System and method for timing enhancement in store-and-forward mode

Abstract

A system and method for timing enhancement in a store-and-forward mode is presented. A wireless communication node may configure a wait duration indicating the duration until the next satellite service period and a serving duration indicating the duration of the satellite service period. The wireless communication node may transmit the wait duration and serving duration to be used by a wireless communication device during a random access procedure. In one embodiment, the random access procedure comprises a four-step random access procedure, or a two-step or non-collision random access procedure.

Description

[Technical Field]

[0001] The present disclosure relates generally to wireless communications, including, but not limited to, systems and methods for timing enhancement in store-and-forward mode. [Background technology]

[0002] Coverage is a fundamental aspect of cellular network deployment. Mobile operators rely on different types of network nodes to provide blanket coverage in their deployments. As a result, new types of network nodes are considered to increase mobile operators' flexibility for network deployment. For example, certain systems or architectures introduce integrated access and backhaul (IAB), which can be augmented in certain other systems as a new type of network node that does not require wired backhaul. Another type of network node is the RF repeater, which simply amplifies and forwards any signals it receives. RF repeaters have seen widespread deployment in 2G, 3G, and 4G to supplement the coverage provided by typical full-stack cells. Summary of the Invention [Means for solving the problem]

[0003] The exemplary embodiments disclosed herein are directed not only to overcoming problems associated with one or more of the problems presented in the prior art, but also to providing additional features that will become readily apparent from a review of the following detailed description in conjunction with the accompanying drawings. In accordance with various embodiments, exemplary systems, methods, devices, and computer program products are disclosed herein. It will be understood, however, that these embodiments are presented by way of example, and not limitation, and that various modifications to the disclosed embodiments will be apparent to those skilled in the art upon reading this disclosure, while remaining within the scope of the present disclosure.

[0004] At least one aspect is directed to a system, method, apparatus, or computer-readable medium. A wireless communication node (e.g., a base station (BS), which may be part of a regenerative satellite or may be separate from the satellite, for example) may monitor the duration until the next service period of the satellite (e.g., T wait ) and the duration of the satellite service period (e.g., T serve ) and a serving duration indicating the waiting duration and serving duration to be used by the wireless communication device (e.g., user equipment (UE)) during the random access procedure. The wireless communication node may transmit (an indication of) the waiting duration and serving duration to be used by the wireless communication device (e.g., user equipment (UE)) during the random access procedure. In some embodiments, the wireless communication node (e.g., a playback satellite) may transmit the waiting duration and serving duration directly to the UE. In a particular embodiment, the wireless communication node (e.g., a BS) may transmit the waiting duration and serving duration to the UE via a satellite (e.g., a transparent satellite). The random access procedure may comprise a four-step random access procedure, or a two-step or non-collision random access procedure.

[0005] In some embodiments, the wait duration may include at least one of the duration of one orbital cycle of the satellite, the processing duration at the wireless communication node, the round-trip propagation time between the satellite and the wireless communication node, the round-trip propagation time between the satellite and the wireless communication device, a fixed value, or the sum of a fixed value and an offset value.

[0006] In some embodiments, the wireless communication node may transmit the wait duration and the serving duration to the satellite via at least one of Master Information Block (MIB) signaling, System Information Block (SIB) signaling, or Radio Resource Control (RRC) signaling. The satellite may store the wait duration and the serving duration. The satellite may transmit the wait duration and the serving duration to the wireless communication device.

[0007] In some embodiments, the wireless communication device may transmit Msg1 or MsgA to the satellite during the first instance of the serving duration at a start time of the first instance of the waiting period (e.g., t1 in FIG. 9 ). The satellite may transmit Msg2 or MsgB to the wireless communication device in response to expiration of the first instance of the waiting period (e.g., t4 in FIG. 9 ). The wireless communication device may receive Msg2 or MsgB from the satellite in a random access response (RAR) window with a delay comprising the sum of the first timing advance (TA1) and the second timing advance (TA2). The wireless communication device may transmit Msg3 during the second instance of the serving duration at a start time of the second instance of the waiting period (e.g., t5 in FIG. 9 ), with a timing advance comprising the sum of TA1 and TA2. The wireless communication device may monitor to receive Msg4 in a delayed collision resolution window that includes the sum of the third timing advance (TA3) and the fourth timing advance (TA4) after expiration of the second instance of the waiting period.

[0008] In some embodiments, the wireless communication device may determine to transmit Msg1, Msg3, or MsgA if (e.g., under the conditions) at least one of: the calculated elevation angle is greater than an elevation angle threshold; the measured Reference Signal Received Power (RSRP) is greater than an RSRP threshold; the calculated distance is less than a distance threshold between the wireless communication device and the satellite; or the remaining portion of the serving duration calculated by the wireless communication device is greater than the sum of the scheduled duration (e.g., K, the scheduled duration of the DCI scheduled Msg3) and the round-trip propagation time between the satellite and the wireless communication device.

[0009] In some embodiments, TA1 may be a propagation delay calculated by the wireless communication device at a start time of the first instance of the waiting period (e.g., t1 in FIG. 9 ). TA2 may be a propagation delay between the wireless communication device and the satellite calculated when the satellite transmits Msg2 or MsgB to the wireless communication device (e.g., t4 in FIG. 9 ). TA3 may be a propagation delay between the wireless communication device and the satellite calculated when the wireless communication device transmits Msg3 (e.g., t5 in FIG. 9 ). TA4 may be a propagation delay between the wireless communication device and the satellite calculated when the wireless communication device transmits Msg4 (e.g., t8 in FIG. 9 ).

[0010] In some embodiments, if Msg2, Msg4, or MsgB is not received (e.g., is not successfully received) by the wireless communication device in response to expiration of the waiting period, the wireless communication device may retransmit Msg1, Msg3, or MsgA to the satellite at the start time of another instance of the waiting period after a defined offset time (e.g., ΔT, mapped to a higher uplink (UL) availability range).

[0011] In some embodiments, a wireless communication node on a satellite may transmit a waiting duration and a serving duration to a wireless communication device. The wireless communication device may transmit Msg1 or MsgA to the satellite during a first instance of the serving duration at a start time of a first instance of the waiting period (e.g., t1 in FIG. 13 ). The satellite may transmit Msg2 or MsgB to the wireless communication device (e.g., t2 in FIG. 13 ). In response to expiration of the first instance of the waiting period, the wireless communication device may receive Msg2 from the satellite in a random access response (RAR) window with a delay comprising two timing advances (TA). The wireless communication device may transmit Msg3 during a second instance of the serving duration at a start time of a second instance of the waiting period (e.g., t3 in FIG. 13 ). The wireless communication device may monitor to receive Msg4 after expiration of the second instance of the waiting period in a collision resolution window after a delay comprising two TAs. TA may be a propagation delay between the wireless communication device and the satellite. If Msg2, Msg4, or MsgB is not received by the wireless communication device in response to expiration of the first or second instance of the waiting period, the wireless communication device may retransmit Msg1, Msg3, or MsgA to the satellite at the start time of another instance of the waiting period after a defined offset time (e.g., ΔT, mapped to a higher uplink (UL) availability range).

[0012] In some embodiments, a wireless communication node (e.g., gNB-CU) may transmit (an indication of) a waiting duration and a serving duration to a satellite. The satellite may store the waiting duration and the serving duration. The satellite may transmit the waiting duration and the serving duration to a wireless communication device. The wireless communication device may transmit Msg1 or MsgA to the satellite at a start time of a first instance of the waiting period (e.g., t1 in FIG. 17 ) during a first instance of the serving duration. The satellite may transmit Msg2 or MsgB to the wireless communication device in response to expiration of the first instance of the waiting period (e.g., t3 in FIG. 17 ). The wireless communication device may receive Msg2 or MsgB and first radio resource control (RRC) information from the satellite within / after a random access response (RAR) window with / a delay comprising the sum of the first timing advance (TA1) and the second timing advance (TA2). The wireless communication device may transmit Msg3 during the second instance of the serving duration at a start time of the second instance of the waiting period (e.g., t4 in FIG. 17) with / after a timing advance comprising the sum of TA1 and TA2. The wireless communication device may monitor to receive Msg4 and the second RRC information within / in a delayed collision resolution window comprising the sum of a third timing advance (TA3) and a fourth timing advance (TA4) after expiration of the second instance of the waiting period.

