Multiuser carrier frequency offsets estimation for OFDMA uplink with generalized carrier assignment scheme

• Published in: IEEE transactions on wireless communications Vol. 8; no. 7; pp. 3347 - 3353
• Main Authors: Wang, Huiming, Yin, Qinye
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.07.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antennas; Applied sciences; Array signal processing; Bandwidth; Base stations; Blinds; Carrier frequencies; carrier-frequency offset (CFO); Carriers; Computer simulation; Content addressable storage; Detection, estimation, filtering, equalization, prediction; Downlink; Dynamical systems; Dynamics; Exact sciences and technology; Frequency estimation; Frequency synchronization; generalized carrier assignment scheme; Information, signal and communications theory; Monte Carlo methods; Multiple access interference; Multiplexing; multiuser system; Narrowband; Orthogonal frequency-division multiple-access (OFDMA); Radiocommunications; Signal and communications theory; Signal, noise; Studies; Subcarriers; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Wireless communication; Performance evaluation; Direction-of-arrival estimation; Parameter estimation; Base station; Signal estimation; carrier-frequency offset (CFO); Frequency division multiple access; Downlink; Frequency conversion; Subcarrier; Beam forming; Dynamic allocation; multiuser system; Linear antenna arrays; Uplink; Availability; generalized carrier assignment scheme; Multiple access; Synchronization; Algorithm; Orthogonal frequency-division multiple-access (OFDMA); Carrier frequency; Narrow band signal; Channel allocation; Orthogonal frequency division multiplexing; Numerical simulation; Frequency offset; Resource management
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2009.080022

The frequency synchronization issue of multiuser in the uplink of an orthogonal frequency-division multiple-access (OFDMA) system is investigated in this letter. We develop a subspace based blind carrier frequency offsets (CFOs) estimation algorithm for the base station (BS) equipped with uniform linear array (ULA). Due to the adoption of ULA at the BS and the narrowband signal assumption, CFOs of different users can be separated by their spatial information. Thus, unlike existing blind alternatives, which are subject to some specific carrier assignment schemes (CAS) or rely on null subcarriers, our proposed method can support generalized carrier assignment scheme (GCAS) and fully loaded systems, i.e., all subcarriers are available to users. Consequently, the dynamic channel assignment is available and the bandwidth efficiency is higher. Moreover, the closed-form directions of arrival (DOAs) of all active users are also obtained, which can be used in downlink beamforming in frequency division duplex (FDD) systems. Performance of the proposed scheme is evaluated by computer Monte Carlo simulations.