Rozeha A. Rashid

Fuzzy logic partition-based call admission control for mobile WiMAX

The unpredictable nature of the wireless network and exponential growth in traffics with different quality of service requirements has led hardware complexity to escalate. In order to effectively control and manage the network traffics, there is a need for intelligent call admission control (CAC) in admitting traffics into the wireless network that provides necessary quality of service. In this paper, we propose a fuzzy logic partition-based call admission control (FZ CAC). The scheme primarily partitions the total link bandwidth into three which corresponds to constant bit rate (CBR), variable bit rate (VBR) and handover (HO) services. The fuzzy logic admission control scheme was implemented in the HO portion to intelligently keep dropping probability as low as possible based on the available bandwidth. Simulation results showed that the proposed approach outperformed both partition-based CAC (PB CAC) and conventional bandwidth allocation CAC (CB CAC).

RSSI measurements for enabling IEEE 802.15.4 coexistence with IEEE 802.11b/g

The 2.4 GHz Industrial, Science and Medical (ISM) band is a license free band allocated for a variety of consumer applications: environmental monitoring, agriculture, medical care, smart buildings, factory monitoring and automation, and numerous military applications. This project focuses on the Adaptive Interference Avoidance Scheme for IEEE 802.15.4 to allow coexistence with IEEE 802.11b/g in the 2.4GHz ISM band. A wireless sensor network (WSN) consists of small nodes with sensing, computation, and wireless communication capabilities. It is an exciting new technology and can also be considered as the underlying infrastructure that will be integral part of future ubiquitous and embedded computing applications. Due to the independent design and development in WSN, together with the unexpected dynamics during deployment of co-existing networks such as IEEE802.11b/g and devices within the same frequency spectrum, it is crucial to ensure that each wireless technology maintains and provides its desired performance requirement. Therefore, a method to determine and avoid the collision between IEEE 802.15.4 and IEEE 802.11b/g devices when co-exist within a certain environment needs to be carried out.

Flood transmission based protocol for home automation system via power line communication

There are many researches and development involving the use of power line as data transmission medium. With multiple power outlets in almost every room in every house, the power line is the most pervasive network and the largest infrastructure available. The aim of this project is to deploy this infrastructure in designing a home automation system. This paper presents a method to develop a home automation system using the AC (alternating current) power line to establish a network between main controlling unit and client units with a proprietary designed power line communication (PLC) protocol. The designed protocol has features such as multinode simplex communication, flood transmission and even parity error detection. The protocol is successfully implemented and tested in a home automation system consisting of one main controlling unit and three client units. Each client unit is able to control three electrical devices. Multipoint of receiver units can be controlled (on/off) by the main controller unit sending command data using power line as transmission medium to the corresponding devices.

TDMA-based cooperative sensing using SDR platform for cognitive radio

The current trend and demand of wireless services requires more efficient spectrum usage. With Cognitive Radio (CR) technology, spectrum efficiency will be increased by exploiting unused licensed or primary users spectrum. Spectrum sensing mechanism is one of the main cores in CR system. To combat the problems of shadowing, multipath fading, and hidden nodes, cooperative spectrum sensing has been proposed. Testbed prototyping for sensing is a challenging task. The demand for cooperative sensing to solve the above mentioned problems leads to proposals of PHY and MAC layer solutions. Therefore, in this paper, we demonstrate an experimental platform using USRP board that can facilitate the development of PHY and MAC layers functionality for cooperative spectrum sensing. In this paper, TDMA-based MAC protocol for cooperative sensing mechanism is proposed. The observation of the preliminary experimental measurement shows significant performance in term of feasibility of cooperative decision mechanism in wireless condition.

Implementation of enhanced lightweight Medium Access (eL-MAC) protocol for wireless sensor network

Wireless sensor network (WSN) is increasingly being used in a variety of applications which include habitat monitoring, smart health care system, building automation, to name a few. Many approaches were developed for all protocol layers, but an energy-efficient Medium Access Control (MAC) layer remains a key design challenge. MAC with scheduled based architecture provides greater advantage over other designs, such as contention-based and frequency division multiple access (FDMA), in terms of minimizing packet collision, overhearing, idle listening, and over emitting. Reliable and energy efficient data transmission are required to prolong the network lifetime. This paper presents the testbed development of an enhanced lightweight medium access (eL-MAC) protocol which introduces distributed time slot assignment and slotting communication mechanism. Therefore, with eL-MAC, idle listening, overhearing and hidden terminal will be eliminated where nodes transmit in its own time slot and sleep in other time slot if there is no activity. This will reduce energy consumption as nodes are active when transmitting and receiving and idle only in the beacon session. The testbed is developed using TelosB sensor nodes programmed with TinyOS. NesC programming language was used to implement the protocols in the WSN module. Experimental results were compared to the results obtained from simulation. As expected, there is a slight degradation in throughput and packet received ratio in the experiment but is consistent for all values. This concludes that the developed testbed reflects the eL-MAC protocol and has been successfully implemented.

Communications in Computer and Information Science: Techniques on Relaying for LTE-Advanced Network

Relay-assisted cellular network is a major concern in research studies around the world as it can aid the cell to achieve coverage extension and capacity enhancement. Long Term Evolution-Advanced (LTE-A), a candidate from Third Generation Partnership Project (3GPP) has include relaying as one of its key technologies to meet International Mobile Telecommunications (IMT) Advanced requirements. This article focuses on relay architectures from LTE-A and the types of relay defined in the standard. Pros and cons of developed relaying strategies, transmission schemes together with relay selection pairing scheme are also reviewed. This article also provides simulation results comparing performance between transmission with and without the usage of relay. In addition, recent studies extending the relaying concept such as cognitive and cooperative relaying as a hot research topic are also discussed.

Performance analysis for cooperative relay with power control scheme over fading channel

Performance of a system is determined by the probability of error of the channel. In this paper, the error probability of cooperative relay channel is analyzed for Quadrature Phase Shift Keying (QPSK) using simple linear block coding. Focusing on a network with single source to destination with one relay station, the upper bound of symbol error rate (SER) is derived. A power control scheme is also proposed to improve the performance of the system. Computer simulations confirm the presented mathematical analysis.