Sökning: "flat fading"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden flat fading.

1. 1. On MIMO Systems and Adaptive Arrays for Wireless Communication : Analysis and Practical Aspects

   Författare :Mattias Wennström; Michael A. Jensen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Systemteknik; antenna array; calibration; MIMO system; flat fading; non-linear amplifier; switched parasitic antenna; analog beamformer; adaptive antenna testbed; Systemteknik; Systems engineering; Systemteknik; Signal Processing; signalbehandling;

   Sammanfattning : This thesis is concerned with the use of multiple antenna elements in wireless communication over frequency non-selective radio channels. Both measurement results and theoretical analysis are presented. New transmit strategies are derived and compared to existing transmit strategies, such as beamforming and space-time block coding (STBC). LÄS MER

3. 2. Interference Cancellation for DS/CDMA Systems in Flat Fading Channels

   Författare :Ann-Louise Johansson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; mixed modulation; direct-sequence code division multiple access DS CDMA ; multiuser detection.; multiple data rates; parallel channels; multicode; interference cancellation;

   Sammanfattning : This thesis investigates interference cancellation in direct-sequence codedivision multiple access (DS/CDMA) systems that support multiple data rates.Two approaches for implementing multiple data rates are considered. Oneis the use of mixed modulation. The second is the use of parallel channels. LÄS MER

4. 3. On Bit-Wise Decoders for Coded Modulation

   Författare :Mikhail Ivanov; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; bit-error probability; L-values; labeling; Gray code; coded modulation; log-likelihood ratio; maximum likelihood decoder; Additive white Gaussian noise; quadrature amplitude modulation.; interleaver; flat fading channel; pairwise error probability;

   Sammanfattning : Coded modulation is a technique that emerged as a response to the growing demand for high data rates. It was devised to achieve high spectral efficiency with high reliability, potentially approaching Shannon’s capacity. The main idea of coded modulation consists in combining error-correcting coding with higher-order modulation. LÄS MER

5. 4. Capacity of MIMO Dispersive Fading Channels and the Achievable Error Performance of OFDM Signals in Frequency Dispersive Fading Channels

   Författare :Djordje Jeremic; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : Communication over a single-input single-output (SISO) and a multiple-input multiple-output (MIMO) dispersive fading channel were studied in the context of the ergodic Shannon channel capacity and the achievable error performance. A major contribution to the study is the equivalent SISO and MIMO vector channel models, derived from the corresponding waveform channel models, using a complete orthonormal and finite set of eigenfunctions to represent the waveform channel's output. LÄS MER

7. 5. Efficient Digital Communication over the Time Continuous Rayleigh Fading Channel

   Författare :Ulf Hansson; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Frequency flat, fast Rayleigh fading may be considered the most critical disturbance in a wireless communication system. In its most general form, it is modeled as a multiplicative time continuous random (zero mean complex Gaussian) distortion of the transmitted signal. LÄS MER