Carrier bandwidth adjustment in cellular radio networks

Abstract

A method for adjusting the bandwidth of a carrier signal providing access to a cellular radio network via a high-altitude platform (HAP), the carrier signal being transmitted within a predetermined spectrum channel, the HAP transmitting a first carrier signal of a first bandwidth in a first portion of the predetermined spectrum allocation, the method comprising: configuring the transmission of a second carrier signal of a second bandwidth in a second portion of the predetermined spectrum allocation, the second bandwidth being different from the first bandwidth; and configuring a service switch from the first carrier signal to the second carrier signal.

Description

Technical Field

[0001] This disclosure relates to adjusting the bandwidth of carrier signals that provide access to cellular radio networks, particularly in cellular radio networks where access is provided via high-altitude platforms (HAPs), such as spacecraft or satellites (referred to as HAPs in this disclosure). Background Art

[0002] Cellular wireless communication networks provide broad geographic coverage by allowing user (mobile) terminals to access the network through a radio access network (RAN) composed of cells, each with a specific geographic coverage area. In this context, a cell refers to a base station (RAN access node) with a cell identifier (cell ID), as used in the 3rd Generation Partnership Project (3GPP) standard. Cell coverage areas may overlap, which can help avoid areas without coverage. Nevertheless, there are still areas without cellular wireless network coverage, for example, where deploying cells is dangerous, difficult, expensive, or a combination of these. This is particularly likely to occur in rural areas and developing countries.

[0003] Using a high-altitude platform (HAP) to provide cell coverage (especially for 4G or 5G) allows for terrestrial coverage, just as it would be provided by a typical mobile network operator (MNO) site, allowing access for the same users or mobile terminals supporting this RAN in a terrestrial network. In the context of this disclosure, satellites will be considered as a type of HAP, and the term encompasses any type of radio platform, typically operating at an altitude of 20 km or higher and preferably at a designated, nominal, fixed point relative to the Earth. The term HAP as used herein should not be confused with the term "high-altitude platform station" used in the International Telecommunication Union (ITU) Radio Regulations, which has a narrower definition than the term HAP used in this disclosure. RANs provided by HAP infrastructure involve complexity.

[0004] First refer to Figure 1The diagram illustrates a schematic architecture of an exemplary cellular RAN provided by, for example, a HAP 10 via satellite 10. HAP 10 acts as a relay between baseband system 30 and end users (e.g., any SIM-based device including a mobile terminal, not shown). Baseband system 30 generates radio signals for transmission by HAP 10 and also processes baseband signals received by HAP 10. Therefore, baseband system 30 provides a lower level of base station functionality (which can be virtualized or non-virtualized). In this case, seven independent intermediate signals are shown (the corresponding portions are indicated by dots or dashes similar to those used in other parts of the diagram). Each intermediate signal represents a baseband carrier signal for a corresponding cell, and each carrier signal has a corresponding bandwidth. These are provided to HAP gateway antenna unit 50, which acts as a mixer, multiplexer, and ground station radio. The transmission frequency between gateway antenna unit 50 and HAP 10 (particularly when HAP 10 is a satellite) is typically in the Ku or Q band. Communication between baseband system 30 and HAP 10 is thus conducted via antenna 50. Seven intermediate signals (in this case, LTE signals using Orthogonal Frequency Division Multiplexing (OFDM)) are transmitted to the frequency-multiplexed HAP 10 via the first intermediate signal 51, the second intermediate signal 52, the third intermediate signal 53, the fourth intermediate signal 54, the fifth intermediate signal 55, the sixth intermediate signal 56, and the seventh intermediate signal 57. Each intermediate signal represents a corresponding carrier signal. The bandwidth for each signal is different, and it... Figure 1 The width is used to describe the middle.

[0005] HAP 10 uses individual, corresponding beams to transmit seven radio signals. The first beam transmits the first carrier 51 to provide a first coverage area 91 (shown as the upper left area); the second beam transmits the second carrier 52 to provide a second coverage area 92 (shown as the center area); the third beam transmits the third carrier 53 to provide a third coverage area 93 (shown as the top area); the fourth beam transmits the fourth carrier 54 to provide a fourth coverage area 94 (shown as the upper right area); the fifth beam transmits the fifth carrier 55 to provide a fifth coverage area 95 (shown as the lower right area); the sixth beam transmits the sixth carrier 56 to provide a sixth coverage area 96 (shown as the lower center area); and the seventh beam transmits the seventh carrier 57 to provide a seventh coverage area 97 (shown as the lower left area). Communication between HAP 10 and end users occurs within the standardized 3GPP radio access band. Each carrier signal is transmitted within its corresponding allocated frequency channel.

