# US 9,439,141 B2 · Decoding algorithm for the HS-DPCCH HARQ message exploiting the pre-and postambles

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- Number: US 9,439,141 B2
- Document ID: US9439141B2
- Status: Granted
- Kind: B2
- Application number: 13/859,570
- Filed: 2013-04-09
- Published: 2014-10-09
- Granted: 2016-09-06
- Earliest claimed: 2013-04-09
- Assignees: Telefonaktiebolaget L M Ericsson (publ)
- Applicants: Telefonaktiebolaget L M Ericsson (Publ)
- Inventors: Michael Samuel Bebawy; Yi-Pin Eric Wang; Erik Larsson; Peter von Wrycza
- Web page: https://patentgrep.com/patent/US9439141B2

## CPC

- H04W 52/0212: {managed by the network, e.g. network or access point is leader and terminal is follower}
- H04L 1/0026: {Transmission of channel quality indication}
- H04L 1/0073: {Special arrangements for feedback channel}
- H04L 1/1628: {List acknowledgements, i.e. the acknowledgement message consisting of a list of identifiers, e.g. of sequence numbers (H04L1/1614 takes precedence)}
- H04L 1/1671: {the supervisory signal being transmitted together with control information}
- H04L 2001/125: {Arrangements for preventing errors in the return channel}
- Y02D 30/70: in wireless communication networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A method that is implemented by a base station to decode a high speed dedicated physical control channel (HS-DPCCH) using a preamble and postamble of a hybrid automatic repeat request (HARQ) message while maintaining a fixed false alarm probability of interpreting a discontinuous transmission (DTX) as a HARQ acknowledgement (ACK) or HARQ negative acknowledgement (NACK). The method includes a set of steps, including receiving a signal from a user equipment (UE). The signal is despread using a G-RAKE demodulator. The despread signal is combined to produce a combined symbol estimate vector x including a preamble and postamble of the HARQ message. The combined symbol estimate vector x is checked to determine whether the signal includes a DTX, HARQ ACK or HARQ NACK, and then the DTX, HARQ ACK or HARQ NACK is output.

## Claims

### Claim 1

A method implemented by a base station to decode a high speed dedicated physical control channel (HS-DPCCH) using a preamble and postamble of a hybrid automatic repeat request (HARQ) message while maintaining a fixed false alarm probability of interpreting a discontinuous transmission (DTX) as a HARQ acknowledgement (ACK) or HARQ negative acknowledgement (NACK), the method comprising the steps of:
receiving a signal from a user equipment (UE);
despreading the signal using a G-RAKE demodulator;
combining the despread signal to produce a combined symbol estimate vector x including
a preamble and postamble of the HARQ message;
checking the combined symbol estimate vector x to determine whether the signal includes
a DTX, HARQ ACK or HARQ NACK, wherein the checking of the combined symbol estimate vector further includes determining boundaries of a DTX region, and checking whether the combined symbol estimate vector x lies within the DTX region; and
outputting the DTX, HARQ ACK or HARQ NACK.

### Claim 2 (depends on 1)

The method of claim 1, wherein checking whether the combined symbol estimate vector x lies within the DTX region, further comprises the step of:
forming a set of vectors ai where aiis an ith constellation point of the signal, and wherein ai includes the preamble and postamble of the HARQ message.

### Claim 3 (depends on 2)

The method of claim 2, wherein checking whether the combined symbol estimate vector x lies within the DTX region, further comprises the step of:
substituting the combined symbol estimate vector x into the inequalities aiH·x ≦b(SINR, PFA), for i=1, . . . , M, where a, is the i th constellation point and b(SINR, PFA) is a parameter that depends on a current SINR and a target FA probability, PFA.

### Claim 4 (depends on 3)

The method of claim 3, wherein the combined symbol estimate vector x lies within the DTX region, further comprises the step of:
outputting DTX where the inequalities are satisfied.

### Claim 5 (depends on 3)

The method of claim 3, wherein the combined symbol estimate vector x lies outside the DTX region, further comprises the step of:
determining a set of minimum distances where the inequalities are not satisfied, where a squared Euclidean distance between the combines symbol estimate vector x and all constellation points of the signal is calculated as di=∥x−ai∥2 to populate a set of minimum distances; and
selecting a constellation point with the minimum distance di.

### Claim 6 (depends on 2)

The method of claim 2, further comprising the steps of:
determining a vector a12 that is equal to a1−a2;
calculating a scalar product a12* x;
selecting a2 where the scalar product is greater than zero; and
selecting a1 where the scalar product is less than zero.

### Claim 7 (depends on 1)

The method of claim 1, wherein checking the combined symbol estimate vector x, further comprises the steps of:
determining whether the signal includes a plurality of HARQ ACKs or HARQ NACKs or a combination of a HARQ ACK and HARQ NACK.

### Claim 8

A base station to decode a high speed dedicated physical control channel (HS-DPCCH) using a preamble and postamble of a hybrid automatic repeat request (HARQ) message while maintaining a fixed false alarm probability of interpreting a discontinuous transmission (DTX) as a HARQ acknowledgement (ACK) or HARQ negative acknowledgement (NACK), the base station comprising:
a transceiver to receive a signal from a user equipment (UE);
a G-RAKE demodulator coupled to the transceiver, the G-RAKE configured to despread the signal and to combine the despread signal to produce a combined symbol estimate vector x including a preamble and postamble of the HARQ message; and
a decoder coupled to the G-RAKE demodulator, the decoder configured to receive the combined symbol estimate vector x from the G-RAKE demodulator, to check the combined symbol estimate vector x to determine whether the signal includes a DTX, HARQ ACK or HARQ NACK, and to output the DTX, HARQ ACK or HARQ NACK, where the decoder is further configured to determine boundaries of a DTX region, to check whether the combined symbol estimate vector x lies within the DTX region.

### Claim 9 (depends on 8)

The base station of claim 8, wherein the decoder is further configured to form a set of vectors a, where a, is an ith constellation point of the signal, and wherein a, includes the preamble and postamble of the HARQ message.

### Claim 10 (depends on 9)

The base station of claim 9, wherein the decoder is further configured to substitute the combined symbol estimate vector x into the inequalities aiH·x≦b(SINR, PFA), for i=1, . . . , M, where ai, is the ith constellation point and b(SINR, PFA) is a parameter that depends on a current SINR and a target FA probability, PFA.

### Claim 11 (depends on 10)

The base station of claim 10, wherein the combined symbol estimate vector x lies within the DTX region, the decoder is configured to output DTX where the inequalities are satisfied.

### Claim 12 (depends on 10)

The base station of claim 10, wherein the combined symbol estimate vector x lies outside the DTX region, the decoder determines a set of minimum distances where the inequalities are not satisfied, where a squared Euclidean distance between the combines symbol estimate vector x and all constellation points of the signal is calculated as di=∥x −ai∥2to populate a set of minimum distances, and the decoder selects a constellation point with the minimum distance di.

### Claim 13 (depends on 9)

The base station of claim 9, wherein the decoder is configured to determine a vector a12 that is equal to a1−a2, calculate a scalar product a12* x, select a2 where the scalar product is greater than zero, and select a1 where the scalar product is less than zero.

### Claim 14 (depends on 8)

The base station of claim 8, wherein the decoder is further configured to check the combined symbol estimate vector x to determine whether the signal includes a plurality of HARQ ACKs or HARQ NACKs or a combination of a HARQ ACK and HARQ NACK.