A method and apparatus for handling communication between a spacecraft operating within an orbit environment and a terrestrial electrical communication device

Abstract

A multiple access base station is provided for handling communications between spacecraft operating within an orbital environment and ground telecommunications devices. A multiple access transceiver handles communications with a mobile station in environments beyond the mobile station's design assumptions, without necessarily requiring modification of the mobile station. One such environment is in Earth orbit. The multiple access transceiver is adapted to block communications with the mobile station during environments beyond the mobile station's design assumptions, such as greater distances, relative motion, and / or other conditions typically encountered when the terrestrial transceiver's functions are performed by an orbital transceiver. The orbital transceiver includes a data analyzer that analyzes frame data structures, a signal timing module that adjusts timing based on orbit-to-ground propagation delays, a frequency shifter, and a programmable radio capable of communicating from Earth orbit using a multiple access protocol.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for handling communication between a spacecraft and a terrestrial electrical communication device, and more particularly, to communication using the characteristics and facilities of a terrestrial electrical communication device typically used for terrestrial electrical communication.

[0002] Cross-reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 62 / 465,945, filed on Mar. 2, 2017, entitled "Method for Low-Cost and Low-Complexity Inter-Satellite Link Communications within a Satellite Constellation Network for Near Real-Time, Continuous, and Global Connectivity", and is a non-provisional application thereof.

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 490,298, filed on Apr. 26, 2017, entitled "Method for Communications Between Base Stations Operating in an Orbital Environment and Ground-Based Telecommunications Devices", and is a non-provisional application thereof.

[0004] The entire disclosure of the applications cited above is hereby incorporated by reference into this specification as if fully set forth herein for all purposes.

Background Art

[0005] Mobile communication involves signals transmitted between a mobile station (MS) and a transceiver that can provide an interface for the MS to communicate with other network resources such as a telecommunications network, the Internet, etc., in order to carry voice and data communications, and in some cases location discovery features as well. The transceiver can be a component within a base transceiver station (BTS) that handles traffic from multiple transceivers. The BTS may also include an antenna and encryption / decryption elements. The antenna can be a selective antenna, and different MSs at different locations can communicate with their respective transceivers via different antennas of the BTS. The BTS can have wired, wireless, and / or optical channels for communicating with those other network resources. The BTS can support one or more transceivers, and a given base station for supporting mobile communication can have a base station controller (BSC) that controls one or more BTSs of that base station.

[0006] Examples of mobile stations include mobile phones, cellular phones, smart phones, and other devices equipped to communicate with a particular BTS. In this specification, the mobile station is referred to by that name, but it should be understood that the operation, function, or characteristics of a mobile station can also be those of a station that is effectively or functionally a mobile station but is not currently mobile. In some examples, a mobile station can be considered in place of a portable station that can move from place to place but is stationary during operation, such as a laptop computer with several connected peripheral devices and a cellular connection, or a mobile station can be stationary, such as a cellular device embedded within an installed home security system. All that is required is that the mobile station be able to communicate or be configured to communicate using the mobile communication infrastructure.

[0007] The BTS can be controlled by the parent BSC via the base station control function (BCF). Each of these elements is implemented using hardware and / or software and may include network management and maintenance functions, but the base station can be described as having one or more transceivers that communicate with mobile stations according to an agreed protocol. This can be by configuring, adapting, or programming the BTS to operate according to the agreed protocol of the BTS, and by configuring, adapting, or programming the MS to operate according to the agreed protocol of the MS. The protocol can include details on how to send data between the transceiver and the MS, how to handle errors, how to handle encryption, and how to send control instructions and status data between the BTS and the MS. For example, part of the protocol can include the interaction where the MS contacts the BTS and the BTS indicates to the MS the timing, carrier frequency, and other protocol options used by the MS. This interaction can include carrying voice data, carrying text data, carrying other data, providing intracell handover and other tasks.

[0008] For simplicity of explanation, in many examples in this specification, the communication is described as being between the BTS and the MS for interaction with one MS, but it should be understood that the interaction can be in the corresponding paths in the other direction from the BTS to the transceiver, radio circuit, antenna, MS antenna, MS radio circuit, software / hardware within the MS, and from the MS to the BTS. Thus, in some examples where the BTS is communicating with the MS, the communication is via the transceiver, and this example ignores descriptions of other transceivers that the BTS may control.

[0009] Examples of protocols that the BTS can use include GSM (registered trademark) (Global System for Mobile Communication: Global System for Mobile Communication, a trademark of the GSM Association) 2G+ protocols including Gaussian minimum-shift keying (GMSK), and EDGE protocols including GMSK and 8-PSK keying. The BTS can handle multiple transceivers that use multiple sets of carrier frequencies within the spectral bands of the radio spectrum allowed by the protocol. Thus, if the spectral band is logically divided into carrier frequency spectra, the transceiver can use one (or more) of those carrier frequencies to communicate with the MS using a channel. The protocol can identify that for a given channel, there are uplink sub-channels and downlink sub-channels, and in some cases, the carrier frequencies are separated from each other. In some cases, the uplink sub-channels have carrier frequencies adjacent to the carrier frequencies of the downlink sub-channels. In some cases, all uplink sub-channels are within one spectral band and all downlink sub-channels are within another spectral band. For simplicity of explanation, a channel may be described as having an uplink portion and a downlink portion and being one channel even if those portions are widely separated within the carrier frequency.

[0010] Some BTSs may provide frequency hopping, in which case the transceiver and the mobile station together quickly jump from carrier frequency to carrier frequency to improve the overall performance of the BTS. The protocol can specify the hopping sequence to be used.

[0011] In the GSM protocol, the communication between the transceiver and the MS is accompanied by frames, and each frame has up to 8 time slots. With 8 time slots, the transceiver can send frames directed at up to 8 MSs, and each MS is assigned a unique time slot within the frame by the BTS of the transceiver. The MSs can send their transmissions within their allotted time slots, and since each MS communicating with the transceiver knows which time slot to use, similarly positioned MSs can communicate back to the transceiver within their allotted time slots. The transceiver does not use all 8 time slots.

[0012] Signaling channels such as the Common Control Channel (CCCH) of the GSM protocol can be used to convey to the MSs their assignments for time slots and carrier frequencies. For example, some common control channels are used for paging (e.g., creation of PCH requests from the BTS to the MS), access authorization (e.g., AGCH from the BTS to the MS), and cell broadcast (e.g., CBCH from the BTS to the MS), and for creating access requests (e.g., creation of RACH requests from the MS to the BTS). The AGCH (Access Grant Channel) is used to authorize time slot assignment / carrier assignment. The Broadcast Control Channel (BCCH) of another channel may or may not be used to send information such as the Location Area Identity (LAI), a list of neighboring cells to be monitored by the MS, a list of frequencies used within the cell, the cell identifier, a power control indicator, whether DTX is permitted, and access control (i.e., emergency calls, call restrictions, etc.) to the MS.

[0013] Examples of BTSs include cellular phone towers, macrocell transceivers, femtocell transceivers, picocells (which may have only one transceiver), etc. The BTS will communicate wirelessly with the MS. Some BTSs have a backhaul (the interface between the BTS and other network resources) that is wired to, for example, a cellular phone tower, while some may have a wireless backhaul such as a microwave point-to-point bi-directional communication channel. Thus, the BTS can be any of several different types of electrical devices that receive data streams from the MS, process them, and / or transfer them to other network resources, and receive data streams from other network resources, process them, and / or transfer them to the MS via the BTS-MS link(s). In this sense, the BTS acts as an access point for the MS, enabling the MS to access network resources such as telecommunications networks, the Internet, private networks, etc. Access can be used to route voice calls, other calls, texting, data transfer, video, etc.

[0014] The telecommunications network behind the BTS may include a network and switching subsystem that determines how to route data to the appropriate BTS and how to route data received from the BTS. The telecommunications network may also have circuit connections and packet-based Internet connections, as well as infrastructure for handling network maintenance support. In any case, the BTS can be configured to use some protocols with the MS and other protocols with the backhaul.

[0015] The protocol for communication between the MS and the BTS is such that they are standardized, and as a result, it is assumed that any standard MS can communicate with any BTS, provided that the range requirements are met and the membership requirements are satisfied (e.g., the MS identifies itself to the BTS in such a way that the BTS or the service used by the BTS determines whether the BTS or the service used by the BTS is a member of a group for which the MS is authorized, or alternatively, whether the MS is authorized to use the service provided by the BTS). Examples of some protocols include the GSM protocol, which is also sometimes referred to as the 2G (i.e., second-generation) network protocol. Other examples include GPRS (General Packet Radio Service), EDGE (Enhanced Data rates for GSM Evolution, or EGPRS), the 3G (third-generation) UMTS standard developed by the 3GPP body, or the fourth-generation (4G) LTE extended protocol.

[0016] These protocols have rules for spectrum band usage, timing, coding, and conflict resolution. Since the BTS may have to communicate with many MSs simultaneously, the available wireless communication paths are divided according to the protocol. A given protocol may have available wireless communication paths divided by frequency, time, code, or two or more of them. This allows multiple users to share the same wireless communication path.

[0017] For example, in Time Division Multiple Access (TDMA), the BTS and multiple MSs agree to divide a period into time slots (or "burst periods"). If there is a possibility that a first MS may interfere with a second MS, the first MS is allocated a first time slot, and the second MS is allocated a different time slot among the available time slots. Since different MSs use different time slots (and all such MSs agree that the timing is sufficiently appropriate), the MSs can share a common carrier frequency, and their respective transmissions do not interfere. An example is that there are eight time slots of 576.92 μs (microsecond) each for each frame. Thus, an MS allocated to the first time slot may transmit some bits during the first time slot, stop the transmission at or before the end of that time slot, maintain silence, and then continue the transmission as needed during the first time slot of the next period. A similar allocation occurs to determine when an MS listens to something from the BTS (and to determine when the BTS starts transmitting its data).

[0018] Therefore, using a single carrier frequency, each transceiver of the BTS can communicate with up to eight MSs. The communications to those MSs are grouped into TDMA frames and transmitted on the downlink channel using that carrier frequency channel. The timing is such that each of those MSs can communicate with the BTS on the uplink channel using that carrier frequency channel within their respective time slots. This is called a "TDMA frame". The data rate across all eight MSs using that carrier frequency is 270.833 kilobits / second (kbit / s), and the TDMA frame duration is 4.615 milliseconds (ms) in either direction.

[0019] Frequency Division Multiple Access (FDMA) is another way of dividing and allocating available wireless communication paths. In FDMA, the available or allocated spectral bandwidth in a wireless communication path is divided into different channels by carrier frequencies. Since one carrier frequency is allocated to the first MS and another carrier frequency is allocated to the second MS, both can transmit and receive with one BTS simultaneously.

[0020] In the above example, multiple mobile stations may communicate with the BTS simultaneously, and the communication between the BTS and a specific MS involves transmitting information with signals from the specific MS or the BTS. Therefore, wireless signal collisions are avoided by having the BTS and the specific MS agree on which time slot among multiple time slots to use (TDMA) and / or which carrier frequency among multiple carrier frequencies to use (FDMA). These are examples of multiple access communications.

[0021] In another type of multiple access communication called "Orthogonal Frequency Division Multiple Access (OFDMA)", a subset of subcarriers is allocated to a mobile device, and orthogonal narrow frequency subchannels are allocated to the mobile device to use the allocated spectrum more efficiently compared to FDMA.

[0022] In some frequency allocations, the allocation is per channel block, where a channel block is a set or group of two-way channels, and each two-way channel uses an uplink carrier frequency for the uplink subchannel and a downlink carrier frequency for the downlink subchannel. Channels can be grouped together into sets of two or more channels based on some logic of classification such that each set shares a common identifier or attribute.

[0023] In some protocols, the spectrum is divided into sub - spectrums of the carrier frequency and the period is divided into time slots. Typically, the BTS includes logic for determining which channels to allocate to which MSs. When allocating channels for an MS to use, a specific transceiver is allocated to use a specific carrier frequency at the BTS, the BTS indicates to the MS that it uses that specific carrier frequency, and using that carrier frequency, it can also indicate which time slots to use from the transmitted / received frames. A channel can comprise an uplink sub - channel and a downlink sub - channel. Communication between a given transceiver - MS may use two or more channels, e.g., two or more carrier frequencies and / or two or more time slots, but in many examples herein, the protocol is exemplified with respect to an MS that uses a channel with only one carrier frequency and only one time slot.

[0024] In yet another example of multiple - access communication, called "Code Division Multiple Access" (CDMA), mobile devices can use the same time slots and carrier frequencies, but each mobile device is assigned a unique pseudo - random code for encoding signals with the BTS. So, even when multiple transmitters occupy the same carrier frequency or approximately the same time, and / or the same time slots for simultaneous transmission, when they are used, applying the unique CDMA code allows receivers to separate different receptions by using the pseudo - random code to decode each specific signal adequately for demodulation, enabling multiple transmitters to occupy the same time and frequency.

[0025] In practice, CDMA does not strictly separate channels by time or by frequency. The use of CDMA results in the transmission of a spread-spectrum signal that spreads over a wider bandwidth than without coding, by using a chipping rate faster than the bit rate of the signal. Thus, when encoding a signal with a pseudo-random code, since each code represents some elements of articulation in both the time and frequency domains, the timing and frequency elements typically seen in TDMA / FDMA protocols can be replaced. In CDMA communication, the signal propagation delay and timing between the MS and the BTS are understood, and thus the pseudo-random code is applied to the received signal over several bits / chips, which of course occupy both a discrete span of part of the time domain and a discrete span of part of the frequency domain.

[0026] In some multiple access protocols, more than one technique is used.

[0027] In the digital mobile radio telephone system of the GSM protocol, the MS and the BTS utilize communication over both frequency division multiple access (FDMA) channels and time division multiple access (TDMA) channels. Thus, the MS can share the same transmission and reception carriers by the allocation of individual time slots on each carrier frequency, and each carrier frequency can be handled by an individual transceiver or transceiver module or logic block.

[0028] In GSM, the BTS plays the role of allocating time slots to the Mobile Station (MS) when access is requested. In the GSM frame structure, there are 8 time slots within each TDMA frame. The number of carrier frequencies used can vary. In some regions, some carriers have licenses for a large number of carrier frequencies, and MSs within those regions are configured to accept instructions to use one of thousands of carrier frequencies (which the BTS will also support). For example, in Europe, the GSM900 MHz spectrum band includes a 25 MHz spectrum. This is logically assigned to 200 kHz carrier frequencies (e.g., carrier frequencies centered within each 200 kHz sub-spectrum band), and when transceivers transmit signals on those carrier frequencies, 125 carrier frequencies are provided. Using guard bands (unused carrier frequencies) within the frequency domain may reduce this number, but it may also lead to improved reliability or easier signal processing. If the TDMA frame allows for 8 time slots, a BTS with a sufficient number of logical or physical transceivers available can support 8 * 125 = 1000 MS channels simultaneously. In time division and frequency division, guard slots and guard frequencies may exist respectively, so one division is separated to some extent from adjacent divisions. In some protocols, two or more time slots and / or two or more carrier frequencies can be allocated to one MS to provide a larger bandwidth.

[0029] In some cases, there are multiple BTSs within the range of supported MSs. Therefore, the support for the MSs may be spread among the BTSs, and they may be adjusted to avoid using the same carrier frequency when adjacent BTSs are possible. The BTS can be programmed to spread these frequencies throughout the tower of the BTS using a specific reuse scheme. The BTS may also be limited in the number of MSs it can support depending on the size of the pipe to other network resources. In one example, the BTS uses 1 to 15 carrier frequencies (i.e., its transceiver can transmit using 1 to 15 carrier frequencies within a transmit / receive frame, so it can support 8 to 120 users simultaneously anywhere.

[0030] Each MS typically includes a processor, memory, radio circuitry, power supply, display, input elements, etc. to perform its functions. The processor can read from the program memory to perform the desired functions. For example, the program memory may have instructions on how to form a data stream, how to pass it to the radio circuitry, how to read the internal clock to determine the value of the system clock, how to time listening and transmission appropriately, and how to set the appropriate frequencies for transmission and reception.

[0031] Each BTS typically includes a processor, memory, radio circuitry, power supply(ies), interface with the telecommunication network, diagnostic interface, etc. to perform its functions. The processor of the BTS can read from the program memory to perform the desired functions. For example, the program memory may have instructions on how to form a data stream, how to pass it to the radio circuitry, how to communicate with the telecommunication network, how to read the internal clock to determine the value of the system clock, how to time listening and transmission appropriately, how to set the appropriate frequencies for transmission and reception, how to continuously track various MSs and their states, locations, allocations, etc., and in some cases, how to store it in locally available memory.

