/*
* Copyright (c) 2008, Swedish Institute of Computer Science.
* 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. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 THE INSTITUTE OR CONTRIBUTORS 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.
*
* This file is part of the Contiki operating system.
*
* $Id: lpp.c,v 1.14 2009/03/31 14:44:13 nvt-se Exp $
*/
/**
* \file
* Low power probing (R. Musaloiu-Elefteri, C. Liang,
* A. Terzis. Koala: Ultra-Low Power Data Retrieval in
* Wireless Sensor Networks, IPSN 2008)
*
* \author
* Adam Dunkels <adam@sics.se>
*
*
* This is an implementation of the LPP (Low-Power Probing) MAC
* protocol. LPP is a power-saving MAC protocol that works by sending
* a probe packet each time the radio is turned on. If another node
* wants to transmit a packet, it can do so after hearing the
* probe. To send a packet, the sending node turns on its radio to
* listen for probe packets.
*
*/
#include "dev/leds.h"
#include "lib/list.h"
#include "lib/memb.h"
#include "lib/random.h"
#include "net/rime.h"
#include "net/mac/mac.h"
#include "net/mac/lpp.h"
#include "net/rime/packetbuf.h"
#include "net/rime/announcement.h"
#include <stdlib.h>
#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
struct announcement_data {
uint16_t id;
uint16_t value;
};
#define ANNOUNCEMENT_MSG_HEADERLEN 2
struct announcement_msg {
uint16_t num;
struct announcement_data data[];
};
#define LPP_PROBE_HEADERLEN 2
#define TYPE_PROBE 1
#define TYPE_DATA 2
struct lpp_hdr {
uint16_t type;
rimeaddr_t sender;
rimeaddr_t receiver;
};
static const struct radio_driver *radio;
static void (* receiver_callback)(const struct mac_driver *);
static struct pt pt;
static struct ctimer timer;
static uint8_t is_listening = 0;
#define LISTEN_TIME CLOCK_SECOND / 32
#define OFF_TIME CLOCK_SECOND * 1
#define PACKET_LIFETIME (LISTEN_TIME + OFF_TIME)
#define UNICAST_TIMEOUT 2 * PACKET_LIFETIME
struct queue_list_item {
struct queue_list_item *next;
struct queuebuf *packet;
struct ctimer timer;
};
#ifdef QUEUEBUF_CONF_NUM
#define MAX_QUEUED_PACKETS QUEUEBUF_CONF_NUM / 2
#else /* QUEUEBUF_CONF_NUM */
#define MAX_QUEUED_PACKETS 4
#endif /* QUEUEBUF_CONF_NUM */
LIST(queued_packets_list);
MEMB(queued_packets_memb, struct queue_list_item, MAX_QUEUED_PACKETS);
/*---------------------------------------------------------------------------*/
static void
turn_radio_on(void)
{
radio->on();
leds_on(LEDS_YELLOW);
}
/*---------------------------------------------------------------------------*/
static void
turn_radio_off(void)
{
radio->off();
leds_off(LEDS_YELLOW);
}
/*---------------------------------------------------------------------------*/
static void
remove_queued_packet(void *item)
{
struct queue_list_item *i = item;
ctimer_stop(&i->timer);
queuebuf_free(i->packet);
list_remove(queued_packets_list, i);
memb_free(&queued_packets_memb, i);
/* XXX potential optimization */
if(list_length(queued_packets_list) == 0 && is_listening == 0) {
turn_radio_off();
}
}
/*---------------------------------------------------------------------------*/
static void
listen_callback(int periods)
{
is_listening = periods;
turn_radio_on();
}
/*---------------------------------------------------------------------------*/
/**
* Send a probe packet.
