Adaptive sleep-wake discrimination for wearable devices

Sleep/wake classification systems that rely on physiological signals suffer from intersubject differences that make accurate classification with a single, subject-independent model difficult. To overcome the limitations of intersubject variability, we suggest a novel online adaptation technique that updates the sleep/wake classifier in real time. The objective of the present study was to evaluate the performance of a newly developed adaptive classification algorithm that was embedded on a wearable sleep/wake classification system called SleePic. The algorithm processed ECG and respiratory effort signals for the classification task and applied behavioral measurements (obtained from accelerometer and press-button data) for the automatic adaptation task. When trained as a subject-independent classifier algorithm, the SleePic device was only able to correctly classify 74.94 ± 6.76% of the human-rated sleep/wake data. By using the suggested automatic adaptation method, the mean classification accuracy could be significantly improved to 92.98 ± 3.19%. A subject-independent classifier based on activity data only showed a comparable accuracy of 90.44 ± 3.57%. We demonstrated that subject-independent models used for online sleep-wake classification can successfully be adapted to previously unseen subjects without the intervention of human experts or off-line calibration.     

Adaptive backbone protocol for heterogeneous wireless networks

We propose Adaptive Backbone Protocol ABP, a lightweight protocol for distributed formation of a backbone over Heterogeneous Wireless Networks. ABP does not require any neighborhood information and consequently scales well with the number of nodes and network size. We present an analytical framework to study the performance of ABP. By making the nodes rotate the role of backbone nodes, we extend the life of the network.     

Adaptive connectivity management middleware for heterogeneous wireless networks

The trends of network convergence and mobile accessibility in the Internet are bringing new challenges to the connectivity management of end hosts. Concerning network convergence, the configuration of heterogeneous access networks should be taken into consideration. As for mobile accessibility, seamless handoff between diverse access points is a challenging issue. This article presents the design and implementation of connectivity management middleware (CMM), a channel-based architecture for context-aware connectivity management. This architecture can both provide network awareness to applications and manage network resources in an adaptive fashion. In the case of network awareness, the platform provides interfaces for applications to query network QoS and availability status, as well as subscribe connection events. As for adaptive resource management, channel-based transport services for seamless access switching and disconnection treatment are provided based on a policy mechanism. A prototype is implemented with which experiments were performed in a GPRS-WLAN integrated environment in order to demonstrate the operational correctness of the architecture. Performance metrics are measured and analyzed.     

Adaptive vertical handoff algorithm in heterogeneous networks

The integration of cellular network (CN) and wireless local area network (WLAN) is the trend of the next generation mobile communication systems, and nodes will handoff between the two kinds of networks. The received signal strength (RSS) is the dominant factor considered when handoff occurs. In order to improve the handoff efficiency, this study proposes an adaptive decision algorithm for vertical handoff on the basis of fast Fourier transform (FFT). The algorithm makes handoff decision after analyzing the signal strength fluctuation which is caused by slow fading through FFT. Simulations show that the algorithm reduces the number of handoff by 35%, shortens the areas influenced by slow fading, and enables the nodes to make full use of WLAN in communication compared with traditional algorithms.     

ADYTIA: Adaptive and Dynamic TCP Interface Architecture for heterogeneous networks

Due to the widespread popularity and usage of Internet of things (IoT)‐enabled devices, there is an exponential increase in the data traffic generated from these IoT devices. Most of these devices communicate with each other using heterogeneous links having constraints such as latency, throughput, and interference from concurrent transmissions. This results in an extra burden on the underlying communication infrastructure to manage the traffic within these constraints between source and destination. However, most of the existing applications use different Transmission Control Protocol (TCP) variants for traffic management between these devices and are dependent on the stage of the sender, irrespective of the application types and link characteristics. Each operating system (OS) has different TCP variant for all applications, irrespective of path characteristics. Hence, a single TCP variant cannot select the best suitable link, which results in degradation in throughput compared to the existing default. Moreover, it cannot use the full capacity of the available link for different applications and network links, especially in heterogeneous network such as IoT. To cope up with these challenges, in this paper, we propose an Adaptive and Dynamic TCP Interface Architecture (ADYTIA). ADYTIA allows the usage of different TCP variants based on application and link characteristics, irrespective of the physical links of the entire path. It allows the usage of different TCP variants based on their design principle across heterogeneous technologies, platforms, and applications. ADYTIA is implemented on NS‐2 and Linux kernel for real testbed experiments. Its ability to select the best suitable TCP variant results in 20% to 80% improvement in throughput compared with the existing default and single TCP variant on Linux and Windows.     

