Optimal link adaptation in wideband CDMA systems

Tim Holliday, Andrea Goldsmith, Peter Glynn

Research output: Contribution to conferencePaperpeer-review

3 Scopus citations


We develop a general framework for optimizing link adaptation for multiuser COMA systems in the wideband limit. The framework is then used to solve for the optimal power control policy that minimizes average transmit power while satisfying a constraint on the per-user probability of packet loss due to deadline expiration. The optimal link adaptation is found through an infinite horizon dynamic program. Typical dynamic programming formulations do not perform well for CDMA systems since the size of the problem grows exponentionally with the number of users. We show that in the limiting regime of long spreading codes and large numbers of users the problem size collapses to that of a single user formulation, allowing us to solve previously intractable problems. In particular, we consider a concrete example of power control in a CDMA system with deadline constrained traffic. We solve for the optimal power control policy and examine the tradeoffs between power consumption, probability of deadline expiration, and number of users in the system. Finally we present simulation results evaluating the accuracy of the wideband limit when used as an approximation for finite bandwidth systems. We show that the optimal power control and resulting performance for the limiting regime is a reasonable approximation for the large bandwidths expected in next generation wireless systems.

Original languageEnglish (US)
Number of pages6
StatePublished - 2002
Externally publishedYes
EventGLOBECOM'02 - IEEE Global Telecommunications Conference - Taipei, Taiwan, Province of China
Duration: Nov 17 2002Nov 21 2002


OtherGLOBECOM'02 - IEEE Global Telecommunications Conference
Country/TerritoryTaiwan, Province of China

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering
  • Global and Planetary Change


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