Showing papers by "Thomas Clausen published in 2013"

Evaluation of routing protocol for low power and Lossy Networks: LOADng and RPL

Abstract: Routing protocol is a critical component of Low-power and Lossy Networks for Smart Grid The protocols are used for data forwarding, which includes data acquisition, information dissemination, etc This paper evaluates two main routing protocols used for Low-power and Lossy Networks: RPL and LOADng, to understand their strengths and limitations Observations are provided based on analysis of specification and experimental experience, regarding the protocol's routing overhead, traffic pattern, resource requirement, fragmentation, etc Simulations are further launched to study the performance in different traffic patterns, which include sensor-to-sensor traffic, sensor-to-root traffic and root-to-sensor bidirectional traffic By evaluating those protocols, the readers could have better understanding of the protocol applicability, and choose the appropriate protocol for desired applications

Performance analysis of Trickle as a flooding mechanism

Abstract: “The Trickle Algorithm” is conceived as an adaptive mechanism for allowing efficient and reliable information sharing among nodes, communicating across a lossy and shared medium Its basic principle is, for each node, to monitor transmissions from its neighbours, compare what it receives with its current state, and schedule future transmissions accordingly: if an inconsistency of information is detected, or if few or no neighbours have transmitted consistent information “recently”, the next transmission is scheduled “soon” - and, in case consistent information from a sufficient number of neighbours is received, the next transmission is scheduled to be “later” Developed originally as a means of distributing firmware updates among sensor devices, this algorithm has found use also for distribution of routing information in the routing protocol RPL, standardised within the IETF for maintaining a routing topology for low-power and lossy networks (LLNs) Its use is also proposed in a protocol for multicast in LLNs, denoted “Multicast Forwarding Using Trickle” This paper studies the performance of the Trickle algorithm, as it is used in that multicast protocol

Enabling multihop communication in spontaneous wireless networks

Abstract: Since the end of the 20th century, wireless networking is experiencing explosive growth, driven by the popularity of wireless telephony on one hand, and by the development of wireless computer networks on the other hand. Both trends are currently merging into a single attempt: enabling massive wireless Internet access. This phenomenon was inspired by Norman Abramson’s pioneer work on packet radio networks [14] in the 1970s, and made possible by the authorization of wireless spectrum use for civil telecommunication purposes, in the 1980s1 . At first, this deregulation encouraged the democratization of wireless telephony, in the 1990s, thanks to the availability of cheaper, more efficient hardware stemming from Cold War military industry efforts. Since 2000, the introduction of new wireless communication standards using the spectrum authorized for civil use has also fueled the development of wireless computer networks and wireless Internet access.

Optimization of jitter configuration for reactive route discovery in wireless mesh networks

Abstract: Jitter is a small, random variation of timing before message emission that is widely used in non-synchronized wireless communication. It is employed to avoid collisions caused by simultaneous transmissions by adjacent nodes over the same channel. In reactive (on-demand) routing protocols, such as AODV and LOADng, it is recommended to use jitter during the flooding of Route Request messages. This paper analyzes the impact of jitter mechanisms in the performance of route discovery procedures of on-demand routing protocols, and examines the drawbacks of the standard and commonly used uniformly distributed jitter. The main studied drawback is denominated delay inversion effect. Two variations on the jitter mechanism-window jitter and adaptive jitter- are proposed to address this effect. Both variations take the presence and the quality of traversed links into consideration to determine the per-hop forwarding delay, and both variations allow to effectively reduce the routing overhead and increase the quality of the computed paths with respect to the standard uniform jitter mechanism. Simulations are performed to compare the performance of different jitter settings in various network scenarios.

Jitter Considerations in On-Demand Route Discovery for Mobile Ad Hoc Networks

Abstract: Jittering (a small, random variation in timing of control message emission) is widely used in protocols for wireless communication, in order to avoid simultaneous packet transmissions over the same channel by adjacent nodes in the network Used for both regularly scheduled packets, for event-triggered packets, and for scheduled resets in the network, jittering is a particularly important mechanism when a network event may cause multiple adjacent nodes to react concurrently Introduced in the proactive MANET routing protocol OLSR, the "LLN On-demand Ad hoc Distance-vector Routing Protocol - Next Generation" (LOADng), a derivative of AODV, is specified so as to also use jitter for flooding Route Request (RREQ) messages during route discovery This use of jitter in RREQ flooding is, however, not without drawbacks, which are identified and addressed in this paper within the framework of a more general study of jitter mechanisms used for route discovery in reactive routing protocols The paper studies the behavior of route discovery when using "naive" jitter (simply, delaying RREQ retransmission by a small uniformly distributed random delay), in order to identify and analyze the problems hereof, mostly related to route sub-optimality and excessive control traffic overhead A Window Jitter mechanism is then proposed to address these issues - with the performance hereof, when compared to "naive" jitter being evaluated by way of modeling, theoretical analysis and experiments The paper shows that the use of Window Jitter improves indeed the efficiency of route discovery in AODV and overcome the drawbacks identified for "naive" jitter

A Depth First Forwarding (DFF) Extension for the LOADng Routing Protocol

Abstract: This paper explores the cooperation between the new standards for "Low Power and Lossy Networks'' (LLNs): IETF RFC 6971, denoted "Depth-First Forwarding in Unreliable Networks'' (DFF) and the ITU-T standardised routing protocol "LOADng''. DFF is a data-forwarding mechanism for increasing reliability of data delivery in networks with dynamic topology and lossy links, using a mechanism similar to a "depth-first search'' for the destination of a packet. LOADng is a reactive on-demand routing protocol used in LLNs. The purpose of this study is to evaluate the benefit of using DFF conjointly with a routing protocol. To this end, the paper compares the performance of LOADng and LOADng+DFF using Ns2 simulations, showing a 20% end-to-end data delivery ratio increase at expense of expected longer path lengths.

Routing MPR Optimization for the Optimized Link State Routing Protocol version 2 (OLSRv2)

Abstract: This specification updates the Optimized Link State Routing Protocol version 2 (OLSRv2) with an optimization to improve the selection of routing MPRs The optimization retains full interoperability between implementations of OLSRv2 with and without this optimization