Tamer Abdelkader

SGBR: A Routing Protocol for Delay Tolerant Networks Using Social Grouping

Delay tolerant networks (DTN) are characterized by a lack of continuous end-to-end connections due to node mobility, constrained power sources, and limited data storage space of some or all of its nodes. To overcome the frequent disconnections, DTN nodes are required to store data packets for long periods of time until they come near other nodes. Moreover, to increase the delivery probability, they spread multiple copies of the same packet on the network so that one of them reaches the destination. Given the limited storage and energy resources of many DTN nodes, there is a tradeoff between maximizing delivery and minimizing storage and energy consumption. In this paper, we study the routing problem in DTN with limited resources. We formulate a mathematical model for optimal routing, assuming the presence of a global observer that can collect information about all the nodes in the network. Next, we propose a new protocol based on social grouping among the nodes to maximize data delivery while minimizing network overhead by efficiently spreading the packet copies in the network. We compare the new protocol with the optimal results and the existing well-known routing protocols using real life simulations. Results show that the proposed protocol achieves higher delivery ratio and less average delay compared to other protocols with significant reduction in network overhead.

Machine-to-Machine (M2M) communications

Machine-to-Machine (M2M) communication is a promising technology for next generation communication systems. This communication paradigm facilitates ubiquitous communications with full mechanical automation, where a large number of intelligent devices connected by wired/wireless links, interact with each other without direct human intervention. As a result, M2M communication finds applications in wide areas such as smart grids, e-healthcare, home area networks, intelligent transportation systems, environmental monitoring, smart cities, and industrial automation. However, distinctive features in M2M communications form different challenges from those in human-to-human communications. These challenges need to be addressed, or otherwise it is not easy for this paradigm to gain trust of people. To understand M2M communications deeply, this paper presents a comprehensive review of M2M communication technology in terms of its system model architecture proposed by different standards developing organizations. This mainly includes 3GPP, ETSI, and oneM2M. Further, we have investigated distinctive features of various M2M applications and their supporting attributes, the M2M data traffic and their characterization, various M2M standardization bodies and their unique tasks, and potential M2M communication challenges and their proposed state-of-the-art solutions, followed by future research directions.

A Socially-Based Routing Protocol for Delay Tolerant Networks

Networks in which nodes are intermittently connected, and have limited storage space and power, are termed Delay Tolerant Networks (DTN). To overcome these conditions, DTN routing protocols require nodes to store data packets for long periods of time until they contact with each other. In addition, they spread multiple copies of the same packet in the network to increase the probability of one of them reaching the destination. Long-term storage and multiple transmissions require large buffer space and non-restricted power availability which is hard to exist in DTN. In this paper, we study the routing problem in DTN with limited resources. We formulate a mathematical model for optimal routing, assuming the knowledge of present and future nodes contact and buffer space. After that, we analyze the previously developed heuristic protocols, and we propose a new protocol based on social relations between the nodes to avoid redundant copying of packets. Simulation results show that the proposed protocol significantly reduces energy consumption and provides better delivery ratio compared to other protocols.

Choosing the objective of optimal routing protocols in Delay Tolerant networks

Networks in which nodes are sparsely distributed and, therefore, are disconnected for long periods of time, are termed Delay Tolerant networks (DTN). The intermittent connection, together, with the limited resources of mobile nodes, mainly power and memory, created a challenging environment for data networking in DTN. Routing protocols developed for DTN tend to discover and select the minimum end-to-end delay paths to destinations assuming that these paths provide the highest delivery rate. To achieve this goal, they spread many copies of the same packet, ignoring the limitedness of storage space and power sources. In this paper, we study this problem by building a mathematical model for optimal routing in DTN. We compare the results of implementing three objectives for this model: minimizing the end-to-end delay, minimizing the end-to-end number of hops, and maximizing the delivered messages. We study and analyze the impact of varying the buffer space, the traffic load and the packets time-to-live (TTL) on the three objectives. Results show that minimizing the number of hops provides higher delivery ratio than minimizing the delay, which contradicts the previous assumption. In addition, minimizing the number of hops significantly reduces the number of transmissions which results in saving energy.

Geocast Routing in Vehicular Networks for Reduction of CO2 Emissions

Pollution and gas emissions are increasing and negatively impacting global warming. Consequently, researchers are looking for solutions that save environment. Greenhouse gas (GHG) emissions from vehicles are considered to be one of the main contributing sources. Carbon dioxide (CO 2) is the largest component of GHG emissions. Vehicular networks offer promising technology that can be applied for reduction of CO 2 emissions. One of the major applications of vehicular networks is Intelligent Transportation Systems (ITS). To exchange and distribute messages, geocast routing protocols have been proposed for ITS applications. Almost all of these protocols evaluate network-centric performance measures, instead of evaluating the impact of the protocol on the vehicular system. Nowadays, the harmful effects of air pollutants have been the subject of considerable public debate. Vehicles’ stop-and-go condition, high speed, and high accelerations are environmentally unfriendly actions (EUF) that increase the amount of emissions. These actions can happen frequently for vehicles approaching a traffic light signal (TLS). Therefore, we propose a new protocol named environmentally friendly geocast (EFG), which focuses on minimizing CO 2 emissions from vehicles approaching a TLS by avoiding the EUF actions. Simulation results demonstrate that the proposed protocol can achieve effective reduction of vehicle CO 2 emissions.

