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Use collisions for csma backoff and retry

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The collision count is now used in the calculation fot the CSMA
backoff and transmission will fail after a certain number of
collisisons.
This commit is contained in:
Billy Kozak 2016-04-01 10:41:02 -06:00
parent 5b5f07ba52
commit ca0f32f45b
1 changed files with 126 additions and 92 deletions
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218
core/net/mac/csma.c
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@ -123,7 +123,6 @@ LIST(neighbor_list);
static void packet_sent(void *ptr, int status, int num_transmissions); static void packet_sent(void *ptr, int status, int num_transmissions);
static void transmit_packet_list(void *ptr); static void transmit_packet_list(void *ptr);
/*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/
static struct neighbor_queue * static struct neighbor_queue *
neighbor_queue_from_addr(const linkaddr_t *addr) neighbor_queue_from_addr(const linkaddr_t *addr)
@ -150,7 +149,7 @@ default_timebase(void)
does not turn the radio off), we make the retransmission time does not turn the radio off), we make the retransmission time
proportional to the configured MAC channel check rate. */ proportional to the configured MAC channel check rate. */
if(time == 0) { if(time == 0) {
time = CLOCK_SECOND / NETSTACK_RDC_CHANNEL_CHECK_RATE; time = (CLOCK_SECOND / 3125) ? (CLOCK_SECOND / 3125) : 1;
} }
return time; return time;
} }
@ -202,34 +201,116 @@ free_packet(struct neighbor_queue *n, struct rdc_buf_list *p, int status)
} }
/*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/
static void static void
tx_done(int status, struct rdc_buf_list *q, struct neighbor_queue *n)
{
mac_callback_t sent;
struct qbuf_metadata *metadata;
void *cptr;
metadata = (struct qbuf_metadata *)q->ptr;
sent = metadata->sent;
cptr = metadata->cptr;
switch(status) {
case MAC_TX_OK:
PRINTF("csma: rexmit ok %d\n", n->transmissions);
break;
case MAC_TX_COLLISION:
case MAC_TX_NOACK:
PRINTF("csma: drop with status %d after %d transmissions, %d collisions\n",
status, n->transmissions, n->collisions);
break;
default:
PRINTF("csma: rexmit failed %d: %d\n", n->transmissions, status);
break;
}
free_packet(n, q, status);
mac_call_sent_callback(sent, cptr, status, n->transmissions);
}
/*---------------------------------------------------------------------------*/
static void
rexmit(struct rdc_buf_list *q, struct neighbor_queue *n)
{
clock_time_t time;
int backoff_exponent;
int backoff_transmissions;
time = default_timebase();
backoff_exponent = n->collisions;
/* Proceed to exponentiation. */
backoff_transmissions = 1 << backoff_exponent;
/* Pick a time for next transmission, within the interval:
* [time, time + 2^backoff_exponent * time[ */
time = time + (random_rand() % (backoff_transmissions * time));
PRINTF("csma: retransmitting with time %lu %p\n", time, q);
ctimer_set(&n->transmit_timer, time, transmit_packet_list, n);
/* This is needed to correctly attribute energy that we spent
transmitting this packet. */
queuebuf_update_attr_from_packetbuf(q->buf);
}
/*---------------------------------------------------------------------------*/
static void
collision(struct rdc_buf_list *q, struct neighbor_queue *n,
int num_transmissions)
{
struct qbuf_metadata *metadata;
metadata = (struct qbuf_metadata *)q->ptr;
n->collisions += num_transmissions;
if(n->collisions > CSMA_MAX_BACKOFF_EXPONENT) {
n->collisions = 0;
n->transmissions += num_transmissions;
}
if(n->transmissions >= metadata->max_transmissions) {
tx_done(MAC_TX_COLLISION, q, n);
} else {
PRINTF("csma: rexmit collision %d\n", n->transmissions);
rexmit(q, n);
}
}
/*---------------------------------------------------------------------------*/
static void
noack(struct rdc_buf_list *q, struct neighbor_queue *n, int num_transmissions)
{
struct qbuf_metadata *metadata;
metadata = (struct qbuf_metadata *)q->ptr;
n->transmissions += num_transmissions;
n->collisions = 0;
if(n->transmissions >= metadata->max_transmissions) {
tx_done(MAC_TX_NOACK, q, n);
