Ghulam M. Chaudhry

Performance analysis of IPSec protocol: encryption and authentication

IPSec provides two types of security algorithms, symmetric encryption algorithms (e.g. data encryption standard DES) for encryption, and one-way hash functions (e.g., message digest MD5 and secured hash algorithm SHA1) for authentication. This paper presents performance analysis and comparisons between these algorithms in terms of time complexity and space complexity. Parameters considered are processing power and input size. The analysis results revealed that HMAC-MD5 can be sufficient for the authentication purposes rather than using the more complicated HMAC-SHA1 algorithm. In encryption applications, authentication should be combined with DES.

Routing framework for all-optical DWDM metro and long-haul transport networks with sparse wavelength conversion capabilities

In this paper, we propose a novel routing framework for all-optical dense wavelength-division-multiplexing transport networks with sparse wavelength conversion capabilities. The routing framework includes an integer linear programming formulation to handle the static lightpath establishment problem and a novel open shortest path first protocol extension that advertises the availability of wavelength usage and wavelength conversion resources. Our routing framework addresses the limitations of the extensions presented in the literature because it also includes: 1) an efficient flooding protocol that is suitable for the dynamic nature of these networks and 2) an efficient route and wavelength computation engine that minimizes connection costs without hindering the blocking probability.

Routing in all-optical DWDM networks with sparse wavelength conversion capabilities

This work focuses on the routing and wavelength assignment (RWA) problem in all-optical DWDM networks with sparse wavelength conversion (SWC) capabilities. By sparse wavelength conversion, we mean that nodes within the optical network domain might or might not support optical wavelength conversion. For these nodes that support optical wavelength conversion, the number of wavelength converters might be limited. As such, optical lightpaths might or might not be able to find the wavelength conversion resources that might be needed for it to be established. In this work, we present the RWA problem in all-optical WDWM networks with sparse wavelength conversion capabilities (RWA-SWC). We also provide integer linear programming (ILP) formulation for static lightpath establishment (SLE) in all-optical networks with sparse wavelength conversion capabilities. Finally, we propose a new opaque extension to the OSPF routing protocol to advertise wavelength usage and converter availability throughout the optical network domain.

Reliable Binary Signed Digit Number Adder Design

The binary signed digit number (BSDN) system is used implicitly or explicitly to speed up arithmetic operations in many digital systems. This is due to its capability of carry-free addition and regular layout. Also, with the proper selection of the encoding scheme used to encode the BSDN digit set D = {-1, 0, 1} into binary bits, an error detection capability feature can be gained. In this work, we present the design of BSDN full adder cell using the 1-out-of-3 encoding with and without error detection capability. Synthesis results showed that the carry-free addition feature of the BSDN adder is preserved in the proposed design regardless of the inputs size. Also the overall adder performance depends on the desired level of error detection and the effectiveness of the used BSDN full adder.

SPEED: Stand-alone programmable ethernet enabled devices ☆

Abstract In this paper we present the design and synthesis of Standalone Programmable Ethernet Enabled Devices (SPEED) as a low cost and power consumption embedded system, which also include an Electrical Erasable Programmable Read Only Memory controller for configurable address assignments. The main function of SPEED is to eliminate the operating system processing of network protocol stack running by personal computer processor and simplifying network functions. This simplification is not exclusively required to fit in a hardware solution, but more important it improves network performance. It utilizes the concept of network channels, where Ethernet frames are delivered through a custom multicast addressing scheme. After validating SPEED simulation outputs, we synthesize the design in FPGA chip using Verilog HDL. Performance measures like power consumption and area utilization are computed using Verilog HDL synthesis tools. Initial performance measures had shown that the SPEED would be reducing the power consumption. Consequently, network devices could be powered through the network cable and eliminate the process of regular electrical power outlet installations and maintenance. This way, SPEED reduces the installation complexity, especially for large number of devices (e.g. surveillance cameras).

