Mohammed Atiquzzaman

VLSI Architectures for Layered Decoding for Irregular LDPC Codes of WiMax

We present a new multi-rate architecture for decoding irregular LDPC codes in IEEE 802.16e WiMax standard. The proposed architecture utilizes the value-reuse property of offset min-sum, block-serial scheduling of computations and turbo decoding message passing algorithm. The decoder has the following advantages: 55% savings in memory, reduction of routers by 50%, and increase of throughput by 2times when compared to the recent state-of-the-art decoder architectures.

A survey of data replication techniques for mobile ad hoc network databases

A mobile ad hoc network (MANET) is a network that allows mobile servers and clients to communicate in the absence of a fixed infrastructure. MANET is a fast growing area of research as it finds use in a variety of applications. In order to facilitate efficient data access and update, databases are deployed on MANETs. These databases that operate on MANETs are referred to as MANET databases. Since data availability in MANETs is affected by the mobility and power constraints of the servers and clients, data in MANETs are replicated. A number of data replication techniques have been proposed for MANET databases. This paper identifies issues involved in MANET data replication and attempts to classify existing MANET data replication techniques based on the issues they address. The attributes of the replication techniques are also tabulated to facilitate a feature comparison of the existing MANET data replication works. Parameters and performance metrics are also presented to measure the performance of MANET replication techniques. In addition, this paper also proposes criteria for selecting appropriate data replication techniques for various application requirements. Finally, the paper concludes with a discussion on future research directions.

Internet telephony: services, technical challenges, and products

The rapid proliferation of the Internet has given rise to a strong interest in carrying telephony over the Internet. Because the Internet supports data communications, a range of other services can be bundled together with Internet telephony. The Internet, however, was designed for non-real-time data communications, and hence it poses several technical challenges that must be overcome before the Internet can be successfully used for carrying telephone services. This article discusses new services we can expect from Internet telephony, the technical challenges and solutions, and the emerging products that promise to support Internet telephony.

Multiresolution Hough transform-an efficient method of detecting patterns in images

A new multiresolution coarse-to-fine search algorithm for efficient computation of the Hough transform is proposed. The algorithm uses multiresolution images and parameter arrays. Logarithmic range reduction is proposed to achieve faster convergence. Discretization errors are taken into consideration when accumulating the parameter array. This permits the use of a very simple peak detection algorithm. Comparative results using three peak detection methods are presented. Tests on synthetic and real-world images show that the parameters converge rapidly toward the true value. The errors in rho and theta , as well as the computation time, are much lower than those obtained by other methods. Since the multiresolution Hough transform (MHT) uses a simple peak detection algorithm, the computation time will be significantly lower than other algorithms if the time for peak detection is also taken into account. The algorithm can be generalized for patterns with any number of parameters. >

Error modeling schemes for fading channels in wireless communications: A survey

Network system designers need to understand the error performance of wireless mobile channels in order to improve the quality of communications by deploying better modulation and coding schemes, and better network architectures. It is also desirable to have an accurate and thoroughly reproducible error model, which would allow network designers to evaluate a protocol or algorithm and its variations in a controlled and repeatable way. However, the physical properties of radio propagation, and the diversities of error environments in a wireless medium, lead to complexity in modeling the error performance of wireless channels. This article surveys the error modeling methods of fading channels in wireless communications, and provides a novel user-requirement (researchers and designers) based approach to classify the existing wireless error models.

Wireless sensor network for aircraft health monitoring

Wireless sensor networks is an emerging paradigm of computing and networking where a node may be selfpowered, and have sensing, computing, and communication capabilities. They have been proposed for use in a wide variety of applications. The objective of this article is to describe a wireless sensor network for monitoring of the health of aircraft engines. We describe the architecture of the wireless sensor network along with how it fits into the general area of wireless sensor networks.

