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Author

E.-D. Schmidt

Other affiliations: Siemens, Nokia
Bio: E.-D. Schmidt is an academic researcher from Nokia Networks. The author has contributed to research in topics: Phase-shift keying & Optical performance monitoring. The author has an hindex of 14, co-authored 39 publications receiving 1028 citations. Previous affiliations of E.-D. Schmidt include Siemens & Nokia.

Papers
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Journal ArticleDOI
01 Jan 2008
TL;DR: In this paper, the use of a coherent digital receiver for compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard is discussed.
Abstract: We discuss the use of a coherent digital receiver for the compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard. We present experimental results on the transmission performance of 111 Gbit/s POLMUX-RZ-DQPSK. For a dense WDM setup with channels carrying 111 Gbit/s with a 50 GHz channel spacing (2.0 bits/s/Hz), we show the feasibility of 2375 km transmission. This is enabled through coherent detection which results in excellent noise performance, and subsequent electronic equalization which provides the high tolerance to polarization mode dispersion and chromatic dispersion (CD). Furthermore, we discuss the impact of sampling and digital signal processing with either 1 or 2 samples/bit. We show that when combined with low-pass electrical filtering, 1 sample/bit signal processing is sufficient to obtain a large tolerance towards CD. The proposed modulation and detection techniques enable 111 Gbit/s transmission that is directly compatible with the existing 10 Gbit/s infrastructure.

405 citations

Proceedings ArticleDOI
01 Nov 2013
TL;DR: Analysis of the EPC nodes and proposed mapping for these functions on four alternative deployment frameworks based on SDN and OpenFlow shows that functions, which involve high data packet processing such as tunneling, have more potential to be kept on the data-plane network element, i.e. an OpenFlow Switch.
Abstract: The recent initiative of Network Functions Virtualization (NFV) aims to deliver any data- plane processing or control-plane function in high volume data centers or network elements to decrease operational cost and increase deployment flexibility. In order to dynamically direct traffic flows between respective network elements, Software Defined Networking (SDN) can be seen as one enabler. In this paper, we focus on mobile core network nodes such as the MME, HSS, S- and P- Gateway as standardized for the LTE Evolved Packet Core (EPC). One straightforward solution for a virtualized EPC architecture would be to move all EPC network nodes completely into a data center and handle the data traffic via SDN-enabled switches. However, this solution would keep the conventional monolithic architecture unchanged. A possible split in the EPC functionality between a centralized data center and operator's transport network elements could be needed to provide the desired flexibility, performance and TCO reduction. Therefore, we have analyzed the EPC nodes and classified their functions according to their impact on data-plane and control-plane processing. We propose a mapping for these functions on four alternative deployment frameworks based on SDN and OpenFlow (OF). In addition, we investigate the current OF implementation's capability to realize basic core operations such as QoS, data classification, tunneling and charging. Our analysis shows that functions, which involve high data packet processing such as tunneling, have more potential to be kept on the data-plane network element, i.e. realized by an OpenFlow Switch. We argue for an enhanced OF network element NE+, which contains additional network functions next to the basic OpenFlow protocol.

157 citations

Proceedings ArticleDOI
22 Dec 2008
TL;DR: In this article, the feasibility of 100G overlaying existing 10G/40G commercial systems is demonstrated, showing that 100G can be achieved over a 50GHz grid over 1,040 km field fiber and two ROADMs.
Abstract: 111-Gb/s transmission combined with 2 times 43-Gb/s and 8 times 10.7-Gb/s on a 50-GHz grid over 1,040-km field fiber and two ROADMs is demonstrated, showing the feasibility of 100G overlaying existing 10G/40G commercial systems.

50 citations

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate transmission of a 111-Gb/s coherent polarization-multiplexed return-to-zero differential quadrature phase shift keying signal over 1040-km field-deployed fiber together with different types of neighboring channels, and with a cascade of 50-GHz reconfigerable optical add-drop multiplexers.
Abstract: We demonstrate transmission of a 111-Gb/s coherent polarization-multiplexed return-to-zero differential quadrature phase-shift keying signal over 1040-km field-deployed fiber together with different types of neighboring channels, and with a cascade of 50-GHz reconfigerable optical add-drop multiplexers. Our transmission experiment proves the feasibility of transmitting a 111-Gb/s phase-modulated channel with 10 times 10.7-Gb/s on-off keying neighboring channels on a 50-GHz grid, despite the presence of strong cross-phase modulation.

44 citations

Patent
05 Jul 2007
TL;DR: In this paper, a receiver for a quadrature-modulated signal, which can be divided into an inphase signal (I) and a quad rature signal (Q), is presented.
Abstract: The invention relates to a receiver for a quadrature-modulated signal, which can be divided into an inphase signal (I) and a quadrature signal (Q). The inphase signal (I) is fed to first and third equalizers (EZl, EZ3), and the quadrature signal (Q) is fed to second and fourth equalizers (EZ2, EZ4), wherein the first and second equalizers (EZl, EZ2) each perform a first equalization of the respective signal. An output of the first equalizer (EZl) is connected to a second input of the fourth equalizer (EZ4), which, by means of a second equalization of the quadrature signal (Q), transmits an equalized quadrature signal (Q2) as a function of the previously fed equalized inphase signal (II) of the first equalizer (EZl). An output of the second equalizer (EZ2) is connected to the second input of the third equalizer (EZ3), which, by means of a second equalization of the inphase signal (I), transmits an equalized inphase signal (12) as a function of the previously fed equalized quadrature signal (Ql) of the second equalizer (EZ2).

