Facilitating MU-MIMO transmission for pdcch and pdsch carrying random access response

Abstract

An apparatus configured to: receive at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determine based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitor for the random access response message using the at least one determined resource and the demodulation reference signal port.

Description

FACILITATING MU-MIMO TRANSMISSION FOR PDCCH AND PDSCH CARRYING RANDOM ACCESS RESPONSETECHNICAL FIELD

[0001] The example and non-limiting embodiments relate generally to the random access procedure and, more particularly, to the random access response message.BACKGROUND

[0002] It is known, in the random access procedure, to broadcast together random access response messages for a plurality of user equipments.SUMMARY

[0003] The following summary is merely intended to be illustrative. The summary is not intended to limit the scope of the claims.

[0004] In accordance with one aspect, an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus at least to: receive at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determine based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitor for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0005] In accordance with one aspect, a method comprising: receiving, with a user equipment, at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitoring for the randomaccess response message using the at least one determined resource and the demodulation reference signal port.

[0006] In accordance with one aspect, an apparatus comprising means for: receiving at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0007] In accordance with one aspect, a computer-readable medium comprising program instructions stored thereon for performing at least the following: causing receiving, with a user equipment, of at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0008] In accordance with one aspect, an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus at least to: transmit, to at least one user equipment, at least one system information block comprising, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; receive, from the at least one user equipment, at least one random access preamble; and transmit, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

[0009] In accordance with one aspect, a method comprising: transmitting, with a network node to at least one user equipment, at least one system information block comprising, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitorfor a random access response message; receiving, from the at least one user equipment, at least one random access preamble; and transmitting, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

[0010] In accordance with one aspect, an apparatus comprising means for: transmitting, to at least one user equipment, at least one system information block comprising, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; receiving, from the at least one user equipment, at least one random access preamble; and transmitting, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

[0011] In accordance with one aspect, a computer-readable medium comprising program instructions stored thereon for performing at least the following: causing transmitting, to at least one user equipment, of at least one system information block comprising, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; causing receiving, from the at least one user equipment, of at least one random access preamble; and causing transmitting, to the at least one user equipment, of the random access response message based, at least partially, on the at least one random access preamble.

[0012] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The foregoing aspects and other features are explained in the following description, taken in connection with the accompanying drawings, wherein:

[0014] FIG. 1 is a block diagram of one possible and non-limiting example system in which the example embodiments may be practiced;

[0015] FIG. 2 is a flowchart illustrating steps as described herein;

[0016] FIG. 3 is a flowchart illustrating steps as described herein;

[0017] FIG. 4 is a diagram illustrating features as described herein;

[0018] FIG. 5 is a flowchart illustrating steps as described herein

[0019] FIG. 6 is a diagram illustrating features as described herein;

[0020] FIG. 7 is a flowchart illustrating steps as described herein; and

[0021] FIG. 8 is a flowchart illustrating steps as described herein.DETAILED DESCRIPTION OF EMBODIMENTS

[0022] The following abbreviations that may be found in the specification and / or the drawing figures are defined as follows:3GPP third generation partnership project5G fifth generation5GC 5G core networkAMF access and mobility management functionCORESET control resource setcRAN cloud radio access networkCSI channel state informationCU central unitDCI downlink control informationDL downlinkDMRS demodulation reference signalDU distributed uniteNB (or eNodeB) evolved Node B (e.g., an LTE base station)EN-DC E-UTRA-NR dual connectivityen-gNB or En-gNB node providing NR user plane and control plane protocol terminations towards the UE, and acting as secondary node in EN-DCE-UTRA evolved universal terrestrial radio access, i.e., the LTE radio access technologygNB (or gNodeB) base station for 5G / NR, i.e., a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GCI / F interfaceLI layer 1LTE long term evolutionMAC medium access controlMCS modulation and coding schemeMIB master information blockMIMO multiple input multiple outputMME mobility management entityMU multiple usersng or NG new generationng-eNB or NG-eNB new generation eNBNR new radioN / W or NW network0-RAN open radio access networkPBCH physical broadcast channelPDCCH physical downlink control channelPDCP packet data convergence protocolPDSCH physical downlink shared control channelPHY physical layerPRACH physical random access channelPSS primary synchronization signalPUCCH physical uplink control channelRA random accessRACH random access channelRAN radio access networkRAR random access responseRF radio frequencyRLC radio link controlRNTI radio network temporary identifierRO RACH occasionRRC radio resource controlRRH remote radio headRS reference signalRU radio unitRx receiverSDAP service data adaptation protocolSGW serving gatewaySIB system information blockSINR signal to interference plus noise ratioSMF session management functionSNR signal to noise ratioSSB synchronization signal blockSSS secondary synchronization signalTC temporary cellTDD time division duplexTRP transmission and / or reception pointTx transmitterUE user equipment (e.g., a wireless, typically mobile device) UL uplinkUPF user plane functionVNR virtualized network function

[0023] Turning to FIG. 1 , this figure shows a block diagram of one possible and non-limiting example in which the examples may be practiced. A user equipment (UE) 110, radio access network (RAN) node 170, and network element(s) 190 are illustrated. In the example of FIG. 1, the user equipment (UE) 110 is in wireless communication with a wireless network 100. A UE is a wireless device that can access the wireless network 100. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. A “circuit” may include dedicated hardware or hardware in association with software executable thereon. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a module 140, comprising one of or both parts 140-1 and / or 140-2, which may be implemented in a number of ways. The module 140 may be implemented in hardware as module 140-1, such as being implemented as part of the one or more processors 120. The module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 140 may be implemented as module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with RAN node 170 via a wireless link 111.