*/
static void
send_probe(void)
{
struct lpp_hdr *hdr;
struct announcement_msg *adata;
struct announcement *a;
/* Set up the probe header. */
packetbuf_clear();
packetbuf_set_datalen(sizeof(struct lpp_hdr));
hdr = packetbuf_dataptr();
hdr->type = TYPE_PROBE;
rimeaddr_copy(&hdr->sender, &rimeaddr_node_addr);
rimeaddr_copy(&hdr->receiver, packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
/* Construct the announcements */
adata = (struct announcement_msg *)((char *)hdr + sizeof(struct lpp_hdr));
adata->num = 0;
for(a = announcement_list(); a != NULL; a = a->next) {
adata->data[adata->num].id = a->id;
adata->data[adata->num].value = a->value;
adata->num++;
}
packetbuf_set_datalen(sizeof(struct lpp_hdr) +
ANNOUNCEMENT_MSG_HEADERLEN +
sizeof(struct announcement_data) * adata->num);
/* PRINTF("Sending probe\n");*/
radio->send(packetbuf_hdrptr(), packetbuf_totlen());
}
/*---------------------------------------------------------------------------*/
/**
* Duty cycle the radio. The protothread is driven by a ctimer that is
* initiated in the lpp_init() function.
*/
static int
dutycycle(void *ptr)
{
struct ctimer *t = ptr;
PT_BEGIN(&pt);
while(1) {
turn_radio_on();
send_probe();
ctimer_set(t, LISTEN_TIME, (void (*)(void *))dutycycle, t);
PT_YIELD(&pt);
if(list_length(queued_packets_list) == 0) {
if(is_listening == 0) {
turn_radio_off();
/* There is a bit of randomness here right now to avoid collisions
due to synchronization effects. Not sure how needed it is
though. XXX */
ctimer_set(t, OFF_TIME / 2 + (random_rand() % (OFF_TIME / 2)),
(void (*)(void *))dutycycle, t);
PT_YIELD(&pt);
} else {
is_listening--;
ctimer_set(t, OFF_TIME, (void (*)(void *))dutycycle, t);
PT_YIELD(&pt);
}
} else {
ctimer_set(t, OFF_TIME, (void (*)(void *))dutycycle, t);
PT_YIELD(&pt);
}
}
PT_END(&pt);
}
/*---------------------------------------------------------------------------*/
/**
*
* Send a packet. This function builds a complete packet with an LPP
* header and queues the packet. When a probe is heard (in the
* read_packet() function), and the sender of the probe matches the
* receiver of the queued packet, the queued packet is sent.
*
* ACK packets are treated differently from other packets: if a node
* sends a packet that it expects to be ACKed, the sending node keeps
* its radio on for some time after sending its packet. So we do not
* need to wait for a probe packet: we just transmit the ACK packet
* immediately.
*
*/
static int
send_packet(void)
{
struct lpp_hdr *hdr;
clock_time_t timeout;
packetbuf_hdralloc(sizeof(struct lpp_hdr));
hdr = packetbuf_hdrptr();
rimeaddr_copy(&hdr->sender, &rimeaddr_node_addr);
rimeaddr_copy(&hdr->receiver, packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
hdr->type = TYPE_DATA;
packetbuf_compact();
PRINTF("%d.%d: queueing packet to %d.%d, channel %d\n",
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
hdr->receiver.u8[0], hdr->receiver.u8[1],
packetbuf_attr(PACKETBUF_ATTR_CHANNEL));
if(packetbuf_attr(PACKETBUF_ATTR_PACKET_TYPE) == PACKETBUF_ATTR_PACKET_TYPE_ACK) {
/* Immediately send ACKs - we're assuming that the other node is
listening. */
/* printf("Immediately sending ACK\n");*/
return radio->send(packetbuf_hdrptr(), packetbuf_totlen());
} else {
struct queue_list_item *i;
i = memb_alloc(&queued_packets_memb);
if(i != NULL) {
i->packet = queuebuf_new_from_packetbuf();
if(i->packet == NULL) {
memb_free(&queued_packets_memb, i);
return 0;
} else {
list_add(queued_packets_list, i);
timeout = UNICAST_TIMEOUT;
if(rimeaddr_cmp(&hdr->receiver, &rimeaddr_null)) {
timeout = PACKET_LIFETIME;
}
ctimer_set(&i->timer, timeout, remove_queued_packet, i);
/* Wait for a probe packet from a neighbor */
turn_radio_on();
}
}
}
return 1;
}
/*---------------------------------------------------------------------------*/
/**
* Read a packet from the underlying radio driver. If the incoming
* packet is a probe packet and the sender of the probe matches the
* destination address of the queued packet (if any), the queued packet
* is sent.
