异构无线接入网络中的通用链路层技术

如何实现异构环境下的多种无线接入网络融合以及多种无线接入技术之间的协同工作,是未来移动通信研究的主要内容。通用链路层(GLL)基于可重配置的链路层平台,完成不同无线接入技术的协同工作,从而实现了无缝和无损的垂直切换。通用链路层作为解决异构网络协同工作的一种新型技术,已经引起了相关研究领域的广泛关注。通用链路层可以划分为通用和特殊功能部分,并且在垂直切换中具有一套独特的执行过程。相比其他异构接入方案,通用链路层在切换执行的性能方面具有优势。     

异构无线融合网络中无线资源管理关键技术探讨

异构无线融合网络并不是多种无线接入技术的叠加,各个网络之间资源形式和管理机制各不相同,如何有效的管理无线资源,提升异构无线融合网络中无线资源的利用效率至关重要。基于以上,本文从异构无线融合网络概述入手,探讨了其无线资源管理的关键技术。     

异构云无线接入网络:原理、架构、技术和挑战

为了缓解密集异构无线网络节点间严重的干扰,提高节点间分布式协作处理增益,同时解决云无线接入网络控制信息传输复杂、无法和已有移动通信网络融合等问题,提出了异构云无线接入网络(H-CRAN)作为5G移动通信系统的接入网解决方案.所提H-CRAN的核心是将云无线接入网络与密集异构无线网络融合,将控制平面功能从云无线接入网络中抽离,通过已存的异构大功率节点实现控制平面功能和全网的无线覆盖,利用无线射频单元实现热点区域海量业务的大容量传输.介绍了H-CRAN的系统架构、关键技术组织和研究技术挑战等.     

基于集中式接入网架构的异构无线网络资源管理技术研究

未来无线通信网络将是一个多种无线接入方式共存的异构网络,如何实现异构网络在频谱、软硬件资源等方面的融合是一个亟需解决的问题.现有方案受限于不同网络独立部署的架构,无法真正实现异构网络资源的融合.针对该问题,提出了一种新型的基于集中式接入网架构的异构网络融合平台,可以在集中式资源池基础上进行异构网络间处理资源及无线资源的共享与统一管理.基于该平台,进一步阐述了异构网络资源管理的关键技术,包括基站资源虚拟化、处理资源按需分配、动态频谱共享、网络覆盖优化及性能分析验证方法等,为未来异构网络融合研究提供了一种可行的方案.     

下一代通信网络中基于策略机制的无线资源管理

下一代无线通信系统是一种异构的网络体系,集成多种无线接入技术（Radio Access Technology,RAT）的同时提供多种窄带和宽带多媒体业务。这样的网络环境需要先进的RRM方法来处理复杂多变的无线信道、网络资源的动态配置及保障不同特征业务的服务质量（QoS）,给无线资源管理（Radio Resource Management,RRM）带来了巨大的技术挑战。本文通过引入对网络进行策略控制的思想,提出了一种基于策略机制的通用方法,致力于解决下一代异构（heterogeneous）网络中的无线资源管理。文中着重讨论了基于策略机制的网络接入控制、切换,以及基于策略机制的QoS管理,给出了各功能模块的工作原理和通信过程的分析与设计。     

REALISM:一种面向未来异构无线网络演进的架构

未来无线通信系统将是各种无线接入技术和标准的融合,包容各自独立的网络,形成通用的平台并以简便的协议和信令操作,来实现异构网络融合是我们提出REALISM(REconfigurable:Adaption Layer for Integrated SysteM)的初衷,它通过在协议栈添加适配层(REAL:REconfigurable Adaption Layer),为由WLAN和UMTS组成的无线异构网络提供了融合的平台.文章重点关注了REALISM架构中的主要功能模块;然后描述了无线资源管理方面功能的实现,并以切换管理,例进行详细阐述.     