[0024] The RAN node 170 in this example is a base station that provides access by wireless devices such as the UE 110 to the wireless network 100. The RAN node 170 may be, for example, a base station for 5G, also called New Radio (NR). In 5G, the RAN node 170 may be a NG-RAN node, which is defined as either a gNB or a ng-eNB. A gNB is a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to a 5GC (such as, for example, the network element(s) 190). The ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via theNG interface to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and distributed unit(s) (DUs) (gNB-DUs), of which DU 195 is shown. Note that the DU may include or be coupled to and control a radio unit (RU). The gNB-CU is a logical node hosting RRC, SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the Fl interface connected with the gNB -DU. The Fl interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the RAN node 170 and centralized elements of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195. The gNB-DU is a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU. One gNB-CU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the Fl interface 198 connected with the gNB-CU. Note that the DU 195 is considered to include the transceiver 160, e.g., as part of a RU, but some examples of this may have the transceiver 160 as part of a separate RU, e.g., under control of and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station, access point, access node, or node.

[0025] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N / W I / F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor(s) 152, memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory / memories and processor(s), and / or other hardware, but these are not shown.

[0026] The RAN node 170 includes a module 150, comprising one of or both parts 150-1 and / or 150-2, which may be implemented in a number of ways. The module 150 may be implemented in hardware as module 150-1, such as being implemented as part of the one or more processors 152. The module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 150 may beimplemented as module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the RAN node 170 to perform one or more of the operations as described herein. Note that the functionality of the module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.

[0027] The one or more network interfaces 161 communicate over a network such as via the links 176 and 131. Two or more gNBs 170 may communicate using, e.g., link 176. The link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

[0028] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the RAN node 170 possibly being physically in a different location from the RRH / DU, and the one or more buses 157 could be implemented in part as, for example, fiber optic cable or other suitable network connection to connect the other elements (e.g., a central unit (CU), gNB-CU) of the RAN node 170 to the RRH / DU 195. Reference 198 also indicates those suitable network link(s).

[0029] It is noted that description herein indicates that “cells” perform functions, but it should be clear that equipment which forms the cell will perform the functions. The cell makes up part of a base station. That is, there can be multiple cells per base station. For example, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single base station’s coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and a base station may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the base station has a total of 6 cells.

[0030] The wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a further network, such as a telephone network and / or a data communications network (e.g., the Internet). Such core network functionality for 5G may include access and mobility management function(s) (AMF(s)) and / or user plane functions (UPF(s)) and / or session management function(s) (SMF(s)). Such core network functionality for LTE may include MME (Mobility Management Entity) / SGW (Serving Gateway) functionality. These are merely illustrative functions that may be supported by the network element(s) 190, and note that both 5G and LTE functions might be supported. The RAN node 170 is coupled via a link 131 to a network element 190. The link 131 may be implemented as, e.g., an NG interface for 5G, or an SI interface for LTE, or other suitable interface for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N / W I / F(s)) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured to, with the one or more processors 175, cause the network element 190 to perform one or more operations.

[0031] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software -based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. For example, a network may be deployed in a tele cloud, with virtualized network functions (VNF) running on, for example, data center servers. For example, network core functions and / or radio access network(s) (e.g. CloudRAN, 0-RAN, edge cloud) may be virtualized. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.

[0032] It may also be noted that operations of example embodiments of the present disclosure may be carried out by a plurality of cooperating devices (e.g. cRAN).

[0033] The computer readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multicore processor architecture, as non-limiting examples. The processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, RAN node 170, and other functions as described herein.

[0034] In general, the various example embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.

[0035] Having thus introduced one suitable but non-limiting technical context for the practice of the example embodiments of the present disclosure, example embodiments will now be described with greater specificity.

[0036] Features as described herein may generally relate to the random access (RA) procedure, and more specifically to the random access response (RAR) message. The RAR message may be part of 4-step RA, 2-step RA, or another RA procedure.

[0037] Referring now to FIG. 2, illustrated is an example of the 4-step RACH procedure. In the 4-step RACH procedure, a UE (210) may transmit, to a gNB (220), a Msgl, also known as aphysical random access channel (PRACH) message (230). The UE (210) may send a specific preamble to the gNB (220) via the Msgl / PRACH using a specific resource called a RACH occasion (RO). The gNB (220) may, in response, transmit to the UE (210) a Msg2, also known as a random-access response (RAR) message (240), which may include the detected preamble ID, the time-advance command, a temporary cell radio network temporary identifier (TC-RNTI), and / or a UL grant for the transmission of Msg3 on the physical uplink shared channel (PUSCH). The UE (210) may, in response, transmit to the gNB (220) a Msg3, also known as a radio resource control (RRC) request (250), over the scheduled PUSCH with an ID for contention resolution. The gNB (220) may transmit, to the UE (210) a Msg4, also known as an RRC setup message (260). The RRC setup message may be a contention resolution message with the contention-resolution ID.

