Terminal, method, base station and communication system

Abstract

A terminal according to one aspect of the present disclosure comprising: a processor configured to determine, based on a function using specific information, a plurality of numbers for identifying periods for transmitting a plurality of replicas of a message; and a transmitter configured to transmit the plurality of replicas in a plurality of periods, wherein each of the plurality of periods is associated with a respective one of the determined plurality of numbers, without appending information explicitly indicating any of the determined plurality of numbers to any of the plurality of replicas. According to one aspect of the present disclosure, reducing signaling overhead and / or increasing implementation flexibility can be achieved.

Description

TERMINAL, METHOD, BASE STATION AND COMMUNICATION SYSTEMCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims priority to U.S. Provisional Application No. 63 / 674,594, filed on July 23, 2024, the contents of which are incorporated herein by reference in their entirety.

[0002] Apparatuses and methods consistent with the present disclosure relate generally to communications, more specifically, methods, systems, and devices for pseudo-random contention resolution diversity slotted ALOHA.

[0003] In radio communication systems, random access is an integral part of the communication connection setup and time advance adjustments. Some of Third Generation Partnership Project (3GPP) radio interfaces are based on Slotted ALOHA (SA) protocol where the main principle is that the transmitter sends data whenever there is data in the transmitter buffer and the receiver resolves conflicts caused by multiple simultaneous transmission attempts from different transmitters (Non Patent Literature 1, 2). If a collision or congestion occurs, a transmitter may back-off for a random period and resume transmission after a while. Upon consistent failures, each transmitter may extend the back-off time, e.g. after every failed transmission attempt, to resolve severe congestion.

[0004] Non Patent Literature 1: 3GPP TS 36.213 V18.2.0, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures”

[0005] Non Patent Literature 2: 3GPP TS 36.321 V18.1.0, “Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol specification”

[0006] In some random access protocols, such as Diversity Slotted ALOHA (DSA), a transmitter sends multiple replicas of the same message in different, randomly chosen sub-frames of a radio frame. An improvement of DSA is Contention Resolution DSA (CRDSA) where the transmitter appends each replica with subframe numbers of all replicas sent within the radio frame, and the receiver uses information on the subframe numbers in successive interference cancellation after successful reception of at least one replica. This allows the receiver, upon successful reception of at least one replica, to know the location of the other replicas and perform successive interference cancellation to resolve collisions.

[0007] However, this approach has shortcomings. Appending the subframe numbers to each replica creates significant signaling overhead, consuming valuable channel resources. Furthermore, this method creates a tight coupling between the transmitter and receiver, as the transmitter must know in advance whether the receiver uses CRDSA in order to decide whether to append the subframe numbers.

[0008] Thus, one object of the present disclosure is to provide a terminal, a method, a base station and a communication system that can reduce signaling overhead and / or increases implementation flexibility.

[0009] A terminal according to one aspect of the present disclosure comprising: a processor configured to determine, based on a function using specific information, a plurality of numbers for identifying periods for transmitting a plurality of replicas of a message; and a transmitter configured to transmit the plurality of replicas in a plurality of periods, wherein each of the plurality of periods is associated with a respective one of the determined plurality of numbers, without appending information explicitly indicating any of the determined plurality of numbers to any of the plurality of replicas.

[0010] According to one aspect of the present disclosure, reducing signaling overhead and / or increasing implementation flexibility can be achieved.

[0011] FIG. 1 is a schematic diagram illustrating a system for some embodiments of the present disclosure.

[0012] FIG. 2 is a schematic diagram illustrating an exemplary functional configuration of each device for some embodiments of the present disclosure.

[0013] FIG. 3 is a schematic diagram illustrating an exemplary hardware configuration of each device for some embodiments of the present disclosure.

[0014] FIG. 4 is a schematic diagram illustrating an example of calculating sub-frame numbers for replicas using the function.

[0015] FIG. 5 is a table illustrating an example of subframe number combinations.

[0016] The present disclosure may introduce a method and apparatus for resource efficient random access in radio communication systems.

[0017] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise represented. The implementations set forth in the following description of exemplary embodiments do not represent all implementations consistent with the present disclosure. Instead, they are merely examples of systems, apparatuses, and methods consistent with aspects related to the present disclosure as recited in the appended claims.

[0018] In the present disclosure, "A / B," “A and / or B” and "at least one of A and B" may be used interchangeably. In the present disclosure, "A / B / C," “A and / or B and / or C” and "at least one of A, B and C" may be used interchangeably.

[0019] (System) FIG. 1 is a schematic diagram illustrating a system for some embodiments of the present disclosure. The system 1 may be a system implementing a communication using Long Term Evolution (LTE), 5th generation mobile communication system New Radio (5G NR) and so on the specifications of which have been drafted by Third Generation Partnership Project (3GPP). The system 1 may include one or more user equipment (UE) 10, one or more base stations (BS) 20, one or more core networks (CN) 30.

[0020] In the present disclosure, terms “system,” “radio system,” “radio communication system,” “radio interface,” and “network” are used as general terms which include one or both of terrestrial network systems and non-terrestrial network (NTN) systems such as satellite systems. In the present disclosure, these terms may be used interchangeably.

[0021] The UE 10 may be a terminal supporting at least one of communication schemes such as LTE, 5G NR, and so on. The UE 10 may be connected to at least one of plurality of BS 20. The UE 10 may take any form, including but not limited to, a vehicle, a component mounted in a vehicle, a road-side unit, a laptop computer, a wireless terminal including a mobile phone, a wireless handheld device, or wireless personal device.

