Patent Description:
To meet the demand for wireless data traffic, which has increased since deployment of fourth generation (<NUM>) communication systems, efforts have been made to develop an improved fifth generation (<NUM> or pre-<NUM> communication system, also referred to as a "beyond <NUM> network" or a "post long term evolution (LTE) system". The <NUM> communication system is considered to be implemented in higher frequency millimeter wave (mmWave) bands, e.g., <NUM> gigahertz (GHz) bands, so as to achieve higher data rates.

To decrease propagation loss of the radio waves and increase the transmission distance, techniques such as beamforming, massive multiple-input multiple-output (mMIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beam forming, and large scale antenna are discussed in <NUM> communication systems. In addition, development for system network improvement in <NUM> communication systems is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMP), and reception-end interference cancellation, for example. In the <NUM> system, hybrid frequency shift keying (FSK), frequency quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.

The Internet is now evolving to the Internet of things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of everything (IoE), which is a combination of IoT technology and big data processing technology through connection with a cloud server, has also emerged. As technology elements, such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology have been demanded for IoT implementation, research is being conducted on a sensor network, a machine-to-machine (M2M) communication, machine type communication (MTC), for example.

Consistent with this, various attempts have been made to apply <NUM> communication systems to IoT networks. Application of a cloud RAN as the above-described big data processing technology may also be considered as an example of convergence between the <NUM> technology and IoT technology.

In line with this, random access procedure is an important way for terminals to establish an access with base stations within a system.

<CIT> describes a method for wireless communication of a user equipment (UE) in a radio resource control (RRC) Inactive state, the method includes sending, by the UE, an RRC Connection Resume Request message to a base station, and transmitting, by the UE, a packet to the base station using one or more radio resources allocated by the base station, where the base station identifies the UE based on the RRC Connection Resume Request message, which includes a UE ID or a UE-specific preamble. Before the UE enters the RRC Inactive state, the base station sends a pre-configured random access configuration to the UE for transmitting the packet in a subsequent a random access procedure. The pre-configured random access configuration includes at least one of a pre-configured bandwidth part configuration, a plurality of access control parameters, the UE ID, and a time pattern for the random access procedure.

<CIT> relates to a random access procedure for a wireless communication system, the random access procedure may include various steps, such as <NUM>-steps or <NUM>-steps. One or more indicators such as, for example, transmission power requirements, may be used to indicate which random access procedure to utilize.

<CIT> describes a random access method comprising receiving random access mechanism configuration information transmitted by a base station, the random access mechanism configuration information comprising: a random access type and random access time-frequency resource information corresponding to the random access type, the random access type comprising a first random access mechanism and/or a second random access mechanism; performing, according to the random access mechanism configuration information, the random access process for the first random access mechanism or the second random access mechanism. <NPL>, is a report of a discussion of a <NUM>-step random access model for <NUM> new-radio and initial information contents of the messages of a <NUM>-step RACH.

<NPL>, is a discussion document relating to the possible design for initial access and mobility procedures for <NUM> new-radio wireless communication systems,.

<CIT>, discloses a broadcast indication of which waveform to be used in a <NUM>-step RACH procedure.

In order to cope with a variety of application scenarios and wider application requirements supported by <NUM>, it is necessary to enhance the random access process supported by <NUM>. The two-step random access procedure is an effective enhancement of the random access procedure. In the two-step random access procedure, the user equipment first transmits the preamble and data on the time-frequency resource pre-configured or selected by the base station. The combination of the payload of data transmission and the preamble is referred to as message A (MSG. The data payload in the MSG. A includes at least the user equipment identity (for example, the Cell-Radio Network Temporary identity, the C-RNTI, allocated by the base station in a linked state, or the unique identity of the user equipment). If the base station successfully detects the transmission of the preamble and detects the user equipment identity included in the data payload, the base station performs feedback in the downlink channel, and the feedback data is referred as message B (MSG. B will contain contention resolution information to inform the user equipment of the contention resolution situation. <FIG> illustrates a schematic flow chart of the above two-step random access process.

Since the random access procedure supported by the <NUM> does not optimize the aforementioned two-step random access procedure, configurations of the existing random access procedure and configurations of the uplink shared channel are reused in the two-step random access procedure, which will cause a decrease in system efficiency. Therefore, it is necessary to further optimize the two-step random access process to improve the efficiency of the two-step random access process.

In view of this, embodiments of the present disclosure provide an optimized two-step random access procedure.

Embodiments of the present disclosure provide a two-step random access method for improving messaging. With the method provided by the embodiment of the present application, problems such as performance degradation caused by inter-symbol interference and inter-carrier interference in messaging in the two-step random access procedure can be alleviated.

The embodiments of the present disclosure optimize the two-step random access procedure in terms of the channel structure and signaling aspects.

Hereinafter, some example embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be understood, however, that the description is only illustrative, and is not intended to limit the scope of the disclosure. In addition, descriptions of well-known structures and techniques are omitted in the following description in order to avoid unnecessarily obscuring the concept of the present disclosure.

All terms (including technical and scientific terms) used herein have the meaning commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of the present specification and should not be interpreted in an ideal or too rigid manner.

Random access procedure is an important way for terminals to establish an access with base stations within a system. In <NUM>, it is divided into a contention-based random access procedure and a contention-free random access procedure, according to whether the same random access resource (including random access channel time-frequency resources and random access preamble resources) is shared by multiple terminals. The contention-based random access procedure is mainly applied in application scenarios including, for example but not limited to, initial access; when the terminal in a connected state is not synchronized in terms of uplink but has data to be transmitted in uplink; cell handover; or beam recovery from failure and the like. The contention-free random access process is mainly applied in application scenarios including, for example but not limited to, when the terminal in the connected state is not synchronized in terms of uplink and requires giving feedback in uplink as well as receiving downlink data; handover; system information request and the like.

