A STUDY ON WIRELESS COMMUNICATION ERROR PERFORMANCE AND PATH LOSS PREDICTION

One channel model that characterises multipath fading effect of a wireless channel is called Flat Rayleigh Fading channel model. Given the properties of Flat Rayleigh Fading channel, an equation to find the capacity of a Flat Rayleigh fading channel with hard decision decoding is derived. The difference of power requirement to achieve the Additive White Gaussian Noise (AWGN) capacity over a Flat Rayleigh Fading channel fading is found to increase exponentially with Es /N0 . Upper and lower bounds of error performance of linear block codes over a Flat Rayleigh Fading channel are also studied. With the condition that the excess delay of a channel is known earlier, it is shown that a correlator with shorter length, according to excess delay of the channel, can be constructed for use in wireless channel response measurements. Therefore, a rule of construction of a shorter length correlator is defined, involving concatenation of parts of a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence. Simulation of [136,68,24] Double Circulant Code with Dorsch List Decoding is also done in order to evaluate error performance of the channel coding scheme over one of the IEEE Wireless Metropolitan Area Network (WirelessMAN) channel models, the Stanford University Interim Channel Model No. 5 (SUI-5) channel. Performance of the channel cod- ing was severely degraded over the SUI-5 channel when it is compared to its performance over the AWGN channel. Indoor path losses within three multifloor office buildings were investigated at 433 MHz, 869 MHz and 1249 MHz. The work involved series of extensive received signal strength measurements within the buildings for all of the considered frequencies. Results have shown that indoor path loss is higher within a square footprint building than indoor path loss in a rectangular building. Parameters of Log-Distance Path Loss and Floor Attenuation Factor Path Loss models have been derived from the measurement data. In addition, a new indoor path loss prediction model was derived to cater for path loss pre- diction within multifloor buildings with indoor atriums. The model performs with better prediction accuracy when compared with Log-Distance Path Loss and Floor Attenuation Factor Path Loss models.Ministry of Higher Education of Malaysia, Universiti Teknologi Malaysi

Seluge++: A Secure Over-the-Air Programming Scheme in Wireless Sensor Networks

Over-the-air dissemination of code updates in wireless sensor networks have been researchers’ point of interest in the last few years, and, more importantly, security challenges toward the remote propagation of code updating have occupied the majority of efforts in this context. Many security models have been proposed to establish a balance between the energy consumption and security strength, having their concentration on the constrained nature of wireless sensor network (WSN) nodes. For authentication purposes, most of them have used a Merkle hash tree to avoid using multiple public cryptography operations. These models mostly have assumed an environment in which security has to be at a standard level. Therefore, they have not investigated the tree structure for mission-critical situations in which security has to be at the maximum possible level (e.g., military applications, healthcare). Considering this, we investigate existing security models used in over-the-air dissemination of code updates for possible vulnerabilities, and then, we provide a set of countermeasures, correspondingly named Security Model Requirements. Based on the investigation, we concentrate on Seluge, one of the existing over-the-air programming schemes, and we propose an improved version of it, named Seluge++, which complies with the Security Model Requirements and replaces the use of the inefficient Merkle tree with a novel method. Analytical and simulation results show the improvements in Seluge++ compared to Seluge

Interval based transaction record keeping mechanism for adaptive 3d network-on-chip routing

Due to technology scaling, network-on-chip (NoC) become the viable solution for on-chip many-core systems. The most critical concern of NoC is congestion management caused due to heavy communication traffic between nodes. Without an appropriate congestion resolution strategy for reducing heavy in-network traffic, the efficiency of the entire network is damaged severely. In this paper, an interval based record-keeping mechanism is presented to reduce network traffic and congestion by maintaining a history table and previous packet transaction records at each node. Proposed method performs certain validity checks before allowing using previous transaction record from history table. The performance of the technique is investigated in terms of average delay and compared to the state-of-the-art routing algorithms using the Access Noxim simulator. The simulation results demonstrate that the proposed method has outperformed in terms of global average delay, with 8-12% improvement, the average number of hits is 26-61% greater than misses under different synthetic traffic. The proposed algorithm has been tested under various topological configurations for efficiency evaluation

Survey on end to end congestion control techniques in different network scenarios

