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SPIRIT – D2.1: Report on application test cases, system requirements and design for 400G/Terabit transmission

SEVENTH FRAMEWORK PROGRAMME

THEME [ICT-‐2013.3.2] [Photonics]

SPIRIT

Software-‐defined energy-‐efficient Photonic transceivers IntRoducing Intelligence and dynamicity in Terabit

superchannels for flexible optical networks Grant Agreement no. 619603

D2.1 Report on application test cases, system requirements and

design for 400G/Terabit transmission

Lead beneficiary for this deliverable: OTE Contact Person: Ioanna Papafili, George Agapiou

Address: 2, Pelika & Spartis str., Maroussi, Greece Phone: +30 210 611 4706, 4663

Fax: +30 210 611 4650 e-‐mail: {iopapafi, gagapiou}@oteresearch.gr

Date due of deliverable: Actual submission date: Deliverable Authors: Participants: Workpackage: Security: Nature: Version: Total number of pages:

M4 31/03/2014 George Agapiou, Dimitris Apostolopoulos, Stefanos Dris, Marco Camera, Roberto Magri, Santo Nani, Ioanna Papafili, Stamatis Perdikouris, Maria Spiropoulou, Hercules Avramopoulos OTE, TEI, ICCS/NTUA WP2 PU R 1.0 45


Executive Summary This document is the deliverable “D2.1: Report on application test-‐cases, system requirements and design for 400G/Terabit transmission” of Work Package 2 “Application scenarios & system design, component specifications and software development” within the ICT SPIRIT Project 619603. The aim of Deliverable D2.1 is to derive the system-‐level specifications of the SPIRIT flexible transceiver based on application-‐driven network requirements following a top-‐to-‐bottom approach.

In the first part of this document, we have assessed the broadband market and considered studies reporting on Internet measurements and forecasting. Based on the findings of these studies, we defined the major application scenarios of interest to SPIRIT. Additionally, we have identified the application-‐driven network requirements mainly in terms of bitrate and latency, and described the reference network architecture of OTE, which will be considered in the evaluation and demonstration of the functionality of the SPIRIT components.

Furthermore, the requirements from a system perspective are presented, and appropriate test cases for performance evaluation of SPIRIT’s devices are identified. Operation in a fixed-‐grid WDM environment is envisaged, both in a mixed coherent/legacy traffic scenario, as well in an all-‐coherent channel setting. Moreover, the requirement for programmable and flexible-‐format operation will ensure compatibility with future elastic optical networks, with an emphasis on the emerging flex-‐grid standard.

Evaluation of SPIRIT’s devices will take place both in the laboratory, as well as in a field trial with deployed fiber and co-‐propagating traffic from commercial transponders. The test cases identified aim to evaluate component performance, in addition to validating SPIRIT’s targeted system concepts in realistic network scenarios.


Table of contents 1. Introduction ........................................................................................................................ 6

1.1 Purpose of the document................................................................................................ 6

1.2 Document outline............................................................................................................ 6

2. Application scenarios and requirements............................................................................. 8

2.1 Broadband market analysis ............................................................................................. 8

2.1.1 Fixed broadband...................................................................................................... 8

2.1.2 Mobile broadband................................................................................................. 11

2.2 Internet traffic analysis and forecast............................................................................. 13

2.2.1 Technology evolution ............................................................................................ 13

2.2.2 Global traffic .......................................................................................................... 14

2.2.3 Mobile traffic ......................................................................................................... 15

2.2.4 Cloud traffic ........................................................................................................... 16

2.3 Future traffic trends ...................................................................................................... 18

2.4 Application scenarios .................................................................................................... 20

2.4.1 Convergence of fixed and mobile networks.......................................................... 20

2.4.2 Support of bandwidth-‐intensive end-‐user applications ........................................ 21

2.4.3 Support of service and network virtualization ...................................................... 22

2.5 Application-‐driven network requirements.................................................................... 24

2.6 Reference network architecture ................................................................................... 25

3. System requirements and design ...................................................................................... 28

3.1 System requirements .................................................................................................... 28

3.2 System specification...................................................................................................... 29

3.2.1 Modulation Formats.............................................................................................. 29

3.2.2 Multi-‐Carrier/Superchannel Generation ............................................................... 31

3.2.3 Software-‐Defined Operation ................................................................................. 34

3.3 Test Cases ...................................................................................................................... 34

3.3.1 Laboratory Testing at Ericsson .............................................................................. 34

3.3.2 Laboratory Testing at ICCS/NTUA.......................................................................... 38

3.3.3 Field Trial Testing................................................................................................... 39

4. Conclusions ....................................................................................................................... 40

5. List of Figures .................................................................................................................... 41

6. List of tables ...................................................................................................................... 42


7. Abbreviations .................................................................................................................... 43

8. References......................................................................................................................... 44


1. Introduction

New end-‐user applications such video streaming, online storage, online social networks, etc. are bandwidth-‐intensive and thus, are stretching the capacity of the physical layer to the limits. Moreover, a general trend is observed over the last few years towards software-‐defined architectures and virtualized network functionalities so as to support cloud-‐based applications in terms of mobility, agility and flexibility.

In order to accommodate bandwidth-‐hungry applications, as well as virtualization and software-‐defined networking architectures, fully programmable optical components that will support easy rate and format adaptation upon the requirements of the upper layers are needed. SPIRIT [1] will fabricate low-‐cost, energy-‐efficient flexible transceivers that are capable of flex grid and gridless operation, while being compatible with both current and future applications. Additionally, both single-‐ and multi-‐carrier (OFDM) QAM formats will be supported. Interfacing to external digital control logic will allow dynamic adjustment of the symbol rate (up to 32GBaud) and modulation format.

The design and fabrication of SPIRIT’s devices is driven by the requirements set by its target applications; system-‐level specifications need to be set in order to achieve compatible operation with current and future optical networking applications. The system specifications, in turn, need to be appropriately translated to the component level: Devices will be needed that will meet the functionality and performance levels in terms of bandwidth, resolution, flexibility and programmability.

1.1 Purpose of the document

The purpose of this document is manifold:

! To identify and describe the potential application scenarios of the SPIRIT transceiver based on current and forecasted traffic and market trends, the objectives for telecommunications in Europe until 2020, and upcoming new networking paradigms such as cloud computing, network function virtualization and software-‐defined networking.

! Based on the identified application scenarios of the SPIRIT transceiver, to derive the application-‐driven network requirements (e.g. in terms of rate and latency).

! To map the network requirements to system-‐level requirements.

! To provide the initial system specification of the SPIRIT component based on the above system requirements.

! To define specific test-‐cases for the SPIRIT prototype.

1.2 Document outline

This document is organized as follows:


Section 2 provides an overview of the factors that drive the need for flexible, fully-‐programmable, optical components, describes the application scenarios for the SPIRIT transceiver, and defines the application-‐driven network requirements for the respective scenarios.

Section 3 outlines the system requirements, as well as test cases to be used in the evaluation of the devices of SPIRIT.

Finally, Section 4 summarizes this document and presents the main conclusions.


2. Application scenarios and requirements

In this chapter, the increasing capacity demand of end-‐user applications, which is expected to drive the growth of aggregate traffic at the metro/core network of ISPs, is discussed. In particular, we consider current and forecasted traffic and market trends, the objectives for telecommunications in Europe for the next six years, as well as new networking paradigms that drive the development of new applications, and thus, capacity demand. Furthermore, specific application scenarios for the SPIRIT optical component are discussed. Finally, the bandwidth and network requirements of the SPIRIT flexible transceiver in the aforementioned scenarios are analyzed, taking into account the prospective capacity demand of end-‐user applications.

2.1 Broadband market analysis

A qualitative and quantitative analysis on the use and implementation of broadband infrastructures and services, both for fixed and mobile networks is discussed in this section. Specifically, we deal with Internet demographics such as broadband coverage and penetration, number of fixed and mobile users, and future targets for the telecommunications market in Europe.

Europe 20201 is a 10-‐year strategy proposed by the European Commission on March 3rd, 2010, for advancement of the economy of the European Union (EU). The initiative of Europe 2020 related to the roll-‐out of high-‐speed Internet, constitutes the so-‐called Digital Agenda2 (DA) for Europe. The DA identifies the need for much faster internet access than is generally available in Europe, especially for providing new services such as high definition television or videoconferencing. To match world leaders like South Korea and Japan, the DA identifies the need for Europe to achieve download rates of 30 Mbps for all of its citizens, and 100 Mbps for at least 50% of European households subscribing to internet connections by 2020.

Two important metrics for the quantification of the broadband market are broadband coverage, and broadband penetration. Broadband coverage is the percentage of population where a broadband contract can be activated by the telecom operator without the need for new deployments, while broadband penetration is the percentage of population with an active broadband contract.

