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Scheduling and power control for connectivity enhancement in multi-hop I2V/V2V networks

- Nguyen, Bach, Ngo, Duy, Dao, Minh, Bao, Vo, Vu, Hai

  • Authors: Nguyen, Bach , Ngo, Duy , Dao, Minh , Bao, Vo , Vu, Hai
  • Date: 2022
  • Type: Text , Journal article
  • Relation: IEEE Transactions on Intelligent Transportation Systems Vol. 23, no. 8 (2022), p. 10322-10332
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  • Description: Infrastructure-to-vehicle (I2V) and vehicle-to-vehicle (V2V) communications are often combined to extend the connectivity and coverage in the Intelligent Transportation System (ITS) and its applications, e.g., augmented reality, real-time parking management and online shopping. Through multi-hop I2V and V2V communications, requesting vehicles are always connected to road side units (RSUs) even when they do not reside within the RSUs' coverage range. However, there may be not adequate network resource for several I2V and V2V links when multiple vehicles request services simultaneously. In this paper, we propose a joint frequency scheduling and power control scheme to enhance connectivity in multi-hop I2V/V2V networks. We associate I2V and V2V links with tuple-links, then formulate an NP-hard problem in which a frequency scheduler and a power controller are jointly designed for the tuple-links. The NP-hard problem is decomposed into two separate subproblems by employing the delayed column generation technique. Then, we employ a method for linear programming and a greedy algorithm to address these subproblems. Through numerical experiments with practical parameter settings, we demonstrate the proposed scheme outperforms several existing ones in terms of connectivity enhancement, measured by the service resumption number and average achieved throughput. Furthermore, the efficiency of our scheme is further enhanced when the number of available channels is high, and buffer size equipped to the requesting vehicles is large. © 2000-2011 IEEE.

Connectivity of cubical polytopes

- Bui, Hoa, Pineda-Villavicencio, Guillermo, Ugon, Julien

  • Authors: Bui, Hoa , Pineda-Villavicencio, Guillermo , Ugon, Julien
  • Date: 2019
  • Type: Text , Journal article
  • Relation: Journal of Combinatorial Theory Series A Vol. 169, no. (Jan 2019), p. 21
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  • Description: A cubical polytope is a polytope with all its facets being combinatorially equivalent to cubes. We deal with the connectivity of the graphs of cubical polytopes. We first establish that, for any d >= 3, the graph of a cubical d-polytope with minimum degree 5 is min{delta, 2d - 2}-connected. Second, we show, for any d >= 4, that every minimum separator of cardinality at most 2d - 3 in such a graph consists of all the neighbours of some vertex and that removing the vertices of the separator from the graph leaves exactly two components, with one of them being the vertex itself. (C) 2019 Elsevier Inc. All rights reserved.

Linkedness of cartesian products of complete graphs

- Jorgensen, Leif, Pineda-Villavicencio, Guillermo, Ugon, Julien

The linkedness of cubical polytopes : beyond the cube

- Bui, Hoa, Pineda-Villavicencio, Guillermo, Ugon, Julien

  • Authors: Bui, Hoa , Pineda-Villavicencio, Guillermo , Ugon, Julien
  • Date: 2024
  • Type: Text , Journal article
  • Relation: Discrete Mathematics Vol. 347, no. 3 (2024), p.
  • Relation: https://purl.org/au-research/grants/arc/DP180100602
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  • Description: A cubical polytope is a polytope with all its facets being combinatorially equivalent to cubes. The paper is concerned with the linkedness of the graphs of cubical polytopes. A graph with at least 2k vertices is k-linked if, for every set of k disjoint pairs of vertices, there are k vertex-disjoint paths joining the vertices in the pairs. We say that a polytope is k-linked if its graph is k-linked. In a previous paper [3] we proved that every cubical d-polytope is ⌊d/2⌋-linked. Here we strengthen this result by establishing the ⌊(d+1)/2⌋-linkedness of cubical d-polytopes, for every d≠3. A graph G is strongly k-linked if it has at least 2k+1 vertices and, for every vertex v of G, the subgraph G−v is k-linked. We say that a polytope is (strongly) k-linked if its graph is (strongly) k-linked. In this paper, we also prove that every cubical d-polytope is strongly ⌊d/2⌋-linked, for every d≠3. These results are best possible for this class of polytopes.
  • Description: A cubical polytope is a polytope with all its facets being combinatorially equivalent to cubes. The paper is concerned with the linkedness of the graphs of cubical polytopes. A graph with at least 2k vertices is k-linked if, for every set of k disjoint pairs of vertices, there are k vertex-disjoint paths joining the vertices in the pairs. We say that a polytope is k-linked if its graph is k-linked. In a previous paper [3] we proved that every cubical d-polytope is

