DETERMINING CONFIGURATION OF SUBFRAMES IN A RADIO COMMUNICATIONS SYSTEM

• US 20110176461A1
• Filed: 11/12/2010
• Published: 07/21/2011
• Est. Priority Date: 12/23/2009
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktienbolaget L M Ericsson
• Inventors: Susitaival, Riikka, Parkvall, Stefan, ASTELY, David
• Application Number:
  US12/945,554
• Publication Number:
  US 20110176461A1
• Time in Patent Office: Days
• US Class Current: 370/280
• CPC Class Codes: H04B 7/2656 for structure of frame, burst
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames

Abstract

The technology disclosed provides the ability for a subframe to be configured as a “flexible” subframe. As a result, at least three different types of subframes in a TDD system may be configured: a downlink (“DL”) subframe, an uplink (“UL”) subframe, and a “flexible” subframe. The use of flexible subframes is determined based on a primary TDD configuration, and in a preferred example, on the existing primary TDD configuration in the network. If there is secondary TDD configuration, flexible subframes may be determined based on both the primary and secondary configurations, e.g., using specific rules. Also, the HARQ feedback timing for downlink (DL) transmissions may be determined based on the secondary TDD configuration. Preferred examples ensure that uplink (UL) feedback does not collide with a flexible subframe used for DL transmission. The technology preferably is compatible with legacy UEs.

Claims

1. A radio network node for use in a radio communications network using time division duplex (TDD) to communicate with user equipment (UE) radio terminals, comprising:

electronic circuitry configured to;

process data for a frame structure that includes one or more subframes preconfigured as downlink subframe, one or more subframes preconfigured as uplink subframes, and one or more flexible subframes each dynamically allocated to be an uplink subframe in one instance and a downlink subframe in another instance, and

determine how to interpret or use one or more of the flexible subframes based on a primary TDD configuration of the radio communications network;

radio receive circuitry configured to receive information sent by the radio terminal in a flexible subframe; and

radio transmit circuitry configured to transmit information in a downlink direction using a flexible subframe.

2. The radio network node in claim 1, wherein the primary TDD configuration is a current TDD configuration of the radio communications network and is used at least by legacy UE radio terminals.

3. The radio network node in claim 1, wherein the radio communications network includes a secondary TDD configuration and the electronic circuitry is configured to determine how to interpret or use one or more of the flexible subframes based on the primary and secondary TDD configurations.

4. The radio network node in claim 3, wherein the secondary TDD configuration includes more downlink subframes as compared to the primary TDD configuration.

5. The radio network node in claim 3, wherein the radio communications system is an LTE system and the primary and secondary TDD configurations are included in the existing TDD configurations for LTE.

6. The radio network node in claim 3, wherein if subframe n is a downlink subframe in the primary and the secondary TDD configuration, the electronic circuitry is configured to determine that the subframe is a downlink subframe, and wherein if subframe n is an uplink subframe in the primary and the secondary TDD configuration, the electronic circuitry is configured to determine that the subframe is an uplink subframe.

7. The radio network node in claim 3, wherein if subframe n is an uplink subframe in the primary TDD configuration and a downlink subframe in the secondary TDD configuration, the electronic circuitry is configured to determine that the subframe is a flexible subframe.

8. The radio network node in claim 3, wherein if subframe n is a downlink subframe in the primary TDD configuration and an uplink subframe in the secondary TDD configuration, the electronic circuitry is configured to determine that the subframe is a downlink subframe.

9. The radio network node in claim 3, wherein if a downlink transmission is transmitted in a downlink or flexible subframe n, the receive circuitry is configured to receive corresponding HARQ feedback signaling in an uplink subframe n+k of the secondary TDD configuration, where k is an offset based on HARQ feedback timing of the secondary TDD configuration.

10. The radio network node in claim 1, wherein the electronic circuitry is configured to use a grant timing of the primary TDD configuration for uplink subframes.

11. A radio terminal configured to communicate with a radio communications network using time division duplex (TDD), comprising:

electronic circuitry configured to;

process data for a frame structure that includes one or more downlink subframes preconfigured as a downlink subframe, one or more uplink subframes preconfigured as an uplink subframe, and one or more flexible subframes, where a flexible subframe is dynamically allocated to be an uplink subframe in one instance of a frame and a downlink subframe in another frame instance, and

determine how to interpret or use one or more of the flexible subframes based on a primary TDD configuration of the radio communications network;

receive circuitry configured to receive information sent by a base station in a flexible subframe; and

transmit circuitry configured to transmit information in an uplink direction using a flexible subframe.