[0032] In the method described above, the MS contacts the BTS, and several time slots are allocated within the frames of several carrier frequencies, and the BTS notifies the MS of the allocation for the MS. Since both the BTS and the MS have the same (or nearly the same) system clock, they communicate within their allocated time slots and carrier frequencies. The allocation and communication of the allocation for the MS can be performed using the random access channel that the MS uses to request the allocation. In the GSM protocol, this is called RACH processing.

[0033] In the example of GSM, communication via the radio communication path is analyzed into TDMA frames with a duration of 4.61538 ms and having 8 time slots per TDMA frame. Each time slot is long enough to hold 156.25 bits of data. In one application, the MS or BTS transmits 148 bits of data within a time slot exceeding 546.46 μs with a guard time of 8.25 bits (30.46 μs) between time slots. In the GSM900 band, the radio communication path has a bandwidth of 25 MHz each in the uplink direction and the downlink direction. The uplink subchannel uses a spectrum band of 890 - 915 MHz, and the downlink subchannel uses a spectrum band of 935 - 960 MHz to provide 125 carrier frequencies (125 carrier frequencies in each direction at 200 kHz intervals). By having a guard separation of 200 kHz on both sides of each spectrum band, 24.6 MHz of spectrum or 123 carrier frequencies remain for the moving data. Then, the total capacity of such a radio communication path (both directions) will be 156.25 bits per time slot * 8 time slots per frame * 216.667 frames / second * 123 carriers = 33.312 Mbits / second.

[0034] Considering that the MS can be mobile, while the BTS is fixed to a cell phone tower, there may be a certain distance between the MS and the BTS, and that distance can change, such as when the MS is 10 km away and moving at 100 KPH, and a voice conversation is continued via the telecommunications network using the MS. When the BTS and the MS are within a few meters of each other and the MS is not moving, the propagation time of the signal and the Doppler shift due to movement can be ignored. When the MS is moving at 100 KPH relative to the BTS, in some cases it can be ignored, but when the MS is at a certain distance away, the propagation time needs to be considered, or alternatively, the transmission within one time slot may not be fully received within that time slot but may arrive late within the time of another time slot, which can cause communication losses.

[0035] To account for the propagation delay, the transmitter advances or delays the transmission and sends a burst of radio frequency (RF) signals to account for the propagation delay, and the receiver anticipates the transmission assigned at the adjusted time. When there are multiple MSs and one BTS, it is often useful for the MSs to adjust their transmission times such that the BTS is the place where all the time slots are aligned. Similarly, the BTS can transmit its transmission within the designated time slot, but considering the propagation delay, the MSs delay or advance the time when they expect to listen or receive the transmission. In addition to assigning time slots or slots, and carrier frequency(ies) to the MSs, the BTS may indicate to the MSs the propagation delay or distance between the BTS and the MS.

[0036] In the case of a BTS operating using the GSM protocol, the BTS recognizes the propagation delay of the MS signal based on how the signal arrives at the RACH (Random Access Control Channel). The RACH channel is an uplink-only time slot used when the MS needs to access the channel to transmit data. The MS requests channel access by transmitting an 87-bit signal burst on the RACH. The RACH burst is designed to have a guard period of 69.25 bits between it and the next time slot. As a result, the burst can slide up to 69.25 bits within the RACH slot without causing adverse effects. When the RACH burst reaches the BTS, the BTS can measure the number of these guard bits by which the signal burst has slipped to the right (i.e., further moved within the time), and thus can determine the propagation delay of the signal. When the BTS responds to the MS with information regarding its channel allocation, the BTS includes what is called "timing advance" (TA), which may be expressed as the number of bits by which the MS needs to advance its signal so that it reaches the BTS within the correct time slot and does not spill over into an adjacent time slot. In the GSM protocol, the value of the timing advance can range from 0 to 63 bits, where 0 bits corresponds to no round-trip propagation delay and 63 bits corresponds to the propagation delay that would be experienced by an MS 35 km away from the BTS, assuming the radio signal travels at the speed of light.

[0037] Without careful time adjustment, transmissions from MSs operating at different distances may reach the BTS within the same time slot, causing collisions or overlaps. These collisions create interference from the BTS's perspective, which hinders the quality and reliability of communication. Guard times (measured in bits and called "guard bits") can be used to prevent burst timing errors from creating signal collisions, but this can only account for small time alignment errors within the internal clock and cannot account for differences in extended variable propagation distances.

[0038] For example, since there can be a guard time of 30.461 μs (8.25 guard bits) between time slots, even if the first MS is 4.569 km (round-trip distance of 9.138 km) away from the BTS and the first time slot is allocated, and the second MS is very close to the BTS and the next time slot is allocated, the relative propagation delay of the signal will not cause interference. This is because the signal from the first MS will be delayed by 30.461 μs, while the BTS will receive the latter part of the transmission during the guard time, and that transmission will end before the time slot of the second MS starts. In many cases, the guard time is too short to be adapted to all MSs at all distances. For example, if the MS is 10 km (round-trip 20 km) away, the propagation delay of the transmission from that MS to the BTS will be delayed by 33.333 μs, which exceeds the guard time, so the BTS will receive that transmission simultaneously with the transmission from another MS to which the next time slot is allocated.

[0039] One solution to adapt to distal MSs sharing the same BTS is to use a timing advance mechanism. The GSM protocol provides an example of this. In the initial handshake between the MS and the BTS, such as the use of the Random Access Channel (RACH) of the GSM protocol, the BTS determines the distance between the MS and the BTS. The BTS can transmit and receive time stamps during the RACH handshake when calculating the distance between the MS and the BTS if each MS is based on the uplink propagation delay.

[0040] The determined distance may not be the actual distance between the MS and the BTS, but for many purposes, the pseudo-distance is sufficient. As used herein, "pseudo-distance" is a value that may or may not be the actual value of a distance, but is used as a proxy or assumed distance. That is, the MS, BTS, or other modules elsewhere assume that the value is a distance, and various components are designed to function adequately with the use of that value when the value is close enough to the actual value. As an extreme example, assume that the MS and BTS are 2 meters apart, but there is something directly interfering with the signal between them, and the closest path is a 3 km path with a very large number of reflections. In such a case, the pseudo-distance would be 3 km, and the MS and BTS would operate assuming they are separated by 3 km. Since the signal path they follow is 3 km, it functions when used as the value of the distance between them.

[0041] Generally, the pseudo-distance or pseudo-range of a distance measured between two objects may be different from the actual distance or range of distances that can be measured by determining the time it takes for a radio frequency signal to propagate from one object to the other. Due to signal reflections and multipath, the line of sight distance (or range of distances) between the signal transmitter and the receiver may be slightly different from the propagation distance of that signal, in which case the pseudo-distance (or pseudo-range of distances) is different from the actual distance (or range of distances). However, for consistent use, many operations can function with only the value of the pseudo-distance. In other uses, "pseudo" can be used similarly to indicate an estimated value, an assumed value, an approximate value, etc.

[0042] Once the BTS determines the pseudo-distance of the MS, the BTS stores the pseudo-distance in a table maintained by the BTS for each parameter and variable of the active MS using the transceiver of that BTS. The BTS communicates that value to the MS in a control message described elsewhere in this specification. The MS is then programmed to implement "timing advance", and the MS subtracts the propagation delay corresponding to the pseudo-distance considering a copy of its system clock and transmits to the BTS earlier than the start of the scheduled time slot for its transmission. The RACH process may include various steps described in more detail below to determine these values.

[0043] As used herein, the propagation delay can be calculated from the propagation distance using c = 3*10 8 m / s as a conversion factor or an approximation thereof, and vice versa. If there is a bit rate standardized for transmission, such as 270.833 kbits / s for GSM, the propagation delay or distance can be expressed in terms of the number of bits. For example, a separation of 12 km results in a round-trip propagation delay of 80 μs, and each bit is transmitted in 3.692 μs, and the 12 km separation and 80 μs propagation delay can be equivalently represented as a separation or propagation of 22 (more precisely 21.66) bits. Thus, the propagation of 1 "bit" is equivalent to a round-trip propagation distance of approximately 555 meters and 3.692 μs.

[0044] MSs operating at different distances from the BTS are assigned different timing advances to adapt to their respective communication distances. For convenience, this may be expressed as an integer number of bits. To account for the movement of the MS, this value of timing advance is communicated to the MS and used by a module within the MS to determine when to transmit or receive, and can be updated at a period and frequency sufficient to adapt to a moving target that may have a time-varying communication distance with respect to the BTS. For example, if a user is using an MS on a high-speed train traveling at 200 KPH, the distance may need to be updated more frequently than when the user is walking on the road.

[0045] In a specific example of the GSM protocol, the timing advance is represented as a 6-bit value, with the minimum value representing a timing advance of 0 bits and the maximum value representing a timing advance of 63 bits. Since each bit in the GSM protocol is assumed to correspond to 3.692 μs (and about 555 meters for round-trip propagation delay), when the pseudo-distance is about 555 m / bit * 63 bits = 34,965 m, i.e., about 35 km, a timing advance of 63 bits will be used. Therefore, this timing advance method will function properly for MSs in the range of 0 to 35 km from the BTS. In the GSM protocol, the BTS is programmed not to respond to requests from the MS or at least not to anticipate such requests if the BTS determines that the MS is more than 35 km away from the BTS. This does not pose a problem if there are other closer BTSs or in the case of a BTS distribution where all points are within 35 km from one or more BTSs.

[0046] In timing advance, the MS transmits a transmission (from the MS's clock timing) before the start of its time slot. When this transmission is received at the BTS after propagation delay, the BTS receives the entire transmission within the time slot where the timing advance corresponds to the propagation delay. Since the MS is provided with a value regarding the amount of timing advance to use, it can do this correctly. It should be noted that the actual distance, and thus the actual propagation delay, may be different from the pseudo-distance, but in many cases, there is a certain margin to handle differences in internal clock, transmitter variations, etc. in the communication between the MS and the BTS, so it does not pose a problem.

[0047] This timing mechanism functions properly when there is always one or more BTSs within 35 km from any MS, but this is not always the case. In some geographical regions, it may not be practical, feasible, or economical to have a BTS within 35 km from any point in that region. For example, in rural, remote, or island geographical regions, a BTS infrastructure with such intervals may not be able to access the land, and since users with MSs may be scattered and cover a wide area, the BTS may not be used, or may not be installable, or may not be able to obtain power. In such situations, an "extended range" mechanism can be used. In the GSM protocol, such a mechanism is possible.

[0048] In the extended range mechanism, instead of one, two consecutive time slots are allocated to each MS, so that the MS can communicate with the BTS without the need for any timing advance if it can delay the transmission at the BTS for the duration of one time slot. This increases the allowable distance between the MS and the BTS (e.g., from 35 km to 120 km), but only 4 instead of 8 allocable time slots are available in each TDMA frame, so the throughput is reduced by half. This may not be important for rural, remote, or island areas when the data rate is low. By using a combination of the timing advance mechanism and the extended range mechanism, the maximum allowable MS - BTS can be 35 km + 85 km = 120 km.

[0049] In the extended range mechanism, for each MS, the entire time slot is allocated as an additional guard period that reduces the throughput by half. A variation of this is, for example, a "sorted extended range mechanism" similar to that shown in U.S. Patent No. 5,642,355. In the sorted extended range mechanism, the time slot is "consumed" and used as a guard bit, and the time slot is allocated to the MS according to the distance. The nearest MS obtains the first time slot, and the farthest MS obtains the last time slot before any "consumed" time slot that has been allocated to an MS, i.e., not allocated to any MS. Since the extended range of the MS spreads the transmission, the consumed time slot is used for the required guard bits. In practice, this "divides" the unused time slots between bursts.

[0050] If there is a separation of more than 85 km or for other reasons, a "ring extended range" mechanism can be used. In the ring extended range mechanism, a fixed minimum distance is assumed, and the timing at the BTS is adjusted according to that fixed minimum distance. Since the BTS assumes that all MSs are at least that distance away, MSs closer than the minimum communication distance are not supported. This is similar to the method shown in U.S. Patent No. 6,101,177. Without the need for any modification of the MS, the distance between the MS and the BTS ranging from the minimum distance to the minimum distance plus 35 km obtained using the timing advance mechanism can be supported. In one example, the minimum distance is 85 km, but different minimum communication distances can be used. In that case, in this example, the BTS can support MSs in the range of 85 km to 120 km from the BTS.

[0051] The ring extension range mechanism may be used using eight of the eight assigned time slots and can handle an MS having a distance ranging from 85 km to 120 km from the BTS. However, this creates a physical coverage gap that radially departs from the BTS to some extent because any signal burst transmitted from that area reaches the BTS much faster than the way the BTS visualizes that time slot. Instead, the BTS provides area ring coverage. Since the ring extension range mechanism can be used in a geographical area having a physical gap such as a lake or a valley between the BTS and the MS designed for service, it would not be a problem for the MS to have an area inside the ring that is not supported.

[0052] It should be noted that the GSM system uses a TDMA frame offset between the uplink subchannel and the downlink subchannel. In a typical GSM frame structure, the uplink TDMA frame (or MS Tx and BTS Rx) is offset by only three time slots from the downlink TDMA frame (or BTS Tx and MS Rx) for the purpose of ensuring that the MS does not need to transmit and receive simultaneously. It will be clear to those skilled in TDMA communication that this offset between the uplink subchannel and the downlink subchannel is independent of communication over an extended distance and is not the same as the time slot synchronization offset used in the uplink TDMA frame only within the ring extension range mechanism.

[0053] When combining the ring extension range mechanism with the extension range mechanism, it can be used alone or in combination to have a BTS coverage that can exceed a radius of 120 km. These techniques are often sufficient for terrestrial communication because such communication is typically limited by the curvature of the earth. For example, to provide a distance D for line-of-sight communication between a surface-based MS and a BTS transceiver, the BTS transceiver should be equipped at a height of at least h = [SQRT(6370^2 + D^2) - 6370] km. When D = 120 km and h = 1130 m, since 1,130 meters is higher than any structure currently being built, the height of the tower is much higher than the distance and also much higher than the height that is the limiting factor for terrestrial communication. Therefore, techniques for extending the distance beyond 120 km are not very useful for cellular voice, data, text, and similar-capacity terrestrial communication, except in some selected locations where there is a large geological structure equipped with a transceiver above.

[0054] In cases where it is not practical to distribute the base station towers to widen the coverage, such as in areas where it is not practical to place a base station within 35 km or 85 km of some locations, or within 120 km where a high tower can be equipped, satellite communication can be used. Typically, satellite communication is very expensive and is therefore only used for applications that support costs such as resource exploration, explorers, searches, and rescues.

[0055] As used herein, the term "satellite" refers to an artificial satellite launched from the Earth with the goal of operating in orbit, and / or an artificial satellite that is assembled in whole or in part on the Earth's surface and / or in orbit, and that operates in orbit regardless of how it is assembled. A satellite may be assembled and / or operate in one orbit and may move to another orbit. A satellite may be propelled or operate without its own propulsion means and may or may not rely on other objects in the orbit to provide propulsion. As used herein, a satellite operating in orbit and not under propulsion is in a more or less stable orbit. Such an orbit has a minimum distance above the Earth's surface due to atmospheric drag. There is no sharp dividing line between the vacuum sufficient to place an object in orbit and the excessive atmosphere that can cause a satellite to deviate from its orbit, and it has been shown that a Low Earth Orbit (LEO) of about 400 - 500 km above the Earth is practical, although in the case of particularly dense spacecraft such as nanosatellites, it may be lower than these altitudes.

[0056] The fact that the minimum distance of a practical orbit is very large has conventionally meant that completely different technologies have been used for satellite communication. In some cases, the ground station was not mobile, and in other cases, the ground station was mobile but power-intensive, heavy, large, and required special equipment. In addition to the distance, the movement of satellites in orbit had to be addressed.

[0057] There are many solutions for communication between a satellite and a terrestrial surface-based mobile handset that uses the TDMA protocol for communication. Some satellite providers include the Iridium™, Globalstar™, Thuraya™, and Inmarsat™ satellite systems, which are based on either proprietary satellite phones or user terminals (i.e., unique hardware devices that can be attached to or connected to an existing mobile phone by a physical or RF connection). In certain user terminals, each can be specially designed to function with other user terminals, thus simplifying the design of the system, satellite, and terminal. The drawback is that it requires specific terminal equipment that may be expensive and unrealistic for all end users or small groups of end users. The custom terminal approach simplifies system design, but the operator can freely set details such as communication methods, power levels, frequencies, etc., tying the user to a specific provider. As a result, end users may need to purchase a satellite phone (or a user terminal that connects to an existing mobile phone) that costs hundreds to thousands of dollars, has a large, unwieldy antenna, consumes significant power, and requires an exorbitant monthly subscription fee to operate, and may need to do so with two or more satellite providers. This has limited the appeal of the traditional satellite phone market.

