Improving return link capacity by using overlapping return link channels

Abstract

Described herein are systems and methods for improving or optimizing return link capacity by employing overlapping return link channels within a return channel group (RCG) for a communication system shared by multiple user terminals. The disclosed techniques allow for simultaneous use of different return link channel configurations while reducing or eliminating the need for additional overhead messages associated with changing the configuration of the RCG. The disclosed techniques allow for more efficient use of return link capacity by responding in real time to changing conditions and demands.

Description

[Technical Field]

[0001] TECHNICAL FIELD This disclosure relates generally to allocating transmission resources in communication systems. [Background technology]

[0002] Network communications involve the transmission and reception of data between nodes such as content servers and user terminals. To transmit user data over a network, a scheduler can be used to allocate network resources to devices and create transmission schedules for the devices. Based on the schedule, individual devices can then transmit data using the allocated resources. Based on the schedule, user terminals can transmit data to a gateway, which is part of the communication system, for forwarding to its final destination. Summary of the Invention

[0003] In a first aspect, the present disclosure provides a method of communicating in a communication system. The method includes receiving a request for return link bandwidth from a first user terminal and from a second user terminal. The method also includes assigning a first return link channel to the first user terminal based at least in part on transmission characteristics of the first user terminal, the first return link channel being selected from a plurality of return link channels grouped into a return channel group, the first return link channel including a first frequency band. The method also includes assigning a first transmission allowed period to the first user terminal. The method also includes assigning a second return link channel to a second user terminal based at least in part on transmission characteristics of the second user terminal, the second return link channel being selected from a plurality of return link channels in the return channel group, the second return link channel including a second frequency band. The method also includes assigning a second transmission allowed period to the second user terminal. The method also includes communicating the first return link channel, the first transmission allowed period, the second return link channel, and the second transmission allowed period to a corresponding user terminal. The multiple return link channels in the return channel group each have different transmission characteristics, with at least one return link channel having a frequency band that at least partially overlaps with a frequency band of another return link channel.

[0004] In some embodiments of the first aspect, the first user terminal has a different transmission rate than the second user terminal.

[0005] In some embodiments of the first aspect, the method further includes determining whether the first frequency band at least partially overlaps with the second frequency band and determining whether the first transmission allowed period at least partially overlaps with the second transmission allowed period. In further embodiments, the method includes, in response to determining that the first frequency band at least partially overlaps with the second frequency band and the first transmission allowed period at least partially overlaps with the second transmission allowed period, assigning a third return link channel to the first user terminal, the third return link channel having a third frequency band that does not overlap with the second frequency band. In further embodiments, the method includes, in response to determining that the first frequency band at least partially overlaps with the second frequency band and the first transmission allowed period at least partially overlaps with the second transmission allowed period, assigning a third transmission allowed period to the first user terminal, where the third transmission allowed period does not overlap with the second transmission allowed period. In a further embodiment, communicating the assigned return link channel and transmission allowed period to the first and second user terminals is performed in response to determining that the first frequency band does not overlap with the second frequency band or that the first transmission allowed period does not overlap with the second transmission allowed period.

[0006] In some embodiments of the first aspect, the return channel group is hard-coded to the first user terminal and the second user terminal. In some embodiments of the first aspect, all possible return link channels of the communication system are included in the return channel group. In some embodiments of the first aspect, each return link channel in the return channel group has a common center frequency. In some embodiments of the first aspect, each return link channel in the return channel group has a common lower edge frequency.

[0007] In some embodiments of the first aspect, the method further includes periodically transmitting a return channel group (RCG) descriptor message to the first user terminal and the second user terminal, the RCG descriptor message including updates to the return channel group. In further embodiments, the RCG descriptor message adds a return link channel to the return channel group, adjusts a center frequency of a return link channel in the return channel group, or adjusts a bandwidth of a return link channel in the return channel group.

[0008] In some embodiments of the first aspect, the first return link channel has a bandwidth equal to or greater than a transmission rate of the first user terminal, and the second return link channel has a bandwidth equal to or greater than a transmission rate of the second user terminal. In some embodiments of the first aspect, channel conditions in the communication system cause degraded transmission characteristics of the first user terminal, and the first return link channel is assigned to the first user terminal based at least in part on the degraded transmission characteristics.

[0009] In a second aspect, the present disclosure provides a communications system for providing communications over a network. The system includes a first user terminal having a first maximum bandwidth, the first user terminal configured to store a return channel group including a plurality of return link channels. The system also includes a second user terminal having a second maximum bandwidth, the second user terminal configured to store the return channel group. The system also includes a gateway configured to communicate with the first user terminal and the second user terminal over the network. The gateway includes a scheduler configured to store a return channel group, assign a first return link channel from the return channel group to a first user terminal based at least in part on a first maximum bandwidth (the first return link channel including a first frequency band), assign a first transmission allowed period to the first user terminal, assign a second return link channel from the return channel group to a second user terminal based at least in part on a second maximum bandwidth (the second return link channel including a second frequency band), assign a second transmission allowed period to the second user terminal, and communicate the first return link channel, the first transmission allowed period, the second return link channel, and the second transmission allowed period to the corresponding user terminal. The multiple return link channels in the return channel group each have different transmission characteristics, with at least one return link channel having a frequency band that at least partially overlaps with the frequency band of another return link channel.

[0010] In some embodiments of the second aspect, the network comprises a satellite network having at least one low Earth orbit satellite. In some embodiments of the second aspect, the network comprises a satellite network having at least one medium Earth orbit satellite. In some embodiments of the second aspect, the network comprises a satellite network having at least one geostationary Earth orbit satellite. In some embodiments of the second aspect, the network comprises a terrestrial network. In some embodiments of the second aspect, the network comprises a cellular network.

[0011] In some embodiments of the second aspect, the first maximum bandwidth is different from the second maximum bandwidth. In some embodiments of the second aspect, the duty cycle of the first user terminal is different from the duty cycle of the second user terminal.

[0012] In some embodiments of the second aspect, the first return link channel is assigned based at least in part on channel conditions that reduce a duty cycle of the first user terminal. In some embodiments of the second aspect, the first return link channel is assigned based at least in part on channel conditions that reduce a first maximum bandwidth.

[0013] In a third aspect, the present disclosure provides a scheduler in a communication system. The scheduler includes a network interface configured to communicate with a first user terminal and a second user terminal via the communication system. The scheduler also includes a data store configured to store computer-executable instructions for generating a return link schedule that allocates return link bandwidth to the user terminals in response to a request for return link bandwidth from the user terminals, and to store a return channel group including a plurality of return link channels. The scheduler also includes a processor configured to execute the computer-executable instructions to allocate a first return link channel including a first frequency band from the return channel group to the first user terminal, allocate a first transmission allowance period to the first user terminal, allocate a second return link channel including a second frequency band from the return channel group to a second user terminal, and allocate a second transmission allowance period to the second user terminal, and communicate the first return link channel, the first transmission allowance period, the second return link channel, and the second transmission allowance period to the corresponding user terminal. The return link channels in the return channel group each have different transmission characteristics, and the frequency band of at least one return link channel at least partially overlaps with the frequency band of another return link channel.

[0014] In some embodiments of the third aspect, the processor is further configured to determine whether the first frequency band at least partially overlaps with the second frequency band and whether the first transmission allowed period at least partially overlaps with the second transmission allowed period. In further embodiments, in response to determining that the first frequency band at least partially overlaps with the second frequency band and the first transmission allowed period at least partially overlaps with the second transmission allowed period, the processor is further configured to assign a third return link channel to the first user terminal, the third return link channel having a third frequency band that does not overlap with the second frequency band. In further embodiments, in response to determining that the first frequency band at least partially overlaps with the second frequency band and the first transmission allowed period at least partially overlaps with the second transmission allowed period, the processor is further configured to assign a third transmission allowed period to the first user terminal, the third transmission allowed period that does not overlap with the second transmission allowed period. In a further embodiment, the processor is configured to communicate the assigned return link channel and transmission allowed period to the first and second user terminals in response to determining that the first frequency band does not overlap with the second frequency band or the first transmission allowed period does not overlap with the second transmission allowed period.

[0015] In some embodiments of the third aspect, all possible return link channels of the communication system are included in the return channel group.

[0016] In some embodiments of the third aspect, the processor is further configured to periodically send an RCG descriptor message to the first user terminal and the second user terminal, the RCG descriptor message including an update of the return channel group. In further embodiments, the RCG descriptor message adds a return link channel to the return channel group, adjusts a center frequency of the return link channel in the return channel group, or adjusts a bandwidth of the return link channel in the return channel group.

