What Handover cases are supported ?

The following Handover cases are supported:

• inter-eNB / inter-gNB handover

Case 1: External Core Network

Supported, please refer to How To Connect Your ORS To Third Party's Core Network On Panel

Case 2: Core Network On ORS also running eNB / gNB

In this case, you need to use IPv6 addresses because this will require the ORS running both core network and eNB / gNB to have two addresses, which we do not support with IPv4.

If all ORS are on the same LAN then all the ORS will be able to access each other directly using their IPv6 through re6st. If they are on different LAN they you need IPv6 connectivity.

Case 1: Handover with one central Core Network

This tutorial focuses on ORS, therefore it will only cover inter-eNB / inter-gNB handover, intra-eNB / intra-gNB handover will not be covered in this tutorial as ORS only has one cell, but it is also supported by Amarisoft (please refer to https://tech-academy.amarisoft.com/appnote_handover.doc )

Core Network may be Amarisoft or from another vendor, please refer to How To Connect Your ORS To Third Party's Core Network On Panel

Case 2: Handover between multiple Amarisoft Core Network

This is an experimental feature which is not yet supported but will be added in the future

Which GTP / MME / AMF Address to choose

Note: Core Network can have multiple GTP Address

Case 1: Core Network and eNB / gNB from Rapid.Space panel (Simpleran Software Release) on the same ORS

You can simply leave the default values by leaving "GTP Address" and "MME Address" / "AMF Address" empty on eNB or gNB, and making sure the Core Network has "Localhost address" in the "GTP Address List" field. Doing this will use a localhost address on the ORS.

Case 2: Core Network and eNB / gNB from panel on different ORS

In that case you have three options:

• LAN IPv4: This requires all ORS to be on the same LAN.
  • In this case make sure you have "IPv4 LAN Address" in GTP Address of eNB / gNB and Core Network, and copy the IPv4 Core Network Address in MME / AMF address on the eNB / gNB
• Re6st IPv6: This will work across different LAN's , it uses the Re6st public IPv6 which is available on all ORS / BBU's
  • In this case make sure you have "IPv6 Re6st Address" in GTP Address of eNB / gNB and Core Network, and copy the IPv6 Core Network Address in MME / AMF address on the eNB / gNB
• Manual address: use this if you are using VLAN's or your own IPv6

Case 3: eNB / gNB from panel and external Core Network

This is the same as Case 2, except if you use Re6st IPv6 you will need IPv6 connectivity on the external Core Network.

Step 1 - Configure your core network

Configure your core network to listen on the IP so that your ORS will be able to connect to it.

If you are using an Amarisoft core network managed by the panel, go to your core network service and configure the following parameters:

• GTP Address List:
  • Should contain at least IPv4 LAN address or IPv6 Re6st address, depending on if you plan to use the IPv4 LAN or the Public Re6st IPv6 Address.
  • It may also contain Localhost address if you are connecting a eNB / gNB running on the same machine
• iperf3 UDP server: true (recommended)

Then, you can get the core network address in the connection parameters, look for "core-network-ipv4" and "core-network-ipv6".

Step 2 - Connect all ORS to the same core network

Please follow https://handbook.rapid.space/ors/rapidspace-HowTo.Connect.Your.ORS.To.Third.Partys.Core.Network.On.Panel in order to connect each of your ORS to the same core network.

Make sure to correctly set the "GTP Address" parameter depending on your case. Remember that if you are running a core network and eNB / gNB on the same ORS you will need to use IPv6.

Once you have configured the ORS to connect to the external core network, you may check that it connected correctly by checking the eNB or gNB log and making sure you see a "NG Setup Response" or "S1 Setup Response".

Please follow How To Monitor And Access Logs On ORS to see how to check the logs.

Step 3 - Configure each ORS individually with GPS

The first step is to configure each ORS individually and to make sure you have the best radio conditions on each of them.

Power on each ORS one at a time and adjust the configuration to make sure your UE does not get disconnected when walking around the antenna, and that the radio quality is good enough.
Your ORS needs to be synchronized with GPS for the Handover to work properly, so make sure you enable the "GPS Sync" option on your eNB / gNB service while testing the ORS individually.
You should refer to these tutorials to adjust the radio settings and test the radio quality:

• How To Adjust TX And RX Gain On ORS
• How To Test 4G 5G Signal With Android
• What Is The Radio Range Of ORS

Step 4 - Configure the cell identities

The following values must be configured to be different on each ORS:

• Physical Cell ID
• eNB ID / gNB ID
• Root Sequence Index
• Cell ID:  If you are using the same band then the Cell ID modulo 3 should be different on the neighbour cells (Example: 100, 101, and 102 is OK, but 100, 103 and 104 is not for 3 neighbour cells)

Please refer to the screenshot above to see where to configure these values.

We recommend that you do a drawing of all your cells to plan the cell identities correctly.

Step 5 - Test each cell individually

It is strongly recommended to test each cell individually (with GPS) before attempting handover to ensure there are no obvious configuration issues or interferences.

For each cell, turn off all other cells and follow these tutorials to test the radio quality:

• How To Troubleshoot UE Radio Quality
• How to test 4G / 5G signal with Android

Step 6 - Configure the neighbour cells

For each neighbour ORS or ORS, you need to click "Object Properties" on the "Neighbour Cell Info" parameter, enter whatever name you want to identify your cell and click Add.

Then, you need to fill in all the values.

4G Cell:

• DL EARFCN: The one you configure on the neighbour cell
• Physical Cell ID: The one you configure on the neighbour cell
• E-EUTRAN Cell ID: Concatenation of the eNB ID and cell ID of the neighbour cell. For instance if the eNB ID is 0x12345 and Cell ID is 0x01 then the E-EUTRAN Cell ID will be 0x1234501
• Tracking Area Code: The one you configure on the neighbour cell, by default 1

5G Cell:

• DL NR ARFCN: The one you configure on the neighbour cell
• SSB NR ARFCN: You can get this value by checking the eNB log of your neighbour cell and searching at the beginning of the log for "ssb_nr_arfcn"
• Physical Cell ID: The one you configure on the neighbour cell
• NR Cell ID: Concatenation of the gNB ID and cell ID of the neighbour cell. For instance if the gNB ID is 0x12345 and Cell ID is 0x01 then the NR Cell ID will be 0x1234501
• gNB ID bits: The one you configure on the neighbour cell, by default 28
• NR Band: The one you configure on the neighbour cell
• Tracking Area Code: The one you configure on the neighbour cell, by default 1

Step 7 - Handover test

Please make sure you have a way to show serving and available cells on your UE, please refer to: How To Test 4G 5G Signal With Android

Power on your UE and start a continuous data stream between the UE and the core network during the whole test, we recommend doing either a ping test, an iperf3 test or a local video call (refer to the Android tutorial and / or How To Do Local Messaging And Video Calls With ORS )
If you do not have a continuous data stream between UE and core network then  your UE will go in idle mode and this will make debugging harder.

First stay near the first cell and check that your UE is connected to the nearest cell (using for example the special dial menu on Android or Network Cell Info app, you can see the PCI of the cell you are connected to on these apps).
Then, move from one cell to another and check that you do not experience too much disruption in your data stream, and check that your serving cell switches to the nearest cell.

Then, search for "Handover" in the gNB logs of your two cells, you should see the following messages:

• Handover request
• Handover request acknowledge

Please refer to this Amarisoft app note for a more detailed analysis of the logs: https://tech-academy.amarisoft.com/appnote_handover.doc