1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>Chapter 17. Spatial Multiplexing Powersave (SMPS)</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="The 802.11 subsystems – for kernel developers"><link rel="up" href="advanced.html" title="Part II. Advanced driver interface"><link rel="prev" href="API-enum-ieee80211-ampdu-mlme-action.html" title="enum ieee80211_ampdu_mlme_action"><link rel="next" href="API-ieee80211-request-smps.html" title="ieee80211_request_smps"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 17. Spatial Multiplexing Powersave (SMPS)</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-enum-ieee80211-ampdu-mlme-action.html">Prev</a> </td><th width="60%" align="center">Part II. Advanced driver interface</th><td width="20%" align="right"> <a accesskey="n" href="API-ieee80211-request-smps.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a name="smps"></a>Chapter 17. Spatial Multiplexing Powersave (SMPS)</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="refentrytitle"><a href="API-ieee80211-request-smps.html"><span class="phrase">ieee80211_request_smps</span></a></span><span class="refpurpose"> — 2 request SM PS transition 3 </span></dt><dt><span class="refentrytitle"><a href="API-enum-ieee80211-smps-mode.html"><span class="phrase">enum ieee80211_smps_mode</span></a></span><span class="refpurpose"> — 4 spatial multiplexing power save mode 5 </span></dt></dl></div><p> 6 </p><p> 7 SMPS (Spatial multiplexing power save) is a mechanism to conserve 8 power in an 802.11n implementation. For details on the mechanism 9 and rationale, please refer to 802.11 (as amended by 802.11n-2009) 10 <span class="quote">“<span class="quote">11.2.3 SM power save</span>”</span>. 11 </p><p> 12 The mac80211 implementation is capable of sending action frames 13 to update the AP about the station's SMPS mode, and will instruct 14 the driver to enter the specific mode. It will also announce the 15 requested SMPS mode during the association handshake. Hardware 16 support for this feature is required, and can be indicated by 17 hardware flags. 18 </p><p> 19 The default mode will be <span class="quote">“<span class="quote">automatic</span>”</span>, which nl80211/cfg80211 20 defines to be dynamic SMPS in (regular) powersave, and SMPS 21 turned off otherwise. 22 </p><p> 23 To support this feature, the driver must set the appropriate 24 hardware support flags, and handle the SMPS flag to the <code class="function">config</code> 25 operation. It will then with this mechanism be instructed to 26 enter the requested SMPS mode while associated to an HT AP. 27</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-enum-ieee80211-ampdu-mlme-action.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="advanced.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="API-ieee80211-request-smps.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">enum ieee80211_ampdu_mlme_action</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span class="phrase">ieee80211_request_smps</span></td></tr></table></div></body></html> 28