Poor Throughput and UE not staying attached

[damide]

I currently have the following setup:

UE: Quectel RM520N-GL module connected to one machine

gNB: srsRAN running on a separate machine with the LibreSDR B210mini RevC

5G Core: Open5GS deployed on a third machine

When I run iperf tests with a 10 MHz channel bandwidth, I am not achieving the expected throughput.

Uplink throughput ranges between 9 Mbps to 11 Mbps

Downlink throughput ranges between 8 Mbps to 13 Mbps

These values seem lower than what should be theoretically achievable under optimal conditions.

Could you please help identify what I might be doing wrong?
Below is the current gnb-config I’m using:

amf:
no_core: false
addr: 192.168..*
bind_addr: 192.168..*

ru_sdr:
device_driver: uhd
device_args: type=b200,num_recv_frames=64,num_send_frames=64
srate: 30.72 #61.44 #23.04 #30.72

lo_offset: 750000

otw_format: sc12
tx_gain: 70
rx_gain: 20

cell_cfg:
dl_arfcn: 628666
band: 78
channel_bandwidth_MHz: 10
common_scs: 30
plmn: "00101"
tac: 7
pci: 1
nof_antennas_dl: 1
nof_antennas_ul: 1

pdsch:
min_ue_mcs: 0
max_ue_mcs: 28
mcs_table: qam64

pusch:
min_ue_mcs: 0
max_ue_mcs: 28
mcs_table: qam256

tdd_ul_dl_cfg:
dl_ul_tx_period: 10
nof_dl_slots: 3
nof_dl_symbols: 0
nof_ul_slots: 6
nof_ul_symbols: 8
pattern2:
dl_ul_tx_period: 10
nof_dl_slots: 3
nof_dl_symbols: 0
nof_ul_slots: 6
nof_ul_symbols: 8

csi:
csi_rs_enabled: true
csi_rs_period: 20
log:
filename: /tmp/gnb.log
all_level: warning

pcap:
mac_enable: false
mac_filename: /tmp/gnb_mac.pcap
ngap_enable: true
ngap_filename: /tmp/gnb_ngap.pcap

[brendan-mcauliffe]

Hi @damide,

Can you provide a copy of your console outputs? It is impossible to diagnose any potential RF-related issues without seeing the channel metrics.

It is worth mentioning that "ideal" rates are unlikely to be achieved in a real-world setup; there are many factors that can impact UE performance. For example, you may have an ideal channel, but if your compute platform is not configured correctly or "slow", then you will not see good rates, there could be interference in your RF channel from other networks, and antenna placement will also impact performance. These are just a few possible examples.

I suggest that you adjust your gain values; this may lead to better results. Try increasing the RX gain in steps of 5 until you find a value that gives you a better connection.