Showing papers in "IEEE Personal Communications in 2001"
TL;DR: The relationship of this new field to its predecessors is examined: distributed systems and mobile computing, and four new research thrusts are identified: effective use of smart spaces, invisibility, localized scalability, and masking uneven conditioning.
Abstract: This article discusses the challenges in computer systems research posed by the emerging field of pervasive computing. It first examines the relationship of this new field to its predecessors: distributed systems and mobile computing. It then identifies four new research thrusts: effective use of smart spaces, invisibility, localized scalability, and masking uneven conditioning. Next, it sketches a couple of hypothetical pervasive computing scenarios, and uses them to identify key capabilities missing from today's systems. The article closes with a discussion of the research necessary to develop these capabilities.
2,584 citations
TL;DR: It is demonstrated that even though DSR and AODV share similar on-demand behavior, the differences in the protocol mechanics can lead to significant performance differentials.
Abstract: Ad hoc networks are characterized by multihop wireless connectivity, frequently changing network topology and the need for efficient dynamic routing protocols. We compare the performance of two prominent on-demand routing protocols for mobile ad hoc networks: dynamic source routing (DSR) and ad hoc on-demand distance vector routing (AODV). A detailed simulation model with MAC and physical layer models is used to study interlayer interactions and their performance implications. We demonstrate that even though DSR and AODV share similar on-demand behavior, the differences in the protocol mechanics can lead to significant performance differentials. The performance differentials are analyzed using varying network load, mobility, and network size. Based on the observations, we make recommendations about how the performance of either protocol can be improved.
1,470 citations
TL;DR: A sensor information networking architecture, called SINA, that facilitates querying, monitoring, and tasking of sensor networks and provides mechanisms to create associations and coordinate activities among sensor nodes.
Abstract: This article introduces a sensor information networking architecture, called SINA, that facilitates querying, monitoring, and tasking of sensor networks. SINA serves the role of middleware that abstracts a network of sensor nodes as a collection of massively distributed objects. SINA's execution environment provides a set of configuration and communication primitives that enable scalable and energy-efficient organization of and interactions among sensor objects. On top the execution environment is a programmable substrate that provides mechanisms to create associations and coordinate activities among sensor nodes. Users then access information within a sensor network using declarative queries, or perform tasks using programming script.
612 citations
TL;DR: In this paper, the authors present an algorithm for routing in wireless ad hoc networks using information about the geographical location of the nodes, where each node knows its geographical position and the position of the node to which it wants to send a packet.
Abstract: We present an algorithm for routing in wireless ad hoc networks using information about the geographical location of the nodes. We assume each node knows its geographical position and the position of the node to which it wants to send a packet. Initially, the nodes know only their neighbors. But over time they discover other nodes in the network. The routing table at a node S is a list , where p/sub i/ is a geographical position and S/sub i/ is a neighbor of node S. When node S receives a packet for a node D at position pos(D), it finds the p/sub i/ in its routing table which is closest to pos(D) and forwards the packet to the neighbor S/sub i/. We prove the correctness of the algorithm and show that our algorithm naturally aggregates the nodes so that the routing tables remain small. We show that the mean routing table size is O(L~logn), where L~ is the average number of hops between two nodes and n is the number of nodes in the network. We also present methods for taking positional errors, node failures and mobility into account. We justify the results through simulation.
397 citations
TL;DR: Simulation experiments show that in the event of route failures, as the route reestablishment time increases, the use of feedback provides significant improvements in performance.
Abstract: Ad hoc networks are completely wireless networks of mobile hosts, in which the topology rapidly changes due to the movement of mobile hosts. This frequent topology change may lead to sudden packet losses and delays. Transport protocols like TCP, which have been designed for reliable fixed networks, misinterpret this packet loss as congestion and invoke congestion control, leading to unnecessary retransmissions and loss of throughput. To overcome this problem, a feedback scheme is proposed so that the source can distinguish between a route failure and network congestion. When a route is disrupted, the source is sent a route failure notification packet, allowing it to invalidate its timers and stop sending packets. When the route is reestablished, the source is informed through a route reestablishment notification packet, upon which it resumes packet transmissions. Simulation experiments show that in the event of route failures, as the route reestablishment time increases, the use of feedback provides significant improvements in performance.
