Patent Application
20100327968
This application claims the benefit of the Spanish Patent Application No. ES P200930383, filed on Jun. 30, 2009, which is hereby incorporated by reference in its entirety.
Embodiments of the present invention pertain to the field of mobile telecommunications, and more specifically to systems and methods for reducing the temperature of power amplifiers of base stations for cellular telecommunications networks.
Power amplifiers (PA from now on) are active elements that amplify an electric signal. These transistors usually have two inputs:
The transistors use the DC power supplied in order to get a similar, but amplified, signal to the RF signal input.
The power amplifiers are based on transistors that usually have a temperature range where they can operate. Operating temperature depends mainly on two factors:
There are different mechanical techniques in order to prevent this dissipated power from increasing the operating temperature too much: Fans; liquid cooling, mechanical design in order to improve air dissipation; air conditioning; etc.
When the maximum temperature threshold is surpassed there are several techniques that are designed to reduce this operating temperature. However they are mainly based on hardware and implemented directly in the PA, and their main function is to reduce the total output power in the PA.
In the past, GSM equipment has been based on PAs that can handle just one carrier. Therefore when the PA exceeds maximum temperature, there was only one countermeasure: reduce the total output power.
However, more recently, equipment has been introduced that allows more than one GSM carrier to be present in one PA. This type of equipment also allows multi-bearer technology (2G, 3G, LTE, WiMAX) inside one PA, enabling further countermeasures that can help to reduce power dissipated in the PA, and therefore reduce the total temperature in the equipment.
In this single RAN (multi-bearer technology) equipment power and frequency resources are common and shared between the different technologies. Several countermeasures can be implemented in order to reduce the power dissipated by the PA.
There are presently several solutions for reducing the power consumption of the power amplifiers used at the base station (BTS), also known as Node B in UMTS, of a mobile network. These solutions are either based on more efficient power amplifiers or techniques based on more sophisticated hardware, which, while feasible and quite efficient for new implementations, are not particularly useful for existing, legacy networks.
Document WO9633555 discloses a temperature compensated automatic gain control, which reduces temperature in order to control the operating temperature, avoiding reaching maximum temperature.
Document EP0735690 discloses a method for controlling power of radio apparatuses. It is in fact hardware that controls the temperature so that output power do not exceed a maximum value.
It is well-known that abbreviations and acronyms are frequently used in the mobile telephony field. Below is a glossary of acronyms/terms used throughout the present specification:
When the power amplifiers (PAs) reach their maximum temperature, actions must be taken. Normally, the actions adopted are aimed to reduce the total output power in the PA. Embodiments of the present invention are directed to methods to reduce the dissipated power without reducing the total output power.
Disclosed embodiments relate to methods for reducing operating temperature in power amplifiers of base stations of mobile networks.
For example, in accordance with one example embodiment, there is provided a method for optimising operating temperature in a power amplifier of a base station (BTS) of a cellular telecommunications network, the method comprising, for example:
the method further comprising:
The alarm message can include the temperature measured in the power amplifier. The predetermined conditions to execute the at least one action from a list of actions to reduce the dissipated power of the power amplifier can include calculating a weighted average of the temperatures measured in the last x alarm messages, being x configurable, and comparing said weighted average with the temperature threshold TTH.
The list of actions can include, for example:
The actions included in the list of actions can be prioritized.
The sending of the alarm message to the controller unit can be carried out via the BTS through the alarm link.
The parameter TTH is preferably configurable through the controller unit.
