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

• US 20090042558A1
• Filed: 07/31/2008
• Published: 02/12/2009
• Est. Priority Date: 08/07/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Pierre Bertrand, Tarik Muharemovic, Zukang Shen
• Inventors: Bertrand, Pierre, Shen, Zukang, Muharemovic, Tarik
• Granted Patent: US 8,149,938 B2
• Time in Patent Office: Days
• US Class Current: 455/422.100
• CPC Class Codes: H04L 1/0028 Formatting
• CPC Class Codes: H04L 1/1671 the supervisory signal being transmitted together with control information
• CPC Class Codes: H04L 1/1692 Physical properties of the supervisory signal, e.g. acknowledgement by energy bursts
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/206 using a pair of orthogonal carriers, e.g. quadrature carriers
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26136 Pilot sequence conveying additional information
• CPC Class Codes: H04L 27/3483 using a modulation of the constellation points
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals

Abstract

A transmission of information within a wireless cellular network may include a first and second type of information. A subframe is produced that includes a plurality of symbols, wherein at least one symbol is designated as a data symbol and at least one symbol is designated as a reference signal symbol that contains a pre-defined reference signal. The first type of information is embedded in the data symbols. If the second type of data is expected, then the second type of information is embedded in at least one reference symbol by quadrature amplitude modulating the pre-defined reference signal. The subframe is then transmitted from one node in the network to a second node. In some embodiments, if it is determined that the second node is not expecting the second type of information, then a discontinuous transmission (DTX) response is embedded in the reference symbol instead of the second type of information.

Claims

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

forming a plurality of data symbols using a first type of information;

forming at least one reference symbol using a pre-defined reference signal;

determining if a second type of information is expected;

if the second type of information is expected, then embedding the second type of information in at least one said reference symbol by modulating the pre-defined reference signal; and

transmitting a subframe comprising formed data symbols and reference symbols to a receiver.

2. Method of claim 1, further comprising:

if the second type of information is not expected, then embedding a discontinuous transmission (DTX) symbol in the reference symbol in place of the second type of information.

3. Method of claim 1, wherein if the second type of information is not expected, then the reference symbol comprises the unmodulated pre-defined reference signal.

4. Method of claim 1, wherein embedding the second type of information in at least one reference symbol comprises:

mapping the second type of information into at least one quadrature amplitude modulation (QAM) symbol; and

modulating the pre-defined reference signal in the reference symbol with the QAM symbol mapped from the second type of information.

5. Method of claim 1, wherein the first type of information is a channel quality indicator (CQI).

6. Method of claim 1, wherein the second type of information is an ACKNAK response, wherein generating a second type of information comprises generating a 1-bit ACKNAK response, and wherein embedding the second type of information in at least one reference symbol comprises:

mapping the generated 1-bit ACKNAK response into at least one symbol according to a constellation mapping scheme comprising two constellation points, wherein a 1-bit “

ACK”

response is mapped to a first constellation point, wherein a 1-bit “

NAK”

response is mapped to a second constellation point; and

modulating the pre-defined reference signal in the at least one reference symbol with the symbol mapped from the 1-bit ACKNAK response.

7. Method of claim 1, wherein the second type of information is an ACKNAK response, wherein generating a second type of information comprises generating a 2-bit ACKNAK response, and wherein embedding the second type of information in at least one reference symbol comprises:

mapping the generated 2-bit ACKNAK response into at least one symbol according to a constellation mapping scheme comprising four constellation points, wherein a 2-bit “

ACK, ACK”

response is mapped to a first constellation point, wherein a 2-bit “

ACK, NAK”

response is mapped to a second constellation point, wherein a 2-bit “

NAK, ACK”

response is mapped to a third constellation point, wherein a 2-bit “

NAK, NAK”

response is mapped to a fourth constellation point; and

modulating the pre-defined reference signal in the at least one reference symbol with the symbol mapped from the 2-bit ACKNAK response.