293 citations
TL;DR: The article suggests a method to build context-aware devices and starts from situation analysis, offers a structured way for selection of sensors, and finally suggests steps to determine recognition and abstraction methods.
Abstract: In this article smart appliances are characterized as devices that are attentive to their environment. We introduce a terminology for situation, sensor data, context, and context-aware applications because it is important to gain a thorough understanding of these concepts to successfully build such artifacts. In the article the relation between a real-world situation and the data read by sensors is discussed; furthermore, an analysis of available sensing technology is given. Then we introduce an architecture that supports the transformation from sensor data to cues then to contexts as a foundation to make context-aware applications. The article suggests a method to build context-aware devices; the method starts from situation analysis, offers a structured way for selection of sensors, and finally suggests steps to determine recognition and abstraction methods. In the final part of the article the question of how this influences the applications is raised and the areas of user interfaces, communication, and proactive application scheduling are identified. We conclude with the description of a case study where a mobile phone was made aware of its environment using different sensors. The profile settings of the phone (ringing mode etc.) are automatically selected according to the real world situation the phone is used in.
292 citations
TL;DR: The objective of this article is to address new concepts in the GSM system, dealing with both standardized features as well as theoretically and technologically feasible improvements, which contribute to evolutionary changes in general.
Abstract: The latest developments and experimentation in mobile ad hoc networks show that MANETs will be an alternative candidate in many private and public multimedia networks. Current interest in MANET systems has grown considerably because they can rapidly and economically extend the boundaries of any terrestrial network; integrating MANET and GSM offers a great number of benefits (e.g., increasing capacity, improving coverage) at the cost of increasing the complexity of the mobile terminal and its battery consumption. The objective of this article is to address new concepts in the GSM system, dealing with both standardized features as well as theoretically and technologically feasible improvements, which contribute to evolutionary changes in general. Dynamic evolution of GSM presents a platform for Universal Mobile Telecommunication System introduction and major trends in GSM development are addressed, in particular progress towards a generic platform to accommodate relaying capability in GSM cellular networks. A GSM simulation tool has been constructed for quantifying the integrated system characteristics.
284 citations
TL;DR: The evolution of WCDMA toward high-speed downlink packet access, aiming for peak rates in the order of 8-10 Mb/s, is described as an example of air-interface evolution.
Abstract: Starting with today's 3G standards, future-generation wireless networks are discussed. Two complementing major trends are identified: seamless roaming between different air interfaces, leading to the always best connected concept, and the continuous development of the current third-generation standards. The evolution of WCDMA toward high-speed downlink packet access. aiming for peak rates in the order of 8-10 Mb/s, is described as an example of air-interface evolution. Fourth-generation technologies such as ad hoc networking and multihop networks, still at the research level, are discussed and their impact on wireless communication systems addressed.
252 citations
IBM1
TL;DR: The DEAPspace group at IBM Research, Zurich Lab is developing a system in which services can be shared between proximate devices, and a new service discovery algorithm is presented that improves the responsiveness of devices to changes in their environments.
Abstract: The DEAPspace group at IBM Research, Zurich Lab is developing a system in which services can be shared between proximate devices. The target environment is single-hop short-range wireless systems, and the solution must offer prompt responsiveness for transient devices. In this article, the service discovery algorithm is presented. Through this new algorithm, a computing device can detect the presence of neighboring devices, share configuration and service information with those devices, and also notice when devices become unavailable. Targeted for wireless ad hoc single-hop networks, this solution improves the responsiveness of devices to changes in their environments. The effectiveness of this algorithm is demonstrated through comparison with others that achieve similar goals, considering the responsiveness to changes in the local environment, power consumption, and bandwidth requirement of devices.