[0017] For purposes of summarizing the disclosure, certain aspects, advantages, and novel features have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with a particular embodiment. Thus, a disclosed embodiment may be implemented in a manner that achieves or optimizes one advantage or advantages taught herein, without necessarily achieving other advantages that may be taught or suggested herein.

[0018] The accompanying drawings depict various embodiments for purposes of illustration and should not be construed as limiting the scope of the present disclosure in any way. Furthermore, various features of different disclosed embodiments may be combined to form additional embodiments that are part of this disclosure. [Brief explanation of the drawings]

[0019] [Figure 1A] FIG. 1A illustrates a diagram of an exemplary communications system that uses a satellite network and a scheduler to provide and manage communications between multiple user terminals and multiple gateway routing devices to provide access to a network (e.g., the Internet). [Figure 1B] FIG. 1B illustrates another exemplary communications system including an access network and a scheduler that provides and manages communications between multiple user terminals and multiple gateway routing devices to provide access to the Internet (or other suitable network). [Figure 2A] FIG. 2A shows that each user terminal requests a resource grant on the satellite network from the scheduler via a gateway routing device. [Figure 2B] FIG. 2B shows that a scheduler allocates resource blocks (time-frequency resources) in one or more time slots to accommodate resource requests from user terminals. [Figure 2C] FIG. 2C shows that the user terminal transmits data from the buffer according to the time-frequency resources allocated by the scheduler. [Figure 3A] FIG. 3A illustrates an example of multiple return channel groups (RCGs), each of which does not include overlapping return link channels, configured for use in a particular communication system. [Figure 3B] FIG. 3B illustrates an example of an RCG channelization that provides overlapping return link channels and provides improved functionality compared to the RCG channelization set of FIG. 3A. [Figure 4A] FIG. 4A shows an example of an RCG with one return link channel having a frequency band that overlaps with two other return link channels. [Figure 4B] FIG. 4B shows an exemplary resource grant map that assigns different user terminals to different return link channels, which correspond to the return link channels in the RCG of FIG. 4A. [Figure 4C] FIG. 4C illustrates another exemplary resource permission map. [Figure 5A] FIG. 5A shows intra-slot allocations in a resource grant map. [Figure 5B] FIG. 5B shows the inter-slot allocation within the resource grant map. [Figure 6] FIG. 6 illustrates a flowchart of an exemplary method of communicating over a communication system supporting return channel groups with overlapping channelization. [Figure 7] FIG. 7 shows a block diagram of an example scheduler configured to allocate resource grants to multiple user terminals using an RCG with overlapping channelization. DETAILED DESCRIPTION OF THE INVENTION

[0020] Headings, if any, provided herein are for convenience only and do not necessarily affect the scope or meaning of the claimed embodiments.

[0021] overview A communication system can simultaneously communicate with multiple terminals on a forward link and a return link. The forward link refers to the communication link from a base station to the terminals, and the return link refers to the communication link from the terminals to the base station. Multiple terminals may simultaneously transmit data on the return link and / or receive data on the forward link. The number of terminals that can communicate with a communication system at any one time may be constrained by the number of physical channels available for data transmission, which in turn are constrained by available system resources.

[0022] Various return link channels can be defined to manage transmissions from user terminals on a communication system. A return link channel may be defined with appropriate transmission characteristics, such as a characteristic frequency (e.g., a center frequency, a lower end frequency, an upper end frequency, a frequency offset, etc.) and a bandwidth (e.g., a transmission rate). A return link channel can be defined to correspond to a particular transmission rate (e.g., a symbol rate or a chip rate). Thus, a user terminal can be allocated transmission resources by requesting the resources and being assigned a return link channel to use for return link transmissions during a transmission grant period.

[0023] In some embodiments, multiple return link channels can be grouped into a return channel group (RCG). An RCG can include multiple return link channels to provide return link channels for various transmission rates. In an RCG shared by multiple user terminals, the return link channels can be defined to be sequential and non-overlapping to reduce or minimize interference and increase or maximize capacity. An RCG defined in this manner can minimize interference, at least in part because the frequency bands of the return link channels do not overlap with each other, and maximize capacity, at least in part because the frequency bands are sequential (e.g., the frequency bands of the return link channels are adjacent to each other).

[0024] A user terminal is assigned transmission resources on the return link using a return link channel from the RCG. The RCG may be conveyed to the user terminal using a message (e.g., an RCG descriptor message) that propagates a description of the set of return link channels for the RCG throughout the communication system. The message used to communicate the RCG may be accomplished using any suitable broadcast message that a communication system may use to transmit system information related to return link assignments to multiple user terminals.

[0025] When it is desirable to use an RCG with a different lineup of non-overlapping return link channels (e.g., to accommodate the arrival of a high-data-rate user terminal or due to a rain attenuation event), the channel lineup change must be propagated throughout the communication system, which can take an undesirably long time (e.g., several minutes) to accomplish. This delay results from the process used to update the RCG, in which a network component (e.g., a scheduler) determines that it is advantageous to change the RCG based on changes in user traffic demands or channel conditions. This process involves propagating the RCG to the user terminal using over-the-air (OTA) messages. Other components in the network (e.g., physical layer processing modules) may also require updated RCG information in order to retune their components with the new channelization profile. This process may also involve the user terminal adjusting its transmit chain to adapt to the new RCG. For example, the user terminal may need to refine its physical layer control loop to optimize its transmit parameters over the newly defined RCG. These steps in the process may require one or more round trips over the radio link. This process can take an undesirably long time, for example, more than several minutes for geosynchronous satellite links, making it difficult to quickly respond to changing conditions in the communications network that may affect the effectiveness or usefulness of the current RCG.

[0026] For example, a situation may arise in which channel conditions deteriorate (e.g., rainfall may adversely affect the transmission capacity of a satellite communications system). In such a situation, it may be desirable to use a different RCG that includes more return link channels for lower transmission rates than defined in the current RCG. This may be done to accommodate user terminals whose transmission rates decrease under such circumstances. Otherwise, the deterioration of channel conditions may result in bandwidth being allocated to user terminals that are unable to utilize all of their allocated bandwidth, reducing the efficiency of the communications system. As another example, a high-capacity user terminal may sporadically request higher-throughput return link traffic. In such a situation, it may be desirable to use a different RCG that includes available return link channels for higher transmission rates that are not defined in the current RCG. Otherwise, unused transmission capacity would exist in the communications system.

[0027] In situations such as these, it may take an undesirably long time to propagate different RCGs to user terminals and other components of a communication system, as described herein. Accordingly, systems and methods are described herein that improve or optimize return link capacity by employing overlapping return link channels within an RCG of a communication system shared by multiple user terminals. The disclosed techniques enable the simultaneous use of different return link channel configurations while reducing or eliminating the need for additional overhead messaging associated with changing RCGs. The disclosed techniques enable more efficient use of return link capacity by responding in real time to changing conditions or demands.

[0028] The disclosed systems and methods specify multiple return link channels within a communication system and define an RCG to include each of these channels, with two or more of the channels overlapping in frequency. In some embodiments, the RCG includes all possible return link channels in the communication system. In various embodiments, the return link channels are defined in the RCG using unique channel identifiers and frequency offsets. In some embodiments, this RCG may be hard-coded into both the user terminal and the scheduler or other components, such as a base station or ground station. In certain embodiments, a periodic message is transmitted containing a list of all channels in the RCG (including overlapping channels). In such embodiments, the user terminal reads the message to understand the return link channelization defined by the communication system. This can be done to preserve the flexibility of the communication system to change the channelization, which can be beneficial as the network evolves and new channels are introduced.

[0029] Because the channels in the disclosed RCG overlap, not all channels defined in the RCG can be used simultaneously. Therefore, a scheduler or other component in the communication system is configured to schedule user terminals in a non-overlapping manner. Non-overlapping time-frequency assignments avoid co-channel interference in certain communication systems, such as those employing multi-frequency time division multiple access (MF-TDMA). For example, if a user terminal is scheduled to transmit on a first channel in a first time period, the scheduler is configured to not allow other user terminals to transmit on channels having frequency bands that overlap with the frequency band of the first channel during a time period that overlaps with the first time period.

