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     

Antenna systems for broadband wireless access

Broadband wireless access along with evolving mobile Internet and multimedia services are driving the surge of research and development activities for future wireless communication systems. We provide an overview of antenna systems for broadband wireless communications and introduce some of the important issues surrounding them. The approach we use is to first provide a general framework of how antenna systems may be utilized in wireless communication systems and then describe the antenna systems themselves. In particular, we consider antenna systems for the base station, mobile station, and then finally multiple-input multiple-output antenna systems where antenna systems are utilized at both the base and mobile stations     

The future generations of mobile communications based on broadband access technologies

The forthcoming mobile communication systems are expected to provide a wide variety of services, from high-quality voice to high-definition videos, through high data rate wireless channels anywhere in the world. The high data rate requires broad frequency bands, and sufficient broadband can be achieved in higher frequency bands such as microwave, Ka-band, and millimeter-wave. Broadband wireless channels have to be connected to broadband fixed networks such as the Internet and local area networks. The future-generation systems will include not only cellular phones, but also many new types of communication systems such as broadband wireless access systems, millimeter-wave LANs, intelligent transport systems, and high altitude stratospheric platform station systems. Key to the future generations of mobile communications are multimedia communications, wireless access to broadband fixed networks, and seamless roaming among different systems. This article discusses future-generation mobile communication systems.     

Beyond 3G: wideband wireless data access based on OFDM and dynamicpacket assignment

The rapid growth of wireless voice subscribers, the growth of the Internet, and the increasing use of portable computing devices suggest that wireless Internet access will rise rapidly over the next few years. Rapid progress in digital and RF technology is making possible highly compact and integrated terminal devices, and the introduction of sophisticated wireless data software is making wireless Internet access more user-friendly and providing more value. Transmission rates are currently only about 10 kb/s for large cell systems. Third-generation wireless access such as WCDMA and the evolution of second-generation systems such as TDMA IS-136+, EDGE, and CDMA IS-95 will provide nominal bit rates of 50-384 kb/s in macrocellular systems. This article discusses packet data transmission rates of 2-5 Mb/s in macrocellular environments and up to 10 Mb/s in microcellular and indoor environments as a complementary service to evolving second- and third-generation wireless systems. Dynamic packet assignment for high-efficiency resource management and packet admission; OFDM at the physical layer with interference suppression, space-time coding, and frequency diversity; as well as smart antennas to obtain good power and spectral efficiency are discussed in this proposal. Flexible allocation of both large and small resources also permits provisioning of services for different delay and throughput requirements     

Mobile and Multicast IP Services in PACS: System Architecture, Prototype, and Performance

Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services.     

Polling-based media access protocols for use with smart adaptivearray antennas

Use of an adaptive antenna array or a space-time processor at each base station of a wireless network can substantially abate the effects of multipath fading and co-channel interference. Among the expected benefits are higher data rates, greater frequency reuse factors, and overall higher capacity systems as needed to enable wireless multimedia services. Media access control (MAC) protocols which facilitate the deployment of such a processor have been previously proposed and studied. These MAC protocols invoke the delivery of a pilot tone from each packet access unit in the network as needed, so that the array antenna at the associated base station may rapidly adjust its weighting coefficients, or its per branch equalization coefficients, thereby ensuring subsequent reliable communication between the access unit and the base station. This paper considers two modifications to these earlier protocols, both based upon the notion of piggybacking information requests on to the actual information messages and both intended to improve utilization efficiency and mean delay performance. Results show that a maximum link utilization efficiency of 97% is readily achieved with either modification, and that this maximum utilization efficiency is independent of the number of remote users in the network. Note that the utilization efficiency refers to the throughput at maximum loading, i.e., when the remotes always have queued requests. The modifications also help in achieving a considerable reduction in the average delay in low-load regimes: for typical system parameters, the average delay at low load is only about 10% of that produced by the original schemes     

Wireless loops: What are they?

