SE4: Multi-Node IoT

1) Experiment Overview

Experiment Definition: The minimal representative working environment for this experiment is with LW1 as the AFRN and any APRN. At the end of the experiment, the user can view logs and test results.

Experiment Goals: The main goal of this experiment is to provide basic IoT signalling between the eNB and UE nodes. The different modes offered in this experiment are EMULATION, TESTBED and applicable tests for these modes are PING, IPERF 

Mode Descriptions:

TESTBED 

Base Station to Single UE Link (# of UEs + 1 PCs)

Description: This mode sets up an eNB on one machine and a UE on one or more machines. The transmission is unidirectional. If the default configuration settings are used, the radios will operate within the 915 MHz spectrum.

Software version

• Ubuntu version 18.04

• srsLTE version 22.10

• uhd 4.3

Most Common Configuration Parameters:

• Center Frequency: this sets the center frequency of the transmission. As this is a unidirectional transmission, there is no uplink channel.

• USRP Tx Gain (sets the gain of variable PA in the USRP in the range of 0 to 89 for B series, 0 to 30 for X310; only available on eNB): default is 0 dBFS which has been determined for the external Tx RF front end.

• USRP Rx Gain (sets the gain of variable PA in the USRP in the range of 0 to 76 for B series, 0 to 30 for X310; only available on UE): default is 0 dBFS which has been determined for the external Rx RF front end and Tx/Rx isolation.

• Skip SIB2 decoding: SIB2 decoding is not yet availabe on the UE. By enabling this option, the process will be skipped, enabling throughput measurements to automatically be measured.

2) Performing the Experiment:

2.A) Choosing the Experiment Mode

LTE Base Station (eNodeB or eNB) configuration

We assume the transmitter is a fixed node. Login to the E-VM corresponding to the fixed node. Navigate to the folder containing all the Radio scripts 

$ cd /root/Profiles/ProfileScripts/Radio

Copy the srsRAN IoT script as startRadio.sh

$ cp Samples/startSRSRAN-IoT-ENB.sh startRadio.sh 

Use an editor to uncomment the line  /Radio/startRadio.sh in /root/startexperiment.sh and run the following command:

$ /root/startExperiment.sh

User equipment (UE) configuration

We assume the transmitter is a portable node. Login to the E-VM corresponding to the portable node. Navigate to the folder containing all the Radio scripts 

$ cd /root/Profiles/ProfileScripts/Radio

Copy the srsRAN IoT script as startRadio.sh

$ cp Samples/startSRSRAN-IoT-UE.sh startRadio.sh 

Use an editor to uncomment the line  /Radio/startRadio.sh in /root/startexperiment.sh and run the following command:

$ /root/startExperiment.sh

3) Modifying the Experiment Configuration Parameters:

Core Network & Base Station: 

The shell script /root/Profiles/ProfileScripts/Samples/startSRSRAN-IoT-ENB.sh calls the script /root/Profiles/ProfileScripts/Radio/Helpers/startIoTENB.sh which can be edited by the experimenter to modify the parameters of the base station.

UE: 

The shell script /root/Profiles/ProfileScripts/Samples/startSRSRAN-IoT-UE.sh calls the script /root/Profiles/ProfileScripts/Radio/Helpers/startIoTUE.sh which can be edited by the experimenter to modify the parameters of the UE.

Multiple UEs:

Several users are to receive the transmission from the eNB.

4) Results:

Trace Results:

The outputted trace data for the nodes will be printed to the /root/Results folder. An example output is shown below.

The trace shows typical radio parameters, specific to the protocol. In this case, the protocol is LTE, and the following uplink and downlink specific parameters are provided by srsran:

• Carrier frequency offset (CFO)

• Reference signal received power (RSRP) is the received signal power.

• Signal to noise ratio (SNR) 

• Reference signal received quality (RSRQ)

• BLER (%) is the percentage of dropped blocks. It should be below 10% for the system to function according to the specifications.

• Bitrate

[2022-05-27 11:37:45.051504] Opening RF device...

[2022-05-27 11:37:45.051544] Available RF device list: UHD  zmq 

[2022-05-27 11:37:45.051555] Trying to open RF device 'UHD'

[2022-05-27 11:37:45.545284] Opening USRP channels=1, args: type=b200,master_clock_rate=23.04e6

[2022-05-27 11:37:46.591959] RF device 'UHD' successfully opened

[2022-05-27 11:37:46.592137] Set RX gain: 40.0 dB

[2022-05-27 11:37:46.753314] Set RX freq: 915.000000 MHz

[2022-05-27 11:37:46.753520] Setting sampling rate 1.92 MHz

[2022-05-27 11:37:46.753578] Actual sampling rate 1.92 MHz

[2022-05-27 11:37:47.118076] NSSS with peak=2.384766, cell-id: 0, partial SFN: 0

[2022-05-27 11:37:47.118121] *Found n_id_ncell:   0 DetectRatio= 0% PSR=7.94, Power=37.9 dBm

[2022-05-27 11:37:48.420908] Finding PSS... Peak:      1.1, FrameCnt: 0, State: 0

Finding PSS... Peak:      1.1, FrameCnt: 0, State: 0

Finding PSS... Peak:      1.3, FrameCnt: 0, State: 0

Finding PSS... Peak:      1.3, FrameCnt: 0, State: 0

Finding PSS... Peak:      1.0, FrameCnt: 0, State: 0

Finding PSS... Peak:      1.1, FrameCnt: 0, State: 0

Finding PSS... Peak:      1.2, FrameCnt: 0, State: 0

Finding PSS... Peak:      6.2, FrameCnt: 0, State: 1

MIB received (CFO:  +4.46 kHz)

[2022-05-27 11:37:50.485795] SIB1 received

[2022-05-27 11:37:55.459864] CFO:  +4.62 kHz, RSRP: -14.8 dBm SNR: 15.0 dB, RSRQ: -5.6 dB, NPDCCH detected: 0, NPDSCH-BLER:  0.00% (0 of total 1), NPDSCH-Rate:  0.04 kbit/s

CFO:  +4.62 kHz, RSRP: -12.7 dBm SNR: 14.5 dB, RSRQ: -4.3 dB, NPDCCH detected: 0, NPDSCH-BLER:  0.00% (0 of total 1), NPDSCH-Rate:  0.04 kbit/s

CFO:  +4.62 kHz, RSRP: -11.8 dBm SNR: 14.1 dB, RSRQ: -3.9 dB, NPDCCH detected: 0, NPDSCH-BLER:  0.00% (0 of total 1), NPDSCH-Rate:  0.04 kbit/s