[0022] In the present disclosure, a UE, a mobile station and a terminal may be used interchangeably.

[0023] The plurality of base stations 10 may be connected each other by a wired connection (for example, optical fiber) or a wireless connection (for example, an NR communication). The base station 10 may be connected to a core network 30 through another base station 10 or directly.

[0024] In the present disclosure, a BS may be referred to as the terms such as a NodeB, an eNodeB (eNB), a gNodeB (gNB), a radio access network (RAN), a carrier, a component carrier, a sector, a cell, a cell group, a super cell, a macro cell, a small cell, a femto cell, a pico cell, and so on. In the present disclosure, a network may mean an apparatus (for example, a BS) included in the network.

[0025] In the present disclosure, a term “node” is used as a general term which includes user equipment (UE), a relay node, a vehicle mounted module, a network infrastructure node such as a base station (BS), a roadside unit, a repeater, a transponder, a wireless router, a controller, an access point, a transmission point (TP), a reception point (RP), a transmission / reception point (TRP), a panel, and sub-systems thereof. In the present disclosure, these entities (apparatuses, devices) may be used interchangeably.

[0026] The communication between UE 10 and BS 20 may be transferred via one or more apparatuses for NTN, e.g., a Geostationary Earth Orbit (GEO) satellite, a Medium-Earth Orbit (MEO), a Low Earth Orbit (LEO) satellite, a High Altitude Platform Station (HAPS), an NTN payload and an NTN gateway. In the present disclosure, the BS 20 may include a BS in a terrestrial network and / or a BS in NTN (or the BS on / within the above one or more apparatuses for NTN). In the present disclosure, the BS 20 and the above one or more apparatuses for NTN may be used interchangeably.

[0027] The NTN (or the system 1) may provide a non-terrestrial NR access to the UE 10 by means of the NTN payload and the NTN Gateway. A wireless link between the NTN payload and the UE 10 may be called as a service link, and a wireless link between the NTN Gateway and the NTN payload may be called as a feeder link.

[0028] A satellite, such as GEO, MEO, LEO and HAPS, may be a space-borne vehicle orbiting the Earth embarking the NTN payload. The NTN payload may be a network node, embarked on board the satellite, providing connectivity functions, between the service link and the feeder link. The NTN Gateway may be an earth station located at the surface of the earth, providing connectivity to the NTN payload using the feeder link.

[0029] The NTN payload may transparently forward the radio protocol received from the UE 10 (via the service link) to the NTN Gateway (via the feeder link) and vice-versa.

[0030] The core network 30 may include at least one of Evolved Packet Core (EPC), 5G Core Network (5GCN), and so on.

[0031] In the system 1, an orthogonal frequency division multiplexing (OFDM)-based wireless access scheme may be used. For example, in at least one of the downlink (DL) communication and the uplink (UL) communication, Cyclic Prefix OFDM (CP-OFDM), Discrete Fourier Transform Spread OFDM (DFT-s-OFDM), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), and the like may be used.

[0032] (Functional / Hardware Configuration of Device) FIG. 2 is a schematic diagram illustrating an exemplary functional configuration of each device for some embodiments of the present disclosure. For example, the UE 10 may have a control unit 110, a communication unit 120, an input / output unit 130, and a storage unit 140.

[0033] The BS 20 may have similar functional configurations. For this reason, in this exemplary functional configuration, the sign of the functional block corresponding to each device is also shown with the largest digit of the sign indicating each device (e.g., the largest digit "2" of "20" for BS 20) replaced with "1". In the following, the functional blocks relating to the UE 10 will be explained, but it is understood that the same explanation applies to other devices as well.

[0034] In this example, the functional blocks of the characteristic parts of the system are mainly shown, and each device may also have other functional blocks necessary for other processes. The configuration may also not include some of the functional blocks.

[0035] The control unit 110 implements control of the UE 10 and provides various functions. For example, the control unit 110 may control communication with other devices via the communication unit 120. The control unit 110 may also obtain information necessary for processing based on information received via the communication unit 120. The control unit 110 may be referred to as a processing unit.

[0036] The communication unit 120 communicates (transmits / receives) with other devices via wired / wireless communication. The communication unit 120 may obtain information from the received signal and output it to the control unit 110, or it may convert information input from the control unit 110 into a signal and transmit it. Communication unit 120 may be referred to as a transmitter, receiver, or transmitter / receiver.

[0037] The input / output unit 130 may include an input unit that accepts input from a person. The input unit may be connected to a predetermined device, storage medium, etc., and may accept data input. The input unit may output input results to, for example, the control unit 110.

[0038] The input / output unit 130 may also include an output unit that outputs data, content, etc. in a format that can be perceived by humans. The output unit may comprise a display unit that displays images, an audio output unit that outputs sound, and the like.

[0039] The storage unit 140 stores (holds) various information used by the management unit 10 for processing. The control unit 110 may instruct the storage unit 140 to read and write data.

[0040] The functional blocks (components) in FIG. 2 may be implemented in arbitrary combinations of at least one of hardware and software. Each functional block may be realized by one apparatus that is physically or logically coupled, or may be realized by directly or indirectly connecting two or more physically or logically separate apparatuses (for example, via wire, wireless, or the like) and using these apparatuses. The functional blocks may be implemented by combining softwares into the apparatus described above or the plurality of apparatuses described above.

