Showing papers by "NTT DoCoMo published in 2004"

Ambient networks: an architecture for communication networks beyond 3G

Abstract: In this article we present a new networking concept referred to as ambient networks, which aims to enable the cooperation of heterogeneous networks belonging to different operator or technology domains. We aim to provide a domain-structured edge-to-edge view for the network control to embrace the heterogeneity arising from the different network control technologies. In this way, it appears as homogeneous to the users of the network services. We aim for an instant network composition to allow rapid adaptation of the network domain topology as required for moving networks. This new view of network composition allows us to treat the communication endpoints as a special case of network domains as well. We introduce the ambient control space, which enables the ambient networks concept and introduce its main features. Two ambient control space functions, media delivery and generic link layer, are presented in more detail. AMBIENT NETWORKS: AN ARCHITECTURE FOR COMMUNICATION NETWORKS BEYOND 3G

Evaluating location predictors with extensive Wi-Fi mobility data

Abstract: Location is an important feature for many applications, and wireless networks can better serve their clients by anticipating client mobility. As a result, many location predictors have been proposed in the literature, though few have been evaluated with empirical evidence. This paper reports on the results of the first extensive empirical evaluation of location predictors, using a two-year trace of the mobility patterns of over 6,000 users on Dartmouth's campus-wide Wi-Fi wireless network. We implemented and compared the prediction accuracy of several location predictors drawn from two major families of domain-independent predictors, namely Markov-based and compression-based predictors. We found that low-order Markov predictors performed as well or better than the more complex and more space-consuming compression-based predictors. Predictors of both families fail to make a prediction when the recent context has not been previously seen. To overcome this drawback, we added a simple fallback feature to each predictor and found that it significantly enhanced its accuracy in exchange for modest effort. Thus the Order-2 Markov predictor with fallback was the best predictor we studied, obtaining a median accuracy of about 72% for users with long trace lengths. We also investigated a simplification of the Markov predictors, where the prediction is based not on the most frequently seen context in the past, but the most recent, resulting in significant space and computational savings. We found that Markov predictors with this recency semantics can rival the accuracy of standard Markov predictors in some cases. Finally, we considered several seemingly obvious enhancements, such as smarter tie-breaking and aging of context information, and discovered that they had little effect on accuracy. The paper ends with a discussion and suggestions for further work.

Robust indoor location estimation of stationary and mobile users

Abstract: We present algorithms for estimating the location of stationary and mobile users based on heterogeneous indoor RF technologies. We propose two location algorithms, selective fusion location estimation (SELFLOC) and region of confidence (RoC), which can be used in conjunction with classical location algorithms such as triangulation, or with third-party commercial location estimation systems. The SELFLOC algorithm infers the user location by selectively fusing location information from multiple wireless technologies and/or multiple classical location algorithms in a theoretically optimal manner. The RoC algorithm attempts to overcome the problem of aliasing in the signal domain, where different physical locations have similar RF characteristics, which is particularly acute when users are mobile. We have empirically validated the proposed algorithms using wireless LAN and Bluetooth technology. Our experimental results show that applying SELFLOC for stationary users when using multiple wireless technologies and multiple classical location algorithms can improve location accuracy significantly, with mean distance errors as low as 1.6 m. For mobile users we find that using RoC can allow us to obtain mean errors as low as 3.7 m. Both algorithms can be used in conjunction with a commercial location estimation system and improve its accuracy further.

Menu item selecting device and method

Abstract: As menu items configuring a menu page displayed in a display device of a cellular phone, facial portraits of persons with whom a predetermined function is executed can be registered.

Benefits and challenges for platform-based design

Abstract: Platforms have become an important concept in the design of electronic systems. We present here the motivations behind the interest shown and the challenges that we have to face to make the Platform-based Design method a standard. As a generic term, platforms have meant different things to different people. The main challenges are to distill the essence of the method, to formalize it and to provide a framework to support its use in areas that go beyond the original domain of application.

