# US 8,571,057 B2 · Methods and apparatus for multi-carrier communications systems with automatic repeat request (ARQ) > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,571,057 B2 - Document ID: US8571057B2 - Status: Granted - Kind: B2 - Application number: 10/583,239 - Filed: 2005-02-07 - Published: 2011-03-03 - Granted: 2013-10-29 - Earliest claimed: 2004-02-07 - Assignees: Neocific, Inc. - Applicants: Xiaodong Li; Haiming Huang; Titus Lo; Kemin Li - Inventors: Xiaodong Li; Haiming Huang; Titus Lo; Kemin Li - Web page: https://patentgrep.com/patent/US8571057B2 ## CPC - H04L 1/1812: Hybrid protocols; Hybrid automatic repeat request [HARQ] - H04L 1/0026: {Transmission of channel quality indication} - H04L 1/1671: {the supervisory signal being transmitted together with control information} - H04L 5/003: {Arrangements for allocating sub-channels of the transmission path} - H04L 5/0055: {Physical resource allocation for ACK/NACK (for physical mapping arrangements in ARQ protocols H04L1/1861)} - H04W 72/20: Control channels or signalling for resource management - H04W 74/002: {Transmission of channel access control information} - H04L 1/0003: {by switching between different modulation schemes} - H04L 1/0013: {Rate matching, e.g. puncturing or repetition of code symbols} - H04L 1/1816: {with retransmission of the same, encoded, message} - H04L 1/1819: {with retransmission of additional or different redundancy} - H04L 1/1822: involving configuration of automatic repeat request [ARQ] with parallel processes - H04L 1/1845: {Combining techniques, e.g. code combining} - H04L 2001/0092: {Error control systems characterised by the topology of the transmission link} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Hybrid ARQ is employed in a multi-carrier communication system for retransmission of erroneous packets by taking advantage of time/frequency/space diversity and by combining ARQ functions at physical layer and MAC layers, making the multi-carrier system more robust in a high packet-error environment. ## Claims ### Claim 1 A method for a transmitter operating over at least two allocated subchannels in a communication system, each subchannel containing a plurality of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers, the method comprising: transmitting, at a first transmission time to a receiver in the communication system, a first data packet over a first subchannel and a second data packet over a second subchannel; receiving a negative acknowledgement (NACK) from the receiver regarding the first data packet, the NACK indicating an error in the first data packet received by the receiver; and implementing a transmission swapping procedure with the first subchannel and the second subchannel at a second transmission time, the transmission swapping procedure enabling recovery of the first data packet by: re-transmitting the first data packet or its parity data over the second subchannel; and transmitting a third data packet originally scheduled for the second subchannel over the first subchannel, wherein the first subchannel and second subchannels have different spatial configurations and different pilot subcarrier compositions. ### Claim 2 (depends on 1) The method of claim 1, wherein the pilot subcarrier composition is selected from a group of phase, amplitude, or location. ### Claim 3 (depends on 1) The method of claim 1, further comprising receiving a channel quality indicator (CQI), channel measurements, or both along from the receiver. ### Claim 4 (depends on 3) The method of claim 3, further comprising selecting the first and second subchannels based on the received CQI, channel measurements, or both. ### Claim 5 (depends on 1) The method of claim 1, wherein the transmission or re-transmission over the first or second subchannel uses an adaptive modulation and coding scheme. ### Claim 6 (depends on 1) The method of claim 1, wherein the re-transmission over the second subchannel uses a rate-matching scheme. ### Claim 7 (depends on 1) The method of claim 1, wherein the parity data is a progressive parity packet. ### Claim 8 A method for a receiver operating over at least two allocated subchannels in a communication system, each subchannel containing a plurality of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers, the method comprising: receiving, at a first reception time from a transmitter in the communication system, a first data packet over a first subchannel and a second data packet over a second subchannel; transmitting a negative acknowledgement (NACK) regarding the first data packet to the transmitter if there is an error in the first data packet; and receiving, at a second reception time, the re-transmission of the first data packet or its parity data over the second subchannel and transmission of a third data packet originally scheduled for the second subchannel over the first subchannel, wherein the first subchannel and second subchannels have different spatial configurations and different pilot subcarrier compositions; and combining the data received over the first subchannel at the first reception time and the data received over the second subchannel at the second reception time to recover the first data packet. ### Claim 9 (depends on 8) The method of claim 8, wherein the the pilot subcarrier composition is selected from a group of phase, amplitude, and location. ### Claim 10 (depends on 8) The method of claim 8, further comprising transmitting a channel quality indicator (CQI), channel measurements, or both agon to the transmitter. ### Claim 11 (depends on 10) The method of claim 10, wherein the CQI, channel measurements, or both are transmitted to assist the selection of the first and second subchannels. ### Claim 12 (depends on 8) The method of claim 8, wherein transmission or re-transmission over the first or second subchannel uses an adaptive modulation and coding scheme. ### Claim 13 (depends on 8) The method of claim 8, wherein the data packet is received using a rate matching scheme over the second subchannel. ### Claim 14 (depends on 8) The method of claim 8, wherein the parity data associated with the data packet is progressive parity data. ### Claim 15 A transmitter operating over at least two allocated subchannels in a communication system, each subchannel containing a plurality of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers, the transmitter comprising: an apparatus configured to transmit to a receiver in the communication system a first data packet over a first subchannel and a second data packet over a second subchannel at a first transmission time; an apparatus configured to receive a negative acknowledgement (NACK) from the receiver regarding the first data packet, the NACK indicating an error in the first data packet received by the receiver; and an apparatus configured to implement a transmission swapping procedure with the first subchannel and the second subchannel at a second transmission time, the transmission swapping procedure enabling recovery of the first data packet by: re-transmitting the first data packet or its parity data over the second subchannel; and transmitting a third data packet originally scheduled for the second subchannel over the first subchannel, wherein the first subchannel and second subchannel have different spatial configurations and different pilot subcarrier compositions. ### Claim 16 A receiver operating over at least two allocated subchannels in a communication system, each subchannel containing a plurality of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers, the method comprising: an apparatus configured to receive from a transmitter in the communication system a first data packet over a first subchannel and a second data packet over a second subchannel at a first reception time; an apparatus configured to transmit a negative acknowledgement (NACK) regarding the first data packet to the transmitter if there is an error in the first data packet; an apparatus configured to receive the first data packet or its parity data over the second subchannel and a third data packet originally scheduled for the second subchannel over the first subchannel at a second reception time, wherein the first subchannel and second subchannel have different spatial configurations and different pilot subcarrier compositions; and an apparatus configured to combine the data received over the first subchannel at the first reception time and the data received over the second subchannel at the second reception time to recover the first data packet.