Performance Evaluation of Coherent High-Speed TD-OFCDM Broadband Packet Wireless Access in Forward Link Employing Multi-Level Modulation and Hybrid ARQ

Hiroyuki ATARASHI; Sadayuki ABETA; Mamoru SAWAHASHI

Performance Evaluation of Coherent High-Speed TD-OFCDM Broadband Packet Wireless Access in Forward Link Employing Multi-Level Modulation and Hybrid ARQ

Hiroyuki ATARASHI, Sadayuki ABETA, Mamoru SAWAHASHI

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This paper evaluates high-speed broadband packet wireless access in the forward link using coherent Time Division-Orthogonal Frequency and Code Division Multiplexing (TD-OFCDM) by applying time-multiplexed pilot symbol assisted channel estimation and integrating efficient multi-level modulation, hybrid automatic repeat request (ARQ), and code-multiplexing over a 50-100 MHz bandwidth. Computer simulation results first clarify that the common time-multiplexed pilot symbols with the transmit power of 6 dB higher than that of data symbols should be placed at both the beginning and end of a packet, and that the optimum averaging interval of channel estimates in the frequency domain is different according to the delay spread of a channel. Based on these optimized parameters for packet transmission, we show that the orthogonality among the code-multiplexed channels is destroyed due to severe frequency selective (multipath) fading and the accumulation of spread signals using equal gain combining (EGC) in the frequency domain. This degrades the achievable throughput performance especially when employing multi-level modulation and a high coding rate. Consequently, coherent TD-OFCDM with 8PSK data modulation and the convolutional coding of rate R = 2/3 employing sixteen-code multiplexing (spreading factor (SF) is 16) achieves the highest throughput of approximately 105 Mbps at the average received E_b/N₀ (signal energy per bit-to-noise power spectrum density ratio) of approximately 24 dB in a 3-path Rayleigh fading channel (rms delay spread, σ= 0.1 µsec). Furthermore, in coherent TD-OFCDM with QPSK and R = 4/5 or 8PSK and R = 1/2, throughput performance greater than 80 Mbps is achieved at the average received E_b/N₀ of approximately 20 dB even in a 24-path Rayleigh fading channel (σ= 0.2 µsec).

Publication: IEICE TRANSACTIONS on Fundamentals Vol.E84-A No.7 pp.1670-1680

Publication Date: 2001/07/01

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Type of Manuscript: Special Section PAPER (Special Section on Multi-dimensional Mobile Information Networks)

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Hiroyuki ATARASHI, Sadayuki ABETA, Mamoru SAWAHASHI, "Performance Evaluation of Coherent High-Speed TD-OFCDM Broadband Packet Wireless Access in Forward Link Employing Multi-Level Modulation and Hybrid ARQ" in IEICE TRANSACTIONS on Fundamentals, vol. E84-A, no. 7, pp. 1670-1680, July 2001, doi: .
Abstract: This paper evaluates high-speed broadband packet wireless access in the forward link using coherent Time Division-Orthogonal Frequency and Code Division Multiplexing (TD-OFCDM) by applying time-multiplexed pilot symbol assisted channel estimation and integrating efficient multi-level modulation, hybrid automatic repeat request (ARQ), and code-multiplexing over a 50-100 MHz bandwidth. Computer simulation results first clarify that the common time-multiplexed pilot symbols with the transmit power of 6 dB higher than that of data symbols should be placed at both the beginning and end of a packet, and that the optimum averaging interval of channel estimates in the frequency domain is different according to the delay spread of a channel. Based on these optimized parameters for packet transmission, we show that the orthogonality among the code-multiplexed channels is destroyed due to severe frequency selective (multipath) fading and the accumulation of spread signals using equal gain combining (EGC) in the frequency domain. This degrades the achievable throughput performance especially when employing multi-level modulation and a high coding rate. Consequently, coherent TD-OFCDM with 8PSK data modulation and the convolutional coding of rate R = 2/3 employing sixteen-code multiplexing (spreading factor (SF) is 16) achieves the highest throughput of approximately 105 Mbps at the average received E_b/N₀ (signal energy per bit-to-noise power spectrum density ratio) of approximately 24 dB in a 3-path Rayleigh fading channel (rms delay spread, σ= 0.1 µsec). Furthermore, in coherent TD-OFCDM with QPSK and R = 4/5 or 8PSK and R = 1/2, throughput performance greater than 80 Mbps is achieved at the average received E_b/N₀ of approximately 20 dB even in a 24-path Rayleigh fading channel (σ= 0.2 µsec).
URL: https://global.ieice.org/en_transactions/fundamentals/10.1587/e84-a_7_1670/_p

