Systems and Methods For Transmit Diversity For DFT Precoded Channels

• US 20120039158A1
• Filed: 01/28/2011
• Published: 02/16/2012
• Est. Priority Date: 08/13/2010
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: BALDEMAIR, Robert, GERSTENBERGER, Dirk, LARSSON, Daniel, CHENG, Jung-Fu
• Granted Patent: US 8,824,267 B2
• Time in Patent Office: Days
• US Class Current: 370/203
• CPC Class Codes: H04B 7/0671 using different delays between antennas

Abstract

A transmission method and apparatus that combines the benefits of DFT precoding and transmit diversity coding for PUCCH transmission. In one aspect, the invention provides an improved transmit diversity coding method and apparatus for DFTS-OFDM PUCCH with minimal impact on multiplexing capacity. In one embodiment, the improved transmit diversity method and apparatus has the feature of employing frequency-domain separation for the payload signals.

Claims

1. In a mobile terminal having a first antenna and a second antenna, a transmit diversity method for discrete Fourier transform (DFT) precoded channels, the method comprising:

producing a block of data symbols;

transforming said block of data symbols to produce a first block of transformed symbols and a second block of transformed symbols;

using the first antenna, transmitting the first block of transformed symbols and a first reference sequence, wherein the transmitting step occurs during a slot of a subframe of a radio frame; and

using the second antenna, transmitting, during said slot, the second block of transformed symbols and a second reference sequence, wherein

the first block of transformed symbols is transmitted using a first set of subcarriers,

the second block of transformed symbols is transmitted using a second set of subcarriers that is orthogonal to the first set of subcarriers, and

the first reference sequence and the second reference sequence are transmitted using a third set of subcarriers that comprises that first set of subcarriers and the second set of subcarriers.

2. The method of claim 1, wherein the first reference sequence is orthogonal to the second reference sequence.

3. The method of claim 2, wherein the first reference sequence is a cyclic shift of the second reference sequence.

4. The method of claim 1, wherein the step of transforming said block of data symbols comprises:

dividing the block of data symbols into at least a first sub-block and a second sub-block;

applying a discrete Fourier transform (DFT) to the first sub-block to produce the first block of transformed symbols; and

applying a discrete Fourier transform (DFT) to the second sub-block to produce the second block of transformed symbols.

5. The method of claim 4, wherein the block of data symbols consists of twelve data symbols, and the step of transforming said block of twelve data symbols comprises:

dividing the block of twelve symbols into first sub-block of six symbols and a second sub-block of six symbols;

applying a DFT of size six to the first sub-block of six symbols to produce the first block of transformed symbols; and

applying a DFT of size six to the second sub-block of six symbols to produce the second block of transformed symbols.

6. The method of claim 1, wherein

the step of transmitting the first block of transformed symbols comprises mapping each symbol within the first block of transformed symbols to a particular subcarrier within the first set of subcarriers and applying an inverse fast Fourier transform (IFFT) to the first block of transformed symbols;

and

the step of transmitting the second block of transformed symbols comprises mapping each symbol within the second block of transformed symbols to a particular subcarrier within the second set of subcarriers and applying the IFFT to the second block of transformed symbols.

7. The method of claim 1, further comprising

producing a second block of data symbols;

transforming said second block of data symbols to produce a third block of transformed symbols and a fourth block of transformed symbols;

using the first antenna, transmitting the third block of transformed symbols and the first reference sequence, wherein the transmitting step occurs during a second slot of the subframe; and

using the second antenna, transmitting, during the second slot, the fourth block of transformed symbols and the second reference sequence, wherein

the third block of transformed symbols is transmitted using a fourth set of subcarriers, and

the fourth block of transformed symbols is transmitted using a fifth set of subcarriers that is orthogonal with the fourth set of subcarriers.

8. The method of claim 1, wherein

the first and fifth sets of subcarriers consist only of even indexed subcarriers and the second and fourth sets of subcarriers consist only of odd indexed subcarriers, or

the first and fifth sets of subcarriers consist only of odd indexed subcarriers and the second and fourth sets of subcarriers consist only of even indexed subcarriers.