[0030] Advantageously, the disclosed technology can eliminate the need for channel reconfiguration algorithms or messaging, at least in part because the disclosed RCGs include many or all possible channel configurations available in a communication system. Advantageously, the disclosed technology also allows terminals with different capabilities to coexist in a communication system. For example, a terminal capable of transmitting at 160 Mcps (megachips per second) can coexist with a terminal capable of transmitting at only 10 Mcps with little wasted bandwidth. Furthermore, the disclosed technology advantageously allows different combinations of communication capabilities to exist and be active simultaneously on different sides of a communication system. For example, a first beam of a satellite could employ a channelization that allows transmission at 160 Mcps, while another beam of the satellite could employ a channelization that does not include transmission at 160 Mcps.

[0031] Communication system example 1A shows a diagram of an exemplary communication system 100a that uses a satellite network 140a to communicatively couple multiple user terminals 110a, 110b, 110c and multiple gateway routing devices 150a, 150b to one another and provide access to a network (such as the Internet 160). The communication system 100a includes a scheduler 170 configured to allocate resource grants to the user terminals 110a, 110b, 110c. The communication system 100a includes multiple gateway satellite transceivers 130a, 130b and multiple customer satellite transceivers 120a, 120b, 120c configured to transmit and receive signals via satellites 105.

[0032] The communications system 100a may utilize various network architectures, including a space segment and a ground segment. The satellite network 140a incorporates these components to provide communications between multiple user terminals 110a, 110b, 110c and gateway routing devices 150a, 150b. For example, the space segment may include one or more satellites, and the ground segment may include one or more satellite user terminals, gateway terminals, a network operations center (NOC), a satellite and gateway terminal command center, and / or the like. Some of these components are not illustrated for clarity. The satellite network 140a may include one or more geosynchronous orbit (GEO) satellites, one or more medium earth orbit (MEO) satellites, and / or one or more low earth orbit (LEO) satellites. It should be understood that satellite 105 may represent one or more satellites, and that the one or more satellites may include GEO satellites, MEO satellites, LEO satellites, or any combination thereof.

[0033] The user terminals 110a, 110b, and 110c may include routers or other user equipment and may be configured to transmit and receive data routed through the communication system 100a. The user terminals 110a, 110b, and 110c may include or be communicatively coupled to any type of consumer premises equipment (e.g., telephones, modems, routers, computers, set-top boxes, etc.). The user terminals 110a, 110b, and 110c are configured to transmit and receive data using the satellite network 140a via respective customer satellite transceivers 120a, 120b, and 120c. The customer satellite transceivers 120a, 120b, and 120c may include a phased array antenna, two antennas (e.g., one transmit and one receive antenna), or multiple antennas, each accessing a different satellite or communication path.

[0034] The satellite network 140a provides forward links for transmitting information from the gateway routing devices 150a, 150b to the user terminals 110a, 110b, and 110c, and return links for transmitting information from the user terminals 110a, 110b, and 110c to the gateway routing devices 150a, 150b. The forward and return links are sometimes referred to as over-the-air (OTA) signals or communication paths. The forward links include transmission paths from the gateway routing devices 150a, 150b through the respective gateway satellite transceivers 130a, 130b, via satellite uplink channels to the satellite 105, via satellite downlink channels to the customer satellite transceivers 120a, 120b, and 120c, and to the user terminals 110a, 110b, and 110c. The return link includes a transmission path from the user terminal 110a, 110b, 110c through the respective customer satellite transceiver 120a, 120b, 120c, via a satellite uplink channel to the satellite 105, via a satellite downlink channel to the gateway satellite transceiver 130a, 130b, and to the gateway routing device 150a, 150b. It should be understood that each communication path may utilize multiple satellites and transceivers.

[0035] Scheduler 170 is configured to manage the allocation of communication resources to user terminals 110a, 110b, and 110c. Scheduler 170 can be part of gateway routing devices 150a, 150b or can be a separate component of communication system 100a. Furthermore, communication resources may be managed by multiple components of communication system 100a. In some embodiments, some or all of gateway routing devices 150a, 150b and / or scheduler 170 may be located in a virtual device residing in a public or private computing cloud and / or as part of a distributed computing environment. Scheduler 170 may be configured to manage resources for multiple gateway routing devices 150a, 150b, as well as user terminals 110a, 110b, and 110c.

[0036] In some embodiments, one or more of the user terminals 110a, 110b, 110c may be configured to communicate using different customer satellite transceivers 120a, 120b, 120c with different communication systems (e.g., satellite systems such as GEO, MEO, and / or LEO satellites, cellular systems such as Long Term Evolution (LTE) technology, and / or terrestrial systems such as Digital Subscriber Line (DSL)). Thus, for the user terminals 110a, 110b, 110c, multiple communication paths may exist between the user terminal and the Internet 160. In some embodiments, the communication system 100a (e.g., the scheduler 170) is configured to select a desirable, efficient, or optimal communication path for the user terminal 110a, 110b, 110c from among multiple communication paths available to the user terminal.

[0037] As described herein, return link channels are grouped into return channel groups (RCGs). An RCG disclosed herein includes multiple return link channels, with at least one return link channel having a frequency band that overlaps with another return link channel. In some embodiments, an RCG disclosed herein specifies many or all possible return link channels available to communication system 100a. A communication system, such as communication system 100a, has a finite number of channels that can be used in the system, and the number of channels depends on various system limitations, such as time and frequency quantization and system number theory. In certain implementations, the number of return link channels may be limited by the available frequency band. As used herein, all possible return link channels in a communication system may be defined as the total number of return link channels available in the communication system, which depends on various system parameters. For example, a communication system may use an RCG defined in a licensed spectrum that is uniquely determined by a frequency span (e.g., parameterized by a lower end frequency, an upper end frequency, and a channel bandwidth). Given a frequency band, a simple channelization scheme for return link channels in an RCG may include several parameters, such as a minimum channel bandwidth and a scale factor. In such a channelization scheme, the bandwidth of each return link channel is BW_min*SF^nMcps, where BW_min is the minimum channel bandwidth, SF is the scale factor, and n is a non-zero positive integer. Therefore, it is possible to determine the set of all possible return link channels for a given scheme.

[0038] As a specific example, a communication system may use 500 MHz channels in the Ka band spanning the 21.0 GHz to 21.5 GHz frequency range, with a minimum channel bandwidth (BW_min) of 5 Mcps and a scale factor (SF) of 2. The possible return link channel bandwidth in this scheme is 5*2^n Mcps. Since the maximum bandwidth of the RCG is 500 MHz, the maximum return link channel bandwidth is 320 Mcps. In other words, with this channeling scheme, the possible return channel bandwidths are 5, 10, 20, 40, 80, 160, and 320 Mcps. Considering the bandwidth of the frequency range, the set of all possible return link channels for this scheme includes 100 possible 5 Mcps channels, 50 possible 10 Mcps channels, 25 possible 20 Mcps channels, 12 possible 40 Mcps channels, 6 possible 80 Mcps channels, 3 possible 160 Mcps channels, and 1 possible 320 Mcps channel. In some embodiments, overlapping channels of different bandwidths can have a common lower end frequency. In various embodiments, overlapping channels may have a common center frequency.

[0039] In some embodiments, the RCG is hard-coded into the scheduler 170 and the user terminals 110a, 110b, 110c. In some embodiments, the RCG can be changed by the scheduler 170, and changes to the RCG can be communicated to the user terminals 110a, 110b, 110c and other components of the communication system 100a through RCG descriptor messages.

[0040] The scheduler 170 is configured to allocate transmission resources on the return link to the user terminals 110a, 110b, and 110c using the RCG. For example, for each user terminal 110a, 110b, and 110c requesting bandwidth on the return link, the scheduler 170 allocates a transmission permission period and a return link channel from the RCG. The return link channel has an associated frequency and bandwidth (e.g., corresponding to a frequency band). The scheduler 170 may be configured to allocate a return link channel to a particular user terminal based at least in part on the transmission characteristics of the corresponding user terminal. For example, the return link channel may be configured to correspond to a particular transmission rate (e.g., a symbol rate or a chip rate), and the scheduler 170 may be configured to allocate the return link channel to a user terminal capable of achieving the particular transmission rate supported by the return link channel. For example, the scheduler 170 may be configured to allocate a return link channel having a bandwidth accommodating a transmission rate of 80 Mcps to a user terminal capable of transmitting at 80 Mcps. The capabilities of a user terminal are affected by user terminal hardware components such as filters and amplifiers that affect transmission characteristics such as power and bandwidth. User terminal capabilities are also related to user terminal parameters such as maximum power and terminal antenna performance / off-axis. Thus, scheduler 170 is configured to allocate return link channels based at least in part on the capabilities of each user terminal, where capabilities are affected by components that affect transmission characteristics.