226 citations
TL;DR: This article describes the experiences building a multihop wireless ad hoc network of eight nodes driving around a 700 m by 300 m site that runs the dynamic source routing protocol and interfaces seamlessly with existing Internet infrastructure and the Mobile IP protocol.
Abstract: This article describes our experiences building a multihop wireless ad hoc network of eight nodes driving around a 700 m by 300 m site. Each node runs the dynamic source routing protocol and interfaces seamlessly with existing Internet infrastructure and the Mobile IP protocol. We present quantitative results from data collected during runs of our testbed under a composite workload including voice, bulk data, and real-time data. Based on careful analysis of our data, we highlight radio propagation issues that network protocols will need to address in the future.
213 citations
TL;DR: The scenarios, as well as the ensuing research into various wireless related topics, point to a vision of fourth-generation systems where "low-hierarchy" user-deployed infrastructures are the prime candidate.
Abstract: A "fourth generation" of wireless systems, likely to appear after the successful deployment of the current third-generation systems, is frequently debated these days. This article presents some of the results of the Fourth Generation Wireless project (4GW) of the Personal Computing and Communications program (PCC), the major Swedish academic research effort on future communications systems, launched in late 1997. In the 4GW project, scenarios have been used as tools for formulating relevant research topics related to future wireless systems. By working with scenarios the project group has been able to challenge some of the assumptions commonly made in the field of wireless research. Since the project group is multidisciplinary, the work has also helped the members of the project group to understand the differences between the research traditions to which they belong. The scenarios, as well as the ensuing research into various wireless related topics, point to a vision of fourth-generation systems where "low-hierarchy" user-deployed infrastructures are the prime candidate. Fourth-generation systems will offer short- to moderate-range communications with very high data rates (>100 Mb/s). They are likely to employ array signal processing and ad hoc operation to provide the required coverage. A key aspect of their design will be the fact that they will be deployed in environments where large-scale wireless, and wired, infrastructures are already in operation.
TL;DR: This article describes a autoconfiguration solution based on the dynamic configuration and distribution protocol (DCDP) and presents an initial version of the basic user registration protocol (BURP), which provides secure client-network registration and interfaces to AAA protocols such as Diameter.
Abstract: In the vision of pervasive computing, users will exchange information and control their environments from anywhere using various wireline/wireless networks and computing devices. We believe that current protocols, such as DHCP, PPP, and Mobile IP, must be enhanced to support pervasive network access. In particular, this article identifies three fundamental functions: autoconfiguration, registration, and mobility management, that need such enhancements. Realizing that the IP autoconfiguration capabilities must be extended to configure routers and large dynamic networks, we first describe our autoconfiguration solution based on the dynamic configuration and distribution protocol (DCDP). Second, we discuss why providing user-specific services over a common infrastructure needs a uniform registration protocol, independent of the mobility and configuration mechanisms. We present an initial version of the basic user registration protocol (BURP), which provides secure client-network registration and interfaces to AAA protocols such as Diameter. Finally, we discuss the dynamic mobility agent (DMA) architecture, which provides a hierarchical and scalable mobility management framework. The DMA approach allows individual users to customize their own mobility-related features, such as paging, fast handoffs, and QoS support, over a common access infrastructure and to select multiple global binding protocols as appropriate.
TL;DR: This article gives a high-level view of the component architecture of the gateway and its adaptation layer to the wireless infrastructure and proposes a communication gateway architecture proposed as an essential building block in future automobile systems.
Abstract: We discuss services and system architecture issues for future wireless communication in the vehicular environment We consider the problem of wireless network heterogeneity that will be a consequence of emerging technologies such as wireless LANs, ad hoc networks, and broadcast systems, in addition to third-generation cellular standards like UMTS In particular, a communication gateway architecture is proposed as an essential building block in future automobile systems It enables services and applications within the car to transparently use different wireless communication systems Our article gives a high-level view of the component architecture of the gateway and its adaptation layer to the wireless infrastructure
TL;DR: This work provides an automatic data recharging capability based on user profiles written in an expressive profile language that identifies relevant information and orders it by its usefulness.
