As a basis for meaningful simulation and optimization efforts with regard to traffic engineering or energy consumption in telecommunication networks, suitable models are indispensable. This concerns not only realistic network topologies but also models for the geographical distribution and the temporal dynamics of traffic, as well as the assumptions on network components and technology. This paper derives such a model from the practice of a large national carrier. Applying the network and traffic model, we demonstrate its use by presenting various optimization cases related to energy-efficient telecommunication. Here, we focus on load adaptivity by employing sleep modes to the network hardware, where several constraints on the reconfigurability of the network over time are considered.

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Comprehensive topology and traffic model of a nationwide telecommunication network

Centralized radio access network (CRAN) is getting considerable attention in 5G radio access network infrastructure because of supporting deployments of small cells at a massive scale. In particular, CRAN enables network operators to enhance network coverage and capacity without interference with one cell solution and centralized radio processing. This centralization decreases both the network capital and operational expenditures. However, all these technological advancements bring considerable challenges in the transport infrastructure of 5G such as the evolution of the mobile front haul (FH) interface which imposes strict latency and bandwidth requirements on the transport layer. In this paper, the architectural changes that CRAN brings in 5G cellular networks and the intrinsic demands of the FH transport network is discussed. Different techniques that constrain FH requirements to make it cost-efficient are also surveyed. The overall motivation of this work is to achieve the optimal FH transport solution through a passive optical network.

Towards the Shifting of 5G Front Haul Traffic on Passive Optical Network

This paper presents a technoeconomical comparison between different emerging architectural approaches for 5G networks: C-RAN, centralized, where a BBU hotel collects several fronthauling streams, able to meet challenging requirements imposed by emerging 5G technology and DA-RAN, considered as an evolution of C-RAN, where resources are disaggregated in order to satisfy the requirements of different applications. Main results, obtained by an analytical evaluation of the cost of a metropolitan area network, show that disaggregating the hardware and software radio access network brings architectural and functional advantages, able to better meet the bandwidth and latency requirements imposed by the 5G verticals. Once analyzed the validness of the solution, we provide a cost analysis that firstly demonstrates that DA-RAN also brings economic advantages w.r.t. C-RAN. Furthermore, observing that the predominant share of the cost of the solution is given by the fiber of the local loop, we evaluate the introduction of TWDM PON in this area in order to share the fiber and reduce the cost of the network.

Scenarios and Economic Analysis of Fronthaul in 5G Optical Networks

Future IP-over-DWDM networks improve economics not only from eliminating grey interfaces substituted by coloured interfaces directly plugged into the packet routers. An even major leverage reducing cost of a traditionally over-dimensioned packet network can be attributed to architectural aspects including advanced multilayer resilience. This is enabled by newly available, flexible optical technology allowing a more dynamic mode of operation of IP-over-DWDM networks. The flexible optical layer can be used to offer service-differentiated resilience combining IP protection with optical restoration in IP-over-Optical networks. By this approach, higher interface utilization can be achieved reducing capital expenditures. In addition, this also improves the overall network availability and reduces operational expenditures. After a short overview on the key enabling technologies for flexible IP-over-DWDM interworking, the authors provide guidelines for the cost-efficient IP topology design of multilayer IP-over-DWDM core networks and show that for a German backbone reference network the combination of IP A/B-plane protection with optical restoration requires 24 – 27% fewer line interfaces compared to the multilayer optimized bypass network design.

Advanced multilayer resilience scheme with optical restoration for IP-over-DWDM core networks

The huge bandwidth capacities and low costs of passive optical networks (PONs) combined with their high data rates have made them strong candidates for wireless backhauls. Many designs have therefore been proposed to integrate PONs with edge and fog computing paradigms, which are essential for many emerging applications. However, the feasibility of this integration has not yet been fully examined. The dynamic bandwidth allocation (DBA) that would best support this integration and the effect it would have on network performance have not yet been studied. In this paper, we study the performance of edge computing in long-reach PONs (LR-PONs), where long propagation delays pose challenges to the bandwidth allocation performance. We believe this paper is one of the first to study the feasibility of edge computing in these optical access networks by investigating whether centralized or decentralized allocation would be better to support computational offloading to the edge. We compare centralized multithread polling and a modified decentralized scheme in terms of offloading delays, effects on upstream traffic delays, and throughput.

