STATUS 2020/09/04 : document will be soon reworked to match the progresses made on functionality
## Table of Contents ##
1. [Configuration Overview](#configuration-overview)
2. [SW Repository / Branch](#repository)
3. [Architecture Setup](#architecture-setup)
4. [Build / Install](#build-and-install)
5. [Run / Test](#run-and-test)
6. [Test case](#test-case)
7. [Log file monitoring](#log-file-monitoring)
6. [Required tools for debug](#required-tools-for-debug)
7. [Status of interoperability](#status-of-interoperability)
## Configuration Overview
* Non Standalone (NSA) configuration : initial Control Plane established between UE and RAN eNB, then User Plane established between UE and gNB, Core network is 4G based supporting rel 15
* Commercial UE: Oppo Reno 5G
* OAI Software Defined gNB and eNB
* eNB RF front end: USRP (ETTUS) B200 Mini or B210
* gNB RF front end: USRP (ETTUS) B200 Mini or B210 (N310 will be needed for MIMO and wider BW's)
* 5G TDD duplexing mode
* 5G FR1 Band n78 (3.5 GHz)
* BW: 40MHz
* Antenna scheme: SISO
## Repository
https://gitlab.eurecom.fr/oai/openairinterface5g/tree/develop
## Architecture Setup
The scheme below depicts our typical setup:
The photo depicts the FR1 setup part of the scheme above:
## Build and Install
General guidelines to build eNB and gNB :
See https://gitlab.eurecom.fr/oai/openairinterface5g/blob/develop/doc/BUILD.md#building-ues-enodeb-and-gnodeb-executables
- **eNB**
```
cd <your oai installation directory>/openairinterface5g/
source oaienv
cd cmake_targets/
./build_oai -I -w USRP --eNB
```
- **gNB**
```
cd <your oai installation directory>/openairinterface5g/
source oaienv
cd cmake_targets/
./build_oai -I -w USRP --gNB
```
- **EPC**
for reference:
https://github.com/OPENAIRINTERFACE/openair-epc-fed/blob/master-documentation/docs/DEPLOY_HOME.md
## Configuration Files
Each component (EPC, eNB, gNB) has its own configuration file.
These config files are passed as arguments of the run command line, using the option -O \<conf file\>
The **REFERENCE** files for eNB and gNB, **used by the CI**, can be found here:
[enb conf file](../ci-scripts/conf_files/enb.band7.tm1.fr1.25PRB.usrpb210.conf)
[gnb conf file](../ci-scripts/conf_files/gnb.band78.tm1.fr1.106PRB.usrpb210.conf)
These files have to be updated manually to set the IP addresses and frequency.
**ATTENTION** : an **EXTERNAL** clock is used to sync the eNB and gNB,
whether the clock is internal or external is defined in the configuration files (!! details needed !!)
1- In the **eNB configuration file** :
- look for MME IP address, and update the **ipv4 field** with the IP address of the **EPC** server
```
////////// MME parameters:
mme_ip_address = ( { ipv4 = "**YOUR_EPC_IP_ADDR**";
ipv6 = "192:168:30::17";
active = "yes";
preference = "ipv4";
}
);
```
- look for S1 IP address, and update the **3 fields below** with the IP address of the **eNB** server
```
NETWORK_INTERFACES :
{
ENB_INTERFACE_NAME_FOR_S1_MME = "eth0";
ENB_IPV4_ADDRESS_FOR_S1_MME = "**YOUR_ENB_IP_ADDR**";
ENB_INTERFACE_NAME_FOR_S1U = "eth0";
ENB_IPV4_ADDRESS_FOR_S1U = "**YOUR_ENB_IP_ADDR**";
ENB_PORT_FOR_S1U = 2152; # Spec 2152
ENB_IPV4_ADDRESS_FOR_X2C = "**YOUR_ENB_IP_ADDR**";
ENB_PORT_FOR_X2C = 36422; # Spec 36422
};
```
2- In the **gNB configuration file** :
- look for MME IP address, and update the **ipv4 field** with the IP address of the **EPC** server
```
////////// MME parameters:
mme_ip_address = ( { ipv4 = "**YOUR_EPC_IP_ADDR**";
ipv6 = "192:168:30::17";
active = "yes";
preference = "ipv4";
}
);
```
- look for X2 IP address, and update the **4 fields** with the IP address of the **eNB** server / **gNB** server as below (notice : even if -in principle- S1 MME is not required for gNB setting)
