Resource scheduling in downlink LTE-advanced system with carrier aggregation

In this paper,we focus on the resource scheduling in the downlink of long term evolution advanced (LTE-A) assuming equal power allocation among subcarriers.Considering the backward compatibility,the LT...     

Energy-efficient and QoS-aware discontinuous reception using a multi-cycle mechanism in 3GPP LTE/LTE-advanced

In the paper we present a novel energy-efficient and Quality-of-Service (QoS)-aware Discontinuous Reception (DRX) scheme by using a multi-cycle mechanism for the Long Term Evolution (LTE) networks. The proposed scheme is capable of improving the power-saving efficiency while simultaneously meeting the specific QoS requirements by dynamically tuning the DRX parameters according to the traffic intensity. It is a table-driven method which off-line pre-establishes the optimal DRX parameters corresponding to the traffic intensities and different QoS requirements such as the packet delays and packet loss rates based on a theoretical analysis approach. At runtime, the DRX parameters of each User Equipment (UE) can be determined optimally with a simple table lookup without spending much computational time and resource. The analytical model is validated against simulation experiments. Based on the analysis results, the power-saving efficiency of our proposed multi-cycle DRX scheme can be effectively boosted by about 37 % comparing to that of the typical DRX scheme while simultaneously meeting the specific QoS requirements like the packet delays and packet loss rates under the scenarios with different traffic intensities.     

Delay analysis of DRX in LTE-advanced considering carrier aggregation

The long term evolution advanced (LTE-advanced) standards target at high system performance comparable or superior to the requirements of the International mobile telecommunications advanced (IMT-advanced). In order to support backward compatibility with LTE, most of the key technologies have been retained in LTE-advanced, one of which is the discontinuous reception mechanism (DRX). LTE-advanced adopts carrier aggregation technology to extend the system bandwidth, which requires the LTE DRX applied in single-transceiver scenario to be adapted to multi-transceiver scenario with multiple component carriers. Apparently, carrier aggregation will influence the performance of DRX severely, so it’s worth studying the impact brought by the coexistence of LTE DRX and carrier aggregation on the system performance, e.g., the system delay. In this paper, first an overview of DRX in carrier aggregation scenario is given. Then it is modeled as a Markov process based on the queuing theory. Simulation results show that the independent component carrier configuration with a uniform Inactivity Timer achieves a superior service delay performance compared with other reference schemes.     

一种基于LTE系统的不连续接收方法

针对3GPP的长期演进系统(LTE)的不间断接收(DRX)机制,提出了一种新的DRX的睡眠周期配置方法。该方法根据突发数据业务模型,动态地调整睡眠周期长度。通过仿真分析,该方法可以改善时延特性,并且能有效地降低移动终端的平均能耗。     

Coded modulation for noncoherent reception with application to OFDM

Power- and bandwidth-efficient differentially encoded transmission over slowly time-varying fading channels with noncoherent reception and without channel state information is considered. For high bandwidth efficiencies, combined phase and amplitude modulation is used. For increased power efficiency, channel coding and multiple-symbol differential detection are applied, i.e., interleaving and detection are based on blocks of N>2 consecutive symbols. The presented concepts are directly applicable to transmission over flat fading channels. However, concentrating on the situation of frequency-selective channels, we consider their application to multicarrier transmission using orthogonal frequency-division multiplexing (OFDM). When coding across subcarriers, OFDM transforms the actual frequency-selective channel into a slowly time-varying frequency-nonselective fading channel. This paper presents a design for multilevel coding schemes to approach theoretical limits for power- and bandwidth-efficient noncoherent transmission over the equivalent fading channel. It is shown that bit-interleaved coded modulation, which relies on Gray labeling, is competitive only in the case of conventional differential detection with N=2. The theoretic considerations are well approved by simulation results, where turbo codes are applied as component codes     

Power density aware application mapping in mesh-based network-on-chip architecture: An evolutionary multi-objective approach

In the era of many-core chips, the problem of power density is a serious challenge. This is particularly important in Network-on-Chip (NoC)-based systems, where application mapping determines the resulting power patterns and the workload distribution across the entire chip. Despite this fact, the majority of mapping algorithms focus on performance, and the resulting power patterns are largely ignored. This work investigates this problem. Three different power pattern metrics with different scopes are defined, namely, power peak, power range, and regional power density. The results of using them as mapping objectives together with communication cost using a multi-objective evolutionary mapping approach are investigated. Results show that employing power patterns results-in Pareto fronts with different power patterns and features. Results are analysed and discussed. Moreover, a case study of thermal analysis of the resulting power patterns is performed. Results show that using communication cost only results-in large hotspots which translates into higher peak and range of chip temperatures. The proposed mapping objectives are shown to significantly improve thermal balancing (up to 55%) and peak temperature (up to 7.77%). These results indicate the importance of considering power patterns in the design of NoC-based many-core systems and their direct impact on the reliability and performance of such systems.     

