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EP-4476983-B1 - USING TIME DIVISION DUPLEXING SYSTEMS IN FREQUENCY DIVISION DUPLEXING NETWORKS

EP4476983B1EP 4476983 B1EP4476983 B1EP 4476983B1EP-4476983-B1

Inventors

  • TSATSANIS, MICHAIL K.
  • CHAKRABORTY, KAUSHIK
  • BUER, KENNETH V.

Dates

Publication Date
20260513
Application Date
20230214

Claims (13)

  1. A method for scheduling time slots (501-508) in a frame for a gateway terminal (150) and a plurality of user equipment, UE, (110a, 110b, 210a, 210b, 310a, 310b, 410) in a communications system (100, 200, 300, 400), the method comprising: determining a propagation delay between the gateway terminal (150) and each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410); determining, for each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410), one or more conflicting time slots (512, 514, 515, 517) at the UE based on the propagation delay between the gateway terminal (150) and the UE, a conflicting time slot being a time slot in which the UE is scheduled to simultaneously transmit and receive; populating a gateway schedule (491) subject to a constraint to avoid conflicting time slots at each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410) by: generating a plurality of potential gateway schedules (691a) that avoid conflicting time slots at each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410) using a variety of algorithms to populate timeslots; and selecting as the gateway schedule (691c) a potential gateway schedule from the plurality of potential gateway schedules (691a) that improves network utilization relative to unselected potential gateway schedules of the plurality of potential gateway schedules; and communicating a schedule that corresponds to the gateway schedule (691c) to each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410).
  2. The method of claim 1, wherein the schedule that corresponds to the gateway schedule (691c) for a particular UE includes a schedule with downlink time slots delayed in time relative to the gateway schedule (691c), the delay in time equal to the propagation time associated with the particular UE, and with uplink time slots advanced in time relative to the gateway schedule (691c), the advance in time equal to the propagation time associated with the particular UE.
  3. The method of claim 1, wherein populating the gateway schedule (491) includes, for each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410), allocating a plurality of downlink time slots.
  4. The method of claim 3, wherein populating the gateway schedule (491) further includes, for each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410), identifying one or more uplink slots that violate the constraint to avoid conflicting time slots due at least in part to the one or more uplink slots overlapping in time with one or more of the plurality of downlink time slots.
  5. The method of claim 1, wherein populating the gateway schedule (491) includes, for each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410), allocating a plurality of uplink time slots.
  6. The method of claim 5, wherein populating the gateway schedule (491) further includes, for each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410), identifying one or more downlink slots that violate the constraint to avoid conflicting time slots due at least in part to the one or more downlink slots overlapping in time with one or more of the plurality of uplink time slots.
  7. The method of claim 1, wherein the propagation delay of a particular UE changes.
  8. The method of claim 7, wherein the gateway schedule (691c) is updated responsive to a change in the propagation delay of the particular UE.
  9. The method of claim 7, wherein the propagation delay of the particular UE varies over time.
  10. A scheduler (170, 970) in a communications system (100, 200, 300, 400) that includes a gateway terminal (150) and a plurality of user equipment, UE, (110a, 110b, 210a, 210b, 310a, 310b, 410), the scheduler (170, 970) comprising: a data store (971) configured to store computer executable instructions for scheduling downlink and uplink time slots of a frame in the communications system (100, 200, 300, 400); and a processor (973) in communication with the data store (971), the processor (973) configured to execute the computer executable instructions to perform the following: determine a propagation delay between the gateway terminal (150) and each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410); determine, for each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410), one or more conflicting time slots (512, 514, 515, 517) at the UE based on the propagation delay between the gateway terminal (150) and the UE, a conflicting time slot being a time slot in which the UE is scheduled to simultaneously transmit and receive; populate a gateway schedule (491) subject to a constraint to avoid conflicting time slots at each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410) by: generate a plurality of potential gateway schedules (691a) that avoid conflicting time slots at each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410) using a variety of algorithms to populate timeslots; and select as the gateway schedule (691c) a potential gateway schedule from the plurality of potential gateway schedules (691a) that improves network utilization relative to unselected potential gateway schedules of the plurality of potential gateway schedules (691a); and communicate a schedule that corresponds to the gateway schedule (691c) to each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410).
  11. The scheduler (170, 970) of claim 10, wherein the scheduler (170, 970) is incorporated into the gateway terminal (150) of the communications system (100, 200, 300, 400).
