Random access response transmission and reception techniques

Abstract

Techniques for transmission and reception of random access response (RAR) messages are described. An example wireless communication method includes performing, by a communication device, transmissions over a plurality of random access channels; and receiving a message responsive to transmissions over a plurality of random access channels, where after the message is received, a transmit beam used by a communication device to perform subsequent transmissions is identified by information scrambled by the message, identified by information included in the message, or associated with a time domain location of the message, and where the transmit beam is not scrambled by the message. The transmit beam is used for transmission of one of the plurality of random access channels.

Description

Technical Field

[0001] The present disclosure relates generally to digital wireless communications. Background Art

[0002] Mobile telecommunication technologies are driving the world towards an increasingly connected and networked society. Compared to existing wireless networks, next-generation systems and wireless communication technologies will need to support a wider range of use case characteristics and provide more complex and sophisticated access requirements and flexibility.

[0003] Long-Term Evolution (LTE) is a wireless communication standard for mobile devices and data terminals developed by the 3rd Generation Partnership Project (3GPP). LTE Advanced (LTE-A) is a wireless communication standard that enhances the LTE standard. The fifth-generation wireless system, known as 5G, advances the LTE and LTE-A wireless standards and is committed to supporting higher data rates, a large number of connections, ultra-low latency, high reliability, and other emerging business needs. Summary of the invention

[0004] Techniques for random access response transmission and reception are disclosed.

[0005] A first wireless communication method includes performing transmissions on multiple random access channels by a communication device; and receiving messages in response to the transmissions on the multiple random access channels, wherein, after the message is received, a transmit beam to be used by the communication device to perform subsequent transmissions is identified by information with which the message is scrambled, identified by information included in the message, or associated with a time domain position of the message, and wherein the transmit beam is used for transmission of one random access channel among the multiple random access channels.

[0006] In some embodiments, the message is a random access response (RAR), the information with which the RAR is scrambled is a random access radio network temporary identifier (RA-RNTI), and the RA-RNTI is a function of the symbol index of the random access channel opportunity, the slot index of the random access channel opportunity, the frequency index of the random access channel opportunity, the carrier index of the random access channel opportunity, and an identifier of the transmit beam. In some embodiments, the message is a random access response (RAR) received in a time window that begins after transmissions on multiple random access channels are performed, and the information with which the RAR is scrambled is a random access radio network temporary identifier (RA-RNTI) associated with the random access channel on which the transmission is performed using the transmit beam. In some embodiments, the message is a random access response (RAR) that includes an identifier of the transmit beam in a medium access control (MAC) protocol data unit (PDU). In some embodiments, the identifier of the transmit beam is included in the MAC RAR content in the MAC PDU of the RAR.

[0007] In some embodiments, the time domain position of the message is associated with one of a plurality of control channel monitoring opportunities included in the time window, the communication device determines the identifier of the transmit beam based on the number or index associated with the control channel monitoring opportunity at which the message is received, and the number or index of the control channel monitoring opportunity is part of a series of numbers or a series of indices associated with a plurality of control channel monitoring opportunities. In some embodiments, the control channel monitoring opportunity is associated with a synchronization signal block (SSB), and the SSB is associated with a plurality of random access channels. In some embodiments, the identifier of the transmit beam is determined using the following equation: Identifier of the transmit beam = number or index associated with the control channel monitoring opportunity at which the message is received modulo the total number of the plurality of random access channels.

[0008] In some embodiments, a series of numbers or a series of indices associated with multiple control channel monitoring opportunities are counted or determined by the communication device. In some embodiments, the communication device counts or determines a series of numbers or a series of indices of multiple control channel monitoring opportunities from a reference point in the time window until the end of the time window. In some embodiments, the reference point is located at the start time of the time window, or the reference point is located at a time slot boundary, a subframe boundary, a frame boundary, or a multi-frame boundary in the time window. In some embodiments, the control resource set (CORESET) used by the message is associated with the transmit beam, or the search space set used by the message is associated with the transmit beam. In some embodiments, the message includes a demodulation reference signal (DMRS) sequence associated with the transmit beam. In some embodiments, the message is a random access response (RAR), and the communication device receives downlink control information (DCI), which includes an identifier of the transmit beam and is associated with the RAR.

[0009] A second wireless communication method, comprising receiving, by a network device, transmissions on multiple random access channels from a communication device; and transmitting a message in response to receiving the transmissions on the multiple random access channels, wherein a transmit beam used by the communication device to perform subsequent transmissions to be received by the network device is identified by information with which the message is scrambled, by information included in the message, or associated with a time domain position of the message, wherein the network device receives a transmission on one of the multiple random access channels, and wherein a transmit beam is used for the transmission.

[0010] In some embodiments, the message is a random access response (RAR), the information with which the RAR is scrambled is a random access radio network temporary identifier (RA-RNTI), and the RA-RNTI is a function of a symbol index of a random access channel opportunity, a slot index of the random access channel opportunity, a frequency index of the random access channel opportunity, a carrier index of the random access channel opportunity, and an identifier of a transmit beam. In some embodiments, the message is a random access response (RAR) transmitted in a time window that begins after a transmission on a plurality of random access channels is received, and the information with which the RAR is scrambled is a random access radio network temporary identifier (RA-RNTI) associated with the random access channel on which a transmission using the transmit beam is received.

[0011] In some embodiments, the message is a random access response (RAR) that includes an identifier of a transmit beam in a medium access control (MAC) protocol data unit (PDU). In some embodiments, the identifier of the transmit beam is included in the MAC RAR content in the MAC PDU of the RAR. In some embodiments, the time domain location of the message is in a control channel monitoring opportunity from a plurality of control channel monitoring opportunities included in the time window, the identifier of the transmit beam is based on a number or index associated with the control channel monitoring opportunity at which the message is transmitted, and the number or index of the control channel monitoring opportunity is part of a series of numbers or a series of indices associated with a plurality of control channel monitoring opportunities. In some embodiments, the control channel monitoring opportunity is associated with a synchronization signal block (SSB), and the SSB is associated with a plurality of random access channels.

[0012] In some embodiments, the identifier of the transmit beam is based on the following equation: Identification of the transmit beam = number or index associated with the control channel monitoring opportunity at which the message is transmitted modulo the total number of multiple random access channels. In some embodiments, the control resource set (CORESET) used by the message is associated with the transmit beam, or the search space set used by the message is related to the transmit beam. In some embodiments, the message includes a demodulation reference signal (DMRS) sequence associated with the transmit beam. In some embodiments, the message is a random access response (RAR), and the network device transmits downlink control information (DCI), which includes the identifier of the transmit beam and is associated with the RAR.

[0013] A third wireless communication method includes receiving a cyclic prefix and multiple preambles by a network device; after receiving the cyclic prefix and the multiple preambles, transmitting multiple random access responses (RARs), wherein each RAR includes a timing advance (TA) command, the command including a TA value corresponding to one of a plurality of round-trip delays, wherein each round-trip delay is associated with one of a plurality of detection windows, and wherein each detection window is associated with the reception of a different set of preambles in the plurality of preambles; in response to transmitting the multiple RARs, receiving a first message based on a TA value associated with a TA command from a RAR; and in response to receiving the first message, transmitting a second message indicating that the first information is received.

