Fiber-wireless Access Networks Research Articles

26.8-m THz wireless transmission of probabilistic shaping 16-QAM-OFDM signals

Recently, remarkable efforts have been made in developing wireless communication systems at ultrahigh data rates, with radio frequency (RF) carriers in the millimeter wave (30–300 GHz) and/or in the terahertz (THz, >300 GHz) bands. Converged technologies combining both the electronics and the photonics show great potential to provide feasible solutions with superior performance compared to conventional RF technologies. However, technical challenges remain to be overcome in order to support high data rates with considerably feasible wireless distances for practical applications, particularly in the THz region. In this work, we present an experimental demonstration of a single-channel THz radio-over-fiber (RoF) system operating at 350 GHz, achieving beyond 100 Gbit/s data rate over a 10-km fiber plus a >20-m wireless link, without using any THz amplifiers. This achievement is enabled by using an orthogonal frequency division multiplexing signal with a probabilistic-shaped 16-ary quadrature amplitude modulation format, a pair of highly directive Cassegrain antennas, and advanced digital signal processing techniques. This work pushes the THz RoF technology one step closer to ultrahigh-speed indoor wireless applications and serves as an essential segment of the converged fiber-wireless access networks in the beyond 5G era.

Resource Allocation and QoS Guarantees for Real World IP Traffic in Integrated XG-PON and IEEE802.11e EDCA Networks

Globally, there is a significant rise in the number of connected devices. Every device has an access to wide variety of telecom services among which voice, video and best effort (BE) contribute significantly. There is a noticeable growing trend towards upstream BE traffic besides real time e-services that demand high quality of service (QoS). Converged next-generation fiber-wireless (FiWi) access networks composed of next-generation passive optical network (XG-PON) and 802.11n based wireless local area network (WLAN) has emerged as a suitable choice to provide high quality and affordable e-services to plenty of subscribers as they possess both high bandwidth and flexibility. In this paper, we study the performance of the integrated network architecture which combines XG-PON and enhanced distributed channel access (EDCA) under real time bursty traffic derived from the current global IP traffic distribution. The joint tuning of various crucial parameters of both XG-PON and EDCA with incorporation of an efficient deficit dynamic bandwidth algorithm (DBA) at optical line terminal (OLT) is done by exhaustive simulations in network simulator-3 (NS-3). Through intensive simulations and tuning, we are able to achieve a end-to-end delay performance of <; 150 ms for voice, <; 500 ms for video and a few seconds for BE upto full capacity. Also, a packet loss ratio (PLR) of <; 3% and <; 6% is achieved for voice and BE respectively upto full load. For voice PLR is <; 1% upto 60% total offered load. Further, it is observed that the fine tuning of key parameters has also resulted in increased bandwidth for dominant BE services. Therefore, this optimized network architecture is 20% more fair to BE services as compared to the conventional integrated FiWi architectures.

An offloading scheme leveraging on neighboring node resources for edge computing over fiber-wireless (FiWi) access networks

The computation resources at a single node in Edge Computing (EC) are commonly limited, which cannot execute large scale computation tasks. To face the challenge, an Offloading scheme leveraging on NEighboring node Resources (ONER) for EC over Fiber-Wireless (FiWi) access networks is proposed in this paper. In the ONER scheme, the FiWi network connects edge computing nodes with fiber and converges wireless and fiber connections seamlessly, so that it can support the offloading transmission with low delay and wide bandwidth. Based on the ONER scheme supported by FiWi networks, computation tasks can be offloaded to edge computing nodes in a wider range of area without increasing wireless hops (e.g., just one wireless hop), which achieves low delay. Additionally, an efficient Computation Resource Scheduling (CRS) algorithm based on the ONER scheme is also proposed to make offloading decision. The results show that more offloading requests can be satisfied and the average completion time of computation tasks decreases significantly with the ONER scheme and the CRS algorithm. Therefore, the ONER scheme and the CRS algorithm can schedule computation resources at neighboring edge computing nodes for offloading to meet the challenge of large scale computation tasks.