[0038] Upon reception of Msg4 (260), the UE (210) may send an ACK on a physical uplink control channel (PUCCH) if its contention-resolution ID is carried by Msg4 (260). This may complete the 4-step RACH. It may be noted that prior to Msgl (230), there may also be a preliminary step of sending and receiving the synchronization signal block (SSB), i.e., DL beam sweeping, which is not formally part of the RACH procedure. As a result of this preliminary step, the UE (210) may select the index of the preferred SSB beam and decode the associated physical broadcast channel (PBCH) for the master information block (MIB), system information block (SIB), and so on. This index may also be used by UE (210) to identify a suitable RACH occasion (RO) for the preamble transmission (Msgl, 230), according to the SSB-to-RO mapping implicitly conveyed by SIB 1. The UE may find / map its DMRS port from the set of DMRS ports reported in SIB, based on the preamble it transmitted or the RO chosen for the last uplink transmission.

[0039] Referring now to FIG. 3, illustrated is an example of 2-step RACH procedure. In 2-step RA, a UE in an RRC_IN ACTIVE state may transmit, to the network, a MS GA (310) comprising, at least, a PRACH preamble and PUSCH. The gNB may transmit, to the UE, a MSGB (320), which may comprise a RAR.

[0040] Following the 5G standard, upon initial connection establishment, a UE may interface with a nearby gNodeB, and may receive therefrom synchronization signal blocks (SSBs) andsystem information blocks (SIBs). These transmissions may be used to synchronize the UE's timing and frequency with that of the network, furnishing essential network configuration parameters. Subsequently, the UE may monitor downlink (DL) signals, primarily SIBs, and may therefrom acquire details on physical random access channel (PRACH) resources, preamble types, and downlink control information (DCI) pertinent to subsequent random access response (RAR) message transmission post-PRACH interaction.

[0041] The RAR message may encapsulate the information of all UEs with the same RA-RNTI. Consequently, it may necessitate more symbols for transmitting the RAR message. However, it may not be necessary for a particular UE to receive the information of all other UEs sharing the same RA-RNTI value.

[0042] Furthermore, transmitting the RAR message using the same SSB beamformers may constrain the RAR message signal-to-noise ratio (SNR) / signal-to-interference -plus-noise ratio (SINR), potentially leading to RAR detection failure.

[0043] Features as described herein may generally relate to multi-user multiple input multiple output (MU-MIMO) transmission for the RAR message.

[0044] In the 5G NR standard, a single DCI (e.g. with DCI format l_0) and RAR message may be transmitted for each random access-radio network temporary identifier (RA-RNTI), utilizing the same beamformer configuration as the SSBs. This RAR message may contain essential information relevant to all UEs associated with the same RA-RNTI. Subsequently, each UE sharing the identical RA-RNTI may decode the DCI information using data extracted from SIB-1, followed by the complete reception and interpretation of the RAR message, which encompasses all UEs sharing the same RA-RNTI. An illustrative representation of the RAR message corresponding to a specific RA-RNTI is provided in FIG. 4. In the example of FIG. 4, the common message (410) may be included in a SIB. The common message may include, for example a back-off indicator, and / or other information. The UE-1 message (420) may follow the common message (410) in the time domain, and may be followed by the UE-2 message (430). The example of FIG. 4 is not limiting; any number of UE-specific messages may be included in a SIB.

[0045] In an example embodiment, if the implementation of RAR message is UE-specific, the RAR message may be served / provided to multiple UEs simultaneously using MU-MIMO techniques. A technical effect of example embodiments of the present disclosure may be to improve the RAR coverage using UE-specific channel state information (CSI) obtained from PRACH.

[0046] It may be noted that, where RAR is broadcast, the transmit power is not generally beamformed toward any specific user. Broadcast transmission exploits the overall channel state information to formulate the transmit beamformer. However, when transmitted this way, the overall signal quality of any given user can be low, since the only consideration is to maximize the overall energy transfer through the channel; some users may individually have bad channel conditions. In comparison, by using user-wise / specific channel state information, the transmit beamformers may be tailored on a per-user basis, which may have the technical effect of maximizing the energy transfer to each individual user separately and / or increasing signal quality at reception.

[0047] RAR message delivery has been identified in practical deployments as having low performance / coverage. This may be due to the fact that the RAR message is broadcast.

[0048] A technical effect of example embodiments of the present disclosure may be to facilitate MU-MIMO transmission for / of the RAR message.

[0049] In an example embodiment, UE-specific messages may be transmitted to multiple UEs simultaneously, utilizing the same time and frequency resources but employing spatial multiplexing.

[0050] In an example embodiment, the UE may determine a demodulation reference signal (DMRS) port and sequence at least partly based on the PRACH preamble and / or the random access occasion index the UE selected for PRACH preamble transmission.

[0051] In an example embodiment, the network may indicate, to the UE(s), the possibility of RAR MU-MIMO transmission during / in the SIB- 1. Additionally, the network may include in SIB-1 the DMRS ports indication (i.e., DCI format).

[0052] In an example embodiment, the DCI and RAR messages may be combined and transmitted separately for each UE. The combination of the messages may comprise multiplexing or encapsulating together the messages. Alternatively, the UE-specific DCI and RAR messages may be transmitted separately for each UE, without being combined together.

[0053] In an example embodiment, the network may provide the timing window and frequency resources for the DCI and RAR message during the SIB-1 transmission.

[0054] In an example embodiment, after PRACH transmission, the UE may monitor the frequency resources during the timing window and decode the DCI and RAR message with chosen DMRS port(s).

