsec tunnel using Multi-homing BGP connection

Increasingly, networks stability and convergence time are critical parameters in overall network performance. Therefore, it is essential to compare the routing protocols performance to understand the convergence issues and future needs. Corporate networks require a better performing network with a stable connection with the remote branches. There is a need for a backup link availability for the remote branches’ connection in case of a link failure. The Internet Service Providers (ISPs) cannot guarantee a network connection without errors or link failures. To avoid network downtime, the enterprise uses a backup link, preferably with a different ISP with a failover link capability for their network. Other research conducted under the title of Routing Protocol Performance Analysis for RIP, EIGRP, OSPF compares the performance of the protocols using the parameters like delay, jitter, throughput. However, not many consider the link failure and its impact on the enterprise network. This research was conducted to analyze the problem faced by the corporate networks in case of link failure and what routing protocols they should use to minimize the network delay, jitter, convergence time and failover convergence time for better network performance when both internal and external routing protocols are used over the secure network connection using IPsec tunnel by simulating the network using GNS3. BGP multi-homing environment is implemented with multiple internet connections with different ISPs using different AS numbers. IPsec tunnel is established over the public network, and EIGRP and OSPF routing protocol performance is compared running over the IPsec tunnel. The testing parameters used in this study are delay, packet loss, initial convergence time, failover convergence time. For added security, the protocols convergence timings are recorded using MD5 authentication. The result of this study indicates that EIGRP has a better initial convergence time, and it has a better failover convergence time compared to OSPF.

Design of Dual Homing Backup Link on Routing Border Gateway Protocol With Method Hot-Swap Routing Protocol

The importance of the role of the network at this time makes companies and organizations look for ways to keep data flows running without downtime. Application of link backup is one way to overcome this. The need for the use of backup links at this time is expected to ensure the smooth running of the company is running its business. In this study, a design that will use BGP routing as well as using the methods HSRP and VLAN (Virtual Local Area Network) on the switch as supporters. The results obtained from the tests that have been carried out have resulted in the application of a backup link using BGP routing with the method HSRP can provide network availability of almost 0 percent in overcoming interference.

Hybrid FSO/RF System Using Intelligent Power Control and Link Switching

Free Space Optical (FSO) communication is promising to provide a wireless connection of tens to hundreds of gigabit capacity. Despite of many advantages, FSO link is sensitive to weather conditions and atmospheric turbulence. To offset these limitations, using Radio Frequency (RF) link as a backup link is a wise choice and thus hybrid FSO/RF system gains wider attention. Research on link switching is of great importance as a key technology in hybrid FSO/RF system. It is well known that link switching is closely related to the Received Signal Strength Indication (RSSI). In this letter, by combining power control and link switching using Recurrent Neural Networks (RNN) to predict RSSI, we propose an intelligent power control and link switching scheme to enhance transmission effectiveness in hybrid FSO/RF system. We set up a testbed of hybrid FSO/RF system and experimentally validate the proposed scheme. Experimental results demonstrate that the proposed scheme can forecast the trend of RSSI accurately and the power control strategy can effectively improve transmission quality of FSO link by reducing the frequency of switching.

Research on high reliability in redundant link aggregation mode

Now, with the rapid development of the Internet, the requirement of bandwidth and reliability of backbone link is higher. In traditional Ethernet networks, it needs to pay a high price to increase the network bandwidth, if you use high-speed equipment, so not only the cost is high, but also the network is not flexible enough. In order to ensure the stability and reliability of Ethernet network, this paper proposes a redundant link aggregation technique, without replacing the equipment, and bundling multiple physical interfaces into a logical interface to increase the bandwidth of the link, dynamic and effective backup links can also be used to improve the reliability of links between devices. Redundant link aggregation can not only improve network bandwidth resources, but also solve the problem of network congestion.

Performance analysis of hybrid FSO/RF communication over generalized fading models

Hybrid free space optics/radio frequency (FSO/RF) communication has been considered as a promising solution for reliable wireless backhaul connectivity for 5G and beyond wireless communication systems. In this paper, comprehensive performance analysis of the hybrid FSO/RF system has been carried out considering single-threshold-based switching strategy for both terrestrial and satellite communication scenarios. We assume that the channel state of the FSO link follows generalized Malaga distribution with pointing errors and atmospheric attenuation. Further, the RF channel fading has been modeled using generalized α-η-κ-μ distribution, which includes most of the well-known RF fading distributions as special cases. We derive the unified closed-form expressions for outage probability, average symbol error rate (SER) and ergodic capacity of the hybrid FSO/RF system considering two types of detection techniques, i.e. heterodyne detection (HD) and intensity modulation/direct detection (IM/DD). Additionally, we determine the range of optimum switching threshold and optimum beam waist values using a numerical optimization method for achieving optimal performance. We also derive simpler asymptotic expressions in terms of elementary functions to obtain diversity gain and coding gain of the hybrid FSO/RF system. The theoretical results of the hybrid FSO/RF system, which are verified using Monte-Carlo simulations, unveil that under strong turbulence, high pointing errors, and adverse weather conditions, the performance of the hybrid FSO/RF system over FSO system is improved significantly due to RF backup link.