[0013] In some embodiments, TA1 may be a propagation delay calculated by the wireless communication device at a start time of the first instance of the waiting period (e.g., t1 in FIG. 17 ). TA2 may be a propagation delay between the wireless communication device and the satellite calculated / determined (e.g., using a GNSS module of the wireless communication device) when the satellite transmits Msg2 or MsgB to the wireless communication device (e.g., t3 in FIG. 17 ). TA3 may be a propagation delay between the wireless communication device and the satellite calculated / determined (e.g., using a GNSS module of the wireless communication device) when the wireless communication device transmits Msg3 (e.g., t4 in FIG. 17 ). TA4 may be a propagation delay between the wireless communication device and the satellite calculated when the wireless communication device receives Msg4. If Msg2, Msg4, or MsgB is not received by the wireless communication device in response to expiration of the waiting period, the wireless communication device may retransmit Msg1, Msg3, or MsgA to the satellite (e.g., attempt to transmit another Msg1, Msg3, or MsgB) at the start time of another instance of the waiting period after a defined offset time (mapped to higher uplink (UL) availability, ΔT). The wireless communication device may receive Msg2 or MsgB from the satellite in an RAR window extended to incorporate a common timing advance (e.g., configured / determined by the wireless communication node) for multiple wireless communication devices or a maximum round-trip propagation delay between the wireless communication device and the satellite. The wireless communication device may monitor to receive Msg4 in a collision resolution window extended / modified to incorporate a common timing advance or a maximum round-trip propagation delay between the wireless communication device and the satellite.

[0014] In some embodiments, the wireless communication device (e.g., UE) indicates the duration until the next service period of the satellite to be used during the random access procedure (e.g., T wait) waiting duration, and the duration of the satellite service period (e.g., T serve ) serving duration. The waiting duration and serving duration may be configured by a wireless communication node (e.g., a BS, which may be part of a playback satellite, for example). [Brief explanation of the drawings]

[0015] Various exemplary embodiments of the present solution are described in detail below with reference to the following figures or drawings. The drawings are provided for illustrative purposes only and merely illustrate exemplary embodiments of the present solution to facilitate the reader's understanding of the present solution. Therefore, the drawings should not be considered as limiting the breadth, scope, or applicability of the present solution. It should be noted that for clarity and ease of illustration, the drawings are not necessarily drawn to scale.

[0016] [Figure 1] FIG. 1 illustrates an example cellular communication network in which the techniques disclosed herein may be implemented according to some embodiments of the present disclosure.

[0017] [Figure 2] FIG. 2 illustrates an example block diagram of an exemplary base station and user equipment device in accordance with some embodiments of the present disclosure.

[0018] [Figure 3] FIG. 3 illustrates a schematic diagram of operation in a store-and-forward mode in a non-terrestrial network (NTN) according to some embodiments of the present disclosure.

[0019] [Figure 4] FIG. 4 illustrates a schematic diagram of a modified store-and-forward mode of operation between satellites according to some embodiments of the present disclosure.

[0020] [Figure 5]FIG. 5 illustrates a schematic diagram of a transparent satellite in a non-terrestrial network (NTN) according to some embodiments of the present disclosure.

[0021] [Figure 6] FIG. 6 illustrates a schematic diagram of a regenerative satellite in a non-terrestrial network (NTN) according to some embodiments of the present disclosure.

[0022] [Figure 7] FIG. 7 shows a schematic diagram of a regenerative satellite with a separate gNB-CU in a non-terrestrial network (NTN) according to some embodiments of the present disclosure.

[0023] [Figure 8] FIG. 8 illustrates a flow diagram of an example application of Twait and Tserve for timing of a random access channel (RACH) according to some embodiments of the present disclosure.

[0024] [Figure 9] FIG. 9 illustrates a sequence diagram for timing enhancement in a four-step RACH for a transparent satellite according to some embodiments of the present disclosure.

[0025] [Figure 10] FIG. 10 illustrates a sequence diagram for timing enhancement during failure of a four-step RACH for a transparent satellite according to some embodiments of the present disclosure.

[0026] [Figure 11] FIG. 11 illustrates a sequence diagram for timing enhancement in a two-step RACH / collision-free (CF) RACH for a transparent satellite according to some embodiments of the present disclosure.

[0027] [Figure 12] FIG. 12 illustrates a sequence diagram for timing enhancement upon failure of a two-step RACH / CF RACH for a transparent satellite according to some embodiments of the present disclosure.

[0028] [Figure 13] FIG. 13 illustrates a sequence diagram for timing enhancement in a four-step RACH for a regenerative satellite according to some embodiments of the present disclosure.

[0029] [Figure 14] FIG. 14 illustrates a sequence diagram for timing enhancement upon failure of a four-step RACH for a regenerative satellite according to some embodiments of the present disclosure.

[0030] [Figure 15] FIG. 15 illustrates a sequence diagram for timing enhancement in a two-step RACH / CF RACH for a regenerative satellite according to some embodiments of the present disclosure.

[0031] [Figure 16] FIG. 16 illustrates a sequence diagram for timing enhancement upon failure of a two-step RACH / CF RACH for a regenerative satellite according to some embodiments of the present disclosure.

[0032] [Figure 17] FIG. 17 illustrates a sequence diagram for timing enhancement in a four-step RACH for a regenerative satellite with gNB DU / CU splitting according to some embodiments of the present disclosure.

[0033] [Figure 18] FIG. 18 illustrates a sequence diagram for timing enhancement in two-step RACH / CF RACH for a regenerative satellite with gNB DU / CU splitting according to some embodiments of the present disclosure.

[0034] [Figure 19] FIG. 19 illustrates a flow diagram of an example method for timing enhancement in store-and-forward mode / operation according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0035] (1. Mobile Communications Technology and Environment) 1 illustrates an example wireless communication network and / or system 100 in which the techniques disclosed herein according to some embodiments of the present disclosure may be implemented. In the following discussion, the wireless communication network 100 may be any wireless network, such as a cellular network or a narrowband Internet of Things (NB-IoT) network, and is referred to herein as “network 100.” Such example network 100 includes a base station 102 (hereinafter “BS 102,” also referred to as a wireless communication node) and a user equipment device 104 (hereinafter “UE 104,” also referred to as a wireless communication device) that can communicate with each other via a communication link 110 (e.g., a wireless communication channel), and a cluster of cells 126, 130, 132, 134, 136, 138, and 140 that overlap a geographic region 101. In FIG. 1, the BS 102 and the UE 104 are contained within the respective geographic boundaries of the cell 126. Each of the other cells 130, 132, 134, 136, 138, and 140 may include at least one base station operating in its assigned bandwidth to provide adequate wireless coverage to intended users.

[0036] For example, the BS 102 may operate with an assigned channel transmission bandwidth to provide adequate coverage to the UE 104. The BS 102 and the UE 104 may communicate via downlink radio frames 118 and uplink radio frames 124, respectively. Each radio frame 118 / 124 may be further divided into subframes 120 / 127, which may include data symbols 122 / 128. In this disclosure, the BS 102 and the UE 104 are generally described herein as non-limiting examples of “communication nodes” capable of implementing the methods disclosed herein. Such communication nodes may be capable of wireless and / or wired communication in accordance with various embodiments of the present solution.

[0037] 2 shows a block diagram of an exemplary wireless communication system 200 for transmitting and receiving wireless communication signals (e.g., OFDM / OFDMA signals) in accordance with some embodiments of the present solution. System 200 may include components and elements configured to support known or conventional operational features that need not be described in detail herein. In one illustrative embodiment, system 200 may be used to communicate (e.g., transmit and receive) data symbols in a wireless communication environment, such as wireless communication environment 100 of FIG. 1, as described above.

