CN112889229B

CN112889229B - Spreading of signatures for multiple access techniques

Info

Publication number: CN112889229B
Application number: CN201880098137.1A
Authority: CN
Inventors: E·法拉格; 张元涛; 朴景敏
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2018-09-28
Filing date: 2018-09-28
Publication date: 2023-01-13
Anticipated expiration: 2038-09-28
Also published as: WO2020062104A1; CN112889229A

Abstract

Embodiments of the present disclosure provide methods, apparatuses, and computer-readable media for communication. In a method implemented at a terminal device, the terminal device determines a first number of slots of a data transmission to be performed by the terminal device. The terminal device determines a signature pattern from a plurality of candidate signature patterns, each candidate signature pattern comprising a sequence of a second number of signatures, the second number being greater than or equal to the first number. The terminal device performs data transmission in a first number of time slots using the determined signature pattern. Embodiments of the present disclosure may support large multiple access capacities without full collisions over multiple timeslots.

Description

Spreading of signatures for multiple access techniques

Technical Field

Embodiments of the present disclosure relate generally to wireless communications, and in particular to spreading of signatures for multiple access techniques (e.g., non-orthogonal multiple access (NOMA) techniques).

Background

Non-orthogonal multiple access (NOMA) is an ongoing research project in 3GPP release 16. In NOMA, multiple terminal devices share the same time-frequency resource using non-orthogonal signatures. The use of non-orthogonal signatures increases the available number of signatures and therefore more terminal devices can be supported, but also introduces Multiple Access Interference (MAI), which requires the use of advanced receivers to distinguish terminal devices and obtain good performance. NOMA may be used in both unlicensed and grant-based transmissions. In case of unauthorized transmission, the terminal device may be configured with a signature, or the signature may be randomly selected from a pool of signatures.

However, the number of available signatures in conventional multiple access schemes is still typically limited compared to a potentially large number of terminal devices, especially in the NOMA scheme, which means that these multiple access schemes may have limited capacity and/or a high collision rate, and therefore the performance of the multiple access scheme may be poor if the number of terminal devices is large.

Disclosure of Invention

In general, example embodiments of the present disclosure provide methods, apparatus, and computer-readable media for communication, and in particular for extension of signatures in multiple access systems.

In a first aspect, a method implemented at a terminal device is provided. The method includes determining a first number of time slots for data transmission to be performed by a terminal device. The method also includes determining a signature pattern from a plurality of candidate signature patterns, each candidate signature pattern comprising a sequence of a second number of signatures, the second number being greater than or equal to the first number. The method also includes sequentially performing data transmission in a first number of slots using a first number of signatures in the determined signature pattern.

In a second aspect, a method implemented at a network device is provided. The method includes receiving a data transmission from a terminal device in a first number of time slots. The method also includes determining a signature pattern from the data transmission, the determined signature pattern being from a plurality of candidate signature patterns, each candidate signature pattern comprising a sequence of a second number of signatures, the second number being greater than or equal to the first number. The method further comprises distinguishing a data transmission of the terminal device from another data transmission of another terminal device using the determined signature pattern.

In a third aspect, a terminal device is provided. The terminal device includes at least one processor and at least one memory storing computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device to determine a first number of time slots for a data transmission to be performed by the terminal device. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to determine a signature pattern from a plurality of candidate signature patterns, each candidate signature pattern comprising a sequence of signatures of a second number, the second number being greater than or equal to the first number. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to sequentially perform data transmission in a first number of time slots using a first number of signatures in the determined signature pattern.

In a fourth aspect, a network device is provided. The network device includes at least one processor and at least one memory storing computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the network device to receive a data transmission from a terminal device in a first number of time slots. The at least one memory and the computer program code are also configured to, with the at least one processor, cause the network device to determine a signature pattern from the data transmission, the determined signature pattern being from a plurality of candidate signature patterns, each candidate signature pattern comprising a sequence of a second number of signatures, the second number being greater than or equal to the first number. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the network device to distinguish a data transmission of the terminal device from another data transmission of another terminal device using the determined signature pattern.

In a fifth aspect, a computer-readable medium having instructions stored thereon is provided. The instructions, when executed on at least one processor of a device, cause the device to perform the method according to the first aspect.

In a sixth aspect, a computer-readable medium having instructions stored thereon is provided. The instructions, when executed on at least one processor of a device, cause the device to perform a method according to the second aspect.

It should be understood that this summary is not intended to identify key or essential features of the embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become readily apparent from the following description.

Drawings

The foregoing and other objects, features, and advantages of the disclosure will be apparent from the following more particular description of some embodiments of the disclosure, as illustrated in the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a communication environment in which embodiments of the present disclosure may be implemented;

fig. 2 illustrates a flow diagram of an example method according to some embodiments of the disclosure;

fig. 3 is a schematic diagram illustrating dynamic multi-slot data transmission by a terminal device, in accordance with some embodiments of the present disclosure;

fig. 4 is a schematic diagram illustrating that a terminal device may transmit in a non-aligned starting time slot, according to some embodiments of the present disclosure;

FIG. 5 is a graph illustrating probability of collision as a function of the number of signatures in a signature pattern according to some embodiments of the present disclosure;

fig. 6 shows a flow diagram of an example method according to some other embodiments of the present disclosure; and

fig. 7 is a simplified block diagram of a device suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numbers refer to the same or similar elements.

