BAKO : Biodiversity Between Land and the Sea

Sarawak’s vast forested landscape includes numerous protected areas network, comprising National Parks represents some of the best examples of the State’s natural wonders- fl oral, faunal as well as geological. Western Sarawak, in particular, is an important area for biodiversity conservation, being home to many Bornean endemics and other species of conservation importance that do not extend beyond the north-western corner of this large tropical island

A Smooth Forwarding Operation in Wireless Mesh Network

The IEEE 802.11 Distributed Coordination Function (DCF) Medium Access Control (MAC) protocol is designed to efficiently facilitate the limited communication bandwidth of wireless channel. This protocol uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism. This mechanism continues suffer from throughput degradation when directly applied in multihop Wireless Mesh Network (WMN). The major reason for this poor performance is due to larger signaling overheads (RTS and CTS signaling packet) introduced in order to forward a single data packet in multihop WMN. This inefficient forwarding operation caused the throughput degradation signifficantly. Therefore, an efficient forwarding operation is proposed in this paper to reduce the amount of signaling overheads which are needed to forward a single packet in multihop WMN. The proposed protocol uses the capability of overhearing in order to forward the data packet from one hop to another hop. This process will continue until the data packet reaches the respective destination. As a result, the enhanced protocol reduces the latency caused by signaling thus improve its throughput in multihop WMN. The multihop network performances are evaluated analytically in terms of throughput and delay. Through the simulation, it is proven that the proposed protocol provides significant improvement in throughput and delay. The results show that the proposed protocol outperforms the existing IEEE DCF MAC protocol when it is evaluated in multihop WMN

INTRODUCTION

The State of Sarawak, with an area of approximately 124,450 km2 , has one of the most established networks of protected areas within Malaysia, representing some of the most megadiverse rainforests of the world. The landscape ranges from coastal lowlands, comprising peat swamps, as well as narrow deltaic and alluvial plains, to a vast hinterland of undulating low hills, that barely reach 300 metres, to the mountainous highlands, that extend to the international border in the interiors of Borneo. The State currently has 67 Totally Protected Areas (including National Parks, Wildlife Sanctuaries and Nature Reserves), scattered throughout the State, a majority located in western Sarawa

A Triple-band Dipole Antenna with 0.92 GHz AMC-HIS

A triple-band dipole antenna integrated with 0.92 GHz Artificial Magnetic Conductor (AMC) is presented. The AMC structure is called a highimpedance surface (HIS) structure and is useful as a ground plane to the dipole antenna. This structure can be used to prevent the degradation of tag and antenna performance caused by the conductive materials (metal objects) and to increase the antenna gain. This paper begins by investigating the parameters in AMC design such as a patch and gap size. The AMC is characterized by the frequency where the phase of the reflection coefficient is zero degrees and has reflected wave in-phase with the incident wave

Characterization of electrostatic discharge threshold voltage of phase-shift mask reticle

A reticle is a stencil used in lithography process for forming integrated circuit (IC) on silicon substrate. It consists of a thin (100 nm) coating of masking metallic patterned (features) with critical dimension (CD) of nanometers on a thicker quartz substrate. The features can be damaged by electrostatic discharge (ESD) when exposed to the environment electrostatic charge and caused deformed IC and eventually device difunctional. Semiconductor equipment materials industry (SEMI) standard established the allowable electrostatic charge on reticle based on the characterization of ESD threshold voltage on binary reticle. However, there is another type of reticle which is phase-shift mask (PSM), has not been characterized for its ESD threshold voltage. A direct current (DC) voltage is applied directly to the structures with CD of 80 nm, 110 nm, and 160 nm. The surface current is recorded at all levels of stress from 1 to 100 V. The current–voltage (IV) curve and physical inspection results for each cell are then reviewed and classified. The results yielded which no electric field induced migration (EFM) defect and breakdown voltage occurred at any of the structures. The cathode’s metal work function has been identified as the factor that influences the PSM reticle ESD threshold voltage

A Meandered Triple-band Printed Dipole Antenna for RFID

In this paper, a meandered triple-band printed dipole antenna is proposed for Radio Frequency Identification (RFID). This meandered tri-band printed dipole antenna is designed to operate at 0.92 GHz, 2.45 GHz and 5.8 GHz with the aid of Computer Simulation Technology (CST) software. In order to achieve triple-band operation, the proposed antenna contains two branch elements, which act as an additional resonator. The designed antenna is fabricated using Taconic RF-35 substrate with a dielectric constant (Er) of 3.5 and thickness (h) of 0.508 mm. The antenna’s parameters for triple-band operation are investigated and discussed. Then, this fabricated antenna is integrated with the UHF microchip to become a passive UHF tag. This tag is tested by measuring the reading distance and it is found that the proposed tag can be used for RFID application

Experimental quantification of electrostatic damage (ESD) in binary reticle with feature of nanometre scale gaps

A Binary reticle for lithography circuit patterning is extremerly senstive to electrostatic field. Damaged is seen on its feature after a breakdown voltage occurred between the metal lines. The experimental quantification of ESD for Binary reticle is performed by direct discharge to the feature of Critical Dimension (CD) of 80 nm to 160 nm. Its breakdown voltage correlated to CD but lower than international standard recommendations and observed Electric Field-Induced Migration (EFM) damaged at CD of 110 nm to 160 nm

A SURVEY OF CONTENTION BASED MEDIUM ACCESS CONTROL (MAC) PROTOCOLS IN WIRELESS LAN

In wireless network, all radio nodes are tuned to the same frequency to interconnect and establish communication between each other. All nodes in the network broadcasts their packets over a common medium and in such scenario collisions are considered as instinctive attribute. Therefore, a proper method/regulation known as Medium Access Control (MAC) protocol is required to regulate and manage an efficient access to the common channel. The protocol is designed to allow radio nodes in wireless network to broadcast their packets in an orderly and efficient manner to eliminate the collision among them. It also provides a fair bandwidth sharing to all contending nodes in the network. To date, various MAC protocols was developed to regulate the communication access among all radio nodes in wireless network. This article presents an exhaustive survey of existing contention based MAC protocols, their operations, advantages and disadvantages. Other than that, a typical MAC protocol used in IEEE 802.11 wireless networks standard, such as Carrier Sense Multiple Access (CSMA) and Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) also explained and presented in this article

Alleviate exposed node issues in Wireless Mesh Network (WMN) using a novel approach of Concurrent Medium Access Control (C-MAC) protocol

The importance and high growth of the communication infrastructure is clearly stated under the Malaysia Economic Transformation Programme (ETP). The most popular technology that used to provide the internet service to public is the IEEE 802.11a/b/g/n based WiFi. However, the coverage provided by the WiFi technology is only limited up to certain range. In addition, the performance of the WiFi network also will become poorer and poorer as the number of users associate with that WiFi network increases. In order to address these issues, the best topology configuration known as mesh is proposed by wireless research community. This technology is also called as Wireless Mesh Networks (WMN) and it became an emerging technology which is plays an important role in the next generation wireless communication. However, the implementation of IEEE 802.11 Medium Access Control (MAC) protocol in WMN significantly degrades the network performance due to the presence of exposed node problem. The presence of exposed nodes in WMN caused waiting delay (prevent the surrounding neighboring nodes to involve in transmission activity for entire duration of ongoing transmission) and it is subsequently leads to poor throughput achievement. The significance of this research is to investigate the cause of exposed nodes that degrade the performance of WMN and proposed a novel protocol to solve it to provide better network performance and throughput