User guide

Chapter 12: logging 40
12.2.2 t cpu command
t cpu command provides key informations about the CPU load.
-Proc- ---RX-------- ---TX-------- ---- TX/RX diff (ms)
CPU MS/s CPU MS/s CPU min/avg/max sigma
51.8% 23.040 6.6% 23.040 1.6% 2.23/2.8/3.3 0.2
52.9% 23.040 6.6% 23.039 1.6% 1.97/2.8/3.3 0.2
52.3% 23.040 6.6% 23.041 1.5% 2.20/2.8/3.3 0.2
51.4% 23.040 6.6% 23.040 1.6% 2.20/2.8/3.3 0.2
50.8% 23.040 6.6% 23.039 1.6% 2.19/2.8/3.3 0.2
t cpu shows CPU consumption for the main LTE task (Proc), the reception chain (RX) or
transmission chain (TX). Units are MS/s (Million of sample per second)
On top of that, t cpu command provides informations on TX-RX delay: The min, average
and max values are given in miliseconds. To make it simple, in LTE FDD mode as instance, UE
is granted in Uplink 4 TTI (4 ms) before data have to be sent. UE has by consequence 4ms to
generate the UL samples. The RX/TX delay is the remaining time before data are processed
and time they must be sent in UL. If this value decreases to zero, this means that PC is too slow
and physical layer is running out of CPU to process the data within this period. The higher is
the TX/RX value is , the better it is.
12.2.3 t command
t command (without argument) provides key informations about the Uplink and downlink trans-
fer
-------------- --Hz--ppm---dB----dBm---------------------DL--------- ---------UL-----
UE_ID CL RNTI CFO SRATE SINR RSRP mcs retx rxko rxok brate mcs ta retx tx brate
4G 1 00 003d -898 -3.5 32.1 -44.0 27.8 0 0 6192 209M 20.0 0 0 50 21.3k
4G 1 00 003d -900 -3.5 32.1 -44.0 27.8 0 0 6208 210M 20.0 0 0 50 21.0k
4G 1 00 003d -900 -3.5 32.1 -44.0 27.8 0 0 6192 209M 20.0 0 0 50 21.0k
4G 1 00 003d -901 -3.5 32.1 -44.0 27.7 14 4 6204 208M 21.0 0 0 64 292k
Where :
• UE ID is the UE ID
• CL is the Cell ID
• RNTI is the (c) RNTI of each UE
• CFO is the Carrier frequency offset in Hertz
• SRATE is the sample rate offset in ppm
• SINR (Signal-to-Interference Ratio) is an indicator of the signal quality while the rsrp is an
indicator of the signal strengh. SINR is the ratio of Signal Power and Noise Power. Unit is
in dB.
• RSRP (Reference signal received power), is the linear average over the power contribu-
tions of the resource elements that carry cell-specific reference signals within the considered
measurement frequency bandwidth. Unit is in dBm
• mcs (Modulation Coding Scheme) is the average MCS value used in downlink during the
measurement interval period. More details about MCS range are available in 3GPP TS
36.213
• retx (retransmission) is the number of retransmission sent by UE in Uplink or received by
eNodeB in downlink. This parameter gives indications about the channel quality.
• rxko is the number of received downlink transport blocks with CRC errors.
• rkok is the number of received downlink transport blocks without CRC error.
• brate is the average bitrate (at the MAC layer), in bits per second.