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