Telcordia Technologies

About: Telcordia Technologies is a based out in . It is known for research contribution in the topics: Network packet & Node (networking). The organization has 3097 authors who have published 4737 publications receiving 237882 citations.

Origin of the 110-K superconducting transition in the Bi-Sr-Ca-Cu-O system.

Abstract: Superconducting critical transitions with an onset at 112 K and zero resistance at 107 K are obtained within the Bi-Sr-Ca-Cu-O system. The synthesis and formation of the 110-K superconducting phase using the 85-K material as a precursor is explained. The 110-K phase grows from the 85-K phase such that the resulting faceted crystal (a pseudomorph) can contain some of the 85-K phase in the core. With such a microstructure our magnetic data can be simply explained. A major structural difference between the 85- and 110-K materials is that the 85-K material can grow (relatively) large single crystals having long-range order whereas the 110-K material has only intermediate-range order (cryptocrystalline) of about 100--200 A.

Carrier confinement and special crystallite dimensions in layered semiconductor colloids.

Abstract: Microcrystallites of the layered semiconductor ${\mathrm{PbI}}_{2}$ were prepared in colloidal form and examined by transmission electron microscopy and optical absorption. The crystallites have lateral dimensions grouped around 12, 18, and 29 A\r{} corresponding to close-packed clusters with bulk ${\mathrm{PbI}}_{2}$ symmetry. Blue-shifted absorption features can be explained by carrier confinement in these differently sized crystallites, each a single layer (\ensuremath{\sim}7 A\r{}) thick.

