Closed loop mimo systems and methods

Patent metadata

Field	Value
Publication number	US-2017222702-A1
Application number	US-201715486060-A
Country	US
Kind code	A1
Filing date	Apr 12, 2017
Priority date	Jun 22, 2004
Publication date	Aug 3, 2017
Grant date	—

Abstract

Systems and methods for closed loop MIMO (multiple input and multiple output) wireless communication are provided. Various transmit formats including spatial multiplexing and STTD are defined in which vector or matrix weighting is employed using information fed back from receivers. The feedback information may include channel matrix or SVD-based feedback.

First claim

1 - 24 . (canceled)

25 . A multiple input multiple output (MIMO) system comprising:
a receiver configured to:
analyze one or more channel conditions of a wireless communication channel between the receiver and a transmitter having a plurality of transmit antennas;
based on the one or more channel conditions, select one of a spatial-multiplexing (SM) format or a transmit diversity format and one or more transmission layers for use in transmission to the receiver, wherein the format is selected from a defined subset of available formats; and
generate, for transmission to the transmitter, feedback information indicating the selected format for transmission and the one or more transmission layers, wherein the one or more transmission layers is included in a rank indication in the feedback information.

26 . The system of claim 25 , wherein the transmit diversity format includes a single data stream.

27 . The system of claim 26 , wherein the single stream comprises four transmission intervals during which four symbols are transmitted.

28 . The system of claim 25 , wherein the transmit diversity format comprises a STTD format.

29 . The system of claim 28 , wherein the STTD format is proportionally weighted.

30 . The system of claim 25 , wherein the SM format includes two data streams.

31 . The system of claim 30 , wherein a first stream of the two data streams is weighted.

32 . The system of claim 25 , wherein the feedback information specifies beam-forming information.

33 . The system of claim 25 , wherein layer based water-filling is employed to provide additional gain to the system.

34 . The system of claim 33 , wherein power is increased for a first transmission layer of the one or more transmission layers based on the channel conditions.

35 . A multiple input multiple output (MIMO) system comprising:
a receiver configured to receive a first orthogonal frequency division multiplexing (OFDM) signal at a first time, the first OFDM signal comprising a set of non-pre-coded pilots from a plurality of transmit antennas, wherein the non-pre-coded pilots are useable to obtain channel measurements for each antenna of the plurality of transmit antennas and are distributed across subcarrier and symbol locations in the first OFDM signal; a processor configured to determine feedback based on the non-pre-coded pilots; and a transmitter configured to transmit the feedback to a base station; wherein the receiver is further configured to:
receive a second OFDM signal at a second time, the second OFDM signal comprising non-pre-coded pilots and pre-coded pilots, wherein the pre-coded pilots are pre-coded for the receiver based on the feedback and are distributed across subcarrier and symbol locations of a resource assignment for the receiver in the second OFDM signal; and
recover transmitted information of pre-coded data received in the resource assignment for the receiver in the second OFDM signal using the pre-coded pilots.

36 . The system of claim 35 , wherein the second OFDM signal further comprises a second resource assignment for a second receiver, and wherein the second resource assignment comprises pre-coded pilots specific to the second receiver.

37 . The system of claim 35 , wherein pre-coded pilots can be recovered by a particular user and non-pre-coded pilots can be recovered by multiple users.

38 . The system of claim 35 , wherein when the receiver is mobile, a number of the pre-coded pilots in the set is reduced in one of time or frequency.

39 . The system of claim 35 , wherein the pilots are pre-coded by dirty-paper pre-coding.

40 . The system of claim 35 , wherein the transmitted information is recovered by, at least, an interpolation process.

41 . The system of claim 35 , wherein the pre-coding comprises beam-forming weights.

42 . The system of claim 35 , wherein the pilots are pre-coded using a flat part of a band.

43 . The system of claim 35 , wherein the pilots are pre-coded using interlaced antenna pilot mapping.

44 . The system of claim 35 , wherein block antenna pilot mapping is employed.

Assignees

• Apple Inc

Inventors

• Tong Wen
• Jia Ming
• Ma Jianglei
• Zhu Peiying
• Xu Hua
• Yu Dong-Sheng
• Zhang Hang
• Fong Mo-Han

Classifications

• H04W72/23

  in the downlink direction of a wireless link, i.e. towards a terminal · CPC title

• H04W72/54

  based on quality criteria · CPC title

• H04B7/0673

  using feedback from receiving side · CPC title

• H04L5/0028

  Variable division (indication of the divided channel H04L5/0092) · CPC title

• H04L27/2601

  Multicarrier modulation systems · CPC title