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Joint Estimation of the Timing and Frequency Offset for Uplink OFDMA

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Abstract

Inheriting all the advantages of Orthogonal Frequency Division Multiplexing (OFDM), plus the ability to offer a fine level of bit granularity and dynamic subcarrier allocation for multiuser diversity, the Orthogonal Frequency Division Multiple Access (OFDMA) has emerged as a potential candidate for multiple access technique for future broadband wireless networks. However, the benefits of OFDMA come with stringent requirements on synchronization, especially in the uplink. Unless the timing offsets (TOs) and carrier frequency offsets (CFOs) among users in the uplink are kept under tolerable ranges, inter-symbol interference (ISI), inter-channel interference (ICI) and multi-user interference (MUI) will occur, which degrade the overall system performance severely. Accurate estimation of TOs and CFOs is required for each user, so that they can be accounted for at the user’s side or compesated for at the base station. This paper proposes a novel method to estimate jointly TOs and CFOs in the time-domain for multi-user in the OFDMA uplink. The method is shown to offer good accuracy, while maintaining a reasonable complexity compared to conventional estimation schemes.

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Abbreviations

OFDM:

Orthogonal Frequency Division Multiplexing

OFDMA:

Orthogonal Frequency Division Multiple Access

ICI:

Inter-channel interference

ISI:

Inter-symbol interference

MUI:

Multi-user interference

CFO:

Carrier-frequency offset

TO:

Timing offset

MS:

Mobile station

BS:

Base Station

CP:

Cyclic prefix

CIR:

Channel impulse response

AWGN:

Additive white Gaussian noise

MSE:

mean squared error

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Authors and Affiliations

  1. Center for TeleInFrastructure, Aalborg University, Aalborg, Denmark

    Huan Cong Nguyen, Elisabeth de Carvalho & Ramjee Prasad

Authors
  1. Huan Cong Nguyen
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  2. Elisabeth de Carvalho
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  3. Ramjee Prasad
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Correspondence to Huan Cong Nguyen.

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Nguyen, H.C., de Carvalho, E. & Prasad, R. Joint Estimation of the Timing and Frequency Offset for Uplink OFDMA. Wireless Pers Commun 52, 119–131 (2010). https://doi.org/10.1007/s11277-008-9508-z

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  • DOI: https://doi.org/10.1007/s11277-008-9508-z

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