Issue with x2 Links for handover

[Erston Outway]

Hi everyone,

I've setup a 4G transmission system with several enbs and am now trying to implement the handover. Hence I've set up the x2 connections between the eNBs as shown in the Simu5G example and in the V2IV2Nsim example on github. But whenever I run the simulation it will sooner or later crash  without giving me a proper error prompt. Omnet will give the console output simulation terminated with exit code:139. I checked online and apparently this is connected to a memory access bug. However this occurs only once I include the X2 links. Does anyone have a clue what might cause this and how to fix this? Thank you in advance!

[Surya Pusapati]

Hello,

I think you have an error in your X2 configurations. Try the following steps to resolve.

In INI file: Revise your X2 connections by drawing your topology on paper and labelling the app index and links.

An example on four fully connected gNodeBs.

*.gNodeB*.numX2Apps = 3
*.gNodeB*.x2App[*].server*.localPort = 5000 + ancestorIndex(1)

*.gNodeB1.x2App[0].client.connectAddress = "gNodeB2%x2ppp0"
*.gNodeB1.x2App[1].client.connectAddress = "gNodeB3%x2ppp2"
*.gNodeB1.x2App[2].client.connectAddress = "gNodeB4%x2ppp1"

*.gNodeB2.x2App[0].client.connectAddress = "gNodeB1%x2ppp0"
*.gNodeB2.x2App[1].client.connectAddress = "gNodeB3%x2ppp1"
*.gNodeB2.x2App[2].client.connectAddress = "gNodeB4%x2ppp0"

*.gNodeB3.x2App[0].client.connectAddress = "gNodeB4%x2ppp2"
*.gNodeB3.x2App[1].client.connectAddress = "gNodeB2%x2ppp1"
*.gNodeB3.x2App[2].client.connectAddress = "gNodeB1%x2ppp1"

*.gNodeB4.x2App[0].client.connectAddress = "gNodeB2%x2ppp2"
*.gNodeB4.x2App[1].client.connectAddress = "gNodeB1%x2ppp2"
*.gNodeB4.x2App[2].client.connectAddress = "gNodeB3%x2ppp0"

In NED file: Check your X2 connections, for example.

connections:

          gNodeB1.x2++ <--> Eth10G <--> gNodeB2.x2++;

          gNodeB1.x2++ <--> Eth10G <--> gNodeB3.x2++;

          gNodeB1.x2++ <--> Eth10G <--> gNodeB4.x2++;

          gNodeB2.x2++ <--> Eth10G <--> gNodeB3.x2++;

          gNodeB2.x2++ <--> Eth10G <--> gNodeB4.x2++;
          gNodeB3.x2++ <--> Eth10G <--> gNodeB4.x2++;

I hope this tutorial helps,

Surya

[Erston Outway]

Thank you very much for your reply. I've looked at my files again and there were issues with the connect addresses assignments, so i attempted to fix it, however the simulation still ends up crashing, only giving me the exit code 139. The Terminal window for the connection to sumo gives me the following error: Error: tcpip::Socket::recvAndCheck @ recv: peer shutdown. Not sure whether this helps at all, I checked online but the info on this is kinda conflicting.

I feel like I've still not quite gotten how to set up the x2 links. Can you tell me what I did wrong?

I currently have 6 eNodeBs:

eNB23201, eNB24143, eNB24141, eNB23202, eNB22139 and eNB23654

From the NED file:

        eNB23201.x2++ <--> Eth10G <--> eNB24143.x2++;
        eNB23201.x2++ <--> Eth10G <--> eNB24141.x2++;
        eNB23201.x2++ <--> Eth10G <--> eNB23202.x2++;
        eNB23201.x2++ <--> Eth10G <--> eNB22139.x2++;
        eNB23201.x2++ <--> Eth10G <--> eNB23654.x2++;