[0006] HAP 10 is therefore capable of managing a large number of wireless network cells, which can communicate (i.e., transmit and / or receive) over specific areas via directional beams. However, HAPs are limited in both power and bandwidth. The bandwidth limitation is particularly relevant to the link between HAP 10 and antenna element 50. The baseband size is directly related to the number of cells to be processed. Therefore, when providing a RAN, the total bandwidth available for transmission (and / or reception) by the HAP is limited. The same challenges may arise regardless of the form of HAP used.

[0007] In any case, business demand can be quite uneven. This demand can not only change drastically over short periods of time (hours, days, and / or weeks), but HAP coverage may also target areas with low population density, so many cells may be inactive (without business demand) for a higher proportion of the time.

[0008] The standard set by the 3rd Generation Partnership Project (3GPP) requires that a Cell-Specific Reference Signal (CRS) be transmitted across the entire carrier bandwidth even if the cell is not being used by a 4G network. The channel bandwidths for cells defined in existing 3GPP standards are 1.4, 3, 5, 10, 15, and 20 MHz. The allowed channel bandwidth depends on the operating frequency band (see, for example, see...). http: / / niviuk.free.fr / lte_bandwidth.PHP For inactive cells, it is optimal to use the minimum carrier bandwidth, for example, 1.4 MHz for band 8 (900 MHz GSM). Therefore, each cell will require this amount of HAP bandwidth even without any activity. Thus, HAP 10 broadcasts seven beams to define seven cells, although four of these cells (using carriers 4, 54, 55, 56, and 57) have the minimum carrier bandwidth and may be empty. This means using 1.4 × 4 = 4.6 MHz of HAP bandwidth to signal an empty area. Furthermore, each cell will consume some baseband resources and power required to guarantee the desired coverage level. Therefore, adjusting the cell bandwidth is desirable. Improving efficiency in this regard presents a challenge, especially for cellular networks provided by HAP. Summary of the Invention

[0009] In this context, this disclosure provides a method for adjusting the bandwidth of a carrier signal providing access to a cellular radio network via a high-altitude platform (HAP) according to claim 1, and a configuration system according to claim 15. Further preferred features are disclosed with reference to the claims and the following description.

[0010] Typically, adjusting the bandwidth of the carrier signal transmitted by the HAP begins with transmitting a first carrier signal of a first bandwidth in a first portion of a predetermined spectrum channel (i.e., the portion of the maximum spectrum allocated or otherwise specified for use by the cell). Then, a second carrier signal of a second bandwidth (different from the first bandwidth) in a second portion of the predetermined spectrum allocation is configured for transmission (along with the first carrier). The second carrier may correspond to a new cell (which is ultimately intended to replace an existing cell). The handover of services from the first carrier signal to the second carrier signal is advantageously configured. This can be implemented either as a method or through a suitably arranged configuration system.

[0011] In this way, a second carrier within the same predetermined spectrum channel for the cell can be configured (and thus transmitted) while still transmitting a pre-existing carrier. This allows services to switch from the first carrier to the second carrier. This feature allows for seamless bandwidth changes within the cell. Optionally, the first carrier can then be configured to shut down. This technique is particularly useful when the first carrier signal and / or the second carrier signal are orthogonal frequency division multiplexing (OFDM) signals, such as when the cell uses LTE or 4G RAN.

[0012] This approach is advantageous when the cell is provided by a high-altitude platform (HAP), in which context, the high-altitude platform may include a satellite. The HAP has an antenna system that defines multiple beams, such that each beam provides independent geographic coverage areas. Preferably, the first and second carrier signals are transmitted by the same or multiple beams of the HAP. Thus, the first and second carrier signals provide service to user terminals in the same geographic area (in terms of the radio access network). In this context, the configuration of the first and second carriers can be achieved by transmitting configuration data from the baseband system to the HAP, the configuration data indicating parameters of the second carrier signal, such as one or more of the following: transmission power; bandwidth; frequency offset from the channel center; and the beam used for transmission. In this bandwidth- and / or power-constrained context, reconfiguration of the HAP can be challenging. The ability to change the bandwidth used for service provisioning in this way can allow for significant improvements in the efficiency and performance of the RAN providing the HAP.

