About Omnet Project Team

Future Internet concepts for demand management

The “Internet of Things” (IoT) is a concept where animate and inanimate objects have the ability to collect and exchange data over a network without requiring human-to-human or human-to-computer interaction. Through the utilisation of IoT and the future Internet, fine-grained, near-real time energy demand management is increasingly becoming a reality. This is achieved through real-time billing, predictive energy costs and demand response signalling using IoT as a data platform.

Installing smarter technologies at the end-user premises and communicating measurements over different network technologies provide access to information and subsequently for smarter decision making about energy management in the household. This paper presents an international research and experimental initiative linked to the Future Internet (TRESCIMO) which facilitates the validity of using these technologies as base for energy demand management. The initiative utilises a philosophy of informing customers about their energy usage behaviour through data received from smart devices that are integrated with a machine-to-machine (M2M) platform. The paper discusses opportunities presented by IoT in the management of energy use in the residential sector.

LESS: Lightweight Establishment of Secure Session: A Cross-Layer Approach Using CoAP and DTLS-PSK Channel Encryption

Secure yet lightweight protocol for communication over the Internet is a pertinent problem for constrained environments in the context of Internet of Things (IoT) / Machine to Machine (M2M) applications. This paper extends the initial approaches published in [1], [2] and presents a novel cross-layer lightweight implementation to establish a secure channel. It distributes the responsibility of communication over secure channel in between the application and transport layers. Secure session establishment is performed using a payload embedded challenge response scheme over the Constrained Application Protocol (CoAP) [3].

Record encryption mechanism of Datagram Transport Layer Security (DTLS) [4] with Pre-Shared Key (PSK) [5] is used for encrypted exchange of application layer data. The secure session credentials derived from the application layer is used for encrypted exchange over the transport layer. The solution is designed in such a way that it can easily be integrated with an existing system deploying CoAP over DTLS-PSK. The proposed method is robust under different security attacks like replay attack, DoS and chosen cipher text. The improved performance of the proposed solution is established with comparative results and analysis.

An efficient resource naming for enabling constrained devices in SmartM2M architecture

The Internet of Things (IoT) paradigm envisions an interconnected world where things can communicate with each other, transmit state information and execute smart tasks. The number of devices connected in Internet has been growing exponentially in the past years and the Machine-to-Machine (M2M) plays a major role in enabling IoT paradigm while it is expected that in the near future billion of devices will be connected. Till now many vertical solutions in the M2M domain exist. To bridge this gap, the European Telecommunications Standards Institute (ETSI) has defined SmartM2M a horizontal service layer that separates the communication part from the application domain and guaranteeing interoperability among different technologies.

Each device independently from the technology should register and post data to the service layer, which makes them available to applications in a seamless way. However the integration with very constrained devices like a IPv6 over Low power Wireless Personal Area Networks (6LoWPAN) based network is not straight forward. In this paper at first it is analyzed the problem of the hierarchical Uniform Resource Identifier (URI) in the SmartM2M standard specifications. Then, a new non hierarchical resource structure is proposed. Finally it is demonstrated that the new resource structure originates very short URIs, which can better suit to be used by constrained devices.

Zero-Outage Cellular Downlink With Fixed-Rate D2D Underlay

Two of the emerging trends in wireless cellular systems are device-to-device (D2D) and machine-to-machine (M2M) communications. D2D enables efficient reuse of the licensed spectrum to support localized transmissions, while M2M connections are often characterized by fixed and low transmission rates. D2D connections can be instrumental in localized aggregation of uplink M2M traffic to a more capable cellular device, before being finally delivered to the base station (BS). In this paper we show that a fixed M2M rate is an enabler of efficient machine-type D2D underlay operation taking place simultaneously with another downlink cellular transmission. In the considered scenario, aBS B transmits to a user U, while there are NM machine-type devices (MTDs) attached to U, all sending simultaneously to U and each using the same rate RM.

While assuming that B knows the channel B – U, but not the interfering channels from the MTDs to U, we prove that there is a positive downlink rate that can always be decoded by U, leading to zero-outage of the downlink signal. This is a rather surprising consequence of the features of the multiple access channel and the fixed rate RM. We also consider the case of a simpler, single-user decoder at U with successive interference cancellation. However, with single-user decoder, a positive zero-outage rate exists only when NM = 1 and is zero when NM > 1. This implies that joint decoding is instrumental in enabling fixed-rate underlay operation.

An IP-based triggering method for LTE MTC devices

In Release 11, the 3rd Generation Partnership Project (3GPP) introduced the ability for Service Capability Servers (SCS) / Machine-to-Machine (M2M) Servers to request that the Mobile Core Network (MCN) deliver a Short Message Service (SMS) device trigger to the User Equipment (UE). The ability to send a trigger avoids the need for the UE to maintain constant contact with the SCS via keep-alive messaging. Keep-alive messaging can be particularly wasteful when considering the nature of M2M Communications. The SMS based triggering solution requires that the UE support an application that listens on an SMS port for triggers.

In this paper, we propose an IP-Based trigger delivery method. The proposed triggering method allows a UE to receive a trigger by simply listening on a User Datagram Protocol (UDP) port. The solution also allows the UE to reply to the SCS with a small application specific response. We present the call flow for the new triggering method and the required enhancements to the 3GPP Machine-Type Communication Interworking Function (MTC-IWF). The paper concludes by presenting a demonstration platform that shows the IP-based trigger delivery method working with a commercially available Long Term Evolution (LTE) UE and a oneM2M compliantM2M Server.