Load‐Balancing and QoS Based Dynamic Resource Allocation Method for Smart Gird Fiber‐Wireless Networks

Real-time network resource allocation based on virtualization technology is an important method to solve the solidification problem of Fiber-wireless (FiWi) access networks. To increase the resource utilization and meet the specific QoS requirements of smart gird communication services, a Load-balancing and QoS based dynamic resource allocation method (LbQ-DR) is proposed with three sub-mechanisms. A time-window based substrate network resource update mechanism is designed to describe the realtime resource consumption of substrate networks, which can balance the accuracy of resource status and the complexity of the allocation algorithm. A QoS-based Virtual network request (VNR) sorting mechanism is presented to precisely calculate the priority of VNRs and reasonably sort the incoming services. A load-balancing based resource allocation mechanism is designed to avoid unbalanced resource consumption. Especially, the channel interference is considered in the cost of embedding and a collision domain mechanism is introduced to decrease interference. Simulation results demonstrate that the proposed method can provide heterogeneous smart grid businesses with differentiated service, improve the utilization and economic benefits of the network and make the network more balanced.

Bending and twisting effects on multicore fiber differential group delay.

In this paper we provide the theoretical and experimental evaluation of fiber bending and twisting effects on the group delay performance of a homogeneous 7-core fiber. We have experimentally evaluated the differential group delay between the central and outer cores for different curvature radii and twisting conditions, demonstrating that fiber twisting counteracts the degradation introduced by the curvature itself. These findings are generally applicable to time-sensitive application areas such as radio-over-fiber distribution and microwave photonics signal processing in fiber-wireless access networks, as well as high-capacity long-haul digital communications where digital multiple-input multiple-output processing may be required.

Resource allocation for edge computing over fibre‐wireless access networks

Edge Computing (EC) has been proposed as a promising approach to fulfil the requirements of high bandwidth and ultra-latency of mobile applications. However, existing researches on resource allocation only consider the computing resource of mobile devices and EC servers, while ignored the constraint of the networking resources once spreading applications among multiple EC servers via wireless and wired networks. Fibre-Wireless access networks (FiWi) combine the huge bandwidth of optical fibre networks and flexible access of wireless networks to address the above issue and bridge the coexistence of multiple EC servers. They propose a Virtualisation-based Architecture converging EC over FiWi (VAECFW) to centralise control and allocate networking and computing resources for serving requested services. In addition, they study the problem of resource allocation of EC over FiWi and propose two algorithms Revenue-based Virtual Network Embedding (R-VNE) and Balanced Central Processing Unit Resource Allocation with Virtual Network Embedding (BCRA-VNE). Simulation experiments show that the services acceptance ratio is increased about 35% under their proposed architecture, and the average service requests bandwidth utilisation of R-VNE is increasing from 50 to 66%, and the BCRA-VNE is from 37 to 48%. The two algorithms not only achieve higher revenue but also get better profit rate.

Optical network unit placement in Fiber-Wireless (FiWi) access network by Whale Optimization Algorithm

Abstract Fiber-Wireless (FiWi) Access Network is proposed as a dominant and advantageous next generation hybrid access network. FiWi integrates wireless access technology with the optical access networks to provide potential benefits of both the technologies. Optical Network Unit (ONU) placement problem in FiWi network plays a vital role as it permits efficient utilization of network resources and enhances the performance in terms of cost efficiency and throughput. In this paper, we consider ONUs placement problem. The present work outlines the deployment of FiWi network and proposes a novel nature-inspired, population based metaheuristic paradigm called as Whale Optimization Algorithm (WOA) for optimal placement of multiple ONUs based on different distribution of wireless routers and ONUs. The outcomes are compared with the existing strategies of Greedy and Moth Flame Optimization (MFO) algorithms. To the best of our knowledge, WOA has never been used in this domain previously. The results in this manuscript prove that the proposed WOA outperforms the Greedy (deterministic) and MFO algorithms, and returns the lowest value of cost function; it results in faster convergence rate and lower time complexity than these algorithms. Moreover, the exploration and exploitation capability of WOA is significantly better than MFO algorithm. The results show dependence of the objective function value on the distribution of wireless users and ONUs; it is reported that random placement of users and deterministic placement of ONUs return the lowest value of objective function.

