CHANNEL QUALITY INDICATION FOR FALLBACK TRANSMISSION MODE OVER NEW CARRIER TYPE
A new carrier type (NCT) has been developed for LTE in order to reduce the overhead associated with cell-specific reference signals (CRS) and control signaling via the PDCCH. The NCT is an LTE carrier with minimized control channel overhead and cell-specific reference signals. Described herein are techniques where, upon receiving a PDSCH grant from a eNB using DCI format 1A to indicate a fallback transmission mode, a UE transmits a CQI to the eNB based upon CSI-RS resources contained in the NCT.
1 .- 24 . (canceled)
25 . A method for operating a user equipment (UE) in an LTE (Long Term Evolution) network, comprising:
communicating with an evolved Node B (eNB) over a New Carrier Type (NCT), wherein the NCT has a reduced density of cell-specific reference signals (CRSs) as compared with a legacy carrier;
receiving grants of physical downlink shared channel (PDSCH) resources via control channel signaling with DCI (downlink control information) format 2C;
reporting to the eNB channel state information (CSI) that includes a channel quality indication (CQI) but includes neither a precoding matrix indication (PMI) nor a rank indication (RI); and
upon receiving a PDSCH grant from the eNB using DCI format 1A to indicate a fallback transmission mode with transmission of the PDSCH over a single DMRS (demodulation reference signal) port, transmitting a CQI to the eNB based upon CSI-RS (channel state information reference signal) resources contained in the NCT.
26 . The method of claim 25 further comprising, for purposes of computing the CQI during the fallback mode if the number of antenna ports of the associated CSI-RS resource is one, assuming that PDSCH transmissions are on a single DMRS port with the channel on the DMRS port being inferred from the channel on antenna port {15} of the associated CSI-RS resource.
27 . The method of claim 25 further comprising, for purposes of computing the CQI during the fallback mode if the number of antenna ports of the associated CSI-RS resource is two, assuming that PDSCH transmissions are received from the eNB using a transmit diversity transmission mode where the channels of the transmit diversity transmission mode are inferred from the channels on antenna ports {15, 16} of the associated CSI-RS resource.
28 . The method of claim 25 further comprising, for purposes of computing the CQI during the fallback mode if the number of antenna ports of the associated CSI-RS resource is four, assuming that PDSCH transmissions are received from the eNB using a transmit diversity transmission mode where the channels of the transmit diversity transmission mode on antenna ports {0, 1, 2, 3} are inferred from the channels on antenna ports {15, 16, 17, 18} of the associated CSI-RS resource.
29 . The method of claim 25 further comprising, for purposes of computing the CQI during the fallback mode, assuming that PDSCH transmissions received from the eNB on the single DMRS port are equivalent to corresponding symbols transmitted on antenna ports {15, . . . 14 +P}, as given by
[
y
(
15
)
(
i
)
⋮
y
(
14
+
P
)
(
i
)
]
=
W
(
i
)
x
(
i
)
,
where modulation symbols d (q) (0), . . . , d (q) (M symb (q) −1) for codeword q are mapped onto the layers x(i)=[x (0) (i) . . . x (ν-1) (i)] T , i=0, 1, . . . , M symb layer −1, where ν is the number of layers and M symb layer is the number of modulation symbols per layer, Pε{1,2,4,8} is the number of antenna ports of the associated CSI-RS resource, and W(i) is a precoding matrix.
30 . The method of claim 29 wherein, if P=1, W(i)=1.
31 . The method of claim 29 wherein, if P>1, W(i) is a precoding matrix selected by the UE.
32 . The method of claim 29 wherein, if P>1, W(i) is a predefined precoding matrix.
33 . A user equipment (UE) for operating in an LTE (Long Term Evolution) network, comprising:
processing circuitry and a radio interface for communicating with an evolved Node B (eNB) wherein the processing circuitry is to:
communicate with an evolved Node B (eNB) over a New Carrier Type (NCT), wherein the NCT has a reduced density of cell-specific reference signals (CRSs) as compared with a legacy carrier;
receive grants of physical downlink shared channel (PDSCH) resources via control channel signaling with DCI (downlink control information) format 2C;
report to the eNB channel state information (CSI) that includes a channel quality indication (CQI) but includes neither a precoding matrix indication (PMI) nor a rank indication (RI);
upon receiving a PDSCH grant from the eNB using DCI format 1A to indicate a fallback transmission mode with transmission of the PDSCH over a single DMRS (demodulation reference signal) port, transmit a CQI to the eNB based upon CSI-RS (channel state information reference signal) resources contained in the NCT.
34 . The UE of claim 33 wherein, for purposes of computing the CQI during the fallback mode if the number of antenna ports of the associated CSI-RS resource is one, the processing circuitry is to assume that PDSCH transmissions are on a single DMRS port with the channel on the DMRS port being inferred from the channel on antenna port {15} of the associated CSI-RS resource.
