1,721,236 research outputs found
Handling priorities in optical buffers
No full textIn this letter we focus on the construction of optical buffers exploiting a static priority scheduling policy. Optical Switches and fiber Delay Lines (SDLs) are used to build the proposed multiple input/output ports Optical Priority Multiplexers and Priority Switching Nodes, used for contention-resolution in Optical Packet Switched networks
Enhancing RAN throughput by optimized CoMP controller placement in optical metro networks
Full text linkThe fifth generation (5G) of mobile communications will target unprecedented network performance and quality of service for end users. Among the various aspects which will be addressed in 5G, advanced cell coordination is deemed as crucial to maximize network throughput. In particular, in this paper, we refer to coordinated multipoint (CoMP) techniques that allow coordinating groups of cells (i.e., clusters) through a coordination controller, namely, a radio controller coordinator (RCC), to enhance the mobile network throughput by reducing interference. We focus on the placement of RCCs in the metro optical network and on its impact on the performance of cell coordination. We provide strategies to perform an optimized placement of such controllers in metro optical networks in order to maximize network throughput via cell coordination. Several CoMP techniques have been designed, whose throughput gain is affected by various factors, e.g., gain increases with the cluster size, while it decreases for larger latencies between the RCC and cells. As current metro networks are characterized by a hierarchical architecture with different levels of central offices, the choice of where to place controllers to maximize throughput gain can be optimized according to several factors, i.e., network geographical dimension, cells density, and available technology. In addition, selection of the most appropriate CoMP technique to be used in each cluster is not trivial, as the gain provided by the various techniques is differently affected by cluster size and latency between the RCC and cells. Our results show that under certain conditions optimized placement provides up to around 10% higher coordination gain with respect to fixed controller placement. Moreover, when adopting fronthaul technology, the coordination gain provided by an optimized controller placement may increase up to 20% in comparison to fixed placement
Reprovisioning for Latency-aware Dynamic Service Chaining in Metro Networks
Full text linkTo support newly emerging and highly dynamic 5G services, optical metro networks must be capable of provisioning services on the fly. Network function virtualization (NFV) is leveraged to fulfill these dynamic service demands by placing virtual network functions (VNFs) in NFV-capable network nodes and chaining them together (service chaining). In addition, new 5G service chains often have bandwidth requirements with subwavelength granularity, making traffic grooming essential for efficient network resource utilization. However, the latency requirement for these services will not allow one to always perform traffic grooming, as grooming operations add non-negligible latency to traffic, and this might lead to poor utilization and high service blocking. Thus, it is important to investigate dynamic solutions to increase network utilization and decrease service blocking. One approach to achieve this goal is to reprovision service chains (SCs) to use network resources as efficiently as possible. Reprovisioning consists of tearing down a service chain and reallocating its resources, typically with the intent to make room for new chains that would be otherwise rejected. While traditional reprovisioning entailed only routing reassignment, reprovisioning of SCs entails both rerouting traffic and/or relocating VNFs, hence originating new research problems. In this paper, we propose new heuristic algorithms to reprovision SCs whenever a service cannot be provisioned. We provide two different approaches to perform reprovisioning, i.e., bandwidth and location. While bandwidth reprovisioning consists of modifying only bandwidth assignment of SCs, location reprovisioning considers the possibility of changing the nodes each SC is mapped to. We also considered two different optical network architectures. Results obtained on realistic network topology and services show that location reprovisioning allows us to achieve up to 28% improvement in terms of the number of SCs we are able to provision in the network
A Techno-Economic Outlook to Optical-Interface Requirements for Midhauling of 5G Small Cells
No full textWe estimate the amount of optical interfaces to support fronthaul of Small Cells under aggressive 5G traffic forecasts, considering different functional splits (midhaul) and cell configurations. Cost of interfaces can be minimized by properly selecting functional split and radio configuration
Resilient BBU placement in 5G C-RAN over optical aggregation networks
Full text linkThe huge data demand envisioned for the 5G requires radical changes in the mobile network architecture and technology. Centralized radio access network (C-RAN) is introduced as a novel mobile network architecture, designed to effectively support the challenging requirements of the future 5G mobile networks. In C-RAN, BaseBand Units (BBUs) are physically separated from their corresponding radio remote heads (RRHs) and located in a central single physical location called BBU pool. The RRHs are connected to the BBU pool via the so-called fronthaul network. The “centralization” demonstrates remarkable benefits in terms of computational resources as well as power savings. Following this centralization, designing a survivable C-RAN becomes crucial as BBU pool and link failures might cause service outage for large number of users. In this paper, we propose three different approaches for the survivable BBU pool placement problem and traffic routing in C-RAN deployment over a 5G optical aggregation network. Namely, we define the following protection scenarios: (1) dedicated path protection, (2) dedicated BBU protection and (3) dedicated BBU and path protection. The three approaches are formalized as integer linear programming (ILP) problems. The ILPs objectives are to minimize the number of BBU pools, the number of used wavelengths and the baseband processing computational resources, in terms of giga operations per second. We provide numerical results to compare the aforementioned protection strategies considering different network topologies. The results show the effect of the latency and the transport–network capacity on the BBU placement. We show the trade-off between the centralization degree and the tight latency requirements. Moreover, we discuss important insights about considering the different objective functions for each protection approach
Dynamic grooming and spectrum allocation in optical metro ring networks with flexible grid
No full text
Survivable Virtual Network Mapping with Fiber Tree Establishment in Filterless Optical Networks
Full text linkFilterless Optical Networks (FONs) (i.e., optical networks where switching nodes are solely based on passive splitters and combiners) enjoy features that are highly appreciated by network operators, such as their low cost and their energy efficiency, posing them as an alternative solution to filtered Wavelength-Switched Optical Networks (WSON) based on active switching nodes. Due to FONs' specific design criteria (the network topology must be divided into link-disjoint filterless fiber trees to avoid laser loops), traditional network problems, such as survivable virtual network mapping, shall be revisited and tackled adopting novel solutions with respect to state-of-the-art filtered WSONs. In this paper, we investigate the problem of survivable virtual network mapping (SVNM) in FONs with the aim of evaluating the cost of survivability when adopting FON technology. We first model the problem as an Integer Linear Program to establish fiber trees and provide survivable mapping of virtual networks, while minimizing cost of additional network equipment and spectrum with respect to WSON. We then propose multiple heuristic and meta-heuristic approaches to tackle large problem instances. In our numerical evaluations, we consider three scenarios: FON, WSON, and FON with pre-established fiber trees. Results show that in FON, where SVNM is jointly optimized with fiber tree establishment, the investment in additional network equipment can be largely minimized, and even avoided in some cases. In contrast, in FON with pre-established trees, amount of additional network equipment needed to guarantee survivability is significant (up to 60% with respect to WSON)
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