CN112119664B

CN112119664B - Multiple access techniques in cellular networks

Info

Publication number: CN112119664B
Application number: CN201980031316.8A
Authority: CN
Inventors: 布鲁诺·杰裘克斯; 欧麦尔·萨利姆
Original assignee: JRD Communication Shenzhen Ltd
Current assignee: JRD Communication Shenzhen Ltd
Priority date: 2018-05-10
Filing date: 2019-05-09
Publication date: 2024-03-19
Anticipated expiration: 2039-05-09
Also published as: WO2019214686A1; GB201807638D0; GB2573751A; CN112119664A

Abstract

A method and apparatus for non-orthogonal multiple access, UE controls selection of transmission parameters for uplink transmission, reducing control overhead compared to network hold control. The uplink transmission may include an indication of transmission parameters, such as a modulation coding scheme.

Description

Multiple access techniques in cellular networks

Technical Field

The present invention relates to multiple access techniques in cellular networks, and more particularly to non-orthogonal multiple access (non-orthogonal multiple access) of uplink channels in cellular networks.

Background

Wireless communication systems, such as third generation (3G) mobile telephone standards and technologies, are well known. The 3G standard and technology was developed by the third generation partnership project (3GPP,Third Generation Partnership Project). Third generation wireless communications were developed to support macrocell mobile telephone communications. Communication systems and networks are evolving towards broadband mobile systems.

In a cellular wireless communication system, a User Equipment (UE) is connected to a radio access network (RAN, radio Access Network) by a wireless link. The RAN comprises: a set of base stations providing radio links to UEs located in a cell covered by the base stations; and an interface to a Core Network (CN) that provides overall Network control. It is understood that the RAN and the CN each perform a corresponding function with respect to the entire network. For convenience, the term cellular network will be used to refer to the combined RAN & CN, and it will be understood that the term is used to refer to the various systems used to perform the disclosed functions.

The third generation partnership project has developed a so-called long term evolution (LTE, long Term Evolution) system, i.e. an evolved universal terrestrial radio access network (E-UTRAN, evolved Universal Mobile Telecommunication System Territorial Radio Access Network), in which one or more macro cells are supported by a base station eNodeB or eNB (evolved NodeB). Recently, LTE has evolved further towards so-called 5G or NR (New Radio) systems, where one or more macro cells are supported by a base station gNB. NR proposes to employ an orthogonal frequency division multiplexing (OFDM, orthogonal Frequency Division Multiplexed) physical transmission format.

One trend in wireless communications is to provide lower latency and more reliable service. For example, NR is intended to support Ultra-reliable low-latency communication (URLLC, ultra-reliable and low-latency communications), and large Machine type communication (mMTC, large Machine-Type Communications) is intended to provide low latency and high reliability for small data packets (typically 32 bytes). The user plane (user-plane) delay is 1ms with a reliability of 99.99999%. Other proposed service types include enhanced mobile broadband (eMBB, enhanced Mobile BroadBand) for high data rate transmissions, and large-scale Machine-type communication (emtc, passive Machine-Type Communication) for supporting a large number of devices over an energy efficient communication channel over a long life cycle.

Communication over a physical radio link is defined by a number of channels, e.g. in the uplink direction, a physical uplink shared channel (PUSCH, physical Uplink Shared Channel) for transmission from the UE to the base station. PUSCH is transmitted using a set of time (slot) and frequency resources. In conventional systems, only one UE transmits a signal on each set of time and frequency resources, so that there is no overlap between transmissions. In a conventional spatial multiplexing system (system applying spatial multiplexing), only one UE per spatial layer (spatial layer) transmits signals on each set of time and frequency resources. While such resource allocation reduces interference between UEs, capacity is limited by available resources.

Techniques such as non-orthogonal multiple access (NOMA) may be utilized to allow multiple UEs to transmit on a particular resource to increase the ability to use time and frequency resources. Fig. 1 shows an example of NOMA transmission, where multiple PUSCHs are transmitted on overlapping resources. Each transmission includes a Multiple Access (MA) signature for identifying the UE that is transmitting, and may also include a DMRS for assisting in demodulation of the signal.

