Systems and methods for beamformed uplink transmission

Abstract

To provide systems and methods for beamforming techniques and uplink control and data transmission techniques.SOLUTION: The techniques enable a UE to maintain at least one beam process for operation with multiple beams and / or points. A beam process may be indicated for transmission or reception over a downlink or uplink physical channel. Power, timing and channel state information may be specific to a beam process. A beam process may be established as part of a random access procedure in which resources may be provisioned in random access response messages. Techniques are provided for handling beam process failures, for using beam processes for mobility, and for selecting beams using open-loop and closed-loop selection procedures.SELECTED DRAWING: Figure 4

Description

Background Art

[0001] Cross - reference to Related Applications This application is a non - provisional application of U.S. Provisional Patent Application No. 62 / 334,754, entitled "Systems and Methods for Beamformed Uplink Transmission", filed on May 11, 2016; U.S. Provisional Patent Application No. 62 / 373,076, entitled "Systems and Methods for Beamformed Uplink Transmission", filed on August 10, 2016; and U.S. Provisional Patent Application No. 62 / 440,903, entitled "Systems and Methods for Beamformed Uplink Transmission", filed on December 30, 2016, and claims the benefit under 35 U.S.C. § 119(e). The entire disclosures of these applications are hereby incorporated by reference into this specification.

[0002] To meet the high data rate requirements for next - generation cellular communication systems, the wireless industry and academia are exploring ways to utilize the large bandwidths available at high frequencies, such as cmW and mmW frequencies.

[0003] These high frequencies can have propagation characteristics that are particularly inconvenient for wireless communication in outdoor environments. Higher - frequency transmissions can experience higher free - space path losses. Rainfall and atmospheric gases (such as oxygen and foliage) can add additional attenuation compared to sub - 6 GHz frequencies. Additionally, penetration and diffraction attenuation can be more severe at higher frequencies, such as at mmW frequencies.

[0004] All of these propagation characteristics can result in significant non - line - of - sight (NLOS) propagation path losses. For example, at mmW frequencies, the NLOS path loss can be more than 20 dB higher than the line - of - sight (LOS) path loss, severely limiting the coverage of mmW transmissions.

Prior Art Documents

Non-Patent Literature

[0005]

Non-Patent Literature 1

Summary of the Invention

[0006] To increase throughput in higher frequency bands and maintain sufficient coverage, a new radio (NR: New Radio) system uses more UE antenna elements compared to legacy systems. For a UE using 64 antenna elements, legacy techniques for controlling multi-antenna transmission become infeasible due to the overhead of transmitting up to 64 orthogonal reference signals and signaling precoders for up to 64 antenna ports. Exemplary embodiments enable a UE to determine a set of precoding weights and other parameters for uplink transmission or sidelink transmission.

[0007] Similarly, in the downlink direction, network equipment is equipped with more antenna elements compared to legacy systems, which may render current techniques infeasible. Exemplary embodiments enable the selection of precoding weights for reception (downlink or sidelink) and feedback to enable an appropriate selection of precoding weights on the network side. Exemplary embodiments also enable other desired design features of NR, such as not relying on the continuous transmission of common downlink reference signals that result in low energy efficiency and limited spectral efficiency.

[0008] The use of a narrow beam pattern during operation may cause the received energy to degrade rapidly during UE rotation and dynamic interference. When the channel varies rapidly due to the rotation of the UE itself or dynamic interferers during system procedures or active data transmission / reception, methods implemented by the UE for adjusting the beam and managing the beam process are disclosed herein.

[0009] Beamforming techniques as well as uplink control and data transmission techniques enable the UE to maintain at least one beam process for operation with multiple beams and / or points. The beam process can be shown for transmission or reception on a downlink physical channel or an uplink physical channel. Power, timing, and channel state information can be specific to the beam process. The beam process can be established as part of a random access procedure where resources can be provisioned in a random access response message. Techniques for handling beam process impairments, techniques for using the beam process for mobility, techniques for selecting a beam using open-loop selection procedures and closed-loop selection procedures are provided for simultaneous beam process power allocation, for example for maximum power back-off (MPR) of the beam process caused by SAR, for beam reselection by MPR, and for beam reselection and repair due to UE rotation and dynamic interferers.

[0010] The systems and methods disclosed herein provide support for a large number of antenna elements on the UE side used in 5G NR compared to legacy systems. The systems and methods disclosed herein are further related to the efficient selection of precoding weights for UE reception and transmission. The exemplary beam-based NR systems and methods disclosed herein reduce the reliance on the continuous transmission of common downlink reference signals to achieve energy efficiency and spectral efficiency.