[0058] As an example, U.S. Patent No. 8,538,327 describes a modification of a user device that calculates a delay measurement based on data indicating the position of a satellite and data indicating the position of a user device. The timing of the uplink communication from the user device adjusts that delay when transmitting to the satellite. The user device also calculates a frequency offset based on data indicating the position and velocity of the satellite and adjusts its uplink signal frequency accordingly to account for the dynamic Doppler shift within the communication system. Of course, this requires a specific user device on the surface designed for satellite communication.

[0059] As another example, U.S. Patent Publication No. 2006 / 0246913 describes a method for managing the propagation delay of RF signals using a subcoverage ring that reduces the difference in the difference of round-trip propagation delays. This uses a geosynchronous Earth orbit (GEO) satellite to act as a relay and connect remote mobile stations to a base station within its network. To handle the much larger delays introduced by the GEO satellite, separate processing devices serve separate subcoverage rings or zones by configuring themselves according to the allowable propagation delay range of the ring / zone. The link between the mobile station and the GEO satellite cannot be closed without the assistance of additional user terminal hardware for power, signal directivity, and frequency operation.

[0060] There is a need for an improved system for satellite-based communication with a portable or mobile device. SUMMARY OF THE INVENTION

[0061] A multi-connect transceiver for communication with a mobile station within an environment addresses conditions that exceed the design assumptions of the mobile station without necessarily requiring modification of the mobile station, as may be seen within an Earth orbit. The multi-connect transceiver is adapted to close communication with the mobile station while exceeding design assumptions of the mobile station, such as greater distances, greater relative motion, and / or other conditions commonly seen when the functionality of a terrestrial transceiver is implemented by an orbital transceiver. The orbital transceiver can include a data parser that analyzes frame data structures, a signal timing module that adjusts timing based on the propagation delay from orbit to ground, a frequency shifter, and a programmable radio that can communicate from an Earth orbit using a multi-connect protocol, such that the communication is compatible with or appears to be so to a terrestrial cellular base station and a terrestrial mobile station.

[0062] The multi-connection transceiver can support terrestrial mobile stations that are cellular phone handsets, smart phones, and / or connected devices. The signal timing module can be adapted to adjust the frequency of the transmission signal to the terrestrial Doppler shift based on the orbit. The signal assignment logic can assign the capacity of the multi-connection transceiver, which is distributed across a plurality of time slots, a plurality of carrier frequencies, a plurality of orthogonal sub-carriers, and / or a plurality of code sequences, to a plurality of terrestrial mobile stations including the terrestrial mobile station. The multi-connection transceiver can include, for each terrestrial mobile station, a range calculator that determines the distance from the multi-connection transceiver to the terrestrial mobile station, and a signal timing module that determines the timing of the transmission signal with respect to the frame structure, where the frame structure includes a plurality of slots each having a zero or non-zero time slot synchronization offset that results in a variable transmission delay due to the distance from the multi-connection transceiver to the terrestrial mobile station, and an input signal assigner that assigns a listening time slot within the frame structure to listen for communications from the terrestrial mobile station, where the listening time slot is timed based on the distance from the multi-connection transceiver to the terrestrial mobile station, the listening time slot is one of the plurality of time slots, and the plurality of time slots are variably delayed within the frame structure to account for the multi-connection transceiver handling communications from a plurality of terrestrial mobile stations having a plurality of distances from the multi-connection transceiver.

[0063] The multi-connection transceiver may have a plurality of time slots, and the plurality of time slots are variably delayed within the frame structure so as to consider a multi-connection transceiver that handles communications from a plurality of terrestrial mobile stations having a plurality of distances from the multi-connection transceiver by allocating each of the plurality of different distance ranges to each of the plurality of channel blocks. The different distance ranges may collectively cover the slant range from the zenith distance to the minimum elevation distance. The zenith distance is the distance between the satellite carrying the multi-connection transceiver and the zenith position with respect to the terrestrial mobile station, and the minimum elevation distance is the distance between the position of the satellite when the terrestrial mobile station enters the designed footprint of the satellite. Each of the different distance ranges may extend approximately 34 to 35 kilometers, and the difference between the zenith distance and the low elevation distance is 210 to 250 kilometers. The designed footprint of the satellite may be circular, elliptical, rectangular, and / or independent of the function of the antenna and / or the shape of the antenna beam, but in many cases, it is approximated as circular.

[0064] The multi-connection transceiver is adapted for operation within the Earth's orbit and is configured to communicate with terrestrial mobile stations, and includes a data analyzer that defines a frame structure specifying which time slots are assigned to which of the plurality of terrestrial mobile stations, a range calculator that determines the distance from the multi-connection transceiver to each terrestrial mobile station, a channel assignment module that allocates the plurality of terrestrial mobile stations to a plurality of channel blocks, where the channel blocks have terrestrial frequencies and orbital frequency offsets, a signal timing module that determines the timing of the transmission signal with respect to the frame structure, and a signal modulator that modulates a signal to the terrestrial mobile station at the terrestrial frequency using the orbital frequency offset, where the orbital frequency offset at least approximately corresponds to the expected Doppler shift in the signal transmitted to the terrestrial mobile station due to the relative movement of the multi-connection transceiver and the terrestrial mobile station, such that the terrestrial mobile station receives the signal at the terrestrial frequency. The plurality of channel blocks may be assigned based on the relative positions of the satellite carrying the multi-connection transceiver and the terrestrial mobile stations, and the orbital frequency offset varies in small increments, such as in 5-kilohertz increments.

[0065] In certain embodiments, a multi-connectivity base station having one or more transceivers handles communication with a plurality of terrestrial mobile stations, and the terrestrial mobile stations are configured to anticipate base station communication with a terrestrial cellular base station that is within a restricted distance from the terrestrial mobile stations and / or is moving at a speed less than a restricted speed relative to the terrestrial mobile stations. The multi-connectivity base station includes a data analyzer that analyzes data received by the multi-connectivity base station according to a frame structure, the frame structure defining which time slots are assigned to which of the plurality of terrestrial mobile stations, the frame structure including a plurality of slots each having a zero or non-zero time slot synchronization offset that results in a variable transmission delay due to the distance from the multi-connectivity base station to the plurality of terrestrial mobile stations; a signal timing module that determines a signal timing adjustment to the frame structure of a transmission signal to a terrestrial mobile station based on the base-mobile distance between the multi-connectivity base station and the terrestrial mobile station, the base-mobile distance exceeding a restricted distance; and a programmable radio that can communicate using a multi-connectivity protocol from the multi-connectivity base station to the terrestrial mobile station and take into account the signal timing adjustment, such that the communication is compatible with or appears to be so to the terrestrial mobile station as if it were communication between a terrestrial cellular base station and the terrestrial mobile station despite the base-mobile distance exceeding the restricted distance.

[0066] The multi-connection base station may be adapted to communicate with a plurality of terrestrial mobile stations, and the plurality of terrestrial mobile stations may include a cellular phone handset, a smart phone, and / or a connected device. The limited distance may be about 100 kilometers, 120 kilometers, or some other distance, and the base-mobile distance exceeds that limited distance. The multi-connection protocol may be one of a CDMA-based protocol, an LTE protocol, a GSM protocol, an OFDMA-based protocol, an FDMA-based protocol, a TDMA-based protocol, an EGPRS protocol, or an EDGE protocol. The multi-connection base station may be an orbital base station operating within the Earth's orbit, the limited distance is 120 kilometers, and the base-mobile distance of the terrestrial mobile stations of the plurality of terrestrial mobile stations is about 500 kilometers to about 750 kilometers. In another variant, the multi-connection base station is a base station operable within the Earth's atmosphere and includes being equipped on or in one or more of an airplane, a drone, and / or a balloon, the limited distance is 120 kilometers, and the base-mobile distance exceeds 120 kilometers.

[0067] The multi-connectivity base station may include signal allocation logic for allocating the capacity of the multi-connectivity base station, which is distributed across a plurality of time slots, a plurality of carrier frequencies, a plurality of orthogonal sub-carriers, and / or a plurality of code sequences, to a plurality of terrestrial mobile stations including terrestrial mobile stations. The programmable radio can listen for communications from terrestrial mobile stations using a multi-connectivity protocol, and for each terrestrial mobile station of the plurality of terrestrial mobile stations, a range calculator that determines the base-mobile distance of each terrestrial mobile station from the multi-connectivity base station to the terrestrial mobile station, and a reception timing module that determines the timing of the received signal of the terrestrial mobile station with respect to the frame structure based on the base-mobile distance of the terrestrial mobile station, and an input signal allocator that allocates listening time slots within the frame structure to listen for communications from terrestrial mobile stations, wherein the listening time slots are timed based on the base-mobile distance of the terrestrial mobile station, the listening time slots are one of the plurality of time slots, and the plurality of time slots are variably delayed within the frame structure to account for a multi-connectivity base station handling communications from a plurality of terrestrial mobile stations having a plurality of base-mobile distances.

[0068] The plurality of time slots can be variably delayed within the frame structure to account for a plurality of terrestrial mobile stations having a plurality of base-mobile distances by allocating each of the plurality of different base-mobile distance ranges to each of the plurality of channel blocks. The multi-connectivity base station can be an orbital base station operating within an Earth orbit, and the plurality of different base-mobile distance ranges collectively cover the slant range from the zenith distance to the minimum elevation distance, where the zenith distance is the distance between the terrestrial mobile station and the zenith position of the satellite carrying the multi-connectivity base station, and the minimum elevation distance is the distance between the terrestrial mobile station and the position of the satellite when the terrestrial mobile station enters the designed footprint of the satellite.

[0069] Each of the different base-mobile distance ranges can extend approximately from 34 to 35 kilometers, and the difference between the zenith distance and the minimum elevation distance is from 210 to 250 kilometers.

[0070] The design footprint of the satellite can be circular, elliptical, rectangular, etc., and can be independent of the function of the antenna and / or the shape of the antenna beam.

[0071] In one modification, a multi-connected base station having one or more transceivers handles communication with a plurality of terrestrial mobile stations that are within a restricted distance from a terrestrial mobile station and / or are moving at a speed less than a restricted speed relative to the terrestrial mobile station, and that are configured to anticipate base station communication with a terrestrial cellular base station. The multi-connected base station includes a data analyzer that analyzes data received by the multi-connected base station according to a frame structure that defines which time slots are assigned to which of the plurality of terrestrial mobile stations, and according to a multi-connection protocol that anticipates that the terrestrial mobile stations receive signals at a specified frequency and transmit signals at the specified frequency; a Doppler shift calculator that determines, for each terrestrial mobile station of the plurality of terrestrial mobile stations, the Doppler shift of each terrestrial mobile station due to the speed of each terrestrial mobile station relative to the multi-connected base station; a channel assignment module that assigns each of the plurality of terrestrial mobile stations to a channel block within a plurality of channel blocks, each channel block having a terrestrial frequency and a Doppler frequency offset; a signal modulator that modulates a signal to the terrestrial mobile station at the terrestrial frequency using the Doppler frequency offset, the Doppler frequency offset corresponding at least approximately to the anticipated Doppler shift in the signal transmitted to the terrestrial mobile station due to the relative movement of the multi-connected base station and the terrestrial mobile station, such that the terrestrial mobile station receives the signal at the terrestrial frequency; and a programmable radio that can receive communication from the terrestrial mobile station using the multi-connection protocol and take into account the Doppler frequency offset of the terrestrial mobile station, such that the communication is compatible with or appears to be so between the terrestrial cellular base station and the terrestrial mobile station even though the speed of the terrestrial mobile station relative to the multi-connected base station exceeds the restricted speed.

[0072] The speed of the terrestrial mobile station with respect to the multi-connectivity base station can be the result that the multi-connectivity base station is within the Earth's orbit, and the Doppler frequency offset can vary in increments of 5 kilohertz.

[0073] The multi-connectivity base station may have signal allocation logic for allocating the capacity of the multi-connectivity base station, which is distributed over a plurality of time slots, a plurality of carrier frequencies, a plurality of orthogonal sub-carriers, and / or a plurality of code sequences, to a plurality of terrestrial mobile stations including the terrestrial mobile station.

[0074] The multi-connectivity base station may provide an uplink sub-channel and a downlink sub-channel including a continuous spectrum of the uplink sub-channel and a continuous spectrum of the downlink sub-channel for each of the plurality of channel blocks. The channel blocks may be allocated such that adjacent channel blocks are assigned to adjacent Doppler frequency offsets.

[0075] In certain embodiments of a multi-connectivity base station having one or more transceivers handling communication with a plurality of terrestrial mobile stations, the terrestrial mobile stations are configured to anticipate base station communication with a terrestrial cellular base station that is within a restricted distance from the terrestrial mobile station and / or moving at a speed less than a restricted speed relative to the terrestrial mobile station. The multi-connectivity base station includes a data analyzer that analyzes data received by the multi-connectivity base station according to a frame structure and a multi-connectivity protocol. The frame structure includes a plurality of slots each having a zero or non-zero time slot synchronization offset that defines which time slot is assigned to which of the plurality of terrestrial mobile stations and results in a variable transmission delay due to the distance from the multi-connectivity base station to the plurality of terrestrial mobile stations. The multi-connectivity protocol is such that the terrestrial mobile stations are expected to transmit at a specified frequency and receive at a Doppler frequency offset, and the multi-connectivity protocol further specifies channels within a plurality of channel blocks, each channel block having a specified terrestrial frequency and a specified time slot. A signal timing module determines a signal timing adjustment to the frame structure of the transmission signal to the terrestrial mobile station based on the base-mobile distance between the multi-connectivity base station and the terrestrial mobile station. When the base-mobile distance exceeds a restricted distance, a specified signal timing adjustment is assigned to each channel block. A Doppler shift calculator determines the Doppler shift of each terrestrial mobile station relative to the multi-connectivity base station due to the speed of each terrestrial mobile station among the plurality of terrestrial mobile stations, and a specified Doppler frequency offset is assigned to each channel block. A dynamic channel allocator assigns each of the plurality of terrestrial mobile stations to a specified channel block within the plurality of channel blocks based on the specified signal timing adjustment and the specified Doppler frequency offset of the channel block, where the number of channels within the specified channel block has or is expected to have the specified signal timing adjustment and the specified Doppler frequency offset.A dynamic channel allocator corresponding to the number of a plurality of terrestrial mobile stations, and a signal modulator that modulates a signal to the terrestrial mobile stations at a terrestrial frequency using a Doppler frequency offset, wherein the Doppler frequency offset corresponds at least approximately to an expected Doppler shift in the signal transmitted to the terrestrial mobile stations due to the relative movement of the multi-connection base station and the terrestrial mobile stations, and thus, the terrestrial mobile stations receive the signal at the terrestrial frequency, a signal modulator, a programmable radio that can receive communications from the terrestrial mobile stations using a multi-connection protocol and take into account the Doppler frequency offset of the terrestrial mobile stations, and thus, the communication is compatible with the communication between the terrestrial cellular base station and the terrestrial mobile stations or appears to be so to the terrestrial mobile stations, even though the base-mobile distance exceeds the limit distance and the speed of the terrestrial mobile stations relative to the multi-connection base station exceeds the limit speed.

[0076] The following detailed description, together with the accompanying drawings, will provide a better understanding of the nature and advantages of the present invention.

Brief Description of the Drawings

[0077] Various embodiments according to the present disclosure will be described with reference to the drawings.

[0078]

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Modes for Carrying Out the Invention

[0079] In the following description, various embodiments are described. For the purpose of the description, specific configurations and details are described to provide a complete understanding of the embodiments. However, it will also be apparent to those skilled in the art that the embodiments can be implemented without specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the described embodiments.

[0080] The techniques described and proposed herein include the design of a satellite-based base transceiver station (BTS) that implements a transceiver for transmitting and receiving between ground-based devices such as a mobile station (MS) that is a satellite or part of a satellite operable in orbit and is designed to be used in a terrestrial BTS. In many cases, the MS can be used without any physical modifications or even any software modifications, in which case the MS is communicating with the transceiver and the BTS is not a terrestrial BTS, or more generally, the BTS is at a relative distance greater than the design assumption of the distance, at a relative speed much faster than the relative speed at which the MS would be designed, and operating outside the scope of the design assumptions of the MS, such as other design assumptions.

[0081] In the case of an orbital transceiver and a terrestrial MS, the BTS would be outside the scope of the design assumptions of the MS design that assumes a maximum distance from the BTS to the MS of about 35 km, such that relative motion such as the time derivative of the distance between the BTS and the MS during communication could be ignored, or outside the scope of the design assumptions of the MS design that assumes much less than the 7.2 - 7.8 km / s that would be experienced compared to an orbital transceiver. Other design assumptions may also be affected. For example, an orbital transceiver would have a limited time window for communication as the satellite rises above the MS until the satellite drops below the minimum altitude on the opposite horizon.

