Mesut Günes

ARA-the ant-colony based routing algorithm for MANETs

A mobile ad-hoc network (MANET) is a collection of mobile nodes which communicate over radio. These kind of networks are very flexible, thus they do not require any existing infrastructure or central administration. Therefore, mobile ad-hoc networks are suitable for temporary communication links. The biggest challenge in this kind of networks is to find a path between the communication end points, what is aggravated through the node mobility. In this paper we present a new on-demand routing algorithm for mobile, multi-hop ad-hoc networks. The protocol is based on swarm intelligence and especially on the ant colony based meta heuristic. These approaches try to map the solution capability of swarms to mathematical and engineering problems. The introduced routing protocol is highly adaptive, efficient and scalable. The main goal in the design of the protocol was to reduce the overhead for routing. We refer to the protocol as the ant-colony-based routing algorithm (ARA).

RIOT OS: Towards an OS for the Internet of Things

The Internet of Things (IoT) is characterized by heterogeneous devices. They range from very lightweight sensors powered by 8-bit microcontrollers (MCUs) to devices equipped with more powerful, but energy-efficient 32-bit processors. Neither a traditional operating system (OS) currently running on Internet hosts, nor typical OS for sensor networks are capable to fulfill the diverse requirements of such a wide range of devices. To leverage the IoT, redundant development should be avoided and maintenance costs should be reduced. In this paper we revisit the requirements for an OS in the IoT. We introduce RIOT OS, an OS that explicitly considers devices with minimal resources but eases development across a wide range of devices. RIOT OS allows for standard C and C++ programming, provides multi-threading as well as real-time capabilities, and needs only a minimum of 1.5 kB of RAM.

Ant-routing-algorithm for mobile multi-hop ad-hoc networks

A mobile ad-hoc network (MANET) is a collection of mobile nodes which communicate over radio. These networks have an important advantage, they do not require any existing infrastructure or central administration. Therefore, mobile ad-hoc networks are suitable for temporary communication links. This flexibility, however, comes at a price: communication is difficult to organize due to frequent topology changes.The Ant-Colony-Based Routing Algorithm (ARA) is highly adaptive, efficient and scalable. It is based on ant algorithms which are a class of swarm intelligence. Ant algorithms try to map the solution capability of ant colonies to mathematical and engineering problems.In this paper we present some extensions to the basic idea and show through simulation results the performance gain and compare it with AODV and DSR.

How to Study Wireless Mesh Networks: A hybrid Testbed Approach

Simulation is the most famous way to study wireless an mobile networks since they offer a convenient combination of flexibility and controllability. However, their largest disadvantage is that the gained results are difficult to transfer into reality since not only the abstraction of the upper network layer are typically high, but also the environment of mobile and wireless networks is very complex. This is due to two reasons. First there are typically many simplifications in the models of the upper networking layers, and second the environment of mobile and wireless networks is in particular complicated and thus difficult to be considered in all details. In this paper we introduce UMIC-mesh, a hybrid testbed approach, that consists of real mesh nodes and a virtualization environment. On the one hand the virtualization allows the development and testing of software as if it was executed on real mesh routers, but in a more repeatable and controllable way. On the other hand the results and conclusions gained by a software evaluation in the testbed can be easily transferred into reality, since the testbed represents a high degree of realism.

The performance of the TCP/RCWE enhancement for ad-hoc networks

Mobile ad-hoc networks (MANET) enable the communication of mobile wireless nodes without any pre-defined infrastructure. Therefore, they are predestined for future mobile applications. To use existing applications and to inter-operate with the world wide Internet, ad-hoc networks have to use TCP/IP, which were not designed for mobile ad-hoc networks and yield poor performance when deployed in this kind of networks. The poor performance of TCP in ad-hoc networks has several reasons, especially the communication medium with high bit error rates (BER) and TCPs optimization on fixed networks. We present an enhancement, the restricted congestion window enlargement (TCP/RCWE), and show its ability to handle TCPs problems in mobile ad-hoc networks. We also illustrate the performance gain of TCP by the enhancement.

Gossip routing in wireless mesh networks

Gossip routing is an approach to reduce the redundancy of flooding in wireless networks. A study by Haas et al. evaluated different gossip routing variants in simulations on regular and random network topologies. Using the DES-Testbed, a wireless mesh network, we tried to replicate their experiments to evaluate whether the findings hold in real world scenarios. Four different gossip routing variants and the experiment setup are elaborated as well as issues regarding the replication of the experiments discussed. With this study we demonstrate that even small wireless network deployments show a bimodal behavior when a certain probability threshold is passed.

Dynamic Channel Assignment for Wireless Mesh Networks Using Clustering

The aggregate capacity of wireless mesh networks can be improved significantly by equipping each node with multiple interfaces and by using multiple channels in order to reduce the effect of interference. Since the number of available channels is limited, it is desired to allocate and reallocate channels on-demand. In this paper, a Cluster Channel Assignment (CCA) approach is proposed, to maximize the aggregate throughput by exploiting spatial reuse and local dynamic switching of the channels. A clustering approach is employed in order to maximize the network capacity while minimizing the interference and taking advantage of the possibility of reuse of channels among clusters.

DES-SERT: A framework for structured routing protocol implementation

Routing is a general task, yet the implementation of routing protocols requires specific operating system related knowledge. The developer has to deal with particular kernel internals that might have severe side effects. This is especially true for reactive and hybrid protocols where routing and forwarding are heavily intermixed. Furthermore, novel routing protocols require features that are not provided by current operating systems or have to be customized. Thus routing protocols for mobile ad-hoc networks and wireless mesh networks are often studied in simulation environments. However, simulations have limitations that can result in conclusions that do not hold in real networks. A framework for the implementation of routing protocols in operating systems is required to enable real world oriented research. We introduce the DES Simple and Extensible Routing-Framework for Testbeds (DES-SERT). The framework supports the implementation and evaluation of routing protocols in a testbed environment. A structured protocol implementation is advocated by transmitting data in extensions attached to packets and by its pipeline based architecture. Several steps are elaborated how to derive an implementation from a routing protocol specification.

Performance Evaluation of a Hybrid Testbed for Wireless Mesh Networks

Wireless mesh networks (WMN) are supposed to provide flexible and high-performance wireless network access for large indoor and outdoor areas, e.g., community networking and metropolitan area networks. However, these claims are mostly substantiated by simulation studies only as real testbeds are inflexible and associated with high maintenance effort. In this work we present a hybrid, i.e., partly real and partly virtualized, WMN testbed. This provides a high degree of realism while still allowing the flexibility known from simulations. In addition to the architectural discussion we present measurement results from our testbed highlighting the optimization potential of small protocol parameter changes.

A real-time and energy-efficient MAC protocol for wireless sensor networks

This paper proposes AREA-MAC, a medium access control (MAC) protocol for wireless sensor networks (WSNs). AREA-MAC reduces latency and energy consumption of nodes by using low power listening (LPL) with short preamble messages. Other protocols like B-MAC use long preamble messages that cause higher latency, energy consumption, and control overhead on nodes. AREA-MAC provides a reasonable trade-off between vital parameters, such as system fairness, throughput, scalability, and adaptability to traffic conditions. Additionally, to minimize network latency and maximize its lifetime, two application-based optimization problems are formulated. The gain of AREA-MAC in terms of delay and energy efficiency and an OMNeT++ based simulation framework are also discussed.