New multiprotocol WDM/CDMA-based optical switch architecture

Different switching techniques have been proposed to design optical switch architectures. Wavelength division multiplexing (WDM) techniques were extensively investigated to implement switching. Code division multiple access (CDMA) permits multiple users to access bandwidth simultaneously and asynchronously via spread spectrum. This paper presents a non-blocking multiprotocol switch architecture bused on WDM and CDMA techniques. A WDM demultiplexer is used to distribute each wavelength to a specific CDMA switch fabric. The CDMA switch fabric is used to switch the information from an input port to an output port. Each packet is segmented into proprietary cells that are switched from the input to the output. This allows synchronous operation of the switch. Orthogonal subcodes are used for the same output port to avoid cell loss. The optimum number of subcodes used is determined using analytical modeling and simulations.

Economic analysis of a photovoltaic system connected to the grid in Recife, Brazil

Brazil has a big potential in solar energy, because of its location and territorial extension. However, this country does not explore this great source of energy, because of the high cost of installation of the photovoltaic (PV) system. This paper brings a design of a grid-interactive PV system with battery backup focusing more on the financial part, as a way to decrease the price to install this type of system. By analyzing a hypothetical load in a house in Recife, two situations were proposed: the use of incentives for financing and capital allowance through tax incentives, and the energy compensation system, net metering. The computational software SAM (System Advisor Model) was used to generate data for economic and financial analysis through methods like NPV (Net Present Value), PAYBACK and LCOE (Levelized Cost of Electricity). The results obtained show that distributed micro-generation through PV system is not economically viable without incentive instruments, such as regulatory policies, fiscal incentives and public financing.

A Real-Time Hardware-Based Scheduler For Next-Generation Optical Burst Switches

Optical burst switching (OBS) is a promising technique for next-generation optical switching networks. In traditional OBS, an entire burst is discarded when all output wavelengths are engaged at the arrival instant of the burst. A critical design issue in OBS is how to reduce burst dropping probability as a result of slow scheduling reservation or resources contention. This paper proposes a hardware-based slotted wavelength assignment pipeline (SWAP) scheduler which integrates the merits of both low computational complexity and low burst dropping probability. The key idea is to maintain all scheduled data bursts and void intervals within a scheduling time window in binary vectors. Scheduling of incoming data bursts is performed using fast hardware operations without the need to search lookup tables for void intervals on output wavelength channels. The design has been verified using Verilog HDL simulation models. The performance has been evaluated for 1 Tbps switch using Poisson traffic arrivals.

Architecture and Performance of A Next-Generation Optical Burst Switch (OBS)

Optical burst switching (OBS) is a promising technique for next-generation optical switching networks which attempts to address the problem of efficiently allocating resources for bursty traffic. In traditional OBS, an entire burst is discarded when all output wavelengths are engaged at the arrival instant of the burst. A critical design issue in OBS is how to reduce burst dropping probability as a result of resource contention. This paper proposes new core node architecture to provide a combined impact for an effective scheduling algorithm that improves burst loss rate and utilization in OBS switches. The new design provides an effective optical burst switching for variable-length bursts with low complexity compared to several existing scheduling algorithms. A combined contention resolution approach of wavelength reassignment capability and limited delay is used.

Link-state update policies for all-optical DWDM transport networks

It has been demonstrated that advertising the availability of wavelength and converter resources in all-optical DWDM transport networks with sparse wavelength conversion capabilities can drastically improve the blocking performance of these networks thus achieving better usage of the network resources. An important aspect with consequences in network performance is when to originate the wavelength-availability and converter-availability link state advertisements (LSAs). Frequent link-state advertisements could overwhelm the network control plane with many update messages that need to be processed. On the other hand, delaying these advertisements could result in inaccurate link-state information thus degrading the network blocking performance. In this paper, we propose two different link-state update policies to advertise the availability of wavelength and converter resource in all-optical DWDM transport networks with sparse wavelength conversion capabilities. The first one is very simple and serves as our base policy for comparison. The second policy, which is very efficient in handling the dynamic nature of all-optical DWDM networks with different degrees of wavelength conversion, reduces the number of LSAs considerably while maintaining the call blocking probability.