Notifying a UL/DL configuration in LTE TDD systems

1. A method for configuring a Time Division Duplex (TDD) Uplink/Downlink (UL/DL) allocation of a user equipment (UE) in a Long Term Evolution (LTE) network, comprising:

receiving a TDD configuration change indicator, from an enhanced NodeB in the LTE network, on a Physical Downlink Control Channel (PDCCH), identifying a TDD configuration change associated with resource allocation between UL and DL for the UE, wherein receiving the TDD configuration change indicator includes:

detecting a downlink control information (DCI) message received on the PDCCH, the DCI message including one or more bits associated with a cyclic redundancy check (CRC), the CRC bits of the DCI message scrambled by a TDD-Radio Network Temporary Identifier (TDD-RNTI), the TDD-RNTI exclusively dedicated for TDD configuration information; and

descrambling the scrambled CRC based, at least in part, on the TDD-RNTI to identify the CRC bits and an associated payload;

identifying the TDD configuration change indicator in the associated payload; and

automatically updating the TDD UL/DL allocation of the UE in accordance with the TDD configuration change identified by the TDD configuration change indicator.

2. The method of claim 1 , further comprising determining a TDD UL/DL allocation corresponding to one of a plurality of TDD UL/DL configurations based on the received TDD configuration change indicator.

3. The method of claim 2 , further comprising determining the TDD UL/DL configuration corresponding to a value indicating a move-up or a move down in one of two TDD configuration groups.

4. The method of claim 3 , wherein the two TDD configuration groups include a first group having a first switching periodicity and a second group having a second switching periodicity longer than the first switching periodicity.

5. The method of claim 4 , wherein the first group and the second group are arranged in ascending order in terms of number of DL subframes.

6. The method of claim 4 , wherein the first switching periodicity is five milliseconds and the second switching periodicity is ten milliseconds.

7. The method of claim 1 , wherein the DCI message is received from a common search space of the PDCCH.

8. The method of claim 1 , wherein the TDD configuration change indicator identifies a specific TDD configuration.

9. The method of claim 1 , wherein the TDD configuration change indicator identifies a change in an existing TDD configuration.

10. The method of claim 1 , wherein the TDD configuration change associated with resource allocation between UL and DL comprises a change of numbers of UL subframes and DL subframes in a radio frame.

11. A user equipment comprising:

a processor configured to receive an indicator, from an enhanced NodeB in the LTE network, on a Physical Downlink Control Channel (PDCCH), identifying a time division duplex (TDD) configuration for the UE associated with resource allocation between UL and DL, wherein receiving the indicator includes:

detecting a downlink control information (DCI) message received on the PDCCH, the DCI message including one or more bits associated with a cyclic redundancy check (CRC), the CRC bits of the DCI message scrambled by a TDD-Radio Network Temporary Identifier (TDD-RNTI), the TDD-RNTI exclusively dedicated for TDD configuration information;

descrambling the scrambled CRC based, at least in part, on the TDD-RNTI to identify a CRC and an associated payload; and

identifying the TDD configuration indicator in the associated payload; and

the processor further configured to automatically update the TDD uplink (UL) and downlink (DL) allocation of the UE in accordance with the TDD configuration identified by the TDD configuration change indicator.

12. The user equipment of claim 11 , wherein the TDD configuration for the UE associated with resource allocation between UL and DL comprises a change of numbers of UL subframes and DL subframes in a radio frame.

13. A method for configuring a Time Division Duplex (TDD) Uplink/Downlink (UL/DL) allocation of a user equipment (UE) in a Long Term Evolution (LTE) network, comprising:

identifying a TDD configuration change associated with resource allocation between UL and DL, wherein identifying the TDD configuration change includes:

identifying a TDD configuration indicator, the TDD configuration indicator indicating a TDD configuration for a UE;

scrambling one or more bits associated with a cyclic redundancy check (CRC) of a downlink control information (DCI) message based, at least in part, on a TDD-Radio Network Temporary Identifier (TDD-RNTI), the TDD-RNTI exclusively dedicated for TDD configuration information; and

transmitting an indicator, from an enhanced NodeB in the LTE network, on a Physical Downlink Control Channel (PDCCH), identifying a TDD configuration for the UE, wherein transmitting the indicator includes transmitting the DCI message using the PDCCH.

14. The method of claim 13 , wherein the TDD configuration change associated with resource allocation between UL and DL comprises a change of numbers of UL subframes and DL subframes in a radio frame.

15. An apparatus for configuring a Time Division Duplex (TDD) UL/DL allocation of a user equipment (UE) in a Long Term Evolution (LTE) network, comprising:

a processor configured to identify a TDD configuration change associated with resource allocation between UL and DL, wherein identifying the TDD configuration change includes:

identifying a TDD configuration indicator, the TDD configuration indicator indicating a TDD configuration for a UE; and

scrambling one or more bits associated with a cyclic redundancy check (CRC) of a downlink control information (DCI) message based, at least in part, on a TDD-Radio Network Temporary Identifier (TDD-RNTI), the TDD-RNTI exclusively dedicated for TDD configuration information;

the processor further configured to transmit an indicator, from an enhanced NodeB in the LTE network, on a Physical Downlink Control Channel (PDCCH), identifying a TDD configuration for the UE, wherein transmitting the indicator includes transmitting the DCI message using the PDCCH.

16. The apparatus of claim 15 , wherein the TDD configuration change associated with resource allocation between UL and DL comprises a change of numbers of UL subframes and DL subframes in a radio frame.