Include ARQ scheme #10

src/mac/mac_bs.c

@@ -20,17 +20,19 @@
 
 #include "mac_bs.h"
 #include "../util/log.h"
+#include <net/ethernet.h>
+#include <netinet/ip.h>
 #include <unistd.h>
 
 #ifdef MAC_TEST_DELAY
 #include "../runtime/test.h"
 #endif
 
-user_s *ue_create(uint userid) {
+user_s *ue_create(uint userid, long long unsigned int *subframe_ptr) {
   // create user instance and association response
   user_s *new_ue = calloc(sizeof(user_s), 1);
   new_ue->msg_control_queue = ringbuf_create(MAC_CTRL_MSG_BUF_SIZE);
-  new_ue->fragmenter = mac_frag_init();
+  new_ue->fragmenter = mac_frag_init(subframe_ptr);
   new_ue->reassembler = mac_assmbl_init();
   new_ue->userid = userid;
   new_ue->ul_queue = 0;
@@ -63,7 +65,7 @@ MacBS mac_bs_init() {
     macinst->UE[i] = NULL;
   }
   macinst->broadcast_ctrl_queue = ringbuf_create(MAC_CTRL_MSG_BUF_SIZE);
-  macinst->broadcast_data_fragmenter = mac_frag_init();
+  macinst->broadcast_data_fragmenter = mac_frag_init(&macinst->subframe_cnt);
 
 #ifdef MAC_ENABLE_TAP_DEV
   macinst->tapdevice = tap_init("tap0");
@@ -137,7 +139,7 @@ void mac_bs_add_new_ue(MacBS mac, uint8_t rachuserid, uint8_t rach_try_cnt,
       ringbuf_put(mac->broadcast_ctrl_queue, response);
     } else {
       // create new UE struct
-      mac->UE[userid] = ue_create(userid);
+      mac->UE[userid] = ue_create(userid, &mac->subframe_cnt);
       mac->UE[userid]->fs = fs;
       mac->UE[userid]->last_seen = mac->subframe_cnt;
       mac->UE[userid]->timingadvance = timing_diff;
@@ -199,6 +201,8 @@ int mac_bs_add_txdata(MacBS mac, uint8_t destUserID, MacDataFrame frame) {
   MacFrag fragmenter = NULL;
   if (destUserID == USER_BROADCAST) {
     fragmenter = mac->broadcast_data_fragmenter;
+    // force frames that are forwarded using broadcast frag to disable ARQ
+    frame->do_arq = 0;
   } else if (mac->UE[destUserID] != NULL) {
     fragmenter = mac->UE[destUserID]->fragmenter;
   } else {
@@ -284,7 +288,15 @@ int mac_bs_handle_message(MacBS mac, MacMessage msg, uint8_t userID) {
         INFO, "[MAC BS] mcs_change_request from user %d mcs: %d is_ul %d\n",
         userID, msg->hdr.MCSChangeReq.mcs, msg->hdr.MCSChangeReq.ul_flag)
     break;
+  case dl_data_ack:
+    mac_frag_ack_fragment(user->fragmenter, msg);
+    break;
   case ul_data:
+    if (msg->hdr.ULdata.do_ack) {
+      MacMessage ack = mac_msg_create_ul_data_ack(ACK, msg->hdr.ULdata.seqNr,
+                                                  msg->hdr.ULdata.fragNr);
+      ringbuf_put(user->msg_control_queue, ack);
+    }
     frame = mac_assmbl_reassemble(user->reassembler, msg);
     if (frame != NULL) {
       user->stats.bytes_rx += frame->size;
@@ -384,6 +396,11 @@ void mac_bs_map_slot(MacBS mac, uint subframe, uint slot, user_s *ue) {
     MacMessage msg = mac_frag_get_fragment(ue->fragmenter, payload_size, 0);
     lchan_add_message(chan, msg);
     ue->stats.bytes_tx += msg->payload_len;
+    if (msg->hdr.DLdata.do_ack) {
+      // if the user is expected to send an ack for this frame, indicade a
+      // pending transmission to the scheduler
+      ue->ul_queue++;
+    }
     mac_msg_destroy(msg);
   }
   lchan_calc_crc(chan);
@@ -692,6 +709,19 @@ void *mac_bs_tap_rx_th(void *arg) {
       MacDataFrame frame = dataframe_create(dev->bytes_rec);
       memcpy(frame->data, dev->buffer, dev->bytes_rec);
 
+      // Packet inspection: determine if this is TCP traffic
+      // then activate ARQ
+      uint16_t ether_type = (frame->data[12] << 8) + frame->data[13];
+      struct iphdr *ip4hdr = (struct iphdr *)&frame->data[14];
+      frame->do_arq = 0; // no ARQ by default
+      LOG(DEBUG, "[TAP] Packet inspect: ethertype %04x, proto %d\n", ether_type,
+          ip4hdr->protocol);
+      if (ether_type == ETHERTYPE_IP) {
+        // is IPv4 packet, check if TCP
+        if (ip4hdr->protocol == 6) {
+          frame->do_arq = 1;
+        }
+      }
       // find correct userid to forward EtherFrame to
       // if no entry is found, broadcast channel is used
       struct entry *np = NULL;

src/mac/mac_common.c

@@ -32,6 +32,7 @@ MacDataFrame dataframe_create(uint size) {
   MacDataFrame frame = malloc(sizeof(MacDataFrame_s));
   frame->data = malloc(size);
   frame->size = size;
+  frame->do_arq = 0; // do not use ARQ mode by default
   return frame;
 }
 

src/mac/mac_common.h

@@ -43,6 +43,7 @@
 typedef struct {
   uint size;
   uint8_t *data;
+  uint do_arq;
 } MacDataFrame_s;
 
 // Store some MAC layer statistics