[0011] In an exemplary embodiment, for operations involving one or more beams and / or points, the UE maintains one beam process per beam and / or point. The beam process can be indicated for transmission / reception on a downlink physical channel or an uplink physical channel. Power, timing, and channel state information can be specific to the beam process. The beam process can be established as part of a random access procedure in which resources can be provisioned during a random access response. The UE can monitor the link quality specific to the beam process and declare a link failure for the beam process based on individual beam quality or aggregated beam quality. The UE can handle mobility based on the use of the beam process. The UE can execute a beam selection procedure for each beam process using (i) an open loop, e.g., based on channel reciprocity, and / or (ii) a closed loop, e.g., based on beam measurements.

Brief Description of the Drawings

[0012] A more detailed understanding can be obtained from the following description, presented as an example in conjunction with the accompanying drawings.

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[0013] 5G Beam-Based Wireless Access Recent channel measurements performed by the wireless industry and academia have demonstrated the feasibility of achieving satisfactory cellular coverage with the aid of beamforming techniques. The measurement data shows that beamforming gain provides coverage for cellular control signaling and boosts link capacity to achieve higher data throughput in LOS conditions.

[0014] Channel propagation characteristics and extremely high data throughput for a 5G NR cellular system may require the use of beamforming on all physical layer signals and channels, including those for broadcast and common purposes, and focusing on beam-based or beam-centric procedures. 5G NR system design may enable beamformed access links with beamforming for most or all physical layer signals and channels. Physical layer signals and channels may apply different beamforming techniques, including digital beamforming, analog beamforming, and hybrid beamforming, and may remember their own beamforming configurations.

[0015] Beamforming may provide additional degrees of freedom in the angular domain compared to conventional cellular systems. System design may take into account beamforming and beam-based characteristics specific to each physical layer signal and channel and incorporate corresponding control and system procedures (such as uplink transmission, cell search, random access, and control channel decoding).

[0016] Beamforming Techniques Beamforming techniques include digital beamforming, analog beamforming, and hybrid beamforming. In digital beamforming, each antenna element may have a dedicated RF chain, including RF processing and ADC / DAC. Signals processed by each antenna element may be independently controlled in terms of phase and amplitude to optimize channel capacity. The number of RF chains may be equal to the number of antenna elements. While providing extremely high performance, digital beamforming techniques may be associated with high cost, implementation complexity, and high energy consumption.

[0017] Analog beamforming can apply one RF chain to several antenna elements that make up a phase antenna array (PAA). Each antenna element can use a phase shifter to set phase-only weights for beamforming and steering of the antenna pattern of the PAA. The number of RF chains applied can be significantly lower than the number of antenna elements. The number of RF chains can be the same as or lower than the number of PAAs. For example, multiple PAAs can be connected to a single RF chain, and each PAA can have an antenna pattern for a specific azimuth and elevation coverage. The RF chain can be switched to one PAA at a time to provide wide coverage by using one beam at different directions and time instances and by using a single RF chain with multiple PAAs.

[0018] Hybrid beamforming can combine digital precoding and analog beamforming. Analog beamforming can be performed on the antenna elements of a PAA connected to an RF chain. Digital precoding can be applied to the baseband signal for each RF chain and its associated PAA. The configuration of hybrid beamforming can include several data streams, several RF chains, several PAAs, and several antenna elements. The PAA connected to an RF chain can be represented by an antenna port uniquely identified by a beamformed reference signal, and the beamformed reference signal is unique to such an antenna port.

[0019] FIG. 1 is a graph 100 of an exemplary UE 3D transmission beam pattern using a 4×4 uniform linear array.

[0020] Figure 2 shows an exemplary UE block diagram of a hybrid beamforming system 200 with two transmitters 202, 204 and two phase antennas 206, 208. It starts with digital precoding 210 in the BB processing block 212. The I (214, 218) output signals and the Q (216, 220) output signals pass through the ADC blocks 222, 224 and the radio frequency processing blocks 226, 228 and are transmitted via the phase shift antenna arrays 206, 208 for analog beamforming.

[0021] The high implementation cost and high energy consumption for digital beamforming techniques can lead to implementation considerations for NR system design. 5G NR beamforming techniques can be based on hybrid beamforming using a considerably lower number of 5G NR transceiver nodes than the number of antenna elements. Analog beamforming techniques have a significant impact on L1 / L23 system procedures and can lead to the behavior and sequence of new procedures. Beamformed transmissions can provide a high degree of flexibility to the eNB to customize the transmission in both the time domain and the spatial domain to reduce signal overhead and energy consumption.

[0022] LTE / LTE-A Uplink Multi-antenna Techniques LTE and LTE-A enable multi-antenna techniques. In transmit antenna selection, open-loop antenna selection masks the scrambling on the uplink grant CRC bits. Closed-loop transmit antenna selection is configured by the upper layer based on optional UE capability reports. The Spatial Orthogonal Resource Transmit Diversity (SORTD) method is the same for UCI on different UE antennas using different orthogonal resources. In PUCCH, it uses dual antennas. In MU-MIMO, up to 8 UEs on the same set of RBs each use single-antenna transmission. Also, 3-bit PUSCH cyclic shifts and OCC for PUSCH DMRS provide orthogonality. The MU-MIMO method is transparent to the UE. In SU-MIMO, there is a precoder with CM preserving constraints (e.g., one layer per antenna). Also, the eNB selects a precoder based on non-precoded SRS and signals the number of layers and PMI using DCI 4. The SU-MIMO method uses SRS for each antenna port.