[0041] FIG. 3 is a schematic diagram illustrating an exemplary hardware configuration of each device for some embodiments of the present disclosure. For example, the UE 10, the BS 20, and the other devices in the present disclosure may function as a computer that executes the processes of the radio communication method(s) in the present disclosure. Each device may have an antenna 910, a Radio Frequency (RF) circuit 920, a processor 930, a network interface 940, an input device / output device 950, a memory 960, and a storage 970.

[0042] For example, the above control unit X10 (e.g., X = 1, 2; same below) described above may be implemented by the processor 930. The communication unit X20 may be implemented by the antenna 910 / RF circuit 920 / network interface 940. The input / output unit X30 may be implemented by the input device / output device 950. The storage unit X40 may be implemented by the memory 960 / storage 970.

[0043] The hardware configuration of each device may be configured to include one or more of the elements shown in this exemplary hardware configuration, or may be configured without some of the elements. For example, the UE 10 may not have a network interface 940.

[0044] The antenna 910 converts signals into radio waves and radiates said radio waves into space. The antenna 910 also receives radio waves in space and converts said radio waves into signals. The antenna 910 may be mounted in plurality, may include a transmitting antenna and a receiving antenna, or may include a single antenna for transmitting and receiving. The antenna 910 may include a directional antenna or may include multiple antenna elements. The antenna 910 may include one or more antenna elements and may enable different input-output antenna configurations.

[0045] The RF circuit 920 performs analog processing of signals transmitted and received via antenna 910. The RF circuit 920 may include filters (e.g., high frequency filters, low pass filters), amplifiers, modulators, frequency synthesizers, analog-to-digital conversion circuit, digital-analog conversion circuit, Fast Fourier Transform (FFT) / Inverse Fast Fourier Transform (IFFT) processing circuit, etc.

[0046] The RF circuit 920 may perform amplification, filter processing, demodulation to a baseband signal, etc. on the received radio frequency band signal and output to processor 930 RF circuit 920 may perform modulation to a radio frequency band, filter processing, amplification and transmit the radio frequency band signals via the transmitter / receiver antenna 910. The RF circuit 920 may perform physical layer processing (e.g., processing of lower functions of the physical layer), and may perform beamforming processing such as analog beamforming and digital beamforming processing.

[0047] The processor 930 may control the entire device. The processor 930 may read programs (program code), software (software modules), data, and the like from the storage 970 to the memory 960 and perform various processes according to these. For example, the processor 930 may execute and control an operating system (OS) program that is loaded into the memory 960. The programs are used to allow computers to execute at least part of methods (operations) shown in embodiments of the present disclosure. For example, the control unit 110 (210) may be implemented by control programs that are stored in the memory 960 and that operate on the processor 930, and other functional blocks may be implemented likewise.

[0048] The processor 930 may be configured by a central processing unit (CPU), which may include interfaces to peripheral devices, control units, arithmetic units, registers, and the like. The processor 930 may also be a microprocessor, Digital Signal Processor (DSP), Application Specific Integrated Circuit (ASIC), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), etc.

[0049] The processor 930 may perform digital processing of signals transmitted and received via the antenna 910 and the RF circuit 920. Said digital processing may include physical layer processing (e.g., processing of higher functions of the physical layer), processing of layers above the Medium Access Control (MAC) layer, modulation, demodulation, coding, decoding, scrambling, etc. The processor 930 also processes signals sent and received via network interface 940.

[0050] The processor 930 may include a plurality of processors or may be a single processor. The multiple processors may include a baseband processor that performs the digital processing described above and one or more processors that perform other processing (e.g., overall control).

[0051] The network interface 940 may be, for example, a network adapter, which may be wired to an external network to send and receive signals.

[0052] The RF circuit 920 / baseband processor / network interface 940 may be an integral part of the RF circuit 920 / baseband processor / network interface 940. The network interface 940 may be referred to as a network controller, network card, communication module, etc.

[0053] The input device / output device 950 may comprise an input device that accepts external input (e.g., keyboard, mouse, microphone, switches, buttons, sensors, etc.), an output device that performs external output (e.g., display, speaker, Light Emitting Diode (LED) lamp etc.), and a device (e.g., a touch panel) that integrates these devices.

[0054] The memory 960 is a computer-readable, non-transitory storage medium that stores a program to be executed by the processor 930, parameters related to said program, and various other information. The memory 960 is at least one of Read Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically EPROM (EEPROM), Random Access Memory (RAM), and flash memory. All or part of the memory 960 may be contained within processor 930. Memory 960 may be referred to as a register, cache, main memory (main storage), etc.

[0055] The storage 970 is a computer-readable, non-transitory storage medium that stores a variety of information. The storage 970 may include, for example, flexible disks, floppy (registered trademark) disks, magneto-optical disks (e.g., compact disc (Compact Disc ROM (CD-ROM), digital versatile disk, Blu-ray (registered trademark) disk), a removable disk, a hard disk drive (Hard Disc Drive (HDD)), a smart card, a flash memory device (e.g., Solid State Drive (SSD)), or at least one other. The storage 970 may be referred to as an auxiliary storage device.

[0056] The processor 930, memory 960, and other devices may be connected by a bus for communicating information. A single bus may be used within a device, or different buses may be used between devices.

[0057] The BS 20 may be separated into three elements: the Radio Unit (RU), the Distributed Unit (DU), and the Central Unit (CU). The RU implements RF processing and lower functions of the physical layer. The DU implements the upper functions of the physical layer, the functions of the MAC layer, and the functions of the Radio Link Control (RLC) layer. The CU realizes the functions of the Packet Data Convergence Protocol (PDCP) layer, the Service Data Adaptation Protocol (SDAP), and the Radio Resource Control (RRC) layer.