Cost-optimal cloudlet placement frameworks over fiber-wireless access networks for low-latency applications

In the recent past, we have observed a trend that edge devices are increasingly accessing computational resources through the Internet, preferably via cloud computing technologies. However, cloud servers fail to meet the desired latency requirements of low-latency applications like augmented reality, cognitive assistance, and Tactile Internet applications, primarily due to the high-transmission latency from edge devices. This issue is resolved by augmenting cloud networks with a cloudlet enabled edge computing solution that creates a three-tier network topology. In this paper, we primarily focus on static cloudlet network planning problem and propose a hybrid cost-optimization framework for optimal cloudlet placement over existing passive optical access networks, subject to capacity and latency constraints. We formulate a mixed integer non-linear program to identify ideal cloudlet placement locations over urban, suburban and rural deployment scenarios. We show that the target latency requirement and the type of deployment scenario plays a major role in determining the amount of computational resources to be installed in the cloudlets. We also show that the percentage of the incremental energy budget of the access networks due to active cloudlet installation is under 18%. Overall, we show that the newly proposed hybrid cloudlet placement framework achieves the most cost optimal solution as compared to the field cloudlet placement framework.

Towards Immersive Tactile Internet Experiences: Low-Latency FiWi Enhanced Mobile Networks With Edge Intelligence [Invited

Historically, research efforts in optical networks have focused on the goal of continuously increasing capacity rather than on lowering end-to-end latency. This slowly started to change in the access environment with post-Next-Generation Passive Optical Network 2 research. The emphasis on latency grew in importance with the introduction of 5G ultra-reliable and low-latency communication requirements. In this paper, we focus on the emerging Tactile Internet as one of the most interesting 5G low-latency applications enabling novel immersive experiences. After describing the Tactile Internet's human-in-the-loop-centric design principles and haptic communications models, we elaborate on the development of decentralized cooperative dynamic bandwidth allocation algorithms for end-to-end resource coordination in fiber-wireless (FiWi) access networks. We then use machine learning in the context of FiWi enhanced heterogeneous networks to decouple haptic feedback from the impact of extensive propagation delays. This enables humans to perceive remote task environments in time at a 1-ms granularity.

Adaptive Hybrid Path Search MFO Algorithm for Optical Network Unit Placement in Fiber-Wireless Access Network

Fiber-Wireless (Fi-Wi) access network is an emerging solution for high bandwidth and wide coverage network which satisfy the demands of many applications. Research work is going on in this field on several issues and some are Optical Network Unit (ONU) placement, routing, survivability; energy consumption etc. ONU placement problem plays important role as it makes network economic and allows optimal use of resources. In this research work, Adaptive Hybrid Path Search (AHPS) - Moth-Flame Optimization algorithm has been proposed to position multiple ONUs, optimally in the network. The comparative study of different variants of MFO algorithm implementing logarithmic, Archimedes’, hyperbolic and AHPS are presented for ONU placement problem. The outcomes of the simulation are based on different configuration of users and ONUs. It has been reported that the proposed algorithm provides most optimal result among all the MFO variants.