Most of the traffic on the Internet is depend upon the Transmission Control Protocol (TCP), so the performance of TCP is directly related to Internet. Many TCP variants are developed and modified according to the environment and communication needs. Most of current TCP variants have set of algorithms which control the congestion in critical situations and maintain the throughput and efficiency of network. Now a day’s TCP is facing fast growth of Internet with the demands of faster data communication techniques on high speed links. In last 15 years many computer systems and cellular networks become linked together with protocol stack used in TCP. TCP variants with different congestion control techniques are working in different operating systems but a very small number of techniques are able to minimize the congestion in the network. This paper presents a survey on end-to-end congestion control techniques used in different TCP versions. The main purpose of this study is to review the characteristics and behavior of TCP variants with different techniques to control the congestion in the different network scenarios

Dynamic mobile anchor path planning for underwater wireless sensor networks

In an underwater wireless sensor network (UWSN), the location of the sensor nodes plays a significant role in the localization process. The location information is obtained by using the known positions of anchor nodes. For underwater environments, instead of using various static anchor nodes, mobile anchor nodes are more efficient and cost-effective to cover the monitoring area. Nevertheless, the utilization of these mobile anchors requires adequate path planning strategy. Mzost of the path planning algorithms do not consider irregular deployment, caused by the effects of water currents. Consequently, this leads towards the inefficient energy consumption by mobile anchors due to unnecessary transmission of beacon messages at unnecessary areas. Therefore, an efficient dynamic mobile path planning (EDMPP) algorithm to tackle the irregular deployment and non-collinear virtual beacon point placement, targeting the underwater environment settings is presented in this paper. In addition, EDMPP controls the redundant beacon message deployment and overlapping, for beacon message distribution in mobile assistant localization. The simulation results show that the performance of the EDMPP is improved by increasing the localization accuracy and decreasing the energy consumption with optimum path length

Secure and authenticated key agreement protocol with minimal complexity of operations in the context of identity-based cryptosystems

Recently, a large variety of Identity-Based Key Agreement protocols have tried to eliminate the use of Bilinear Pairings in order to decrease complexity of computations through performing group operations over Elliptic Curves. In this paper we propose a novel pairing-free Key Agreement protocol over elliptic curve based algebraic groups. The results show that our proposed protocol is significantly less complex than related works from complexity of computation perspective

A performance improved certificateless key agreement scheme over elliptic curve based algebraic groups

Due to the importance of key in providing secure communication, various Key Agreement protocols have been proposed in the recent years. The latest generation of Public Key Cryptosystems (PKC) called Certificateless PKC played an important role in the transformation of Key Agreement protocols. In this scientific area, several Key Agreement protocols have been proposed based on Bilinear Pairings. However, pairing operation is known as an expensive cryptographic function. Hence, utilization of pairing operation in the mentioned works made them complex from overall computational cost perspective. In order to decrease the computational cost of Key Agreement protocols, several Certificateless Key Agreement protocols have been proposed by the use of operations over Elliptic Curve based Algebraic Groups instead of using Bilinear Pairings. In this paper, we propose a Pairing-free Certificateless two-party Key Agreement protocol. Our results indicate that our secure protocol is significantly more lightweight than existing related works

Mortality in children under 5: prevalence of congenital malformations and its associated demographic variables

Introduction Congenital malformations (CM) comprise a wide range of abnormalities of body structure or function that are present at birth and are of prenatal origin. It has contributed to a significant proportion of infant morbidity and mortality. The aims of this study were to determine the extent and investigate the relationship between CM and its associated demographic variables. Methods Data was extracted from Ministry of Health (MOH) database compiled from the reports on Stillbirth & Under 5 Mortality from year 2013 to 2014. Results Out of 9,827 child death, 2,840 (28.9%) were classified under CM as defined under ICD-10 classification. Majority of those with CMs died at neonatal stage (62.7%) and among mothers aged between 20 to 35 years old (67.3%). The mean age of mothers among CM children was 30.8±6.5 years old. Approximately 5.8%, 6.7% and 3.3 % of total CM were neural tube defects, heart defects and hydrops fetalis respectively. The prevalence of CM in males was 15% higher than females. The difference were evident between CM and age of death of children under 5 years old (p<0.001) as well as between CM and maternal age groups (p<0.001). Conclusions CM is responsible for 28.9% of total causes of child death with higher occurrence of malformation in males. A significantly higher risk of CMs among mother aged between 20 to 35 years old was observed. This emphasises the importance of raising awareness and the need to strengthen appropriate response for surveillance and prevention program of common CM in Malaysia