2.1.1 Fixed broadband According to [2], at the end of 2012, over 99.9% of European homes could have access to at least a basic broadband network considering all technologies, i.e., including fixed, fixed-‐wireless, mobile and satellite access. Satellite broadband has the largest physical

1 http://ec.europa.eu/europe2020/index_en.htm 2 http://ec.europa.eu/digital-‐agenda/


coverage: It is available to 100% of the population in 24 of 27 Member States. Despite the high coverage, satellite take-‐up is still marginal, as it represents less than 1% of all EU broadband lines. Without satellite, 99.4% of homes are covered by broadband (standard broadband). Considering only fixed and fixed-‐wireless technologies (standard fixed broadband), coverage goes down to 95.5% leaving a gap of more than 9 million homes.

Moreover, Next Generation Access (NGA) technologies capable of at least 30 Mbps are available to 53.8% of homes as of the end of 2012, while Docsis 3.0 cable has by far the highest NGA footprint (39.4%), followed by VDSL (24.9%) and FTTP (12.2%). Expectedly, broadband coverage is significantly lower in rural areas. Standard broadband covers 96.1% while standard fixed broadband reached only 83.2% of rural homes. Wireless technologies (satellite and mobile HSPA) exceed the rural coverage of fixed technologies in general. Moreover, NGA remains very low in rural areas, with 12.4% availability. Figure 2-‐1 and Figure 2-‐2 illustrate the standard fixed and NGA coverage in EU countries, respectively.

Figure 2-‐1: Fixed broadband coverage; end of 2012. (Source: Point Topic)

As of January 2013 there were 144.8 million fixed broadband lines in the EU, which corresponds to 28.8 lines per 100 inhabitants. Although the annual growth has been continuously slowing down since 2007, the fixed broadband market grew by 5.5 million lines in 2012. There is still potential for further growth in the market, as 24% of EU homes do not have an internet subscription. Figure 2-‐3 depicts the fixed broadband penetration at the EU level between years 2004-‐2013.

Additionally, fixed broadband penetration in the EU was slightly higher than in Japan and just below that of the US as of July 2012. Figure 2-‐4 shows the fixed broadband penetration both in EU and OECD countries as of July 2012.


Figure 2-‐2: NGA coverage; end of 2012. (Source: Point Topic)

Figure 2-‐3: Fixed broadband penetration; 2004-‐2013. (Source: Communications Committee)

Concerning the fixed broadband market, xDSL continues to be the predominant technology in the EU despite the decrease of its share from 80.9% of all fixed broadband lines in January 2006, to 73.8% in January 2013. Nevertheless, the number of xDSL lines increased by 1.7 million in 2012. All of this increase can be attributed to VDSL lines, which currently represent a mere 3.9% of xDSL lines.

Cable, being the second most widespread fixed technology, has slightly increased its market share from 15.4% to 17.4% since 2010. The number of cable lines increased by 2 million, slightly surpassing xDSL in growth in 2012. NGA cable based on DOCSIS 3.0 doubled in 2012, as it expanded by 8.4 million lines making cable the most widely used NGA technology in the EU. By now, the vast majority of European cable networks have been upgraded to DOCSIS 3.0, and two thirds of cable subscriptions have already been


migrated to this standard. As for the other technologies, fibre lines (FTTH and FTTB) went up by 31% in the last 12 months, but still represent only 5.1% of all fixed broadband lines.

Figure 2-‐4: Fixed broadband subscription per 100 inhabitants; EU & OECD; July 2012.

(Source: Communications Committee and OECD [3])

In total, NGA technologies, including FTTx, VDSL and cable, are available to 54% of EU homes, but take-‐up is only around 12%.

2.1.2 Mobile broadband Concerning mobile broadband, we focus on third generation (3G) HSPA and fourth generation (4G) LTE networks. On average, there was 96.3% population coverage of third generation HSPA networks in the EU in December 2012, while rural coverage varies greatly among countries, but on average it is higher than any fixed technology [2]. On the other hand, the European coverage of fourth generation LTE networks tripled in 2012; currently, LTE is available to 26.2% of population, while it mainly covers urban areas. Figure 2-‐5 and Figure 2-‐6 illustrate the coverage of HSPA and LTE in the EU as of the end of 2012.


Figure 2-‐5: HSPA coverage; end of 2012. (Source: Point Topic)

Figure 2-‐6: LTE coverage; end of 2012. (Source: Point Topic)

Mobile broadband penetration reached 54.5% (use of handheld devices and computers), although the growth slowed down last year. Moreover, 83.4% of mobile broadband subscriptions were used in handheld devices. Figure 2-‐7 depicts the mobile broadband penetration for both technologies at EU level, per type of device for the years from 2009 to 2013.


Figure 2-‐7: Mobile broadband penetration at EU level; 2009-‐2013. (Source: Communications Committee)

2.2 Internet traffic analysis and forecast

2.2.1 Technology evolution Over the last few years, the rise and adoption of a new computing paradigm has been observed: That of cloud computing. This includes new service models such as Infrastructure-‐as-‐a-‐Service (IaaS), Platform-‐as-‐a-‐Service (PaaS), Software-‐as-‐a-‐Service (SaaS), or Network-‐as-‐a-‐Service (NaaS).

The first three involve data center virtualization and imply the provision of infrastructure (e.g. storage, computation), platform (e.g. virtual machines), or software (e.g. online storage applications such as Dropbox3 or Google Drive4) as services to third parties. On the other hand, the fourth one, i.e. NaaS, involves a network infrastructure provider employing network virtualization by means of software-‐defined networking and network function virtualization so as to provide network resources (e.g. access to nodes, links with specific QoS requirements) to his customers dynamically (i.e. on-‐the-‐fly), in a flexible and scalable manner.

Software-‐defined networking (SDN) is a recently proposed approach (cf. OpenFlow [5]) that enables network management through an abstraction of lower level functionality. This is practically done by decoupling the control plane (i.e. the modules that make decisions about traffic routing), from the data plane (i.e. the underlying systems such as routers and switches that forward traffic to the selected destination). Within the context of software-‐defined networking, network functions virtualization (NFV) [6] was

3 https://www.dropbox.com/ 4 https://drive.google.com/


introduced by ETSI Industry Specification Group (ISG) that proposes the virtualization of network functions, previously carried out by proprietary, dedicated hardware.

An example of NaaS is network slicing or Bandwidth-‐on-‐Demand (BoD). In particular, network slicing involves splitting of available network capacity (e.g. bandwidth) into channels, each of which is independent from the others, and can be assigned to specific server of device based on their QoS requirements for a specific amount of time. Under this model link rates can be dynamically adapted to the traffic demands of the nodes connected to the link in real-‐time.

Moreover, Virtual Private Networks (VPNs) constitute an older example of the recent-‐rising NaaS, however by means of SDN their operation will be much more flexible. Finally, another case falling under the scope of NaaS is mobile network virtualization. In this case, a Mobile Network Operator (MNO) builds and operates a network and sells its communication access capabilities to third parties, e.g. Mobile Virtual Network Operators (MVNOs), charging them by capacity utilization. An MVNO is, thus, a mobile communications service provider that does not own the radio spectrum or wireless network infrastructure over which it provides services; rather, it offers its communication services using the network infrastructure of an established Mobile Network Operator.

The evolution of technology as described in previous paragraphs has led to a significant increase of the aggregate IP traffic in core, metro and access networks. In the following sections, we report findings of Cisco studies on the volume of IP traffic that crosses today’s networks, as well as forecasts for the next 4 years up to 2017.

2.2.2 Global traffic Global IP traffic is forecast to surpass the zettabyte5 (ZB) threshold by 2017 [7], i.e., 1.4 ZBs per year, or 120 exabytes (EBs) per month. In particular, global IP traffic has increased more than fourfold within 2008-‐2012, and will increase threefold until 2017. Overall, IP traffic will grow at a compound annual growth rate (CAGR) of 23% from 2012 to 2017 as presented in Table 2-‐1.

The high increase of data center IP traffic is mainly due to the faster delivery of services and data, increased performance of applications, and improved operational efficiency. Indeed data center traffic dominated IP traffic since 2008 [9], however, it is undergoing a fundamental transformation due to the rise of cloud computing (see Section 2.2.1).

Metro-‐only traffic (traffic that traverses only the metro network of ISPs and bypasses long-‐haul traffic links) will surpass long-‐haul traffic in 2014 as it will grow nearly twice as fast as long-‐haul traffic, and it will account for 58% of total IP traffic by 2017 (Table 2-‐2). The higher traffic growth in metro networks is due in part to the increasingly significant role of Content Delivery Networks (CDNs), which bypass long-‐haul links and deliver

5 1 zettabyte (ZB) = 10007 bytes (Bs)


traffic to metro and regional backbones. Specifically, CDNs will carry over half, i.e., 51%, of Internet traffic in 2017 from 34% in 2012.