        eNB24143.x2++ <--> Eth10G <--> eNB24141.x2++;
        eNB24143.x2++ <--> Eth10G <--> eNB23202.x2++;
        eNB24143.x2++ <--> Eth10G <--> eNB22139.x2++;
        eNB24143.x2++ <--> Eth10G <--> eNB23654.x2++;

        eNB24141.x2++ <--> Eth10G <--> eNB23202.x2++;
        eNB24141.x2++ <--> Eth10G <--> eNB22139.x2++;
        eNB24141.x2++ <--> Eth10G <--> eNB23654.x2++;

        eNB23202.x2++ <--> Eth10G <--> eNB22139.x2++;
        eNB23202.x2++ <--> Eth10G <--> eNB23654.x2++;

        eNB22139.x2++ <--> Eth10G <--> eNB23654.x2++;

From the ini file:

*.eNB*.numX2Apps = 5    # one x2App per peering eNB
*.eNB*.x2App[*].server.localPort = 5000 + ancestorIndex(1) # Server ports (x2App[0]=5000, x2App[1]=5001, ...)

#                eNB23201
*.eNB23201.x2App[0].client.connectAddress="eNB24143%x2ppp0"
*.eNB23201.x2App[1].client.connectAddress="eNB24141%x2ppp1"
*.eNB23201.x2App[2].client.connectAddress="eNB23202%x2ppp2"
*.eNB23201.x2App[3].client.connectAddress="eNB22139%x2ppp3"
*.eNB23201.x2App[4].client.connectAddress="eNB23654%x2ppp4"

#                eNB24143
*.eNB24143.x2App[0].client.connectAddress="eNB23201%x2ppp0"
*.eNB24143.x2App[1].client.connectAddress="eNB24141%x2ppp0"
*.eNB24143.x2App[2].client.connectAddress="eNB23202%x2ppp1"
*.eNB24143.x2App[3].client.connectAddress="eNB22139%x2ppp2"
*.eNB24143.x2App[4].client.connectAddress="eNB23654%x2ppp3"

##                eNB24141
*.eNB24141.x2App[0].client.connectAddress="eNB24143%x2ppp1"
*.eNB24141.x2App[1].client.connectAddress="eNB23201%x2ppp1"
*.eNB24141.x2App[2].client.connectAddress="eNB23202%x2ppp0"
*.eNB24141.x2App[3].client.connectAddress="eNB22139%x2ppp1"
*.eNB24141.x2App[4].client.connectAddress="eNB23654%x2ppp2"

##                eNB23202
*.eNB23202.x2App[0].client.connectAddress="eNB24141%x2ppp2"
*.eNB23202.x2App[1].client.connectAddress="eNB24143%x2ppp2"
*.eNB23202.x2App[2].client.connectAddress="eNB23201%x2ppp2"
*.eNB23202.x2App[3].client.connectAddress="eNB22139%x2ppp0"
*.eNB23202.x2App[4].client.connectAddress="eNB23654%x2ppp0"

##                eNB22139
*.eNB22139.x2App[0].client.connectAddress="eNB23202%x2ppp3"
*.eNB22139.x2App[1].client.connectAddress="eNB24141%x2ppp3"
*.eNB22139.x2App[2].client.connectAddress="eNB24143%x2ppp3"
*.eNB22139.x2App[3].client.connectAddress="eNB23201%x2ppp3"
*.eNB22139.x2App[4].client.connectAddress="eNB23654%x2ppp1"

##                eNB23654
*.eNB23654.x2App[0].client.connectAddress="eNB23202%x2ppp4"
*.eNB23654.x2App[1].client.connectAddress="eNB22139%x2ppp4"
*.eNB23654.x2App[2].client.connectAddress="eNB24141%x2ppp4"
*.eNB23654.x2App[3].client.connectAddress="eNB24143%x2ppp4"
*.eNB23654.x2App[4].client.connectAddress="eNB23201%x2ppp4"

[Surya Pusapati]

I used to have the same issue a long time ago. But I forgot how I resolved that time. I will let you know if I have any leads.

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