Showing papers on "Wi-Fi array published in 2002"

Space-Time Codes for High Data Rate Wireless Communications

Abstract: Space-time codes (STC) are a class of signaling techniques, offering coding and diversity gains along with improved spectral efficiency. These codes exploit both the spatial and the temporal diversity of the wireless link by combining the design of the error correction code, modulation scheme and array processing. STC are well suited for improving the downlink performance, which is the bottleneck in asymmetric applications such as downstream Internet. Three original contributions to the area of STC are presented in this dissertation. First, the development of analytic tools that determine the fundamental limits on the performance of STC in a variety of channel conditions. For trellis-type STC, transfer function based techniques are applied to derive performance bounds over Rayleigh, Rician and correlated fading environments. For block-type STC, an analytic framework that supports various complex orthogonal designs with arbitrary signal cardinalities and array configurations is developed. In the second part of the dissertation, the Virginia Tech Space-Time Advanced Radio (VT-STAR) is designed, introducing a multi-antenna hardware laboratory test bed, which facilitates characterization of the multiple-input multiple-output (MIMO) channel and validation of various space-time approaches. In the third part of the dissertation, two novel space-time architectures paired with iterative processing principles are proposed. The first scheme extends the suitability of STC to outdoor wireless communications by employing iterative equalization/decoding for time dispersive channels and the second scheme employs iterative interference cancellation/decoding to solve the error propagation problem of Bell-Labs Layered Space-Time Architecture (BLAST). Results show that remarkable energy and spectral efficiencies are achievable by combining concepts drawn from space-time coding, multiuser detection, array processing and iterative decoding.

APTEEN: a hybrid protocol for efficient routing and comprehensive information retrieval in wireless

Abstract: Wireless sensor networks with thousands of tiny sensor nodes, are expected to find wide applicability and increasing deployment in coming years, as they enable reliable monitoring and analysis of the environment. In this paper, we propose a hybrid routing protocol (APTEEN) which allows for comprehensive information retrieval. The nodes in such a network not only react to time-critical situations, but also give an overall picture of the network at periodic intervals in a very energy efficient manner. Such a network enables the user to request past, present and future data from the network in the form of historical, one-time and persistent queries respectively. We evaluated the performance of these protocols and observe that these protocols are observed to outperform existing protocols in terms of energy consumption and longevity of the network.

Exploiting the 60 GHz band for local wireless multimedia access: prospects and future directions

Abstract: This article addresses basic issues regarding the design and development of wireless access and wireless LAN systems that will operate in the 60 GHz band as part of the fourth-generation (4G) system. The 60 GHz band is of much interest since this is the band in which a massive amount of spectral space (5 GHz) has been allocated worldwide for dense wireless local communications. The article gives an overview of 60 GHz channel characteristics and puts them in their true perspective. In addition, we discuss how to achieve the exploitation of the abundant bandwidth resource for all kinds of short-range communications. The main tenor is that an overall system architecture should be worked out that provides industry with plenty of scope for product differentiation. This architecture should feature affordability, scalability, modularity, extendibility, and interoperability. In addition, user convenience and easy and efficient network deployment are important prerequisites for market success. This article discusses these features and indicates a number of key research topics.

Wake on wireless: an event driven energy saving strategy for battery operated devices

Abstract: The demand for an all-in-one phone with integrated personal information management and data access capabilities is beginning to accelerate. While personal digital assistants (PDAs) with built-in cellular, WiFi, and Voice-Over-IP technologies have the ability to serve these needs in a single package, the rate at which energy is consumed by PDA-based phones is very high. Thus, these devices can quickly drain their own batteries and become useless to their owner.In this paper, we introduce a technique to increase the battery lifetime of a PDA-based phone by reducing its idle power, the power a device consumes in a "standby" state. To reduce the idle power, we essentially shut down the device and its wireless network card when the device is not being used---the device is powered only when an incoming call is received. Using this technique, we can increase the battery lifetime by up to 115%.In this paper, we describe the design of our "wake-on-wireless" energy-saving strategy and the prototype device we implemented. To evaluate our technique, we compare it with alternative approaches. Our results show that our technique can provide a significant lifetime improvement over other technologies.