[0023] Control of Uplink Transmission The wireless system employs a mechanism to control the transmission from the UE (such as in the uplink or sidelink) in order to ensure appropriate link adaptation while preventing excessive interference to other UEs. Such a mechanism includes, for example, transmission power control, timing alignment, and transmission parameter indicators such as modulation, coding, and frequency allocation. In LTE, a UE equipped with multiple antenna elements can also be indicated by the precoding weights to be applied for transmission. This mechanism can use a UE that transmits a reference signal for each antenna element to determine a precoder that maximizes the quality at the receiver side. The use of such a precoder enables a reduction in the transmission power for a given transmission and thus, of course, can reduce the interference to the system. In LTE, the maximum number of reference signals (or antenna ports) for uplink transmission is 4.

[0024] UE Autonomous Rotation and Obstacle Detection It is not common for a UE to be equipped with various motion sensors including an accelerometer, a gravity sensor, a gyroscope, a rotation vector sensor, etc. The accelerometer and the gyroscope are hardware-based, and other software-based sensors can derive further motion data based on the inputs received from the two hardware-based sensors.

[0025] The sensor data provides the UE with detailed detection information regarding the rotational movement of the UE. The rotational movement can be a reflection of direct user input, such as the tilting, wobbling, rotating, or swaying movement of the UE during video game play. The detected rotation data enables the UE to calculate the angular change in the orientation of its own antenna array. The orientation change can be represented using the rate of rotation about the X / Y / Z axes and the respective vector components along each axis.

[0026] The movement sensor of the UE can collect data resulting from relative movement. The relative movement can provide reflections of the physical environment in which the UE is located. For example, in some embodiments, the movement sensor can detect the approach of a stationary obstacle due to the movement of the UE, or the movement of a moving obstacle towards a stationary UE. In such embodiments, the movement sensor data enables the UE to detect an upcoming interference and estimate the translational movement vector of the interference, including its speed and direction relative to the UE.

[0027] In an exemplary embodiment, the advanced movement sensor can operate to discriminate between a human body and an inert material. In such embodiments, the UE can thus not only detect an approaching interference but also distinguish whether the interference is a human body. This feature can be used by the UE to comply with the Specific Absorption Rate (SAR) regulations for handset devices.

[0028] Beam The term "beam" can be used in several different contexts in this specification. A beam can be used to mean a set of precoding weights or co-phasing weights applied to antenna elements in a user equipment (UE) or a network device (e.g., a transmission point or a reception point) for transmission or reception. The term "beam" can also refer to the antenna pattern or radiation pattern resulting from the application of such precoding weights, or to at least one reference signal transmitted while applying a set of precoding weights to antenna elements, or to at least one sequence used for the generation of at least one reference signal. There are other references to a set of properties associated with this antenna pattern, such as gain, directivity, beam width, beam direction (with respect to a reference plane) in azimuth and elevation, peak to side lobe ratio, etc., or to at least one antenna port associated with such an antenna pattern. Further, the term "beam" can refer to the associated number and / or configuration of antenna elements (e.g., a uniform linear array, a uniform rectangular array, or other uniform array).

[0029] Beam process A beam class refers to beams that share at least one characteristic, such as beam width or beam solid angle. A higher beam class refers to a higher level of directivity, and a lower beam class refers to a lower level of directivity. A beam family consists of all beams of the same beam class. A beam group is a set of beams associated with beams of a lower beam class. A beam can be associated with a beam of a lower beam class, for example, based on the beam with the closest central direction or the beam with the largest overlap or correlation.

[0030] Figures 3A and 3B are two graphs 300, 350 of beam amplitude versus direction 308, 316 showing the distinction between the central directions 304, 314 of the beams and the peak directions 306, 312 of the beams. The beam direction is the direction of the beam that can be defined as the central direction 304, 314 of the beam or as the peak direction 306, 312 of the beam. Figures 3A and 3B also show the EIRP peaks 302, 310 with black dots. The beam space is the area or solid angle covered by a set of beams that can have any weight vector. The beam space can be defined or defined by a set of parameters, such as a set of angles, or by the beam itself.

