Life is short. The impact of power states on base station lifetime

We study the impact of power state transitions on the lifetime of base stations (BSs) in mobile networks. In particular, we propose a model to estimate the lifetime decrease/increase as a consequence of the application of power state changes. The model takes into account both hardware (HW) parameters, which depend on the materials used to build the device, and power state parameters, that instead depend on how and when power state transitions take place. More in depth, we consider the impact of different power states when a BS is active, and one sleep mode state when a BS is powered off. When a BS reduces the power consumption, its lifetime tends to increase. However, when a BS changes the power state, its lifetime tends to be decreased. Thus, there is a tradeoff between these two effects. Our results, obtained over universal mobile telecommunication system (UMTS) and long term evolution (LTE) case studies, indicate the need of a careful management of the power state transitions in order to not deteriorate the BS lifetime, and consequently to not increase the associated reparation/replacement costs

Platelets and Hepatocellular Cancer: Bridging the Bench to the Clinics

Growing interest is recently being focused on the role played by the platelets in favoring hepatocellular cancer (HCC) growth and dissemination. The present review reports in detail both the experimental and clinical evidence published on this topic. Several growth factors and angiogenic molecules specifically secreted by platelets are directly connected with tumor progression and neo-angiogenesis. Among them, we can list the platelet-derived growth factor, the vascular endothelial growth factor, the endothelial growth factor, and serotonin. Platelets are also involved in tumor spread, favoring endothelium permeabilization and tumor cells\u2019 extravasation and survival in the bloodstream. From the bench to the clinics, all of these aspects were also investigated in clinical series, showing an evident correlation between platelet count and size of HCC, tumor biological behavior, metastatic spread, and overall survival rates. Moreover, a better understanding of the mechanisms involved in the platelet\u2013tumor axis represents a paramount aspect for optimizing both current tumor treatment and development of new therapeutic strategies against HCC

Platelets and hepatocellular cancer: Bridging the bench to the clinics

Growing interest is recently being focused on the role played by the platelets in favoring hepatocellular cancer (HCC) growth and dissemination. The present review reports in detail both the experimental and clinical evidence published on this topic. Several growth factors and angiogenic molecules specifically secreted by platelets are directly connected with tumor progression and neo-angiogenesis. Among them, we can list the platelet-derived growth factor, the vascular endothelial growth factor, the endothelial growth factor, and serotonin. Platelets are also involved in tumor spread, favoring endothelium permeabilization and tumor cells' extravasation and survival in the bloodstream. From the bench to the clinics, all of these aspects were also investigated in clinical series, showing an evident correlation between platelet count and size of HCC, tumor biological behavior, metastatic spread, and overall survival rates. Moreover, a better understanding of the mechanisms involved in the platelet-tumor axis represents a paramount aspect for optimizing both current tumor treatment and development of new therapeutic strategies against HCC

A simple analytical model for the BS lifetime

We propose a simple analytical model to evaluate the base station (BS) lifetime subject to power state changes (i.e., transmitted power or a sleep mode (SM)). We first consider the effect of setting the power state, and the impact of transitions occurring between the power states. We then build a model to compute the probability distribution of lifetime for a single BS, given the hardware (HW) parameters and the transition probabilities between the power states. Our results, obtained over a 4G scenario, show that frequent power state changes may deteriorate the BS lifetime. However, if the BS survives for a sufficient amount of time, then the impact on the lifetime is reduced. Finally, we have compared the costs due to the reduction of lifetime (i.e., reparation and replacement of BS HW) with the monetary savings introduced by the energy-aware policies

Modeling the impact of power state transitions on the lifetime of cellular networks

We consider the effect of power state transitions on the lifetime of Base Stations (BSs) in a cellular network. In particular, we take into account the impact of putting in sleep mode the BS, and also the change of the radiated power. When the BS reduces its power consumption, its lifetime tends to increase, as a consequence of the temperature reduction. However, the change in the power state triggers a negative effect which instead tends to reduce the BS lifetime. We therefore propose a model to evaluate the BS lifetime considering the two aforementioned effects, triggered either by the application of a sleep mode state or a change in the radiated power. Our results, obtained over a representative case study, indicate that the BS lifetime may be negatively affected when power state transitions take place. Therefore, we argue that the lifetime should be considered in the process of deciding how and when to change from a power state to another one

Fatigue-aware management of cellular networks infrastructure with sleep modes

We consider the problem of controlling the rate of failures triggered by fatigue processes of Base Stations (BSs) in cellular networks subject to Sleep Modes (SMs). Specifically, the increase of time spent in SM tends to decrease the BS failure rate by following, e.g., the Arrhenius law. However, the transitions between the power states tend to increase the BS failure rate, which can be predicted by the Coffin- Manson model. In this context, the energy savings triggered by SMs would not be economically useful if the BS failure rate were increased too much. Our goal is therefore to tackle the problem of minimizing the BS failure rate in a cellular network subject to SMs. After showing that the optimal formulation of the problem is NP-Hard, we propose a new algorithm, named LIFE, to practically solve it. We run LIFE on different scenarios (driven by LTE and legacy UMTS technologies). Our results show that LIFE outperforms two previous energy-aware algorithms, which instead do not take into account the BS failure rate. Specifically, our solution is able to achieve up to 40% of power saving during night, without a strong penalty in the BS failure rate

Sleep to stay healthy: managing the lifetime of energy-efficient cellular networks

We target the problem of managing the Base Stations (BSs) lifetime and their energy efficiency when a sleep mode (SM) is adopted. We first show that the BS lifetime is affected by two opposite effects: the duration of SM, which tends to increase the lifetime, and the SM frequency, which on the contrary decreases the lifetime. After optimally formulating the problem for a cellular network, we propose a new heuristic, called LIFE, to practically solve it. Our solution integrates the BS lifetime when SM decisions are considered. Results, obtained over an UMTS scenario and a LTE one, prove that LIFE outperforms two previous energy-efficient algorithms in terms of lifetime performance, since all the previous solutions tend to drastically reduce the BS lifetime. Moreover, we show that LIFE is able to save up to 40% of power during night in the long-term