The contention-based random access process supported by <NUM> consists of four steps, as shown in <FIG>. In the first step, a user equipment randomly selects a preamble from a preamble sequence resource pool, and then sends the selected preamble to a base station. The base station performs correlation detection on the received signal to identify the preamble sent from the user equipment. In the second step, the base station sends to the user equipment a random access response (RAR) including a random access preamble identifier, a timing advance command determined according to a delay estimation between the user equipment and the base station, a temporary Cell-Radio Network Temporary Identity (C-RNTI), and time-frequency resources allocated for the next uplink transmission for the user equipment. In the third step, the user equipment sends a third message (Msg3) to the base station according to the information included in the RAR. The Msg3 includes information such as a user equipment terminal identity and a RRC link request. The user equipment terminal identity is unique to the user equipment and is applied to resolve a contention. In the fourth step, the base station sends a contention resolution identity to the user equipment, which includes the user equipment terminal identity of the user equipment that wins in the contention resolution. After detecting its own identity, the user equipment upgrades the temporary C-RNTI to a C-RNTI, and sends an acknowledgment (ACK) signal to the base station to complete the random access procedure and waits for scheduling of the base station. Otherwise, the user equipment will start a new random access procedure after a delay.

The contention-free random access procedure is a simplification of the above four-step random access procedure, including two steps as shown in <FIG>. The user equipment sends the preamble allocated by the base station over a random access occasion allocated by the base station, and detects the RAR within a detection window corresponding to the random access occasion. If the RAR detection is successful, the contention-free random access procedure is considered successful.

In a <NUM> system, the inventors have recognized that optimization for a two-step random access procedure can include the following possible aspects:.

The embodiments of the present disclosure mainly optimize the two-step random access procedure in terms of the channel structure and signaling aspects.

<FIG> schematically illustrates a schematic diagram of a random access method <NUM> according to an embodiment of the present disclosure.

The random access method <NUM> is performed on user equipment side. The method includes: in step S401, acquiring configuration information; in step S402, transmitting a first message including the preamble and the uplink shared channel according to the configuration information; and in step S403, receiving a second message including contention resolution information from the base station.

The configuration information may be configuration information in system information sent by the base station to the user equipment.

In step S402, the user equipment may determine a channel structure in the first message according to the configuration information acquired in step S401, and transmit the first message including the preamble and the uplink shared channel according to the channel structure.

In one embodiment, the channel structure may include the preamble, the uplink shared channel, and the guard time.

The user equipment may acquire a number of consecutive symbols which are occupied by the preamble and the uplink shared channel, on one or more slots in the configuration information, the number of consecutive symbols being less than the maximum number of symbols on the one or more slots. The guard time in the channel structure may be determined based on the number of consecutive symbols and the maximum number of symbols.

A starting time position of the uplink shared channel may be determined in the following manners. For example, the user equipment may acquire the number of time units K from the configuration information, and use a position behind the K time units after the end of time units for a random access occasion as the starting time position for transmitting the uplink shared channel. Alternatively, for example, the user equipment may acquire a time unit index from the configuration information, and determine the starting time position for transmitting the uplink shared channel.

The length of the uplink shared channel may be determined in the following manners. For example, the length of the uplink shared channel may be determined according to the number of slots of the uplink shared channel and the number of symbols in the last slot. Alternatively, the length of the uplink shared channel may be determined according to the number of slots of the uplink shared channel and the number of symbols of the uplink shared channel.

The two-step random access procedure is introduced below in terms of the channel structure in combination with a specific system.

In this embodiment, the user equipment acquires the random access configuration information in the system information, including configuration information of the preamble applied by the message A shown in <FIG>, and configuration information of the uplink shared channel in the message A.

The user equipment may generate the preamble and the uplink shared channel according to the configuration information, and may determine a transmitted power of the preamble and the uplink shared channel according to the power control parameter in the aforementioned configuration information, and may perform transmission on the configured time-frequency resource.

The user equipment may perform transmission according to the configured or preset channel structure when transmitting the preamble and the uplink shared channel constituting the message A.

Considering that the base station receives messages A from the plurality of user equipments, it is necessary to estimate a timing advance by the preamble, and to use the estimated timing advance to attempt to detect data subsequently sent on the uplink shared channel. Since the time at which a signal sent by a different user equipment arrives at the base station is inconsistent, the base station, during detection, may suffer from a severe inter-symbol interference and thus an inter-carrier interference. Therefore, the design of the channel structure of the message A needs to take the possible inter-symbol interference and the inter-carrier interference into account to reduce the influence of interference on data demodulation by improving the channel structure.

In one embodiment, there is no guard time between the preamble and the uplink shared channel. When the user equipment sends the message A including the preamble and the data payload, a possible channel structure for sending is that the message A sequentially includes a cyclic prefix <NUM>, the preamble, a cyclic prefix <NUM>, the uplink shared channel, and the guard time. In this configuration, there is no guard time between the preamble and the uplink shared channel. It should be noted that the preamble may contain multiple consecutive symbols, each symbol having a separate cyclic prefix, and the length of the cyclic prefix for each symbol being the same as the cyclic prefix <NUM>; the uplink shared channel may contain multiple consecutive symbols, each symbol having a separate cyclic prefix, and the length of the cyclic prefix for each symbol being the same as the cyclic prefix <NUM>. <FIG> illustrates the possible channel structure of the message A.

When the above structure is employed, the user equipment determines the number of symbols in preamble and the length of the cyclic prefix <NUM> according to the preamble format in the random access configuration; the user equipment selects a starting symbol position for the preamble transmission according to configuration of the random access occasion, the selected synchronization signal block, and the association between the synchronization signal block and the random access occasion; the user equipment determines the number of symbols for the uplink shared channel according to the number of symbols of the uplink shared channel of the message A in the random access configuration; the user equipment determines the length of the cyclic prefix <NUM> according to configuration in the system information.