Table 2-‐1: Global IP traffic; 2012-‐2017. (Source: Cisco VNI, 2013)

Additionally, Internet video traffic will be 69% of all Internet traffic in 2017, up from 57% in 2012; note that this percentage does not include video exchanged through peer-‐to-‐peer (P2P) file sharing. In particular, the sum of all forms of video (TV, VoD, Internet, and P2P) will be in the range of 80%-‐90% of global consumer traffic by 2017. Specifically, it is estimated that it will take an individual over 5 million years to watch the amount of video that will cross global IP networks each month in 2017, while every second, nearly a million minutes of video content will cross the network.

Table 2-‐2: Metro and Long-‐Haul traffic; 2012-‐2017. (Source: Cisco VNI, 2013)

2.2.3 Mobile traffic Global mobile data traffic grew 81% in 2013, while reaching 1.5 EBs per month at the end of the same year, up from 820 petabytes (PBs) per month at the end of 2012. Moreover, over half a billion (526 million) mobile devices and connections were added


in 2013, while mobile devices and connections in 2013 grew to 7 billion, up from 6.5 billion in 2012.

According to [8], traffic from wireless and mobile devices exceeded 50% of IP traffic in 2012, in contradiction to former projections that it would surpass fixed traffic in 2016 [7]. Moreover, in 2013, a 4G connection generated 14.5 times more traffic on average than a non-‐4G connection. Although 4G connections represent only 2.9 percent of mobile connections today, they already account for 30 percent of mobile data traffic.

Globally, mobile data traffic is expected to increase 11-‐fold, growing at a CAGR of 61% between 2013 and 2018, reaching 15.9 EBs per month by 2018 [8] while by the end of 2014, the number of mobile-‐connected devices will exceed the number of people on earth, and by 2018 there will be nearly 1.4 mobile devices per capita. There will be over 10 billion mobile-‐connected devices, including machine-‐to-‐machine (M2M) modules—exceeding the world’s population at that time (7.6 billion).

Finally, over two-‐thirds of the world’s mobile data traffic will be video by 2018. Mobile video will increase 14-‐fold between 2013 and 2018, accounting for 69% of total mobile data traffic by the end of the forecast period (Figure 2-‐9).

Figure 2-‐8: Mobile IP traffic; 2013-‐2018. (Source: Cisco VNI Mobile, 2014)

Figure 2-‐9: Mobile video traffic; 2013-‐2018. (Source: Cisco VNI Mobile, 2014)

2.2.4 Cloud traffic Two major technology trends arose within the last years: Cloud computing and data center / network virtualization. In this section, we capture some characteristics of the impact of these trends in terms of IP traffic increase.

Specifically, in [9], it is forecasted that global data center IP traffic will reach 7.7 ZBs per year or 644 EBs per month, up from 214 EBs per month in 2012, by the end of 2017. Moreover, about two thirds of this traffic will be comprised of workload processed in the cloud; thus, global cloud IP traffic will reach in 2017 5.3 ZBs per year or 443 EBs per month up from 98 EBs per month in 2012.


Note that while the amount of global traffic crossing the Internet and IP WAN networks is projected to reach 1.4 ZBs per year in 2017 [7], the amount of data center traffic is already 2.6 ZBs per year—and by 2017, it will triple, reaching 7.7 ZBs per year [9]. The higher volume of data center traffic is due to the inclusion of traffic that is not only from the data center to the user and vice versa, but also traffic between data centers, as well as traffic inside the data center.

Table 2-‐3 provides details of the growth of global data center traffic, overall and by type, from 2012 to 2017. It can be observed that most of the traffic, i.e. up to 75%, remains within the data center. However, traffic that traverses IP WAN links, i.e. traffic from the data center to the user and vice versa, and inter-‐data center traffic (e.g. for replication purposes), reaches 25% of global data center traffic, i.e. 1.8 ZBs per year in 2017.

Significant promoters of cloud traffic growth are the rapid adoption of and migration to cloud architectures, along with the ability of cloud data centers to handle significantly higher traffic loads. Cloud data centers support increased virtualization, standardization, and automation. These factors lead to increased performance, as well as higher capacity and throughput.

Table 2-‐3: Global data center traffic; 2012-‐2017. (Source: Cisco Global Cloud Index, 2013)

Real-‐time and time-‐sensitive applications are contributing to increased cloud adoption in both the business and consumer segments. For business, the necessity to provide fast and flexible access to large data archives is an important objective for IT organizations considering cloud-‐based solutions. In addition, enabling advanced analytics to tap into the wealth of information contained in largely unstructured data archives can create a valuable competitive business advantage. Moreover, enhanced collaboration services delivered through the cloud can increase employee productivity and customer satisfaction.


Figure 2-‐10: Personal content locker traffic growth; 2012-‐2017. (Source: Cisco Global Cloud

Index, 2013)

On the other hand, in the consumer space, applications such as video and audio streaming are strong contributors to cloud traffic growth, while newer services such as personal content lockers are also gaining in popularity. In particular, personal content lockers such as Dropbox and Google Drive are applications by means of which users can store and share music, photos, and videos online, through an easy-‐to-‐use interface at relatively low or no cost. Furthermore, the proliferation of tablets, smartphones, and other mobile devices, which allow access to personal content lockers in a manner convenient to the user, drives the increasing popularity of such applications. Specifically, personal cloud traffic is expected to increase from 1.7 EBs annually in 2012 to 20 EBs in 2017, at a CAGR of 63% [9] (Figure 2-‐10).

2.3 Future traffic trends

Broadband speed improvement results in increased consumption and use of high-‐bandwidth content and applications. According to [10], the global average fixed broadband speed will continue to grow and will nearly quadruple from 2012 to 2017, from 11.3 Mbps to 39 Mbps. Several factors that influence the fixed broadband speed forecast include the deployment and adoption of FTTx, high-‐speed xDSL and cable broadband adoption, as well as overall broadband penetration. On the other hand, the average mobile broadband speed in 2012 was 526 kbps, while the average speed will grow at a CAGR of 4%, and will exceed 3.9 Mbps in 2017. Additionally, smartphone speeds, generally 3G and higher, are currently almost four times higher than the overall average, while they are expected to triple by 2017, reaching 6.5 Mbps.

As discussed in Section 2.1.2 and Section 2.2.3, mobile data traffic is driving an exponential increase in data transmission through the Internet. This is due to the increasing adoption of mobile devices like smartphones and tablets, which are moving away from being purely "utility" devices, with entertainment increasingly occupying a central role in the usage of internet on-‐the-‐go. In particular, smartphones accounted for more than half of all handset shipments in 2013, and the percentage is expected to


continue to grow, mainly due to decreasing prices and the perceived value, and greater integration of mobile apps into everyday life [4].

Moreover, the emergence of faster and widely accessible internet connection is having an impact on the television and movie sectors. In particular, concepts like SmartTV, PayTV or VoD (video-‐on-‐demand) have become equally familiar as traditional direct television or movie viewing. The increase of the IP video traffic will drive and accelerate the global IP traffic growth until 2017 [10]. Globally, IP video traffic will account for 73% of traffic in 2017.

Additionally, Live TV is currently distributed by means of a broadcast network, which is highly efficient in that it carries one stream to many viewers. Live TV over the Internet would carry a separate stream for each viewer. Such a shift from multicast or broadcast to over-‐the-‐top unicast would multiply the IP backbone traffic by more than an order of magnitude [11]. Furthermore, the IP video traffic will be further affected by the adoption of 3DTV (three-‐dimensional TV), which is foreseen to take 3 to 5 years to gain momentum [10].

The increase of the popularity of IP video is the underlying reason for accelerated busy-‐hour traffic growth. Unlike other forms of traffic that are spread evenly throughout the day (such as web browsing and file sharing), video tends to have a “prime time”. Because of such video consumption patterns, the Internet has a much busier busy hour as video popularity increases. Because video has a higher peak-‐to-‐average ratio than data or file sharing, and because video is gaining traffic share, peak Internet traffic grows faster than average traffic [10].

Moreover, the use of social networking sites has grown over the past few years and posting messages to social media sites or instant messaging has become one of the most popular activities of European internet users with same levels of take-‐up as reading newspapers or internet banking. Social network services are also one of the driving factors behind the production and uptake of online video games, also called cloud games, supported by online app stores and played on general-‐purpose devices including the PC browser, smart phones and tablets, and to a lesser degree smart TVs and TV connected boxes.

With traditional gaming, graphical processing is done locally on the gamer’s computer or console. With cloud gaming, game graphics are produced on a remote server and transmitted over the network to the gamer. Currently, online gaming traffic represents only 0.04% of the total information content associated with online and offline game play [12]. If cloud gaming takes hold, gaming could quickly become one of the largest Internet traffic categories.

