Pilot resource allocation for a MIMO system

1. A method of allocating resources for a transmission of pilot signals of a plurality of terminals of a cellular multiple-input and multiple-output, MIMO, system, the cellular MIMO system comprising a base station having a plurality of antennas and a logic which analyzes pilot signals received from a terminal at the plurality of antennas to obtain information about a radio channel property of the radio channel between the terminal and the plurality of antennas, the method comprising:

determining, by the base station, whether the radio channel property between the terminal and the plurality of antennas is constant over a period of time, and

if the radio channel property between the terminal and the plurality of antennas is constant over a period of time:

configuring, by the base station, receiving parameters of the plurality of antennas of the base station for nulling pilot signals from the terminal, and

allocating a resource, which is assigned to the terminal for a transmission of pilot signals of the terminal, to another terminal for a transmission of pilot signals of the other terminal during the nulling pilot signals from the terminal.

2. The method according to claim 1 , wherein determining, by the base station, whether the radio channel property between the terminal and the plurality of antennas is constant over a period of time, comprises:

receiving, at the base station, a movement information from the terminal, the movement information indicating whether the terminal is moving or is stationary, and

determining that the radio channel property between the terminal and the plurality of antennas is constant over a period of time depending on the movement information.

3. The method according to claim 1 , wherein determining, by the base station, whether the radio channel property between the terminal and the plurality of antennas is constant over a period of time, comprises:

receiving, at the base station, a constant channel information from a further base station, the constant channel information indicating that a radio channel property between the terminal and a plurality of antennas of the further base station is constant over a period of time, and

determining that the radio channel property between the terminal and the plurality of antennas of the base station is constant over a period of time depending on the constant channel information.

4. The method according to claim 1 , wherein determining, by the base station, whether the radio channel property between the terminal and the plurality of antennas is constant over a period of time, comprises:

determining, by the base station, a temporal rate of change information, the temporal rate of change information indicating a rate of change of the radio channel property of the channel between the terminal and the plurality of antennas, and

determining that the radio channel property between the terminal and the plurality of antennas is constant over a period of time if the temporal rate of change information is varying less than a predefined amount over at least a predefined period of time.

5. The method according to claim 4 , wherein determining, by the base station, the temporal rate of change information comprises:

receiving, at the base station, a plurality of pilot signals from the terminal in a temporal sequence,

determining, by the base station, a plurality of radio channel properties, wherein each radio channel property of the plurality of radio channel properties is associated to a corresponding pilot signal of the plurality of pilot signals, wherein each radio channel property is determined based on its associated pilot signal, and

determining, by the base station, the temporal rate of change information of the radio channel property based on the plurality of radio channel properties.

6. The method according to claim 1 , wherein configuring the receiving parameters of the plurality of antennas of the base station for nulling pilot signals from the terminal comprises:

combining and/or filtering signals from the plurality of antennas for cancelling the pilot signal received from the terminal.

7. The method according to claim 1 , further comprising if the radio channel property between the terminal and the plurality of antennas is constant over a period of time:

transmitting, by the base station, a further constant channel information to a further base station, the further constant channel information indicating that the radio channel property between the terminal and the plurality of antennas of the base station is constant over a period of time.

8. A method of allocating resources for a transmission of pilot signals of a plurality of terminals of a cellular multiple-input and multiple-output, MIMO, system, the cellular MIMO system comprising a base station having a plurality of antennas and a logic which analyzes pilot signals received from a terminal at the plurality of antennas to obtain information about a radio channel property of the radio channel between the terminal and the plurality of antennas, the method comprising:

determining, by the base station, whether the radio channel property between the terminal and the plurality of antennas is constant over a period of time, and

if the radio channel property between the terminal and the plurality of antennas is constant over a period of time:

transmitting, by the base station, a constant channel information to a further base station, the constant channel information indicating that the radio channel property between the terminal and the plurality of antennas of the base station is constant over a period of time suet′ indicating that a resource assigned to the terminal for a transmission of pilot signals is reusable by the further base station for another terminal, and

configuring, by the base station, receiving parameters of the plurality of antennas of the base station for nulling pilot signals from the terminal while reusing the resource by the further base station for another terminal.

9. The method according to claim 8 , wherein determining, by the base station, whether the radio channel property between the terminal and the plurality of antennas is constant over a period of time, comprises:

receiving, at the base station, a movement information from the terminal, the movement information indicating whether the terminal is moving or is stationary, and

determining that the radio channel property between the terminal and the plurality of antennas is constant over a period of time depending on the movement information.

10. The method according to claim 8 , wherein determining, by the base station, whether the radio channel property between the terminal and the plurality of antennas is constant over a period of time, comprises:

determining, by the base station, a temporal rate of change information, the temporal rate of change information indicating a rate of change of the radio channel property of the channel between the terminal and the plurality of antennas, and

determining that the radio channel property between the terminal and the plurality of antennas is constant over a period of time if the temporal rate of change information is varying less than a predefined amount over a predefined period of time.

11. The method according to claim 10 , wherein determining, by the base station, the temporal rate of change information comprises:

receiving, at the base station, a plurality of pilot signals from the terminal in a temporal sequence,

determining, by the base station, a plurality of radio channel properties, wherein each radio channel property of the plurality of radio channel properties is associated to a corresponding pilot signal of the plurality of pilot signals, wherein each radio channel property is determined based on its associated pilot signal, and

determining, by the base station, the temporal rate of change information of the radio channel property based on the plurality of radio channel properties.

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

a plurality of antennas, and

a logic coupled to the plurality of antennas and configured to

analyze pilot signals received from a terminal at the plurality of antennas to obtain information about a radio channel property between the terminal and the plurality of antennas,

determine whether the radio channel property between the terminal and the plurality of antennas is constant over a period of time, and

if the radio channel property between the terminal and the plurality of antennas is constant over a period of time:

configure receiving parameters of the plurality of antennas for nulling pilot signals from the terminal, and

allocate a resource, which is assigned to the terminal for the transmission of pilot signals of the terminal, to another terminal for a transmission of pilot signals of the other terminal during the nulling pilot signals from the terminal.

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

a plurality of antennas; and

a logic coupled to the plurality of antennas and configured to

analyze pilot signals received from a terminal at the plurality of antennas to obtain information about a radio channel property between the terminal and the plurality of antennas,

determine whether the radio channel property between the terminal and the plurality of antennas is constant over a period of time, and

if the radio channel property between the terminal and the plurality of antennas is constant over a period of time:

transmit a constant channel information to a further base station, the constant channel information indicating that the radio channel property between the terminal and the plurality of antennas of the base station is constant over a period of time indicating that a resource assigned to the terminal for a transmission of pilot signals is reusable by the further base station for another terminal, and

configure, by the base station, receiving parameters of the plurality of antennas of the base station for nulling pilot signals from the terminal while reusing the resource by the further base station for another terminal.