[0031] In some exemplary embodiments, the UE may set precoding weights and other parameters for the transmission and / or reception of signals, control, and data according to at least one beam process. The UE may calculate or modify values for such parameters and use these values in subsequent transmissions or receptions that refer to the beam process, for example, using beam process identification information. Such exemplary processes significantly reduce the overhead associated with the determination of precoding weights because it does not rely on the continuous transmission of reference signals and does not necessarily involve the signaling of precoding for every transmission. Such exemplary processes also reduce the implementation complexity for advanced transmission schemes, such as spatial multiplexing, beam diversity, or multi-site cooperation, by using two or more beam processes. The beam process may also be referred to as a beam pair link (BPL).

[0032] In transmission from the UE, the beam process may determine at least one set of precoding weights or co-phasing weights to be applied to the antenna elements. Such determination may form a beam, where each such set may correspond to an antenna port. The transmission beam process may determine a timing advance with respect to a downlink timing reference signal, or a transmission power level. In reception by the UE, the beam process may determine at least one set of precoding weights to be applied to the antenna elements for reception. Again, such determination may form a beam, where each such set may correspond to an antenna port. The beam process may also determine settings for an automatic gain control (AGC).

[0033] In some exemplary embodiments, a bi-directional beam process may control both transmission and reception and may determine separate sets of precoding weights or beams for transmission and reception. Alternatively, the beam process may control transmission only (transmission, or UL, beam process) or may control reception only (reception, or DL, beam process).

[0034] The UE may determine that the beams used in reception and transmission should have the same pattern or a similar pattern in each of the reception beam process and the transmission beam process or in the bi-directional beam process. Such determination may be based on higher layer signaling or may be implicitly based on the frequency band or another property of the system to which the UE is accessing or to which the UE is connected. In such a case, the UE may derive the precoding weights used in transmission based on the precoding weights determined for reception, or vice versa. In the case of the transmission beam process and the reception beam process, such processes may then be referred to as being associated by reciprocity. In the case of the bi-directional beam process, the process may be referred to as being reciprocal.

[0035] In some embodiments, a default beam process may be defined. Such a default beam process may be applied for downlink or uplink transmission in the absence of a specific configuration, or the default beam process may be determined from higher layer signaling. Such a default beam process may be predefined such that the resulting maximum beam gain or directivity is minimized, or the pattern is approximately omni-directional.

[0036] Also, the use of the default beam process may depend on the frequency band, for example, according to predetermined rules or higher layer signaling. For example, whether PRACH transmission should use the default beam process may be indicated as part of the RACH configuration provided by the system information. Such signaling may be beneficial when the network uses synchronized transmissions from multiple TRPs for the transmission of signals used by the UE for system timing and path loss estimation.

[0037] The UE may maintain one beam for each beam process. Such a beam may be initially selected and updated as part of a beam selection procedure. The beam selection procedure determines the beam that results in the best propagation channel (e.g., by maximizing the received signal power for a given transmit power) for a given beam or antenna applied to another UE (e.g., a network node).

[0038] Figure 4 shows an exemplary embodiment of beam propagation in system 400. Always, UE 402 can be composed of multiple beam processes to support spatial diversity or multiplexing, multi-site operation, and mobility. This is shown in Figure 4, where process 1 and process 2 correspond to the direct path 404 and the reflected path 406 to TRP1 (410), and process 3 corresponds to the path 408 to TRP2 (414). The reflected path 406 reflects off building 412, and the direct paths 404, 408 are line-of-sight. Each configured beam process can be considered to correspond to a transmission or reception instance with a specific antenna pattern that maximizes the beamforming gain along the channel path. The multiple beam processes can also be used to support different levels of beamforming depending on the type of information being transmitted and the associated reliability requirements, or whether the transmission is unicast or multicast.

[0039] The current beam refers to the latest result of the beam selection procedure. In a two-way process, the current beam can be applied to both transmission and reception. Alternatively, separate current beams can be applied for transmission and reception. Similarly, the beam selection procedure can select a separate beam for each antenna port, resulting in a current beam for each antenna port.

[0040] In some exemplary embodiments, when a beam process is applied to transmission or reception, the applied beam corresponds to the current beam. In some exemplary embodiments, UE 402 can maintain the beam selected in the previous beam selection procedure. For example, UE 402 can maintain the latest selected beam of a certain beam class only if such beam class (or beam gain) is lower than the beam class (or beam gain) of the current beam. When maintaining multiple beams for a beam process, each beam can be associated with beam identification information that can correspond to the beam class.

[0041] Some beam selection procedures may be based on performing a series of measurements taken from downlink reference signals. Such reference signals are referred to herein as beam selection reference signals. In some embodiments, UE402 may adjust the AGC setting based on such a beam selection reference signal. The beam process may be provisioned with resources for at least one such beam selection reference signal. The resources for provisioning the beam process reference signal may include at least one identification information parameter used to generate a sequence and indications of time resources and frequency resources. In some exemplary embodiments, the identification information parameter may be unique to the beam process.

