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    Methods and systems for OFDM using code division multiplexing
    72.
    发明授权
    Methods and systems for OFDM using code division multiplexing 有权

    公开(公告)号：US10541773B2

    公开(公告)日：2020-01-21

    申请号：US16374147

    申请日：2019-04-03

    Applicant: Apple Inc.

    Inventor： Jianglei Ma ,  Ming Jia ,  Wen Tong ,  Peiying Zhu ,  Hua Xu ,  Hang Zhang ,  Mo-Han Fong

    IPC: H04J13/00 ,  H04B7/06 ,  H04L5/00 ,  H04L25/02 ,  H04L27/26 ,  H04B1/707 ,  H04B7/0404 ,  H04W72/04 ,  H04J13/16 ,  H04L25/03

    Abstract: In some embodiments of the invention, OFDM symbols are transmitted as a plurality of clusters. A cluster includes a plurality of OFDM sub-carriers in frequency, over a plurality of OFDM symbol durations in time. Each cluster includes data as well as pilot information as a reference signal for channel estimation. In some embodiments, a plurality of clusters collectively occupy the available sub-carrier set in the frequency domain that is used for transmission. In some embodiments of the invention data and/or pilots are spread within each cluster using code division multiplexing (CDM). In some embodiments pilots and data are separated by distributing data on a particular number of the plurality of OFDM symbol durations and pilots on a remainder of the OFDM symbol durations. CDM spreading can be performed in time and/or frequency directions.

    Pilot symbol patterns for transmission through a plurality of antennas
    73.
    发明授权
    Pilot symbol patterns for transmission through a plurality of antennas 有权

    公开(公告)号：US10476719B2

    公开(公告)日：2019-11-12

    申请号：US16433273

    申请日：2019-06-06

    Applicant: Apple Inc.

    Inventor： Jianglei Ma ,  Ming Jia ,  Wen Tong ,  Peiying Zhu ,  Hang Zhang ,  Hua Xu ,  Dongsheng Yu

    IPC: H04L27/26 ,  H04L25/02 ,  H04L5/00 ,  H04B7/06 ,  H04B7/08 ,  H04W52/32 ,  H04L1/00 ,  H04L1/06

    Abstract: A method and apparatus for improving channel estimation within an OFDM communication system. Channel estimation in OFDM is usually performed with the aid of pilot symbols. The pilot symbols are typically spaced in time and frequency. The set of frequencies and times at which pilot symbols are inserted is referred to as a pilot pattern. In some cases, the pilot pattern is a diagonal-shaped lattice, either regular or irregular. The method first interpolates in the direction of larger coherence (time or frequency). Using these measurements, the density of pilot symbols in the direction of faster change will be increased thereby improving channel estimation without increasing overhead. As such, the results of the first interpolating step can then be used to assist the interpolation in the dimension of smaller coherence (time or frequency).

    Preambles in OFDMA system
    75.
    发明授权
    Preambles in OFDMA system 有权

    公开(公告)号：US10212017B2

    公开(公告)日：2019-02-19

    申请号：US15823072

    申请日：2017-11-27

    Applicant: APPLE INC.

    Inventor： Jianglei Ma ,  Hang Zhang ,  Wen Tong ,  Ming Jia ,  Peiying Zhu ,  Mo-Han Fong

    IPC: H04L27/26 ,  H04B7/02 ,  H04L5/00 ,  H04W24/02 ,  H04B7/0452 ,  H04L7/04

    Abstract: The present invention provides a preamble that is inserted into an OFDMA frame and has a common sequence for all the base stations participating in a transmission. The subscriber station performs fine synchronization using the common sequence on the common preamble, and the resulting peaks will provide the locations of candidate base stations. The base station specific search is then performed in the vicinities of those peaks by using base station specific pseudo-noise sequences. With this two stage cell search, the searching window is drastically reduced. The preamble is matched to known values by a respective receiver to decode the signals and permit multiple signals to be transferred from the transmitter to the receiver. The preamble may comprise two parts, Preamble-1 and Preamble-2, which may be used in different systems, including multioutput, multi-input (MIMO) systems.

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