Error characteristics and calibration-free techniques for wireless LAN-based location estimation

Abstract: Using wireless LAN technology for location estimation provides alternate means to enable location-based applications without investment in sensor network infrastructure and special hardware. However, the main drawback of wireless LAN-based location systems is calibration of signal strength as a function of location in spatially high-density, which consumes manual labor and needs to be carried out repeatedly. In this paper, we analyze empirical error characteristics of calibration-based location algorithms such as triangulation in various spatial densities of calibration, using commercially available wireless LAN products. Then, we propose Triangular Interpolation and eXtrapolation (TIX), a calibration-free location algorithm, and present empirical performance evaluation. TIX can achieve mean distance error within 5.4 m, which is comparable to within 4.7 m errors of the calibration-based algorithms. We also present theoretical analysis on error characteristics of the location algorithms deriving accuracy limits and quantifying the effect of RF measurement and calibration.

Charging, accounting and billing management schemes in mobile telecommunication networks and the internet

Abstract: The current technological advances in mobile telecommunication networks and the Internet are about to alter existing business models. These different worlds converge and create an open market, where a large number of independent application/service providers will offer their services to users through a limited number of network providers. At the same time, the evolution of existing network technologies and the specification of new concepts requires new advanced and holistic solutions in several technical areas. One such area is related to the design and management of new sophisticated functions and protocols to support innovative, flexible, and efficient charging, accounting, and billing mechanisms. This survey article considers the key concepts of such mechanisms, and the requirements they impose upon the network infrastructure. The article presents the latest efforts undertaken by standardization bodies in the mobile telecommunication industry as well as by Internet Working Groups to meet these requirements.

Adaptive selection of surviving symbol replica candidates based on maximum reliability in QRM-MLD for OFCDM MIMO multiplexing

Abstract: The paper proposes an adaptive selection algorithm for surviving symbol replica candidates based on the maximum reliability in ML detection with QR decomposition and M-algorithm (QRM-MLD) for OFCDM MIMO multiplexing. In the proposed algorithm, symbol replica candidates newly-added at each stage are ranked for each surviving symbol replica from the previous stage using multiple quadrant detection. Then, branch metrics are calculated only for the limited number of symbol replica candidates with high reliability based on an iterative loop in increasing order of the accumulated branch metrics from the candidate with the minimum one. Simulation results show that the computational complexity of the proposed algorithm from the viewpoint of the number of real multiplications is reduced to approximately 1/6 and 1/1900, respectively, compared to that of the original QRM-MLD and that of the conventional MLD with squared Euclidian distance calculations for all symbol replica candidates, assuming the identical achievable average block error rate (BLER) performance in 4-by-4 MIMO multiplexing with 16QAM data modulation. The results also show that 1-Gbps throughput is achieved at the E/sub b//N/sub 0/ per receiver antenna of approximately 9 dB using the adaptive selection algorithm in QRM-MLD associated with 16QAM modulation and turbo coding with coding rate of 8/9, assuming a 100-MHz bandwidth for a twelve-path Rayleigh fading channel (rms delay spread, 0.26 /spl mu/sec; maximum Doppler frequency, 20 Hz).

Api system, method and computer program product for accessing content/security analysis functionality in a mobile communication framework

Abstract: A system, method and computer program product are provided for accessing security or content analysis functionality utilizing a mobile communication device. Included is an operating system installed on a mobile communication device capable of communicating via a wireless network. Further provided is an application program installed on the mobile communication device and executed utilizing the operating system for performing tasks. A scanning subsystem remains in communication with the application program via an application program interface. Such scanning subsystem is adapted for accessing security or content analysis functionality in conjunction with the tasks performed by the application program.

I-centric communications: personalization, ambient awareness, and adaptability for future mobile services

Abstract: The acceptance of next-generation mobile communication systems depends to a large extent on the services and applications that can be offered to customers. Tailoring the services to actual user needs is considered to be crucial for the success of future wireless technology. The individual user, "I", has to be put in the center of service provisioning. In this article, we report the work developed by the Working Group 2 of the Wireless World Research Forum on a service infrastructure framework for the future wireless world. Major service capabilities such as personalization, ambient awareness, and adaptability are described along with a reference model focusing in I-centric communication.

Method for supporting scalable and reliable multicast in tdma/tdd systems using feedback suppression techniques

Abstract: A method supports scalable and reliable multicast in a wireless network with a large bandwidth-delay product. In this method, acknowledgement packets from different receivers experiencing the same number of data packets lost are assigned the same time slots. This method can be combined with other loss recovery techniques, such as forward error correction (FEC) recovery, proactive protection, feedback suppression and collision detection. Scalability is achieved as bandwidth usage relates only to the number of packets transmitted, rather than the number of receivers.