[0014] A fourth wireless communication method includes transmitting, by a communication device, a cyclic prefix followed by a plurality of preambles in a time domain; receiving, after transmitting the cyclic prefix and the plurality of preambles, a plurality of random access responses (RARs), wherein each RAR includes a timing advance (TA) command; transmitting, in response to receiving the plurality of RARs, a plurality of messages, wherein each of the plurality of messages is based on a TA value associated with a TA command from a RAR; and receiving, in response to transmitting the plurality of messages, a message indicating that a message is received from the communication device, wherein the one message is from the plurality of messages.

[0015] In some embodiments, the TA command for each RAR is associated with one of a plurality of round trip delays, each round trip delay is associated with one of a plurality of detection windows of the network device, and each detection window is associated with a different set of preambles in a plurality of preambles. In some embodiments, the TA command includes a TA value corresponding to one of the plurality of round trip delays.

[0016] In another exemplary aspect, the above method is embodied in the form of processor executable code and stored in a non-transitory computer readable storage medium. When executed by a processor, the code included in the computer readable storage medium causes the processor to implement the method described in this patent document.

[0017] In yet another exemplary embodiment, a device configured or operable to perform the above method is disclosed.

[0018] The above-mentioned aspects and other aspects and embodiments thereof are described in more detail in the drawings, the description and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A scenario is shown in which a user equipment (UE) transmits (Tx) beams and receives (Rx) beams correspondingly.

[0020] Figure 2 A scenario is shown where the UE Tx beam and Rx beam do not correspond.

[0021] Figure 3 A physical random access channel (PRACH) format C2 is shown.

[0022] Figure 4 It is shown that before the base station transmits a random access response (RAR) to the UE, the UE sends PRACH repetitions using different beams.

[0023] Figure 5 A single RAR window corresponding to an entire PRACH transmission with repetitions is shown, where the single RAR window starts after the end of the last symbol of the last PRACH repetition.

[0024] Figure 6 It is shown that each of the multiple RAR windows corresponds to one of the multiple PRACH repetitions.

[0025] Figure 7 is a diagram showing an example of a configuration of a physical downlink control channel (PDCCH) monitoring opportunity.

[0026] Figure 8 UE Tx beam indication using PDCCH monitoring opportunity (MO) positions is shown, which the UE can count from the start of the RAR window.

[0027] Fig. 9 It is shown that the number of PRACH repetitions is the same as the number of MOs used for RAR in one frame.

[0028] Fig.10 An example of an MO indexing period with two frames is shown, where indexing starts at the even frame and ends at the odd frame.

[0029] Fig.11 It is shown that when the relationship between the synchronization signal block (SSB) and the MO of the PDCCH has been defined, the UE Tx beam indication is performed using the PDCCH MO position that the UE can count from the start of the RAR window.

[0030] Fig.12 The conventional behavior of gNB detecting PRACH is shown.

[0031] Fig.13 A scenario is shown in which the coverage limited by the cyclic prefix (CP) length is extended by using a part of the preamble as a supplementary CP.

[0032] Fig.14 A solution to the ambiguity of multiple round trip delays (RTDs) is shown.

[0033] Fig.15 An example procedure when PRACH repetition is applied is shown.

[0034] Fig.16 An example of wireless communication including a base station (BS) and a user equipment (UE) based on some embodiments of the disclosed technology is shown.

[0035] Fig.17 An exemplary block diagram of a hardware platform that may be part of a network device or a communication device is shown.

[0036] Fig.18 An exemplary flow diagram for receiving a message identifying a transmit beam for a transmission is shown.

[0037] Fig.19 An exemplary flow diagram for transmitting a message identifying a transmit beam of a communication device is shown.

[0038] Fig. 20 An exemplary flow diagram for receiving a message based on a timing advance (TA) value is shown.

[0039] Fig.21 An exemplary flow chart for transmitting a message based on a TA value is shown. DETAILED DESCRIPTION

[0040] In mobile communication networks, such as New Radio (NR), enhancing the cell's larger coverage or reducing the access delay of the initial access technology is one of the main challenges. When the UE transmit beam and the receive beam may not correspond (for example, the UE antenna reciprocity is not satisfied), after the previous random access channel (RACH) transmission fails, the UE will try to perform RACH retransmission using a different transmit beam. Retransmissions will be performed until the UE finds a suitable transmit beam, but the initial access delay caused by the retransmission may not meet the system requirements.

[0041] For some large cell coverage scenarios, for example, super cells with a cell radius of more than 100 km are required in the frequency band below 6 GHz, or fixed wireless access with a cell diameter of more than 1 km is required in the microwave band, the cell coverage is limited by the maximum cyclic prefix (CP) length allowed by the current physical random access channel (PRACH) format.

[0042] NR introduces a basic scheme to support initial access in FR1 (frequency bands below 6 GHz) and FR2 (frequency bands above 6 GHz). The scheme may include different PRACH formats, PRACH resource configurations, the relationship between SSB and PRACH, PRACH retransmission mechanisms, PRACH power control mechanisms, etc.

[0043] However, the RACH process in the basic scheme only considers that the UE transmit beam and receive beam correspond. If the UE's transmit beam and receive beam do not correspond (which is likely to happen when the UE operates in the millimeter wave (mm wave) band), the only way for the UE to find a suitable transmit beam is to try a RACH retransmission using a different beam after the previous RACH transmission failed.

[0044] Figure 1It shows that the UE Tx beam and Rx beam are corresponding, and the best Tx beam and Rx beam are the same, where the IDs are both "1".

[0045] Figure 2 It shows that when the UE Tx beam and Rx beam do not correspond, the first available Tx beam ID is "2", but the best Rx beam ID is "1". The first msg1 reception fails because the gNB cannot receive msg1 from the unsuitable Tx beam "1" of the UE. After the failure, msg1 needs to be retransmitted until the first available UL Tx beam "2" is selected. When the UE tries to find the first available Tx beam through Tx beam switching, the delay of initial access will be extended.

[0046] Figure 3 PRACH format C2 is shown. The current PRACH format design only considers that the CP length will not exceed the length of one OFDM symbol, for example, 2048κ·2 -μ , but the current CP length does not support extreme coverage requirements. For example, format C2 is commonly used in the millimeter wave band to support fixed wireless access (FWA). With a subcarrier spacing (SCS) of 120KHz, the CP length can support a cell radius of up to about 1.15km, which is smaller than the requirements of a typical FWA scenario. In actual deployment, FWA may require a transmission distance of up to 10km between the base station and the UE.

[0047] The example titles of the following sections are used to facilitate understanding of the disclosed subject matter and do not limit the scope of the claimed subject matter in any way. Therefore, one or more features of one example section can be combined with one or more features of another example section. In addition, for clarity of explanation, 5G terminology is used, but the technology disclosed in this document is not limited to 5G technology and can be used in wireless systems implementing other protocols.