Detailed Description

The principles of the present disclosure will now be described with reference to some exemplary embodiments. It is understood that these examples are described solely for the purpose of illustration and to assist those skilled in the art in understanding and practicing the disclosure, and are not intended to suggest any limitation as to the scope of the disclosure. In addition to the manner described below, the disclosure described herein may be implemented in a variety of other ways.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

As used herein, the term "network device" or "base station" (BS) refers to a device that is capable of providing or hosting a cell or coverage area in which a terminal device may communicate. Examples of network devices include, but are not limited to, node bs (NodeB or NB), evolved nodebs (eNodeB or eNB), next generation nodebs (gNB), remote Radio Units (RRUs), radio Heads (RH), remote Radio Heads (RRH), low power nodes (such as femto nodes, pico nodes), and so forth. For purposes of discussion, some embodiments will be described below with reference to an eNB or a gNB as an example of a network device.

As used herein, the term "terminal device" refers to any device having wireless or wired communication capabilities. Examples of terminal devices include, but are not limited to, user Equipment (UE), personal computers, desktop computers, mobile phones, cellular phones, smart phones, personal Digital Assistants (PDAs), portable computers, image capture devices such as digital cameras, gaming devices, music storage and playback devices, or internet devices that enable wireless or wired internet access and browsing functionality, among others. For purposes of discussion, some embodiments will be described below with reference to a UE as an example of a terminal device, and the terms "terminal device" and "user equipment" (UE) may be used interchangeably within the context of the present disclosure.

The term "circuitry" as used herein may refer to one or more or all of the following: (a) Hardware-only circuit implementations (such as implementations in analog and/or digital circuitry only), and (b) combinations of hardware circuitry and software, such as (if applicable): (i) A combination of analog and/or digital hardware circuitry and software/firmware, and (ii) a hardware processor with software (including a digital signal processor), any portion of software and memory that work together to cause an apparatus (such as a mobile telephone or server) to perform various functions, and (c) hardware circuitry and/or a processor, such as a microprocessor or a portion of a microprocessor, that requires software (e.g., firmware) for operation but which may not be present when operation is not required.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As another example, as used in this application, the term "circuitry" also encompasses only a portion of an implementation of a hardware circuit or processor (or multiple processors) or a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also encompasses (e.g., and where applicable to the particular claim element) a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "comprising" and variants thereof is to be understood as an open term meaning "including but not limited to". The term "based on" should be understood as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". The terms "first," "second," and the like may refer to different or the same objects. Other definitions (explicit and implicit) may be included below.

In some examples, a value, process, or device is referred to as "optimal," "lowest," "highest," "minimum," "maximum," or the like. It should be understood that such descriptions are intended to indicate that a selection may be made among many functional alternatives used, and that such selections need not be better, smaller, higher, or otherwise more preferred than other selections.

Fig. 1 is a schematic diagram of a communication environment 100 in which embodiments of the present disclosure may be implemented. Communication environment 100 may include a network device 110 that provides wireless connectivity to a plurality of

terminal devices

120, 130, and 140 within its coverage area.

Terminal devices

120, 130, and 140 may communicate with network device 110 via

wireless transmission channels

115, 125, and 135, respectively. In addition,

end devices

120, 130, and 140 may communicate with each other via device-to-device (D2D) links (not shown in fig. 1).

In some embodiments, the

wireless transport channels

115, 125 and 135 may be carried by a common physical channel such as the Physical Uplink Shared Channel (PUSCH) defined in the 3GPP specifications. In this case, the

terminal devices

120, 130, and 140 may access the common physical channel using a multiple access scheme such as NOMA. If the NOMA scheme is used, the

terminal devices

120, 130 and 140 may transmit in the same time-frequency resource, but with different signatures, so that the network device 110 as a receiving device may distinguish between transmission data from different terminal devices.

As described above, the signatures in the NOMA scheme are not orthogonal to each other. As used herein, depending on the details of the NOMA scheme, the signature may be, but is not limited to, a spreading sequence, an interleaver pattern, a codebook, a DMRS pattern/sequence, etc. It should be noted that although the present disclosure may be described below primarily based on the NOMA scheme, embodiments of the present disclosure may also be applicable to other possible multiple access schemes, such as FDMA, TDMA, CDMA, and SDMA schemes.

It should be understood that the number of network devices and the number of terminal devices as shown in fig. 1 are for illustrative purposes only and do not present any limitations. Communication environment 100 may include any suitable number of network devices and any suitable number of terminal devices suitable for implementing embodiments of the present disclosure. In addition, it should be understood that various wireless as well as wired communications may exist (if desired) between these additional network devices and additional terminal devices.

Communications in communication environment 100 may conform to any suitable standard including, but not limited to, global system for mobile communications (GSM), extended coverage global system for mobile internet of things (EC-GSM-IoT), long Term Evolution (LTE), LTE evolution, LTE advanced (LTE-a), wideband Code Division Multiple Access (WCDMA), code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), and so on.

Further, communications in communication environment 100 may be performed according to any generation of communication protocols currently known or to be developed in the future. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, and fifth generation (5G) communication protocols.

As an illustrative example, the various example implementations or techniques described herein may be applied to various terminal devices, such as Machine Type Communication (MTC) terminal devices, enhanced machine type communication (eMTC) terminal devices, internet of things (IoT) terminal devices, and/or narrowband IoT terminal devices.

An IoT may refer to an ever-increasing group of objects that may have internet or network connectivity, such that these objects may send information to and receive information from other network devices. For example, many sensor type applications or devices may monitor physical conditions or states and may send reports to a server or other network device, for example, upon the occurrence of an event. Machine type communication (MTC or machine-to-machine communication) may be characterized by fully automatic data generation, exchange, processing, and actuation between intelligent machines with or without human intervention.

