This specification describes several improvements to the Multiband OFDM (MB-OFDM) Physical Layer. A new PLCP frame format that better supports interoperability between 3-band and 7-band modes is described. An expanded PHY header is described with more reserved bits for future enhancements, an even number of OFDM symbols for the PLCP header that better supports time spreading and that the information is limited to just 2 OFDM symbols. A zero prefix is used to eliminate ripe in the transmitted spectrum so there is no back off required at the transmitter. A length 160 hierarchical sequence for the packet synchronization sequence is used to help eliminate the artificial side-lobe that is created during the correlation process at the receiver with the current length 128 hierarchical packet synchronization sequence.