[0048] I. Example #1: PRACH repetition using different beams

[0049] In the above, if the UE transmit beam and receive beam do not correspond, the UE must try to use a different beam for RACH retransmission after each failure of the previous RACH transmission to find a suitable transmit beam. The process of finding a suitable transmit beam is a Tx beam switching based on the PRACH retransmission mechanism. In order to reduce the delay of initial access, the Tx beam switching is expected to be completed within the first transmission cycle, and there is no need to switch the Tx beam in the next transmission cycle. This method is also regarded as PRACH (msg1) repetition using different beams in the first round of transmission cycles.

[0050] Figure 4 It is shown that before the base station transmits a random access response (RAR) to the UE, the UE sends PRACH repetitions using different beams. For example, six PRACH repetitions sharing the same preamble index (in other embodiments, the preamble index may also be different between PRACH repetitions using different beams) are transmitted to the gNB, and the gNB selects a suitable repetition reception based on the reception quality (such as RSRP / SNR of PRACH), determines the appropriate UL Tx beam ID for the next UL transmission, and indicates the appropriate UL Tx beam ID to the UE through the RAR. The appropriate UL Tx beam ID may belong to the best repetition reception (e.g., from Tx beam ID "6") or the first repetition reception whose RSRP / SNIR exceeds the threshold (e.g., from Tx beam ID "2"), etc. The determination criteria depends on the implementation of the gNB.

[0051] According to the conventional RACH procedure, RAR or msg2 / msgA should be after the end of PRACH transmission, and the RAR window starts from the first symbol of the earliest CORESET where the UE is configured to receive PDCCH for Type1-PDCCH CSS set, i.e. at least one symbol after the last symbol of the PRACH opportunity corresponding to the PRACH transmission. When PRACH repetition is applied, the determination of the last symbol of the PRACH opportunity can be the last symbol of the first PRACH repetition, or if all PRACH repetitions are regarded as the entire PRACH / msg1 transmission, it can be the last symbol of the last PRACH repetition. Obviously, it is better to determine the last symbol of the last PRACH repetition as the end of the entire PRACH transmission. Therefore, there is only one RAR window corresponding to the entire PRACH transmission.

[0052] Figure 5 A single RAR window corresponding to an entire PRACH transmission with repetitions is shown, where the single RAR window starts after the end of the last symbol of the last PRACH repetition. In other words, the RAR window starts at the first symbol of the earliest CORESET for which the UE is configured to receive a PDCCH for a Type 1-PDCCH CSS set, which is at least a predefined number of symbols after the end of the last symbol of the last PRACH opportunity of the PRACH transmission.

[0053] In another way, all PRACH repetitions are considered as separate PRACH transmissions, and each PRACH repetition may have a corresponding RAR window also based on the conventional procedure.

[0054] Figure 6It is shown that each of the multiple RAR windows corresponds to one of the multiple PRACH repetitions. For example, RAR window 1 can correspond to PRACH repetition 1, RAR window 2 can correspond to PRACH repetition 2, and so on. The gNB can transmit a response to any PRACH repetition in any RAR window. In this RAR window, the UE detects a PDCCH scrambled by the RA-RNTI for the response message to the PRACH repetition. In addition, the PDSCH for the response message to the PRACH repetition is scrambled by the RA-RNTI. The traditional RA-RNTI associated with the PRACH opportunity at which the random access preamble is transmitted is calculated as follows:

[0055] RA-RNTI = 1 + s_id + 14 × t_id + 14 × 80 × f_id + 14 × 80 × 8 × ul_carrier_id where s_id is the symbol index of the PRACH opportunity, t_id is the slot index of the PRACH opportunity, f_id is the frequency index of the PRACH opportunity, and ul_carrier_id is the carrier index of the PRACH opportunity. Figure 6 As shown, since multiple RAR windows overlap each other, if the UE receives a RAR in one of the RAR windows, the UE cannot easily determine which transmit beam is indicated by the PDCCH scrambled by the RA-RNTI in the RAR if the RA-RNTI is calculated using the above equation. The RA-RNTI calculation can distinguish each PRACH repetition, and the conventional process processes each PRACH repetition as a normal PRACH transmission.

[0056] In some other scenarios where there is only one RAR window corresponding to the entire PRACH repetition transmission utilizing different beams, if the RA-RNTI calculation is based on the last PRACH repetition, the UE may have some difficulty distinguishing which RAR corresponds to which PRACH repetition, and the UE may have difficulty determining which UE Tx beam is suitable for gNB reception. There are several alternatives to address this issue to distinguish which PRACH repetition the RAR belongs to.

[0057] Alternative 1: Modify RA-RNTI calculation with beam ID.

[0058] The conventional RA-RNTI calculation is based on the symbol index of the PRACH opportunity, the slot index of the PRACH opportunity, the frequency index of the PRACH opportunity, and the carrier index of the PRACH opportunity as described above. Information about the UE Tx beam ID can be added to the RA-RNTI calculation, assuming that the maximum number of beams is 8, for example, the RA-RNTI calculation can be modified as follows:

[0059] RA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id+14×80×8×8×beam ID

[0060] Alternative 2: RAR transmission with RA-RNTI corresponding to one of multiple PRACH repetitions.

[0061] Only one RAR window is defined corresponding to the entire PRACH repetition transmission. And the starting point of the RAR window is determined only based on the last PRACH repetition. However, one of the RA-RNTIs corresponding to multiple PRACH repetitions can be used to scramble the PDCCH for RAR transmission, that is, each RA-RNTI is calculated based on each PRACH repetition. There is a one-to-one mapping between RA-RNTI and PRACH repetition, and there is a one-to-one mapping between PRACH repetition and UE Tx beam ID. Therefore, for example, each PRACH repetition can be associated with a RA-RNTI, so that the UE, after receiving the RA-RNTI, can determine the Tx beam used to transmit the PRACH repetition corresponding to the RA-RNTI. The UE Tx beam can then be indicated by the RA-RNTI used to scramble the PDCCH for RAR.

[0062] Alternative 3: Indicate explicitly in the contents of the RAR.

[0063] The MAC PDU for random access response (RAR) consists of MAC sub-PDU, padding, etc. The MAC sub-PDU consists of a MAC sub-header, MAC RAR or other possible MAC structures. An alternative is to explicitly indicate the UL Tx beam in the MAC PDU, specifically, the indication can be added to the MAC RAR content.

[0064] Alternative 4: UE Tx beam indication via PDCCH monitor occasion (MO) number or count.

[0065] In a wireless communication system, a control resource set (CORESET) consists of one or more resource blocks (RBs) in the frequency domain and one or more orthogonal frequency division multiplexing (OFDM) symbols in the time domain. One or more physical downlink control channel (PDCCH) candidates are transmitted in the CORESET. The configuration parameters of the CORESET are configured by the network for the user equipment (UE), including the CORESET index, frequency domain resources, CORESET duration, etc. One or more CORESETs can be configured for the UE to monitor the PDCCH.

[0066] The gNB may configure the transmission configuration indicator (TCI) state flag for the CORESET through RRC signaling or a combination of RRC signaling and MAC signaling. The TCI state includes Quasi Co-Location (QCL) information, and the QCL information also includes at least one of reference signal (RS) configuration information and QCL type, etc. The RS may be a Channel State Indication RS (CSI-RS) or a synchronization signal and a physical broadcast channel block (SSB), and the RS configuration information includes a CSI-RS resource flag or an SSB index.