In this configuration, the guard length may be determined in an implicit manner without additional configuration information. Specifically, the preamble and the uplink shared channel in the message A occupy multiple consecutive symbols on one or more slots. If the preamble and the uplink shared channel in the message A do not occupy all the symbols, the unoccupied symbols are used as the guard time, as the schematic diagram of configuration of the guard time illustrated in <FIG>.

In another embodiment, the guard time is provided between the preamble and the uplink shared channel. To ensure that the symbol boundary between the preamble symbol and the uplink shared channel symbol in the message A is aligned with the symbol boundary of the transmission of other channels, and that the interference between symbols of the preamble and symbols of the uplink shared channel is reduced, a guard spacing is added according to the preamble format when transmitting the preamble symbols. In this channel structure, the message A may sequentially include: the cyclic prefix <NUM>, the preamble, the guard time <NUM>, the cyclic prefix <NUM>, the uplink shared channel, and the guard time <NUM>, as another possible channel structure of the message A illustrated in <FIG>.

It should be noted that the preamble may contain multiple consecutive symbols; each symbol includes a separate cyclic prefix, and the length of the cyclic prefix for each symbol is the same as the cyclic prefix <NUM>. The uplink shared channel may contain multiple consecutive symbols; each symbol includes a separate cyclic prefix, and the length of the cyclic prefix for each symbol is the same as the cyclic prefix <NUM>.

When such channel structure is employed, the number of symbols of the preamble and the length of the cyclic prefix <NUM> are determined by the preamble format in the random access configuration; and the time and frequency domain positions of symbols of the preamble are determined by configuration information of the random access channel.

The user equipment may determine the starting time position of the uplink shared channel as follows:.

The user equipment may determine the time length of the uplink shared channel and the length of the guard time <NUM> as follows:.

When the channel structure is employed, the guard time between the preamble and the uplink shared channel is able to protect the symbols of the preamble from the inter-symbol interference and the inter-carrier interference caused by subsequent symbols of the uplink shared channel due to different arrival times of signals sent by different user equipment, and is able to protect the uplink shared channel from the inter-symbol interferences and the inter-carrier interferences caused by the symbols of the preamble.

Furthermore, this configuration enables the base station a more flexible scheduling if the guard time <NUM> is long enough. For example, if the base station does not detect the transmission of the preamble on the random access occasion of the message A, the base station may schedule the time-frequency resources of the uplink shared channel corresponding to the random access occasion to other user equipments. In this case, the guard time <NUM> needs to be long enough, and one possible example is that the guard time <NUM> is <NUM> slot.

On the basis of the above two basic structures, the user equipment may also acquire a repetition factor configured for the uplink shared channel, to transmit data on the uplink shared channel in a repetitive manner on a plurality of time units. Specifically, for example, a repetition structure may be introduced into the uplink shared channel, that is, the repetition factor Krep is configured to transmit data in the repetitive manner on a plurality of time units. The time unit can be a slot, a symbol, a mini slot, or the like. The repetition factor may be configured in the random access configuration information, or in the common uplink shared channel configuration, or in the default bandwidth part configuration.

In another possible repetition structure, Krep symbols are grouped together to change the lengths of the cyclic prefix and the symbol. For example, the length of the cyclic prefixes becomes a sum of lengths of Krep original cyclic prefixes, and the length of symbols is a sum of lengths of Krep original symbols. The new symbol may be transmitted in the repetitive manner, or the data may be transmitted in a reducing code rate, such as another possible channel structure of the message A as shown in <FIG>.

In this embodiment, the user equipment may acquire a frequency domain resource for the random access occasion occupied by the preamble and a frequency domain resource occupied by the uplink shared channel, and may reserve a guard band between neighboring frequency domain resources for the uplink shared channel.

The reserved guard band may be determined as follows. In an embodiment, the user equipment may determine the reserved guard band according to the frequency domain resource for the random access occasion, the starting index for frequency domain physical resource block of the uplink shared channel corresponding to the random access occasion, and the bandwidth identified by the number of physical resource blocks. Alternatively, the user equipment may determine the reserved guard band according to the first physical resource block index of the first uplink shared channel, the uplink shared channel bandwidth identified by the number of physical resource blocks, and the number of guard bands.

Specifically, for the frequency domain resource of the message A, the base station may jointly configure or separately configure the frequency domain resource for the random access occasion occupied by the preamble and the frequency domain resource occupied by the uplink shared channel.

For the later case (i.e., separately configuring), frequency domain resources used for the random access occasion may be determined according to the random access channel configuration, and frequency domain resources applied by the uplink shared channel may be determined according to the configuration in the system information, and an association between the uplink shared channel and the random access occasion and/or the preamble may be established.

For the frequency domain resource of the uplink shared channel, the guard band needs to be reserved between neighboring frequency domain resources to reduce inter-carrier interference caused by different user equipment timing sequences. A possible configuration manner is that when the base station configures the frequency domain resource for the random access occasion, the base station simultaneously configures the starting index for frequency domain physical resource block of the uplink shared channel corresponding to the random access occasion and the bandwidth identified by the number of physical resource blocks, as illustrated in <FIG>. In this way, the guard bandwidth between different uplink shared channels may be configured in an implicit manner.

In another possible manner, the base station configures the first physical resource block index of the first uplink shared channel, the uplink shared channel bandwidth identified by the number of physical resource blocks, and the number of guard bands. In this manner, the number of guard bands may be an integer number of physical resource blocks, or may be the number of subcarriers.

For the case where the guard bandwidth is multiple subcarriers, after acquiring the configuration information, the user equipment reserves the configured number of subcarriers at the edge of the uplink shared channel (for example, the case where guard band is the subcarrier is shown in <FIG>).

For the case where the frequency domain resource for the random access occasion and the frequency domain resource of the uplink shared channel are jointly configured, the aforementioned manner for configuring the uplink shared channel can still be applied,.