[0058] In this disclosure, BS 20 may include one device that realizes all the functions of RU, DU and CU, or may include multiple devices that each realize some of the functions of RU, DU and CU.

[0059] Other devices in the present disclosure may also be implemented by multiple devices that are physically located apart from each other. Conversely, a plurality of different devices in this disclosure may be implemented as a single device.

[0060] Some or all of the devices in this disclosure may also mean logical devices realized by virtual machines, containers, Docker, etc., or physical devices that operate such logical devices.

[0061] (Slotted ALOHA) In radio communication systems, random access is an integral part of the communication connection setup and time advance adjustments. Some of Third Generation Partnership Project (3GPP) radio interfaces are based on Slotted ALOHA (SA) protocol where the main principle is that the transmitter sends data whenever there is data in the transmitter buffer and the receiver resolves conflicts caused by multiple simultaneous transmission attempts from different transmitters. If a collision or congestion occurs, a transmitter may back-off for a random period and resume transmission after a while. Upon consistent failures, each transmitter may extend the back-off time, e.g. after every failed transmission attempt, to resolve severe congestion.

[0062] Even though SA is a well-established and simple protocol, it is known to be very inefficient because at maximum only one third of the channel capacity can be utilized.

[0063] 3GPP is currently studying more efficient random-access protocols within the scope of Non-Terrestrial Networks (NTN) work item for Internet of Things (IoT) type of applications.

[0064] One of the state-of-the-art solutions is to use Diversity Slotted ALOHA (DSA). The main idea of DSA is to send multiple replicas of the same message in different and randomly chosen sub-frames of a radio frame. If the transmitter sends multiple replicas in a radio frame, the likelihood of successful reception is increased because the receiver may receive at least one replica without collisions. A downside of DSA is that the system may get congested even at lower traffic loads than SA, and also sending multiple replicas increases the collision probability. An improvement of DSA is Contention Resolution DSA (CRDSA) where the transmitter appends each replica with subframe numbers, and the receiver uses the information in successive interference cancellation after successful reception of at least one replica. It means that all replicas convey all randomly generated sub-frame numbers sent within the radio frame and the receiver uses the information to produce as many collision-free outcomes as possible. For example, if the transmitter sends 3 replicas in subframes 4, 6, and 1, it appends the subframe numbers 4, 6, and 1 in all replicas. After successful reception of a replica, e.g., in sub-frame 6, the receiver knows that the transmitter randomly sent the same replica in subframes 1 and 4, and thereby the signal received in sub-frame 6 can be cancelled from sub-frames 1 and 4. Prior to random access, the transmitter needs to know what kind of receiver is implemented in order to decide whether to append sub-frame numbers in the replicas.

[0065] For CRDSA, there are two variants: - Constant Replication Ratio CRDSA (CR-CRDSA): using a constant number of replicas of each message. - Variable Replication Ratio CRDSA (VR-CRDSA): using a varying number of replicas for the different message, where the number of replicas is determined according to a pre-defined probability distribution.

[0066] Some embodiments in the present disclosure may provide the way to derive one or more pseudo random numbers from the message content, system parameters and / or other information that are known by both sides of the radio interface instead of using a local random number generator in the transmitter, for deriving the sub-frame numbers of the replicas and / or the number of the replicas. With this, the sub-frame numbers may be not appended in the replicas, or not appended in all the replicas.

[0067] A shortcoming of the state-of-the-art solutions such as DSA and CRDSA is signaling overhead caused by appended sub-frame numbers, and coupling between transmitter and receiver because the transmitter needs to know if the receiver uses DSA or CRDSA. The chief advantage of some embodiments in the present disclosure is that both the transmitter and the receiver know the message content and the system parameters and therefore they can derive the sub-frame numbers of the replicas and / or the number of the replicas without the use of appended sub-frame numbers. In addition, the transmitter does not need to know whether the receiver implements DSA or CRDSA which may further reduce signaling overhead.

[0068] (Method) The methods (wireless (or radio) communication methods, control methods) described below may be applied in the system 1 described above. A transmitter in the methods may be the UE 10 and may be considered as a UE. A receiver in the methods may be the BS 20 and may be considered as a BS.

[0069] The present disclosure discloses a method and apparatus for new CRDSA random access protocol that may be called Pseudo-Random CRDSA (PR-CRDSA) random access protocol.

[0070] Methods in the present disclosure can be applied to any wireless communication system that makes use of random access but, in the rest of the disclosure, the method is exemplified with, but not limited to, terrestrial mobile radio communication systems, such as 3GPP LTE and / or NR radio access technology.

[0071] In one embodiment, a transmitter may trigger a random access by sending two or more replicas of a message in two or more subframes of a radio frame where each subframe of the radio frame are associated with a number. The transmitter may compute sub-frame numbers for replica transmissions and / or the number of the replica transmissions as a function of the message content, and / or system parameters provided by a receiver, and / or reported radio measurements conveyed in the message and / or other information known by the transmitter and receiver. The receiver may use the same function for computation of sub-frame numbers and / or the number of the replica transmissions by decoding a replica of the message whereof it obtains subframe numbers for other replicas within the radio frame. The receiver may use the information of sub-frame numbers for successive interference cancellation or other type of advanced receiver operation.