Abstract: Mobile devices need two basic renewable resources - power and data. Power recharging is easy; data recharging is a much more problematic activity. It requires complex interaction between a user and a collection of data sources. We provide an automatic data recharging capability based on user profiles written in an expressive profile language. A profile identifies relevant information and orders it by its usefulness. We discuss the issues involved in designing a profile language for data recharging.
TL;DR: A network platform with future IP-based techniques for "beyond IMT-2000" is described and the study of key network techniques featured in the proposed platform architecture is discussed.
Abstract: This article describes a network platform with future IP-based techniques for "beyond IMT-2000." First, it presents a vision for beyond IMT-2000 in terms of requirements for service and network capabilities. Next, it shows a general architecture of the IP-based IMT network platform (IP/sup 2/). Then it discusses the study of key network techniques (location management, routing/handover, and service management) featured in the proposed platform architecture.
TL;DR: The network architecture of the mobile communications system beyond IMT-2000 that will satisfy requirements and offer higher bit rate channels and adapt to multimedia traffic more efficiently is considered.
Abstract: This article describes a suitable network architecture for the mobile communications system beyond IMT-2000. The rapid developments in mobile communication services have significantly altered the lifestyles of many people. With the increasing demand for access to the Internet, the amount of data traffic in mobile communication networks has significantly increased and will dominate these networks. Therefore, mobile networks beyond IMT-2000 should offer higher bit rate channels and adapt to multimedia traffic more efficiently. This article first forecasts market trends in mobile communications in order to identify requirements of the mobile communications system beyond IMT-2000. Then the article considers the network architecture of the mobile communications system beyond IMT-2000 that will satisfy those requirements.
TL;DR: A techno-economic evaluation of 3G rollout scenarios in two "typical" European countries with contrasting profiles, analyzing both the incumbent and newcomer business cases is presented, based on a techno- economic methodology developed within the ACTS-TERA project.
Abstract: This article presents a techno-economic evaluation of 3G rollout scenarios in two "typical" European countries with contrasting profiles, analyzing both the incumbent and newcomer business cases. The analysis is based on a techno-economic methodology developed within the ACTS-TERA project. Market and tariff forecasts as well as the technological evolutionary paths are discussed and financial figures are analyzed. Sensitivity analysis follows these basic results in order to identify the impact of uncertainties and risks. The success of such an investment project mainly depends on the regulatory framework, demand and tariff structure, and the market share.
TL;DR: In this article, the authors discuss aspects of implementing a complete Hiperlan/2 and IEEE 802.11a compliant modem, including the physical layer as well as the data link control layer, into a single chip.
Abstract: Broadband wireless communication is the key technology to a new generation of products in the consumer market. The emerging standards for the 5 GHz band will form the basis for many applications requiring a high communication bandwidth. Low cost and low power dissipation will be a prerequisite for most mobile applications. One way to realize low-cost systems is to reduce the system complexity and deploy highly integrated components. The work presented in this article discusses aspects of implementing a complete Hiperlan/2 and IEEE 802.11a compliant modem, including the physical layer as well as the data link control layer, into a single chip.
TL;DR: In this paper, the authors explore characteristics of the future satellite networks and their interoperability with terrestrial wireless and wired networks and explore the issues that must be resolved before satellite and terrestrial networks take place.