Another significant promoter of IP traffic growth is the rapid adoption of and migration to cloud architectures, along with the ability of cloud data centers to handle significantly higher traffic loads. In order for cloud data centers to support virtualization, service mobility and redundancy, data replication and Virtual Machine (VM) migration needs to be performed. Furthermore, data center and cloud federation for footprint expansion


and collaborative service provisioning so as to achieve energy efficiency and increased availability also contributes to the global IP traffic. The inter-‐data center communication necessary for the aforementioned activities leads to increased performance, but simultaneously generates huge traffic volumes to be handed by metro/core networks of telecom operators.

The increase in the speed of broadband internet access, the development of more modern devices and the migration of multiple services and applications in the cloud drive the increase of both fixed and mobile IP traffic. Naturally, the trend toward mobility carries over into the realm of fixed metro/core networks as well, in that an increasing portion of traffic will originate from portable or mobile devices.

The increased volume and volatility of traffic patterns generated by new services and applications accentuate the pressure for technological development and innovation on the part of service providers and network components vendors. Eventually, the identified market and traffic trends constitute the necessity for high-‐capacity optical components that will support flexibility, dynamicity and programmability such as the SPIRIT transceiver.

2.4 Application scenarios

Considering the market analysis and evolution discussed in Section 2.1, the technology evolution and the IP traffic analysis and forecasting presented in Section 2.2, we define below three potential application scenarios for the SPIRIT transceiver.

2.4.1 Convergence of fixed and mobile networks As discussed in Section 2.1.2, smartphones accounted for more than half of all handset shipments in 2013, and the percentage is expected to continue to grow, mainly due to decreasing prices and the perceived value and greater integration of mobile apps into everyday life [4]. Additionally, the number of mobile SIM cards grew by 17.4 million in 2012, while more than 30% of the growth came from Machine-‐to-‐Machine (M2M) SIM cards [2]. Moreover, the enhanced speed of 4G and the decreasing prices for mobile access by means of 3G is also increasing the attractiveness of games, video and interactive services. Furthermore, the number of MVNOs grew by 3.2 million within 2012. Therefore, smartphones, M2M, new mobile broadband services, higher mobile broadband access speeds and lower prices are driving the exponential increase in mobile data traffic in both Europe and worldwide.

As discussed in Section 2.1 and Section 2.2, IP traffic both fixed and mobile will increase significantly within the next 4-‐5 years. Thus, in order for telecom operators to efficiently address the increasing traffic demand from mobile access networks, we define as the first application scenario for the SPIRIT transceiver the convergence of fixed and mobile networks. Specifically, we consider telecom operators selling backhauling to MNOs or MVNOs, while serving simultaneously their own, business and residential, fixed customers. Additionally, QoS requirements of the various types of traffic and SLAs


established with M(V)NOs need to be fulfilled dynamically. The SPIRIT optical transceiver in combination with SDN and network virtualization techniques will achieve efficient and flexible management of traffic originated by both fixed and mobile access networks in the metro and core networks of telecom operators.

Figure 2-‐11: Support of high-‐bandwidth consuming applications with heterogeneous QoS requirements for a multitude of users with different access devices.

2.4.2 Support of bandwidth-‐intensive end-‐user applications As estimated in [7], Internet video traffic will be 69% of all Internet traffic in 2017, up from 57% in 2012, whereas the aggregate volume of all forms of video, i.e., live TV, VoD, Internet (HTTP-‐Based) and P2P, will be in the range of 80%-‐90% of global consumer IP traffic. Additionally, it is expected that over two-‐thirds of the world’s mobile data traffic will be video by 2018 [8]. This video streaming traffic increase is led by:

• the increasing access speeds, both fixed and mobile, that will be offered to end-‐users by the telecom operators,

• the investment and evolution of the audio-‐visual industry, • the emergence and adoption smart TV, i.e. larger screen requires video of higher

resolution and thus, higher bitrates, and • the adoption and increase of mobile devices (see Section 2.1.4).

At the same time, apart from video streaming, another category of applications that are strong contributors to IP traffic growth is online personal storage such as Dropbox [9]. The increasing popularity of such application is driven also by the proliferation of tablets, smartphones, and other mobile devices, and is of high importance to SPIRIT due to the high impact of these applications in terms of traffic volume on core, metro and access links. Moreover, social networking with more than 1 billion active users drives the increase of interacting applications such as online gaming, which is performed in non-‐dedicated devices such as smartphones and tablets.

The aforementioned applications are also responsible for the increase of IP traffic especially, at the metro networks of telecom operators, but also at the core network, as


also indicated in Table 2-‐2, which is the application field of the SPIRIT transceiver. Therefore, the second application scenario for the SPIRIT transceiver addresses the support of high-‐bandwidth demanding/consuming applications, such as video streaming, online personal storage applications, and online gaming, and is depicted in Figure 2-‐12. In particular, this scenario addresses the efficient and QoS-‐aware support of bandwidth-‐intensive applications, concurrently, for a multitude of users that access them by multiple devices with different characteristics. The explicit application-‐driven network requirements are reported in Section 2.5.

Figure 2-‐12: Support of high-‐bandwidth consuming applications with heterogeneous QoS requirements for a multitude of users with different access devices.

2.4.3 Support of service and network virtualization We discussed in the beginning of Section 2.2, the rapid adoption of cloud computing and the evolution of traditional networking architectures to virtualized ones by means of software-‐defined networking and network functions virtualization paradigms. The so-‐called network virtualization and the adoption of cloud computing constitute drivers for the high increase of global IP traffic and especially traffic crossing the core and metro networks of telecom operators.

As reported in [9], the amount of data center traffic is 2.6 ZBs per year, while it will triple to reach 7.7 ZBs per year in 2017. In particular, in [9], it is observed that most of the traffic, i.e., up to 75%, remains within the data center, whereas traffic that trespasses IP WAN links, i.e. traffic from the data center to the user and vice versa, and inter-‐data center traffic, reaches 25% of global data center traffic. This 25% corresponds to 1.8 ZBs per year in 2017, which is higher that the global public IP traffic, i.e. 1.4 ZBs per year in 2017.

Thus, the third application field for the SPIRIT transceiver includes the dynamic and flexible management of the traffic generated by the communication between data


center and end-‐users (and vice versa), as well as inter-‐data center communication, e.g., virtual machines migration to multiple cloud locations for boost of availability and QoS support, or content/data replication to alternative locations to achieve redundancy, fault-‐tolerance, etc.

Additionally, the communication between data centers and end-‐users includes a multitude of services and applications that are served by both cloud and traditional data centers, and which employ heterogeneous QoS requirements depending also on the type of users, i.e., residential, business or enterprise ones. For instance, in the case of enterprise and business customers, apart from performance-‐related requirements, security might be also significant, e.g., for banking institutions or governmental organizations; thus, traffic generated by the communication between the data centers of business/enterprise customers and their users, or inter-‐data center traffic needs to be served over dedicated lines, either physically, e.g. leased lines, or, more commonly, logically, e.g., by means of VPN.

Therefore, the SPIRIT transceiver needs to be capable of sufficiently addressing the heterogeneous QoS requirements of these services and applications dynamically, on-‐demand, and in a scalable manner, i.e., without any performance deterioration while the user number increases (dramatically). Figure 2-‐13 illustrates the case of a network simultaneously supporting inter-‐data center communication between the sites of an enterprise, the communication between the enterprise data centers and some enterprise users, as well as the communication of residential users with a generic cloud operator offering some cloud service, e.g. online personal storage.

Figure 2-‐13: Support of service and network virtualization; flexible and dynamic management of data center to user and inter-‐data center communication for services

with heterogeneous QoS requirements for a multitude of users.


2.5 Application-‐driven network requirements

Based on the identified application scenarios for SPIRIT that have been described in Section 2.4, in this section we present the application-‐driven network requirements for the SPIRIT component, which will be translated to system requirements to be addressed by the design of the transceiver in Section 3.

Major qualitative requirements for the SPIRIT optical transceiver are:

• Flexibility to sufficiently address volatility of resources demand;

• Dynamicity to support rate-‐ and format-‐adaptation on-‐the-‐fly based either on monitoring of some pre-‐defined KPI, or on-‐demand;

• Granularity of adaptation per flow, end-‐point device, or network slice;

• Programmability to support rate-‐ and format-‐ adaptation;

• Monitoring and troubleshooting;

• Support of Network Functions Virtualization (NFV);

• Performance and scalability.

In particular, concerning performance, quantitative network requirements in terms of bitrate for video streaming, and online gaming are discussed below. Note that we do not consider here applications such as online personal storage or online social networks, as traffic generated by them can be considered as delay-‐tolerant.

