Cooperative transmission involves the simultaneous transmission by a group of devices, alldevices sending the same data. The devices may use sidelink (SL) to share data prior to thejoint transmission. Cooperative transmission helps improve network coverage since it can usethe combined transmission power of all devices in a group, whereas single-hop transmissionby one device is limited to its own maximum uplink power. Cooperative transmission aim is toimprove the network coverage of devices involved. The cooperative transmission solutioncomprisestwo steps. The first step is when a device (source device) in the group wants to senddata in the UL and then transmits data via SL to the devices in a created group. In the secondstep, all users simultaneously transmit the data in the UL to the base station the group isassigned to.This master thesis studies both the performance in the uplink (UL), comparing cooperativewith direct transmission, and how to reduce the power consumption of the devices involvedin the cooperative transmission.A power consumption model was developed to analyze the energy consumption, both viaanalytical and simulations methods. The analytical results show that cooperative transmissioncan reduce energy consumption by 7% compared to direct transmission. An algorithm wasproposed for cooperative transmission, which helps reduce energy consumption by 31%.Furthermore, the performance of cooperative transmissions was also studied using a systemsimulator. The results shows that the UL total bit rate increases with cooperative transmissionand is proportional to the number of users in the group. The total bit rate increased by 57%for a group with five users and for a group of 10 the increase was 107% (with a carrierfrequency of 3GHz). Different scenarios were simulated, and the increase in total bit ratevaries from 50-150%. Cooperative transmission involves the simultaneous transmission by a group of devices, alldevices sending the same data. The devices may use sidelink (SL) to share data prior to thejoint transmission. Cooperative transmission helps improve network coverage since it can usethe combined transmission power of all devices in a group, whereas single-hop transmissionby one device is limited to its own maximum uplink power. Cooperative transmission aim is toimprove the network coverage of devices involved. The cooperative transmission solutioncomprisestwo steps. The first step is when a device (source device) in the group wants to senddata in the UL and then transmits data via SL to the devices in a created group. In the secondstep, all users simultaneously transmit the data in the UL to the base station the group isassigned to.This master thesis studies both the performance in the uplink (UL), comparing cooperativewith direct transmission, and how to reduce the power consumption of the devices involvedin the cooperative transmission.A power consumption model was developed to analyze the energy consumption, both viaanalytical and simulations methods. The analytical results show that cooperative transmissioncan reduce energy consumption by 7% compared to direct transmission. An algorithm wasproposed for cooperative transmission, which helps reduce energy consumption by 31%.Furthermore, the performance of cooperative transmissions was also studied using a systemsimulator. The results shows that the UL total bit rate increases with cooperative transmissionand is proportional to the number of users in the group. The total bit rate increased by 57%for a group with five users and for a group of 10 the increase was 107% (with a carrierfrequency of 3GHz). Different scenarios were simulated, and the increase in total bit ratevaries from 50-150%.