Mobile telephony

About: Mobile telephony is a research topic. Over the lifetime, 38008 publications have been published within this topic receiving 553646 citations.

Wireless Digital Communications: Modulation and Spread Spectrum Applications

Abstract: 1. Introduction to Wireless, Cellular, Digital, PCS-Mobile Radio. Summary. Mobile Communications: Evolution and Fundamentals. International Mobile Satellite, Low Earth Orbit, and Medium Altitude Orbit Satellite Frequency Bands. Personal Communication Systems (PCS) Universal Digital PCS. Standards: The Importance of National and International Standardization. Mobile Personal Computers (PC) and Personal Communication Systems (PCS). U.S. and World Cellular Markets. 2. Speech Coding for Wireless Systems Applications. Introduction to Digital Signal Processing (DSP) Techniques in Wireless Telephone and Broadcast Systems. Speech Coding Techniques for Audio and Voice. American and European Speech Codes. 3. Radio Propagation and Cellular Engineering Concepts. Introduction. Fundamental Radio Propagation and System Concepts. Fundamentals of Antenna Gain. Propagation Characteristics. Models of Multipath-Faded Radio Signals. Instrumentation and Measurements for Laboratory and Field Tests. Delay-Spread Field Measurement Results. Industry Standards for Propagation Models. Problems. 4. Digital Modulation-Demodulation (MODEM) Techniques. Introduction. Baseband Transmission Systems. Modem Principles and Architectures. Interference. Definitions and Performance of Spectral and Power Efficiency. Performance in Complex Interference-Controlled Mobile Systems. Advantages of Coherent Demodulation over Noncoherent Systems. Advanced Modulation Methods. Adaptive Equalization for Frequency- Selective Faded and Delay-Spread Systems. Synchronization of Burst Demodulators: Carrier Recovery and Symbol Timing Recovery. Problems. 5. Coding: Error Correction and Detection. Error Control Requirements. Interleaving. Block Coding. Convolutional Coding. Price of Error Correction: Reduced Throughput? Word-Error Rate, False-Alarm Rate, and Probability of Bit Error. Repetition Transmission and Majority-Voting System: Concepts and Performance. Automatic Repeat Request. 6. Spread-Spectrum Systems. Introduction. Fundamental Concepts of Spread-Spectrum Systems. Pseudo-noise Sequences. Performance of Direct- Sequence Spread-Spectrum Systems. Code Division Multiple Access (CDMA): Direct-Sequence (DS) and Frequency-Hopped (FH) Spread-Spectrum Systems. Frequency-Hopping Spread-Spectrum Systems. Synchronization of Spread-Spectrum Systems. Spread- Spectrum Applications in Cellular, PCS, and Mobile Communications. Problems. 7. Diversity Techniques for Mobile-Wireless Radio Systems. Introduction. Concepts of Diversity Branch and Signal Paths. Combining and Switching Methods. Carrier-to-Noise and Carrier-to-Interference Ratio Performance Improvements. Average Pe Performance Improvement. Summary. Problems. 8. Personal Mobile Satellite Communications. Introduction. Integration of GEO, LEO, and MEO Satellite and Terrestrial Mobile Systems. Personal Satellite Communications Programs. 9. Cellular and Wireless Systems Engineering. Introduction. Access Methods: TDMA (TDD and FDMA) Spread-Spectrum Frequency-Hopping Direct-Sequence CDMA and CSMA. Comparison of Linearly Amplified BPSK, DQPS and DQPSK and Nonlinearly Amplified (NLA) GMSK, GFSK, 4-FM, and FQPSK Radio Equipment (Coherent and Noncoherent). Radio Link Design of Digital Wireless Cellular Systems. Spectrum Utilization in Digital Wireless Mobile Systems. Capacity and Throughput (Message Delay) Study and Comparison of GMSK, GFSK, and FQPSK Modulated Wireless Systems. Time Division Multiple Access Wireless Cellular Systems. Code Division Multiple Access Spread-Spectrum Digital Cellular IS-95 System. Standards for Wireless Local Area Networks. Wireless Personal Communications. Problems. Appendices. Statistical Communication Theory: Terms, Definitions, and Concepts. Software Package of CREATE-1 (Disk Enclosed). Dr. Feher Associates Patented Filter, Digital Signal Processing, and Correlated Modulation/RF Amplification Means: GMSK, GFSK, FBPSK and FQPSK Implementations of Digcom, Inc. Licensed Technologies. Abbreviations and Acronyms. Bibliography. Index.

