Quality-of-service provisioning and efficient resource utilization in CDMA cellular communications

One of the major challenges in supporting multimedia services over Internet protocol (IP)-based code-division multiple-access (CDMA) wireless networks is the quality-of-service (QoS) provisioning with efficient resource utilization. Compared with the circuit-switched voice service in the second-generation CDMA systems (i.e., IS-95), heterogeneous multimedia applications in future IP-based CDMA networks require more complex QoS provisioning and more sophisticated management of the scarce radio resources. This paper provides an overview of the CDMA-related QoS provisioning techniques in the avenues of packet scheduling, power allocation, and network coordination, summarizes state-of-the-art research results, and identifies further research issues.     

OMAC: A new access control architecture for overlay multicast communications

Multicast communications concern the transfer of data among multiple users. Multicast communications can be provided at the network layer—an example is IP multicast—or at the application layer, also called overlay multicast. An important issue in multicast communications is to control how different users—senders, receivers, and delivery nodes—access the transmitted data as well as the network resources. Many researchers have proposed solutions addressing access control in IP multicast. However, little attention has been paid to overlay multicast. In this paper, we investigate the access control issues in overlay multicast and present OMAC: a new solution to address these issues. OMAC provides access control for senders, receivers, and delivery nodes in overlay multicast. The proposed architecture, which is based on symmetric key cryptosystem, centralizes the authentication process in one server whereas it distributes the authorization process among the delivery nodes. Moreover, delivery nodes are utilized as a buffer zone between end systems and the authentication server, making it less exposed to malicious end systems. To evaluate our work, we have used simulation to compare the performance of OMAC against previous solutions. Results of the simulation show that OMAC outperforms previous multicast access control schemes. Copyright © 2010 John Wiley & Sons, Ltd.     

Quality-of-service driven power and rate adaptation for multichannel communications over wireless links

We propose a quality-of-service (QoS) driven power and rate adaptation scheme for multichannel communications systems over wireless links. In particular, we use multichannel communications to model the conceptual architectures for either diversity or multiplexing systems, which play a fundamental role in physical-layer evolutions of mobile wireless networks. By integrating information theory with the concept of effective capacity, our proposed scheme aims at maximizing the multichannel-systems throughput subject to a given delay-QoS constraint. Under the framework of convex optimization, we develop the optimal adaptation algorithms. Our analyses show that when the QoS constraint becomes loose, the optimal power-control policy converges to the well-known water-filling scheme, where the Shannon (or ergodic) capacity can be achieved. On the other hand, when the QoS constraint gets stringent, the optimal policy converges to the scheme operating at a constant-rate (i.e., the zero-outage capacity), which, by using only a limited number of subchannels, approaches the Shannon capacity. This observation implies that the optimal effective capacity function decreases from the ergodic capacity to the zero-outage capacity as the QoS constraint becomes more stringent. Furthermore, unlike the single-channel communications, which have to trade off the throughput for QoS provisioning, the multichannel communications can achieve both high throughput and stringent QoS at the same.     

适于资源动态重组的测控设备体系结构

资源动态重组能够有效提高航天测控站的运行效益。介绍了我国传统测控设备的体系结构,从优化测控站总体设计的角度入手,设计了适应资源动态重组需求的测控设备的体系结构及其监控管理方式,提出了集中监控管理平台的概念,分析了其功能需求,讨论了需要重点关注的关键技术。所提出的体系结构可供该领域的设计、管理人员借鉴。     

Quality-of-service oriented medium access control for wireless ATMnetworks

The medium access control (MAC) protocol and the underlying traffic scheduling algorithm developed within project Magic WAND (Wireless ATM Network Demonstrator) are presented. Magic WAND is investigating wireless ATM technology for customer premises networks in the framework of the Advanced Communications Technologies and Services (ACTS) program funded by the European Union. The MAC protocol, known as MASCARA, is a hub-based, adaptive TDMA scheme which combines reservation- and contention-based access methods to provide multiple access efficiency and quality-of-service guarantees to wireless ATM terminal connections sharing a common radio channel. The traffic scheduling algorithm is delay-oriented to meet the requirements of the various traffic classes defined by the ATM architecture. The results of the simulation of a number of scenarios are presented to assess the performance of the proposed algorithm     

Cell hopping: a lightweight architecture for wireless communications

We propose a novel lightweight cellular wireless network architecture called cell hopping. Unlike traditional cellular networks, cell hopping has base stations interconnected by wireless inter-base station links, WIBLs. WIBLs support all routing and switching in cell hopping networks, obviating the need for costly core networks (or a costly switching infrastructure). Cell hopping utilizes an unlicensed frequency and presents a low-cost, rapidly deployable solution for mobile communications. We discuss various technical challenges that must be addressed before cell hopping can become a reality. In particular, we concentrate on location management. We propose an on-demand location management technique that completely eliminates the need for location databases and periodic updates by mobile stations. We provide a few variations of the location management scheme, and compare their performance through simulation.     