[0038] The system 200 generally includes a base station 202 (hereinafter "BS 202") and a user equipment device 204 (hereinafter "UE 204"). The BS 202 includes a BS (base station) transceiver module 210, a BS antenna 212, a BS processor module 214, a BS memory module 216, and a network communication module 218, each of which is coupled and interconnected as needed via a data communication bus 220. The UE 204 includes a UE (user equipment) transceiver module 230, a UE antenna 232, a UE memory module 234, and a UE processor module 236, each of which is coupled and interconnected as needed via a data communication bus 240. The BS 202 communicates with the UE 204 via a communication channel 250, which can be any wireless channel or other medium suitable for the transmission of data as described herein.

[0039] As will be appreciated by those skilled in the art, system 200 may further include any number of modules other than those shown in FIG. 2 . Those skilled in the art will understand that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented in hardware, computer-readable software, firmware, or any practical combination thereof. To clearly illustrate this compatibility and suitability of hardware, firmware, and software, the various illustrative components, blocks, modules, circuits, and steps have been described generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software may depend on the particular application and design constraints imposed on the overall system. Those familiar with the concepts described herein may implement such functionality in a manner suitable for each particular application, but such implementation decisions should not be construed as limiting the scope of the present disclosure.

[0040] According to some embodiments, the UE transceiver 230 may be referred to herein as an “uplink” transceiver 230 including a radio frequency (RF) transmitter and an RF receiver, each with circuitry coupled to an antenna 232. Alternatively, a duplexing switch (not shown) may couple the uplink transmitter or receiver to the uplink antenna in a time-duplexed manner. Similarly, according to some embodiments, the BS transceiver 210 may be referred to herein as a “downlink” transceiver 210 including an RF transmitter and an RF receiver, each with circuitry coupled to an antenna 212. Alternatively, a downlink duplexing switch may couple the downlink transmitter or receiver to the downlink antenna 212 in a time-duplexed manner. The operation of the two transceiver modules 210 and 230 may be coordinated in time such that the downlink transmitter is coupled to the downlink antenna 212 at the same time that the uplink receiver circuitry is coupled to the uplink antenna 232 for receiving transmissions over the wireless transmission link 250. Conversely, the operation of the two transceivers 210 and 230 may be coordinated in time such that the uplink transmitter is coupled to the uplink antenna 232 at the same time that the downlink receiver is coupled to the downlink antenna 212 to receive transmissions over the wireless transmission link 250. In some embodiments, there is strict time synchronization with a minimum guard time between changes in duplex direction.

[0041] The UE transceiver 230 and the base station transceiver 210 are configured to communicate over a wireless data communication link 250 and cooperate with a suitably configured RF antenna arrangement 212 / 232 capable of supporting a particular wireless communication protocol and modulation scheme. In some demonstrative embodiments, the UE transceiver 210 and the base station transceiver 210 are configured to support industry standards such as Long Term Evolution (LTE) and emerging 5G standards. However, it will be understood that the present disclosure is not necessarily limited in application to a particular standard and associated protocol. Rather, the UE transceiver 230 and the base station transceiver 210 may be configured to support alternative or additional wireless data communication protocols, including future standards or variants thereof.

[0042] According to various embodiments, the BS 202 may be, for example, an evolved node B (eNB), a serving eNB, a target eNB, a femto station, or a pico station. In some embodiments, the UE 204 may be embodied in various types of user devices, such as a mobile phone, a smartphone, a personal digital assistant (PDA), a tablet, a laptop computer, a wearable computing device, etc. The processor modules 214 and 236 may be implemented or realized using a general-purpose processor, a content-addressable memory, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. Thus, a processor may be realized as a microprocessor, a controller, a microcontroller, a state machine, etc. A processor may also be implemented as a combination of computing devices, such as a combination of a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

[0043] Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, firmware, a software module executed by processor modules 214 and 236, respectively, or any practical combination thereof. Memory modules 216 and 234 may be realized as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard, memory modules 216 and 234 may be coupled to processor modules 210 and 230, respectively, thereby enabling processor modules 210 and 230 to read information from and write information to memory modules 216 and 234, respectively. Memory modules 216 and 234 may also be integrated into their respective processor modules 210 and 230. In some embodiments, memory modules 216 and 234 may each include a cache memory for storing temporary variables or other intermediate information during execution of instructions executed by processor modules 210 and 230, respectively. Each of the memory modules 216 and 234 may include non-volatile memory for storing instructions executed by the processor modules 210 and 230, respectively.

[0044] The network communications module 218 generally represents the hardware, software, firmware, processing logic, and / or other components of the base station 202 that enable bidirectional communications between the base station transceiver 210 and other network components and communications nodes configured to communicate with the base station 202. For example, the network communications module 218 may be configured to support Internet or WiMAX traffic. In a typical deployment, without limitation, the network communications module 218 provides an 802.3 Ethernet interface to enable the base station transceiver 210 to communicate with conventional Ethernet-based computer networks. In this embodiment, the network communications module 218 may include a physical interface for connecting to a computer network (e.g., a mobile switching center (MSC)). As used herein with respect to a specified operation or function, the terms “configured for,” “configured to,” and conjugations thereof refer to a device, component, circuit, structure, machine, signal, etc. that is physically structured, programmed, formatted, and / or arranged to perform the specified operation or function.

[0045] The Open Systems Interconnection (OSI) model (referred to herein as the "Open Systems Interconnection Model") is a conceptual and logical layout that defines network communications used by open systems (e.g., wireless communication devices, wireless communication nodes) to interconnect and communicate with other systems. The model is decomposed into seven subcomponents or layers, each of which represents a conceptual collection of services provided to the layers above and below it. The OSI model also defines logical networks and effectively describes computer packet transfers by using different layer protocols. The OSI model may be referred to as the seven-layer OSI model or seven-layer model. In some embodiments, the first layer may be the physical layer. In some embodiments, the second layer may be the medium access control (MAC) layer. In some embodiments, the third layer may be the radio link control (RLC) layer. In some embodiments, the fourth layer may be the packet data convergence protocol (PDCP) layer. In some embodiments, the fifth layer may be the radio resource control (RRC) layer. In some embodiments, the sixth layer may be a non-access stratum (NAS) layer or an Internet Protocol (IP) layer, and the seventh layer is another layer.

[0046] Various exemplary embodiments of the present solution are described below with reference to the accompanying drawings to enable those skilled in the art to make and use the solution. As will be apparent to those skilled in the art, after reading this disclosure, various changes or modifications to the examples described herein can be made without departing from the scope of the solution. Thus, the present solution is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the specific order or hierarchy of steps in the methods disclosed herein is merely an example approach. Based on design preferences, the specific order or hierarchy of steps in a disclosed method or process can be rearranged while remaining within the scope of the solution. Thus, those skilled in the art will understand that the methods and techniques disclosed herein present various steps or operations in a sample order, and that the solution is not limited to the specific order or hierarchy presented unless otherwise specified.

[0047] 2. Systems and Methods for Timing Enhancement in Store-and-Forward Mode In a non-terrestrial network (NTN), large delays may be generated due to the long propagation distances involved in information exchange between a user equipment (UE) and a base station (BS). Furthermore, in a store-and-forward mode, larger delays may occur when a satellite travels back (e.g., along an orbital path) to the UE for signaling or information exchange. To address the challenges posed by large delays and achieve uplink synchronization, it may be beneficial to implement timing enhancements (e.g., adjustments) in the random access procedure. Furthermore, it is important to note that timing enhancements in the random access channel (RACH) procedure may vary depending not only on the specific satellite architecture / type, such as a transparent architecture and a regenerative architecture, but also on the type of RACH used in the system. Therefore, this disclosure describes various timing enhancements for the RACH procedure for transparent and regenerative satellites using the store-and-forward mode in an NTN.

[0048] FIG. 3 shows a schematic diagram of operation in a store-and-forward mode in a non-terrestrial network (NTN) according to some embodiments of the present disclosure. The structure of the store-and-forward mode in an NTN is shown in FIG. 3. The link between the UE and the satellite can be a service link. The link between the gateway and the satellite can be a feeder link and can be common to all UEs. During step A, there can be only a service link connected between the UE and the satellite (e.g., the satellite can operate / communicate only on the service link without a feeder link connection / communication). During step B, there can be only a feeder link connected between the gateway and the satellite (e.g., the satellite can simultaneously operate / communicate only on the feeder link without a service link connection / communication). As the satellite moves between step A and step B, signaling / data exchange can be performed using the satellite's ability to perform store-and-forward.

