Solution to the Sum Power Minimization Problem under Given Rate Requirements for the OFDM Multiple Access Channel

In this paper, we investigate the sum power minimization problem subject to given rate requirements for an orthogonal frequency division multiplexing (OFDM) multiple-access channel (MAC). This problem is interesting not only from an information-theoretic point of view but also of significant relevance for practical purposes, since it establishes the key to optimal resource allocation in OFDM when Quality of Service (QoS) demands have to be guaranteed. The 'dual' problem, i.e. the maximization of a weighted sum of rates, is well understood. Here, the linear weights determine the optimal decoding order, assuring simultaneously the convexity of the problem. In contrast, determining the optimal decoding order for the problem at hand is crucial. As we show, the decoding order problem can not be tackled isolated from the resource allocation problem itself. In contrast to recent approaches, our solution uses the particular structure of the capacity region, turning the nonconvex problem into a convex one. Further, it motivates a highly efficient algorithm. Due to duality results, all results can easily be transfered to the non-degraded OFDM broadcast channel (BC).

• Multi-carrier Systems
• Signal Processing
• Information Theory

@inproceedings{MW05stts,
   author          = "T. Michel and G. Wunder", 
   title           = "{Solution to the Sum Power Minimization Problem under Given Rate Requirements for the
    OFDM Multiple Access Channel}", 
   booktitle       = "{Proc. of Allerton Conference on Communication, Control and Computing}", 
   address         = "Monticello, USA", 
   month           = sep, 
   year            = "2005", 
}