Low overhead MIMO scheme

• US 20100091905A1
• Filed: 08/26/2009
• Published: 04/15/2010
• Est. Priority Date: 10/14/2008
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Khan, Farooq
• Granted Patent: US 8,774,310 B2
• Time in Patent Office: Days
• US Class Current: 375/296
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0087 when data requirements change

Abstract

Systems and methods are disclosed for use in a communications network that includes transmitting a set of known precodes on a plurality of subbands and storing a correlation of transmitted precodes with a time of transmission of the precodes. These systems and methods also include receiving a set of channel quality indicators (CQI) that correspond to the time of transmission of the precodes and determining which precodes may be used in communication based upon the received CQIs and the correlation of the transmitted precodes with the time of transmission of the precodes.

Claims

1. For use in a communications network, a method of reducing the transmission overhead, comprising:

transmitting a set of known precodes on a plurality of subbands;

storing a correlation of transmitted precodes with a time of transmission of the precodes;

receiving a set of channel quality indicators (CQIs) that correspond to the time of transmission of the precodes; and

determining which precodes among the transmitted precodes is usable for communication based upon the received CQIs and the correlation of the transmitted precodes with the time of transmission of the precodes.

2. The method of claim 1, wherein a base station is used to transmit the set of known precodes.

3. The method of claim 1, wherein the precodes are obtained from a codebook.

4. The method of claim 3, wherein the code corresponds to a particular number of antenna ports.

5. The method of claim 1, wherein the known set of precodes are also transmitted on a set of subfrequencies.

6. The method of claim 1, wherein the communications network is a wireless communications network.

7. The method of claim 6, wherein the communications network uses a plurality of antennas.

8. The method of claim 7, wherein the communications network uses a multiple in multiple out (MIMO) transmission scheme.

9. For use in a wireless communications network, a base station, comprising:

a transmitter to transmit a set of signals with known precodes on at least two subbands;

a storage device to store a time when the set of known precodes are transmitted;

a receiver to receive a set of channel quality indicators (CQI) that correspond to the time of transmission of the precodes; and

a processor to determine which precodes among the set of known precodes is operable for communication based upon the received CQI and the correlation of the transmitted precodes with the time of transmission of the precodes.

10. The base station of claim 9, wherein the base station is an Enhanced-node B (E-node-B).

11. The base station of claim 9, wherein the set of signals contain at least one reference signal.

12. The base station of claim 9, wherein the base station is able to receive a plurality of CQI from a plurality of user equipment devices.

13. The base station of claim 12, wherein the base station schedules data transmission based upon the plurality of CQIs.

14. The base station of claim 12, wherein the transmitter transmits the known set of precodes on all available subbands.

15. For use in a wireless network, a mobile device, comprising:

a receiver that receives a precoded signal, wherein the precoded signal is transmitted using a multiple in multiple out (MIMO) scheme;

a processor that interprets the precoded signal; and

a transmitter that transmits a channel quality indicator (CQI) based upon the precoded signal, wherein the transmitter transmits the CQI determined using the precoded signal without providing feedback related to the precoded signal.

16. The mobile device of claim 15, wherein the mobile device is capable of determining which beam among a plurality of beams in the MIMO scheme is preferred.

17. The mobile device of claim 15, wherein the device is capable of determining the number of transmission layers without a dedicated reference signal from a base station using the precoded signal.

18. The mobile device of claim 15, wherein the device is configured to use multiple layers within the MIMO scheme simultaneously.

19. The mobile device of claim 16, wherein the mobile device determines the preferred beam based upon a comparison of CQIs from a plurality of beams.

20. The mobile device of claim 19, wherein the mobile device only reports the CQI and an ID of the selected beam.