In a wireless network, access points communicate with each other by transmitting and receiving data in first units and with client devices by transmitting and receiving data in second units over wireless links. A first unit encapsulates one or more second units addressed to client devices served by the same access point. Multiple second units encapsulated in a single first unit are transmitted with a single first-unit header. This scheme enables more payload data to be delivered with less overhead than would be required if every second unit were to be encapsulated in a separate first unit.