An ultrafast 1 x M all-optical WDM packet-switched router based on the PPM header address

This paper presents an all-optical 1 x M WDM router architecture for packet routing at multiple wavelengths simultaneously, with no wavelength conversion modules. The packet header address adopted is based on the pulse position modulation (PPM) format, thus enabling the use of only a singlebitwise optical AND gate for fast header address correlation. It offers multicast as well as broadcast capabilities. It is shown that a high speed packet routing at 160 Gb/s can be achieved with a low channel crosstalk (CXT) of ~ -27 dB at a channel spacing of greater than 0.4 THz and a demultiplexer bandwidth of 500 GHz

1 x M packet-switched router based on the PPM header address for all-optical WDM networks

This paper presents an all-optical 1xM router architecture for simultaneous multiple-wavelength packet routing, without the need for wavelength conversion. The packet header address is based on the pulse position modulation (PPM) format, which allows the use of only a single-bitwise optical AND gate for fast packet header address correlation. The proposed scheme offers both multicast and broadcast capabilities. We’ve demonstrated a high speed packet routing at 160 Gb/s in simulation, with a low channel crosstalk (CXT) of ~ -27 dB with a channel spacing of > 0.4 THz and a demultiplexer bandwidth of 500 GHz. The output transfer function of the PPM header processing (PPM-HP) module is also investigated in this paper

All Optical Packet Processing in Optical Network

No Abstrac

Wireless Communication in Data Centers: A Survey

Data centers (DCs) is becoming increasingly an integral part of the computing infrastructures of most enterprises. Therefore, the concept of DC networks (DCNs) is receiving an increased attention in the network research community. Most DCNs deployed today can be classified as wired DCNs as copper and optical fiber cables are used for intra- and inter-rack connections in the network. Despite recent advances, wired DCNs face two inevitable problems; cabling complexity and hotspots. To address these problems, recent research works suggest the incorporation of wireless communication technology into DCNs. Wireless links can be used to either augment conventional wired DCNs, or to realize a pure wireless DCN. As the design spectrum of DCs broadens, so does the need for a clear classification to differentiate various design options. In this paper, we analyze the free space optical (FSO) communication and the 60 GHz radio frequency (RF), the two key candidate technologies for implementing wireless links in DCNs. We present a generic classification scheme that can be used to classify current and future DCNs based on the communication technology used in the network. The proposed classification is then used to review and summarize major research in this area. We also discuss open questions and future research directions in the area of wireless DCs

Characterisation and optimisation of the semiconductor optical amplifier for ultra-high speed performance

This research is in the area of high speed telecommunication systems where all- optical technologies are being introduced to meet the ever increasing demand for bandwidth by replacing the costly electro-optical conversion modules. In such systems, all-optical routers are the key technologies capable of supporting networks with high capacity/bandwidth as well as offering lower power consumption. One of the fundamental building blocks in all-optical routers/networks is the semiconductor optical amplifier (SOA), which is used in for clock extraction, wavelength conversion, all-optical gates and optical processing. The SOAs are perfect for optical amplification and optical switching at a very high speed. This is due to their small size, a low switching energy, non-linear characteristics and the seamless integration with other optical devices. Therefore, characterisation of the SOA operational functionalities and optimisation of its performance for amplification and switching are essential and challenging. Existing models on SOA gain dynamics do not address the impact of optical propagating wavelength, the combined input parameters and their adaptation for optimised amplification and switching operations. The SOA operation is limited at high data rates > 2.5 Gb/s to a greater extent by the gain recovery time. A number of schemes have been proposed to overcome this limitation; however no work has been reported on the SOA for improving the gain uniformity. This research aims to characterise the boundaries conditions and optimise the SOA performance for amplification and switching. The research also proposes alternative techniques to maximise the SOA gain uniformity at ultra-high speed data rates theoretically and practically. An SOA model is been developed and used throughout the research for theoretical simulations. Results show that the optimum conditions required to achieve the maximum output gain for best amplification performance depends on the SOA peak gain wavelength. It is also shown that the optimum phase shift of 180º for switching can be induced at lower input power level when the SOA biasing current is at its maximum limit. A gain standard deviation equation is introduced to measure the SOA gain uniformity. New wavelength diversity technique is proposed to achieve an average improvement of 7.82 dB in the SOA gain standard deviation at rates from 10 to 160 Gb/s. Other novel techniques that improved the gain uniformity employing triangular and sawtooth bias currents, as replacements for the uniform biasing, have been proposed. However, these current patterns were not able to improve the SOA gain uniformity at data rates beyond 40 Gb/s. For that reason, an optimised biasing for SOA (OBS) pattern is introduced to maximise the gain uniformity at any input data rates. This OBS pattern was practically generated and compared to the uniform biased SOA at different data rates and with different input bit sequences. All executed experiments showed better output uniformities employing the proposed OBS pattern with an average improvement of 19%