[0067] For example, the TCI state list may be configured by RRC signaling, and one of the TCI states in the list may also be indicated by MAC signaling (e.g., MAC CE (control element)) for the CORESET. Then, the DMRS antenna port for PDCCH reception in the CORESET and the RS resources indicated in the TCI state are quasi-co-located with the indicated QCL type. Quasi-co-location is defined for two antenna ports when the large-scale characteristics of the channel that transmits symbols on one antenna port can be inferred from the large-scale characteristics of the channel that transmits symbols on another antenna port. The large-scale characteristics include one or more of delay spread, Doppler spread, Doppler shift, average gain, average delay, and spatial Rx parameters.

[0068] In a wireless communication system, the network configures one or more search space sets for the UE. The configuration parameters of the search space set include search space index, associated CORESET index, monitoringSlotPeriodicityAndOffset, duration, monitoringSymbolsWithinSlot, search space type, etc. In general, there are two types of search spaces, UE-specific search space (USS) and common search space (CSS). The search space type also indicates the downlink control information (DCI) format monitored by the UE. The search space set is associated with the CORESET. The RRC signaling "monitoringSlotPeriodicityAndOffset" indicates the time slot in which the UE needs to monitor the PDCCH. According to the search space set configuration and the associated CORESET configuration, the UE is configured to monitor the corresponding PDCCH with the DCI format indicated by the search space type on the resources indicated by the CORESET in the time slot indicated by the monitoringSlotPeriodicityAndOffset.

[0069] Figure 7 It is a diagram showing an example configuration of the PDCCH monitoring opportunity. A total of eight time slots are shown (represented by time slots 0 to 7). The PDCCH monitoring period is 4 time slots and the offset is 0. The search space duration is 2, which means that two consecutive time slots contain PDCCH monitoring opportunities (MO) within the PDCCH monitoring period. The position of the PDCCH MO within each time slot is configured via the RRC signaling "monitoringSymbolsWithinSlot". There are 2 PDCCH MOs configured in one time slot. Therefore, there are a total of 4 MOs in one PDCCH monitoring period. On each MO, a resource is configured for the UE through CORESET to monitor the PDCCH.

[0070] In a wireless communication system, there are one or more PDCCH candidates in a search space. Each PDCCH candidate has a PDCCH candidate index. PDCCH consists of one or more control channel elements (CCEs). Each CCE has a CCE index.

[0071] Within the RAR window, the gNB can freely choose the location of the PDCCH MO for RAR transmission. The relationship between PDCCH MO and UE Tx beam ID helps the UE to determine the UE Tx beam ID for subsequent UL transmission. For example, within the RAR window, the window length is 10ms, there are many PDCCH MOs for Type1-PDCCH CSS set, assuming the maximum number of UE Tx beams is 8, for example, each UE Tx beam has a Tx beam index m, which belongs to {0,...,7}. There are N MOs within the RAR window, and the MOs starting from the starting point of the RAR window can be indexed as 0,1,2,3,4,5,6,7,...,N-1 in the normal order of PDCCH MOs. When the UE successfully receives a RAR with MO index n (n is {0...n-1}), the UE will know the UE Tx beam ID m for subsequent UL transmission. The index can be implicitly determined by the UE starting counting from the first PDCCH MO after the starting point of the RAR window. Specifically, the UE counts the number of PDCCH MOs and calculates the remainder based on the count number or index of the PDCCH MOs where the RAR is received divided by the number of PRACH repetitions. The UE can determine the UE Tx beam ID based on the following equation: UE Tx beam ID m = (count or number or index of the PDCCH MO n where the RAR is received) Mod (PRACH repetition number).

[0072] Figure 8 UE Tx beam indication using PDCCH MO position is shown, and the UE can count the PDCCH MO position from the start of the RAR window. In this example, UE Tx beam ID "1" is selected by the gNB and indicated to the UE via RAR transmission located in MO index "1". Therefore, in some embodiments, if the UE receives a RAR from the gNB at MO 1, the UE can determine that the gNB is indicating UE Tx beam ID "1".

[0073] The UE determines the appropriate Tx beam based on the relationship between the PDCCH MO for RAR and the UE Tx beam ID. The UE counts all PDCCH MOs for RAR from the reference point, the count increments to the number of PRACH repetitions and loops back to the first count value, and the loop count ends until the reference window (which is the RAR window) ends. When the UE obtains a valid RAR from the PDCCH MO, the UE Tx beam index for the next UL transmission is determined by the count value (or number) of the corresponding PDCCH MO.

[0074] The count or number of MOs can also start from the time slot boundary / subframe boundary / frame boundary, but not from the beginning of the RAR window. The index of the MO is relatively fixed to the time period boundary of the frame structure, which is convenient for UE counting and requires less complexity.

[0075] Fig. 9 It is shown that the number of PRACH repetitions is the same as the number of MOs used for RAR in a frame. The MO index is repeated once per frame. In this example, RAR is transmitted at MO 0, which means that the gNB selects UE Tx beam ID 0 corresponding to PRACH repetition 1.

[0076] Fig.10 An example of an MO index period with two frames is shown, where the index starts at the even frame and ends at the odd frame. Since the number of PRACH repetitions exceeds the number of MOs provided in one frame, a two-frame period for MO indexing is applied. In this example, RAR is transmitted at MO 5, which means that the gNB selects UE Tx beam ID 5 corresponding to PRACH repetition 6. It should be noted that since the RAR window length is usually 10ms, which is the same as the frame length, it may not be possible to find a suitable MO within the RAR window to transmit some RARs, for example, the gNB selects UE Tx beam ID 2 corresponding to PRACH repetition 3, but the UE cannot find MO2 in the RAR window. To solve this problem, one way is that the gNB should ensure that enough MOs are provided for RAR within one frame period. Another way is to extend the RAR window length, for example, setting the RAR window length double, triple, or longer based on the original length of 10ms.

[0077] Fig.11 It is shown that when the relationship between the synchronization signal block (SSB) and the MO of the PDCCH has been defined, the UE Tx beam indication is performed using the PDCCH MO position that the UE can count from the start of the RAR window.

[0078] The relationship between the MO of SSB and PDCCH has been defined, and the downlink transmission of each MO will use the downlink beam corresponding to each SSB. During the RACH process, the UE will first select the SSB, and the MO for PDCCH is also determined based on the association between the MO and the SSB. The UE determines the appropriate Tx beam based on the relationship between the PDCCH MO for RAR and the UE Tx beam ID. The UE counts all PDCCH MOs associated with the selected SSB from the reference point until the end of the reference window (or the end of the RAR window). The reference point for starting the count can be the start time of the RAR window or the time slot boundary / subframe boundary / frame boundary / multi-frame boundary. The UE performs modulo on the count or count or current number or index of the MO where the RAR is received to the total number of PRACH repetitions (or the total number of random access channels) and derives the UE Tx beam ID. When the UE obtains a valid RAR from the PDCCH MO, the UE Tx beam index for subsequent UL transmission is determined by a modulo operation on the count of the corresponding PDCCH MO.

