A tutorial on cross-layer optimization in wireless networks

Xiaojun Lin, Ness B. Shroff, R. Srikant

Research output: Contribution to journalArticlepeer-review


This tutorial paper overviews recent developments in optimization-based approaches for resource allocation problems in wireless systems. We begin by overviewing important results in the area of opportunistic (channel-aware) scheduling for cellular (single-hop) networks, where easily implementable myopic policies are shown to optimize system performance. We then describe key lessons learned and the main obstacles in extending the work to general resource allocation problems for multihop wireless networks. Towards this end, we show that a clean-slate optimization-based approach to the multihop resource allocation problem naturally results in a "loosely coupled" cross-layer solution. That is, the algorithms obtained map to different layers [transport, network, and medium access control/physical (MAC/PHY)] of the protocol stack, and are coupled through a limited amount of information being passed back and forth. It turns out that the optimal scheduling component at the MAC layer is very complex, and thus needs simpler (potentially imperfect) distributed solutions. We demonstrate how to use imperfect scheduling in the cross-layer framework and describe recently developed distributed algorithms along these lines. We conclude by describing a set of open research problems.

Original languageEnglish (US)
Article number1665000
Pages (from-to)1452-1463
Number of pages12
JournalIEEE Journal on Selected Areas in Communications
Issue number8
StatePublished - Aug 2006


  • Cellular networks
  • Congestion control
  • Cross-layer optimization
  • Imperfect schedule
  • Multihop wireless networks
  • Opportunistic scheduling

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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