Cellphone repeater basics

Outside antennas

How much of an improvement can be expected?

Base station unique ID numerology

CellTracker app for Android

What about “4G” LTE?

Timing Advance in LTE

The short story:

Sector antennas used on cell phone towers are ideal as outside antennas;

The outside antenna should have high gain;

Suitable bi-directional amplifiers are commercially available;

Smartphone apps that provide signal strength and base station ID are useful;

• With the arrival of “Long Term Evolution” (LTE), covering both voice and data frequencies becomes important.

Some gripes:

Android did not in the past provide information about what frequency band the phone is operating on — with API Level 24, Absolute Radio Frequency Channel Number is available: EARFCN for LTE, UARFCN for WCDMA and ARFCN for GSM).

Some providers (e.g. Verizon Wireless), do not encode base station geo-location in the signal (unlike e.g. U.S. Cellular);

In some regions, some providers (e.g. SPRINT) encode the center of the area that an antenna is designed to cover rather than the base station geo-location;

The FCC licenses the spectrum, yet does not provide listing of cell phone base stations (while such information is available in other countries).

Some antenna gains may be overstated in manufacturer's listing (common exception: sector antennas);

Berthold K.P. Horn, bkph@ai.mit.edu