Also, in an example implementation, the terminal device or UE may be a UE/terminal device with a URLLC application. One or more cells may include a plurality of terminal devices connected to the cell, including different types or classes of terminal devices, including MTC, NB-IoT, URLLC classes, or other UE classes, for example.

Various example implementations may be applied to a wide variety of wireless technologies or wireless networks, such as LTE, LTE-a, 5G, cmWave, and/or mmWave band networks, ioT, MTC, eMTC, URLLC, etc., or any other wireless network or wireless technology. These example networks or technologies are provided merely as illustrative examples, and various example implementations may be applied to any wireless technology/wireless network.

Through research into conventional solutions for multiple access, the inventors have found that the number of signatures provided by conventional multiple access schemes may be too small to support a large number of terminal devices. For example, consider a multiple access system with N terminal devices and M signatures available in a time slot, where a time slot may be defined as the period during which a terminal device may randomly select a signature and transmit dataA time interval. In case the signatures are pre-configured and N > M, each or some of the signatures may be assigned to more than one terminal device, i.e. to N terminal devices, wherein

Or

Consider a poisson distribution where the average number of terminal devices transmitting in a certain time slot is λ, λ being much smaller than 1. For simplicity, assume that

Probability of terminal equipment not transmitting in a certain time slot is represented by e ^-λ It is given. In case the terminal device selects a signature and the remaining n-1 terminal devices assigned to this signature do not transmit, the probability is derived that the terminal device does not collide with another terminal device. The probability is represented by (e) ^-λ ) ^n-1 It is given. Thus, the collision probability is represented by 1- (e) ^-λ ) ^n-1 It is given. It can be seen that as the number of terminal devices increases, the probability of collision increases greatly.

In addition, some contributions of the radio access network 1 (RAN 1) have recently been proposed for configured authorization in 3GPP release 15. The inventors have noted that the configured grant according to 3GPP release 15 considers repeated transmissions to improve the reliability of the transmission, but fails to extend the limited number of signatures for multiple access techniques with repeated transmissions. In particular, conventional multiple access schemes do not feature multiple access signature patterns over repeated transmissions.

In view of the above, embodiments of the present disclosure propose methods, apparatuses, and computer readable media for communication, in particular for the extension of signatures in multiple access systems. According to an embodiment of the present disclosure, a terminal device may perform data transmission on a plurality of slots, and may use an individual signature in each slot. In this way, considering a plurality of time slots as a whole, available signature patterns can be created from various permutations of individual signatures. Thus, the number of available signature patterns may be much larger than the number of individual signatures, so that the overall probability of transmission collisions between terminal devices may be reduced. With embodiments of the present disclosure, large multiple access capacity may be supported without full collisions over multiple timeslots. Hereinafter, some embodiments according to the present disclosure will be described in detail with reference to fig. 2 to 7.

Fig. 2 illustrates a flow diagram of an example method 200 in accordance with some embodiments of the present disclosure. Method 200 may be implemented at a terminal device, such as

terminal devices

120, 130, and 140 shown in fig. 1. For discussion purposes, the method 200 will be described with reference to fig. 1, and without loss of generality, the method 200 will be described as being performed by the terminal device 120. It should be understood that method 200 may also be performed by

terminal devices

130 and 140 and other terminal devices not shown in fig. 1.

At block 210, the terminal device 120 determines a first number of time slots for data transmission to be performed by the terminal device 120. Terminal device 120 may determine the first number of time slots in a variety of ways. In some embodiments, terminal device 120 may transmit a measurement report to network device 110, which may reflect the link quality from terminal device 120 to network device 110. Network device 110 may determine the first number of time slots for terminal device 120 based on the measurement report. In this way, the number of time slots used for data transmission may be adjusted based on the link quality.

For example, if the measurement report indicates that the link quality is not good, the network device 110 may configure the first number to a relatively large number so that the terminal device 120 may perform data transmission a plurality of times in the first number of slots to improve the reliability of the data transmission. On the other hand, if the link quality is good, network device 110 may configure the first number to a relatively small number to conserve transmission resources. After determining the first number based on the measurement report, network device 110 may send the first number to terminal device 120, and terminal device 120 may accordingly receive the first number from network device 110.

In some other embodiments, terminal device 120 may select the first number from a plurality of predetermined numbers. In other words, the first number may be dynamically determined by the terminal device 120 from a plurality of predetermined numbers. In this case, in order to help the network device 110 as a receiving device determine the number of slots used by the terminal device 120 as a transmitting device, respective DMRS sets may be defined for a plurality of predetermined number of slots. That is, each of a predetermined number of the plurality of predetermined numbers of slots is associated with a respective DMRS set. For example, if the first number has two possible values and the two values are associated with two DMRS sets, respectively, then the terminal device 120 may switch between the two DMRS sets when transposing between the first number of two possible values. This is further explained with reference to fig. 3.

Fig. 3 is a diagram 300 illustrating dynamic multi-slot data transmission by terminal device 120, according to some embodiments of the present disclosure. As shown in fig. 3, the first row of blocks (e.g., block 305) represents a time slot. For the first number there are two possible values, i.e. the terminal device 120 may swap between three and two time slots when performing several instances of data transmission. It is to be understood that the specific number of slots (three and two) used herein is only one example and does not set any limit to the present disclosure. In other embodiments, any other suitable number of time slots may be used for data transmission.

