64 research outputs found
A security architecture for personal networks
Abstract Personal Network (PN) is a new concept utilizing pervasive computing to meet the needs of the user. As PNs edge closer towards reality, security becomes an important concern since any vulnerability in the system will limit its practical use. In this paper we introduce a security architecture designed for PNs. Our aim is to use secure but lightweight mechanisms suitable for resource constrained devices and wireless communication. We support pair-wise keys for secure cluster formation and use group keys for securing intra-cluster communication. In order to analyze the performance of our proposed mechanisms, we carry out simulations using ns-2. The results show that our mechanisms have a low overhead in terms of delay and energy consumption
Poster Abstract: Hierarchical Subchannel Allocation for Mode-3 Vehicle-to-Vehicle Sidelink Communications
In V2V Mode-3, eNodeBs assign subchannels to vehicles in order for them to
periodically broadcast CAM messages \cite{b2}. A crucial aspect is to ensure
that vehicles in the same cluster will broadcast in orthogonal time
subchannels\footnote{A subchannel is a time-frequency resource chunk capable of
sufficiently conveying a CAM message.} to avoid conflicts. In general,
resource/subchannel allocation problems can be represented as weighted
bipartite graphs. However, in this scenario there is an additional time
orthogonality constraint which cannot be straightforwardly handled by
conventional graph matching methods \cite{b3}. Thus, in our approach the
mentioned constraint has been taken into account. We also perform the
allocation task in a sequential manner based on the constrainedness of each
cluster. To illustrate the gist of the problem, in Fig. 1 we show two partially
overlapping clusters where a conflict between vehicles and is
generated as the allotted subchannels are in the same subframe
Network-Assisted Resource Allocation with Quality and Conflict Constraints for V2V Communications
The 3rd Generation Partnership Project (3GPP) has recently established in
Rel. 14 a network-assisted resource allocation scheme for vehicular broadcast
communications. Such novel paradigm is known as vehicle--to--vehicle (V2V)
\textit{mode-3} and consists in eNodeBs engaging only in the distribution of
sidelink subchannels among vehicles in coverage. Thereupon, without further
intervention of the former, vehicles will broadcast their respective signals
directly to their counterparts. Because the allotment of subchannels takes
place intermittently to reduce signaling, it must primarily be conflict-free in
order not to jeopardize the reception of signals. We have identified four
pivotal types of allocation requirements that must be guaranteed: one quality
of service (QoS) requirement and three conflict conditions which must be
precluded in order to preserve reception reliability. The underlying problem is
formulated as a maximization of the system sum-capacity with four types of
constraints that must be enforced. In addition, we propose a three-stage
suboptimal approach that is cast as multiple independent knapsack problems
(MIKPs). We compare the two approaches through simulations and show that the
latter formulation can attain acceptable performance at lesser complexity
Poster: Resource Allocation with Conflict Resolution for Vehicular Sidelink Broadcast Communications
In this paper we present a graph-based resource allocation scheme for
sidelink broadcast V2V communications. Harnessing available information on
geographical position of vehicles and spectrum resources utilization, eNodeBs
are capable of allotting the same set of sidelink resources to different
vehicles distributed among several communications clusters. Within a
communications cluster, it is crucial to prevent time-domain allocation
conflicts since vehicles cannot transmit and receive simultaneously, i.e., they
must transmit in orthogonal time resources. In this research, we present a
solution based on a bipartite graph, where vehicles and spectrum resources are
represented by vertices whereas the edges represent the achievable rate in each
resource based on the SINR that each vehicle perceives. The aforementioned time
orthogonality constraint can be approached by aggregating conflicting vertices
into macro-vertices which, in addition, reduces the search complexity. We show
mathematically and through simulations that the proposed approach yields an
optimal solution. In addition, we provide simulations showing that the proposed
method outperforms other competing approaches, specially in scenarios with high
vehicular density.Comment: arXiv admin note: substantial text overlap with arXiv:1805.0655
Protocol and networking design issues for local access WDM networks
This report gives an overview of some of the protocol and networking design issues that have been addressed in Flamingo, a major ongoing project which investigates the use of WDM optical technology in local access networks. Quality of service delivery and wavelength assignment are focused on in this report. A brief introduction to optical networks and WDM as well as a brief description of Flamingo are also included in this report
Parallel and Successive Resource Allocation for V2V Communications in Overlapping Clusters
The 3rd Generation Partnership Project (3GPP) has introduced in Rel. 14 a
novel technology referred to as vehicle--to--vehicle (V2V) \textit{mode-3}.
Under this scheme, the eNodeB assists in the resource allocation process
allotting sidelink subchannels to vehicles. Thereupon, vehicles transmit their
signals in a broadcast manner without the intervention of the former one.
eNodeBs will thereby play a determinative role in the assignment of subchannels
as they can effectively manage V2V traffic and prevent allocation conflicts.
The latter is a crucial aspect to be enforced in order for the signals to be
received reliably by other vehicles. To this purpose, we propose two resource
allocation schemes namely bipartite graph matching-based successive allocation
(BGM-SA) and bipartite graph matching-based parallel allocation (BGM-PA) which
are suboptimal approaches with lesser complexity than exhaustive search. Both
schemes incorporate constraints to prevent allocation conflicts from emerging.
In this research, we consider overlapping clusters only, which could be formed
at intersections or merging highways. We show through simulations that BGM-SA
can attain near-optimal performance whereas BGM-PA is subpar but less complex.
Additionally, since BGM-PA is based on inter-cluster vehicle pre-grouping, we
explore different metrics that could effectively portray the overall channel
conditions of pre-grouped vehicles. This is of course not optimal in terms of
maximizing the system capacity---since the allocation process would be based on
simplified surrogate information---but it reduces the computational complexity
Graph-Based Resource Allocation with Conflict Avoidance for V2V Broadcast Communications
In this paper we present a graph-based resource allocation scheme for
sidelink broadcast vehicle-to-vehicle (V2V) communications. Harnessing
available information on the geographical position of vehicles and spectrum
resources utilization, eNodeBs are capable of allotting the same set of
sidelink resources to several different vehicles in order for them to broadcast
their signals. Hence, vehicles sharing the same resources would ideally be in
different communications clusters for the interference level-generated due to
resource repurposing-to be maintained under control. Within a communications
cluster, it is crucial that vehicles transmit in orthogonal time resources to
prevent conflicts as vehicles-with half-duplex radio interfaces--cannot
transmit and receive simultaneously. In this research, we have envisaged a
solution based on a bipartite graph, where vehicles and spectrum resources are
represented by vertices whereas the edges represent the achievable rate in each
resource based on the signal-to-interference-plus-noise ratio (SINR) that
vehicles perceive. The aforementioned constraint on time orthogonality of
allocated resources can be approached by aggregating conflicting vertices into
macro-vertices which, in addition, narrows the search space yielding a solution
with computational complexity equivalent to the conventional graph matching
problem. We show mathematically and through simulations that the proposed
approach yields an optimal solution. In addition, we provide simulations
showing that the proposed method outperforms other competing approaches,
specially in scenarios with high vehicular density
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