[0042] Some exemplary beam selection procedures may be based on performing at least one transmission of an uplink (or sounding) reference signal called a beam sounding reference signal. The beam process may be provisioned with resources for at least one such beam sounding reference signal. The resources for provisioning the beam sounding reference signal may include at least one identification information parameter used to generate a sequence and indications of time resources and frequency resources. In some exemplary embodiments, the identification information parameter may be unique to the beam process. Also, the identification information parameter for the uplink may be the same as the identification information parameter used to generate the beam selection reference signal.

[0043] In some exemplary embodiments, the resources for the beam selection reference signal and the resources for the beam sounding reference signal can be dynamically allocated. Further, these reference signals can be allocated on a subset of the available time and frequency resources. Such allocation can be done to avoid continuous broadcasting of signals and to reduce high overhead costs. For example, downlink control information (such as signaling that triggers a random access response or a beam selection procedure), or a combination of downlink control information and upper layer signaling, can indicate the resource allocation.

[0044] The beam selection reference signal can be associated with a set of parameters used for spreading or scrambling. The parameters can include, for example, a spreading factor, a spreading sequence such as an index of an OVSF code and a Walsh code, and a scrambling sequence index.

[0045] As described below, various resources can be associated with a beam process for data transmission / reception.

[0046] The beam process for data transmission / reception can be associated with time domain resources including, for example, blocks of time units, symbols, subframes, slots, and frames. The beam process can also be associated with a set of frequency domain resources including, for example, subcarriers, blocks of subcarriers, resource blocks, sets of resource blocks, and wideband carriers. The beam process can be associated with code domain resources including, for example, the type of spreading and / or scrambling code (OVSF / Walsh / ZC code), the length of spreading / scrambling, and the index of the spreading / scrambling sequence.

[0047] The time / frequency / code resources associated with a beam process are static and can be preconfigured for a certain type of beam process. For example, the resources associated with the beam process used for the cell-specific common control channel in some embodiments are fixed and can be broadcast in system information broadcast transmission. In other embodiments, such beam processes can have fixed and predefined resource allocations. The beam processes for both data transmission and data reception can also be associated with resources that dynamically use downlink control information in physical layer control signaling. In another embodiment, the resource association information for each beam process can be carried in higher layer signaling such as RRC signaling.

[0048] The association of a beam process with resource allocation can enable a flexible configuration and reduced signaling overhead for beam processes connected to multiple TRPs or used for hierarchical control channels for downlink / uplink / sidelink.

[0049] UE402 can be configured to maintain two or more beam processes (see Figure 4), such as bidirectional processes or unidirectional processes. Each such beam process can correspond to reception or transmission for a specific antenna pattern such that the patterns of different beam processes maximize the antenna gain in different directions. Thus, for each beam process, UE402 can maintain precoding weights, Tx power, and timing. Each beam process can be associated with different network transmission points, e.g., TRPs. Connection to multiple TRPs can enable support for multi-site operation, diversity, seamless mobility, and fallback operation. Maintenance of two or more such beam processes can enable transmission and / or reception to and / or from multiple points and / or to a single point using different beams.

[0050] The beam process may be composed of beam process identification information for reference purposes. A particular beam process may be designated as a primary beam process or a master beam process. If UE402 maintains only one beam process, such a beam process may be designated as the primary (or master) beam process. If UE402 maintains two or more beam processes, UE402 may receive signaling for designating the primary beam process.

[0051] Control channel monitoring In some exemplary embodiments, UE402 may determine at least one beam process for decoding a downlink control channel, such as a physical downlink control channel or a physical broadcast channel. When attempting to decode the downlink control channel, UE402 may use the precoding weights determined by the beam process for reception.

[0052] In one embodiment, the beam process is associated with at least one control channel configuration that then determines the resources for which UE402 should attempt to decode downlink control information. The configuration may include at least one of the following: - At least one control resource set, control subband, or control time symbols within a scheduling unit such as a slot, mini-slot, or subframe. - At least one parameter used to derive at least one search space (or set of candidates) for an instance of a control channel within at least one control resource set. 〇 At least one search space may be defined with respect to at least control channel elements, resource element groups, sets of time symbols, and / or subsets of physical resource blocks within a control resource set. 〇 At least one beam process may be associated with a common search space. - At least one parameter used to determine a subset of possible scheduling units (e.g., slots), such as periods and offsets within a unit of slots (or minislots), in which downlink control information transmitted using a beam process may exist. In some embodiments, there may be two or more such configured subsets that can be selected based on the activity state or priority associated with the beam process. - At least one parameter used to determine at least one property of a reference signal, such as a sequence, used at least for the purpose of decoding a control channel.

[0053] The configuration can be obtained from RRC signaling, such as dedicated signaling and / or system information from at least a physical broadcast channel.

