检索结果-内蒙古大学图书馆

World Congress on Information and Communication Technologies

作者： Bing Li Yijun Guo Jianjun Hao Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications

ISBN: (纸本)9781467348065

In this paper, a new strategy was proposed that combining network coding with hierarchical modulation to solve the problem of asymmetry in two-user two-relay wireless networks. Hierarchical modulation was used to improve the performance of the low-priority stream and network coding was aimed at strengthening the reliability of the high-priority stream. Bit error rate (BER) was obtained to prove the correctness of the simulations. Compared with the conventional network coding scheme, it was obvious that the new strategy performed much better under additive white Gaussian noise (AWGN) channel. However under Rayleigh channel, its advantages played a dominant role in relatively lower signal-to-noise ratio (SNR) while its disadvantages leaded in higher SNR. In addition, simulations were performed to find a proper priority parameter of hierarchical modulation in accordance with the circumstances of the channels.

关键词： Hierarchical modulation (HM) network coding (NC) Asymmetric Two-user two-relay wireless network

来源：评论

学校读者我要写书评

暂无评论

A Distributed TDMA-based MAC Protocol for Ad Hoc networks with Directional Antennas

A Distributed TDMA-based MAC Protocol for Ad Hoc Networks wi...

引用

International Conference on Wireless Communications and Signal Processing

作者： Dong Hao Dan Pu Liu Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijng China

ISBN: (纸本)9781467358309

To improve the network capacity and reduce interference, directional antenna has been used in ad hoc networks for a long time. Due to the drawbacks of random access MAC protocols with directional antennas such as inevitable collisions, a distributed TDMA-based directional MAC protocol for ad hoc networks is proposed in this paper. It takes the advantage of real-time capability of TDMA and spatial reuse potential owing to directivity. By using the binary countdown mechanism instead of CSMA/CA, collision is completely avoided in contention stages. It offers priority services as well. The network saturation throughput and average delay are analyzed theoretically. Simulation results show that this new protocol performs better than DMAC protocol, as well as IEEE802.11 DCF and TDMA-based protocol with omnidirectional antennas.

关键词： Distributed Protocol networks

来源：评论

学校读者我要写书评

暂无评论

Joint Subchannel and Power Allocation in Interference-Limited OFDMA Femtocells with Heterogeneous QoS Guarantee

Joint Subchannel and Power Allocation in Interference-Limite...

引用

IEEE Global Communications Conference

作者： Haijun Zhang Wei Zheng Xiaoli Chu Xiangming Wen Meixia Tao A. Nallanathan David Lopez-Perez Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications The University of Sheffield Department of Electronic Engineering Shanghai Jiao Tong University King's College London London UK Bell Labs Alcatel-Lucent Dublin

ISBN: (纸本)9781467309202

In this paper, we consider the joint subchannel and power allocation problem in both the uplink and the downlink for two-tier networks comprising spectrum-sharing macrocells and femtocells. A joint subchannel and power allocation scheme for co-channel femtocells is proposed, aiming to maximize the capacity for delay-tolerant users subject to delay-sensitive users' quality of service and interference constraints imposed by macrocells. The joint subchannel and power allocation problem is modeled as an mixed integer programming problem, then transformed into a convex optimization problem by relaxing subchannel sharing, and finally solved by a dual decomposition approach. The effectiveness of the proposed approach is verified by simulations and compared with existing scheme.

关键词： power splitting subchannel Femtocells Interference constraints Joints Joints TWO-LAYER Quality of service macrocells up link Convex function

来源：评论

学校读者我要写书评

暂无评论

An Anti-blocking Scheme with Spatial Reuse for mm Wave Wireless networks

An Anti-blocking Scheme with Spatial Reuse for mm Wave Wirel...

