A grant-free transmission mode may be used to communicate small traffic transmissions to reduce overhead and latency. The grant-free transmission mode may be used in downlink and uplink data channels of a wireless network. In the downlink channel, a base station transmits packets to a group of UEs in a search space without communicating any transmission code assignments to the UEs. The UEs receive the downlink packets using blind detection. In the uplink channel, UEs transmit packets in an access space using assigned access codes which are either independently derived by the UEs or otherwise communicated by the base station using a slow-signaling channel. Hence, the grant-free transmission mode allows mobile devices to make small traffic transmissions without waiting for uplink grant requests.