Enhanced PDCCH with transmit diversity in LTE systems
A method is provided for communication in a wireless telecommunications network. The method comprises transmitting an extended physical downlink control channel to a user equipment using transmit diversity from at least one demodulation reference signal port.
1. A method for communication in a wireless telecommunications network, comprising:
transmitting an extended physical downlink control channel (E-PDCCH) to a user equipment (UE) using transmit diversity from at least one demodulation reference signal (DMRS) port.
2. The method of claim 1 , wherein the DMRS port uses the same set of resource elements to carry a reference signal as those DMRS ports defined in Release 10 of the Third Generation Partnership Project Long Term Evolution standards.
3. The method of claim 1 , wherein the transmit diversity is at least one of:
space-frequency block code (SFBC);
hybrid SFBC and space-time block code (STBC); or
channel independent beamforming.
4. The method of claim 3 , wherein channel independent beamforming is achieved by applying a precoding operation on modulated E-PDCCH symbols before the modulated E-PDCCH symbols are transmitted over at least two antennas, and wherein the precoding operation comprises applying one precoding vector to a modulated E-PDCCH symbol.
5. The method of claim 4 , wherein different precoding vectors are used for different modulated symbols or different groups of modulated symbols of the E-PDCCH in a physical resource block pair.
6. The method of claim 5 , wherein the different groups of modulated symbols of the E-PDCCH are transmitted on different DMRS ports.
7. The method of claim 1 , wherein transmission using transmit diversity is assumed for an E-PDCCH transmission when at least two DMRS ports are configured in a physical resource block pair for the E-PDCCH.
8. The method of claim 1 , wherein the use of transmit diversity for an E-PDCCH transmission is explicitly signaled to the UE.
9. The method of claim 1 , wherein modulated symbols of the E-PDCCH are mapped to resource elements in at least one physical resource block pair using at least one of:
space frequency block code (SFBC)-based mapping;
hybrid SFBC and space time block code (STBC)-based mapping; or
symbol-by-symbol based mapping to a time-and-frequency resource following a pre-defined rule for channel independent beamforming.
10. The method of claim 1 , wherein, when the UE is within the coverage areas of at least two transmission points, an E-PDCCH is transmitted from at least two of the transmission points using at least one of:
transmit diversity;
beamforming; or
combined transmit diversity and beamforming.
11. An access node in a wireless telecommunications network, comprising:
a processor configured such that the access node transmits an extended physical downlink control channel (E-PDCCH) to a user equipment (UE) using transmit diversity from at least one demodulation reference signal (DMRS) port.
12. The access node of claim 11 , wherein the DMRS port uses the same set of resource elements to carry a reference signal as those DMRS ports defined in Release 10 of the Third Generation Partnership Project Long Term Evolution standards.
13. The access node of claim 11 , wherein the transmit diversity is at least one of:
space-frequency block code (SFBC);
hybrid SFBC and space-time block code (STBC); or
channel independent beamforming.
14. The access node of claim 13 , wherein channel independent beamforming is achieved by applying a precoding operation on modulated E-PDCCH symbols before the modulated E-PDCCH symbols are transmitted over at least two antennas, and wherein the precoding operation comprises applying one precoding vector to a modulated E-PDCCH symbol.
15. The access node of claim 14 , wherein different precoding vectors are used for different modulated symbols or different groups of modulated symbols of the E-PDCCH in a physical resource block pair.
16. The access node of claim 15 , wherein the different groups of modulated symbols of the E-PDCCH are transmitted on different DMRS ports.
17. The access node of claim 11 , wherein transmission using transmit diversity is assumed for an E-PDCCH transmission when at least two DMRS ports are configured in a physical resource block pair for the E-PDCCH.
18. The access node of claim 11 , wherein the use of transmit diversity for an E-PDCCH transmission is explicitly signaled to the UE.
19. The access node of claim 11 , wherein modulated symbols of the E-PDCCH are mapped to resource elements in at least one physical resource block pair using at least one of:
space frequency block code (SFBC)-based mapping;
hybrid SFBC and space time block code (STBC)-based mapping; or
symbol-by-symbol based mapping to a time-and-frequency resource following a pre-defined rule for channel independent beamforming.
20. The access node of claim 11 , wherein, when the UE is within the coverage areas of at least two transmission points, an E-PDCCH is transmitted from at least two of the transmission points using at least one of:
transmit diversity;
beamforming; or
combined transmit diversity and beamforming.
21. A user equipment (UE), comprising:
a processor configured such that the UE receives an extended physical downlink control channel (E-PDCCH) that was transmitted using transmit diversity from at least one demodulation reference signal (DMRS) port.
22. The UE of claim 21 , wherein the DMRS port uses the same set of resource elements to carry a reference signal as those DMRS ports defined in Release 10 of the Third Generation Partnership Project Long Term Evolution standards.
23. The UE of claim 21 , wherein the transmit diversity is at least one of:
space-frequency block code (SFBC);
hybrid SFBC and space-time block code (STBC); or
channel independent beamforming.
24. The UE of claim 23 , wherein, in the case of channel independent beamforming, the UE receives different modulated symbols or different groups of modulated symbols of the E-PDCCH in a physical resource block pair associated with different DMRS ports.
25. The UE of claim 21 , wherein transmit diversity is assumed for an E-PDCCH reception when at least two DMRS ports are configured in a physical resource block pair for the E-PDCCH.
26. The UE of claim 21 , wherein the use of transmit diversity for an E-PDCCH transmission is explicitly signaled to the UE.
27. The UE of claim 21 , wherein modulated symbols of the E-PDCCH are mapped to resource elements in at least one physical resource block pair using at least one of:
space frequency block code (SFBC)-based mapping;
hybrid SFBC and space time block code (STBC)-based mapping; or
symbol-by-symbol based mapping to a time-and-frequency resource following a pre-defined rule for channel independent beamforming.
28. The UE of claim 21 , wherein, when the UE is within the coverage areas of at least two transmission points, the UE receives the E-PDCCH from at least two of the transmission points, the E-PDCCH having been transmitting using at least one of:
transmit diversity;
beamforming; or
combined transmit diversity and beamforming.