Applications of Cdma in Wireless/ Personal Communications

Abstract: 1. Introduction to Code-Division Multiple Access Technology. Introduction. Trends in Wireless Communications. Market Trends for Wireless Communications. Needs of Digital Technologies for Wireless Communications. Elements of a Wireless Network. Digital Technologies. Spread Spectrum Technology. Summary. References. 2. Spread Spectrum Systems. Introduction. Types of Techniques Used for Spread Spectrum (SS). The Concept of the Spread Spectrum System. The Performance of Direct Sequence Spread Spectrum. The Direct Sequence Spread Spectrum System. Coherent Binary Phase-Shift Keying. Quadrature Phase-Shift Keying. The Performance of a Code-Division Multiple Access System. Pseudorandom Noise Sequences. Properties of a Maximal Length Pseudorandom Sequence. Autocorrelation. Cross-correlation. Orthogonal Functions. TIA IS-95 CDMA System. Downlink. Uplink (Reverse). Summary. References. 3. CDMA Standards. Introduction. Background. Layering Concepts. Call Processing. Mobile Station Initialization State. Mobile Station Idle State. System Access State. Mobile Station Control on the Traffic Channel State. Base Station Call States. Service Configuration and Negotiation. Concept of System Identification and Network Identification. Registration. Wideband CDMA Standards. Summary. References. 4. System Architecture for Wireless Communications. Introduction. TR-45/TR-46 Reference Model. Elements of the Reference Model. Standardization of the MSC-BS Interface. Supported Architectural Configurations. Call Processing and Supplementary Services. Radio Resource Management. Mobility Management. Transmission Facilities Management. Services. Basic Services. Supplementary Services. Summary. References. 5. Physical Layer of CDMA. Introduction. Open Systems Interconnect Reference Model. Forward CDMA Channel and W-CDMA Channel. Pilot Channel. Sync Channel. Forward Paging Channel. Forward Traffic Channel. Modulator. The Reverse CDMA Channel. Reverse Access Channel. Reverse Traffic Channel. Reverse Channel Modulator. Channel Spacing and Frequency Tolerance. Power Control in CDMA. Modulation Parameters. Convolutional Encoding. Bit Repetition. Block Interleaving. Randomizing. Orthogonal Codes. 64-ary Orthogonal Modulation. Long Codes. Direct PN Spreading. Baseband Filtering. Synchronization of CDMA Signals. Summary. References. 6. Network and Data Link Layers of CDMA. Introduction. Forward CDMA Channel. Sync Channel. Paging Channel. Traffic Channel. Reverse CDMA Channel. Access Channel. Traffic Channel. Forward W-CDMA Channel. Layer-to-Layer Communications. Sync Channel. Paging Channel. Traffic Channel. Reverse W-CDMA Channel. Layer-to-Layer Communications. Access Channel. Traffic Channel. Summary. References. 7. Signaling Applications in the CDMA System. Introduction. End-to-End Operation of a Wireless System. Basic Services. Unique Challenge. Supplementary Services. Handoffs. Summary. References. 8. Voice Applications in the CDMA System. Introduction. Voice Encoding. Pulse Code Modulation. Adaptive Differential Pulse Code Modulation. Code-Excited Linear Predictor. Summary. References. 9. RF Engineering and Facilities Engineering. Introduction. Radio Design for a Cellular/PCS Network. Radio Link Design. Coverage Planning. Propagation Models. Modeling for the Outside Environment. Models for Indoor Environment. Link Budgets. Forward Direction. Reverse Direction. Dual-Mode CDMA Mobiles. The Transition from an Analog System to a Digital System. Overlay Design. Integrated Design. Partial CDMA Coverage, Integrated System. Facilities Engineering. Capacity of Forward Radio Channel. Design Considerations at the Boundary of a CDMA System. Summary. References. 10. Wireless Data. Introduction. Wireless Data Systems. Wide Area Wireless Data Systems. High-Speed Wireless Local Area Networks. WLAN Standards. IEEE 802.11. Wireless Information Networks Forum. High-Performance Radio Local Area Network. ARPA. Access Methods. Fixed-Assignment Access Methods. Random Access Methods. Error Control Schemes. The Data Services Standard for CMDA Cellular/Personal Communications Systems. Asynchronous Data and Group-3 Facsimile. Short Message Service. Packet Data Services for CDMA Cellular/Personal Communications Systems. Summary. References. 11. Management of CDMA Networks. Introduction. Management Goals for PCS Networks. Requirements for Management of PCNs. Telecommunication Management Network and Wireless Network Management. Functional Architecture. Physical Architecture. Quality of Service. Accounting Management. Billing Data Management. Data Message Handling and TMN. Security Management. Information-Gathering Mechanisms. Audit Trail Mechanism. Security Alarm Reporting Mechanisms. Configuration Management. Fault Management. Performance Management. Requirements on Types of Data. Measurement Administration Requirements. Requirement on Measurement Definition. Measurement Job Requirements. Performance Measurement Areas. Summary. References. 12. Interconnection Between Systems. Introduction. Interworking Issues. Dual-Mode Digital/AMPS Systems and Phones. Dual-Mode Digital Systems. Wireless Intelligent Networks. Summary. References. 13. Evolution of CDMA Technology for Wireless Communications. Introduction. Over-the-Air Service Provisioning. Improvement of Speech Coders. Interference Cancellation. Multiple Beam Adaptive Antenna Array. Improvements of Handoff Algorithms. Summary. References. A. Traffic Tables. B. List of Abbreviations and Acronyms. Index.

Voice performance in WLAN networks - an experimental study

Abstract: In this work, we measure wireless local area network (WLAN) voice performance and capacity. While most WLAN applications today are data centric, the growing popularity of Voice over IP (VoIP) applications and the escalating trend towards convergence with cellular networks will catalyze an increased mix of voice traffic. Since voice applications must compete with each other and with simultaneous data applications for WLAN bandwidth, quantifying voice performance and capacity in the presence of background data traffic is an important issue. We offer a practical investigation into the ability of 802.11b MAC layer to support simultaneous voice and data. We quantify VoIP capacity for standard WLAN networks, indicative of those already in the field, as well as evaluate the practical benefits of implementing backoff control and priority queuing at the access point. Conclusions are drawn based on an extensive set of real-world measurements conducted using off-the-shelf equipment in a commercial testbed.