[0013] In a preferred embodiment, the second bandwidth is greater than the first bandwidth. In other words, the process is used to increase the bandwidth of the cell, although it can also be used to decrease the cell bandwidth (making the second bandwidth less than the first bandwidth). Increasing the bandwidth can, for example, be in response to increased traffic through the cell provided by the first carrier signal, or in response to increased users or mobile terminals connecting to the cell provided by the first carrier signal.

[0014] The first carrier (or its center) is advantageously offset from the center of the cell's predetermined spectrum channel. This reduces the complexity of adding a second carrier, for example, because the user or mobile terminal reads the center of the carrier for initial setup. Avoiding the center of the carrier being located in the center of the cell's predetermined spectrum channel allows for greater flexibility. For similar reasons, the second portion of the predetermined spectrum channel is advantageously offset from the center of the predetermined spectrum channel, especially when the second bandwidth is less than the entire bandwidth of the predetermined spectrum channel.

[0015] In one option, the first and second carriers overlap. In this case, transmission of the overlapping portion of the second carrier signal is suppressed or muted. For example, this suppression can be achieved by allocating a transmission power level to the overlapping portion of the second carrier signal that is insufficient to interfere with the reception of the first carrier signal. In OFDM signals, this can be achieved by configuring one or more physical resource blocks (PRBs) in the overlapping portion. The insufficient transmission power level can be at least 3 dB lower than the transmission power of the first carrier signal, and more preferably at least 6 dB, 9 dB, 12 dB, or 15 dB lower. Alternatively, the insufficient transmission power level can be zero (which can be considered complete muting). Preferably, no cell-specific reference signal is transmitted within the suppressed portion of the second carrier signal (which can also be considered muted). Advantageously, the broadcast channel of the first carrier signal does not overlap with the broadcast channel of the second carrier signal.

[0016] In another option, the second carrier does not overlap with the first carrier. The second carrier can then be spaced apart from the first carrier, for example, by a guard interval or some other radio frequency spacing. Attached Figure Description

[0017] The method disclosed herein can be implemented in various ways, one of which will be described by way of example only and with reference to the accompanying drawings, in which:

[0018] Figure 1 A schematic architecture for an exemplary cellular RAN provided via HAP is shown;

[0019] Figure 2A , 2B The diagram 2C schematically depicts the transmission in the spectrum according to the first example;

[0020] Figure 3A , 3B The 3C schematic depicts the transmission in the spectrum according to the second example;

[0021] Figure 4 A flowchart for the method according to this disclosure is shown; and

[0022] Figure 5A schematic block diagram of a configuration system according to this disclosure is shown. Detailed Implementation

[0023] Figure 1 The arrangement shown represents static cell management, where each cell is associated with a corresponding single beam and has a set bandwidth. The beam coverage for each cell is fixed and given by a beam fingerprint. In existing methods, the bandwidth of a cell cannot be changed without removing an existing cell and subsequently creating a new cell with a different (higher) bandwidth. This process is disruptive to service and can have an impact on users. This disclosure aims to achieve seamless bandwidth changes within cells, particularly utilizing semi-static or dynamic cell management, where cell bandwidth can change, for example, based on cell load.

[0024] As mentioned above, the LTE RAN, as defined by existing 3GPP standards, requires a minimum bandwidth of 1.4 MHz for the cell carrier. This initial carrier bandwidth is used when the cell remains inactive and without traffic. For example, once traffic demand arises (e.g., when calls are established or the number of users connecting to the cell increases), a new carrier with higher bandwidth (corresponding to a replacement cell) is used for data transmission. With the establishment of the new carrier, all calls are switched to this carrier (cell), and the previous 1.4 MHz carrier (cell) is shut down. The initial carrier is not configured at the center of the total bandwidth channel, but rather on one side of the multiple sides within the channel range. The broadcast channel (BCH) within 1.08 MHz at the center of the carrier allows users or mobile terminals to read the cell at initialization, so it is advantageous for the carrier not to be at the center of the channel. As will be discussed below, offsetting the initial carrier from the center of the spectrum allocation can allow for room for new carriers and is in some implementations. For similar reasons, the new carrier may also be offset from the center of the spectrum channel. This process can be repeated so that a new carrier becomes the initial carrier, and another new carrier is added, as long as the initial carrier does not exhaust the entire spectrum channel for the cell.