The random access method will be introduced below for the uplink shared channel.

In this embodiment, the user equipment first acquires the random access configuration information from the configuration information of the system information, wherein the random access configuration information may include the configuration information of the random access channel, the configuration information of the preamble, and the resource configuration information of the uplink shared channel for transmitting the data payload in the message A. The system information may be Remaining Minimum System Information (RMSI), or a Master Information Block (MIB), or information carried by a System Information Block (SIB).

When the user equipment acquires the random access configuration information, in addition to acquiring the configuration information of the preamble and the random access occasion, the user equipment also acquires the configuration information of the uplink shared channel for sending the data payload in the message A, such as the time-frequency resource information and the waveform configuration applied, Sub-carrier Spacing (SCS) configuration information, and the like.

Acquiring the waveform configuration of the uplink shared channel for transmitting the data payload in the message A may be performed in the following manners:.

For example, a corresponding field may be acquired from the configuration, and then the waveform configuration of the uplink shared channel may be acquired by assignment of the value of the field. One possible way is to acquire the field in the configuration information, which may be assigned with a first waveform (e.g., DFT-s-OFDM) or a second waveform (e.g., OFDM). That is, the following fields may be defined in the configuration information:
WF_MSGA = ENUMERATED {OFDM, DFT-s-OFDM}.

Where WF_MSGA is a field for configuring the waveform of the uplink shared channel in the configuration information, and ENUMERATED { } indicates an enumeration, that is, the field can be assigned a value selected from the ones defined in the parentheses. If the WF_MSGA is configured with, for example, OFDM, OFDM will be applied by the uplink shared channel in the message A; if the WF_MSGA is configured with, for example, DFT-s-OFDM, DFT-s-OFDM will be applied by the uplink shared channel in the message A. The user equipment acquires the waveform of the uplink shared channel according to the field WF_MSGA in the configuration information.

Another possible way is that an optional field such as DFT_enabled may be defined in the configuration information. This field may be assigned a value of {enabled}. If the field is not acquired by the user equipment in the configuration information (that is, the optional field is not included in the configuration information, or the optional field is invalid in the configuration information), a default waveform, such as OFDM, will be applied by the uplink shared channel for carrying the data payload in the message A. If the field is acquired by the user equipment in the system information, the DFT-s-OFDM will be applied by the uplink shared channel carrying the data payload in the message A.

Similarly, an optional field such as OFDM_enabled may be defined in the configuration information. This field may be assigned a value of {enabled}. If the field is not acquired by the user equipment in the system information (that is, the optional field is not included in the system information, or the optional field is invalid in the system information), a default waveform, such as DFT-s-OFDM, will be applied by the uplink shared channel for carrying the data payload in the message A. If the field is acquired by the user equipment in the system information, OFDM will be applied by the uplink shared channel carrying the data payload in the message A.

It should be noted that the aforementioned field defined in the configuration information may be added in the random access configuration information, in the common uplink shared channel configuration, and also in the default bandwidth part configuration.

Configuration information indicating whether a transform precoding is enabled or not may be acquired in the configuration information.

For example, the corresponding field may be acquired in the configuration information, and then according to the value of the field, whether the transform precoding is enabled or not may be determined. It should be noted that if the transform precoding is not enabled, the second waveform (such as an OFDM waveform) will be applied by the uplink shared channel part of the message A; if the transform precoding is enabled, the first waveform (such as a DFT-s-OFDM waveform) will be applied by the uplink shared channel part of the message A employs.

One possible way is to acquire fields in the configuration information, which may be assigned a value of {enabled} or {disabled}. That is, a field such as msgATransformPrecoder may be defined in the configuration information, which is applied to configure the waveform for the uplink shared channel in the message A, and is assigned a value of {enabled} or {disabled}. When the user equipment acquires the configuration information, whether the transform precoding is applied by the uplink shared channel in the message A may be determined according to the value of the field.

Another possible way is that an optional field such as msgATransformPrecoder may be defined in the configuration information. This field may be assigned a value of {enabled}. If the field is not acquired by the user equipment in the configuration information (that is, the optional field is not included in the configuration information, or the optional field is invalid in the configuration information), the transform precoding will not be applied by the uplink shared channel for carrying the data payload in the message A, that is, the second waveform such as OFDM will be applied. If the field is acquired by the user equipment in the configuration information, the transform precoding will be applied by the uplink shared channel carrying the data payload in the message A, that is, the first waveform such as DFT-s-OFDM will be applied.

A field for configuring whether the transform precoding for a message <NUM> is enabled or not, is applied to determine whether the uplink shared channel in the message A enables the transform precoding or not.

For example, the user equipment may acquire the random access configuration information, if a msg3-transformPrecoding field for configuring whether the uplink shared channel carrying a message <NUM> enables the transform precoding or not is acquired from the random access configuration information with a value of {enabled}, the transform precoding will be applied by the uplink shared channel in the message A, that is, the DFT-s-OFDM will be applied. If the field is not acquired by the user equipment in the random access configuration information, or the field is acquired with a value {disabled}, the transform precoding will not be applied by the uplink shared channel in the message A, that is, the OFDM waveform will be applied.

The UE first determines whether the resource configuration information for the four-step random access is configured in an activated uplink bandwidth part (BWP) (or carrier) allocated for the UE (i.e., whether the subcarrier spacing or the waveform! transform precoding for the message <NUM> is configured). The activated uplink BWP (or carrier) may be an initial activated uplink BWP (or carrier), or may be an activated uplink BWP (or carrier) configured by the network after the UE enters the connection state. The determination may be performed as follows:.

