Alper Karahan

A Novel Cross-layer Routing Protocol for Increasing Packet Transfer Reliability in Mobile Sensor Networks

In mobile sensor networks (MSNs), sensor data is generally transferred via mobile sensor nodes by multi-hop fashion. Because of the mobility of the nodes in the network, the efficient routing protocols are needed to ensure end-to-end route reliability while incurring minimal power consumption and packet delay. In this study, we developed a new routing protocol to meet these requirements for MSNs based on a cross-layer interaction among five reference layers (application, transport, network, MAC and physical). The proposed protocol primarily exploits the idea of interaction among these five layers all-in-one protocol. Its primary goals are (i) to discover the most reliable route in network, (ii) to sustain the route reliability and (iii) to be energy efficient and delay aware. It has been designed, modeled and simulated by using OPNET Modeler simulation software. The simulation results of the proposed protocol have been compared to three well known routing protocols (i.e., AODV, Leach-Mobile, CBR-Mobile). According to the obtained results, the proposed protocol outperforms its counterparts in terms of route reliability and end-to-end delay performances.

A new MAC protocol for broadband wireless communications and its performance evaluation

This paper presents a new Time Division Multiple Access/Frequency Division Duplexing (TDMA/FDD) based Medium Access Control (MAC) protocol for broadband wireless networks, supporting Quality of Service (QoS) for real-time multimedia applications. It also gives the Call Blocking Probability (CBP), packet end-to-end delay and utilization analysis of different service classes, as they are most essential performance criterions in broadband wireless network assessment. The Connection Admission Control (CAC) mechanism in the proposed MAC efficiently organizes the bandwidth allocation for different service classes by means of a fairness based scheduling algorithm. In addition, the simulation model of the proposed MAC scheme is realized by using OPNET Modeler network simulator. The results of the analytical calculations for the CBPs are compared to those of the simulation of the proposed MAC, thus validity of the MAC protocol is proved.

isMOTE: Mobile sensor and actuator node design for Wireless Body Area Networks

As a result of advances in wireless communication technologies, while sensor nodes that can sense physical signals are constantly evolving; their power consumption values and dimensions are dwindling. Thus, their usage on health-care applications in daily life is increasing. In this study, a wireless mobile sensor and actuator node which is called isMOTE is designed and carried out for Wireless Body Area Networks (WBAN). isMOTE nodes are designed as a low-cost solution to realize different Wireless Sensor Networks (WSN), and they make academic and experimental studies possible on MAC protocols and routing algorithms. isMOTE, evaluated in terms of features, differentiates from counterparts due to the low-cost, high communication speed and low energy consumption.

Energy efficient hybrid MAC protocol for large scale wireless sensor networks

In this study, a hybrid, energy efficient MAC (Medium Access Control) protocol has been developed for usage in dense WSN (Wireless Sensor Network) applications. In the designed hybrid MAC, favorable aspects of both CSMA (Carrier Sense Multiple Access) and TDMA (Time Division Multiple Access) techniques are considered. Consequently, a MAC protocol which is more energy efficient than both CSMA and TDMA-based MAC protocols is aimed. Therefore, with the combination of CSMA which responses to the events rapidly and TDMA which reduces the collisions and unnecessary channel listening, high system throughput and node energy efficiency are obtained.

A cluster based routing approach in LTE ad-hoc networks

In this work, a new routing algorithm which allows smart terminals to join the ad-hoc network at random times in order to carry out data transmission using Long Term Evolution (LTE) infra-structure has been developed and simulated by using OPNET Modeler. The routing scheme has been realized by clustering the terminals according to some predefined physical layer parameters and by utilizing Carrier Sense Multiple Access (CSMA) and Time Division Multiple Access (TDMA) schemes. After determining the cluster members and cluster head, time slot allocation process is carried out per cluster head and data gathered from the cluster members are relayed to the main server. The results show that the proposed algorithm utilizes less control packets during the path discovery than the widely used Ad hoc On-Demand Distance Vector (AODV). Besides, it has less route discovery time than AODV for all network loads.

Performance aspects of isMAC protocol for WBANs using isMOTES

Wireless body area networks (WBAN) consist of wireless smart sensor nodes placed on, in or around the human body for medical monitoring systems, entertainment and ubiquitous computing. The nodes in WBAN are usually battery-powered and they send sensed data from a human body, including heart rate, temperature and ECG, etc. to the medical centre to monitor the health situation of individuals. One of the major problems of a WBAN is to prolong the sensor network lifetime. To solve this major problem, different approaches are used, but the most effective one is a well-designed MAC protocol. This paper investigates three inter-BAN communication methods and suggests a coordinator node rotating mechanism to ensure energy balance among the sensor nodes and to extend the network lifetime up to 59%.