A survey on the connectivity of cages

- Miller, Mirka, Lin, Yuqing

All (k;g)-cages are edge-superconnected

- Lin, Yuqing, Miller, Mirka, Balbuena, Camino, Marcote, Xavier

  • Authors: Lin, Yuqing , Miller, Mirka , Balbuena, Camino , Marcote, Xavier
  • Date: 2006
  • Type: Text , Journal article
  • Relation: Networks Vol. 47, no. 2 (2006), p. 102-110
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  • Description: A (k;g)-cage is k-regular graph with girth g and with the least possible number of vertices. In this article we prove that (k;g)-cages are edge-superconnected if g is even. Earlier, Marcote and Balbuena proved that (k;g)-cages are edge-superconnected if g is odd [Networks 43 (2004), 54-59]. Combining our results, we conclude that all (k;g)-cages are edge-superconnected. © 2005 Wiley Periodicals, Inc.
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  • Description: 2003001830

Modeling and analysis of finite-scale clustered backscatter communication networks

- Wang, Qiu, Zhou, Yong, Dai, Hong-Ning, Zhang, Guopeng, Imran, Muhammad, Nasser, Nidal

  • Authors: Wang, Qiu , Zhou, Yong , Dai, Hong-Ning , Zhang, Guopeng , Imran, Muhammad , Nasser, Nidal
  • Date: 2023
  • Type: Text , Conference paper
  • Relation: 2023 IEEE International Conference on Communications, ICC 2023, Rome, 28 May-1 June 2023, ICC 2023 - IEEE International Conference on Communications Vol. 2023-May, p. 1456-1461
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  • Description: Backscatter communication (BackCom) is an intriguing technology that enables devices to transmit information by reflecting environmental radio frequency signals while consuming ultra-low energy. Applying BackCom in the Internet of things (IoT) networks can effectively address the power-unsustainability issue of energy-constraint devices. Considering many practical IoT applications, networks are finite-scale and devices are needed to be deployed at hotspot regions organized in clusters to cooperate for specific tasks. This paper considers finite-scale clustered backscatter communication networks (F-CBackCom Nets). To ensure communications, this paper establishes a theoretic model to analyze the communication connectivity of F-CBackCom Nets. Different from prior studies analyzing the connectivity with a focus on the transmission pair located at the center of the network, this paper analyzes the connectivity of a transmission pair located in an arbitrary location, because the performance of transmission pairs potentially varies with their network location. Extensive simulations validate the accuracy of our analytical model. Our results show that the connectivity of a transmission pair can be affected by its network location. Our analytical model and results can offer beneficial implications for constructing F-CBackCom Nets. © 2023 IEEE.

On connectivity of wireless sensor networks with directional antennas

- Wang, Qiu, Dai, Hong-Ning, Zheng, Zibin, Imran, Muhammad, Vasilakos, Athanasios

  • Authors: Wang, Qiu , Dai, Hong-Ning , Zheng, Zibin , Imran, Muhammad , Vasilakos, Athanasios
  • Date: 2017
  • Type: Text , Journal article
  • Relation: Sensors (Switzerland) Vol. 17, no. 1 (2017), p.
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  • Description: In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models. © 2017 by the authors; licensee MDPI, Basel, Switzerland.