[0049] 4 shows a schematic diagram of a modified operation of an inter-satellite store-and-forward mode according to some embodiments of the present disclosure. As shown in FIG. 4, the modified operation of the inter-satellite store-and-forward mode can be a specific manner in which a connection between a UE and a gateway via an inter-satellite link can be achieved. For example, an inter-satellite link between satellite A and satellite B can be established to maintain a communication connection between the UE and the gateway when the feeder link between satellite A and the gateway is disabled or inoperative.

[0050] FIG. 5 shows a schematic diagram of a transparent satellite in a non-terrestrial network (NTN) according to some embodiments of the present disclosure. FIG. 6 shows a schematic diagram of a regenerative satellite in a non-terrestrial network (NTN) according to some embodiments of the present disclosure. The satellite payload may be divided into a transparent payload and a regenerative payload, as shown in FIGS. 5 and 6. For a transparent satellite, the satellite can be considered an analog radio frequency (RF) repeater, which can realize / perform frequency conversion and RF amplification in the uplink and downlink directions. For a regenerative satellite, base station functions may be on the satellite, which can realize / perform / include not only radio frequency filtering, frequency conversion, and amplification, but also demodulation / decoding, switching and / or routing, and / or coding / modulation. In particular, for a gNB DU / CU split in a regenerative satellite, some higher layer (e.g., radio resource control (RRC)) functions may be divided into a gNB-CU (e.g., separate from the satellite). FIG. 7 shows a schematic diagram of a regenerative satellite based on a gNB-CU or the like in a non-terrestrial network (NTN) according to some embodiments of the present disclosure.

[0051] Based on the above introduction, timing enhancements for the RACH procedure can be performed for different scenarios, taking into account transparent satellite mode and regenerative satellite mode for (e.g., to support / facilitate) store-and-forward operation in the NTN.

[0052] FIG. 8 illustrates a timing diagram for a random access channel (RACH) in accordance with some embodiments of the present disclosure. wait and T serve 1 shows a flow chart of an exemplary application of T wait With respect to the configuration of, the waiting duration may include at least one of (a) a satellite orbit periodicity duration, (b) a processing duration at the gateway, (c) a round-trip propagation delay between the satellite and the gateway, (d) a round-trip propagation delay between the satellite and the UE, or (e) a timing offset.

[0053] Tserve For the configuration of (K), the serving duration can be the maximum duration for which the UE is covered by the satellite (e.g., receiving cellular coverage from it). To determine whether the remaining portion of (or therein) the serving duration is sufficient / available, the determination method can be summarized as determining / detecting the following: (1) the current elevation angle is less than an elevation angle threshold; (2) the Reference Signal Received Power (RSRP) at the current time is greater than an RSRP threshold; (3) the distance at the current time is less than a distance threshold between the UE and the satellite; or (4) (a portion of) the remaining serving duration is greater than the sum of the scheduled duration (e.g., K) and the round-trip propagation time (RTT). Here, the remaining serving duration is expressed as the time from the current Coordinated Universal Time (UTC), T serve The UTC time at which the timer starts, and T serve by (e.g. 、 T serve -(T current,UTC -T startofTimer,UTC ) or by the difference between the serving duration and the current serving duration (e.g., T serve -T current,serve K is the scheduled duration of the DCI scheduled Msg3. RTT is the maximum round trip time between the UE and the satellite.

[0054] For a UE with a Global Navigation Satellite System (GNSS) module, a timing advance (TA) may be calculated according to the UE's location and satellite ephemeris to delay / shift the random access response (RAR) window.

[0055] For a UE without a GNSS module, extending the range of the RAR window with the maximum RTT between the UE and the satellite may cover the exact round trip delay.

[0056] (Implementation Example 1: RACH timing enhancement based on waiting duration and serving duration for satellite transparent mode) Case 1-1: Transparent satellite in store-and-forward mode (e.g., the satellite receives synchronization signal blocks (SSBs), system information blocks (SIBs), and T wait , T serve , and then forwarding to the UE). Figure 9 shows a sequence diagram of timing enhancement (e.g., adjustment) in a four-step RACH for a transparent satellite according to some embodiments of the present disclosure. Figure 10 shows a sequence diagram of timing enhancement upon failure of a four-step RACH for a transparent satellite according to some embodiments of the present disclosure.

[0057] Before the random access procedure, the satellite receives the stored synchronization signal block (SSB), system information (SI), and waiting duration T wait , and serving duration T serve to the UE. The wait duration may be indicated by the following options:

[0058] Option-1: Wait duration T wait , as a constant value of T wait ≧T peiod , which ensures successful transmission and / or processing of Msg1 according to network configuration (e.g., Physical Random Access Channel (PRACH) opportunity, preamble index in Minimum Reference Signal Received Power (RSRP) threshold, elevation angle threshold, and / or distance threshold). The waiting duration may include at least one of a satellite orbit period duration, a processing duration at the gateway, a round propagation delay between the satellite and the gateway, or a round propagation delay between the satellite and the UE.

[0059] Option-2: As an offset and constant value of the wait duration, where T wait =ΔT+T wait,initial Each value of the offset may be mapped to a corresponding RSRP threshold, elevation threshold, and / or distance threshold. For example, the following Table 1 may be constructed: [Table 1]

[0060] At time t1, the UE may transmit Msg1 to the satellite and wait for Msg2 for a waiting duration T wait The UE may calculate and store a first timing advance (TA1) (e.g., a propagation delay between the UE and the satellite).

[0061] At time t2, the satellite may forward the stored Msg1 to the gateway as the satellite passes the gateway (eg, along the satellite's orbital path).

[0062] At time t3, the gateway may send Msg2 to the satellite if Msg1 is correctly decoded at the gateway.

[0063] At time t4, the satellite waits for a waiting period of T wait When the timer expires, the UE may forward the stored Msg2 to the UE. The UE may receive Msg2 at / within a random access response (RAR) window adjusted by the sum of the delay of the first timing advance (TA1) and the second timing advance (TA2). TA1 may be the calculated propagation delay stored by the UE at time t1. TA2 may be the calculated propagation delay between the UE and the satellite at time t4. In another case, as shown in FIG. 10, if Msg2 is not received by the UE, the UE may resume random access after an offset of ΔT, which may be mapped to a higher uplink (UL) availability range. wait For example, random access may be resumed at a higher reference signal received power (RSRP), a higher elevation angle, or a larger time offset delay at a shorter distance according to the mapping table above.

[0064] At time t5, the UE may transmit Msg3 with a timing advance of the sum of TA1+TA2, where TA2 may be the propagation delay between the UE and the satellite. wait When / after the timer expires, the UE may wait for Msg4 within the collision resolution window (e.g., before the collision resolution timer expires) after a delay of the third timing advance and the fourth timing advance (e.g., TA3+TA4). TA3 and TA4 may be the propagation delays between the UE and the satellite calculated when the UE transmits Msg3 and receives Msg4, respectively.

[0065] At time t6, the satellite may forward the stored Msg3 to the gateway, and conflict detection and persistent cell radio network temporary identifier (C-RNTI) assignment may occur.

[0066] At time t7, the network may transmit Msg4 to the satellite when Msg3 is decoded correctly.

[0067] At time t8, the satellite may transmit the stored Msg4 to the UE as the satellite passes over the UE. If Msg4 is successfully decoded, random access may be completed. Otherwise, the UE may transmit the stored Msg4 to the UE at time t8. serve After waiting for a new offset of ΔT within a serving duration of ΔT, the access may resume at a higher UL availability range.

[0068] Case 1-2: For two-step random access or collision-free random access in the transparent satellite mode, the waiting duration T wait and serving duration T serve The application of the following may be feasible / supported. Figure 11 shows a sequence diagram for timing enhancement in a two-step RACH / control function (CF) RACH for a transparent satellite according to some embodiments of the present disclosure. Figure 12 shows a sequence diagram for timing enhancement during a failure of a two-step RACH / CF RACH for a transparent satellite according to some embodiments of the present disclosure.

