Packet construction for communications across multiple access networks such as wireless local area networks

The present invention relates to packet construction or format for communications across multiple access networks such as wireless local area networks (WLAN). The present invention provides a device for use in a wireless network and comprising means for generating a packet comprising a first portion having a destination address and preferably a network duration identifier for a recipient device in the network, and a second portion; and means for transmitting the first portion at a predetermined coding and/or modulation rate, and means for transmitting the second portion at a higher coding and/or modulation rate.