TCP transmission over a reconfigurable optical access network

The switching and routing is essential for an advanced and reconfigurable optical network, and great efforts have been done for traditional single-mode system. We propose and demonstrate an on-chip switch compatible with mode-division multiplexing system. By controlling the induced phase difference, the functionalities of dynamically routing data channels can be achieved. The proposed switch is experimentally demonstrated with low insertion loss of ~1 dB and high extinction ratio of ~20 dB over the C-band for OFF-ON switchover. For further demonstration, the non-return-to-zero on-off keying signals at 10 Gb/s carried on the two spatial modes are successfully processed. Open and clear eye diagrams can be observed and the bit error rate measurements indicate a good data routing performance.

Transport Control Protocol (TCP), a basic communication language, consists of a set of rules that control communication. There are many versions of TCP which modified time to time as per need. Initially we discuss the basic functions of TCP and their role to control the congestion then graphically examine slow start, congestion avoidance, fast retransmission and fast recovery. This paper compares the performance of different TCP variants specifically Tahoe, Reno, New Reno, Westwood, Selective Acknowledgment (SACK), Forward Acknowledgement (FACK) and Vegas. TCP Vegas algorithm is explained with new structure mechanism and new congestion avoidance and modified slow start mechanisms. Subsequently, a table derived evaluates TCP variants on the basis of algorithm. We conversed the progress, and evaluated advantages and disadvantages of above TCP variants.

The MONET project ended in November 1999. Over the five year duration of this project, many significant advances were made in optical networking architectures, components, subsystems, systems, and network demonstrations. In this paper, we report on the major accomplishment of the last year of the MONET project, which was the completion and operation of a transparent, reconfigurable optical network in Washington, DC. This paper describes the network and summarizes experimental results achieved in the first months of operation.

We have designed and constructed a scalable and reconfigurable optical IP network system for use in residential premises. The network system consists of an optical fiber bus, bus interfaces attached to the bus, and a gateway. In the newly constructed network, 8 optical wavelengths in the course WDM standard were allocated to Gigabit optical transceivers and optical add/drop modules, respectively. The performance examination clarified that throughput of around 90 Mbps was obtained even when 8 personal computers belonging to the different 8 sub networks sent packets simultaneously. The scalability was also confirmed by experiment.

Transport protocol design for supporting smart metering applications poses certain challenges because of unique issues. The issues stem from the need to deploy a significantly large number of meters (e.g., hundreds of thousands). Each meter generates small reports at a fixed low rate. All meters' reports are destined to the same data collection center and require reliable end-to-end delivery. Although individual data rates are low, aggregation creates large traffic that can disrupt the network functionality. Our experiments show that for this type of application, the Internet transport control protocol (TCP) results in the following drawbacks: (i) Meters' data suffer from excessive packet retransmission rate. (ii) Other applications suffer from high packet drop rate at shared bottleneck links. In this paper, we propose a solution through the addition of a TCP aggregator device and the use of an application level protocol called Session Initiation Protocol (SIP). At the TCP aggregator device, meters' TCP connections get combined into one TCP connection with the utility collection server. The SIP protocol acts as the signaling protocol to provide the different network parties with proper transport control information. The proposed strategy provides better response to traffic conditions and, most importantly, makes congestion control and flow control viable. Using the simulator NS-2, we show the effectiveness of our approach in mitigating the problems in terms of throughput and packet drop rate performance measures.

Optical performance monitoring might play a crucial role in enabling self-managed and reconfigurable high-performance optical networks. We will explore key motivating networking issues as well as potential monitoring techniques.

The authors discuss optical network devices and the performances that can be expected. The architectural features of a multiprocessor prototype machine's software tools, at system and user levels, are described. A survey of applications well suited for reconfigurable architectures using large networks built with optical components is also given. The presented optical network allows any link to be connected to any other link without contention. Such optical networks take advantage of the best features of two technologies by using optics for communications and electronics for computation. It is stated that massively parallel architectures using large networks can be reasonably envisaged with optical components. >

As the Internet becomes increasingly heterogeneous, the issue of congestion control becomes ever more important. And the queue length and end-to-end (congestion) delays are some of the important things in term of congestion avoidance and control mechanisms. In this research we continued to study the performances of the New-Additive Increase Multiplicative Decrease (AIMD) algorithm as one of the core protocols for TCP congestion avoidance and control mechanism, we want now to evaluate the effect of using the New-AIMD algorithm to measure the queue length and end-to-end delays and we will use the NCTUns simulator to get the results after make the modification of the mechanism. And we will use the Drop tail mechanism as Active Queue Management (AQM) in the bottleneck router. After implementation of our new approach with different number of flows, we will measure the delay for two types of delays (queuing delay and end-to-end delay), we expect the delay will be less with using our mechanism comparing with the mechanism in the previous study. Now and after got this results as low delay for bottleneck link case, we know the New-AIMD mechanism work as well under the network condition in the experiments.