8. Method of claim 2, wherein the second type of information is an ACKNAK response, wherein generating a second type of information comprises generating a 1-bit ACKNAK response, and wherein embedding the second type of information in at least one reference symbol comprises:

mapping the generated 1-bit ACKNAK response into at least one symbol according to a constellation mapping scheme comprising two constellation points, wherein a 1-bit “

ACK”

response is mapped to a first constellation point, wherein a 1-bit “

NAK”

response is mapped to a second constellation point, wherein a discontinuous transmission “

DTX”

response is mapped to same constellation point as the 1-bit “

NAK”

response; and

modulating the pre-defined reference signal in the at least one reference symbol with the symbol selected by the mapping function.

9. Method of claim 2, wherein the second type of information is an ACKNAK response, wherein generating a second type of information comprises generating a 2-bit ACKNAK response, and wherein embedding the second type of information in at least one reference symbol comprises:

mapping the generated 2-bit ACKNAK response into at least one symbol according to a constellation mapping scheme comprising four constellation points, wherein a 2-bit “

ACK, ACK”

response is mapped to a first constellation point, wherein a 2-bit “

ACK, NAK”

response is mapped to a second constellation point, wherein a 2-bit “

NAK, ACK”

response is mapped to a third constellation point, wherein a 2-bit “

NAK, NAK”

response is mapped to a fourth constellation point, wherein a discontinuous transmission “

DTX”

response is mapped to the same constellation point as the 2-bit “

NAK, NAK”

response, and

modulating the pre-defined reference signal in the at least one reference symbol with the symbol selected by the mapping function.

10. Method of claim 2, wherein the second type of information is an ACKNAK response, wherein generating a second type of information comprises generating a 1-bit ACKNAK response, and wherein embedding the second type of information in at least one reference symbol comprises:

mapping the generated 1-bit ACKNAK response into at least one symbol according to a constellation mapping scheme comprising three constellation points, wherein a 1-bit “

ACK”

response is mapped to a first constellation point, wherein a 1-bit “

NAK”

response is mapped to a second constellation point, wherein a discontinuous transmission “

DTX”

response is mapped to a third constellation point; and

modulating the pre-defined reference signal in the at least one reference symbol with the symbol selected by the mapping function.

11. Method of claim 2, wherein the second type of information is an ACKNAK response, wherein generating a second type of information comprises generating a 2-bit ACKNAK response, and wherein embedding the second type of information in at least one reference symbol comprises:

mapping the generated 2-bit ACKNAK response into at least one symbol according to a constellation mapping scheme comprising five constellation points, wherein a 2-bit “

ACK, ACK”

response is mapped to a first constellation point, wherein a 2-bit “

ACK, NAK”

response is mapped to a second constellation point, wherein a 2-bit “

NAK, ACK”

response is mapped to a third constellation point, wherein a 2-bit “

NAK, NAK”

response is mapped to a fourth constellation point, wherein a discontinuous transmission “

DTX”

response is mapped to a fifth constellation point; and

modulating the pre-defined reference signal in the at least one reference symbol with the symbol selected by the mapping function.

12. Method of claim 1, wherein each symbol confines to an orthogonal frequency division multiplexing (OFDM) symbol.

13. Method of claim 12, wherein transmitting the subframe lasts for a duration which is an integral multiple of 0.5 ms slots.

14. Method of claim 13, wherein the first type of information is a channel quality indicator (CQI), and wherein forming a plurality of data symbols using the first type of information comprises:

mapping the first type of information into at least one quadrature amplitude modulation (QAM) symbol; and

modulating the data symbol with the QAM symbol mapped from the first type of information.

15. Method of claim 13, wherein the second type of information is an ACKNAK response, and wherein embedding the second type of information in at least one reference symbol comprises:

mapping the second type of information into at least one quadrature amplitude modulation (QAM) symbol; and

modulating the pre-defined reference signal in the reference symbol with the QAM symbol mapped from the second type of information.

