Methods and equipment for reducing power loss in cellular systems
Methods of powering a radio that is mounted on a tower of a cellular base station are provided in which a direct current (“DC”) power signal is provided to the radio over a power cable and a voltage level of the output of the power supply is adjusted so as to provide a substantially constant voltage at a first end of the power cable that is remote from the power supply. Related cellular base stations and programmable power supplies are also provided.
1. A method of powering a remote radio head, the method comprising:
determining a resistance of a power cabling connection between a power supply and the remote radio head, wherein determining the resistance of the power cabling connection comprises measuring a current level and a voltage level of a pulse transmitted by the power supply onto the power cabling connection;
outputting a direct current (DC) power signal from the power supply and supplying the DC power signal that is output from the power supply to the remote radio head over the power cabling connection;
measuring a current level of the DC power signal at the power supply;
automatically adjusting a voltage level of the DC power signal in response to changes in the measured current level of the DC power signal.
2. The method of claim 1 , wherein the voltage level of the DC power signal that is output from the power supply is adjusted so that the DC power signal at an end of the power cabling connection adjacent the remote radio head is maintained within a predetermined range notwithstanding variation in a current level of the DC power signal that is output from the power supply.
3. The method of claim 2 , wherein the predetermined range is a substantially constant voltage.
4. The method of claim 1 , wherein the resistance is automatically determined multiple times on the same day.
5. A protection circuit for a power cabling connection between a power supply and a remote radio head of a cellular base station, comprising:
an avalanche diode coupled between a power supply conductor of the power cabling connection and a return conductor of the power cabling connection, wherein the avalanche diode has a reverse breakdown voltage that is selected based on a maximum specified voltage for a power supply signal that is provided to the remote radio head;
at least one capacitor electrically coupled between the power supply conductor of the power cabling connection and the return conductor of the power cabling connection, in parallel to the avalanche diode; and
a fuse circuit coupled in series with the at least one capacitor between the power supply conductor of the power cabling connection and the return conductor of the power cabling connection.
6. The protection circuit of claim 5 , wherein the at least one capacitor is a non-polar electrolytic capacitor or at least two polar electrolytic capacitors.
7. The protection circuit of claim 6 in combination with a jumper cable, wherein the protection circuit is part of the jumper cable.
8. The protection circuit of claim 5 , further comprising a diode that is configured to prevent the at least one capacitor from discharging through the power supply.
9. A method of determining a resistance of a power cabling connection between a power supply and a remote radio head, the method comprising:
including a diode between a power supply conductor and a return conductor of the power cabling connection;
outputting a reverse direct current (DC) power signal having a first voltage level from the power supply onto the power cabling connection, wherein the reverse DC power signal is different from a DC power signal used to operate the remote radio head;
measuring a first current level of a reflection of the reverse DC power signal, wherein the reflection of the reverse DC power signal is received at the power supply via the power cabling connection; and
determining the resistance of the power cabling connection based on the first voltage level and the measured first current level.
10. The method of claim 9 , further comprising including a capacitor in parallel to the diode to power the remote radio head during a period when the reverse DC power signal is applied.
11. The method of claim 10 , further comprising providing a second diode that prevents the capacitor from discharging through the power supply during the period when the reverse DC power signal is applied.
12. The method of claim 9 , wherein the reverse DC power signal flows through the diode.
13. The method of claim 9 , wherein a reverse voltage across the remote radio head is equal to a forward voltage across the diode when the reverse DC power signal is output onto the power cabling connection.
14. The protection circuit of claim 8 , wherein the diode that is configured to prevent the at least one capacitor from discharging through the power supply is provided in series along the power supply conductor.