Cooperative Edge Caching in User-Centric Clustered Mobile Networks

Abstract: With files proactively stored at base stations (BSs), mobile edge caching enables direct content delivery without remote file fetching, which can reduce the end-to-end delay while relieving backhaul pressure. To effectively utilize the limited cache size in practice, cooperative caching can be leveraged to exploit caching diversity, by allowing users served by multiple base stations under the emerging user-centric network architecture. This paper explores delay-optimal cooperative edge caching in large-scale user-centric mobile networks, where the content placement and cluster size are optimized based on the stochastic information of network topology, traffic distribution, channel quality, and file popularity. Specifically, a greedy content placement algorithm is proposed based on the optimal bandwidth allocation, which can achieve $(1-{1/e})$ -optimality with linear computational complexity. In addition, the optimal user-centric cluster size is studied, and a condition constraining the maximal cluster size is presented in explicit form, which reflects the tradeoff between caching diversity and spectrum efficiency. Extensive simulations are conducted for analysis validation and performance evaluation. Numerical results demonstrate that the proposed greedy content placement algorithm can reduce the average file transmission delay up to 45 percent compared with the non-cooperative and hit-ratio-maximal schemes. Furthermore, the optimal clustering is also discussed considering the influences of different system parameters.

Multiple web-based content category searching in mobile search application

Abstract: In embodiments of the present invention improved capabilities are described for multiple web-based content category searching for web content on a mobile communication facility comprising capturing speech presented by a user using a resident capture facility on the mobile communication facility; transmitting at least a portion of the captured speech as data through a wireless communication facility to a speech recognition facility; generating speech-to-text results for the captured speech utilizing the speech recognition facility; and transmitting the text results and a plurality of formatting rules specifying how search text may be used to form a query for a search capability on the mobile communications facility, wherein each formatting rule is associated with a category of content to be searched.

System for advertising on a network by displaying guide codes

Abstract: An advertising method on a network comprises displaying a guide code corresponding to a network address of an advertisement object and allowing a user to transmit said guide code. Moreover, an advertisement method on a network for additionally allows a user to purchase an advertised good or service by transmitting a guide code via a mobile telephone and charging the cost of the purchase to a calling account of the mobile telephone. Also, the present invention has particular application as an advertisement guide system and method using guide codes, wherein users are able to simply and conveniently recollect Internet homepage addresses of advertisers of advertisements made through various advertisement media, using voice or character mailboxes or electronic mails of mobile communication terminals, without having to write down the Internet homepage addresses on a memo paper. The invention further relates to a simple reservation, purchase and settlement system that takes advantage of the rapid increase in the number of users of mobile communication terminals.

Self-Organization Routing Protocol Supporting Mobile Nodes for Wireless Sensor Network

Abstract: In mobility-centric environments, wireless sensor networks are designed to accommodate energy efficiency, dynamic self-organization and mobility. In typical applications of wireless sensor networks, fixed sensor nodes are mixed with mobile sensor nodes in 'hot areas'. Also, as they move, network topology needs to be reconstructed by reacting upon the mobility of sensor nodes quickly. In this paper we proposed an improved protocol called "LEACH-Mobile" for mobile nodes to declare the membership of a cluster as they move, and to confirm whether a mobile sensor node is able to communicate with a specific cluster head within a time slot allocated in TDMA schedule. The LEACH-Mobile protocol achieved definite improvement in data transfer success rate as mobile nodes increased compared to the non-mobility centric LEACH protocol.