Analytical Evaluation of Coverage-Oriented Femtocell Network Deployment

This paper proposes a coverage-oriented femtocell network deployment scheme, in which the femtocell base stations (BSs) can decide whether to be active or inactive depending on their distances from the macrocell BSs. Specifically, as the areas close to the macrocell BSs already have satisfactory cellular coverage, the femtocell BSs located inside such areas are kept to be inactive. Thus, all the active femtocells are located in the poor macrocell coverage areas. Based on a stochastic geometric framework, the coverage probability can be analyzed with tractable results. Surprisingly, the results show that the proposed scheme, although with a lower defacto femtocell density, can achieve better coverage performance than that keeping all femtocells in the entire network to be active. The analytical results further identify the achievable optimal performance of the new scheme, which provides mobile operators a guideline for femtocell deployment and operation.Comment: 6 pages, 7 figures, published in IEEE International Conference on Communications (ICC'13

On the physical layer security in large scale cellular networks

This paper studies the information-theoretic secrecy performance in large-scale cellular networks based on a stochastic geometry framework. The locations of both base stations and the mobile users are modeled as independent two-dimensional Poisson point processes. We consider a key feature of the cellular network, namely, information exchange between base stations, and characterize its impact on the achievable secrecy rate of an arbitrary downlink transmission with a certain portion of the mobile users acting as potential eavesdroppers. In particular, analytical results are presented under diverse assumptions on the availability of eavesdroppers' location information at the serving base station, which captures the benefit from the exchange of mobile users' location information between base stations.H. Wang is with the Australian National University and NICTA. NICTA is funded by the Australian Government as represented by the Department of Broadband, Communications and the Digital Economy and the Australian Research Council through the ICT Centre of Excellence program. This work was supported by the Australian Research Councils Discovery Projects funding scheme (Project No. DP110102548 and Project No. DP130101760)

Analytical evaluation of coverage-oriented femtocell network deployment

This paper proposes a coverage-oriented femtocell network deployment scheme, in which the femtocell base stations (BSs) can decide whether to be active or inactive depending on their distances from the macrocell BSs. Specifically, as the areas close to the macrocell BSs already have satisfactory cellular coverage, the femtocell BSs located inside such areas are kept to be inactive. Thus, all the active femtocells are located in the poor macrocell coverage areas. Based on a stochastic geometric framework, the coverage probability can be analyzed with tractable results. Surprisingly, the results show that the proposed scheme, although with a lower defacto femtocell density, can achieve better coverage performance than that keeping all femtocells in the entire network to be active. The analytical results further identify the achievable optimal performance of the new scheme, which provides mobile operators a guideline for femtocell deployment and operation.H. Wang is with the Australian National University and NICTA. NICTA is funded by the Australian Government as represented by the Department of Broadband, Communications and the Digital Economy and the Australian Research Council through the ICT Centre of Excellence program. This work was supported by the Australian Research Councils Discovery Projects funding scheme (Project No. DP110102548 and Project No. DP130101760)

Physical layer security in cellular networks: a stochastic geometry approach

This paper studies the information-theoretic secrecy performance in large-scale cellular networks based on a stochastic geometry framework. The locations of both base stations and mobile users are modeled as independent two-dimensional Poisson point processes. We consider two important features of cellular networks, namely, information exchange between base stations and cell association, to characterize their impact on the achievable secrecy rate of an arbitrary downlink transmission with a certain portion of the mobile users acting as potential eavesdroppers. In particular, tractable results are presented under diverse assumptions on the availability of eavesdroppers' location information at the serving base station, which captures the benefit from the exchange of the location information between base stations.This work was supported by National ICT Australia (NICTA), and the Australian Research Council's Discovery Projects funding scheme (Project No. DP110102548 and DP130101760). NICTA is funded by the Australian Government as represented by the Department of Broadband, Communications and the Digital Economy and the Australian Research Council through the ICT Centre of Excellence program

Data-driven discovery of rules for protein function classification based on sequence motifs

This thesis describes an approach to data-driven discovery of decision trees or rules for assigning protein sequences to functional families using sequence motifs. This method is able to capture regularities that can be described in terms of presence or absence of arbitrary combinations of motifs. A training set of peptidase sequences labeled with the corresponding MEROPS functional families or clans is used to automatically construct decision trees that capture regularities that are sufficient to assign the sequences to their respective functional families. The performance of the resulting decision tree classifiers is then evaluated on an independent test set. Results of experiments that proposed approach matches or outperforms protein function classification based on the presence of a single characteristic motif in terms of accuracy, precision, and recall. We compared the rules constructed using motifs generated by a multiple sequence alignment based motif discovery tool (MEME) with rules constructed using expert annotated ProSite motifs (patterns and profiles). Our results indicate that the former provide a potentially powerful high throughput technique for constructing protein function classifiers when adequate training data are available. Examination of the generated rules in the case of a Caspase (C14) family suggests that the proposed technique might be able to identify combinations of sequence motifs that characterize functionally significant 3-dimensional structural features of proteins

Perceived macroeconomic uncertainty and export: evidence from cross-country data

The Perceived Macroeconomic Uncertainty (PMU) is seen as unpredictable volatility about the future economic development at aggregate level. While prior research explains how uncertainty (in general) influences international trade flows, research on the role of PMU in international trade flows is scarce. This article attempts to address this lack of understanding. Utilizing the gravity model and multicountry level data, our results show that: (1) the level of PMU in both importing countries and exporting countries has a significant negative impact on exports, but the effect of PMU of importing countries is larger than that of PMU of exporting countries; (2) PMU in importing countries has a trade diversion effect, suggesting that exporters are more willing to export to countries with relatively lower level of PMU; (3) the negative effects of PMU on trade have declined after the 2008 Great Financial Crisis, which may be related to the relative stability of the PMU index since the Great Financial Crisis and the increased concern of traders about other factors, such as trade policy uncertainty and Sino-US economic conflicts. Our research enriches prior findings that examine the effects of uncertainty on trade flows and carries important policy implication