Analysis of optical networks in presence of nodes noise and crosstalk

Optical packet switching has gained lot of momentum in last decade due to the advantages of optical fiber over copper cables. Optical switching is beneficial in optical networks which form connections of links and switching nodes. In these high speed networks minimum delay and high throughput are two important parameters which are considered. To minimize network delay shortest path algorithm is used for route selections. In previous studies while choosing shortest path distance among various nodes is considered. In this work we have shown that it is necessary to consider both distance and number of hops while choosing path from source to destination to minimize power per bit used for the transmission.

Hybrid buffer and AWG based add-drop optical packet switch

Optical packet switching (OPS) exhibits the ability to be utilized as a data transmission technique for next-generation. The core router/switch plays a significant role in packet routing and buffering in OPS. Arrayed waveguide grating (AWG) is realized as a promising core element for fast optical switching, with its intrinsic capacity to achieve wavelength routing of different wavelengths in parallel. This paper proposes an AWG-based add-drop optical packet switch, including a hybrid buffer, to resolve contention among packets. In a hybrid buffer, both optical and electronic buffers are used for the buffering of contending packets. AWGs are affected by crosstalk that can significantly impair system operation. The physical layer analysis is discussed in the presence of crosstalk, and the performance of the switch is evaluated in terms of bit error rate. The desired minimum input power is calculated for the switch’s correct operation for both optical buffer and electronic buffer. Finally, the packet loss probability (PLP) of the hybrid buffer is examined under various buffering conditions. Results reveal that with the increase in the optical power of the input signal, crosstalk power increases linearly for optical and electronic buffers. The increased crosstalk power is higher for electronic buffers than the optical buffer. The use of electronic memory in the hybrid buffer allows the hybrid buffer to increase its buffer size thus, reducing the PLP.

A critical review of optical switches

Optical packet switching has gained lot of popularity in last a few years due to its advantages like, large speed, more bandwidth and very less crosstalk. But due to immature optical fabrication and designing technology OPS is still beyond reality. However, many of the optical components are commercialized and some of them are still in laboratory. Thus, for optical switches which are considered as future generation routers, many switch architectures are proposed by using different sets of optical components. This paper presents a detailed review of notable switch designs in past 20 years, and also presents a comprehensive literature survey of the notable papers related to optical packet switch designs.

A Novel Variable-Length Header Extraction Scheme Based on Ring Laser for All-Optical Packet Switching Network

In this paper, a novel header extraction scheme based on semiconductor ring laser is proposed and simulated for proof of principle. This scheme is to be used in all-optical packet switching network which can extract return-to-zero (RZ) format modulation data packet with variable header/payload length and intensive spacing. Simulations and numerical analysis for a 3-byte header and 128-byte payload show that this structure can extract the headers with more than 20 dB contrast ratio. Additionally, the structure simplicity and its small size is proper candida to integration in all-optical circuits.

Optical Packet and Burst-Switched Networks

In order to address poor bandwidth-utilization in circuit-switched WRONs, various techniques for optical packet-switching (OPS) have been explored, but needing complex technologies, such as real-time header extraction/insertion, packet alignment, etc. An intermediate solution between the WRONs and OPS networks – the optical burst-switched (OBS) network – has been explored, where several packets are clubbed together at ingress nodes to form optical bursts, which are transmitted with the headers sent as control packets ahead of each bursts. With this prior resource-reservation scheme at en-route nodes before burst arrivals, OBS networks overcome the challenges of OPS networks, while improving bandwidth utilization as compared to WRONs. We first present the node architectures, followed by header-processing schemes and switch designs for OPS networks. Next we present the basic concepts of OBS networking and describe the necessary network protocols, including burst assembly scheme, just enough time (JET) signaling, resource-reservation and routing schemes. (145 words)