The UE may perform the determination according to the PUSCH (Physical Uplink Shared Channel) subcarrier spacing configuration or the waveform configuration separately configured in the resource configuration for the two-step random access, or may perform the determination according to the subcarrier spacing configuration or the waveform configuration in the configuration for the activated uplink BWP (or carrier), when the resource configuration information for the four-step random access is not contained in the activated uplink BWP (or carrier) (i.e., the subcarrier spacing configuration or the waveform configuration for the message <NUM> is not contained), and/or the resource configuration information for the two-step random access is contained in the activated uplink BWP (or carrier) (i.e., the subcarrier spacing configuration or the waveform configuration for the PUSCH for two-step random access is contained);.

The UE may perform the determination by determiningg the subcarrier spacing configuration or the waveform configuration for the PUSCH for the two-step random access according to the subcarrier spacing configuration or the waveform configuration for the message <NUM> (in this case, the UE ignores the subcarrier spacing configuration or waveform configuration, if any, separately configured for the PUSCH for the two-step random access), or may perform the determination according to the subcarrier spacing configuration or the waveform configuration for the activated uplink BWP (or carrier), when the resource configuration information for the four-step random access is contained in the activated uplink BWP (or carrier) (i.e., the subcarrier spacing configuration or the waveform configuration for the message <NUM> is contained), and/or the resource configuration information for the two-step random access is contained in the activated uplink BWP (or carrier) (i.e., the subcarrier spacing configuration or the waveform configuration for the PUSCH for the two-step random access is contained).

As described above, the resource configuration information for the two-step random access includes the configuration information of the preamble, the resource configuration information of the random access occasion, the subcarrier spacing configuration and the waveform configuration for the PUSCH for the message A. Alternatively, instead of the waveform configuration, the transform precoding configuration may be used. The resource configuration information for the four-step random access includes the configuration information of the preamble for the four-step random access, the resource configuration information of the random access occasion, the subcarrier spacing configuration and the waveform configuration for the PUSCH for the message <NUM>. Alternatively, instead of the waveform configuration, the transform precoding configuration may be used.

Some special cases of the above approach are provided:.

The user equipment may determine the waveform applied or whether the transform precoding is enabled or not according to some measurement results of the channel.

One possible way is that the user equipment may select a synchronization signal block according to the measurement result of the synchronization signal block. At the same time, the user equipment compares a reference signal received power (RSRP) obtained by measuring the synchronization signal block with a pre-configured or predefined first threshold. If the RSRP is greater than the first threshold, the second waveform such as OFDM will be applied, or the transform precoding will not be enabled; otherwise, if the RSRP is less than the first threshold, the first waveform, such as DFT-s-OFDM, will be applied, or the transform precoding will be enabled. The RSRP may be obtained by measuring a Primary Synchronous Signal (PSS) or a Secondary Synchronous Signal (SSS), or a demodulation reference signal in a broadcast channel.

Another possible way is that the user equipment may compare a path loss obtained by measuring and/or computing with a preset or pre-acquired second threshold. If the path loss is greater than the second threshold, the first waveform, such as DFT-s-OFDM, will be applied as the waveform of the uplink shared channel in the message A, or the user equipment will enable the transform precoding when the uplink shared channel in the message A is generated. Otherwise, if the path loss is less than the second threshold, the second waveform, such as OFDM, will be applied as the waveform of the uplink shared channel in the message A, or the user equipment will not enable the transform precoding when the uplink shared channel in the message A is generated.

The user equipment may acquire the aforementioned parameters as follows: for example, the user equipment may acquire the RSRP by measuring the synchronization signal block, acquire the transmitted power of the base station in the configuration information, and acquire the path loss by computing the transmitted power of the base station and the RSRP.

It should be noted that the aforementioned first threshold and the second threshold may be configured and notified by the base station in the configuration information, that is, the user equipment acquires the aforementioned first threshold or the second threshold by acquiring the configuration information. It may also be configured in a preset manner. The system information may be the random access configuration information, the common uplink shared channel configuration, or the default bandwidth part configuration information.

If the aforementioned method (i.e., the manner d) of determining the waveform of uplink shared channel in the message A according to the measurement result is applied, the reliability and effectiveness of the base station detecting the message A may be improved as follows. Possible approaches may include:.

For example, the first time-frequency resource corresponds to that OFMD is applied by the uplink shared channel or that the transform precoding is not enabled; the second time-frequency resource corresponds to that DFT-s-OFDM is applied by the uplink shared channel or that the transform precoding is enabled. The time-frequency resource group information is configured and notified in the random access configuration information, or in the common uplink shared channel configuration, or in the default bandwidth part configuration.

<NUM> the aforementioned two approaches are combined, that is, simultaneously grouping the preamble and the time-frequency resources of the uplink shared channel, establishing associations between the respective groups and the waveform applied by the uplink shared channel in the message A, or establishing associations between the respective groups and whether the transform precoding is enabled or not. Correspondingly, the user equipment may obtain associations between the first preamble group and the second preamble group of the first message, the first and the second time-frequency resources for the uplink shared channel in the first message and the waveform configuration of the uplink shared channel or whether the transform precoding is enabled or not.

For example, the first preamble group and the first time-frequency resource correspond to that OFMD is applied by the uplink shared channel or that the transform precoding is not enabled; the second preamble group and the second time-frequency resource correspond to that DFT-s-OFDM is applied by the uplink shared channel or that the transform precoding is enabled. The aforementioned grouping information may be configured and notified in the system information. For example, the preamble group information and the time-frequency resource group configuration information of the uplink shared channel in the message A are configured and notified in the random access configuration information; alternatively, the preamble group information is configured and notified in the random access configuration information, and the time-frequency resource group configuration information of the uplink shared channel in the message A is configured and notified in the common uplink shared channel configuration or the default bandwidth part configuration information.

A subcarrier spacing applied by the uplink shared channel in the message A may be determined as follows.

Specifically, the configuration information for configuring the subcarrier spacing for the uplink shared channel in the message A is added to the configuration information of the system information, and the user equipment then determines the subcarrier spacing according to the added configuration information. The configuration information may be added in the random access configuration information, or in the common uplink shared channel configuration or in the common uplink bandwidth part configuration information.

