Operating a cellular MIMO system

1. A method for operating a cellular multiple-input and multiple-output, MIMO, system, the cellular MIMO system comprising a first device having an antenna array comprising a plurality of antennas, and a second device comprising at least two antennas, the method comprising:

broadcasting an identical uplink pilot signal from each antenna of the at least two antennas of the second device using a single pilot signal resource,

receiving, at the antenna array of the first device, a signal resulting from transmission of the identical uplink pilot signal from each antenna of the at least two antennas of the second device,

determining, at the first device, a first set of first device receiving parameters for the antenna array depending on the received identical uplink pilot signal,

sending from each antenna of the at least two antennas of the second device a corresponding uplink pilot signal of a plurality of uplink pilot signals, wherein the plurality of uplink pilot signals are orthogonal to each other,

receiving the plurality of uplink pilot signals at the antenna array of the first device using the first set of first device receiving parameters, and

determining, at the first device, for each received uplink pilot signal of the plurality of uplink pilot signals a corresponding second set of first device receiving parameters for the antenna array of a plurality of second sets, depending on the plurality of received orthogonal uplink pilot signals.

2. The method according to claim 1 , further comprising:

sending via each antenna of the at least two antennas of the second device corresponding uplink payload data, and

receiving the uplink payload data at the antenna array of the first device using the corresponding second set of first device receiving parameters.

3. The method according to claim 1 , further comprising for at least one second set of first device receiving parameters of the second sets of first device receiving parameters:

determining a corresponding set of first device transmission parameters, the corresponding set of first device transmission parameters being configured to focus a downlink signal from the antenna array of the first device to a corresponding antenna of the second device from which the corresponding uplink pilot signal was received.

4. The method according to claim 3 , further comprising:

sending from the antenna array of the first device downlink payload data using the corresponding set of first device transmission parameters.

5. The method according to claim 3 , further comprising:

sending from the antenna array of the first device a downlink pilot signal using the corresponding set of first device transmission parameters,

receiving at the corresponding antenna of the second device, from which the corresponding uplink pilot signal was received, the downlink pilot signal, and

determining, at the second device, a corresponding set of second device receiving parameters for the corresponding antenna, from which the corresponding uplink pilot signal was emitted, based on the received downlink pilot signal.

6. The method according to claim 5 , further comprising:

sending via the antenna array of the first device corresponding downlink payload data using the corresponding set of the first device transmission parameters, and

receiving the downlink payload data at the corresponding antenna of the second device, from which the corresponding uplink pilot signal was emitted, using the set of second device receiving parameters.

7. The method of claim 1 , further comprising:

for each received uplink pilot signal:

selecting, at the first device, a corresponding pre-coding from a predefined codebook,

pre-coding a corresponding downlink pilot signal and corresponding downlink payload data stream using the corresponding pre-coding,

sending from the antenna array of the first device the pre-coded corresponding downlink pilot signal and corresponding downlink payload data stream, and

receiving, at each antenna of the at least two antennas of the second device, each of the pre-coded corresponding downlink pilot signals and corresponding downlink payload data streams, and

separating, in the second device, the corresponding downlink payload data streams based on the corresponding downlink pilot signals and the predefined codebook.

8. The method of claim 1 , wherein the cellular MIMO system comprises a further second device comprising at least two antennas, the method comprising:

broadcasting a further identical uplink pilot signal from each antenna of the at least two antennas of the further second device,

receiving the further identical uplink pilot signal from the further second device at the antenna array of the first device,

determining, at the first device, a third set of first device receiving parameters for the antenna array depending on the received further identical uplink pilot signal,

sending from each antenna of the at least two antennas of the further second device a corresponding uplink pilot signal of the plurality of uplink pilot signals, wherein the corresponding uplink pilot signals are the same as the corresponding uplink pilot signals sent from each antenna of the at least two antennas of the second device and are sent at the same time,

receiving the plurality of uplink pilot signals at the antenna array of the first device using the third set of first device receiving parameters, and

determining, at the first device, for each received uplink pilot signal of the plurality of uplink pilot signals a corresponding fourth set of first device receiving parameters for the antenna array depending on the plurality of received orthogonal uplink pilot signals.

9. The method of claim 1 ,

wherein the first device comprises at least one of a base station of the cellular MIMO system or a user equipment of the cellular MIMO system, and

wherein the second device comprises at least one of a base station of the cellular MIMO system or a user equipment of the cellular MIMO system.

10. The method according to claim 9 , wherein the user equipment comprises at least one device of a group comprising:

a mobile telephone,

a mobile computer,

a tablet computer,

a wearable device, or

a mobile accessory.

11. The method of claim 1 , wherein the plurality of uplink pilot signals is sent from each antenna of the at least two antennas of the second device and/or received at the antenna array of the first device in an uplink payload section of a transmission frame.

12. A device for a cellular multiple-input and multiple-output, MIMO, system, the device comprising:

an antenna array comprising a plurality of antennas, and

a logic coupled to the antenna array and configured to

receive, at the antenna array, a signal resulting from transmission of an identical uplink pilot signal from each antenna of at least two antennas of a further device of the MIMO system, the identical uplink pilot signal being broadcasted from the further device from each antenna of the at least two antennas of the further device,

determine a first set of device receiving parameters for the antenna array depending on the received identical uplink pilot signal,

receive, from the further device, a plurality of orthogonal uplink pilot signals at the antenna array using the first set of device receiving parameters, and

determine for each received uplink pilot signal of the plurality of orthogonal uplink pilot signals a corresponding second set of device receiving parameters for the antenna array depending on the plurality of received orthogonal uplink pilot signals.

13. A device for a cellular multiple-input and multiple-output, MIMO, system, the device comprising:

at least two antennas, and

a logic coupled to the at least two antennas and configured to

broadcast an identical uplink pilot signal from each antenna of the at least two antennas using a single pilot signal resource, and

after broadcasting the identical uplink pilot signal, send from each antenna of the at least two antennas a corresponding uplink pilot signal of a plurality of uplink pilot signals, wherein the plurality of uplink pilot signals are orthogonal to each other.

14. A cellular multiple-input and multiple-output, MIMO, system, comprising:

a first device comprising:

an antenna array comprising a plurality of first antennas, and

a logic coupled to the antenna array;

a second device comprising:

at least two second antennas, and

a logic coupled to the at least two second antennas;

wherein the first device is configured to perform operations comprising:

receiving, at the antenna array, a signal resulting from transmission of an identical uplink pilot signal from each of the at least two second antennas of the second device of the MIMO system, the same uplink pilot signal being broadcasted from the second device from each antenna of the at least two second antennas of the second device,

determining a first set of device receiving parameters for the antenna array depending on the identical uplink pilot signal that was received,

receiving, from the second device, a plurality of uplink pilot signals at the antenna array using the first set of device receiving parameters, and

determining for each received uplink pilot signal of the plurality of uplink pilot signals a corresponding second set of device receiving parameters for the antenna array depending on the plurality of the uplink pilot signals that were received; and

wherein the second device is configured to perform operations comprising:

broadcasting the identical uplink pilot signal from each antenna of the at least two second antennas, and

sending from each antenna of the at least two second antennas a corresponding uplink pilot signal of the plurality of uplink pilot signals,

wherein the plurality of uplink pilot signals are orthogonal to each other.