Wireless Feedback System and Method
    21.
    发明申请
    Wireless Feedback System and Method 有权
    无线反馈系统和方法

    公开(公告)号:US20150103938A1

    公开(公告)日:2015-04-16

    申请号:US14551053

    申请日:2014-11-23

    Applicant: Apple Inc.

    Abstract: A codebook C is provided in a MIMO transmitter as well as a MIMO receiver. The codebook C will include M codewords ci, where i is a unique codeword index for each codeword ci. Each codeword defines weighting factors to apply to the MIMO signals, and may correspond to channel matrices or vectors to apply to the MIMO signals prior to transmission from the respective antennas of the MIMO transmitter. The present invention creates codeword subsets S1 for each codeword c1 of the codebook C. Each codeword subset S1 defines L codewords cj, which are selected from all the codewords ci in the codebook C. The codewords cj in a codeword subset S1 are the L codewords in the entire codebook that best correlate with the corresponding codeword ci.

    Abstract translation: 码本C被提供在MIMO发射机以及MIMO接收机中。 码本C将包括M个码字ci,其中i是每个码字ci的唯一码字索引。 每个码字定义了应用于MIMO信号的加权因子,并且可以对应于在从MIMO发射机的各个天线发送之前应用于MIMO信号的信道矩阵或向量。 本发明为码本C的每个码字c1创建码字子集S1。每个码字子集S1定义从码本C中的所有码字ci中选择的L个码字cj。码字子集S1中的码字cj是L个码字 在整个码本中与相应的码字ci最相关。

    Method and system for combining DFT-transformed OFDM and non-transformed OFDM

    公开(公告)号:US11032119B2

    公开(公告)日:2021-06-08

    申请号:US16780620

    申请日:2020-02-03

    Applicant: Apple Inc.

    Abstract: Methods and systems are provided that enable an OFDM transmitter to be used for transmitting conventional OFDM or a form of transformed OFDM. A technique is provided for transforming a coded and modulated sequence of samples prior to an IFFT that enables the transformed sequence of samples to be transmitted using conventional OFDM or transformed OFDM. The selection of a transform function for transforming the coded and modulated sequence of samples may be based on optimizing the transform function for particular operating conditions between the transmitter and receiver. In some embodiments of the invention OFDM and time transformed OFDM are multiplexed in time and/or frequency in a transmission frame. In some embodiments of the invention a pilot pattern is provided in which the pilot are sent using OFDM and data is sent using OFDM and/or transformed OFDM.

    Methods and Systems for OFDM Using Code Division Multiplexing

    公开(公告)号:US20200119827A1

    公开(公告)日:2020-04-16

    申请号:US16716845

    申请日:2019-12-17

    Applicant: Apple Inc.

    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 scheme for a MIMO communication system

    公开(公告)号:US10560159B2

    公开(公告)日:2020-02-11

    申请号:US16151636

    申请日:2018-10-04

    Applicant: Apple Inc.

    Abstract: The present invention employs a pilot scheme for frequency division multiple access (FDM) communication systems, such as single carrier FDM communication systems. A given transmit time interval will include numerous traffic symbols and two or more short pilot symbols, which are spaced apart from one another by at least one traffic symbol and will have a Fourier transform length that is less than the Fourier transform length of any given traffic symbol. Multiple transmitters will generate pilot information and modulate the pilot information onto sub-carriers of the short pilot symbols in an orthogonal manner. Each transmitter may use different sub-carriers within the time and frequency domain, which is encompassed by the short pilot symbols within the transmit time interval. Alternatively, each transmitter may uniquely encode the pilot information using a unique code division multiplexed code and modulate the encoded pilot information onto common sub-carriers of the short pilot symbols.

    Pilot Symbol Patterns for Transmission through a Plurality of Antennas

    公开(公告)号:US20190288893A1

    公开(公告)日:2019-09-19

    申请号:US16433273

    申请日:2019-06-06

    Applicant: Apple Inc.

    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).

    Pilot symbol patterns for transmission through a plurality of antennas

    公开(公告)号:US10348542B2

    公开(公告)日:2019-07-09

    申请号:US16255702

    申请日:2019-01-23

    Applicant: Apple Inc.

    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).

    Methods and systems for OFDM using code division multiplexing

    公开(公告)号:US10284322B2

    公开(公告)日:2019-05-07

    申请号:US16031047

    申请日:2018-07-10

    Applicant: Apple Inc.

    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

    公开(公告)号:US10200226B2

    公开(公告)日:2019-02-05

    申请号:US16110205

    申请日:2018-08-23

    Applicant: Apple Inc.

    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).

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