HTTP协议技术探析

简单概述了WWW核心技术HTTP协议的地位，以及WEB协议族的工作机制和URL编码和解码，对HTTP协议的运行机制与特性进行了详细介绍，着重论述了协议的缺陷及HTTP1．1的新发展。     

超视距空战的几个观点

介绍了超视距空战武器发展和实战应用,提出了和超视距空战有关的几个观点:信息战和网络中心战是如何影响超视距空战,在超视距中指挥协同和信息的问题,超视距空战和多目标攻击的关系,在超视距空战研究中容易忽视的问题——在空战中如何对付敌方超视距武器,评价战斗机超视距空战能力要考虑的问题,超视距和视距内空战的界限可能逐渐模糊以及无人机在超视距空战中的作用。     

Adaptive subcarrier and bit allocation in OFDMA systems supporting heterogeneous services

Orthogonal Frequency Division Multiple Access (OFDMA) is an efficient multiple access method for the future wireless systems. This paper studies the adaptive subcarrier and bit allocation problem in OFDMA systems to support heterogeneous services. The goal of the considered resource optimization technique is to maximize the total system throughput under the overall transmit power constraint while guaranteeing the QoS requirement of realtime users and supporting proportional fairness among non-realtime users. First, we introduce a Rate Adaptive (RA) resource allocation algorithm for non-realtime users and a Margin Adaptive (MA) algorithm for realtime users. Then, based on the previous algorithms, a novel algorithm is proposed to allocate the resource to both classes of users, which makes an efficient tradeoff between the resource usage of realtime users and non-realtime users. The algorithm is locally optimal solution provided that the MA and RA algorithms are utilized. Also, to reduce the computational complexity, a suboptimal method based on the balancing of the average power per subcarrier is also introduced. Monte Carlo simulation results show that all the proposed algorithms outperform the existing counterparts. The results also show that the suboptimal method for heterogeneous services can efficiently reduce the computational complexity at the cost of very little performance degradation. This work was supported by the National Natural Science Foundation of China (Nos. 60472079, 60572115), and by the Natural Science Foundation of Zhejiang Province (No. Z104252), China.     

GUIDE: Smartphone sensors‐based pedestrian indoor localization with heterogeneous devices

A plethora of indoor localization systems based on Wi‐Fi, radio frequency chips, ultra‐wide‐band, and bluetooth have been proposed, yet these systems do not work when the infrastructure is absent. On the other hand, infrastructure less systems benefit mostly from off‐the‐shelf smartphone sensors and do not need additional hardware. This study shows a similar indoor localization approach which turns smartphone built‐in sensors to good account. We take advantage of magnetic field strength fingerprinting approach to localize a pedestrian indoor. In addition, accelerometer and gyroscope sensors are utilized to find the pedestrian's traveled distance and heading estimation, respectively. Our aim is to solve the problem of device dependence by devising an approach that can perform localization using various smartphones in a similar fashion. We make the use of patterns of magnetic field strength to formulate the fingerprint database to achieve this goal. This approach solves two problems: need to update the database periodically and device dependence. We conduct experiments using Samsung Galaxy S8 and LG G6 for five different buildings with different dimensions in Yeungnam University, Republic of Korea. The evaluation is performed by following three different path geometries inside the buildings. The results show that the proposed localization approach can potentially be used for indoor localization with heterogeneous devices. The errors for path 1 and path 2 are very similar, however, localization error for path 3 is comparatively higher because of the complexity of the path 3. The mean and median errors for Galaxy S8 are 1.37 and 0.88 m while for LG G6, these are 1.84 and 1.21 m, respectively, while considering all buildings and all paths followed during the experiment. Overall, the proposed approach can potentially localize a pedestrian within 1.21 m at 50% and within 1.93 m at 75%, irrespective of the device used for localization. The performance of the proposed approach is compared with the K nearest neighbor (KNN) for evaluation. The proposed approach outperforms the KNN     

南昌市接入网的发展与探讨

简要介绍了光纤接入网的系统组成、组网结构及接入业务,并对南昌市接入网的建设和发展策略提出了几点建议。     

浅谈PHS系统的空中同步

PHS(Personal Handyphone Sysyem)系统 (俗称“小灵通”)作为市话的延伸和补充 ,在中国电信已得到了广泛的应用。随着无线通信技术的不断发展 ,PHS技术同最初在日本应用时相比也得到了较大的发展 :从最初10 m W基站到现在 2 0 m W、2 0 0 m W、5 0 0 m W基站 ,发射功率得到了较大的提高 ,覆盖范围也相应增大 (空旷地带覆盖范围半径可达1.5 km,楼房密集区亦可达 30 0～ 5 0 0 m) ,切换明显减少 ;从最初应用的普通天线到现在普遍应用的自适应智能阵列天线 ,接受灵敏度和频率利用率得到了很大的改善。由于基站覆盖范围的增大 ,千百万基站…     