The method can further comprise:
In another embodiment there is provided apparatus for reducing operating temperature in a power amplifier of a base station (BTS) of a cellular telecommunications network, the apparatus including: a temperature sensor for measuring the operating temperature of the power amplifier, a controller unit for executing actions in the power amplifier; and an alarm unit for sending an alarm message to the controller unit if the operating temperature exceeds a predetermined temperature threshold TTH; the controller unit being operable to analyse the alarm messages received and, when determined conditions are met, executing at least one action from a list of actions to reduce the dissipated power of the power amplifier. The controller unit can be included in the BTS or in the BSC/RNC corresponding to the BTS. The alarm unit is provided with processing means such as a microprocessor or a microcontroller connected to the temperature sensor, in charge of periodically monitoring the temperature measured by the sensor to sending, when an alarm condition is detected, an alarm message to the controller unit. For that purpose the alarm unit can be provided with transmission means (e.g., a wireless communication module).
Power amplifiers have a working temperature range and performance will highly depend on the working temperature. This invention targets a more efficient power feed of the power amplifiers based on the expected power amplifier performance depending on the temperature.
There are known solutions that monitor and control the temperature in radios and PAs. However they are mainly directed at preventing equipment from reaching maximum temperature. The present invention, by contrast, is focused on optimizing several radio parameters, e.g. as MTBF, number of carriers, carrier separation, etc.
Another difference between the existing solutions and embodiments of the present invention is that these solutions are mainly design algorithms and hardware that are implemented by the manufacturers of network hardware while the present invention allows the mobile operator to configure the behaviour of hardware. One goal of the present invention is thus to optimize the temperature based on different parameters.
For a better understanding of the present invention, reference will now be made, by way of non-limiting example only, to the accompanying drawing in which:
Embodiments of the present invention are based on having alternative algorithms that help to reduce the dissipated power without having to use the default implementation (decrease total output power) which can have a higher impact in network performance.
Power Amplifiers (PA) are elements implemented in the BTSs responsible for providing enough power to the signal that is going to be broadcasted in a mobile network. Conventional PAs 3, as shown in
In disclosed embodiments a new limit is defined at a predetermined temperature value substantially below the conventional maximum temperature, in order to be able to launch some actions that are less aggressive before reaching that maximum temperature. The conventional limit will hereafter be referred to as TMAX (the maximum permissible temperature in the PA, so that when TMAX is reached the total output power in PA is reduced). The new limit will hereafter be referred to as TTH. An alarm is be configured in the PA 3, so when TTH is exceeded this alarm will be activated. The parameter TTH is defined in the controller unit 1 (BSC/RNC) and distributed to the BTSs 2 and PAs 3 through the normal O&M (Operations & Maintenance) links.
Whenever there is an alarm, PA 3 sends a message to the controller unit 1 via the BTS 2 through the normal alarm link defined by each supplier. This message initially only includes the temperature measured. The rest of the message will be blank in order to leave space for future enhancements.
Controller unit 1 takes several of the temperature measurements reported in order to make a more reliable decision and avoid launching the algorithm when there is a sudden peak measurement that effectively should not have any effect. Therefore controller unit 1 is able to have a weighing process in order to get to this significant value (e.g. minimum 4 alarms required and a normal average will be done). Additionally in the controller unit 1 there can be an additional threshold, a temperature reduction threshold TRTH in order to decide when to launch the temperature reduction algorithm. Whenever this threshold is surpassed, controller unit executes the algorithm in order to reduce temperature in the PA. This parameter TRTH will typically be higher than TTH. Logic approach is that there is a processing part in the controller that takes into consideration temperature values sent by the BTS. For example, a decision will only be made when at least a predetermined number of samples (say, x samples) have been received and an average of those x samples will be taken, the average being compared with TRTH or with TTH. In this way, decisions made based on peak sample values are avoided. This process can be quite complex and therefore it should be left open (e.g. average could be linear or weighted, such that the most recent sample is weighted higher than previous samples: for every sample: last sample multiplied by 1, previous one multiplied by 0.8, etc.).
Controller unit 1 has a parameter defining the priority list of the actions to be taken. Different actions can be made an each of them can be also prioritized between different technologies (2G/3G/LTE):
| Number | Date | Country | Kind |
|---|---|---|---|
| P200930383 | Jun 2009 | ES | national |
