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When most people think about problems with in-building cellular reception, they tend to focus on the inability to get the incoming cell signal through their walls and receive calls or texts.

However, the problems presented by weak cellular coverage are two-fold: First, the incoming or downlink signal needs to be strong enough to reach your phone or cellular-connected device. Second, the outgoing or uplink signal needs enough power to transmit back to the cell tower.

Bi-directional in-building amplifiers are engineered to handle both of these tasks using the same antenna(s).

What is a bi-directional amplifier and what is it used for?

A cellular bi-directional or two-way amplifier receives, amplifies, and broadcasts cellular signal back and forth from the cell tower—and then to your phone, tablet, or cellular-connected device. In receive mode, the BDA amplifies incoming cell signal and broadcasts it throughout your building using the system’s indoor antenna(s) to enhance coverage. While in transmit mode, it amplifies and extends the range of outgoing signals from your building, regardless of the carrier. Within this basic architecture of bi-directional amplifiers, there are some additional differences to consider when comparing BDA systems, and how they  can affect performance and coverage range.

Differences between bi-directional amplifier systems

There are two types of bi-directional amplifiers: full-duplex and half-duplex. A full-duplex bi-directional amplifier simultaneously receives and transmits cell signal. It uses either a separate transmit and receive frequency or by frequency division multiplexing (FDM). These BDAs use duplex filters to prevent interference between outgoing and incoming signals. A half-duplex bi-directional amplifier can only receive or transmit cell signals at one time. With a half-duplex BDA, transferring between the reception and transmission functionality occurs with the help of a switch network at the input and output ports, or through the use of intelligent biasing.

Factors that affect the performance of a bi-directional amplifier

Bi-directional amplifiers also vary greatly based on two values: gain and uplink-output power.

With the gain, you are comparing a measure of how much the signal is being amplified. Measured in decibels (dB), the greater amount of gain your amplifier has will indicate just how much more incoming cell signal it can amplify from the outdoor antenna(s).

The typical home booster offers 60+ to 65 dB gain. The WilsonPro Enterprise 4300 boasts +70 dB gain; the level-capped by for all FCC-approved commercial cell signal amplifiers. This power difference may not seem substantial until you know that decibels are measured exponentially.

For example, with every +3 dB increase, the cell signal’s power suddenly doubles in strength. Conversely, with every -3dB decrease in gain, the cell signal power essentially drops by half.

Measured in Decibel Milliwatts (dBm), the uplink-output power denotes the maximum amount of cell signal strength a BDA can transmit from inside your building to the surrounding towers.

The WilsonPro Enterprise 4300 averages almost +4 dB more uplink power than the WilsonPro Pro 70 Plus, which translates to more than twice the transmission power. It also has greater downlink power, delivering better indoor coverage—with the Enterprise 4300 capable of providing up to 100,000 sq. ft. in coverage area using multiple server antennas.

Why you need a bi-directional amplifier

We’ve covered the basics of bi-directional amplifiers, how they work, and why variances in gain and uplink-output power affect their overall performance.

WilsonPro bi-directional amplifiers can improve data and cellular coverage in buildings and businesses for any carrier or device. To learn more about the WilsonPro line of commercial cellular signal amplifier systems, click here.