158 research outputs found
Wireless digital point to multipoint link utilizing wideband CDMA
One of the proposed techniques for multiple access communications for the third generation is code division multiple access (CDMA). This has been shown to be a viable alternative to both TDMA and FDMA. While there does not appear to be a single multiple accessing technique that is superior to others in all situations, there are characteristics of CDMA that give it a distinct advantage over the other multiple access techniques. In CDMA each user is provided with an unique, orthogonal code. If these K codes are orthogonal and uncorrelated with each other, than K independent users can transmit at the same time and in the same radio bandwidth. The receivers decorrelate the information and regenerate the original transmitted signal. It must be noted that the term "Wideband CDMA" is used comparatively to the only existing commercial CDMA system, IS-95 which uses a spectral bandwidth of only 1.2288 MHz. This thesis examines and evaluates a good set of orthonormal codes (orthogonal and normalized to have equal power) and their application to providing accessing for a point to multipoint (PMP) stationary system. The correlation properties, design and constellation properties of these codes are investigated. The system model is then simulated using Systemview and then evaluated in terms of it's bit error rate, user capacity and Erlang with addition of users to the system
Identification of Technologies for Provision of Future Aeronautical Communications
This report describes the process, findings, and recommendations of the second of three phases of the Future Communications Study (FCS) technology investigation conducted by NASA Glenn Research Center and ITT Advanced Engineering & Sciences Division for the Federal Aviation Administration (FAA). The FCS is a collaborative research effort between the FAA and Eurocontrol to address frequency congestion and spectrum depletion for safety critical airground communications. The goal of the technology investigation is to identify technologies that can support the longterm aeronautical mobile communication operating concept. A derived set of evaluation criteria traceable to the operating concept document is presented. An adaptation of the analytical hierarchy process is described and recommended for selecting candidates for detailed evaluation. Evaluations of a subset of technologies brought forward from the prescreening process are provided. Five of those are identified as candidates with the highest potential for continental airspace solutions in L-band (P-34, W-CDMA, LDL, B-VHF, and E-TDMA). Additional technologies are identified as best performers in the unique environments of remote/oceanic airspace in the satellite bands (Inmarsat SBB and a custom satellite solution) and the airport flight domain in C-band (802.16e). Details of the evaluation criteria, channel models, and the technology evaluations are provided in appendixes
Multi-carrier CDMA using convolutional coding and interference cancellation
SIGLEAvailable from British Library Document Supply Centre-DSC:DXN016251 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Final report on the evaluation of RRM/CRRM algorithms
Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin
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