At the base station, the lower power signal appears as noise on the higher power signal. The higher power signal may be directly demodulated by removing noise and then may be removed from the received signal to recover the lower power signal. Such a receiving end is called a successive interference cancellation (SIC, successive Interference Cancellation) receiving end, but other receiving techniques may be used as well.

Since uplink resources are used for more than one UE transmission, the NOMA technique has the advantage of improving resource efficiency.

mctc services are typically characterized by a large number of devices, occasionally transmitting small data packets (typically 10-75 bytes). For example, a cell is expected to support thousands of devices. In this case, overhead of a signaling channel for configuring uplink communication (e.g., scheduling and modulation coding scheme (MCS, modulation Coding Scheme)) may be prohibited, and thus unlicensed transmission may be used for uplink. Similarly, the number of devices may be much greater than the available number of MA signatures, thus preventing unique identification of the UE.

The UE may also not transmit in the first time (from RRC IDLE state (rrc_idle) or RRC INACTIVE state (rrc_inactive)) to RRC CONNECTED state (rrc_connected), thus eliminating the ability to use RRC for UE transmission parameter configuration.

Thus, there is a need for an improved NOMA uplink transmission system.

Disclosure of Invention

This summary presents some concepts in a simplified form as a more detailed description detailing the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

The present invention provides a method of uplink data transmission from a user equipment UE to a base station in a wireless cellular communication network, the uplink transmission using a non-orthogonal multiple access NOMA protocol, the method comprising the steps of: the UE selects a modulation coding scheme for uplink data transmission; and transmitting an uplink transmission using the modulation and coding scheme, the uplink transmission including an indication of the selected modulation and coding scheme; wherein the uplink transmission is transmitted using an unlicensed transmission protocol.

The modulation and coding scheme may be selected from a subset of modulation and coding schemes, wherein the subset of modulation and coding schemes is a set selected from a larger set of modulation and coding schemes available for use by the UE.

The indication of the modulation coding scheme may be transmitted in an uplink control information report.

The modulation coding scheme may be selected based on the performance of a previous set of uplink unlicensed NOMA transmissions.

The modulation coding scheme may be selected by selecting a modulation coding scheme that enhances or reduces robustness, respectively, based on the failure or success of a previous uplink unlicensed NOMA transmission.

The modulation coding scheme may be selected from an ordered list of coding schemes, the ordered list ordered by robustness, each coding scheme having a robustness index.

Depending on the failure or success of at least one previous transmission, a coding scheme may be selected with a higher or lower robustness index than the one used for the previous transmission, respectively.

The robustness index may be higher or lower than the first step size or the second step size, respectively.

If consecutive m uplink transmissions are not successfully acknowledged, the robustness index may be higher.

If n consecutive uplink transmissions are successfully acknowledged, the robustness index may be lower.

The modulation and coding scheme may be selected based on downlink performance information obtained from downlink synchronization.

The modulation coding scheme may be selected according to a BLER value.

The uplink transmission may include a multiple access signature (multiple access signature).

The modulation and coding scheme may be selected independently of the base station.

The CRC of the uplink transmission may be scrambled with the identity of the UE.

The identity may be a UE xnti or a UE ID.

The indication of the modulation coding scheme may be provided by a dedicated field in the PUSCH channel.

The dedicated field may include 2 to 5 bits.

The format of the indication of the modulation coding scheme may be defined by at least one RRC configuration message.

The RRC configuration message may include a set of parameters including betaOffsetMCS-Index0, betaOffsetMCS-Index1, respectively providing an Index for the UEFor use when the UE multiplexes up to 2 MCS bits or more than 2 and up to 5 MCS bits in PUSCH.

The parameters used by the UE in the algorithm to select the modulation and coding scheme may be defined by the base station.

The invention also provides mobile equipment configured to execute the method.

The non-transitory computer readable storage medium may include at least one of a hard disk, a compact disk Read Only Memory (CD-ROM, compact Disc Read Only Memory), an optical Memory, a magnetic Memory, a Read Only Memory (ROM), a programmable Read Only Memory (PROM, programmable Read Only Memory), an erasable programmable Read Only Memory (EPROM, erasable Programmable Read Only Memory), an electrically erasable programmable Read Only Memory (EEPROM, electrically erasable programmable Read Only Memory), and a Flash Memory (Flash Memory).

Drawings

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Elements in the figures have been simplified and are not necessarily drawn to scale. Reference numerals have been included in the various figures to facilitate understanding.

