Presentation	2003/4/11 Optimum Design of Two-dimensional Spreading Factor Control in vSF-OFCDM with Two-dimensional Spreading for Forward Link Broadband Wireless Access Noriyuki Maeda, Yoshihisa Kishiyama, Hiroyuki Atarashi, Mamoru Sawahashi,
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Abstract(in English)	This paper proposes an optimum design for adaptively controlling the spreading factor in Variable Spreading Factor-Orthogonal Frequency and Code Division Multiplexing (VSF-OFCDM) with two-dimensional spreading according to the cell configuration, channel load, and propagation channel conditions. Simulation results elucidate that the optimum spreading factor in the time domain spreading becomes SF_ = 16, except for an extremely high mobility case such as for the fading maximum Doppler frequency of f_D = 1500 Hz, and it should be decreased to SF_ = 8 for such a very fast fading environment using 16QAM data modulation. Furthermore, when the channel load is light such as C_/SF =0.25(C_ and SF denote the number of multiplexed codes and total spreading factor, respectively), the required average received signal energy per symbol-to-background noise power spectrum density ratio (E_S/N_0) is reduced as the spreading factor in the frequency domain is increased up to say SF_ = 32 both for QPSK and 16QAM data modulations. Meanwhile, when the channel load is near full condition such as when C_/SF = 0.94, the optimum SF_ for 16QAM data modulation is 1 and that for QPSK takes from 1 to 8 according to the delay spread. Consequently, by setting optimum combinations of SF_and SF_ among the limited number of orthogonal combinations, the near maximum system capacity is achieved both in cellular and hot-spot cell configurations assuming various channel conditions.
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Keyword(in English)	VSF-OFCDM / two-dimensional spreading factor control / delay spread / maximum Doppler frequency / channel load
Paper #	RCS2003-22,CQ2003-22
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Committee	CQ
Conference Date	2003/4/11(1days)
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Paper Information
Registration To	Communication Quality (CQ)
Language	JPN
Title (in Japanese)	(See Japanese page)
Sub Title (in Japanese)	(See Japanese page)
Title (in English)	Optimum Design of Two-dimensional Spreading Factor Control in vSF-OFCDM with Two-dimensional Spreading for Forward Link Broadband Wireless Access
Sub Title (in English)
Keyword(1)	VSF-OFCDM
Keyword(2)	two-dimensional spreading factor control
Keyword(3)	delay spread
Keyword(4)	maximum Doppler frequency
Keyword(5)	channel load
1st Author's Name	Noriyuki Maeda
1st Author's Affiliation	Wireless Laboratories, NTT DoCoMo, Inc.()
2nd Author's Name	Yoshihisa Kishiyama
2nd Author's Affiliation	Wireless Laboratories, NTT DoCoMo, Inc.
3rd Author's Name	Hiroyuki Atarashi
3rd Author's Affiliation	Wireless Laboratories, NTT DoCoMo, Inc.
4th Author's Name	Mamoru Sawahashi
4th Author's Affiliation	Wireless Laboratories, NTT DoCoMo, Inc.
Date	2003/4/11
Paper #	RCS2003-22,CQ2003-22
Volume (vol)	vol.103
Number (no)	14
Page	pp.pp.-
#Pages	8
Date of Issue