MIMO transmitter for transmitting a group of sequential OFDM symbols using a plurality of antennas

• US 8,396,147 B2
• Filed: 04/09/2010
• Issued: 03/12/2013
• Est. Priority Date: 08/08/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Sadowsky, John S., Ho, Minnie, Jacobsen, Eric A., Maltsev, Alexander A., Sadri, Ali S., Sandhu, Sumeet
• Primary Examiner(s): PHU, PHUONG M
• Application Number:
  US12/757,117
• Publication Number:
  US 20100195545A1
• Time in Patent Office: 1,068 Days
• Field of Search: 375/260, 375/267, 375/347, 375/299, 375/343, 455/500, 455/504, 455/506, 455/101, 455/65, 455/137, 370/208
• US Class Current: 375/260
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 74/02 Hybrid access

Abstract

A MIMO transmitter and method for transmitting a group of sequential OFDM symbols on a downlink channel using a plurality of antennas is disclosed herein. Groups of OFDM subcarriers are individually modulated in accordance with spatial-frequency subcarrier modulation assignments to generate groups of symbol-modulated subcarriers, corresponding symbol-modulated subcarriers are combined for transmission on each of a plurality of spatial channels, and beamforming is performed on the combined symbol-modulated subcarriers for transmission over the spatial channels. The channel comprises a plurality of the groups of the OFDM subcarriers and the OFDM subcarriers within each group of subcarriers and within each group of sequential OFDM symbols have the same spatial-frequency subcarrier modulation assignments. The spatial-frequency subcarrier modulation assignments for each group are determined based on feedback by a receiver, which is determined from spatial channel characteristics of the spatial channels.

Claims

1. A multiple-input-multiple output (MIMO;

) transmitter for transmitting a group of sequential orthogonal frequency division multiplexed (OFDM) symbols on a channel using a plurality of antennas comprising;

subcarrier modulators to individually modulate groups of OFDM subcarriers in accordance with spatial-frequency subcarrier modulation assignments to generate groups of symbol-modulated subcarriers;

logic to combine corresponding symbol-modulated subcarriers for transmission on each of a plurality of spatial channels, the spatial channels being non-orthogonal and having different multipath characteristics; and

a beamformer to perform beamforming on the combined symbol-modulated subcarriers for transmission over the spatial channels,

wherein the channel comprises a plurality of the groups of the OFDM subcarriers,

wherein the OFDM subcarriers within each group of subcarriers and within each group of sequential OFDM symbols have the same spatial-frequency subcarrier modulation assignments, and

wherein the spatial-frequency subcarrier modulation assignments for each group are determined based on feedback by a receiver, the feedback determined from spatial channel characteristics of the spatial channels.

2. The MIMO transmitter of claim 1 further comprising a spatial-frequency parser to parse a block of bits into spatial-frequency groups of a variable number of coded bits, each spatial frequency group being associated with a spatial component and a frequency component of the OFDM symbols, the spatial component being associated with one of the spatial channels, the frequency component being associated with one group of the OFDM subcarriers.

6. The MIMO transmitter of claim 1 wherein the channel is a time-division multiplexed (TDM) downlink channel in which frames comprising the groups of symbols are time-division multiplexed.

3. A multiple-input-multiple output (MIMO) receiver for receiving a group of sequential orthogonal frequency division multiplexed (OFDM) symbols, the receiver comprising:

a beamformer to perform beamforming on signals received through a single antenna that were transmitted by a MIMO transmitter over a plurality of spatial channels, the beamformer to help separate signals of the spatial channels, the spatial channels being non-orthogonal and having different multipath characteristics;

logic to determine spatial-frequency subcarrier modulation assignments for groups of OFDM subcarriers from channel characteristics of the spatial channels and provided feedback indicative of the assignments for transmission to the MIMO transmitter; and

subcarrier demodulators to demodulate received OFDM subcarriers that comprise the OFDM symbol based on the spatial-frequency subcarrier modulation assignments for the groups of OFDM subcarriers, wherein the same spatial-frequency subcarrier modulation assignments are selected for each subcarrier within the groups of OFDM subcarriers, and wherein the MIMO transmitter is configured to transmit a group of sequential OFDM symbols on a channel with each subcarrier of the group having the same spatial-frequency subcarrier modulation assignment.

4. The MIMO receiver of claim 3 wherein the beamformer performs beamforming on signals that are received through each of a plurality of single antennas, the signals having been transmitted by the MIMO transmitter over the plurality of spatial channels.

5. The MIMO receiver of claim 3 wherein the channel is a time-division multiplexed (TDM) downlink channel in which frames comprising the groups of symbols are time-division multiplexed.

7. A MIMO transmitter to transmit a group of sequential orthogonal frequency division multiplexed (OFDM) symbols on a channel using a plurality of antennas, the MIMO transmitter configured to:

individually modulate groups of OFDM subcarriers in accordance with spatial-frequency subcarrier modulation assignments to generate groups of symbol-modulated subcarriers;

combine corresponding symbol-modulated subcarriers for transmission on each of a plurality of spatial channels; and

perform beamforming on the combined symbol-modulated subcarriers for transmission over the spatial channels,

wherein the channel comprises a plurality of the groups of the OFDM subcarriers,

wherein the OFDM subcarriers within each group of subcarriers and within each group of sequential OFDM symbols have the same spatial-frequency subcarrier modulation assignments, and

wherein the spatial-frequency subcarrier modulation assignments for each group are determined based on feedback by a receiver, the feedback determined from spatial channel characteristics of the spatial channels.

8. The MIMO transmitter of claim 7 wherein the spatial channels are non-orthogonal and have different multipath characteristics, and

wherein the channel is a downlink channel in which frames comprising the groups of symbols are time-division multiplexed on the downlink channel.

9. A method for transmitting a group of sequential orthogonal frequency division multiplexed (OFDM) symbols on a channel using a plurality of antennas, the method comprising:

individually modulating groups of OFDM subcarriers in accordance with spatial-frequency subcarrier modulation assignments to generate groups of symbol-modulated subcarriers;

combining corresponding symbol-modulated subcarriers for transmission on each of a plurality of spatial channels; and

performing beamforming on the combined symbol-modulated subcarriers for transmission over the spatial channels,

wherein the channel comprises a plurality of the groups of the OFDM subcarriers,

wherein the OFDM subcarriers within each group of subcarriers and within each group of sequential OFDM symbols have the same spatial-frequency subcarrier modulation assignments, and

wherein the spatial-frequency subcarrier modulation assignments for each group are determined based on feedback by a receiver, the feedback determined from spatial channel characteristics of the spatial channels.

10. The method of claim 9 wherein the spatial channels are non-orthogonal and have different multipath characteristics, and

wherein the channel is a downlink channel in which frames comprising the groups of symbols are time-division multiplexed on the downlink channel.