Hybridisation rates, population structure, and dispersal of sambar deer (Cervus unicolor) and rusa deer (Cervus timorensis) in south-eastern Australia

- Hill, Erin, Murphy, Nicholas, Li-Williams, Scarlett, Davies, Christopher, Forsyth, David, Comte, Sebastien, Rollins, Lee, Hogan, Fiona, Wedrowicz, Faye, Crittle, Troy, Thomas, Elaine, Woodford, Luke, Pacioni, Carlo

  • Authors: Hill, Erin , Murphy, Nicholas , Li-Williams, Scarlett , Davies, Christopher , Forsyth, David , Comte, Sebastien , Rollins, Lee , Hogan, Fiona , Wedrowicz, Faye , Crittle, Troy , Thomas, Elaine , Woodford, Luke , Pacioni, Carlo
  • Date: 2023
  • Type: Text , Journal article
  • Relation: Wildlife Research Vol. 50, no. 9 (2023), p. 669-687
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  • Description: Context. Introduced populations of sambar deer (Cervus unicolor) and rusa deer (Cervus timorensis) are present across south-eastern Australia and are subject to local population control to alleviate their negative impacts. For management to be effective, identification of dispersal capability and management units is necessary. These species also readily hybridise, so additional investigation of hybridisation rates across their distributions is necessary to understand the interactions between the two species. Aims. Measure the hybridisation rate of sambar and rusa deer, assess broad-scale population structure present within both species and identify distinct management units for future population control, and measure the likely dispersal capability of both species. Methods. In total, 198 sambar deer, 189 rusa deer, and three suspected hybrid samples were collected across Victoria and New South Wales (NSW). After sequencing and filtering, 14 099 polymorphic single-nucleotide polymorphism (SNP) markers were retained for analysis. Hybridisation rates were assessed before the data were split by species to identify population structure, diversity indices, and dispersal distances. Key results. Across the entire dataset, 17 hybrids were detected. Broad-scale population structure was evident in sambar deer, but not among the sites where rusa deer were sampled. Analysis of dispersal ability showed that a majority of deer movement occurred within 20 km in both species, suggesting limited dispersal. Conclusions. Distinct management units of sambar deer can be identified from the dataset, allowing independent population control. Although broad-scale population structure was not evident in the rusa deer populations, dispersal limits identified suggest that rusa deer sites sampled in this study could be managed separately. Sambar × rusa deer hybrids are present in both Victoria and NSW and can be difficult to detect on the basis of morphology alone. Implications. Genetic analysis can identify broad-scale management units necessary for population control, and estimates of dispersal capability can assist in delineating management units where broad-scale population structure may not be apparent. The negative impacts associated with hybridisation require further investigation to determine whether removal of hybrids should be considered a priority management aim. © 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing.

Managing uncertainty in movement knowledge for environmental decisions

- Smith, Annabel, Kujala, Heini, Lahoz-Monfort, José, Guja, Lydia, Barton, Philip

  • Authors: Smith, Annabel , Kujala, Heini , Lahoz-Monfort, José , Guja, Lydia , Barton, Philip
  • Date: 2019
  • Type: Text , Journal article
  • Relation: Conservation Letters Vol. 12, no. 3 (2019), p.
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  • Description: Species’ movements affect their response to environmental change but movement knowledge is often highly uncertain. We now have well-established methods to inte-grate movement knowledge into conservation practice but still lack a framework to deal with uncertainty in movement knowledge for environmental decisions. We provide a framework that distinguishes two dimensions of species’ movement that are heavily influenced by uncertainty: knowledge about movement and relevance of movement to environmental decisions. Management decisions can be informed by their position in this knowledge-relevance space. We then outline a framework to support decisions around (1) increasing understanding of the relevance of movement knowledge, (2) increasing robustness of decisions to uncertainties and (3) improving knowledge on species’ movement. Our decision-support framework provides guid-ance for managing movement-related uncertainty in systematic conservation plan-ning, agri-environment schemes, habitat restoration and international biodiversity policy. It caters to different resource levels (time and funding) so that species’ movement knowledge can be more effectively integrated into environmental decisions. © 2018 The Authors. Conservation Letters published by Wiley Periodicals, Inc.