  12. The scheduler (170, 970) of claim 10 or 11, wherein the processor (973) is configured to execute the computer executable instructions to perform the method of one or more of claims 2 to 9.
  13. A communications system (100, 200, 300, 400) comprising: a plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410), wherein each of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410) is configured for half duplex operation; a gateway terminal (150), wherein the gateway terminal (150) is configured for full duplex operation, and is configured to communicate with each UE of the plurality of UE (110a, 110b, 210a, 210b, 310a, 310b, 410); and the scheduler (170, 970) of claim 10, 11 or 12, wherein the scheduler (170, 970) is in communication with the gateway terminal (150).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Prov. App. No. 63/310,099 filed February 14, 2022 and entitled "SCHEDULER FOR HALF DUPLEX TERMINAL WITH FULL DUPLEX GATEWAY". BACKGROUND Field The present disclosure generally relates to communications systems that employ both time division duplexing and frequency division duplexing; in particular scheduling time slots in a frame for a gateway terminal and a plurality of user equipment, UE, in a communications system. Description of Related Art Communications systems may employ a variety of technologies to enable communication between devices on a network. Communications systems can use terrestrial network links, non-terrestrial network links, or a combination of these to deliver information between devices. These network links use duplexing to achieve two-way communication over a communications channel. Two forms of duplexing include time division duplexing (TDD) and frequency division duplexing (FDD). In wireless communications systems, time division duplexing uses a single frequency band or channel for both transmit and receive whereas frequency division duplexing uses different frequency bands or channels for transmit and receive. Examples of timing relationship items and turnaround reporting are disclosed in Nokia et al., "Timing relationship enhancements for NB-IoT/eMTC over NTN," 3GPP draft; R1-211277, 3rd generation partnership project (3GPP), vol. RAN WG1, no. e-Meeting; 20211111-20211119 (2021-11-06), XP052074804. SUMMARY The invention is defined in the appended claims. The present disclosure relates to a method for scheduling time slots in a frame for a gateway terminal and a plurality of user equipment (UE) in a communications system; a scheduler; and a communications system. BRIEF DESCRIPTION OF THE DRAWINGS Various embodiments are depicted in the accompanying drawings for illustrative purposes and should in no way be interpreted as limiting the scope of this disclosure. In addition, various features of different disclosed embodiments can be combined to form additional embodiments, which are part of this disclosure. FIG. 1 illustrates a diagram of an example communications system that uses a satellite network to communicatively couple a plurality of user equipment (UE) and a gateway terminal to one another to provide access to a network (such as the Internet).FIG. 2 illustrates an example cellular communications system that includes a base station with a first UE and a second UE both in communication with the base station.FIG. 3 illustrates another example cellular communications system that includes a base station with a first UE and a second UE both in communication with the base station.FIG. 4 illustrates an example satellite communications system that includes a ground station and a UE in communication with each other through a satellite.FIG. 5A illustrates an example of a scheduler determining a conflicting time slot for a gateway schedule and a first UE schedule.FIG. 5B illustrates an example of a scheduler determining a conflicting time slot for a gateway schedule and a second UE schedule.FIG. 5C illustrates an example of a scheduler determining a conflicting time slot for a gateway schedule and a third UE schedule.FIG. 5D illustrates an example of a scheduler determining a conflicting time slot for a gateway schedule and a fourth UE schedule.FIG. 6A illustrates an example of a process for populating a schedule for a gateway terminal and four UEs, wherein each UE has a different propagation delay.FIG. 6B illustrates an example algorithm for determining potentially conflicting time slots and for populating time slots subject to the determined potential conflicts constraints.FIG. 7 illustrates a flow chart of an example method of scheduling time slots in a full duplex network that includes half duplex user equipment.FIG. 8 illustrates a flow chart of another example method of scheduling time slots in a full duplex network that includes half duplex user equipment.FIG. 9 illustrates a block diagram of an example scheduler configured to schedule time slots in a full duplex network that includes half duplex user equipment. DETAILED DESCRIPTION OF SOME EMBODIMENTS The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed subject matter. Overview Certain wireless communications systems, such as cellular networks, can have base stations and user equipment (UE), such as a cellular phone, capable of frequency division duplexing (FDD). This means that different carrier frequencies or channels are used for downlink (DL) and uplink (UL) transmissions. In such systems, it may be desirable to have all UE transmissions aligned when they arrive at the base station. To achieve this alignment, a timing advance is employed for each UE, the timing advance being equal to the propagation delay between the base station and the UE. The timing advance is used to ad