[0041] In some embodiments, scheduler 170 may assign different RCGs to different aspects of communication system 100a, such as satellite network 140a. For example, scheduler 170 may assign a first RCG having a first channelization scheme to a first communication link (e.g., a beam) of communication system 100a and a second RCG having a second channelization scheme different from the first channelization scheme to a second communication link. The different RCGs with different channelization schemes allow different devices to communicate simultaneously over the respective communication links.

[0042] For example, a first beam of satellite network 140a may serve one or more user terminals 110 (fixed and / or mobile) capable of transmitting at 80 Mcps and 160 Mcps and may be assigned a first RCG employing a first channelization scheme that enables device communication at both 80 Mcps and 160 Mcps. However, a second beam of satellite network 140a may serve one or more user terminals 110 (fixed and / or mobile) capable of transmitting at up to 80 Mcps and may be assigned a second RCG employing a second channelization scheme that does not enable device transmissions above 80 Mcps. Thus, the first RCG may include a first set or plurality of return link channels, and the second RCG may include a second set or plurality of return link channels that are different from the first set or plurality of return link channels. Based on these first and second RCGs, scheduler 170 can assign user terminal 110a communicating via a first beam a return link channel with a bandwidth corresponding to 160 Mcps in accordance with the first RCG channelization scheme, while scheduler 170 assigns user terminal 110b communicating via a second beam a return link channel with a bandwidth corresponding to only 80 Mcps in accordance with the second RCG channelization scheme. Thus, scheduler 170 can configure various aspects of communication system 100a (beams, paths, etc.) in different ways based on and suited to the characteristics of those aspects.

[0043] Based on the assignment from scheduler 170, each user terminal that has been assigned resources transmits data during the assigned time period using the assigned return link channel. The schedule for transmitting bursts on the return link may be predetermined by scheduler 170 based at least in part on the aggregate demand of user terminals 110a, 110b, 110c.

[0044] Accordingly, scheduler 170 is configured to receive resource requests (e.g., requests for return link bandwidth) from each user terminal 110a, 110b, 110c. For each received resource request, scheduler 170 is configured to determine a return link channel for the user terminal based at least in part on the transmission characteristics of the user terminal. Scheduler 170 is then configured to communicate the determined return link channel along with an assigned transmission permitted period to the corresponding user terminal.

[0045] The scheduler 170 is configured to determine whether the assigned return link channels have overlapping frequency bands and overlapping transmission grant periods. If the scheduler 170 determines that two resource grants overlap (e.g., if the frequency bands at least partially overlap within the at least partially overlapping period), the scheduler 170 may reallocate one resource grant to another return link channel. This may be repeated until there are no more overlapping resource grants. The scheduler 170 may be configured to allocate resource grants to various user terminals based on various parameters, such as, but not limited to, bandwidth requirements, quality of service parameters of the service flows (e.g., priority, guaranteed rate, latency, jitter, etc.), and / or waiting times of previous resource grants for the same user terminal or service flow in the scheduler queue. In some embodiments, the scheduler 170 is configured to allocate a resource grant to the user terminal at the head of the scheduler queue, after which the scheduler 170 is configured to mark the allocated resource grant (time / frequency resource) as available for subsequent allocation. This may reduce or eliminate the need to determine whether assigned resource grants overlap in time and frequency.

[0046] Scheduler 170 may then transmit resource grants or schedules to user terminals 110a, 110b, 110c. In some embodiments, the transmitted resource grants may provide permission to reference an index or other identifier of the return link channel to the corresponding user terminal. The user terminal may use the index or other identifier to look up the return link channel in the RCG stored in the user terminal and determine associated characteristics of the return link channel to enable transmission of bursts over satellite network 140a.

[0047] The scheduler 170 is configured to separate the transmissions of two user terminals in time when their frequency bands overlap. The scheduler 170 is configured to intelligently schedule the transmissions of return link channels that overlap in the frequency domain so that the transmissions do not overlap in the time domain. In this way, only one user terminal can transmit during a given period for a subset of overlapping return link channels (or channels that overlap in frequency bands). Similarly, the scheduler 170 is configured to intelligently schedule the transmissions of the return channels so that transmission allocations that overlap in the time domain do not overlap in the frequency domain. The scheduler 170 may implement any suitable technology, including but not limited to MF-TDMA technology, to achieve this scheduling.

[0048] The disclosed overlapping channelization techniques enable more efficient use of radio capacity on the return link, which can be particularly beneficial in high-throughput broadband satellite systems. As used herein, overlapping channelization may refer to the presence of return link channels with overlapping frequency bands within a single RCG used by a communications system to allocate transmission resources. A communications system utilizing overlapping channelization may implement an optimization technique to determine return link channel assignments that do not conflict or interfere with each other. This differs from certain channelization techniques that utilize non-overlapping and / or contiguous return link channels because such techniques do not include return link channels that interfere with each other. The disclosed overlapping channelization techniques enable more efficient use of return link capacity, at least in part, by allocating resources to accommodate the transmission capabilities or needs of user terminals in the system and adapting to changes in those transmission capabilities or needs. Certain channelization techniques do not respond quickly to changes in transmission capabilities or needs because such changes may require implementing and propagating different RCG configurations to user terminals, which can take an undesirably long time (e.g., several minutes) to implement and potentially cause network instability. Furthermore, in certain channelization techniques, the scheduler does not determine that having different channel configurations is beneficial; rather, different RCG channel sets are selected based on predetermined criteria, and changes between sets occur over a period of minutes. In contrast, scheduler 170 is configured to determine, from all possible channels represented in the overlapping channelization configurations, which channel is appropriate or optimal for each user terminal. As a result, different channel configurations can be implemented in real time and can also be reverted in real time.

[0049] FIG. 1B illustrates another exemplary communication system 100b including an access network 140b configured to communicatively connect multiple user terminals 110a, 110b to the Internet 160 (or other suitable network) via gateway routing devices 150a, 150b, which provide the functionality described herein with reference to FIG. 1A. The access network 140b may be a terrestrial network, a satellite network, a cellular network, or any combination of these networks. For example, the user terminals 110a, 110b may connect to the Internet 160 via the access network 140b, which includes a combination of a satellite network and a cellular network. The scheduler 170 also provides the functionality described herein with reference to FIG. 1A. In other words, the scheduler 170 allocates transmission resources to the user terminals 110a, 110b utilizing an RCG with overlapping return link channels. Thus, the communication system 100b can utilize the overlapping channelization techniques described herein and benefit from the advantages provided by such techniques. The scheduler 170 is also configured to manage transmission resources between the user terminals 110a, 110b and the gateway routing devices 150a, 150b.

[0050] Figures 2A, 2B, and 2C illustrate examples of scheduling and transmitting bursts according to an allocated resource schedule in the communication system 100a of Figure 1A. Note that a similar procedure can be implemented in the communication system 100b of Figure 1B. The procedures for allocating transmission resources in Figures 2A-2C advantageously utilize the overlapping channelization techniques described herein.

[0051] 2A shows that each of the user terminals 110a, 110b, and 110c requests resource grants 112a, 112b, and 112c on the satellite network 140a from a scheduler 170 via gateway routing devices 150a and 150b. The user terminals 110a, 110b, and 110c request resource grants from the scheduler 170 based on buffer sizes, quality of service (QoS) parameters, and other flow parameters. Each of the user terminals 110a, 110b, and 110c has associated transmission characteristics, such as a transmission rate. The scheduler 170 can determine a return link channel based at least in part on the user terminal's transmission characteristics.

[0052] 2B shows that scheduler 170 allocates resource grants 230 (time-frequency resources) to one or more time slots, such as time slot 220, to accommodate resource requests from user terminals 110a, 110b, and 110c. These allocations are based at least in part on the requests from user terminals 110a, 110b, and 110c and the transmission characteristics of user terminals 110a, 110b, and 110c. The allocations may be forwarded to user terminals 110a, 110b, and 110c via gateway routing devices 150a, 150b.

