Method, base station, and user equipment for communicating downlink control information
The application pertains to a method for communicating downlink control information. A base station maps an enhanced physical downlink control channel (E-PDCCH) sequentially to resource elements for transmitting the E-PDCCH in each orthogonal frequency division multiplexing (OFDM) symbol according to an order of OFDM symbols used by the E-PDCCH of a user equipment (UE). The E-PDCCH is sent to the UE from the base station by using the resource elements, where the E-PDCCH and a physical downlink shared channel (PDSCH) invoked by the E-PDCCH are frequency-division multiplexed. Because the E-PDCCH is mapped sequentially to resource elements for transmitting the E-PDCCH in each OFDM symbol according to an order of OFDM symbols used by the E-PDCCH of the UE, different control channel elements of E-PDCCHs at different aggregation levels will not include a same E-PDCCH modulation symbol, thereby ensuring that the UE judges a start position of the E-PDCCH correctly.
1. A method for transmitting downlink control information, comprising:
mapping, by a base station, an enhanced physical downlink control channel (E-PDCCH) of a user equipment device (UE) to resource elements allocated for transmitting the E-PDCCH, wherein the resource elements are in L enhanced control channel elements (eCCEs) allocated to the E-PDCCH, wherein L is an aggregation level and is greater than or equal to 1; and
transmitting, by the base station, the E-PDCCH to the UE by using the resource elements mapped with the E-PDCCH;
wherein one or more orthogonal frequency division multiplexing (OFDM) symbols are used by the E-PDCCH, and each OFDM symbol comprises one or more resource elements that are allocated for transmitting the E-PDCCH;
wherein mapping the E-PDCCH to the resource elements in the L eCCEs comprises:
following an order of the OFDM symbols, in each OFDM symbol, mapping the E-PDCCH to the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol;
wherein the E-PDCCH carries the downlink control information; and
wherein the E-PDCCH and a physical downlink shared channel (PDSCH) invoked by the E-PDCCH are frequency-division multiplexed.
2. The method according to claim 1 , wherein the order of the OFDM symbols is the order of the indexes of the OFDM symbols.
3. The method according to claim 1 , wherein the order of subcarriers is the order of the indexes of the subcarriers.
4. The method according to claim 1 , wherein mapping the E-PDCCH to the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol comprises:
mapping modulation symbols of the E-PDCCH with index numbers of j 0 +[0, . . . , N−1] sequentially to a set R of resource elements in the OFDM symbol, wherein the set R is a set of resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH in the OFDM symbol;
wherein j 0 is a start position of the modulation symbols of the E-PDCCH mapped in the OFDM symbol; N is the quantity of the resource elements in the set R; and L, N and j 0 are integers.
5. A method for receiving downlink control information, comprising:
receiving, by a user equipment device (UE), a downlink subframe from a base station; and
extracting, by the UE, the downlink control information carried in an enhanced physical downlink control channel (E-PDCCH) from resource elements allocated for transmitting the E-PDCCH in the downlink subframe,
wherein the resource elements are in L enhanced control channel elements (eCCEs) allocated to the E-PDCCH, L is an aggregation level and is greater than or equal to 1, one or more orthogonal frequency division multiplexing (OFDM) symbols are used by the E-PDCCH, and each OFDM symbol comprises one or more resource elements that are allocated for transmitting the E-PDCCH;
wherein extracting the downlink control information carried in the E-PDCCH from the resource elements in the L eCCEs comprises:
following an order of the OFDM symbols, in each OFDM symbol, extracting the E-PDCCH from the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol;
and wherein the E-PDCCH and a physical downlink shared channel (PDSCH) invoked by the E-PDCCH are frequency-division multiplexed.
6. The method according to claim 5 , wherein the order of the OFDM symbols is the order of the indexes of the OFDM symbols.