In the illustrated example, the terminal device 120 performs four

instances

330, 340, 350, and 360 of data transmission using three slots, two slots, three slots, and two slots, respectively. As shown, data transmission using three slots is associated with DMRS set 0, and data transmission using two slots is associated with DMRS set 1. In this way, at the network device 110, which is the receiving device, the detection of a new DMRS set indicates the start of a new data transmission from the terminal device 120. It is to be understood that the above-described association between a particular DMRS set and a particular number of slots for data transmission is only an example and does not set any limit to the present disclosure. In other embodiments, other suitable associations with any DMRS set and any number of slots of a data transmission are possible. The key is to switch the DMRS set at every new transmission.

Referring again to fig. 2, at block 220, terminal device 120 determines a signature pattern from a plurality of candidate signature patterns. The signature pattern will be used to perform the data transmission such that the network device 110 can distinguish the data transmission from other data transmissions that share the same time-frequency resources. To this end, each candidate signature pattern comprises a sequence of a second number of signatures. In other words, the candidate signature pattern may be a plurality of signatures arranged in a particular order.

As described above, in some embodiments, the signature may include a spreading sequence, an interleaver pattern, a codebook, and a DMRS pattern or sequence, among others. In some other embodiments, the signature may be any other suitable means that enables a receiver (e.g., network device 110 as shown in fig. 1) to distinguish data transmissions of terminal device 120 from other data transmissions of another terminal device, such as

terminal devices

130 and 140.

In some embodiments, the second number of signatures in the candidate signature pattern may be configured based on the number of terminal devices that are to use the candidate signature pattern (i.e. the number of terminal devices sharing the same transmission resources), an estimated traffic arrival rate of one of the terminal devices, or other possible parameters. The reason is that the larger the second number, the more different signature patterns are available. In this way, the number of available signature patterns may be adapted to the number and characteristics of the relevant terminal devices.

In some embodiments, the second number is equal to the first number of time slots for performing the data transmission, which means that there is a one-to-one correspondence between individual signatures in one signature pattern and individual time slots for data transmission. As a simple example for demonstration, consider a set of three available signatures, represented by { A, B, C }. Data transmission is performed over beta slots. That is, the first number is represented by β, and it is assumed that the second number is equal to the first number β =3. Then, the set of all possible signature patterns on these three slots is { AAA, AAB, AAC, ABA, ABB, ABC, ACA, ACB, ACC, BAA, BAB, BAC, BBA, BBB, BBC, BCA, BCC, CAA, CAB, CAC, CBA, CBB, CBC, CCA, CCB }.

In other words, there are a total of 27 available signature patterns. In case all 27 available signature patterns are used as candidate signature patterns, the minimum number of signatures that differ at corresponding positions is 1 if two different signature patterns are selected by two terminal devices. For example, if terminal device 120 selects signature mode "AAA" and terminal device 130 selects signature mode "AAB", only the signature for the third location is different. This may negatively affect the quality of the data communication, since the signatures of the two terminal devices collide in the two time slots.

To improve the quality of the data communication, a subset of the 27 signature patterns may be selected as candidate signature patterns such that any two different signature patterns from the subset differ at more than one corresponding position. In other words, when signature patterns are used to perform data transmission, the available signature patterns are limited in order to maximize the number of slots in which the signatures between any two signature patterns differ.

For example, such a subset may be ABC, BCA, CAB, and when two terminal devices select different signature patterns from the subset, all three locations have different signatures. In this way, when data transmission is performed using such subsets, a different signature may be used for each particular terminal device in each time slot. However, for this example subset, the number of available signature patterns is three, which is equal to the number of available signatures. Thus, the cardinality of the signature pattern subset is not increased.

As an intermediate alternative, a subset of signature patterns may be selected from all 27 signature patterns as candidate signature patterns, such that any two signature patterns in the subset differ in at least two corresponding positions. An example of such a subset may be { ABA, BCA, CAA, ACB, BAB, CBB, AAC, BBC, CCC }. It can be seen that any two elements in the subset differ in at least two positions. An alternative possible subset may be { AAA, BBB, CCC, ABC, BCA, CAB, ACB, BAC, CBA }. In this way, the number of available signature patterns increases from three to nine.

It is to be understood that the specific number of signatures, time slots, and number of signatures available in a signature pattern are merely examples and do not set any limit to the scope of the present disclosure. In other embodiments, any other suitable number of available signatures, time slots, and number of signatures in a signature pattern may be employed.

More generally, an example is given here to illustrate how candidate signature patterns are determined from all possible signature patterns formed by available signatures. Let "M" be the number of available signatures, where M is assumed to be prime, and let "β" be the number of signatures in one signature pattern, such that β ≦ M. A subset of signature patterns may be constructed as candidate signature patterns such that any two signature patterns in the subset have at most "t" corresponding positions with the same signature. As an example, the parameter "t" may be two, i.e. any two candidate signature patterns have at most two identical signatures at corresponding positions. With this value, a balance can be struck between the number of signature patterns and the likelihood of signature collisions in the signature patterns.

Without loss of generality, for signature pattern g, where g =0 ^t+1 1, the signature used in the time slot "i" can be given by the following formula, where s =0.. Beta-1, the symbol "Permut ()" represents the permutation function, and the symbol "%" represents the modulus operator.

Table 1 below shows how the size of the signature pattern subsets as described above varies with the number of available signatures and the value of "t".

TABLE 1

The candidate signature patterns generated according to the above-described method may be pre-configured in the terminal device 120, e.g. stored in a memory of the terminal device 120. In this case, when determining the signature pattern from the candidate signature patterns to perform the data transmission, the terminal device 120 may select the signature pattern from the candidate signature patterns based on an identifier of the terminal device 120, a slot number of at least one slot of the first number of slots, and/or other possible parameters.