Video streaming is the most popular and bandwidth-‐consuming application according to recent studies ([7], [13]), while it has significant impact also on mobile networks [8]. A number of online video streaming/on demand and digital download services offer HD video, among them YouTube, Vimeo, Hulu, Amazon Video On Demand, Netflix Watch Instantly, and others. Table 2-‐4 summarizes the requirements of HTTP video streaming in terms of bitrate. Note though that due to heavy compression, the image detail produced by these formats are far below that of broadcast HD.

Table 2-‐4: Bitrate of HTTP video streaming.

Resolution Video bitrate Audio bitrate Highest bitrate

HD (1920x1080) 3.5-‐4.5 Mbps 256-‐320 Kbps 5 Mbps

HD (1280x720) 2.5-‐4.5 Mbps 256-‐320 Kbps 5 Mbps

SD (1280x720) 2.5 Mbps 192 Kbps 3 Mbps

Concerning IPTV bandwidth requirements, there is no standard value, as IPTV bandwidth may be dependent on other added-‐value services accompanying the IPTV service, the number of simultaneous streams, as well as compression methods. However, a typical IPTV service requires up to 4 Mbps downstream for SD quality (720x480), and up to 8-‐10 Mbps downstream for HD (1920x1080), while higher values,


e.g. 13 Mbps, have been reported in literature. Upstream can be much lower, as it is required only for EPG handling.

Next, we focus on online gaming and especially cloud gaming. Cloud gaming is a newly-‐emerged gaming paradigm, and the most bandwidth-‐demanding form of online gaming, as it combines cloud computing and online gaming. Cloud gaming is real-‐time game playing via thin clients. Essentially, cloud gaming moves the game logic required to run a game away from the user, and into a data center (the cloud), and then streams the entire game experience to the user. The streaming can be done in three ways: i) Streaming the 3D graphics and update messages to the player (which is the classical approach), ii) encoding the game frames as video and streaming the video to the player, or iii) a hybrid approach of streaming graphics primitives as well as video simultaneously.

According to [14], the video streaming case, called Game-‐as-‐Video (GaV), although a new paradigm, has been commercially successful and is growing rapidly. Using video streaming, the gamer is no longer required to possess high-‐end gaming hardware; the only requirement for the client side is broadband internet connection and the ability to display high quality video. Therefore, it can be safely assumed that the bandwidth requirements for cloud gaming are similar to those of HD video streaming.

Nonetheless, cloud gaming is also highly time-‐sensitive, i.e., latency is also of the highest importance, which is not the case for the video streaming paradigm. In particular, according to [15], 100 ms (milliseconds) is the optimal latency which is acceptable by the end-‐users; by subtracting a 20 ms playout and processing delay from the target 100 ms latency, 80 ms is the threshold network latency for cloud gaming.

2.6 Reference network architecture

The IP network of OTE consists of 15 BRAS and 47 ATM nodes; it is depicted in Figure 2-‐14. Moreover, the backbone network of OTE, which is depicted in Figure 2-‐15, consists entirely of optical fibers with length of 27800 km on land and 6000 km submarine.

The transmission network of OTE currently has 1960 NG-‐SDH nodes, 16 DWDM local and national rings with a total capacity exceeding 2.7 Terabit/s, while it is continuously expanding in order to offer even higher data speeds as well as to support / provide sophisticated applications and services. Figure 2-‐16 depicts an Ethernet domain, which is part of the network of OTE.


Figure 2-‐14: IP network of OTE.

Figure 2-‐15: Optical core network of OTE.


Figure 2-‐16: Part of an Ethernet domain of OTE.


3. System requirements and design

3.1 System requirements

The SPIRIT transceiver’s high spectral efficiency, advanced flexibility and software-‐defined capabilities are perfectly suitable for elastic optical networks and pure coherent optical infrastructures. However, changes in the deployed DWDM networks are slow and costly, so it is expected that the SPIRIT transceiver will also operate in legacy environments. The following scenarios should be addressed:

1) Scenario 1: New generation coherent elastic networks: These networks will allow optimal use of SPIRIT transceiver functionalities in terms of flexibility, spectral efficiency, reach performance, and network utilization. They are characterized by:

-‐ All-‐coherent line interface (100G, 400G, 1T, flex-‐rate) with no legacy OOK 10G traffic (10G traffic is muxponded by high rate interfaces).

-‐ No inline optical dispersion compensation (high non-‐linear tolerance, reduced optical amplification, lower cost).

-‐ Flex-‐grid: Spectrum can be allocated according to new ITU recommendations. ROADMs are flex-‐grid.

-‐ SMF or new fiber.

-‐ Typical ultra-‐long haul (ULH) reach >3000 km.

2) Scenario 2: Fixed Grid coherent networks. These networks are recently deployed or upgraded in order to better support coherent transmission, but without the investments for flex-‐grid operation. Elasticity can still be exploited in some way, but spectrum allocation is rigid.

-‐ All coherent interfaces with no legacy OOK 10G traffic.

-‐ No in-‐line optical dispersion compensation.

-‐ Fixed, 50GHz grid.

-‐ SMF (G652), G655 fiber (TW, eLeaf).

-‐ Typical ULH reach > 3000 km.

3) Scenario 3: Fixed Grid legacy networks. Many deployed networks are still based on 10G infrastructure with dispersion compensation. We assume that no 10G OOK line traffic will co-‐exist with 400G or 1T traffic, assuming all the legacy OOK traffic will be muxed in higher rate line interfaces.

-‐ All coherent interfaces.

-‐ In-‐line dispersion compensation.

-‐ Fixed, 50GHz grid.


-‐ SMF (G652), G655 fiber (TW, eLeaf).

-‐ Typical ULH reach 1500-‐3000 km.

Recent deployments may have colorless/directionless (C/D) or even contention-‐less (CDC) ROADMs, while legacy networks may have directionless only for restoration purposes, or even simple ROADMs with no flexibility.

3.2 System specification

The functional units that will be developed will ensure the transmission over the network scenarios listed in Section 3.1. Therefore, modulation formats will be selected in order to guarantee an adequate tolerance to signal to noise ratio (OSNR), linear distortions due to optical fiber transmission (GVD, PMD, PDL, etc.) and nonlinear effects (XPM, SPM, etc.), both in the presence and in the absence of chromatic dispersion compensation. The following features are requested:

! Stabilization of the various circuit blocks that make up the transmitter and the optical receiver (temperature, aging, etc.).

! Appropriate FEC code (with Hard-‐ and Soft-‐Decision available). To comply with ULH reach, a BER <1E-‐2 is recommended.

! Digital CD and PMD compensation to ensure operability in new generation networks. Non-‐linear compensation can boost the reach, giving 1-‐2 dB more margin: Back-‐Propagation Vs linearized channel inversion methods should be benchmarked.

! Ability to control the signal quality and monitoring of linear/nonlinear distortions introduced by the optical link (GVD, DGD, OSNR, etc.). This monitoring information is used by the SDN controller to optimize transceiver configuration and operate protection/restoration switching mechanism. DSP usage can also be monitored in order to perform power-‐saving operation depending on performance required.

! Compatible with Hybrid Raman/EDFA amplification.

3.2.1 Modulation Formats

SPIRIT transceivers will be compatible with current and near-‐future standards. In particular, 100Gb/s implementation will be supported with DP-‐QPSK at 28/32 Gbaud (with appropriate FEC overhead). The emerging standard for 400Gb/s (and later 1Tb/s) must comply with relevant evolving standards (ITU-‐T, OIF) during the course of the project. SPIRIT’s transceivers will explore possible avenues for 400G and 1T implementation. Figure 3-‐1 illustrates the flexibility of SPIRIT transceivers in terms of the range of possible configurations, given their capability in terms of baudrate (up to 32GBaud) and dual-‐polarization QAM formats, on a single wavelength (shaded area). The solid curves indicate the loci of bits/symbol-‐baudrate pairs needed for generating a 400G channel (448Gb/s with overhead) with 1 carrier (black line), 2 carriers (red), 3 carriers (green) and 4 carriers (blue). Thus, the intersection of the shaded area with the


loci in the plot show the 400G configurations possible with SPIRIT devices, in terms of carrier number, baudrate and QAM format. As can be seen, 400G is possible for a SPIRIT transceiver even with a single carrier configuration (or multiple carriers and lower-‐order QAM formats depending on the transmission reach).

Figure 3-‐1: Showing the range of combinations of spectral efficiency (or, equivalently, M-‐QAM format) and symbol rate possible with SPIRIT devices (shaded area).

Figure 3-‐2 quantifies the theoretical transmission performance (in terms of the capacity-‐reach product) as a function of M-‐QAM format [16]. Clearly, the format(s) chosen must be tailored to the application: In ULH links it will be necessary to keep the modulation order low (e.g. DP-‐QPSK), in order to maximize the reach. Metro/access links, on the other hand, where reach can be sacrificed, higher bandwidth efficiency can be achieved by using DP-‐16-‐QAM and beyond.