[0025] Generally, a method for adjusting the bandwidth of a carrier signal providing access to a cellular radio network via a High Altitude Platform (HAP) can be considered. The carrier signal resides within a predetermined spectrum channel (e.g., particularly the spectrum allocated to the cell in the downlink). The HAP (through at least one of its multiple beams) transmits a first carrier signal of a first bandwidth in a first portion of the predetermined spectrum channel (the first portion defines the spectral range of a first carrier, typically the first portion of the spectrum channel). The method includes: configuring the transmission of a second carrier signal (by the HAP through at least one of its beams) of a second bandwidth in a second portion of the predetermined spectrum channel (the second portion defines the spectral range of a second carrier, particularly different from the first portion, e.g., the second portion of the spectrum channel), the second bandwidth being different from the first bandwidth; and (subsequently) configuring a handover of service from the first carrier signal to the second carrier signal. In this way, the second carrier signal can replace the first carrier signal for the cell. In particular, the second carrier signal advantageously serves the same geographical coverage area (or at least a subset thereof) for which the first carrier signal provides service. The transmission of the second carrier begins before the first carrier is stopped, so both carriers can be transmitted simultaneously. This allows for an efficient handover process between the first and second carriers. Optionally, the method may further include (after configuring the handover step) configuring the cessation of the first carrier signal. Typically, the first and second carrier signals are orthogonal frequency division multiplexing (OFDM) signals and are specifically configured for 4G RAN.

[0026] The method can be implemented as a computer program (e.g., configured to execute the method when executed by a processor, such as having instructions accordingly), in software, hardware, firmware, digital logic (optionally reconfigurable, including FPGA devices or similar devices), programmable memory or circuitry), or an equivalent arrangement, or any combination of two or more of these. Further consideration may be given to computer program products (e.g., on a non-transitory computer-readable medium) that include or store the computer program. A configuration system for adjusting the bandwidth of carrier signals transmitted by a cell in a cellular radio network, configured to perform any of the methods disclosed herein, may also be considered. The configuration system may be part of or coupled to a baseband system for a cell. It may include or be contained in an existing node of the RAN (including the baseband system) or a new node (or server) coupled to an existing node of the RAN (e.g., coupled to the baseband system).

[0027] In a preferred embodiment, the second bandwidth is greater than the first bandwidth (i.e., the second carrier has a larger bandwidth than the first carrier). Increasing the bandwidth in this way can be in response to the identification of increased traffic by an increased number of user terminals connected to or supplied by the first carrier signal within the cell. In other words, the bandwidth may be associated with the load on the cell. Conversely, the method of this disclosure can also be used to reduce the cell bandwidth such that the second bandwidth is less than the first bandwidth.

[0028] Advantageously, a first portion of the predetermined spectrum channel (e.g., the center frequency of the first portion or the first carrier) is offset from the center of the predetermined spectrum channel. Additionally or alternatively, a second portion of the predetermined spectrum channel is offset from the center of the predetermined spectrum channel. In some embodiments, the second bandwidth is less than the entire bandwidth of the predetermined spectrum channel. For example, this may allow a third carrier to replace the second carrier. In this case, the second portion of the predetermined spectrum channel is advantageously offset from the center of the predetermined spectrum channel.

[0029] Further features described in this overview will be detailed below. As an example, a specific implementation will be discussed first. Now refer to... Figure 2A , 2B And 2C, based on the first example, schematically depict the transmission in the spectrum. In Figure 2A The diagram illustrates the bandwidth allocation for cell 100. Within bandwidth allocation (or channel) 100, a first initial carrier 110 is transmitted. The first initial carrier 110 has a minimum bandwidth of 1.4 MHz. Typically, all cells are initially configured with such a minimum bandwidth because this allows service to be provided, but without any significant traffic passing through the cell. Figure 2A As shown, the first initial carrier 110 is not configured at the center of the total bandwidth allocation 100 (i.e., it is offset from the center).

