Guido Casati
7c788be9e0
* In LTE there is logic that checks the thread configurtion with the getters `get_thread_parallel_conf()` and `get_thread_worker_conf()` in NR these getters are not used, only setters, which have no impact
3.6 KiB
OpenAirInterface for SystemX
Terminology
This document use the 5G terminology
Central Unit (CU): It is a logical node that includes the gNB functions like Transfer of user data, Mobility control, Radio access network sharing, Positioning, Session Management etc., except those functions allocated exclusively to the DU. CU controls the operation of DUs over front-haul (Fs) interface. A central unit (CU) may also be known as BBU/REC/RCC/C-RAN/V-RAN/VNF
Distributed Unit (DU): This logical node includes a subset of the gNB functions, depending on the functional split option. Its operation is controlled by the CU. Distributed Unit (DU) also known with other names like RRH/RRU/RE/RU/PNF.
In OpenAir code, the terminology is often RU and BBU.
OpenAirUsage
EPC and general environment
OAI EPC
Use the stable OAI EPC, that can run in one machine (VM or standalone)
Draft description: https://open-cells.com/index.php/2017/08/22/all-in-one-openairinterface-august-22nd/
Standalone 4G
EPC+eNB on one machine, the UE can be commercial or OAI UE.
USRP B210
Main current issue: traffic is good only on coaxial link between UE and eNB (probably power management issue).
Simulated RF
Running eNB+UE both OAI can be done over a virtual RF link.
The UE current status is that threads synchronization is implicit in some cases. As the RF simulator is very quick, a “sleep()” is required in the UE main loop
(line 1744, targets/RT/USER/lte-ue.c).
Running also the UE in the same machine is possible with simulated RF.
Running in same machine is simpler, offers about infinite speed for virtual RF samples transmission.
A specific configuration is required because the EPC Sgi interface has the same IP tunnel end point as the UE.
So, we have to create a network namespace for the UE and to route data in/out of the namespace.
ip netns delete aNameSpace 2> /dev/null
ip link delete v-eth1 2> /dev/null
ip netns add aNameSpace
ip link add v-eth1 type veth peer name v-peer1
ip link set v-peer1 netns aNameSpace
ip addr add 10.200.1.1/24 dev v-eth1
ip link set v-eth1 up
iptables -t nat -A POSTROUTING -s 10.200.1.0/255.255.255.0 -o enp0s31f6 \
-j MASQUERADE
iptables -A FORWARD -i enp0s31f6 -o v-eth1 -j ACCEPT
iptables -A FORWARD -o enp0s31f6 -i v-eth1 -j ACCEPT
ip netns exec aNameSpace ip link set dev lo up
ip netns exec aNameSpace ip addr add 10.200.1.2/24 dev v-peer1
ip netns exec aNameSpace ip link set v-peer1 up
ip netns exec aNameSpace bash
After the last command, the Linux shell is in the new namespace, ready to run the UE.
To make user plan traffic, the traffic generator has to run in the same namespace
ip netns exec aNameSpace bash
The traffic genenrator has to specify the interface:
route add default oaitun_ue1
or specify the outgoing route in the traffic generator (like option “-I” in ping command).
5G and F1
Today 5G achievement is limited to physical layer.
The available modulation is 40MHz, that require one X310 or N300 for the gNB and a X310 or N300 for the nrUE.
Usage with X310
Linux configuration: https://files.ettus.com/manual/page_usrp_x3x0_config.html
We included most of this configuration included in OAI source code.
Remain to set the NIC (network interface card) MTU to 9000 (jumbo frames).
Running 5G
Usage with RFsimulator:
gNB
sudo ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-LTE-EPC/CONF/gnb.band78.tm1.106PRB.usrpn300.conf
nrUE
sudo ./nr-uesoftmodem --numerology 1 -r 106 -C 3510000000 -d --rfsimulator.serveraddr 127.0.0.1