FIG. 27 illustrates an example of a procedure of groupcast (or unicast) transmission with repetition transmissions of V2V communication. A Tx wireless device (e.g., Tx UE1) may receive one or more RRC messages from a base station at time T1. The one or more RRC messages may comprise configuration parameters. The configuration parameters may indicate: a plurality of repetition values of a PSSCH, and a plurality of repetition thresholds for the PSSCH. Each of the plurality of repetition values of the PSSCH may indicate a number of PSSCH repetition transmissions for a transport block of the sidelink communication. Each of the plurality of repetition thresholds may be a repetition value for a transmission of a transport block. A Tx wireless device and/or a Rx wireless device may control/determine whether a HARQ feedback is required based on the repetition threshold. The Rx wireless device (e.g., Rx UE2) may receive one or more RRC messages from the Tx wireless device (Tx UE1) at time T2. The one or more RRC messages may comprise configuration parameters of sidelink communication. The configuration parameters of sidelink communication may indicate: a plurality of repetition values of a PSSCH, and a plurality of repetition thresholds for the PSSCH. Each of the plurality of repetition values of the PSSCH may indicate a number of PSSCH repetition transmissions for a transport block of the sidelink communication. Each of the plurality of repetition thresholds may be a repetition value for a transmission of a transport block. A Tx wireless device and/or a Rx wireless device may control/determine whether a HARQ feedback is required based on the repetition threshold. In an example, the Rx wireless device (e.g., Rx UE2) may receive one or more RRC messages from the base station at time T2. The one or more RRC messages may comprise configuration parameters of sidelink communication. The configuration parameters of sidelink communication may indicate: a plurality of repetition values of a PSSCH, and a plurality of repetition thresholds for the PSSCH. Each of the plurality of repetition values of the PSSCH may indicate a number of PSSCH repetition transmissions for a transport block of the sidelink communication. Each of the plurality of repetition thresholds may be a repetition value for a transmission of a transport block. A Tx wireless device and/or a Rx wireless device may control/determine whether a HARQ feedback is required based on the repetition threshold. In an example, the configuration parameters may indicate a plurality of radio resources for the Tx wireless device (e.g., Tx UE1). The plurality of radio resources may comprise one or more radio resource pools. The one or more radio resource pools may comprise one or more transmission resources pools. The one or more radio resource pools may comprise one or more reception resources pools. In an example, each resources pool of the one or more transmission resource pools (or the one or more reception resource pools) may comprise at least one of: a control region, and a data region. The Tx wireless device (e.g., Tx UE1) may transmit a transport block via the data region of a transmission resource pool according to control information in the control region of the transmission resource pool. The Rx wireless device (e.g., Rx UE2) of the plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may receive the transport block via the data region of a reception resource pool of the Rx wireless device according to control information in a control region of the reception resource pool. In an example, the transmission resource pool of the Tx wireless device (e.g., Tx UE1) may have an association relationship with the reception resource pool of the Rx wireless device (e.g., Rx UE2). The association relationship may be a one-to-one mapping relationship. In an example, the configuration parameters may indicate the association relationship to the Tx wireless device and/or the Rx wireless device (e.g., Tx UE1 and/or Rx UE2).