[0055] Referring now to FIG. 5, illustrated is an example of MU-MIMO transmission of RAR message(s) according to example embodiments of the present disclosure.

[0056] At 510, the BS may transmit, to the UE, SSB, which may comprise primary synchronization signal (PSS), secondary synchronization signal (SSS), MIB, etc. The UE may receive the SSB and perform synchronization with the NW. In addition, the UE may receive the SIB1 configuration.

[0057] At 520, the BS may transmit, to the UE, SIB1. The network may inform the UE about the possibility (e.g. the activation or enablement) of the MU-MIMO transmission of the PDCCH scheduling PDSCH carrying RAR message, and / or PDSCH carrying the RAR message, in the SIB-1 transmission. In other words, the UE may receive the PDCCH and PDSCH information needed to monitor for and / or receive the RAR message where the RAR message is transmitted using a MU-MIMO transmission technique.

[0058] The indication that the RAR will be a MU-MIMO RAR may, for example, be a flag. Alternatively, the UE may determine that a RAR will be a MU-MIMO RAR based, at least partially, on an indication of a DMRS antenna port included in SIB-1.

[0059] In an example embodiment, the SIB-1 may indicate the time and frequency resources for the control resource set for PDCCH that schedules PDSCH carrying RAR. Based on this information, the UE may assume that PDCCH in the control resource set (CORESET) may be transmitted in a MU-MIMO manner. Different resources (e.g. DMRS resources) may be indicated or allocated for each UE. Alternatively, the (DMRS) resources allocated for different UEs may be the same or at least partially overlap, while spatial multiplexing may be used to separate the messages intended for each UE.

[0060] In an example embodiment, the SIB-1 may indicate the DMRS port mapping for the UE to DMRS port mapping used for PDCCH and PDSCH carrying RAR transmission. A possible mapping may be based on the UE selected preamble in an RO and DMRS port. For example, a DMRS port number for PDCCH scheduling PDSCH carrying RAR, and for PDSCH, may be 7000 + mod(preamble, 8), which may have the technical effect of enabling up to 8 simultaneous RAR transmissions.

[0061] At 530, the UE may transmit the PRACH preamble in the given resources. At 540, the network may transmit the PDCCH carrying DCI + PDSCH carrying RAR in a MU-MIMO manner. The network may acquire the CSI from the UL PRACH and compute the DL beamformer for the specific UE from the CSI, which may have the technical effect of improving the SINR of the intended UE. The network may use the UE-specific beamformer acquired during the UL PRACH. The UE-specific beamformers may improve the SINR of the intended UE. A technical effect of this may be to improve the DL coverage of the RAR messages.

[0062] It may be noted that channel information may be obtained from pilot signals, which may be transmitted alongside the PRACH preamble.

[0063] Based on the received PDCCH carrying DCI + PDSCH carrying RAR in a MU-MIMO manner, the UE may receive / decode a UL grant. The UE may identify the DMRS portsbased on its chosen PRACH preamble transmission, and may decode the DCI and RAR messages. The RAR message may contain the UL grants for the specified UE. The UE may demultiplex the RAR message specific to the UE from the MU-MIMO RAR.

[0064] Referring now to FIG. 6, illustrated is an example of a MU-MIMO RAR message according to example embodiments of the present disclosure. The UE-1 message (610) and the UE-2 message (620) may be multiplexed in the spatial domain, such that each UE may detect the message specific to itself and avoid decoding the message(s) specific to other UE. In an example embodiment, the MU-MIMO RAR message may be multicast, rather than broadcast, by the NW or base station. While not illustrated in FIG. 6, the MU-MIMO RAR message may include the common message. Alternatively, the common message may be included in SIB-1.

[0065] In an example embodiment, the DCI and RAR messages may be UE-specific. In an example embodiment, the DCI and RAR messages may be scrambled with UE-specific identity, instead of RA-RNTI. Therefore, RA-RNTI calculations may not be required. Alternatively, the RA-RNTI may be needed to verify the correct RO. In an example embodiment, the common message in RAR may be removed or moved to the SIB-1. In an example embodiment, UE-specific beams may need to be used for the RAR message. In an example embodiment, all the UEs in a group may use the same modulation and coding scheme (MCS), which may depend on the worst UE in the group (e.g. according to the SNR of the received signal(s)).

[0066] A technical effect of example embodiments of the present disclosure may be to enhancing network efficiency. A technical effect of example embodiments of the present disclosure may be to utilize multiple spatial degrees of freedom, or multiple parallel streams of data multiplexed in the spatial domain via different user-specific beamformers. A technical effect of example embodiments of the present disclosure may be to increase the RAR transmission rate based on the UE channel conditions. A technical effect of example embodiments of the present disclosure may be to improve the DL coverage of RAR messages using the UE-specific beamformers from the CSI acquired with the PRACH, instead of SSB beams.

[0067] In an example embodiment, a UE may be configured for multi-TRP operation.

[0068] Example embodiments of the present disclosure may be applicable to any random access procedure. Example embodiments of the present disclosure may be applicable to any digital system, for example 6G.

[0069] A technical effect of example embodiments of the present disclosure may be to provide high capacity (multiple UEs can be provided RAR simultaneously).

[0070] FIG. 7 illustrates the potential steps of an example method 700. The example method 700 may include: receiving at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message, 710; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message, 720; and monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port, 730. The example method 700 may be performed, for example, with a UE.

