Modulation and coding for a high altitude platform

Modulation and coding for a high altitude platform is disclosed. An example apparatus includes a gateway antenna configured to communicate with a ground-based gateway station and user antennas configured to provide communication coverage among a plurality of terminals within a specified area on the ground or in the air. Each user antenna is configured to communicate with a cell within the specified area. The example apparatus also includes a processor configured to demodulate and decode a first modulation scheme and a first coding scheme used for a feeder link provided by the gateway antenna, and apply at least a second modulation scheme and a second coding scheme for user links provided in spot beams by the user antennas. The first modulation scheme and the first coding scheme are configured to be relatively more spectrally efficient compared to the second modulation scheme and the second coding scheme for the user links.

BACKGROUND

Communications platforms include towers, balloons, Unmanned Aerial Vehicles (particularly High Altitude Platforms (“HAPS”) and High Altitude Long Endurance (“HALE”) platforms), and satellites at low (“LEO”), medium (“MEO”) and geostationary (“GEO”) Earth orbits. These platforms use directive antennas to form spot beams to provide communication coverage over a specified surface area on Earth referred to as cells. As discussed herein, a cell is a geographical coverage area on the surface of the Earth or in the atmosphere between a communication platform and the area on the surface of the Earth. A spot beam is a radiation pattern of an antenna that illuminates a cell. A surface spectral density (Hertz per square kilometer (“Hz/km2”) within the coverage area is typically increased by increasing the number of radiated spot beams to partition the coverage area into multiple cells and reusing the available spectrum many times. For instance, dividing an area previously covered by one broad beam into 19 cells covered by 19 narrow spot beams and splitting the frequency spectrum into four equal parts (and reusing the spectrum in smaller cells) may result in a surface spectral density that is increased by a factor of 19/4 or nearly five-times. To provide broad and uniform coverage with a high surface spectral density, the telecommunications platform accordingly may use a plurality of antennas such that each antenna is configured to provide similar communication coverage (e.g., a spot beam) to a cell. It is also common practice in satellites to create multiple beams from a single antenna by using more than one duplex feed for each antenna.

In hub-and-spoke networks, also called star networks, communication platforms facilitate communication between at least one gateway station or feederlink station and a plurality of user terminals within a coverage area. The gateway stations are directly connected to the Internet or other local, wide, or geographic computer/television network and configured to provide an Internet/television connection to the user terminals. The communications platforms have at least one feeder link to the gateway station, which is located in one of the cells. The communications platforms convert the forward feeder link uplink signals into forward user link downlink signals provided by the spot beams to user terminals. Similarly, the communications platforms convert user terminal return uplink signals into a return downlink to the gateway station.

Some communications platforms perform demodulation and decoding on each signal received via the feeder link from the gateway station. The signal may include an array of individual baseband packets or time-divided data, which is individually switched by the communications platforms to the appropriate downlink. The communications platforms combine all of the individual baseband packets (or time-divided data) destined for a particular spot beam into a downlink signal, which is coded and modulated for transmission via the spot beam. Some communications platforms also perform the demodulation, decoding, and switching of individual baseband packets (or time-divided data) received in the user terminal return transmissions for transmission to one or more gateway stations, other communications platforms or even other user terminals.

In most communications platforms, however the feeder link with the gateway station uses the same modulation/demodulation and coding/decoding scheme as the links for the user spot beams. Such a configuration is typically optimized for the user terminals because these devices have very low antenna gains and are more frequently subject to fading and noise from environmental factors. This optimization typically includes using modulation and coding schemes that produce relatively more robust links at the expense of being spectrally inefficient, where spectral efficiency is the data rate achieved per unit of spectrum (bps/Hz). If the platform-user terminal link conditions deteriorate due to, for example, heavy rain, an even more robust modulation and coding scheme must be used, thereby further reducing overall system capacity not only on the platform-user terminal link but also on the unimpaired feeder link.

SUMMARY

The present disclosure provides a new and innovative system, method, and apparatus for modulation and coding in a telecommunications platform such as a HAPS, LEO or MEO communications platform to achieve high capacity given the limited allocated frequency resources. The example system, method, and apparatus disclosed herein use a multiplicity of spot beam antennas within the telecommunications platform to illuminate cells within a coverage area. This is necessary to close the user links with sufficient margin to support high data rates and overall system capacity.

The example system, method, and apparatus disclosed herein use a processor within the telecommunications platform to demodulate and decode a feeder link from a gateway station to recover a baseband signal. This enables a different modulation-coding (“MODCOD”) mode to be selected for the feeder link that is independent of the MODCOD mode for the user links. Such a configuration of different MODCOD modes enables a spectrally efficient MODCOD mode to be used for the feeder link with the gateway station to improve bandwidth while a different MODCOD mode for the user links carried by the spot beams is optimized for robustness.

The example system, method, and apparatus disclosed herein may use a switch within a telecommunications platform to dynamically share the 47 GHz band spectrum between a Gateway-HAPS uplink and multiple HAPS-user terminal downlinks. On the downlink spectral resources may be shared in either time or frequency or both between various spot beams.

In an example embodiment, a telecommunications platform or transceiver apparatus includes a gateway-link antenna configured to communicate with a ground-based gateway station and a plurality of user-link antennas configured to provide communication coverage among a plurality of terminals within a specified area on the ground. Each user-link antenna is configured to communicate with a specified cell within the specified area. The platform or transceiver apparatus also includes a processor (or circuitry components) configured to demodulate and decode a first set of modulation and coding schemes (e.g., a first MODCOD mode set) used for an uplink feeder link provided by the gateway antenna and apply a second set of modulation and coding schemes (e.g., a second MODCOD mode set) for user links provided in spot beams. The first MODCOD mode set is configured to be relatively more spectrally efficient to provide a better data rate for the feeder link compared to the second MODCOD mode set for the user links.

In another example embodiment, a method to provision a telecommunications apparatus includes determining a first set of modulation and coding schemes (e.g., a first MODCOD mode set) that is spectrally efficient for a feeder link communicatively coupled to a gateway antenna. The example method also includes determining a second set of modulation and coding schemes (e.g., a second MODCOD mode set) that is robust for user links communicatively coupled to respective user antennas, each antenna being configured to communicate with a specified cell within the specified area. The method further includes provisioning the telecommunications apparatus with the first MODCOD mode set and the second MODCOD mode set.

Additional features and advantages of the disclosed system, method, and apparatus are described in, and will be apparent from, the following Detailed Description and the Figures.