*/
static int
read_packet(void)
{
int len;
struct lpp_hdr *hdr;
packetbuf_clear();
len = radio->read(packetbuf_dataptr(), PACKETBUF_SIZE);
if(len > 0) {
packetbuf_set_datalen(len);
hdr = packetbuf_dataptr();
packetbuf_hdrreduce(sizeof(struct lpp_hdr));
/* PRINTF("got packet type %d\n", hdr->type);*/
if(hdr->type == TYPE_PROBE) {
/* Parse incoming announcements */
struct announcement_msg *adata = packetbuf_dataptr();
int i;
/* PRINTF("%d.%d: probe from %d.%d with %d announcements\n",
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
hdr->sender.u8[0], hdr->sender.u8[1], adata->num);*/
for(i = 0; i < adata->num; ++i) {
/* PRINTF("%d.%d: announcement %d: %d\n",
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
adata->data[i].id,
adata->data[i].value);*/
announcement_heard(&hdr->sender,
adata->data[i].id,
adata->data[i].value);
}
if(list_length(queued_packets_list) > 0) {
struct queue_list_item *i;
for(i = list_head(queued_packets_list); i != NULL; i = i->next) {
struct lpp_hdr *qhdr;
qhdr = queuebuf_dataptr(i->packet);
if(rimeaddr_cmp(&qhdr->receiver, &hdr->sender) ||
rimeaddr_cmp(&qhdr->receiver, &rimeaddr_null)) {
PRINTF("%d.%d: got a probe from %d.%d, sending packet to %d.%d\n",
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
hdr->sender.u8[0], hdr->sender.u8[1],
qhdr->receiver.u8[0], qhdr->receiver.u8[1]);
radio->send(queuebuf_dataptr(i->packet),
queuebuf_datalen(i->packet));
/* If the packet was not a broadcast packet, we dequeue it
now. Broadcast packets should be transmitted to all
neighbors, and are dequeued by the dutycycling function
instead, after the appropriate time. */
if(!rimeaddr_cmp(&qhdr->receiver, &rimeaddr_null)) {
remove_queued_packet(i);
}
turn_radio_on(); /* XXX Awaiting an ACK: we should check the
packet type of the queued packet to see
if it is a data packet. If not, we
should not turn the radio on. */
}
}
}
} else if(hdr->type == TYPE_DATA) {
PRINTF("%d.%d: got data from %d.%d\n",
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
hdr->sender.u8[0], hdr->sender.u8[1]);
/* XXX send probe after receiving a packet to facilitate data
streaming. We must first copy the contents of the packetbuf into
a queuebuf to avoid overwriting the data with the probe packet. */
if(rimeaddr_cmp(&hdr->receiver, &rimeaddr_node_addr)) {
struct queuebuf *q;
q = queuebuf_new_from_packetbuf();
if(q != NULL) {
send_probe();
queuebuf_to_packetbuf(q);
queuebuf_free(q);
}
}
}
len = packetbuf_datalen();
}
return len;
}
/*---------------------------------------------------------------------------*/
static void
set_receive_function(void (* recv)(const struct mac_driver *))
{
receiver_callback = recv;
}
/*---------------------------------------------------------------------------*/
static int
on(void)
{
turn_radio_on();
return 1;
}
/*---------------------------------------------------------------------------*/
static int
off(int keep_radio_on)
{
if(keep_radio_on) {
turn_radio_on();
} else {
turn_radio_off();
}
return 1;
}
/*---------------------------------------------------------------------------*/
static const struct mac_driver lpp_driver = {
"LPP",
send_packet,
read_packet,
set_receive_function,
on,
off,
};
/*---------------------------------------------------------------------------*/
static void
input_packet(const struct radio_driver *d)
{
if(receiver_callback) {
receiver_callback(&lpp_driver);
}
}
/*---------------------------------------------------------------------------*/
const struct mac_driver *
lpp_init(const struct radio_driver *d)
{
radio = d;
radio->set_receive_function(input_packet);
ctimer_set(&timer, LISTEN_TIME, (void (*)(void *))dutycycle, &timer);
announcement_register_listen_callback(listen_callback);
memb_init(&queued_packets_memb);
list_init(queued_packets_list);
return &lpp_driver;
}
/*---------------------------------------------------------------------------*/