Quality-of-service control in GRAMS for ATM local area network

Gopher-style real-time ATM multimedia services (GRAMS) is a multimedia system designed for an ATM local area network with the server providing multimedia services to multiple users in real-time. The major goal of this system is to serve heterogeneous media requests so that every client served has satisfactory service while the network bandwidth and the host capacity are fully exploited. Therefore, a server that can determine the service rates and successfully multiplex media transmissions according to the quality-of-service (QoS) requirement of each request becomes the key component of this system. However, given the heterogeneity of QoS requirements from different types of media, it is usually very difficult to clearly specify and accurately measure the QoS for these media. Also, it is difficult to control the QoS in a distributed-multimedia environment. We propose in this paper a simple yet effective way to measure QoS in the GRAMS system. Based on the GRAMS system architecture, we use different kinds of starvation counters to measure system resource utilization and individual service quality. These counters are employed as major QoS parameters for the admission and rate-control algorithms in the GRAMS server that are under intensive evaluation and refinement. Experimental results are also presented, showing the feasibility of simultaneously providing tens of video and images transfer sessions using low-cost workstation technology. Bottlenecks for the video server are identified     

PETRA: performance enhancing transport architecture for Satellite communications

This paper presents a performance enhancing transport architecture for the satellite environment. This solution improves the network transport performance by overcoming the limits imposed by a transmission control protocol/Internet protocol (TCP/IP)-based stack suite, while maintaining the interfaces offered by it. This is an important issue since TCP/IP is widely used and most of the applications are based on it. The work starts from the state-of-the-art about the transport layer over satellite by distinguishing two alternative frameworks: the black box (BB) and the complete knowledge (CK) approaches. In the former, the network is considered as a "black box" and only modifications in the terminal tools are permitted. In the latter, the complete control of any network element is allowed so as a performance optimization procedure is possible. The proposed architecture [called Performance Enhancing Transport Architecture (PETRA)] is designed in all details using the second approach. PETRA uses network elements, called relay entities, to isolate the satellite portions in case of heterogeneous networks, while a transport layer protocol stack is used to optimize the transport of information over satellite links. A special satellite transport protocol, that is part of the transport layer protocol stack, is used over such links to perform error recovery. Simulation results show that the proposed framework significantly enhances throughput performance.     

Service needs and systems architecture in satellite communications

This paper examines the projected needs for satellite communications services of two fundamental types, point-to-point and broadcast, through the end of the 20th century, and relates the needs to systems architecture. This is done by considering factors which affect systems architecture, and by relating the service needs to available and developing technologies for satellite communications Systems. Some of these technologies originate from requirements on the different types of systems to share the communications channel capacity of the orbital are in allocated spectral bands. Consideration of the technologies applied to different systems architectures leads to the conclusion that developing capabilities are converging on elimination of the distinction between point-to-point and broadcast services at 12 GHz. This emerges in the discussion of systems architectures that completes the paper.     

Understanding the software communications architecture - [topics in radio communications]

The Software Communications Architecture is an open architecture developed by the U.S. Department of Defense to standardize the development of software-defined radio, improve communication systems interoperability, and reduce development and deployment costs. The SCA facilitates software reuse and technology insertion by abstracting radio applications from the supporting platform and defining a common operational environment across platforms. The SCA relies on commercial standards, classic software engineering principles, and software design patterns. While some SCA design choices are controversial and tightly tied to the specific needs for which it was developed, the basic design principles of software reuse and abstraction are sound and necessary if SDR is to achieve its full potential. Some of the techniques and concepts used in the SCA may be foreign to a communications engineer, and can result in confusion and long learning curves. The understanding of these concepts is of great relevance for communications engineers independent of any opinion about the SCA itself. This tutorial is aimed at educating communication engineers on these software engineering principles and describing how the SCA applies them to achieve its goals. We describe the different interfaces of the SCA that provide a framework for the implementation of SDR. The tutorial provides introductory material to understand the basic operation of the SCA as implemented in the Open-Source SCA Implementation::Embedded developed by Wireless @ Virginia Tech.     