7. The method according to claim 5 , wherein the order of subcarriers is the order of the indexes of the subcarriers.
8. The method according to claim 5 , wherein extracting the E-PDCCH from the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol comprises:
extracting modulation symbols of the E-PDCCH with index numbers of j 0 +[0, . . . , N−1] sequentially from a set R of resource elements in the OFDM symbol, wherein the set R is a set of resource elements occupied by the L eCCEs and mapped with the modulation symbols of the E-PDCCH in the OFDM symbol;
wherein j 0 is a start position of the modulation symbols of the E-PDCCH mapped in the OFDM symbol; N is the quantity of the resource elements in the set R; and L, N and j 0 are integers.
9. A non-transitory computer-readable storage medium storing program codes thereon for use by a base station, wherein the program codes, when executed by the base station, cause the base station to perform a method that comprises:
mapping an enhanced physical downlink control channel (E-PDCCH) of a user equipment device (UE) to resource elements allocated for transmitting the E-PDCCH, wherein the resource elements are in L enhanced control channel elements (eCCEs) allocated to the E-PDCCH, wherein L is an aggregation level and is greater than or equal to 1; and
transmitting the E-PDCCH to the UE by using the resource elements mapped with the E-PDCCH,
wherein one or more orthogonal frequency division multiplexing (OFDM) symbols are used by the E-PDCCH, and each OFDM symbol comprises one or more resource elements that are allocated for transmitting the E-PDCCH;
wherein mapping the E-PDCCH to the resource elements in the L eCCEs comprises:
following an order of the OFDM symbols, in each OFDM symbol, mapping the E-PDCCH to the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol;
wherein the E-PDCCH carries downlink control information; and
wherein the E-PDCCH and a physical downlink shared channel (PDSCH) invoked by the E-PDCCH are frequency-division multiplexed.
10. The non-transitory computer-readable storage medium according to claim 9 , wherein the order of the OFDM symbols is the order of the indexes of the OFDM symbols.
11. The non-transitory computer-readable storage medium according to claim 9 , wherein the order of subcarriers is the order of the indexes of the subcarriers.
12. The non-transitory computer-readable storage medium according to claim 9 , wherein mapping the E-PDCCH to the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol comprises:
mapping modulation symbols of the E-PDCCH with index numbers of j 0 +[0, . . . , N−1] sequentially to a set R of resource elements in the OFDM symbol, wherein the set R is a set of resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH in the OFDM symbol;
wherein j 0 is a start position of the modulation symbols of the E-PDCCH mapped in the OFDM symbol; N is the quantity of the resource elements in the set R; and L, N and j 0 are integers.
13. A non-transitory computer-readable storage medium storing program codes thereon for use by a user equipment device (UE), wherein the program codes, when executed by the UE, cause the UE to perform a method that comprises:
receiving a downlink subframe from a base station; and
extracting downlink control information carried in an enhanced physical downlink control channel (E-PDCCH) from resource elements allocated for transmitting the E-PDCCH in the downlink subframe,
wherein the resource elements are in L enhanced control channel elements (eCCEs) allocated to the E-PDCCH, L is an aggregation level and is greater than or equal to 1, one or more orthogonal frequency division multiplexing (OFDM) symbols are used by the E-PDCCH, and each OFDM symbol comprises one or more resource elements that are allocated for transmitting the E-PDCCH;
wherein extracting the downlink control information carried in the E-PDCCH from the resource elements in the L eCCEs comprises:
following an order of the OFDM symbols, in each OFDM symbol, extracting the E-PDCCH from the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol;
and wherein the E-PDCCH and a physical downlink shared channel (PDSCH) invoked by the E-PDCCH are frequency-division multiplexed.
14. The non-transitory computer-readable storage medium according to claim 13 , wherein the order of the OFDM symbols is the order of the indexes of the OFDM symbols.
15. The non-transitory computer-readable storage medium according to claim 13 , wherein the order of subcarriers is the order of the indexes of the subcarriers.
16. The non-transitory computer-readable storage medium according to claim 13 , wherein extracting the E-PDCCH from the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol comprises:
extracting modulation symbols of the E-PDCCH with index numbers of j 0 +[0, . . . , N−1] sequentially from a set R of resource elements in the OFDM symbol, wherein the set R is a set of resource elements occupied by the L eCCEs and mapped with the modulation symbols of the E-PDCCH in the OFDM symbol;
wherein j 0 is a start position of the modulation symbols of the E-PDCCH mapped in the OFDM symbol; N is the quantity of the resource elements in the set R; and L, N and j 0 are integers.