16. Method of claim 14, wherein modulating an R-th data symbol comprises:

producing a first sequence; and

multiplying the entire first sequence with the R-th QAM symbol mapped from the first type of information.

17. Method of claim 15, wherein modulating the pre-defined reference signal in the reference symbol with the QAM symbol mapped from the second type of information comprises:

producing a second sequence; and

multiplying the entire second sequence with one QAM symbol mapped from the second type of information.

18. Method of claim 13, wherein each 0.5 ms slot comprises five data symbols and two reference symbols;

wherein the first type of information is a channel quality indicator (CQI) and the second type of information is a 1-bit ACKNAK response;

wherein forming a plurality of data symbols using the first type of information comprises mapping the CQI to produce five QPSK symbols per slot; and

modulating each R-th data symbol by producing a first sequence and multiplying the entire first sequence with the R-th QPSK symbol mapped from the first type of information; and

wherein embedding the second type of information in a second reference symbol of the two reference symbols comprises;

mapping the 1-bit ACKNAK response into at least one BPSK symbol according to a BPSK constellation mapping scheme comprising two constellation points; and

quadrature amplitude modulating the second reference symbol by producing a second sequence and multiplying the entire second sequence with one BPSK symbol mapped from the second type of information;

wherein a 1-bit “

ACK”

response is mapped to a first BPSK constellation point; and

wherein a 1-bit “

NAK”

response is mapped to a second BPSK constellation point.

19. Method of claim 13, wherein each 0.5 ms slot comprises five data symbols and two reference symbols;

wherein the first type of information is a channel quality indicator (CQI) and the second type of information is a 2-bit ACKNAK response;

wherein forming a plurality of data symbols using the first type of information comprises mapping the CQI to produce five QPSK symbols per slot; and

modulating each R-th data symbol by producing a first sequence and multiplying the entire first sequence with the R-th QPSK symbol mapped from the first type of information; and

wherein embedding the second type of information in a second reference symbol of the two reference symbols comprises;

mapping the 2-bit ACKNAK response into at least one QPSK symbol according to a QPSK constellation mapping scheme comprising four constellation points; and

quadrature amplitude modulating the second reference symbol by producing a second sequence and multiplying the entire second sequence with one QPSK symbol mapped from the second type of information;

wherein a 2-bit “

ACK, ACK”

response is mapped to a first QPSK constellation point;

wherein a 2-bit “

ACK, NAK”

response is mapped to a second QPSK constellation point;

wherein a 2-bit “

NAK, ACK”

response is mapped to a third QPSK constellation point; and

wherein a 2-bit “

NAK, NAK”

response is mapped to a fourth QPSK constellation point.

20. An apparatus for transmitting in a wireless cellular network, comprising:

generating circuitry for forming a plurality of data symbols using a first type of information;

generating circuitry for forming at least one reference symbol using a pre-defined reference signal;

producing circuitry coupled to the generating circuitry and operable to determine if a second type of information is expected, and operable to produce a signal comprising the plurality of data symbols and the at least one reference symbol, wherein if the second type of information is expected, then the second type of information is embedded in at least one said reference symbol by modulating the pre-defined reference signal; and

transmitter circuitry coupled to the producing circuitry operable to transmit the produced signal.

21. The apparatus of claim 20, wherein if the second type of information is not expected, then a discontinuous transmission (DTX) symbol is embedded in the at least one said reference symbol in place of the second type of information.

22. An apparatus for receiving in a wireless cellular network, comprising:

a receiver operable to receive a channel quality indicator (CQI) signal transmitted via a selected control channel, wherein the transmitted CQI signal comprises a plurality of symbols, with at least one symbol designated as a data symbol and at least one symbol designated as a reference symbol; and

demodulation circuitry connected to the receiver operable to demodulate the data symbols to recover the CQI information and operable to demodulate at least one of the reference symbols using quadrature amplitude demodulation to recover ACKNAK information embedded in the reference symbol.