A communications interface for systems application architecture

The requirements for program-to-program communication that prompted the creation of the communications interface for IBM's Systems Application Architecture (SAA), the considerations that went into the design of its function, and the basic concepts of the interface are discussed. An example of two programs using the Communications Interface is also included. The authors conclude that the evolving SAA Common Programming Interface and the Communications Interface within it provide a programming environment of languages and services for development of application programs that span systems     

UP2P: a peer-to-peer overlay architecture for ubiquitous communications and networking

Approaches to building an intelligent consumerfriendly network have evolved over time from centralized switch-based to router- and serverbased Internet architectures. We propose to drive this evolution further with a new highly scalable architecture that provides features to users derived from the computational and networking capabilities of very large populations of sophisticated terminals. This architecture relies on emerging peer-to-peer overlay technology. We describe a peer-to-peer overlay design that addresses requirements crucial for consumer applications, including overlay federation, peer heterogeneity, peer mobility, and service discovery. In addition, we introduce the concept of an overlay operator and describe the requirements for managed overlays. We have designed and implemented both a middleware and a peer-topeer platform that illustrates these concepts.     

UMTS-mobile communications beyond the year 2000: requirements,architecture and system options

To support the massive demand for mobile services third generation land mobile systems will be based on a new architecture concept and adaptive techniques. Moreover, these systems are expected to offer service quality comparable to that of fixed networks contemporary to their deployment. UMTS (universal mobile telecommunication system) is the developing pan-European concept for third generation mobile systems. The paper briefly overviews the requirements for and the emerging architecture of the UMTS as they appear at the transition between two RACE research phases and the beginning of dedicated standardisation activity in ETSI     

Broadband networks and services: architecture and control

Broadband networks to support a diverse combination of media and services present two interrelated challenges to the designers: how to devise the proper network architectures to efficiently deliver information, and how to realize the control and software infrastructure for end-to-end support of broadband applications. The new networks and applications that represent the future of interactive digital broadband are not driven by technology alone. We should recognize that the true foundation of the future information networking business involves the uses and benefits that it produces. The applications that are driving the information age are numerous, coming from the areas of entertainment, enterprise systems, telecommunications, education, health, etc. The use of client-server distributed object computing technologies is at the foundation of all the software systems that have been designed and implemented. There are still many Issues to he resolved in the application of this software technology, but it is clear that we must rely on distributed software designs to support the features of interactive broadband services. Concerns over the ability to manage complexity and scalability in these large distributed software systems are a common thread and an indication that the technology still needs to mature     

MaxNet: a congestion control architecture

On the Internet all the bottlenecked links of a source to destination path contribute to the aggregate congestion signal that controls the source rate. We introduce an architecture, MaxNet, in which only one link, the most severely bottlenecked link on the end-to-end path, controls the source rate. We prove that MaxNet results in MaxMin fairness for sources with general homogenous utility functions and the current architecture may not. MaxNet is distributed and requires no global information or per-flow state in the link.     

A voice over IP service architecture for integrated communications

The convergence of the traditional telecommunications world and the Internet has sparked the rapid evolution of Internet telephony, which has also introduced new implementation paradigms. As a result, the creation of a large variety of new and sophisticated communication services has become possible. This article addresses the problem of integrating IP-based telephony with the legacy circuit-switched intelligent network and proposes a novel service architecture for their seamless integration     

面向6G的卫星通信网络架构展望

分析和研究了未来6G卫星网络架构并提出了设想。首先介绍国内外星地融合的研究现状,结合6G网络的愿景、需求和6G网络架构的当前研究成果,总结了6G网络架构的技术特征;然后通过对人工智能（AI）在通信领域的研究和应用分析,以及AI在6G网络中关键作用的深入挖掘,提出了AI赋能的6G卫星通信网络总体架构、接入网架构及核心网架构的设想,同时提出了分阶段演进和分步骤实现的建设思路,最后对基于区块链的6G卫星通信网络韧性鲁棒机制进行了技术探讨。     

Ad hoc peer-to-peer network architecture for vehicle safety communications

This article addresses the design of an architecture for ad hoc peer-to-peer networking of neighboring vehicles to help achieve near-instantaneous communication for safety applications such as collision avoidance warnings. We propose a local peer group (LPG) architecture to organize neighboring vehicles that have frequently changing neighbors and have no inherent relationships with one another. We study two architectural alternatives for LPG in this article, and consider areas of improvement for ad hoc vehicle networking protocols to support safety communications including multihop throughput, connection setup time, and configuration.