Use of presence and location information concerning wireless subscribers for instant messaging and mobile commerce

Abstract: Presence determination (112), location determination (114), instant messaging (116), and mobile commerce (118) are integrated into a functionally seamless system, which may be implemented as an added component of a wireless provider's network. Alternatively, the integrated system enables instant messaging and mobile commerce as a centralized gateway attached to the networks of a large number of wireless providers. The gateway facilitates a business model that advances beyond today's practices, in which individual wireless carriers enter into bi-lateral agreements with specific Internet content providers. The functionally integrated gateway disclosed empowers Internet services that require realtime information about wireless subscribers in order to conduct m-commerce or offer advanced messaging services. Optimization of a wireless network is also facilitated by taking network performance measurements, without using a special drive test team, via devices that are regularly using the network during standard network operation.

Characterizing user behavior and network performance in a public wireless LAN

Abstract: This paper presents and analyzes user behavior and network performance in a public-area wireless network using a workload captured at a well-attended ACM conference. The goals of our study are: (1) to extend our understanding of wireless user behavior and wireless network performance; (2) to characterize wireless users in terms of a parameterized model for use with analytic and simulation studies involving wireless LAN traffic; and (3) to apply our workload analysis results to issues in wireless network deployment, such as capacity planning, and potential network optimizations, such as algorithms for load balancing across multiple access points (APs) in a wireless network.

Handbook of wireless networks and mobile computing

Abstract: If you want to get Handbook of Internet Computing pdf eBook copy write by good Handbook of Wireless Networks and Mobile Computing Google Books. Mobile Computing General. Handbook of Algorithms for Wireless Networking and Mobile Computing by Azzedine Boukerche (Editor). Call Number: TK 5103.2. CITS4419 Mobile and Wireless Computing software projects related to wireless networks, (2) write technical reports and documentation for complex computer.

On indoor position location with wireless LANs

Abstract: Location aware services are becoming attractive with the deployment of next generation wireless networks and broadband multimedia wireless networks especially in indoor and campus areas. To provide location aware services, obtaining the position of a user accurately is important. While it is possible to deploy additional infrastructure for this purpose, using existing communications infrastructure is preferred for cost reasons. Because of technical restrictions, location fingerprinting schemes are the most promising. In this paper we present a systematic study of the performance tradeoff and deployment issues. In this paper we present some experimental results towards such a systematic study and discuss some issues related to the indoor positioning problem.

Analysis of a campus-wide wireless network

Abstract: Understanding usage patterns in wireless local-area networks (WLANs) is critical for those who develop, deploy, and manage WLAN technology, as well as those who develop systems and application software for wireless networks. This paper presents results from the largest and most comprehensive trace of network activity in a large, production wireless LAN. For eleven weeks we traced the activity of nearly two thousand users drawn from a general campus population, using a campus-wide network of 476 access points spread over 161 buildings. Our study expands on those done by Tang and Baker, with a significantly larger and broader population.We found that residential traffic dominated all other traffic, particularly in residences populated by newer students; students are increasingly choosing a wireless laptop as their primary computer. Although web protocols were the single largest component of traffic volume, network backup and file sharing contributed an unexpectedly large amount to the traffic. Although there was some roaming within a network session, we were surprised by the number of situations in which cards roamed excessively, unable to settle on one access point. Cross-subnet roams were an especial problem, because they broke IP connections, indicating the need for solutions that avoid or accommodate such roams.

Device and method for intelligent wireless communication selection

Abstract: A wireless communication device (100) includes one or more radio interfaces (102-109) to communicate using various wireless protocols with different communication networks. The wireless device may, for example, be a notebook or laptop computer, a personal digital assistant (PDA), a mobile data terminal, wireless telephone, video camera or another multimedia device. A multi-channel radio controller (110) within the wireless device characterizes available communication networks to determine network characteristics including current network information. Available communication networks and services may be characterized by monitoring traffic, using location information, interrogating or from current connectivity. A wireless connectivity assistant (112) may select a communication network and service based on the network characteristics and at least one of user preferences, application requirements and system information.

Measurements of a wireless link in an industrial environment using an IEEE 802.11-compliant physical layer

Abstract: The design and simulation of coding schemes, medium access control (MAC), and link-layer protocols for future industrial wireless local area networks can be supported by some understanding of the statistical properties of the bit error patterns delivered by a wireless link (which is an ensemble of transmitter, channel, receiver, modems). The authors present results of bit error measurements taken with an IEEE 802.11-compliant radio modem in an industrial environment. In addition to reporting the most important results, they draw some conclusions for the design of MAC and link-layer protocols. Furthermore, they show that the popular Gilbert/Elliot model and a modified version of it are a useful tool for simulating bit errors on a wireless link, despite their simplicity and failure to match certain measured statistics.

