Distributed Power Control

Power control with fixed signal to interference ratio (SIR)

Here we can visualize the basic formulation of the distributed power control algorithm over a narrow range of inputs.

Each receiving channel is assigned a target SIR that is randomly sampled from a uniform distribution with range 1-3. Each mobile station is assigned an initial transmit power level that is randomly sampled from a uniform distribution with range 1-3mW. Gains for interference channels are randomly sampled from a uniform distribution with range 0.01-0.10. These inputs are displayed in tables where each row corresponds to a given mobile station. The input values used here are arbitrary and don't reflect actual numerical values observed in real cellular networks.

The transmit power of each mobile station is plotted as a line over time (i.e. over the DPC algorithm iterations). If there exists a set of transmit powers that satisfies all target SIRs, the minimal power solution is displayed in a table to the right of the input tables. Otherwise "No Solution" is displayed.

Users can:

• alter the seed for the random number generator (this will generate different inputs)
• set the number of mobile stations (3-9)
• set the receiver noise (0.1-0.5mW) which is assumed to be the same for all channels
• set the number of iterations for the DPC algorithm

Viz: bl.ocks.org/renschler Source: gist.github.com/renschler

References

Mobile station power control plays a crucial role in communication systems in terms of interference management, energy management, and connectivity management. For example, power control helps address the near-far problem faced in non-orthogonal wireless systems like CDMA.

• M. Chiang, "Chapter 1: What makes CDMA work for my Smartphone", Networked Life: 20 Questions and Answers, Cambridge University Press, 2012. (youtube lecture)
• M. Chiang, P. Hande, T. Lan, and C.W. Tan, "Power control for cellular networks", Foundation and Trends in Networking, vol. 2, no. 4, pp. 381-533, July 2008.