Method and apparatus for providing downlink delay diversity

• US 20060166701A1
• Filed: 01/21/2005
• Published: 07/27/2006
• Est. Priority Date: 01/21/2005
• Status: Active Grant

• Current Assignee: Cingular Wireless LLC (AT&T, Inc.)
• Original Assignee: Cingular Wireless LLC (AT&T, Inc.)
• Inventors: Shah, Dipesh
• Granted Patent: US 7,813,306 B2
• Time in Patent Office: Days
• US Class Current: 455/561
• CPC Class Codes: H04B 7/0671 using different delays between antennas

Abstract

A method and apparatus for providing downlink transmit delay diversity (TDD). In accordance with the invention, a BTS includes at least one simplex transceiver (S-TRX) that does not implement downlink TDD and at least one duplex transceiver (D-TRX) that does implement TDD. In accordance with the preferred embodiment, the BTS has “N” S-TRXs and “A” D-TRXs, where N and A are positive integers and A is less than N. When downlink TDD is implemented, a total of N+A transceivers may be used (i.e., N S-TRXs and A D-TRXs). When downlink TDD is not needed, as many as N S-TRXs may be used. When downlink TDD is not needed, typically no D-TRXs are used. Therefore, the present invention reduces the amount of resources that is required to implement downlink TDD. In addition, the present invention efficiently utilizes resources by preferably implementing downlink TDD only when it is needed.

Claims

1. A base transceiver station (BTS) of a wireless network, the BTS comprising:

at least one transceiver that implements downlink transmit delay diversity (TDD); and

at least one transceiver that does not implement downlink TDD.

2. The BTS of claim 1 comprising:

“

A”

transceivers that implement downlink TDD, the number of transceivers that implement downlink TDD, “

A”

being an integer that is greater than 0; and

“

N”

transceivers that do not implement downlink TDD, “

N”

being an integer that is greater than 0, and wherein “

A”

is less than “

N”

.

3. The BTS of claim 2, wherein “

A”

is equal to 1 and “

N”

is equal to “

2”

.

4. The BTS of claim 1, wherein each transceiver that implements downlink TDD is a duplex transceiver comprising two simplex transceivers, each simplex transceiver having a respective antenna, and wherein each transceiver that does not implement downlink TDD comprises a simplex transceiver, each simplex transceiver having a respective antenna, each duplex transceiver handling a single respective call during a single respective time slot, each simplex transceiver handling a single respective call during a single respective time slot.

5. An apparatus for allocating resources during call setup based on whether or not downlink transmit delay diversity (TDD) is needed for the call being setup, the apparatus comprising:

first logic configured to evaluate one or more downlink parameters associated with a call;

second logic configured to determine whether or not TDD is needed for the call based on the evaluation by the first logic;

third logic configured to allocate a duplex transceiver to the call if the second logic makes a determination that downlink TDD is needed, the duplex transceiver being configured to implement downlink TDD; and

fourth logic configured to allocate a simplex transceiver to the call if the second logic determines that downlink TDD is not needed for the call, the simplex transceiver not being configured to implement downlink TDD.

6. The apparatus of claim 5, wherein the downlink parameters are evaluated while the call is being setup.

7. The apparatus of claim 5, wherein the downlink parameters are evaluated while the call is in progress between a mobile device and a first transceiver, the first transceiver not being configured to implement downlink transmit delay diversity (TDD), the apparatus further comprising:

fifth logic configured to initiate a handover from the first transceiver to the second transceiver if the second logic determines that downlink TDD is needed, the second transceiver being configured to implement downlink TDD.

8. The apparatus of claim 7, wherein the second transceiver is a duplex transceiver comprising at least two simplex transceivers, each simplex transceiver being connected to a respective antenna, said at least two simplex transceivers communicating with a single mobile device during a single time slot.

9. The apparatus of claim 7, further comprising:

sixth logic configured to initiate a handover from a first transceiver to a second transceiver if the second logic determines that downlink TDD is not needed, the second transceiver not being configured to implement downlink TDD.

10. The apparatus of claim 9, wherein the first transceiver is a duplex transceiver comprising at least two simplex transceivers, each simplex transceiver being connected to a respective antenna, said at least two simplex transceivers communicating with a single mobile device during a single time slot.

11. The apparatus of claim 5, wherein the first logic evaluates one or more downlink parameters associated with the call as the call is being handed over from a first BTS to a second BTS, the apparatus further comprising:

fifth logic configured to initiate a handover from a transceiver of the first BTS to a transceiver of the second BTS if the second logic determines that downlink TDD is needed.

12. The apparatus of claim 11, wherein the transceiver of the second BTS is configured to implement downlink TDD.

13. The apparatus of claim 11, wherein the transceiver of the second BTS is not configured to implement downlink TDD.

15. The method of claim 13, wherein the downlink parameters are evaluated as the call is being handed over from the first transceiver to the second transceiver, the first transceiver being a duplex transceiver, the second transceiver being a simplex transceiver, the duplex transceiver comprising at least two simplex transceivers, each simplex transceiver of the duplex transceiver being connected to a respective antenna, said at least two simplex transceivers communicating with a single mobile device during a single time slot.

16. The method of claim 13, wherein the downlink parameters are evaluated during an intracell handover while the call is being handed over from the first transceiver to the second transceiver, the first transceiver being in a first coverage area of the wireless network and the second transceiver being in the same coverage area of the wireless network.

17. The method of claim 13, wherein the downlink parameters are evaluated during a handover of the call from the first transceiver to the second transceiver, the first transceiver being part of a first base transceiver station (BTS), the second transceiver being part of a second BTS.

14. A method for allocating resources during call setup based on whether downlink transmit delay diversity (TDD) is needed for the call, the method comprising:

evaluating one or more downlink parameters associated with a call;

determining whether or not downlink TDD is needed for the call based on the evaluation;

allocating a first transceiver to the call if a determination that downlink TDD is needed, the first transceiver being configured to implement downlink TDD; and

allocating a second transceiver to the call if a determination is made that downlink TDD is not needed for the call, the second transceiver not being configured to implement downlink TDD.

18. A computer program for allocating resources during call setup based on whether downlink transmit delay diversity (TDD) is needed for the call, the program being embodied on a computer-readable medium, the program method comprising:

a first code segment for evaluating one or more downlink parameters associated with a call;

a second code segment for determining whether or not downlink TDD is needed for the call based on the evaluation;

a third code segment for allocating a first transceiver to the call if a determination is made that downlink TDD is needed, the first transceiver being configured to implement downlink TDD; and

a fourth code segment for allocating a second transceiver to the call if a determination is made that downlink TDD is not needed for the call, the second transceiver not being configured to implement downlink TDD.