Several loop applications of wireless technology are aimed at reducing the cost of deploying communications services ranging from telephone to wideband video. In these applications, wireless links replace a portion of a wireline loop from a central location (a central office or cable headend) to a subscriber. The replacement of labor-intensive wireline technology by complex mass-produced integrated electronics in wireless transceivers is projected to reduce the overall cost of the resulting loop. These wireless loop applications attempt to provide existing communications services or small modifications to existing communications services. A different interpretation of a wireless loop makes use of low-power digital radio technology to provide the last thousand feet or so of a loop. Low-power low-complexity wireless loop technology in small base units can be integrated with network intelligence to provide the fixed-infrastructure network needed to support economical personal communications services (PCS) to small, lightweight, low-power personal voice and/or data communicators. Low-complexity communicators can provide many hours of “talk time” or data transmission time and perhaps several days of standby time from small batteries (≤ 1.5 oz). Because this application of wireless loop technology can reduce the inherent costs in several parts of a wireline loop, it has the potential to provide convenient widespread PCS at less costs than providing telephone services over conventional wireline loops. This low-power wireless loop application does not fit into any existing communications system paradigm. Wireless technology with tetherless access and wide-ranging mobility, e.g., the personal access communications system (PACS), does not fit the accumulated wisdom of the wireline telephony paradigm. It also does not fit the paradigm of existing cellular radio that has sparsely distributed expensive cell sites, and it is not targeted at fixed video services as is wireless cable. Because a significant change in thinking is required in addressing this new low-power low-complexity widespread wireless loop paradigm, its large economic advantages and service benefits have not yet been embraced by many of the existing communications providers, who appear to be more comfortable pursuing the better-known paradigms of video using wireless cable, or of cellular radio in the guise of high-tier PCS, or in the guise of rapid economical deployment of telephone services in developing nations. This paper discusses the inherent economic advantages and service benefits of low-power low-complexity wireless loop technology integrated with network intelligence aimed at providing economical low-tier PCS to everyone.     

Compact multidimensional broadband wireless: the convergence of wireless mobile and access

Broadband wireless communications have gained increased interest during the last few years. This has been fuelled by a large demand on high-frequency utilization as well as a large number of users requiring simultaneous high-data-rate access for the applications of wireless mobile Internet and e-commerce. The convergence of wireless mobile and access will be the next storm in wireless communications, which will use a new network architecture to deliver broadband services in a more generic configuration to wireless customers, and support value-added services and emerging interactive multimedia communications. Large bandwidth, guaranteed quality of service, and ease of deployment coupled with the great advancements in semiconductor technologies make this converged wireless system a very attractive solution for broadband service delivery.     

Seamless Support for Mobile Internet Protocol Based Cellular Environments

Cellular is the inevitable architecture for the Personal Communication Service system (PCS) in the coming future. Access to the Internet via cellular networks is expected to become an essential portion of future wireless service offerings. Providing seamless support for IP based packet switched services has become an important issue.The Internet Engineering Task Force's (IETF's) mobile IP protocol offers a standard solution for wide-area mobility at the IP layer. However, Mobile IP does not solve all of the problems involved in providing mobile Internet access to cellular users, especially during handoff period. Thus, IPv6 might be a good candidate to solve this problem.IPv6 is a new version of the Internet Protocol that was standardized by the IETF. It supports mobility and is presently being standardized by the IETF Mobile IP Working Group. At the same time, cellular is an inevitable architecture for the Personal Communication Service system (PCS).This paper introduces the current cellular support based on the Mobile Internet Protocol version 6. We will point out the short-falls using Mobile IP and try to emphasize protocols especially for mobile management schemes that can optimize a high speed mobile station moving among small wireless cells. A comparison between those schemes and future work will be presented.     

Integrated circuits for channel coding in 3G cellular mobile wireless systems

Error control coding is a key element of any digital wireless communication system, minimizing the effects of noise and interference on the transmitted signal at the physical layer. In 3G mobile cellular wireless systems, error control coding must accommodate both voice and data users, whose requirements vary considerably in terms of latency, throughput, and the impact of errors on the user application. At the base station, dedicated hardware or readily reconfigurable components are needed to address the concurrent coding and decoding demands of a large number of users with different call parameters. In contrast, the encoder and decoder at the user equipment (UE) are dedicated to a single call setup which changes infrequently. In designing encoder and decoder solutions for 3G wireless systems, not only are the performance issues important, but also the costs. Cellular wireless infrastructure manufacturers need to reduce costs, maximize system reuse, and increase flexibility in order to compete in the market. Furthermore, future-proofing a network is a primary concern due to the high cost of deployment. For the UE, power consumption (battery life) and size are key constraints in addition to manufacturing costs. This article considers the 3G decoder design problem and, using case studies, describes two 3G decoder solutions using ASICs. The first device is targeted for base station deployment and is based on a unified architecture for convolutional and turbo decoding. The second device is a dedicated high-speed radix-4 logMAP turbo decoder targeted for UE, motivated by the requirements for high-speed downlink packet access. Both devices have been fabricated in 0.18 /spl mu/m CMOS technology, and while optimized for either base station or UE, may be used in both applications.     

