Power, Rate and QoS Control for Impulse Radio

Because of its limitations due to interference, ultra- wideband impulse radio needs a careful investigation of the signal-to-interference ratio (SIR). This paper contributes to understanding the theoretical foundations of the SIR effects in multi-user impulse radio systems. Two basic aspects are investigated. First, the set of admissible power allocations to maintain certain quality-of-service thresholds is described. Secondly, the geometry of the set of feasible reciprocal bit rates is characterized. Both sets turn out to have certain monotonicity and convexity properties. We furthermore discuss the case that the pulse repetition time is used as a global parameter to achieve an admissible power allocation at the price of proportionally reduced quality-of-service parameters. Techniques from analyzing code division multiple access systems are generalized and applied to impulse radio in this paper.