User equipment and method for transmitting a data stream to an evolved node b

Abstract

In a wireless network, a user equipment (UE) can communicate with an Evolved Node B (eNodeB). During at least some times, the UE transmits a data stream to the eNodeB, over one of several available antenna states on the UE. The antenna states can include one or more tuning states for each antenna port on the UE. At predetermined times, which can be periodic, the UE ceases transmission of the data stream, transmits a test signal sequentially over each of its antenna states, receives a signal back from the eNodeB indicating which of the antenna states provides the strongest signal, and switches to the indicated antenna state. After switching, the UE can resume transmission of the data stream over the indicated antenna state. In some examples, the UE can repeat the antenna tuning/retuning process periodically.

What is claimed is: 
     
         1 . An apparatus of a user equipment (UE), the apparatus comprising:
 memory; and   processing circuitry, the processing circuitry configured to:   encode a first portion of the data stream for transmission to the eNB over a first antenna of a plurality of antennas;   encode a test signal for sequential transmission to the eNB over a second antenna of the plurality of antennas, the test signal indicative of a tuning state of a plurality of tuning states for the second antenna;   in response to the test signal, decode a transmit (Tx) antenna selection indicator received from the eNB, the Tx antenna selection indicator indicating the second antenna of the plurality of antennas for use in subsequent transmissions; and   encode a second portion of the data stream for transmission to the eNB over the second antenna.   
     
     
         2 . The apparatus of  claim 1 , wherein the processing circuitry is further configured to:
 encode the test signal for transmission to the eNB as a sounding reference signal (SRS), the SRS indicative of one of a plurality of antenna states associated with the second antenna.   
     
     
         3 . The apparatus of  claim 2 , wherein an antenna state of the plurality of antenna states is a combination of one of the tuning states and an antenna of the plurality of antennas. 
     
     
         4 . The apparatus of  claim 2 , wherein the SRS is encoded for transmission within an antenna tuning subframe (ATSF). 
     
     
         5 . The apparatus of  claim 2 , wherein the processing circuitry is configured to:
 encode a plurality of additional test signals for transmission to the eNB, each of the additional test signals associated with a unique antenna state of the plurality of antenna states.   
     
     
         6 . The apparatus of  claim 1 , wherein the processing circuitry is configured to:
 decode a downlink control indicator (DCI) message received via a physical downlink control channel (PDCCH), the DCI message including the Tx antenna selection indicator.   
     
     
         7 . The apparatus of  claim 6 , wherein the DCI message comprises rank indicator (RI) and precoding matrix indicator (PMI) associated with the tuning state of the second antenna. 
     
     
         8 . The apparatus of  claim 6 , wherein the Tx antenna selection indicator is an SRS report within the DCI message. 
     
     
         9 . The apparatus of  claim 8 , wherein the SRS report is indicative of an antenna tuning subframe (ATSF) of a plurality of ATSFs transmitted by the UE, the ATSF associated with one of the plurality of tuning states for the second antenna of the plurality of antennas. 
     
     
         10 . The apparatus of  claim 1 , wherein the processing circuitry is further configured to encode the test signal for transmission using protocols of a physical layer. 
     
     
         11 . The apparatus of  claim 1 , wherein the tuning state of the plurality of tuning states is associated with at least one of a selectable impedance or a selectable aperture for the second antenna. 
     
     
         12 . The apparatus of  claim 1 , further comprising transceiver circuitry coupled to the processing circuitry and the plurality of antennas. 
     
     
         13 . An apparatus of an evolved Node-B (eNB), the apparatus comprising: memory; and processing circuitry, configured to:
 decode a plurality of test signals received from a user equipment (UE), wherein:   each test signal is associated with a corresponding antenna state of a plurality of antenna states for the UE; and   an antenna state of the plurality of antenna states is indicative of a transmit antenna of a plurality of UE transmit antennas and a tuning state of a plurality of tuning states;
 select an antenna state from the plurality of antenna states based on signal quality characteristics of the received plurality of test signals; and 
 encode the selected antenna state as a transmit (Tx) antenna selection indicator within a downlink control information (DCI) message for transmission to the UE. 
   
     
     
         14 . The apparatus of  claim 13 , wherein the processing circuitry is further configured to:
 decode the plurality of test signals as part of a corresponding plurality of antenna tuning subframes (ATSFs).   
     
     
         15 . The apparatus of  claim 14 , wherein the processing circuitry is further configured to:
 encode an identification of an ATSF of the plurality of ATSFs within the DCI message, wherein the ATSF corresponds to the selected antenna state.   
     
     
         16 . A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors of a user equipment (UE), the instructions to configure the one or more processors to cause the UE to:
 encode a plurality of test signals for sequential transmission to an evolved Node-B (eNB) using one of a corresponding plurality of antenna states, wherein an antenna state of the plurality of antenna states is indicative of an antenna of a plurality of transmit antennas and at least one tuning state for the antenna;   in response to the sequential transmission of the test signals, decode a transmit (Tx) antenna selection indicator received from the eNB, the Tx antenna selection indicator indicating a transmit antenna of the plurality of transmit antennas for use in subsequent transmissions, and   encode a data stream for transmission to the eNB over the indicated transmit antenna.   
     
     
         17 . The non-transitory computer-readable storage medium of  claim 16 , wherein the instructions further cause the UE to:
 encode the test signals for transmission to the eNB as sounding reference signals (SRSs), each SRS indicative of one of the plurality of antenna states associated with the transmit antennas.   
     
     
         18 . The non-transitory computer-readable storage medium of  claim 17 , wherein the instructions further cause the UE to:
 encode the SRSs for transmission to the eNB within a corresponding plurality of antenna tuning subframes (ATSFs).   
     
     
         19 . The non-transitory computer-readable storage medium of  claim 16 , wherein the instructions further cause the UE to:
 decode a downlink control indicator (DCI) message received via a physical downlink control channel (PDCCH), the DCI message including the Tx antenna selection indicator.   
     
     
         20 . The non-transitory computer-readable storage medium of  claim 19 , wherein the Tx antenna selection indicator is an SRS report within the DCI message.