Dynamic Cell Selection Research Articles

Dynamic stem cell selection safeguards the genomic integrity of the epidermis.

Maintaining genomic integrity and stability is crucial for life; yet, no tissue-driven mechanism that robustly safeguards the epithelial genome has been discovered. Epidermal stem cells (EpiSCs) continuously replenish the stratified layers of keratinocytes that protect organisms against various environmental stresses. To study the dynamics of DNA-damaged cells in tissues, we devised an invivo fate tracing system for EpiSCs with DNA double-strand breaks (DSBs) and demonstrated that those cells exit from their niches. The clearance of EpiSCs with DSBs is caused by selective differentiation and delamination through the DNA damage response (DDR)-p53-Notch/p21 axis, with the downregulation of ITGB1. Moreover, concomitant enhancement of symmetric cell divisions of surrounding stem cells indicates that the selective elimination of cells with DSBs is coupled with the augmented clonal expansion of intact stem cells. These data collectively demonstrate that tissue autonomy through the dynamic coupling of cell-autonomous and non-cell-autonomous mechanisms coordinately maintains the genomic quality of the epidermis.

Load-Driven Dynamic User Assignment Algorithms for Dense Cellular Networks

A key option to further increase mobile network capacity is to deploy dense cellular networks (DCNs). This densification of cellular networks raises challenging issues though, as it likely increases the spatial variation and temporal fluctuations in load. To harness the full potential of DCNs, cell selection algorithms must take these varying load conditions into account. In this paper we study the optimal user association in DCNs based on a Linear Program (LP). Since several system parameters tend to be unknown and time-varying in practice, we develop a dynamic, self-organizing, and load-aware cell selection algorithm: the Shadow Price Assignment (SPA) algorithm. Our algorithm realizes an optimal user association without explicit knowledge of the system parameters by using a parsimonious set of dynamically adapted control parameters. We establish convergence of the control parameters under suitable assumptions. For larger systems the convergence may be slower, and we propose a local clustering approach to further improve the user-perceived performance in systems with many APs. Extensive simulations confirm that the SPA algorithm substantially outperforms conventional approaches.

Bandwidth Distribution Algorithm of Applications in LTE-Femtocell Network

The wireless communication has become the essential of today’s Internet of Things (IoT) and mobile applications which is increasing exponentially in near future. These applications demand high data rate to speed up the communication among IoT or internet applications. The data rate requirement of individual application is different. To fulfill these demands of every application Long Term Evolution (LTE) integrated with femtocell technology is identified as suitable wireless technology. The running applications on a user equipment changes dynamically. Hence in dense deployment of femtocell and IoT devices, the bandwidth distribution to many active applications becomes more complicated. For multiple running applications per device with available bandwidth constraint, optimal bandwidth allocation to applications has become the most challenging issue. We include the bandwidth allocation to applications during handover of user equipment in LTE-femtocell network. The handover procedure needs efficient cell selection criteria for target cell selection. Hence in our research we focus on bandwidth distribution among applications by proposing “Efficient Bandwidth Distribution” (EBD) mechanism and efficient cell selection by “Dynamic Cell Selection” (DCS) mechanisms to mitigate above mentioned issues.

INTERCELL INTERFERENCE MITIGATION IN MICROCELL USING DYNAMIC CELL SELECTION TECHNIQUE

In large cellular network macro cells are used as they cover large areas about more than 5km in radius but they have drawbacks when we consider the services between these cells, the areas where the signal quality decays are large shopping malls, small garages, tunnels and underground railways, as macro cells is unable to cover these specific areas. So here the microcells are required. Microcells cover almost 1Km radius so the areas where the macro cells are unable to provide services, microcells are used. Microcells are deployed relatively closer than macro cells so they experience intercell interference, which occurs when UE(user equipment) is at edge of a cell and receiving signals from two base stations simultaneously but with same carrier frequency, here problem arises for the user for the selection of base station, so DCS (Dynamic cell selection) is applied between the cells to reduce the interference between the cells.

Cross-Layer Performance of Downlink Dynamic Cell Selection With Random Packet Scheduling and Partial CQI Feedback in Wireless Networks With Cell Sleeping

In this paper, we consider a coordinated multipoint dynamic cell selection (DCS) transmission scheme for serving sleeping cell user equipments (UEs). According to this DCS scheme, packets of UEs in a sleeping cell are randomly forwarded to the potential active base stations (BSs) by the packet serving gateway and UEs in the sleeping cell dynamically select their serving BS from these active BSs. We model the system as a fork/join (F/J) queuing system and develop a cross-layer analytical model that considers the time varying nature of the channels, channel scheduling mechanism, partial channel quality information feedback, cell selection mechanism, bursty packet arrivals, and packet scheduling mechanism. The developed analytical model can be used to measure various packet-level performance parameters, such as packet loss probability (PLP) and queuing delay while accounting for out-of-sequence packet delivery. We validate the accuracy of the developed analytical model via simulations, and we compare the performance of the DCS scheme under consideration with the conventional fixed cell selection scheme and with the state-of-the-art DCS scheme. Presented numerical results show that the DCS scheme under consideration significantly improves the PLP performance. Queuing delay performance, on the other hand, depends on the system and operating parameters.