Method and apparatus for resource sharing over handset terminals

Abstract: A mechanism and supporting apparatus to enable resource sharing among groups of users over mobile terminals. The system presented leverages the carrier infrastructure to simplify the requirements at the terminals, and describes a graphical user interface binding mechanism that allows developing generic graphical users interfaces that can be customized to heterogeneous devices at run-time.

Fast authentication methods for handovers between IEEE 802.11 wireless LANs

Abstract: Improving authentication delay is a key issue for achieving seamless handovers across networks and domains. This paper presents an overview of fast authentication methods when roaming within or across IEEE 802.11 Wireless-LANs. Besides this overview, the paper analyses the applicability of IEEE 802.11f and Seamoby solutions to enable fast authentication for inter-domain handovers. The paper proposes a number of possible changes to these solutions (typically in terms of network architectures and/or required trust relationships) for inter-domain operation. In addition, the paper identifies the crucial research issues therein. Possible solutions and directions for future research include: update to security infrastructure, inter-layer communication and discovery of appropriate networks.

Domain-specific Web search with keyword spices

Abstract: Domain-specific Web search engines are effective tools for reducing the difficulty experienced when acquiring information from the Web. Existing methods for building domain-specific Web search engines require human expertise or specific facilities. However, we can build a domain-specific search engine simply by adding domain-specific keywords, called "keyword spices," to the user's input query and forwarding it to a general-purpose Web search engine. Keyword spices can be effectively discovered from Web documents using machine learning technologies. The paper describes domain-specific Web search engines that use keyword spices for locating recipes, restaurants, and used cars.

Likelihood function for QRM-MLD suitable for soft-decision turbo decoding and its performance for OFCDM MIMO multiplexing in multipath fading channel

Abstract: This paper proposes likelihood function generation of complexity-reduced maximum likelihood detection with QR decomposition and M-algorithm (QRM-MLD) suitable for soft-decision turbo decoding and investigates the throughput performance using QRM-MLD with the proposed likelihood function in multipath Rayleigh fading channels for orthogonal frequency and code division multiplexing (OFCDM) with multiple-input multiple-output (MIMO) multiplexing Simulation results show that by using the proposed likelihood function generation scheme for soft-decision turbo decoding following QRM-MLD in 4-by-4 MIMO multiplexing, the required average received signal energy per bit-to-noise power spectrum density ratio (E/sub b//N/sub o/) at the average block error rate (BLER) of 10/sup -2/ at a 1-Gbps data rate is significantly reduced compared to that using hard-decision decoding in OFCDM access with 16 QAM modulation, the coding rate of 8/9, and 8-code multiplexing with a spreading factor of 8 assuming a 100-MHz bandwidth Furthermore, we show that by employing QRM-MLD associated with soft-decision turbo decoding for 4-by-4 MIMO multiplexing, the throughput values of 500 Mbps and 1 Gbps are achieved at the average received E/sub b//N/sub o/ of approximately 45 and 93 dB by QPSK with the coding rate of R = 8/9 and 16 QAM with R = 8/9, respectively, for OFCDM access assuming a 100-MHz bandwidth in a twelve-path Rayleigh fading channel

High-efficiency linear power amplifier

Abstract: A transmission signal and a pilot signal are predistorted by a digital predistorter 13 by use of a power-series model, and the predistorted output is converted by a digital-analog converter 14 to an analog signal. The analog signal is up converted by a frequency converter 15 to an RF-band signal, which is transmitted after being power-amplified by a Doherty amplifier 16. The pilot signal is extracted by a pilot signal extractor 17 from the output from the Doherty amplifier, and the extracted pilot signal is down converted by a frequency converter 18 to a baseband signal. The baseband pilot signal is converted by an analog-digital converter 19 to a digital pilot signal. A control part 21 detects an odd-order distortion component from the digital pilot signal, and based on the detected result, controls parameters of the digital predistorter.

Inter frame coding with template matching spatio-temporal prediction

Abstract: A new algorithm is proposed for predicting pixels for inter frame coding without side information. There are many approaches in the past that exploited either spatial or temporal correlations for generating prediction signals of an image in a block-by-block basis. Our method proposed in this paper exploits both spatial and temporal correlations at once to predict the pixels to be encoded. The prediction is achieved by using a template matching mechanism, with reference to previously reconstructed groups of pixels in the same frame or adjacent frames, to fill in the pixels of target regions of a frame. This process is conducted at both the encoder and decoder, and hence allows the decoder to produce the same predictor as the encoder does without any side information. Our coder uses the proposed prediction in addition to conventional motion compensation means. Simulation results show that our approach achieves up to 11.14% of improvements at the same PSNR over a codec which uses conventional block-based motion compensation.

