[Show abstract][Hide abstract] ABSTRACT: A mode-unbundled reconfigurable add/drop multiplexer (ROADM), composed of a fiber-based mode-multiplexer/demultiplexer pair and a multiport microelectromechanical systems switch, is proposed and experimentally characterized for higher data granularity in mode-division multiplexing (MDM) deployment of future metro area networks (MAN). For enabling mode-unbundling transmission, crosstalk reduction through bidirectional mode assignment is adopted. Finally, a 62-km MDM-MAN ring, composed of two mode-unbundled ROADMs and few-mode fiber spans, is experimentally demonstrated by taking advantage of bidirectionally mode assigned 40 Gb/s, 16-QAM signals.
No preview · Article · Dec 2015 · Journal of Lightwave Technology
[Show abstract][Hide abstract] ABSTRACT: This paper considers a novel virtual optical circuit switching (VOCS) scheme for data center networks where short flows are transmitted via optical packet switching (OPS), while long flows with reliability requirement are transmitted via VOCS. VOCS preserves the advantage of optical circuit switching (OCS) for reliable communication, while it overcomes the disadvantage of OCS in terms of low link utilization. In the VOCS/OPS scheme, idle periods of the virtual circuits can be used by OPS, which thus enhances the overall performance. Simulations on a six-dimensional torus topology data center network with 4096 (=4(Formula presented.)) nodes are conducted for the performance evaluation. We have observed that, compared to OCS, VOCS has much less adverse impact on the performance of OPS. Furthermore, quite a large number (i.e., 2048) of virtual circuits can be set up with little affect on the OPS performance.
Full-text · Article · Nov 2015 · Photonic Network Communications
[Show abstract][Hide abstract] ABSTRACT: A deployment scenario of mode division multiplexing (MDM) in metro ring network using few-mode fibers (FMFs) is presented. A novel mode-unbundled ROADM demonstrates the finest data granularity, and bi-directional transmission can circumvent the MIMO DSP.
[Show abstract][Hide abstract] ABSTRACT: Modeling and performance analysis of a data center network (DCN) combining optical packet switching (OPS) and agile optical circuit switching (OCS) in a unified platform are presented. Hybrid optoelectronic packet routers which combine optical switching fabric and electronic buffers are used, supporting 100 Gbit/s (25 Gbit/s×4 wavelengths) optical packets. OCS transmission is implemented by a novel “express path,” (ExP) an instant wavelength path on demand, which enables certain flows following the ExP with no packet contention, whereas ordinary OPS packets are switched with a deflection routing algorithm and buffering for contention resolution. This architecture can support OCS for large and reliability-sensitive data transferring and OPS for latency-sensitive applications. The performance of the network is investigated via numerical simulations of top-of-rack switch (ToR)-to-ToR traffic in an 𝑁-dimensional (up to 4096 node) torus topology. We have made the following observations: 1) torus topology results in high throughput and can be scaled out by increasing the dimension; 2) contention resolution between OPS and agile OCS is needed and our proposed strategies enhance the overall performance; and 3) in a lightly to moderately loaded case of OPS traffic, more than 100 ExPs can be supported simultaneously with acceptable affect on OPS.
No preview · Article · Nov 2015 · Journal of Optical Communications and Networking
[Show abstract][Hide abstract] ABSTRACT: Mode-division multiplexing (MDM) over wavelength division multiplexed (WDM) networks is studied, particularly for the deployment of metro area networks (MAN) using two-mode fibers (TMF). Full C-band differential mode group delay (DMGD)-compensated TMF links are adopted for decreasing the computational complexity of real-time multiple-input multiple-output (MIMO) signal processing. The effect of modal crosstalk to the maximum delay spread of the channel is validated through numerical simulations. Finally, the 2×2 MIMO channel state information (CSI) of a 102.6-km DMGD-compensated TMF link is experimentally estimated for mode path provisioning based upon routing and mode assignment (RMA) in MDM networks. The results confirm close-to-zero total DMGD value over the entire C-band.
No preview · Article · Oct 2015 · Optics Communications
[Show abstract][Hide abstract] ABSTRACT: W-band RoF transmission system with converged MIMO DSP for compensating signal impairments both in optical fiber and free-space is presented, particularly focusing on MDM transmission in a low differential mode group delay two-mode fiber link.
[Show abstract][Hide abstract] ABSTRACT: This paper deals with massive number of optical code (OC) label generation and recognition for scalable optical packet switching (OPS) networks. In order to expand the system scalability of code label processing, we develop a record port count 128 x 128 optical encoder/decoder (E/D) and propose a novel three-dimensional (3-D) optical label combining code label with wavelength and polarization. In the experiment, we conduct a proof-of-concept demonstration of 4-code x 2-wavelength x 2-polarization and validate that the 3-D labeling scheme can consequently increase the available number of code label up to more than 1,000 labels. Real-time labeling performance using a field programmable gate array (FPGA)-based processor and crosstalk influence at an optical switch are also experimentally evaluated.
