Precoding matrix set quality measurement and reporting

Patent metadata

Field	Value
Publication number	US-9496940-B2
Application number	US-201214356344-A
Country	US
Kind code	B2
Filing date	Sep 13, 2012
Priority date	Nov 7, 2011
Publication date	Nov 15, 2016
Grant date	Nov 15, 2016

Abstract

The invention relates to methods for determining the interference variability of a precoding matrix set, and the use of same for purposes of scheduling and precoding matrix set selection. The precoding matrix set used by an interferer base station is evaluated by the mobile terminal which experiences the intercell interference from the interferer base station. The mobile terminal is informed about the precoding matrices of the precoding matrix set used by the base station. The mobile terminal measures the radio channel to the interferer cell, and then estimates based on the measured radio channel and with the knowledge on the particular precoding matrices of the precoding matrix set, the interference variability of the precoding matrix set. The interference variability may be reported to the serving base station of the mobile terminal, and thus considered for scheduling decisions by the serving base station referring the mobile terminal.

First claim

The invention claimed is:

1. A method for determining a quality measure of at least one precoding matrix set usable for downlink data transmissions by an interferer base station in a mobile communication system, wherein a mobile terminal is located in the cell of a serving base station and experiences intercell interference from a neighbour cell controlled by the interferer base station, the method comprising the steps of:
informing the mobile terminal by the serving base station about the particular precoding matrices in the at least one precoding matrix set usable by the interferer base station,
measuring by the mobile terminal the current channel state of the channel between the interferer base station and the mobile terminal,
estimating by the mobile terminal the interference from each of the precoding matrices of the at least one precoding matrix set based on the measured current channel state, and
determining an interference variability of the at least one precoding matrix set as a quality measure for the at least one precoding matrix set based on the estimated precoding matrix interferences,
wherein the step of informing the mobile terminal about the particular precoding matrices in the at least one precoding matrix set:
is performed by using messages of the physical layer, the media access control layer or higher layers, and/or
informs about weighting information regarding the usage probability of each precoding matrix of the at least one precoding matrix set usable by the interferer base station, and the weighting information is used by the mobile terminal in the step of determining the interference variability of the at least one precoding matrix set.

2. The method according to claim 1 , further comprising the step of:
calculating a mean interference based on the estimated precoding matrix interferences, and including the calculated mean interference into the quality measure of the at least one precoding matrix set in addition to the interference variability, wherein preferably the weighting information is used by the mobile terminal in the step of calculating the mean interference.

3. The method according to claim 1 , wherein the interference variability is at least one of the following:
a standard deviation of the interference from all precoding matrices of the at least one precoding matrix set,
variance of the interference from all precoding matrices of the at least one precoding matrix set,
minimum and/or maximum interference of any of the precoding matrices of the at least one precoding matrix set,
range of the interferences from all precoding matrices of the at least one precoding matrix set, being preferably the difference between the maximum and minimum interference of any of the precoding matrices of the at least one precoding matrix set.

4. The method according to claim 1 , further comprising the steps of:
reporting the quality measure of the at least one precoding matrix set from the
mobile terminal to the serving base station, preferably within a channel quality report message, and
considering the reported quality measure of the at least one precoding matrix set for scheduling decisions at the serving base station.

5. The method according to claim 4 , wherein the serving base station:
schedules the mobile terminal for particular subframes of a radio frame based on the reported quality measure of the precoding matrix set, or
selects a modulation and coding scheme for a transmission to the mobile terminal based on the reported quality measure of the precoding matrix set.

6. The method according to claim 1 , wherein at least two precoding matrix sets are predefined one of which is to be used by the interferer base station, and the steps of informing, estimating and determining are performed for each of the at least two precoding matrix sets, the method further comprising the steps of:
determining by the mobile terminal a preferred precoding matrix set out of the at least two precoding matrix sets, based on the determined quality measure of the at least two precoding matrix sets, and reporting information on the preferred precoding matrix set from the mobile terminal over the serving base station to the interferer base station, or
reporting the determined quality measure of the at least two precoding matrix sets from the mobile terminal to the serving base station, and determining by the serving base station a preferred precoding matrix set out of the at least two precoding matrix sets, based on the reported quality measure of the at least two precoding matrix sets, and reporting information on the preferred precoding matrix set from the serving base station to the interferer base station, or
calculating by the mobile terminal a difference between the quality measures of the two precoding matrix sets, and reporting information on the difference from the mobile terminal to the serving base station, and determining by the serving base station a preferred precoding matrix set out of the at least two precoding matrix sets, based on the reported difference, and reporting information on the preferred precoding matrix set from the serving base station to the interferer base station.

7. The method according to claim 1 , wherein a radio frame of the communication system is divided into at least two subframe sets, and wherein for each subframe set of the radio frame a different precoding matrix set is configured at the interferer base station, and the steps of informing, estimating and determining are performed for each precoding matrix set, and the step of informing further comprises informing the mobile terminal about the correspondence of each precoding matrix set to a subframe set.

8. A mobile terminal for determining a quality measure of at least one precoding matrix set usable for downlink data transmissions by an interferer base station in a mobile communication system, wherein the mobile terminal is located in the cell of a serving base station and experiences intercell interference from a neighbour cell controlled by the interferer base station, the mobile terminal comprising:
a receiver adapted to receive information from the serving base station about the particular precoding matrices in the at least one precoding matrix set usable by the interferer base station,
a processor and the receiver adapted to measure the current channel state of the channel between the interferer base station and the mobile terminal,
the processor adapted to estimate the interference from each of the precoding matrices of the at least one precoding matrix set based on the measured current channel state, and
the processor adapted to determine an interference variability of the at least one precoding matrix set as a quality measure for the at least one precoding matrix set based on the estimated precoding matrix interferences,
wherein the received information about the particular precoding matrices in the at least one precoding matrix set:
is in messages of the physical layer, the media access control layer or higher layers, and/or
informs about weighting information regarding the usage probability of each precoding matrix of the at least one precoding matrix set usable by the interferer base station, and the weighting information is used when determining the interference variability of the at least one precoding matrix set.

9. The mobile terminal according to claim 8 , wherein the transmitter is adapted to report the quality measure of the at least one precoding matrix set to the serving base station, preferably within a channel quality report message.

10. The mobile terminal according to claim 8 , wherein at least two precoding matrix sets are predefined one of which is to be used by the interfe

Assignees

• Einhaus Michael
• Wengerter Christian
• Golitschek Edler Von Elbwart Alexander
• Hoshino Masayuki
• Panasonic Ip Corp America

Inventors

• Einhaus Michael
• Wengerter Christian
• Golitschek Edler Von Elbwart Alexander
• Hoshino Masayuki

Classifications

• H04B7/0639 Primary

  Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection · CPC title

• H04B7/0417

  Feedback systems · CPC title

• H04B7/0634

  Antenna weights or vector/matrix coefficients · CPC title

• H04B7/0665

  Feed forward of transmit weights to the receiver · CPC title

• H04B7/0632

  Channel quality parameters, e.g. channel quality indicator [CQI] · CPC title