Cisco Cisco 1800 2800 3800 Series 16-Port Async High-Speed WIC
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Antenna Guide for ISR and CGR with Verizon Wireless 4G LTE
Signal Strength and Quality:
The effect of LTE signal strength and quality on the ISR performance on Verizon Wireless LTE is considerable. A
weak or low quality LTE signal degrades throughput by more than 80%, and can reduce the efficiency of an LTE
sector (the 120 degree area around a cell tower) that affects the remote site (and likely other devices nearby).
2 questions: How to know if the LTE signal strength and quality are “good” and what can be done if it’s not “good”.
Is the LTE signal strength and quality “good”? Cisco ISRs and CGRs with embedded LTE interfaces provide
benefits for performance, security, routing and management, which are equivalent across these product lines. As part
of management functions, the router provides detailed radio statistics and logs. To check the LTE signal strength and
quality, a simple “show” command is used. Sample output is shown below, followed by the meaning of the important
values and current suggestions for what may be considered “good” values.
Values are “good”
Values show need for antenna placement/change
819r6DM#
sh
sh
sh
show
ow
ow
ow
cell 0 radio
cell 0 radio
cell 0 radio
cell 0 radio
819H#
sho
sho
sho
show
ww
w
cell 0 radio
cell 0 radio
cell 0 radio
cell 0 radio
Radio power mode = ON
Radio power mode = ON
Channel Number = 5230
Channel Number = 5230
Current Band = LTE
Current Band = LTE
Current RSSI =
-54 dBm
Current RSSI =
-65 dBm
Current RSRP =
-79 dBm
Current RSRP =
-100 dBm
Current RSRQ =
-9 dB
Current RSRQ =
-16 dB
Current SNR =
14.4 dB
Current SNR =
-4.1 dB
LTE Technology Preference = AUTO
LTE Technology Preference = AUTO
LTE Technology Selected = LTE
LTE Technology Selected = LTE
Different LTE devices types measure RF values differently. A smartphone app may yield different results than an ISR.
It is recommended to measure the signal using an actual ISR (all 4G ISRs/CGR use the same LTE modem and will
yield similar results). The values below are not absolute. Good performance may be obtained with results outside of
the “good” values and vice versa. A speed/performance test should be done over the ISR LTE connection and used in
conjunction with the suggestions below to determine if antenna placement/replacement is needed.
-
RSSI: Received Signal Strength Indication – a generic radio receiver technology metric for signal strength.
Measures both usable signal and noise. Rated in dBm
o
“
Good” value is greater than -80 dBm
(e.g. -79 is greater than -80)
-
RSRP: Received Signal Reference Power – the average of the power received of all radio resource elements
that carry cell-specific reference signals. Measures usable downstream signal. Rated in dBm
o
“Good” value is greater than – 105dBm
(e.g. -104 is greater than -105)
-
RSRQ: Reference Signal Received Quality – the ratio of usable signal usable+noise signal (RSRP-RSSI).
Measures how close the usable signal is to usable+noise. Rated in dBm.
o
“Good” value is greater than -12dBm
(e.g. -11 is greater than -12)
-
SNR: Signal to Noise (Interference) Ratio – The ratio of usable signal to noise (plus interfering) signal.
Measures how much of the total signal is usable by comparing usable to noise. Rated in dB
o
“Good” value is greater than 5 dB
(e.g. 6 is better than 5)