[0071] FIG. 8 illustrates the potential steps of an example method 800. The example method 800 may include: transmitting, to at least one user equipment, at least one system information block comprising, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message, 810; receiving, from the at least one user equipment, at least one random access preamble, 820; and transmitting, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble, 830. The example method 800 may be performed, for example, with a NW, a base station, a gNB, a network node, a network entity, etc.

[0072] In accordance with one example embodiment, an apparatus may comprise: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determine based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; andmonitor for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0073] The at least one system information block may further comprise at least one of: an indication that multiple-user multiple input multiple output transmission of random access response messages is enabled, a physical random access channel configuration, a format of a downlink control information message, or at least one time and frequency resource for receiving the random access response message.

[0074] A mapping of the demodulation reference signal port may be based, at least partially, on at least one of: a physical random access channel preamble determined by the example apparatus, or a random access occasion index associated with the determined physical random access channel preamble.

[0075] The random access response message may be encapsulated with a downlink control information message, wherein the downlink control information message may be a user equipment specific downlink control information message associated with the example apparatus.

[0076] The random access response message may comprise a multicast random access response common message.

[0077] The random access response message may comprise a broadcast random access response common message.

[0078] The random access response message may be associated with the example apparatus and may be multiplexed with at least one random access response message associated with at least another user equipment.

[0079] The random access response message and the at least one random access response message associated with the at least other user equipment may be multiplexed in a spatial domain.

[0080] The example apparatus and the at least other user equipment may use a same modulation and coding scheme.

[0081] The example apparatus and the at least other user equipment may use at least partially different modulation and coding schemes.

[0082] The random access response message may be scrambled with an identity of the example apparatus.

[0083] The random access response message may not comprise a common message, wherein the at least one system information block may comprise the common message.

[0084] The example apparatus may be further configured to: determine that the random access response message may comprise a multiple user-multiple input multiple output random access response message based, at least partially, on the indication of the demodulation reference signal port for monitoring for the random access response message.

[0085] The example apparatus may be further configured to: transmit at least one random access preamble based, at least partially, on the at least one system information block.

[0086] In accordance with one aspect, an example method may be provided comprising: receiving, with a user equipment, at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0087] The at least one system information block may further comprise at least one of: an indication that multiple-user multiple input multiple output transmission of random access response messages is enabled, a physical random access channel configuration, a format of a downlink control information message, or at least one time and frequency resource for receiving the random access response message.

[0088] A mapping of the demodulation reference signal port may be based, at least partially, on at least one of: a physical random access channel preamble determined by the user equipment,or a random access occasion index associated with the determined physical random access channel preamble.

[0089] The random access response message may be encapsulated with a downlink control information message, wherein the downlink control information message may be a user equipment specific downlink control information message associated with the user equipment.

[0090] The random access response message may comprise a multicast random access response common message.

[0091] The random access response message may comprise a broadcast random access response common message.

[0092] The random access response message may be associated with the user equipment and may be multiplexed with at least one random access response message associated with at least another user equipment.

[0093] The random access response message and the at least one random access response message associated with the at least other user equipment may be multiplexed in a spatial domain.

[0094] The user equipment and the at least other user equipment may use a same modulation and coding scheme.

[0095] The user equipment and the at least other user equipment may use at least partially different modulation and coding schemes.

[0096] The random access response message may be scrambled with an identity of the user equipment.

[0097] The random access response message may not comprise a common message, wherein the at least one system information block may comprise the common message.

[0098] The example method may further comprise: determining that the random access response message may comprise a multiple user-multiple input multiple output random accessresponse message based, at least partially, on the indication of the demodulation reference signal port for monitoring for the random access response message.

[0099] The example method may further comprise: transmitting at least one random access preamble based, at least partially, on the at least one system information block.

[0100] In accordance with one example embodiment, an apparatus may comprise: circuitry configured to perform: receiving, with a user equipment, at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; circuitry configured to perform: determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and circuitry configured to perform: monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0101] In accordance with one example embodiment, an apparatus may comprise: processing circuitry; memory circuitry including computer program code, the memory circuitry and the computer program code configured to, with the processing circuitry, enable the apparatus to: receive at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determine based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitor for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0102] As used in this application, the term “circuitry” or “means” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone orserver, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.” This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0103] In accordance with one example embodiment, an apparatus may comprise means for: receiving at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0104] The at least one system information block may further comprise at least one of: an indication that multiple-user multiple input multiple output transmission of random access response messages is enabled, a physical random access channel configuration, a format of a downlink control information message, or at least one time and frequency resource for receiving the random access response message.

[0105] A mapping of the demodulation reference signal port may be based, at least partially, on at least one of: a physical random access channel preamble determined by the example apparatus, or a random access occasion index associated with the determined physical random access channel preamble.

[0106] The random access response message may be encapsulated with a downlink control information message, wherein the downlink control information message may be a user equipment specific downlink control information message associated with the example apparatus.

[0107] The random access response message may comprise a multicast random access response common message.

[0108] The random access response message may comprise a broadcast random access response common message.

[0109] The random access response message may be associated with the example apparatus and may be multiplexed with at least one random access response message associated with at least another user equipment.

[0110] The random access response message and the at least one random access response message associated with the at least other user equipment may be multiplexed in a spatial domain.