[0069] Before starting / executing the random access procedure, the satellite must first read the stored synchronization signal block (SSB), system information (SI), and wait duration T wait , and / or serving duration T serve to the UE. The wait duration can be indicated by the following options:

[0070] Option-1: Waiting duration T greater than the period duration of the satellite orbit wait As a constant value of T wait ≧T peiod ,It at least guarantees successful transmission / processing of Msg1 / MsgA with a network configuration at a minimum high ,Reference Signal Received Power (RSRP) threshold, elevation threshold, or distance threshold.

[0071] Option-2: As an offset and constant value of the wait duration, where T wait =ΔT+T wait,initial Different values ​​of the offset may be mapped with corresponding values ​​of the RSRP threshold, the elevation threshold, and / or the distance threshold. The time offset may be less than the serving duration (e.g., ΔT≦T serve ). T wait , T serve、 ΔT, and T wait , initial may be indicated to the UE via SIB signaling. For the mapping relationship, the following Table 2 may be constructed. [Table 2]

[0072] At time t1, the UE may transmit Msg1 / MsgA to the satellite and wait for Msg2 / MsgB for timing duration T wait The UE may start a timer for / . The UE may calculate and store a first timing advance (TA1) (e.g., a propagation delay between the UE and the satellite).

[0073] At time t2, the satellite may forward the stored Msg1 / MsgA to the gateway when the satellite passes over the gateway.

[0074] At time t3, the gateway may transmit Msg2 / MsgB to the satellite if Msg1 / MsgA is decoded correctly.

[0075] At time t4, the satellite waits for a waiting period of T wait When the timer expires, the UE may forward the stored Msg2 / MsgB to the UE. The UE may receive Msg2 in a random access response (RAR) window (shifted / adjusted by the delay) with a delay equal to the sum of the first timing advance (TA1) and the second timing advance (TA2). TA2 may be the calculated propagation delay between the UE and the satellite at time t4. Otherwise, as shown in FIG. 12, if Msg2 / MsgB is not received by the UE, the UE may resume random access with an offset of ΔT mapped to a higher UL availability range. wait For example, random access may be resumed at a higher RSRP, a higher elevation angle, or a larger time offset delay at a shorter distance according to the mapping table above.

[0076] For successful preamble decoding for MsgA, but failure for Msg3, the wait duration may be used for the 4-step RACH fallback procedure.

[0077] (Implementation Example 2: RACH timing enhancement based on waiting duration and serving duration for regenerative satellite with onboard gNB) Case 2-1: For a regenerative satellite with an onboard gNB, timing enhancement of the four-step random access procedure may be performed as follows: Figure 13 shows a sequence diagram for timing enhancement in a four-step RACH of a regenerative satellite (e.g., with a gNB / satellite processing payload) according to some embodiments of the present disclosure. Figure 14 shows a sequence diagram for timing enhancement upon failure of a four-step RACH of a regenerative satellite (e.g., with a gNB / satellite processing payload) according to some embodiments of the present disclosure.

[0078] Before the random access procedure begins, the satellite transmits the synchronization signal block (SSB), system information (SI), and a waiting duration T wait , and serving duration T serve to the UE. The wait duration may be indicated by the following options:

[0079] Option-1: Wait duration T wait As a constant value of T wait ≧T peiod , which ensures successful communication and / or processing of Msg1 with a network configuration at a minimum RSRP threshold, elevation threshold, or distance threshold.

[0080] Option-2: T as an offset and constant value for the wait duration. wait =ΔT+T wait,initial , where the value of the offset may be mapped to respective values ​​of the RSRP threshold, elevation threshold, and / or distance threshold. For example, the following Table 3 may be constructed: [Table 3]

[0081] At time t1, the UE may transmit Msg1 to the satellite and wait for Msg2 in / within the RAR window with a delay of 2*TA (e.g., TA may be the calculated propagation delay between the UE and the satellite).

[0082] At time t2, the UE may receive Msg2 if Msg1 is correctly decoded by the onboard base station. Otherwise, the UE may receive Msg2 according to the above mapping table, based on a time offset (e.g., a higher RSRP, ΔT≦T serve ), a higher elevation angle, or a shorter distance, the random access procedure may be resumed at a higher UL coverage area.

[0083] At time t3, the UE may transmit Msg3 to the satellite and may wait for Msg4 within the collision resolution timer after a delay of 2*TA (e.g., after being adjusted / delayed / shifted by that delay), where TA may be the calculated propagation delay between the UE and the satellite at time t3.

[0084] At time t4, if Msg4 is successfully decoded, the random access can be completed. Otherwise, the UE serve By using a larger offset ΔT within the serving duration of ΔT, random access can resume at a higher UL availability range. serve If T, the UE may resume. wait The random access may be delayed by a configured wait duration of .

[0085] T serve When this timer expires, the UE may discontinue its transmission.

[0086] Case 2-2: Regenerative satellite, gNB processed payload, timing enhancement in two-step random access procedure or collision-free random access procedure, waiting duration T wait and serving duration T serveApplication of the following may also be feasible. Figure 15 shows a sequence diagram for timing enhancement in a two-step RACH / CF RACH for a regenerative satellite (e.g., gNB / satellite processing payload) according to some embodiments of the present disclosure. Figure 16 shows a sequence diagram for timing enhancement upon failure of a two-step RACH / CF RACH of a regenerative satellite gNB processing payload according to some embodiments of the present disclosure.

[0087] Before the random access procedure starts / occurs, the satellite must receive the synchronization signal block (SSB), system information (SI), and waiting duration T wait , and / or serving duration T serve to the UE. The wait duration may be indicated by the following options:

[0088] Option-1: Waiting duration T greater than the period duration of the satellite orbit wait As a constant value of T wait ≧T peiod ,It can guarantee the success of Msg1 / MsgA with network ,configuration at the minimum RSRP threshold, elevation threshold, or distance ,threshold.

[0089] Option-2: T as an offset and constant value for the wait duration. wait =ΔT+T wait,initial , where each value of the offset may be mapped to a respective value of the RSRP threshold, the elevation threshold, and / or the distance threshold. The time offset may be less than the serving duration (e.g., ΔT≦T serve For example, the following Table 4 can be constructed: [Table 4]

[0090] At time t1, the UE may transmit Msg1 / MsgA to the satellite and wait for Msg2 / MsgB in / within the RAR window with a delay of 2*TA, where TA may be the propagation delay between the UE and the satellite.

[0091] At time t2, the UE may receive Msg2 / MsgB if Msg1 / MsgA is correctly decoded by the onboard base station. Otherwise, the UE may receive Msg2 / MsgB according to the above mapping table (ΔT≦T serve If ΔT > T, random access may resume at a higher UL availability range by using a time offset (e.g., a higher RSRP), a higher elevation angle, or a shorter distance. serve If T, the UE may resume. wait The random access may be delayed by a configured wait duration of .

[0092] (Implementation Example 3: RACH timing enhancement based on waiting duration and serving duration for regenerative satellite with onboard gNB-DU) Case 3-1: For regenerative satellite, gNB-DU processing payload, timing enhancement in 4-step random access may be specified. Figure 17 shows a sequence diagram for timing enhancement in 4-step RACH for regenerative satellite with gNB DU / CU split according to some embodiments of the present disclosure. For CU / DU split, the UE uses T wait The following procedure can be modified.

[0093] Before the random access procedure, the satellite receives the stored synchronization signal block (SSB), system information (SI), and waiting duration T wait , and / or serving duration T serve to the UE. The wait duration may be indicated by the following options:

[0094] Option-1: Wait duration T wait As a constant value of T wait ≧T peiod, which can ensure successful communication and / or processing of Msg1 with network configuration (e.g., PRACH opportunity, preamble index) at a minimum RSRP threshold, elevation threshold, or distance threshold. The waiting duration may include at least one of a satellite orbit period duration, a processing duration at the gateway, or a round propagation delay between the satellite and the gateway, or a round propagation delay between the satellite and the UE.