DETAILED DESCRIPTION

The present disclosure relates in general to a method, apparatus, and system to use different modulation/demodulation schemes and coding/decoding schemes within a telecommunications platform. As disclosed herein, the term ‘platform’ may refer to any Low Earth Orbit (“LEO”) satellite, Medium Earth Orbit (“MEO”) satellite, Geosynchronous Earth Orbit (“GEO”) satellite, and/or High Altitude Platform (“HAP”). A HAP may include any airship, airplane, balloon, etc. operating between, for example, 17 km and 22 km over the surface.

The example method, apparatus, and system disclosed herein are used in conjunction with a high capacity telecommunications platform configured to relay communications between one or more gateway stations and a plurality of user terminals within a specified coverage area as shown inFIGS. 1 and 2. The telecommunications platform is configured with multiple antennas to provide multiple spot beams to respective cells within the coverage area. The telecommunications platform may also be configured for frequency reuse to improve overall system capacity.

In high capacity communication systems, bandwidth is provided by using a large number of gateway stations. The capacity of a telecommunications platform is therefore limited by the number of gateway stations that can be used because each gateway station has a limited spectrum to use for communications with the platform. The use of many gateways stations to increase capacity is problematic because some gateway stations may have to use the same spectrum as the user links if the gateway stations are located in the same areas as the user terminals, thereby creating interference or reducing signal quality. Further, gateway stations are expensive, require high speed access to terrestrial fiber, and need a facility to house a large antenna. It should be appreciated that reducing the number of gateway stations can reduce the overall cost of deploying and operating the ground-segment of the system. However, reducing the number of gateway stations may reduce overall bandwidth capacity.

The telecommunications platform disclosed herein is configured or provisioned to improve (or maximize) the spectrum efficiency for each gateway station link to reduce (or minimize) the required bandwidth to achieve the desired capacity, and therefore reduce the number of gateway stations. The improvement in spectrum efficiency within the example telecommunications platform accordingly reduces system implementation costs and operating costs because fewer gateway stations are needed to maintain capacity for user terminals. Since there are fewer gateway stations than user terminals, the gateway antenna and the radio frequency (“RF”) chain at the gateway station can have considerable gain, and thus can support more spectrally efficient modulation/demodulation schemes and coding/decoding schemes (e.g., MODCOD modes or MODCOD mode sets) on both the uplink and downlink between the gateway and the telecommunications platform. This enables more robust modulation/demodulation and coding/decoding schemes (e.g., MODCOD modes or MODCOD mode sets) to be used for the uplinks and downlinks between the telecommunications platform and the user terminals within the spot beams. The more robust MODCOD modes compensate for the smaller antennas (and consequently lower gains) at the user terminals and signal deterioration due to environmental conditions on these links.

It should be appreciated that robust MODCOD modes are necessarily less spectrally efficient than highly efficient MODCOD modes. Spectrally efficient MODCOD modes require higher link quality or signal-to-noise ratio than more robust MODCOD modes which are preferred on links with poor quality or signal-to-noise ratios. The separation of MODCOD modes for gateways stations and user terminals accordingly enables the most optimal MODCOD mode to be used for each communication path without having to sacrifice robustness, quality, or spectral efficiency desired for other communication paths. One benefit of using a more spectrally efficient MODCOD mode for communications between a gateway station and a telecommunications platform is that fewer gateway stations are needed overall to support, for example, a coverage area with 19+ cells having an area over 36,000 km2.

HAPs configured to support communications have been envisioned since the 1970s. However, technology to support high-speed and reliable wireless communication has not become available until recently. Additionally, technology to maintain HAPs within the air for extended periods of time (e.g., HALE) has only recently become available. For instance, the energy density, weight, and size of batteries, fuel cells, and solar cells have become advanced enough to support continuous operation of an airship or blimp in the sky for 30 to 60 days or more.

HAPs have several potential advantages compared to higher altitude satellites. For instance, HAPs generally have a relatively low communication latency in the 100's of microseconds (“μsec”) compared to latencies of 100's milliseconds (“msec”) for GEO satellites and 10's msec for LEO satellites operating over 500 km. Additionally, HAPs have a shorter product development cycle time compared to satellites, which require space qualification in addition to engineering design that ensures continuous operation for an extended period of time (e.g., ten years). Also, launching a few GEO satellites or a large constellation of LEO satellites can be very expensive and high risk. This means that HAPs may be developed with less upfront capital investment than satellites. HAPs may also be repaired and/or upgraded relatively easily by landing the HAPs for service. In comparison, satellites cannot generally be repaired or upgraded once launched into space.

Further, HAPs may be provisioned one at a time so that a HAP-based communication system can be rolled out to different geographic areas at different times without affecting performance of other HAPs within the system. In contrast to HAPs, satellites are expensive and generally take several years to design, build, qualify, and launch before service can begin. LEO satellite systems also generally require that all satellites be provisioned at the same time to provide system wide coverage.

Another disadvantage of satellites is that there is generally too much capacity provided in low usage areas. Satellites have coverage areas that are relatively large where a sizable portion of the coverage area includes oceans, lakes, deserts, forests, and protected lands that have few (if any) users. Additionally, some LEO satellites spend a significant amount of time orbiting over oceans and other uninhabited areas. Since a sizeable portion of the coverage area (and consequently bandwidth) is provided to sparsely populated areas, satellites have trouble providing enough capacity in relatively small high usage areas where the amount of bandwidth for that area is limited. In contrast, HAPs are deployed where there are large concentrations of users (e.g., cities), thereby providing service where there is the greatest demand/need.

A further disadvantage of satellites is the power and antenna size needed to provide high QoS communications. Satellites are generally thousands of kilometers above the surface, which requires high power output per antenna and larger antenna sizes to maintain acceptable QoS parameters. HAPs in contrast are much closer to the surface (e.g., 17 km to 22 km) and can provide the same (or better) QoS with lower power and smaller antennas.

While the disclosure is not limited to any frequency, certain frequency spectrums have been allocated for HAP communications by regulatory bodies. These allocated frequencies are used in the examples discussed herein. For example, the uplink214bofFIGS. 1 and 2may use a frequency band between 31.0 and 31.3 GHz and the downlink216amay use a frequency band between 27.9 and 28.2 GHz. Additionally or alternatively, both the uplink214band the downlink214bmay use a frequency band between 47.2 and 47.5 GHz and 47.9 and 48.2 GHz. In the United States, the allocation includes the entire band between 47.2 and 48.2 GHz. In some instances, the boundary between uplink and downlink may be dynamically adjusted to meet traffic demand. The signals on the two links may use time division duplexing at the HAPs.