17. A base station, comprising one or more processors, a transmitter, and a memory storing program instructions;
wherein the one or more processors are configured to execute the program instructions to:
map an enhanced physical downlink control channel (E-PDCCH) of a user equipment device (UE) to resource elements allocated for transmitting the E-PDCCH, wherein the resource elements are in L enhanced control channel elements (eCCEs) allocated to the E-PDCCH,
wherein L is an aggregation level and is greater than or equal to 1; and
wherein the transmitter is configured to:
transmit the E-PDCCH to the UE by using the resource elements mapped with the E-PDCCH;
wherein one or more orthogonal frequency division multiplexing (OFDM) symbols are used by the E-PDCCH, and each OFDM symbol comprises one or more resource elements that are allocated for transmitting the E-PDCCH;
wherein in mapping the E-PDCCH to resource elements in the L eCCEs, the one or more processors are configured to execute the program instructions to:
following an order of the OFDM symbols, in each OFDM symbol, map the E-PDCCH to the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol;
wherein the E-PDCCH carries downlink control information; and
wherein the E-PDCCH and a physical downlink shared channel (PDSCH) invoked by the E-PDCCH are frequency-division multiplexed.
18. The base station according to claim 17 , wherein the order of the OFDM symbols is the order of the indexes of the OFDM symbols.
19. The base station according to claim 17 , wherein the order of subcarriers is the order of the indexes of the subcarriers.
20. The base station according to claim 17 , wherein in mapping the E-PDCCH to the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol, the one or more processors are configured to execute the program instructions to:
map modulation symbols of the E-PDCCH with index numbers of j 0 +[0, . . . , N−1] sequentially to a set R of resource elements in the OFDM symbol, wherein the set R is a set of resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH in the OFDM symbol;
wherein j 0 is a start position of the modulation symbols of the E-PDCCH mapped in the OFDM symbol; N is the quantity of the resource elements in the set R; and L, N and j 0 are integers.
21. A user equipment device (UE), comprising one or more processors, a receiver, and a memory storing program instructions;
wherein the receiver is configured to receive a downlink subframe from a base station; and
wherein the one or more processors are configured to execute the program instructions to:
extract downlink control information carried in an enhanced physical downlink control channel (E-PDCCH) from resource elements allocated for transmitting the E-PDCCH in the downlink subframe;
wherein the resource elements are in L enhanced control channel elements (eCCEs) allocated to the E-PDCCH, L is an aggregation level and is greater than or equal to 1, one or more orthogonal frequency division multiplexing (OFDM) symbols are used by the E-PDCCH, and each OFDM symbol comprises one or more resource elements that are allocated for transmitting the E-PDCCH;
wherein in extracting the downlink control information carried in the E-PDCCH from the resource elements in the L eCCEs, the one or more processors are configured to execute the program instructions to:
following an order of the OFDM symbols, in each OFDM symbol, extract the E-PDCCH from the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol;
wherein the E-PDCCH and a physical downlink shared channel (PDSCH) invoked by the E-PDCCH are frequency-division multiplexed.
22. The UE according to claim 21 , wherein the order of the OFDM symbols is the order of the indexes of the OFDM symbols.
23. The UE according to claim 21 , wherein the order of subcarriers is the order of the indexes of the subcarriers.
24. The UE according to claim 21 , wherein in extracting the E-PDCCH from the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol, the one or more processors are configured to execute the program instructions to:
extract modulation symbols of the E-PDCCH with index numbers of j 0 +[0, . . . , N−1] sequentially from a set R of resource elements in the OFDM symbol, wherein the set R is a set of resource elements occupied by the L eCCEs and mapped with the modulation symbols of the E-PDCCH in the OFDM symbol;
wherein j 0 is a start position of the modulation symbols of the E-PDCCH mapped in the OFDM symbol; N is the quantity of the resource elements in the set R; and L, N and j 0 are integers.