The user equipment acquires the configuration information in the system information, acquires the random access configuration information, obtains the configuration of the preamble and the time-frequency configuration of the uplink shared channel in the message A, and according to the aforementioned manners, obtains the waveform and the subcarrier spacing applied by the uplink shared channel in the message A, generates the message A, and transmits the preamble and the uplink shared channel on the aforementioned configured time-frequency resources.

Hereinafter, the random access method will be described in combination with scrambling.

In this embodiment, the user equipment acquires the random access configuration information in the system information, including the configuration information of the preamble applied by the message A, and the configuration information of the uplink shared channel in the message A.

The user equipment generates the preamble and the uplink shared channel according to the configuration information, and performs transmission on a configured time-frequency resource.

When generating data of the uplink shared channel, the user equipment may scramble bit data, according to information, such as the time-frequency resource for transmitting the random access occasion and/or the time-frequency resource for the uplink shared channel and/or the preamble and/or the demodulation reference signal and the like. The scrambling process is as follows:
For bit data b(<NUM>),. , b(Mbit-<NUM>), Mbit representing the number of bits, scrambling data b̃(<NUM>),. ,b̃(Mbit-<NUM>) is generated before the bit data is modulated, wherein
<MAT>.

Where the operation mod represents a modulo operation. The sequence c(i), i=<NUM>,. Mbit-<NUM> is a scrambling sequence, which is a Gold sequence generated as follows. <MAT><MAT><MAT>.

Where parameter Nc is a preset parameter or a parameter configured by the base station, and one possible value of the parameter is Nc= <NUM>. x<NUM>(n) and x<NUM>(n) are two m sequences. The initialization state of the first m sequence x<NUM>(n) is x<NUM>(<NUM>)=<NUM>, x<NUM>(n)=<NUM>, n=<NUM>,<NUM>,. The initialization state of the second m sequence x<NUM>(n) is expressed as <MAT>, with a value determined by the following manner.

If a data scrambling indication "Data-Scrambling-identifier" for the message A is configured in the system information, the value of nID is the same as the value of the data scrambling indication. Otherwise, nID is equal to the cell ID. The data scrambling indication for the message A may be configured and notified in the random access configuration information, or may be configured and notified in the common uplink shared channel configuration or the default bandwidth portion configuration information.

The data scrambling indication parameter nRNTI can be determined by the following manners.

In this manner, the parameter nRNTI is determined by the time-frequency resource position of the random access occasion. If the message A is sent only on normal uplink (UL) carriers, nRNTI may be calculated by the following equation:
<MAT>
where y<NUM> is the initial value, which has a possible value y<NUM>=<NUM>; sid is a symbol index of the first symbol of the random access occasion, and its value range is <NUM>≤sid<Ns; Ns is the maximum number of symbols of slots carrying the random access occasion, which has a possible value Ns=<NUM>; tid is the slot index of the first slot of slots in which the random access occasion is located, and its value range is <NUM>≤tid<Nt with Nt being the maximum number of slots in the radio frame in which the random access occasion is located and having a possible value Nt=<NUM>; fid is a frequency domain index of the random access occasion, and its value range is <NUM>≤fid<Nf, with Nf being the maximum number of the random access occasions on the frequency domain and having a possible value Nf=<NUM>.

If the message A may be sent on multiple uplink carriers, nRNTI may be calculated by the following equation:
<MAT>.

Where ULid is an uplink carrier index. One possible example is that there are two uplink carriers in the system for the transmission of the message A, including a normal uplink carrier (NUL) and a supplemental uplink carrier (SUL), then ULid is <NUM> to indicate NUL and ULid is <NUM> to indicate SUL.

The parameter nRNTI is determined according to a time-frequency resource position for transmitting the uplink shared channel in the message A.

In this manner, the parameter nRNTI is determined by the time-frequency resource position of the uplink shared channel. A possible calculation approach may include:
<MAT>.

Wherein, y<NUM> is the initial value, which has a possible value y<NUM>=<NUM>; tid is the slot index of the first slot of the uplink shared channel, and its value range is <NUM>≤tid<Nt, that is, Nt is the maximum number of slots in the radio frame; fid is a frequency domain index for transmitting the uplink shared channel in the message A on the frequency domain.

For a case where there are multiple available uplink carriers, the above equation may be modified to:
<MAT>.

This manner is suitable for a case where time domain boundaries of the uplink shared channel are aligned with slot boundaries, that is, a time unit of the uplink shared channel in the message A is a slot.

For a case where the mini-slot is applied as a scheduling unit, the parameter nRNTI may be calculated as follows:
<MAT>.

Where sid is, in one slot, the first symbol index of the uplink shared channel, and Ns represents the maximum number of symbols available in one slot; in another representation manner, sid is, in one slot, the time domain index of the uplink shared channel, and Ns represents the number of uplink shared channels available in one slot.

For the case where there are multiple available uplink carriers, the above equation may be modified to:
<MAT>.

In order to avoid the same scrambling code is applied, by the user equipment occupying the same time-frequency resources for the uplink shared channel, to scramble the data, the port index of the demodulation reference signal may be introduced on the basis of the aforementioned approach.

At this point, the aforementioned first calculation approach for the nRNTI may be corrected to:
<MAT>.

Where nDMRS is the port index of the demodulation reference signal applied by the uplink shared channel in message A.

For the case where there are multiple available uplink carriers, the first calculation approach for the nRNTI may be corrected to:
<MAT>.

The aforementioned second calculation approach for the nRNTI may be corrected to:
<MAT>.

For the case where there are multiple available uplink carriers, the second calculation approach for the nDMRS may be corrected to:
<MAT>.

The parameter nRNTI is determined based on the preamble in the message A.