[0030] As call setup and / or traffic through the cell increases, bandwidth will need to be increased. For example... Figure 2B As shown, a new second carrier 120 is configured. This has a higher bandwidth than the first carrier 110, and it is transmitted in a separate portion of the spectrum allocation 100 that does not overlap with the initial first carrier 110. After the transmission of the new second carrier 120 begins, a handover is triggered for all calls and users on the first carrier 110. Figure 2C As shown, the first carrier 110 is turned off, leaving only the second carrier 120, but with a higher bandwidth than the first carrier 110. This process can be repeated with even higher bandwidth carriers, provided the bandwidths do not overlap and there is sufficient capacity in channel 100.

[0031] Now refer to Figure 3A , 3B And 3C, according to the second example, schematically depicts the transmission in the spectrum. In Figure 3A The image shows the bandwidth allocation for cell 100. This is consistent with... Figure 2A The same applies here, and the description of the graph above also applies.

[0032] As call setup and / or traffic through the cell increases, bandwidth will need to be increased. For example... Figure 3B As shown, a new second carrier 130 is configured. This has a higher bandwidth than the first carrier 110, but is transmitted to overlap with the initial first carrier 110 (i.e., the two carrier portions share the same spectrum). The second carrier 130 can be divided into three parts: a lower frequency non-overlapping portion 131; an overlapping portion 132; and a higher frequency non-overlapping portion 133. In the overlapping portion 132, the second carrier 130 is configured to mute the physical resource block (PRB) of traffic including the cell reference signal (CRS). This mitigates the risk of interference to the first carrier 110 received by a user or mobile terminal. For example, mute for interference mitigation is described in “Co-channel interference management using eICIC / FeICIC with coordinated scheduling for the coexistence of PS-LTE and LTE-R networks” by Chen et al. (2017) 2017:34 in the journal EURASIP in Wireless Communications and Networks.

[0033] The BCH is transmitted within 1.08 MHz of the center of the new second carrier 130, i.e., within the non-overlapping portion 131 of the example shown. Therefore, it does not overlap with the initial first carrier 110, allowing the user or mobile terminal to read the new cell directly (and without interference). This is at least partly a result of the first initial carrier 110 being offset from the center of the spectrum allocation 100.

[0034] After the transmission of the new second carrier 130 begins, a handover is triggered for all calls and users on the first carrier 110. For example... Figure 3C As shown, the first carrier 110 is turned off, leaving only the second carrier 130, but with a higher bandwidth than the first carrier 110. This process can be repeated with carriers of even higher bandwidths, provided there is sufficient capacity in channel 100.

[0035] Returning to the general meaning of the discussion above, one embodiment can be considered in which a second portion of a predetermined spectrum channel overlaps with a first portion of the predetermined spectrum channel. Then, advantageously, the transmission of a portion of the second carrier signal that overlaps with the first carrier signal is suppressed. For example, the suppressed portion of the second carrier signal may have a transmission power level insufficient to interfere with the reception of the first carrier signal. This could be a transmission power level no greater than (or less than) 50% (3dB), 25% (6dB), 12.5% ​​(9dB), 6.25% (12dB), 3.125% (15dB), 1% (20dB), or some lower percentage of the average transmission power level of the remaining portion of the second carrier signal. Optionally, no reference signal (such as a cell-specific reference signal or CRS) is transmitted within the suppressed portion of the second carrier signal. Advantageously, the first and second carrier signals are configured such that the broadcast channel of the first carrier signal does not overlap with the broadcast channel of the second carrier signal. The broadcast channel can be configured within a predetermined frequency limit compared to the center of the respective carrier signal. Configuring the broadcast channel in this way, by offsetting the center of the first carrier signal and / or the second carrier signal, becomes simpler compared to the center of a predetermined spectrum channel. Advantageously, the broadcast channel of the second carrier signal is transmitted within the second carrier signal and is not within the suppressed portion of the second carrier signal.

[0036] In an alternative embodiment, the second portion of the predetermined spectrum channel does not overlap with the first portion of the predetermined spectrum channel. In this way, the first and second carriers can be transmitted simultaneously without any adjustments to them. However, the bandwidth of the second carrier may be limited by the total bandwidth of the predetermined spectrum channel minus the bandwidth of the first carrier signal (i.e., the first portion of the predetermined spectrum channel). The bandwidth of the second carrier may be further limited due to any guard band implemented between the first and second carriers.

