In many telecommunication systems, communications networks are used to exchange messages among several interacting spatially-separated devices. Networks can be classified according to geographic scope, which could be, for example, a metropolitan area, a local area, or a personal area. Such networks would be designated respectively as a wide area network (WAN), metropolitan area network (MAN), local area network (LAN), wireless local area network (WLAN), or personal area network (PAN). Networks also differ according to the switching/routing technique used to interconnect the various network nodes and devices (e.g. circuit switching vs. packet switching), the type of physical media employed for transmission (e.g. wired vs. wireless), and the set of communication protocols used (e.g. Internet protocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).
Wireless networks are often preferred when the network elements are mobile and thus have dynamic connectivity needs, or if the network architecture is formed in an ad hoc, rather than fixed, topology. Wireless networks employ intangible physical media in an unguided propagation mode using electromagnetic waves in the radio, microwave, infra-red, optical, etc. frequency bands. Wireless networks advantageously facilitate user mobility and rapid field deployment when compared to fixed wired networks.
Devices in a wireless network can transmit and/or receive information to and from each other. The information can include packets, which in some aspects can be referred to as data units. The packets can include overhead information (e.g., header information, packet properties, etc.) that helps in routing the packets through the network, identifying the data in the packets, processing the packets, etc. The packets can further include data, such as user data, multimedia content, etc. that can be carried in a payload of the packet. Prior to sending a packet, a wireless device may first determine if the wireless medium is in use. If the medium is in use, the wireless device may defer sending a packet. However, in some cases it may be possible for two or more devices to transmit on the wireless medium simultaneously without disrupting each other's transmissions. Accordingly, more efficient systems and methods for timing various communications on a wireless medium are desired.