An eco-friendly routing protocol for Delay Tolerant Networks

In sparse mobile networks, nodes are connected at discrete periods of time. This disconnection may last for long periods in suburban and rural areas. In addition, mobile nodes are energy and buffer sensitive, such as in mobile sensor networks. The limited power and storage resources, combined with the intermittent connection have created a challenging environment for inter-node networking. This type of networks is often referred to as Delay Tolerant networks (DTN). Routing protocols developed for DTN focused on minimizing the end-to-end delay as a means of maximizing number of delivered packets. Therefore, they tend to spread many copies of the same packet into the network, assuming the availability of sufficient storage space and power. A key factor to help maintain a clean environment, is the reduction of energy consumption which can be achieved by decreasing number of transmissions in the network. In this paper, we formulate a mathematical model for optimal routing in DTN to minimize number of transmissions. In addition, we study and analyze the DTN heuristic routing protocols. After that, we propose an eco-friendly routing protocol, EFR-DTN, that efficiently uses simple information provided from the network to deliver packets with higher delivery ratio and minimum energy consumption than the other protocols. Simulation results show the outperformance of the proposed protocol under different buffer capacities, traffic loads, packet TTL values, and number of nodes in the network.

Adaptive backoff scheme for contention-based vehicular networks using fuzzy logic

In contention-based wireless networks, collisions between data packets can be reduced by introducing a random delay before each transmission. Backoff schemes are those that provide the backoff interval from which the random delay is drawn. In this paper, we propose a new scheme which calculates the backoff interval dynamically according to the network conditions. The network conditions are measured locally by each node, which supports the distributed nature of the vehicular networks. The measures are used by a fuzzy inference system to calculate the backoff interval. We compare the proposed scheme with other known schemes: the binary exponential backoff (BEB), the sensing backoff algorithm (SBA) and an optimal scheme which requires the knowledge of the number of nodes in the network (Genie). The evaluation measures are the throughput and fairness. Results show an improvement of the fuzzy-based schemes compared to the BEB and SBA, especially for large number of nodes in the network.

Using fuzzy logic to calculate the Backoff Interval for contention-based vehicular networks

In contention-based wireless networks, packet collisions are considered the main source of data loss. Retransmission of the lost packet is done several times until an acknowledgment of successful reception (ACK) is received or the maximum number of retries is reached. The retransmission delay is drawn randomly from an interval, called the Backoff Interval. A good choice the backoff interval reduces the number of collisions and, therefore, increases the throughput and decreases the energy consumed in retransmissions. In this paper, we propose a backoff scheme based on fuzzy logic. The new scheme depends on locally measured data to estimate the backoff interval which supports the distributed nature of the vehicular networks. We present several versions of the Fuzzy Backoff scheme and compare them with other known schemes: the binary exponential backoff (BEB), and an optimal scheme which requires the knowledge of the total number of nodes in the network. We used throughput, fairness, and energy consumption as performance measures for evaluation. Results show an improvement of the fuzzy-based schemes compared to the BEB, and approaching the optimal results.

A Localized Adaptive Strategy to Calculate the Backoff Interval in Contention-Based Vehicular Networks

The dynamic nature of vehicular networks with their fast changing topology poses several challenges to setup communication between vehicles. Packet collisions are considered to be the main source of data loss in contention-based vehicular networks. Retransmission of collided packets is done several times until an acknowledgment of successful reception is received or the maximum number of retries is reached. The retransmission delay is drawn randomly from an interval, called the backoff interval. A good choice of the backoff interval reduces the number of collisions and the waiting periods of data packets, which increases the throughput and decreases the energy consumption. An optimal backoff interval could be obtained if global network information spread in the network in a short time. However, this is practically not achievable which motivates the efficient utilization of local information to approach the optimal performance. In this paper, we propose a localized adaptive strategy that calculates the backoff interval for unicast applications in vehicular networks. The new strategy uses fuzzy logic to adapt the backoff interval to the fast changing vehicular environment using only local information. We present four schemes of that strategy that differ in their behavior and the number of inputs. We compare the proposed schemes with other known schemes, binary exponential backoff, backoff algorithm, and an optimal scheme, in terms of throughput, fairness, and energy consumption. Results show that by proper tuning of the fuzzy parameters and rules, one of the proposed schemes outperform the other schemes, and approach the optimal results.

Optimal link scheduling for multimedia QoS support in Wireless Mesh Network

Supporting multimedia quality of service (QoS) is a necessary and critical requirement for next generation wireless networks. Wireless Mesh Networking is envisioned as an economically viable paradigm and a promising technology for supporting multimedia QoS. The non-mobile mesh routers with the capability of having less-constrained transmission power are the distinct characteristics for this type of wireless networks. Exploiting these capabilities provides better solutions for allocating network resources such as bandwidth, and supports satisfying QoS requirements. Using these characteristics, we propose a QoS-aware link scheduling scheme for wireless mesh networks (WMNs). The scheme allocates time slots and transmission power to the network nodes in a way that maximizes the spatial reuse of the network bandwidth. In this paper, we study two cases: a mesh network with battery-powered devices and a network with outlet-powered devices. Using computer simulations, we show that the QoS constraints for the different traffic flows can be met, for the two cases, in addition to maximizing the network throughput.