This paper presents the results on IF/baseband up/down direct digital conversion and multiple channel analysis/synthesis software defined radio modules which are implemented using high speed ADC, DAC and FPGA, for IS-95 code division multiple access (CDMA) systems. The implemented system can directly down-convert multiple channel IS-95 CDMA IF signals to the baseband, and selectively analyze specific channel signals based on polyphase analysis filter bank techniques. Moreover, the analyzed baseband signals of multiple channels can be directly up-converted and synthesized in the same system. We have deployed the implemented system in IS-95 CDMA optical digital repeaters for PCS applications.

A software antenna, which will be a key device realizing flexible and highly reliable wireless communications systems, is inherently matched with software defined radios (SDR). In this paper, first, key technologies on the software antenna are introduced. The technologies contain i) how to recognize the radio environment, ii) how to determine the optimum adaptive signal processing algorithm, and iii) how to reconfigure the digital beamforming circuit. Then, an image of a software antenna with reconfigurable eigenvector-beamspace configuration is presented. Finally, by assuming various propagation conditions, performance of the software antenna in terms of algorithm diversity is demonstrated.

It is expected that software receivers will be widely available for radio communication, broadcasting and radio monitoring applications because they are able to be equipped with multimode, multirate and multiband functions in a single hardware platform. This paper describes the basic techniques required for software receivers for both hardware and software. The evaluation items and methods were studied and some evaluations done with an experimental software receiver model fabricated for radio monitoring applications. Future concepts in radio communication, broadcasting and radio monitoring applications where software receivers are thought to be suitable, were studied, and problems for realization identified.

A broadband and flexible receiver architecture is investigated for the handheld software defined radio (SDR). The proposed SDR architecture is based on the direct conversion and low intermediate frequency (low-IF) principle with digital channel filtering, which provides the receiver with flexibility for the multi-standard application. This architecture also enables analog-to-digital converter activating essentially in baseband or low frequency so that the clock jitter, which serves as an important subject in the well-known IF sampling method, can be reduced. Basic performance of the proposed architecture has been confirmed by the experimental model.

In this paper, a new configuration method of multimode software radio system by parameter controlled and telecommunication component block embedded digital signal processing hardware (DSPH) is proposed for the future flexible multimedia communications. In this method, in advance, basic telecommunication component blocks are implemented in the DSPH like DSP and FPGA. And, external parameters, which are simple but important information, change the specification of each block. This proposed method has the following features: i) People need to have only one mobile handset and select communication services as they like. ii) The volume of download software is reduced drastically in comparison with conventional full-download-type software radio system. iii) Since important component blocks have already been implemented into the DSPH except for some external parameters in advance, the know-how related to the implementation of DSPH never leak out. In this paper, we evaluate the effectiveness of the proposed configuration method by using computer simulation and developed experimental prototype and comparing with full-download-type software radio system from the viewpoint of the volume of download software. Finally, we introduce several new software radio systems by using the proposed configuration method.

In recent years, the concept of the software radio has been put forward by the international communication society. It is well known that software radio will play an important role in third generation wireless communication systems. But until now there is not an acceptable concept of software radio. How to make software radio be applicable authentically, and how to develop its ascendancy? This paper introduces some new ideas about the key issues of software radio, including software radio architecture and its hardware platform, and it focuses on the design considerations of the hardware platform. Conventional software radio systems use pipeline architecture, which is not scalable and cannot fulfill the inherent requirements of software radios. In this paper a new layer structure of the hardware platform is proposed. It is an open architecture with flexibility and scalability. Then three schemes for hardware platform realization are introduced: bus architecture, switched network architecture, and fat tree architecture. An extensive analysis on advantages and disadvantages of each architecture is given. Then an application example is proposed. The switched network architecture is applied in the cellular wireless communication systems. The basestation is divided into four components according to their functions: antenna, IF, baseband, and control, which are connected by the ATM network. We call this virtualization of wireless communication systems. This will bring great benefits such as fast handoff, easily realization of different macrodiversity algorithm.

Software radio has emerged as a focus of both academic research and commercial development for future wireless systems. This paper briefly reviews the foundation concepts of the software radio. It then characterizes the tradeoffs among core software-radio technologies. Object-oriented analysis leads to the definition of the radio reference platform and the related layered object-oriented architecture supporting simultaneous hardware and software evolution. Research issues include layering, tunneling, virtual machines and intelligent agents.