In one embodiment the forward downlink from the HAPS to the user terminals may use time hopping of the entire spectrum from one beam to another, dwelling on each beam as required. Another embodiment may divide the available spectrum into frequency channels so that each channel is allocated to a different spot beam. Frequency channels could be reused if the beams are far enough apart. Some combination of frequency and time division sharing of the spectrum between spot beams is also possible. The advantage of this embodiment is that more spectrum is available for the user data links. The disclosure is not restricted to these embodiments of this frequency plan. For instance, in the future, other frequencies may become available to HAP communications. Additionally, if the methods and apparatus of this disclosure are applied to LEO satellites, other spectrum is already available.

The problem for HAPS communications may be magnified because the allocated spectrum at 47 GHz is near the oxygen absorption band between 50.47 and 68.96 GHz. The atmospheric losses due to oxygen absorption can be made up for in a gateway station to HAPS feeder link by increasing the Effective Isotropic Radiated Power (“EIRP”) of the gateway station. Unfortunately, the user terminals should be low cost in order to make the HAPS system a competitive system and a sufficiently high antenna gain-to-noise-temperature (“G/T”) needed to support high throughput modulation and coding schemes may not be possible. The currently allocated spectrum for HAPS communications requires rethinking how newly evolving technologies are applied. While regulatory authorities are considering additional spectrum for HAPS, there exists competition for spectrum from other types of communications services.

HAP Communication Environment

FIG. 1shows a diagram of an example communication system100, according to an example embodiment of the present disclosure. The example communication system100includes a platform102(e.g., a HAP) configured to operate at a specified altitude above the Earth's surface104. For instance, the platform102may operate between 17 to 22 km above the surface of the Earth. In other examples, the platform102may be replaced by any other suitable communications platforms.

The example platform102includes antennas106in addition to hardware107(e.g., receiver, switch, transmitter, modem, router, filter, amplifier, frequency translator computing device, processor, memory/buffer, etc.) to facilitate the relay of communications between user terminals108and a gateway station110. For example, the platform102may have a transponder bent-pipe design for relaying communications signals between the gateway110and the user terminals108in multiple cells. As described below in more detail, the hardware107includes processing, switching, and/or routing capability so that circuits may be switched or individual packets may be routed between different cells. The processing also enables different MODCOD modes to be selected for communication with the user terminals108and communication with the gateway station110. The communications signals transmitted to/from the platform102can be any combination of standard or proprietary waveforms. Additionally, the gateway station110can be connected to any combination of communications networks such as the Internet (e.g., external network113).

The example hardware107includes a switch and/or processor that is configured to retransmit communications received from one cell back to the same cell or another cell. For instance, a switch may be configured to receive communication data from at least one of the gateway station110and the user terminals108and determine a destination cell within a coverage area for the communication data. The switch then selects one of the plurality of antennas106corresponding to the destination cell to transmit the communication data and accordingly transmits the communication data via the selected antenna.

In other embodiments the data could be sent to other HAPS, GEO/LEO satellites, or other aircraft (e.g., the platform102aofFIG. 2). For instance, the platform102may operate within a star or hub-and-spoke network that routes communication data from the gateway station110and/or the user terminals108to the platform102a. The second platform102adetermines a destination cell within a respective different coverage area for routing the communication data. In some instances, the platform102amay transmit the communications data to yet another platform. It should be appreciated that the platform102may include a platform antenna aligned with the platform102ato establish and maintain one or more (forward and return) feeder links to facilitate the transmission of the communication data. In other embodiments, a gateway or user antenna may be used.

The example user terminal108can be any terminal capable of communicating with the platform102. The user terminal108includes an antenna, transceiver, and processor to facilitate the transmission of data with the platform102. The user terminals108may be connected to any user communications equipment or device such as a router, switch, phone or computer109. The user terminal108may also include a mobile platform such as a vehicle, ship, or aircraft. WhileFIG. 1shows one user terminal108, it should be appreciated that the platform102is configured to communicate with a plurality of user terminals within a coverage area.

The example gateway station110includes any centralized transceiver connected to the network113(e.g., the PSTN, Internet, a LAN, a virtual LAN, a private LAN, etc.). The gateway station110may include one or more base stations, antennas, transmitters, receivers, processors, etc. configured to convert data received from the network113into signals for wireless transmission to the platform102and convert data received from the platform102into signals for transmission to the network113. In some instances, the platform102may be in communication with more than one gateway station110(which may require a separate gateway antenna pointed at each station). Additionally or alternatively, the gateway station110may be in communication with more than one platform102. In these instances, the gateway station110may select which platform102is to receive the data based on, for example, a destination of the data.

The example user terminals108and the gateway station110are configured to communicate with the platform102via uplinks114downlinks116. The links114and116use spot beams provided by the platform102to cover specified cells containing the user terminal108and/or the gateway station110. It should be appreciated that a spot beam may multiplex a plurality of signals on each uplink114and each downlink116based on the amount of user terminals108and/or gateway stations110transmitting or receiving data within a cell.

As shown inFIG. 1, data is transmitted to the platform102from the user terminals108via the uplink114aand data is received from the platform102at the user terminals208via the downlink116a. Similarly, data is transmitted to the platform102from the gateway station110via the uplink114band data is received from the platform102at the gateway station110via the downlink116b. The uplink114band the downlink116bare referred to herein as the forward link (that carry forward link user data and management and control signals) between the gateway station110and the user terminals108. The uplink114aand the downlink116aare referred to herein as return links (that carry return link user data or management and control signals) between the user terminals108and the gateway station110. The downlinks116band the uplinks114btogether comprise the feeder link(s) and the downlinks116aand the uplinks114atogether comprise the user links.

The gateway station110sends communication signals to platform102via a forward feeder link comprising the uplink114b. The hardware207at the platform102demodulates and decodes the forward feeder link signals so that individual packets or time-divided portions may be routed to a buffer for a corresponding spot beam. For each spot beam buffer, the individual packets or time-divided portions are multiplexed or combined into a forward user spot beam signal, which is coded and modulated. The platform102transmits the modulated forward user spot beam signal via a forward user spot beam comprising the downlink116a.

The user terminal108sends communications signals to the platform via a return user spot beam signal included within a spot beam comprising the uplink114a. The hardware207at the platform102demodulates and decodes the return user spot beam signals so that individual packets or time-divided portions may be routed to a buffer for a link to a gateway station. For each link to a gateway station, the individual packets or time-divided portions are multiplexed or combined into a return feeder link signal, which is then coded and modulated. The platform102transmits the modulated return feeder link signal to the gateway station110via a return feeder link comprising the downlink116b.