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@ARTICLE{e84-a_7_1670,
author={Hiroyuki ATARASHI, Sadayuki ABETA, Mamoru SAWAHASHI, },
journal={IEICE TRANSACTIONS on Fundamentals},
title={Performance Evaluation of Coherent High-Speed TD-OFCDM Broadband Packet Wireless Access in Forward Link Employing Multi-Level Modulation and Hybrid ARQ},
year={2001},
volume={E84-A},
number={7},
pages={1670-1680},
abstract={This paper evaluates high-speed broadband packet wireless access in the forward link using coherent Time Division-Orthogonal Frequency and Code Division Multiplexing (TD-OFCDM) by applying time-multiplexed pilot symbol assisted channel estimation and integrating efficient multi-level modulation, hybrid automatic repeat request (ARQ), and code-multiplexing over a 50-100 MHz bandwidth. Computer simulation results first clarify that the common time-multiplexed pilot symbols with the transmit power of 6 dB higher than that of data symbols should be placed at both the beginning and end of a packet, and that the optimum averaging interval of channel estimates in the frequency domain is different according to the delay spread of a channel. Based on these optimized parameters for packet transmission, we show that the orthogonality among the code-multiplexed channels is destroyed due to severe frequency selective (multipath) fading and the accumulation of spread signals using equal gain combining (EGC) in the frequency domain. This degrades the achievable throughput performance especially when employing multi-level modulation and a high coding rate. Consequently, coherent TD-OFCDM with 8PSK data modulation and the convolutional coding of rate R = 2/3 employing sixteen-code multiplexing (spreading factor (SF) is 16) achieves the highest throughput of approximately 105 Mbps at the average received E_b/N₀ (signal energy per bit-to-noise power spectrum density ratio) of approximately 24 dB in a 3-path Rayleigh fading channel (rms delay spread, σ= 0.1 µsec). Furthermore, in coherent TD-OFCDM with QPSK and R = 4/5 or 8PSK and R = 1/2, throughput performance greater than 80 Mbps is achieved at the average received E_b/N₀ of approximately 20 dB even in a 24-path Rayleigh fading channel (σ= 0.2 µsec).},
keywords={},
doi={},
ISSN={},
month={July},}

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TY - JOUR
TI - Performance Evaluation of Coherent High-Speed TD-OFCDM Broadband Packet Wireless Access in Forward Link Employing Multi-Level Modulation and Hybrid ARQ
T2 - IEICE TRANSACTIONS on Fundamentals
SP - 1670
EP - 1680
AU - Hiroyuki ATARASHI
AU - Sadayuki ABETA
AU - Mamoru SAWAHASHI
PY - 2001
DO -
JO - IEICE TRANSACTIONS on Fundamentals
SN -
VL - E84-A
IS - 7
JA - IEICE TRANSACTIONS on Fundamentals
Y1 - July 2001
AB - This paper evaluates high-speed broadband packet wireless access in the forward link using coherent Time Division-Orthogonal Frequency and Code Division Multiplexing (TD-OFCDM) by applying time-multiplexed pilot symbol assisted channel estimation and integrating efficient multi-level modulation, hybrid automatic repeat request (ARQ), and code-multiplexing over a 50-100 MHz bandwidth. Computer simulation results first clarify that the common time-multiplexed pilot symbols with the transmit power of 6 dB higher than that of data symbols should be placed at both the beginning and end of a packet, and that the optimum averaging interval of channel estimates in the frequency domain is different according to the delay spread of a channel. Based on these optimized parameters for packet transmission, we show that the orthogonality among the code-multiplexed channels is destroyed due to severe frequency selective (multipath) fading and the accumulation of spread signals using equal gain combining (EGC) in the frequency domain. This degrades the achievable throughput performance especially when employing multi-level modulation and a high coding rate. Consequently, coherent TD-OFCDM with 8PSK data modulation and the convolutional coding of rate R = 2/3 employing sixteen-code multiplexing (spreading factor (SF) is 16) achieves the highest throughput of approximately 105 Mbps at the average received E_b/N₀ (signal energy per bit-to-noise power spectrum density ratio) of approximately 24 dB in a 3-path Rayleigh fading channel (rms delay spread, σ= 0.1 µsec). Furthermore, in coherent TD-OFCDM with QPSK and R = 4/5 or 8PSK and R = 1/2, throughput performance greater than 80 Mbps is achieved at the average received E_b/N₀ of approximately 20 dB even in a 24-path Rayleigh fading channel (σ= 0.2 µsec).
ER -