[0079] For example, Fig.11 MO 0-0 and MO 0-1 in are related to SSB0; MO 1-0 and MO 1-1 are related to SSB1 respectively. The UE first selects SSB1 and determines PRACH based on SSB1. The UE can monitor the MO of PDCCH only in MO 1-0 and MO 1-1. When the UE detects RAR in MO1-0, it means that the UE Tx beam is indicated as the first Tx beam.

[0080] Alternative 5: UE Tx beam indication via CORESET or search space set configuration.

[0081] For different PRACH repetitions, different CORESETs and / or search space sets may be configured. Then, if the UE detects a RAR PDCCH in a CORESET or search space set, the UE may determine the best UE Tx beam corresponding to the CORESET or search space set.

[0082] Alternative solution 6: UE Tx beam indication through the DMRS sequence of RAR PDCCH / PDSCH.

[0083] The relationship between the UE Tx beam and the DMRS sequence of the RAR PDCCH / PDSCH can be predefined or configured by the gNB (e.g., via SIB1). Then, if the UE detects a RAR PDCCH / PDSCH, it can determine the best UE Tx beam that corresponds to the DMRS of the detected RAR PDCCH / PDSCH. The RAR can include DMRS sequences for PDCCH and / or PDSCH.

[0084] Alternative solution 7: UE Tx beam indication via the DCI content of the RAR PDCCH.

[0085] The UE Tx beam indication is explicitly indicated in the DCI content of the PDCCH of the RAR. DCI is downlink control information with many information bits carried by the PDCCH.

[0086] In some embodiments, a solution for the UE to distinguish the RAR corresponding to any PRACH repetition and decide which UE Tx beam is appropriate is shown in the following three alternatives:

[0087] • Alternative 1: Modify the RA-RNTI calculation, additional information about the UE Tx beam ID is added to the RA-RNTI calculation.

[0088] • Alternative 2: RAR transmission with RA-RNTI corresponding to one of the multiple PRACH repetitions.

[0089] Alternative 3: Explicit indication in the content of RAR. The gNB indicates the UL Tx beam in the MAC PDU (specifically in the MAC RAR content).

[0090] ·Alternative solution 4: UE Tx beam indication through PDCCH MO (Monitoring Occasion) counting.

[0091] oUE can determine the appropriate Tx beam based on the relationship between the PDCCH MO for RAR and the UE Tx beam ID. The UE counts all PDCCH MOs for RAR from the reference point until the end of the reference window. The UE performs modulo on the total number of PRACH repetitions (or the total number of random access channels) and derives the UE Tx beam ID. When the UE obtains a valid RAR from the PDCCH MO, the UE Tx beam index for subsequent UL transmission is determined by modulo on the count of the corresponding PDCCH MO.

[0092] o The reference point for starting counting may be the start time of the RAR window or a slot boundary / subframe boundary / frame boundary / multi-frame boundary. The reference window may be a RAR window or a slot / subframe / frame / multi-frame.

[0093] Alternative 5: UE Tx beam indication via CORESET or search space set configuration.

[0094] Alternative 6: UE Tx beam indication via RAR PDCCH / PDSCH DMRS sequence

[0095] ·Alternative solution 7: UE Tx beam indication is performed through the DCI content of the RAR PDCCH.

[0096] II. Example #2: Multiple reception of RAR to enhance coverage

[0097] As an introduction, for example scenarios that may include extreme coverage requirements, the cyclic prefix (CP) length can be a major obstacle to enhancing coverage, since the CP length should not exceed the length of one OFDM symbol, e.g., 2048κ·2 -μ .

[0098] Fig.12 The figure shows the traditional behavior of gNB detecting PRACH. The gNB has only one assumption, that is, the PRACH detection window covers the four preamble time zones that should arrive. Four reception states can be summarized in the order shown in the figure: (1) The UE is very close to the gNB, where the round trip delay (RTD) is equal to zero; (2) The UE is in the middle of the gNB coverage, where the RTD is between 0 and a CP length; (3) The UE is far away from the gNB at the cell edge, where the RTD is equal to the CP length; (4) The UE is outside the gNB coverage, the additional delay causes incomplete PRACH detection, and the gNB is at risk of failing to successfully detect PRACH.

[0099] One solution to extend the coverage limited by the CP length is to use part of the preamble as a supplementary CP, for example, some of the front preamble is assumed as a CP by the gNB. Assuming that this solution is based on the current PRACH format C2, the PRACH format consists of a length of 2048κ·2 -μ A CP and a total length of 4*2048κ·2 -μThe PRACH format is composed of 4 identical consecutive preambles. Under the setting of SCS equal to 120KHz, one CP length can support a cell radius of up to about 1.15km; one CP + one preamble length can support a cell radius of up to about 2*1.15=2.3km; one CP + two preamble lengths can support a cell radius of up to about 3*1.15=3.45km; one CP + three preamble lengths can support a cell radius of up to about 4*1.15=4.6km. For another PRACH format, such as format B4 with one CP and 12 preambles, the maximum supported cell radius can reach 0.48+11*1.15=13.13km.

[0100] Under this solution, gNB has at least two assumptions about CP length, one is the traditional understanding, that is, only the traditional CP is regarded as CP. The other is that gNB assumes one CP + one preamble as the total CP. In this way, the coverage can be doubled. If more preambles are involved in the CP, the coverage can be enhanced proportionally. A detailed example can be found in Fig.13 Shown. Fig.13 A scenario of extending coverage limited by CP length by using a portion of the preamble as a supplementary CP is shown. Fig.13 The assumption of the gNB in ​​is that one CP + 1 preamble is assumed as the total CP. The RTD is extended to the sum of the CP length and the preamble length at most. Fig.13 In the embodiment, the detection window starts from the second preamble, and the length of the detection window can be the sum of the remaining preambles, such as three preamble lengths, or keep the same length of the detection window of the first hypothesis, such as four preamble lengths.

[0101] The problem with this solution is that if the gNB holds two assumptions about the CP length, when it detects PRACH, there may be two detection energy peaks for PRACH detection under these two assumptions due to the different locations of the UE in the cell, which leads to two possible RTD results. The gNB cannot distinguish the validity of the two RTD estimation results in random access step 1. The more assumptions the gNB holds, the more possible RTD estimation results there are. In the traditional RACH process, multiple RTD estimates are regarded as false positives of PRACH detection. If the gNB generates multiple RARs based on multiple RTD estimates, the RACH process cannot proceed to the next step because the UE has the ability to detect only one RAR belonging to the UE within the RAR window. The traditional UE behavior is that if one RAR is successfully detected and confirmed to belong to the UE based on the preamble index verification, the UE will stop RAR detection. The UE is likely to get an incorrect TA (timing advance) command based on the wrong RTD estimation, and it can be predicted that msg3 reception will fail based on the wrong TA command.