[0072] In the present disclosure, “radio frame” may be replaced with a first period (or, duration, occasion, time unit) and “subframe” may be replaced with a second period (or, duration, occasion, time unit) that is shorter than the first period. In the present disclosure, a message, a payload, data, a packet, a transport block, a field and an information element may be used interchangeably.

[0073] In another embodiment, the function can make use of arithmetic operations, for example, multiplications, additions and modulo operations among message contents and / or system parameters to create a pseudo-random number known by both sides of the radio interface. One example of such a function (a pseudo-random number generator) is a linear congruential generator composed of random generator parameters, such as a seed value, multiplier, increment, and modulus, but any other type of generator or function may be used.

[0074] In another embodiment, a Cyclic Redundancy Checksum, i.e., Cyclic Redundancy Check (CRC) from a message, a transport block, a payload, data, a packet, a field, or information element could be used. For example, CRC computed with bits of the message may be attached to the message for error detection. The CRC may be scrambled by an identity, such as a unique user identity described later. In another element, any form of checksum could be used.

[0075] In another embodiment, the transmitter may use the function for generating a sequence of pseudo-random numbers, e.g., by means of a linear congruential generator, whereof each number in the sequence may be a sub-frame number for a replica transmission. The length of the sequence may be at least the number of replicas transmitted within a radio frame. An arithmetic operation such as a modulo operation in the function may limit the maximum value of each pseudo-random number to the number of sub-frames within the radio frame. The receiver may find the replicas by using the same generator function.

[0076] FIG. 4 is a schematic diagram illustrating an example of calculating sub-frame numbers for replicas using the function. For example, the generator may provide a sequence of sub-frame numbers for 3 replicas in a radio frame consisting of 12 sub-frames which means that the length of the sequence is 3 and the modulus may be set to value 12 assuming that the first sub-frame is numbered as 0. One possible pseudo-random number sequence for the example is {7, 2, 11} resulting in transmission of 3 replicas in sub-frames 7, 2, and 11 as shown in FIG.4. Note that “12” in this example may be read as “N” that may be an integer, e.g. 10.

[0077] In another embodiment, the transmitter may provide at least one of the random generator parameters, such as a seed value, increment, multiplicator and modulus, to the receiver contained in a transferred message or replica. Upon successful reception of a replica, the receiver may generate the same pseudo-random sequence as the transmitter. The transmitter may update at least one of the random generator parameters and transmit the updated value of the at least one of the random generator parameters to the receiver by the transferred message or replica.

[0078] In another embodiment, the receiver may provide at least one of the random generator parameters, such as a seed value, increment, multiplicator and modulus, to the transmitter contained in radio interface signalling, e.g., RRC signalling. The receiver may update at least one of the random generator parameters and transmit the updated value of the at least one of the random generator parameters to the transmitter by the radio interface signalling.

[0079] In another embodiment, a list of possible sub-frame number combinations for a given number of replicas in a radio frame may be pre-defined in a data structure or object such as an indexed list, table, or key-value pair where an index or key produces sub-frame numbers for replicas. For example, if an exhaustive list of combinations may be defined for transmission of 3 replicas in a radio frame composed of 12 subframes then 220 combinations are possible because 3 sub-frames can be chosen from 12 sub-frames in 220 different ways. Each entry of the table may be associated with a unique index ranging from 0 to 219. FIG. 5 is a table illustrating an example of subframe number combinations. FIG.5 illustrates the first 9 combinations of the above 220 combinations. In this embodiment a pseudo-random number may be used as an index in the table where the modulus is set to value 220. The transmitter / receiver may calculate a pseudo-random number using the function, and may generate / obtain a sequence of sub-frame numbers for replicas or the number of replicas based on the data structure or object and the pseudo-random number.

[0080] It should be noted that the combinations in Table 1 are only examples. Other combinations are possible, for example (0,2,3) or (9,10,11). The indexes of the combinations in the table can also be randomly permutated to create randomness in the sense that the correlation between adjacent entries is removed as much as possible, e.g. the combination (0,1,2) can appear at any index from 0 to 219 and likewise the combination (0,1,3) does not need to be located next to (0,1,2). Note that “12” in this example may be read as “N” that may be an integer, e.g. 10.

[0081] <Message Content Used in the Function> In another embodiment, a message content used in the function may be a unique user identity conveyed in the message. An example of such an identity is the 3GPP Serving Temporary Mobile Subscriber Identity (S-TMSI) which may uniquely define the subscriber unit in a tracking area, or a Radio Network Temporary Identity (RNTI) which may uniquely define the device in a cellular radio network cell coverage area, or UE Contention Resolution Identity which may uniquely define the devices in a cellular radio network cell coverage area and may be used for contention resolution. The unique user identity may provide randomization between different users. In the present disclosure, “S-TMSI” may mean “System Architecture Evolution(SAE)-Temporary Mobile Subscriber Identity,” “5G-Short(S)-Temporary Mobile Subscriber Identity,” and the like. In the present disclosure, “RNTI” may be Cell-RNTI (C-RNTI), Temporary Cell RNTI (TC-RNTI), Random Access RNTI (RA-RNTI), RNTI for PR-CRDSA, and the like.

[0082] In another embodiment, a message content used in the function could be the International Mobile Subscriber Identity (IMSI) of one node, for example the transmitting node.

