Battery power efficiency of PPM and FSK in wireless sensor networks

Qiuling Tang, Liuqing Yang, Georgios B. Giannakis, Tuanfa Qin

Research output: Contribution to journalArticlepeer-review

70 Scopus citations


As sensor nodes are typically powered by non-renewable batteries, energy efficiency is a critical factor in wireless sensor networks (WSNs). Orthogonal modulations appropriate for the energy-limited WSN setup have been investigated under the assumption that batteries are linear and ideal, but their effectiveness is not guaranteed when more realistic nonlinear battery models are considered. In this paper, based on a general model that integrates typical WSN transmission and reception modules with realistic battery models, we derive two battery power-conserving schemes for two M-ary orthogonal modulations, namely pulse position modulation (PPM) and frequency shift keying (FSK), both tailored for WSNs. Then we analyze and compare the battery power efficiency of PPM and FSK over various wireless channel models. Our results reveal that FSK is more power-efficient than PPM in sparse WSNs, while PPM may outperform FSK in dense WSNs. We also show that in sparse WSNs, the power advantage of FSK over PPM is no more than 3dB; whereas in very dense WSNs, the power advantage of PPM over FSK can be much more significant as the constellation size M increases.

Original languageEnglish (US)
Pages (from-to)1308-1318
Number of pages11
JournalIEEE Transactions on Wireless Communications
Issue number4
StatePublished - Apr 2007
Externally publishedYes

Bibliographical note

Funding Information:
Manuscript received December 11, 2004; revised July 29 and December 4, 2005; accepted December 5, 2005. The associate editor coordinating the review of this letter and approving it for publication was R. Negi. Part of this work was presented at the Milcom Conf., Atlantic City, NJ, Oct. 17-20, 2005. The work of the first and fourth authors was supported by the Science Research Foundation of Guangxi Education Department of China No. [2002]316. The work of the third author was supported by the NSF Grant No. EIA-0324864 and by the USDoD Army Grant No. W911NF-05-1-0283.


  • Battery power efficiency
  • Fading
  • Frequency shift keying (FSK)
  • Pulse position modulation (PPM)
  • Wireless sensor networks (WSN)


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