The identifier of the terminal device 120 may be an Identification (ID) configured by the communication network, an ID randomly selected by the terminal device 120, or an ID pre-assigned to the terminal device 120 (e.g., international mobile subscriber identity IMSI), or a combination thereof. In this way, the signature pattern may be determined by the terminal device itself, thereby saving communication resources between the terminal device 120 and the network device 110.

Alternatively, the candidate signature patterns may be stored in network device 110 instead of terminal device 120. In this case, network device 110 may configure the signature mode for terminal device 120. This applies primarily to Radio Resource Control (RRC) connected terminal devices. In other words, in determining the signature pattern, the terminal device 120 may receive an indication of the signature pattern from the network device 110: which signature pattern is selected by the network device 110 for the terminal device 120 from the candidate signature patterns. In this way, the terminal device 120 does not need to store the candidate signature patterns and does not need to perform an operation for determining the signature pattern, and thus the requirement on the terminal device 120 can be reduced.

In some embodiments, the second number of signatures in the signature pattern is greater than the first number of slots used for data transmission. This means that it may be assumed that the data transmission is performed in the second number of time slots to determine the length of the signature pattern, but that the terminal device 120 actually uses fewer (the first number of) time slots than the second number of time slots used for the data transmission. By way of example, referring again to fig. 3,

signature patterns

310 and 320 each include four signatures and thus may span four time slots. That is, in FIG. 3, the second number of signatures in the signature pattern is four, which is greater than the first number (three or two) of slots for the data transmission instances 330-360.

Additionally, for the last data transmission instance 360 in fig. 3, the network device 110 may rely on DTX detection of the DMRS in the first slot without the DMRS. Terminal device 120 can transmit a corresponding DMRS set with no data for one slot, and network device 110 can use DTX detection for the data. Alternatively, the terminal device 120 may send a special signature pattern on the data detectable by the network device 110.

In the case where the second number is greater than the first number, candidate signature patterns may be determined based on the first number. In particular, the signatures or signature patterns may be divided according to a first number. For example, for single slot transmission (first number = 1), terminal device 120 may use the first M ₁ And (4) signature. For a two-slot transmission (first number = 2), terminal device 120 may use the next M ₂ Signature to create M ₂ A signature pattern, wherein any two signature patterns differ at two corresponding locations. For three-slot transmission (first number = 3), terminal device 120 may use the next M ₃ A signature to give (M) ₃ ) ² A signature pattern, wherein any two signature patterns differ in at least two corresponding positions. For a first number with even larger values, a large number of partially overlapping signature patterns may be generated. In this way, for a first number with a large value, many signatures are not required.

Referring again to fig. 2, at block 230, the terminal device 120 sequentially performs data transmission in a first number of slots using a first number of signatures in the determined signature pattern. For example, if three time slots are used for data transmission and the determined signature pattern is "ABC", the terminal device 120 may use signature "a" in the first time slot, signature "B" in the second time, and signature "C" in the third time slot when performing data transmission.

If the second number of signatures in the determined signature pattern is greater than the first number of time slots used for data transmission. The terminal device 120 may use a second number of consecutive signatures of the second number of signatures. For example, if three slots are used for data transmission and the determined signature pattern is "ABCCA," the terminal device 120 may perform data transmission using the first three signatures, while the remaining signature "CA" may be used for the next data transmission. This is the case for

signature patterns

310 and 320 shown in fig. 3. In some other embodiments, the terminal device 120 may perform data transmission using the other three consecutive signatures.

It should be understood that the specific numbers and specific signature patterns are examples only, and do not set forth any limitations on the scope of the present disclosure. In other embodiments, any other suitable number and any other signature pattern may be employed.

In order to support data transmission by terminal devices with different starting slot index numbers and/or different number of slots, there may be a common starting slot in which all signature patterns start. To this end, in some embodiments, the terminal device 120 may initiate the determined signature pattern before the first number of time slots for data transmission such that the determined signature pattern starts at a time slot having a predetermined time slot number. A possible reason is that, for example, data transmission may start in any time slot. In this way, all signature patterns can start in the same time slot regardless of when the terminal device 120 starts data transmission. This is further described with reference to fig. 4.

Fig. 4 is a diagram 400 illustrating that terminal devices 120-140 may transmit in unaligned starting time slots according to some embodiments of the present disclosure. As an example, consider a subset of signature patterns { ABA, BCA, CAA, ACB, BAB, CBB, AAC, BBC, CCC }. As shown in fig. 4, terminal apparatus 120 uses signature pattern "ABA", terminal apparatus 130 uses signature pattern "ACB", and terminal apparatus 140 uses signature pattern "CBB".

The terminal device 120 executes four

data transmission instances

122, 124, 126 and 128 and starts data transmission in the first time slot. The terminal device 130 executes three data transmission instances 132, 134 and 136 and starts data transmission in the second time slot. The terminal device 140 executes three data transmission instances 142, 144 and 146 and starts data transmission in the third time slot. Note that each of the

terminal devices

120, 130, and 140 uses the same signature pattern for subsequent transmission instances. In other embodiments, each terminal device may also be caused to use a different sequence for subsequent transmission instances.

There may be two alternatives as to the timing of the data transmission on the first number of time slots. As a first alternative, in some embodiments, terminal device 120 may initiate data transmission in a time slot having a predetermined time slot number. That is, data transmissions on the first number of slots may be synchronized to start at the same slot boundary for all terminal devices. For example, if the time slots available for uplink transmission are consecutively numbered with an index "p". Data transmission of β slots may begin at slot p such that p is an integer multiple of β. This alternative introduces additional latency, since the data transmission will have to wait until slot p, which is a multiple of β.

