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Proceedings Paper

System design for OFDM systems with high-density constellations
Author(s): Jian Gu
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Paper Abstract

This paper addresses issues in designing OFDM systems with high-density constellations. To achieve high data throughput, many high-speed OFDM systems such as HiperLAN2 and IEEE 802.11a use high-density constellations such as 64QAM to reach up to 54Mbits/s over a 20 MHz frequency bandwidth. Compared with low-density constellation modulations, OFDM systems using M-QAM (M>=64) are very sensitive to analog circuits/components variations causing so-called I-Q imbalances. Moreover, for the purpose of high integration level and low cost, simple front-end radio/analog architectures such as direct conversion and low-IF are desirable but such architectures are even more sensitive to circuitry and component variation. We have developed a patent-pending technology called IQ-Balancing, which removes the adverse effect of I-Q imbalance and enables OFDM systems to have high tolerance to circuitry and component variations. With IQ-Balancing technology, direct conversion and low-IF architectures become very attractive for high-speed OFDM systems. Exploring further with IQ- balancing technology leads to a simple implementation of software Defined Radio (SDR).

Paper Details

Date Published: 18 October 2001
PDF: 10 pages
Proc. SPIE 4586, Wireless and Mobile Communications, (18 October 2001); doi: 10.1117/12.445226
Show Author Affiliations
Jian Gu, 4D Connect, Inc. (United States)


Published in SPIE Proceedings Vol. 4586:
Wireless and Mobile Communications
Hequan Wu; Jari Vaario, Editor(s)

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