Optical Wireless Data Center Networks

Bandwidth and computation-intensive Big Data applications in disciplines like social media, bio- and nano-informatics, Internet-of-Things (IoT), and real-time analytics, are pushing existing access and core (backbone) networks as well as Data Center Networks (DCNs) to their limits. Next generation DCNs must support continuously increasing network traffic while satisfying minimum performance requirements of latency, reliability, flexibility and scalability. Therefore, a larger number of cables (i.e., copper-cables and fiber optics) may be required in conventional wired DCNs. In addition to limiting the possible topologies, large number of cables may result into design and development problems related to wire ducting and maintenance, heat dissipation, and power consumption. To address the cabling complexity in wired DCNs, we propose OWCells, a class of optical wireless cellular data center network architectures in which fixed line of sight (LOS) optical wireless communication (OWC) links are used to connect the racks arranged in regular polygonal topologies. We present the OWCell DCN architecture, develop its theoretical underpinnings, and investigate routing protocols and OWC transceiver design. To realize a fully wireless DCN, servers in racks must also be connected using OWC links. There is, however, a difficulty of connecting multiple adjacent network components, such as servers in a rack, using point-to-point LOS links. To overcome this problem, we propose and validate the feasibility of an FSO-Bus to connect multiple adjacent network components using NLOS point-to-point OWC links. Finally, to complete the design of the OWC transceiver, we develop a new class of strictly and rearrangeably non-blocking multicast optical switches in which multicast is performed efficiently at the physical optical (lower) layer rather than upper layers (e.g., application layer). Advisors: Jitender S. Deogun and Dennis R. Alexande

Characterisation and optimisation of the semiconductor optical amplifier for ultra-high speed performance

This research is in the area of high speed telecommunication systems where all- optical technologies are being introduced to meet the ever increasing demand for bandwidth by replacing the costly electro-optical conversion modules. In such systems, all-optical routers are the key technologies capable of supporting networks with high capacity/bandwidth as well as offering lower power consumption. One of the fundamental building blocks in all-optical routers/networks is the semiconductor optical amplifier (SOA), which is used in for clock extraction, wavelength conversion, all-optical gates and optical processing. The SOAs are perfect for optical amplification and optical switching at a very high speed. This is due to their small size, a low switching energy, non-linear characteristics and the seamless integration with other optical devices. Therefore, characterisation of the SOA operational functionalities and optimisation of its performance for amplification and switching are essential and challenging. Existing models on SOA gain dynamics do not address the impact of optical propagating wavelength, the combined input parameters and their adaptation for optimised amplification and switching operations. The SOA operation is limited at high data rates > 2.5 Gb/s to a greater extent by the gain recovery time. A number of schemes have been proposed to overcome this limitation; however no work has been reported on the SOA for improving the gain uniformity. This research aims to characterise the boundaries conditions and optimise the SOA performance for amplification and switching. The research also proposes alternative techniques to maximise the SOA gain uniformity at ultra-high speed data rates theoretically and practically. An SOA model is been developed and used throughout the research for theoretical simulations. Results show that the optimum conditions required to achieve the maximum output gain for best amplification performance depends on the SOA peak gain wavelength. It is also shown that the optimum phase shift of 180º for switching can be induced at lower input power level when the SOA biasing current is at its maximum limit. A gain standard deviation equation is introduced to measure the SOA gain uniformity. New wavelength diversity technique is proposed to achieve an average improvement of 7.82 dB in the SOA gain standard deviation at rates from 10 to 160 Gb/s. Other novel techniques that improved the gain uniformity employing triangular and sawtooth bias currents, as replacements for the uniform biasing, have been proposed. However, these current patterns were not able to improve the SOA gain uniformity at data rates beyond 40 Gb/s. For that reason, an optimised biasing for SOA (OBS) pattern is introduced to maximise the gain uniformity at any input data rates. This OBS pattern was practically generated and compared to the uniform biased SOA at different data rates and with different input bit sequences. All executed experiments showed better output uniformities employing the proposed OBS pattern with an average improvement of 19%.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Journal of Telecommunications and Information Technology, 2009, nr 1

kwartalni