Fig. 1 is an exemplary diagram of NOMA transmission.

Fig. 2 is a schematic diagram of an uplink transmission method.

Fig. 3 is a schematic diagram of a receiving method.

Fig. 4 is a schematic diagram of an uplink transmission method.

Fig. 5 is a schematic diagram of a receiving method.

Detailed Description

The embodiments described herein are intended to be merely some, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

As described above, overhead problems may prevent the use of grant-based UL NOMA transmissions, especially for devices using mtc type services, thereby limiting the ability of the base station to select and configure UL transmission parameters. Furthermore, each MA signature may be used by multiple UEs, thereby preventing identification of MA signature-based UEs.

One way to identify a UE is to include the UE's xrit or UE ID in the UCI of PUSCH transmission multiplexing. Although this may directly identify the UE, 16 or 24 bits of overhead may be required on a 10-150 byte payload. In addition, these bits must be encoded in a robust (robust) and fixed MCS, thus further increasing overhead. An alternative that does not require any overhead is to use the UE identity to scramble the CRC transmission. Although in this case the UE can only be identified after data demodulation and CRC check, the reduced overhead may be more attractive, especially for the transmission of small data.

Fig. 2 shows a flow chart of a method of transmitting signals from a UE to a base station. In step 20, the UE prepares to transmit the required data on PUSCH, including a MA signature selected from a set of MA signatures allocated to the UE. The UE may randomly select the MA signature. The UE scrambles the CRC of the prepared data using the UE's xrit or UE ID in step 21 and transmits the message on PUSCH using the unlicensed (grant-free) transmission protocol in step 22. Multiple UEs connected to a particular base station may use the method of fig. 2 at the same time, and thus resources may be occupied by transmissions by more than one UE. Similarly, more than one message may be transmitted using the same MA signature.

Fig. 3 illustrates a method of decoding a received transmission and identifying a transmitting UE. In step 30, the base station receives NOMA transmissions from one or more UEs and detects a MA signature. Since each MA signature may be shared between more than one UE, the signature allows the base station to identify a group of UEs that may have received a transmission, rather than uniquely identifying the UE.

In step 31, the base station demodulates the received signal using a blind detection algorithm (blind detection algorithm). At this stage of the process, the base station does not know the identity of the UE that is transmitting nor the MCS used for the transmission. The SIC type receiving end can be utilized to demodulate the received signal and recover each overlapping transmission. Because the base station has insufficient knowledge of the received signal, the base station may need to test a large number of options during blind demodulation. That is, blind demodulation can be performed in a larger search space. The use of SIC receivers to recover multiple NOMA signals can make the process more challenging.

After signal recovery, the CRC is checked and descrambled (descrambled) in step 32 to identify the xRNTI or UE ID of the UE used to scramble the CRC (scramble) by the UE.

Selecting a unique MCS for all relevant devices may reduce the search space of the demodulation process. Thus, the blind demodulation process only needs to test the MCS. However, the selected MCS must be the most robust performing MCS because it will be used in all cases, and therefore it must support worst case link conditions. QPSK MCS with lower code rate is usually adopted, and has stronger robustness (robust), but the spectrum efficiency is poor.

These standards (e.g., TS28.214, table 6.1.4.1-1) define a set of possible MCS schemes. To reduce the set of MCSs that must be tested during blind demodulation, a subset of MCSs may be allocated to UEs transmitting NOMA traffic (traffic), thereby reducing search space. The scheme can flexibly select proper MCS according to the link condition, but simultaneously, the complexity of demodulation is also considered. When transmitting the NOMA message using the procedure shown in fig. 1, the UE selects an appropriate MCS from the allocated subset.

Due to the infrequent nature of mctc transmissions, it is unlikely that a base station will acquire enough signals from a UE to know the current channel conditions and thus select an appropriate MCS. In addition, the overhead of transmitting the configuration message to each UE may be significant. Instead, the UE must synchronize on the downlink channel before transmission, so the UE has up-to-date information about the downlink channel conditions. The downlink channel condition is a reasonable indicator (reasonable indicator) of the uplink channel condition and thus can be used to guide the selection of an appropriate MCS that is independent of the base station.

