With the increased demand for Broadband Wireless Access (BWA) networks, there is a significant interest in sharing the same radio spectrum for BWA and Fixed Satellite Service (FSS). However, many FSS receivers are located in the same geographical areas as the areas with an increased demand for BWA. Signals received by FSS ground receivers travel long distances from geostationary communication satellites and thus may have weak signal strength upon arrival at the FSS ground receivers. These received FSS signals may be weak and may benefit from significant protection from BWA signals from nearby terrestrial base stations and user equipments (UE) transmitters. Interference from terrestrial base station BWA transmitters to the FSS satellite receivers is thus of concern.
Example embodiments of the present inventive concepts now will be described with reference to the accompanying drawings. The present inventive concepts may, however, be embodied in a variety of different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present inventive concepts to those skilled in the art. In the drawings, like designations refer to like elements.
Satellite downlink transmission of broadcast television occurs in the C-band (3.7 GHz to 4.2 GHz) from Fixed Satellite Service (FSS) satellites while uplink transmission may be between 5.925 to 6.425 GHz. A typical satellite may have multiple C-band transponders, with each transponder having one or more channels occupying a total bandwidth up to 72 MHz. A terrestrial FSS receiver may receive signals from various channels transmitted by some, but not all of the C-band transponders. Although the example embodiment provided herein are in the context of C-band FSS receivers, the techniques described herein may apply to any frequency bands used by FSS satellites and/or FSS receivers, such as Ku-band FSS satellites and/or FSS receivers. A geostationary satellite may be at a distance of more than 22,000 miles from a FSS receiver. Due to the distance traveled by the signals from the C-band satellite transponders, the signal strength may be relatively weak and thus may be susceptible to interference from terrestrial communication networks such as Broadband Wireless Access (BWA) networks. Base stations (BS) and User Equipments (UE) of BWA networks may be in close proximity (i.e. within a few miles) to the FSS receivers. Various embodiments described herein arise from the recognition that terrestrial co-channel use of satellite frequencies may interfere with the satellite signals received at the satellite receive station. MIMO interference reduction techniques are described herein in a real-world environment to reduce interference to FSS receivers.
Modern communication systems utilize Orthogonal Frequency Division Modulation (OFDM) and other advanced waveforms to create signals from a base station (BS) targeted to User Equipments (UEs). The base station may enhance the signal to a given UE while reducing the signal strength in other areas not near the given UE, by using directional techniques such as beam forming and/or solutions such as massive multiple-input and multiple-output (MIMO) systems. Channel State information (CSI) may be used to configure MIMO and/or massive MIMO systems. The term “channel state information” (CSI) may be used to refer to channel characteristics between a base station and a UE in a BWA network. The term “satellite channel status” (SCS) may be used to refer to channel characteristics between a satellite and the FSS receiver.
In wireless communications, channel state information, may refer to known channel properties of a communication link. This information describes how a signal propagates from the transmitter to the receiver and represents the combined effect of, for example, scattering, fading, and power decay with distance. Techniques such as channel estimation may be used to characterize the aforementioned effects. The CSI makes it possible to adapt transmissions to current channel conditions, which may be used for achieving reliable communication with high data rates in multi-antenna systems. In some cases, the CSI may be measured and/or estimated at the FSS receiver and fed back to the base station transmitter in order to facilitate transmitter adjustments such as channel selection, transmit power, etc. The CSI may be used by a base station or a UE in a BWA network to improve the quality of communication. In other words, signal transmission parameters between BWA network elements such as a base station and a UE may be changed to reduce interference to an FSS receiver's operation.
Depending on the channel state information associated with a given FSS site, a base station may make computations that will use one or more multi-element antennas at the base station to enhance or reduce the radio signal strength directionally. In some embodiments, multiple base stations may coordinate with one another to directionally send signals to UEs. Interference may be mitigated in systems where base stations may be in different locations but still cover similar and/or partially overlapping geographical areas.
A Massive MIMO beamforming solution using a feedback loop between monitor stations located near or at the FSS receiver site and/or one or more BWA base stations may reduce interference between FSS signals and BWA signals. Monitor stations may include passive devices, modified UEs, or custom built receivers that listen for and/or receive FSS transmissions and/or BWA network transmissions between UEs and base stations. In some embodiments, a UE of the BWA network may perform the functionality of the monitor station. Monitor stations may be located after the FSS antenna, or if that is not possible, within meters of near or at the FSS receiver (i.e., in close geographic proximity to the FSS receiver). In some embodiments, monitor stations may be configured to listen for and/or receive C-band signals, but may not transmit C-band signals. The monitor stations may facilitate a second feedback loop that detects signals before or after the FSS receiver antenna and provides information about interfering signals that have been seen by the monitor station to the BS controller. This second feedback loop may work in conjunction with the first feedback loop or may work independently from the first feedback loop. The second feedback loop may include a receiver/detector monitor located before or after the FSS antenna, and may be designed to specifically look for unique characteristics of the BS or UE waveform in order to discriminate from the FSS signal, or take advantage of a gap in transmission, blanking interval, or unused spectrum located between multi-carrier transponders in the FSS downlink transmissions. A gap or blanking interval in the downlink transmissions can occur due to the nature of the application or by operator design without significantly affecting the performance of the FSS. C-band signals for FSS may include services such as broadcast television that may have gaps or blanking intervals periodically or aperiodically between segments of data. The monitor stations, may send the CSI or the SCS to the core network directly to one or more of the base stations in order to effect the feedback loop and allow the offending BS to take corrective action.