The parameter nRNTI is determined based on a selected preamble sequence index in the message A. That is, if the preamble sequence index selected by the user equipment is RAPID, nRTNI=RAPID.

Considering that the preamble sequence index has a small value range, the calculation approach may be applied in combination with the aforementioned manners.

For example, the parameter nRNTI is calculated by the time-frequency resource position of the random access occasion and the preamble sequence index. Specifically, a parameter nRNTI' is calculated by the aforementioned manner a, and then the parameter nRNTI may be calculated as:
<MAT>.

Where M'RNTI is the maximum value of nRNTI'.

Alternatively, the parameter nRNTI is calculated by the time-frequency resource position of the uplink shared channel and the preamble sequence index. Specifically, the parameter nRNTI' is calculated by the aforementioned manner b, and then the parameter nRNTI may be calculated as:
<MAT>.

Alternatively, the parameter nRNTI is calculated according to a port index of the demodulation reference signal applied by the uplink shared channel, and the preamble sequence index, which may be described in detail as follows:
<MAT>.

Alternatively, the parameter nRNTI is calculated according to a time-frequency position of the random access occasion and a time-frequency position of the uplink shared channel. Specifically, a parameter
<MAT>
is calculated by the aforementioned manner a, and a parameter
<MAT>
is calculated by the aforementioned manner b, and then the parameter nRNTI may be calculated as:
<MAT>.

Where
<MAT>
is the maximum value of
<MAT>.

Alternatively, the parameter nRNTI is calculated according to the time-frequency resource position of the random access occasion and the port index of the demodulation reference signal applied by the uplink shared channel. Specifically, the parameter
<MAT>
is calculated by the aforementioned manner a, and then the parameter nRNTI may be calculated as:
<MAT>.

In addition to scrambling the data to be transmitted using the scrambling code, the scrambling may be replaced with bit-level interleaving. By defining a plurality of bit-level interleaving patterns, and defining associations between the random access preamble sequence index and the interleaving patterns, the user equipment acquires the corresponding interleaving pattern by selecting the preamble, and performs bit-level scrambling on the bit data to be transmitted; the base station acquires the bit-level interleaving pattern applied by the uplink shared channel by detecting the preamble, and performs data detection. The bit-level interleaving pattern configuration and the association between the interleaving pattern and the preamble sequence index are all configured and notified in the system information.

Hereinafter, the random access method will be introduced in combination with the power control.

The user equipment generates the preamble and the uplink shared channel according to the configuration information, and determines the transmitted power of the preamble and the uplink shared channel according to the power control parameter in the aforementioned configuration information, and performs transmission on the configured time-frequency resource. For example, the user equipment may determine the transmitted power of the uplink shared channel in the first message according to a sum of the power rampups of the single physical resource block.

The user equipment determines the transmitted power of the uplink shared channel in the message A according to the following manner:
<MAT>.

Where parameter PCMAX is the configured transmitted power of the user equipment, i.e., the maximum transmitted power of the user equipment.

The parameter PO_PUSCH is calculated as follows:
<MAT>.

Where PO_PRE is a preamble initial received target power, preamble InitialReceivedTargetPower, configured by a high layer, ΔPrampup is a sum of the power rampups calculated from the first attempt for transmitting first message to the current attempt for transmitting first message, and ΔPREAMBLE_MSG<NUM> is parameter Delta-preamble-msg3 configured by a high layer, to characterize power difference between the preamble and the message <NUM>, and it is applied to characterize the power difference between the preamble in the message A and the uplink shared channel in the message A when the message A is transmitted. The parameter Delta-preamble-msg3 is configured and notified in the system information.

In another approach, a parameter PO_PUSCH is calculated as follows:
<MAT>.

Where the meanings of PO_PRE and ΔPrampup are the same meaning as the aforementioned ones. ΔPREAMBLE_MSGA A parameter is configured by a high layer to characterize the power difference between the preamble in the message A and the uplink shared channel in the message A. This parameter can be configured and notified in the system information. For example, the parameter is added in the random access configuration information to configure the power difference between the preamble in the message A and the uplink shared channel in the message A; alternatively, the parameter is configured in the common uplink shared channel configuration or configured and notified in the default bandwidth portion configuration information, to configure the power difference between the preamble in the message A and the uplink shared channel in the message A.

Parameter <MAT> is the number of physical resource blocks occupied by the uplink shared channel bandwidth in the message A. Parameter µ is a parameter for configuring the subcarrier spacing of the uplink shared channel in the message A, and is configured and notified through the system information.

Parameter PL is the path loss calculated by the user equipment according to the RSRP and the transmitted power of the base station which is configured by a high layer signaling. Parameter α is the power control parameter configured by the high layer signaling or set in advance.

In some possible cases, if, after transmitting the message A, the user equipment detects the random access response matching the preamble in the message A within a detection window after a pre-configured or predefined time, the user equipment transmits the message <NUM> on the responded time-frequency resource according to an uplink grant command contained in the random access response.

The transmitted power of the message <NUM> may be determined in the following manner.

The transmitted power PPUSCH of the message <NUM> is calculated as:
<MAT>.

Where PO_PRE is the preamble Initial Received Target Power, preamble Initial-ReceivedTargetPower, configured by the high layer, and ΔPREAMBLE_MSG<NUM> is the parameter Delta-preamble-msg3 configured by the high layer, to characterize the power difference between the preamble and the message <NUM>.

Parameter <MAT> is the number of physical resource blocks occupied by the uplink shared channel bandwidth in the message <NUM>. Parameter µ is a parameter for configuring the subcarrier spacing of the uplink shared channel in the message <NUM>, and is configured and notified through the system information.

Parameter f(i) is cumulative power control parameter of the ith transmission period, and the calculation approach for the parameter is as follows:
<MAT>.

Where δPUSCH(i-KPUSCK) is the power control parameter configured by the base station in the downlink control channel within a transmission period before KPUSCK.