[0083] In another embodiment, a message content used in the function may be an establishment cause value (or cause value) that provides an establishment cause for an establishment of a connection in accordance with information received from upper layers. The connection may be a 3GPP radio resource control (RRC) connection. An example of such a cause value is a RRC protocol field (e.g., establishmentCause field) to indicate a priority or reason of access request, e.g., delay tolerant access, high priority, mobile originated request, and so on. In the present disclosure, the cause value may be included in a connection request (e.g., RRC CONNECTION REQUEST message), a setup request (e.g., RRCSetupRequest message), and the like. In the present disclosure, the cause value may indicate cause (reason) regarding connection other than the establishment. The cause values may be specified as an enumeration which can be interpreted as an integer and used as input in the function. The cause value may provide randomization between different traffic types and priorities.

[0084] In another embodiment, a message content used in the function may be a reported radio measurement. One example of such a reported radio measurement is the reported channel quality indicator (CQI). For example, LTE Narrow Band (NB) IoT early data transmission request may contain a CQI value obtained from downlink control channel measurements to be used, e.g., for downlink early data transmissions, i.e. from the receiver back to the transmitter that triggered a random access. The reported radio measurement may create randomization based on the radio environment and propagation conditions.

[0085] In another embodiment, a message content used in the function may be a length indicator. For example, 3GPP RRC protocol makes use of octet aligned encodings where a payload may be, for example, contained as an octet string such as a Non-Access Stratum (NAS) container for the transfer of small data upon random access. The contained octet string may include a length indicator in terms of octets. In the present disclosure, the length indicator may indicate a length of the remaining of the payload (e.g., information element), i.e., the number of octets between the end of the Length Indicator field included in the information element and the end of the last octet in the information element. The length indicator may create randomization among different applications that are exchanging data because different applications most likely use different payload sizes.

[0086] In another embodiment, a message content may be a transaction identity. One example of such a transaction identity is 3GPP radio resource control protocol or Non-Access Stratum (NAS) control-plane message transaction identity.

[0087] <System Parameter Used in the Function> In another embodiment, a system parameter used in the function may be a System Frame Number (SFN), e.g. as used in 3GPP radio interface deployments for numbering the radio frames . For example, the 3GPP radio interface SFN may count from 0 to 1023 which ensures that the randomization is different at different points of time. A variant of the embodiment may be to use a Hyper Frame Number (HFN) which is applied for numbering sets of SFNs. The SFNs and HFNs may also be combined with an arithmetic operation, e.g. adding them together. The SFN or HFN, or combination of thereof, may create randomization over time thus preventing the transmitter to use the same sub-frames for every random access.

[0088] In another embodiment, a system parameter may be a cell identity such as used in 3GPP radio network deployments for identifying cell sites, i.e., receivers in this case. In the present disclosure, the cell identity may be a physical cell identity, a virtual cell identity, or the other information used to specify a cell. If neighbouring cells are allocated different cell identities, the parameter may create randomization based on the transmitter’s physical location.

[0089] In another embodiment, a system parameter may be a beam identity of transmitter or receiver, or beam identities of transmitter and receiver (i.e., a beam pair), such as used in 3GPP radio network interfaces for identifying beams in advanced antenna system deployments. In the present disclosure, the beam identity may be considered equivalent to information on at least one of the following: a spatial relation, Transmission Configuration Indicator (TCI) state, Quasi-Co-Location (QCL), precoding, precoder, a spatial domain filter, and a panel. If neighbouring beams are allocated different beam identities, the parameter may create randomization based on the transmitter’s physical location.

[0090] In another embodiment, a system parameter may be the device capability such as supported band combinations and power classes as used in 3GPP radio interfaces. In general, different devices may make use of different band combinations which may create randomizations based on implementations. The capabilities may be reported from the transmitting side (the UE) to the receiving side (the network). The capabilities may be known by both sides of the interface based on the device identity.

[0091] In another embodiment, a system parameter may be a system information field provided by the receiving side. For example, 3GPP radio interfaces (the network) can broadcast a data volume threshold in system information to control the data volume that is permitted to trigger a small data transmission, i.e. transmission of small data within one transport block, upon random access and access requests. In the present disclosure, the system information field may be a field (e.g., sdt-DataVolumeThreshold-r17) that indicate a data volume threshold used to determine whether a small data transmission can be initiated and the field may be transmitted to the terminal by system information block 1 (SIB1). If the parameter value is adapted to traffic conditions, it may create randomization based on time-varying traffic.

[0092] In another embodiment, a system parameter may be the value of time advance. For example, 3GPP radio interface supports adjustments of time advance during random access to compensate propagation delays. The value may be known by both transmitting and receiving sides and it may provide randomization based on propagation delays.

[0093] <Other Information Used in the Function) In another embodiment, information used in the function may be time information which can be, for example, combined with one or more information from other embodiments above to prevent collisions. For example, this could be absolute time corresponding to the transmission of a message. In an example, second value is used. One or more values of hours, minutes or seconds of the time may be used as the time information. In an example, unit corresponding to decaseconds, i.e. 10 seconds, may be used. The relative time (e.g., epoch time) from a reference time may be used as the time information.

[0094] In another embodiment, information used in the function may be geographical information which can be, for example, combined with one or more information from other embodiments above to prevent collisions. For example, this could be the geographical location of the transmitting or receiving node.

[0095] <Supplement> In another embodiment, at least one of a content of the message, system parameters and / or the other information may be used either entirely or partially, e.g. the most or least significant bits, as an operand or input in the function, for example, as a seed value, multiplicator, or increment in a linear congruential generator or in a lookup table and / or function to compute entries of a data structure, e.g., as an index in a list or table, or as a key in a key-value pair.