[0095] Option-2: T as an offset and constant value for the wait duration. wait =ΔT+T wait,initial , where the offset may be mapped with an RSRP threshold, an elevation threshold, and / or a distance threshold. For example, the following Table 5 may be constructed: [Table 5]

[0096] At time t1, the UE may transmit Msg1 to the satellite and wait for Msg2 for timing duration T wait The UE may start a timer for TA1 (e.g., a propagation delay between the UE and the satellite).

[0097] At time t2, the gNB centralized unit (gNB-CU) may transmit radio resource control (RRC) information (e.g., ra-ResponseWindow) to the satellite gNG distributed unit (gNB-DU) if Msg1 is correctly decoded.

[0098] At time t3, the satellite waits for a waiting period of T waitWhen the timer expires, the UE may forward the stored RRC information in the ra-ResponseWindow and Msg2 to the UE. The UE may receive Msg2 in the RAR window with a delay of the sum of TA1 + TA2. TA1 may be the calculated propagation delay stored by the UE at time t1. TA2 may be the calculated propagation delay between the UE and the satellite at time t3. Otherwise, if Msg2 is not received by the UE, the UE may resume random access at a higher UL availability range. For example, random access may be resumed at a higher RSRP, a higher elevation angle, or a larger time offset delay at a lower distance according to the mapping table above.

[0099] At time t4, the UE may transmit Msg3 with a timing advance of the sum of TA1+TA2, where TA2 may be the propagation delay between the UE and the satellite. wait When this timer expires, it may wait for Msg4 within the collision resolution timer after a delay of TA3+TA4, where TA3 and TA4 may be the calculated propagation delays between the UE and the satellite when the UE sends Msg3 and receives Msg4, respectively.

[0100] At time t5, the gNB-CU may transmit the RRC information of ra-ContentionResolutionTimer to the satellite gNB-DU when Msg3 is correctly decoded.

[0101] At time t6, the satellite may transfer the stored RRC information of ra-ContentionResolutionTimer and Msg4 to the UE when the satellite passes over the UE. If Msg4 is successfully decoded, the random access can be completed. If not, the UE may serve By using a new offset of ΔT within the serving duration of , random access may resume at a higher UL availability range.

[0102] Case 3-2: For regenerative satellites (e.g., gNB-DU / satellite-processed payloads), timing enhancements for two-step random access or collision-free random access may be specified. Wait duration T wait and serving duration T serve 18 illustrates a sequence diagram for timing enhancement in two-step RACH / CF RACH, gNB DU / CU splitting for regenerative satellites according to some embodiments of the present disclosure.

[0103] Before the random access procedure, the satellite uses the stored SSB, SI, and waiting duration T wait , and / or serving duration T serve to the UE. The wait duration may be indicated by the following options:

[0104] Option-1: Waiting duration T longer than the satellite orbit period duration wait As a constant value of T wait ≧T peiod , which at least guarantees successful communication and / or processing of Msg1 / MsgA with a network configuration at a minimum high reference signal received power (RSRP) threshold, elevation threshold, or distance threshold.

[0105] Option 2: T as an offset and constant value for the wait duration. wait =ΔT+T wait,initial , where the value of the offset may be mapped to a corresponding value of the RSRP threshold, the elevation threshold, and / or the distance threshold. The time offset may be less than the serving duration (e.g., ΔT≦T serve For example, the following Table 6 can be constructed: [Table 6]

[0106] At time t1, the UE may transmit Msg1 / MsgA to the satellite gNB-DU. The UE may wait for timing duration Twait The UE may start a timer for TA1 (e.g., a propagation delay between the UE and the satellite).

[0107] At time t2, the gNB-CU may transmit RRC information in the RAR-ResponseWindow or MsgB-ResponseWindow to the satellite gNB-DU when the satellite passes over the gNB-CU.

[0108] At time t3, the satellite gNB-DU may send RRC information in the RAR-ResponseWindow / MsgB-ResponseWindow and Msg2 / MsgB to the UE if Msg1 / MsgA is correctly decoded.

[0109] At time t4, the waiting time T wait When the timer expires, the UE may receive Msg2 / MsgB in the RAR window with / after a delay of the sum of TA1+TA2. TA2 may be the calculated propagation delay between the UE and the satellite at time t4. Otherwise, if Msg2 / MsgB is not received by the UE, the UE may resume random access at a higher UL availability range. For example, random access may be resumed at a higher RSRP, a higher elevation angle, or a larger time offset delay at a shorter distance according to the mapping table above.

[0110] For successful preamble decoding for MsgA and failure for Msg3, the wait duration may be used for the 4-step RACH fallback procedure.

[0111] (Implementation Example 4: RACH Timing Enhancement Based on Wait Duration and Common TA) If the UE does not have a Global Navigation Satellite System (GNSS) module, the propagation delay (e.g., TA1, TA2) between the UE and the satellite may not be calculated by the UE, and therefore, collisions may occur in the Random Access Response (RAR) window. To cover the round trip time (RTT) between the UE and the satellite, extending the RAR window may help to eliminate the effect of the maximum RTT differential delay. The extension range of the RAR window may depend on the common TA in the following manner: (1) When a common TA is configured in the network, the timing relationship is wait This can be achieved by applying a common TA (for all UEs) and an RAR window extension can be used to cover the maximum RTT differential delay (for all UEs). (2) Without a common TA (configured by the network), T wait Application of

[0047] may be used to extend / update a wide range for the RAR window, the collision resolution timer, and the extension of the RAR window to cover the maximum RTT.

[0112] It should be understood that one or more features from the above implementation examples are not limited to only a particular implementation example, but may be combined in any manner (e.g., in any priority and / or order, simultaneously or otherwise).

[0113] FIG. 19 shows a flow diagram of a method 1900 for timing enhancement in store-and-forward mode. Method 1900 may be implemented using any one or more of the components and devices detailed herein in connection with FIGS. 1-2. In summary, method 1900 may be performed by a communicating wireless node in some embodiments. Additional, fewer, or different operations may be performed in method 1900 depending on the embodiment. At least one aspect of these operations is directed to a system, method, apparatus, or computer-readable medium.

[0114] A wireless communication node (e.g., a base station (BS), which may be part of a regenerative satellite or may be separate from the satellite) may measure the duration until the next service period of the satellite (e.g., T wait ) and the duration of the satellite service period (e.g., T serve ) and a serving duration indicating the waiting duration and serving duration to be used by the wireless communication device (e.g., user equipment (UE)) during the random access procedure. The wireless communication node may transmit (an indication of) the waiting duration and serving duration to be used by the wireless communication device (e.g., user equipment (UE)) during the random access procedure. In some embodiments, the wireless communication node (e.g., a playback satellite) may transmit the waiting duration and serving duration directly to the UE. In a particular embodiment, the wireless communication node (e.g., a BS) may transmit the waiting duration and serving duration to the UE via a satellite (e.g., a transparent satellite). The random access procedure may comprise a four-step random access procedure, or a two-step or non-collision random access procedure.

[0115] In some embodiments, the wait duration may include at least one of the duration of one orbital cycle of the satellite, the processing duration at the wireless communication node, the round-trip propagation time between the satellite and the wireless communication node, the round-trip propagation time between the satellite and the wireless communication device, a fixed value, or the sum of a fixed value and an offset value.

[0116] In some embodiments, the wireless communication node may transmit the wait duration and the serving duration to the satellite via at least one of Master Information Block (MIB) signaling, System Information Block (SIB) signaling, or Radio Resource Control (RRC) signaling. The satellite may store the wait duration and the serving duration. The satellite may transmit the wait duration and the serving duration to the wireless communication device.

[0117] In some embodiments, the wireless communication device may transmit Msg1 or MsgA to the satellite during the first instance of the serving duration at a start time of the first instance of the waiting period (e.g., t1 in FIG. 9 ). The satellite may transmit Msg2 or MsgB to the wireless communication device in response to expiration of the first instance of the waiting period (e.g., t4 in FIG. 9 ). The wireless communication device may receive Msg2 or MsgB from the satellite in a random access response (RAR) window with a delay comprising the sum of the first timing advance (TA1) and the second timing advance (TA2). The wireless communication device may transmit Msg3 during the second instance of the serving duration at a start time of the second instance of the waiting period (e.g., t5 in FIG. 9 ), with a timing advance comprising the sum of TA1 and TA2. The wireless communication device may monitor to receive Msg4 in a delayed collision resolution window that includes the sum of the third timing advance (TA3) and the fourth timing advance (TA4) after expiration of the second instance of the waiting period.