```
///X2
enable_x2 = "yes";
t_reloc_prep = 1000; /* unit: millisecond */
tx2_reloc_overall = 2000; /* unit: millisecond */
target_enb_x2_ip_address = (
{ ipv4 = "**YOUR_ENB_IP_ADDR**";
ipv6 = "192:168:30::17";
preference = "ipv4";
}
);
NETWORK_INTERFACES :
{
GNB_INTERFACE_NAME_FOR_S1_MME = "eth0";
GNB_IPV4_ADDRESS_FOR_S1_MME = "**YOUR_GNB_IP_ADDR**";
GNB_INTERFACE_NAME_FOR_S1U = "eth0";
GNB_IPV4_ADDRESS_FOR_S1U = "**YOUR_GNB_IP_ADDR**";
GNB_PORT_FOR_S1U = 2152; # Spec 2152
GNB_IPV4_ADDRESS_FOR_X2C = "**YOUR_GNB_IP_ADDR**";
GNB_PORT_FOR_X2C = 36422; # Spec 36422
};
```
3- The frequency setting requires a manual update in the .C and in the gNB conf file:
In the C file **openair2/RRC/LTE/rrc_eNB.c:3217**
set the nrarfcn to the same value as absoluteFrequencySSB in the **gNB config file**, that is **641272** in the example below
C file :
```
MeasObj2->measObject.choice.measObjectNR_r15.carrierFreq_r15 =641272;
```
gNB config file :
```
# absoluteFrequencySSB is the central frequency of SSB
absoluteFrequencySSB = 641272;
dl_frequencyBand = 78;
# the carrier frequency is assumed to be in the middle of the carrier, i.e. dl_absoluteFrequencyPointA_kHz + dl_carrierBandwidth*12*SCS_kHz/2
dl_absoluteFrequencyPointA = 640000;
#scs-SpecificCarrierList
dl_offstToCarrier = 0;
# subcarrierSpacing
# 0=kHz15, 1=kHz30, 2=kHz60, 3=kHz120
dl_subcarrierSpacing = 1;
dl_carrierBandwidth = 106;
```
## Run and Test
The order to run the different components is important:
1- first, CN
2- then, eNB
3- then, gNB
4- finally, switch UE from airplane mode OFF to ON
It is recommended to redirect the run commands to the same log file (fur further analysis and debug), using ```| tee **YOUR_LOG_FILE**``` especially for eNB and gNB.
It is not very useful for the CN.
The test takes typically a few seconds, max 10-15 seconds. If it takes more than 30 seconds, there is a problem.
- **EPC** (on EPC host):
for reference:
https://github.com/OPENAIRINTERFACE/openair-epc-fed/blob/master-documentation/docs/DEPLOY_HOME.md
- **eNB** (on the eNB host):
Execute:
```
~/openairinterface5g/cmake_targets/ran_build/build$ sudo ./lte-softmodem -O **YOUR_ENB_CONF_FILE** | tee **YOUR_LOG_FILE**
```
- **gNB** (on the gNB host)
**ATTENTION** : for the gNB execution,
The **-E** option is required to enable the tri-quarter sampling rate when using a B2xx serie USRP
The **-E** option is **NOT supported** when using a a N300 USRP
Execute:
```
~/openairinterface5g/cmake_targets/ran_build/build$ sudo ./nr-softmodem -O **YOUR_GNB_CONF_FILE** -E | tee **YOUR_LOG_FILE**
```
## Test Case
The test case corresponds to the UE attachement, that is the UE connection and its initial access in 5G, as depicted below:
**Source** : https://www.sharetechnote.com/html/5G/5G_LTE_Interworking.html
The test reaches step **12. E-RAB modifcation confirmation** , eventhough not all the messages will appear in the log file.
## Log file monitoring
From the log file that is generated, we can monitor several important steps, to assess that the test was successful.
Log files examples can be found here:
[enb log file](https://gitlab.eurecom.fr/oai/openairinterface5g/-/blob/rh_doc_update_3/doc/testing_gnb_w_cots_ue_resources/oai_enb.log)
[gnb log file](https://gitlab.eurecom.fr/oai/openairinterface5g/-/blob/rh_doc_update_3/doc/testing_gnb_w_cots_ue_resources/oai_gnb.log)
- eNB receives UE capabilities information, including its NR capabilites, and triggers sGNB Addition Request message:
***eNBlog.1315 :***
```
[RRC] [FRAME 00000][eNB][MOD 00][RNTI 43eb] received ueCapabilityInformation on UL-DCCH 1 from UE
...
[RRC] [eNB 0] frame 0 subframe 0: UE rnti 43eb switching to NSA mode
...