As described in more detail below, the signals transmitted along the uplink114band the downlink116bbetween the gateway station110and the platform102are modulated/demodulated and/or coded/decoded to increase spectrum efficiency while the signals transmitted along the uplink114aand the downlink116abetween the user terminal108and the platform102are differently modulated/demodulated and/or coded/decoded to increase robustness.

The example platform102includes separate antennas106(or apertures and feeds) for each spot beam and each link or beam to a gateway station. For example, the platform102may include four port feeds for gateway stations and two port feeds for spot beams. The port feeds may include dual polarization (e.g., left hand circular polarization (“LHCP”) and right hand circular polarization (“RHCP”). In this example, the return link114ais converted to baseband, processed, and multiplexed at the platform102. The multiplexed signal is then transmitted via return link116bto the gateway station110. The user terminal108may handoff from one spot beam to another as the beams move across the Earth's surface, which is conducive to a user terminal which can transmit and receive both polarizations. Similarly the forward link114bis converted to baseband, processed, and multiplexed at the platform102. The multiplexed signal is then transmitted in a spot beam via the forward link116ato the user terminal108. A gateway antenna106on board the platform102is configured to be constantly pointed toward the gateway station110despite any changes to the platform's pitch, roll, yaw, and position. The gateway antenna106may be mechanically or electrically controlled and/or moved to remain aligned with the gateway station110.

FIG. 2shows a diagram of the example platform102ofFIG. 1routing signals from the gateway station110to three user terminals108ato108c, according to an example embodiment of the present disclosure. In this example, the gateway station110is located in cell202, user terminal108ais located in cell204, user terminal108bis located in cell206, and user terminal108cis located in cell208. The platform102provides each of the cells202to208a respective spot beam.

While this disclosure is not limited to any frequency, certain frequency spectrums have been allocated for HAP communications by regulatory bodies, as discussed above. These allocated frequencies are used in the example discussed herein. The example embodiment disclosed herein assumes the downlink116bofFIGS. 1 and 2may use a frequency band between 31.0 and 31.3 GHz and the uplink114amay use a frequency band between 27.9 and 28.2 GHz. Additionally, both the uplink114band the downlink116amay use a frequency band between 47.2 and 47.5 GHz and 47.9 and 48.2 GHz. In the United States, the allocation includes the entire band between 47.2 and 48.2 GHz. The time-division boundary between forward uplink and forward downlink may be dynamically adjusted to meet traffic demand. As shown inFIG. 3, the signals on the two links may use time division duplexing at the platform102. Time Division Duplexing is required because a frequency division duplex of the 47 GHz band would result in a low level received signal from the gateway station110being interfered with by a high level transmitted signal from the platform102towards the user terminals108. There is not enough separation in frequency to be able to implement a suitable duplex filter. As shown inFIG. 3A, in one embodiment the forward downlink from the platform102to the user terminals108uses time hopping of the entire spectrum from one beam to another, dwelling on each beam as required. The dwell time for each beam can be dynamically adjusted depending on the amount of traffic towards each beam. As shown inFIG. 3B, in another embodiment the available spectrum is divided into frequency channels so that each channel would be allocated to a different spot beam. Frequency channels could be reused if the beams are far enough apart. Some combination of frequency and time division sharing of the spectrum between spot beams is also possible. The disclosure is not restricted to this frequency plan and in the future other frequencies may become available to HAP communications.

Returning toFIGS. 1 and 2, the gateway station110transmits forward feeder link signals along the uplink114bto the platform102. The forward feeder link signals may include, for example, a 16 phase-shift keying (“PSK”) modulation scheme and 3/4 forward error correction (“FEC”) mode. The hardware107at the platform102separates the individual data packets or time-portions within the forward feeder link signals. The separated data packets or time-portions are then switched to the appropriate spot beam for the respective cells204to208based on a destination (e.g., the user terminal108). The platform102transmits forward user spot beam signals via the respective downlinks116a1,116a2, and116a3to the cells204to208. The forward user spot beam signals may use, for example, a Quadrature-PSK (“QPSK”) modulation scheme and 1/2 FEC mode, which is more robust to thermal noise than the 16-PSK modulation scheme proposed for the uplink from the gateway station110to the platform102.

The example gateway station110uses the same spectrum along the uplink114bas each of the three spot beams along the downlinks116a. However, the gateway station110can transmit three times the data in the same time because the 16 PSK modulation 3/4 FEC mode is more spectrally efficient. Specifically, the uplink114bhas a spectral efficiency of 2.7 (bits/second)/Hertz (“b/s/Hz”) while the downlinks116aeach have a spectral efficiency of 0.9 b/s/Hz. The tradeoff is that the 16 PSK modulation 3/4 FEC mode requires 12 dB of Es/No(energy per bit to noise power spectral density ratio) while the QPSK 1/2 FEC mode requires an Es/Noof only 1.5 dB. However, this tradeoff is acceptable because only the one gateway station110needs to be deployed to serve the traffic for the three spot beams corresponding to cells204to208. Further, the gateway station110may compensate for the difference signal-to-noise ratio requirement of about 10.5 dB with a larger antenna or power amplifier. It should be appreciated that a larger antenna or power amplifier cannot be added to the user terminals108(which are constrained by portability or size) to compensate for higher signal-to-noise ration losses, which is why a more robust MODCOD mode is used for those signals.

As discussed, the example embodiment assumes the uplink214bofFIGS. 1 and 2may use a frequency band between 47.2 and 47.5 GHz, the downlink216bmay use a frequency band between 47.9 and 48.2 GHz, the uplink214amay use a frequency band between 31.0 and 31.3 GHz and the downlink216amay use a frequency band between 27.9 and 28.2 GHz. Another possible embodiment assumes the uplink214bmay use a frequency band between 31.0 and 31.3 GHz and the downlink216amay use a frequency band between 27.9 and 28.2 GHz and both the uplink214band the downlink214bmay use a frequency band between 47.2 and 47.5 GHz and 47.9 and 48.2 GHz. The advantage of the first embodiment is that rain attenuation on the user links are easier to close with higher data rates. The advantage of the second embodiment is that more spectrum is available for the user data links. The disclosure is not restricted to either of these frequency plans and in the future other frequencies may become available to HAP communications.