基于强化学习的异构无线网络资源管理算法

为了充分利用各种无线网络的资源,需要实现异构网络的融合,而异构网络的融合又面临接入控制与资源分配的问题。为此,提出一种基于强化学习的异构无线网络资源管理算法,该算法引入 D2D （device-to-device）通信模式,并可以根据终端不同的业务类型、终端移动性及网络负载条件等状态,选择合适的网络接入方式。同时,为降低存储需求,采用神经网络技术解决连续状态空间问题。仿真结果表明,该算法具有高效的在线学习能力,能够有效地提升网络的频谱效用,降低阻塞率,从而实现自主的无线资源管理。     

异构无线网络中支持端到端重配置的资源管理技术

可重配置的异构网络是无线领域研究的一个热点问题。通过有效的资源管理,重配置技术可以实现对异构环境的灵活适应和对异构无线资源的有效利用。作为一种适变能力很强的技术,重配置可以使异构无线系统从目前的隔离状态走向互通与协同,真正实现网络融合。本文描述了异构网络重配置技术的产生背景和基本概念,对重配置研究中的一系列资源管理关键技术,包括动态网络规划与管理、联合无线资源管理和先进频谱管理,进行了系统的总结。     

5G异构网络融合关键技术探究

在5G系统中,异构网络融合能够充分利用不同类型网络的优势,为用户提供多样化的接入手段、通信方式和网络服务.然而,不同类型的无线网络在融合过程中不可避免地会出现一些问题,如移动性管理、无线资源管理、服务质量等,这就给5G异构网络融合提出了新的挑战.基于此,本文围绕5G异构网络融合相关问题进行研究,探究改善5G异构网络融合...     

基于环境感知的异构无线Mesh网络体系结构及关键技术

文章以蜂窝网、无线局域网(WLAN)、Ad Hoc网络3种典型网络环境为组成元素,研究集环境感知、协作通信与网络融合于一体的异构无线格状网(Mesh)网络体系架构及其相关理论与技术问题.文章设计与实现的软硬件平台,不仅达到了各种异构网络的兼容和融合的目的,而且显著提高了无线通信网的容量和质量,可提供更经济和更便利的服务.     

Performance Analysis of an Improved Common Radio Resource Management Algorithm Based on Load Balance and Service Characteristics

In order to provide users with satisfactory quality of service and reduce service cost as much as possible, a key issue is how to manage radio resources reasonably and effectively in heterogeneous wireless networks (HWNs). Based on load balance and service characteristics, a common radio resource management (CRRM) algorithm for HWNs consisting of CDMA2000 and IEEE802.11 is proposed. The proposed algorithm selects appropriate access and handoff networks for new and handoff calls respectively, according to users’ mobility characteristic, location information, service type and network load. The performance of the proposed algorithm is analyzed based on a three-dimensional Markov chain model. Based on the HWNs model and handoff rate analysis, the model’s parameters are determined. In order to resolve the steady-state distribution of the three-dimensional Markov model, successive over-relaxation iteration method is adopted to work out steady state equations. According to the steady state probabilities of the Markov model, the closed formulas of HWNs performance metrics are given to evaluate the proposed CRRM algorithm, e.g. call blocking probability, handoff blocking probability, throughput, and service cost. For the purpose of illustrating advantages of the proposed algorithm, two other CRRM algorithms are employed for comparison. The simulation results show that the proposed algorithm can effectively reduce call blocking probability, and improve HWNs throughput.     