[0082] Many of the examples and details in this specification relate to an orbit transceiver that is adapted, configured, programmed, etc. to close communication with an MS that operates as if its design assumptions still hold, but these techniques can be used beyond the example of an orbit. For example, it can be used for a BTS located sufficiently high such that the slant angle exceeds 120 km. For example, if the BTS can be equipped at an altitude of 1,130 meters, it is sufficient to enable a line of sight (slant range) to an MS of more than 120 km. Platforms such as airplanes, UAVs, high-altitude drones, hot air balloons, high-altitude balloons, suborbital vehicles, space planes, mountains, or even some very large towers may be conditions where some or all of these techniques are found to be useful. Also, the techniques described can be deployed even for a ground-based BTS, but it is worth noting that the antenna is directed to provide services to an MS operating in a platform that creates a long communication distance (such as exceeding 120 km) and / or a high Doppler shift environment such as exceeding approximately 200 KPH. This can include conditions where the MS is operating on the surface, in the atmosphere, or in a space environment, the BTS is on the surface, and is mobile (e.g., on some vehicles) or in some cases stationary.

[0083] These techniques may also be found useful when the MS is in an orbit and needs to operate and be adjusted to adapt to those MSs as if the design assumptions are true, the BTS is terrestrial, and it operates even if the design assumptions are not true. For example, the MS can be used in a moving airplane or, in some cases, in a future space station. A base station tower on the surface with a sufficiently large antenna can perform the operation of closing communication with the MS while dealing with violations of similar design assumptions such as long distances and high Doppler shifts.

[0084] The BSC and MSC (including Home Location Register or HLR, and subscriber handling) functions may also be satellite-supplied, or some of the functions that are not needed in orbit are implemented terrestrially. The BTS, BSC, and / or MSC functions can be implemented using conventional off-the-shelf software-defined radios, or commercial-grade (or proprietary) hardware / software, as long as they can be programmed, configured, or adapted to perform the required functions.

[0085] The BTS can provide its function despite the increased distance between the BTS and the MS, which causes power reduction due to distance and latency in the time of flight due to distance, and also despite the greater relative movement between the BTS and the MS that exceeds typical ground-based relative movement that the MS can make with respect to the BTS. The latter causes Doppler shift, and conventional MSs such as cell phones may not be designed to handle Doppler shifts as large as those caused by satellites moving relative to the MS at speeds of up to 7.6 km / s experienced in LEO in some cases. These Doppler shifts will be variable since they vary with the location of the MS within the satellite's footprint. Negative Doppler shifts are seen at locations behind the satellite, and positive Doppler shifts are seen at locations in front of the satellite.

[0086] Power levels should be addressed. As an example, in the GSM specification, mobile phones are required to rapidly increase their transmission power to 1 - 2W (depending on frequency) as needed. Mobile phones do this naturally on the RACH, and once a channel is allocated, the BTS can instruct it to be quiet if there is no need to transmit at "high volume". At a suitable BTS antenna capacity, 2 watts can be sufficient transmission power to close the link at an altitude of 500 km with a reasonable elevation angle using an antenna such as a 50 cm foam factor, and the data transfer speed is adjusted as needed. For example, one implementation might focus on narrowband messaging with 2G speeds and short data bursts rather than attempting to support data rates such as 4G LTE, although the latter might be possible. In such a way, lower power levels and higher data rates can still typically be supported by space-based base stations with sufficient antenna technology. However, reducing the power level of surface devices and increasing the data rate tends to increase the power and mass requirements of the space segment.

[0087] As used herein, "footprint" refers to an area on the earth's surface within the range that closes the communication channel with the BTS on the satellite. In the examples of this specification, a circular footprint is used, but it should be understood that the footprint may not be circular and may depend on unclear factors, the shape of the earth's surface, atmospheric conditions, etc. In some examples, the footprint is a "design footprint" that is different from the actual footprint. For example, the satellite may actually be at a certain distance, and thus may be able to communicate with a mobile device within the actual footprint of the satellite, but due to selectivity, performance, or other reasons, the system using that satellite is designed for a different footprint, such as a footprint smaller than the actual footprint, i.e., the design footprint. The boundary of the design footprint can be circular or elliptical projected onto the earth by the satellite, centered on a point on the surface directly below the satellite and having a radius that the satellite is designed to cover, such as a certain slant range.

[0088] As used herein, "earth's surface" is used to refer to the location of the MS, but it should be understood that "earth's surface" is not limited to the surface of the earth. When the MS is described as being surface-based or on the earth's surface, the MS may be on the surface of the earth, on the surface of a body of water, somewhat below the surface of the earth or somewhat below the surface of a body of water, on an upper floor of a building, within a structure that is not exactly at ground level, in an airplane or otherwise in the air but in the atmosphere, or in the hand of a person standing in a similar location. However, for clarity of explanation, the MS may be described as being on the earth's surface to distinguish it from elements in orbit. This does not mean that the systems described herein are not usable for MSs in orbit. Where applicable, unless stated otherwise, even if the MS in orbit has not been specially modified to communicate with a BTS in orbit, assuming the device has sufficient durability for electrical, mechanical, and otherwise orbital use, it is also possible to support the MS in orbit.

[0089] As used herein, "in orbit" means being at a location, moving at a velocity relative to an inertial frame that is (more or less) stationary with respect to the center of the Earth's gravity, and experiencing little or no atmospheric drag at that location such that it can easily maintain its orbit. In some examples herein, an orbital distance is given, which refers to the approximate typical distance from an average or normal point on the surface of the Earth, as is conventional, to describe the orbit. "LEO" is used in some examples, and it should be understood that these examples can apply to orbits that are somewhat outside the range that is still considered to be an orbit as conventionally defined as LEO. Unless otherwise indicated, being in orbit can also describe an orbit around another celestial body, such as Mars, the Moon, a moon of another planet, or even a target point such as L1 or L2. In many of the examples herein, the BTS is in orbit around the Earth and the MS is terrestrial. If the BTS and MS exchange locations, or if the BTS is inside an aircraft, an autonomous vehicle without a driver, a balloon, etc. instead of an Earth orbit, and encounters similar difficulties, or more generally, if conditions exist where difficulties such as distance, propagation delay, and / or Doppler shift exceed those that the MS is typically designed to support or experience, for example, if the design assumes that the MS is involved in the construction and / or programming, the teachings herein can be used for other situations.

[0090] In a traditional TDMA communication system, there are aspects of timing and signal power that create conditions to follow the expected protocol to close the communication link, i.e., the received signal power is sufficiently higher than the noise / interference environment so that data can flow over the channel at the desired data rate and bit error rate, and the communicating devices do not give up at either end. As described herein, a satellite-based BTS can communicate with a terrestrial-based MS designed to be used with a terrestrial-based BTS. The satellite-based BTS modifies the TDMA communication with the MS in a way that is transparent to the MS while allowing communication over a certain range of different distances by considering variable propagation delays. With a constellation of satellites in LEO, it is possible to provide continuous connection from an orbit 400 - 500 km above the Earth to an MS using conventional terrestrial communication technologies and protocols at an acceptable economic deployment cost and reasonable service life. The BTS provides timing suitable for the TDMA frame structure, enabling channel allocation or assignment schemes that support communication over orbital ranges and reduction of the required range of pseudo distances and Doppler shifts, and dealing with issues and inconsistencies of signal interference associated with Doppler shifts caused by orbital interference. As a result, the BTS described herein can provide communication between a spacecraft and a terrestrial telecommunications device, as well as communication using the characteristics and facilities of terrestrial telecommunications devices typically used for terrestrial telecommunications. This can extend the range of radio coverage of the communication system and enable communication between an orbiting spacecraft and a mobile phone or other communication / wireless device. The BTS can be used in a communication system that utilizes multiple access techniques in the frequency and / or time domain (i.e., TDMA, FDMA, OFDMA, etc.) used by conventional mobile phones to communicate with a spacecraft in orbit using the GSM cellular communication protocol or a similar terrestrial protocol.

[0091] Because the BTS handles RF signals that slide in both the time domain and the frequency domain, it can be implemented using a communication mode that uses a multiple access method in the time domain and / or the frequency domain, such as TDMA, FDMA, CDMA, OFDMA, etc., which need to handle a given associated distance and the associated speed. Generally, unless otherwise indicated, the teachings herein can be applied to one or more of these examples of multiple access methods and systems, and multiple mobile stations are communicating with or attempting to communicate with the BTS. To avoid interference, the protocol used provides multiple access by having the MSs use different time slots, carrier frequencies, and / or code sequences. Thus, many examples are described with reference to the TDMA / FDMA protocol, but can be extended to other protocols.

[0092] In this specification, distances may be expressed in units other than kilometers, in which case certain conversions are assumed. For example, the speed of light in a vacuum may be the conversion factor when distances are expressed in units of seconds such as microseconds and milliseconds. The propagation delay in a particular situation may be the speed of light in a vacuum or may be longer, but from the context, it will be apparent to those skilled in the art how to determine the given distance from the propagation delay expressed in seconds.

[0093] Similarly, distances and / or times may be expressed in bits, in which case certain bit rates are assumed. For example, when the bit rate is 270.833 kbit / s, a period expressed as "156.25 bits" will refer to a period of 576.92 μs, and a distance expressed as 10 bits will occupy 36.92 μs to transmit 10 bits. In a period of 36.92 μs, the signal can travel a distance of 5.538 km (round trip) at the speed of light in a vacuum, so it can correspond to a distance of 5.538 km. The difference between the speed of light in a vacuum and the actual propagation speed may vary and may be taken into account, but the details may be omitted for the purpose of illustration so as not to complicate the description.

[0094] Description of an Exemplary BTS and Its Operation The present invention will be described in detail with reference to specific, but not necessarily preferred, embodiments of the present invention. These specific embodiments are by way of example, and those skilled in the art of multi-connection communication systems and orbital mechanisms will recognize, upon reading this disclosure, that other variations are possible, and that this disclosure relates to many types of multi-connection communication systems between an MS on the surface of a planet and a spacecraft BTS operating in various orbits around that planet.

[0095] In many of the examples herein, the orbit of the satellite containing the BTS is given as a circular orbit with an altitude of 500 km, but it should be understood that the teachings herein apply to other orbits adjusted accordingly. In some examples, the BTS operates as a GSM BTS or simulates the operation of a GSM BTS, or fully implements the functions for communicating with a terrestrial mobile station (MS) near the surface of the Earth, i.e., not in orbit.

[0096] In some of the examples herein, the footprint of the satellite is given as a set of points on or near the surface of the Earth where the satellite is above a minimum elevation angle as seen from the MS. As used herein, when the satellite is directly above the MS, the MS "sees" the satellite at an elevation angle of 90 degrees (and thus the MS is in the nadir direction with respect to the satellite). In the examples herein, the slant range is 90 degrees to 40 degrees, but other slant ranges greater than or less than that may be used. Those skilled in the art will understand how to appropriately modify the calculations herein after reading this disclosure.

[0097] Assuming a circular orbit of 500 km using a radius of 6370 km for the Earth, when the elevation angle is 90 degrees, the MS within the footprint is 500 km from the BTS. Using basic geometry, it can be determined that a satellite within a 500 km circular orbit will appear at an altitude of approximately 40 degrees with respect to the horizon of a point on the Earth's surface when the distance from the satellite to that point is about 741 km. The propagation delay of the signal between the MS and the satellite BTS is a function of the distance, and the distance to the satellite within the orbit is a function of the orbit radius and the elevation angle, which is the angle between the position vector of the satellite and the position vector of the MS. When the elevation angle is 90 degrees, i.e., the satellite is overhead and the MS is at the surface point in the direction of the nadir of the satellite, the distance can be taken as, or approximately so, the difference between the orbit radius and the Earth's radius. When the elevation angle is less than 90 degrees, the distance can be calculated. For some of the minimum elevation angles for which a connection is expected to be established, it is generally considered that it will correspond to the longest distance supported for an angled connection. At a minimum elevation angle of 40 degrees, the interaction time between the MS and the satellite BTS can be calculated at the BTS and / or the MS as follows. For a 40-degree elevation angle and a 500 km circular orbit, the central angle of the Earth is ACOS(R_earth*COS(min_elev) / (R_earth+h))-min_elev = 4.74 degrees, where R_earth = 6370 km (radius of the Earth), min_elev is the minimum elevation angle (40 degrees in this example), and h is the satellite altitude (500 km in this example). The time it takes for the MS to move from a minimum elevation angle of 40 degrees with respect to a satellite on one horizon to a minimum elevation angle of 40 degrees with respect to a satellite on the other horizon can be calculated as the time it takes for the satellite to travel 2*4.74 = 9.47 degrees of the Earth's surface. As described herein, a satellite in a 500 km circular orbit is moving at 7.11 km / s with respect to the Earth's surface. Therefore, the time it takes to travel 9.47 degrees of the Earth's surface at this speed is in seconds and is approximately 9.47 degrees * pi / 180 * (R_earth+h) / 7.11 km / s = 159.86 seconds. Of course, other minimum elevation angles can be used and the calculations adjusted accordingly.This assumes that when the MS passes overhead, it travels straight through the center of the satellite footprint. In various scenarios, the BTS and / or MS can take into account this value of 159.86 seconds to plan and adjust communication and scheduling.

[0098] The actual distance may vary depending on atmospheric effects and other physical interactions. In this example, the BTS is then configured to support communication with devices in the range of approximately 500 km to 741 km between the BTS and the MS, and it is necessary to support the MS when those MSs view the BTS at an elevation lower than 40 degrees from the local horizon. In some implementations, the lower limit is reduced from the orbital distance to enable communication with MSs well above the surface of the Earth. For example, if the MS is located inside an airplane flying at 15,000 meters and the satellite assumes a minimum distance of 485 km, it cannot support that MS. In another example, a satellite within a geostationary Earth orbit (GEO) may provide the BTS, in which case the minimum distance is approximately 35,786 km.

[0099] FIG. 1 illustrates an environment in which the present invention may be used. As shown therein, on the surface 102 of the Earth (or a planetary body or celestial body related thereto), there are several mobile stations (MSs) 104 that can be mobile, or in some cases portable or stationary, but can function as MSs. These MSs 104 communicate with an orbiting BTS 106 via a link 108 between the BTS and the MS. As illustrated, each of the BTSs 106 has an orbital velocity with respect to the surface 102 and a certain separation distance.

[0100] Figure 2 illustrates an additional example of the environment of Figure 1. Person 202 has various devices 204 including elements that make up mobile stations such as smart phone 204(1), laptop computer 204(2), and tablet device 204(N). Each of these is configured and / or adapted to communicate with a terrestrial BTS. If person 202 desires to communicate with or access the Internet 208 and / or Internet-connected resources 210, they can do so via BTS 206. Other examples of devices can be devices without a user interface, such as industrial or household devices that interact via a network (e.g., "Internet of Things" devices).

[0101] Figure 3 illustrates an example of a frame-based protocol used between a base transceiver station (BTS) 306 and a mobile station (MS) 304 via a surface-orbit link 308 that uses a protocol such as TDMA or other protocols that can also be used for terrestrial communication.

[0102] As described in the examples herein, the BTS uses various techniques that enable it to transparently support MSs that are configured solely for terrestrial cellular communication. Some examples will be described. First, some methods for range extension in a TDMA system will be described.

[0103] Figure 4 illustrates how a timing advance mechanism can be used. As should be understood, when a timing diagram is shown, it implicitly means that there is a corresponding module with logic that follows the timing diagram. Figure 4 also shows the effects of propagation delay and the use of timing advance when using a time-division protocol.

[0104] In FIG. 4, eight time slots of a TDMA frame are shown. These can be part of a larger data structure that has been omitted for clarity of explanation. If the MS or BTS has a time slot allocated for communication between the MS and BTS, each of the devices is programmed to determine, using the local copy of the system clock for each device, when to start transmission, when to stop transmission, when to start listening, and when to stop listening, which will correspond to their allocated time slots.

[0105] In FIG. 4, the top line illustrates a transmission 402 from the MS. In this specification, "Tx" is an abbreviation for transmission, transmitter, or transmitting, as the context may require. Similarly, "Rx" is an abbreviation for reception, receiver, or receiving, as the context may require. As used in this specification, "transmission" is what is sent from a transmitter as part of a communication or signal, and "reception" is what is received. If the transmitter and receiver have the same system time and there is a measurable propagation delay, the transmission and its corresponding reception do not occur at the same system time. From the perspective of the MS, the process of transmitting transmission 402 occurs entirely within time slot 1, where it is assumed that time slot 1 is allocated to the MS. If transmission 402 occupies most of the allocated time slot, it is received as reception 404, which is received partially during time slot 2, when it is received at the BTS as BTS Rx after propagation delay. This is not desirable. With timing advance, the MS transmits transmission 412 before time slot 1 starts (from the MS's clock timing), and when it is received at the BTS as reception 414 after propagation delay, it is completed entirely within time slot 1 at the BTS.