网络安全与措施探讨

首先分析了Internet的不安全性以及TCP／IP协议自身存在的安全性问题，然后介绍了Internet中近年出现的一些新的安全问题，同时给出了一些相应的解决措施，最后强调了在全社会范围内对网络安全系统加以改善。     

Surface-acoustic-wave devices for communications

Surface-wave components have demonstrated performance capabilities in the VHF/UHF range which are available with no other filtering technique. The major advantages of the filters are their small size, high reliability, low cost, high Q, good reproducibility, temperature stability, wide dynamic range, and linear phase response, as well as special characteristics relevant to specific applications. Surface-acousticwave (SAW) devices are used for bandpass filtering [1], matched filtering for radar pulse compression [2], [3] or spread-spectrum signal processing [4], delay lines [5], and frequency control elements [3], [6]. Within the context of communication systems' applications, this paper reviews the state of the art for SAW components from high-performance fixed-tuned devices to tunable or programmable filters. Major technological advances discussed include unidirectional SAW filters [7] which eliminate bidirectionality loss and simultaneously suppress in-band spurious responses to achieve an insertion loss below 1 dB with a 0.04-dB peak-to-peak ripple. A novel surface-wave sub-system [8] which offers revolutionary signal processing functions through transform processing is also described.     

MIRAI architecture for heterogeneous network

One of the keywords that describe next-generation wireless communications is "seamless." As part of the e-Japan Plan promoted by the Japanese Government, the Multimedia Integrated Network by Radio Access Innovation project has as its goal the development of new technologies to enable seamless integration of various wireless access systems for practical use by 2005. This article describes a heterogeneous network architecture including a common tool, a common platform, and a common access. In particular, software-defined radio technologies are used to develop a multiservice user terminal to access different wireless networks. The common platform for various wireless networks is based on a wireless-supporting IPv6 network. A basic access network, separated from other wireless access networks, is used as a means for wireless system discovery, signaling, and paging. A proof-of-concept experimental demonstration system is available     

电力电子装置通讯电路的研究

研究了一种简化电力电子装置通讯电路的方案,将控制器和驱动电路之间多路并行信号转化成串行信号,并且在一台单相逆变器上进行了实验验证,使逆变器得到了很好的输出波形.     

Extended AMR-WB for high-quality audio on mobile devices

This article presents the architecture, performance, and application scenarios of the AMR-WB+ (extended AMR-WB) audio codec, which provides high quality at exceptionally low rates, and consistent quality over all audio types. This codec was recently selected by 3GPP and DVB to support low-bit-rate audio and audiovisual applications on mobile networks.     

Optimal policies for integrating heterogeneous services on isdn channels

A technique for the classification and evaluation of hierarchical access integration policies of ISDN channels is proposed. The essence of the basic control decisions based on several parameters of the servers and channel is captured in a single priority-based-layered model of multiple queues. We solve for the resulting delay of different policies and investigate the performance in one tractable limit of this model. Using our understanding of the problem parameters and their interaction, we propose a number of heuristic policies for the general model. The results of the general problem complexity investigations suggest the use of simulation models. Problem parameters considered are channel acceptable access delay value, number of servers needed, and flow duration time of a request. Preemptive and non-pre-emptive policies on queued traffic are considered. Performance considers average delay, delay variation and channel utilization. Simulation data on these policies suggest that policies that favour shorter services given better overall delay over a wide range of system parameters. Policies that favour longer and broadband services, on the other hand, show better quality and smaller delay variation.     

基于强化学习的异构网络垂直切换方法

网络切换技术不仅可以保证用户的网络连接,同时能够以较强的信号传输网络数据。网络切换技术的性能对网络服务质量(quality of service, QoS)的影响至关重要。然而,现有的切换算法多数存在严重的乒乓效应,这不仅造成网络资源的严重浪费,还会损害用户的QoS。为此,提出了一种基于强化学习的异构网络垂直切换方案,主要从触发切换、网络选择及判决切换等方面进行优化。在触发切换时将垂直切换考虑成必要切换和择优切换,通过Q-Learning（QL）算法在选择网络时优化垂直切换;然后以QoS为条件,在判决切换时加入驻留定时器,从多角度减少用户切换次数,降低乒乓效应对异构网络垂直切换的影响。仿真结果表明,基于强化学习的异构网络垂直切换方法可以在保证QoS的条件下有效减少用户切换网络的次数,短时间内频繁切换的情况也有所改善,降低了乒乓效应的影响。