LTE-Advanced系统中载波聚合技术的安全研究

主要分析了LTE-Advanced系统中引入载波聚合技术带来的安全需求,并提出了解决方案。载波聚合技术是LTE-Advanced系统的一个关键技术,它的应用给系统安全带来了新的挑战。文章基于3GPP组织关于载波聚合技术制定的相关标准,对载波聚合技术进行了阐述和分析,根据LTE系统的安全实现方案提出了载波聚合场景下的安全解决方案。     

异构网中载波聚合系统的成员载波选择和干扰协同

为了解决下一代演进移动通信系统在异构网场景由于低功率基站在高功率基站覆盖区域的随意分布而导致的小区间干扰问题及容量速率限制,提出了一种载波聚合系统的成员载波选择和干扰协同方法。该方法基于修正的载波公平比例准则,动态地在小区间协同选择成员载波。为了进一步提高低功率节点的系统容量,设计了新的基于调和平均数的用户小区选择准则及算法。仿真结果表明,与频率复用因子为1的系统相比,设计的方法由于静默了部分高功率节点用户成员载波,从而使低功率节点用户获得更多的选择机会,可提高低功率节点小区的容量。     

负载感知的低开销网络保护机制研究

为提高资源利用率和降低网络阻塞率,提出一种应用于光网络中带有负载感知(LA)的低开销保护机制,充分考虑了网络共享风险链路组(SRLG)的约束条件,建立整数线性规划(ILD)模型对共享通道保护策略与LA技术进行联合优化。仿真表明,与传统机制相比,所提出的机制能够有效地降低网络阻塞以及保护开销,使网络中的流量更加均衡。     

Stochastic modeling for energy efficiency in modified directional discontinuous reception for LTE-5G networks

Fifth-generation (5G) networks deal with high-frequency data rates, ultra-low latency, more reliability, massive network capacity, more availability, and a more uniform user experience. To validate the high-frequency rates, 5G networks engage beam searching operation. By adopting a beam searching state between the short and long sleep, one can reduce the system's delay. The energy consumption of user equipment (UE) in 5G networks is much higher than in the 4G networks. To reduce the energy consumption and increase the energy saving in UE, Long-Term Evolution (LTE)-5G networks adopt the discontinuous reception (DRX) scheme with a fixed number of short sleep. LTE-DRX without beam search operation (i.e., beam alignment) cannot work in 5G networks. Hence, keeping this scenario in mind, we have modeled a new modified directional discontinuous reception (MD-DRX) mechanism for LTE-5G networks. The MD-DRX mechanism captures the behavior of a beam searching, an inactive, an active, a long sleep, an ON, and a short sleep states. The short sleep state consists of a maximum $M$ short sleep. To get the optimal energy saving and energy consumption (i.e., energy efficiency) from the MD-DRX mechanism, it is required to check the system's throughput. The trade-off between energy saving/energy consumption and throughput will provide the system's optimal energy saving and optimal energy consumption. In this paper, we have obtained the system's optimal energy saving and throughput by optimizing the maximum short sleep and short sleep duration. To get the energy efficiency for LTE-5G networks, the trade-off between average energy consumption/energy saving and throughput is shown.     

Autonomous component carrier selection: interference management in local area environments for LTE-advanced - [femtocell wireless communications]

Low-power base stations such as femtocells are one of the candidates for high-data-rate provisioning in local areas, such as residences, apartment complexes, business offices, and outdoor hotspot scenarios. Unfortunately, the benefits are not without new challenges in terms of interference management and efficient system operation. Due to the expected large number of user-deployed cells, centralized network planning becomes impractical, and new scalable alternatives must be sought. In this article we propose a fully distributed and scalable solution to the interference management problem in local areas, basing our study case on LTE-Advanced. We present extensive network simulation results to demonstrate that a simple and robust interference management scheme, called autonomous component carrier selection, allows each cell to select the most attractive frequency configuration; improving the experience of all users and not just the few best ones, while overall cell capacity is not compromised.     

The optimum fin width in p-MuGFETs with the consideration of NBTI and hot carrier degradation

Generally it is known that NBTI degradation increases with decrease of a channel width in p-MOSFETs but hot carrier degradation decreases. In this work, a guideline for the optimum fin width in p-MuGFETs is suggested with consideration of NBTI and hot carrier degradation. Using the device lifetime defined as the stress time necessary to reach ΔV_TH = 10 mV, the optimum fin widths have been extracted for different stress voltages and temperatures. When a fin width is narrower than the optimum fin width, the device lifetime is governed by the NBTI degradation. However, when fin width is wider than the optimum fin width, the device lifetime is dominantly governed by hot carrier degradation. The optimum fin width decreases with the increase of the stress voltage but it increases with the increase of the stress temperature.     