The UE may also contribute to a raised interference level at the FSS site. Monitor stations may monitor base station transmissions or may monitor UE transmissions. In the case of UE caused interference, the UE may not be able to modify antenna patterns, so the feedback loop would need to inform the base station to no longer allocate frequencies falling within the channel receive bandwidth of the FSS receiver to the offending UE. This could include shifting operation between the UE and the base station to an in band channel with FSS or to an out of band channel, if available.
Additionally, a terrestrial FSS receiver (i.e., ground station) may provide information to the core network, the base station, or the base station controller regarding polarization, modulation, channel on/off status, and/or antenna pattern information, which may be used by the base station controller to further reduce interference potential. This information may be sent back to the base station controller via monitoring stations via a wired facility and/or on an out-of-band channel.
In some embodiments, CSI or SCS may be sent to the core network or to the base station controller from monitor stations during a FSS downlink transmission. Monitor stations may send this information infrequently, such that the disruption to FSS transmissions may occur infrequently, thus causing minor signal interference/degradation. In some embodiments, monitor receivers may send information infrequently, such as when interference that is causing an increase in Bit Error Rate (BER) is detected. FSS receivers may take advantage of Forward Error Correction (FEC) methods to overcome any minor degradation of FSS downlinks. FSS operation may also assign a small portion of the FSS frequency band, such as a FSS sub-band, to enable feedback to the base station controller. The FSS sub-band may be used on a continuous basis to provide a feedback loop for the CSI or SCS to the base station controller and reduce/minimize interference to the FSS receiver from a BWA base station.
Communication between UEs and the base station may interfere with the signal received by FSS signals. In some embodiments, in order to mitigate interference from a UE to BS at the FSS receiver, the state information from the UE may be transmitted in guard bands between the downlink channels used by the C-band transponders to communicate with the terrestrial FSS receiver. Use of the guard bands by the UE to transmit state information may significantly reduce interference with the FSS receiver.
Various embodiments will now be discussed in further detail with reference to the figures.
The user equipment 150 may be (or may be a part of) one of various types of wireless electronic user devices, including mobile/cell phones, as well as wireless user devices without phone capabilities. For example, the user equipment 150 may be a smartphone, a laptop computer, a tablet computer, or any other portable, wireless electronic device with communications capability. The user equipment 150 can be located anywhere inside a geographical area serviced by a base station 130.
Referring now to
In some embodiments, coordination may not be possible between the FSS network and the BWA network since it may be difficult to update network topology changes in either network. However, in some embodiments, coordination between the FSS network and the BWA network may not be necessary for both networks to coexist using the C-band. Referring now to
The carriers associated with C-band channels may have some spectral energy in adjacent channels.
In some embodiments, the BWA network may use guard bands between C-band channels for BWA communications. In some embodiments, it may be understood that the guard band may be a part of the spectrum where a roll off of the signal at the edge of a channel has occurred. A guard band may be at an edge of the allocated spectrum or between adjacent carriers in a band. Referring now to
In some embodiments, the C-band channel usage may be coordinated between the FSS and the BWA network. The FSS C-band spectrum may be divided into FSS sub-bands. A coordinated effort between FSS operators and BWA network operators may allow specific FSS sub-bands to be allocated for use for terrestrial communications in the BWA network. As such, these terrestrially allocated FSS sub-bands would not be used in the FSS downlink. Referring now to
Referring now to
Referring to
A transmitter portion of the transceiver 742 may convert information, which is to be transmitted by the wireless electronic device 701, into electromagnetic signals suitable for radio communications. A receiver portion of the transceiver 742 may demodulate electromagnetic signals, which are received by the wireless electronic device 701. The transceiver 742 may include transmit/receive circuitry (TX/RX) that provides separate communication paths for supplying/receiving RF signals to different radiating elements of the antenna system 746 via their respective RF feeds. Accordingly, when the antenna system 746 includes two active antenna elements, the transceiver 742 may include two transmit/receive circuits 743, 745 connected to different ones of the antenna elements via the respective RF feeds. For example, the transmit/receive circuit 743 may be connected to a Wi-Fi antenna or a close/short-range (e.g., a Near-Field Communication (NFC) or BLUETOOTH®) antenna, whereas the transmit/receive circuit 745 may be connected to a cellular antenna or a 3G, 4G, LTE, or 5G antenna. Moreover, the antenna system 746/transceiver 742 may include a GPS receiver.
Referring still to
Referring to
A variety of different embodiments of the present inventive concepts have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments of the present inventive concepts described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.
It will be understood that when an element is referred to as being “connected,” “coupled,” or “responsive” to another element, it can be directly connected, coupled, or responsive to the other element or intervening elements may be present. Furthermore, “connected,” “coupled,” or “responsive” as used herein may include wirelessly connected, coupled, or responsive.
The terminology used herein is for the purpose of describing particular embodiments of the present inventive concepts only and is not intended to be limiting of the present inventive concepts. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including,” and/or “comprising,” when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The symbol “/” is also used as a shorthand notation for “and/or.”
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present inventive concepts belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It will be understood that although the terms “first” and “second” may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element could be termed a second element, and similarly, a second element may be termed a first element without departing from the teachings of the present inventive concepts.
A variety of different embodiments of the present inventive concepts have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments of the present inventive concepts described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination.
In the drawings and specification, there have been disclosed example embodiments of the present inventive concepts. Although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the present inventive concepts being defined by the following claims.
The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/609,457, filed Dec. 22, 2017, the disclosure of which is hereby incorporated herein it its entirety by reference.
Number | Date | Country | |
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62609457 | Dec 2017 | US |