Profit-Based Routing for Multihop Coverage Extension in Wireless Networks

In future wireless systems, the coverage of a base station will decrease due to the characteristics of the channel at high-frequency bands. To expand the service coverage, a hybrid network that combines an ad hoc network with a cellular (or wireless LAN) network, appears to have great potential. In such systems, some mobile users outside the service area can access the network with the aid of other intermediate mobiles. However, this method incurs energy consumption in routing users, which could be a serious obstacle for wide-spread deployment of multihop wireless networks. Therefore we consider a revenue-cost model and propose a profit-based routing strategy that encourages routing users to actively participate in the relaying service because they are compensated for their energy consumption cost. Our strategy enables each mobile node to find an appropriate multihop path to a base station (or access point) that satisfies the interests of the service provider and the users. Numerical results show that our model successfully expands the network coverage area while ensuring the profit of each system involved.     

High speed wireless data access based on combining EDGE withwideband OFDM

The success of cellular services, combined with the increased presence of laptop computers and the rapid growth in the number of Internet users, indicates that wireless data should have a very bright future. Nevertheless, today the number of wireless data subscribers is small, with the most formidable obstacle to user acceptance being the performance limitations of existing services and products. This article discusses combining enhanced data rates for CSM evolution (EDGE) with wideband orthogonal frequency-division multiplexing in an asymmetrical solution to provide high-speed data rates, with wide-area coverage and good quality, for wireless packet data services     

A flexible overlay architecture for mobile IPv6 multicast

The Internet has evolved from a wired infrastructure to a hybrid of wired and wireless domains. As network access is now provided with much of the last mile being a wireless mobile environment, delivering rich multimedia to users is now a necessity. However, despite the advent of new technology and standards such as Mobile Internet protocol version 6 (MIPv6), there is still an important dilemma over the choice of systems that either achieve high levels of performance or offer easier deployment. The very deployment of IPv6 is delayed for this reason; network providers continue to use legacy systems. The goal of this paper then is to offer insight into this issue by examining the case of data streaming to MIPv6 users through the use of multicast. By specifically considering the debate over network and application layer multicast, we examine a spectrum of possible alternatives and evaluate the potential of enhancing the functionality of access routers. The result is an overlay architecture that can bring the desired balance between deployment complexity and performance.     

CDMA2000 1X无线上网数据业务的特点

主要介绍了CDMA2000 1X无线上网数据业务的特点。首先介绍了基于移动IP技术的CDMA2000 1X数据业务的通信协议栈,包括移动台与基站接口之间分层协议结构,接着详细分析了物理层的特点、链路接入控制子层（LAC）的RLP协议以及传输层的PPP协议;然后给出CDMA2000 1X无线上网过程中的状态转化,分析无线上网过程中基本信道和补充信道的建立和释放;最后对无线上网过程中的相关信令进行了分析。     

Enhancing IP service provision over heterogeneous wirelessnetworks: a path toward 4G

Second-generation mobile radio systems have been deployed successfully worldwide and have evolved to higher data rates and services. Third-generation mobile radio systems are currently starting to be developed in different regions of the world. Today, the open question is how the third-generation systems will evolve. It is very likely that fourth-generation systems will not be a single standardized air interface, but a set of different technologies and standards. In particular, wireless LAN/wireless PAN type systems are designed for high/medium-data-rate access, low range, and, in general, low mobility. They are applicable to corporate networks and public access as a complement to cellular mobile radio systems for hot spot applications such as airports, hotels, and campuses. In this specific WLAN/WPAN framework and to guarantee an agreed QoS provision over such infrastructures, we propose a solution based on the wireless adaptation layer approach. In particular, aspects related to wireless link impairments and traffic requirements are approached by the implementation of configurable, modular software that is adapted to the specific conditions and needs of the particular wireless infrastructures     

An evolved cellular system architecture incorporating relay stations - [WiMAX update]