<X2AP-PDU>
<initiatingMessage>
<procedureCode>27</procedureCode>
<criticality><reject/></criticality>
<value>
<SgNBAdditionRequest>
<protocolIEs>
<SgNBAdditionRequest-IEs>
<id>111</id>
<criticality><reject/></criticality>
<value>
<UE-X2AP-ID>0</UE-X2AP-ID>
</value>
</SgNBAdditionRequest-IEs>
```
- gNB receives sGNB Addition request, processes UE capabilities for the corresponding UE and triggers sGNB Addition Request ACK, carrying NR RRC Reconfiguration message:
***gNBlog.2291 :***
```
<X2AP-PDU>
<successfulOutcome>
<procedureCode>27</procedureCode>
<criticality><reject/></criticality>
<value>
<SgNBAdditionRequestAcknowledge>
<protocolIEs>
<SgNBAdditionRequestAcknowledge-IEs>
<id>111</id>
<criticality><reject/></criticality>
<value>
<UE-X2AP-ID>0</UE-X2AP-ID>
</value>
</SgNBAdditionRequestAcknowledge-IEs>
```
- Upon reception of the sGNB Addition Request ACK, the eNB sends a new RRCConnectionReconfiguration message containing the NR Reconfiguration.
The UE replies with a Reconfiguration Complete message:
***eNBlog.1686 :***
```
[RRC] [FRAME 00000][eNB][MOD 00][RNTI 43eb] UE State = RRC_RECONFIGURED (default DRB, xid 1)
```
- The Random Access procedure of the UE to the gNB takes place:
***gNBlog.2382 :***
```
[PHY] [gNB 0][RAPROC] Frame 751, slot 19 Initiating RA procedure with
preamble 63, energy 35.7 dB, delay 6
[0m [0m[MAC] [gNB 0][RAPROC] CC_id 0 Frame 751, Slot 19 Initiating RA
procedure for preamble index 63
[0m [0m[MAC] [gNB 0][RAPROC] CC_id 0 Frame 751 Activating Msg2
generation in frame 752, slot 7 using RA rnti 10b
[0m [0m[MAC] [gNB 0] [RAPROC] CC_id 0 Frame 752, slotP 7: Generating
RAR DCI, state 1
[0m [0m[MAC] [RAPROC] DCI type 1 payload: freq_alloc 120 (0,6,24),
time_alloc 3, vrb to prb 0, mcs 0 tb_scaling 0
[0m [0m[MAC] Frame 752: Subframe 7 : Adding common DL DCI for RA_RNTI 10b
[0m [0m[MAC] Frame 752, Subframe 7: Setting Msg3 reception for Frame
752 Subframe 17
[0m [0m[PHY] ULSCH received ok
```
- The eNB triggers the path switch procedure towards the MME, so that
the traffic can be routed now from the SGW towards the gNB on the S1-U
plane.
***eNBlog.1691 :***
```
<S1AP-PDU>
<initiatingMessage>
<procedureCode>50</procedureCode>
<criticality><reject/></criticality>
<value>
<E-RABModificationIndication>
<protocolIEs>
<E-RABModificationIndicationIEs>
<id>0</id>
<criticality><reject/></criticality>
<value>
<MME-UE-S1AP-ID>553648130</MME-UE-S1AP-ID>
</value>
</E-RABModificationIndicationIEs>
```
Eventually, step **12. E-RAB Modification Confirmation** is successfully reached
## Required tools for debug
- **Wireshark** to trace X2AP and S1AP protocols
- **Ttracer** for 5G messages
- **GDB debugger** to check function calls
## Status of interoperability
The following parts have been validated with FR1 COTS UE:
- Phone accepts the configurtion provided by OAI eNB:
this validates RRC and X2AP
- Successful Random Access Procedure:
PRACH is correctly decoded at gNB
Phone correctly receives and decodes msg2 (NR PDCCH Format 1_0 and NR PDSCH)
msg3 is transmitted to gNB according to the configuration sent in msg2, and received correctly at gNB
- Successful path switch of user plane traffic from 4G to 5G cell (E-RAB modification message):
this validates S1AP
- Downlink traffic:
PDCCH DCI format 1_1 and correponding PDSCH are decoded correctlyby the phone
ACK/NACK (PUCCH format 0) are successfully received at gNB
- On going:
validation of HARQ procedures
Integration with higher layers to replace dummy data with real traffic
- Known limitations as of May 2020:
only dummy DL traffic
no UL traffic
no end-to-end traffic possible