SPIRIT should account for the current trends in research and development of coherent optical systems, as well as standardization body efforts, in order to select the formats to be targeted. One of the strongest candidates for the 400G standard is dual-‐carrier DP-‐16QAM at 28/32 Gbaud, which should be supported [17]. Standardization for 1T is further away, and SPIRIT should therefore explore a range of possible formats on multiple wavelengths. In order to achieve realistic transmission reaches while at the same time achieving high spectral efficiencies, formats up to DP-‐64-‐QAM are targeted (Table 3-‐1 lists the likely modulation formats and how many carriers could be used to achieve 100G, 400G and 1T standards).


Figure 3-‐2: Capacity-‐Reach product vs. Bandwidth Efficiency (modulation format).

Table 3-‐1: Possible modulation formats to be targeted for generation of current and prospective telecom standards, with one or multiple wavelengths.

Number of optical carriers/wavelengths

Standard 1 2 3-‐4 4-‐5 8-‐10

100G DP-‐QPSK

28/32 GBaud

400G DP-‐16-‐QAM 28/32 GBaud

DP-‐QPSK

28/32 GBaud

1T DP-‐64-‐QAM 28/32 GBaud

DP-‐16-‐QAM 28/32 GBaud

DP-‐QPSK 28/32 GBaud

3.2.2 Multi-‐Carrier/Superchannel Generation

SPIRIT transceivers should support both Orthogonal Frequency Division Multiplexing (OFDM), as well as Nyquist WDM for multi-‐carrier/superchannel generation. The superchannel structures must be selected in order to comply with the network scenarios highlighted. In both cases, the modulation formats and number of carriers to be supported should be determined after theoretical and experimental investigation, taking into account the constraints imposed by the resolution of the multi-‐level functionality of the developed transmitter.


OFDM and Nyquist WDM may be suitable for networks based on a flex-‐grid infrastructure, but may be troublesome for use in 50 Ghz fixed-‐grid deployed networks. As an alternative, Ericsson has pioneered a new superchannel approach called ‘Time-‐Frequency Packing’ [18] which is an innovative and highly spectral-‐efficient implementation of the Faster-‐than-‐Nyquist paradigm. The subcarriers need not be orthogonal, increasing superchannel flexibility in terms of channel spacing and generation. Furthermore, the modulation format used is QPSK which is simple and robust. High spectral efficiency is obtained by strong filtering and spectral shaping at the transmitter, in order to space the subcarriers closer than the Nyquist paradigm: This introduces controlled ISI that is cleared at the receiver by appropriate DSP based on channel shortening and turbo equalization techniques. This is in agreement with the Shannon theory, which postulates that the spectral efficiency of a communication system can be improved by giving up the orthogonality condition, at least when low-‐order constellations are considered.

This technique also enables working at high baud rates, with low electrical analog bandwidth requirements (due to narrow filtering). The Frequency Packing approach can be adapted to fit both the flex-‐grid and fixed 50GHz grid networks, thanks to the tuning flexibility of the subcarriers.

Figure 3-‐3: 16-‐QAM and Frequency Packing spectra in fixed and flex-‐grid implementations.

Figure 3-‐3 shows the Frequency Packing spectrum in both fixed-‐ and flex-‐grid cases, and it is compared to the 16-‐QAM option. The spectral efficiency is about the same as 16-‐QAM, the latter requiring fewer carriers, but achieving worse performance in terms of reach, due to the poor OSNR tolerance of the 16-‐QAM format.


Frequency Packing can be a valid alternative selectable by the SPIRIT transceiver to transport 400G, as opposed to the currently demonstrated Dual-‐Carrier DP-‐16-‐QAM: Four QPSK sub-‐carriers in two 50 GHz slots can be employed, with an expected back to back OSNR performance of 13.5 dB. Furthermore the DAC functionality of the SPIRIT transmitter, as well as its linearity, can enable better signal shaping at the transmitter, thus improving Frequency Packing performance.

Typically, Frequency Packing is operated at a fixed baud-‐rate and the FEC rate is adjusted to trade off spectral efficiency with reach. The SPIRIT transceiver, by means of the SDN controller, can then select between M-‐QAM formats, and in addition configure to Frequency Packing when reach and high spectral efficiency are necessary, adjusting the FEC to optimize the transmission: Number of subcarriers involved is then also traded-‐off.

Figure 3-‐4 shows the spectral efficiency vs. OSNR required to transport 1 TB net rate: 7 bits/s/Hz can in principle be obtained. The various points of the plot correspond to different FEC overhead.

Figure 3-‐4: Spectral Occupancy and Spectral Efficiency vs. OSNR required for 1 Tb/s.

It is important for the SPIRIT transceiver to have flexibility both in the constellation space and FEC-‐rate space. SPIRIT DSP will implement both equalization techniques and FEC. It is important to design these blocks in order to be able to switch on and off parts of the digital processing according to system needs, thus enabling forms of cognitive power saving. For example, when the light path has a high margin, hard-‐decision FEC can be used instead of soft-‐decision FEC, or the number of soft-‐decision FEC iterations can be lowered. Chromatic dispersion compensation should also be selectable. The more modular the DSP, the easier it will be to control the power consumption of its constituent parts.


3.2.3 Software-‐Defined Operation

The SPIRIT transceiver flexibility in terms of spectral occupancy and data rate provides optical networks with new optimization operations as well as protection schemes. The following scenarios should be addressed:

! Distance-‐adaptive modulation: The transceiver shall enable the capability to adjust its modulation format and FEC overhead, depending on the reach of the lightpath. Trading off spectral efficiency with reach will improve network utilization. A shorter path may be served by a high level constellation format saving spectrum for other traffic. Alternativley, FEC can be traded off with payload if no additional spectrum is available for a given reach. This flexibility will be managed by the Transport-‐SDN controller.

! Sub-‐Rate Protection: A new protection scheme shall be enabled by the SPIRIT flexible transceiver. When no-‐protection path can be found by standard protection schemes due to reach or spectral constrains, the rate of the protected traffic is reduced, losing part of the traffic (possibly the lowest priority one), but still being able to protect the relevant traffic. Sub-‐rate protection may be achieved by increasing FEC, reducing baud rate, lowering the level of modulation format, or by slicing some of the subcarriers of the superchannel.

! Network Monitoring: SDN functionalities require monitoring of the network status to select the proper configuration. The coherent receiver enables physical layer parameter monitoring. CD and PMD monitoring techniques are well-‐known in the literature, while OSNR and Non-‐Linearity monitoring is still troublesome. Furthermore, techniques to get local information from end-‐to-‐end information are required: In fact, a coherent receiver gives estimates over the whole link, and not on a span-‐by-‐span basis. By combining information of different end-‐to-‐end paths, it is possible to derive local information to be used for new path feasibility and assessment (e.g. network kriging). Distributed monitoring techniques may be investigated to minimize the paths probing. An accurate assessment of a lightpath status enables SDN optimizations at the network, as well as the transceiver level.

3.3 Test Cases

3.3.1 Laboratory Testing at Ericsson

The SPIRIT prototype’s performance will be assessed considering the network scenarios described above, focusing on metro/core networks. It is suggested that a lab set-‐up be employed, emulating a small meshed network (Figure 3-‐5) with real fiber and attenuators. One of the spans of the network is replaced by a recirculating loop so that arbitrary distances can be covered for many network lightpaths. This way, distance-‐adaptive modulation and sub-‐rate protection can be emulated, as well as other flexible reconfigurations. The node switches (ROADMs) can be controlled by the SDN controller.


A traditional multi-‐span point-‐to-‐point ULH link can also be set up especially for testing with real commercial equipment, as shown in Figure 3-‐6. Signals generated by the SPIRIT transceiver will be transmitted along with traffic from commercial transponders by means of a wavelength-‐selective switch (WSS), and propagated over a physical link.

Figure 3-‐5: Meshed network topology laboratory setup for performance evaluation of the SPIRIT transceiver.

Figure 3-‐6: Point-‐to-‐point link for SPIRIT transceiver validation.


3.3.1.1 The Ericsson SPO Packet/optical Transport Platform: System Overview

SPIRIT devices will be tested in Ericsson’s SPO product family, a packet optical integrated platform with flexible DWDM capabilities for core and metro applications. It supports a maximum of 96 channels in the C-‐band on a 50GHz channel grid as well as flex grid. 10G and 100G WDM interfaces are available. 100G is based on best in class coherent technology. Further general information on the product is available at the Ericsson web-‐site6.

Figure 3-‐7: SPO main subrack.