This paper reports the prehistory of software defined radio (SDR) studies in Japan. In 1999, a boom in the field of SDR started in Japan, and this year an ARIB study group completed its final report on SDR. SDR is a recently proposed technology concept and has attracted the attention of many communication engineering researchers. SDR will become one of the most important technologies in advanced communication, broadcasting and intelligent transportation systems on the 21st century. Although SDR has several attractive features, there are also many design issues to be solved. In this work we have examined these issues and discussed a new design methodology for wireless receivers in the SDR era.

An architecture for a digital-to-RF converter for a software defined radio (SDR) transmitter is proposed. The ideal hardware architecture for an SDR is a digital-signal to RF-signal direct conversion transmitter. However no conventional digital-to-analog converter (DAC) has converted over 1-GHz RF signal with enough resolution, in the present condition. In this paper, a digital-to-RF direct converter architecture using a ΔΣ modulation technique is proposed for the amplitude-phase modulated signal. The experimental results show that the proposed direct converter outputs a sufficiently accurate signal.

A new type of Meteor Burst Communication (MBC) network is developed. Each unit of the network is based on a DSP board running a modem software. All the fundamental blocks and functions of a modem are implemented in software. Unlike hardware modems, this software modem has flexibility of system configuration and operation. The system implements adaptability in terms of modulation type (number of phases in MPSK) using a unique dynamic channel estimation scheme appropriate for MBC channel. An MBC network protocol is implemented within the modem software. Some preliminary experiments were carried out for differential BPSK and differential QPSK modulations over a practical meteor burst link, and the results are presented.

Software radio base and personal station prototypes are proposed and implemented. The prototypes are composed of RF/IF, A/D and D/A, pre- and post-processors, CPU, and DSP parts. System software is partitioned into CPU program and DSP program to use processor resources effectively. They support various air interfaces, some of which are equivalent to the 384 kbit/s transmission rate PHS (personal handy phone system) and a 96 kbit/s transmission rate system. The base station can also be used as a communication bridge between two systems. In order to ease IF filter requirements, the zero-stuff method is employed. Basic transmission and receiving performances are evaluated in an experiment and their results agree well with those expected.

Interference suppression is one of the important functions for mobile communications and software radio. First, this paper shows a new type of interference suppression method by P-RCE (Probability-Restricted Coulomb Energy) which is applicable to mobile communications and software radio. P-RCE is one of the neural networks and mainly used in the field of pattern classification. Secondly, this paper presents several characteristics of this method. For example, it is found from our studies that good suppression effects can be performed even when the interference signals exist closely adjacent to the desired signal and/or total number of signals is more than that of the antenna elements. Next, this paper discusses two types of improvement of processing speed for new suppression method. One is the setting up the learning and non-learning intervals, and the other is the restriction of the number of prototype cells. According to the results, fairly good improvement is realized.

We study the evolution and the dominance of the service based functions and their distinguishing features. As the service industry matures, its functions bear many similarities with the software development processes, such as intense man-machine interaction, knowledge intensive activities, flexibility in the organization, control and execution of tasks. In this paper we discuss wide range of interconnected topics, emphasizing the multi-faceted nature of service functions. These include the evolution of service industry and their products, the consumerization of high tech products based on their large-scale adoption and the consequent creation of implicit requirements; the technology transfer processes; the error proneness due to intense and prolonged interaction with computers and some methods of mitigating error incidence. We argue that by proper 'humanization and personalization' of interactive systems and by the use of teams of computer supported professionals, we can prevent such errors. We discuss some useful team types, models of their behavior and their control aspects. As the cost of communications shrinks like due to the Internet, we conclude that a fully decentralized system control provides a flat, flexible, and fair and friction-free organization for large team based service systems.

In this paper, a program generator for communication protocol software will be presented. Our program generator takes an extended finite state machine as a domain model and generates a group of C++ classes needed for an implementation. For each state of the FSM, a C++ class is generated, where the interface events are implemented as member functions of the corresponding state object. Protocol data units (PDUs) are embedded as Message objects and specified in the same way as packet filter and is interpreted to generate necessary PDU definition statements and PDU manipulation statements. Also, protocol objects from different layers can be linked together by using an organization model, where a protocol entity is invoked by its upper layer entity or lower layer entity by member function calls.