38 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors survey the state-of-the-art in NFV and identify promising research directions in this area, and also overview key NFV projects, standardization efforts, early implementations, use cases, and commercial products.
Abstract: Network function virtualization (NFV) has drawn significant attention from both industry and academia as an important shift in telecommunication service provisioning. By decoupling network functions (NFs) from the physical devices on which they run, NFV has the potential to lead to significant reductions in operating expenses (OPEX) and capital expenses (CAPEX) and facilitate the deployment of new services with increased agility and faster time-to-value. The NFV paradigm is still in its infancy and there is a large spectrum of opportunities for the research community to develop new architectures, systems and applications, and to evaluate alternatives and trade-offs in developing technologies for its successful deployment. In this paper, after discussing NFV and its relationship with complementary fields of software defined networking (SDN) and cloud computing, we survey the state-of-the-art in NFV, and identify promising research directions in this area. We also overview key NFV projects, standardization efforts, early implementations, use cases, and commercial products.

1,634 citations

Journal ArticleDOI
TL;DR: Using the analytical solution an upper bound on the number of taps required to compensate chromatic dispersion is obtained, with simulation revealing an improved bound of 2.2 taps per 1000ps/nm for 10.7GBaud data.
Abstract: Digital filters underpin the performance of coherent optical receivers which exploit digital signal processing (DSP) to mitigate transmission impairments. We outline the principles of such receivers and review our experimental investigations into compensation of polarization mode dispersion. We then consider the details of the digital filtering employed and present an analytical solution to the design of a chromatic dispersion compensating filter. Using the analytical solution an upper bound on the number of taps required to compensate chromatic dispersion is obtained, with simulation revealing an improved bound of 2.2 taps per 1000ps/nm for 10.7GBaud data. Finally the principles of digital polarization tracking are outlined and through simulation, it is demonstrated that 100krad/s polarization rotations could be tracked using DSP with a clock frequency of less than 500MHz.

1,201 citations

Journal ArticleDOI
TL;DR: In this article, a theoretical analysis of the dual-polarization constant modulus algorithm is presented, where the control surfaces several different equalizer algorithms are derived, including the decision-directed, trained, and the radially directed equalizer for both polarization division multiplexed quadriphase shift keyed (PDM-QPSK) and 16 level quadrature amplitude modulation (PDm-16-QAM).
Abstract: Digital coherent receivers have caused a revolution in the design of optical transmission systems, due to the subsystems and algorithms embedded within such a receiver. After giving a high-level overview of the subsystems, the optical front end, the analog-to-digital converter (ADC) and the digital signal processing (DSP) algorithms, which relax the tolerances on these subsystems are discussed. Attention is then turned to the compensation of transmission impairments, both static and dynamic. The discussion of dynamic-channel equalization, which forms a significant part of the paper, includes a theoretical analysis of the dual-polarization constant modulus algorithm, where the control surfaces several different equalizer algorithms are derived, including the constant modulus, decision-directed, trained, and the radially directed equalizer for both polarization division multiplexed quadriphase shift keyed (PDM-QPSK) and 16 level quadrature amplitude modulation (PDM-16-QAM). Synchronization algorithms employed to recover the timing and carrier phase information are then examined, after which the data may be recovered. The paper concludes with a discussion of the challenges for future coherent optical transmission systems.

772 citations

Proceedings ArticleDOI
24 Aug 2015
TL;DR: A thorough study of the NFV location problem is performed, it is shown that it introduces a new type of optimization problems, and near optimal approximation algorithms guaranteeing a placement with theoretically proven performance are provided.
Abstract: Network Function Virtualization (NFV) is a new networking paradigm where network functions are executed on commodity servers located in small cloud nodes distributed across the network, and where software defined mechanisms are used to control the network flows. This paradigm is a major turning point in the evolution of networking, as it introduces high expectations for enhanced economical network services, as well as major technical challenges. In this paper, we address one of the main technical challenges in this domain: the actual placement of the virtual functions within the physical network. This placement has a critical impact on the performance of the network, as well as on its reliability and operation cost. We perform a thorough study of the NFV location problem, show that it introduces a new type of optimization problems, and provide near optimal approximation algorithms guaranteeing a placement with theoretically proven performance. The performance of the solution is evaluated with respect to two measures: the distance cost between the clients and the virtual functions by which they are served, as well as the setup costs of these functions. We provide bi-criteria solutions reaching constant approximation factors with respect to the overall performance, and adhering to the capacity constraints of the networking infrastructure by a constant factor as well. Finally, using extensive simulations, we show that the proposed algorithms perform well in many realistic scenarios.

509 citations

Journal ArticleDOI
Steven Gringeri1, B. Basch1, Vishnu Shukla1, R. Egorov1, Tiejun J. Xia1 
TL;DR: The architectures and various ROADM implementations including colorless, directionless, and contentionless add/drop structures are presented and the effect of scaling bit rates beyond 100 Gb/s onROADM architectures is reviewed including providing variable channel bandwidth depending on bit rate.
Abstract: Flexibility to support mesh topologies, dynamic capacity allocation, and automated network control and light path setup are key elements in the design of next-generation optical transport networks. To realize these capabilities, reconfigurable optical add/drop multiplexers with dynamic add/drop structures, embedded control planes, and lightpath characterization are required. This article presents the architectures and various ROADM implementations including colorless, directionless, and contentionless add/drop structures. The effect of scaling bit rates beyond 100 Gb/s on ROADM architectures is reviewed including providing variable channel bandwidth depending on bit rate. Automated provisioning and restoration using the GMPLS control plane and optical measurement approaches for lightpaths are also discussed.

484 citations