QoS约束下多层异构蜂窝网中基于分层休眠的节能机制研究

针对多层异构蜂窝网中资源分配和节能问题,本文基于随机几何模型利用分布式配对算法实现了用户连接和资源分配的联合优化,并利用分层休眠机制提升了系统的整体能效。首先,采用随机几何工具对不同类型的基站进行建模,在建立模型的基础上提出用户QoS约束下的最小化系统总功耗的联合优化方案,然后将该方案分解简化为用户连接资源分配和基站休眠两个子问题,并分别利用稳定配对算法和基于投票法的分层休眠机制加以解决。仿真和分析结果表明本文方法可以显著提升系统能效,与已有的休眠策略相比具有更低的用户平均中断比。      

Renewable Energy Assisted Function Splitting in Cloud Radio Access Networks

Mobile Networks and Applications - Cloud-Radio Access Network (C-RAN) is a promising network architecture to reduce energy consumption and the increasing number of base station deployment costs in...     

Small Cells in Cellular Networks: Challenges of Future HetNets

Due to their low cost and easy deployment, small cells provide a viable and cost-effective way of improving the cellular coverage and capacity both for homes and enterprises, both in metropolitan and rural areas. Stimulated by their attractive features and advantages, the ongoing development and deployment of small cells by manufacturers and mobile network operators have seen a surge in recent years. Together with macro-cells, they form, what are called Heterogeneous Networks or HetNets. However, the successful rollout and operation of small cells are still facing significan issues. In this paper the need for, challenges and solutions of small cell deployments are analyzed. This analysis is conducted with respect to self-organizing features, interference coordination, energy efficiency and spectrum efficiency. The analysis is complemented with numerical results based on system simulations in Macro-only and HetNet scenarios and also on real measurements performed on an mobile operator network. Results show the clear improvement that a HetNet brings in term of user throughput and also the amunt of spectrum waste that is present in nowadays’ operator networks.     

Device-to-Device Assisted Downlink Broadcast Channel in Cellular Networks

In this paper, two protocols of device-to-device (D2D) communication are proposed to assist multi-input multi-output downlink broadcast channel in cellular networks. Devices in a D2D group are arranged to extract their own data originated from a base station (BS) in an order according to their decoding performance. At each intermediate hop, a best-decoding node is selected and responsible for the next hop transmission. In the first protocol, the selected user forwards its own data stream after decoding, then a proper interference cancellation is performed at each receiving node to eliminate this interference from the buffered reception of the broadcast channel in the first hop from the BS. A closed form representation of the outage probability of each node is derived. In the second protocol, the selected user re-constructs its own signal and cancels this signal from its received vector and forwards the resultant vector. This forwarded signal contains less interference and preserves the data information for the users who have not yet decoded their data. The receiving nodes decode their data streams by jointly considering the received vectors from all the previous hops. The comparison of the two proposed protocols in terms of computational complexity, achieved diversity order and performance are provided. We show that the proposed protocols provide promising diversity gain and avoid error propagations as compared to traditional schemes.     

The Cellular Relay Carpet: Distributed Cooperation with Ubiquitous Relaying

We consider the up- as well as downlink of a cellular network in which base stations (BSs) are supported by a large amount of relays spread over the entire area like a carpet. The BSs only see the static relays as the nodes they communicate with, which enables large antenna arrays at the BSs with sophisticated multi-user MIMO transmission. Together with a simple form of BS cooperation, the communication via the small relay cells allows to improve the data rates by distributed interference management and to reduce the complexity at the terminals. We investigate different types of relays as well as different relaying strategies for this relay carpet and compare them with respect to complexity, required channel state information (CSI), and performance in the interference-limited environment of dense cellular networks. The robustness of the different schemes with respect to channel estimation errors is studied and we conclude that especially relays of very low complexity are not sensitive to CSI imperfections. Relays can thus be applied in large numbers and enable massive MIMO at the BSs. The relay carpet proves thereby to be an efficient approach to enhance future generations of cellular networks significantly.     

Energy Efficient Opportunistic Routing with Sleep Scheduling in Wireless Sensor Networks

Wireless Personal Communications - The network life of wireless sensor networks (WSNs) relies on the limited energy of non-rechargeable batteries used at the sensor node. Hence, maximum energy...     

