N. M. Abdul Latiff

Proactive integrated handoff management in CR-MANETs: A conceptual model

In cognitive radio (CR), CR users or also known as secondary users (SUs) are considered as “visitors” to the licensed spectrum. During the case when the primary user (PU) claims the band of the spectrum that is occupied by the SU, the SUs ongoing call must be transferred to another unused spectrum band. The variation in spectrum band is called spectrum mobility. Spectrum mobility leads to a new handoff in cognitive radio networks, namely spectrum handoff, in which the SUs handover their spectrum band and continue their ongoing calls on an unused spectrum band with different frequency upon the appearance of the PU. In this paper, we investigate a new concept of integrated handoff management in mobile cognitive radio Ad hoc networks (CR-MANET), along with a conceptual framework, its connections and related handoff algorithm.

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).

Interference aware channel assignment (IACA) for cognitive wireless mesh networks

In this paper, we present the end-to-end interference aware concept of Cognitive wireless mesh network (CWMN). CWMN is the leading upcoming technology with the advantage of cognitive radio (CR). We demonstrate that the end-to-end interference model has the ability to perform better from SINR base model. To enhance the utilization of the unused spectrum the channel selection strategy should have some awareness mechanism to avoid interference. In this paper, novel interference aware channel assignment (IACA) algorithm is proposed. The end-to-end delay, packet delivery ratio and the throughput is used to estimate the performance of the proposed algorithm. The numerical results demonstrate that the proposed algorithm is closer to the optimum resource utilization.

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.

Integrated handoff management in cognitive radio mobile ad hoc networks

The paper introduces proactive integrated handoff management (IHM) scheme in cognitive radio mobile ad hoc networks (CR-MANETs) through an established route. This scheme considers the primary user (PU) activity, secondary user (SU) mobility and channel heterogeneity in the spectrum handoff decision. To reduce the handoff delay, handoff thresholds are used. When the spectrum handoff cannot be done due to the SUs mobility, a local flow handoff (LFH) is performed to find a node in the vicinity of a potential link breakage where the data flow is transferred to the node. The proposed proactive IHM scheme predicts the cognitive link availability that considers the interference to PUs to estimate the maximum link availability time. The availability time is then used in the channel allocation scheme. The results emphasized on improvement of the route maintenance probability using LFH. It is also verified that the number of handoff needed is significantly decreased using the proposed proactive IHM scheme.

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.

Energy efficient protocol in wireless sensor networks using mobile base station

A wireless sensor network is made up of battery operated devices that have sensing, processing and transmitting capabilities. The design constraint of a wireless sensor network is its network lifetime. In order to prolong the network lifetime, the sensor nodes must be able to use the minimal energy to transmit data to the base station. Hence, an efficient protocol is needed. One method to reduce the energy consumption among sensor nodes is to use mobile base station instead of static base station. This approach allows the base station to move closer to sensor nodes in order to reduce the communication distance between them. Consequently, it decreases the energy utilisation of the network. Another approach is by using the clustering method in which the sensor nodes in a network are grouped into clusters and only the cluster heads relay the aggregated data to the base station. However, this approach would be a burden to the cluster heads. Hence, the task of the cluster head could be alternated among sensor nodes so that the energy load among all sensor nodes is balanced. This paper proposes an energy efficient protocol for wireless sensor networks using mobile base station which is based on the clustering approach with role rotation.

Load distributed routing protocol for wireless mesh networks

This paper presents a routing protocol called Load Distributed Mesh Routing (LDMR) that is developed for Wireless Mesh Network (WMN) with IEEE 802.11 standard. The LDMR protocol decides on the potential next hop nodes based on a quadrant and distance information. Then, the Next Hop Forwarding (NHF) decision is used to select the best next hop nodes based on Packet Success Rate (PSR) and maximum velocity of a packet. The proposed LDMR protocol has been implemented and verified through simulation in Network Simulator 3 (NS3) for both randomly distributed and grid network topologies. The network performance of LDMR is compared with the existing routing protocols, which are Ad Hoc on Demand Distance Vector (AODV) and Hybrid Wireless Mesh Protocol (HWMP). Simulation results show that the throughput of LDMR is improved when compared to HWMP and AODV in most of the simulated cases. The LDMR protocol also maintains a low average end-to-end delay which is lower than 0.01s in almost all cases when compared with AODV and HWMP protocols.

Hybrid Backtracking Search Optimization Algorithm and K-Means for Clustering in Wireless Sensor Networks

Rapid technology evolvement in the area of wireless sensor networks (WSNs) has led to many application-specific protocols that are particularly developed to cover different fields of usage and various network scenarios. Energy efficiency is one of the apparent challenges facing WSNs which has impacted immensely on the network performance. Hence, clustering protocols that eliminate energy inefficiencies in the network is essential. As finding an optimal set of cluster heads is an NP-hard problem, the application of heuristic algorithm is required to produce good clustering. In this paper, we propose a clustering solution for WSNs using a hybrid algorithm based on Backtracking Search Optimization Algorithm (BSA) and K-Means. A fitness function that incorporates aspects such as expected energy consumption in the network and maximum intra-cluster distance is utilized to address the problem of energy efficiency. Performance comparison against well-known clustering protocols such as LEACH and LEACH-C reveals that the hybrid of BSA and K-Means clustering algorithm is able to deliver more data to the base station and extends the network lifetime.

Collaborative beamforming null-steering array for wireless sensor networks

This paper presents a method of collaborative beamforming (CB) of organizing sensor node location in linear array for wireless sensor network (WSN). Appropriate Appropriate selection of active CB nodes and cluster are needed each time to perform CB in WSNs. The nodes are modeled in linear array organization in order to perform as a perform as a linear antenna array (LAA). This newly proposed proposed CB null-steering linear array (CBNL) that is able to able to solve the null-steering problem is then presented. presented. Performances in the form of normalized power power gains are given. Analyses obtained are compared with with previous work. The findings showed an enhanced CBNL CBNL that posses null-steering capability.