PMP Synchronization Solutions User Guide
Interference and reliability
PMP-0297 007v001 (January, 2017)
1-3
Sources of interference
In general, there are three basic categories of interference:
Self-interference
Emanating from an organization’s own operating environment, self-interference is a factor
in both licensed and unlicensed frequencies. In either band, self-interference occurs when
distinct signals come from a network under your control, whether from the same tower
location or from several miles away. Furthermore, the larger and denser the network
grows, the more it will be exposed to self-interference and the reliability and performance
issues it may cause.
In most cases, it is best dealt with self-interference the network planning stage. In building
or extending a wireless network, proper product design, ad- vanced technology (such as
Cambium’s industry leading use of GPS synchronization) and the ability to reuse a
frequency band within the spectrum can in most cases combine to reduce self-interference
to a point at which it does not have a significant impact on network performance and
reliability.
External interference
In unlicensed frequencies, interference is more difficult to manage, since the interference
comes from networks and technology not under your control. Because a single access
point can support hundreds of subscribers or end users, interference can have a
substantial impact.
Other networks aren’t the only culprits; more and more network interference is coming
from a wide range of consumer devices — such as surveillance cameras, Wi-Fi hotspots,
and microwave ovens — that may operate in or near the same frequency. Furthermore, a
network must be designed to not only deal with present interference sources, but must
also be pre- pared to deal with potential future sources as the wireless environment
evolves and usage of the spectrum expands.
Ambient Noise
Also called the noise floor, ambient noise is simply background noise that is always
present in a frequency band. It is caused by the growing numbers of wireless devices —
from garage door openers to other wireless networks — operating in the same unlicensed
frequency. These all crowd the spectrum and can be a significant factor in degrading signal
and bandwidth. Ambient noise levels increase as more devices and networks are deployed
in the spectrum.