[0106] Figure 5 shows an example of the use of the extended range feature of the time division protocol. The duration of the time slot in this example is approximately 0.28 milliseconds, representing a distance of 85 km. Therefore, if the MS can delay the transmission at the BTS for only the duration of one time slot, it can communicate with the BTS without any need for timing advance. The extra time slots serve as additional guard periods.

[0107] As illustrated in Figure 5, the MS has eight time slots, but only the first (slot 0), third (slot 2), fifth (slot 4), and seventh (slot 6) time slots are being used. As shown, MS1 performs transmission 502(0) during time slot 0, MS2 performs transmission 502(2) during time slot 2, MS3 performs transmission 502(4) during time slot 4, and MS4 performs transmission 502(6) during time slot 6. The BTS receives such transmissions and receives a reception 504(0) that starts at any time after the start of time slot 0 and ends at any time before the end of time slot 1 (referred to as "(0)" in the figure). Similarly, the BTS receives a reception 504(2) that starts after the start of time slot 2 and ends at any time before the end of time slot 3 ("(2)"), and the same applies to receptions 504(4) and 504(6).

[0108] Figure 6 shows an example of the use of the extended range feature and the use of timing advance in the time division protocol. As shown there, the MS transmission 602 is between their respective time slots, and the BTS receives such transmission and receives the reception 604 at the appropriate time. As illustrated in Figure 6, in the combination of the timing advance mechanism and the extended range mechanism, the maximum allowable MS - BTS can be 35km + 85km = 120km. Regardless of whether the timing advance mechanism is used alone, the extended range mechanism is used alone, or both are used, the BTS can manage which one to use. The MS may not even notice whether the extended range mechanism is being used because the BTS will not allocate time slots to every other one. For example, if the BTS determines that the MS is 60km away, the BTS may tell the MS to use 0 bits of timing advance (i.e., not use timing advance) and may not allocate the next time slot to any MS. If the BTS determines that the MS is 95km away, the BTS may tell the MS to use 18 bits of timing advance and may not allocate the next time slot to any MS.

[0109] Figure 7 shows an example of various MSs at different distances from the BTS, and those distances are at least approximately determined. In this example, there are seven MSs labeled A - G with respective pseudo - distances between d A ~d G . This illustrates how the MSs can be sorted by distance.

[0110] Figure 8 illustrates how various MSs at different distances from Figure 7 are allocated to time slots based on their determined distances and provided for sorted extended range communication. As shown in Figure 8, time slot 0 is allocated to user G, the closest user to the BTS in Figure 7, and time slot 6 is allocated to user E, the farthest user from the BTS in Figure 7. Only 7 time slots are allocated. Considering the range of propagation delays, transmissions 802 from various MSs are received as receptions 804, such that transmissions 802 do not overlap with other transmissions 802, and all receptions 804 are received within the TDMA frame period. As illustrated in Figure 8, signal bursts are gradually delayed over time slots that can eliminate collisions and interference.

[0111] The sorted extended range scheme has a higher throughput than the extended range mechanism, but can still tolerate an MS - BTS distance of up to 120 km and up to 7 / 8 of the maximum frame capacity (as long as the separation between the distances of two sorted MSs does not exceed 85 km in total). In some cases, two or more time slots will be allocated so as to be separated by a distance separation. Thus, if N time slots are allocated in this way, N is between 1 and 7, and the throughput will be 1 - (N / 8) of the maximum frame capacity. If the time slot is 156.25 bits, the separation can be allocated as the number of bits distributed between time slots. When this logic is implemented by the BTS, an implementation example of the sorted extended range mechanism requires no modification to the logic or operation of the MS, since the BTS arranges the calculated time slot allocations.

[0112] Figure 9 illustrates the distance range of a BTS using a ring extended range mechanism and the coverage area of a ring scheme using a synchronization offset. The cross - hatched area is the area supported by the BTS. If the BTS assumes that all MSs are at least d * apart, the minimum communication distance d *MSs closer than this are not supported. Using the 35 km range obtained using the timing advance mechanism, without any modification to the MS, the MS-BTS distances from d * ~d * +35 km can be supported. In one example, d * = 85 km, but other minimum communication distances can be used. In that case, in this example, the BTS can support MSs in the range 85 km to 120 km from the BTS.

[0113] Figure 10 illustrates the transmission and reception timings, and how the timings are adjusted for the ring system. The minimum communication distance d * is directly scaled by the time slot synchronization offset selected for use by the BTS on the uplink subchannel. At the MS, transmission 1002 that the MS sees as time slot 0 is transmitted by the MS. At the BTS, reception 404 is received after a propagation delay that is at least d * times the speed of light. Since the value of d * times the speed of light is known, the BTS can simply offset the timing of that time slot by an offset (T_offset = 2×d * / (speed of light)) minutes, where 2 takes into account the round-trip distance between the MS and the BTS, and the BTS receives reception 1004 within the BTS's time slot 0.

[0114] Figure 11 illustrates a satellite footprint, an example of a ring, and the resulting distance ranges of that ring of the satellite footprint. Satellite 1102 will have a coverage footprint that is illustrated as footprint 1104 side-on in Figure 11 and as footprint 1106 from above. The different cross-hatched portions within footprint 1106 indicate different distance ranges between the surface and the BTS that form the ring. In this example, there are seven rings, but more or fewer rings may exist as required. In this example, the rings are from r 0 ~r 6It is labeled with , and corresponds to the distance between the BTS-MS (which can be a pseudo-distance range) {500 - 534.4, 534.4 - 568.9, 568.9 - 603.3, 603.3 - 637.7, 637.7 - 672.1, 672.1 - 706.6, 706.6 - 741} (all in km). Each of these ranges happens to be just less than 35 km, which is a useful design choice as will be explained below. For other applications, different design choices may be used. In an initial handshake such as the RACH process, the distance between the BTS-MS is determined, from which the MS can be assigned to one of the rings within the satellite footprint.

[0115] As will be explained below, all of the MSs assigned to a particular one of the rings can be assigned to one carrier frequency, or a block of carrier frequencies transmitted on a TDMA / FDMA frame, or other techniques can be taken. In some embodiments, the rings may overlap such that an MS can be in more than one ring. For example, the first two rings can be 490 - 540 and 530 - 580, so an MS at 535 km from the BTS can be in either of these rings.

[0116] Depending on the desired application, the orbital BTS can adjust its protocol and operation according to (1) the timing advance method, (2) the extended range method (using fewer time slots than all available time slots and instead using the unused time slots as guard bits), (3) the sorted extended range method (using fewer time slots than all available time slots and instead using the unused time slots as guard bits assigned between the time slots to which time slots are allocated based on the expected variable delay), (4) the ring extended range method (offsetting the timing so that the coverage is a ring with an inner circle that is not supported), (5) the multiple ring extended range method (similar to method (4), using multiple rings to simultaneously cover different ranges and the MSs assigned to the rings based on the distance between the BTS-MS), and (6) the sorted channel-ring assignment method (similar to method (5) and using different rings associated with different carrier frequencies, and for the carrier frequencies, using method (3) to allocate time slots to the MSs within the distance range of that ring), or can be adjusted according to one or more combinations of (1), (2), (3), (4), (5), and (6).

[0117] Timing Advance, Ring, and Sorted Extended Range Methods Figure 12 illustrates a first example of a BTS using the timing advance method, the ring extended range method, and the sorted extended range method. Therein, different time slots can be allocated to different mobile stations based on their terrestrial locations to implement the sorted extended range method for TDMA communication, and the ring method can be used to make the range terrestrial.

[0118] In this example, satellite 1202 is in orbit at an altitude of d * and there is no need for satellite 1202 to support MSs closer than d * and a maximum distance d maxIt is assumed that there is no need to support MSs that are far away. In this example, there are five MSs, MS1 to MS5, labeled by the distance from the BTS, which is in the range of d * ~d max . MSs MS1 to MS5 are respectively allocated to time slots 4 to 0, and time slots 5, 6, and 7 are not allocated. Therefore, they can be used in three time slots that value the sorted extended range method as guard time. This corresponds to about 486 bits and is illustrated in MS frame 1204. As a result of the distance between the MS and the BTS, signal bursts of MS1 to MS5 are received as shown in the BTS frame 1206 shown.

[0119] In this example, the timing advance is 22 bits (required for a range of 12 km), and the ring synchronization offset is 875 bits, which corresponds to a distance of about 488 km. Therefore, d * is about 488 + 12 = 500 km. The guard time of the extended range uses up three time slots, but provides a full range of about 295 km of the MS - BTS distance (i.e., d max -d * ). Assuming a maximum range of 35 km that can be 0 to 63 bits for timing advance, the range of the sorted extended range method can be about 35 km to about 640 km depending on the number of time slots allocated to the guard time, as shown in Table 1. Table 1 assumes that the full range of 0 to 63 bits of timing advance is available.

Table 1

[0120] This TDMA frame structure enables wide cellular coverage based on satellites over a large geographical area. Even with this solution, there are still operational problems and issues that need to be solved. First, each frame has slightly more than half of the potential throughput of a typical GSM frame. Second, in this configuration, each frame is subject to a variable Doppler shift between approximately plus or minus 35 kHz (which varies for each solution depending on orbit selection, slant range, frequency use, etc.). However, the problem of Doppler shift can be mitigated using the methods and apparatus of the BTS on the orbit described herein. The timing issue can be solved using the following methods.

[0121] Timing Advance and Allocation Method between Sorted Channel - Rings Figure 13 illustrates how different channels are allocated to different mobile stations based on their terrestrial location with respect to their BTS so that the ring method can be used with varying ring diameters for different channels. As shown there, the method using Timing Advance (for ranges of about 0 - 35 km), and the allocation method between sorted channel - rings can provide another range of about 241 km without using up time slots. In the allocation method between sorted channel - rings, as illustrated in Figure 11, the satellite footprint is divided into rings, and each ring is paired with an individual carrier frequency. Each ring operates with a different synchronization offset.

[0122] As used herein, a channel may include one or more specific frequency divisions within a protocol, such as a group of carrier frequencies. In FIG. 13, the range of the virtual distances supported between the nearest potential target and the farthest potential target is 241 km, which is distributed among seven rings of virtual distance ranges. This results in a coverage range of approximately 34 km per ring, and the synchronization offset can vary for different rings assigned to a channel block or set of channels. By keeping the offset between channel blocks below approximately 35 km, full throughput becomes possible within each channel by eliminating the need for an extra slot guard period, and then the timing advance by itself becomes sufficient.

[0123] Using the RACH request burst, the propagation distance from the signal of each MS can be determined. The BTS can always or periodically notify the MSs on the RACH, using the broadcast channel (BCCH), about which carrier frequencies and time slots the BTS assigns to that MS for uplink use. The BTS will know exactly when the MS transmits its RACH burst and can count the number of bits between that time and the time the actual burst arrives. By dividing that number of bits by the channel bit rate (270.83 kbps in the case of GSM), the BTS can calculate the round-trip propagation delay time. Then, the BTS can calculate the propagation distance or virtual distance by dividing the speed of light by the round-trip propagation delay time. Depending on the calculated virtual distance, each MS modifies its assignment to channels within a specific channel block. For example, in the configuration shown in FIG. 13, the channels within channel block b 0 are assigned to MSs that have calculated a virtual distance of 500 km to approximately 534 km, and the channels within channel block b 1 are assigned to MSs that have a virtual distance measured from the orbiting BTS of approximately 534 km to approximately 568 km, and the same applies to the other ranges shown in FIGS. 11 and 13.

[0124] The first channel block b 0 has an uplink TDMA frame offset by the same amount as shown in FIG. 12 from the transmission uplink frame. The next channel block b 1 has a frame offset by approximately 62 additional bits from the frame of channel block b 0 . Thereafter, the frame of each channel block has an additional offset of approximately 62 bits compared to the previous channel block (i.e., the frame of channel block b i+1 is offset by approximately 62 bits more from the frame of channel block b i ). Each bit of the frame offset corresponds to approximately 555 m, and since each ring / channel block is extended by approximately 34 km more than the previous one, this configuration that utilizes 62 bits creates various coverage rings of approximately 34 km each. By allocating different synchronization offsets, each channel block indicates the coverage of different rings of the universe (and the Earth's surface). When a synchronization offset is given to the channel block in increments of 62 bits and the traditional implementation of GSM is used, full throughput can be achieved in all channels, and a very extensive coverage can be realized. This can be done without requiring modification of the GSM MS. A downward view of the range rings is shown in FIG. 11. The channel blocks of each range ring are defined by the characteristic "range of distance" defined for this particular implementation by the key on the left in FIG. 11.

[0125] Handling of Doppler shift The above methods and their variants may provide the maximum throughput of all channel spectra, but due to the relative movement of the BTS and MS, the transmission frequency may be different between transmission and reception. Using Doppler solutions, scenarios can be considered where multiple MSs are within a similar pseudo-distance range from the orbiting BTS but may experience a wide range of variations in the perceived carrier frequency offset. For example, in FIG. 11, for the same ring / channel block b 6Consider two MSs calculated to be present within. In this case, one MS is positioned at the tip in front of the top of the satellite coverage footprint and the other is positioned at the tip of the bottom of the satellite coverage footprint.

[0126] In Figure 11, the satellite is directly above the center of the coverage area shown for channel block b 0 (origin of the arrow) and is moving in the direction of the arrow labeled "velocity". The first MS in front of the satellite's velocity vector experiences a positive Doppler shift within the received frequency, and the second MS behind the satellite's velocity vector experiences a negative Doppler shift within the received frequency. If the same frequency is assigned to these MSs, the satellite can receive signal bursts at frequencies that are several kilohertz apart (up to 70 kHz apart in the case of the 1800 / 1900 GSM band). Furthermore, allocating adjacent channels to MSs that experience significantly different Doppler shift environments can result in signal interference at the satellite.

[0127] Figure 14 shows how the satellite footprint can be subdivided into Doppler shift strips in a way that mitigates this problem. As illustrated there, assume a satellite 1402 moving at a certain velocity relative to the surface 1404 of the Earth. The satellite footprint 1406 is the view from the satellite at the shown velocity. MSs within the vector area 1410 of the satellite footprint 1406 experience a positive Doppler shift within the received frequency of the signal from the satellite 1402, while MSs within the vector area 1412 of the satellite footprint 1406 experience a negative Doppler shift within the received frequency of the signal from the satellite 1402. A particular Doppler shift within the received frequency can be determined using simple geometry, and for the range of Doppler shifts, the satellite footprint 1406 can be divided into strips delineated by contour lines to which values 1420 for their respective Doppler shifts can be assigned.

[0128] In three-dimensional space, considering sufficient information, the Doppler shift at any point within the satellite footprint can be calculated by the BTS or the MS. One way to do so may assume that all vectors are represented in the Earth-Centered, Earth-Fixed (ECEF) coordinate frame. This is also known as the Earth's rotation frame since it is a coordinate system that rotates the Earth in space about its axis of rotation. In this process, each of the vectors is treated as a vector quantity with three component values, and as a result, each component value within the vector represents a value along each dimension of the coordinate frame represented by the vector. Such numerical values can be stored in memory for the processor to operate on.

[0129]

Number

Number

Number

Number

Number

Number

Number

Number

Number

Number

Number

[0130] In Equation 1, D is the calculated Doppler shift and λ is the wavelength of the carrier frequency that can be calculated when the carrier frequency is divided by the speed of light

[0131] As an example, consider a spacecraft operating in an equatorial orbit at an altitude of 500 km and happening to be directly above the meridian at a particular instant (e.g., where the direct nadir to the satellite is the intersection of the equator and the meridian). At the same particular instant, the stationary MS1430 is positioned approximately below the sea surface of the spacecraft but is resting on the equator at 1 degree east longitude (e.g., the latitude and longitude position can be described as [0, 1]).

[0132] In this scenario, the ECEF position coordinates of the satellite are approximately [6870 km, 0 km, 0 km]. The velocity vector of the spacecraft in a circular orbit at 500 km is approximately perpendicular to the position vector and (in the case of an equatorial orbit) parallel to the equator. The magnitude of the velocity vector relative to the Earth's surface can be calculated as SQRT(mu_earth / (R_e+h)) - w_earth*(R_e+h) = 7.11 km / s, where mu_earth is the gravitational constant of the Earth (mu_earth = 398658.366 km 3 / s 2 ), R_e is the radius of the Earth at the equator (R_e is approximately 6370 km), w_earth is the angular velocity of the Earth's rotation (w_earth = 7.27*10 -5 radians / second), and h is the altitude of the satellite (in this example, h = 500 km). Thus, the ECEF velocity vector of the spacecraft is approximately [0 km / s, 7.11 km / s, 0 km / s]. The ECEF position of the MS stationary at 0 degrees latitude and 1 degree east longitude is approximately [R_earth*cos(1 degree), R_earth*sin(1 degree), 0] = [6369 km, 111 km, 0]. Thus, the ECEF position of this stationary MS relative to the spacecraft is [6369 km, 111 km, 0] - [6870 km, 0 km, 0 km] = [-501 km, 111 km, 0]. Thus, the Doppler shift of the 1900 MHz signal received by this MS from the spacecraft is as shown in equations 2, 3, and 4.

