Working with relaying based on the module of psc but unfortunately packets are not delivered via the relay node

aadesh shah

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Jun 11, 2020, 3:56:19 AM6/11/20

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Hello All,

I am trying to use the psc based UE relay to network module. I have tried to scale up the "lte-sl-in-covrg-relay-building.cc" file for a factory environment with 80 relay nodes and 20 mobile nodes with mobility as per by factory definition. Now from the trace files I can see the remote nodes are connecting to relay nodes but out of 42613 packets only 22345 are received and rest are lost. Now if I turn of the relay service then 41768 are delivered and if I schedule the relay service a bit later in time even than more packets are delivered. Can someone help me locate the error in my code (I have attached to this post). I even tried a IPv6 trace and there I got an error of "IP" not a match for multiple addresses. I am doing something wrong with the configuration of the relay node but cant locate the problem.

It would be great if you could help me. Stuck with this problem for a while.

Thank you so much.

Regards,

Aadesh Shah

factory_relaying.cc

aadesh shah

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Jun 12, 2020, 10:37:00 AM6/12/20

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Any help??

aadesh shah

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Jun 12, 2020, 11:01:28 AM6/12/20

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I found one mistake in my code where the start of relay service and the start of applications was a problem so I changed the timing as per the applications. But now I am able to get maximum 97% of the packets and 3% of the packets are still missing. Plus I have few more issues like:

- The remote node I connecting to only 1 Relay node (thats with imsi 1), I have no idea why this is happening? Can someone tell me? Due to this when I try to scale up I still get can error of maxSl_dest reached which is 16 and I have 20 remote nodes.

- Is there a middle ground to switch on relay nodes? As I have 80 relay nodes and 20 remote nodes so if I keep the start of relay service as mentioned in the examples then the relay service would start for all the nodes atlest after 80s and if reduce the time for relay service then I lose packets. can someone provide the solution for this?

- I even observed a strange behavior, if I reduce the tx power of the enb to say (1dbm) I am doing this as all my nodes are close to the enb and I dont have a blocking model. In this case the enb cant choose relaying can someone explain what is the relation between relaying and the power consumption of enb?

- When I try to use Mode 1 for relaying I guess there is selection of relay nodes as the pdcp trace shows no change of IMSI. does the module support this?

- From the test of ue network relay file one can see the remote node can choose 2 relay nodes but can I tried to do that in a scale example I was not able to do it? Is it possible for the remote node to choose multiple relay nodes?

- I was able to calculate the reliability and latency of relaying with flowmointor, if the normal LTE the latency values are 19s but with relay the latency is around 40s can you tell me the reason overhead? And if there is a way I can trace the delay for the packet for each hops?

It would be great if some can reply to all or even some of the questions I have asked.

Thank You and Regards,

Aadesh Shah

aadesh shah

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Jun 13, 2020, 2:35:52 PM6/13/20

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This is really urgent anyone can help?

Hemant Saini

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Jun 15, 2020, 6:19:57 AM6/15/20

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@aadesh shah hi

where u changed in factory_relayinng for timing as u mentioned

pl. share the modified factory_relay

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aadesh shah

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Jun 15, 2020, 8:28:37 AM6/15/20

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I have modified the code further and now the node runs for a scale up model with 80 static nodes and 20 relay nodes. But the reliability has reduced to 78%. And solved the issue of reduced power and relaying.

Now the problems I face are:

- Reliability is reduced. How can I see where and why the packets are being dropped?

- From the test of ue network relay file one can see the remote node can choose 2 relay nodes but can I tried to do that in a scale example I was not able to do it? I was able to scale up but the 2 address the eNB connects to are the remote node itself and one more relay node. But the test file says the addresses would be of two different relay nodes. Can you tell me whats wrong here?

- The latency is very high with relaying. This is due to hoping but can you tell me how this can be reduced? As the delay is around 42 ms which is very high. Can you tell me how I can calculate the hope latency?