A wireless device may identify a set of resources reserved for feedback information (e.g., resource elements (REs) reserved for feedback such as acknowledgement (ACK) or negative ACK (NACK) information) within a transmission time interval (TTI). Feedback information may be mapped to the reserved set of resources (e.g., reserved REs). The wireless device may determine a set of unused reserved resources (e.g., a set of unused reserved REs) based on the number of feedback bits. The wireless device may then map other bits (e.g., zeros, known bits, pattern or sequence of bits, random bits, etc.) to the set of unused reserved REs, or boost transmission power of bits mapped around the unused reserved REs. In some cases, the number of reserved REs may be determined based on the number of feedback bits (e.g., the size of the ACK/NACK payload). The wireless device may then transmit the information to a base station.