Abstract: Satellites will continue to be an essential element in the establishment of long-distance telecommunications for many years, and it will have a major role in the implementation of the so-called global information infrastructure in the future. This is because of the particular feature of the satellite that can provide wide coverage independent of the actual land distance between any pair of communicating entities. The new generation of broadband satellite systems, which can provide high-speed data transmission and connectivity to terrestrial data networks, will create profound changes in all aspects of the emerging data communications applications such as the Internet and electronic commerce. We explore characteristics of the future satellite networks and their interoperability with terrestrial wireless and wired networks. The emerging data and IP applications impose new implementation issues on the long-latency and restricted satellite channel that must be resolved before such interoperability between satellite and terrestrial networks takes place.
TL;DR: This work defined a horizontal and uniform software architecture for building a Web presence for people, places, and things that enables the dynamic generation of Web contents based on the user context, security permissions, and the relationships with other Web presences.
Abstract: The Cooltown vision is that people, places, and things have a Web representation and that many useful services can be offered by creating a tighter link between the real world entity and its virtual representation. We defined a horizontal and uniform software architecture for building a Web presence for people, places, and things. This architecture enables the dynamic generation of Web contents based on the user context (location, identity, device capabilities), security permissions, and the relationships with other Web presences. Our implementation of this architecture is portable enough to be embedded in the entity that the Web presence describe but also scalable enough to support multiple Web presence hosting. We focused on making the creation of a Web presence easy for non-programmers.
TL;DR: An evolution of an IP-based infrastructure from today's networks toward a future multi-radio infrastructure enables the cooperation of existing radio networks to combine their spectrum-efficient capabilities, whereby high-quality mobile multimedia services shall be provided.
Abstract: The demand of both the new telecom industry and digital broadcasters for cost-efficient provisioning of mobile multimedia services faces the reality of scarce radio resources. Various digital mobile and broadcast radio technologies have been developed and specifically been optimized. However, existing and emerging multimedia services exhibit challenging requirements in terms of asymmetry, interactivity, real time, and multicast communication. This article describes an evolution of an IP-based infrastructure from today's networks toward a future multi-radio infrastructure, taking into account the implications on the end-user terminal. This multi-radio infrastructure enables the cooperation of existing radio networks to combine their spectrum-efficient capabilities, whereby high-quality mobile multimedia services shall be provided. Furthermore, the need for dynamic allocation of spectrum to radio services is motivated. The basic functionality and architecture of a multi-radio system are outlined, with a special emphasis on cooperation between different radio systems. Also, an evolution path for the convergence of broadcast and new telecom is described, starting from today's systems and leading to a fully coordinated system.
TL;DR: The simulation results evaluating the uplink BER performance of W-CDMA is slightly better than that of OFDM, and these differences in performance become even smaller when channel coding is applied and when LOS conditions between the mobile terminal and the LEO satellite exist.
Abstract: This article presents a comparison study of the uplink performance of two well-known transmission schemes, W-CDMA and OFDM, for mobile multimedia communications via LEO satellite. In order to provide a framework for a fair comparison we have considered for both schemes common parameters, including identical channel bandwidth, coding/decoding algorithms and similar net data rate. The values of these parameters have been appropriately selected in accordance with the corresponding UMTS system specifications. For W-CDMA, we propose a receiver structure that eliminates ISI for both channel estimation and equalization at the LEO satellite. For OFDM, we propose a system the design of of which is based upon the parameters of W-CDMA for UMTS. For both schemes appropriate transceiver structures are proposed and analyzed and their performance is evaluated in terms of computer simulation. The design of these transceiver structures effectively takes into account the statistical characteristics of the LEO satellite channel, so that the overall system performance is improved. The simulation results evaluating the uplink BER performance for a single user indicate that, although the BER performance of W-CDMA is slightly better than that of OFDM, the performance differences are rather small. Furthermore, these differences in performance become even smaller when channel coding is applied and when LOS conditions between the mobile terminal and the LEO satellite exist. Since these results have not shown a clear-cut winner, further comparative studies are required in order to identify the most appropriate transmission scheme for applications supporting global mobile multimedia communication via LEO satellite networks. Such studies should include determination of the downlink BER performance as well as spectrum efficiency and capacity performance equations for both up and down satellite communication links.
