Method and Apparatus for Operation with Carrier Aggregation of Time Division Duplex Cells

• US 20140133369A1
• Filed: 07/24/2013
• Published: 05/15/2014
• Est. Priority Date: 11/09/2012
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Cheng, Jung-Fu, Frenne, Mattias, Furuskog, Johan, Larsson, Daniel
• Granted Patent: US 10,003,452 B2
• Time in Patent Office: Days
• US Class Current: 370/280
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission

Abstract

According to the network-side teachings herein, transmission adaptations taken with respect to a secondary serving cell provide improved operation in the context of serving a half-duplex wireless device having a carrier aggregation configuration involving primary and secondary cells with different Time Division Duplex (TDD) uplink/downlink configurations. Transmission adaptations are taken with respect to a normal downlink subframe in a secondary cell that is time-wise overlapped by a special subframe in the primary cell. Similarly, improved operations are obtained on the device-side according to reception adaptations taken with respect to normal downlink subframes in a secondary cell that are overlapped by special subframes in the primary cell. Non-limiting improvements include better channel estimation and link adaptation, improved scheduling, and revised timings for the transmission and reception of user or control data targeting the device.

Claims

1. A method at a network node in a wireless communication network comprising:

serving a half-duplex, Time Division Duplex (TDD) wireless device having a carrier aggregation configuration that includes a primary cell and a secondary cell having different Uplink/Downlink (UL/DL) configurations;

identifying a normal downlink subframe in the secondary cell as having a first portion overlapped by a downlink portion of a special subframe in the primary cell and a second portion overlapped by an uplink portion of the special subframe;

adapting transmission to the wireless device for the normal downlink subframe in the secondary cell, so that data targeted to the wireless device is not sent in the second portion of the normal downlink subframe.

2. The method of claim 1, wherein the wireless communication network comprises a Long Term Evolution (LTE) network, and wherein the special subframe and the normal downlink subframe comprise transmission subframes on primary and secondary LTE carriers in the primary and secondary cells, respectively.

3. The method of claim 1, wherein adapting transmission to the wireless device in the normal downlink subframe comprises limiting the transmission of user or control data to the first portion of the normal downlink subframe.

4. The method of claim 3, wherein limiting the transmission of user or control data to the first portion of the normal downlink subframe comprises at least temporarily switching the wireless device from an enhanced Physical Downlink Control Channel (ePDCHH) to a Physical Downlink Control Channel (PDCHH).

5. The method of claim 3, wherein limiting the transmission of user or control data to the first portion of the normal downlink subframe comprises limiting the number and position of symbols transmitted on an enhanced Physical Downlink Control Channel (ePDCCH) or on a Physical Downlink Shared Channel (PDSCH) to correspond with the length and position of the first portion of the normal downlink subframe.

6. The method of claim 1, wherein adapting transmission to the wireless device in the normal downlink subframe comprises selecting one or more transmission parameters based on the length and/or position of the first portion of the normal downlink subframe, rather than based on a full length of the normal downlink subframe.

7. The method of claim 6, wherein selecting the one or more transmission parameters includes selecting one or more of the following:

a transport block size, a modulation and coding scheme, and which Orthogonal Frequency Division Multiplex (OFDM) resource elements are used within the normal downlink subframe.

8. The method of claim 1, wherein adapting the transmission to the wireless device in the normal downlink subframe comprises treating the normal downlink subframe as if it were a special downlink subframe in the secondary cell, including assuming a special subframe configuration that corresponds to that used for special subframes in the primary or secondary cell, or according to a predefined pattern or rule.

9. The method of claim 1, wherein adapting transmission to the wireless device in the normal downlink subframe comprises adapting ongoing scheduling operations to avoid scheduling any Physical Downlink Shared Channel (PDSCH) transmission to the wireless device in the normal downlink subframe.

10. The method of claim 1, further comprising adapting the transmission of any Demodulation Reference Symbols (DMRS) for the wireless device in the normal downlink subframe to fall within the first portion of the normal downlink subframe, based on using a DMRS transmission pattern used for the special subframe in the primary cell, or used for special subframes in the secondary cell, or according to a predefined pattern or rule.

11. The method of claim 1, further comprising, for carrier aggregation configurations involving primary and secondary cells of different UL/DL configurations, logically treating half-duplex wireless devices as belonging to a first set of wireless devices and treating full-duplex wireless devices as belonging to a second set of wireless devices, and using radio blocks (RBs) from a first set of RBs to serve the first set of wireless devices and RBs from a second set of RBs to serve the second set of wireless devices.

12. A network node configured for use in a wireless communication network and comprising:

a communication interface configured for sending data to and receiving data from wireless devices operating in one or more cells of the wireless communication network;

a processing circuit that is operatively associated with the communication interface and, with respect to a half-duplex wireless device being served in a carrier aggregation configuration that includes a primary cell and a secondary cell having different Time Division Duplex (TDD) configurations, configured to;

identify a normal downlink subframe in the secondary cell as having a first portion overlapped by a downlink portion of a special subframe in the primary cell and a second portion overlapped by an uplink portion of the special subframe; and

adapt transmission to the wireless device for the normal downlink subframe, so that data targeted to the wireless device is not sent in the second portion of the normal downlink subframe.

