1/*	$OpenBSD: ieee80211_rssadapt.c,v 1.11 2014/12/23 03:24:08 tedu Exp $	*/
2/*	$NetBSD: ieee80211_rssadapt.c,v 1.7 2004/05/25 04:33:59 dyoung Exp $	*/
3
4/*-
5 * Copyright (c) 2003, 2004 David Young.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or
8 * without modification, are permitted provided that the following
9 * conditions are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above
13 *    copyright notice, this list of conditions and the following
14 *    disclaimer in the documentation and/or other materials provided
15 *    with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
19 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
20 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
21 * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
22 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
23 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
26 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
28 * OF SUCH DAMAGE.
29 */
30
31#include <sys/param.h>
32#include <sys/systm.h>
33#include <sys/kernel.h>
34#include <sys/socket.h>
35
36#include <net/if.h>
37#include <net/if_media.h>
38
39#include <netinet/in.h>
40#include <netinet/if_ether.h>
41
42#include <net80211/ieee80211_var.h>
43#include <net80211/ieee80211_rssadapt.h>
44
45#ifdef interpolate
46#undef interpolate
47#endif
48#define interpolate(parm, old, new)				\
49	((parm##_old * (old) +					\
50	(parm##_denom - parm##_old) * (new)) / parm##_denom)
51
52#ifdef IEEE80211_DEBUG
53static	struct timeval lastrateadapt;	/* time of last rate adaptation msg */
54static	int currssadaptps = 0;		/* rate-adaptation msgs this second */
55static	int ieee80211_adaptrate = 4;	/* rate-adaptation max msgs/sec */
56
57#define RSSADAPT_DO_PRINT() \
58	((ieee80211_rssadapt_debug > 0) && \
59	 ppsratecheck(&lastrateadapt, &currssadaptps, ieee80211_adaptrate))
60#define	RSSADAPT_PRINTF(X) \
61	if (RSSADAPT_DO_PRINT()) \
62		printf X
63
64int ieee80211_rssadapt_debug = 0;
65
66#else
67#define	RSSADAPT_DO_PRINT() (0)
68#define	RSSADAPT_PRINTF(X)
69#endif
70
71static const struct ieee80211_rssadapt_expavgctl master_expavgctl = {
72	.rc_decay_denom		= 16,
73	.rc_decay_old		= 15,
74	.rc_thresh_denom	= 8,
75	.rc_thresh_old		= 4,
76	.rc_avgrssi_denom	= 8,
77	.rc_avgrssi_old		= 4
78};
79
80int
81ieee80211_rssadapt_choose(struct ieee80211_rssadapt *ra,
82    const struct ieee80211_rateset *rs, const struct ieee80211_frame *wh,
83    u_int len, int fixed_rate, const char *dvname, int do_not_adapt)
84{
85	u_int16_t (*thrs)[IEEE80211_RATE_SIZE];
86	int flags = 0, i, rateidx = 0, thridx, top;
87
88	if ((wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK) == IEEE80211_FC0_TYPE_CTL)
89		flags |= IEEE80211_RATE_BASIC;
90
91	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
92	     i < IEEE80211_RSSADAPT_BKTS;
93	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
94		thridx = i;
95		if (len <= top)
96			break;
97	}
98
99	thrs = &ra->ra_rate_thresh[thridx];
100
101	if (fixed_rate != -1) {
102		if ((rs->rs_rates[fixed_rate] & flags) == flags) {
103			rateidx = fixed_rate;
104			goto out;
105		}
106		flags |= IEEE80211_RATE_BASIC;
107		i = fixed_rate;
108	} else
109		i = rs->rs_nrates;
110
111	while (--i >= 0) {
112		rateidx = i;
113		if ((rs->rs_rates[i] & flags) != flags)
114			continue;
115		if (do_not_adapt)
116			break;
117		if ((*thrs)[i] < ra->ra_avg_rssi)
118			break;
119	}
120
121out:
122#ifdef IEEE80211_DEBUG
123	if (ieee80211_rssadapt_debug && dvname != NULL) {
124		printf("%s: dst %s threshold[%d, %d.%d] %d < %d\n",
125		    dvname, ether_sprintf((u_int8_t *)wh->i_addr1), len,
126		    (rs->rs_rates[rateidx] & IEEE80211_RATE_VAL) / 2,
127		    (rs->rs_rates[rateidx] & IEEE80211_RATE_VAL) * 5 % 10,
128		    (*thrs)[rateidx], ra->ra_avg_rssi);
129	}
130#endif /* IEEE80211_DEBUG */
131	return rateidx;
132}
133
134void
135ieee80211_rssadapt_updatestats(struct ieee80211_rssadapt *ra)
136{
137	long interval;
138
139	ra->ra_pktrate =
140	    (ra->ra_pktrate + 10 * (ra->ra_nfail + ra->ra_nok)) / 2;
141	ra->ra_nfail = ra->ra_nok = 0;
142
143	/* a node is eligible for its rate to be raised every 1/10 to 10
144	 * seconds, more eligible in proportion to recent packet rates.
