A mobile radio communication terminal device, comprising: at least one receiver; at least one transmitter; and one or more processors operatively coupled to a memory that stores computer readable software, wherein the computer readable software, when executed by the one or more processors, cause the mobile radio communication terminal device to: transmit, via the at least one transmitter, a physical sidelink control channel/sidelink control information, PSCCH/SCI, which includes feedback resource allocation information, to at least a second mobile radio communication terminal device; transmit, via the at least one transmitter, a physical sidelink shared channel, PSSCH message to at least the second mobile radio communication terminal device; receive, via the at least one receiver, either a non-acknowledgment, NACK, feedback message from the second mobile radio communication terminal device or no response, wherein when the NACK feedback message is received it indicates the PSSCH message was not successfully decoded and when no response is received an acknowledgement, ACK, of the successfully decoded PSSCH message is indicated and wherein a starting resource block and cyclic shift of a sequence for the NACK feedback message are determinable based on information included in the PSCCH/SCI; determine whether or not to retransmit the PSSCH message in response to receiving the NACK feedback message or no response, and retransmit, via the at least one transmitter, the PSSCH message if the mobile radio communication terminal device determines to retransmit the PSSCH message, and not retransmit the PSSCH message if the mobile radio communication terminal device determines not to retransmit the PSSCH message. at least one receiver; at least one transmitter; and one or more processors operatively coupled to a memory that stores computer readable software, wherein the computer readable software, when executed by the one or more processors, cause the mobile radio communication terminal device to: transmit, via the at least one transmitter, a physical sidelink control channel/sidelink control information, PSCCH/SCI, which includes feedback resource allocation information, to at least a second mobile radio communication terminal device; transmit, via the at least one transmitter, a physical sidelink shared channel, PSSCH message to at least the second mobile radio communication terminal device; receive, via the at least one receiver, either a non-acknowledgment, NACK, feedback message from the second mobile radio communication terminal device or no response, wherein when the NACK feedback message is received it indicates the PSSCH message was not successfully decoded and when no response is received an acknowledgement, ACK, of the successfully decoded PSSCH message is indicated and wherein a starting resource block and cyclic shift of a sequence for the NACK feedback message are determinable based on information included in the PSCCH/SCI; determine whether or not to retransmit the PSSCH message in response to receiving the NACK feedback message or no response, and retransmit, via the at least one transmitter, the PSSCH message if the mobile radio communication terminal device determines to retransmit the PSSCH message, and not retransmit the PSSCH message if the mobile radio communication terminal device determines not to retransmit the PSSCH message. transmit, via the at least one transmitter, a physical sidelink control channel/sidelink control information, PSCCH/SCI, which includes feedback resource allocation information, to at least a second mobile radio communication terminal device; transmit, via the at least one transmitter, a physical sidelink shared channel, PSSCH message to at least the second mobile radio communication terminal device; receive, via the at least one receiver, either a non-acknowledgment, NACK, feedback message from the second mobile radio communication terminal device or no response, wherein when the NACK feedback message is received it indicates the PSSCH message was not successfully decoded and when no response is received an acknowledgement, ACK, of the successfully decoded PSSCH message is indicated and wherein a starting resource block and cyclic shift of a sequence for the NACK feedback message are determinable based on information included in the PSCCH/SCI; determine whether or not to retransmit the PSSCH message in response to receiving the NACK feedback message or no response, and retransmit, via the at least one transmitter, the PSSCH message if the mobile radio communication terminal device determines to retransmit the PSSCH message, and not retransmit the PSSCH message if the mobile radio communication terminal device determines not to retransmit the PSSCH message.