[0054] Independent configurations and exemplary usage scenarios For maximum flexibility, each beam process can be configured with, or associated with, an independent control channel configuration. For example, control subbands or resource sets can be configured differently between different beam processes, which can be useful in scenarios where they are associated with geographically separated TRPs that use different resources for the control channel to better coordinate interference.

[0055] In another example, the time symbols within a slot can be configured differently, which can be useful in scenarios where uplink data transmission and downlink data transmission involve different TRPs (e.g., a hetnet scenario with low and high transmission power TRPs). In such scenarios, a downlink allocation can be received from a first TRP using a first beam process, and an uplink grant can be received from a second TRP using a second beam process.

[0056] In some embodiments, at least one parameter of the control channel configuration may be common to all beam processes in order to reduce signaling overhead.

[0057] Prioritization between beam processes In some situations, there may be an overlap between the resources used by different beam processes, and as a result, reception using at least one such beam process may not be feasible. For example, this can occur when UE402 can only receive using at most N beam processes at a given time (where N may correspond, for example, to the number of RF chains in the UE receiver implementation), and there is an overlap in the time domain between the control channel candidates of more than N beam processes in a given slot. In another example, the control channel candidates for a first beam process may overlap with the scheduled transmission for a second beam process. When such a situation occurs, UE402 may apply a prioritization rule between beam processes based on at least one of the following criteria: - The configured priority associated with each beam process. For example, UE402 may prioritize the reception of the control channel for a primary beam process or based on an index associated with the beam process (e.g., a lower index has a higher priority). - The activity state associated with each beam process. For example, a beam process in an "active" state may be prioritized over a beam process in an "inactive" state, or if the quality for a beam process in an active state is degraded, the beam process in an "inactive" state may be prioritized to provide a fallback mechanism. - The periodicity for a subset of the scheduling units when the control channel is monitored for a beam process. For example, the priority may be given to the beam process with the greatest periodicity. - The most recently reported channel state indication for each beam process. For example, the priority may be given to the beam process with the highest channel quality indication. - The type of transmission associated with the beam process. For example, a scheduled transmission for a first beam process may have a priority that prevails over a control channel candidate for a second beam process. In another example, such a scheduled transmission may have been scheduled during a previous slot and may overlap with the control resource set of the current slot.

[0058] To handle instances where one rule does not allow for subdivision, multiple rules may be used. For example, UE402 may first assign priorities based on the activity state, and if two or more processes have the same activity state, rules based on the configured priorities may be used. Alternatively, other conditional orderings of the rules may be utilized.

[0059] Relationship with antenna ports In some exemplary embodiments, a fixed or semi-static association between a beam process and an antenna port or a set of antenna ports may be established. UE402 applies the precoding weights of the corresponding beam process whenever it is configured to transmit or receive on the antenna port. The set of (one or more) antenna ports associated with the beam process may be spatially quasi-collocated with each other. For example, when the association between the antenna port on which the demodulation reference is transmitted and the reference signal (such as CSI-RS or beam selection RS) used for beam selection and the antenna port on which it is transmitted for the beam process is defined, the association may indicate that such antenna ports are spatially quasi-collocated. Thus, an implicit or explicit indication of a beam process for reception using an antenna port may be equivalent to an indication that this antenna port is spatially quasi-collocated with the reference signal of the beam process or beam pair link (e.g., CSI-RS). Alternatively, in some exemplary embodiments, the association between the beam process and the antenna port may be dynamically modified. UE402 may determine an applicable beam process for transmission or reception on the antenna port.

[0060] In an exemplary embodiment, an applicable beam process can be determined from an explicit indication received from physical layer signaling or upper layer signaling. For example, UE 402 may receive downlink control information (DCI) indicating an uplink (or sidelink) transmission (grant) on an uplink (or sidelink) physical channel, and such a grant may include an indication of an applicable beam process for transmission on each antenna port. Such a beam process may be different from the beam process used to receive the DCI. In another exemplary embodiment, UE 402 may receive downlink control information indicating a downlink allocation for reception from a downlink physical channel, and such an allocation may include an indication of an applicable beam process for reception on each antenna port. In yet another exemplary embodiment, UE 402 may receive a MAC control element or an RRC message indicating an applicable beam process for transmission or reception on each antenna port for a subsequent transmission or reception on an uplink physical channel, a sidelink physical channel, or a downlink physical channel.