引用

International Conference on Wireless Communications and Signal Processing

作者： Guangcan Yan Dan Pu Liu Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijng China 100876

ISBN: (纸本)9781467358309

In this paper, we investigate the two unique features of 60GHz mmWave links: inherent directivity and susceptible to blockage of human body. Due to the narrowed transmission beam of directional antenna, a moving human may cause link breakage and degradation. A fast relay selection and STDMA scheduling scheme is proposed to maintain the stability of the mmWave links and maximize the overall throughput in the presence of relay. We evaluate the anti-blocking scheme through MATLAB simulations, and compare it with existing scheduling algorithm without relay operation. The results show that the proposed scheme solves the problem of human blockage by the use of relay, and achieves high system throughput at the same time owing to the support for spatial reuse in scheduling time slots.

关键词： An Anti-blocking Scheme

来源：评论

学校读者我要写书评

暂无评论

Design of QSPM-MAC: Quasi-Synchronous Priority Multi-Channel MAC Access Protocol

Design of QSPM-MAC: Quasi-Synchronous Priority Multi-Channel...

引用

International Conference on Wireless Communications and Signal Processing

作者： Jingye Li Jing Gao Tao Luo Guangxin Yue Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing P.R.China.

ISBN: (纸本)9781467358309

Spectrum mobility poses a challenge to the medium access control (MAC) protocol design. This paper proposes a novel multi-channel MAC design, quasi-synchronous priority multi-channel (QSPM-MAC) protocol, for single transceiver device terminal of distributed cognitive radio networks (DCRN), presents a time frame structure consisting of spectrum sensing, channel access and data transmission, as well as the theoretical analysis framework. Depending on the different QoS requirements of different users, the proposed quasi-synchronous network access algorithm (QSNAA) euphemistically extends the contention time to increase the competitiveness of the cognitive users while solving the bidden terminal problem. The priority access policy based on super-slot commands the second position user (SPU) to abdicate to the primary position user (PPU), which reduces the collision probability. The results achieved from theoretical analysis and simulation show that the proposed protocol outperforms the existing protocol in many system performances.

关键词： Design QSPM-MAC: Quasi

来源：评论

学校读者我要写书评

暂无评论

Variability analysis for traffic distribution of typical network services

引用

Journal of China Universities of Posts and Telecommunications 2011年第SUPPL.2期18卷 46-53页

作者： Yang, Jie Li, He Beijing Key Laboratory of Network System Architecture and Convergence School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

network traffic characteristics analysis is an important prerequisite for network traffic engineering, traffic monitoring and controlling. Our analysis draws upon massive data obtained from a large Internet service provider (ISP) network. By analyzing traffic change rate features and the maximum rate of change, we extract and summarize the variation distribution characteristics of main services. Then we used Euclidean distance algorithm to research the similarity between the bi-direction change rates. Finally we used the change rate data for integral summation analysis. By these work, we present some interesting conclusions that characteristics of inbound traffic are more changeable than outbound, and the maximum value time intervals of typical services are fixed and similar, in addition the similarity between outbound and inbound change rate is not large, but the span among different services is large. These conclusions are useful information for providing insights of planning and managing networks. © 2011 The Journal of China Universities of Posts and Telecommunications.

关键词： Internet service providers

来源：评论

学校读者我要写书评

暂无评论

Internet quality abnormal analysis with k-means clustering

引用

Journal of China Universities of Posts and Telecommunications 2011年第SUPPL.2期18卷 94-100页

作者： Dong, Chao Lei, Zhen-Ming Liu, Feng Beijing Key Laboratory of Network System Architecture and Convergence School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

The anomaly detection using data mining techniques has widely aroused interests in recent years. This paper proposes a novel algorithm to do the Internet quality abnormal analysis. The algorithm is developed with k-means clustering method to analyze the real-time data of Internet quality acquired at the testbed of beijing University of Posts and Telecommunications (BUPT) for the first time. The main objective of this paper is to construct a statistical Internet quality abnormal analysis system capable of classifying the Internet quality data as normal or abnormal. For this purpose the algorithm constructs a model in training process. The data of Internet quality are compared with the model and data with distinct deviation from the model is marked as abnormal. The algorithm can split the abnormal data which are applied as a guide to further investigation of Internet anomaly root cause. And the result proved to be credible, which will be useful for the network administrators to manage the network. © 2011 The Journal of China Universities of Posts and Telecommunications.

