Methods, systems, and devices are described contention-based channel access procedures that may enhance efficiency in communications using unlicensed spectrum. A time period may be identified during which base stations perform contention-based downlink channel access procedures for access to a channel in an unlicensed spectrum. The base stations may be coordinated such that different base stations may seek channel access during different time intervals during the time period. Contention-based uplink channel access procedures for UEs may then be modified to favor one or more UEs that are associated with a base station that has won channel access.