Security, Privacy and Anonymity in Computation, Communication and Storage

Software defined networking (SDN) decouples the network control and data planes. The network intelligence and state are logically centralized and the underlying network infrastructure is abstracted from applications. SDN enhances network security by means of global visibility of the network state where a conflict can be easily resolved from the logically centralized control plane. Hence, the SDN architecture empowers networks to actively monitor traffic and diagnose threats to facilitates network forensics, security policy alteration, and security service insertion. The separation of the control and data planes, however, opens security challenges, such as man-in-the middle attacks, denial of service (DoS) attacks, and saturation attacks. In this paper, we analyze security threats to application, control, and data planes of SDN. The security platforms that secure each of the planes are described followed by various security approaches for network-wide security in SDN. SDN security is analyzed according to security dimensions of the ITU-T recommendation, as well as, by the costs of security solutions. In a nutshell, this paper highlights the present and future security challenges in SDN and future directions for secure SDN.

Signaling cost and performance of SIGMA: A seamless handover scheme for data networks

Department of Technology Education, Korea National University of Education, San 7-1, Darakri, Chongwon-Gun, Chungbuk, 363-791, KoreaSummaryMobile IPhasbeendeveloped to handlemobility of Internet hosts at thenetworklayer.MobileIP(MIP),however,suffers from a number of drawbacks such as requirement of infrastructure change, high handover latency, highpacket loss rate, and conflict with network security solutions. In this paper, we describe and evaluate theperformance of SIGMA, a Seamless IP diversity-based Generalized Mobility Architecture. SIGMA utilizesmultihoming to achieve seamless handover of mobile hosts, and is designed to solve many of the drawbacks ofMIP, including requirement for changes in infrastructure. We first evaluate the signaling cost of SIGMA andcomparewiththatofhierarchicalMobileIPv6(anenhancementofMobileIP)byanalyticalmodeling,followedbycomparison of handover performance of SIGMA and Mobile IPv6 enhancements. Criteria for performanceevaluation include handover latency, packet loss, throughput, and network friendliness. Our results indicatethat in most cases SIGMA has a lower signaling cost than Hierarchical Mobile IPv6. Moreover, for a typicalnetwork configuration,SIGMA hasahigherhandoverperformanceoverMobileIP.Copyright#2005JohnWiley& Sons, Ltd.KEY WORDS: mobile handover; SIGMA; mobile IP; IP diversity; signaling cost1. IntroductionMobile IP (MIP) [1] has been designed to handlemobility of Internet hosts at the network layer tomanage mobile data communication. It allows aTCP connection to remain alive when a mobile host(MH) moves from one point of attachment to another.Several drawbacks exist when using MIP in a mobilecomputing environment, the most important onesidentified to date are high handover latency, highpacket loss rate [2], and requirement for change ininfrastructure. MIP is based on the concept of homeagent (HA) and foreign agent (FA) (which requiresmodificationtoexistingroutersinInternet)forroutingpackets from previous point of attachment to the newone. An MH needs to complete the following foursteps before it can receive forwarded data from theprevious point of attachment: (i) perform layer 2 (L2)handover, (ii) discover the new care of address (CoA),(iii) registering the new CoA with the HA, and (iv)

Architecture and performance of SIGMA: a seamless mobility architecture for data networks

The Internet Engineering Task Force has developed Mobile IP to handle the mobility of Internet hosts at the network layer. Mobile IP, however, suffers from a number of drawbacks such as high handover latency, packet loss, and conflict with network security solutions. We describe and evaluate the performance of SIGMA (seamless IP diversity based generalized mobility architecture). SIGMA utilizes IP diversity to achieve the seamless handover of a mobile host, and is designed to solve many of the drawbacks of Mobile IP. Various aspects of the performance of SIGMA and Mobile IPv6 enhancements have been compared. Criteria for performance evaluation include handover latency, packet loss, throughput, and network friendliness.

SCTP: state of the art in research, products, and technical challenges

The stream control transmission protocol (SCTP) is being standardized by IETF as a reliable transport protocol to address a number of limitations of TCP. Due to its attractive features, such as multi-streaming and multi-homing, SCTP has received much attention from the research community and industry. The paper serves as a tutorial by introducing the main features of SCTP, and discussing the state of the art in SCTP research activities. We also provide a survey on the available products which implement SCTP. Finally, the challenges faced by SCTP research community are identified with a view to stimulating further research.