[0111] The example apparatus and the at least other user equipment may use a same modulation and coding scheme.

[0112] The example apparatus and the at least other user equipment may use at least partially different modulation and coding schemes.

[0113] The random access response message may be scrambled with an identity of the example apparatus.

[0114] The random access response message may not comprise a common message, wherein the at least one system information block may comprise the common message.

[0115] The means may be further configured for: determining that the random access response message may comprise a multiple user-multiple input multiple output random access response message based, at least partially, on the indication of the demodulation reference signal port for monitoring for the random access response message.

[0116] The means may be further configured for: transmitting at least one random access preamble based, at least partially, on the at least one system information block.

[0117] A processor, memory, and / or example algorithms (which may be encoded as instructions, program, or code) may be provided as example means for providing or causing performance of operation.

[0118] In accordance with one example embodiment, a (non-transitory) computer-readable medium comprising instructions stored thereon which, when executed with at least one processor, cause the at least one processor to: cause receiving, with a user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determine based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitor for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0119] In accordance with one example embodiment, a (non-transitory) computer-readable medium comprising program instructions stored thereon for performing at least the following: causing receiving, with a user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0120] The at least one system information block may further comprise at least one of: an indication that multiple-user multiple input multiple output transmission of random access response messages is enabled, a physical random access channel configuration, a format of a downlink control information message, or at least one time and frequency resource for receiving the random access response message.

[0121] A mapping of the demodulation reference signal port may be based, at least partially, on at least one of: a physical random access channel preamble determined by the user equipment, or a random access occasion index associated with the determined physical random access channel preamble.

[0122] The random access response message may be encapsulated with a downlink control information message, wherein the downlink control information message may be a user equipment specific downlink control information message associated with the user equipment.

[0123] The random access response message may comprise a multicast random access response common message.

[0124] The random access response message may comprise a broadcast random access response common message.

[0125] The random access response message may be associated with the user equipment and may be multiplexed with at least one random access response message associated with at least another user equipment.

[0126] The random access response message and the at least one random access response message associated with the at least other user equipment may be multiplexed in a spatial domain.

[0127] The user equipment and the at least other user equipment may use a same modulation and coding scheme.

[0128] The user equipment and the at least other user equipment may use at least partially different modulation and coding schemes.

[0129] The random access response message may be scrambled with an identity of the user equipment.

[0130] The random access response message may not comprise a common message, wherein the at least one system information block may comprise the common message.

[0131] The example computer-readable medium may further comprise program instructions stored thereon for performing: determining that the random access response message may comprise a multiple user-multiple input multiple output random access response message based, at least partially, on the indication of the demodulation reference signal port for monitoring for the random access response message.

[0132] The example computer-readable medium may further comprise program instructions stored thereon for performing: transmitting at least one random access preamble based, at least partially, on the at least one system information block.

[0133] In accordance with another example embodiment, a (non-transitory) program storage device readable by a machine may be provided, tangibly embodying instructions executable by the machine for performing operations, the operations comprising: causing receiving, with a user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0134] In accordance with another example embodiment, a (non-transitory) computer-readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: causing receiving, with a user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0135] A computer implemented system comprising: at least one processor and at least one (non-transitory) memory storing instructions that, when executed by the at least one processor,cause the system at least to perform: causing receiving, with a user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0136] A computer implemented system comprising: means for causing receiving, with a user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for monitoring for a random access response message; means for determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; and means for monitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

[0137] In accordance with one example embodiment, an apparatus may comprise: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit, to at least one user equipment, at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; receive, from the at least one user equipment, at least one random access preamble; and transmit, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

[0138] The at least one system information block may further comprise at least one of: an indication that multiple-user multiple input multiple output transmission of random access response messages is enabled, a physical random access channel configuration, a format of a downlink control information message, or at least one time and frequency resource for receiving the random access response message.

[0139] The random access response message may be encapsulated with a downlink control information message, wherein the downlink control information message may be a user equipment specific downlink control information message associated with the at least one user equipment.

[0140] The random access response message may comprise a multicast random access response common message.

[0141] The random access response message may comprise a broadcast random access response common message.

[0142] The random access response message may be associated with the at least one user equipment and may be multiplexed with at least one random access response message associated with at least another user equipment.

[0143] The random access response message and the at least one random access response message associated with the at least one other user equipment may be multiplexed in a spatial domain.

[0144] The at least one user equipment and the at least one other user equipment may use a same modulation and coding scheme.

[0145] The at least one user equipment and the at least one other user equipment may use at least partially different modulation and coding schemes.

[0146] The random access response message may be scrambled with an identity of the at least one user equipment.

[0147] The random access response message may not comprise a common message, wherein the at least one system information block may comprise the common message.

[0148] Transmitting the random access response message may comprise the example apparatus being further configured to: determine a beamformer based, at least partially, on channel state information; and transmit the random access response message using the determined beamformer.

[0149] In accordance with one aspect, an example method may be provided comprising: transmitting, with a network node to at least one user equipment, at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; receiving, from the at least one user equipment, at least one random access preamble; and transmitting, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

[0150] The at least one system information block may further comprise at least one of: an indication that multiple-user multiple input multiple output transmission of random access response messages is enabled, a physical random access channel configuration, a format of a downlink control information message, or at least one time and frequency resource for receiving the random access response message.