[0053] As shown in FIG. 2B, the scheduler 170 is configured to allocate resource grants 230 to the time slots 220 in a non-overlapping manner. An overlapping resource grant is a resource grant that at least partially overlaps in frequency with another resource grant for at least a portion of the time period. Here, the scheduler 170 allocates resource grants 230 in a non-overlapping manner. The scheduler 170 is configured to allocate non-overlapping resource grants even when overlapping channels are defined in the RCG. The allocated resource grants 230 may use the same or overlapping frequency bands, but reused or overlapping frequency bands are not used in the same time period. Similarly, multiple frequency bands can be used in the same time period as long as the frequency bands do not overlap. For example, resource grants 231-234 represent resource grants to the user terminals 110a, 110b, and 110c, where the width of the resource blocks 231-234 represents their duration and the height of the resource blocks 231-234 represents their frequency range. Resource grant 231 may be assigned to user terminal 110a, and resource grant 232 may be assigned to user terminal 110c, where resource grants 231, 232 are allowed to overlap in time because they span different frequencies. Resource grant 233 may be assigned to user terminal 110a, and resource grant 234 may be assigned to user terminal 110b, where resource grants 233, 234 are allowed to overlap in time because they span different frequencies. Furthermore, resource grants 231, 234 are allowed to overlap in frequency range because they span different time periods. Similarly, resource grants 232, 233 are allowed to overlap in frequency range because they span different time periods. Further examples of return link channel assignments are described herein with reference to Figures 4B, 4C, 5A, and 5B.

[0054] 2C illustrates user terminals 110a, 110b, and 110c transmitting data 114a, 114b, and 114c from their buffers according to time-frequency resources assigned by scheduler 170. Each time-frequency resource corresponds to a return link channel assigned during a transmission grant period, which is selected by scheduler 170 from an RCG, which includes overlapping return link channels. User terminals 110a, 110b, and 110c transmit data 114a, 114b, and 114c via the return link to gateway routing devices 150a and 150b via satellite network 140a. It should be understood that multiple gateways (e.g., gateway routing devices 150a and 150b) may be involved in receiving bursts from each user terminal 110a, 110b, and 110c. After arriving at gateway routing devices 150a and 150b, the data is transmitted toward Internet 160. Data from the Internet 160 may be transmitted by gateway routing devices 150a, 150b to user terminals 110a, 110b, 110c over the forward link of satellite network 140a. In some embodiments, scheduler 170 is also configured to manage transmission resources on the forward link of satellite network 140a similar to how a scheduler manages transmission resources on the return link.

[0055] Overlapping Channelization Example As described herein, the disclosed systems and methods provide definitions of return link channel partitions that support overlapping channels. The disclosed communication system supports many different return link channels with different transmission characteristics. Return channel groups can be defined to include many or all of the possible return link channels, resulting in overlapping return link channels (or frequency-overlapping return link channels) within the RCG.

[0056] FIG. 3A illustrates an example of multiple RCGs 301-304, each of which does not include overlapping channels, configured for use in a particular communication system. Each RCG set 301-304 defines a different RCG and can be implemented in different situations. For example, during a rain attenuation event, the communication system may switch from RCG set A 301 to RCG set B 302, RCG set C 303, or RCG set D 304 to accommodate the deteriorating transmission characteristics of the user terminal. However, as described herein, changing from RCG set A 301 to one of the other RCG sets 302, 303, or 304 may take an undesirably long time and may result in intermittent unavailability of portions of the spectrum, resulting in inefficient use of return link capacity. As another example, a user terminal may be capable of a higher data rate. To accommodate the higher data rate user terminal, RCG set A may be configured as the active RCG. However, if the high-data-rate user terminal only sporadically uses the 160 Mcps channels while RCG Set A is active, other user terminals that support only lower-data-rate channels (e.g., 80 Mcps) cannot use the portion of the spectrum reserved for the 160 Mcps channels, even when the high-data-rate user terminal is idle. In such a case, the entire 160 Mcps frequency band remains unused when the high-data-rate user terminal is not transmitting return link traffic. Using the disclosed overlapping return link channel technique, other user terminals can use the portion of the spectrum that would have been reserved for the 160 Mcps channels, thereby enabling more efficient use of return link capacity. Thus, the disclosed technology can be configured to use an RCG that includes many or all of the potentially overlapping return link channels, eliminating the need to switch RCGs during operation.

[0057] 3B illustrates an exemplary RCG 300 that provides multiple overlapping return link channels, which are useful in communication systems where changing channel conditions (e.g., severe weather such as rain in a satellite network) can degrade transmission characteristics, and where one or more dedicated terminals can generate sporadic demand for high-throughput return link traffic. The return link channels are uniquely identified using identifiers id1 through id40. In some embodiments, the identifiers of the return link channels can be used to indicate resource grants from the scheduler to the user terminals.

[0058] As an example, user terminals may transmit using a transmission rate of 80 Mcps under nominal conditions. However, when certain conditions occur (e.g., a rain attenuation event), these same user terminals may not be able to achieve the 80 Mcps transmission rate, but may only be able to achieve a transmission rate of 40 Mcps or 20 Mcps. RCG 300 allows for the rapid utilization of return link channels with reduced bandwidth. A scheduler, such as scheduler 170 or scheduler 770, is configured to incorporate grants into individual return link channels as needed, utilizing lower transmission rate channels as needed, depending on channel conditions within the communication system.

[0059] For example, the number of user terminals capable of transmitting at a particular chip rate (e.g., home channel) varies depending on channel conditions within the communication system. Under clear weather conditions, most terminals can close links at the highest chip rate, but during a rain attenuation event, many terminals may drop to a lower chip rate channel. Furthermore, a rain attenuation event may not affect all user terminals in the system uniformly, with some terminals converging to a higher chip rate channel while others settle at a lower chip rate. The RCG 300 advantageously enables a communication system (e.g., a scheduler) to dynamically adapt the RCG channelization to accommodate user terminals within the communication system, based at least in part on the preferred home channel. The RCG 300 also provides a flexible configuration that can be changed in response to changing conditions affecting the performance of user terminals within the communication system. The RCG 300 also provides a flexible configuration that can be changed in response to changing demands to accommodate high-throughput return link traffic within the communication system. Furthermore, the RCG 400 advantageously allows for switching return link channels on a timescale that does not cause network instability.

[0060] FIG. 4A shows an example of a return channel group or RCG 400 having one return link channel (id9) with a frequency band that overlaps with two other return link channels (id8 and id10). The return link channels of the RCG 400 are assigned indices id1 through id10 to uniquely identify each return link channel. Note that the index is merely one method for identifying a return link channel, and other methods may be employed to identify the return link channel. For example, a return link channel may be identified using a characteristic frequency (e.g., center frequency, lower end frequency, upper end frequency, frequency offset) and bandwidth (e.g., transmission rate, frequency bandwidth, etc.). A return link channel may be identified or defined using a frequency and the width of a frequency band, e.g., an offset from the center frequency of the frequency band and the channel bandwidth (e.g., in Msps, Mcps, or MHz). The identifier may be used to identify the corresponding return link channel within the RCG, for example, when allocating transmission resources or modifying or updating the RCG. For example, RCG 400 includes ten return link channels id1 to id10 with corresponding center frequencies f1 to f10. Return link channels id1 to id10 have transmission rates of 5 Mcps (id1), 10 Mcps (id2, id3), 40 Mcps (id4, id5), 80 Mcps (id6, id7, id8, and id9), and 160 Mcps (id10), respectively.

[0061] RCG 400 is an example of an RCG that can be used in a communications system with one or more dedicated terminals that may generate sporadic demand for high-throughput return link traffic. In this example, the dedicated user terminal may be capable of sustaining a transmission rate of 160 Mcps under nominal conditions. In response to a demand for high-throughput return link traffic, a scheduler (such as scheduler 170 or scheduler 770) may allocate return link channel id10 to the dedicated user terminal with a transmission rate of 160 Mcps. If that user terminal does not require return link bandwidth, it may allocate return link channels id8 and id9 without the possibility of transmission burst collisions.

[0062] An example is provided to illustrate one or more advantages of RCG 400. A particular user terminal with a low transmission rate (e.g., 5 or 10 Mcps) may not function on a return link channel with a high transmission rate (e.g., 160 Mcps). In some communication systems with a particular RCG (e.g., an RCG with non-overlapping and / or contiguous channelization as described herein with reference to FIG. 3A), a portion of the channelization is reserved for high-throughput user terminals (e.g., 160 Mcps), such as RCG 301 of FIG. 3A. This portion of the channelization may be unavailable to a particular low-transmission-rate user terminal, leaving a significant portion of the available bandwidth unusable when the high-throughput user terminal is not transmitting. In the disclosed RCG with overlapping channelization, high-throughput return link channels can be dynamically allocated without reserving a portion of the bandwidth for high-throughput user terminals. This allows low-throughput user terminals to utilize the available bandwidth because the low-throughput return link channels are also defined in an RCG with overlapping channelization (e.g., RCG 400). When a high-speed user terminal subsequently requests resources for a transmission burst, it is assigned the high-throughput channel and then resumes using the low-throughput channel. To replicate this functionality with a non-overlapping channelization approach would require a relatively large number of messages to communicate RCG changes to the user terminals of the communication system, which is undesirable, at least in part because of the delays in communicating such changes and / or the potential for them to cause network instability.