Dynamic V2I/V2V cooperative scheme for connectivity and throughput enhancement

- Nguyen, Bach, Ngo, Duy, Tran, Nguyen, Dao, Minh, Vu, Hai

  • Authors: Nguyen, Bach , Ngo, Duy , Tran, Nguyen , Dao, Minh , Vu, Hai
  • Date: 2022
  • Type: Text , Journal article
  • Relation: IEEE Transactions on Intelligent Transportation Systems Vol. 23, no. 2 (2022), p. 1236-1246
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  • Description: Automotive infotainment systems are expected to be first deployed on highways to service drivers travelling long distances, who are more likely to utilize the infotainment applications. In order to meet the stringent requirements of the infotainment systems, road side units (RSUs) are installed along the highway to facilitate a continuous vehicle-to-infrastructure (V2I) connectivity. Due to the long travelling distance and small coverage of the individual RSU, a more cost-effective solution would be to combine V2I with the vehicle-to-vehicle (V2V) communications to maintain the continuous connectivity. In this paper, we propose a new dynamic cooperation scheme that employs a dynamic forwarder selection strategy to generate an adaptive multi-hop V2V path for connectivity maintenance and throughput enhancement at a vehicle located outside of the RSU's coverage range. For the commonly assumed scenario that all vehicles travel in the same direction and at the same speed, we develop an analytical model and derive closed-formed expressions for the average out-of-range connection time, number of service resumptions and achieved throughput. The developed analytical model provides insights into the impacts of inter-RSU distance, vehicles' assistance willingness and the target vehicle's buffer size to the network performance. Simulation results with practical parameter settings show that our proposed scheme is effective in improving connectivity while offering a high throughput for the target vehicle. In particular, a high vehicle density, more assistance willingness by the forwarders and a large buffer size at the target vehicle are shown to be helpful in sparse RSU deployments. © 2000-2011 IEEE.

All (k;g)-cages are k-edge-connected

- Lin, Yuqing, Miller, Mirka, Rodger, Chris

  • Authors: Lin, Yuqing , Miller, Mirka , Rodger, Chris
  • Date: 2005
  • Type: Text , Journal article
  • Relation: Journal of Graph Theory Vol. 48, no. 3 (2005), p. 219-227
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  • Description: A (k;g)-cage is a k-regular graph with girth g and with the least possible number of vertices. In this paper, we prove that (k;g)-cages are k-edge-connected if g is even. Earlier, Wang, Xu, and Wang proved that (k;g)-cages are k-edge-connected if g is odd. Combining our results, we conclude that the (k;g)-cages are k-edge-connected. © 2005 wiley Periodicals, Inc.
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Improved lower bound for the vertex connectivity of (delta;g)-cages

- Lin, Yuqing, Miller, Mirka, Balbuena, Camino

  • Authors: Lin, Yuqing , Miller, Mirka , Balbuena, Camino
  • Date: 2005
  • Type: Text , Journal article
  • Relation: Discrete Mathematics Vol. 299, no. 1-3 (Aug 2005), p. 162-171
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  • Description: A (delta, g)-cage is a delta-regular graph with girth g and with the least possible number of vertices. We prove that all (delta, g)-cages are r-connected with r >= root(delta + 1) for g >= 7 odd. This result supports the conjecture of Fu, Huang and Rodger that all (delta; g)-cages are delta-connected. (c) 2005 Elsevier B.V. All rights reserved.
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  • Description: 2003001397