Maximum lifetime data gathering and aggregation in wireless sensor networks

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Next-generation wireless communications concepts and technologies

Abstract: Next-generation wireless (NextG) involves the concept that the next generation of wireless communications will be a major move toward ubiquitous wireless communications systems and seamless high-quality wireless services. This article presents the concepts and technologies involved, including possible innovations in architectures, spectrum allocation, and utilization, in radio communications, networks, and services and applications. These include dynamic and adaptive systems and technologies that provide a new paradigm for spectrum assignment and management, smart resource management, dynamic and fast adaptive multilayer approaches, smart radio, and adaptive networking. Technologies involving adaptive and highly efficient modulation, coding, multiple access, media access, network organization, and networking that can provide ultraconnectivity at high data rates with effective QoS for Next Gare are also described.

An implicit prioritized access protocol for wireless sensor networks

Abstract: Recent advances in wireless technology have brought us closer to the vision of pervasive computing where sensors/actuators can be connected through a wireless network. Due to cost constraints and the dynamic nature of sensor networks, it is undesirable to assume the existence of base stations connected by a wired backbone. In this paper, we present a network architecture suitable for sensor networks along with a medium access control protocol based on earliest deadline first.

Wireless Communications and Networking

Abstract: 1. Overview of Wireless Communications and Networking. 2. Characterization of the Wireless Channel. 3. Bandpass Transmission Techniques for Mobile Radio. 4. Receiver Techniques for Fading Dispersive Channels. 5. Fundamentals of Cellular Communications. 6. Multiple Access Techniques. 7. Mobility Management in Wireless Networks. 8. Wireless/Wireline Interworking. Appendices. References. Answers to Selected Problems.

Antenna systems for broadband wireless access

Abstract: 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.

Method and apparatus for converging local area and wide area wireless data networks

Abstract: A converged network accessible by wireless client devices (fig. 2) includes a wide area wireless network, a local area wireless network, and a gateway linked to the wide area and local area wireless networks for integrating access to the networks by the wireless client devices.

Method and apparatus for integrating wireless communication and asset location

Abstract: A method and apparatus to identify tags in a wireless tag identification system. Operation of the wireless tag identification system may be controlled to minimize interference or otherwise improve interoperation with a wireless communication system, such as a wireless local area network (WLAN). For example, the timing and/or power of wireless signals produced by the wireless tag identification system can be controlled to provide sufficient space to the wireless communication system to operate properly. The systems may be tightly integrated, e.g., so that tags may be identified by responding to wireless communications traffic as opposed to special purpose tag search signals. The wireless communications traffic may be modified to enhance tag location resolution.

Method for providing entertainment to a portable device

Abstract: A unique method for providing entertainment to a portable device, such as a wireless communication device, is disclosed. The method includes steps of receiving location information related to said wireless communication device; providing challenges associated with a game to a user of a wireless communication; providing rewards in response to answers based upon the location of said wireless communication device. The method finds particular application in vehicles having telematics communications products.

System, method, and computer program product for sharing bandwidth in a wireless personal area network or a wireless local area network

Abstract: A system, method, and computer program product for sharing bandwidth by a plurality of devices in a wireless personal area network or a wireless local area network. A media access control protocol frame includes a beacon signal sent from a coordinator including coordination information to each of the devices of the WPAN, an optional contention access period, and a contention free period that includes an additional shared period that is managed as a slot cycle time division multiple access period, a polling period, or as management period. The coordination information includes a device-unique start time indicator and a transmission duration defining a guaranteed time slot within the contention free period of the frame for each of the networked devices. Each of the network devices sleeps while not receiving the beacon and not transmitting data during their guaranteed time slot, thereby reducing power consumption as compared to slot cycle time division multiple access or polling schemes which require listening by all devices during the contention free period.

Device with passive receiver

Abstract: A wireless communications apparatus includes a wake-up receiver adapted to receive a wake-up signal and an initially powered-off, sleeping wireless communications transceiver. When the wake-up receiver receives the wake-up signal, it can in turn power on the wireless communications transceiver. In another aspect, the invention includes an apparatus for sending a wake-up signal to the wake-up receiver. The wake-up transmitter and the wake-up receiver can communicate via a variety of wireless communications protocols, including the BLUETOOTH™ standard.

