A peer-to-peer (P2P) wireless network is designed to operate in a manner where all devices share a common wireless resource (i.e., spectrum) for both receive and transmit operations (i.e., time-division duplex scheme). A key objective of the P2P network is to facilitate discovery. i.e., the act of discovering devices in the radio frequency (RF) vicinity that a terminal can make a connection with (i.e., receive from and transmit to). The interconnection of P2P devices constitutes the network.
The discovery process generally requires P2P devices to periodically transmit an identifier (ID) probe message (possibly at pseudorandom times) intended to be received by other P2P devices in the RF vicinity. In general, a P2P device spends a majority of it's time listening for ID probes from other devices, and very small amount of time transmitting its own ID probe message.
An ID probe message typically includes various types of information, such as a unique ID of the device, a location of the device (if available), and a specific service advertised by the device. All P2P devices create and maintain a “discovery” database of other P2P devices in the RF vicinity. The discovery database then contains the information collected from the received ID probes.
The coverage around a specific node (i.e. device) in the P2P network is typically non-uniform and severely constrained compared to that of, for example, a macro-cell, a microcell or even a pico-cell. This is because many of the P2P devices are often buried in the local clutter and the propagation conditions can be highly variable, leading to large path-losses due to shadowing and building penetration losses. Because of the large degree of variability in the propagation, a device advertising a desired service may be discovered even if it is far away from a searching node (e.g., 1 km), while another device advertising the same desired service much closer to the searching node may not been discovered because of excessive path loss specific to the geometry and topology of the P2P network.