[0096] In another embodiment, the subframe numbers, which may be generated at each side via some of the embodiments above, or generated at each side as from the state-of-the-art, may be only appended into some of the replicas. In one example the pseudo-random numbers, or subframe numbers, that were previously appended into some other replicas may be re-used. For example, a first set of replica(s) may include the random number(s) or frame number(s), and a rule would be defined where a second set of replicas do not include the random number(s) or frame number(s).

[0097] In another embodiment, none of replicas may include any sub-frame numbers.

[0098] In another embodiment, the rule to use to derive new subframe numbers associated with future replicas may be provided from the transmitter to the receiver. This rule may make use of a formula, which may include multiplication and addition for example. Information on the rule may be transmitted from the receiver to the transmitter, and the vice versa.

[0099] In another embodiment, the generated sub-frame numbers of the replicas may be represented by absolute sub-frame numbers or relative sub-frame numbers (e.g., sub-frame offsets from one of replicas or reference sub-frame).

[0100] In another embodiment, the number of replicas may be the same for two or more nodes. In another embodiment, the number of replicas may be different for two or more nodes.

[0101] In another embodiment, the number of replicas may be the same for two or more messages of each node. In another embodiment, the number of replicas may be different for two or more messages of each node.

[0102] In some embodiments, replicas may be transmitted on at least one of a Physical Random Access Channel (PRACH), a Physical Uplink Shared Channel (PUSCH), a Physical Uplink Control Channel (PUCCH), and any other channels.

[0103] The present disclosure may disclose a method and apparatus for Pseudo Random Contention Resolution Diversity Slotted ALOHA (PR-CRDSA) where the inventive step is to make use of pseudo random numbers computed from the message content and / or system parameters and / or the other information. It means that random access may be triggered without the need for adding sub-frame numbers for replicas and without making a distinction between ordinary DSA and Contention Resolution DSA. The benefits may be that the signalling overhead may be reduced, and the receiver implementation may become transparent to the transmitter, i.e. the transmitter behaviour may be always the same regardless how the receiver is implemented.

[0104] (Supplementary Notes) Regarding embodiments of the present disclosure, the following supplementary notes are given. <Supplementary Note 1> A terminal comprising: a processor configured to determine, based on a function using specific information, a plurality of numbers for identifying periods for transmitting a plurality of replicas of a message; and a transmitter configured to transmit the plurality of replicas in a plurality of periods, wherein each of the plurality of periods is associated with a respective one of the determined plurality of numbers, without appending information explicitly indicating any of the determined plurality of numbers to any of the plurality of replicas. <Supplementary Note 2> The terminal according to supplementary note 1, wherein the specific information includes a content of the message. <Supplementary Note 3> The terminal according to any one of supplementary notes 1 to 2, wherein the content of the message is a unique user identity. <Supplementary Note 4> The terminal according to any one of supplementary notes 1 to 3, wherein the content of the message is a value indicating a cause regarding connection. <Supplementary Note 5> The terminal according to any one of supplementary notes 1 to 4, wherein the specific information includes a system parameter. <Supplementary Note 6> The terminal according to any one of supplementary notes 1 to 5, wherein the system parameter is a System Frame Number (SFN). <Supplementary Note 7> The terminal according to any one of supplementary notes 1 to 6, wherein the system parameter is a cell identity. <Supplementary Note 8> The terminal according to any one of supplementary notes 1 to 7, wherein the specific information includes other information than a content of the message and a system parameter. <Supplementary Note 9> The terminal according to any one of supplementary notes 1 to 8, wherein the other information is time information. <Supplementary Note 10> The terminal according to any one of supplementary notes 1 to 9, wherein the other information is geographical information. <Supplementary Note 11> A method performed by a terminal, the method comprising: determining, based on a function using specific information, a plurality of numbers for identifying periods for transmitting a plurality of replicas of a message; and transmitting the plurality of replicas in a plurality of periods, wherein each of the plurality of periods is associated with a respective one of the determined plurality of numbers, without appending information explicitly indicating any of the determined plurality of numbers to any of the plurality of replicas. <Supplementary Note 12> A base station comprising: a receiver configured to receive at least one replica of a message from a terminal; and a processor configured to determine, based on a function using specific information, a plurality of numbers for identifying periods where other replicas of the message are transmitted. <Supplementary Note 13> A communication system comprising: a terminal according to any one of supplementary notes 1 to 10; and a base station according to supplementary note 12.

[0105] (Variations) Embodiments in the present disclosure may be used for any 3GPP radio access technologies, for example, 3GPP 4G technology referred to as Long Term Evolution (LTE), 3GPP 5G technology referred to as New Radio (NR) or future 3GPP radio technology generations such as 6G. While the examples in the present disclosure relate to 3GPP technologies, embodiments in the present disclosure could be used for non-3GPP technologies, for example, Bluetooth, IEEE and its 802.11 variants, Wi-Fi, WiMAX, etc.

[0106] In the present disclosure, any signals (e.g., for indication, configuration and notification of some information) from a node to another node may be transmitted using any one or combinations of Radio Resource Control (RRC) layer signaling, Medium Access Control (MAC) layer signaling, and physical (PHY) layer signaling, even if not explicitly stated.

[0107] The RRC layer signaling may be an RRC message or an RRC information element. The MAC layer signaling may be a MAC control element (MAC CE) or a MAC Protocol Data Unit (PDU). The PHY layer signaling may be downlink control information (DCI), uplink control information (UCI), or sidelink control information (SCI).

[0108] Any parameters, values and information in the present disclosure may be indicated from a node to another node, even if not explicitly stated. In the present disclosure, “X” and “information on X” may be used interchangeably.

