N. Fisal

Real-Time Routing in Wireless Sensor Networks

In wireless sensor networks (WSNs), sensors gather information about the physical world and base station makes appropriate decision upon the environment. This technology enables users to effectively sense and monitor from a distance. WSN are slated to become very popular in the near future. It allows video/audio streaming to be transferred between sensor nodes in real-time. WSN can use real-time forwarding which means messages in the network are delivered according to their end-to-end deadlines (packet lifetime). This paper proposes a novel real-time routing protocol based on link quality, packet velocity over one-hop and remaining power in the sensor devices. The proposed routing has been successfully studied and verified through simulation and real test bed implementation. The results in this paper show that the proposed routing protocol has efficient power consumption, high packet delivery ratio and minimum control packet overhead in WSNs.

Power reduction quadrant-based directional routing protocol (Q-DIR) in Mobile Ad Hoc Network

Flooding of request packet in the route discovery phase in Mobile Ad Hoc Network (MANET) creates a broadcast storm which increases the probability of packet collisions. With location information of the destination node, the source node and also of the current node, route request will be more directed towards destination since nodes that are within the directed region will participate in the routing process. Hence, nodes that are out of the trajectory will ignore the packet and thus reduces the number of broadcasting nodes and consequently, less probability of collisions. This paper presents Quadrant- based directional routing protocol (Q-DIR) algorithm that limits the broadcast region to a quadrant where the destination node and source node are located. Q-DIR utilizes location information of the destination node, the source node and the current node. With Q-DIR as a reactive routing protocol, routing overhead will be reduced and consequently, reduces total network power consumption through limited flooding. This paper will present the performance of Q-DIR in a densely populated network of 49 nodes.

MPEG-4 video transmission using distributed TDMA MAC protocol over IEEE 802.15.4 wireless technology

The issues of green technology nowadays give an inspiration to the researcher to make all the future design to be energy efficient. Medium Access Control (MAC) layer is the most effective layer to provide energy efficient due to its ability to control the physical radio directly. One of the important applications in the future is a video transmission that can be transmitted with low-cost and low power consumption. MPEG-4 is one of the international standards for moving video. MPEG-4 provide better compression and primarily design at low bit rate communication. In order to achieve good quality for video application, the design at MAC layer must be strong. Therefore, to increase the performance of the MPEG-4 in IEEE 802.15.4, in this paper we propose a cross layer design between MAC layer and Application layer. A priority queue will be implemented at MAC scheduling depends on the level of frame important in MPEG-4 format frame. A distributed Time division Multiple Access (TDMA) will be used for MAC protocol to provide reliable data transmission for high priority frame.

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.

Interference management for irregular cell geometry heterogeneous networks

Recent trends of bandwidth hungry application services in cellular communication put tremendous pressure on the network operators to significantly increase the system capacity. Within such perspective, the deployment of femtocells offers reliable and cost effective means to enhance the system capacity and indoor coverage. However, the random deployment of femtocells challenges several technical aspects of the existing cellular systems. The most obvious challenge is the occurrence of interference, which is more severe if spectrum management is not carefully considered. Fractional Frequency Reuse (FFR) has emerged as an attractive interference management technique due to its low complexity and significant coverage improvement. However, most of the previous work analyzes the performance of FFR for perfect geometry based models, whereas no practical deployment has such symmetry. In this paper we investigate the performance of FFR for cellular network based on irregular cell geometry. Furthermore, a novel FFR scheme is proposed for two-tier (macro-femto) network and the capacity of the system is evaluated. It is shown that the proposed scheme outperform the conventional frequency allocation schemes in term of capacity and cell edge performance.

Optimal user selection for decision making in cooperative sensing

In enabling spectrum-aware communication protocol of cognitive radio (CR), spectrum sensing becomes the key technology for unlicensed or cognitive users (CUs) to exploit the unused spectrum of primary users (PUs) via opportunistic spectrum access (OSA). A longer sensing time will result in a higher detection probability and hence, a better protection for the PU. However, in a fixed frame size, this leads to reduced data transmission time and hence, decreases the achievable throughput of CUs. In this paper, particle swarm optimization (PSO) formulation is proposed to address this sensing-throughput tradeoff under distributed cooperative sensing scenario using hard combining fusion schemes to determine the presence of PUs. The objective is to optimize the sensing time and achieve maximized throughput for CUs while sufficiently protecting the PUs. The findings show that jointly optimizing the sensing time and the parameter k of k-out-of-N rule outperforms other optimized fusion schemes of OR, AND and Half-Voting significantly in terms of achievable throughput and reliability.

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.

Cognitive Radio Simplex Link Management for Dynamic Spectrum Access Using GNU Radio

The explosion of new wireless communication technologies and services has led to the increase in spectrum demand. The fixed spectrum allocation approach has resulted in current day spectrum scarcity and poorly utilized licensed spectrum. In order to overcome these problems, a new concept of accessing the spectrum, defined as dynamic spectrum access (DSA), is proposed. DSA mechanism enables unlicensed or cognitive users (CUs) to temporarily utilize a spectrum hole for a period of time. In this work, DSA based on cognitive radio (CR) technology is chosen due to its features of able to sense, learn, adapt and react according to the environment. The proposed design of the system consists of four main functional blocks: spectrum sensing, spectrum management, spectrum decision and data transmission. Spectrum management is further divided into three parts: spectrum identification, synchronization and link management. This paper focuses on the establishment of link management module in simplex mode. The implementation is done using GNU Radio and USRP SDR platform. The GMSK based and IEEE 802.15.4 standard radios, equipped with DSA capability using CR technique, have been developed and tested. The results show that the link module has successfully maintained CU’s seamless communication while the DSA mechanism offers significant improvement in terms of achieved packet rate ratio (PRR).

Reconfiguring Software Defined Radio platform for Dynamic Spectrum Access

Traditional static spectrum allocation policy has resulted in current day spectrum scarcity and inefficient spectrum utilization. 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, CU is implemented on Software Defined Radio (SDR) platform consisting of GNU Radio and USRP. This platform is then reconfigured for DSA based on Cognitive Radio (CR) technology which features include abilities 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. In this paper, we address the implementation of DSA based CR on IEEE802.15.4 standard. The result shows a significant improvement in term of Packet Reception Rate (PRR) for CU with DSA based CR system compared to the system without DSA capability.

A dynamic approach for location management in IP-based networks

An approach is presented to facilitate location management of mobile hosts using a distributed intelligent architecture. Intelligence is imbued onto an IP-based network as an overlay to provide mobility services. The overlay consists of a three-layered multi-agent architecture that would provide the necessary signaling and control information to support mobility. Dynamism in the network is accomplished through the use of this dasiaagencypsila. This represents a departure from traditional methods of providing mobility services to hosts.