[0118] In some embodiments, the wireless communication device may determine to transmit Msg1, Msg3, or MsgA if (e.g., under the conditions) at least one of: the calculated elevation angle is greater than an elevation angle threshold; the measured Reference Signal Received Power (RSRP) is greater than an RSRP threshold; the calculated distance is less than a distance threshold between the wireless communication device and the satellite; or the remaining portion of the serving duration calculated by the wireless communication device is greater than the sum of the scheduled duration (e.g., K, the scheduled duration of the DCI scheduled Msg3) and the round-trip propagation time between the satellite and the wireless communication device.

[0119] In some embodiments, TA1 may be a propagation delay calculated by the wireless communication device at a start time of the first instance of the waiting period (e.g., t1 in FIG. 9 ). TA2 may be a propagation delay between the wireless communication device and the satellite calculated when the satellite transmits Msg2 or MsgB to the wireless communication device (e.g., t4 in FIG. 9 ). TA3 may be a propagation delay between the wireless communication device and the satellite calculated when the wireless communication device transmits Msg3 (e.g., t5 in FIG. 9 ). TA4 may be a propagation delay between the wireless communication device and the satellite calculated when the wireless communication device transmits Msg4 (e.g., t8 in FIG. 9 ).

[0120] In some embodiments, if Msg2, Msg4, or MsgB is not received (e.g., is not successfully received) by the wireless communication device in response to expiration of the first or second instance of the waiting period, the wireless communication device may retransmit Msg1, Msg3, or MsgA to the satellite at the start time of another instance of the waiting period after a defined offset time (e.g., ΔT, mapped to a higher uplink (UL) availability range).

[0121] In some embodiments, a wireless communication node on a satellite may transmit a waiting duration and a serving duration to a wireless communication device. The wireless communication device may transmit Msg1 or MsgA to the satellite during a first instance of the serving duration at a start time of a first instance of the waiting period (e.g., t1 in FIG. 13 ). The satellite may transmit Msg2 or MsgB to the wireless communication device (e.g., t2 in FIG. 13 ). In response to expiration of the first instance of the waiting period, the wireless communication device may receive Msg2 from the satellite in a random access response (RAR) window with a delay comprising two timing advances (TA). The wireless communication device may transmit Msg3 during a second instance of the serving duration at a start time of a second instance of the waiting period (e.g., t3 in FIG. 13 ). The wireless communication device may monitor to receive Msg4 after expiration of the second instance of the waiting period in a collision resolution window after a delay comprising two TAs. TA may be a propagation delay between the wireless communication device and the satellite. If Msg2, Msg4, or MsgB is not received by the wireless communication device in response to expiration of the first or second instance of the waiting period, the wireless communication device may retransmit Msg1, Msg3, or MsgA to the satellite at the start time of another instance of the waiting period after a defined offset time (e.g., ΔT, mapped to a higher uplink (UL) availability range).

[0122] In some embodiments, a wireless communication node (e.g., gNB-CU) may transmit (an indication of) a waiting duration and a serving duration to a satellite. The satellite may store the waiting duration and the serving duration. The satellite may transmit the waiting duration and the serving duration to a wireless communication device. The wireless communication device may transmit Msg1 or MsgA to the satellite at a start time of a first instance of the waiting period (e.g., t1 in FIG. 17 ) during a first instance of the serving duration. The satellite may transmit Msg2 or MsgB to the wireless communication device in response to expiration of the first instance of the waiting period (e.g., t3 in FIG. 17 ). The wireless communication device may receive Msg2 or MsgB and first radio resource control (RRC) information from the satellite within / after a random access response (RAR) window with / a delay comprising the sum of the first timing advance (TA1) and the second timing advance (TA2). The wireless communication device may transmit Msg3 during the second instance of the serving duration at a start time of the second instance of the waiting period (e.g., t4 in FIG. 17) with / after a timing advance comprising the sum of TA1 and TA2. The wireless communication device may monitor to receive Msg4 and the second RRC information within / in a delayed collision resolution window comprising the sum of a third timing advance (TA3) and a fourth timing advance (TA4) after expiration of the second instance of the waiting period.

[0123] In some embodiments, TA1 may be a propagation delay calculated by the wireless communication device at a start time of the first instance of the waiting period (e.g., t1 in FIG. 17 ). TA2 may be a propagation delay between the wireless communication device and the satellite calculated / determined (e.g., using a GNSS module of the wireless communication device) when the satellite transmits Msg2 or MsgB to the wireless communication device (e.g., t3 in FIG. 17 ). TA3 may be a propagation delay between the wireless communication device and the satellite calculated / determined (e.g., using a GNSS module of the wireless communication device) when the wireless communication device transmits Msg3 (e.g., t4 in FIG. 17 ). TA4 may be a propagation delay between the wireless communication device and the satellite calculated when the wireless communication device receives Msg4. If Msg2, Msg4, or MsgB is not received by the wireless communication device in response to expiration of the first or second instance of the waiting period, the wireless communication device may again transmit Msg1, Msg3, or MsgA to the satellite (e.g., attempt to transmit another Msg1 or MsgA) at the start time of another instance of the waiting period after a defined offset time (mapped to higher uplink (UL) availability, ΔT). The wireless communication device may receive Msg2 or MsgB from the satellite in an RAR window extended to incorporate a common timing advance (e.g., configured / determined by the wireless communication node) for multiple wireless communication devices or a maximum round-trip propagation delay between the wireless communication device and the satellite. The wireless communication device may monitor to receive Msg4 in a collision resolution window extended / modified to incorporate a common timing advance or a maximum round-trip propagation delay between the wireless communication device and the satellite.

[0124] In some embodiments, the wireless communication device (e.g., UE) indicates the duration until the next service period of the satellite to be used during the random access procedure (e.g., Twait ) waiting duration, and the duration of the satellite service period (e.g., T serve ) serving duration. The waiting duration and serving duration may be configured by a wireless communication node (e.g., a BS, which may be part of a playback satellite, for example).

[0125] While various embodiments of the present solution have been described above, it should be understood that they are presented by way of example only, and not by way of limitation. Similarly, various diagrams may depict example architectures or configurations, which are provided to enable those skilled in the art to understand example features and functionality of the present solution. However, such skilled artisans will understand that the present solution is not limited to the example architectures or configurations shown, but may be implemented using various alternative architectures and configurations. Additionally, as will be understood by those skilled in the art, one or more features of one embodiment may be combined with one or more features of another embodiment described herein. Thus, the breadth and scope of the present disclosure should not be limited by any of the illustrative embodiments described above.

[0126] It will also be understood that any reference to elements herein using designations such as "first," "second," etc., generally does not limit the number or order of those elements. Rather, these designations may be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, reference to a first and a second element does not imply that only two elements may be used or that the first element must precede the second element in any way.

[0127] Additionally, those skilled in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, and symbols that may be referred to in the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0128] Those skilled in the art will further appreciate that any of the various illustrative logical blocks, modules, processors, means, circuits, methods, and functions described in connection with the aspects disclosed herein may be implemented by electronic hardware (e.g., digital implementations, analog implementations, or a combination of the two), firmware, various forms of programs or design code incorporating instructions (which may be referred to herein for convenience as “software” or “software modules”), or any combination of these techniques. To clearly illustrate this interchangeability of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software, or a combination of these techniques, depends on the particular application and design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in various ways for each particular application, but such implementation decisions do not cause a departure from the scope of the present disclosure.

[0129] Furthermore, those skilled in the art will understand that the various illustrative logic blocks, modules, devices, components, and circuits described herein may be implemented in or performed by an integrated circuit (IC), which may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, or any combination thereof. The logic blocks, modules, and circuits may further include an antenna and / or transceiver for communicating with various components within a network or device. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration for performing the functions described herein.