In some embodiments, the antennas106of the example platform102are configured to have different sizes (e.g., different size apertures), as disclosed in U.S. patent application Ser. No. 14/510,790, filed Mar. 5, 2015, the entirety of which is incorporated herein by reference. The different size antennas106are used to create cells of substantially the same size in order to achieve a constant surface spectral density throughout the coverage area. The differently sized antennas106provide corresponding different size beam widths, which compensates for the angle at which Earth subtends at 17 km to 22 km resulting in substantially similarly sized cells. Such a configuration of differently sized antennas maintains a consistent QoS or available bandwidth throughout the cells of a coverage area so that a user does not experience service degradation when the user terminal108moves between cells and/or the platform102moves relative to a user terminal. To maintain consistent cell areas, antennas covering the outer cells are relatively larger (and consequently have more gain) than those antennas coving the interior cells. The increased gain for the antennas covering the outer cells compensates, in part, for the increased path loss from the greater distance to reach those outer cells. Further, the consistent cell sizes means that link margins between user terminals108and the platform102are similar, which means that antennas on the user terminals can be the same regardless of the location of the user terminal within the coverage area.

Returning toFIG. 1, the example communication system100also includes a system configuration manager120, which may comprise any processor or system tasked with designing, developing, and/or maintaining the antennas106, hardware107, and other features of the platform102. The system configuration manager120may determine a coverage area to be serviced by the platform102in addition to a number of antennas needed to provide acceptable bandwidth to user terminals and the size of the antennas to maintain spectral density uniformity among the cells. The system configuration manager120may also select the type of antenna106including, for example, a reflector, array, open ended waveguide, dipole, monopole, horn, etc. The system configuration manager120may select the antenna type based on, for example, a desired spot beam size, bandwidth, gain, elevation angle relative to the surface, etc. The system configuration manager120may also select the size of the aperture of the antenna106based on the desired spot beam size, bandwidth, gain, elevation angle, etc. In some instances, the system configuration manager120may include a control link to configure the platform102based on a new set of coverage area and QoS parameters. Depending on the capability of the platform102, such parameters may include new frequency assignments, new spot beam forming coefficients or new routing tables.

The example system configuration manager120may also determine the MODCOD modes for the platform102. For instance, the manager120may determine spectrally efficient MODCOD modes for the links114band116bcommunicatively coupling to the gateway station110to the platform102. The manager120may also determine more robust MODCOD modes for user links114aand116a. Alternatively, the MODCOD modes used on these links may be selected dynamically (or varied) to match current link conditions as these change by a processor on-board the platform102or in each terminal. The configuration manager120may provision the hardware107on the platform102for the range of MODCOD modes to be used on each of these links. Provisioning may include, for example, programming one or more processors, tuning/configuring/selecting appropriate amplifiers, analog-to-digital converters (“ADC”), demodulators/modulators, coders/decoders, buffers, down-converters (“DCs or DoCos”), and up-converters (“UCs or UpCos”) compatible for each MODCOD mode and/or frequency.

In addition to configuring the platform102, the example system configuration manager120may also service and/or maintain the platform102. For example, the system configuration manager120may transmit software updates while the platform102is operational in the sky. The system configuration manager120may also instruct the platform102to move to a new geographical location. The system configuration manager120may further instruct the platform102to return to the ground for maintenance, upgrades, service, antenna reconfiguration, etc. The system configuration manager120may communicate with the platform102via the gateway110and/or a proprietary/private communication link. In some instances, the platform102may provide diagnostic and status information to the system configuration manager120via the proprietary/private communication link and/or through the gateway110multiplexed with communications traffic.

Modulation and Coding Embodiments

The example hardware107of the platform102is configured to slice or partition signals from the user terminals108and the gateway station110based on a format of the signals. For example, a data stream or signal provided in the forward feeder link114bfrom the gateway station110may be time-sliced by the hardware107within the platform102based on a number of cells or spot beams. For instance, gateway station110in the embodiment ofFIG. 2may partition a signal into three portions, one for each of the cells204,206, and208. The partition may be at fixed time boundaries such that each cell is allocated 1/3 of the bandwidth. The hardware107at the platform102is configured to partition the signal at the fixed time boundaries and route or switch each partitioned portion to the appropriate cell204to208.

Alternatively, the data stream or signal from the gateway station110may be configured such that the partition for each of the cells204to208is dynamic. Such a configuration enables a larger portion to be allocated for a cell with higher bandwidth needs. A control signal or codeblock may be provided by the gateway station110to the platform102indicative of the timing for the portions. The control signal (or codeblock) may be provided in-band or out-of-band.

In yet another embodiment, the data stream or signal from the gateway station110may include individual data packets, which are configured to be processed individually by the platform102. For instance, hardware107(including hardware controlled by software or machine readable instructions) may be configured to determine a cell identifier within a header of the packet, which is used for routing the packet to the appropriate cell204to208. The hardware107may include, for example, a switch or router implemented at the media access control (“MAC”) layer or the network layer. This MAC address may indicate the appropriate user terminal and/or the spot beam in which the user terminal resides.

The example platform102is also configured to combine portions or signals or data packets into a signal or data stream for the return feeder link116bto the gateway station110. For instance, the hardware107at the platform102may be configured to determine which gateway station110a signal from a user terminal108is to be routed using, for example, a time-based approach or packet-based approach. The hardware107combines packets or signal portions from the different cells204to208that all have a destination (or intermediate destination) of the gateway station110.

It should be appreciated that the time-division duplexing (“TDD”) and packet routing embodiments discussed above enables incremental additions of gateway stations without any impact to the user terminals. For example, gateway stations may be added to the system as bandwidth demand increases without affecting the timing scheme for routing or switching signals among the cells within a coverage area. The TDD and packet routing methods are conducive to the modulation-demodulation performed by the platform102. The time division duplex scheme of sharing the total bandwidth between the forward uplink signals on links114band the forward downlink signals on links116ais independent of the propagation times and may be implemented on the longer paths associated with GEO and/or LEO satellites if the spectrum allocation is similarly constrained

FIG. 3shows a timing diagram300of signals transmitted to and from the platform102ofFIGS. 1 and 2, according to an example embodiment of the present disclosure. The example timing diagram300includes transmission pattern302,304,306, and308for signals transmitted from the gateway station110to the user terminal108. Each of the transmission patterns302to308have the same frame period312having a fixed duration. The frame period duration may be, for example, 100 ms. The shaded areas within each of the patterns302to308designate active times of the frame period312. The clear or white areas within each of the patterns302to308designate inactive times of the frame period312for the associated link. The shaded areas may have a duration of 1-α ms and the clear areas may have a duration of α ms on the link114b. The time reference may be at the gateway station110or the platform102. Additionally, the platform102may actively or passively synchronize the transmission patterns with the user terminals108and the gateway station110.