关键词： Quality control

来源：评论

学校读者我要写书评

暂无评论

Measuring QoS in Gb interface of GPRS networks based on user session

引用

Journal of China Universities of Posts and Telecommunications 2011年第SUPPL.2期18卷 40-45页

作者： Wang, Huan Lei, Zhen-Ming Lin, Wen-Hui Shi, Ling Yang, Jie Beijing Key Laboratory of Network System Architecture and Convergence School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This article puts forward one novel Gb measuring and monitoring system (GBMMS) in Gb interface of general packet radio service (GPRS) networks based on user session. As is well known, the mobile internet is evolving rapidly to accommodate a myriad variety of emerging services with heterogeneous mobile terminals. Increasing packet traffic volumes put high pressure on GPRS networks especially in Um and Gb interface, which seriously hampers the capability and effectiveness of networks. GBMMS presented in this paper can precisely analyze quality of service (QoS) key performance indicators (KPIs) from the perspective of user perception. Furthermore, this article presents our recent findings based on the massive data collected with GBMMS placed in China's live GPRS networks. In particular, the study has scrutinized the Gb traffic in terms of attach procedure, from which meaningful and interesting insights on the current GPRS networks of China from the perspective of user session are derived. © 2011 The Journal of China Universities of Posts and Telecommunications.

关键词： Quality of service

来源：评论

学校读者我要写书评

暂无评论

Radio resource joint management scheme for the BBS and CBS mixed mode of BWM systems

Radio resource joint management scheme for the BBS and CBS m...

引用

2011 14th International Symposium on Wireless Personal Multimedia Communications: Communications, networking and Applications for the Internet of Things, WPMC'11

作者： Wang, Min Feng, Chunyan Zhang, Tiankui Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing China

ISBN: (纸本)9781457717864

To maximize the utilization of system resources and satisfy the requirements for quality of service (QoS), the radio resource joint management (RRJM) scheme is proposed for the broadcast base station (BBS) and cell base station (CBS) mixed mode of broadband wireless multimedia (BWM) system. The RRJM includes multiple utility factors-based packet scheduling (MUFPS) and broadcast cell seamless handover algorithm (BCSHA). The MUFPS takes into account QoS requirements, queue dynamics and channel state information to adapt packet priority with multiple utility factors. The BCSHA adopts seamless switch between BBS with point-to-multipoint (PTM) and CBS with point-to-point (PTP). The switch from BBS PTM to CBS PTP takes into account handover delay for accurate execution. The switch from CBS PTP to BBS PTM avoids ping-pong effect by considering the handover threshold predefined with QoS. Simulation results show that the proposed scheme improves system performance in terms of throughput and delay. © 2011 National Institute of Inform.

关键词： Base stations

来源：评论

学校读者我要写书评

暂无评论

A simulated annealing algorithm for the transmission mode selection of multicast services in LTE networks

A simulated annealing algorithm for the transmission mode se...

引用

2011 14th International Symposium on Wireless Personal Multimedia Communications: Communications, networking and Applications for the Internet of Things, WPMC'11

作者： Wang, Min Feng, Chunyan Zhang, Tiankui Beijing Key Laboratory of Network System Architecture and Convergence Beijing University of Posts and Telecommunications Beijing China

ISBN: (纸本)9781457717864

A simulated annealing (SA) algorithm is proposed for the transmission mode selection of multicast services in LTE networks. The multicast services can be transmitted by single frequency network (SFN) mode and point-to-multipoint (PTM) mode, and the unicast services are delivered with point-to-point (PTP) mode. To avoid the network congestion in LTE networks with the multicast and unicast mixed services, the demanded resources of the maximum load cell is minimized by selecting the optimal mode between SFN and PTM for multicast services. The transmission mode selection problem is solved by means of SA heuristics. Simulation results show that the proposed SA algorithm achieves less demanded resources of the maximum load cell than SFN mode for all the multicast services. © 2011 National Institute of Inform.

关键词： Simulated annealing

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：