12. The radio terminal in claim 11, wherein the primary TDD configuration is a current TDD configuration of the radio communications network and is used at least by legacy UE radio terminals.

13. The radio terminal in claim 11, wherein the radio communications network includes a secondary TDD configuration and the electronic circuitry is configured to determine how to interpret or use one or more of the flexible subframes based on the primary and secondary TDD configurations.

14. The radio terminal in claim 13, wherein the secondary TDD configuration includes more downlink subframes as compared to the primary TDD configuration.

15. The radio terminal in claim 13, wherein the radio communications system is an LTE system and the primary and secondary TDD configurations are included in the existing TDD configurations for LTE.

16. The radio terminal in claim 13, wherein if subframe n is a downlink subframe in the primary and the secondary TDD configuration, the electronic circuitry is configured to determine that the subframe is a downlink subframe, and wherein if subframe n is an uplink subframe in the primary and the secondary TDD configuration, the electronic circuitry is configured to determine that the subframe is an uplink subframe.

17. The radio terminal in claim 13, wherein if subframe n is an uplink subframe in the primary TDD configuration and a downlink subframe in the secondary TDD configuration, the electronic circuitry is configured to determine that the subframe is a flexible subframe.

18. The radio terminal in claim 13, wherein if subframe n is a downlink subframe in the primary TDD configuration and an uplink subframe in the secondary TDD configuration, the electronic circuitry is configured to determine that the subframe is a downlink subframe.

19. The radio terminal in claim 13, wherein if an uplink transmission is transmitted in an uplink or flexible subframe n, the receive circuitry is configured to receive corresponding HARQ feedback signaling in the downlink subframe n+k of the primary TDD configuration, where k is an offset based on HARQ feedback timing of the primary TDD configuration.

20. The radio network node in claim 13, wherein the electronic circuitry is configured so that HARQ feedback signaling for a downlink transmission from the radio network in a downlink or flexible subframe is transmitted to the radio network only in an uplink subframe and not in a flexible subframe.

21. The radio terminal in claim 13, wherein the electronic circuitry is configured so that HARQ feedback signaling for a downlink transmission from the radio network in an downlink or flexible subframe is transmitted to the radio network in a flexible subframe.

22. The radio terminal in claim 11, wherein the electronic circuitry is configured to transmit one or more of:

signaling for radio terminal channel-status reports, signaling for radio terminal uplink scheduling requests, radio terminal random access attempt signaling according to an uplink subframe, downlink subframe, and flexible subframe configuration for an uplink frame.

23. The radio terminal in claim 11, wherein the electronic circuitry is configured to avoid making and/or reporting radio signal quality measurements on received flexible subframes.

24. A method for communicating using subframes in a radio communications network that uses time division duplex (TDD) communications between a radio network node and a radio terminal, comprising one or both of the radio network node and the radio terminal performing the steps of:

processing data for a frame structure that includes one or more downlink subframes preconfigured as a downlink subframe, one or more uplink subframes preconfigured as an uplink subframe, and one or more flexible subframes, where a flexible subframe is dynamically allocated to be an uplink subframe in one instance of a frame and a downlink subframe in another frame instance;

determining how to interpret or use one or more of the flexible subframes based on a primary TDD configuration of the radio communications network;

receiving information sent in a flexible subframe; and

transmitting information in an uplink direction using a flexible subframe.

25. The method claim 24, wherein the radio communications network includes a secondary TDD configuration, and the determining step is based on the primary and secondary TDD configurations.

26. The method in claim 25, wherein:

if subframe n is a downlink subframe in the primary and the secondary TDD configuration, determining that the subframe is a downlink subframe;

if subframe n is an uplink subframe in the primary and the secondary TDD configuration, determining that the subframe is an uplink subframe;

if subframe n is an uplink subframe in the primary TDD configuration and a downlink subframe in the secondary TDD configuration, determining that the subframe is a flexible subframe; and

if subframe n is a downlink subframe in the primary TDD configuration and an uplink subframe in the secondary TDD configuration, determining that the subframe is a downlink subframe.

27. The radio method in claim 24, further comprising using a grant timing of the primary TDD configuration for uplink subframes.