System and method for uplink transmissions in time division MIMO RDN architecture

• US 8,824,596 B1
• Filed: 07/31/2013
• Issued: 09/02/2014
• Est. Priority Date: 07/31/2013
• Status: Expired due to Fees

• Current Assignee: Magnolia Broadband Incorporated
• Original Assignee: Magnolia Broadband Incorporated
• Inventors: Wang, Sherwin J., Chen, Phil F., Harel, Haim, Abreu, Eduardo
• Primary Examiner(s): Kim, Kevin
• Application Number:
  US13/955,194
• Time in Patent Office: 398 Days
• Field of Search: 375/299, 375/267
• US Class Current: 375/299
• CPC Class Codes: H04B 7/0404 the mobile station comprising multiple antennas, e.g. to provide uplink diversity
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas

Abstract

A mobile device in a (e.g., full rank N×N) MIMO system is augmented by a plurality of kn antennae coupled to at least one of N beamformers such that the total number of antennae M=Σ_n=1^n=N is greater than the total number of beamformers N. A highest gain anchor (e.g., optimal) antenna set may be selected from among a plurality of antenna sets, each antenna set comprising a different one of the kn antennae for each nth beamformer. The phase(s) of the non-selected kn−1 antennae may be set to align with the phase of the selected anchor antenna for each nth beamformer. Using TDD communication, the highest gain anchor antenna set for transmitting during the uplink periods may be determined using information measured by at least some of the plurality of M antennae while receiving during one or more downlink periods.

Claims

1. A mobile device in a multiple-input multiple-output (MIMO) system, the mobile device comprising:

a plurality of N beamformers where N is an integer of which each nth beamformer (n=1, . . . , N) is operatively connected to a plurality of kn antennae where kn is an integer such that the device comprises a total number of antennae that is greater than the number of beamformers N,

a processor to select an optimal antenna set from among a plurality of antenna sets, each antenna set comprising a different one of the kn antennae for each nth beamformer; and

a plurality of phase adjusters configured to set the phase(s) of the non-selected kn−

1 antennae to align with the phase of the selected antenna for each nth beamformer.

2. The mobile device of claim 1 comprising a total number of antennae M, wherein

3. The mobile device of claim 1, wherein each antenna in the mobile device alternates between transmitting during uplink periods and receiving during downlink periods on a single channel according to a time division communication protocol and wherein the selected antenna set defining the phases for transmitting during the uplink periods is selected using information measured at the mobile device while receiving during one or more downlink periods.

4. The mobile device of claim 3, wherein the processor selects the selected antenna set measured to have a maximal total data rate received by the sets during the downlink periods.

5. The mobile device of claim 3, wherein the processor selects the selected antenna set calculated to have an estimated below threshold variation of signal-to-noise ratio and an estimated maximum power for transmitting during uplink periods.

6. The mobile device of claim 5, wherein the processor selects the selected antenna set calculated to have a minimum ratio of largest to smallest singular values

7. The mobile device of claim 6, wherein the uplink channel matrix H_UL is calculated as a function of the transpose of a downlink channel matrix H_DL^T measured during the downlink period.

8. The mobile device of claim 1, wherein the phase adjusters adjust the phases of a non-selected antenna, b, for aligning it with the selected antenna, a, in each beamformer by p·

(φ

_1a−

φ

_1b)+(1−

p)·

(φ

_2a−

φ

_2b), wherein φ

_ij is the phase of the channel from the jth transmitting antenna to the ith receiving antenna, p is a phase constant in a range between 0 and 1, and abs((φ

_1a−

φ

_1b)−

(φ

_2a−

φ

_2b))≦

180.

9. The mobile device of claim 8, wherein the value of the phase constant p is measured to maximize the received power.

10. The mobile device of claim 8, wherein the value of the phase constant p is computed to maximize a sum of powers of singular values

11. The mobile device of claim 1, wherein the mobile device is a full rank N×

N MIMO transmitter augmented by a plurality of kn antennae coupled to at least one (nth) of the N beamformers.

12. A mobile device in a multiple-input multiple-output (MIMO) system, the mobile device comprising:

a plurality of antennae communicating over a single channel with a base station using a time division protocol in which the antennae alternate between transmitting during uplink periods and receiving during downlink periods;

a processor configured to convert channel information measured by the plurality of antennae while receiving data at the mobile device during a downlink period to estimate channel information associated with uplink periods and configured to select phases for the plurality of antennae to transmit data during the uplink periods; and

a plurality of phase adjusters configured to set the phase(s) of data transmitted by the plurality of antennae during the uplink periods, wherein the processor selects phases for the antennae to transmit during the uplink periods based on calculations that correspond to an estimated below threshold signal-to-noise ratio variation and an estimated maximum power.

13. The mobile device of claim 12, wherein the processor selects phases for the antennae to transmit during the uplink periods selected that are calculated to have a minimum ratio of largest to smallest singular values,

14. The mobile device of claim 12, wherein the uplink channel matrix H_UL is calculated as a function of the transpose of a downlink channel matrix H_DL^T measured during the downlink period.

15. The mobile device of claim 12 comprising N beamformers, wherein the plurality of antennae are grouped into kn antennae coupled to each nth beamformer to transmit N data streams, wherein n=1, . . . , N.

16. The mobile device of claim 15, wherein the receiving base station includes N receivers for a full rank N×

N MIMO system augmented by a plurality of kn antennae coupled to at least one (nth) of the N beamformers.

17. The mobile device of claim 15, wherein before receiving data during downlink periods for all of the plurality of antennae, the phase adjusters use previously set phase(s) for the plurality of antennae.

18. A method for transmitting data in a multiple-input multiple-output (MIMO) system, the method comprising:

transmitting data from a plurality of M antennae, wherein the plurality of M antennae include an integer number of kn antennae operatively connected to each nth one of a plurality of N beamformers (n=1, . . . , N) such that

19. The method of claim 18, comprising alternating the direction of transmission of each antenna in the mobile device between transmitting during uplink periods and receiving during downlink periods on a single channel according to a time division communication protocol and selecting the selected antenna set defining the phases for transmitting during the uplink periods using information measured by at least some of the plurality of M antennae while receiving during one or more downlink periods.

20. The method of claim 19, wherein the selected antenna set is selected that is measured to have a maximal total data rate received by the sets during the downlink periods.

21. The method of claim 19, wherein the selected antenna set is selected that is calculated to have an estimated below threshold signal-to-noise ratio variation and an estimated maximum power for transmitting during uplink periods.

22. The method of claim 21, wherein the selected antenna set is selected that is calculated to have a minimum ratio of largest to smallest singular values

23. The method of claim 22, wherein the uplink channel matrix H is calculated as a function of the transpose of a downlink channel matrix H_DL^T measured during the downlink period.

24. The method of claim 18, wherein the phases applied to a non-anchor antenna, b, for aligning it with the anchor antenna, a, in each beamformer is adjusted by p·

(φ

_1a−

φ

_1b)+(1−

p)·

(φ

_2a−

φ

_2b), wherein φ

_ij is the phase of the channel from the jth transmitting antenna to the ith receiving antenna, p is a phase constant in a range between 0 and 1, and abs((φ

_1a−

φ

_1b)−

(φ

_2a−

φ

_2b))−

180°

.

25. The method of claim 24, wherein the value of the phase constant p is measured to maximize the received power.

26. The method of claim 24, wherein the value of the phase constant p is computed to maximize a sum of powers of singular values

27. The method of claim 18, wherein the data is transmitted by the plurality of M antennae in a full rank N×

N MIMO transmitter augmented by a plurality of kn antennae coupled to at least one (nth) of the N beamformers.