The photonic infrastructure is implemented in a unit called Photonic Attachment Unit (PAU) which can be configured to operate as an Optical Terminal (OTA), Optical Line Amplifier (OLA) or RROADM (see Figure 3-‐8). This unit is a separate subrack that can be used in any network node as standalone network element, or in conjunction with the main POTP (Packet Optical Transport Platform) subrack which houses the transponders, muxponders, packet card, OTN units, etc.

Figure 3-‐8: SPO Photonic Attachment Units (PAU). 6 http://www.ericsson.com/us/ourportfolio/products/spo-‐1400-‐family


3.3.1.2 Multiplexing and de-‐multiplexing

SPO has a wide range of multiplexing options ranging from thin-‐film filters combining a pair of channels (2 skip 0 filters), to 48 channel 100GHz-‐multiplexers based on AWG. The latter, when combined with a group inter-‐leaver units (GIU), provide the most efficient method to multiplex and de-‐multiplex 96 channels on a 50GHz grid.

Additionally, SPO supports meshed network topologies with a range of Wavelength Selective Switch (WSS) solutions to enable Reconfigurable Optical Add-‐Drop Multiplexer (ROADM) nodes (see Table 3-‐2). Flex-‐grid-‐ready WSSs are also available with SPO.

Table 3-‐2: SPO RROADM configurations.

RROADM type 3 dB BW (GHz)

2 ways RROADM version house a 2x1 WSS -‐

4 ways RROADM version house a 4x1 WSS 32

9 ways RROADM version house a 9x1 WSS 35

9 ways RROAD Flexgrid (N slices) 12.5*N-‐15

3.3.1.3 Optical amplifiers

SPO has a range of EDFA amplifier options with varying operating gain to cover different fiber span lengths. A single-‐stage amplifier (SSA) with variable gain and output power, but no mid-‐stage access for Dispersion Compensating Modules (DCMs), and a dual-‐stage amplifier (DSA) with up to 10.5dB loss budget for DCMs are available. Each of these EDFAs has an embedded Variable Optical Attenuator (VOA) to allow for deployment on a range of spans with different losses, and to compensate for variation of span attenuation over the lifetime of the system.

In the DSA, the first stage contains the embedded VOA and operates with a variable gain, such that its output power is significantly lower than that of the second stage, to suppress any nonlinear effects in the DCF. The SPO product family also provides a Raman amplification solution: A 700mW pump power capable of 14.5 dB gain on G.652 fibers.The EDFA parameters of the SSA and DSA modules are summarized in Table 3-‐3 and Table 3-‐4, respectively:

Table 3-‐3: EDFA parameters of SSA modules.

Amplifier type SSA-‐20/20 SSA-‐27/20

Max power dBm 20.5 20.5

Gain range dB 15-‐25 22-‐32

NF @ G min dB 8.4 6.2

NF @ G nom dB 6 5.3

NF @ G max dB 5.4 5.3


Table 3-‐4: EDFA parameters of DSA modules.

Amplifier type DSA-‐20/20 DSA-‐27/20

Max power dBm 20.5 20.5

Gain range dB 15-‐25 22-‐32

NF @ G min dB 10.6 7.2

NF @ G nom dB 7.6 6.1

NF @ G max dB 6.5 5.7

3.3.1.4 Dispersion Compensation Modules

SPO allows for the introduction of DCMs to provide dispersion compensation for systems operating at 10Gbit/s and 40G. DCMs are available for SMF, TW-‐RS and eLEAF fibre types with a range of lengths. SMF DCMs are available up to a maximum length of 150km with a granularity of 10km. TW-‐RS and eLEAF modules are available with maximum lengths of 240km and 200km, respectively, both with granularities of 40km.

Dispersion compensating fibre parameters are given in Table 3-‐5:

Table 3-‐5: EDFA parameters of DSA modules.

Fibre Dispersion Dispersion

slope Dispersion curvature

Loss Effective Area

ps/nm/km ps/nm2/km ps/nm2/km dB/km μm2

SMF -‐113.7 -‐0.41 0.0 0.47 19

TW-‐RS -‐150 -‐1.41 -‐0.007 0.65 13

eLEAF -‐110 -‐2.375 -‐0.04 0.8 13

3.3.2 Laboratory Testing at ICCS/NTUA A high-‐capacity transmission and coherent reception test-‐bed will be implemented at ICCS/NTUA and will be used in the evaluation of the SPIRIT transceivers. This will support testing of dual-‐polarization QAM signals at symbol rates up to 32GBaud. Two options will be pursued for generating the high-‐speed binary data signals needed for multi-‐level QAM operation: (a) Using FPGA development boards equipped with serial transceivers capable of up to 28Gbit/s operation (Altera Stratix V GT and/or Xilinx Virtex 7), and (b) Using high-‐speed pulse pattern generator (PPG) outputs. In the case of (a), the symbol rate possible is limited to 28 GBaud, while case (b) allows much higher rates. The use of an FPGA, however, enables programmable, flexible operation and transmitter-‐side DSP, whereas available PPGs at these speeds only provide PRBS outputs. An option for overcoming this rate limitation of the FPGA is the use of commercial 2:1 or 4:1 RF multiplexers.


The test signals will be transmitted through a recirculating fiber loop, in order to emulate propagation through multiple spans, and several hundreds of kilometres (mimicking typical metro/core network scenarios). The signals will then be received and digitized with a 33 GHz, 80 GSa/s real-‐time oscilloscope for further offline DSP processing. ICCS/NTUA will utilize its existing expertise and suite of DSP algorithms, as well as those developed during the course of the project, and required specifically by SPIRIT for modulation/demodulation of the high-‐order, single/multi-‐carrier M-‐QAM or arbitrary constellations that will be employed.

SPIRIT devices will be tested for suitability in future software-‐defined flexible optical networks, including dynamic adjustment of the baudrate and QAM format, performance monitoring in DSP and determination of Quality of Service. System parameters that will be evaluated will include OSNR, transmission reach, extinction ratio and dispersion, polarization crosstalk and BER for variable modulation formats. Back-‐to-‐back, as well as transmission performance will be assessed, considering the trade-‐off between modulation type and reach.

3.3.3 Field Trial Testing

The SPIRIT transceiver will be tested in field trials in order to investigate its performance under real transmission conditions and identify performance trade-‐offs. The primary objective of the field trials is to test the provided optical platform in a real DWDM system configuration, focusing on interoperability of existing 10, 40 and 100 Gbit/s channels with high capacity channels generated by SPIRIT devices. This will be done by inserting them into a DWDM system installed in the regional OTE network, employing G.652 fiber. This network will be used for testing the transceiver unit in a deployed plant environment. The interoperability trial will be crucial to clearly evaluate network migration scenarios and share the benefits of the new technology, as well provide clearer ideas of potentiality and limits.

The channels provided by the developed optical platform will be tested under real impairments (optical noise from amplifiers, CD, PMD, non-‐linear interaction, reflections, filter cascading distortion, high insertion loss for optical splices and connectors).


4. Conclusions

In this deliverable, we have defined the major application scenarios of interest to SPIRIT; we identified the application-‐driven network requirements mainly in terms of bitrate and latency and described the reference network architecture of OTE, which will be considered in the evaluation and demonstration of the functionality of the SPIRIT component.

In particular, as discussed in Section 2, the increased Internet usage due to a multitude of factors e.g. emergence of new applications such as cloud gaming, increasing penetration of broadband (fixed and mobile), increasing number of mobile devices and M2M, etc., coupled with faster speeds are accelerating recent trends in Internet traffic volumes, as well as they are inducing new and different behaviour traffic patterns. Moreover, consumers’ increased demand for services, information and entertainment "anytime, anywhere", is putting pressure not only on service providers, but also to components vendors for constant innovation and specifically, for high-‐capacity optical components that will support flexibility, dynamicity and programmability such as the SPIRIT transceiver.

Major application scenarios described in Section 2, include the flexible management of fixed and mobile traffic in the core/metro network of network operators, the support of bandwidth-‐intensive applications, including both end-‐user application as well as inter-‐data center services, and the support of service and network virtualization,

Furthermore, the requirements from a system perspective have been presented in Section 3, and appropriate test cases for performance evaluation of SPIRIT’s devices have been identified. Operation in a fixed-‐grid WDM environment is envisaged, both in a mixed coherent/legacy traffic scenario, as well in an all-‐coherent channel setting. Moreover, the requirement for programmable and flexible-‐format operation will ensure compatibility with future elastic optical networks, with an emphasis on the emerging flex-‐grid standard.

Evaluation of SPIRIT’s devices will take place both in the laboratory, as well as in a field trial with deployed fiber and co-‐propagating traffic from commercial transponders. The test cases identified aim to evaluate component performance, in addition to validating SPIRIT’s targeted system concepts in realistic network scenarios.