Virtual Network Embedding in Fiber-Wireless Access Networks for Resource-Efficient IoT Service Provisioning

The rise of Industry 4.0 is pushing more machine devices into the connection of the communication network. Internet of Things (IoT) emerges as an enabling technique to support automatic information transmission and the universal interconnection among massive machine devices. Unlike the human type communication (HTC) in the conventional Internet, IoT features machine type communication (HTC) with small data granularity and massive connections, which impose new challenges on the network resource allocation earlier designed for HTC communication. One of the challenging issues is how we can manage the network resource for the IoT service provisioning. As a promising network architecture for the “last-mile” access in 5G communication, Fiber-Wireless (FiWi) access network compromises the high bandwidth capacity of the optical access network and the flexibility of wireless access network. Especially, network virtualization as an emerging technique provides FiWi with the feasibility for the coordinated bandwidth allocation of wireless access network and optical access network. The evolution of FiWi access network should be not only oriented to the technological breakthrough in regular traffic, but also be supportive of the emerging IoT traffic. In this paper, we focus on the resource allocation problem in FiWi access network supporting IoT service. We first analyze the dynamics of regular traffic and propose the traffic prediction method based on Q-Learning. Then, we propose a virtual network embedding algorithm to map exactly the virtual networks of IoT traffic to the idle resource of the virtual networks of regular traffic without degrading the performance of regular traffic. Thus, the proposed algorithm can improve the resource utilization more effectively. The simulation results demonstrate that the proposed algorithm can achieve a higher acceptance ratio and lower migration ratio of IoT traffic.

Resource-Efficiently Survivable IoT Services Provisioning via Virtual Network Embedding in Fiber-Wireless Access Network

Fiber-Wireless (FiWi) access network is a promising network architecture to provide the constantly available connections for the collaboration of objects in the Internet of Things (IoT). The network virtualization is dominating the evolution of FiWi, i.e., virtualized FiWi access network, which shields the difference between wireless and optical subnetworks and enables the customized transmission of different types of the IoT services in a common substrate network. However, the differences between optical and wireless subnetworks pose severe obstacle on their interoperability of resource allocation. In this paper, we focus on the survivable virtual network embedding (SVNE) in the FiWi access network for the purpose of the robust IoT service provisioning even in the scenario of network component failure. Each type of the IoT service is carried on one virtual network (VN), which is characterized by not only computing the resource and bandwidth resource demands but also the connection availability requirement. A connection availability model is proposed as an indicator of the network survivability and the IoT service robustness. We aim to allocate the resource for each VN with the resource cost minimized. The optimization problem of resource allocation is formulated in the integer linear programming (ILP) model that is solved for the optimal solution in a small-scale network. A heuristic algorithm is further put forward to facilitate the use of the proposed SVNE mechanism in a large-scale network. The simulation results verify that the proposed SVNE mechanism gains significant advantages in lower resource redundancy and higher acceptance ratio of VNs.

QoE-Aware Video Multicast Mechanism in Fiber-Wireless Access Networks

In this paper, a video multicast mechanism is studied in fiber-wireless (FiWi) access networks with object to guarantee the quality of experience (QoE) for different users. Firstly, according to the characteristics of scalable video coding, a new QoE evaluation model is built in terms of the video interruption probability, video bitrate and smoothness. Then the optimal transmission path is studied based on the coverage and transmission capabilities of ONU-BS nodes. Specifically, a bipartite graph is constructed based on which the multicast tree is obtained by solving the minimum dominating set problem. Thereafter, a video bitrate adjustment algorithm is proposed to reduce the video interruption probability based on the buffer state on the user side and meet the bitrate requirements for different users during multicast transmissions. Simulation results verify that the proposed scheme performs well in QoE guarantees for different users simultaneously.