[0037] Reconsidering again the specific implementation details of the examples according to this disclosure, it will be noted that the techniques and processes described herein are particularly useful for RANs provided by HAPs or types of HAPs, which may include HAPs in accordance with this disclosure. For example, referring to the previously discussed... Figure 1 The baseband system 30 can indicate cells, and for each cell, one or more associated elements: beam; bandwidth; power; allocated frequency band and / or channel; carrier; frequency offset within the channel (e.g., compared to the channel center or edge). Handover instructions can also form a portion of the signal provided by the baseband system 30.

[0038] The power of the initial and new carriers may vary; for example, the power spectral density may remain the same despite changes in bandwidth between carriers. While a carrier can be transmitted by multiple beams, the power transmitting that carrier can vary between beams. In the case of two carriers that do not overlap and are transmitted by the same one or more beams, this is equivalent to two parallel transmitters with different carriers.

[0039] In the general terminology discussed earlier, the first and second carrier signals are transmitted via a HAP (which may include satellites, aircraft, spacecraft, unmanned aerial vehicles, or similar devices). The HAP advantageously has an antenna system that defines multiple beams, such that each beam provides an independent geographic coverage area. The first and second carrier signals are then transmitted by at least one of the multiple beams. Therefore, the first and second carrier signals can be transmitted by a set of one or more beams from the multiple beams, wherein the first and second carrier signals may optionally be transmitted by the same set of one or more beams.

[0040] The transmission power levels of the first carrier signal and the second carrier signal can be different. For example, the power spectral density of the first carrier signal and the second carrier signal transmitted can be the same.

[0041] In an embodiment, configuring the transmission of the second carrier signal includes transmitting configuration data from the baseband system to the HAP. The configuration data indicates at least one parameter of the second carrier signal and / or at least one parameter of the first carrier signal. One or more parameters may include one or more of the following: transmission power of the carrier for each of a plurality of beams used to transmit the respective carrier signal; bandwidth of the respective carrier signal; transmission frequency band and / or channel of the respective carrier signal; and offset of the transmission of the respective carrier signal within the channel (compared to a fixed point in the channel, such as an edge or center). At least one parameter of the second carrier signal and / or at least one parameter of the first carrier signal may be transmitted in the form of a lookup table.

[0042] Now refer to Figure 4A flowchart of the method according to this disclosure is shown. In a first step 200, a first carrier signal of a first bandwidth is transmitted in a first portion of a predetermined spectrum allocation (channel). Specifically, the first carrier signal is transmitted via a HAP to allow access to a cellular radio network. In a second step 210, a second carrier signal is configured. The second carrier signal has a second bandwidth different from the first bandwidth. The second carrier signal is located in a second portion of the predetermined spectrum allocation (channel), which is different from the first portion. This configuration can be achieved by instructing the HAP, for example, by transmitting and / or receiving instructions (such instructions include messages, one or more information elements, lookup tables, or other command or instruction formats) from a configuration system. The configuration system is typically separate from the HAP and is typically located remotely from the HAP (e.g., on the ground). The second carrier signal can be implemented in any form disclosed herein, such that it does not overlap with the first carrier signal or overlaps with the first carrier signal. After the configuration of the second carrier signal, the second carrier is transmitted such that the first carrier signal and the second carrier signal are transmitted simultaneously.

[0043] In the third step 220, the handover of service from the first carrier signal to the second carrier signal is configured. This can be achieved by instructing user equipment or terminals connected using the first carrier signal to switch to the second carrier signal (e.g., by sending such an instruction using the first carrier signal). Other mechanisms can be implemented to encourage the switch to the second carrier signal. In the fourth step 230 (which is preferred but not necessary, since the first carrier signal may not be used or may only be used infrequently once the second carrier signal is in use), the first carrier signal is configured to stop. Stopping the first carrier signal will prevent its transmission.

[0044] Now refer to Figure 5 A schematic block diagram of configuration system 300 is shown. As described above, the configuration system can be part of an existing portion of a RAN (Radio Area Network), such as a baseband system, or it can be a standalone unit or server typically coupled to the RAN (e.g., the baseband system). Configuration system 300 includes: input 310; processing section 320; and output 330. Configuration system 300 can be implemented by a computer (server) with appropriate interfaces, such as those described below.