[0102] Fig.14 A solution to the ambiguity of multiple RTDs is shown. In order to resolve the ambiguity caused by the gNB's multiple assumptions about the CP length or the assumptions about the PRACH detection window, the UE needs to be able to receive and decode multiple RARs within one RAR window, for example, even if one RAR is successfully confirmed, the UE will not stop RAR detection and will continue to detect RARs until the end of the RAR window. When the UE gets multiple RARs, the UE will follow the TA commands of the multiple RARs and send multiple msg3s based on the multiple TA commands associated with the multiple RTD estimates. The TA command in each of the multiple RARs includes a TA value. Therefore, for example, each of the multiple msg3s is transmitted using the TA value associated with one of the multiple RARs. The gNB will try to receive all msg3s, but in fact it can only successfully receive one msg3 whose effective TA corresponds to the true RTD estimate. The ambiguity of multiple RTD estimates is then resolved by multiple msg3 transmissions and subsequent multiple RAR receptions. In Fig.14 In the process, the gNB sends msg4 to the UE to indicate to the UE that the gNB has received msg3, where msg4 may include an acknowledgement (ACK) message.

[0103] Fig.15 An example process when PRACH repetition is applied is shown. If PRACH repetition is applied, for example, PRACH is repeated twice in the time domain, this means that the gNB may not need to perform preamble detection based on two hypotheses at the same time, it can detect the first repetition with the first hypothesis, and later detect the second repetition with the second hypothesis. The gNB needs to respond to the two repetitions with multiple RARs respectively. The other processes are the same as the above example.

[0104] In some embodiments, the techniques described in Part II of this patent document can enhance coverage. In some embodiments, the gNB assumes different CP lengths (original CP length, extended CP length including a portion of the preamble) of the PRACH, and assumes multiple assumptions of the PRACH arrival time zone by setting different parallel PRACH reception windows corresponding to the assumptions of different CP lengths; the gNB may obtain multiple RTD estimates with ambiguity during PRACH detection; the gNB sends multiple RARs with different TA commands to the UE based on different RTD estimates; the gNB attempts to receive all msg3s corresponding to the UL grants in the RARs with different TA commands, and obtains at most one valid msg3, and then resolves the RTD ambiguity by receiving the msg3 with a valid TA.

[0105] For the UE, even if one RAR is successfully confirmed, the UE shall not stop RAR detection and continue to detect all possible RARs until the RAR window ends. When the UE gets multiple RARs belonging to it, the UE shall follow the commands in the UL grant in multiple RARs and send multiple msg3 based on multiple TA commands related to multiple RTD estimates. Fig.15 In the embodiment, after the gNB receives msg3, the gNB transmits a message (e.g., msg4) to the UE to indicate to the UE that the gNB has received msg3, where msg4 may include an acknowledgment (ACK) message.

[0106] The above-described embodiments may be applied to wireless communications. Fig.16 An example of a wireless communication system (e.g., a 5G or NR cellular network) is shown that includes a base station 1620 and one or more user equipment (UE) 1611, 1612, and 1613. In some embodiments, the UE accesses the BS (e.g., the network) using a communication link to the network (sometimes referred to as an uplink direction, as shown by dashed arrows 1631, 1632, 1633), which then enables subsequent communication from the BS to the UE (e.g., shown in the direction from the network to the UE, sometimes referred to as a downlink direction, as shown by arrows 1641, 1642, 1643). In some embodiments, the BS sends information to the UE (sometimes referred to as a downlink direction, as shown by arrows 1641, 1642, 1643), which then enables subsequent communication from the UE to the BS (e.g., the direction from the UE to the BS, sometimes referred to as an uplink direction, as shown by dashed arrows 1631, 1632, 1633). The UE may be, for example, a smart phone, a tablet computer, a mobile computer, a machine to machine (M2M) device, an Internet of Things (IoT) device, etc.

[0107] Fig.17 1 shows an exemplary block diagram of a hardware platform 1700, which may be part of a network device (e.g., a base station) or a communication device (e.g., a user equipment (UE)). The hardware platform 1700 includes at least one processor 1710 and a memory 1705 having instructions stored thereon. The instructions executed by the processor 1710 configure the hardware platform 1700 to perform Figures 1 to 16 and Figures 18 to 21 As well as the operations described in various embodiments described in this patent document. Transmitter 1715 transmits or sends information or data to another device. For example, a network device transmitter can send a message to a user device. Receiver 1720 receives information or data transmitted or sent by another device. For example, a user device can receive a message from a network device.

[0108] Fig.18 An exemplary flow chart for receiving a message for identifying a transmit beam for a transmission is shown. Operation 1802 includes performing, by a communications device, a transmission on a plurality of random access channels. Operation 1804 includes receiving a message in response to the transmission on the plurality of random access channels, wherein after the message is received, a transmit beam to be used by the communications device for performing a subsequent transmission is identified by information with which the message is scrambled, by information included in the message, or associated with a time domain location of the message, and wherein the transmit beam is used for a transmission on one of the plurality of random access channels.

[0109] In some embodiments, the message is a random access response (RAR), the information scrambled by the RAR is a random access radio network temporary identifier (RA-RNTI), and the RA-RNTI is a function of the symbol index of the random access channel opportunity, the slot index of the random access channel opportunity, the frequency index of the random access channel opportunity, the carrier index of the random access channel opportunity, and the identifier of the transmit beam. In some embodiments, the message is a random access response (RAR) received in a time window that starts after transmissions on multiple random access channels are performed, and the information scrambled by the RAR is a random access radio network temporary identifier (RA-RNTI) associated with the random access channel on which the transmission is performed using the transmit beam. In some embodiments, the message is a random access response (RAR) that includes an identifier of the transmit beam in a medium access control (MAC) protocol data unit (PDU). In some embodiments, the identifier of the transmit beam is included in the MAC RAR content in the MAC PDU of the RAR.

[0110] In some embodiments, the time domain position of the message is associated with one of a plurality of control channel monitoring opportunities included in the time window, the communication device determines the identifier of the transmit beam based on the number or index associated with the control channel monitoring opportunity where the message is received, and the number or index of the control channel monitoring opportunity is part of a series of numbers or a series of indices associated with a plurality of control channel monitoring opportunities. In some embodiments, the control channel monitoring opportunity is associated with a synchronization signal block (SSB), and the SSB is associated with a plurality of random access channels. In some embodiments, the identifier of the transmit beam is determined using the following equation: Identifier of the transmit beam = number or index associated with the control channel monitoring opportunity where the message is received modulo the total number of the plurality of random access channels.

[0111] In some embodiments, a series of numbers or a series of indices associated with multiple control channel monitoring opportunities are counted or determined by the communication device. In some embodiments, the communication device counts or determines a series of numbers or a series of indices of multiple control channel monitoring opportunities from a reference point in the time window until the end of the time window. In some embodiments, the reference point is located at the start time of the time window, or the reference point is located at a time slot boundary, a subframe boundary, a frame boundary, or a multi-frame boundary in the time window. In some embodiments, the control resource set (CORESET) used by the message is associated with the transmit beam, or the search space set used by the message is associated with the transmit beam. In some embodiments, the message includes a demodulation reference signal (DMRS) sequence associated with the transmit beam. In some embodiments, the message is a random access response (RAR), and the communication device receives downlink control information (DCI), which includes an identifier of the transmit beam and is associated with the RAR.