35 . The UE of claim 33 wherein, for purposes of computing the CQI during the fallback mode if the number of antenna ports of the associated CSI-RS resource is two, the processing circuitry is to assume that PDSCH transmissions are received from the eNB using a transmit diversity transmission mode where the channels of the transmit diversity transmission mode are inferred from the channels on antenna ports {15, 16} of the associated CSI-RS resource.
36 . The UE of claim 33 wherein, for purposes of computing the CQI during the fallback mode if the number of antenna ports of the associated CSI-RS resource is four, the processing circuitry is to assume that PDSCH transmissions are received from the eNB using a transmit diversity transmission mode where the channels of the transmit diversity transmission mode on antenna ports {0, 1, 2, 3} are inferred from the channels on antenna ports {15, 16, 17, 18} of the associated CSI-RS resource.
37 . The UE of claim 33 wherein, for purposes of computing the CQI during the fallback mode, the processing circuitry is to assume that PDSCH transmissions received from the eNB on the single DMRS port are equivalent to corresponding symbols transmitted on antenna ports {15, . . . 14 +P}, as given by
[
y
(
15
)
(
i
)
⋮
y
(
14
+
P
)
(
i
)
]
=
W
(
i
)
x
(
i
)
,
where modulation symbols d (q) (0), . . . , d (q) (M symb (q) −1) for codeword q are mapped onto the layers x(i)=[x (0) (i) . . . x (ν-1) (i)] T , i=0, 1, . . . , M symb layer −1, where ν is the number of layers and M symb layer is the number of modulation symbols per layer, Pε{1,2,4,8} is the number of antenna ports of the associated CSI-RS resource, and W(i) is a precoding matrix.
38 . The UE of claim 37 wherein, if P=1, W(i)=1.
39 . The UE of claim 37 wherein, if P>1, W(i) is a precoding matrix selected by the UE.
40 . The UE of claim 37 wherein, if P>1, W(i) is a predefined precoding matrix.
41 . An evolved Node B (eNB) for operating in an LTE (Long Term Evolution) network, comprising:
processing circuitry and a radio interface for communicating with a user equipment (UE), wherein the processing circuitry is to:
communicate with the UE over a New Carrier Type (NCT), wherein the NCT has a reduced density of cell-specific reference signals (CRSs) as compared with a legacy carrier;
transmit grants of physical downlink shared channel (PDSCH) resources via control channel signaling with DCI (downlink control information) format 2C;
configure the UE to report channel state information (CSI) that includes a channel quality indication (CQI) but includes neither a precoding matrix indication (PMI) nor a rank indication (RI);
if a PDSCH grant is transmitted to the UE using DCI format 1A to indicate a fallback transmission mode, transmit the PDSCH over a single DMRS (demodulation reference signal) port, and assume that the CQI received from the UE is based upon CSI-RS (channel state information reference signal) resources contained in the NCT.
42 . The eNB of claim 41 wherein the processing circuitry is to assume that the UE, for purposes of computing the CQI during the fallback mode if the number of antenna ports of the associated CSI-RS resource is one, assumes that PDSCH transmissions are on a single DMRS port with the channel on the DMRS port being inferred from the channel on antenna port {15} of the associated CSI-RS resource.
43 . The eNB of claim 41 wherein the processing circuitry is to assume that the UE, for purposes of computing the CQI during the fallback mode if the number of antenna ports of the associated CSI-RS resource is two, assumes that PDSCH transmissions are received from the eNB using a transmit diversity transmission mode where the channels of the transmit diversity transmission mode are inferred from the channels on antenna ports {15, 16} of the associated CSI-RS resource.
44 . The eNB of claim 41 wherein the processing circuitry is to assume that the UE, for purposes of computing the CQI during the fallback mode if the number of antenna ports of the associated CSI-RS resource is four, assumes that PDSCH transmissions are received from the eNB using a transmit diversity transmission mode where the channels of the transmit diversity transmission mode on antenna ports {0, 1, 2, 3} are inferred from the channels on antenna ports {15, 16, 17, 18} of the associated CSI-RS resource.
45 . The eNB of claim 41 wherein the processing circuitry is to assume that the UE, for purposes of computing the CQI during the fallback mode, assumes that PDSCH transmissions received from the eNB on the single DMRS port are equivalent to corresponding symbols transmitted on antenna ports {15, . . . 14 +P}, as given by
[
y
(
15
)
(
i
)
⋮
y
(
14
+
P
)
(
i
)
]
=
W
(
i
)
x
(
i
)
,
where modulation symbols d (q) (0), . . . , d (q) (M symb (q) −1) for codeword q are mapped onto the layers x(i)=[x (0) (i) . . . x (ν-1) (i)] T , i=0, 1, . . . , M symb layer −1, where ν is the number of layers and M symb layer is the number of modulation symbols per layer, Pε{1,2,4,8} is the number of antenna ports of the associated CSI-RS resource, and W(i) is a precoding matrix.
46 . The eNB of claim 45 wherein, if P=1, W(i)=1.
47 . The eNB of claim 45 wherein, if P>1, W(i) is a precoding matrix selected by the UE.
48 . The eNB of claim 45 wherein, if P>1, W(i) is a predefined precoding matrix.