FreeBSD/Linux Kernel Cross Reference
sys/net80211/ieee80211_rssadapt.h

     /* $NetBSD: ieee80211_rssadapt.h,v 1.2 2004/03/17 17:00:35 dyoung Exp $ */
     /*-
      * Copyright (c) 2003, 2004 David Young.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or
      * without modification, are permitted provided that the following
      * conditions are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above
     *    copyright notice, this list of conditions and the following
     *    disclaimer in the documentation and/or other materials provided
     *    with the distribution.
     * 3. The name of David Young may not be used to endorse or promote
     *    products derived from this software without specific prior
     *    written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
     * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
     * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
     * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
     * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
     * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
     * OF SUCH DAMAGE.
     */
    
    /* Data-rate adaptation loosely based on "Link Adaptation Strategy
     * for IEEE 802.11 WLAN via Received Signal Strength Measurement"
     * by Javier del Prado Pavon and Sunghyun Choi.
     */   
    
    /* Buckets for frames 0-128 bytes long, 129-1024, 1025-maximum. */
    #define IEEE80211_RSSADAPT_BKTS         3
    #define IEEE80211_RSSADAPT_BKT0         128
    #define IEEE80211_RSSADAPT_BKTPOWER     3       /* 2**_BKTPOWER */      
    
    #define ieee80211_rssadapt_thresh_new \
        (ieee80211_rssadapt_thresh_denom - ieee80211_rssadapt_thresh_old)
    #define ieee80211_rssadapt_decay_new \
        (ieee80211_rssadapt_decay_denom - ieee80211_rssadapt_decay_old)
    #define ieee80211_rssadapt_avgrssi_new \
        (ieee80211_rssadapt_avgrssi_denom - ieee80211_rssadapt_avgrssi_old)
    
    struct ieee80211_rssadapt_expavgctl {
            /* RSS threshold decay. */
            u_int rc_decay_denom;
            u_int rc_decay_old;
            /* RSS threshold update. */
            u_int rc_thresh_denom;
            u_int rc_thresh_old;
            /* RSS average update. */
            u_int rc_avgrssi_denom;
            u_int rc_avgrssi_old;
    };
    
    struct ieee80211_rssadapt {
            /* exponential average RSSI << 8 */
            u_int16_t               ra_avg_rssi;
            /* Tx failures in this update interval */
            u_int32_t               ra_nfail;
            /* Tx successes in this update interval */
            u_int32_t               ra_nok;
            /* exponential average packets/second */
            u_int32_t               ra_pktrate;
            /* RSSI threshold for each Tx rate */
            u_int16_t               ra_rate_thresh[IEEE80211_RSSADAPT_BKTS]
                                                  [IEEE80211_RATE_SIZE];
            struct timeval          ra_last_raise;
            struct timeval          ra_raise_interval;
    };
    
    /* Properties of a Tx packet, for link adaptation. */  
    struct ieee80211_rssdesc {
            u_int                    id_len;        /* Tx packet length */
            u_int                    id_rateidx;    /* index into ni->ni_rates */
            struct ieee80211_node   *id_node;       /* destination STA MAC */
            u_int8_t                 id_rssi;       /* destination STA avg RSS @
                                                     * Tx time
                                                     */
    };
    
    void    ieee80211_rssadapt_updatestats(struct ieee80211_rssadapt *);
    void    ieee80211_rssadapt_input(struct ieee80211com *, struct ieee80211_node *,
                struct ieee80211_rssadapt *, int);
    void    ieee80211_rssadapt_lower_rate(struct ieee80211com *,
                struct ieee80211_node *, struct ieee80211_rssadapt *,
                struct ieee80211_rssdesc *);
    void    ieee80211_rssadapt_raise_rate(struct ieee80211com *,
                struct ieee80211_rssadapt *, struct ieee80211_rssdesc *);
    int     ieee80211_rssadapt_choose(struct ieee80211_rssadapt *,
                struct ieee80211_rateset *, struct ieee80211_frame *, u_int, int,
                const char *, int);

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