[0061] In another exemplary embodiment, the applicable beam process may be implicitly determined based on the beam process used to decode the associated transmission. For example, the applicable beam process for a downlink transmission may correspond to the beam process used to decode the DCI indicating this downlink transmission from the downlink physical control channel. In some cases, the downlink transmission may be a downlink physical data channel, a second downlink physical control channel, or a downlink signal such as DM-RS or CSI-RS. In another example, the applicable beam process for an uplink transmission (e.g., an uplink physical channel or signal) may correspond to the beam process used to decode the DCI indicating or triggering this uplink transmission. In particular, the applicable beam process for an uplink control channel including HARQ-ACK feedback associated with a downlink data transmission may correspond to the beam process used to decode the DCI indicating the transmission of this downlink data, and / or the applicable beam process for an uplink control (or data) channel including CSI reporting may correspond to the beam process used to decode the DCI indicating the transmission of the (one or more) reference signals, e.g., CSI-RS, from which the report is derived. In another example, the applicable beam process for an uplink control channel including HARQ-ACK for a downlink transmission may correspond to the beam process used to decode the downlink transmission. In another example, the applicable beam process for a random access response may correspond to the beam process used to transmit the random access preamble.

[0062] In the above example, the correspondence between the beam processes can be that both processes are equivalent (e.g., for a bidirectional beam process), or that both beam processes are associated by reciprocity.

[0063] Alternatively, in some embodiments, the correspondence may be configured by physical layer signaling or upper layer signaling. For example, when a certain beam process is used to decode DCI indicating this transmission, the applicable beam process for UL data transmission may be configured by RRC signaling. Such embodiments may enable transmission and reception from different network TRPs, which may be advantageous in heterogeneous deployments where the best node for downlink transmission may be a high-power TRP and the best node for uplink transmission may be a (closer) low-power TRP. In another example, the applicable beam process for random access response may be configured to correspond to the default beam process (e.g., an omni-directional beam is so configured as part of the RACH configuration). Such a configuration may enable synchronized transmission of random access responses from multiple TRPs.

[0064] In another example, the correspondence may be obtained more dynamically, such as by MAC signaling or physical layer signaling. Such embodiments may enable the use of different beam processes for control or data reception on one hand and data transmission on the other (e.g., having beams in different directions). This may be beneficial if the configured maximum transmission power for one beam process is lower than that for another beam process, such that the best beam process for downlink reception is not the beam that enables the best performance for uplink transmission. Such a situation may occur, for example, due to SAR requirements that affect some beam processes more than others. In such a case, for example, UE402 may notify the network of different configured maximum transmission powers by transmitting one or more power headroom reports triggered by a change in power management maximum power reduction (P-MPR) for at least one beam process.

[0065] In another embodiment, the applicable beam process may be implicitly determined based on the time resources and / or frequency resources occupied by the transmission. The correspondence between the resources and the beam process may be provided by upper layer signaling.

[0066] In another exemplary embodiment, the applicable beam process may be determined based on the physical channel or signal type on which the transmission or reception is performed.

[0067] In another exemplary embodiment, the applicable beam process may be determined based on the type and / or content of the transmission, such as whether the transmission consists of control information (e.g., uplink or sidelink) or upper layer data, or whether the transmission is multicast or unicast (e.g., for sidelink transmission). For example, the transmission of a scheduling request may be performed using a specific beam process, such as a primary beam process.

[0068] When maintaining multiple beams for a beam process, embodiments similar to those described above may be used to determine which beam identification information is applicable to a particular transmission. In some embodiments, the sequence used for generating the demodulation reference signal may be specific to the beam process. Such a sequence may be generated using identification information parameters that match the identification information parameters used for generating the sequence for the beam selection reference signal or the beam sounding reference signal.

[0069] Beam correspondence determination In some embodiments, the UE 402 may determine a correspondence between at least one pair of a transmission beam and a reception beam, for the beam used for transmission (transmission beam or uplink beam) and the beam used for reception (reception beam or downlink beam). When such a correspondence is determined, the UE 402 may determine that the transmission beam used for the first transmission from the UE 402 is the transmission beam corresponding to the reception beam used for receiving the second transmission. Such a reception beam may correspond to the reception beam that maximizes the signal strength or quality when receiving the second transmission. The following paragraphs describe such embodiments.

[0070] Predetermined or static beam correspondence In one embodiment, the beam correspondence may be predetermined for at least a subset of all transmission beams and reception beams according to a mapping stored in the memory. The mapping may be performed as part of a calibration or test procedure. The mapping may be such that the difference in the radiation pattern (or its properties such as the direction where the gain is maximized) between the transmission beam and its corresponding reception beam is minimized. The mapping may also be such that the precoding weights used for the transmission beam and the reception beam have equal or approximately the same value.

[0071] Dynamic beam correspondence state In some embodiments, the beam correspondence between the transmission beam and the reception beam may not always exist due to implementation conditions (e.g., the difference between the TX RF path and the RX RF path) and / or operating conditions (e.g., temperature change, reference clock phase drift) such that the determination of the beam correspondence is dynamic.