How bioregional history could shape the future of agriculture

- Brown, Julian, Barton, Philip, Cunningham, Saul

  • Authors: Brown, Julian , Barton, Philip , Cunningham, Saul
  • Date: 2021
  • Type: Text , Book chapter
  • Relation: Advances in Ecological Research p. 149-189
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  • Description: Biodiversity conservation and agriculture are becoming intimately intertwined. Wildlife-friendly agriculture is promoted as a way to conserve biodiversity, connect nature reserves, facilitate climate-driven range shifts and enhance ecosystem services to agriculture. Yet some approaches that increase native biodiversity in agricultural landscapes, such as tropical agroforestry, may support a suite of species that is distinct from nearby remnant habitat. Wildlife-friendly farming, therefore, does not necessarily facilitate native species persistence through landscape conversion to agriculture or facilitate the movement of local species among nature reserves. We argue the historical composition of native species in agricultural landscapes can be maintained by enhancing ecological similarity between production land uses and natural ecosystems. Some agricultural systems already support native species from, and share some ecological attributes with, natural grasslands, wetlands and forests. However, we suggest there are benefits to be gained by focusing on the finer details of similarities in structure, floristic composition (e.g. crop species) and disturbance regimes occurring across natural and modified habitat types. A key advancement of this approach is that the composition of agricultural diversity and its spatio-temporal dynamics are selected and managed according to the spatial and temporal habitat requirements of the wildlife species naturally inhabiting the local area. We argue that ensuring ecological similarity between agricultural systems and the ecosystems they replaced or lie between will strengthen the capacity of agricultural landscapes to maintain historical species pools and provide spatial and temporal connectivity between nature reserves and analogous future climatic zones. © 2021 Elsevier Ltd

A new proof of Balinski's theorem on the connectivity of polytopes

- Pineda-Villavicencio, Guillermo

  • Authors: Pineda-Villavicencio, Guillermo
  • Date: 2021
  • Type: Text , Journal article
  • Relation: Discrete Mathematics Vol. 344, no. 7 (2021), p.
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  • Description: Balinski (1961) proved that the graph of a d-dimensional convex polytope is d-connected. We provide a new proof of this result. Our proof provides details on the nature of a separating set with exactly d vertices; some of which appear to be new. © 2021 Elsevier B.V.

On the connectivity of (k, g)-cages of even girth

- Lin, Yuqing, Balbuena, Camino, Marcote, Xavier, Miller, Mirka

  • Authors: Lin, Yuqing , Balbuena, Camino , Marcote, Xavier , Miller, Mirka
  • Date: 2008
  • Type: Text , Journal article
  • Relation: Discrete Mathematics Vol. 308, no. 15 (2008), p. 3249-3256
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  • Description: A (k,g)-cage is a k-regular graph with girth g and with the least possible number of vertices. In this paper we give a brief overview of the current results on the connectivity of (k,g)-cages and we improve the current known best lower bound on the vertex connectivity of (k,g)-cages for g even. © 2007 Elsevier B.V. All rights reserved.
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A lower bound on the order of regular graphs with given girth pair

- Balbuena, Camino, Jiang, Tingshun, Lin, Yuqing, Marcote, Xavier, Miller, Mirka

  • Authors: Balbuena, Camino , Jiang, Tingshun , Lin, Yuqing , Marcote, Xavier , Miller, Mirka
  • Date: 2007
  • Type: Text , Journal article
  • Relation: Journal of Graph Theory Vol. 55, no. 2 (2007), p. 153-163
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  • Description: The girth pair of a graph gives the length of a shortest odd and a shortest even cycle. The existence of regular graphs with given degree and girth pair was proved by Harary and Kovács [Regular graphs with given girth pair, J Graph Theory 7 (1983), 209-218].
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  • Description: The girth pair of a graph gives the length of a shortest odd and a shortest even cycle. The existence of regular graphs with given degree and girth pair was proved by Harary and Kovács [Regular graphs with given girth pair, J Graph Theory 7 (1983), 209-218]. A (
  • Description: 2003004727
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