Self-organisation in LTE networks : an investigation

Mobile telecommunications networks based on Long Term Evolution (LTE) technology promise faster throughput to their users. LTE networks are however susceptible to a phenomenon known as inter-cell interference which can greatly reduce the throughput of the network causing unacceptable degradation of performance for cell edge users. A number of approaches to mitigating or minimising inter-cell interference have been presented in the literature such as randomisation, cancellation and coordination. The possibility of coordination between network nodes in an LTE network is made possible through the introduction of the X2 network link. This thesis explores approaches to reducing the effect of inter-cell interference on the throughput of LTE networks by using the X2 link to coordinate the scheduling of radio resources. Three approaches to the reduction of inter-cell interference were developed. Localised organisation is a centralised scheme in which a scheduler is optimised by a Genetic Algorithm (GA) to reduce interference. Networked organisation makes use of the X2 communications link to enable the network nodes to exchange scheduling information in a way that lowers the level of interference across the whole network. Finally a more distributed and de-centralised approach is taken in which each of the network nodes optimises its own scheduling in coordination with its neighbours. An LTE network simulator was built to allow for experimental comparison between these techniques and a number of existing approaches and to serve as a test bed for future algorithm development. These approaches were found to significantly improve the throughput of the cell edge users who were most affected by intereference. In particular the networked aspect of these approaches yielded the best initial results showing clear improvement over the existing state of the art. The distributed approach shows significant promise given further development.EPSR

Morphological divergence in multivariate space and rates of morphological divergence.

<p>(A) Molecular phylogenetic tree <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098536#pone.0098536-Ahrens1" target="_blank">[31]</a>, trees with optimized branch lengths by (B) the uncorrected and (C) the size-corrected data set (BBPM), and rates of morphological divergence (multivariate standardized phylogenetic independent contrasts) for (D) the uncorrected and (E) the size-corrected data set mapped on the ultrametric phylogenetic tree showing relative divergence times. The tips of the molecular tree (A) are color-coded for feeding habits (ANT  =  anthophilous, COP  =  coprophagous, HERB  =  herbivorous, SFU  =  sap/fluid utilizers, NF  =  not feeding, SAP  =  saprophagous). Branches in (B) and (C) with significantly lower (blue) and higher (red) morphological rates of evolution are colored respectively. Background shading indicates clade affiliation.</p

Correlated evolution of metacoxal length and the secondary metacoxal ostium.

<p>(A) Reconstruction of relative metacoxal length in ancestral nodes of the molecular phylogeny <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098536#pone.0098536-Ahrens1" target="_blank">[31]</a>. The left hand arrow shows the internal branch where ancestral relative metacoxal length strongly increases and where the secondary ostium of metacoxa is closed by the medial apophysis <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098536#pone.0098536-Garland1" target="_blank">[77]</a>. The right hand arrow points to the clade of <i>Hymenoplia</i> and <i>Paratriodonta</i> (see text for explanation). (B) <i>Chasmatopterus</i> spec., metacoxa, dorsal view: secondary ostium open (arrow). (C) <i>Hymenoplia castilliana</i>, metacoxa, dorsal view: secondary ostium closed (arrow). The numbers in the legend correspond to the size-corrected values of metacoxal length.</p

Correlation between molecular and morphometric distance-matrices for specimens within one feeding type and the complete sampling.

<p>Correlation between molecular and morphometric distance-matrices for specimens within one feeding type and the complete sampling.</p

Lineage diversifications in morphospace.

<p>Phylomorphospace projections of the molecular phylogenetic tree <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098536#pone.0098536-Ahrens1" target="_blank">[31]</a> for the sister clade subsets 1–5 (A–E) and the complete data set (F) showing the first two PC axes of the size-corrected (BBPM) data set.</p

F-values from non-parametric MANOVA of the complete sampling (excluding singletons) regarding 95% of total variation.

<p>F-values from non-parametric MANOVA of the complete sampling (excluding singletons) regarding 95% of total variation.</p

Morphological divergence in multivariate space and rates of morphological divergence.

<p>(A) Molecular phylogenetic tree <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098536#pone.0098536-Ahrens1" target="_blank">[31]</a>, trees with optimized branch lengths by (B) the uncorrected and (C) the size-corrected data set (BBPM), and rates of morphological divergence (multivariate standardized phylogenetic independent contrasts) for (D) the uncorrected and (E) the size-corrected data set mapped on the ultrametric phylogenetic tree showing relative divergence times. The tips of the molecular tree (A) are color-coded for feeding habits (ANT  =  anthophilous, COP  =  coprophagous, HERB  =  herbivorous, SFU  =  sap/fluid utilizers, NF  =  not feeding, SAP  =  saprophagous). Branches in (B) and (C) with significantly lower (blue) and higher (red) morphological rates of evolution are colored respectively. Background shading indicates clade affiliation.</p

F-values from non-parametric MANOVA (Anderson 2001) of each subset (ss1–ss5, excluding singletons) regarding 95% of total variation.

<p>F-values from non-parametric MANOVA (Anderson 2001) of each subset (ss1–ss5, excluding singletons) regarding 95% of total variation.</p

Patterns of morphospace covariation between major phylogenetic lineages and feeding types.

<p>Scatterplots of the principal component scores from the analysis of the complete sampling of (A, D) the uncorrected and the size-corrected data sets from (B, E) the Burnaby Back Projection Method (BBPM) and (C, F) the linear regression method with (A–C) major phylogenetic lineages and (D–F) feeding types projected on it (ANT  =  anthophilous, COP  =  coprophagous, HERB  =  herbivorous, SFU  =  sap/fluid utilizers, NF  =  not feeding, SAP  =  saprophagous). The percentage of variance explained by principal component 1 and 2 is given in each upper right corner. Taxa with more than 2 members are surrounded by a similarly colored hull. (G–I) Morphospace divergence within the feeding types projected on scatterplots of the principal component scores from size corrected data (BBPM): (G) Herbivores, (H) anthophilous, and (I) the remaining feeding types. Dots are color-coded in the molecular phylogeny (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098536#pone-0098536-g003" target="_blank">Figure 3A</a>) for phylogenetic lineages. x-axis: PC1, y-axis: PC2.</p

Additional file 6: Figure S6. of Long-term leukocyte reconstitution in NSG mice transplanted with human cord blood hematopoietic stem and progenitor cells

Gating strategy for assessment of engraftment of HSPCs in bone marrow. A representative example for the assessment of engraftment of HSPCs in bone marrow is shown. Percentages of cell populations were determined as follows: Total HSPCs: Í34+ cells (of CD45+ cells), more primitive cells: Í38- or CD90+ cells (of CD45 + CD34+ or CD45+ cells). (TIF 5264 kb