Roam, a seamless application framework

Abstract: One of the biggest challenges in future application development is device heterogeneity. In the future, we expect to see a rich variety of computing devices that can run applications. These devices have different capabilities in processors, memory, networking, screen sizes, input methods, and software libraries. We also expect that future users are likely to own many types of devices. Depending on users' changing situations and environments, they may choose to switch from one type of device to another that brings the best combination of application functionality and device mobility (size, weight, etc.). Based on this scenario, we have designed and implemented a seamless application framework called the Roam system that can both assist developers to build multiplatform applications that can run on heterogeneous devices and allow a user to move/migrate a running application among heterogeneous devices in an effortless manner. The Roam system is based on partitioning of an application into components and it automatically selects the most appropriate adaptation strategy at the component level for a target platform. To evaluate our system, we have created several multi-platform Roam applications including a Chess game, a Connect4 game, and a shopping aid application. We also provide measurements on application performance and describe our experience with application development in the Roam system. Our experience shows that it is relatively easy to port existing applications to the Roam system and runtime application migration latency is within a few seconds and acceptable to most non-real-time applications.

Mobile communication terminal

Abstract: A mobile communication terminal includes an interference rejection combining processor for obtaining a received signal vector with regard to each of multiple resource elements and for calculating receiving weights so as to suppress influence to a desired beam of electric wave sent from the desired base station by other beams, on the basis of the received signal vectors; a non-interference-rejection receiving weight calculator for calculating receiving weights so as not to suppress influence to the desired beam by other beams; a signal separator for separating a signal destined for the mobile communication terminal from signals destined for other mobile communication terminals; and an interference rejection combining determiner for determining whether the receiving weights to suppress influence by other beams or the receiving weights calculated by the non-interference-rejection receiving weight calculator should be used for signal separation by the signal separator, on the basis of an index representing a relationship between reception quality of a desired downlink transmission signal and reception quality of an interfering signal.

Input key and input apparatus

Abstract: An input apparatus, which has at least one input key 10 assigned a plurality of information items to be inputted, is provided with a push detector 36 for detecting a push on the input key 10; a direction detector 38 for detecting a strain occurring in the input key 10 when the push is detected, and for thereby detecting a direction of a force exerted on the input key 10; and a symbol determiner 40 for determining an input information item, based on the detected direction.

Method and apparatus for location estimation using region of confidence filtering

Abstract: A method for location estimation employs filtering in both the radio signal domain and the space domain separately. The method filters raw values of the run-time radio signal measurements to reject distorted inputs. A region of confidence (RoC) is formed according to certain algorithms. Only location estimates falling within the RoC are considered for further processing. The location estimate candidates filtered by the RoC are put in a number of time-indexed bins. Each of the bins contains location estimate candidates obtained at similar times. A shortest route connecting a candidate from each bin is calculated to further improve the accuracy of the location estimation.

Method and apparatus for quality of service determination

Abstract: A method of estimating bandwidth capacity, available bandwidth and utilization along a path in an IP network is disclosed. ICMP time-stamp requests are sent from a source host on the edge or inside the network to all routers on the end-to-end path to a desired destination. Differences between time-stamp values are used as indicators of QoS service at each router. The collected measurements are then processed at the sending host to infer QoS parameters in terms of path capacity in bit/sec, available bandwidth in bits/sec, individual link utilization and congestion at each router. These parameters can be combined to infer the QoS service in terms of bandwidth on the end-to-end path.