9. A transmit diversity apparatus for discrete Fourier transform (DFT) precoded channels, the apparatus comprising:

a first antenna;

a second antenna; and

a data processor coupled to the first antenna and the second antenna, the data processor being configured to;

(a) produce a block of data symbols from a set of message bits;

(b) transform said block of data symbols to produce a first block of transformed symbols and a second block of transformed symbols;

(c) use the first antenna to transmit, during a slot of a subframe of a radio frame, the first block of transformed symbols and a first reference sequence; and

(d) use the second antenna to transmit, during said slot, the second block of transformed symbols and a second reference sequence, wherein

the data processor is further configured such that (a) the first block of transformed symbols is transmitted using a first set of subcarriers, (b) the second block of transformed symbols is transmitted using a second set of subcarriers that is orthogonal to the first set of subcarriers, and (c) the first reference sequence and the second reference sequence are transmitted using a third set of subcarriers that comprises that first set of subcarriers and the second set of subcarriers.

10. The apparatus of claim 9, wherein the first reference sequence is orthogonal to the second reference sequence.

11. The apparatus of claim 10, wherein the first reference sequence is a cyclic shift of the second reference sequence.

12. The apparatus of claim 9, wherein the data processor is further configured such that the data processor transforms said block of data symbols by:

dividing the block of data symbols into at least a first sub-block and a second sub-block;

applying a discrete Fourier transform (DFT) to the first sub-block to produce the first block of transformed symbols; and

applying a discrete Fourier transform (DFT) to the second sub-block to produce the second block of transformed symbols.

13. The apparatus of claim 12, wherein the block of data symbols consists of twelve data symbols, and the data processor is further configured such that the data processor transforms said block of data symbols by:

dividing the block of twelve symbols into first sub-block of six symbols and a second sub-block of six symbols;

applying a DFT of size six to the first sub-block of six symbols to produce the first block of transfolined symbols; and

applying a DFT of size six to the second sub-block of six symbols to produce the second block of transformed symbols.

14. The apparatus of claim 9, wherein the data processor is further configured such that the data processor:

maps each symbol within the first block of transformed symbols to a particular subcarrier within the first set of subcarriers and applies an inverse fast Fourier transform (IFFT) to the first block of transformed symbols; and

maps each symbol within the second block of transformed symbols to a particular subcarrier within the second set of subcarriers and applies the IFFT to the second block of transformed symbols.

15. The apparatus of claim 9, wherein the data processor is further configured to:

produce a second block of data symbols;

transform said second block of data symbols to produce a third block of transformed symbols and a fourth block of transformed symbols;

use the first antenna to transmit, during a second slot of the subframe, the third block of transformed symbols and the first reference sequence; and

use the second antenna to transmit, during the second slot, the fourth block of transformed symbols and the second reference sequence, wherein

the data processor is further configured such that (a) the third block of transformed symbols is transmitted using a fourth set of subcarriers, (b) the fourth block of transformed symbols is transmitted using a fifth set of subcarriers, and (c) the fourth set of subcarriers is orthogonal with the fifth set of subcarriers.

16. The apparatus of claim 15, wherein

the first and fifth sets of subcarriers consist only of even indexed subcarriers and the second and fourth sets of subcarriers consist only of odd indexed subcarriers, or

the first and fifth sets of subcarriers consist only of odd indexed subcarriers and the second and fourth sets of subcarriers consist only of even indexed subcarriers.

17. The apparatus of claim 9, wherein the set of message bits comprises one or more HARQ feedback bits.

18. The apparatus of claim 17, wherein the set of message bits further comprises a scheduling request bit.

19. The apparatus of claim 17, wherein the HARQ feedback bits comprises bits obtained by a logical AND operation of several individual HARQ feedback bits.

20. A mobile terminal comprising a transmit diversity apparatus for discrete Fourier transform (DFT) precoded channels, the apparatus comprising:

a first antenna;

a second antenna; and

a data processor coupled to the first antenna and the second antenna, the data processor being configured to;

(a) produce a block of data symbols from a bit sequence;

(c) transform said block of data symbols to produce a first block of transformed symbols and a second block of transformed symbols;

(d) use the first antenna to transmit, during a slot of a subframe of a radio frame, the first block of transformed symbols and a first reference sequence; and

(e) use the second antenna to transmit, during said slot, the second block of transformed symbols and a second reference sequence, wherein

the data processor is further configured such that (a) the first block of transformed symbols is transmitted using a first set of subcarriers, (b) the second block of transformed symbols is transmitted using a second set of subcarriers that is orthogonal to the first set of subcarriers, and (c) the first reference sequence and the second reference sequence are transmitted using a third set of subcarriers that comprises that first set of subcarriers and the second set of subcarriers.