[0063] The RCG400 is configured to enable the 160 Mcps return link channel (id10) to be turned on on demand for selected terminals. When there is no demand, the return link channel utilization can revert to the normal channelization plan (e.g., a maximum transmission rate of 80 Mcps). This allows for desirable configuration flexibility. Furthermore, with the disclosed overlapping channelization technique, the dynamic return link channelization timescale does not destabilize the network. The disclosed overlapping channelization technique also reduces capacity loss and fairness for non-exclusive terminals.

[0064] FIG. 4B shows an example resource permission map 410 that assigns different user terminals (labeled UT A, UT B, UT C, and UT D) to different return link channels, which correspond to the return link channels of the RCG 400 of FIG. 3A (e.g., RCG channel id4 in resource permission map 410 corresponds to channel id4 in RCG 400). The horizontal axis represents time, and allocation blocks 412 represent the respective transmission permission periods. If there is no resource allocation, the allocation block is labeled "GAP." In resource permission map 410, channels id8 and id9 are allocated during the period covered by resource permission map 410, and RCG channel id10 is unused because channels id8 and id9 overlap with channel id10 in RCG 400. This may represent a situation where a high-capacity dedicated terminal is not requesting or has not been assigned transmission resources. The resource permission map described herein is similar to the UL-MAP message used in the IEEE 802.16 set of standards (e.g., Worldwide Interoperability for Microwave Access, or WiMAX) used to allocate access to uplink (or downlink) channels. While the resource permission map described herein is simplified to illustrate certain elements of the disclosed technology, it should be understood that it also includes other information that may be advantageous or necessary for allocating transmission resources. For example, the disclosed resource permission map may be configured to conform to the WiMAX set of standards for UL-MAP. Furthermore, it should be understood that the described resource permission map specifies a subset of channels, but also includes additional channels where appropriate.

[0065] 4C shows another example resource grant map 420 that allocates return link channel id10 to a fifth user terminal (UT E) for a portion of the time period covered by resource grant map 420. This may represent a situation in which a high-capacity dedicated terminal requests and is allocated transmission resources. In resource grant map 420, RCG channel id10 is not used in the first period because channels id8 and id9 are allocated in the first period, and channels id8 and id9 are not used in the second period because channel id10 is allocated in the second period.

[0066] 4B and 4C illustrate the performance benefits provided by the overlapping channelization technique disclosed herein. Here, a 160 Mcps channel (channel id 10) is selected for a high-data-rate user terminal (UT) and is used only when the UT has return link traffic. Otherwise, the overlapping 80 Mcps channel can be used for user terminals with compatible transmission rates. Because the disclosed RCG configurations enable overlapping channelization, there is no delay in switching between different RCG configurations.

[0067] 5A and 5B illustrate examples of resource permission maps 510, 520 that allocate resource permission by dividing resource permission within a time slot (FIG. 5A) or by allocating resource permission to a time slot (FIG. 5B). The RCG channelization corresponds to the RCG 400 described herein with reference to FIG. 4A. FIG. 5A illustrates intra-slot allocation within resource permission map 510. In resource permission map 510, allocations are divided within a time slot, allowing both an 80 Mcps channel and a 160 Mcps channel to transmit bursts in the same time slot. In other words, the transmission permission period can be shorter than the communication system's time slot and can be short enough to allocate multiple non-overlapping transmission permission periods in the same time slot. FIG. 5B illustrates inter-slot allocation within resource permission map 520. In resource permission map 520, two 80 Mcps channels overlap with a 160 Mcps channel, so only the two 80 Mcps channels or the 160 Mcps channel can have bursts in a particular time slot. In other words, the transmission allowance periods can be approximately the same duration as the time slots of the communication system, so that the scheduler cannot assign multiple non-overlapping transmission allowance periods to the same time slot.

[0068] Method for allocating transmission resources with overlapping channelization - Patents.com 6 illustrates a flowchart of an example method 600 of communicating in a communication system supporting return channel groups with overlapping channelization. Method 600 may be performed by any of the schedulers described herein with reference to FIGS. 1A-2C and 7. For ease of explanation, method 600 is described as being performed by a scheduler. This should not be understood to limit the scope of the disclosure. Rather, any step or portion of method 600 may be performed by any component or combination of components of the communication systems described herein.

[0069] In block 605, a scheduler receives requests for return link bandwidth from multiple user terminals. In block 610, the scheduler assigns a return link channel to each requesting user terminal based at least in part on the transmission characteristics of the corresponding user terminal. The return link channel is selected from multiple return link channels grouped into a return channel group. Each return link channel covers a corresponding frequency band. The scheduler also assigns a transmission permission period to each requesting user terminal. The multiple return link channels in the return channel group each have different transmission characteristics, and at least one return link channel has a frequency band that at least partially overlaps the frequency band of another return link channel. In some embodiments, all possible return link channels of the communication system are included in the return channel group.

[0070] In block 610, the scheduler determines whether the resource allocations assigned in block 605 overlap. To do so, the scheduler determines whether the frequency bands of any of the assigned return link channels at least partially overlap with the frequency bands of any of the other assigned return link channels and whether any of the transmission allowance periods at least partially overlap with other transmission allowance periods. If the scheduler determines that there are no overlapping allocations, the scheduler communicates the assigned return link channels and associated transmission allowance periods to the corresponding user terminal in block 620. In some embodiments, the scheduler is configured to mark the resource grant as obtained at the time the resource grant is assigned to avoid allocating an overlapping resource grant to another user terminal.

[0071] If the scheduler determines that an assigned resource grant has a frequency band and transmission allowance period that overlaps with another assigned resource grant, the scheduler changes the return link channel and / or transmission allowance period for one of the overlapping assignments in block 625. The scheduler then returns to block 615 to check whether there are any more overlapping assignments. This cycle continues until there are no more overlapping assignments.

[0072] In some embodiments, the scheduler is further configured to periodically transmit, to the plurality of user terminals, an RCG descriptor message including an update of the return channel group, wherein the RCG descriptor message can be configured to add return link channels to the return channel group, adjust center frequencies of the return link channels in the return channel group, and adjust bandwidths of the return link channels in the return channel group.

[0073] In some embodiments, return link channels are assigned based at least in part on the capabilities (e.g., bandwidth, power, etc.) of the requesting user terminal. For example, the scheduler may assign a return link channel to a user terminal if the bandwidth of the return link channel is equal to or greater than the transmission rate of the corresponding user terminal. User terminal capabilities may be affected by hardware components such as filters and amplifiers that affect transmission characteristics such as power and bandwidth.

[0074] In some embodiments, channel conditions in a communication system cause degraded transmission characteristics of one or more of a plurality of user terminals. In such a situation, the scheduler can assign a return link channel based at least in part on the degraded transmission characteristics. The degraded transmission characteristics may include the transmission rate or duty cycle of the user terminal.

[0075] Scheduler Example 7 shows a block diagram of an example scheduler 770 configured to allocate resource grants to multiple user terminals using return channel groups (RCGs) with overlapping channelization. The scheduler is similar to scheduler 170 described herein with reference to FIGS. 1A-2C and may be implemented in any of the communication systems described herein. Scheduler 770 may employ any of the methods described herein for allocating resource grants using RCGs with overlapping channelization, such as example method 600 described herein with reference to FIG. 6.

[0076] The scheduler 770 may include hardware, software, and / or firmware components for allocating resource grants. The scheduler 770 includes a data store 771, one or more processors 773, one or more network interfaces 775, a return link module 772, a schedule conflict module 774, and a forward link module 776. The components of the scheduler 770 may communicate with each other, with external systems, and with other components of the network using a communication bus 779. The scheduler 770 may be implemented using one or more computing devices. For example, the scheduler 770 may be implemented using a single computing device, multiple computing devices, a distributed computing environment, or may be located in a virtual device residing in a public or private computing cloud. In a distributed computing environment, one or more computing devices may be configured to provide the modules 772, 774, and 776 to provide the described functionality.