Scheduling in Successive Interference Cancellation based Wireless Ad Hoc Networks

Successive Interference Cancellation (SIC) allows multiple transmissions in the same neighborhood by enabling both concurrent reception and interference rejection via decoding and subtracting the signals successively from the composite received signal. In this paper, we study the scheduling problem for minimizing the schedule length required to satisfy the traffic demands of the links in SIC based wireless ad hoc networks.

Upon proving the NP-hardness of the problem, we propose a novel efficient heuristic scheduling algorithm based on the greedy assignment of the links to each time slot by using a novel metric called Interference Effect (IE). The IE of a feasible link is defined as the total Signal-to-Interference-plus-Noise Ratio (SINR) drop of the links in the scheduled set with the addition of that link. We demonstrate via extensive simulations that the proposed algorithm performs better than the previous algorithms, with lower computational complexity.

VaSili – A simulation runtime environment for applications in Vehicular Ad-Hoc Networks

In recent years, Vehicular Ad-Hoc Networks (VANETs) have become a very active research field. Since real-world experiments might involve potentially costly and complex hardware installations, simulations are a widely used alternative. However, due to, e.g., different scopes of functionality of available VANET simulators, simulations of VANET applications yield different results when using different simulators. Thus, it would be beneficial to test a VANET application in multiple simulation environments. Unfortunately, VANET applications are typically implemented inside of a certain simulator.

Hence, to switch the simulator, the source code of the application has to be adapted. To solve this problem, we developed a VANET API which defines the structure and interfaces of crucial VANET components to make them accessible in a unified way. We further developed VANET Simulation Runtime (VaSili), a framework which allows executing VANET API-compliant VANET applications in different VANET simulators without modification. Hence, applications developed using our proposed API can be run in different simulation environments and, since the VANET API is independent of VaSili, on real hardware.

A MAC protocol for link maintenance in multichannel cognitive radio ad hoc networks

To provide an efficient link maintenance approach, we propose a cross layer medium access control (LM-MAC) protocol for multichannel cognitive radio ad hoc networks. Link establishment and reliable transmission are two key problems for a perfect link maintenance mechanism. Since the cognitive user (CU) pairs have to reestablish their links each frame, in the proposed MAC protocol, three different access modes are designed to guarantee transmission efficiency in continuous frames. To enhance the transmission reliability, each CU will create a father spectrum list (FSL) after joining in the network.

FSL is divided into three groups of sub-channels with different functions to compensate the packet loss caused by the primary users’ appearance and the deep fading. Meanwhile, since the transmitter and the receiver will share the same FSL, periodical cooperative sensing is adopted to further optimize the former problem. Finally, compared with the existing opportunistic multichannel (OMC)-MAC protocol, the proposed LM-MAC protocol achieves better system performance in terms of saturation throughput, continuity and access delay.

New Reservation Multiaccess Protocols for Underwater Wireless Ad Hoc Sensor Networks

In a wireless network, where propagation delay is high and communications are sporadic, some kind of reservation protocol is generally used. Reservation access protocols were proposed earlier in earth stations-to-satellite communication with known propagation delay. However, optimality of the number of access slots with respect to the system performance parameters, such as system utilization, blocking probability, and delay, were not thoroughly studied. Besides, the effect of propagation delay uncertainty, which predominantly happens in underwater communications, are yet to be addressed. In this paper, we first analyze the system performance in many-to-one multiaccess data transfer scenario in underwater wireless ad hoc sensor networks with a fixed number of access slots and with the assumption of perfect propagation delay information.

We propose two system state aware dynamic approaches to suitably adjust the number of access slots, and investigate the optimum slotting strategy to maximize the system utilization. Next, by accounting the propagation delay uncertainty, we relook into the optimality criteria on the number of access slots, where we apply a modified receiver-synchronized slotted Aloha principle to maximize the access performance. Via mathematical analysis, supported by discrete event simulations, we show that the system utilization and blocking probability performances with our proposed dynamic reservation protocols are consistently better compared to the competitive reservation protocols with fixed as well as variable access slots. Further, we conduct NS3 simulations to study the protocol performances under more realistic channel and traffic conditions, which also demonstrate that the proposed optimized dynamic slotting offers a much better system utilization performance compared to a similar underwater reservation multiaccess protocol.

Application of fuzzy logic for selecting the route in AODV routing protocol for vehicular ad hoc networks

One of the known routing protocols in vehicular ad hoc networks is AODV routing protocol which usually uses the criterion of the minimum number of hops to select the route. According to frequent change of topology and the rapid movement of vehicles in these networks, considering the criterion of the minimum hops in AODV prevents selecting more stable routes and decreases the networkefficiency. The purpose of this paper is to increase the efficiency of AODV routing protocol using fuzzy logic.

Three criteria such as speed, direction and distance of vehicles to destination are used as the inputs of fuzzy system. The result of the fuzzy system can be considered as the probability of selecting route. The proposed protocol has been compared with AODV and FCAR. The evaluation results show that the proposed protocol has a lower average end to end delay than AODV. Packet delivery rate has also increased more than AODV and FCAR.