Low-Latency Oriented Network Planning for MEC-Enabled WDM-PON Based Fiber-Wireless Access Networks

WDM-PON-based mobile edge computing (MEC)-enabled fiber wireless access networks (MFWAN) have been identified as a promising technology for next-generation broadband access. Low-latency oriented network planning of the WDM-PON-based MFWAN would be required for low-latency access to newly emerging latency-sensitive applications in the fifth-generation (5G) era. However, this would require a low-latency oriented network design in the network planning phase and has thus become a crucial challenge. In this paper, we investigate low-latency oriented network planning of the WDM-PON-based MFWAN under physical and management constraints. To this end, we develop a mathematical model to minimize total transmission latency for all latency-sensitive services. Our model is composed of the propagation latency on the paths and the processing latency on the network equipment and is subject to constraints of maximal transmission distance, maximal PON power budget, bandwidth requests, and the fronthaul latency limit under some functional split options. Given the model’s complexity, we also propose a heuristic algorithm called latency-minimized integrated multi-associated positioning and routing algorithm (LMI-MAPRA). The simulation results show that the proposed algorithm outperforms the benchmark algorithm with more total transmission latency reductions in both sparse and dense networks. We also analyze the impact of key parameters on comparisons of different approaches in terms of low-latency optimal performances.

Improving Animal-Human Cohabitation with Machine Learning in Fiber-Wireless Networks

In this paper, we investigate an animal-human cohabitation problem with the help of machine learning and fiber-wireless (FiWi) access networks integrating cloud and edge (fog) computing. We propose an early warning system which detects wild animals near the road/rail with the help of wireless sensor networks and alerts passing vehicles of possible animal crossing. Additionally, we show that animals’ detection at the earliest and the related processing, if possible, at sensors would reduce the energy consumption of edge devices and the end-to-end delay in notifying vehicles, as compared to the scenarios where raw sensed data needs to be transferred up the base stations or the cloud. At the same time, machine learning helps in classification of captured images at edge devices, and in predicting different time-varying traffic profiles— distinguished by latency and bandwidth requirements—at base stations, including animal appearance events at sensors, and allocating bandwidth in FiWi access networks accordingly. We compare three scenarios of processing data at sensor nodes, base stations and a hybrid case of processing sensed data at either sensors or at base stations, and showed that dynamic allocation of bandwidth in FiWi access networks and processing data at its origin lead to lowering the congestion of network traffic at base stations and reducing the average end-to-end delay.

QoS satisfaction aware and network reconfiguration enabled resource allocation for virtual network embedding in Fiber-Wireless access network

Network virtualization emerges as a revolutionary transformation for network operation pattern, which potentially benefits Fiber-Wireless (FiWi) access network by overcoming the bottleneck of joint wireless and optical resource allocation. On one hand, the heterogeneity between optical and wireless subnetworks that has posed severe challenges on the global optimization of FiWi can be tackled using network virtualization by shielding their physical differences. On the other hand, the flexible nature of resource scheduling in FiWi provides an opportunity for Infrastructure Provider (InP) to obtain high profit in the process of Virtual Network Embedding (VNE). In this paper, we highlight the VNE problem in FiWi access network. The wireless channel allocation algorithm and dynamic bandwidth allocation algorithm in FiWi are put forward, based on which the Integer Liner Programming (ILP) model of VNE problem in FiWi access network is formulated mathematically where a practical model of Virtual Network (VN) is focused by endowing each VN with a unique QoS satisfaction requirement. Moreover, aiming at maximizing InP profit, a QoS satisfaction aware VNE algorithm is designed and then improved by network reconfiguration mechanisms that enable the reconfiguration of not only virtual networks but also substrate network. Simulation results demonstrate that our proposed algorithms are effective in achieving higher VN acceptance ratio as well as InP profit. Furthermore, the mobility in network virtualization is analyzed in company with suggested solutions for virtualized FiWi access network. Comprehensive designs will be addressed in future work.

A QoS Control Scheme based on Software Defined Fiber-Wireless Access Network for Survivability

Abstract Fiber-Wireless (FiWi) access network is a promising broadband access network. Taking its heterogeneous structure into consideration, the paper introduces the Software Defined Networks (SDN) into FiWi access network. Survivability is an important issue in FiWi access network. Once there is a single fiber fails, many high-rate traffic flows may loss. A failure detection scheme is proposed for one distribution fiber fault in the new architecture. For the affected data flows recovery, we focus on the bandwidth allocation scheme for different priorities queues to meet the QoS. The simulation results show that the proposed scheme can maintain the QoS performance in terms of delay, loss rate and network throughput. The survivability is improved efficiently.