As a second option, in some other embodiments, data transmission over β slots may be allowed to start at any slot and span β slots. In this case, the signature used in the time slot m is given by the following equation, where m = n, n +1,.. Cndot.. N + β -1, the symbol "Permut ()" denotes the permutation function, and the symbol "%" denotes the modulus operator.

In this case, although the terminal devices start at different time slots, the signature pattern is determined based on the absolute time slot number m, which allows the terminal devices having unique signature patterns starting at different time slots to coexist. It should be noted that the second alternative increases computational complexity at the receiver (e.g., network device 110) while reducing latency, as it may require multiple hypothesis tests using different starting time slots.

In some embodiments, while performing the data transmission, the terminal device 120 may repeat performing the data transmission in the first number of time slots. This is done to advantageously increase the reliability of the unlicensed transmission. If considered in multiple time slots (assuming β slots)Time slots), this repetition has two effects on the collision of signatures. The first effect is based on e in the probability equation ^-βλ Term, the probability of no transmission across β slots can be reduced.

A second effect is that as the number of slots used for data transmission increases, the number of available signatures also increases. Even though the increase may be greater than the increase in linearity and may provide better results, for simplicity it is assumed that the increase is linear. Therefore, the number of signatures per slot is inversely proportional to β. The probability of collision considering beta time slots is 1- (e) ^-βλ ) ^n/β-1 It is given.

Fig. 5 is a graph 500 illustrating probability of collision as a function of the number of signatures in a signature pattern, in accordance with some embodiments of the present disclosure. Line 510 in fig. 5 shows how the probability of collision changes with the second number (in this case, it is equal to the first number β). In this particular example shown in fig. 5, it is assumed that the average number of terminal devices transmitting in a time slot (denoted by λ) is 0.01, and the number of terminal devices assigned the same signature (denoted by n) is 10.

It can be seen that as the number of time slots aggregated for a single data transmission instance increases, the likelihood of collisions decreases. The reason is that there are fewer terminal devices assigned to each signature, which reduces the likelihood of two terminal devices colliding on the same signature.

In the above, it is described how to determine the signature pattern used by the terminal device 120 to perform data transmission. In addition to the signature patterns set forth herein, DMRS or preamble patterns may be available to terminal devices 120 for performing data transmission. Generally, DMRS or preamble is used for channel estimation and identification of terminal devices. There are different alternatives for the association of signature or signature pattern with DMRS/preamble.

As a first alternative, in some embodiments, terminal device 120 may associate each signature with a unique demodulation reference signal (DMRS) or preamble. That is, there is a one-to-one correspondence between signatures and DMRSs/preambles. In this alternative, when signatures in a time slot collide, there is also a collision of DMRS/preambles in the same time slot. If one of the colliding terminal devices (e.g., terminal device 120) is decodable, the signal from terminal device 120 may be reconstructed (assuming the channel is sufficiently fixed over β slots for data transmission) due to transmissions on the other non-colliding slots and thus may be cancelled from the DMRS/preamble and data signal in the colliding slots in favor of the other colliding terminal devices (e.g., terminal devices 130 and 140).

As a second alternative, in some embodiments, the terminal device 120 may associate each candidate signature pattern with a unique DMRS or preamble. In other words, there is a one-to-one correspondence between signature patterns and DMRSs/preambles. In this alternative, each signature pattern has its unique DMRS/preamble. This has the following advantages: channel estimation and detection for each terminal device may be done independently of whether certain signatures collide in certain time slots. On the other hand, this requires a significant increase in the number of unique preamble/DMRS ports.

As a third alternative, in some other embodiments, the terminal device 120 may associate a set of candidate signature patterns of the plurality of candidate signature patterns with the same DMRS or preamble. This is a hybrid solution of the first and second alternatives, such that signature pattern groups are associated with the same DMRS/preamble.

Fig. 6 shows a flowchart of an example method 600 according to some other embodiments of the present disclosure. Method 600 may be implemented at a network device, such as network device 110 shown in fig. 1. For discussion purposes, method 600 will be described with reference to fig. 1, and method 600 will be described as being performed by network device 110. It should be understood that method 600 may also be performed by other network devices not shown in fig. 1.

At block 610, network device 110 receives a data transmission from terminal device 120 in a first number of time slots.

At block 620, network device 110 determines a signature pattern from the data transmission. The determined signature pattern is from a plurality of candidate signature patterns. Each candidate signature pattern comprises a sequence of a second number of signatures. The second number is greater than or equal to the first number.

At block 630, the network device 110 distinguishes a data transmission of the terminal device 120 from another data transmission of another terminal device 130 using the determined signature pattern.

In some embodiments, network device 110 may determine the signature pattern of terminal device 120, as described above. To this end, network device 110 may select a signature pattern for terminal device 120 from a plurality of candidate signature patterns. Network device 110 may then transmit an indication of the signature mode to terminal device 120 to perform the data transmission.

In some embodiments, network device 110 may determine a first number of time slots for data transmission by terminal device 120, as described above. In this case, network device 110 may receive the measurement report from terminal device 120, determine the first number based on the measurement report, and transmit the first number to network device 120.

In some embodiments, an apparatus (e.g.,

terminal devices

120, 130, and 140) for performing method 200 may include respective modules for performing corresponding steps in method 200. These modules may be implemented in any suitable manner. It may be implemented, for example, by circuitry or software modules.

In some embodiments, the apparatus comprises: means for determining a first number of timeslots for data transmission to be performed by a terminal device; means for determining a signature pattern from a plurality of candidate signature patterns, each candidate signature pattern comprising a sequence of a second number of signatures, the second number being greater than or equal to the first number; and means for sequentially performing data transmission in a first number of slots using a first number of signatures in the determined signature pattern.