25. An apparatus, implemented in a base station, comprising one or more processors and a memory storing program instructions for execution by the processors;
wherein by executing the program instructions, the one or more processors are configured to perform operations of:
mapping an enhanced physical downlink control channel (E-PDCCH) of a user equipment device (UE) to resource elements allocated for transmitting the E-PDCCH, wherein the resource elements are in L enhanced control channel elements (eCCEs) allocated to the E-PDCCH, wherein L is an aggregation level and is greater than or equal to 1; and
controlling the base station to transmit the E-PDCCH to the UE by using the resource elements mapped with the E-PDCCH;
wherein one or more orthogonal frequency division multiplexing (OFDM) symbols are used by the E-PDCCH, and each OFDM symbol comprises one or more resource elements that are allocated for transmitting the E-PDCCH;
wherein the operation of mapping the E-PDCCH to the resource elements in the L eCCEs comprises:
following an order of the OFDM symbols, in each OFDM symbol, mapping the E-PDCCH to the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol;
wherein the E-PDCCH carries downlink control information; and
wherein the E-PDCCH and a physical downlink shared channel (PDSCH) invoked by the E-PDCCH are frequency-division multiplexed.
26. The apparatus according to claim 25 , wherein the order of the OFDM symbols is the order of the indexes of the OFDM symbols.
27. The apparatus according to claim 25 , wherein the order of subcarriers is the order of the indexes of the subcarriers.
28. The apparatus according to claim 25 , wherein the operation of mapping the E-PDCCH to the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol comprises:
mapping modulation symbols of the E-PDCCH with index numbers of j 0 +[0, . . . , N−1] sequentially to a set R of resource elements in the OFDM symbol, wherein the set R is a set of resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH in the OFDM symbol;
wherein j 0 is a start position of the modulation symbols of the E-PDCCH mapped in the OFDM symbol; N is the quantity of the resource elements in the set R; and L, N and j 0 are integers.
29. An apparatus, implemented in a user equipment device (UE), comprising one or more processors and a memory storing program instructions for execution by the processors;
wherein, by executing the program instructions, the one or more processors are configured to perform operations of:
controlling the UE to receive a downlink subframe from a base station; and
extracting downlink control information carried in an enhanced physical downlink control channel (E-PDCCH) from resource elements allocated for transmitting the E-PDCCH in the downlink subframe;
wherein the resource elements are in L enhanced control channel elements (eCCEs) allocated to the E-PDCCH, L is an aggregation level and is greater than or equal to 1, one or more orthogonal frequency division multiplexing (OFDM) symbols are used by the E-PDCCH, and each OFDM symbol comprises one or more resource elements that are allocated for transmitting the E-PDCCH;
wherein the operation of extracting the downlink control information carried in the E-PDCCH from the resource elements in the L eCCEs comprises:
following an order of the OFDM symbols, in each OFDM symbol, extracting the E-PDCCH from the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol;
wherein the E-PDCCH and a physical downlink shared channel (PDSCH) invoked by the E-PDCCH are frequency-division multiplexed.
30. The apparatus according to claim 29 , wherein the order of the OFDM symbols is the order of the indexes of the OFDM symbols.
31. The apparatus according to claim 29 , wherein the order of subcarriers is the order of the indexes of the subcarriers.
32. The apparatus according to claim 29 , wherein the operation of extracting the E-PDCCH from the resource elements occupied by the L eCCEs and allocated for transmitting the E-PDCCH according to an order of subcarriers in the OFDM symbol comprises:
extracting modulation symbols of the E-PDCCH with index numbers of j 0 +[0, . . . , N−1] sequentially from a set R of resource elements in the OFDM symbol, wherein the set R is a set of resource elements occupied by the L eCCEs and mapped with the modulation symbols of the E-PDCCH in the OFDM symbol;
wherein j 0 is a start position of the modulation symbols of the E-PDCCH mapped in the OFDM symbol; N is the quantity of the resource elements in the set R; and L, N and j 0 are integers.