Shrinking cell sizes, primarily a result of keeping up with the increasing demand for higher data rates, are stretching thin the notion of our traditional cellular system architecture. More and more base stations are serving smaller and smaller areas (cells) which in effect is driving up deployment costs. The option of deploying relay stations is increasingly beginning to look like a solution to the problem of providing a cost-effective way to extend the coverage and capacity in a cellular network. A relay station can be used to extend the point-to-multipoint link between the base station and mobile stations. Relay stations connect to the base stations without wires and are expected to be deployed to cover smaller geographic areas. Primarily the deployment costs but also the equipment costs are expected to be substantially lower than those of base stations. In this article we first introduce the relay station and discuss the place it is likely to carve out for itself in the traditional cellular architecture. We highlight the important economic and performance benefits relay stations could potentially offer, and outline a few scenarios where relays are likely to be deployed in the beginning. The multihop relay standard developed by the IEEE 802.16 working group is then used as a basis to provide an overview of the relay-enhanced cellular architecture and the key choices that can be made in developing relay support within a cellular system ? a precursor to what can be expected in later releases of the Mobile WiMAX system. Finally, we discuss some future directions in the development of relay systems.     

无线宽带接入技术WiMAX802．16e

随着无线网络技术和互联网络业务的不断发展,宽带接入移动服务逐渐成为宽带无线接入发展的趋势。阐述了宽带无线接入标准802.16e,分析其在无线数据网络中地位和主要的关键技术,与现存的无线局域网和3G网络进行比较,指出其发展的方向。     

Hotspot wireless LANs to enhance the performance of 3G and beyond cellular networks

At present, WLANs supporting broadband multimedia communications are being developed and deployed around the world. Standards include HIPERLAN/2 defined by ETSI BRAN and the 802.11 family defined by the IEEE. These systems provide channel adaptive data rates up to 54 Mb/s (in a 20 MHz channel spacing) over short ranges up to 200 m. The HIPERLAN/2 standard also specifies a flexible radio access network that can be used with a variety of core networks, including UMTS. It is likely that WLANs will become an important complementary technology to 3G cellular systems and will typically be used to provide hotspot coverage. In this article the complementary use of WLANs in conjunction with UMTS is presented. In order to quantify the capacity enhancement and benefits of cellular/hotspot interworking we have combined novel ray tracing, software-simulated physical layer performance results, and optimal base station deployment analysis. The study focuses on an example deployment using key lamppost mounted WLAN access points to increase the performance (in terms of capacity) of a cellular network.     

The role of Internet technology in future mobile data systems

Mobile telephony and the Internet are the fastest growing businesses in the telecommunications market. This is why most operators and service providers are looking after the development of new services in both sectors, and newcomers are expected to enter the arena. The mobile operators foresee an increasing share of their revenues coming from new data services, while Internet service providers are attracted to wireless technology and mobility services both to reduce costs within the last-mile segment and to enrich their market share, providing ubiquitous access to the Internet and corporate intranets. In this scenario several wireless overlay networks will coexist, and their interworking will be a challenging objective. The employment of Internet technology, with its novel mobility and security extensions, seems to be the most attractive option for achieving that goal. In addition, the migration to a full IP network architecture, even within each specific wireless domain, will be another promising opportunity, already under consideration within several technical and standardization bodies. The envisioned role of Internet technology makes it worthwhile to undertake significant research efforts on the development of innovative IP-based mobile data systems, and opens promising opportunities for both telcos and Internet service providers.     

Wideband DS-CDMA for next-generation mobile communications systems

Wideband wireless access based on direct sequence code division multiple access aimed at third-generation mobile communications systems is reviewed. W-CDMA is designed to flexibly offer wideband services which cannot be provided by present cellular systems, with various data rates as high as 2 Mb/s. The important concept of W-CDMA is the introduction of intercell asynchronous operation and the pilot channel associated with individual data channels. Intercell asynchronous operation facilitates continuous system deployment from outdoors to indoors. Other technical features of W-CDMA include fast cell search under intercell asynchronous operation, fast transmit power control, coherent spreading code tracking, a coherent RAKE receiver, orthogonal multispreading factor forward link, and variable-rate transmission with blind rate detection. The introduction of the data-channel-associated pilot channel allows W-CDMA to support interference cancellation and adaptive antenna array techniques that can significantly increase the link capacity and coverage. This article presents the radio link performance evaluated by computer simulation. Field experiment radio link performance results are also presented