Number

[0133] As described above, the pseudo distance can be calculated using the signal received by the BTS from the MS on the RACH. The signal can also be used to approximate the Doppler shift from the MS. The BTS knows the carrier frequency that is on, just as it knows the time slot during which the RACH is on. Therefore, when the BTS receives a RACH burst, it can measure the center of the burst frequency and calculate the offset (difference) from the expected center frequency on the RACH. Depending on the magnitude of the Doppler shift experienced by the system, there may or may not be a case where the satellite BTS needs to listen over a wider frequency range on the RACH.

[0134] Figure 15 is a flowchart of the measurement process that can be used by the BTS for the RACH to determine the pseudo distance and Doppler shift from the MS. The RACH can be indicated when the MS wants to start a session (e.g., send an SMS text, make a phone call, transmit data). It is not necessary to repeatedly measure / update the value of the Doppler shift. The value of the Doppler shift changes with the time taken to request access to the channel and transmit data, and the payload is typically not large enough to degrade the capabilities of the system for sending and receiving signals. In cases where this can be a problem, the BTS can make predictive changes and assume that the MS is not moving at high speed. This process can be used by the satellite BTS when managing the measured values of the pseudo distance and Doppler shift to adjust the channel allocation.

[0135] As illustrated in the flowchart of FIG. 15, at the start of the process, the satellite BTS notifies the RACH timing information on the BCCH channel (step 1501), and then the MS learns the time slot in which the RACH is on (step 1502). Knowing this, the MS transmits a burst during the RACH time slot indicated by the BTS for the MS to use (step 1503). The burst reaches the BTS with the frequency delayed and offset (step 1504). Next, the BTS flow has two threads, one for the delay and one for the Doppler shift. In the first flow, the BTS counts the number of bits by which the burst is delayed (step 1505), divides the counted number of bits by the channel bit rate to calculate the round-trip delay (step 1506), and then divides the round-trip delay by twice the speed of light to calculate the pseudo distance (step 1507). In the second flow, the BTS measures the center frequency of the burst (step 1508), subtracts the center frequency from the center frequency of the RACH to calculate the Doppler shift (step 1509). Next, the two threads are combined, and the BTS checks the channel configuration matrix to allocate a channel configured for the MS for its pseudo distance and Doppler shift (step 1510). Then, the BTS checks whether the channel is already configured (step 1511). If "yes", the BTS allocates the configured channel to the MS (step 1513), if "no", the BTS configures a channel for the detected MS's pseudo distance and Doppler shift environment (step 1512), and the process ends.

[0136] Since the BTS can acquire knowledge of Doppler shift from each MS, it can allocate a specific Doppler shift range to a specific channel. When doing this, each of the individual channels can have its own, specific locally reduced range of potential Doppler shift values. For example, some channels may only experience a shift of 0 to 5 kHz within the carrier frequency because the channel is allocated to an MS within a specific strip shown in Figure 14, while other channels will experience only a shift of 25 to 30 kHz within the carrier frequency. Since the Doppler range is clearly defined and more localized for each channel, it can be used as a modifier for channel assignment and allocation. This way, it is much simplified to handle the wide variation of Doppler shifts across the entire set of serviceable MSs within the satellite footprint.

[0137] Referring back to Figure 14, that figure illustrates the Doppler shifts perceived at various locations across the satellite coverage footprint. Intuitively speaking, half of the satellite footprint in the direction of the velocity vector experiences a positive Doppler shift and the other half experiences a negative Doppler shift. What is less intuitive is that the geometry of the curvature of the earth creates a Doppler shift map on the satellite footprint depicted by a gradually curving contour line.

[0138] One approach described herein is to assign channel blocks to pre-determined Doppler shift blocks in the same way that channel blocks are assigned to rings of pre-determined pseudo-range. When a carrier frequency is assigned to a specific pseudo-range and Doppler shift, the actual Doppler shift experienced at each channel is unique to the frequency of that channel. An implementation example of this approach will consider this. In one design, the contour map of the Doppler shift uses the center frequency of the underlying spectrum and in the figure, a 1900 MHS GSM with a satellite at an altitude of 500 km and an elevation angle of 40 degrees is assumed.

[0139] In FIG. 14, each dashed line defines the boundary of a Doppler shift strip that is used to localize the potential Doppler shift of each channel and thus minimize interference. The curvature of the contour lines on the map is the result of the geometry of the communication link and the communication frequency.

[0140] FIG. 16 shows how a satellite footprint can be subdivided into range rings, Doppler shift strips, and both range rings and Doppler shift strips. As illustrated, the range of the pseudorange forms a ring and the contour of the Doppler shift forms a strip. When these are overlaid on a grid (not necessarily an orthogonal or linear grid), the satellite footprint 1602 is divided into grid cells bounded by a first distance value, a second distance value, a first Doppler shift value, and a second Doppler shift value. Thus, each of these grid cells corresponds to a combination of a range of pseudorange and a range of Doppler shift to the BTS on the orbit and is a modifier of the MS assigned to a particular channel (or one of a particular set of channels).

[0141] Note that the satellite footprints represented herein are essentially circular, but this is not essential. The footprint can be more square or elliptical in shape depending on which antennas are being used on the satellite and how they are configured. A non-circular footprint can offer the advantage that it can increase or decrease the spread of the propagation delay and / or Doppler shift environment within the footprint.

[0142] This grid represents a combination of a range of pseudo-distances and a range of Doppler shifts corresponding to the modification of the pseudo-distances and Doppler shift channel blocks. The grid cells described above are assumed to be symmetric with respect to the velocity vector of the satellite. This means that each grid cell off the centerline of the satellite's coverage area has a "twin" grid cell on the opposite side of the satellite footprint. The term "twin" grid cell is used because both MSs of these grid cells operate with similar pseudo-distances and Doppler shifts, so these two grid cells share "buckets" that are logically associated with the range of pseudo-distances and the range of Doppler shifts (i.e., an MS is logically assigned to a bucket based on whether the MS's pseudo-distance is within the range of pseudo-distances assigned to that bucket and whether the MS's Doppler shift is within the range of Doppler shifts assigned to that bucket).

[0143] Handling of Doppler shift for a particular MS device Some protocols may be more resilient to Doppler shift when demodulating downlink signals, while others may not. For some devices or some protocols, a 2.5 kHz offset can be the threshold of Doppler shift. However, even some lower-end cellular phones may be able to demodulate the BCCH signal with an offset of up to 20 kHz from what would typically be the center carrier frequency of that channel. This may be related to the interaction between the BTS and the MS on the FCCH (Frequency correction channel), another notification channel used to synchronize the local clock with the BTS. This synchronization is ultimately the information required for the phone to demodulate the BCCH and other downlink channels subsequently. Therefore, a Doppler shift strip larger than the exemplary 5 kHz strip used in the above example can be used. For example, the bucket can be adjusted and extended to adapt to a wider range of Doppler shifts in either direction up to at least 20 kHz. In practice, this can prevent the need for bucketing of Doppler shift if the satellite footprint is small enough that the highest Doppler shift case is less than 20 kHz. This may not be the case for other protocols such as NB-IoT that use a much smaller signal bandwidth. NB-IoT also has other differences, such as when the multiplexing protocol is the LTE NB-IoT protocol and the limited range is 40 km, which exceeds the base-mobile distance.

[0144] Channel Assignment As described herein, a BTS can support multiple transceivers, each using its own carrier frequency, and each of the multiple transceivers can then support up to eight MSs. Since a transceiver can be set to use one of many possible carrier frequencies, a channel can be associated with a transceiver. In the example above, there are 123 available carrier frequencies. Some of these many carrier frequencies can be allocated to the MSs as needed, but if they are allocated by grid cells, some advantages can be obtained, so that buckets of similarly positioned MSs having a similar distance from the BTS and using the same carrier frequency(ies) and the same Doppler shift can be strategically allocated. (Logically, as described above, it can include an uplink subchannel and a downlink subchannel.) A channel can be allocated one of the multiple time slots and one of the multiple carrier frequencies. A channel can be identified only by its allocated characteristics, such as the carrier frequency of the channel and the time slot of the channel, but in some situations, each channel is given a channel label. The label of a channel can encode the carrier frequency of the channel, the time slot of the channel, and possibly the timing advance of the channel, as well as the Doppler shift, which can be something simple like a sequential number, and the BTS and / or MSs include a stored mapping of the channel number label to the allocated characteristics (e.g., channel 1 uses carrier frequency f 1 and time slot 0, and channel 2 uses carrier frequency f 7 and time slot 3, etc.).

[0145] Figure 17 illustrates an example of a range ringing / Doppler shift cell of a satellite footprint. The intersections of the pseudorange rings and the Doppler shift strips form the footprint grid. Channels can be allocated to grid cells, range ringing / Doppler shift cells.

[0146] FIG. 18 illustrates an example of the assignment of the range ring / Doppler offset cells of FIG. 17 to specific carrier frequencies and Doppler offset blocks. A logical channel block may be associated with one or more carrier frequencies and / or time slots on a TDMA frame that uses those carrier frequencies. In FIG. 17, the channels are shown with arbitrary channel labels, in this case 1 to 70. They happen to be labeled in order from bottom to top, i.e., from the most negative Doppler offset to the most positive Doppler offset. Channels 1 to 70 may correspond to channels assigned to each of eight time slots within a frame using eight carrier frequencies, and six time slots within a frame for another carrier frequency.

[0147] The diagram of FIG. 17 shows how channel numbers are assigned to the grid cells of the satellite footprint. It should be understood that only the left side of the footprint is shown numbered, but the twin cells on the right are also assigned these channel numbers. The channel assignment table of FIG. 18 shows that each channel number is associated with a Doppler offset strip (D 0 ~D 13 ) and a channel block (b 0 ~b 6) illustrates a channel assignment scheme associated with, assigned to, or allocated to a Doppler offset block corresponding thereto. Note that in other embodiments, the number of channels may vary depending on how the pseudo-range and Doppler shift of the MS are "binned". Multiple channels can be assigned to grid cells. In the examples of FIGS. 17 and 18, for simplicity, one channel number is assigned to each grid cell. Since the grid cells are symmetric with respect to the satellite velocity vector, only half of the grid cells are filled with channel assignments. In an actual implementation example, the unfilled grid cells are assigned the same channel number as the grid cells on the opposite side within the contour map. This is because the symmetric grid cells exist at different physical locations on the contour map (and in the real world), but they represent the same modified parameters in terms of pseudo-range and Doppler shift from the BTS on the orbit.

[0148] Pinching and Fraying The "pinching and fraying" feature of the BTS design is useful when the uplink subchannels are within the continuous spectrum and the downlink subchannels are within the continuous spectrum and the Doppler shift can be greater than the signal bandwidth, but they do not have to be so in order to implement the following techniques.

[0149] The table of FIG. 18 is a channel allocation matrix, which is used to determine how the BTS on orbit allocates channels to the MS, and will allocate them in a way that adjacent carrier frequencies are allocated to adjacent numbers. When a signal burst is received on the RACH, the appropriate grid cell is found using the calculated Doppler shift and the estimated value of the calculated pseudo distance, and by searching for the channel number of the MS from the table, it is determined which channel should be allocated to that MS. In this example, since not all channel blocks correspond to pseudo distances that can experience the full range of Doppler shift, not all channel blocks (columns in FIG. 18) have the same number of actual channels that are in use or available. The BTS may store a copy of this table and have different versions of this table for use when allocating channel numbers based on the grid cell.

[0150] The advantage of channel allocation where channels are allocated in the order of grid cells having a specific Doppler shift is illustrated in FIG. 19. Since the spacecraft actively allocates channels based on the expected Doppler shift, there is no longer a need to consider a wide range of shifts within the received frequency, etc. Instead, the BTS on orbit can instruct the existing MS infrastructure to communicate at a certain carrier frequency, but listen at a slightly shifted carrier frequency depending on how much Doppler shift is expected at that channel. This reduces interference between adjacent carrier frequencies in the spacecraft segment.

[0151] In this particular embodiment, the profile of the Doppler shift is spaced at 5 kHz intervals, but other intervals can be used. Thus, for each channel allocated to the MS, the satellite BTS listens at the carrier frequency that is the average of the maximum and minimum Doppler shifts of the carrier frequency of that channel and checks for data bursts within the time slot allocated to that channel. For example, MS is allocated to channel 70, frequency F 70 and time slot TS 70is assumed to be logically associated with. The BTS on the spacecraft is the TS 70 will listen for the uplink signal from the MS at a carrier frequency of +27.5 kHz. In this way, there is no signal with an offset of more than 2.5 kHz from the frequency being listened to by the BTS. In the return link, the orbiting BTS can transmit the signal on channel 70 by transmitting a signal burst at 70 -27.5 kHz, so that the signal is received at the MS within the reasonable limits of the carrier frequency being listened to.

[0152] FIG. 19 shows a map of the uplink carrier frequencies and downlink carrier frequencies used by the MS and the BTS for communication. Specifically, FIG. 19 shows the Doppler blocks referred to in FIGS. 17 and 18, and the Doppler blocks have widths that are scaled based on the number of channels they hold. If the channels are assigned in ascending order of increasing carrier frequency as a function of some known Doppler effect, the uplink signals "wear" on each other and define the channels that the BTS selects for listening. This reduces interference at the orbiting BTS. Instead of "wearing" the downlink transmission frequencies, they are "pinched" to ensure that the signals have the appropriate carrier frequencies when they reach the MS. The Doppler blocks are referred to for both the uplink frequencies and the downlink frequencies, and it should be noted that this implicitly means that each channel has both uplink and downlink components. Other variations are possible.

[0153] Figure 19 shows that the BTS in orbit listens at a frequency slightly offset from the frequency transmitted by the MS. This is a result of the new channel assignment scheme, which reduces the interference and complexity of Doppler shift when communicating with the MS. In the downlink operation, the spacecraft transmits on more "pinched" channels, so that the signal reaching the target MS is at the correct frequency. The channel blocks are represented as the Doppler blocks referred to in Figures 17 and 18 and have a width that scales with the number of channels they hold.

[0154] Similarly, note that the channels can be assigned to the Doppler blocks in descending order of signal frequency. In this scheme, the effects of the received and transmitted signals from the perspective of the BTS are reversed. It is reasonable to assume that this technique may actually help enhance the ability to close the uplink signal from the MS. This is because the uplink signal will be "pinched" instead of being "offset" as shown in Figure 19. Since the amount of "pinch" is fairly well understood, the BTS in orbit will take advantage of this fact to intelligently narrow the bandwidth that the BTS "listens" to for each uplink channel. This would mean that the received uplink signals are separated by less than 200 kHz (similar to GSM). In this case, the BTS in orbit can, in theory, listen on narrower channels to reduce noise.

[0155] Some embodiments of the present invention may prefer channels that are "worn" or "pinched" at the BTS for both the uplink and downlink subchannels. To accommodate this, the implementer will allocate channels where the uplink signal frequency increases and the downlink signal frequency decreases. This will result in channels that are "worn" for the BTS's uplink reception function and downlink transmission function. Conversely, channels where the uplink signal frequency decreases and the downlink signal frequency increases will result in channels that are "pinched" for the BTS's uplink reception function and downlink transmission function.

[0156] Figure 19 illustrates each Doppler block with a channel as a box, but it should be understood that the boxes in Figure 19 that are worn or pinched can correspond to one or more carrier frequencies and one or more time slots. For example, in the case of Doppler block D 9 Figure 18 shows that channels 50 to 56 are allocated to the cells within the strip covered by that Doppler block. Channels 50 to 56 can represent seven time slots within a frame of one carrier frequency, one time slot within a frame of seven different carrier frequencies, or some other configuration.

[0157] Location Discovery In addition to data communication between the BTS and the MS, the BTS can be used to discover a location, i.e., to determine the geographical location of the MS with at least approximately or with sufficient resolution for various purposes (e.g., supporting remote search and rescue operations). When a satellite passes over the MS, the BTS of that satellite determines the grid cell of the MS (actually a pair of twin grid cells) as described above. When another satellite passes over the same MS, the BTS of that second satellite determines a pair of grid cells within the footprint of that second satellite. If the second satellite is in a different orbit from the first satellite, the symmetry line of the range ring of its pseudo-distance and the contour strip of the Doppler shift will be somewhat different from that of the first satellite. The BTS assumes that the MS has not moved or has moved only slightly on the scale of the satellite footprint, such that one grid cell of one satellite overlaps one grid cell of the other satellite, and the other two grid cells do not overlap. From this, the BTS can determine the likely location of the MS.