In some embodiments, the means for determining the signature pattern comprises: means for selecting a signature mode from a plurality of candidate signature modes based on at least one of: an identifier of the terminal device and a slot number of at least one slot of the first number of slots.

In some embodiments, the means for determining the signature pattern comprises: means for receiving an indication of a signature mode from a network device in communication with a terminal device.

In some embodiments, any two signature patterns of the plurality of candidate signature patterns have at most two signatures that are the same at the corresponding positions.

In some embodiments, the means for performing data transfer comprises: means for initiating the determined signature pattern before the first number of slots such that the determined signature pattern starts at a slot having a predetermined slot number.

In some embodiments, the second number is configured based on at least one of: the number of terminal devices to use the plurality of candidate signature patterns and an estimated traffic arrival rate of one of the terminal devices.

In some embodiments, the apparatus further comprises at least one of: means for associating each signature of the second number of signatures with a unique demodulation reference signal (DMRS) or preamble; means for associating each candidate signature pattern with a unique DMRS or preamble; and means for associating a set of candidate signature patterns of the plurality of candidate signature patterns with the same DMRS or preamble.

In some embodiments, the means for performing data transfer comprises: means for initiating a data transmission in a time slot having a predetermined slot number.

In some embodiments, the means for determining the first number of timeslots comprises: means for transmitting a measurement report to a network device in communication with a terminal device; and means for receiving a first number from the network device.

In some embodiments, the means for determining the first number of time slots comprises: means for selecting a first number from a plurality of predetermined numbers, each predetermined number of the plurality of predetermined numbers of slots being associated with a respective DMRS set.

In some embodiments, the plurality of candidate signature patterns is determined based on the first number.

In some embodiments, the means for performing data transfer comprises: means for repeatedly performing data transmission in a first number of time slots.

In some embodiments, each signature comprises at least one of: spreading sequences, interleaver patterns, codebooks, and DMRS patterns or sequences.

In some embodiments, an apparatus (e.g., network device 110) for performing method 600 may include respective modules for performing corresponding steps in method 600. These modules may be implemented in any suitable manner. It may be implemented, for example, by circuitry or software modules.

In some embodiments, the apparatus comprises: means for receiving a data transmission from a terminal device in a first number of timeslots; means for determining a signature pattern from the data transmission, the determined signature pattern being from a plurality of candidate signature patterns, each candidate signature pattern comprising a sequence of a second number of signatures, the second number being greater than or equal to the first number; and means for distinguishing a data transmission of the terminal device from another data transmission of another terminal device using the determined signature pattern.

In some embodiments, the apparatus further comprises: means for selecting a signature mode for the terminal device from a plurality of candidate signature modes; and means for transmitting an indication of the signature mode to the terminal device to perform the data transmission.

In some embodiments, the apparatus further comprises: means for receiving a measurement report from a terminal device; means for determining a first number based on the measurement report; and means for transmitting the first number to the network device.

Fig. 7 is a simplified block diagram of a device 700 suitable for implementing embodiments of the present disclosure. Device 700 may be viewed as another example embodiment of network device 110 and

terminal devices

120, 130, and 140 as shown in fig. 1. Accordingly, device 700 may be implemented at network device 110 or

terminal devices

120, 130, or as part of network device 110 or

terminal devices

120, 130, and 140.

As shown, device 700 includes a processor 710, a memory 720 coupled to processor 710, a suitable Transmitter (TX) and Receiver (RX) 740 coupled to processor 710, and a communication interface coupled to TX/RX 740. The memory 720 stores at least a portion of the program 730. TX/RX 740 is used for bi-directional communication. TX/RX 740 has at least one antenna to facilitate communication. The communication interface may represent any interface required for communication with other network elements, such as an X2 interface for bidirectional communication between enbs, an S1 interface for communication between a Mobility Management Entity (MME)/serving gateway (S-GW) and an eNB, a Un interface for communication between an eNB and a Relay Node (RN), or a Uu interface for communication between an eNB and a terminal device.

The programs 730 are assumed to include program instructions that, when executed by the associated processor 710, enable the device 700 to operate in accordance with embodiments of the present disclosure, as described herein with reference to fig. 1-6. The implementations herein may be implemented by computer software executable by the processor 710 of the device 700, or by hardware, or by a combination of software and hardware. The processor 710 may be configured to implement various embodiments of the present disclosure. Further, the combination of processor 710 and memory 720 may form a processing device 750 suitable for implementing various embodiments of the present disclosure.

The memory 720 may be of any type suitable to a local technology network and may be implemented using any suitable data storage technology, such as non-transitory computer-readable storage media, semiconductor-based storage devices, magnetic storage devices and systems, optical storage devices and systems, fixed memory and removable memory, as non-limiting examples. Although only one memory 720 is shown in device 700, there may be several physically distinct memory modules in device 700. The processor 710 may be of any type suitable to the local technology network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital Signal Processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples. The device 700 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock that is synchronized to the main processor.

The components included in the apparatus and/or devices of the present disclosure may be implemented in various ways, including software, hardware, firmware, or any combination thereof. In one embodiment, one or more of the units may be implemented using software and/or firmware (e.g., machine executable instructions stored on a storage medium). Some or all of the elements in an apparatus and/or device may be implemented, at least in part, by one or more hardware logic components in addition to or in place of machine-executable instructions. By way of example, and not limitation, illustrative types of hardware logic components that may be used include Field Programmable Gate Arrays (FPGAs), application Specific Integrated Circuits (ASICs), application Specific Standard Products (ASSPs), system-on-Chip Systems (SOCs), complex Programmable Logic Devices (CPLDs), and so forth.