CSCW系统中的协作支持

设计ＣＳＣＷ系统结构的关键问题是如何提供有效的协作支持本文提出了一个分层的协作支持方案，此方案包括三层：面向系统，面向应用以及面向共享对象的协作支持，相应于这一方案，本文还提出了一个可容纳多种协同应用，并基于公共平台的ＣＳＣＷ系统体系结构，通过对言之有理三层协作支持的实现，多媒体桌面会议系统ＴＨ－ＭＤＣＳ可借助视频，音频，图象，图形，文本等多种媒体形式方便有效地支持分散在各地汪同专业领域的小组成员     

新能源微电网综合实验平台及教学研究

新能源微电网综合实验平台集成了多种分布式发电与储能装置,其结构灵活多变,可满足不同运行方式的需求.本文介绍了该实验平台系统架构与硬件组成,以及集中式管理系统,并选取三类代表性运行模式进行介绍.借助该综合实验平台设计了分布式电源运行特性验证、并网逆变器控制策略设计、并离网状态切换、运行优化策略验证等实验,通过教学实践增强...     

双向能量协作的中继系统功率分配算法

在无线中继系统中,考虑源节点和中继节点都是能量采集的,而源与中继之间可以进行能量协作,即可双向传递能量,针对瑞利衰落信道场景以最大化系统吞吐量为目标,联合优化源节点的发射功率、中继节点的发射功率以及传递的能量值,提出了双向能量传递的最优功率分配算法。本文根据场景模型建立了最优化问题,利用凸优化知识求得最优解的形式,假设能量传递无损耗情况下提出了理想功率分配方案;然后以此为基础,在满足能量因果性和数据因果性的条件下,对传递的能量和发送的功率进行优化。仿真结果表明,本文提出的双向能量传递的功率分配算法优于其它的功率分配算法,能有效的提高系统吞吐量。      

Energy Efficient Cooperation with Chip-Interleaved Transceivers in WSNs Over Frequency-Selective Fading Channels

Cooperative diversity techniques have been utilized to improve the energy efficiency of wireless sensor networks (WSNs) operating over flat fading channels in a considerable number of literature. However, wireless channels of WSNs operating in indoor environments are supposed to be characterised by frequency-selective fading. Theoretical analysis of energy efficient cooperative communications in WSNs operating in indoor environments are rarely addressed. Therefore, this paper studies the energy efficient cooperative communications in WSNs operating over frequency-selective fading channels. Closed-form bit error rate expressions are derived for systems over frequency-selective fading channels. In order to fully explore the energy conservation potential of cooperative communications, solutions of the optimal transmit power allocation and the partner node selection are provided. Moreover, it is proven that the communication quality can be greatly improved by using chip-interleaving techniques in WSNs subject to flat fading channels. Thus, this paper investigates the energy-saving potential of chip-interleaved transceivers in WSNs subject to frequency-selective fading. Numerical results show that significant energy savings can be achieved via cooperations with chip-interleaved transceivers in WSNs operating in indoor environments.

     

中继协同的无线物联能量收集和信息传输算法

本文针对两跳无线物联通信系统,对中继节点利用收集的能量采用功率分流法进行能量收集和信息传输算法进行了设计,其中算法设计是基于能效最大化的优化准则,能效函数定义为瞬时吞吐量与硬件电路总功耗的比值,中继节点利用源节点发送的信号进行能量收集,考虑EARTH计划中实际的功率转换效率和硬件电路损耗的功耗因子,推导了中继协同的无线物联系统能量收集和信息传输的最优功率分配方案的解析解,由于优化问题是非凸问题,为了解决该问题,本文利用高信噪比近似法并通过拉格朗日算法和Lambert W函数获得了优化问题的最优解,数值仿真验证了所提方案的正确性和有效性。      

Distributed Power Control for Energy Conservation in Hybrid Cellular Network with Device-to-Device Communication

Device-to-Device （D2D） com- munication has been proposed as a promising implementation of green communication to benefit the existed cellular network. In order to limit cross-tier interference while explore the gain of short-range communication, we devise a series of distributed power control （DPC） schemes for energy conservation （EC） and enhancement of radio resource utilization in the hybrid system. Firstly, a constrained opportunistic power control model is built up to take advantage of the interference avoidance methodology in the presence of service requirement and power constraint. Then, biasing scheme and admission control are added to evade ineffective power consumption and maintain the feasibility of the system. Upon feasibility, a non-cooperative game is further formulated to exploit the profit in EC with minor influence on spectral efficiency （SE）. The convergence of the DPC schemes is validated and their performance is confirmed via simulation results.     

