S. H. S. Ariffin

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).

Enabling dynamic spectrum access for cognitive radio using software defined radio platform

This Spectrum occupancy measurement in many countries shows sporadic and poorly utilized licensed radio spectrum due to the outdated exclusive spectrum access policy. Dynamic Spectrum Access (DSA) technique allows cognitive (unlicensed) user (CU) to opportunistically transmit in a primary (licensed) user (PU) frequency band for a given time if it does not detect any ongoing operations. In this work, DSA is realized using cognitive radio (CR) technology due to its features of able to sense, learn, adapt and react according to the environment. The proposed design of the DSA based CR system consists of four main functional blocks: spectrum sensing, spectrum management, spectrum decision and data transmission. The implementation is done using GNU Radio and Universal Software Radio Peripheral (USRP) Software Defined Radio (SDR) platform. The result shows a significant improvement in term of Packet Reception Rate (PRR) in DSA based CR systems compared to the system without DSA capability.

Optimizing achievable throughput for cognitive radio network using swarm intelligence

Cognitive radio (CR) technology allows a secondary or cognitive user (CU) to opportunistically access frequency band of a primary user (PU) when it is not in use. However, a CU needs to perform spectrum sensing periodically to avoid causing harmful interference and thereby protecting the quality of service of PUs. A conventional frame structure for CR operation consists of sensing time slot and data transmission time slot which run consecutively. Basically, a longer sensing time produces a higher probability of detection and therefore, better PU protection. However, longer sensing time will reduce the amount of time for data transmission and hence affects the achievable throughput of a CU. In this paper, we study the fundamental tradeoff between sensing time and achievable throughput of the CUs. Based on energy detection scheme, we propose and investigate the feasibility of using Particle Swarm Optimization (PSO) in the design of sensing slot duration to maximize the achievable throughput for CUs for a given frame duration. The results show an encouraging 8.89% increase in throughput with respect to the probability of false alarm, a reduced sensing time by 80% while achieving 97.8% of normalized throughput for CU system with PSO.

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.

An improved authentication key management scheme for Multihop relay in IEEE 802.16m networks

IEEE 802.16m Multihop relay network is assiduously developing to accomplish high capacity services with large cell coverage. However due to lack of physical boundaries and injection of distributed relays, it is known to be more vulnerable to security holes as a trade off. In this paper we propose a new distributed authentication key scheme for Multihop Relays IEEE 802.16m network service. The propose scheme uses decode and forward relays with localized authentication. The scheme works in distributed authentication to authenticate Subscriber station (SS) and Relay stations (RS) at initial network entry. Our new imprpoved distributed scheme utilizes healthy security issues and the Multihop Relay network application features. Both analysis and performance evaluation shows that our scheme can significantly increases the network throughput and reduce the security holes as well as communication overheads.

Performance comparison of AODV and HWMP routing protocols in wireless mesh networks

Wireless mesh networks (WMNs) have gain attention from researchers in telecommunication engineering field due to its potential to provide low cost internet broadband access, wireless local area network coverage and network connectivity for stationary or mobile host. This network consists of multiple wireless routers that are used to relay each others packet in multi-hop fashion. Hence, routing protocol plays an important part in maintaining the connectivity of WMNs. In this paper, two routing protocols, Ad hoc On-demand Distance Vector (AODV) and Hybrid Wireless Mesh Routing Protocol (HWMP) are compared in terms of their performance in WMNs. A random wireless mesh topology with router nodes is modelled in Network Simulator 3 by assuming that the router nodes are connected to its client nodes. The simulations are performed in two different topologies with varied number of nodes. Three merits are taken into account when making the comparisons which are packet delivery fraction, throughput, and end-to-end delay. The simulation results demonstrate that HWMP is more suitable to be applied in WMNs compared to AODV.

Development of TelG mote for Wireless Biomedical Sensor Network (WBSN) application

Wireless Sensor Network (WSN) consists of sensor nodes that interact with each other to collectively monitor environmental or physical conditions at different location for the intended user. One of its potential deployments is in the form of Wireless Biomedical Sensor Network (WBSN) to measure physiological signals. The WBSN applications would allow the medical practitioners to continuously monitor and update the status of a patient remotely. This paper focuses on the development of a wireless sensor node platform for WBSN application which complies with IEEE 802.15.4 standard and operates in 2.4 GHz ISM (industrial, scientific and medical) band. The initial state of WBSN development is the design of the wireless sensor node called TelG. The main features of TelG include low power consumption, wearable, flexible and small size. It is then embedded with a self-built operating system called WiseOS to support customized operations.

A route selection algorithm for WiMAX Mobile multi-hop relay networks

Next generation of wireless broadband network such as WiMAX MMR networks and LTE Advanced support high quality multimedia services with high data transmission rate. Most of the current broadband operates at high frequency and thus has limited transmission range. Multi-hop relaying technology is seen as an efficient solution that could enhance coverage and improves system capacity. However, overall system performances worsen as the number of hop increases. Providing efficient route selection is one of the key issues to be tackled to improve overall system performance in multi-hop relay network. In this paper, we propose route selection algorithm based on channel condition for WiMAX Mobile multi-hop relay network. We conducted simulation study to evaluate the performance of the proposed scheme.

Route optimization in proxy mobile IPv6 test-bed via RSSI APPs

Proxy Mobile IPv6 is the new protocol, but there is a problem on Localized Routing (LR) algorithm which it is not ready build in PMIPv6 protocol. As for this in PMIPv6 in RFC5213 address the needed to enable Localized Routing (LR) but it not specify a complete procedure to establish Route Optimization (RO). RFC6279 state the problem statement on LR issue with several scenarios to tackle down. LR is important especially to minimize data delay and decrease handover latency due to the un-optimized data route. Data packets on PMIPv6 protocol without LR always need to travel to Local Mobility Anchor (LMA) with result in end-to-end delay. Therefore, this paper propose the new LR algorithm to optimized data route for selected scenarios to reduce handover and data packet delay. This paper also will illustrate the setting up of the PMIPv6 and test-bed performance.

Optimizing Distributed Cooperative Sensing Performance Using Swarm Intelligence

Cognitive radio (CR) technology offers attractive solution to overcome spectrum scarcity problem and improve spectrum utilization. Opportunistic spectrum access concept adopted by a CR network allows unlicensed or cognitive users (CUs) to access a frequency band that is not in use by the licensed or primary users (PUs). In enabling such spectrum-aware communication protocol, spectrum sensing becomes the fundamental requirement to exploit the unused spectrum and effectively protect the quality of service (QoS) of PUs. An increase in sensing time results in a higher detection probability (P d ) and lower false alarm probability (P f ), which leads to better protection of the primary users from harmful interference in addition to improved utilization of the available unused spectrum. However, this will reduce the amount of time for data transmission and hence, affects the achievable throughput of CUs. In this paper, this sensing-throughput tradeoff is addressed in terms of distributed approach of cooperative channel sensing. In order to find the optimal sensing time that maximizes the throughput of an OSA based CR network, the decision fusion scheme of OR rule are subjected to particle swarm optimization (PSO). The results show that a lower sensing time is achieved under PSO based cooperative sensing. The maximum achievable normalized throughput also increases with the increase of sensing terminals under optimal fusion scheme compared to normal fusion technique.