The MAC layer in veins
I am using omnet++-5.4.1, veins-4.7.1 and sumo-0.25.0 to simulate vehicle frame transmission.
About the behavior of the EDCA in the mac layer in WAVE, in my understanding the waiting time to send can be obtained by the following calculation.
waiting time = AIFS[AC] + backoff
AIFS[AC] = SIFS + AIFSN[AC] * slotlength
However, in the startContent function of Mac 1609_4.cc, it is written as follows
if (idleTime > possibleNextEvent) {
DBG_MAC << "Could have already send if we had it earlier" << std::endl;
//we could have already sent. round up to next boundary
simtime_t base = idleSince + DIFS;
possibleNextEvent = simTime() - simtime_t().setRaw((simTime() - base).raw() % SLOTLENGTH_11P.raw()) + SLOTLENGTH_11P;
}
Even during simulation, transmission is performed without waiting for the time calculated just after the transmission request has occurred.
As described above, it is considered that the operation of the original EDCA (CSMA / CA) has not been performed and the busyness of the channel is not sensed.
I do not understand enough about this Mac layer? Please let me know if I missed some information.
Thank you.
omnet++ veins
asked Nov 20 '18 at 6:44
7ufi7ufi
112
add a comment |
I am using omnet++-5.4.1, veins-4.7.1 and sumo-0.25.0 to simulate vehicle frame transmission.
About the behavior of the EDCA in the mac layer in WAVE, in my understanding the waiting time to send can be obtained by the following calculation.
waiting time = AIFS[AC] + backoff
AIFS[AC] = SIFS + AIFSN[AC] * slotlength
However, in the startContent function of Mac 1609_4.cc, it is written as follows
if (idleTime > possibleNextEvent) {
DBG_MAC << "Could have already send if we had it earlier" << std::endl;
//we could have already sent. round up to next boundary
simtime_t base = idleSince + DIFS;
possibleNextEvent = simTime() - simtime_t().setRaw((simTime() - base).raw() % SLOTLENGTH_11P.raw()) + SLOTLENGTH_11P;
}
Even during simulation, transmission is performed without waiting for the time calculated just after the transmission request has occurred.
As described above, it is considered that the operation of the original EDCA (CSMA / CA) has not been performed and the busyness of the channel is not sensed.
I do not understand enough about this Mac layer? Please let me know if I missed some information.
Thank you.
omnet++ veins
asked Nov 20 '18 at 6:44
7ufi7ufi
112
What exactly is your question? If the implementation in Veins is correct? If your understanding is correct?
– Christoph Sommer
Nov 20 '18 at 7:08
Sorry, I may have misunderstood. I was calling the sendDown function in TraCIDemo 11p.cc. In my opinion, after the sendDown function was called, it waited for AIFS and backoff time, then sent a frame. However, in Veins, after the sendDown function was called, AIFS and backoff time were taken into account by inverse computing whether the channel was free from that point.
– 7ufi
Nov 21 '18 at 5:15
add a comment |
I am using omnet++-5.4.1, veins-4.7.1 and sumo-0.25.0 to simulate vehicle frame transmission.
About the behavior of the EDCA in the mac layer in WAVE, in my understanding the waiting time to send can be obtained by the following calculation.
waiting time = AIFS[AC] + backoff
AIFS[AC] = SIFS + AIFSN[AC] * slotlength
However, in the startContent function of Mac 1609_4.cc, it is written as follows
if (idleTime > possibleNextEvent) {
DBG_MAC << "Could have already send if we had it earlier" << std::endl;
//we could have already sent. round up to next boundary
simtime_t base = idleSince + DIFS;
possibleNextEvent = simTime() - simtime_t().setRaw((simTime() - base).raw() % SLOTLENGTH_11P.raw()) + SLOTLENGTH_11P;
}
Even during simulation, transmission is performed without waiting for the time calculated just after the transmission request has occurred.
As described above, it is considered that the operation of the original EDCA (CSMA / CA) has not been performed and the busyness of the channel is not sensed.
I do not understand enough about this Mac layer? Please let me know if I missed some information.