TL;DR: The suitability of MBAC in wireless IP networks is discussed by comparing its pros and cons with traditional parameter based schemes, and its procedures are described, and the effect of delay tolerance on the overall system performance is investigated.
Abstract: The huge commercial success of mobile telephony, phenomenal growth of mobile and Internet users, and emerging popularity of IP-based multimedia applications are the major driving forces behind third-generation (3G) evolution. 3G will bring will bring applications, both data and multimedia, into wireless environments. It will operate on IP-based infrastructures to provide wider service access capability. However, current IP is designed for data applications with a single service class, best-effort. Therefore, it is insufficient to support real-time applications that require diverse quality of service (QoS). Although IP can provide greater service flexibility in terms of spectrum efficiency and QoS, it is not the most appropriate choice in wireless environments. In order to support real-time applications in wireless IP networks, measurement-based admission control (MBAC) is considered. We consider two admission criteria, reservation and priority. The system performance is measured in terms of new call blocking and hand-off call dropping probabilities with three different levels of user mobility: low, moderate and high level of mobility. Considering the delay-tolerant nature of real-time applications in wireless IP networks, the effect of delay tolerance on the overall system performance is also investigated. We discuss the suitability of MBAC in wireless IP networks by comparing its pros and cons with traditional parameter based schemes, and then describe its procedures. Next, we discuss simulation details, and present simulation results with discussions. We compare new and hand-off traffic performance with strictly policy-based and policy and traffic characteristic-based admission control schemes. We discuss the effectiveness of MBAC and its role in 3G and forthcoming 4G networks.
TL;DR: These problems are described along with the solutions previously proposed in the literature and both real-time and non-real-time applications are considered.
Abstract: Traditional transport layer flow control schemes proposed for IP networks have low performance when satellite links are involved in the communication. These problems are described along with the solutions previously proposed in the literature. For each solution the advantages and drawbacks of the existing solutions are pointed out. Both real-time and non-real-time applications are considered.
TL;DR: Class A dual transfer mode of GPRS/EDGE operation addresses barriers in the migration path from the so-called 2.5G services offered by GSM to similar ones offered by UMTS and the ability to offer users a reasonably priced service that combines voice and data interchange capabilities with a low-cost mobile station.
Abstract: Class A dual transfer mode of GPRS/EDGE operation addresses barriers in the migration path from the so-called 2.5G services offered by GSM to similar ones offered by UMTS and the ability to offer users a reasonably priced service that combines voice and data interchange capabilities with a low-cost mobile station.
TL;DR: The importance of pervasive computing is rapidly increasing with the current trend toward universal presence of mobile computing, computer networks, and wireless communications ineveryday life.
Abstract: he importance of pervasive computing is rapidlyincreasingwith the current trend toward universal presence of mobile computing, computer networks, and wireless communications ineveryday life. In thelastdecade, there has been a dramatic increase in the use of companion devices and embedded computing devices. For example, wirelessly connectcd organizers and smart phones are becoming popular, and digital computing in some form is now an integral part of numerous evcryday appliances. This has led to a change in thc waywe perceive computing andcomputers. Computers are no longer standalone special-purpose machines to beusedbyexperts; rather, they arc ubiquitously present in a networked environment to scrve myriad needs of everyday life. The change in our perception of computing and computing devices, and their ever increasing presence in our everyday life is the subject of the new ficld known as pervasive computing. The word pervasive
IBM1
TL;DR: A rate-2/3 run-length-limited code designed to meet basic system requirements and modulation constraints imposed by the WIrC is introduced and it is shown that the specific composite nature of the new RLL modulation code enables simple and efficient generation of VFIr packet frames.