13. The network node of claim 12, wherein the wireless communication network comprises a Long Term Evolution (LTE) network, the network node comprises an eNB associated with at least one of the primary and secondary cells, and the normal and special downlink subframes comprise transmission subframes on primary and secondary carriers.

14. A method in a half-duplex capable wireless device operating in a wireless communication network, said method comprising:

operating in a Time Division Duplex (TDD) mode having a carrier aggregation configuration that includes a primary cell and a secondary cell having different Uplink/Downlink (UL/DL) configurations;

identifying a normal downlink subframe in the secondary cell as having a first portion overlapped by a downlink portion of a special subframe in the primary cell and a second portion overlapped by an uplink portion of the special subframe; and

adapting reception for the normal downlink subframe in the secondary cell, based on treating the normal downlink subframe as an abbreviated downlink subframe having all user or control data targeted to the wireless device only within the first portion.

15. The method of claim 14, wherein the special subframe and the normal downlink subframe comprise subframes on primary and secondary LTE carriers in the primary and secondary cells, respectively.

16. The method of claim 14, wherein treating the normal downlink subframe as an abbreviated downlink subframe comprises limiting the reception of user data or control data to the first portion of the normal downlink subframe.

17. The method of claim 16, wherein limiting the reception of user data or control data to the first portion of the normal downlink subframe comprises at least temporarily switching from enhanced Physical Downlink Control Channel (ePDCCH) monitoring to Physical Downlink Control Channel (PDCCH) monitoring.

18. The method of claim 14, wherein adapting the reception for the normal downlink subframe in the secondary cell comprises assuming that one or more transmission parameters for the normal downlink subframe, in the secondary cell are set based on the length and/or position of the first portion of the normal downlink subframe, rather than based on a full length of the normal downlink subframe.

19. The method of claim 18, wherein the one or more transmission parameters include one or more of the following:

a transport block size, a modulation and coding scheme, and which Orthogonal Frequency Division Multiplex (OFDM) resource elements are used within the normal downlink subframe.

20. The method of claim 14, wherein adapting the reception for the normal downlink subframe in the secondary cell comprises treating the normal downlink subframe as if it were a special downlink subframe in the secondary cell, including assuming a special subframe configuration that corresponds to that used for special subframes in the primary or secondary cell, or according to a predefined pattern or rule.

21. The method of claim 14, wherein adapting the reception for the normal downlink subframe in the secondary cell comprising assuming that the transmission of any Demodulation Reference Symbols (DMRS) for the wireless device in the normal downlink subframe fall within the first portion of the normal downlink subframe, according to a DMRS transmission pattern used for the special subframe in the primary cell or used for special subframes in the secondary cell, or according to a predefined pattern or rule.

22. A half-duplex capable wireless device configured for operation in a wireless communication network, said wireless device comprising:

a communication interface configured to receive signals from the wireless communication network and to transmit signals to the wireless communication network; and

a processing circuit that is operatively associated with the communication interface and, for the case where the wireless device operates in a Time Division Duplex (TDD) mode having a carrier aggregation configuration that includes a primary cell and a secondary cell of the wireless communication network having different Uplink/Downlink (UL/DL) configurations, is configured to;

identify a normal downlink subframe in the secondary cell as having a first portion overlapped by a downlink portion of a special subframe in the primary cell and a second portion overlapped by an uplink portion of the special subframe; and

adapt reception for the normal downlink subframe in the secondary cell, based on treating the normal downlink subframe as an abbreviated downlink subframe having all user or control data targeted to the wireless device only within the first portion.

23. The wireless device of claim 22, wherein the processing circuit is configured to adapt reception for the normal downlink subframe based on at least temporarily switching from enhanced Physical Downlink Control Channel (ePDCCH) monitoring to Physical Downlink Control Channel (PDCCH) monitoring.

24. The wireless device of claim 22, wherein the processing circuit is configured to adapt reception for the normal downlink subframe in the secondary cell by assuming that one or more transmission parameters for the normal downlink subframe in the secondary cell are set based on the length and/or position of the first portion of the normal downlink subframe, rather than based on a full length of the normal downlink subframe.

25. The wireless device of claim 24, wherein the one or more transmission parameters include one or more of the following:

a transport block size, a modulation and coding scheme, and which Orthogonal Frequency Division Multiplex (OFDM) resource elements are used within the normal downlink subframe.

26. The wireless device of claim 22, wherein the processing circuit is configured to adapt reception for the normal downlink subframe in the secondary cell based on treating the normal downlink subframe as if it were a special downlink subframe in the secondary cell, including assuming a special subframe configuration that corresponds to that used for special subframes in the primary or secondary cell, or according to a predefined pattern or rule.

27. The wireless device of claim 22, wherein the processing circuit is configured to adapt reception for the normal downlink subframe in the secondary cell based on assuming that the transmission of any Demodulation Reference Symbols (DMRS) for the wireless device in the normal downlink subframe fall within the first portion of the normal downlink subframe, according to a DMRS transmission pattern used for the special subframe in the primary cell or used for special subframes in the secondary cell, or according to a predefined pattern or rule.