In this paper, we develop an effective smoothing technique to estimate the optimal software release schedule which minimizes the total software cost. The optimal software release problem is essentially reduced to a statistical estimation problem for the software failure rate, but the resulting estimator based on both the fault-detection time data observed in testing phase and its estimate in future is discontinuous and does not always function well for determining the optimal release schedule. We estimate the smoothed software failure rate using the usual quadratic programming approach and generate the optimal software release schedule with higher accuracy.

In this paper, we construct a software availability model considering the number of restoration actions. We correlate the failure and restoration characteristics of the software system with the cumulative number of corrected faults. Furthermore, we consider an imperfect debugging environment where the detected faults are not always corrected and removed from the system. The time-dependent behavior of the system alternating between up and down states is described by a Markov process. From this model, we can derive quantitative measures for software availability assessment considering the number of restoration actions. Finally, we show numerical examples of software availability analysis.

In a software maintenance phase, since quality assurance engineers frequently only change source codes, the consistency between the source codes and their specification documents cannot be kept. In this paper we propose a supporting technique for changing specification documents automatically so that the specifications can be consistent with the source codes. In our technique, we represent a program with multiple graphs and we consider the changes on programs as the modification of the graphs. The modification of the graphs is formalized with a sequence of the operation on the graphs. We design the rules of how to relate the operations on program graphs to the operations on graphs that represent specification documents. By applying these rules, we can detect what modification and which parts of the specification document should be made to maintain the consistency between the specification and the program, when the program is modified.

This paper presents a model for the naming, packing, version control, storage, and retrieval of software assets. The naming and version control schemes are based on content-derived coding of the asset body. The name-to-asset mapping can be fixed or be varying with time. The packing scheme is designed so that the asset integrity verification and authentication information is made an intrinsic part of the packed asset. A comparison with an existing naming and version control scheme is given. The storage and retrieval scheme is a unification of four most commonly used methods, namely the enumerative method, the keyword-based method, the faceted method, and the text-based method. This unification makes it possible for the users to access heterogeneous repositories (with different storage and retrieval methods) simultaneously, using the same tool set and query syntax. The degradation functions technique is used to automatically broaden queries. A demonstrative retrieval tool is described to show how the unification of methods is done at the user interface level.

The Capability Maturity Model (CMM) proposed by the Software Engineering Institute (SEI) of Carnegie Mellon University (CMU) is an effective framework for software process improvement (SPI) because it can increase development productivity and improve software quality for many software development companies. However, the CMM only indicates 'what' needs to be improved, it does not indicate 'how to' perform software process improvement activities (SPIA). In this paper we describe a Software Process Improvement support System (SPIS) that does indicate 'how to' perform SPIA. It is designed to be used mainly for internal SPIA by software development companies and their project teams. The SPIS is composed of seven support tools and promotes SPIA. The tools include a specific capability maturity model (SCMM), rules for assessing a company's maturity level, and an assessor qualification system for organizing the assessment team. These tools were extracted deductively from our experience and have proved to be effective when used for the SPIA at our company. (R): CMM is registered trademarks in the U. S. Patent and Trademark Office. SM: CMM is a service mark of Carnegie Mellon University.

Software Composition is one of the major concerns in component based software development (CBSD). In this paper, we present a formal approach to construct software systems from requirements models using available components. We focus on the knowledge resides in the requirements and the components in order to deal with those heterogeneous concepts. This approach consists of three steps. The first step is selecting adaptable components to the requirements model. The requirements and the components are transformed into the form of Σ algebra, and the component adaptability is evaluated by Σ homomorphism. Rough Set Theory (RST) is used to make carriers of two Σ algebras common, which are derived from the requirements and the components. The second step is identifying the control structure of the requirements. Decision tables are used for representing the knowledge on the requirements, and RST is used to optimize the control structure. The third step is to implement the control structure as glue codes which would perform the components appropriately. This approach mainly focuses on enterprise back-office applications in this paper, however, it can be easily applied to other domains, since it assumes the requirements to be expressed in Colored Petri Nets (CPN), and CPN can express various problem domains other than enterprise back-office applications.