Application of the Stacking and LACP Technology in Communications Networks

A key factor that has been winning market competitive advantage by carrier markets is how to solve the selection of equipments with lowest cost which provides a reasonable solution on network security and topology. By introducing the stacking technology, this paper gives a detailed explanation on how to use the lowest cost to solve the equipment selection problem and the devices’ hot backup. As the same time, it is shown that the network link aggregation hot backup is resolved by using the Link Aggregation Control Protocol (LACP). Once there is a failure in both a link and an equipment, the system would detect the failure and automatically switch to the backup link and equipment to ensure the network security.

Adaptive-Combining-Based Hybrid FSO/RF Satellite Communication With and Without HAPS

In recent years, a growing interest has been witnessed in the usage of free space optics (FSO) link for satellite communication (SATCOM) scenarios, as it offers much higher data rates up to gigabits per second (Gbps) compared to existing radio frequency (RF) link. However, FSO links are sensitive to beam scintillation and pointing errors. In this paper, we consider a hybrid FSO/RF communication between ground station (GS) and satellite, where the RF link will act as a backup link to improve the reliability of FSO communication. In addition, we also consider high-altitude platform station (HAPS), which will act as a relay station, between GS and satellite to improve the end-to-end system performance. This has led to the development of space-air-ground integrated hybrid FSO/RF SATCOM networks. We analyse the performance of the proposed hybrid network considering an adaptive-combining-based switching scheme for both uplink and downlink scenarios with and without using HAPS as a relay station. In case of adaptive-combining-based switching scheme, the data is continuously transmitted over the FSO link, while maximal-ratio-combining (MRC) of RF and FSO links is performed when the quality of FSO link deteriorates. The performance analysis of adaptive-combining-based switching scheme in terms of outage and average symbol error rate (SER) is carried out and the same is compared with the single-link FSO SATCOM and single-threshold-based switching scheme proposed in the literature for hybrid FSO/RF SATCOM. In addition, the performance gain obtained by the proposed adaptive combining scheme over single-link FSO system for different channel conditions is also reported. Further, the asymptotic analysis is also carried out to obtain the diversity gain of the proposed system.

PERANCANGAN DAN IMPLEMENTASI JARINGAN FAILOVER MENGGUNAKAN PROTOKOL SPANNING TREE PADA PT. PLN UP3B KALIMANTAN TIMUR

The availability of electricity is very reliable as a main of supporting component in development progress and economic growth. PT. PLN as an authorized implementation unit for distributing and regulating electricity supply from the power plant to the transmission line requires a reliable network communication system for its operations, as a facility to connect all of its main substations. The disruption of the information network is an important thing that must be avoided in the company so that it does not interfere the distribution of information. The reliable information distribution methods from the main office to the branch offices should be failover that uses backup links in all branch offices as a solution to keep the information network system reliable by using the protocol of spanning tree and VLAN configuration on the routers and manageable switches. Having used the failover method on a network system, it is expected to help the company to always keep reliable in distributing information to all substations so that information loss can be drastically reduced.

Improving the performance of a DF relay-aided FSO system with an additional source–relay mmWave RF backup

Atmospheric turbulence and pointing errors are major hindrances behind the proliferation of free-space-optics (FSO) technology in next-generation fronthaul networks. This paper investigates the effect of a decode-and-forward relay in overcoming these impairments and how an additional source-to-relay millimeter-wave (mmWave) radio-frequency (RF) backup link improves the performance of the relay-aided FSO system further; i.e., we study the performance of a hybrid FSO/(FSO-FSO)/(RF-FSO) system. Generalized Málaga distribution is adopted to model atmospheric turbulence in FSO links, whereas the fading statistics of the mmWave RF link is modeled by Nakagami-mdistribution. The performance of the hybrid system is studied on the basis of analytical expressions derived for metrics such as outage probability, bit error rate, and ergodic capacity, and the results show the supremacy of the proposed hybrid FSO system. The improvement is, however, dependent on factors such as turbulence location and signal-to-noise ratio per bit, and not all performance metrics exhibit equal improvement.

Reliability Improvement in Clustering-Based Vehicular Ad-Hoc Network

Clustering based vehicular Ad-hoc Network (CAN) is being considered as the most viable solution to integrate milimeter wave (mmWave) and sub-6 GHz interface in vehicular communication. In CAN, the data path contains two cascaded links, mostly mmWave link for vehicular to vehicular (V2V) connectivity and sub-6 GHz link for vehicular to infrastructure (V2I) connectivity. In this letter, we have introduced diverted path approach (DPA) to enhance V2V communication reliability. In addition, the notion of back-up link has been introduced to enhance V2I communication reliability. Then, through simulation results, it is shown that DPA can significantly improve V2V communication reliability. Further, it is shown that the incorporation of both the proposed schemes with the existing CAN, significantly enhances the overall vehicular (V2V+V2I) communication reliability.