13 KiB
STATUS 2020/06/26 : information is up to date, but under continuous improvement
Table of Contents
- Configuration Overview
- SW Repository / Branch
- Architecture Setup
- Build / Install
- Run / Test
- Test case
- Log file monitoring
- Required tools for debug
- 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>
Some config examples can be found in the following folder:
https://gitlab.eurecom.fr/oai/openairinterface5g/-/tree/develop/targets/PROJECTS/GENERIC-LTE-EPC/CONF
Also base config files can be found here:
enb conf file
gnb conf file
TO DO : attach base confif files
These files have to be updated manually to set the IP addresses and frequency.
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 (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_ENB_IP_ADDR**";
GNB_INTERFACE_NAME_FOR_S1U = "eth0";
GNB_IPV4_ADDRESS_FOR_S1U = "**YOUR_ENB_IP_ADDR**";
GNB_PORT_FOR_S1U = 2152; # Spec 2152
GNB_IPV4_ADDRESS_FOR_X2C = "**YOUR_ENB_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**
For example:
~/openairinterface5g/cmake_targets/ran_build/build$ sudo ./lte-softmodem -O ../../../targets/PROJECTS/GENERIC-LTE-EPC/CONF/enb.band7.tm1.50PRB.usrpb210.conf | tee mylogfile.log
- gNB (on the gNB host)
Execute:
~/openairinterface5g/cmake_targets/ran_build/build$ sudo ./nr-softmodem -O **YOUR_GNB_CONF_FILE** | tee **YOUR_LOG_FILE**
For example:
~/openairinterface5g/cmake_targets/ran_build/build$ sudo ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band78.tm1.106PRB.usrpn300.conf | tee mylogfile.log
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
gnb log file
- 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