Abstract: Devices for convenient information exchange over the wireless infrared channel are commonly found in many of today's mobile platforms for computing, communicating, and imaging. Most devices comply with the international standards promoted by the Infrared Data Association for data rates of up to 4 Mb/s. With the approval of a 16 Mb/s data rate option called Very Fast Infrared, IrDA's point-to-point usage model is extendable to applications requiring wireless connectivity beyond 4 Mb/s. We describe the design and the properties of a new modulation code specifically developed for VFIr, and discuss related system design aspects. After defining basic system requirements and modulation constraints imposed by the WIrC, we introduce a rate-2/3 run-length-limited code designed to meet these criteria. The Boolean expressions for encoding and decoding are given, and their implementation is discussed together with various aspects of system design such as scrambling, invalid sequence detection, and error propagation. Furthermore, it is shown that the specific composite nature of the new RLL modulation code enables simple and efficient generation of VFIr packet frames by encoding an equivalent packet frame assembled entirely in the code's input data domain.
IBM1
TL;DR: The article focuses on the evolution of the application design through a process that alternated design activities with formative evaluations in the field, and the result was to produce a solution for home ordering of groceries using a PDA.
Abstract: The coming ubiquity of handheld devices and e-commerce will offer many new design and application opportunities for human-computer interaction, many of them in "everyday" domains. This article reports on the iterative design of a handheld application for one such domain, grocery shopping. Our goal was to produce a solution for home ordering of groceries using a PDA. The article focuses on the evolution of the application design through a process that alternated design activities with formative evaluations in the field. At the end of the design and development process, 200 shoppers in the United Kingdom were using the resulting application.
TL;DR: The article describes the work performed to date in the Wireless Internet Network (WINE) project, sponsored by the European Commission, under the framework V Information Society Technologies (IST) program, to enhance the performance of Internet protocols when operating over wireless LANs.
Abstract: The article describes the work performed to date in the Wireless Internet Network (WINE) project, sponsored by the European Commission, under the framework V Information Society Technologies (IST) program. The project aims to enhance the performance of Internet protocols when operating over wireless LANs. One of the key issues of the project is the development of a wireless adaptation layer (WAL) that resides between the IP and WLAN link layers. The WAL may be viewed as a "shim" layer that compensates for wireless impairments. An important feature of the WAL architecture is its ability to map quality of service protocols such as differentiated services onto WLANs. The architecture also aims to support intradomain mobility, and a range of existing mechanisms have been reviewed and enhanced for that purpose. The project,includes the development of extended testbeds and simulation models to assess the performance of the proposed solutions.
TL;DR: In this paper, a new approach for soft handoff in distributed all-IP wireless networks is presented, which consists of two main parts: first, a new design of IP-based distributed base stations enables mobile stations in multiple cells to be on the same IP subnet and multiple streams of the same data to be distributed via multiple base stations to a mobile without broadcasting/multicasting and with minimal signaling.
Abstract: The Internet protocol (IP) can potentially become the universal network-layer protocol over all wireless systems as it already is for wireline packet networks. Such an all-IP wireless and wireline network can bring the proven advantages of IP networking to mobile users. However, realizing an all-IP wireless network introduces many challenges, among which is soft handoff. Two major problems need to be solved in order to support soft handoff. First, multiple streams of the same IP traffic have to be distributed via multiple base stations to a mobile station. Second, pieces of data arriving at the mobile station at the same time from different base stations need to be copies of the same data in order for the mobile station's radio system to correctly combine these different pieces into a single copy. A similar problem also needs to be resolved in the reverse direction from mobile stations to base stations. Solving these problems in a distributed all-IP wireless network remains a challenge. Although solutions exist for today's circuit-switched wireless systems. This article presents a new approach for soft handoff in distributed all-IP wireless networks. It consists of two main parts. First, a new design of IP-based distributed base stations enables mobile stations in multiple cells to be on the same IP subnet and multiple streams of the same data to be distributed via multiple base stations to a mobile without broadcasting/multicasting and with minimal signaling. Second, a novel IP-layer procedure performed by the base stations ensures that the data coming simultaneously from multiple base stations to a mobile station are copies of the same data.