[0151] The random access response message may be encapsulated with a downlink control information message, wherein the downlink control information message may be a user equipment specific downlink control information message associated with the at least one user equipment.

[0152] The random access response message may comprise a multicast random access response common message.

[0153] The random access response message may comprise a broadcast random access response common message.

[0154] The random access response message may be associated with the at least one user equipment and may be multiplexed with at least one random access response message associated with at least another user equipment.

[0155] The random access response message and the at least one random access response message associated with the at least one other user equipment may be multiplexed in a spatial domain.

[0156] The at least one user equipment and the at least one other user equipment may use a same modulation and coding scheme.

[0157] The at least one user equipment and the at least one other user equipment may use at least partially different modulation and coding schemes.

[0158] The random access response message may be scrambled with an identity of the at least one user equipment.

[0159] The random access response message may not comprise a common message, wherein the at least one system information block may comprise the common message.

[0160] The transmitting of the random access response message may comprise: determining a beamformer based, at least partially, on channel state information; and transmitting the random access response message using the determined beamformer.

[0161] In accordance with one example embodiment, an apparatus may comprise: circuitry configured to perform: transmitting, with a network node to at least one user equipment, at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; circuitry configured to perform: receiving, from the at least one user equipment, at least one random access preamble; and circuitry configured to perform: transmitting, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

[0162] In accordance with one example embodiment, an apparatus may comprise: processing circuitry; memory circuitry including computer program code, the memory circuitry and the computer program code configured to, with the processing circuitry, enable the apparatus to: transmit, to at least one user equipment, at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; receive, from the at least one user equipment,at least one random access preamble; and transmit, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

[0163] In accordance with one example embodiment, an apparatus may comprise means for: transmitting, to at least one user equipment, at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; receiving, from the at least one user equipment, at least one random access preamble; transmitting, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

[0164] The at least one system information block may further comprise at least one of: an indication that multiple-user multiple input multiple output transmission of random access response messages is enabled, a physical random access channel configuration, a format of a downlink control information message, or at least one time and frequency resource for receiving the random access response message.

[0165] The random access response message may be encapsulated with a downlink control information message, wherein the downlink control information message may be a user equipment specific downlink control information message associated with the at least one user equipment.

[0166] The random access response message may comprise a multicast random access response common message.

[0167] The random access response message may comprise a broadcast random access response common message.

[0168] The random access response message may be associated with the at least one user equipment and may be multiplexed with at least one random access response message associated with at least another user equipment.

[0169] The random access response message and the at least one random access response message associated with the at least one other user equipment may be multiplexed in a spatial domain.

[0170] The at least one user equipment and the at least one other user equipment may use a same modulation and coding scheme.

[0171] The at least one user equipment and the at least one other user equipment may use at least partially different modulation and coding schemes.

[0172] The random access response message may be scrambled with an identity of the at least one user equipment.

[0173] The random access response message may not comprise a common message, wherein the at least one system information block may comprise the common message.

[0174] The means configured for transmitting the random access response message may comprise means configured for: determining a beamformer based, at least partially, on channel state information; and transmitting the random access response message using the determined beamformer.

[0175] In accordance with one example embodiment, a (non-transitory) computer-readable medium comprising instructions stored thereon which, when executed with at least one processor, cause the at least one processor to: cause transmitting, to at least one user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; cause receiving, from the at least one user equipment, of at least one random access preamble; and cause transmitting, to the at least one user equipment, of the random access response message based, at least partially, on the at least one random access preamble.

[0176] In accordance with one example embodiment, a (non-transitory) computer-readable medium comprising program instructions stored thereon for performing at least the following: causing transmitting, to at least one user equipment, of at least one system information block thatmay comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; causing receiving, from the at least one user equipment, of at least one random access preamble; and causing transmitting, to the at least one user equipment, of the random access response message based, at least partially, on the at least one random access preamble.

[0177] The at least one system information block may further comprise at least one of: an indication that multiple-user multiple input multiple output transmission of random access response messages is enabled, a physical random access channel configuration, a format of a downlink control information message, or at least one time and frequency resource for receiving the random access response message.

[0178] The random access response message may be encapsulated with a downlink control information message, wherein the downlink control information message may be a user equipment specific downlink control information message associated with the at least one user equipment.

[0179] The random access response message may comprise a multicast random access response common message.

[0180] The random access response message may comprise a broadcast random access response common message.

[0181] The random access response message may be associated with the at least one user equipment and may be multiplexed with at least one random access response message associated with at least another user equipment.

[0182] The random access response message and the at least one random access response message associated with the at least one other user equipment may be multiplexed in a spatial domain.

[0183] The at least one user equipment and the at least one other user equipment may use a same modulation and coding scheme.

[0184] The at least one user equipment and the at least one other user equipment may use at least partially different modulation and coding schemes.

[0185] The random access response message may be scrambled with an identity of the at least one user equipment.

[0186] The random access response message may not comprise a common message, wherein the at least one system information block may comprise the common message.

[0187] The program instructions for performing causing transmitting of the random access response message may comprise program instructions for performing: determining a beamformer based, at least partially, on channel state information; and causing transmitting of the random access response message using the determined beamformer.

[0188] In accordance with another example embodiment, a (non-transitory) program storage device readable by a machine may be provided, tangibly embodying instructions executable by the machine for performing operations, the operations comprising: causing transmitting, to at least one user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; causing receiving, from the at least one user equipment, of at least one random access preamble; and causing transmitting, to the at least one user equipment, of the random access response message based, at least partially, on the at least one random access preamble.