A multimedia publishing system for wireless devices

Abstract: A dynamic publishing system for delivery and presentation of multimedia on a wireless device, such as a PDA or mobile telephone. A presentation server dynamically compiles application data based on scene description data for one or more media objects, and sends the application data to the wireless device for presentation of the media objects. The wireless device has a media player that is able to process the application data at an object level for the objects in response to events, and control the presentation. The application data includes content, layout and control logic data for the media objects.

Frequency assignment for multi-cell IEEE 802.11 wireless networks

Abstract: A frequency planning method for use in an IEEE 802.11 wireless network is described. The frequency planning method obtains traffic load information associated with access points belonging to a multi-cell wireless network and assigns channels to the access points based on the traffic load information.

System and method for wireless data terminal management using general packet radio service network

Abstract: A method, system, and computer program product that provides the capability to manage, control, and reconfigure wireless devices remotely over a wireless network with acceptable reliability and security. A method for remotely managing a wireless device over a telecommunications network comprising a server and the wireless device, the method comprises the steps of establishing a communicative connection between the server and the wireless device over a packet radio channel of the telecommunications network, transmitting a command from the server to the wireless device over the packet radio channel, and executing the command at the wireless device.

MIRAI architecture for heterogeneous network

Abstract: One of the keywords that describe next-generation wireless communications is "seamless." As part of the e-Japan Plan promoted by the Japanese Government, the Multimedia Integrated Network by Radio Access Innovation project has as its goal the development of new technologies to enable seamless integration of various wireless access systems for practical use by 2005. This article describes a heterogeneous network architecture including a common tool, a common platform, and a common access. In particular, software-defined radio technologies are used to develop a multiservice user terminal to access different wireless networks. The common platform for various wireless networks is based on a wireless-supporting IPv6 network. A basic access network, separated from other wireless access networks, is used as a means for wireless system discovery, signaling, and paging. A proof-of-concept experimental demonstration system is available.

System and methodology for control of, and access and response to internet email from a wireless device

Abstract: The invention discloses a system and method for access and response to Internet emails, from a wireless device. The system extracts the emails from multiple Internet email accounts and forwards them, on the basis of pre-defined filter settings of the user, to the user's wireless device. The filter settings comprise filter criteria for identifying whether a new mail is to be forwarded to the wireless device or not, and content selection criteria for identifying parts of the new email to be sent to the wireless device. The system also enables the user to reply to the emails in a transparent manner whereby the replied message from the wireless device appears to have originated from the email address. The system also enables the user to dynamically change the filter settings using multi-modal inputs from his/her wireless device.

A wireless embedded sensor architecture for system-level optimization

Abstract: Emerging low power, embedded, wireless sensor devices are useful for wide range of applications, yet have very limited processing, storage, and especially energy resources. Thus, a key design challenge is to support application-specific optimizations in a highly flexible manner. Power consumption and capabilities of the radio communication layer are the dominant factors in overall system performance. This paper presents a wireless sensor node architecture to achieve high communication bandwidth with the flexibility to efficiently implement novel communication protocols. The architecture is instantiated in an operational design using commercial microcontroller and radio technology. Its ability to optimize system performance by using unconventional protocols is demonstrated by four case studies involving power management, synchronization, localization, and wake-up.

Analysis of a metropolitan-area wireless network

Abstract: We analyze a seven-week trace of the Metricom metropolitan-area packet radio wireless network to find how users take advantage of a mobile environment. Such understanding is critical for planning future large-scale mobile network infrastructures. Amongst other results, we find that users typically use the radios during the day and evening. Of the users who move around during the trace (over half), we find that the more locations a user visits on a daily basis, the closer together, on average, those locations are. While these results are only known to be valid for this particular network, we hope future analysis of other networks will add to a growing understanding of mobile network behavior.

Wireless malware scanning back-end system and method

Abstract: A system, method and computer program product are provided for scanning a plurality of mobile wireless devices for malware. A request is received to update an anti-malware scanner installed on a mobile wireless device over a wireless network. Further, an update tailored for the mobile wireless device is prepared using a back-end infrastructure. Such tailored update is then transmitted from the back-end infrastructure to the mobile wireless device over the wireless network.