As shown inFIG. 3, the gateway station110transmits a signal or data stream during time period314and is inactive during time period316. The platform102receives the transmitted signal or data stream during time period318, which has the same duration as the time period316. It should be noted that the transmission pattern304has a time offset from the transmission period302due to signal propagation delays. In other words, the signal received at the platform102has a time offset from the signal transmitted by the gateway station110due to signal propagation delays. It should be noted that during the time the platform102is receiving the signal from the gateway station110, the platform102is not transmitting signals to the user terminal108. This configuration eliminates interference at the platform102from the forward downlinks116ainto the forward uplinks114beven though they use the same frequency spectrum.

The platform102accordingly transmits during time period320at least a portion of the signal received during time period318. During the time period320the platform102does not receive signals from the gateway station110. The user terminal108, which has a time offset from the platform102due to signal propagation delays, receives the signal during time period322. As illustrated inFIG. 3, regardless of propagation time, the signals received from the gateway station110and the signals transmitted towards the user terminals108using the allocated spectrum between 47.2 and 48.2 GHz cannot overlap in time at the platform102.

In an example embodiment, the value of α, which is the ratio of i) the time duration for transmission from the platform102to the user terminals108in relation to ii) the frame time, can be determined by the following equation:

In the above equation, N is the number of gateway stations, n is the number of cells or spot beams, r is the frequency reuse factor, ξfis the spectral efficiency of the signal transmitted from the gateway station110to the platform102on the link114b, and ξuis the spectral efficiency of the signal transmitted from the user terminal108to the platform102on the link116a.

In an example embodiment, 600 MHz of spectrum between 31.0 and 31.3 GHz (with 2× polarization reuse) is allocated to the user terminals108for the return uplink114a. The user terminals108time share with the gateway station1101200 MHz of spectrum at the 47 GHz frequency (using the 600 MHz international allocation with 2× polarization reuse) in the forward downlink116a. The gateway station110is configured to use 600 MHz of spectrum between 27.9 and 28.2 GHz (with 2× polarization reuse) for the downlink116b. The gateway station110time shares with the user terminals108the 1200 MHz of spectrum at the 47 GHz frequency in the forward uplink114b. The time sharing is accomplished using the configuration described in conjunction withFIG. 3and using the forward downlink multiplex shown in eitherFIG. 3AorFIG. 3B.

In this embodiment, the coverage area of the platform102is 36,000 km2, assuming a 10 degree elevation angle limitation from a perspective of the user terminal108at the edge of the coverage area and a 20 km elevation of the platform102. The 600 MHz allocated for the user terminals108is spread over the 36,000 km2area producing a spectral density of 16.7 kHz per km2. The spectral density may be increased by increasing the number of spot beams or cells. For instance, using 19 cells and a spectral reuse of 4 can increase the capacity by approximately a factor of four.

FIGS. 4 to 7show diagrams of respective tables400,500,600, and700illustrating bandwidth information in relation to values for transmission duration α for the example platform102in communication with one, two, three, and four gateways stations, according to an example embodiment of the present disclosure. The bandwidth information (units in MHz) is based on the above example embodiment and includes total bandwidth capacity for the user terminals108, bandwidth capacity for each link with a gateway station110, bandwidth per each cell or spot beam, and bandwidth per km2. As illustrated, as the number of gateway stations increases, the total bandwidth for the spot beams increases in conjunction with bandwidth per cell and bandwidth per km2. Additionally, the transmission time duration 1-α decreases in line with the bandwidth for each feeder link to a gateway station. In other words, adding gateways stations reduces the amount of bandwidth any one gateway station has to provide, thereby reducing the time needed for transmission.

The example tables400to700show how the bandwidth information and α duration changes as different MODCOD modes are used for the feeder link between the gateway station110and the platform102. In the example shown in table400ofFIG. 4, both the gateway station110and the user terminal108are configured to transmit with a (or using a) MODCOD mode including QPSK modulation and 1/2 FEC. This MODCOD mode is relatively more robust and selected more for the user terminals. In the example shown in the table500ofFIG. 5, the MODCOD mode for the feeder link with the gateway station110is made more spectrally efficient compared to the example inFIG. 4while the MODCOD mode for the user terminals remains unchanged. The MODCOD mode for the gateway station110shown inFIG. 5is three times more spectrally efficient than the MODCOD mode ofFIG. 4. As shown inFIG. 5, the portion of the 1200 MHz forward signal allocated for the user terminals108more than doubles compared to the example ofFIG. 4. For a single gateway station, the available bandwidth increases from 27 to 761 kHz/km2. It should be noted that because of the way the feeder links share bandwidth with the user links the capacity gains become less as more gateway stations are added. For instance, four gateway stations support less than twice the capacity in table500compared to table400.

The example table600shows bandwidth information and α for a MODCOD mode that includes 64PSK modulation and 4/5 FEC. The example table700shows bandwidth information and α for a MODCOD mode that includes 256PSK modulation and 13/18 FEC. These tables600and700shows that as spectral efficiency is further increased on the feeder link between the gateway station110and the platform102, the throughput of the entire system in also increased. It should be appreciated the examples shown in tables400to700are non-limiting and that virtually any spectrally efficient MODCOD mode (or set of MODCOD modes) may be used for the feeder link.

Platform Processor Embodiment

As discussed above, to use different modulation schemes and coding schemes on the feeder links and the user links, the example platform102includes hardware107.FIGS. 8 to 10show a diagram of at least a portion of the hardware107, according to an example embodiment of the present disclosure. The example shown inFIG. 8illustrates processing for receiving only one 47 GHz band. Other examples may include processing for receiving the 47.9 to 48.2 GHz band, such as the example shown inFIG. 9. It should be appreciated that the example shown inFIG. 8is non-limiting and the hardware107may include additional, fewer, or different components.

In the illustrated example ofFIG. 8, a forward feeder link signal802is transmitted from the gateway station110to the platform102during the (1-α) duration. The signal802may be provided by the uplink114bofFIGS. 1 and 2. A feed804(e.g., the antenna106) at the platform102routes the received signal802to one of the receivers806based on a polarization of the signal. As shown inFIG. 9, the receivers806may include low-noise amplifiers (“LNAs”). A baseband processor808is configured to demodulate, decode, and de-multiplex the signal802during the time period having the (1-α) duration. The baseband processor808also switches or routes the de-multiplexed individual packets or signal portions to the appropriate buffer of a cell or spot beam signal. As discussed above, the routing or switching may be time-based or address-based. The baseband processor808then codes and modulates the buffered packets or signal portions into a spot beam signal810for transmission during the time period having the a transmission duration. Transmission into the appropriate spot beam (e.g., spot beam19) includes sending the signal810to transmitter812and feed814(including the antenna106).