Where ΔPrampup is a sum of the power rampups calculated from the first attempt for transmitting first message to the current attempt for transmitting first message, and δmsg<NUM> is the power control parameter in the uplink grant command contained in the random access response.

<FIG> schematically illustrates a schematic diagram of a random access method according to an embodiment of the present disclosure.

The random access method is performed on the base station side. The random access method includes: in step S1001, transmitting the configuration information; in step S1002, receiving the first message including the preamble and the uplink shared channel, which is transmitted by the user equipment according to the configuration information; and in step S1003, transmitting the second message including the contention resolution information to the user equipment.

The configuration information may be configuration information in the system information transmitted by the base station to the user equipment, and the channel structure for transmitting the message A may be acquired according to the configuration information, wherein the channel structure includes the preamble, the uplink shared channel, and the guard time.

In an embodiment, the base station may configure, in the configuration information, the number of time units and/or the time unit index of the uplink shared channel, configure the number of slots of the uplink shared channel and the number of symbols in the last slot, or configure the number of slots of the uplink shared channel and the number of symbols of the uplink shared channel.

The base station may also configure the repetition factor for the uplink shared channel.

The user equipment may configure the frequency domain resource for the random access occasion occupied by the preamble and the frequency domain resource occupied by the uplink shared channel, and configure the guard band reserved between neighboring frequency domain resources for the uplink shared channel.

Configuring the reserved guard band may comprises: configuring the frequency domain resource for the random access occasion, the starting index for frequency domain physical resource block of the uplink shared channel corresponding to the random access occasion, and the bandwidth identified by the number of physical resource blocks. Configuring the reserved guard band may further comprise: configuring the first physical resource block index of the first uplink shared channel, the uplink shared channel bandwidth identified by the number of physical resource blocks, and the number of guard bands.

The field or optional field indicating the waveform configuration may also be configured in the configuration information; or the field or optional field indicating whether the transform precoding is enabled or not may also be configured in the configuration information.

The base station may also configure, in the configuration information, a parameter for characterizing the power difference between the preamble and the message <NUM> and a parameter for characterizing the power difference between the preamble in the first message and the uplink shared channel in the first message.

The configuration information may include the random access configuration information, the common uplink shared channel configuration information, or the default bandwidth portion configuration information.

In the context, the features included in the embodiment method suitable for the user equipment side may also be appropriately used for the embodiment method and apparatus on the base station side to avoid duplication as appropriate.

<FIG> schematically illustrates a schematic diagram of a user equipment <NUM> according to an embodiment of the present disclosure.

The user equipment <NUM> includes a processor <NUM> and a memory <NUM> that stores computer executable code that, when executed by the processor, performs the random access method on the user equipment side as described above.

<FIG> schematically illustrates a schematic diagram of a base station <NUM> according to an embodiment of the present disclosure.

The base station device <NUM> includes a processor <NUM> and a memory <NUM> that stores computer executable code that, when executed by the processor, performs the random access method on the base station side as described above.

The present disclosure further provides a computer readable medium storing instructions, when executed by the processor, performing the random access method on the user equipment side or the base station side according to the aforementioned embodiments of the present disclosure.

The "memory" herein may be of any type suitable for the technical environment herein, and may be implemented using any suitable data storage technology, including but not limited to semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memories and removable memories.

The processor herein may be of any type suitable for the technical environment herein, including but not limited to one or more of the following: a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor DSP, and a multi-core processor architecture based processor.

"Computer-readable medium" herein should be considered to include any medium or combination of a plurality of mediums capable of storing instructions executed by a computer, or a device capable of storing instructions and data temporarily or permanently, and may include, but is not limited to, random storage Memory (RAM), read only memory (ROM), buffer memory, flash memory, optical media, magnetic media, cache memory, other types of memory (e.g., erasable programmable read only memory (EEPROM)), and/or any suitable combination thereof. "Computer-readable medium" may refer to a single storage or memory device and/or a "cloud-based" storage system or storage network that includes a plurality of storages or memory devices.

The terminology used herein is for the purpose of describing the particular embodiments, and not intended to limit the disclosure. In addition, the terms "including", "comprising", etc., are used to indicate the presence of the described features, steps, operations and/or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

Each block in the flowchart or block diagram in the embodiments of the present disclosure may represent a hardware module, a program segment, or a portion of code, and the above-described module, program segment, or a portion of code may include one or more executable instructions for implementing specified logical functions. It should also be noted that, in some alternative implementations, the functions noted in the flowcharts and blocks may also occur in a different order than those illustrated in the drawings. For example, two successively represented blocks may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It is also noted that each block of the block diagrams or flowcharts, and combinations of blocks in the block diagrams or flowcharts, can be implemented by a dedicated hardware-based system that performs a specified function or operation, or may be implemented by a combination of a dedicated hardware and computer instructions.

Claim 1:
A method (<NUM>) performed by a terminal in a (<NUM>) communication system, the method comprising:
receiving (S401), from a base station (<NUM>), system information including configuration for a message A, MsgA, of a two-step random access procedure, the MsgA including a preamble on a physical random access channel, PRACH, and a payload on a physical uplink shared channel, PUSCH, in the two-step random access procedure;
transmitting (S402), to the base station (<NUM>), the PRACH and the PUSCH based on the configuration; and
receiving (S403), from the base station (<NUM>), a response for the PRACH and the PUSCH; and
wherein whether to apply a transform precoding for the PUSCH of the MsgA is determined based on the configuration for the MsgA, in case that the configuration for the MsgA includes information indicating whether to apply the transform precoding for the PUSCH of the MsgA, and
wherein whether to apply a transform precoding for the PUSCH of the MsgA is determined based on a configuration for a message <NUM>, Msg3, of a four-step random access, in case that the configuration for the MsgA does not include the information indicating whether to apply the transform precoding for the PUSCH of the MsgA.