Handover parameter optimization in LTE self-organizing networks

This paper presents a self-optimizing algorithm that tunes the handover (HO) parameters of a LTE (Long-Term Evolution) base station in order to improve the overall network performance and diminish negative effects (call dropping, HO failures). The proposed algorithm picks the best hysteresis and time-to-trigger combination for the current network status. We examined the effects of this self-optimizing algorithm in a realistic scenario setting and the results show an improvement from the static value settings

Self-optimisation of admission control and handover parameters in LTE

In mobile cellular networks the handover (HO) algorithm is responsible for determining when calls of users that are moving from one cell to another are handed over from the former to the latter. The admission control (AC) algorithm, which is the algorithm that decides whether new (fresh or HO) calls that enter a cell are allowed to the cell or not, often tries to facilitate HO by prioritising HO calls in favour of fresh calls. In this way, a good quality of service (QoS) for calls that are already admitted to the network is pursued. In this paper, the effect of self-optimisation of AC parameters on the HO performance in a long term evolution (LTE) network is studied, both with and without the self-optimisation of HO parameters. Simulation results show that the AC parameter optimisation algorithm considerably improves the HO performance by reducing the amount of calls that are dropped prior to or during HO

An enhanced weighted performance-based handover parameter optimization algorithm for LTE networks

This article introduces an enhanced version of previously developed self-optimizing algorithm that controls the handover (HO) parameters of a long-term evolution base station in order to diminish and prevent the negative effects that can be introduced by HO (radio link failures, HO failures and ping-pong HOs) and thus improve the overall network performance. The default algorithm selects the best hysteresis and time-to-trigger combination based on the current network status. The enhancement proposed here aims to maximize the gain provided by the algorithm by improving its convergence time. The effects of this enhancement have been studied in a rural scenario setting and compared to the original algorithm; the results show a clear improvement, faster convergence, and better network performance, because of the enhancement

Load balancing in downlink LTE self-optimizing networks

In this paper we present system level simulation results of a self-optimizing load balancing algorithm in a long-term-evolution (LTE) mobile communication system. Based on previous work, we evaluate the network performance of this algorithm that requires the load of a cell as input and controls the handover parameters. We compare the results for different simulation setups: for a basic, regular network setup, a non-regular grid with different cell sizes and also for a realistic scenario based on measurements and realistic traffic setup

Periostin in ovarian carcinoma: from heterogeneity to prognostic value

Introduction. Periostin (POSTN), an extracellular matrix protein, is involved in tumor-associated extracellular matrix (ECM) remodeling. However, its potential value as a prognostic and/or predictive factor has not yet been confirmed. The present study aims to assess POSTN expression separately in tumor cells and stroma of different ovarian carcinoma (OC) histological types, and its relationship with clinicopathological features. Material and methods. 102 cases of different histological OC subtypes were immunohistochemically investigated, for POSTN expression assessment in both epithelial tumor cells and tumor stroma. Statistical analysis was performed to correlate POSTN profile with clinicopathological characteristics, therapeutic response, and survival. Results.  POSTN expression in epithelial tumor cells was significantly correlated with POSTN expression in tumor stroma. The expression of POSTN in tumor cells was associated with histological type, tumor type (type I and II), tumor recurrence, progression-free survival (PFS), and overall survival (OS), whereas stromal POSTN expression was significantly correlated with age, histological type, tumor type, grade, and stage, residual disease, tumor recurrence, response to chemotherapy, and OS. Survival analysis revealed significant differences of PFS and OS in patients with high POSTN expression in tumor cells and negative stromal POSTN expression compared to patients with low POSTN expression in tumor cells and positive stromal POSTN expression (PFS: hazard ratio (HR) = 2.11, 95% confidence interval (CI): 1.33–3.37, P = 0.002; OS: HR = 1.78, 95% CI: 1.09–2.89, P = 0.019). Conclusions. The comparative assessment of POSTN immunoexpression in two tumor compartments: in tumor cells and stroma, by use of different scoring systems revealed that higher stromal POSTN levels are evidently correlated with unfavorable clinical features and poorer prognosis, while POSTN expression in tumor cells seems to be associated with a better patient outcome