Radio communication system and radio communication method

Abstract: A radio communication system for carrying out communications between radio stations by modulating a plurality of signal sequences to be transmitted and received into at least one frequency channel assigned to each of a plurality of cells is formed by a channel mapping means for rearranging for each cell a plurality of frequency channels assigned with respect to each cell, and newly assigning particular frequency channels as a transmission and reception band of said signal sequences, and a bandwidth control means for controlling a bandwidth of said assigned frequency channel according to a propagation state of said assigned frequency channel

Image encoding apparatus, image encoding method, image encoding program, image decoding apparatus, image decoding method, and image decoding program

Abstract: The image encoding apparatus of one embodiment of the present invention comprises a coding mode determination unit, a prediction image generation unit, a storage unit, and an encoding unit. The coding mode determination unit determines a coding mode relating to which of the first image prediction processing or second image prediction processing is used for generating prediction image of a partial area of input images. The prediction image generation unit extracts the prediction assist information by the first image prediction processing and generates a prediction image based on the prediction assist information. The storage unit stores the reproduced image that is based on the prediction image. The encoding unit generates a bit stream comprising data obtained by encoding the coding mode information and prediction assist information.

Apparatus and method for reading and decoding information contained in a barcode

Abstract: An image output device inputs content information, generates a barcode by encoding input content information, and outputs print data so that a sign visually indicating a property of the content information is printed adjacent to the generated barcode or by superimposing the sign on the generated barcode.

Fast active scanning wireless network apparatus and method

Abstract: In a fast active scanning wireless network apparatus and method for quick determination of available access points (20), information about a candidate set of available access points (20) is obtained, and a candidate access point is identified from the candidate set. A mobile station (10) then queries the candidate access point with a probe request that designates the candidate access point as a sole responder. The probe request prevents other access points from contending for the medium of communication between the mobile station and the designated sole responder access point by excluding the attempt by other access points (20) to transmit probe responses. The apparatus and method thus increases the probability of a fast and successful probe request from the mobile station and subsequent response from the designated access point (20). The designated access point may also respond with a probe response of high priority, preventing intervention of communication.

End-to-end QoS provisioning in mobile heterogeneous networks

Abstract: The remarkable advances in information technologies bring a heterogeneous environment for mobile users and service providers. This heterogeneity exists in wireless access technologies, networks, user terminals, applications, service providers, and so on. The ability to provide seamless and adaptive quality of service in such a heterogeneous environment is key to the success of next-generation wireless communications systems. There has been a considerable amount of QoS research recently. However, the main part of this research has been in the context of individual architectural components, and much less progress has been made in addressing the issue of an overall QoS architecture for the mobile Internet. This article first summarizes the state-of-the-art QoS techniques and standardization activities, then examines in detail important challenges in building a ubiquitous QoS framework over the heterogeneous environment, and finally proposes a QoS framework integrating a three-plane network infrastructure and a unified terminal cross-layer adaptation platform to provide seamless support for future applications.

Radio repeater and radio relay transmission method

Abstract: A radio repeater including at least first and second relay systems, each including a reception antenna configured to receive a radio signal, a loop interference suppressor, connected to the reception antenna, configured to suppress a loop interference signal in the received radio signal from said reception antenna, an amplifier configured to amplify the loop interference-suppressed radio signal from the loop interference suppressors, and a transmission antenna having a polarization characteristic, which is orthogonal to a polarization characteristic of said reception antenna, configured to transmit the output of said amplifier.

Pitfalls of OWL-S: a practical semantic web use case

Abstract: OWL-S is a combined effort of the Semantic Web and the Web Service community to facilitate an intelligent service provisioning on the Semantic Web. The vision of OWL-S includes automatic service discovery, invocation, composition, orchestration and monitoring of Web-Services through their semantic descriptions. In this paper, we investigate the practical applicability of the current OWL-S specification and show that, in spite of the large momentum of OWL-S, significantly more work needs to be done before the vision of truly intelligent Semantic Web Services can become true. We therefore study the case of an autonomous travel agent that helps users with online hotel arrangements. The aim of our work is twofold: on the one side, we show step-by-step how a prototypical implementation can be realized based on current semantic technologies around UDDI, WSDL, and SOAP. On the other hand, we reveal pitfalls in the current version of OWL-S that severely limit its support for mechanizing service discovery, configuration, combination and automated execution. Throughout the paper, we present practical solutions and workarounds to existing OWL-S shortcomings and hope to therewith further stimulate the ongoing work on Semantic Web Services.

Secure intra- and inter-domain handover

Abstract: To achieve a secure and fast handover in a distributed mobile communication environment (10), the control functionality is lying at the borderline between wireless and wire-bound communication network elements, and it is proposed to, firstly, execute a mutual authentication between a mobile device (26) and a new access point (14) using security context information previously transmitted to the new access point. Then, after successful mutual authentication, a handover will be executed from the current access point (12) to the new access point (14).