Transmission of ACK/NACK Bits and their Embedding in the Reference Signal

• US 20080075184A1
• Filed: 09/20/2007
• Published: 03/27/2008
• Est. Priority Date: 09/22/2006
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Shen, Zukang, Bertrand, Pierre, Muharemovic, Tarik
• Granted Patent: US 8,571,120 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 27/2605 Symbol extensions, e.g. Zero Tail, Unique Word [UW]
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26134 Pilot insertion in the transmitter chain, e.g. pilot overlapping with data, insertion in time or frequency domain
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals

Abstract

Transmitting a ACK/NACK response in a wireless cellular network by mapping the data value into a cyclic shifted version of a reference signal. A subframe is formed with a plurality of symbols with certain symbols designated as reference signal (RS) symbols. The receiver and transmitter both know when an ACK/NACK response is expected. If an ACK/NACK response is not expected, then an RS is inserted in the duration of symbols designated as RS symbols. If an ACK/NACK response is expected, then the ACK/NACK response is embedded in one or more of the symbols designated as RS symbols. The subframe is transmitted to a receiver, and the receiver can determine the ACK/NACK value in the RS symbol, if present, and also use the RS symbol for coherent demodulation of a CQI (channel quality indicator) or data.

Claims

1. A method for transmitting in a wireless cellular network, comprising:

determining a data value for one or more data bits;

mapping the data value to a cyclic shift amount;

constructing a pre-defined base signal using orthogonal frequency-division multiplexing (OFDM) modulation, where OFDM modulation comprises mapping a constant amplitude sequence onto a set of tones;

cyclically shifting the base signal in the time-domain by the mapped cyclic shift amount representative of the data value to form a cyclic shifted base signal; and

transmitting the cyclic shifted base signal to a receiver, whereby the receiver can determine the data value by determining the shift amount.

2. The method of claim 1 wherein the constant amplitude sequence is a CAZAC-like sequence.

3. The method of claim 1, further comprising transmitting a channel quality indicator (CQI) in conjunction with the cyclic shifted CAZAC-like sequence, whereby the receiver may use the cyclic shifted CAZAC-like sequence as a reference signal for coherent demodulation of the CQI.

4. The method of claim 1, further comprising modifying the CAZAC-like sequence before cyclic shifting.

5. The method of claim 1, wherein the data value is an ACK/NACK status bit.

6. The method of claim 1, wherein the same data value is re-transmitted a second or more times for redundancy.

7. The method of claim 6, wherein the data value is mapped to a different cyclic shift amount that is used for the second re-transmission.

8. The method of claim 3, further comprising:

receiving a signal at the receiver that includes the transmitted cyclic shifted CAZAC-like sequence;

determining the shift amount of the transmitted cyclic shifted CAZAC-like sequence; and

extracting the data value in accordance with the shift amount.

9. The method of claim 8, wherein determining the shift amount comprises:

demodulating the received signal with the base CAZAC-like sequence to obtain the estimated channel taps; and

estimating the shift amount based on a location of a maximum channel tap.

10. The method of claim 8, wherein determining the shift amount comprises:

demodulating the received signal with the base CAZAC-like sequence to obtain the estimated channel taps; and

estimating the shift amount based on a maximum section energy wherein a length of the CAZAC-like sequence is divided into N sections.

11. The method of claim 8, further comprising using the cyclic shifted CAZAC-like sequence as a reference signal for coherent demodulation of the CQI.

12. A method for transmitting in a wireless cellular network, comprising:

forming a subframe with a plurality of symbols with certain symbols designated as reference signal (RS) symbols;

determining if an ACK/NACK response is expected;

if ACK/NACK response is not expected, inserting a pre-defined reference signal in the duration of symbols designated as RS symbols;

if an ACK/NACK response is expected, embedding the ACK/NACK response in one or more of the symbols designated as RS symbols; and

transmitting the subframe to a receiver, whereby the receiver can determine the ACK/NACK in the RS symbol, if present, and also use the RS symbol for coherent demodulation of a CQI (channel quality indicator) or data.

13. The method of claim 12 wherein the RS comprises a base CAZAC-like sequence and embedding the ACK/NACK response comprises:

determining a data value for the ACK/NACK response;

mapping the data value to a cyclic shift amount; and

cyclic shifting the base CAZAC-like sequence by the mapped cyclic shift amount representative of the data value to form a cyclic shifted CAZAC-like sequence.

14. A method for receiving in a wireless cellular network, comprising:

receiving a signal at the receiver that includes a transmitted cyclic shifted base signal;

determining the shift amount of the transmitted cyclic shifted base signal; and

extracting a data value in accordance with the shift amount if a data value is expected; and

using the cyclic shifted base signal as a reference signal for coherent demodulation of a data symbol.

15. The method of claim 14, wherein the cyclic shifted base signal is a CAZAC-like sequence.

16. The method of claim 15, wherein determining the shift amount comprises:

demodulating the received signal with a base CAZAC-like sequence to obtain the estimated channel taps; and

estimating the shift amount based on a location of a maximum channel tap.

17. The method of claim 16, wherein determining the shift amount comprises:

demodulating the received signal with the base CAZAC-like sequence to obtain the estimated channel taps; and

estimating the shift amount based on a maximum section energy wherein a length of the CAZAC-like sequence is divided into N sections.

18. The method of claim 15, further comprising using the cyclic shifted CAZAC-like sequence as a reference signal for coherent demodulation of the CQI.

19. A user equipment (UE) device for use in a wireless cellular network, comprising:

means for forming a subframe with a plurality of symbols with certain symbols designated as reference signal (RS) symbols;

means for determining if an ACK/NACK response is expected;

means for inserting an RS in the duration of symbols designated as RS symbols if ACK/NACK response is not expected;

means for embedding the ACK/NACK response in one or more of the symbols designated as RS symbols if an ACK/NACK response is expected; and

means for transmitting the subframe to a receiver, whereby the receiver can determine the ACK/NACK in the RS symbol, if present, and also use the RS symbol for coherent demodulation of a CQI (channel quality indicator) or data.

20. The UE of claim 19 wherein the RS comprises a base CAZAC-like sequence and wherein the means for embedding the ACK/NACK response comprises:

means for determining a data value for the ACK/NACK response;

means for mapping the data value to a cyclic shift amount; and

means for cyclic shifting the base CAZAC-like sequence by the mapped cyclic shift amount representative of the data value to form a cyclic shifted CAZAC-like sequence.

21. A receiver for use in a wireless cellular network, comprising:

a radio receiver operable to receive a signal that includes a transmitted cyclic shifted base signal;

circuitry operable to determine the shift amount of the transmitted cyclic shifted base signal; and

circuitry operable to extract a data value in accordance with the shift amount if a data value is expected; and

circuitry operable to use the cyclic shifted base signal as a reference signal for coherent demodulation of a data symbol.