Patent Application
20220070789
This disclosure relates generally to communication systems for distributing signals in a communications network.
The use of Signal Boosters, also referred to as bidirectional amplifiers (BDAs), and of Distributed Antenna Systems, also referred to as Fiber DAS or just DAS, which may include at least one DAS Master Unit (MU) and at least one DAS Remote Unit (RU), are the two most popular methods for extending the signal coverage of two-way radio systems in locations with poor reception or without signal coverage, such as indoor areas (buildings, tunnels, subways, etc.) as well as open areas (canyons, cliffs, valleys, etc.). BDA and DAS are bidirectional amplification devices or systems, with two or more amplifiers in an anti-parallel configuration, which provide simultaneous amplification to the downlink and uplink signals. Downlink signals are transmitted by the Base Station towards the Radios or terminal units, and the Uplink signals are transmitted by the Radios or Terminal Units towards the Base Station. The BDA and DAS amplify the signals when, due to physical barriers, the signals cannot propagate and suffer high attenuation. Being an amplifying system or device, the BDA and DAS do not only amplify only the signals but also the received noise. Because they are active components, they also generate noise of their own that is added to the amplified noise. The noise in the uplink direction has a serious impact on the performance of the Base Station receivers, affecting the capability to properly receive signals originating from Radios located far away from the Base Station. This effect is called Near-Far effect and affects all the two-way radio Base Stations that service BDA and DAS devices. As a result, the effective coverage area of a two way Base Station is reduced from its original designed coverage area, which seriously impacts the ability of two way Radio users located far away from the Base Station to obtain radio service. In order to minimize the Near-Far effect, it is important to reduce the uplink noise being generated by a BDA or DAS system towards the Base Station receiver.
Some BDA and DAS are equipped with uplink squelch functionality, which turns off the uplink amplification chain, totally or partially, when there are no uplink signals entering the BDA or DAS at the uplink input ports, or when the uplink signals entering the BDA or DAS at the uplink input ports have a power level that is lower than a predefined value. This squelch feature works well enough but requires a very fast circuitry response in order avoid modifying or altering the uplink signals during the turn on period. During the process of turning an electronic circuit on, there is a transitory time that elapses until the electronic circuit begins to work in a stable manner. When the transitory time period is long, the signals being amplified are distorted during that “turning on” period, which creates issues. For example, in a p25 radio, the symbol time is much smaller when compared with the turning on time, and hence the turn on process distorts the signal, resulting in the loss of many signal symbols, in turn creating synchronization issues in the communication establishing process.
Other BDA and DAS are equipped with a circuitry that controls the ON and OFF mechanism of the uplink output power amplifier stages, managed with a timer that allows the uplink output power amplifier stages to remain ON for a predefined or adjustable period of time after the uplink input port of the BDA or DAS stops receiving input uplink signals. That is, amplifiers that are not fast with respect to their turning on process, once turned on, they remain ON for a certain period, allowing subsequent communications to be established without the need to be turned back on every time that a new signal is received. So even when distortion occurs during the first time the amplifier is turned on due to the slow turning on process, the subsequent communications will not be distorted because the amplifier circuitry will be ON. This method typically does not avoid modifying or altering the first uplink signal received at the uplink input port of the BDA or DAS, but due to the use of the timer and the uplink output power amplifier stages remaining ON, the subsequent uplink signals (e.g., walkie talkie communications) received by the BDA, then amplified and transmitted to the base station by the BDA, will not be affected by the turn ON period. For example, when a police officer uses his or her radio for the first time, the communication from the officer is the first signal that passes through the BDA, resulting in the BDA being turned ON, and when the BDA is not fast enough with respect to the turning on process, that first call will be distorted or will have quality issues. In that scenario, a police station answers the first call, and then the officer calls again (i.e., generating a subsequent uplink signal) such as for example:
initial call: “police station, this is Officer Jones reporting, I need support”
second call: “Officer Jones, this is the police station, what is the status”
third call: “police station, this is Officer Jones, there has been a bank robbery”
The second, third and all other calls between the officer and the station are referred to as the “subsequent” calls. Since the BDA remains “ON”, then all those subsequent calls (or signals) passing through the BDA will not be distorted by the BDA turning on process, while the first one (initial call) does experience distortion. This squelch feature works well enough, but allows the BDA or DAS uplink chain to be ON, which causes noise to radiate to the Base Station receiver even when no uplink signals are being amplified by the BDA or DAS.
Therefore, there is a need in the art for an improved method and system for reducing the Near Far effect in a wireless coverage extension system.