[0130] If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein may be implemented as software stored on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium enabled to transmit a computer program or code from one place to another. Storage media can be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0131] As used herein, the term "module" refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. Additionally, while for purposes of discussion, various modules are described as individual modules, those skilled in the art will appreciate that two or more modules may be combined to form a single module that performs associated functions according to embodiments of the present solution.

[0132] Additionally, memory or other storage devices, as well as communication components, may be used in embodiments of the solution. It will be understood that, for clarity, the above description describes embodiments of the solution with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processing logic elements, or domains may be used without detracting from the solution. For example, functionality shown to be performed by separate processing logic elements or controllers may be performed by the same processing logic element or controller. References to specific functional units therefore do not refer to a strict logical or physical structure or organization, but merely to suitable means for providing the described functionality.

[0133] Various modifications to the embodiments described in this disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the novel features and principles disclosed herein as set forth in the appended claims.

Claims

1. 1. A method, comprising: configuring, by the wireless communications node, a waiting duration indicating a duration until the next service period for a satellite and a serving duration indicating a duration of said service period for said satellite; transmitting, by the wireless communication node, the waiting duration and the serving duration to be used by a wireless communication device during a random access procedure; A method comprising:

2. 10. The method of claim 1, wherein the random access procedure comprises a four-step random access procedure, or a two-step or non-collision random access procedure.

3. The wait duration is the duration of one orbital cycle of said satellite; a duration of processing at said wireless communication node; a round trip propagation time between the satellite and the wireless communication node; a round-trip propagation time between the satellite and the wireless communication device; a fixed value, or Sum of fixed value and offset value The method of claim 1 , comprising at least one of:

4. transmitting, by the wireless communications node, the waiting duration and the serving duration to the satellite via at least one of Master Information Block (MIB) signaling, System Information Block (SIB) signaling, or Radio Resource Control (RRC) signaling; The method of claim 1 , wherein the satellite stores the wait duration and the serving duration and transmits the wait duration and the serving duration to the wireless communication device.

5. the wireless communication device transmits Msg1 or MsgA to the satellite during a first instance of the serving duration at a start time of a first instance of the waiting period; the satellite transmitting Msg2 or MsgB to the wireless communication device in response to expiration of the first instance of the waiting period; the wireless communication device receives the Msg2 or MsgB from the satellite in a random access response (RAR) window having a delay comprising the sum of a first timing advance (TA1) and a second timing advance (TA2); the wireless communication device transmits Msg3 during a second instance of the serving duration at a start time of a second instance of the waiting period with a timing advance comprising the sum of the TA1 and the TA2; or The wireless communication device monitors to receive Msg4 in a delayed collision resolution window comprising the sum of a third timing advance (TA3) and a fourth timing advance (TA4) after expiration of the second instance of the waiting period.

5. The method of claim 4 , wherein at least one of

6. the wireless communication device The calculated elevation angle is greater than the elevation angle threshold; The measured reference signal received power (RSRP) is greater than the RSRP threshold; The calculated distance is less than a distance threshold between the wireless communication device and the satellite; or the remaining portion of the serving duration calculated by the wireless communication device is greater than the sum of the scheduled duration and the round-trip propagation time between the satellite and the wireless communication device.

6. The method of claim 5, wherein the method determines to transmit the Msg1, the Msg3, or the MsgA if at least one of the following is true:

7. TA1 is a propagation delay calculated by the wireless communication device at the start time of the first instance of the waiting period; TA2 is the propagation delay between the wireless communication device and the satellite calculated when the satellite transmits Msg2 or MsgB to the wireless communication device; The TA3 is the propagation delay between the wireless communication device and the satellite calculated when the wireless communication device transmits the Msg3; or TA4 is the propagation delay between the wireless communication device and the satellite calculated when the wireless communication device receives Msg4.

6. The method of claim 5, wherein at least one of

8. if the Msg2, Msg4, or MsgB is not received by the wireless communication device in response to expiration of the waiting period, 6. The method of claim 5, wherein the wireless communication device retransmits the Msg1, Msg3, or MsgA to the satellite at a start time of another instance of the waiting period after a defined offset time.

9. 2. The method of claim 1, comprising transmitting, by the wireless communications node on the satellite, the wait duration and the serving duration to the wireless communications device.

10. the wireless communication device transmits the Msg1 or MsgA to the satellite during a first instance of the serving duration at a start time of a first instance of the waiting period; The satellite transmits Msg2 or MsgB to the wireless communication device; In response to expiration of the first instance of the waiting period, the wireless communication device receives Msg2 from the satellite in a random access response (RAR) window having a delay comprising two timing advances (TA); the wireless communication device transmits Msg3 during a second instance of the serving duration at a start time of a second instance of the waiting period; or The wireless communication device monitors to receive Msg4 in a delayed collision resolution window comprising two TAs after expiration of the second instance of the waiting period.

10. The method of claim 9, wherein at least one of

11. The method of claim 10 , wherein the TA is a propagation delay between the wireless communication device and the satellite.

12. if the Msg2, Msg4, or MsgB is not received by the wireless communication device in response to expiration of the waiting period, 11. The method of claim 10, wherein the wireless communication device retransmits the Msg1, Msg3, or MsgA to the satellite at a start time of another instance of the waiting period after a defined offset time.

13. transmitting, by the wireless communications node, the waiting duration and the serving duration to the satellite; The method of claim 1 , wherein the satellite stores the wait duration and the serving duration and transmits the wait duration and the serving duration to the wireless communication device.

14. the wireless communication device transmits Msg1 or MsgA to the satellite during a first instance of the serving duration at a start time of a first instance of the waiting period; the satellite transmitting Msg2 or MsgB to the wireless communication device in response to expiration of the first instance of the waiting period; the wireless communication device receives the Msg2 or MsgB and first radio resource control (RRC) information from the satellite in a random access response (RAR) window having a delay comprising the sum of a first timing advance (TA1) and a second timing advance (TA2); the wireless communication device transmits Msg3 during a second instance of the serving duration at a start time of a second instance of the waiting period with a timing advance comprising the sum of the TA1 and the TA2; or The wireless communication device monitors to receive Msg4 and second RRC information in a delayed collision resolution window comprising a sum of a third timing advance (TA3) and a fourth timing advance (TA4) after expiration of the second instance of the waiting period.

14. The method of claim 13, wherein at least one of

15. TA1 is a propagation delay calculated by the wireless communication device at the start time of the first instance of the waiting period; TA2 is the propagation delay between the wireless communication device and the satellite calculated when the satellite transmits Msg2 or MsgB to the wireless communication device; The TA3 is the propagation delay between the wireless communication device and the satellite calculated when the wireless communication device transmits the Msg3; or TA4 is the propagation delay between the wireless communication device and the satellite calculated when the wireless communication device receives Msg4.

15. The method of claim 14, wherein at least one of

16. if the Msg2, Msg4, or MsgB is not received by the wireless communication device in response to expiration of the waiting period, 16. The method of claim 15, wherein the wireless communication device retransmits the Msg1, Msg3, or MsgA to the satellite at a start time of another instance of the waiting period after a defined offset time.

17. the wireless communication device receives the Msg2 or MsgB from the satellite in an RAR window extended to incorporate a common timing advance for multiple wireless communication devices or a maximum round-trip propagation delay between the wireless communication device and the satellite; or The wireless communication device monitors to receive the Msg4 in a collision resolution window extended to incorporate the common timing advance or the maximum round-trip propagation delay between the wireless communication device and the satellite.

15. The method of claim 5, 10, or 14.

18. 1. A method, comprising: receiving, by the wireless communication device, a configuration comprising a waiting duration indicating a duration until the next serving period of a satellite to be used during a random access procedure and a serving duration indicating a duration of the serving period of said satellite; The method, wherein the waiting duration and the serving duration are configured by a wireless communications node.

19. 19. A non-transitory computer readable medium storing instructions that, when executed by at least one processor, cause the at least one processor to perform the method of any one of claims 1 to 18.

20. Apparatus comprising at least one processor configured to perform the method of any one of claims 1 to 18.

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