Communication apparatus includes a transceiver configured to communicate over a wireless channel in accordance with both a first and a second communication protocol. The second communication protocol is backward-compatible with the first communication protocol, and has an extended range, which is greater than a nominal range defined by the first communication protocol. A communication controller is configured to generate data frames for transmission by the transceiver, including frame headers in a header format that is compatible both with the first communication protocol and with the second communication protocol. The frame headers include a set of legacy header fields. The communication controller is configured to transmit the legacy fields with a first gain according to the first communication protocol, and to apply a second gain, greater than the first gain, to a transmission of at least one of the legacy header fields for communicating in accordance with the second communication protocol.