Wireless ATM networks: technology status and future directions

The concept of “wireless ATM” (WATM), first proposed in 1992, is now being actively considered as a potential framework for new-generation wireless communication networks capable of supporting integrated, quality-of service (QoS) based multimedia services. In this review paper, we outline the technological rationale for wireless ATM, present a system-level architecture, and discuss key design issues for both mobile ATM switching infrastructure and radio access subsystems. The WATM radio access layer issues covered in this paper include: spectrum allocation; spectrum etiquette; modem technology; and medium access/data link control (MAC/DLC) protocols. Mobile ATM aspects such as ATM signaling extensions for handoff control, location management, and mobile QoS control are discussed. A summary of current wireless/mobile ATM technology development and standardization status is given, including an outline of our WATMnet prototype. The paper concludes with a discussion of future directions for wireless ATM technology such as Internet protocol (IP) integration and mobile multimedia terminals/applications     

An AHP-based resource management scheme for CRRM in heterogeneous wireless networks

In a heterogeneous wireless environment, a variety of Radio Access Technologies (RATs) coexist. Since the number of RATs is anticipated to increase in the near future, it is desirable to have radio and network resources managed in a cooperative manner using the Common Radio Resource Management (CRRM) strategy. In order to make RAT-specific radio resources manageable in CRRM, this paper proposes the Analytical Hierarchy Process (AHP) based resource management scheme that efficiently allocates resources among heterogeneous wireless networks. The proposed AHP-based method is simple and flexible enough to be used in any network environment and can consider a multitude of decision factors. In addition, the proposed scheme uses a radio bandwidth model, which properly reflects transmission rates under given channel conditions, as the actual radio resources to be allocated. The model considers the AMC (Adaptive Modulation and Coding) scheme that is widely used in current broadband wireless access technologies, and thus, packet service characteristics, such as response time, can be analyzed. This is in contrast to existing work that focuses only on circuit service characteristics (e.g., blocking probability). The effectiveness and flexibility of the proposed method are demonstrated by implementing a number of existing methods and performing extensive simulation study on several different scenarios.     

A Unified Architecture and Key Techniques for Interworking between WiMAX and Beyond 3G/4G Systems

The trend of inter-connection among a multitude of different wireless access networks presents the great and bright potential business opportunities for communication operators. However, such a trend also creates a huge challenge for the network designers to manage the different radio access technologies in a cooperative mode. Therefore, this paper proposes two advanced functional architectures to support the functionalities of interworking between WiMAX and beyond 3G/4G systems, i.e., Radio Control Server (RCS) and Access Point (AP) based centralized architectures. Both control and user planes are defined in these two architectures. This paper further describes the corresponding key techniques for the interworking. These techniques can be partitioned into four categories: the key mechanisms in Generic Link Layer (GLL), the key mechanisms in Multi-Radio Resource Management (MRRM), the end-to-end Quality of Service (QoS) provision, and the heterogeneous paging. For the mechanisms in GLL, Multi-radio transmission diversity (MRTD) and Multi-Radio Multi-Hop networking (MRMH) schemes are researched. Meanwhile, Radio Access Technology (RAT) selection and load balancing schemes in aspect of MRRM are presented to improve the performance of interworking. In particular, the heterogeneous paging procedures for the convergence of WiMAX and beyond 3G/4G are proposed and evaluated, which can decrease the transmission load and save the power consumption.

Cognitive Wireless Communication Networks (Hossian, E. and Bhargava, V.; 2007) [Book Review]

?Cognitive radio? is emerging as a promising technology to cope with the spectrum scarcity as well as the spectrum underutilization problem in the next generation wireless communications systems. This book, Cognitive Wireless Communication Networks, edited by Ekram Hossain and Vijay Bhargava, puts together a rich set of research articles featuring recent advances in theory, design, and analysis of cognitive wireless communication networks. The book consists of 15 invited articles from distinguished researchers in this area, which cover a wide range of topics related to the cognitive radio technology. In particular, the topics covered in this book include fundamental challenges and issues in designing cognitive radio systems, information-theoretic analysis of cognitive radio systems, spectrum sensing and co-existence issues, adaptive physical layer protocols and link adaptation techniques for cognitive radio, orthogonal frequency division multiple access (OFDM) and ultra wide band (UWB)- based cognitive radio, different techniques for spectrum access by distributed cognitive radio, cognitive medium access control (MAC) protocols, decentralized learning-based dynamic spectrum access methods, and microeconomic models for spectrum management in cognitive radio.     

