Mathematical expressions for bit error rates in a wireless system are derived and provide insight into interference control.
In mobile communication systems, like UMTS or WLAN, the transmissions of different mobile devices interfere with each other. For example, when a mobile device transmits signals to its base station, other mobile devices transmitting on the same frequency band cause interference at that base station, which in turn may result in decoding errors in the intended signal. This form of interference becomes more and more relevant with the increasing number of wireless devices, and defines what is known as an interference-limited network. The number of incorrectly decoded bits per unit time is the bit error rate in the network.
Senior researchers Jorge F. Schmidt and Udo Schilcher together with their professor Christian Bettstetter at the University of Klagenfurt investigated the bit error rate in certain interference-limited networks using methods from stochastic geometry. They derived closed-form expressions for the average bit error rate in networks with randomly distributed users (Poisson point process) using a widely employed signal modulation scheme (Gray-coded quadrature amplitude modulation) to communicate over a typical radio channel (Nakagami fading) .
“A key difference to existing literature is that we consider the spatial characteristics of the network — the way in which interfering devices are distributed across the coverage area of the wireless system. These characteristics determine the usefulness of our expressions. We also provide examples on how our expressions can be applied in different contexts,” Schmidt says.
The researchers are in general interested in the way how interference influences the bit error rate, since this knowledge provides insight into the interference control mechanism to be implemented and helps to analyze the achievable data rates. Results have been published in a two-page paper in IET Electronics Letters. Work was supported by KWF/ERDF and FWF grants.
Jorge F. Schmidt, Udo Schilcher, and Christian Bettstetter. Exact Bit Error Rate Expressions for Interference-Limited Poisson Networks. IET Electronics Letters, vol. 52, no. 23, pp. 1961–1963, November 2016.