Fuzzy Set Theory - And Its Applications, Third Edition is a textbook for courses in fuzzy set theory. It can also be used as an introduction to the subject. The character of a textbook is balanced with the dynamic nature of the research in the field by including many useful references to develop a deeper understanding among interested readers. The book updates the research agenda (which has witnessed profound and startling advances since its inception some 30 years ago) with chapters on possibility theory, fuzzy logic and approximate reasoning, expert systems, fuzzy control, fuzzy data analysis, decision making and fuzzy set models in operations research. All chapters have been updated. Exercises are included.

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Fuzzy Set Theory - and Its Applications

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Convex Analysisの二,三の進展について

It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

Handover is the mechanism that transfers an ongoing call from one cell to another as a user moves through the coverage area of a cellular system. As smaller cells are deployed to meet the demands for increased capacity, the number of cell boundary crossings increases. The author presents an overview of published work on handover performance and control and discusses current trends in handover research. He discusses investigations that are applicable to a single tier of cells. He focuses on macrocells, but includes a brief discussion on how things change as cell sizes shrink. By assuming an overlay of macrocells and microcells he summarizes issues and approaches unique to such systems.

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Trends in handover design

A location system is disclosed for wireless telecommunication infrastructures. The system is an end-to-end solution having one or more location systems for outputting requested locations of hand sets or mobile stations (MS) based on, e.g., AMPS, NAMPS, CDMA or TDMA communication standards, for processing both local mobile station location requests and more global mobile station location requests via, e.g., Internet communication between a distributed network of location systems. The system uses a plurality of mobile station locating technologies including those based on: (1) two-way TOA and TDOA; (2) home base stations and (3) distributed antenna provisioning. Further, the system can be modularly configured for use in location signaling environments ranging from urban, dense urban, suburban, rural, mountain to low traffic or isolated roadways. The system is useful for 911 emergency calls, tracking, routing, people and animal location including applications for confinement to and exclusion from certain areas.

Locating a mobile station and applications therefor

Indoor positioning systems (IPS) use sensors and communication technologies to locate objects in indoor environments. IPS are attracting scientific and enterprise interest because there is a big market opportunity for applying these technologies. There are many previous surveys on indoor positioning systems; however, most of them lack a solid classification scheme that would structurally map a wide field such as IPS, or omit several key technologies or have a limited perspective; finally, surveys rapidly become obsolete in an area as dynamic as IPS. The goal of this paper is to provide a technological perspective of indoor positioning systems, comprising a wide range of technologies and approaches. Further, we classify the existing approaches in a structure in order to guide the review and discussion of the different approaches. Finally, we present a comparison of indoor positioning approaches and present the evolution and trends that we foresee.

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Evolution of Indoor Positioning Technologies: A Survey

One method to increase capacity in mobile communications systems is to decrease the cell size or service area. However, due to this area reduction, a mobile will pass through more cells during a call. To maintain the reliability of the system, the success rate of call transfers must increase as the cell area diminishes, preventing a ping-pong effect. Hence new and better handoff algorithms must be developed. Fuzzy classifier schemes are proposed in this paper in order to select the base stations that will best serve mobiles in a typical cellular system. The performance of handoff algorithms based on different classification techniques is discussed and evaluated through digital simulation. The results show better cell definition than the conventional handoff approach. For large-variance propagation channels, a reduction in the handoff number can be achieved. The applicability of the proposed methodology is also discussed.

Handoff algorithms based on fuzzy classifiers

Pattern recognition algorithms are used to process the field strength intensities in order to select the base station which will serve the call. The algorithms are: the Isodata clustering algorithm and fuzzy classifiers based on membership functions. The performance and application of these algorithms, in a microcellular environment, are evaluated and discussed. >

Pattern recognition techniques in handoff and service area determination

The use of chaotic signals as generators of binary and multilevel sequences suitable for code division multiple access (CDMA) is proposed. The number of obtained sequences is found to be greater than the number of m-sequences of the same length. These new chaotic sequences are used as spreading codes in a CDMA system. Simulation results are presented and compared with those obtained for m-sequences in terms of BER performance.

Chaotic sequences for multiple access

This paper presents a genetic algorithm approach to solve the channel assignment problem in cellular telecommunication systems. The general purpose simple genetic algorithm as well as a hybrid genetic algorithm are proved to cope with a variety of channel demands in different cellular system scenarios. The hard interference requirements are also considered. The application of genetic algorithms is proposed as a system planning tool capable of producing a low call blocking assignment.

David Munoz-Rodriguez

Papers

Evolution of Indoor Positioning Technologies: A Survey

Handoff algorithms based on fuzzy classifiers

Pattern recognition techniques in handoff and service area determination

Chaotic sequences for multiple access

Channel assignment in cellular systems using genetic algorithms