Methods to signal current mimo rx antenna configuration status

Patent metadata

Field	Value
Publication number	US-2016226709-A1
Application number	US-201615007444-A
Country	US
Kind code	A1
Filing date	Jan 27, 2016
Priority date	Jan 29, 2015
Publication date	Aug 4, 2016
Grant date	—

Abstract

In MIMO wireless communication networks, receiver MIMO antenna parameters are not static over time. For example, the MIMO channel correlation is higher for high frequency bands than for low frequency bands. This variability of the receiver antenna parameters introduces uncertainty based the reported CSI (e.g., CQI, PMI, RI) if the network uses only static assumptions for such antenna parameter values. In embodiments, the UE determines the current status of its receive antenna parameters—such as number, configuration, correlation, and power imbalance—and transmits this information to the network (e.g., serving BS). The network node then based on the received information performs one or more radio operational tasks leading to more efficient use of radio resources and enhanced system performance.

First claim

What is claimed is:

1 . A method, performed by a user equipment (UE) having a plurality of receive antennas and being operative in a wireless communication network implementing Multiple Input, Multiple Output (MIMO) transmissions, of apprising the network of dynamically changing antenna parameters, comprising, for each active frequency band on which the UE is operating:
performing an action selected from the group consisting of obtaining information whether the receive antennas are configured as a Uniform Linear Array (ULA) or as Cross Polarized (Xpol), determining a correlation among the receive antennas, and determining a power imbalance among the receive antennas; and transmitting information to the network indicative of at least one of the receive antenna configuration, correlation, and power imbalance.

2 . The method of claim 1 further comprising determining, for each active frequency band, the number of active receive antennas, and transmitting information to the network indicative of the number of active receive antennas per frequency band.

3 . The method of claim 1 wherein obtaining information whether the receive antennas are configured as a ULA or as Xpol comprises reading the receive antenna configuration from memory.

4 . The method of claim 1 wherein determining a correlation among the receive antennas comprises reading from memory a first correlation value for the active frequency band.

5 . The method of claim 4 wherein determining the correlation among the receive antennas comprises performing two-stage MIMO Over The Air (OTA) measurement to obtain a second correlation value.

6 . The method of claim 5 wherein the correlation among the receive antennas is determined according to
Y=α 1 Y 1 +α 2 Y 2 subject to α 1 +α 2 =1 where

Y is the correlation among the receive antennas reported to the network;
Y 1 is the first correlation value read from memory;
Y 2 is the second correlation value determined from a two-step MIMO OTA measurement; and
α 1 and α 2 are weighting factors indicating confidence in the first and second correlation values, respectively.

7 . The method of claim 1 wherein determining the power imbalance among the receive antennas comprises estimating received signal quality per receive antenna, and comparing one or more of the per-antenna signal qualities and per-antenna signal powers to ascertain the power imbalance among the receive antennas.

8 . The method of claim 1 wherein transmitting information to the network indicative of at least one of the receive antenna configuration, correlation, and power imbalance comprises periodically transmitting the information to the network.

9 . The method of claim 8 wherein periodically transmitting the information to the network comprises transmitting the information to the network at a periodicity determined by a frame structure of the network protocol.

10 . The method of claim 1 wherein transmitting information to the network indicative of at least one of the receive antenna configuration, correlation, and power imbalance comprises transmitting the information to the network when the value of one or more of the receive antenna configuration, correlation, and power imbalance has changed more than a predetermined amount.

11 . The method of claim 1 wherein transmitting information to the network indicative of at least one of the receive antenna configuration, correlation, and power imbalance comprises transmitting the information to the network in response to receiving a request from the network for the information.

12 . The method of claim 1 wherein transmitting information to the network indicative of at least one of the receive antenna configuration, correlation, and power imbalance comprises transmitting the information to the network in one of a Radio Resource Control (RRC) message and a Media Access Control (MAC) layer message.

13 . The method of claim 1 wherein transmitting information to the network indicative of at least one of the receive antenna configuration, correlation, and power imbalance comprises transmitting the information to the network in unused or reserved bits of an uplink control message.

14 . A method, performed by a network node operative in a wireless communication network implementing Multiple Input, Multiple Output (MIMO) transmissions, of adjusting to dynamically changing user equipment (UE) antenna parameters, comprising, for each active frequency band on which the UE is operating:
receiving from the UE information indicative of at least one of: a configuration, a correlation, and a power imbalance of receive antennas on the UE; and utilizing the UE receive antenna information to perform one or more radio operational or radio resource management tasks.

15 . The method of claim 14 wherein the network node tasks include adding an offset to a Channel Quality Indicator (CQI) reported by the UE in response to one or more of: the correlation and the power imbalance.

16 . The method of claim 14 wherein the network node tasks include adapting one or more of scheduling and link adaptation in response to the correlation.

17 . The method of claim 14 wherein the network node tasks include adapting MIMO transmission mode in response to the correlation or the power imbalance.

18 . The method of claim 14 further comprising transmitting to the UE a request for the UE information, and wherein receiving the UE information is done in response to the request.

19 . User equipment (UE) operative in a wireless communication network implementing Multiple Input, Multiple Output (MIMO) transmissions, comprising:
a plurality of receive antennas; memory; and a controller operatively connected to the memory and the receive antennas, and for each active frequency band on which the UE is communicating, operative to perform an action selected from the group consisting of
obtaining information whether the receive antennas are configured as a Uniform Linear Array (ULA) or as Cross Polarized (Xpol),
determining a correlation among the receive antennas, and
determining a power imbalance among the receive antennas; and
further operative to transmit information to the network indicative of at least one of the receive antenna configuration, correlation, and power imbalance.

20 . The UE of claim 19 wherein the controller is further operative to determine, for each active frequency band, the number of active receive antennas, and to transmit information to the network indicative of the number of active receive antennas per frequency band.

21 . The UE of claim 19 wherein the controller is operative to obtain the information whether the receive antennas are configured as a ULA or as Xpol by reading the receive antenna configuration from memory.

22 . The UE of claim 19 wherein the controller is operative to determine the correlation among the receive antennas by reading from memory a first correlation value for the active frequency band.

23 . The UE of claim 22 wherein the controller is operative to determine the correlation among the receive antennas by performing two-stage MIMO Over The Air (OTA) measurement to obtain a second correlation value.

24 . The UE of claim 23 wherein the controller is operative to determine the correlation among the receive antennas according to
Y=α 1 Y 1 +α 2 Y 2 subject to α 1 +α 2 =1 where

Y is the correlation among the receive antennas rep

Assignees

• Ericsson Telefon Ab L M

Inventors

• Chen Maomao
• Nordström Fredrik

Classifications

• H04L1/0003

  by switching between different modulation schemes · CPC title

• H04L1/0015

  characterised by the adaptation strategy · CPC title

• H04L1/0009

  by adapting the channel coding (H04L1/1812 takes precedence) · CPC title

• H04B7/066

  Combined feedback for a number of channels, e.g. over several subcarriers like in orthogonal frequency division multiplexing [OFDM] · CPC title

• H04B7/0413

  MIMO systems · CPC title