[0112] Fig.19 An exemplary flow diagram for transmitting a message for identifying a transmit beam for a communication device is shown. Operation 1902 includes receiving, by a network device, a transmission on a plurality of random access channels from a communication device. Operation 1904 includes transmitting a message in response to receiving the transmission on the plurality of random access channels, wherein a transmit beam used by the communication device to perform a subsequent transmission to be received by the network device is identified by information with which the message is scrambled, by information included in the message, or associated with a time domain location of the message, wherein the network device receives a transmission on one of the plurality of random access channels, and wherein a transmit beam is used for the transmission.

[0113] In some embodiments, the message is a random access response (RAR), the information with which the RAR is scrambled is a random access radio network temporary identifier (RA-RNTI), and the RA-RNTI is a function of a symbol index of a random access channel opportunity, a slot index of a random access channel opportunity, a frequency index of a random access channel opportunity, a carrier index of a random access channel opportunity, and an identifier of a transmit beam. In some embodiments, the message is a random access response (RAR) transmitted in a time window that begins after a transmission on a plurality of random access channels is received, and the information with which the RAR is scrambled is a random access radio network temporary identifier (RA-RNTI) associated with the random access channel on which a transmission using the transmit beam is received.

[0114] In some embodiments, the message is a random access response (RAR) that includes an identifier of a transmit beam in a medium access control (MAC) protocol data unit (PDU). In some embodiments, the identifier of the transmit beam is included in the MAC RAR content in the MAC PDU of the RAR. In some embodiments, the time domain location of the message is in a control channel monitoring opportunity from a plurality of control channel monitoring opportunities included in the time window, the identifier of the transmit beam is based on a number or index associated with the control channel monitoring opportunity at which the message is transmitted, and the number or index of the control channel monitoring opportunity is part of a series of numbers or a series of indices associated with a plurality of control channel monitoring opportunities. In some embodiments, the control channel monitoring opportunity is associated with a synchronization signal block (SSB), and the SSB is associated with a plurality of random access channels.

[0115] In some embodiments, the identifier of the transmit beam is based on the following equation: Identifier of the transmit beam = number or index associated with the control channel monitoring opportunity at which the message is transmitted modulo the total number of multiple random access channels. In some embodiments, a control resource set (CORESET) used by the message is associated with the transmit beam, or a search space set used by the message is associated with the transmit beam. In some embodiments, the message includes a demodulation reference signal (DMRS) sequence associated with the transmit beam. In some embodiments, the message is a random access response (RAR), and the network device transmits downlink control information (DCI) that includes an identifier of the transmit beam and is associated with the RAR.

[0116] Fig. 20 An exemplary flow chart for receiving a message based on a timing advance (TA) value is shown. Operation 2002 includes receiving, by a network device, a cyclic prefix and a plurality of preambles. Operation 2004 includes transmitting, after receiving the cyclic prefix and the plurality of preambles, a plurality of random access responses (RARs), wherein each RAR includes a timing advance (TA) command including a TA value corresponding to one of a plurality of round trip delays, wherein each round trip delay is associated with one of a plurality of detection windows, and wherein each detection window is associated with reception of a different set of preambles in the plurality of preambles. Operation 2006 includes, in response to transmitting the plurality of RARs, receiving a first message based on a TA value associated with a TA command from a RAR. Operation 2008 includes, in response to receiving the first message, transmitting a second message indicating that the first message was received.

[0117] Fig.21An exemplary flow chart for transmitting a message based on a TA value is shown. Operation 2102 includes transmitting, by a communication device in a time domain, a cyclic prefix followed by a plurality of preambles. Operation 2104 includes receiving a plurality of random access responses (RARs) after transmitting the cyclic prefix and the plurality of preambles, wherein each RAR includes a timing advance (TA) command. Operation 2106 includes transmitting a plurality of messages in response to receiving the plurality of RARs, wherein each of the plurality of messages is based on a TA value associated with a TA command from a RAR. Operation 2108 includes receiving a message indicating receipt of a message from the communication device in response to transmitting the plurality of messages, wherein the one message is from the plurality of messages.

[0118] In some embodiments, the TA command for each RAR is associated with one of a plurality of round trip delays, each round trip delay is associated with one of a plurality of detection windows of the network device, and each detection window is associated with a different set of preambles in a plurality of preambles. In some embodiments, the TA command includes a TA value corresponding to one of the plurality of round trip delays.

[0119] In this document, the term "exemplary" is used to mean an "example of," and does not imply an ideal or preferred embodiment unless otherwise specified.

[0120] Some embodiments described herein are described in the general context of methods or processes, which in one embodiment can be implemented by a computer program product embodied in a computer-readable medium, including computer executable instructions, such as program code, executed by a computer in a networked environment. Computer-readable media may include removable and non-removable storage devices, including but not limited to read-only memory (ROM), random access memory (RAM), compact discs (CD), digital versatile discs (DVD), etc. Therefore, computer-readable media may include non-transitory storage media. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. Computer or processor executable instructions, related data structures, and program modules represent examples of program codes for executing the steps of the methods disclosed herein. A specific sequence of such executable instructions or related data structures represents an example of corresponding actions for implementing the functions described in these steps or processes.

[0121] Some of the disclosed embodiments can be implemented as devices or modules using hardware circuits, software or a combination thereof. For example, the hardware circuit implementation may include discrete analog and / or digital components, which are, for example, integrated as a part of a printed circuit board. Alternatively or additionally, the disclosed components or modules may be implemented as application specific integrated circuits (Application Specific Integrated Circuit, ASIC) and / or field programmable gate arrays (Field Programmable Gate Array, FPGA) devices. Some embodiments may additionally or alternatively include a digital signal processor (digital signal processor DSP), which is a dedicated microprocessor with an architecture optimized for the operational requirements of digital signal processing associated with the disclosed functions of the present application. Similarly, various components or subcomponents within each module may be implemented with software, hardware or firmware. The connection between modules and / or components within the modules may be provided using any of the connection methods and media known in the art, including but not limited to communications on the Internet, wired or wireless networks using appropriate protocols.

[0122] Although this document contains many details, these details should not be interpreted as limitations on the scope of any invention or what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features described in this document in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually in multiple embodiments or in any suitable sub-combination. In addition, although the above-mentioned features may be described as working in certain combinations and even initially claimed as such, in some cases, one or more features from the combination may be deleted from the combination, and the combination may involve sub-combinations or variations of sub-combinations. Similarly, although operations are described in a particular order in the accompanying drawings, this should not be understood as requiring that the operations be performed in the particular order or sequence shown, or requiring that all illustrated operations be performed to obtain the desired results.

[0123] Only a few implementations and examples are described, and other implementations, enhancements, and variations may be made based on what is described and illustrated in this disclosure.

Claims

1. A wireless communication method, comprising: performing transmissions on a plurality of random access channels by a communication device; as well as receiving a message in response to a transmission on the plurality of random access channels, wherein the transmit beam used by the communication device to perform subsequent transmissions after the message is received is identified by information with which the message is scrambled, by information included in the message, or is associated with a time domain position of the message, and The transmit beam is used for transmission of a random access channel among the multiple random access channels.