The example hardware107also includes receivers818, return baseband processor820, and transmitters822for processing return signals originating at the user terminals108. For example, the feeds814and816are configured to receive return user spot beam signals810and824having a frequency in the 31.0 to 31.3 GHz band.FIG. 8shows the hardware107for receiving right and left polarized signals in the 31.15 to 31.30 GHz band. The receivers818amplify the signal824for processing by the return baseband processor820. As discussed above, processing includes demodulating, decoding, and de-multiplexing. The processing also includes routing or switching individual packets or signal portions to the appropriate gateway station buffer and multiplexing the packets or signal portions within each buffer into a return feeder link signal826. The processor820codes and modulates the signal826for transmission, via transmitter822and feed804, to the gateway station110.

FIG. 9shows a diagram of a front-end of the forward baseband processor808aofFIG. 8, according to an example embodiment of the present disclosure. In this illustrated example, the baseband processor808areceives signals transmitted by the gateway110within the two 47 GHz bands using both polarizations. In some instances, it may be possible to receive both bands using one amplifier806per polarization.

As shown inFIG. 9, the example front-end of the baseband processor808aincludes a down converter (“DoCo”)902configured to down-convert the received forward feeder link signal802into a baseband (“BB”) signal for locale transmission and processing. An ADC904converts the baseband analog signal into a digital signal, which is then demodulated via demodulator906. In this illustrated example, the ADC904has a 272 Msps sample rate based on the 300 MHz bandwidth forward feeder link signal802. A decoder908is configured to decode the demodulated signal. The embodiment ofFIG. 9is configured for a modulation of 256 PSK and a 0.55 FEC. In this example, the decoded signal is provided at a rate of 784 Mb/s, which is equal to the 272 Msps sample rate multiplied by 0.55 FEC and a 5.25 decode factor.

FIG. 10shows a diagram of a back-end of the forward baseband processor808bofFIG. 8, according to an example embodiment of the present disclosure. The signal having a rate of 784 Mb/s transmitted from the front-end of the baseband processor808ainFIG. 9is received at respective switches1002inFIG. 10. For clarity, only two of the switches1002are shown. The example switches1002are time-based switches configured to connect the decoded forward feeder link signal802to a downlink user spot beam. The example illustrated inFIG. 10shows each of the switches1002being connected to two spot beam downlink feeds. However, it should be appreciated that each switch may be connected to each spot beam downlink feed (or feed to another platform).

The example switches1002are configured to switch the decoded signal802based on a fixed or variable time plan. For instance, a time plan may specify that the switch1002is to route a first portion of the signal802to buffer1004aand a second subsequent portion of the signal802to buffer1004b. In instances where the time division is variable between the signal portions, the switch1002may be instructed using in-band and/or out-of-bands received from, for example, the gateway110and/or the system configuration manager120.

The buffers1002within the example back-end baseband processor808bare configured to queue portions of the signal802destined for the same spot beam, thereby forming the forward spot beam signal810. The buffer1004may be configured to store portions of the signal802for an entire uplink transmission having a duration of (1-α) if the decoder908is capable of operating in real time. Otherwise, the buffer1004may be configured to store less data at the expense of also needing a buffer in the front-end of the baseband processor808a.

The example back-end of the baseband processor808bincludes an encoder1006to encode the forward spot beam signal810based on a specified FEC. The baseband processor808may include a separate encoder for each supported MODCOD mode. The processor808balso includes a modulator1008to modulate the forward spot beam signal810based on a specified modulation scheme. The processor808bfurther includes an up-converter configured to up-convert a baseband format/frequency of the forward spot beam signal810into a desired frequency (e.g., the 47.2 to 47.5 GHz band) for HAP or satellite. In some instances, the up-converter and the modulator may be the same component or included within the same packaging. The processor808may include a separate modulator for each supported MODCOD mode. The selection of the downlink encoder1006and/or modulator1008may be made by the gateway station110, the user terminals108, and/or the processor808either statically or based on propagation conditions. For example, detection of heavy rain in a cell may cause an encoder and modulator to be selected that supports very robust communications. In some instances, the baseband processor808may use DVB-S2x Adaptive Coding and Modulation to select which modulator/demodulator and coder(encoder)/decoder is used.

Returning toFIG. 10, the transmitter812is configured amplify the forward spot beam signal810for transmission via one of the antennas106via a spot beam. As shown in FIG.10, the transmitter812may include a traveling-wave tube amplifier (“TWTA”). In other embodiments, the transmitter812may include any type of amplifier.

It should be appreciated that the processor808displayed inFIGS. 9 and 10may also be used for the return baseband processor820ofFIG. 8. The only differences may be the frequencies of the signals transmitted/received and the routing for the switch1002. For example, the switch1002in the return baseband processor820may route portions of signals among one or more gateway stations110and/or one or more downlink feeds having a certain polarization and/or frequency band for the gateway station110(or another platform in a mesh or hub-and-spoke system).

Additional Platform Processor Embodiments

FIG. 11shows a diagram of an alternative embodiment of the back-end baseband processor808bofFIG. 10, according to an example embodiment of the present disclosure. In this example, the baseband processor808is configured to process individual data packets instead of time-dividing a signal. In this example, the switch1002of the baseband processor808is replaced with a packet de-multiplexer1102. As illustrated, the de-multiplexer1102for each forward feeder link signal is connected to a bus1104to enable the routing data packets or codeblocks to any spot beam. An uplink codeblock, such as uplink codeblock1200discussed in conjunction withFIG. 12, includes data with a high rate FEC code and/or a high modulation, such as 256 Quadrature amplitude modulation (“QAM”). For instance, the coding may follow the DVB-S2 Part II standard, which specifies the configuration of long and short codeblocks. It should be appreciated that shorter codeblocks sacrifice some performance for reduced complexity within the decoder908. Alternatively, some of terrestrial cellular LTE modulation and coding may be used.