[0077] The scheduler 770 includes a return link module 772 that assigns return link channels and transmission grant periods to user terminals requesting return link bandwidth. The return link module 772 can be configured to determine a suitable return link channel for a user terminal from a return channel group that includes multiple return link channels with overlapping frequency ranges. The suitability of the return link channel can be based, at least in part, on transmission characteristics, such as the transmission rate, of the user terminal.

[0078] The scheduler 770 includes a schedule conflict module 774 that analyzes assignments to determine whether the assignments conflict with each other. A schedule conflict is an assignment where the frequency band of a first return link channel at least partially overlaps with the frequency band of a second return link channel and where the first and second return link channels are assigned during a period of time where they at least partially overlap. The schedule conflict module 774 is configured to resolve the conflict by modifying one or more assignments using the return link module 772, and may repeat this process until the determined schedule is free of conflicts (e.g., overlapping assignments, etc.).

[0079] The scheduler 770 includes a forward link module 776 for assigning forward link channels to components requesting forward link bandwidth and transmitting grant periods. The forward link module 776 can be configured to determine a suitable forward link channel from a channel group including multiple forward link channels with overlapping frequency ranges. The suitability of the forward link channel can be based, at least in part, on transmission characteristics, such as transmission rates, of the components or user terminals.

[0080] Scheduler 770 includes one or more processors 773 configured to control the operation of modules 772, 774, 776 and data store 771. The one or more processors 773 implement and use software modules, hardware components, and / or firmware elements configured to allocate resource grants using RCGs with overlapping channelization. The one or more processors 773 may include any suitable computer processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), or other suitable microprocessor. The one or more processors 773 may include other computing components configured to interface with the various modules and data store of scheduler 770.

[0081] The scheduler 770 includes a data store 771 configured to store configuration data, analysis parameters, control commands, databases, algorithms, executable instructions (e.g., instructions for one or more processors 773), etc. The data store 771 may be any suitable data storage device or combination of devices including, for example, but not limited to, random access memory, read-only memory, solid state disks, hard drives, flash drives, bubble memory, etc.

[0082] Additional Embodiments and Terminology As used herein, the term "user terminal" may refer to any suitable user equipment that enables communication over the disclosed communication system. Thus, a user terminal may include user equipment or customer premises equipment. As used herein, the terms "resource grant," "bandwidth grant," and / or "return link grant" refer to the allocation of transmission resources over a communication system, where resources may include time periods and frequency channels. Similarly, as used herein, resource requests, bandwidth requests, and return link requests refer to requests for transmission resources over a communication system.

[0083] As used herein, the term "transmission rate" can be used to refer to the rate at which data is transmitted over a network and may also be referred to as bandwidth, symbol rate, chip rate, bit rate, etc. For example, in a direct sequence spread spectrum signal, a "chip" is an encoding element. Mcps is a measure of the rate at which chips can be generated by a circuit. In digital communications, chips may refer to pulses in a direct sequence spread spectrum (DSSS) code, such as the pseudorandom noise (PN) sequence used in direct code division multiple access (CDMA) channel access techniques. In some embodiments, the chip rate and symbol rate are the same and may be used interchangeably herein.

[0084] This disclosure describes various features, none of which alone provide the benefits described herein. It will be understood that the various features described herein can be combined, modified, or omitted as would be apparent to one of ordinary skill in the art. Combinations and subcombinations other than those specifically described herein will be apparent to those of ordinary skill in the art and are intended to form part of this disclosure. Various methods are described herein in terms of steps and / or phases of various flowcharts. It should be understood that in many cases, certain steps and / or phases can be combined such that multiple steps and / or phases shown in the flowcharts can be performed as a single step and / or phase. Also, certain steps and / or phases can be divided into additional subcomponents that are performed separately. In some cases, the order of steps and / or phases can be rearranged, and certain steps and / or phases can be omitted entirely. It should also be understood that the methods described herein are open-ended, meaning that additional steps and / or phases can be performed in addition to those shown and described herein.

[0085] Some aspects of the systems and methods described herein can be advantageously implemented using, for example, computer software, hardware, firmware, or any combination of computer software, hardware, and firmware. Computer software can include computer-executable code stored on a computer-readable medium (e.g., a non-transitory computer-readable medium) that, when executed, performs the functions described herein. In some embodiments, the computer-executable code is executed by one or more general-purpose computer processors. Those skilled in the art will appreciate, in light of this disclosure, that any feature or function that can be implemented using software running on a general-purpose computer can also be implemented using a different combination of hardware, software, or firmware. For example, such modules can be implemented entirely in hardware using a combination of integrated circuits. Alternatively or additionally, such features or functions can be implemented, in whole or in part, using a special-purpose computer designed to perform the specific functions described herein, rather than a general-purpose computer.

[0086] Any single computing device described herein may be replaced by multiple distributed computing devices, in which the functionality of a single computing device is distributed (e.g., over a network) with some functionality being performed on each of the distributed computing devices.

[0087] Some embodiments may be described with reference to equations, algorithms, and / or flowchart diagrams. These methods may be implemented using computer program instructions executable on one or more computers. These methods may also be implemented separately as a computer program product or as a component of a device or system. In this regard, each equation, algorithm, block, or step of the flowcharts, and combinations thereof, may be implemented by hardware, firmware, and / or software including one or more computer program instructions embodied in computer-readable program code logic. It will be understood that such computer program instructions may be loaded into one or more computers, including, but not limited to, general-purpose or special-purpose computers, or other programmable processing devices to generate machines, such that the computer program instructions, executed by the computers or other programmable processing devices, implement the functions specified in the equations, algorithms, and / or flowchart diagrams. It will also be understood that each equation, algorithm, and / or block of the flowchart diagrams, and combinations thereof, may be implemented by a dedicated hardware-based computer system that performs the specified functions or steps, or a combination of dedicated hardware and computer-readable program code logic means.

[0088] Furthermore, computer program instructions, e.g., embodied in computer-readable program code logic, can be stored in a computer-readable memory (e.g., a non-transitory computer-readable medium) and direct one or more computers or other programmable processing devices to function in a particular manner, such that the instructions stored in the computer-readable memory perform the functions specified in the blocks of the flowcharts. The computer program instructions are loaded into one or more computers or other programmable computing devices and executed on the one or more computers or other programmable computing devices to produce a computer-implemented process, where the instructions executing on the computers or other programmable processing devices provide steps for performing the functions specified in the equations, algorithms, and / or blocks of the flowcharts.

[0089] Some or all of the methods and tasks described herein are performed by a computer system and may be fully automated. The computer system may, in some cases, include multiple separate computers or computing devices (e.g., physical servers, workstations, storage arrays, etc.) that communicate and interoperate over a network to perform the described functions. Each such computing device typically includes a processor (or multiple processors) that executes program instructions or modules stored in memory or other non-transitory computer-readable storage media or devices. While various functions disclosed herein are embodied in such program instructions, some or all of the disclosed functions may also be implemented in application-specific circuitry (e.g., ASICs or FPGAs) of the computer system. When a computer system includes multiple computing devices, these devices may, but are not necessarily, co-located. The results of the disclosed methods and tasks may be persistently stored by transforming physical storage devices, such as solid-state memory chips and / or magnetic disks, into different states.

[0090] Unless the context clearly dictates otherwise, throughout the description and claims, words such as "comprises," "comprising," and the like are intended to be interpreted in an inclusive sense, rather than an exclusive or exhaustive sense, i.e., "including, but not limited to." The word "coupled," as generally used herein, refers to two or more elements connected directly or via one or more intermediate elements. Furthermore, words such as "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to particular portions of this application. Where the context permits, words using the singular or plural in the above "Detailed Description" can also include the plural or singular, respectively. With respect to a list of two or more items, the word "or" covers all of the following interpretations of that word: any one of the listed items, all items within the listed items, and any combination of the listed items. The word "exemplary" is used herein only to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0091] The present disclosure is not intended to be limited to the implementations shown herein. Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of the present disclosure. The teachings of the present disclosure provided herein may be applied to other methods and systems and are not limited to the methods and systems described above; elements and operations of the various embodiments described above may be combined to provide further embodiments. Thus, the novel methods and systems described herein may be embodied in a variety of other forms, and various omissions, substitutions, and changes in the form of the methods and systems described herein may be made without departing from the spirit of the present disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as fall within the scope and spirit of the present disclosure.