The UE may select the MCS using any suitable procedure. In an example, the UE may pre-configure a specific MCS. For example, a low-end (low-end) UE transmitting a small amount of data may always utilize a simple MCS, such as QPSK.

Fig. 4 illustrates a method of selecting an MCS for a NOMA UL transmission. In step 40, the UE wakes up and performs DL synchronization before NOMA transmission. Based on the measured DL SINR and optionally the ACK/NACK history for the previous PUSCH transmission (41), the UE selects the appropriate MCS in step 42.

In step 43, the ue performs data transmission on PUSCH using the selected MCS, for example as shown in fig. 2. The transmitted message may include an indication of the selected MCS, which may be utilized by the base station to demodulate the received signal at step 44. Once demodulated, the base station transmits an ACK/NACK in step 45.

The UE may update its ACK/NACK history for future transmissions and may then return to a sleep state (sleep).

As described above, the MCS for each UL NOMA transmission is selected by the UE (i.e., the UE performs link rate adaptation (link rate adaptation)). Although the MCS may be selected based on conventional BER or BLER statistics, this is unlikely to be effective in mctc type systems, which rarely make small data transmissions (small transmissions), and therefore the link characteristics may vary greatly between transmissions.

The procedure outlined below may be used to select an MCS for UL NOMA transmission, such as the method of fig. 4. The method uses the latest PUSCH transmission result to increase or decrease the selected MCS, which is expressed as follows: if lastmtxfaiiled, mcs=max (MCS-K1, MCSmin), end;

if lastntxsummed, mcs=min (mcs+k2, MCSmax) ends.

MCSmin is an index of the most robust available MCSs (e.g., 0 represents NR OMA), and MCSmax is an index of the highest throughput MCS.

Lastmtxfailed=1 if the last NOMA Tx of the UE is not acknowledged, otherwise 0.

K1 and K2 are integer values greater than or equal to 1.

Lastmtxfailed=1 if the last m NOMA UL transmissions fail, m is a configurable integer greater than or equal to 1.

If the last n NOMA UL transmissions have been successful, lastntxsuccided=1, n being a configurable integer greater than or equal to 1.

Thus, when ordered according to robustness, the process increases or decreases the MCS according to success or failure of a configurable number of the latest PUSCH transmissions. As described above, if there is no ACK/NACK (acknowledgement/non-acknowledgement) history (e.g., no ACK transmission, or insufficient previous transmission), the MCS may be selected based on an assessment of the signal quality or other channel quality of the downlink synchronization (e.g., DL SINR, DL RSRP, DL RSSI, or any equivalent).

In general, the selection of MCS can be said to be based on the latest events (events) related to the transmission channel.

The selected MCS may be indicated in PUSCH using a "UCI reporting in physical uplink shared channel" (clause 9.3 in TS 38.213) procedure in which the UE multiplexes UCI information in PUSCH.

The new offset value, specific to the signaling MCS, may be defined by the UE to determine the number of resources for multiplexing the MCS indication in the PUSCH. The offset value may be scheduled PUSCH transmission in a DCI format or transmitted by higher layers to the UE. In particular, a new set of parameters betaoffsetmc-index0, betaoffsetmc-index1, respectively, provide an index for the UEFor use when the UE multiplexes up to 2 MCS bits or more than 2 MCS bits and up to 5 MCS bits, respectively, in PUSCH.

Fig. 5 shows a flow chart of a NOMA PUSCH reception method when the PUSCH includes an indication of MCS. In step 50, the base station detects the MA signature (which, as described above, allows to identify the group of UEs to which the transmitting UE belongs), and then in step 51, the base station demodulates the MCS field. In step 52, the received signal is demodulated and recovered using the indicated MCS, for example using the SIC receiver. Since the MCS is known, no penalty is incurred at this stage due to lack of knowledge of the particular UE transmitting the signal. The UE may be identified at step 53 after the CRC check and descrambling from which the xrrnti or UE ID used to scramble the CRC may be recovered.

Although not shown in detail, any device or apparatus forming part of a network may comprise at least a processor, a storage unit and a communication interface, wherein the processor unit, the storage unit and the communication interface are configured to perform the methods of any aspect of the invention. Further options and choices are described below.