[0045] Input 310 may include an interface to, for example, another part of the RAN of a baseband system. Input 310 may be configured to receive information about changes in bandwidth for a cell. This could be an instruction to change the bandwidth to a specific value or information indicating a new bandwidth for the cell. Processing section 320 (e.g., a processor or processor group) is then configured, for example, according to the reference above. Figure 4The described method determines the configuration for a cell. Output 330 then transmits this configuration to the HAP, for example, via a baseband system or other communication link. Input 310 and output 330 can be separate interfaces, or they can be provided by a combined input / output interface to configuration system 300.

[0046] While specific embodiments have now been described, those skilled in the art will understand that various modifications and variations are possible. Furthermore, combinations of any particular features shown with reference to one or more embodiments are provided, even if such combinations are not explicitly detailed herein. For example, as demand increases further, a new non-overlapping carrier for a cell may be followed by a new overlapping carrier for the cell.

[0047] For example, Figure 1 The specific architecture described is just an example, and alternative architectures are possible. The baseband can be implemented in a different way than discussed, and other interfaces can be used.

[0048] In the example where the overlapping portion of the second carrier is suppressed, the transmitted symbols within this portion do not need to be muted. Other forms of suppression, such as power reduction, coding, or similar methods, can be used instead.

Claims

1. A method for adjusting the bandwidth of a carrier signal used by a high-altitude platform (HAP) operating at an altitude of 20 km or above to provide access to a cellular radio network for a user terminal, the carrier signal being transmitted within a predetermined spectrum allocation, the HAP transmitting a first carrier signal of a first bandwidth in a first portion of the predetermined spectrum allocation, the first carrier signal corresponding to an existing cell, the method comprising: In the second part of the predetermined spectrum allocation, the transmission of a new second carrier signal with a second bandwidth by the HAP is configured, the second bandwidth being different from the first bandwidth, and the second carrier signal corresponding to a new cell provided by the HAP; as well as Configure the switching of services from the first carrier signal to the second carrier signal.

2. The method according to claim 1, wherein the second bandwidth is greater than the first bandwidth.

3. The method of claim 2, wherein the step of configuring the transmission of the second carrier signal is in response to the identification of an additional service by an additional user terminal provided by the first carrier signal or connected to an additional user terminal provided by the first carrier signal.

4. The method according to any one of claims 1-3, wherein the first portion of the predetermined spectrum allocation is offset from the center of the predetermined spectrum allocation.

5. The method according to any one of claims 1-3, wherein the second bandwidth is less than the entire bandwidth of the predetermined spectrum allocation, and wherein the second portion of the predetermined spectrum allocation is offset from the center of the predetermined spectrum allocation.

6. The method according to any one of claims 1-3, further comprising: Configure the first carrier signal to stop.

7. The method according to any one of claims 1-3, wherein the first carrier signal and the second carrier signal are orthogonal frequency division multiplexing (OFDM) signals.

8. The method according to any one of claims 1-3, wherein the second portion of the predetermined spectrum allocation overlaps with the first portion of the predetermined spectrum allocation, and wherein the transmission of the portion of the second carrier signal overlapping with the first carrier signal is suppressed or muted.

9. The method of claim 8, wherein the suppression or mute portion of the second carrier signal has a transmission power level insufficient to interfere with the reception of the first carrier signal.

10. The method of claim 8, wherein no reference signal is transmitted within the suppressed or muted portion of the second carrier signal.

11. The method of claim 8, wherein the first carrier signal and the second carrier signal are configured such that the broadcast allocation of the first carrier signal does not overlap with the broadcast allocation of the second carrier signal.

12. The method according to any one of claims 1 to 3, wherein the second portion of the predetermined spectrum allocation does not overlap with the first portion of the predetermined spectrum allocation.

13. The method according to any one of claims 1-3, wherein the HAP has an antenna system that defines a plurality of beams such that the beams provide independent geographic coverage areas, and the first and second carrier signals are transmitted by the same at least one of the plurality of beams.

14. The method according to any one of claims 1-3, wherein the step of configuring the transmission of the second carrier signal comprises: Configuration data is transmitted from the baseband system to the HAP, the configuration data indicating at least one parameter in the second carrier signal.

15. A configuration system for adjusting the bandwidth of a carrier signal providing access to a cellular radio network via a high-altitude platform (HAP) operating at an altitude of 20 km or above, the configuration system being arranged to perform the method of any one of the preceding claims.

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