Full duplex (FD) communication has attracted the attention of the industry and the academia as an important feature in the design of the future 5th generation (5G) wireless communication system. Such technology allows a device to simultaneously transmit and receive in the same frequency band, with the potential of providing higher throughput and lower latency compared to traditional half duplex (HD) systems. In this paper, the interaction between Transport Control Protocol (TCP) and FD in 5G ultra- dense small cell networks is studied. TCP is a well- known transport layer protocol for providing reliability, which comes at the price of increased delay and reduced system throughput. FD is expected to accelerate the TCP congestion control mechanism and hence mitigate such consequences. System level results show that FD can outperform HD and alleviate the TCP drawbacks when the inter-cell interference is not the main limiting factor. On the other hand, under strong inter-cell interference, results show that the capabilities of the system to cope with such interference dictates the gain that FD may provide over HD.

Problem statement: Transmission Control Protocol is the Internet’s most widely used transport control protocol. TCP’s strength lies in the adaptive nature of its congestion avoidance and control algorithm and its retransmission mechanism. In TCP Vegas rerouting (a path), which change the propagation delay of the connection and this may be able to result in a substantial decrease in through put. An enhanced algorithm for TCP in wireless Ad Hoc networks is needed to obtain a fairer share of the available bandwidth, tackle re-routing problems and solve the problems associated with older TCP Vegas flows. Approach: TCP-Vegas uses an Estimation of the propagation delay, base RTT, to adjust its window size and it is very important for a TCP Vegas connection to be able to have an accurate estimation. Results: One of the issues is rerouting (a path), which change the propagation delay of the connection and this may be able to result in a substantial decrease in through put. The issue identified with TCP Vegas was reinvestigated and to address them, a modification to TCP Vegas’s congestion avoidance algorithm is proposed. Conclusion: This modified TCP enhancement algorithams is shown to obtain a fairer share of the available bandwidth, tackle re-routing problems and solve the problems associated with older TCP Vegas flows.

We demonstrate a MEMS tunable silicon photonic ring resonator with a 20 µm radius and a 5 nm free spectral range (FSR) for wavelength selection in reconfigurable optical networks. The device shows a loaded Q of 12000, and 300 pm tuning range at a wavelength of 1544 nm.

Wavelength multiplexing and tuning capabilities are highly important for applications in optical interconnects and optical communications using wavelength division multiplexing (WDM). We review novel methods and experimental results to achieve these functions in vertical cavity surface-emitting lasers (VCSEL), we believe for the first time. By implementing spatially chirped layers in the laser cavities and obliquely aligning the array axes to the thickness chirp direction, we obtained 7 × 20 VCSEL array emitting 140 unique, non-redundant, controllable, uniformly separated single-mode wavelengths. A large total wavelength span of 43 nm is obtained without compromising the performance of the lasers. Moreover, our techniques are generic and can be readily extended to other wavelength regimes. In addition, we describe our work on wavelength-tunable VCSELs with a 1.8-nm (~540 GHz) continuous tuning and no mode hopping. The laser output power remains nearly constant throughout the tuning range. The wavelength tuning speed is ~400 ns. The multiple wavelength tunable laser arrays are promising for achieving ultrahigh bandwidth (hundreds Gbit/sec to Tbit/sec), high redundancy and reliability, reconfigurable optical networks.

We describe a wide range of reconfigurable optical add-drop multiplexer architecture designs that may be implemented in standard silica-on-silicon planar lightwave circuits. This proven, reliable technology offers high performance and cost-effective solutions for reducing complex service provisioning in reconfigurable optical networks. Recent advances enable very flexible wavelength routing devices for mesh- and ring-based networks to be implemented on a common subsystem integration platform. We show excellent system performance at 10 Gb/s.

Wavelength conversion in the transmission of a message masked by optical chaos is experimentally demonstrated. In our setup, chaos is generated by a distributed-feedback laser subject to delayed optical feedback, and hides a message by additive chaos masking. The optical wavelength is converted, along the transmission line, by four-wave mixing in a semiconductor optical amplifier. At the receiver, the message is extracted by master-slave synchronization. Our experiments demonstrate that secure communications based on chaos are compatible with channel switching as required in reconfigurable optical networks.

Optical on-chip interconnects enable significantly increased bandwidth and decreased latency in MPSoC. They are characterized by high static energy and low dynamic energy consumption. Achieving high energy-efficient communication thus requires a certain adaptability degree to the executed application and its communication traffic in order to reduce the static energy. In this paper, we introduce a mapping method for CHAMELEON, an optical interconnect allowing configuring dedicated communication channels according to an application and its corresponding communication traffic.