[0158] This may be used either alone or in combination with other location discovery systems.

[0159] Software-defined radio, dynamic allocation by density The BTS implements various functions described herein. The BTS may be implemented with commercial software-defined radios or may be programmed or configured with the specific functions provided herein. The software-defined radios may be reprogrammed in orbit to shift around the channel configuration of the BTS channel assignment scheme. This may be valuable when the MSs on the ground are not evenly distributed. For example, as illustrated in FIG. 20, when the BTS has a mapping of connected MSs or expected MSs, or when the BTS exhibits a specific Doppler shift range and obtains most of its requests from MSs operating within a similar pseudorange, the BTS may prefer a more congested grid cell with more channels. Thus, Doppler shift and pseudorange data can be used to proportionally allocate channel assignments. The right side of FIG. 20 is a diagram showing how many channels can be allocated to each grid cell. Only a semicircle is shown under the assumption that the satellite footprint is symmetric with respect to the satellite's velocity vector.

[0160] FIG. 21 illustrates an example of a channel assignment table that can be used for the assignments and mappings illustrated in FIG. 20, where the channel allocation is mapped with channels ordered using a channel assignment scheme. To reconfigure the channels serving a grid cell, the transceivers of those channels are reconfigured with a time slot synchronization offset different from the transmission TDMA frame, and the transceivers obtain an update of the configured frequency offset for receiving and transmitting on the uplink carrier and downlink carrier, respectively. When the channels are reconfigured and remapped to the channel assignment scheme, those channels may remain in count order (ascending or descending) from the lower right corner to the upper left corner of the channel assignment table as shown. The channel assignment table may be stored in an accessible computer-readable memory such that a processor controlling the software-defined radio can set the frequency and timing according to the channel assignment table.

[0161] In addition to remapping channels to blocks, software-defined radios on orbit can also reconfigure their block mappings. For example, when MSs are densely packed, the BTS can reconfigure the channel assignment scheme at finer intervals of pseudorange and Doppler shift to improve the service, especially the throughput, in a specific geographical area. Further, the BTS on orbit can set the minimum and maximum time slot synchronization offsets and Doppler compensation for its channels based on the minimum and maximum measured values of pseudorange and Doppler shift, respectively. Thereby, the BTS can more precisely define the grid cells of its satellite footprint and more efficiently allocate channels to serve the high-density pockets of MSs. When the interval of the Doppler blocks is finer, the influence of the Doppler shift on each channel is further reduced, while when the interval of the pseudorange range ringing is made finer, the potential throughput at more specific ring locations increases to serve more densely packed MSs.

[0162] In on-orbit processing, the known velocity of the satellite can be utilized to predict the movement of the satellite footprint and, thus, the profiles of the pseudorange and Doppler shift with respect to the MSs to which the satellite provides services. This will enable the satellite BTS to predict which pseudorange buckets and Doppler shift buckets will require channel allocation in the near future and which will not, and the predictability will allow for a more accurate execution of the reconfiguration of the channel allocation scheme. Since there is a certain lead time associated with channel reconfiguration, the predictability can be greatly exploited to ensure that the downtime of that channel is limited. For example, to account for this lead time of channel reconfiguration, the on-orbit BTS can "juggle" or reserve one or more channels so that the carrier frequency serving the MS does not have to suddenly stop service due to reconfiguration. Since the channels must be configured in ascending or descending order of frequency, reconfiguration sometimes creates a domino effect and may require reconfiguring many channels to maintain this important frequency order in the channel allocation scheme. For example, consider an on-orbit GSM BTS with access to 80 channels within the GSM spectrum. Assuming the channels are labeled from 1 to 124, all odd channels (i.e., 1, 3, 5, 7, etc.) can be configured to serve the MS, while all even channels (i.e., 2, 4, 6, 8, etc.) can be "juggled" or reserved. When the need for reconfiguration arises, the on-orbit BTS can reconfigure the "juggled" channels without disturbing service on any of the other 62 already-configured channels. If a configured channel no longer serves the MS, that channel can be reserved or cycled into the set of "juggled" channels, and the process itself repeats to maintain consistent service and limit channel downtime.

[0163] The BTS on the orbit can be programmed to further enhance the quality of the services of such a network using real-time measurements of the pseudo-distance, Doppler shift, and other data (i.e., GPS) of the MS. Examples include reallocation or shift of channels based on large datasets collected over time and many satellite passes (based on the relatively static location of the MS), and more dynamic real-time shifts based on changes in the MS distribution detected by a spacecraft that passed through this location immediately prior to the current spacecraft, or even by the current spacecraft itself.

[0164] The dynamic channel allocation described above can also be done in a way that reserves a particular channel for a particular MS or geographical location that the satellite passes over in its entirety. In other words, the Doppler shift and pseudo-distance profile of a particular channel, when plotted over time, is described by a somewhat smooth function that matches the Doppler shift and pseudo-distance environment experienced by a particular MS or geographical location over its pass course. This embodiment can be strategic when a particular MS on the surface needs to maintain a locked link with the satellite for a longer period (e.g., minutes rather than seconds) or under conditions where it can benefit from such a link.

[0165] Consider the case illustrated in FIG. 20 where the connected MS is "clamped" and in some cases operating in a remote area. As a note, the map only shows half of the satellite footprint because the pseudo-distance buckets and Doppler shift buckets are symmetric with respect to the satellite's velocity vector. When the spacecraft collects pseudo-distance and Doppler shift data from these users, it can strategically proportionally allocate channels in its channel assignment scheme and, based on this proportional allocation, reprogram the channels to shift their service configurations. Such techniques can also utilize predictive data analysis software. The BTS in orbit can closely combine past MS data and GPS navigation data to predict where and when it will cross pockets of customers concentrated within its footprint. The GPS data from the MSs actually being served can also be used to further enhance channel predictive analysis and assignment, as well as tracking applications. This can be promoted to increase the service quality of such a network.

[0166] FIG. 22 illustrates a process for determining MS parameters in the RACH process. By measuring the propagation delay from the MS uplink burst, the BTS can calculate the timing advance required for each MS to transmit the burst at the correct time. The RACH process can be: (1) the MS listens to the BCCH when it camps on the BTS; (2) the MS user types a text message and strongly presses "send"; (3) the MS requests access to the channel by transmitting a burst on the RACH using the information provided on the BCCH; (4) the BTS searches for a channel allocation and responds with the channel allocation and timing advance (in bits); and (5) the MS advances the burst for the allocated time slot using the timing advance and uses the allocated frequency carrier.

[0167] In a more schematic case illustrated in FIG. 22, the MS requests the allocation of a dedicated signaling channel to perform call setup, and after the allocation of the signaling channel, a call setup request for the MOC including the TMSI (IMSI) and the last LAI is transferred to the VLR. The VLR requests the AC via the triple HLR (if necessary). The VLR then begins authentication, encryption start, IMEI confirmation (optional), and TMSI reallocation (optional). If none of this causes an error that requires cancellation of the process, the MS sends setup information (the requested subscriber number and a detailed service description) to the MSC, and the MSC requests the VLR to confirm (from the subscriber data) whether it can handle the requested service and quantity (or whether there are restrictions that prevent further processing of the call setup).

[0168] If the VLR indicates that the call should be handled, the MSC instructs the BSC to allocate a traffic channel to the MS, and the BSC allocates the traffic channel TCH to the MS. The MSC then sets up a connection to the requested number (calling party).

[0169] According to one embodiment, the techniques described herein are implemented by one or more general-purpose computing systems programmed to perform the techniques according to program instructions in firmware, memory, other storage, or a combination. Dedicated computing devices such as a desktop computer system, a portable computer system, a handheld device, a network device, or any other device with hardwired logic and / or program logic incorporated to implement the techniques can be used.

[0170] For example, FIG. 23 is a block diagram illustrating a computer system 2300 in which an embodiment of the present invention can be implemented. The computer system 2300 includes a bus 2302 or other communication mechanism for communicating information, and a processor 2304 coupled to the bus 2302 for processing information. The processor 2304 can be, for example, a general-purpose microprocessor.

[0171] The computer system 2300 also includes a main memory 2306, such as a random access memory (RAM) or other dynamic storage device, coupled to the bus 2302 for storing information and instructions to be executed by the processor 2304. The main memory 2306 can also be used to store temporary variables or other intermediate items during execution of instructions by the processor 2304. When such instructions are stored on a non-transitory storage medium accessible to the processor 2304, the computer system 2300 is rendered a special-purpose machine customized to perform the operations specified by the instructions.

[0172] The computer system 2300 further includes a read only memory (ROM) 2308 or other static storage device coupled to the bus 2302 for storing static information and instructions for the processor 2304. A storage device 2310, such as a magnetic disk or optical disk, is provided and coupled to the bus 2302 for storing information and instructions.

[0173] The computer system 2300 can be coupled via a bus 2302 to a display 2312, such as a computer monitor, for displaying information to a user of the computer. An input device 2314 including alphanumeric and other keys is coupled to the bus 2302 for communicating information and command selections to a processor 2304. Another type of user input device is a cursor control 2316, such as a mouse, trackball, or cursor direction keys, for communicating direction information and command selections to the processor 2304 and for controlling movement of a cursor on the display 2312. This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), whereby the device can specify a position within a plane.

[0174] The computer system 2300 can implement the techniques described herein using customized hardwired logic, one or more ASICs or FPGAs, firmware, and / or program logic that in combination with the computer system 2300 causes or programs the computer system 2300 to be a special-purpose machine. According to one embodiment, the techniques herein are performed by the computer system 2300 in response to the processor 2304 executing one or more sequences of one or more instructions contained in the main memory 2306. Such instructions can be read into the main memory 2306 from another storage medium, such as a storage device 2310. Execution of the sequences of instructions contained in the main memory 2306 causes the processor 2304 to perform the process steps described herein. In an alternative embodiment, hardwired circuitry can be used in place of, or in combination with, software instructions.

[0175] As used herein, the term "storage medium" refers to any non-transitory medium that stores data and / or instructions for operating a machine in a particular manner. Such storage media can include non-volatile media and / or volatile media. For example, non-volatile media can include optical disks or magnetic disks such as storage device 2310. Volatile media can include dynamic memory such as main memory 2306. For example, common forms of storage media include floppy disks, flexible disks, hard disks, solid state drives, magnetic tapes, or any other magnetic data storage media, CD-ROMs, any other optical data storage media, any physical media with patterns of holes, RAM, PROM, EPROM, FLASH-EPROM, NVRAM, any other memory chip, or cartridges.

[0176] A storage medium is different from a transmission medium but can be used in conjunction with a transmission medium. A transmission medium is involved in transferring information between storage media. For example, transmission media can include coaxial cables, copper wires, and optical fibers including wires with bus 2302. A transmission medium can take the form of acoustic or light waves such as those generated during radio wave and infrared data communications.

[0177] The various forms of media can involve carrying one or more series of one or more instructions to processor 2304 for execution. For example, the instructions can first be performed on a magnetic disk or solid state drive of a remote computer. The remote computer can load the instructions into its dynamic memory and can transmit those instructions via a network connection. A local modem or network interface of computer system 2300 can receive the data. Bus 2302 carries the data to main memory 2306 from where processor 2304 retrieves and executes the instructions. The instructions received by main memory 2306 can optionally be stored in storage device 2310 either before or after execution by processor 2304.

[0178] Computer system 2300 also includes a communication interface 2318 coupled to bus 2302. Communication interface 2318 provides for bi-directional data communication coupling to a network link 2320 connected to local network 2322. For example, communication interface 2318 can be an integrated services digital network (ISDN) card, cable modem, satellite modem, or modem to provide a data communication connection over a corresponding type of telephone line. A wireless link can also be implemented. In any such implementation, communication interface 2318 transmits and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[0179] Network link 2320 typically provides data communication through one or more networks to other data devices. For example, network link 2320 can provide the connection to a host computer 2324 through local network 2322 or to a data device operated by an Internet Service Provider (ISP) 2326. The ISP 2326 then provides data communication services through a worldwide packet data communication network commonly referred to herein as the "Internet" 2328. Both local network 2322 and Internet 2328 use electrical, electromagnetic, or optical signals that carry digital data streams. Signals through various networks that carry digital data between computer system 2300 as well as signals on network link 2320 and through communication interface 2318 are examples of forms of transmission media.

[0180] Computer system 2300 can send messages and receive data including program code via a network(s), network link 2320, and communication interface 2318. In an example of the Internet, server 2330 can transmit the requested code of an application program via Internet 2328, ISP 2326, local network 2322, and communication interface 2318. The received code can be executed by processor 2304 when received and / or stored in storage device 2310 or other non-volatile storage device for later execution.

[0181] The operations of the processes described herein can be performed in any suitable order unless otherwise explicitly indicated herein or otherwise clearly contradicted by context. The processes described herein (or variations and / or combinations thereof) can be performed under the control of one or more computer systems configured with executable instructions and implemented as code collectively executed on one or more processors, by hardware, or combinations thereof (e.g., executable instructions, one or more computer programs, or one or more applications). The code can be stored in a computer-readable storage medium in the form of, for example, a computer program that includes a plurality of instructions executable by one or more processors. The computer-readable storage medium may be non-transitory.

[0182] Unless otherwise specifically stated or otherwise clearly negated by context, connective language such as expressions in the form of "at least one of A, B, and C" or "at least one of A, B and C" is generally understood in context as being used to indicate that an item, term, etc. can be any of A or B or C, or any non-empty subset of the set of A and B and C. For example, in an example of an exemplary set having three members, the connective expressions "at least one of A, B, and C" as well as "at least one of A, B and C" refer to any of the following sets: {A}, {B}, {C}, {A, B}, {A, C}, {B, C}, {A, B, C}. Thus, such connective expressions are generally not intended to implicitly mean that a particular embodiment requires the presence of at least one of A, at least one of B, and at least one of C, respectively.

[0183] Any examples and all examples provided in this specification, or the use of exemplary language (e.g., "such as"), are merely intended to make the embodiments of the present invention clearer and do not cause a limitation of the scope of the present invention unless otherwise claimed. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the present invention.

[0184] In the foregoing specification, embodiments of the present invention have been described with reference to numerous specific details that may vary between implementation examples. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indicator of the scope of the present invention, and what the applicant intends the scope of the present invention to be, is the literal scope and equivalents of the set of claims issued from this application in a particular form, including any subsequent amendments thereto.

[0185] Those skilled in the art may envision additional embodiments after reading this disclosure. In other embodiments, combinations or sub - combinations of the inventions disclosed above can be advantageously made. By way of example, an arrangement example of components is shown, and it should be understood that combinations, additions, rearrangements, etc. are contemplated in alternative embodiments of the present invention. Thus, although the present invention has been described with respect to exemplary embodiments, those skilled in the art will recognize that numerous modifications are possible.

[0186] For example, the processes described herein can be implemented using hardware components, software components, and / or any combination thereof. Thus, this specification and the drawings are to be regarded in an illustrative rather than a restrictive sense. However, it is clear that various modifications and changes can be made to them without departing from the broader spirit and scope of the invention as set forth in the claims, and that the present invention is intended to cover all modifications and equivalents within the scope of the following claims.

