6 research outputs found
Hedonic Coalition Formation for Distributed Task Allocation among Wireless Agents
Autonomous wireless agents such as unmanned aerial vehicles or mobile base
stations present a great potential for deployment in next-generation wireless
networks. While current literature has been mainly focused on the use of agents
within robotics or software applications, we propose a novel usage model for
self-organizing agents suited to wireless networks. In the proposed model, a
number of agents are required to collect data from several arbitrarily located
tasks. Each task represents a queue of packets that require collection and
subsequent wireless transmission by the agents to a central receiver. The
problem is modeled as a hedonic coalition formation game between the agents and
the tasks that interact in order to form disjoint coalitions. Each formed
coalition is modeled as a polling system consisting of a number of agents which
move between the different tasks present in the coalition, collect and transmit
the packets. Within each coalition, some agents can also take the role of a
relay for improving the packet success rate of the transmission. The proposed
algorithm allows the tasks and the agents to take distributed decisions to join
or leave a coalition, based on the achieved benefit in terms of effective
throughput, and the cost in terms of delay. As a result of these decisions, the
agents and tasks structure themselves into independent disjoint coalitions
which constitute a Nash-stable network partition. Moreover, the proposed
algorithm allows the agents and tasks to adapt the topology to environmental
changes such as the arrival/removal of tasks or the mobility of the tasks.
Simulation results show how the proposed algorithm improves the performance, in
terms of average player (agent or task) payoff, of at least 30.26% (for a
network of 5 agents with up to 25 tasks) relatively to a scheme that allocates
nearby tasks equally among agents.Comment: to appear, IEEE Transactions on Mobile Computin
Hybrid token-CDMA MAC protocol for wireless networks.
Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2009.Ad hoc networks are commonly known to implement IEEE 802.11 standard as their medium
access control (MAC) protocol. It is well known that token passing MAC schemes
outperform carrier-sense-multiple-access (CSMA) schemes, therefore, token passing MAC
protocols have gained popularity in recent years. In recent years, the research extends the
concept of token passing ' scheme to wireless settings since they have the potential of
achieving higher channel utilization than CSMA type schemes.
In this thesis, a hybrid Token-CDMA MAC protocol that is based on a token passing scheme
with the incorporation of code division multiple access (CDMA) is introduced. Using a
dynamic code distribution algorithm and a modified leaky-bucket policing system, the
hybrid protocol is able to provide both Quality of Service (QoS) and high network resource
utilization, while ensuring the stability of a network. This thesis begins with the introduction
of a new MAC protocol based on a token-passing strategy. The input traffic model used in
the simulation is a two-state Markov Modulated Poisson Process (MMPP). The data rate
QoS is enforced by implementing a modified leaky bucket mechanism in the proposed MAC
scheme. The simulation also takes into account channel link errors caused by the wireless
link by implementing a multi-layered Gilbert-Elliot model. The performance of the proposed
MAC scheme is examined by simulation, and compared to the performance of other MAC
protocols published in the literature. Simulation results demonstrate that the proposed hybrid
MAC scheme is effective in decreasing packet delay and significantly shortens the length of
the queue.
The thesis continues with the discussion of the analytical model for the hybrid Token CDMA
protocol. The proposed MAC scheme is analytically modelled as a multiserver
multiqueue (MSMQ) system with a gated service discipline. The analytical model is
categorized into three sections viz. the vacation model, the input model and the buffer model.
The throughput and delay performance are then computed and shown to closely match the
simulation results. Lastly, cross-layer optimization between the physical (PHY) and MAC
layers for the hybrid token-CDMA scheme is discussed. The proposed joint PHY -MAC
approach is based on the interaction between the two layers in order to enable the stations to
dynamically adjust the transmission parameters resulting in reduced mutual interference and
optimum system performance
Enabling the Development and Implementation of Digital Twins : Proceedings of the 20th International Conference on Construction Applications of Virtual Reality
Welcome to the 20th International Conference on Construction Applications of Virtual Reality (CONVR 2020). This year we are meeting on-line due to the current Coronavirus pandemic. The overarching theme for CONVR2020 is "Enabling the development and implementation of Digital Twins". CONVR is one of the world-leading conferences in the areas of virtual reality, augmented reality and building information modelling. Each year, more than 100 participants from all around the globe meet to discuss and exchange the latest developments and applications of virtual technologies in the architectural, engineering, construction and operation industry (AECO). The conference is also known for having a unique blend of participants from both academia and industry. This year, with all the difficulties of replicating a real face to face meetings, we are carefully planning the conference to ensure that all participants have a perfect experience. We have a group of leading keynote speakers from industry and academia who are covering up to date hot topics and are enthusiastic and keen to share their knowledge with you. CONVR participants are very loyal to the conference and have attended most of the editions over the last eighteen editions. This year we are welcoming numerous first timers and we aim to help them make the most of the conference by introducing them to other participants