节点连接态势感知的低开销机会网络消息传输策略

利用节点保存的相遇历史信息,提出一种节点连接态势感知的消息传输策略,通过建立时序图模型估计节点间的连接态势,以时延、投递率以及负载率为联合优化目标参数,采用均衡和量化方法,为消息分布式地选择最佳中继节点。仿真结果表明,所提出的消息传输策略能够有效降低网络负载48%以上,并改善消息投递率和平均时延性能。     

基于信漏噪比的异构网络载波干扰协调技术

针对异构网络存在小区间干扰的问题,提出了一种基于频域载波聚合的干扰协调管理机制。该机制将所有小区的用户分为中心用户和边缘用户,采用可降低干扰的信漏噪比(SLNR)准则,动态调度用户和选择小区载波,并将每种小区载波选择方案对应一种调度用户分组的机制,即对小区的中心用户和边缘用户采用不同优先级,以此有效避免小区间的干扰,其中优先级采用比例公平和SLNR准则。仿真结果表明,由于在系统目标最大化时实现了频率复用增益和干扰消除增益间实现最佳的平衡,可有效取得系统流量的分流和总吞吐量的提升。     

机会网络中能量有效的副本分布状态感知路由机制

针对机会网络中的节点能耗与消息扩散程度之间存在矛盾,基于节点能耗与副本状态感知的路由机制可以显著地改善资源受限场景的网络性能,综合考虑消息扩散程度与节点剩余能量,并结合节点相遇概率预测方法,提出能量有效的副本分布状态感知路由机制,为消息分布式地选择合理的中继节点。仿真结果表明,所提出的路由机制能够有效降低网络负载,并大幅改善消息投递率和平均时延性能。     

Residual resources aware distributed admission control mechanism in mobile multi-hop network

Without considering current residual resources of the medium, nodes in mobile ad hoc networks (MANETs) admit the data flow arbitrarily, and the quality of service (QoS) of the data flows deteriorates. To release the contending on the resources induced by the overloaded flows, the admission control mechanism can effectively keep the balance between injected data flows and network capacity, and it is viewed as the most important technology in MANET. A novel distributed residual resources aware admission control mechanism is proposed in this paper, where the residual resources and the service rate are studied thoroughly. Considering the medium utilization, frame retransmission and backoff procedure, the passive method is applied to predict the residual resources, and the binomial distribution is utilized to model the medium status; moreover, based on the cooperation between the source node and intermediate nodes, the path meeting the resource demand is probed across the network, and the flows are rejected while the residual resources cannot meet its demand. Results show that the network load can be constrained by our proposed admission control mechanism, and the QoS of the data flows can be guaranteed effectively.     

An analytical model for determining carrier transport mechanism of polysilicon emitter bipolar transistors

An analytical model is proposed by including carrier transport mechanisms which previous unified analytical models do not consider: minority carrier combination at both sides of polysilicon-silicon interfacial oxides and thermionic emission over segregation potential barriers for determining the precise carrier transport mechanisms which govern current gain and specific emitter interfacial resistivity. This approach allows us to gain an insight into carrier transport mechanisms and provides a distinct image for polysilicon emitter bipolar devices. With the consideration of the interfacial capture cross section as a function of temperature, the dependence of current gain for devices given an HF etch prior to polysilicon deposition on temperature is first explained successfully. For improving device performance, some directive suggestions are presented.<>     

CAPR: context‐aware participant recruitment mechanism in mobile crowdsourcing

With the advances of sensing, wireless communication, and mobile computing, mobile crowdsourcing has become a new paradigm for data collection and retrieval that has attracted considerable attention. This paper addresses the fundamental research issue in mobile crowdsourcing: Which participants should be selected as winners in each time slot with the aim of maximizing the total utility of the service provider in the long term? First, a double‐sided combinatorial auction model is introduced to describe the relationships between the mobile users and requesters from the perspective of supply and demand at a given time. Then, the coupling between the utility values of the system in different time slots is investigated. Based on the aforementioned analyses, this paper proposes a context‐aware participant recruitment mechanism, in which the mobile crowdsourcing system dynamically adjusts the participant recruitment mechanism depending on the ratio between the numbers of mobile users and requesters. Context‐aware participant recruitment consists of two main components: (1) a heuristic algorithm based on the greedy strategy to determine the winning participants and (2) a critical payment scheme, which guarantees the rationality of the proposed mechanism. Finally, extensive simulations demonstrate that the proposed mechanism achieves high system utility in the long term. Copyright © 2016 John Wiley & Sons, Ltd.     

An autonomic risk‐ and penalty‐aware resource allocation with probabilistic resource scaling mechanism for multilayer cloud resource provisioning

Cloud computing environment allows presenting different services on the Internet in exchange for cost payment. Cloud providers can minimize their operational costs by auto‐scaling of the computational resources based on demand received from users. However, the time and cost required to increase and decrease the number of active computational resources are among the biggest limitations of scalability. Thus, auto‐scaling is considered as one of the most important challenges in the field of cloud computing. The present study aimed to present a new solution to automatic scalability of resources for multilayered cloud applications under the Monitor‐Analysis‐Plan‐Execute‐Knowledge loop. In addition, the Google penalty payment model was used to model the penalty costs in the problem and to accurately evaluate the earned profit. A hybrid resource load prediction algorithm was proposed to evaluate the future of resources in each cloud layer. Further, we used statistical solution to determine the statuses of VMs in addition to presenting a risk‐aware algorithm to allocate the user requests to active resources. The experimental results by Cloudsim indicated the improvement of the proposed approach in terms of operational costs, the number of used resources, and the amount of profit.