Method and device for sending and detecting enhanced physical downlink control channel
Disclosed are a method and a device for sending and detecting an enhanced physical downlink control channel (E-PDCCH), relating to the field of wireless communications, and used for solving the problem of how to send downlink control information through the E-PDCCH. In the method, when a current subframe needs to send downlink control information to a terminal by adopting a frequency domain distributed transmission mode, a base station selects, according to the current aggregation level, at least one available distributed E-CCE in a distributed E-PDCCH time frequency resource area of the current subframe, and uses the selected distributed E-CCE to send the downlink control information to the terminal. The present application solves the problem of how to transmit downlink control information through the E-PDCCH.
1. A method for transmitting an Enhanced Physical Downlink Control Channel, E-PDCCH, wherein the method comprises:
when downlink control information needs to be transmitted to a User Equipment, UE, in a current sub-frame in a localized transmission mode, selecting, by a base station, at least one available localized Enhanced Control Channel Element, E-CCEs, in a localized E-PDCCH time-frequency resource region of the current sub-frame at a current aggregation level; and
transmitting, by the base station, the downlink control information to the UE in the selected localized E-CCE;
wherein the localized E-PDCCH time-frequency resource region comprises at least one E-PDCCH resource cluster, each of which consists of at least one Physical Resource Block, PRB, pair consecutive in frequency domain in the current sub-frame; and each E-PDCCH resource cluster comprises at least one localized E-CCE, and each localized E-CCE is a set of a part of Resource Elements, REs, in a PRB pair;
wherein transmitting, by the base station, the downlink control information to the UE in the selected localized E-CCE comprises:
determining, by the base station, a DMRS port corresponding to the selected localized E-CCE according to a correspondence relationship, between the localized E-CCE and the DMRS port, preset for the E-PDCCH resource cluster where the selected localized E-CCE is located, and transmitting a Reference Signal (RS) for demodulation to the UE via the determined DMRS port;
wherein when there are a plurality of localized E-CCEs selected, one of DMRS ports corresponding to the selected plurality of localized E-CCEs is selected in Equation 3 below, and the RS for demodulation is transmitted to the UE via the selected DMRS port:
n port =f ( n eCCE lowest +mod(RNTI, L ′)), Equation 3
wherein n port represents index of a port, L′ represents the number of localized E-CCEs occupied by localized E-PDCCHs in a PRB pair, n eCCE lowest represents serial number of one of the current L′ localized E-CCEs with a lowest serial number, and the function f( ) represents index of a DMRS port corresponding to serial number of a localized E-CCE, calculated in expression bracketed in Equation 3, derived according to the correspondence relationship.
2. The method according to claim 1 , wherein:
DMRS ports corresponding to localized E-CCEs in a (i+1)-th E-PDCCH resource cluster in the localized E-PDCCH time-frequency resource region result from cyclic shifting of DMRS ports corresponding to localized E-CCEs in a i-th E-PDCCH resource cluster, wherein i represents an integer ranging from 0 to N′−1 with N′ representing a total number of E-PDCCH resource clusters in the localized E-PDCCH time-frequency resource region;
wherein localized E-CCEs in each E-PDCCH resource cluster are numbered sequentially starting with 0 in an order of time-frequency resources.
3. A method for detecting an Enhanced Physical Downlink Control Channel, E-PDCCH, wherein the method comprises:
determining, by a User Equipment, UE, a localized E-PDCCH time-frequency resource region in a current sub-frame, and aggregation levels supported in a localized transmission mode; and
performing, by the UE, channel blind detection on at least one localized Enhanced Control Channel Elements, E-CCEs, in the localized E-PDCCH time-frequency resource region respectively at the respective aggregation levels supported in the localized transmission mode;
wherein the localized E-PDCCH time-frequency resource region comprises at least one E-PDCCH resource cluster, each of which consists of at least one Physical Resource Block, PRB, pair consecutive in frequency domain in the current sub-frame; and each E-PDCCH resource cluster comprises at least one localized E-CCE, and each localized E-CCE is a set of a part of Resource Elements, REs, in a PRB pair;
wherein performing channel blind detection on the localized E-CCE in the localized E-PDCCH time-frequency resource region comprises:
determining a DMRS port corresponding to the localized E-CCE in the localized E-PDCCH time-frequency resource region according to a correspondence relationship, between the localized E-CCE and the DMRS port, preset for the current E-PDCCH resource cluster, and demodulating the localized E-CCE using an RS transmitted via the determined DMRS port;
wherein when there are a plurality of localized E-CCEs in a localized E-PDCCH, one of DMRS ports corresponding to the plurality of localized E-CCEs is selected in Equation 3 below, and the plurality of localized E-CCEs are demodulated using an RS transmitted via the selected DMRS port:
n port =f ( n eCCE lowest +mod(RNTI, L ′)), Equation 3
wherein n port represents index of a port, L′ represents the number of localized E-CCEs lowest occupied by localized E-PDCCHs in a PRB pair, n eCCE lowest represents the serial number of one of the current L′ localized E-CCEs with a lowest serial number, and the function f( ) represents index of a DMRS port corresponding to serial number of a localized E-CCE, calculated in expression bracketed in Equation 3, derived according to the correspondence relationship.