[0187] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference in their entirety as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. [Item 1] A multi - connection base station having one or more transceivers for handling communication with a plurality of terrestrial mobile stations, wherein a certain terrestrial mobile station among the plurality of terrestrial mobile stations is configured to anticipate base - station communication with a terrestrial cellular base station that is (1) within a restricted distance from the terrestrial mobile station and / or (2) moving at a speed less than a restricted speed with respect to the terrestrial mobile station, and the multi - connection base station A data analyzer that analyzes data received by the multi-connection base station according to a frame structure, wherein the frame structure defines which time slot is assigned to which of the plurality of terrestrial mobile stations, and the frame structure includes a plurality of slots each having a zero or non-zero time slot synchronization offset that results in a variable transmission delay due to the distance from the multi-connection base station to the plurality of terrestrial mobile stations, and a data analyzer. A signal timing module that determines signal timing adjustment for a frame structure of a transmission signal to a terrestrial mobile station based on a base-mobile distance between the multi-connection base station and the terrestrial mobile station, wherein the base-mobile distance exceeds the limit distance, and a signal timing module. A programmable radio that communicates from the multi-connection base station to the terrestrial mobile station using a multi-connection protocol and can take into account the signal timing adjustment, so that the communication is compatible with the communication between a terrestrial cellular base station and the terrestrial mobile station or appears to be so to the terrestrial mobile station even though the base-mobile distance exceeds the limit distance, and a programmable radio, comprising a multi-connection base station. [Item 2] The multi-connection base station according to item 1, further adapted to communicate with the plurality of terrestrial mobile stations, wherein the plurality of terrestrial mobile stations include a cellular phone handset, a smartphone, and a connected device. [Item 3] The multi-connection base station according to item 1 or 2, wherein the limit distance is 120 kilometers and the base-mobile distance exceeds 120 kilometers. [Item 4] The multi-connection base station according to item 1 or 2, wherein the multi-connection protocol is an LTE protocol, the limit distance is 100 kilometers, and the base-mobile distance exceeds 100 kilometers. [Item 5] The multi-connection protocol is the LTE-IoT protocol, the limited distance is 40 kilometers, and the distance between the base and the mobile exceeds 40 kilometers. The multi-connection base station according to item 1 or 2. [Item 6] The multi-connection protocol is one of a CDMA-based protocol, an LTE protocol, a GSM (registered trademark) protocol, an OFDMA-based protocol, an FDMA-based protocol, a TDMA-based protocol, an EGPRS protocol, or an EDGE protocol. The multi-connection base station according to any one of items 1 to 3. [Item 7] The multi-connection base station is an orbital base station operating within the orbit of the earth. The multi-connection base station according to any one of items 1 to 6. [Item 8] The limited distance is 120 kilometers, and the distance between the base and the mobile of the terrestrial mobile stations of the plurality of terrestrial mobile stations is about 500 kilometers to about 750 kilometers. The multi-connection base station according to item 7. [Item 9] The multi-connection base station is a base station operable within the earth's atmosphere and includes being mounted on or in one or more of an airplane, a drone, and / or a balloon. The multi-connection base station according to any one of items 1 to 6. [Item 10] The limited distance is 120 kilometers, and the distance between the base and the mobile exceeds 120 kilometers. The multi-connection base station according to item 9. [Item 11] The multi-connection base station further includes signal allocation logic for allocating the capacity of the multi-connection base station, which is distributed over a plurality of time slots, a plurality of carrier frequencies, a plurality of orthogonal sub-carriers, and / or a plurality of code sequences, to the plurality of terrestrial mobile stations including the terrestrial mobile stations. The multi-connection base station according to any one of items 1 to 10. [Item 12] The programmable radio can further listen to communications from the terrestrial mobile stations using a multi-connection protocol. The multi-connection base station For each of the plurality of terrestrial mobile stations, a range calculator that determines the base-mobile distance of each terrestrial mobile station, which is the distance from the multi-connection base station to the terrestrial mobile station; A reception timing module that determines the timing of the reception signal of the terrestrial mobile station with respect to the frame structure based on the base-mobile distance of the terrestrial mobile station; An input signal allocator that allocates a listening time slot within the frame structure to listen to communications from the terrestrial mobile station, wherein the listening time slot is timed based on the base-mobile distance of the terrestrial mobile station, the listening time slot is one of a plurality of time slots, and the plurality of time slots are variably delayed within the frame structure so as to consider the multi-connection base station that handles communications from the plurality of terrestrial mobile stations having a plurality of base-mobile distances. The multi-connection base station according to item 1. [Item 13] The multi-connection base station according to item 12, wherein the plurality of time slots are variably delayed within the frame structure so as to consider the plurality of terrestrial mobile stations having a plurality of base-mobile distances by allocating each of the plurality of different base-mobile distance ranges to each of the plurality of channel blocks. [Item 14] The multi-connection base station according to item 13, wherein the multi-connection base station is an orbital base station operating within the orbit of the earth, the plurality of different base-mobile distance ranges collectively cover the slant range from the zenith distance to the minimum elevation distance, the zenith distance is the distance between the terrestrial mobile station and the zenith position of the satellite holding the multi-connection base station, and the minimum elevation distance is the distance between the terrestrial mobile station and the position of the satellite when the terrestrial mobile station enters the designed footprint of the satellite. [Item 15] The distance ranges between the plurality of different base-mobile stations each extend to approximately 34 to 35 kilometers, and the difference between the zenith distance and the minimum elevation distance is 210 to 250 kilometers. The multi-connectivity base station according to item 14. [Item 16] The designed footprint of the satellite is circular, elliptical, or rectangular, and is independent of the function of the antenna and / or the shape of the antenna beam, or is the function of the antenna and / or the shape of the antenna beam. The multi-connectivity base station according to item 14 or 15. [Item 17] A multi-connectivity base station having one or more transceivers for handling communication with a plurality of terrestrial mobile stations, wherein the terrestrial mobile stations are configured to anticipate base station communication with a terrestrial cellular base station that is (1) within a restricted distance from the terrestrial mobile station and / or (2) moving at a speed less than a restricted speed with respect to the terrestrial mobile station. The multi-connectivity base station A data analyzer that analyzes the data received by the multi-connectivity base station according to a multi-connectivity protocol, which defines which time slot is assigned to which of the plurality of terrestrial mobile stations according to a frame structure, and anticipates that the terrestrial mobile stations receive signals at a specified frequency and transmit signals at the specified frequency. A Doppler shift calculator that determines the Doppler shift of each of the plurality of terrestrial mobile stations due to the speed of each of the terrestrial mobile stations with respect to the multi-connectivity base station. A channel assignment module that assigns each of the plurality of terrestrial mobile stations to a channel block within a plurality of channel blocks, each channel block having a terrestrial frequency and a Doppler frequency offset. A signal modulator that modulates a signal to the terrestrial mobile station at the terrestrial frequency using the Doppler frequency offset, wherein the Doppler frequency offset corresponds at least approximately to an expected Doppler shift in the signal transmitted to the terrestrial mobile station due to relative movement of the multi-connection base station and the terrestrial mobile station, such that the terrestrial mobile station receives the signal at the terrestrial frequency. A programmable radio that can receive communications from the terrestrial mobile station using the multi-connection protocol and take into account the Doppler frequency offset of the terrestrial mobile station, such that the communications are compatible with or appear to be so between the terrestrial cellular base station and the terrestrial mobile station even though the speed of the terrestrial mobile station relative to the multi-connection base station exceeds the limit speed. A multi-connection base station comprising such a programmable radio. [Item 18] The multi-connection base station according to item 17, wherein the speed of the terrestrial mobile station relative to the multi-connection base station results from the multi-connection base station being within the Earth's orbit, and the Doppler frequency offset changes in increments of 5 kilohertz. [Item 19] The multi-connection base station according to item 17 or 18, further adapted to communicate with the plurality of terrestrial mobile stations, the plurality of terrestrial mobile stations comprising cellular phone handsets, smartphones, and connected devices. [Item 20] The multi-connection base station according to any one of items 17 to 19, wherein the multi-connection base station is an orbital base station operating within the Earth's orbit. [Item 21] The multi-connection base station according to any one of items 17 to 19, wherein the multi-connection base station is a base station operable within the Earth's atmosphere and includes being mounted on or in one or more of an airplane, a drone, and / or a balloon. [Item 22] A multi-connection base station according to any one of items 17 to 21, further comprising signal allocation logic for allocating the capacity of the multi-connection base station, which is distributed over a plurality of time slots, a plurality of carrier frequencies, a plurality of orthogonal sub-carriers, and / or a plurality of code sequences, to the plurality of terrestrial mobile stations including the terrestrial mobile station. [Item 23] A multi-connection base station according to any one of items 17 to 22, wherein each of the plurality of channel blocks has an uplink sub-channel and a downlink sub-channel including a continuous spectrum of the uplink sub-channel and a continuous spectrum of the downlink sub-channel, and the channel blocks are allocated such that adjacent channel blocks are allocated to adjacent Doppler frequency offsets. [Item 24] A multi-connection base station having one or more transceivers for handling communication with a plurality of terrestrial mobile stations, wherein the terrestrial mobile stations are configured to anticipate base station communication with a terrestrial cellular base station that is (1) within a restricted distance from the terrestrial mobile station and / or (2) moving at a speed less than a restricted speed relative to the terrestrial mobile station, and the multi-connection base station A data analyzer for analyzing data received by the multi-connection base station according to a frame structure and further according to a multi-connection protocol, the frame structure defining which time slots are allocated to which of the plurality of terrestrial mobile stations, and comprising a plurality of slots each having a zero or non-zero time slot synchronization offset that results in a variable transmission delay due to the distance from the multi-connection base station to the plurality of terrestrial mobile stations, the multi-connection protocol transmitting on the prediction that the terrestrial mobile station receives signals at a specified frequency and transmits signals at a terrestrial frequency, and is received at a Doppler frequency offset, and the multi-connection protocol identifies channel blocks within a plurality of channel blocks, each channel block having a specified terrestrial frequency and a specified time slot, and a data analyzer A signal timing module that determines signal timing adjustment for a transmission signal to the terrestrial mobile station with respect to the frame structure based on the base-mobile distance between the multi-connection base station and the terrestrial mobile station, wherein the base-mobile distance exceeds the limit distance, and a designated signal timing adjustment is allocated to each channel block. For each terrestrial mobile station of the plurality of terrestrial mobile stations, a Doppler shift calculator that determines the Doppler shift of each terrestrial mobile station due to the speed of each terrestrial mobile station with respect to the multi-connection base station, and a designated Doppler frequency offset is allocated to each channel block. A dynamic channel allocator that allocates each of the plurality of terrestrial mobile stations to a designated channel block within the plurality of channel blocks based on the designated signal timing adjustment and the designated Doppler frequency offset of the channel block, wherein the number of channels within the designated channel block corresponds to the number of the plurality of terrestrial mobile stations that have or are expected to have the designated signal timing adjustment and the designated Doppler frequency offset. A signal modulator that modulates a signal to the terrestrial mobile station at the terrestrial frequency using the Doppler frequency offset, wherein the Doppler frequency offset at least substantially corresponds to the expected Doppler shift in the signal transmitted to the terrestrial mobile station due to the relative movement of the multi-connection base station and the terrestrial mobile station, so that the terrestrial mobile station receives the signal at the terrestrial frequency. A programmable radio that can receive communications from the terrestrial mobile station using the multi-connection protocol and take into account the Doppler frequency offset of the terrestrial mobile station, so that the communication is compatible with the communication between the terrestrial cellular base station and the terrestrial mobile station or appears to be so to the terrestrial mobile station, even though the distance between the base and the mobile exceeds the limit distance and the speed of the terrestrial mobile station relative to the multi-connection base station exceeds the limit speed, comprising such a programmable radio. [Item 25] The multi-connection base station according to item 24, wherein the speed of the terrestrial mobile station relative to the multi-connection base station results from the multi-connection base station being within the Earth's orbit, and the Doppler frequency offset varies in 5-kilohertz increments. [Item 26] The multi-connection base station according to item 24 or 25, further adapted to communicate with the plurality of terrestrial mobile stations, the plurality of terrestrial mobile stations including cellular phone handsets, smartphones, and connected devices. [Item 27] The multi-connection base station according to any one of items 24 to 26, wherein the multi-connection base station is an orbital base station operating within the Earth's orbit. [Item 28] The multi-connection base station according to any one of items 24 to 26, wherein the multi-connection base station is a base station operable within the Earth's atmosphere and includes being mounted on or in one or more of an airplane, a drone, and / or a balloon. [Item 29] The multi-connection base station according to any one of items 24 to 28, further comprising signal allocation logic for allocating the capacity of the multi-connection base station, distributed over a plurality of time slots, a plurality of carrier frequencies, a plurality of orthogonal subcarriers, and / or a plurality of code sequences, to the plurality of terrestrial mobile stations including the terrestrial mobile station.

Claims

A multi - connection transceiver configured to communicate with a plurality of terrestrial mobile stations including at least a first terrestrial mobile station using a multi - connection protocol, a data analyzer that analyzes data received by the multi - connection transceiver into a structure suitable for a predefined frame structure in the multi - connection protocol, wherein the frame structure defines which time slots are assigned to which of the plurality of terrestrial mobile stations, a signal timing module that adjusts the timing of a transmission signal according to signal timing adjustment based at least in part on a propagation delay across a communication path between the multi - connection transceiver and the first terrestrial mobile station, wherein the propagation delay is due to propagation of a signal from the first terrestrial mobile station to the multi - connection transceiver, a programmable radio that can communicate from the multi - connection transceiver to the first terrestrial mobile station using the multi - connection protocol and take into account the signal timing adjustment, so that, even though a first communication distance between the multi - connection transceiver and the first terrestrial mobile station exceeds a limited communication distance defined in the multi - connection protocol, at least to the first terrestrial mobile station, the communication appears to be compatible with communication between a terrestrial cellular base station and the first terrestrial mobile station, A multi - connection transceiver comprising the above.

2. The multi - connection transceiver according to claim 1, wherein the plurality of terrestrial mobile stations comprise cellular phone handsets, smartphones, and / or connected devices.

3. The multi - connection transceiver according to claim 1 or 2, wherein one or more antennas used by the multi - connection transceiver include antennas on a second surface of the earth.

4. The first terrestrial mobile station is configured to expect that communication with the terrestrial cellular base station is via the communication path within the limited communication distance, The frame structure includes a plurality of slots, The signal timing module adjusts the timing of the transmission signal for the frame structure for the first terrestrial mobile station by offsetting the timing of each of the plurality of slots by a zero or non-zero time slot synchronization offset based on the first communication distance, where the first communication distance exceeds the limited communication distance. The multi-connection transceiver according to any one of claims 1 to 3.

5. The multi-connection transceiver according to any one of claims 1 to 4, further comprising signal allocation logic for allocating the capacity of the multi-connection transceiver, which is distributed across a plurality of time slots, a plurality of carrier frequencies, a plurality of orthogonal sub-carriers, and / or a plurality of code sequences, to the plurality of terrestrial mobile stations including the first terrestrial mobile station.

6. The programmable radio can further listen to communications from the first terrestrial mobile station using the multi-connection protocol, and the multi-connection transceiver a range calculator that determines, for each terrestrial mobile station of the plurality of terrestrial mobile stations, the communication distance of each terrestrial mobile station, which is the propagation distance along the communication path between the multi-connection transceiver and the corresponding terrestrial mobile station from the multi-connection transceiver to the corresponding terrestrial mobile station; a reception timing module that determines the timing of the reception signal of the first terrestrial mobile station with respect to the frame structure based on the first communication distance of the first terrestrial mobile station; The multi-connection transceiver according to any one of claims 1 to 5, further comprising an input signal allocator that allocates a listening time slot within the frame structure to listen to communications from the first terrestrial mobile station, where the listening time slot is timed based on the first communication distance of the first terrestrial mobile station, the listening time slot is one of the plurality of time slots, and the plurality of time slots are variably delayed within the frame structure in consideration of the multi-connection transceiver that handles communications from the plurality of terrestrial mobile stations having respective communication distances.

7. The multi-connection transceiver according to claim 6, wherein the plurality of time slots are variably delayed within the frame structure so as to consider the multi-connection transceiver that handles communications from the plurality of terrestrial mobile stations having the respective plurality of communication distances by allocating each of the plurality of different communication distance ranges to each of the plurality of channel blocks.

8. The programmable radio can further listen to the communication from the first terrestrial mobile station using the multi-connection protocol, and the multi-connection transceiver a range calculator that determines, for each terrestrial mobile station of the plurality of terrestrial mobile stations, the communication distance of each terrestrial mobile station, which is the propagation distance along the communication path between the multi-connection transceiver and the corresponding terrestrial mobile station from the multi-connection transceiver to the corresponding terrestrial mobile station; a reception timing module that determines the timing of the reception signal of the first terrestrial mobile station with respect to the frame structure based on the first communication distance of the first terrestrial mobile station; further comprising an input signal allocator that allocates a listening time slot within the frame structure to listen to the communication from the first terrestrial mobile station; the listening time slot is timed based on the first communication distance of the first terrestrial mobile station, the listening time slot is one of the plurality of time slots, and the plurality of time slots are variably delayed within the frame structure so as to consider the multi-connection transceiver that handles communications from the plurality of terrestrial mobile stations having the respective plurality of communication distances; the plurality of time slots are variably delayed within the frame structure so as to consider the multi-connection transceiver that handles communications from the plurality of terrestrial mobile stations having the respective plurality of communication distances by allocating each of the plurality of different communication distance ranges to each of the plurality of channel blocks; The multi-connection transceiver is an orbital base station operating within an orbit around the Earth, the plurality of different communication distance ranges collectively cover a slant range from the zenith distance to the minimum elevation distance, the zenith distance is the distance between the satellite holding the multi-connection transceiver and the zenith position with respect to the corresponding terrestrial mobile station, and the minimum elevation distance is the distance between the satellite's position when the corresponding terrestrial mobile station enters the satellite's designed footprint. The multi-connection transceiver according to claim 1.

9. Each of the plurality of different communication distance ranges extends from 34 to 35 kilometers, and the difference between the zenith distance and the minimum elevation distance is from 210 to 250 kilometers. The multi-connection transceiver according to claim 8.

10. The designed footprint of the satellite is a shape having an area, including at least one of a circle, an ellipse, and / or a rectangle, and is independent of or a function of the shape of one or more antennas, one or more beams, and / or one or more antenna beams. The multi-connection transceiver according to claim 8 or 9.

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