FAQ


Are there any problems with multi users on one unit? That is if our neighbours in adjacent offices on the same network use it?


Within the footprint of the unit any devices on that particular network will use it (so yes, neighbours might see benefit).  There is a limit to the number of users; this is because all of the uplink traffic from the users within its coverage is funnelled through the uplink radio of the Cel-Fi unit and it has a finite maximum power.

The number of calls the unit can support depends on how far away it is from the serving base station (shown by the number of coverage bars on the display of the Cel-Fi Window Unit). Where the coverage is weak (1 or 2 bars on the Cel-Fi Window Unit) the unit may support as little as 3-6 calls.  Where the coverage is good (4 or 5 bars on the Cel-Fi Window Unit) of the order of 20 calls can be supported.

How does Cel-Fi differ from a broadband repeater?


Cel-Fi does several things:
1. A Cel-Fi device only boosts specific UMTS carrier frequencies (5MHz channels, up to 3) and not the whole band.
2. Cel-Fi will only boost the pre-configured UMTS carrier frequencies if they actually contain a valid UMTS signal and are for the correct network (i.e. the Cel-Fi device can lock onto the UMTS pilot channel, like a phone, and read broadcast information, such as the network identity or ‘PLMN-ID’ then determine what to boost)
3. Cel-Fi automatically limits its boost when close to the base station (based on a calculation of the actual RF path-loss) and so will never boost thermal noise to a level where the base station’s uplink performance will be damaged
4. Cel-Fi is unconditionally stable and will never oscillate – oscillation is usually a common and serious problem with traditional repeaters which causes power spikes that degrade the base station’s uplink performance.

Does Cel-Fi work internationally?


Cel-Fi units are not only set to particular frequencies, but they are locked to the network identity (referred to as the ‘PLMN-ID’). Therefore Cel-Fi devices typically only work for the particular country and network they are sold to. Only Nextivity can create the configuration for any given network.

What’s the radiation level of Cel-Fi RS2?


So is the Cel-FI RS2 Signal booster safe? We actually test the Cel-Fi units like a phone for a SAR rating. Anything with a SAR rating of less than 2.0 is defined as ‘touch safe’. Both the Cel-fi window unit and coverage unit have a SAR rating below 2.0.

Technically measuring SAR is usually only done for hand-held or body worn devices so WiFi routers generally don’t have a SAR rating. In any case the power we emit is no greater in general than other consumer wireless networking devices and smart phones.