Cluster based resource allocation in two‐tier HetNets with hierarchical throughput constraints

Two‐tier heterogeneous networks (HetNets), formed by deploying small cell base stations (SBSs) over existing macrocells, can enhance the network performance in future fifth generation network. However, the cross‐/co‐tier interference in HetNets also will severely influence the user throughput of both tiers. In this paper, we investigate the resource allocation and interference mitigation problem in cluster based orthogonal frequency division multiple access (OFDMA) two‐tier HetNets. In a typical cluster, one SBS is selected as the cluster head to allocate resources among all small cells to guarantee their throughput requirements. Hybrid access policy enables small cells to suppress the cross‐tier interference and earn additional revenue from macrocells, but it also leads to decrease of available resources for small cell users (SUs). To compensate hybrid access SBSs for their resources loss, we impose hierarchical SU throughput constraints on the optimization problem, which guarantee these small cells more resources than closed access ones. Besides, the cross‐tier interference constraint is also considered to protect the transmissions of macrocell users. Accordingly, a subgradient iteration based resource allocation algorithm is proposed. Numerical results show that the proposed algorithm can satisfy SU throughput constraints of all small cells with different access policies and guarantee quality of service requirements of all accessed macrocell users in hybrid access small cells.     

低功率激光的生物刺激作用机理及研究

近年来 ,低功率激光的生物刺激作用的研究取得了可喜的成果 ,在临床上已经应用到各个领域 ,在对某些疾病的治疗效果是肯定的。但还存在许多问题 ,作用机理还没有统一。本文就低功率激光的生物刺激作用的一些典型实验研究 ,治病机理的研究进展以及存在的问题进行了评述     

A Distributed Power Allocation Scheme for Base Stations Powered by Retailers with Heterogeneous Renewable Energy Sources

Owing to the intermittent power generation of renewable energy sources (RESs), future wireless cellular networks are required to reliably aggregate power from retailers. In this paper, we propose a distributed power allocation (DPA) scheme for base stations (BSs) powered by retailers with heterogeneous RESs in order to deal with the unreliable power supply (UPS) problem. The goal of the proposed DPA scheme is to maximize our well‐defined utility, which consists of power satisfaction and unit power costs including added costs as a non‐subscriber, based on linear and quadratic cost models. To determine the optimal amount of DPA, we apply dual decomposition, which separates the master problem into sub‐problems. Optimal power allocation from each retailer can be obtained by iteratively coordinating between the BSs and retailers. Finally, through a mathematical analysis, we show that the proposed DPA can overcome the UPS for BSs powered from heterogeneous RESs.     

能量收集辅助的矿山物联网智能计算卸载方法

针对计算、能量和内存资源受限的矿山物联网设备和大量时延敏感型计算任务需求的智慧矿山场景,该文提出一种能量收集(EH)辅助的矿山物联网智能计算卸载方法。通过采用移动边缘计算(MEC)技术协助矿山物联网设备任务计算,同时利用能量收集技术为能量受限的矿山物联网设备供电。基于Q-learning的智能计算卸载机制实现在不可精确获取矿井系统模型的情况下动态探索最优计算卸载策略。此外,为处理复杂矿井环境下的维度灾难问题并减小策略离散化导致的离散化误差,该文还提出一种基于深度确定性策略梯度(DDPG)的计算卸载机制来进一步提高井下任务计算卸载性能。理论分析与仿真结果表明所提机制可降低系统的能量损耗、计算时延和任务处理失败率,有助于保障矿山物联网的安全和高效生产。     

无人机群辅助的数据采集能耗优化方法

针对无线传感器网络(WSN)中数据采集的安全性和能耗问题,该文提出一种无人机(UAV)群辅助的数据采集能耗优化方法。该方法通过优化无人机的数量、高度和WSN中数据传输数量降低系统总能耗。首先,针对WSN数据采集,提出一种基于信誉值的数据双层压缩(RDCC)算法。该算法根据地理位置将传感器分簇,簇内传感器分为簇头和簇成员,簇成员负责训练预测模型并发送给簇头;簇头则负责模型的筛选、聚合以及信誉值更新,并将聚合结果发送给无人机;其次,针对无人机群数据收集,提出一种无人机优化部署算法,该算法将无人机部署问题转化为圆包装问题,通过动态调整无人机数量,最小化无人机群网络总能耗;同时,针对数据采集过程,在无人机群建立了私有区块链用于存储采集数据,保证了数据的安全性;最后,基于伯克利大学联合研究实验室数据集对所提方法进行验证,仿真结果表明该方法能实现无人机的最优部署,同时具有误差小、能耗低及安全性高的优势。     

带有负载转移的光无线融合网跨域节点协同休眠机制

针对跨域节点间的协同休眠、休眠节点负载转移时导致的网络拥塞等问题,该文提出一种带有负载转移的跨域节点协同休眠机制。通过分析光网络单元(ONU)当前负载及休眠ONU与无线路由器间相关性选择休眠节点,并结合最大匹配理论确定休眠节点转移负载的目标节点,从而在保证网络连通性及业务低时延的基础上,进一步降低网络能耗。仿真结果表明,所提出的算法在有效降低整网能耗的同时不会对网络数据包时延产生显著影响。