In general, the various embodiments of the disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of the embodiments of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product comprises computer-executable instructions, such as those included in program modules, that execute in a device on the target real or virtual processor to perform the processes or methods described above with reference to any of figures 3 and 4. Generally, program modules include routines, programs, libraries, objects, classes, components, data types, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed arrangement, program modules may be located in both local and remote memory storage media.

Program code for performing the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/acts specified in the flowchart and/or block diagram to be performed. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine-readable medium, which may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More specific examples of a machine-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. Also, while the above discussion contains several specific embodiment details, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method implemented at a terminal device, comprising:

determining a first number of timeslots for data transmission to be performed by the terminal device;

determining a signature pattern from a plurality of candidate signature patterns, each candidate signature pattern comprising a sequence of a second number of signatures, the second number being greater than or equal to the first number; and

sequentially performing the data transmission in the first number of slots using the first number of signatures in the determined signature pattern.

2. The method of claim 1, wherein determining the signature pattern comprises:

selecting the signature pattern from the plurality of candidate signature patterns based on at least one of: an identifier of the terminal device, and a slot number of a slot of the first number of slots.

3. The method of claim 1, wherein determining the signature pattern comprises:

receiving an indication of the signature mode from a network device in communication with the terminal device.

4. The method of claim 1, wherein any two signature patterns of the plurality of candidate signature patterns have at most two signatures that are the same at corresponding positions.

5. The method of claim 1, wherein performing the data transmission comprises:

initiating the determined signature pattern before the first number of time slots such that the determined signature pattern starts at a time slot having a predetermined time slot number.

6. The method of claim 1, wherein the second number is configured based on at least one of: a number of terminal devices to use the plurality of candidate signature patterns, and an estimated traffic arrival rate of one of the terminal devices.

7. The method of claim 1, further comprising at least one of:

associating each signature of the second number of signatures with a unique demodulation reference signal (DMRS) or preamble;

associating each candidate signature pattern with a unique DMRS or preamble; and

associating a set of candidate signature patterns of the plurality of candidate signature patterns with the same DMRS or preamble.

8. The method of claim 1, wherein performing the data transmission comprises:

the data transmission is initiated in a time slot having a predetermined slot number.

9. The method of claim 1, wherein determining the first number of slots comprises:

transmitting a measurement report to a network device in communication with the terminal device; and

receiving the first number from the network device.

10. The method of claim 1, wherein determining the first number of slots comprises:

selecting the first number from a plurality of predetermined numbers, each predetermined number of the plurality of predetermined numbers being associated with a respective DMRS set.

11. The method of claim 1, wherein the plurality of candidate signature patterns is determined based on the first number.

12. The method of claim 1, wherein performing the data transmission comprises:

the data transmission is repeatedly performed in the first number of slots.

13. The method of any of claims 1 to 12, wherein each of the signatures comprises at least one of: spreading sequences, interleaver patterns, codebooks, and DMRS patterns or sequences.

14. A method implemented at a network device, comprising:

receiving a data transmission from a terminal device in a first number of timeslots;

determining a signature pattern from the data transmission, the determined signature pattern being from a plurality of candidate signature patterns, each candidate signature pattern comprising a sequence of a second number of signatures, the second number being greater than or equal to the first number; and

using the determined signature pattern to distinguish the data transmission of the terminal device from another data transmission of another terminal device.

15. The method of claim 14, further comprising:

selecting the signature mode for the terminal device from the plurality of candidate signature modes; and

transmitting an indication of the signature mode to the terminal device to perform the data transmission.

16. The method of claim 14 or 15, further comprising:

receiving a measurement report from the terminal device;

determining the first number based on the measurement report; and

transmitting the first number to the network device.

17. A terminal device, comprising:

at least one processor; and

at least one memory storing computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the terminal device to:

18. The terminal device of claim 17, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to:

19. The terminal device of claim 17, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to:

20. The terminal device of claim 17, wherein any two signature patterns of the plurality of candidate signature patterns have at most two signatures that are identical at corresponding positions.

21. The terminal device of claim 17, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to:

22. The terminal device of claim 17, wherein the second number is configured based on at least one of: a number of terminal devices to use the plurality of candidate signature patterns, and an estimated traffic arrival rate of one of the terminal devices.

23. The terminal device of claim 17, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to perform at least one of:

24. The terminal device of claim 17, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to:

25. The terminal device of claim 17, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to:

receiving the first number from the network device.

26. The terminal device of claim 17, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to:

27. The terminal device of claim 17, wherein the plurality of candidate signature patterns is determined based on the first number.

28. The terminal device of claim 17, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the terminal device to:

the data transmission is repeatedly performed in the first number of slots.

29. The terminal device of any of claims 17 to 28, wherein each of the signatures comprises at least one of: spreading sequences, interleaver patterns, codebooks, and DMRS patterns or sequences.

30. A network device, comprising:

at least one processor; and

at least one memory storing computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the network device to:

31. The network device of claim 30, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the network device to:

32. The network device of claim 30 or 31, wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the network device to:

receiving a measurement report from the terminal device;

determining the first number based on the measurement report; and

transmitting the first number to the network device.

33. A computer-readable medium having instructions stored thereon that, when executed on at least one processor of a device, cause the device to perform the method of any one of claims 1-13.

34. A computer-readable medium having instructions stored thereon, which when executed on at least one processor of a device, cause the device to perform the method of any of claims 14 to 16.