Cisco Cisco 2800 3800 Series 1-Port (SFP) Gigabit Ethernet High-Speed WIC

Antenna Guide for ISR and CGR with Verizon Wireless 4G LTE

If the output of the “show cellular 0/x/0|0 radio” command is different than above and shows the “Technology Selected”

is eHRPD, only RSSI will be provided. This means that the LTE signal received is not present, or the LTE signal was

not good and the 3G signal was better and selected for use. The remediation is the same as not getting a “good” LTE

signal, but with an additional caveat listed in the Q&A section (LTE reselection). The way to determine which is the

case (no LTE signal or LTE signal not “good”) is to force the LTE interface to only use LTE. Note that the forcing is

”permanent”Jan ISR reload will not change the radio “preference” to “auto” (to return it to “auto” issue the command

again as shown below). Also, if not LTE signal is present, no cellular connection will be made with this setting, and

thus this test may affect data transfer.

Run the following enable-mode IOS command:

cellular 0/x/0 lte tech lte

(where x is the LTE eHWIC slot

number) or

cellular 0 lte tech lte

(for 819).

Issue the

show cell 0/x/0 radio

(for LTE eHWIC, or

show cell 0 radio

for 819) again and review the values

To return the setting to its default:

cellular 0/x/0 lte tech auto

(or

cellular 0 lte tech auto

for 819)

What can be done if the LTE signal strength and quality are not “good”? There are two common actions that can

be taken to improve the signal:

Relocate one or both antennas for better reception, and/or use antennas that are more

appropriate (meet the needs of that location and use).

Relocating antennas: Placement of the existing 2 antennas can make a significant performance difference due to

multipath interference, proximity to walls or structures that inhibit the signal, and proximity to devices emitting

interfering radio signals. This is especially the case where the ISR in located in a metal enclosure (kiosk, ATM) or a

room that significantly inhibits the signal. In these cases, the antennas should be placed outside the enclosure/room

using antenna cables as mentioned below.

Depending on the ISR model and what was ordered, 1 or 2 ten foot extension antenna cables are included with the

ISR. The antenna connected to the connector labeled “M0/MAIN” can be extended using this supplied cable (antenna

cable connects to antenna cable’s base and to ISR, no adapters needed). This allows placement up to 10 feet away.

By moving the main antenna to different usable locations, the best location can be determined. The antenna

connected to M1/DIV can be left connected directly to the ISR, or if there is a 2nd cable, it can be used.

Record the radio statistics (from the “show” command) before attaching cable(s) and moving antenna(s)

Connect the cable(s) and move the antenna(s) to a different location. Wait 1 minute, then record the radio

statistics and mark the antenna location(s).

Repeat the previous step as feasible for various antenna placements.

Choose the best placement from the above test, and check to see if all the signal values are “good”. If so,

move the antenna(s) to the location(s) permanently.

What if no nearby antenna location provides “good” LTE signal? The ISR can be moved to another location and the

test repeated. This can be done even if the location is not feasible for permanent installation. By determining if there

is a better location for reception, longer antenna cables can be ordered for the permanent installation. Up to 75 foot

LTE antenna cables are available from Cisco as standard SKUs. Note that for indoor antennas (such as the supplied

dipoles) proximity to a window may provide improved signal strength.