[0109] In the present disclosure, a time unit for radio communication may be replaced with (or interchangeably used as) another time unit for radio communication. For example, a radio frame, a subframe, a slot, a sub-slot, and a symbol all express time units for radio communication.

[0110] As used in the present disclosure, use of the term “or” in a list of items indicates an inclusive list. The list of items may be prefaced by a phrase such as “at least one of” or “one or more of.” For example, a list of at least one of A, B, or C includes A or B or C or AB (i.e., A and B) or AC or BC or ABC (i.e., A and B and C). Also, as used in the present disclosure, prefacing a list of conditions with the phrase “based on” shall not be construed as “based only on” the set of conditions and rather shall be construed as “based at least in part on” the set of conditions. For example, an outcome described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure.

[0111] In the present disclosure, the terms “comprise,” “include,” or “contain” may be used interchangeably and have the same meaning and are to be construed as inclusive and open-ended. The terms “comprise,” “include,” or “contain” may be used before a list of elements and indicate that at least all of the listed elements within the list exist but other elements that are not in the list may also be present. For example, if A comprises B and C, both {B, C} and {B, C, D} are within the scope of A.

[0112] The present disclosure, in connection with the accompanied drawings, describes example configurations that are not representative of all the examples that may be implemented or all configurations that are within the scope of the present disclosure. The term “exemplary” should not be construed as “preferred” or “advantageous compared to other examples” but rather “an illustration, an instance or an example.” By reading the present disclosure, including the description of the embodiments and the drawings, it will be appreciated by a person of ordinary skills in the art that the technology disclosed herein may be implemented using alternative embodiments. The person of ordinary skill in the art would appreciate that the embodiments, or certain features of the embodiments described herein, may be combined to arrive at yet other embodiments for practicing the technology described in the present disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

[0113] The flowcharts and block diagrams in the figures illustrate examples of the architecture, functionality, and operation of possible implementations of systems, methods, and devices according to various embodiments. It should be noted that, in some alternative implementations, the functions noted in blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Likewise, additional steps may be included in such methods, and certain steps may be omitted or combined, in methods consistent with various embodiments.

[0114] It is understood that the described embodiments are not mutually exclusive, and elements, components, materials, or steps described in connection with one example embodiment may be combined with, or eliminated from, other embodiments in suitable ways to accomplish desired design objectives. Any embodiment (two or more) used in the present disclosure may be used in combination.

[0115] Reference herein to “some embodiments” or “some exemplary embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment. The appearance of the phrases “one embodiment,” “some embodiments” or “another embodiment” in various places in the present disclosure do not all necessarily refer to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. In the present disclosure, “an / one embodiment,” “(some) embodiments” and “another embodiment” may be used interchangeably.

[0116] The articles “a” and “an” as used in the present disclosure and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.

[0117] Unless explicitly stated otherwise, each numerical value and range in the present disclosure may be interpreted as being approximate as if the word “about” or “approximately” preceded the value of the value or range.

[0118] The term "connected" or any variation of the terms as used in the present disclosure mean all direct or indirect connections between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" to each other. The connection between the elements may be physical, logical, or a combination thereof. For example, "connection" may be interpreted as "access."

[0119] Although the elements in the following method claims, if any, are recited in a particular sequence, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

[0120] It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination or as suitable in any other described embodiment of the present disclosure. Certain features described in the context of various embodiments are not essential features of those embodiments, unless noted as such.

[0121] It will be further understood that various modifications, alternatives, and variations in the details, materials, and arrangements of the parts which have been described and illustrated in order to explain the nature of described embodiments may be made by those skilled in the art without departing from the scope. Accordingly, the following claims embrace all such alternatives, modifications, and variations that fall within the terms of the claims.

Claims

1. A terminal comprising: a processor configured to determine, based on a function using specific information, a plurality of numbers for identifying periods for transmitting a plurality of replicas of a message; and a transmitter configured to transmit the plurality of replicas in a plurality of periods, wherein each of the plurality of periods is associated with a respective one of the determined plurality of numbers, without appending information explicitly indicating any of the determined plurality of numbers to any of the plurality of replicas.

2. The terminal according to claim 1, wherein the specific information includes a content of the message.

3. The terminal according to claim 2, wherein the content of the message is a unique user identity.

4. The terminal according to claim 2, wherein the content of the message is a value indicating a cause regarding connection.

5. The terminal according to claim 1, wherein the specific information includes a system parameter.

6. The terminal according to claim 5, wherein the system parameter is a System Frame Number (SFN).

7. The terminal according to claim 5, wherein the system parameter is a cell identity.

8. The terminal according to claim 1, wherein the specific information includes other information than a content of the message and a system parameter.

9. The terminal according to claim 8, wherein the other information is time information.

10. The terminal according to claim 8, wherein the other information is geographical information.

11. A method performed by a terminal, the method comprising: determining, based on a function using specific information, a plurality of numbers for identifying periods for transmitting a plurality of replicas of a message; and transmitting the plurality of replicas in a plurality of periods, wherein each of the plurality of periods is associated with a respective one of the determined plurality of numbers, without appending information explicitly indicating any of the determined plurality of numbers to any of the plurality of replicas.

12. A base station comprising: a receiver configured to receive at least one replica of a message from a terminal; and a processor configured to determine, based on a function using specific information, a plurality of numbers for identifying periods where other replicas of the message are transmitted.

13. A communication system comprising: a terminal according to any one of claims 1 to 10; and a base station according to claim 12.

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