4. The method according to claim 3 , wherein:
DMRS ports corresponding to localized E-CCEs in a (i+1)-th E-PDCCH resource cluster in the localized E-PDCCH time-frequency resource region result from cyclic shifting of DMRS ports corresponding to localized E-CCEs in a i-th E-PDCCH resource cluster, wherein i represents an integer ranging from 0 to N′−1 with N′ representing a total number of E-PDCCH resource clusters in the localized E-PDCCH time-frequency resource region;
wherein localized E-CCEs in each E-PDCCH resource cluster are numbered sequentially starting with 0 in an order of time-frequency resources.
5. A base station, wherein the base station comprises:
a resource selecting unit configured, when downlink control information needs to be transmitted to a User Equipment, UE, in a current sub-frame in a localized transmission mode, to select at least one available localized Enhanced Control Channel Element, E-CCE, in a localized Enhanced Physical Downlink Control Channel, E-PDCCH, time-frequency resource region of the current sub-frame at a current aggregation level; and
an information transmitting unit configured to transmit the downlink control information to the UE in the selected localized E-CCE;
wherein the localized E-PDCCH time-frequency resource region comprises at least one E-PDCCH resource cluster, each of which consist of at least one Physical Resource Block, PRB, pair consecutive in frequency domain in the current sub-frame; and each E-PDCCH resource cluster comprises at least one localized E-CCE, and each localized E-CCE is a set of a part of Resource Elements, REs, in a PRB pair;
wherein the information transmitting unit is configured:
to determine a DMRS port corresponding to the selected localized E-CCE according to a correspondence relationship, between the localized E-CCE and the DMRS port, preset for the E-PDCCH resource cluster wherein the selected localized E-CCE is located and to transmit a Reference Signal, RS, for demodulation to the UE via the determined DMRS port; and
when there are a plurality of localized E-CCEs selected, to select one of DMRS ports corresponding to the selected plurality of localized E-CCEs in Equation 3 below and to transmit the RS for demodulation to the UE via the selected DMRS port:
n port =f ( n eCCE lowest +mod(RNTI, L ′)) Equation 3
wherein n port represents the index of a port, L′ represents the number of localized E-CCEs occupied by localized E-PDCCHs in a PRB pair, n eCCE lowest represents the serial number of one of the current L′ localized E-CCEs with a lowest serial number, and the function f( ) represents index of a DMRS port corresponding to serial number of a localized E-CCE, calculated in expression bracketed in Equation 3, derived according to the correspondence relationship.
6. The base station according to claim 5 , wherein the information transmitting unit is configured to:
shift cyclically DMRS ports corresponding to localized E-CCEs in a i-th E-PDCCH resource cluster in the localized E-PDCCH time-frequency resource region resulting in DMRS ports corresponding to localized E-CCEs in a (i+1)-th E-PDCCH resource cluster, wherein i represents an integer ranging from 0 to N′−1 with N′ representing a total number of E-PDCCH resource clusters in the localized E-PDCCH time-frequency resource region;
wherein localized E-CCEs in each E-PDCCH resource cluster are numbered sequentially starting with 0 in an order of time-frequency resources.
7. A User Equipment, UE, wherein the UE comprises:
a determining unit is configured to determine a localized Enhanced Physical Downlink Control Channel, E-PDCCH, time-frequency resource region in a current sub-frame, and aggregation levels supported in a localized transmission mode; and
a blind detection unit is configured to perform channel blind detection on at least one localized Enhanced Control Channel Element, E-CCE, in the localized E-PDCCH time-frequency resource region respectively at the respective aggregation levels supported in the localized transmission mode to obtain downlink control information;
wherein the localized E-PDCCH time-frequency resource region comprises at least one E-PDCCH resource cluster, each of which consists of at least one Physical Resource Block, PRB, pair consecutive in frequency domain in the current sub-frame; and each E-PDCCH resource cluster comprises at least one localized E-CCE, and each localized E-CCE is a set of a part of Resource Elements, REs, in a PRB pair;
wherein the blind detection unit is configured:
to perform channel blind detection on the localized E-CCE in the localized E-PDCCH time-frequency resource region is configured to determine a DMRS port corresponding to the localized E-CCE in the localized E-PDCCH time-frequency resource region according to a correspondence relationship, between the localized E-CCE and the DMRS port, preset for the current E-PDCCH resource cluster and to demodulate the localized E-CCE using an RS transmitted via the determined DMRS port; and
when there are a plurality of localized E-CCEs in a localized E-PDCCH, to select one of DMRS ports corresponding to the plurality of localized E-CCEs in Equation 3 below and to demodulate the plurality of localized E-CCEs using an RS transmitted via the selected DMRS port:
n port =f ( n eCCE lowest +mod(RNTI, L ′)), Equation 3
wherein n on represents index of a port, L′ represents the number of localized E-CCEs occupied by localized E-PDCCHs in a PRB pair, n eCCE lowest represents the serial number of one of the current L′ localized E-CCEs with a lowest serial number, and the function f( ) represents the index of a DMRS port corresponding to serial number of a localized E-CCE, calculated in the expression bracketed in Equation 3, derived according to the correspondence relationship.
8. The UE according to claim 7 , wherein the blind detection unit is configured to:
shift cyclically DMRS ports corresponding to localized E-CCEs in a i-th E-PDCCH resource cluster in the localized E-PDCCH time-frequency resource region resulting in DMRS ports corresponding to localized E-CCEs in a (i+1)-th E-PDCCH resource cluster, wherein i represents an integer ranging from 0 to N′−1 with N′ representing a total number of E-PDCCH resource clusters in the localized E-PDCCH time-frequency resource region;
wherein localized E-CCEs in each E-PDCCH resource cluster are numbered sequentially starting with 0 in an order of time-frequency resources.