REALIZING FDD CAPABILITY BY LEVERAGING EXISTING TDD TECHNOLOGY

• US 20090180408A1
• Filed: 01/11/2008
• Published: 07/16/2009
• Est. Priority Date: 01/11/2008
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Seymour, James, Graybeal, John
• Granted Patent: US 9,537,566 B2
• Time in Patent Office: Days
• US Class Current: 370/281
• CPC Class Codes: H04B 7/2615 using hybrid frequency-time division multiple access [FDMA-TDMA]
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04W 72/535 based on resource usage policies
• CPC Class Codes: H04W 84/042 Public Land Mobile systems, e.g. cellular systems

Abstract

Systems and methods are disclosed for using two TDD carriers in the same paired spectrum by offsetting the DL and UL transmissions in frequency to cause the TDD carriers to behave as two half-duplex FDD carriers. DL and UL transmission and reception periods are predefined such that only one of the TDD carriers is transmitting on the DL at any instant in time while the other TDD carrier is transmitting on the UL.

Claims

1. A cellular communication system, comprising:

a base transmission station (BTS), that transmits information on a downlink (DL) frequency band to one or more mobile devices and receives information on an uplink (UL) frequency band from the one or more mobile devices;

a frequency division duplex (FDD) processor that alternately applies first and second time division duplexed (TDD) carriers to a transmission signal on the DL frequency band according to a predefined switching schedule; and

a memory that stores information related to the predefined switching schedule, TDD carrier identity, and DL and UL frequency bands.

2. The system of claim 1, wherein the BTS transmits on the DL frequency band using the first TDD carrier for a first portion of a transmission frame, and using the second TDD carrier for a second portion of the transmission frame.

3. The system of claim 2, wherein the wherein the BTS receives on the UL frequency band using the first TDD carrier for a first portion of a transmission frame, and using the second TDD carrier for a second portion of the transmission frame.

4. The system of claim 3, wherein the FDD processor applies the first TDD carrier to the transmission signal during the first portion of the transmission frame and applies the second TDD carrier to the transmission signal during the second portion of the transmission frame, and applies a first transition gap during which the FDD processor switches from the first TDD carrier to the second TDD carrier.

5. The system of claim 4, wherein the BTS does not receive information on the UL frequency band during the first transition gap.

6. The system of claim 5, wherein the first portion of the transmission frame comprises N symbols, where N is a positive integer, and the second portion of the transmission from comprises M-N symbols, where M is the number of symbols per frame.

7. The system of claim 6, wherein the FDD processor applies a second transition gap during which the FDD processor switches from the second TDD carrier to the first TDD carrier for transmission of a first portion of a next transmission frame on the DL frequency band.

8. The system of claim 7, wherein the second transition gap is shorter than the first transition gap.

9. The system of claim 7, further comprising a receive time gap (RTG) on the UL frequency band immediately preceding each transition gap to prevent concurrent transmission on the DL frequency band and reception on the UL frequency using the same TDD carrier.

10. The system of claim 9, further comprising a transmission time gap (TTG) during the symbol preceding the first transition gap to prevent concurrent transmission on the DL frequency band and reception on the UL frequency using the same TDD carrier.

11. The system of claim 1, wherein the BTS receives information on the UL frequency band using the second TDD carrier during the first portion of the transmission frame, and receives information on the UL frequency band using the first TDD carrier during the second portion of the transmission frame.

12. A method of using existing TDD communication structures to perform FDD communication, comprising:

transmitting a DL signal on a DL frequency band using a first TDD carrier during a first portion of a transmission frame;

receiving a UL signal on a UL frequency band using a second TDD carrier during the first portion of the transmission frame;

transmitting the DL signal on the DL frequency band using the second TDD carrier during a second portion of the transmission frame;

receiving the UL signal on the UL frequency band using the first TDD carrier during the second portion of the transmission frame; and

switching from the first TDD carrier to the second TDD carrier on the DL frequency band, and from the second TDD carrier to the first TDD carrier on the UL frequency band, during a first transition gap that occurs between the first and second portions of the transmission frame.

13. The method of claim 12, further comprising temporarily stopping reception on the UL during first transition gap.

14. The method of claim 13, wherein the first portion of the transmission frame comprises N symbols, where N is a positive integer, and the second portion of the transmission from comprises M-N symbols, where M is the number of symbols per frame.

15. The method of claim 12, further comprising switching from the second TDD carrier to the first TDD carrier on the DL frequency band, and from the first TDD carrier to the second TDD carrier on the UL frequency band, during a second transition gap that occurs at the end of the transmission frame.

16. The method of claim 15, wherein the second transition gap is shorter than the first transition gap.

17. The method of claim 15, further comprising employing a receive time gap (RTG) on the UL frequency band immediately preceding each transition gap to prevent concurrent transmission on the DL frequency band and reception on the UL frequency using the same TDD carrier.

18. The method of claim 17, further comprising employing a transmission time gap (TTG) during the symbol preceding the first transition gap to prevent concurrent transmission on the DL frequency band and reception on the UL frequency using the same TDD.

19. The method of claim 18, wherein the RTG has a shorter duration than the TTG.

20. A system that facilitates wireless communication by causing two TDD carriers to behave as half-duplex FDD carriers, comprising:

means for transmitting a DL signal on a DL frequency band using a first TDD carrier during a first portion of a transmission frame;

means for receiving a UL signal on a UL frequency band using a second TDD carrier during the first portion of the transmission frame;

means for transmitting the DL signal on the DL frequency band using the second TDD carrier during a second portion of the transmission frame;

means for receiving the UL signal on the UL frequency band using the first TDD carrier during the second portion of the transmission frame;

means for switching from the first TDD carrier to the second TDD carrier on the DL frequency band, and from the second TDD carrier to the first TDD carrier on the UL frequency band, during a first transition gap that occurs between the first and second portions of the transmission frame; and

means for switching from the second TDD carrier to the first TDD carrier on the DL frequency band, and from the first TDD carrier to the second TDD carrier on the UL frequency band, during a second transition gap that occurs at the end of the transmission frame;

wherein transmission, reception, and carrier switching are performed iteratively across multiple transmission frames during a communication event.