[Show abstract][Hide abstract] ABSTRACT: A torus-topology photonic data center network with smart flow control is presented, where optical packet switching (OPS), optical circuit switching (OCS), and virtual OCS (VOCS) schemes are all enabled on a unified hardware platform via the combination of hybrid optoelectronic routers (HOPR) and a centralized network controller. An upgraded HOPR is being developed with the goal of handling 100 Gbps optical packets with a high energy efficiency of 90 mW/Gbps and low latency of less than 100 ns. The architecture of HOPR and its enabling technologies are reviewed, including a label processor, optical switch, and optoelectronic shared buffer. We also explain the concept and operation mechanisms of both the data and control planes in the hybrid OPS/OCS/VOCS torus network. The performance of these three transmission modes is evaluated by numerical simulations for a network composed of 4096 HOPRs.
No preview · Article · Oct 2015 · Journal of Optical Communications and Networking
[Show abstract][Hide abstract] ABSTRACT: In OPS-based data center networks, setting up temporal OCS paths for high-reliability-required large data transmissions is preferred. However, inappropriate OCS path selection could severely affect the original OPS traffic, which is because OCS path may break the network topology and cause OPS packet circulations. We propose to hold bypassing routes for every link of the OCS path when it is established. Then, the OPS packets could bypass the OCS links by being deflected to the bypassing routes. Therefore, this method facilitates the coexistence of OCS in OPS-based data center networks. Simulations demonstrate the benefit achieved by our proposal compared to no-bypassing-route scenarios.
[Show abstract][Hide abstract] ABSTRACT: A novel mode-selective optical packet switching, based on mode-multiplexers/demultiplexers and multi-port optical micro-electro-mechanical systems (MEMS) switches, has been proposed and experimentally demonstrated. The experimental demonstration was performed using the LP<sub>01</sub>, LP<sub>11a</sub> and LP<sub>11b</sub> modes of a 30-km long mode-division multiplexed few-mode fiber link, utilizing 40 Gb/s, 16-QAM signals.
[Show abstract][Hide abstract] ABSTRACT: Packet switching offers better network resource utilization. Optical packet switching is the technology that challenges to perform high-speed header processing and switching. A novel mode-labeled optical packet switching without them, based on mode multiplexers/demultiplexers and multi-port optical micro-electromechanical systems (MEMS) switches, has been proposed and experimentally demonstrated. The experimental demonstration was performed using the LP01, LP11a and LP11b modes of a 30-km long mode division multiplexed few-mode fiber link, 16-QAM signals without serious signal impairments.
[Show abstract][Hide abstract] ABSTRACT: We present the performance of fixed-length, variable-capacity (FL-VC) packets in optical packet-switching (OPS) networks. We show how FL-VC achieves an effective balance between implementation feasibility and performance of the applications using the network. Focusing on metropolitan area networks and real-world file distributions, we also show that an adequate selection of packet duration leads to nearly optimal application throughput with respect to conventional variable-length, fixed-bit-rate packets (VL-FBR), and that this optimal packet duration is robust against changes in the workload. Finally, we show that a single fiber delay line per OPS switch managed by a first-fit scheduler can increase throughput to levels similar to those obtained by random access buffers.
No preview · Article · Jul 2015 · Journal of Optical Communications and Networking
[Show abstract][Hide abstract] ABSTRACT: A multi-domain optical infrastructure with end-to-end Ethernet transport capability can deliver Ethernet services over a large scale and provide a promising solution for inter data center networks (DCN) communication. The already existed metro and core networks should be evolved both in data plane and control plane towards to support the heterogeneous and dynamic Ethernet traffic environment.
In this paper, we report the work carried out in the ICT STRAUSS project to provide Ethernet connections for intra-DCN and inter-DCN over metro and core networks. The key technologies for intra- and inter- DCN communications are reported with experimental validation.
[Show abstract][Hide abstract] ABSTRACT: In this study, we demonstrate coherent OFDMA-PON uplink transmission experimentally using three optical network units including a 3-Gbaud real-time transmitter prototype. Cooperative digital signal processing at the ONUs and an optical line terminal enable no-guard-band subcarrier-based multiple access with free-running up to 100-kHz-linewidth external cavity lasers over a 40-km fiber link. In addition, we demonstrate the OFDMA-PON uplink with multiformatted and unequally-allocated subcarriers over up to 65-km link to verify the bandwidth flexibility of the proposed uplink. We then extend the experimental results to cases with >3 ONUs via numerical simulation.
No preview · Article · Apr 2015 · Journal of Lightwave Technology