The following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the various embodiments disclosed herein. This summary is not an extensive overview of every detail of every embodiment. It is intended to neither identify key or critical elements of every embodiment nor delineate the scope of every disclosed embodiment. Its sole purpose is to present some concepts of disclosure in a simplified form as a prelude to the more detailed description that is presented later.
A system for managing an uplink amplification chain in a coverage extension system is disclosed. The system includes a transceiver unit; an uplink amplification chain including one or more amplifiers; and an ON/OFF mechanism that turns ON or OFF the uplink amplification chain totally or partially. The uplink amplification chain is located within the transceiver unit. The ON/OFF mechanism receives from an external source instructions directing the ON/OFF mechanism when to turn ON or OFF the amplification chain totally or partially.
The following description and annexed drawings set forth certain illustrative aspects of the disclosure. These aspects are indicative, however, of but a few of the various ways in which the principles disclosed may be employed. Other advantages and novel features disclosed herein will become apparent from the following description when considered in conjunction with the drawings.
The drawings, in which like numerals represent similar parts, illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.
The foregoing summary, as well as the following detailed description of certain embodiments of the subject matter set forth herein, will be better understood when read in conjunction with the appended drawings. In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the subject matter disclosed herein may be practiced. These embodiments, which are also referred to herein as “examples,” are described in sufficient detail to enable those skilled in the art to practice the subject matter disclosed herein. It is to be understood that the embodiments may be combined or that other embodiments may be utilized, and that variations may be made without departing from the scope of the subject matter disclosed herein. It should also be understood that the drawings are not necessarily to scale and in certain instances details may have been omitted, which are not necessary for an understanding of the disclosure, such as details of fabrication and assembly. Furthermore, references to “one embodiment” are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the subject matter disclosed herein is defined by the appended claims and their equivalents.
The present disclosure describes a system that solves the problems with the prior art. The exemplary implementations disclosed herein include a mechanism to externally instruct the BDA or DAS when to turn on and turn off the uplink amplification chain, totally or partially. For example, an amplifier in the uplink amplification chain may be implemented as a digital variable gain RF amplifier. If more than one amplifying stage is to be turned OFF (or gain decreased), in one embodiment the amplifying stage (in the uplink direction) closer to the base station would be turned OFF first.
The ON/OFF mechanism 105 can be a mechanical ON/OFF switch or an ON/OFF button (which would require an actuator), or a dry contact sensing device such as, but not limited to, an opto-coupled sensor, a relay, or any other type of ON/OFF device. These features differ from the prior art in that conventional methods for turning on a BDA involve turning the BDA on when receiving signals from the radios or the Base Station, captured by the antenna, but there is no BDA that is ready to start the amplifying operation when, for example, a fire alarm goes off and there is an emergency, which is the precise time that the BDA (or DAS) needs to begin the turning on process. The external source can be the fire alarm system or an on/off button. Most Public Safety systems need to operate when the alarm system is on, or when there is an emergency, and should remain OFF during the rest of the time while there is no emergency and hence, no firefighters/first responders, etc. are inside the building.
In the embodiment illustrated in
The ON/OFF mechanism may be implemented as part of the BDA or MU or RU, or may be an external component that provides the BDA or MU or RU with the instructions to turn ON or turn OFF, totally or partially, the uplink amplification chain. Those instructions may also include instructions to manage the RF connection and disconnection circuitry, where the RF connection and disconnection circuitry can be an internal component of the BDA or MU or RU, or can be an external device.
The descriptions set forth above are meant to be illustrative and not limiting. Various modifications to the disclosed embodiments, in addition to those described herein, will be apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the concepts described herein. The disclosures of each patent, patent application, and publication cited or described in this document are hereby incorporated herein by reference, in their entireties.
The foregoing description of possible implementations consistent with the present disclosure does not represent a list of all such implementations or all variations of the implementations described. The description of some implementations should not be construed as an intent to exclude other implementations described. For example, artisans will understand how to implement the disclosed embodiments in many other ways, using equivalents and alternatives that do not depart from the scope of the disclosure. Moreover, unless indicated to the contrary in the preceding description, no particular component described in the implementations is essential to the invention. It is thus intended that the embodiments disclosed in the specification be considered illustrative, with a true scope and spirit of invention being indicated by the following claims. Further, the limitations of the following claims are not written in means—plus-function format and are not intended to be interpreted based on 35 U.S.C. 112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.
This application claims the benefit of U.S. Provisional Application No. 63/073,676 filed Sep. 2, 2020, the disclosure of which is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63073676 | Sep 2020 | US |