Toward parallel edge computing in long-reach PONs

In this paper, we study the influence of technology, traffic properties and price trends on optimized design of a reference IP-over-WDM network with rich underlying fiber topology. In each network node, we investigate the optimal degree of traffic switching in an optical (lambda) domain versus an electrical (packet) domain, also known as measure of node transparency. This measure is studied in connection to changes in traffic volume, demand affinity, optical circuit speeds and equipment cost. By applying variable design constraints, we assess the relative roles of the two distinct equipment groups, IP routers and optical cross-connects, with respect to resulting changes in cost-sensitive network architectures.

Optimal Degree of Optical Circuit Switching in IP-over-WDM Networks

In this paper, we evaluate the cost of wireless integration into an architecture based on long reach passive optical networks (LR-PON). We will demonstrate that including backhaul or fronthaul signals from antenna sites into existing LR-PON structures deployed for wired customers requires only marginal additional resources. We will also show that scenarios with remote radio heads and centralised base band units outperform distributed radio access networks mainly because of operational cost savings.

Centralised versus distributed radio access networks: Wireless integration into long reach passive optical networks

In this paper, we study the influence of technology, traffic properties and price trends on the optimized design of a reference IP-over-WDM network with rich underlying fiber topology. In each network node, we investigate the optimal degree of traffic switching in an optical (lambda) domain versus an electrical (packet) domain, also known as measure of node transparency. This measure is studied in connection to changes in traffic volume and distribution, optical circuit speeds and equipment cost. By applying variable design constraints, we assess the relative roles of the two distinct equipment groups, IP routers and optical cross-connects, with respect to resulting changes in cost-sensitive network architectures.

/pdf/optimal-degree-of-optical-circuit-switching-in-ip-over-wdm-4yu5aav19l.pdf

Optimal degree of optical circuit switching in IP-over-WDM networks

The tremendous increase in network traffic compared to relatively constant per customer revenues forces network operators to change both their aggregation and core networks. The key questions in this context are how cost-effective carrier-grade Ethernet transport abilities, high-capacity WDM transport and scalable, high-capacity IP routers influence the structure and the architecture of next generation networks: What is the right size of an IP backbone? How should aggregation be organized? How (de-)? centralized should services like video-on-demand be provided and how (de-)? centralized should functionalities such as accounting be implemented?

In this paper, we present a model-based optimization approach using mixed-integer programs at its core to answer these questions. We illustrate our general solution approach, describe the mathematical programming models used to solve the arising subproblems, and discuss how to express common network architecture variants within these models. Computational studies on nation-wide reference networks with more than 1800 locations, which have been developed within the German research project 100GET, show the effectiveness of our approach and its usefulness in evaluating alternative network architectures and network expansion strategies.

Integrated optimization of aggregation and core for varying NGN architectures

The tremendous increase in network traffic compared to relatively constant per customer revenues forces network operators to change both their aggregation and core networks. The key questions in this context are how cost-effective carrier-grade Ethernet transport abilities, high-capacity WDM transport and scalable, high-capacity IP routers influence the structure and the architecture of next generation networks: What is the right size of an IP backbone? How should aggregation be organized? How (de-)centralized should services like video-on-demand be provided and how (de-)centralized should functionalities such as accounting be organized? In this paper, we present a model-based optimization approach using mixed-integer programs at its core to answer these questions. Preliminary computational results on nation-wide reference networks with more than 900 network locations, which have been developed within the German research project 100GET, show the effectiveness of our approach.

Roland Wessaly

Papers

Optimal Degree of Optical Circuit Switching in IP-over-WDM Networks

Centralised versus distributed radio access networks: Wireless integration into long reach passive optical networks

Optimal degree of optical circuit switching in IP-over-WDM networks

Integrated optimization of aggregation and core for varying NGN architectures

Integrated optimization of aggregation and core for varying NGN architectures