Adaptive multilevel quadrature amplitude radio implementation in programmable logic
Date
2004-04-22
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Degree Level
Masters
Abstract
Emerging broadband wireless packet data networks are increasingly employing spectrally efficient modulation methods like Quadrature Amplitude Modulation (QAM) to increase the channel efficiency and maximize data throughput. Unfortunately, the performance of high level QAM modulations in the wireless channel is sensitive to channel imperfections and throughput is degraded significantly at low signal-to-noise
ratios due to bit errors and packet retransmission. To obtain a more “robust” physical
layer, broadband systems are employing multilevel QAM (M-QAM) to mitigate this reduction in throughput by adapting the QAM modulation level to maintain acceptable packet error rate (PER) performance in changing channel conditions.
This thesis presents an adaptive M-QAM modem hardware architecture, suitable for use as a modem core for programmable software defined radios (SDRs) and broadband wireless applications. The modem operates in “burst” mode, and can reliably synchronize to different QAM constellations “burst-by-burst”.
Two main improvements exploit commonality in the M-QAM constellations to minimize the redundant hardware required. First, the burst synchronization functions (carrier, clock, amplitude, and modulation level) operate reliably without prior knowledge of the QAM modulation level used in the burst. Second, a unique bit stuffing and shifting technique is employed which supports variable bit rate operation, while reducing the core signal processing functions to common hardware for all constellations. These features make this architecture especially attractive for implementation with Field Programmable Gate Arrays (FPGAs) and Application-Specific Integrated Circuits (ASICs); both of
which are becoming popular for highly integrated, cost-effective wireless transceivers.
Description
Keywords
Adaptive, M-QAM, QAM, FPGA, Programmable Logic, Modem, Radio
Citation
Degree
Master of Science (M.Sc.)
Department
Electrical Engineering
Program
Electrical Engineering