Finding a path subject to many additive QoS constraints

Guoliang Xue, Arunabha Sen, Weiyi Zhang, Jian Tang, Krishnaiya Thulasiraman

Research output: Contribution to journalArticlepeer-review

113 Scopus citations


A fundamental problem in quality-of-service (QoS) routing is to find a path between a source- destination node pair that satisfies two or more end-to-end QoS constraints. We model this problem using a graph with n vertices and edges with K additive QoS parameters associated with each edge, for any constant K ≥ 2. This problem is known to be NP-hard. Fully polynomial time approximation schemes (FPTAS) for the case of K = 2 have been reported in the literature. We concentrate on the general case and make the following contributions. 1) We present a very simple O(Km + n log n) time K-approximation algorithm that can be used in hop-by-hop routing protocols. 2) We present an FPTAS for one optimization version of the QoS routing problem with a time complexity of O(m (n/ε)K-1). 3) We present an FPTAS for another optimization version of the QoS routing problem with a time complexity of O(n log n + m (H/ε)K-1) when there exists an H-hop path satisfying all QoS constraints. When K is reduced to 2, our results compare favorably with existing algorithms. The results of this paper hold for both directed and undirected graphs. For ease of presentation, undirected graph is used.

Original languageEnglish (US)
Pages (from-to)201-211
Number of pages11
JournalIEEE/ACM Transactions on Networking
Issue number1
StatePublished - Feb 2007
Externally publishedYes


  • Efficient approximation algorithms
  • Multiple additive constraints
  • QoS routing

ASJC Scopus subject areas

  • Software
  • Computer Science Applications
  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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