[0189] In accordance with another example embodiment, a (non-transitory) computer-readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: causing transmitting, to at least one user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; causing receiving, from the at least one user equipment, of at least one random access preamble; and causing transmitting, to the at least one user equipment, of the random access response message based, at least partially, on the at least one random access preamble.

[0190] A computer implemented system comprising: at least one processor and at least one (non-transitory) memory storing instructions that, when executed by the at least one processor, cause the system at least to perform: causing transmitting, to at least one user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; causing receiving, from the at least one user equipment, of at least one random access preamble; and causing transmitting, to the at least one user equipment, of the random access response message based, at least partially, on the at least one random access preamble.

[0191] A computer implemented system comprising: means for causing transmitting, to at least one user equipment, of at least one system information block that may comprise, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message; means for causing receiving, from the at least one user equipment, of at least one random access preamble; and means for causing transmitting, to the at least one user equipment, of the random access response message based, at least partially, on the at least one random access preamble.

[0192] The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0193] It should be understood that the foregoing description is only illustrative. Various alternatives and modifications can be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination(s). In addition, features from different embodiments described above could be selectively combined into a new embodiment. Accordingly, the description is intended to embrace all such alternatives, modification and variances which fall within the scope of the appended claims.

Claims

CLAIMSWhat is claimed is:

1. An apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed with the at least one processor, cause the apparatus at least to:receive at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message;determine based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; andmonitor for the random access response message using the at least one determined resource and the demodulation reference signal port.

2. The apparatus of claim 1, wherein the at least one system information block further comprises at least one of:an indication that multiple-user multiple input multiple output transmission of random access response messages is enabled,a physical random access channel configuration,a format of a downlink control information message, orat least one time and frequency resource for receiving the random access response message.

3. The apparatus of claim 1 or 2, wherein a mapping of the demodulation reference signal port is based, at least partially, on at least one of:a physical random access channel preamble determined by the apparatus, ora random access occasion index associated with the determined physical random access channel preamble.

4. The apparatus of any one of claims 1 through 3, wherein the random access response message is encapsulated with a downlink control information message, wherein the downlink control information message is a user equipment specific downlink control information message associated with the apparatus.

5. The apparatus of any one of claims 1 through 4, wherein the random access response message comprises a multicast random access response common message.

6. The apparatus of any one of claims 1 through 4, wherein the random access response message comprises a broadcast random access response common message.

7. The apparatus of any one of claims 1 through 6, wherein the random access response message is associated with the apparatus and is multiplexed with at least one random access response message associated with at least another user equipment.

8. The apparatus of claim 7, wherein the random access response message and the at least one random access response message associated with the at least other user equipment are multiplexed in a spatial domain.

9. The apparatus of claim 7 or 8, wherein the apparatus and the at least other user equipment use a same modulation and coding scheme.

10. The apparatus of claim 7 or 8, wherein the apparatus and the at least other user equipment use at least partially different modulation and coding schemes.

11. The apparatus of any one of claims 1 through 10, wherein the random access response message is scrambled with an identity of the apparatus.

12. The apparatus of any one of claims 1 through 11, wherein the random access response message does not comprise a common message, wherein the at least one system information block comprises the common message.

13. The apparatus of any one of claims 1 through 12, wherein the instructions, when executed with the at least one processor, cause the apparatus to:determine that the random access response message comprises a multiple usermultiple input multiple output random access response message based, at least partially, on the indication of the demodulation reference signal port for monitoring for the random access response message.

14. The apparatus of any one of claims 1 through 13, wherein the instructions, when executed with the at least one processor, cause the apparatus to:transmit at least one random access preamble based, at least partially, on the at least one system information block.

15. A method comprising:receiving, with a user equipment, at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message;determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; andmonitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

16. An apparatus comprising means for:receiving at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message;determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; andmonitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

17. A computer-readable medium comprising program instructions stored thereon for performing at least the following:causing receiving, with a user equipment, of at least one system information block comprising, at least, an indication of a demodulation reference signal port for monitoring for a random access response message;determining based, at least partially, on the at least one system information block, at least one resource for reception of the random access response message; andmonitoring for the random access response message using the at least one determined resource and the demodulation reference signal port.

18. An apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed with the at least one processor, cause the apparatus at least to:transmit, to at least one user equipment, at least one system information block comprising, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message;receive, from the at least one user equipment, at least one random access preamble; andtransmit, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

19. A method comprising:transmitting, with a network node to at least one user equipment, at least one system information block comprising, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message;receiving, from the at least one user equipment, at least one random access preamble; andtransmitting, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

20. An apparatus comprising means for:transmitting, to at least one user equipment, at least one system information block comprising, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message;receiving, from the at least one user equipment, at least one random access preamble; andtransmitting, to the at least one user equipment, the random access response message based, at least partially, on the at least one random access preamble.

21. A computer-readable medium comprising program instructions stored thereon for performing at least the following:causing transmitting, to at least one user equipment, of at least one system information block comprising, at least, an indication of a demodulation reference signal port for the at least one user equipment to monitor for a random access response message;causing receiving, from the at least one user equipment, of at least one random access preamble; andcausing transmitting, to the at least one user equipment, of the random access response message based, at least partially, on the at least one random access preamble.

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