Performance Evaluation of Integrated Multi-Access Edge Computing and Fiber-Wireless Access Networks

With the widespread use of smart mobile devices, the exponential growth of mobile Internet traffic and newly emerging services, such as Internet of Things, virtual reality/augmented reality, and serious games, the network performance requirements for delay and bandwidth are increasing. The inherent long-distance propagation and possible network congestion of mobile cloud computing may lead to excessive latency, which cannot satisfy the new delay-sensitive mobile applications. The proximity of edge computing provides the possibility of low-latency access and raises increasing interest from non-mobile operators; therefore, edge computing faces a variety of access network technologies, including wired (fixed) and wireless (mobile) access. In this paper, we propose an integrated heterogeneous networking scheme for multi-access edge computing and fiber-wireless access networks that uses network virtualization to achieve the dynamic orchestration of the network, storage, and computing resources to meet diverse application demands. The global view and centralized control of the entire network and the unified scheduling of the resources in the scheme anticipate the convergence of various types of access networks and the edge cloud. The multipath transmission of the service flows is further combined as an instance of integrated edge cloud networking. An experimental testbed is established in the laboratory, and the performance of the multi-access edge computing and networking is evaluated to verify the feasibility and effectiveness of the scheme. The results demonstrate that the scheme can effectively improve the network performance.

Fiber-Wireless Network Virtual Resource Embedding Method Based on Load Balancing and Priority

Network virtualization is becoming one of the most promising ways to solve resource solidification problem of fiber-wireless access networks. To fully utilize substrate resources, a virtual resource embedding method including three sub-mechanisms is presented in this paper. The first one is the priority-based virtual network request (VNR) selecting mechanism, which sorts VNRs and preferentially selects higher priority VNRs for embedding. Then a dynamic embedding mechanism based on load balancing is presented to increase the acceptance rate of VNRs. Second, when embedding is saturated, an embedding update mechanism is proposed to deal with the arrival of new VNRs. It promotes the acceptance rate of high-priority VNRs and the revenue of the infrastructure provider (InP). Finally, a backup resource sharing mechanism is designed to improve reliability, which enables backup resources to be shared and responds to the failures with minimal resources. The simulation results show that the proposed embedding method can balance the resource consumption better than the Greedy Node Embedding and Shortest-path Link Embedding Algorithm, as well as the Greedy Node Embedding and Maximum Residual Bandwidth Link Embedding Algorithm. Besides, by applying our proposed algorithm, higher VNR acceptance rate, InP revenue, and resource utilization are achieved.

Energy Efficient Rate Adaptation Algorithm for FiWi Access Network

Similar to any telecommunication network, energy efficiency is a desirable feature for fiber wireless (FiWi) access networks. These networks have optical back end and wireless front end. Both ends may contribute for energy efficiency. This work focusses on front end of FiWi access network, which is IEEE 802.11a wireless local area network (WLAN). For energy saving WLAN uses power saving mode (PSM), in which sleeping opportunity of a station is increased. During sleep time station remains switched off and results in reduction in energy required. However it is also observed that during active period of transmission considerable energy is consumed, which is the function of rate of data transmission. More data rate results in more active energy consumption but less transmission delay and vice versa. In order to reduce active and hence total energy consumption, we tried to transmit the data at lower data rate, while maintaining transmission delay in tolerable limit. This paper presents an Energy Efficient Rate Adaptation Algorithm (EERAA) for the front end of fiber wireless access networks. Simulation results compare the energy efficiency and transmission delay of EERAA and various existing fixed data rate schemes. Proposed scheme offers good trade-off between energy efficiency and transmission delay.