The signal processing functions in the embodiments of the present application, and in particular, the signal processing capabilities of the gNB and the UE, may be implemented by computing systems or architecture known to those skilled in the art. The computing system may be a desktop, laptop or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device as may be satisfied by or otherwise employed in a given application or environment. The computing system may include one or more processors that may execute a general-purpose or special-purpose processing engine, such as a microprocessor, single-chip microcomputer or other control module.

The computing system may also include a main memory, such as random access memory (Random Access Memory, RAM) or other dynamic memory, for storing information and instructions to be executed by the processor. The main memory may also be used for storing temporary variables or other intermediate information during execution of instructions by the processor. The computing system may also include a Read Only Memory (ROM) or other static storage device for storing static information and instructions for execution by the processor.

The computing system may also include an information storage system including, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism that supports fixed or removable storage media, such as a hard disk drive, floppy disk drive, magnetic tape drive, optical disk drive, compact disk drive (CD) or Digital Video Drive (DVD) read-write drive (R or RW), or other fixed or removable media drive. Storage media may include, for example, hard disk, floppy disk, magnetic tape, optical disk, CD, DVD, or other fixed or removable medium that is read by and written to by media drives. The storage medium may include a computer-readable storage medium storing specific computer software or data.

In alternative embodiments, the information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. These components may include, for example, removable storage units and interfaces such as program cartridge and cartridge interfaces, removable memory (such as flash memory or other removable memory modules) and memory slots, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to the computing system.

The computing system may also include a communication interface. The communication interface may be used to allow software and data to be transferred between the computing system and an external device. For example, the communication interface can include a modem, a network interface (such as an Ethernet or other network card), a communication port (such as a Universal Serial Bus (USB) port), a PCMCIA slot and card, etc. Software and data transferred via the communications interface are in the form of signals which may be electronic, electromagnetic, optical or other signals capable of being received by the communications interface medium.

In this application, the terms "computer program product," "computer-readable medium," and the like are generally used to refer to tangible media, such as memory, storage devices, or storage units. These and other forms of computer-readable media may store one or more instructions for use by a processor, including a computer system, to cause the processor to perform specified operations. These instructions, which are typically referred to as "computer program code" (which may be grouped in the form of computer programs or other groupings), when executed, enable the computer system to perform functions of embodiments of the present application. It is noted that the code may direct a processor to perform specified operations, or may be compiled to perform specified operations and/or combined with other software, hardware, and/or firmware elements (e.g., libraries that perform standard functions).

The non-computer readable medium may include at least one of the group consisting of: hard disk, compact disk Read Only (CD-ROM, compact Disc Read Only Memory), optical storage, magnetic storage, read Only Memory (ROM), programmable Read Only Memory (PROM, programmable Read Only Memory), erasable programmable Read Only Memory (EPROM, erasable Programmable Read Only Memory), electrically erasable programmable Read Only Memory (EEPROM, electrically erasable programmable Read Only Memory), and Flash Memory (Flash Memory).

In an embodiment implemented by software, the software may be stored in a computer readable medium and loaded into a computing system using, for example, a removable storage drive. A control module (e.g., software instructions or executable computer program code) executed by a processor in a computer system causes the processor to perform the functions as described herein.

Further, the present application may be applied in any circuit in a network element for performing signal processing functions. For example, it is further contemplated that a semiconductor manufacturer may employ innovative concepts in the design of a stand-alone device, which may be a microcontroller (DSP) of a digital signal processor, an Application Specific Integrated Circuit (ASIC), and/or any other subsystem element.

For clarity of description, the above description describes embodiments of the present application with reference to single processing logic. However, the present application may equally implement the signal processing function by a plurality of different functional units and processors. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical, physical structure, or organization.

Aspects of the present application may be implemented in any suitable form including hardware, software, firmware or any combination of these. The present application may optionally be implemented at least in part as computer software, as computer software components such as FPGA devices running on one or more data processors and/or digital signal processors or configurable modules. Thus, the elements and components of an embodiment of the disclosure may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units.

Although the present application has been described with reference to the preferred embodiments, the preferred embodiments are not intended to limit the application, but rather the scope of the application is defined by the claims. Furthermore, although a description of features associated with a particular embodiment may occur, those skilled in the art may obtain a variety of features of the described embodiment in light of the instant application. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Further, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Furthermore, although different features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Likewise, the inclusion of a feature in one set of claims does not imply a limitation to this set of claims but rather indicates that the feature is equally applicable to other classes of claims where appropriate.