Highly efficient digital quadrature transmitter with dual VDD and dynamic cell selection

A digital quadrature dual VDD transmitter with a switched capacitor power combiner is presented. To improve the efficiency, the cell in the transmitter is dynamically selected to minimise the voltage across the capacitors, thereby minimising the discharging loss. The chip is fabricated in 28-nm CMOS process. The implemented transmitter has a peak power of 17.2 dBm with a PAE of 37.4% at 880 MHz. The average power is 7.9 dBm with a PAE of 23.6% under ACLR of −32 dBc using a 10 MHz, 16 QAM, and 6.9 dB LTE signal.

Dynamic Inter-RAT Handover Decision for Offloading Heavy Traffic in Heterogeneous Networks

We present a dynamic inter-RAT handover decision mechanism that allocates network resource for UEs over heterogeneous cells considering UE's mobility, QoS, cell transition, and inter-cell interference for overload situations. It aims to minimize access failure and handover signalling, while prioritizing UEs with high QoS level for differentiated cell selection. We formulate the problem of dynamic cell selection over a period of time into an optimization problem consisting of step-wise integer programs depending on UE's moving speed. Simulation results show that our dynamic scheme achieves low access failure ratio in a highly overloaded network. More importantly, the proposed algorithm remarkably diminishes cell handover rate by 20 % compared to a counterpart algorithm based on static optimization. We demonstrate that our algorithm successfully controls cell acceptance and connected cell types by prioritizing with UE's QoS, moving speed, and inter-cell interference.

Comp-Jt With Dynamic Cell Selection, Global Precoding Matrix And Irc Receiver For Lte-A

Comp-Jt With Dynamic Cell Selection, Global Precoding Matrix And Irc Receiver For Lte-A

Radio Resource Management of CoMP System in HetNet under Power and Backhaul Constraints

Recently, Heterogeneous Network (HetNet) with Coordinated Multi-Point (CoMP) scheme is introduced into Long Term Evolution-Advanced (LTE-A) systems to improve digital services for User Equipments (UEs), especially for cell-edge UEs. However, Radio Resource Management (RRM), including Resource Block (RB) scheduling and Power Allocation (PA), in this scenario becomes challenging, due to the intercell cooperation. In this paper, we investigate the RRM problem for downlink transmission of HetNet system with Joint Processing (JP) CoMP (both joint transmission and dynamic cell selection schemes), aiming at maximizing weighted sum data rate under the constraints of both transmission power and backhaul capacity. First, joint RB scheduling and PA problem is formulated as a constrained Mixed Integer Programming (MIP) which is NP-hard. To simplify the formulation problem, we decompose it into two problems of RB scheduling and PA. For RB scheduling, we propose an algorithm with less computational complexity to achieve a suboptimal solution. Then, according to the obtained scheduling results, we present an iterative Karush-Kuhn- Tucker (KKT) method to solve the PA problem. Extensive simulations are conducted to verify the effectiveness and efficiency of the proposed algorithms. Two kinds of JP CoMP schemes are compared with a non-CoMP greedy scheme (max capacity scheme). Simulation results prove that the CoMP schemes with the proposed RRM algorithms dramatically enhance data rate of cell-edge UEs, thereby improving UEs fairness of data rate. Also, it is shown that the proposed PA algorithms can decrease power consumption of transmission antennas without loss of transmission performance.

동적 셀 선택 기반 기회적 간섭 정렬

An opportunistic interference alignment based on dynamic cell selection is proposed. Since the proposed method can switch the desired signal space and the interference space of received signals, an additional selective diversity gain increases. The performance analysis using probabilistic models provides a mathematical expression for the sum-rate capacity. Simulation examples show that the proposed method achieves the higher sum-rate capacity than that of the conventional opportunistic interference alignment.

Multiuser Adaptive Subcarrier-and-Bit Allocation With Adaptive Cell Selection for OFDM Systems

Adaptive resource allocation has been identified as one of the key technologies for providing efficient utilization of the limited power and spectrum in future wireless systems. In this paper, an adaptive resource allocation methodology is proposed for cellular orthogonal frequency division multiplexing systems in a multiuser environment. The proposed method is featured as a low-complexity algorithm that involves not only adaptive modulation, but also adaptive multiple-access control and cell selection. Specifically, a multiuser subcarrier-and-bit loading scheme is developed to maximize the spectral efficiency. Besides, a dynamic cell selection scheme is proposed to deal with the problem of overloading and nonuniform traffic density. Numerical results show that the presented algorithm offers significant improvement in spectral efficiency due to the successful exploitation of channel variation, multiuser diversity, and inter-cell diversity.