As illustrated inFIG. 12, the uplink codeblock1200(e.g., forward feeder link signal) includes a sequence of downlink codeblocks1204(e.g., data packets), each preceded by a downlink codeblock format control header1206. The header1206identifies the downstream data stream, spot beam, or user terminal for the following codeblock1204in addition to the modulation and coding (e.g., MODCOD) mode to be used for the codeblock. It should be appreciated that the gateway station110knows the instantaneous data rate for each of the spot beams it serves and can accordingly insert ‘dummy’ data as needed to maintain a steady flow rate for each spot beam to avoid large dynamic buffers on the platform102. The on-board queue or buffer for each downlink may be limited to two codeblocks. As illustrated inFIG. 12, the de-multiplexer1102ofFIG. 11is configured to separate the downlink codeblocks1204within the codeblock1200for each spot beam. For instance, the codeblocks1204for spot beam1are transmitted to the buffer1004ainFIG. 11. The coding/modulation/up-conversion/and transmission of the buffered codeblocks1204as the forward spot beam signal810is similar to the example discussed in conjunction withFIG. 10.

FIGS. 13 and 14show diagrams of alternative embodiments of a front-end for the return baseband processor820a, according to an example embodiment of the present disclosure. In particular,FIG. 13shows an embodiment where 300 MHz of dual polarization bandwidth is received from the user terminals108in a plurality of cells or spot beams. In this embodiment, a demodulator group1302includes a plurality of selectable demodulators and a decoder group1304includes a plurality of decoders. As discussed above, such a configuration enables the modulation and/or coding of the signals to be changed at the gateway station110and/or the user terminals108based on conditions. For instance, a first demodulator supports QPSK modulation, a second demodulator supports 16 PSK modulation, a third demodulator supports 64 PSK modulation, and a fourth demodulator supports 256 PSK modulation.

FIG. 14shows an embodiment where the demodulator group1302and the decoder group1304are replaced by an in-route demodulator and decoder (“IDM”)1402. In this embodiment, the IDM1402enables only about 1/2 the bandwidth being needed for the return signal to have roughly the same performance as the example shown inFIG. 13. This configuration enables only one polarization to be used for the return signals, meaning the transmission and reception of the return signals at the platform102are not always crossed.

FIGS. 15 and 16show diagrams of alternative embodiments of the back-end of the return baseband processor820aofFIG. 8, according to an example embodiment of the present disclosure. In this example, de-multiplexers (not shown) are configured to route data packets or codewords1204via the bus1104to the appropriate buffer1004. In the alternative example ofFIG. 15, the bus1104is communicatively coupled to buffers for additional gateway stations110(or platforms). Such a configuration provides additional capacity beyond the limits of a single gateway station110.FIG. 15also shows that a set of encoders1502may be used to support different coding modes. The buffer1004, the set of encoders1502, the modulator/up-converter1008, and the transmitter812designated for the second gateway station110operate as discussed in conjunction withFIGS. 8 and 10.FIG. 16shows an example where the encoder set1502and the modulator/up-converter1008ofFIG. 15are combined within a single encoder/modulator/up-converter1602.

It should be appreciated that the baseband processors808and820ofFIGS. 8 to 16may be adjusted to accommodate different reuse arrangements for the spot beams. For example, the configuration of the baseband processors808and820may enable 19 cells to be further divided into 37 cells to provide additional capacity. In such a configuration, the baseband processors808and820may include switches or routers to reuse the modulators/demodulators, buffers, and/or encoders/decoders for multiple spot beams. Alternatively, the baseband processors808and820may include additional modulators/demodulators, buffers, and/or encoders/decoders to expand capacity while the platform is in use.

Flowchart of the Example Process

FIG. 17illustrates a flow diagram showing an example procedure1700to configure the platform102ofFIGS. 1 and 2with different MODCOD modes, according to an example embodiment of the present disclosure. Although the procedure1700is described with reference to the flow diagram illustrated inFIG. 17, it should be appreciated that many other methods of performing the steps associated with the procedure1700may be used. For example, the order of many of the blocks may be changed, certain blocks may be combined with other blocks, and many of the blocks described are optional. Further, the actions described in procedure1700may be performed among multiple devices.

The example procedure1700ofFIG. 17operates on, for example, the system configuration manager120and/or the platform102ofFIG. 1. The procedure1700begins when the system configuration manager120receives a request1701to provision a HAP (e.g., the platform102ofFIG. 1) for a specified coverage area. The request1701may include, for example a latitude (e.g., geographic location) at which the proposed HAP will operate. The request1701may also include a season of the year in which the HAP will operate. Responsive to the request1701, the system configuration manager120determines an altitude at which the HAP will operate in addition to a minimum elevation angle, a coverage area, bandwidth requirements and/or QoS requirements/parameters (block1702). The system configuration manager120also determines a number of antennas, a beam width, elevation angle, gain, and antenna aperture for the platform (as described further in U.S. patent application Ser. No. 14/510,790, filed Mar. 5, 2015).

The system configuration manager120further determines MODCOD modes that are spectrally efficient for the links114band116bbetween one or more gateway stations110and the platform102(block1704). Moreover, the system configuration manager120determines MODCOD modes that are robust for the links114aand116abetween one or more user terminals108and the platform102(block1706). The determination of the MODCOD modes may take into any of the design or configurations of the processors808and820discussed in conjunction withFIGS. 8 to 16. The system configuration manager120may then provision the hardware107on the platform102to operate in conjunction with the MODCOD modes (blocks1708and1710).

The example system configuration manager120then provisions the platform102into service (block1712). While the platform102is in service, checks may be made by the system configuration manager120, the gateway station110, and/or the user terminals108to determine if signal propagation conditions have changed (e.g., heavy rain in a cell). Conditioned upon determining conditions have changed, the system configuration manager120, the gateway station110, and/or the user terminals108determine how the MODCOD modes should be changed (blocks1704and1706). The system configuration manager120, the gateway station110, and/or the user terminals108may then instruct the platform102to adjust the processors808and/or820to compensate for the change or variation to the MODCOD mode. It should be appreciated that the MODCOD mode for only one user spot beam may change, with the corresponding changes being made in the platform102while the MODCOD mode for the other spot beams remains the same. The platform102continues to operate (block1716) until conditions change again or until an instruction is received to land or end service.

CONCLUSION

It will be appreciated that all of the disclosed methods and procedures described herein can be implemented using one or more computer programs or components. These components may be provided as a series of computer instructions on any computer-readable medium, including RAM, ROM, flash memory, magnetic or optical disks, optical memory, or other storage media. The instructions may be configured to be executed by a processor, which when executing the series of computer instructions performs or facilitates the performance of all or part of the disclosed methods and procedures.

It should also be understood that the example telecommunications platform disclosed herein may be an element of a larger system. Examples of larger system include relays between platforms, relays between platforms and GEO satellites, relays between platforms to gateways shared by those platforms, relays between gateways and GEO satellites.