5. List of Figures Figure 2-‐1: Fixed broadband coverage; end of 2012. (Source: Point Topic) ................................... 9

Figure 2-‐2: NGA coverage; end of 2012. (Source: Point Topic) ..................................................... 10

Figure 2-‐3: Fixed broadband penetration; 2004-‐2013. (Source: Communications Committee)... 10

Figure 2-‐4: Fixed broadband subscription per 100 inhabitants; EU & OECD; July 2012. (Source: Communications Committee and OECD [3]) ................................................................................. 11

Figure 2-‐5: HSPA coverage; end of 2012. (Source: Point Topic).................................................... 12

Figure 2-‐6: LTE coverage; end of 2012. (Source: Point Topic)....................................................... 12

Figure 2-‐7: Mobile broadband penetration at EU level; 2009-‐2013. (Source: Communications Committee) ................................................................................................................................... 13

Figure 2-‐8: Mobile IP traffic; 2013-‐2018. (Source: Cisco VNI Mobile, 2014) ................................. 16

Figure 2-‐9: Mobile video traffic; 2013-‐2018. (Source: Cisco VNI Mobile, 2014) ........................... 16

Figure 2-‐10: Personal content locker traffic growth; 2012-‐2017. (Source: Cisco Global Cloud Index, 2013)................................................................................................................................... 18

Figure 2-‐11: Support of high-‐bandwidth consuming applications with heterogeneous QoS requirements for a multitude of users with different access devices........................................... 21

Figure 2-‐12: Support of high-‐bandwidth consuming applications with heterogeneous QoS requirements for a multitude of users with different access devices........................................... 22

Figure 2-‐13: Support of service and network virtualization; flexible and dynamic management of data center to user and inter-‐data center communication for services with heterogeneous QoS requirements for a multitude of users. ......................................................................................... 23

Figure 2-‐14: IP network of OTE. .................................................................................................... 26

Figure 2-‐15: Optical core network of OTE. .................................................................................... 26

Figure 2-‐16: Part of an Ethernet domain of OTE. .......................................................................... 27

Figure 3-‐1: Showing the range of combinations of spectral efficiency (or, equivalently, M-‐QAM format) and symbol rate possible with SPIRIT devices (shaded area)........................................... 30

Figure 3-‐2: Capacity-‐Reach product vs. Bandwidth Efficiency (modulation format). ................... 31

Figure 3-‐3: 16-‐QAM and Frequency Packing spectra in fixed and flex-‐grid implementations. ..... 32

Figure 3-‐4: Spectral Occupancy and Spectral Efficiency vs. OSNR required for 1 Tb/s. ................ 33

Figure 3-‐5: Meshed network topology laboratory setup for performance evaluation of the SPIRIT transceiver..................................................................................................................................... 35

Figure 3-‐6: Point-‐to-‐point link for SPIRIT transceiver validation. .................................................. 35

Figure 3-‐7: SPO main subrack........................................................................................................ 36

Figure 3-‐8: SPO Photonic Attachment Units (PAU). ...................................................................... 36


6. List of tables Table 2-‐1: Global IP traffic; 2012-‐2017. (Source: Cisco VNI, 2013) ............................................... 15

Table 2-‐2: Metro and Long-‐Haul traffic; 2012-‐2017. (Source: Cisco VNI, 2013) ........................... 15

Table 2-‐3: Global data center traffic; 2012-‐2017. (Source: Cisco Global Cloud Index, 2013) ....... 17

Table 2-‐4: Bitrate of HTTP video streaming. ................................................................................. 24

Table 3-‐1: Possible modulation formats to be targeted for generation of current and prospective telecom standards, with one or multiple wavelengths................................................................. 31

Table 3-‐2: SPO RROADM configurations. ...................................................................................... 37

Table 3-‐3: EDFA parameters of SSA modules. ............................................................................... 37

Table 3-‐4: EDFA parameters of DSA modules. .............................................................................. 38

Table 3-‐5: EDFA parameters of DSA modules. .............................................................................. 38


7. Abbreviations

BoD Bandwidth-‐on-‐Demand

CAGR Compound Annual Growth Rate

CDN Content Delivery Network

DA Digital Agenda

DOCSIS Data over Cable Service Interface Specification

FTTB Fibre-‐To-‐The-‐Building

FTTH Fibre-‐To-‐The-‐Home

FTTP Fibre-‐To-‐The-‐Premises

GaV Game-‐as-‐Video

HSPA High Speed Packet Access

ISP Internet Service Provider

LTE Long Term Evolution

M2M Machine-‐to-‐Machine

MNO Mobile Network Operator

MVNO Mobile Virtual Network Operator

NGA Next Generation Access

OECD Organization for Economic Co-‐operation and Development

OFDM Orthogonal Frequency Division Multiplexing

SIM Subscriber Identity Module

VDSL Very-‐high-‐bit-‐rate Digital Subscriber Line

VoD Video-‐on-‐Demand

VPN Virtual Private Network


8. References [1] www.spirit-‐project.eu

[2] Digital Agenda Scoreboard 2013 – Chapter 2: Broadband markets, http://ec.europa.eu/digital-‐agenda/sites/digital-‐agenda/files/DAE%20SCOREBOARD%202013%20-‐%202-‐BROADBAND%20MARKETS%20_0.pdf

[3] Organization for Economic Co-‐operation and Development: http://www.oecd.org/

[4] Digital Agenda Scoreboard 2013 – Chapter 5: Online content, http://ec.europa.eu/digital-‐agenda/sites/digital-‐agenda/files/DAE%20SCOREBOARD%202013%20-‐%205-‐ONLINE%20CONTENT_0.pdf

[5] McKeown, Nick, Tom Anderson, Hari Balakrishnan, Guru Parulkar, Larry Peterson, Jennifer Rexford, Scott Shenker, and Jonathan Turner. "OpenFlow: enabling innovation in campus networks." ACM SIGCOMM Computer Communication Review 38, no. 2 (2008): 69-‐74.

[6] Chiosi, M., Clarke, D., Willis, P., Reid, A., Feger, J., Bugenhagen, M., ... & Sen, P. (2012, October). Network functions virtualisation: An introduction, benefits, enablers, challenges and call for action. In SDN and OpenFlow World Congress.

[7] Cisco Visual Networking Index: Forecast and Methodology, 2012 – 2017 (white paper): http://www.cisco.com/en/US/solutions/collateral/ns341/ns525/ns537/ns705/ns827/white_paper_c11-‐481360.pdf

[8] Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2013-‐2018, white paper, February 5th, 2014: http://www.cisco.com/en/US/solutions/collateral/ns341/ns525/ns537/ns705/ns827/white_paper_c11-‐520862.pdf

[9] Cisco Global Cloud Index: Forecast and Methodology, 2012-‐2017, white paper, 2013: http://www.cisco.com/en/US/solutions/collateral/ns341/ns525/ns537/ns705/ns1175/Cloud_Index_White_Paper.pdf

[10] Cisco Visual Networking Index: The Zettabyte Era – Trends and Analysis, May 2013: http://www.cisco.com/en/US/solutions/collateral/ns341/ns525/ns537/ns705/ns827/VNI_Hyperconnectivity_WP.pdf

[11] Gerber, Alexandre, and Robert Doverspike (AT&T). "Traffic types and growth in backbone networks." Optical Fiber Communication Conference and Exposition (OFC/NFOEC), 2011 and the National Fiber Optic Engineers Conference. IEEE, 2011.

[12] Bohn, Roger E., and James E. Short. How Much Information?: 2009 Report on American Consumers. University of California, San Diego, Global Information Industry Center, 2009.

[13] Sandvine: Global Internet Phenomena Report – 2H 2013: https://www.sandvine.com/downloads/general/global-‐internet-‐phenomena/2013/2h-‐2013-‐global-‐internet-‐phenomena-‐report.pdf

[14] Hemmati, Mahdi, Abbas Javadtalab, Ali Asghar Nazari Shirehjini, Shervin Shirmohammadi, and Tarik Arici. "Game as video: bit rate reduction through adaptive object encoding."


In Proceeding of the 23rd ACM Workshop on Network and Operating Systems Support for Digital Audio and Video, pp. 7-‐12. ACM, 2013.

[15] Choy, Sharon, Bernard Wong, Gwendal Simon, and Catherine Rosenberg. "The brewing storm in cloud gaming: A measurement study on cloud to end-‐user latency." In Proceedings of the 11th Annual Workshop on Network and Systems Support for Games, p. 2. IEEE Press, 2012.

[16] Kuang-‐Tsan Wu et al., “The Age of Optical Coherent Communication,” CLEO Technical Digest 2012, paper CF1F.1.

[17] “Path to 400G,” Fujitsu presentation (available online: http://www.fujitsu.com/downloads/TEL/fnc/whitepapers/Pathto400G.pdf).

[18] L. Poti et al., “Casting 1 Tb/s DP-‐QPSK Communication into 200 GHz Bandwidth,” ECOC Technical Digest 2012, paper P4.19.

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