2. The method according to claim 1, in, The message is a Random Access Response (RAR), The information scrambled by the RAR is a random access radio network temporary identifier (RA-RNTI), and Wherein, the RA-RNTI is a function of: The symbol index of the random access channel opportunity, The slot index of the random access channel opportunity, The frequency index of the random access channel opportunity, the carrier index of the random access channel opportunity, and An identifier for the transmit beam.

3. The method according to claim 1, in, The message is a random access response (RAR) received in a time window that begins after transmissions on the plurality of random access channels are performed, and The information into which the RAR is scrambled is a random access radio network temporary identifier (RA-RNTI) associated with the random access channel in which the transmission is performed using the transmit beam.

4. The method according to claim 1, wherein: The message is a random access response (RAR) that includes an identifier of a transmit beam in a medium access control (MAC) protocol data unit (PDU).

5. The method according to claim 4, wherein: The identifier of the transmit beam is included in the MAC RAR content in the MAC PDU of the RAR.

6. The method according to claim 1, in, The time domain position of the message is associated with a control channel monitoring opportunity among a plurality of control channel monitoring opportunities included in the time window, wherein the communication device determines the identifier of the transmit beam based on a number or index associated with a control channel monitoring occasion at which the message is received, and The number or index of the control channel monitoring opportunity is part of a series of numbers or a series of indexes associated with the multiple control channel monitoring opportunities.

7. The method according to claim 6, wherein: The control channel monitoring opportunity is associated with a synchronization signal block (SSB), and the SSB is associated with the plurality of random access channels.

8. The method according to claim 6, wherein: The identifier of the transmit beam is determined using the following equation: The identifier of the transmit beam=the number or the index associated with the control channel monitoring occasion at which the message is received modulo the total number of the plurality of random access channels.

9. The method according to claim 6, wherein: The series of numbers or the series of indices associated with the plurality of control channel monitoring opportunities are counted or determined by the communications device.

10. The method according to claim 9, wherein: The communications device counts or determines the series of numbers or the series of indices of the plurality of control channel monitoring opportunities from a reference point in the time window until the end of the time window.

11. The method according to claim 10, in, The reference point is located at the start time of the time window, or The reference point is located at a time slot boundary, a subframe boundary, a frame boundary, or a multi-frame boundary in the time window.

12. The method according to claim 1, in, A control resource set (CORESET) used by the message is associated with the transmit beam, or Wherein a search space set used by the message is associated with the transmit beam.

13. The method according to claim 1, wherein: The message includes a demodulation reference signal (DMRS) sequence associated with the transmit beam.

14. The method according to claim 1, in, The message is a Random Access Response (RAR), and The communication device receives downlink control information (DCI), the downlink control information including an identifier of the transmit beam and associated with the RAR.

15. A wireless communication method, comprising: receiving, by a network device, transmissions on a plurality of random access channels from a communication device; as well as transmitting a message in response to receiving a transmission on the plurality of random access channels, wherein the transmit beam used by the communication device to perform a subsequent transmission to be received by the network device is identified by information with which the message is scrambled, by information included in the message, or is associated with a time domain location of the message, wherein the network device receives a transmission of a random access channel from among the plurality of random access channels, and Wherein, the transmit beam is used for the transmission.

16. The method according to claim 15, in, The message is a Random Access Response (RAR), The information scrambled by the RAR is a random access radio network temporary identifier (RA-RNTI), and Wherein, the RA-RNTI is a function of: The symbol index of the random access channel opportunity, The slot index of the random access channel opportunity, The frequency index of the random access channel opportunity, the carrier index of the random access channel opportunity, and An identifier for the transmit beam.

17. The method according to claim 15, in, The message is a random access response (RAR) transmitted in a time window that begins after transmissions on the plurality of random access channels are received, and The information into which the RAR is scrambled is a random access radio network temporary identifier (RA-RNTI) associated with a random access channel in which a transmission using the transmit beam is received.

18. The method according to claim 15, wherein: The message is a random access response (RAR) that includes an identifier of a transmit beam in a medium access control (MAC) protocol data unit (PDU).

19. The method according to claim 18, wherein: The identifier of the transmit beam is included in the MAC RAR content in the MAC PDU of the RAR.

20. The method according to claim 15, in, The time domain position of the message is a control channel monitoring opportunity among a plurality of control channel monitoring opportunities included in the time window, wherein the identifier of the transmit beam is based on a number or index associated with the control channel monitoring occasion at which the message is transmitted, and The number or index of the control channel monitoring opportunity is part of a series of numbers or a series of indices associated with the multiple control channel monitoring opportunities.

21. The method according to claim 20, wherein: The control channel monitoring opportunity is associated with a synchronization signal block (SSB), and the SSB is associated with the plurality of random access channels.

22. The method according to claim 20, wherein: The transmit beam identifier is based on the following equation: The identifier of the transmit beam=the number or index associated with the control channel monitoring occasion at which the message is transmitted modulo the total number of the plurality of random access channels.

23. The method according to claim 15, in, A control resource set (CORESET) used by the message is associated with the transmit beam, or Wherein a search space set used by the message is associated with the transmit beam.

24. The method according to claim 15, wherein: The message includes a demodulation reference signal (DMRS) sequence associated with the transmit beam.

25. The method according to claim 1, in, The message is a Random Access Response (RAR), and The network device transmits downlink control information (DCI), the downlink control information includes an identifier of the transmit beam and is associated with the RAR.

26. A wireless communication method, comprising: receiving, by a network device, a cyclic prefix and a plurality of preambles; after receiving the cyclic prefix and the plurality of preambles, transmitting a plurality of random access responses (RARs), wherein each RAR includes a timing advance (TA) command including a TA value corresponding to one of a plurality of round trip delays, Wherein each round trip delay is associated with one detection window among the plurality of detection windows, and wherein each detection window is associated with the reception of a different set of preambles among the plurality of preambles; In response to transmitting the plurality of RARs, receiving a first message based on a TA value associated with a TA command from a RAR; and In response to receiving the first message, a second message is transmitted indicating that the first message was received.

27. A wireless communication method, comprising: A cyclic prefix followed by a plurality of preambles is transmitted in the time domain by a communication device; receiving a plurality of random access responses (RARs) after transmitting the cyclic prefix and the plurality of preambles, Wherein, each RAR includes a timing advance (TA) command; In response to receiving the plurality of RARs, transmitting a plurality of messages, wherein each message of the plurality of messages is based on a TA value associated with a TA command from a RAR; and In response to transmitting the plurality of messages, a message is received indicating receipt of a message from the communication device, wherein the one message is from the plurality of messages.

28. The method according to claim 27, in, The TA command of each RAR is associated with one of a plurality of round trip delays, wherein each round trip delay is associated with one of a plurality of detection windows of the network device, and Each detection window is associated with a different set of preambles among the plurality of preambles.

29. The method according to claim 27, wherein: The TA command includes a TA value corresponding to one of a plurality of round trip delays.

30. An apparatus for wireless communication, comprising a processor configured to implement the method according to one or more of claims 1 to 29.

31. A non-transitory computer-readable program storage medium having stored thereon codes which, when executed by a processor, cause the processor to implement the method according to one or more of claims 1 to 29.

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