Claims

1. 1. A method of communicating in a communication system, the method comprising: receiving a request for return link bandwidth from a first user terminal and a second user terminal; assigning a first return link channel to the first user terminal based at least in part on transmission characteristics of the first user terminal, the first return link channel being selected from a plurality of return link channels grouped into a return channel group, the first return link channel including a first frequency band; Allocating a first transmission permitted period to the first user terminal; assigning a second return link channel to the second user terminal based at least in part on transmission characteristics of the second user terminal, the second return link channel being selected from the plurality of return link channels in the return channel group, the second return link channel including a second frequency band; Allocating a second transmission permitted period to the second user terminal; communicating the first return link channel, the first permitted transmission period, the second return link channel, and the second permitted transmission period to the corresponding user terminal; Including, The method, wherein the plurality of return link channels in the return channel group each have different transmission characteristics, wherein at least one return link channel has a frequency band that at least partially overlaps with a frequency band of another return link channel.

2. The method of claim 1 , wherein the first user terminal has a different transmission rate than the second user terminal.

3. determining whether the first frequency band at least partially overlaps with the second frequency band; determining whether the first transmission allowed period at least partially overlaps with the second transmission allowed period; The method further comprises:

4. 4. The method of claim 3, further comprising: in response to determining that the first frequency band at least partially overlaps with the second frequency band and the first permitted transmission period at least partially overlaps with the second permitted transmission period, assigning a third return link channel to the first user terminal, the third return link channel having a third frequency band that does not overlap with the second frequency band.

5. 5. The method of claim 3, further comprising: in response to determining that the first frequency band at least partially overlaps with the second frequency band and the first transmission allowed period at least partially overlaps with the second transmission allowed period, assigning a third transmission allowed period to the first user terminal, wherein the third transmission allowed period does not overlap with the second transmission allowed period.

6. 5. The method of claim 3 or 4, wherein communicating the assigned return link channel and transmission allowed period to the first and second user terminals is responsive to determining that the first frequency band does not overlap with the second frequency band or that the first transmission allowed period does not overlap with the second transmission allowed period.

7. The method of claim 1 , wherein the return channel group is hard-coded in the first user terminal and the second user terminal.

8. 8. The method of claim 1, wherein all possible return link channels of the communication system are included in the return channel group.

9. The method of claim 1 , wherein each return link channel in the return channel group has a common center frequency.

10. 10. The method of claim 1, wherein each return link channel in the return channel group has a common lower edge frequency.

11. 11. The method of claim 1, further comprising periodically transmitting a return channel group descriptor message to the first user terminal and the second user terminal, the return channel group descriptor message including updates to the return channel group.

12. 12. The method of claim 11, wherein the return channel group descriptor message adds a return link channel to the return channel group, adjusts a center frequency of a return link channel in the return channel group, or adjusts a bandwidth of a return link channel in the return channel group.

13. 12. The method of claim 1, wherein the first return link channel has a bandwidth equal to or greater than a transmission rate of the first user terminal, and the second return link channel has a bandwidth equal to or greater than a transmission rate of the second user terminal.

14. 14. The method of claim 1, wherein channel conditions of the communication system degrade transmission characteristics of the first user terminal, and the first return link channel is assigned to the first user terminal based at least in part on the degraded transmission characteristics.

15. 1. A communication system for providing communications over a network, the system comprising: a first user terminal having a first maximum bandwidth, the first user terminal configured to store a return channel group including a plurality of return link channels; a second user terminal having a second maximum bandwidth, the second user terminal configured to store the return channel group; a gateway configured to communicate with the first user terminal and the second user terminal via the network, the gateway comprising: storing the return channel group; assigning a first return link channel from the return channel group to the first user terminal, the first return link channel including a first frequency band based at least in part on the first maximum bandwidth; assigning a first transmission permitted period to the first user terminal; assigning a second return link channel from the return channel group to the second user terminal, the second return link channel including a second frequency band based at least in part on the second maximum bandwidth; Allocating a second transmission permitted period to the second user terminal; a gateway configured to communicate the first return link channel, the first permitted transmission period, the second return link channel, and the second permitted transmission period to the corresponding user terminal; Equipped with The plurality of return link channels in the return channel group each have different transmission characteristics, wherein at least one return link channel has a frequency band that at least partially overlaps with a frequency band of another return link channel.

16. 16. The communication system of claim 15, wherein the network includes a satellite network comprising at least one low earth orbit satellite.

17. 17. A communication system according to claim 15 or 16, wherein the network comprises a satellite network comprising at least one medium earth orbit satellite.

18. 18. A communications system according to any one of claims 15 to 17, wherein the network comprises a satellite network comprising at least one geostationary orbiting satellite.

19. 19. A communication system according to any one of claims 15 to 18, wherein the network comprises a terrestrial network.

20. 20. The communication system of claim 15, wherein the network comprises a cellular network.

21. 21. A communication system according to any one of claims 15 to 20, wherein the first maximum bandwidth is different from the second maximum bandwidth.

22. 22. A communications system according to any one of claims 15 to 21, wherein the duty cycle of the first user terminal is different from the duty cycle of the second user terminal.

23. 23. The communications system of claim 15, wherein the first return link channel is assigned based at least in part on channel conditions that reduce the duty cycle of the first user terminal.

24. 24. The communication system of claim 15, wherein the first return link channel is assigned based at least in part on channel conditions that reduce the first maximum bandwidth.

25. 1. A scheduler in a communication system, the scheduler comprising: a network interface configured to communicate with a first user terminal and a second user terminal via the communication system; a data store configured to store computer-executable instructions for generating a return link schedule that allocates return link bandwidth to user terminals in response to requests for return link bandwidth from the user terminals, and to store a return channel group including a plurality of return link channels; a processor configured to execute the computer-executable instructions, the processor executing the computer-executable instructions to: assigning a first return link channel from the return channel group to the first user terminal, the first return link channel including a first frequency band; assigning a first transmission permitted period to the first user terminal; assigning a second return link channel including a second frequency band from the return channel group to the second user terminal; Allocating a second transmission permitted period to the second user terminal; a processor that communicates the first return link channel, the first permitted transmission period, the second return link channel, and the second permitted transmission period to the corresponding user terminal; Equipped with The plurality of return link channels in the return channel group each have different transmission characteristics, and in the transmission characteristics, at least one return link channel has a frequency band that at least partially overlaps with a frequency band of another return link channel.

26. The processor: determining whether the first frequency band at least partially overlaps with the second frequency band; determining whether the first transmission allowed period at least partially overlaps with the second transmission allowed period; 26. The scheduler of claim 25, further configured to:

27. 27. The scheduler of claim 26, wherein in response to determining that the first frequency band at least partially overlaps with the second frequency band and the first transmission allowed period at least partially overlaps with the second transmission allowed period, the processor is further configured to assign a third return link channel to the first user terminal, the third return link channel having a third frequency band that does not overlap with the second frequency band.

28. 28. The scheduler of claim 26 or 27, wherein in response to determining that the first frequency band at least partially overlaps with the second frequency band and the first transmission allowed period at least partially overlaps with the second transmission allowed period, the processor is further configured to assign a third transmission allowed period to the first user terminal, the third transmission allowed period not overlapping with the second transmission allowed period.

29. 29. The scheduler of claim 26, wherein the processor is configured to communicate assigned return link channels and transmission allowed periods to the first and second user terminals in response to determining that the first frequency band does not overlap with the second frequency band or that the first transmission allowed period does not overlap with the second transmission allowed period.

30. 30. A scheduler according to any one of claims 25 to 29, wherein all possible return link channels of the communication system are included in the return channel group.

31. 31. The scheduler of claim 25, wherein the processor is further configured to periodically send a return channel group descriptor message to the first user terminal and the second user terminal, the return channel group descriptor message including updates to the return channel group.

32. 32. The scheduler of claim 31 , wherein the return channel group descriptor message adds a return link channel to the return channel group, adjusts a center frequency of a return link channel in the return channel group, or adjusts a bandwidth of a return link channel in the return channel group.

33. 33. The scheduler of claim 25, wherein the return channel group is the first return channel group, and the processor is further configured to assign a first return link channel from a second return channel group to a third user terminal, the second return channel group having a different channelization scheme than the first return channel group.

34. 34. The scheduler of claim 33, wherein the different channelization scheme of the second return channel group includes a plurality of return link channels that differ from the plurality of return link channels in the first return channel group.

35. 35. The scheduler of claim 33 or 34, wherein the processor is further configured to assign one or more of the plurality of return link channels from the first return channel group to a user terminal communicating via a first beam in the communication system, and to assign one or more of the plurality of return link channels from the second return channel group to a user terminal communicating via a second beam in the communication system.

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