Thank you.
omnet++ veins
asked Nov 20 '18 at 6:44
7ufi7ufi
112
I am using omnet++-5.4.1, veins-4.7.1 and sumo-0.25.0 to simulate vehicle frame transmission.
About the behavior of the EDCA in the mac layer in WAVE, in my understanding the waiting time to send can be obtained by the following calculation.
waiting time = AIFS[AC] + backoff
AIFS[AC] = SIFS + AIFSN[AC] * slotlength
However, in the startContent function of Mac 1609_4.cc, it is written as follows
if (idleTime > possibleNextEvent) {
DBG_MAC << "Could have already send if we had it earlier" << std::endl;
//we could have already sent. round up to next boundary
simtime_t base = idleSince + DIFS;
possibleNextEvent = simTime() - simtime_t().setRaw((simTime() - base).raw() % SLOTLENGTH_11P.raw()) + SLOTLENGTH_11P;
}
Even during simulation, transmission is performed without waiting for the time calculated just after the transmission request has occurred.
As described above, it is considered that the operation of the original EDCA (CSMA / CA) has not been performed and the busyness of the channel is not sensed.
I do not understand enough about this Mac layer? Please let me know if I missed some information.
Thank you.
omnet++ veins
omnet++ veins
asked Nov 20 '18 at 6:44
7ufi7ufi
112
asked Nov 20 '18 at 6:44
7ufi7ufi
112
asked Nov 20 '18 at 6:44
7ufi7ufi
112
asked Nov 20 '18 at 6:44
7ufi7ufi
112
asked Nov 20 '18 at 6:44
7ufi7ufi
112
112
What exactly is your question? If the implementation in Veins is correct? If your understanding is correct?
– Christoph Sommer
Nov 20 '18 at 7:08
Sorry, I may have misunderstood. I was calling the sendDown function in TraCIDemo 11p.cc. In my opinion, after the sendDown function was called, it waited for AIFS and backoff time, then sent a frame. However, in Veins, after the sendDown function was called, AIFS and backoff time were taken into account by inverse computing whether the channel was free from that point.
– 7ufi
Nov 21 '18 at 5:15
add a comment |
What exactly is your question? If the implementation in Veins is correct? If your understanding is correct?
– Christoph Sommer
Nov 20 '18 at 7:08
Sorry, I may have misunderstood. I was calling the sendDown function in TraCIDemo 11p.cc. In my opinion, after the sendDown function was called, it waited for AIFS and backoff time, then sent a frame. However, in Veins, after the sendDown function was called, AIFS and backoff time were taken into account by inverse computing whether the channel was free from that point.
– 7ufi
Nov 21 '18 at 5:15
What exactly is your question? If the implementation in Veins is correct? If your understanding is correct?
– Christoph Sommer
Nov 20 '18 at 7:08
What exactly is your question? If the implementation in Veins is correct? If your understanding is correct?
– Christoph Sommer
Nov 20 '18 at 7:08
Sorry, I may have misunderstood. I was calling the sendDown function in TraCIDemo 11p.cc. In my opinion, after the sendDown function was called, it waited for AIFS and backoff time, then sent a frame. However, in Veins, after the sendDown function was called, AIFS and backoff time were taken into account by inverse computing whether the channel was free from that point.
– 7ufi
Nov 21 '18 at 5:15
Sorry, I may have misunderstood. I was calling the sendDown function in TraCIDemo 11p.cc. In my opinion, after the sendDown function was called, it waited for AIFS and backoff time, then sent a frame. However, in Veins, after the sendDown function was called, AIFS and backoff time were taken into account by inverse computing whether the channel was free from that point.
– 7ufi
Nov 21 '18 at 5:15
add a comment |
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What exactly is your question? If the implementation in Veins is correct? If your understanding is correct?
– Christoph Sommer
Nov 20 '18 at 7:08
Sorry, I may have misunderstood. I was calling the sendDown function in TraCIDemo 11p.cc. In my opinion, after the sendDown function was called, it waited for AIFS and backoff time, then sent a frame. However, in Veins, after the sendDown function was called, AIFS and backoff time were taken into account by inverse computing whether the channel was free from that point.
– 7ufi
Nov 21 '18 at 5:15