面向接入回传一体化的毫米波空地网络建模与分析

无人机(UAV)作为空中基站有望成为传统地面网络的有力补充,以提供灵活覆盖和容量增强的解决方案.然而,大多现有研究忽略空中基站的无线回传这一实际因素对网络性能和用户体验的影响.为此,考虑接入回传一体化的空地毫米波蜂窝网络场景,其中无人机提供热点流量传输服务,地面基站(TBS)提供无人机回传链路并且服务非热点区域用户,以...     

The common RRM approach to admission control for converged heterogeneous wireless networks

As the wireless environment becomes ever more populated and complex, individual networks offering single or restricted services will become ever more uncompetitive. Common radio resource management algorithms and strategies are used in heterogeneous or converged wireless networks to integrate multiple physical radio interfaces to support different levels of data rates, mobility, and traffic. Admission control in a common RRM environment is used to select the most appropriate wireless access based on service type, user preference, and network load. This is used to provide a balance between real-time and non-real-time traffic across the available access technologies. The development of common radio resource management strategies requires a suitable platform of coupled access networks and is the motivation behind the development of a converged wireless test platform. The tightly coupled platform supports voice and data call setup and delivery over UMTS and WLAN     

Advanced cellular Internet service (ACIS)

The public's desire for mobile communications and computing, as evidenced by the popularity of cellular phones and laptop computers combined with the explosive demand for Internet access suggest a very promising future for wireless data services. The key to realizing this potential is the development and deployment of high-performance radio systems. In this article we describe a basic service concept, advanced cellular Internet service (ACIS), and the technologies for achieving reliable high-speed transmission to wide-area mobile and portable cellular subscribers with very high spectrum efficiency. Such a wireless service, optimized to meet the needs of a client-server model for information retrieval and Web browsing, and combined with evolutionary enhancements in second-generation technologies, can provide an attractive option for third-generation systems. The radio link design combines OFDM with transmit and receive antenna diversity and Reed-Solomon coding to overcome the link budget and dispersive fading limitations of the cellular mobile radio environment. For access, a dynamic packet assignment algorithm is proposed which combines rapid interference measurements, priority ordering, and a staggered frame assignment schedule to provide spectrum efficiencies of two-to-four times existing approaches     

Dynamic spectrum access — concepts and future architectures

New trends and developments in radio technology are enhancing the future capabilities of devices to access electromagnetic spectrum using the full range of dimensions associated with the spectrum. This increased capability, together with current developments towards liberalisation of spectrum management regulations, are opening up opportunities to exploit an emerging paradigm in wireless communications and networking known as dynamic spectrum access (DSA). The key characteristic of DSA networks is their ability to exploit knowledge of their electromagnetic environment to adapt their operation and access to spectrum. Their key promise is that they open the possibility of highly efficient (re)use of spectrum. This paper introduces the main concepts behind DSA, reviews the proposed architectures for future DSA systems, and outlines some of the key research challenges associated with this new paradigm. Particular emphasis will be given to autonomous cognitive radio DSA.     

ORCA-MRT: an optimization-based approach for fair scheduling in multirate TDMA wireless networks

This paper presents an optimization-based approach to solve the wireless fair scheduling problem under a multirate time division multiple access (TDMA)-based medium access control (MAC) framework. By formulating the fair scheduling problem as an assignment problem, the authors propose the optimal radio channel allocation for multirate transmission (ORCA-MRT) algorithm for fair bandwidth allocation in wireless data networks that support MRT at the radio link level. The key feature of ORCA-MRT is that while allocating transmission rate to each flow fairly, it keeps the interaccess delay bounded under a certain limit. The authors investigate the performance of the proposed ORCA-MRT scheduler in comparison to another recently proposed multirate fair scheduling algorithm. They also propose two channel prediction models and perform extensive simulations to investigate the performance of ORCA-MRT for different system parameters such as channel state correlation, number of flows, etc.