} else {
PRINTF("csma: rexmit noack %d\n", n->transmissions);
rexmit(q, n);
}
}
/*---------------------------------------------------------------------------*/
static void
tx_ok(struct rdc_buf_list *q, struct neighbor_queue *n, int num_transmissions)
{
n->transmissions += num_transmissions;
tx_done(MAC_TX_OK, q, n);
}
/*---------------------------------------------------------------------------*/
static void
packet_sent(void *ptr, int status, int num_transmissions) packet_sent(void *ptr, int status, int num_transmissions)
{ {
struct neighbor_queue *n; struct neighbor_queue *n;
struct rdc_buf_list *q; struct rdc_buf_list *q;
struct qbuf_metadata *metadata;
clock_time_t time = 0;
mac_callback_t sent;
void *cptr;
int num_tx;
int backoff_exponent;
int backoff_transmissions;
n = ptr; n = ptr;
if(n == NULL) { if(n == NULL) {
return; return;
} }
switch(status) {
case MAC_TX_OK:
case MAC_TX_NOACK:
n->transmissions += num_transmissions;
break;
case MAC_TX_COLLISION:
n->collisions += num_transmissions;
break;
case MAC_TX_DEFERRED:
n->deferrals += num_transmissions;
break;
}
/* Find out what packet this callback refers to */ /* Find out what packet this callback refers to */
for(q = list_head(n->queued_packet_list); for(q = list_head(n->queued_packet_list);
@ -240,78 +321,31 @@ packet_sent(void *ptr, int status, int num_transmissions)
} }
} }
if(q != NULL) { if(q == NULL) {
metadata = (struct qbuf_metadata *)q->ptr; PRINTF("csma: seqno %d not found\n",
packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO));
return;
} else if(q->ptr == NULL) {
PRINTF("csma: no metadata\n");
return;
}
if(metadata != NULL) { switch(status) {
sent = metadata->sent; case MAC_TX_OK:
cptr = metadata->cptr; tx_ok(q, n, num_transmissions);
num_tx = n->transmissions; break;
if(status == MAC_TX_COLLISION || case MAC_TX_NOACK:
status == MAC_TX_NOACK) { noack(q, n, num_transmissions);
break;
/* If the transmission was not performed because of a case MAC_TX_COLLISION:
collision or noack, we must retransmit the packet. */ collision(q, n, num_transmissions);
break;
switch(status) { case MAC_TX_DEFERRED:
case MAC_TX_COLLISION: n->deferrals += num_transmissions;
PRINTF("csma: rexmit collision %d\n", n->transmissions); break;
break; default:
case MAC_TX_NOACK: tx_done(status, q, n);
PRINTF("csma: rexmit noack %d\n", n->transmissions); break;
break;
default:
PRINTF("csma: rexmit err %d, %d\n", status, n->transmissions);
}
/* The retransmission time must be proportional to the channel
check interval of the underlying radio duty cycling layer. */
time = default_timebase();
/* The retransmission time uses a truncated exponential backoff
* so that the interval between the transmissions increase with
* each retransmit. */
backoff_exponent = num_tx;
/* Truncate the exponent if needed. */
if(backoff_exponent > CSMA_MAX_BACKOFF_EXPONENT) {
backoff_exponent = CSMA_MAX_BACKOFF_EXPONENT;
}
/* Proceed to exponentiation. */
backoff_transmissions = 1 << backoff_exponent;
/* Pick a time for next transmission, within the interval:
* [time, time + 2^backoff_exponent * time[ */
time = time + (random_rand() % (backoff_transmissions * time));
if(n->transmissions < metadata->max_transmissions) {
PRINTF("csma: retransmitting with time %lu %p\n", time, q);
ctimer_set(&n->transmit_timer, time,
transmit_packet_list, n);
/* This is needed to correctly attribute energy that we spent
transmitting this packet. */
queuebuf_update_attr_from_packetbuf(q->buf);
} else {
PRINTF("csma: drop with status %d after %d transmissions, %d collisions\n",
status, n->transmissions, n->collisions);
free_packet(n, q, status);
mac_call_sent_callback(sent, cptr, status, num_tx);
}
} else {
if(status == MAC_TX_OK) {
PRINTF("csma: rexmit ok %d\n", n->transmissions);
} else {
PRINTF("csma: rexmit failed %d: %d\n", n->transmissions, status);
}
free_packet(n, q, status);
mac_call_sent_callback(sent, cptr, status, num_tx);
}
} else {
PRINTF("csma: no metadata\n");
}
} else {
PRINTF("csma: seqno %d not found\n", packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO));
} }
} }
/*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/