Microwave Transmission KPIs: Key Performance Indicators Explained
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Microwave transmission remains a critical backbone for modern telecommunications, connecting cell towers, enterprise networks, and remote locations. However, a microwave link is only as good as its performance and stability.
To monitor and maintain these networks, engineers rely on Key Performance Indicators (KPIs). KPIs are essential metrics used to measure the quality, capacity, and reliability of a microwave link, ensuring it meets strict Service Level Agreements (SLAs). In this guide, we will break down the most important microwave transmission KPIs, how they are measured, and why they matter.
Core Network Performance Metrics
These KPIs define the actual user experience and the overall reliability of the network. They are typically the metrics written into a customer’s SLA.
Availability
Availability is arguably the most critical KPI. It indicates how much time the microwave link is fully operational and available to carry traffic without disruption. It is calculated using following formula in units of percentage.
Throughput
Throughput measures the actual amount of data successfully transmitted over the microwave link at a given time.
Monitoring throughput helps network planners understand if a link is nearing capacity and requires an upgrade (via higher modulation or additional channels).
Latency
Latency is the delay in data transmission from one end of the link to the other, usually measured in milliseconds (ms).
High latency causes lag. Interestingly, in direct Point to Point (PtP) routes, microwave transmission often has lower latency than fiber optic cables, making it the preferred choice for High Frequency Trading (HFT) networks where every millisecond counts.
Packet Loss
Packet loss is the percentage of data packets that fail to reach their destination during transmission.
Even a small amount of packet loss can lead to data retransmissions (slowing down the network), broken or choppy voice calls (VoIP), and a generally poor user experience.
Radio Frequency (RF) & Signal Health
To maintain the core performance metrics listed above, engineers must monitor the physical health of the radio signal. Following are the KPI parameters useful for such tasks.
Received Signal Level
It is the absolute foundation of link monitoring. It is the signal strength received at the microwave antenna, measured in dBm (decibel-milliwatts).
Fade Margin
Weather happens. Fade Margin is the “buffer” of extra signal strength engineered into the link to handle temporary fading conditions, primarily heavy rain or atmospheric changes.
Modulation
It defines the method used to pack data onto the radio wave. Common types include QPSK, 16QAM, 64QAM, up to 256QAM and beyond. Modern radios use Adaptive Modulation.
Higher modulation schemes (like 256QAM) provide much higher data capacity. However, they require a very clean, strong signal. Lower modulation schemes are slower but offer higher robustness against noise and bad weather.
Interference
Interference consists of unwanted radio signals that degrade the quality of your microwave link. Types are as follows.
- Co-channel: Interference from another link using the exact same frequency.
- Adjacent channel: Bleed over from a frequency right next to yours.
- Cross-polar: Interference between horizontal and vertical polarizations on the same antenna.
Physical Planning and Alignment
A link will only achieve its target KPIs if it is physically planned and installed correctly. This involves the Link Budget, which is the mathematical calculation of all expected gains (TX power, Antenna gain) and losses (Path loss, Rain loss) to ensure the signal arrives properly.
Line of Sight (LOS) & The Fresnel Zone
For microwave transmission to work, you need a clear, unobstructed path between the two antennas; this is the Line of Sight (LOS).
However, visual clearance isn’t enough. Radio waves spread out into an elliptical shape known as the Fresnel Zone.
At least 60% of the first Fresnel Zone must be completely clear of obstacles (buildings, trees, terrain) for proper signal propagation.
Link Alignment
Alignment is the physical process of meticulously adjusting the “pan and tilt” of the antennas during installation.
The goal of alignment is to perfectly point the antennas at each other to achieve the absolute maximum RSL and best possible signal quality.
Future : E-Band Technology
As demand for throughput increases, networks are utilizing higher frequency bands. The E-Band operates in the 70/80 GHz frequency range. It provides massive capacity (up to 10 Gbps) and avoids the congestion of lower frequencies.
Because high frequencies are easily absorbed by rain and oxygen, E-band is strictly limited to short distance hops, typically between 0.5 and 3 kilometers.
Summary
Microwave transmission KPIs help identify performance bottlenecks, maintain high network availability, and ensure reliable data transport. Continuous KPI monitoring supports efficient network optimization and proactive maintenance.