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Charles G. Sodini. Edalat, Farinaz, 1979- Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science 2008-11-07T18:54:13Z 2008-11-07T18:54:13Z 2008 2008 http://hdl.handle.net/1721.1/43031 243604749 Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008. Includes bibliographical references (p. 153-159). The increasing demand for high speed wireless connectivity at low cost proposes new challenges for communication systems designers to implement solutions that increase the data rate by utilizing the limited radio resources more efficiently at a low additional complexity. Sub-carrier Adaptive Modulation and Coding (AMC) exploits the high frequency diversity in wideband Orthogonal Frequency Division Multiplexing (OFDM) channels to obtain higher data rates. While prior work has discussed the value of sub-carrier AMC from a theoretical perspective, this work presents the design and performance of a real-time sub-carrier AMC system. We describe our OFDM transceiver prototype, which implements real-time subcarrier AMC for a wideband wireless channel. We discuss how our design achieves accurate and consistent Signal-to-Noise Ratio (SNR) estimates, which are critical for the success of AMC. We compare the performance of sub-carrier AMC with a non-adaptive scheme that assigns the same modulation and channel coding to all sub-carriers that can support that modulation and coding for the target Bit Error Rate (BER). For a conservative comparison, we compare against the uniform modulation/coding assignment that achieves the highest data rate. Our experiments over the wireless channel show that for a target coded BER of 10-5, our system achieves average data rates of 308.3 and 237.1 Mbps across a variety of Line-of-Sight (LOS) and Non Line-of-Sight (NLOS) locations respectively, which result in 34% and 40% gain over the best non-adaptive scheme. Equivalently, such data rate gain from AMC translates to an SNR improvement of 3 dB. Finally, our implementation of AMC incurs a low overhead of 1.1% of the data rate, and a reasonable complexity, occupying 9.95% of the total transceiver gates on the Field Programmable Gate Array (FPGA). by Farinaz Edalat. Ph.D. 159 p. eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Electrical Engineering and Computer Science. Real-time sub-carrier Adaptive Modulation and Coding in wideband Orthogonal Frequency Division Multiplexing wireless systems Real-time sub-carrier AMC in wideband OFDM wireless systems Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="e519079a-8aa9-4ae2-a214-ee2937ce256d"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Real-time sub-carrier Adaptive Modulation and Coding in wideband Orthogonal Frequency Division Multiplexing wireless systems</Title> <Subtitle>Real-time sub-carrier AMC in wideband OFDM wireless systems</Subtitle> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2008</PublicationDate> <Authors> <Author> <DisplayName>Edalat, Farinaz, 1979-</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Electrical Engineering and Computer Science.</Keyword> <Abstract>The increasing demand for high speed wireless connectivity at low cost proposes new challenges for communication systems designers to implement solutions that increase the data rate by utilizing the limited radio resources more efficiently at a low additional complexity. Sub-carrier Adaptive Modulation and Coding (AMC) exploits the high frequency diversity in wideband Orthogonal Frequency Division Multiplexing (OFDM) channels to obtain higher data rates. While prior work has discussed the value of sub-carrier AMC from a theoretical perspective, this work presents the design and performance of a real-time sub-carrier AMC system. We describe our OFDM transceiver prototype, which implements real-time subcarrier AMC for a wideband wireless channel. We discuss how our design achieves accurate and consistent Signal-to-Noise Ratio (SNR) estimates, which are critical for the success of AMC. We compare the performance of sub-carrier AMC with a non-adaptive scheme that assigns the same modulation and channel coding to all sub-carriers that can support that modulation and coding for the target Bit Error Rate (BER). For a conservative comparison, we compare against the uniform modulation/coding assignment that achieves the highest data rate. Our experiments over the wireless channel show that for a target coded BER of 10-5, our system achieves average data rates of 308.3 and 237.1 Mbps across a variety of Line-of-Sight (LOS) and Non Line-of-Sight (NLOS) locations respectively, which result in 34% and 40% gain over the best non-adaptive scheme. Equivalently, such data rate gain from AMC translates to an SNR improvement of 3 dB. Finally, our implementation of AMC incurs a low overhead of 1.1% of the data rate, and a reasonable complexity, occupying 9.95% of the total transceiver gates on the Field Programmable Gate Array (FPGA).</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>