145	 */
146	interval = MAX(100000, 10000000 / MAX(1, 10 * ra->ra_pktrate));
147	ra->ra_raise_interval.tv_sec = interval / (1000 * 1000);
148	ra->ra_raise_interval.tv_usec = interval % (1000 * 1000);
149}
150
151void
152ieee80211_rssadapt_input(struct ieee80211com *ic,
153    const struct ieee80211_node *ni, struct ieee80211_rssadapt *ra, int rssi)
154{
155#ifdef IEEE80211_DEBUG
156	int last_avg_rssi = ra->ra_avg_rssi;
157#endif
158
159	ra->ra_avg_rssi = interpolate(master_expavgctl.rc_avgrssi,
160	    ra->ra_avg_rssi, (rssi << 8));
161
162	RSSADAPT_PRINTF(("%s: src %s rssi %d avg %d -> %d\n",
163	    ic->ic_if.if_xname, ether_sprintf((u_int8_t *)ni->ni_macaddr),
164	    rssi, last_avg_rssi, ra->ra_avg_rssi));
165}
166
167/*
168 * Adapt the data rate to suit the conditions.  When a transmitted
169 * packet is dropped after IEEE80211_RSSADAPT_RETRY_LIMIT retransmissions,
170 * raise the RSS threshold for transmitting packets of similar length at
171 * the same data rate.
172 */
173void
174ieee80211_rssadapt_lower_rate(struct ieee80211com *ic,
175    const struct ieee80211_node *ni, struct ieee80211_rssadapt *ra,
176    const struct ieee80211_rssdesc *id)
177{
178	const struct ieee80211_rateset *rs = &ni->ni_rates;
179	u_int16_t last_thr;
180	u_int i, thridx, top;
181
182	ra->ra_nfail++;
183
184	if (id->id_rateidx >= rs->rs_nrates) {
185		RSSADAPT_PRINTF(("ieee80211_rssadapt_lower_rate: "
186		    "%s rate #%d > #%d out of bounds\n",
187		    ether_sprintf((u_int8_t *)ni->ni_macaddr), id->id_rateidx,
188		    rs->rs_nrates - 1));
189		return;
190	}
191
192	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
193	     i < IEEE80211_RSSADAPT_BKTS;
194	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
195		thridx = i;
196		if (id->id_len <= top)
197			break;
198	}
199
200	last_thr = ra->ra_rate_thresh[thridx][id->id_rateidx];
201	ra->ra_rate_thresh[thridx][id->id_rateidx] =
202	    interpolate(master_expavgctl.rc_thresh, last_thr,
203	    (id->id_rssi << 8));
204
205	RSSADAPT_PRINTF(("%s: dst %s rssi %d threshold[%d, %d.%d] %d -> %d\n",
206	    ic->ic_if.if_xname, ether_sprintf((u_int8_t *)ni->ni_macaddr),
207	    id->id_rssi, id->id_len,
208	    (rs->rs_rates[id->id_rateidx] & IEEE80211_RATE_VAL) / 2,
209	    (rs->rs_rates[id->id_rateidx] & IEEE80211_RATE_VAL) * 5 % 10,
210	    last_thr, ra->ra_rate_thresh[thridx][id->id_rateidx]));
211}
212
213void
214ieee80211_rssadapt_raise_rate(struct ieee80211com *ic,
215    struct ieee80211_rssadapt *ra, const struct ieee80211_rssdesc *id)
216{
217	u_int16_t (*thrs)[IEEE80211_RATE_SIZE], newthr, oldthr;
218	const struct ieee80211_node *ni = id->id_node;
219	const struct ieee80211_rateset *rs = &ni->ni_rates;
220	int i, rate, top;
221#ifdef IEEE80211_DEBUG
222	int j;
223#endif
224
225	ra->ra_nok++;
226
227	if (!ratecheck(&ra->ra_last_raise, &ra->ra_raise_interval))
228		return;
229
230	for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
231	     i < IEEE80211_RSSADAPT_BKTS;
232	     i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
233		thrs = &ra->ra_rate_thresh[i];
234		if (id->id_len <= top)
235			break;
236	}
237
238	if (id->id_rateidx + 1 < rs->rs_nrates &&
239	    (*thrs)[id->id_rateidx + 1] > (*thrs)[id->id_rateidx]) {
240		rate = (rs->rs_rates[id->id_rateidx + 1] & IEEE80211_RATE_VAL);
241
242		RSSADAPT_PRINTF(("%s: threshold[%d, %d.%d] decay %d ",
243		    ic->ic_if.if_xname, IEEE80211_RSSADAPT_BKT0 <<
244			(IEEE80211_RSSADAPT_BKTPOWER * i),
245		    rate / 2, rate * 5 % 10, (*thrs)[id->id_rateidx + 1]));
246		oldthr = (*thrs)[id->id_rateidx + 1];
247		if ((*thrs)[id->id_rateidx] == 0)
248			newthr = ra->ra_avg_rssi;
249		else
250			newthr = (*thrs)[id->id_rateidx];
251		(*thrs)[id->id_rateidx + 1] =
252		    interpolate(master_expavgctl.rc_decay, oldthr, newthr);
253
254		RSSADAPT_PRINTF(("-> %d\n", (*thrs)[id->id_rateidx + 1]));
255	}
256
257#ifdef IEEE80211_DEBUG
258	if (RSSADAPT_DO_PRINT()) {
259		printf("%s: dst %s thresholds\n", ic->ic_if.if_xname,
260		    ether_sprintf((u_int8_t *)ni->ni_macaddr));
261		for (i = 0; i < IEEE80211_RSSADAPT_BKTS; i++) {
262			printf("%d-byte", IEEE80211_RSSADAPT_BKT0 <<
263			    (IEEE80211_RSSADAPT_BKTPOWER * i));
264			for (j = 0; j < rs->rs_nrates; j++) {
265				rate = (rs->rs_rates[j] & IEEE80211_RATE_VAL);
266				printf(", T[%d.%d] = %d", rate / 2,
267				    rate * 5 % 10, ra->ra_rate_thresh[i][j]);
268			}
269			printf("\n");
270		}
271	}
272#endif /* IEEE80211_DEBUG */
273}
274