Further, the ordering of features in the claims does not imply that the features must be performed in a specific order, and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus, the singular references of "a", "an", "the" and "second" do not exclude a plurality.

Although the present application has been described with reference to the preferred embodiments, the preferred embodiments are not intended to limit the application, but rather the scope of the application is defined by the claims. Furthermore, although a description of features associated with a particular embodiment may occur, those skilled in the art may obtain a variety of features of the described embodiment in light of the instant application. In the claims, the term "comprising" or "including" does not exclude the presence of other elements.

Claims

1. A method of uplink data transmission from a user equipment, UE, to a base station in a wireless cellular communication network, wherein the uplink transmission uses a non-orthogonal multiple access, NOMA, protocol, the method comprising the steps of:

the UE selecting a modulation coding scheme (Modulation Coding Scheme, MCS) for uplink data transmission; the method comprises the steps of,

transmitting an uplink transmission using the modulation and coding scheme, the uplink transmission including an indication of the selected modulation and coding scheme;

wherein the format of the indication of the modulation and coding scheme is defined by at least one RRC configuration message, the uplink transmission being transmitted using an unlicensed transmission protocol, the RRC configuration message comprising a set of parameters, each providing an index for the UE to use when the UE multiplexes up to 2 MCS bits or more than 2 and up to 5 MCS bits in a physical uplink shared channel (Physical uplink Shared Channel, PUSCH), the index being a parameter related to MCS and an offset, the offset being a parameter related to MCS;

the modulation coding schemes are selected from an ordered list of modulation coding schemes, the ordered list being ordered according to robustness, each modulation coding scheme having a robustness index;

selecting a modulation and coding scheme having a higher or lower robustness index than the modulation and coding scheme used for the previous transmission, respectively, depending on the failure or success of at least one previous transmission;

if the m consecutive uplink transmissions are not successfully acknowledged, the index of the selected modulation and coding scheme takes the following two large values: the index of the most robust available MCS, or the index of the modulation and coding scheme used by the previous transmission minus the first step size, such that the robustness index of the selected modulation and coding scheme is higher than the robustness index of the modulation and coding scheme used by the previous transmission; and

If n consecutive uplink transmissions are successfully acknowledged, the index of the selected modulation and coding scheme is the following two small values: the index of the highest throughput MCS, or the sum of the index of the modulation and coding scheme used by the previous transmission plus a second step, is such that the robustness index of the selected modulation and coding scheme is lower than the robustness index of the modulation and coding scheme used by the previous transmission, where m and n are positive integers.

2. The method of claim 1, wherein the modulation and coding scheme is selected from a subset of modulation and coding schemes, wherein the subset of modulation and coding schemes is a set selected from a larger set of modulation and coding schemes available for use by UEs.

3. The method of claim 1, wherein the indication of the modulation coding scheme is transmitted in an uplink control information report.

4. The method of claim 1 wherein the modulation coding scheme is selected based on performance of a previous set of uplink unlicensed NOMA transmissions.

5. The method of claim 1, wherein the modulation and coding scheme is selected based on a failure or success of a previous uplink unlicensed NOMA transmission by selecting a modulation and coding scheme that enhances or reduces robustness, respectively.

6. The method of claim 1, wherein the modulation and coding scheme is selected based on downlink performance information obtained from downlink synchronization.

7. The method of claim 1, wherein the modulation coding scheme is selected based on a BLER value.

8. The method of claim 1, wherein the uplink transmission comprises a multiple access signature.

9. The method of claim 1, wherein the modulation and coding scheme is selected independently of the base station.

10. The method of claim 1, wherein the CRC of the uplink transmission is scrambled with an identity of the UE.

11. The method of claim 10, wherein the identity is a UE xnti or a UE ID.

12. The method of claim 1, wherein the indication of the modulation coding scheme is provided by a dedicated field in a PUSCH channel.

13. The method of claim 12, wherein the dedicated field comprises 2 to 5 bits.

14. The method of claim 1, wherein parameters used by the UE in an algorithm to select the modulation and coding scheme are defined by the base station.

15. A mobile device comprising a processor configured to perform the method of any of claims 1 to 14.