[0072] The dynamic beam correspondence state can be indicated in-state and out-of-state. The beam correspondence state can be specific to an individual beam, beam type, beam class, beam group, or antenna panel, or to a set of beams, beam types, beam classes, beam groups, or antenna panels. UE402 can be configured with a beam correspondence update period and can periodically evaluate and update beam correspondence according to the update configuration. UE402 can perform a beam correspondence state update in response to receiving L1 control signaling or upper layer (MAC, RRC) signaling from the network. In another embodiment, UE402 can trigger a beam correspondence update at a predefined event that can include one or more of the following procedures: - Reconfiguration of a new beam, beam type, beam class, beam group, or antenna panel, - During or at the end of the RACH procedure, for example, by incorporating update procedure steps into Msg1 transmission and / or Msg3 transmission, or - Configuration of the UL beam management procedure. The network can determine whether the UL beam management can be configured according to the beam correspondence state. The network may not configure any such procedure, such as U1, U2, or U3, if the beam correspondence state is in-state.

[0073] In one embodiment, UE402 can update the beam correspondence state by evaluating the transmission beam radiation pattern and the corresponding reception beam radiation pattern and comparing / correlating pattern parameters such as peak lobe direction, 3dB main lobe width, side lobe direction, side lobe width, side lobe suppression ratio, etc. The comparison and evaluation criteria can be predefined.

[0074] In another embodiment, UE402 can update the beam correspondence using a beam correspondence update procedure. In one embodiment, UE402 can perform the following actions: - Use uplink beam sweeping based on a set of uplink transmission beams to transmit beam-specific reference signals, e.g., SRS. - Monitor downlink control information in all receiving beams corresponding to the uplink transmission beam, where the downlink control information may include best uplink transmission beam identification information, e.g., a beam index or SRS resource indication (SRI). - Receive downlink control information in one or more receiving beams (e.g., when UE402 is located at the center of two downlink beams), and verify whether the best receiving beam can correspond to the uplink transmission beam identification information received in the downlink control information. - If the verification results match, determine within the beam correspondence state; if the verification results do not match, determine outside the beam correspondence state. - Report the beam correspondence state using uplink control signaling.

[0075] In another embodiment, UE402 may perform the following actions: - Transmit in a first transmission using a beam-specific reference signal, e.g., via SRS in an uplink beam corresponding to the best downlink beam (e.g., based on an SS block), where the SRS resource / sequence may carry an indication of the best SS block. - Transmit a second transmission using uplink beam sweeping based on a set of uplink transmission beams having a beam-specific reference signal, e.g., SRS, including those used in the first transmission. - Receive an in-beam or out-of-beam indication in downlink L1 control signaling from the network.

[0076] In this embodiment, the network may determine the beam correspondence state by verifying whether the first SRS is the same as the best SRS received in the second transmission. It should be noted that the network may use the received beam corresponding to the indicated best SS block in both the first UE transmission and the second UE transmission.

[0077] UE402 may be configured to execute an UL beam management procedure (U1 / U2 / U3) when the UE beam correspondence state is out of state. In this embodiment, UE402 may be configured with an explicit association between the uplink beam and the downlink beam.

[0078] When the UE beam correspondence state is in state, UE402 may receive an instruction in the L1 control signaling or the upper layer dedicated signaling to select an uplink beam based on the downlink beam without an UL beam management procedure. In this embodiment, UE402 may maintain an implicit uplink and downlink beam association.

[0079] In another embodiment, UE 402 may determine beam correspondence based on an instruction from the network. Such an embodiment may be applicable, for example, when the beam correspondence already exists on the network side. UE 402 may first transmit a sequence of beam-specific reference signals (e.g., SRS) for at least one beam (e.g., beam sweep). Such transmission may be triggered by signaling from the network in the physical layer or upper layer. UE 402 may then receive an indication of the transmission beam, for example, using an SRS indicator, together with an indication of CSI-RS (or CSI-RS indicator) corresponding to a certain downlink transmission beam. Such an indication may be included in the same instance of physical layer signaling (downlink control information), MAC signaling (MAC control element), or RRC message. The indication may be combined with an indication that the CSI-RS is transmitted at a certain time. When the indicated CSI-RS is received, UE 402 may determine the receive beam that maximizes the signal quality. UE 402 may determine that there is a beam correspondence between this receive beam and the transmit beam used for the transmission of SRS indicated by the network.

[0080] Power Control - Open-Loop Component In some exemplary embodiments, the transmit power may depend on the beam process applicable to the transmission.

[0081] The transmit power may be a function of the path loss measurement taken on the downlink reference signal. Such a downlink reference signal may sometimes be referred to as a beam path loss reference signal. Resources for such a beam path loss reference signal may be allocated independently for each beam process. In some exemplary embodiments, the beam path loss reference signal may coincide with the beam selection reference signal. The path loss measurement PL may be defined as the difference (in dB) between the reference transmit power P ref when the current beam is applied and the received signal power P r as received.

[0082] The beam used for measurement can be at least a receiving beam for a counter - directional beam process or can correspond to a receiving beam process associated with a transmitting beam process by counter - directionality. Alternatively, the beam used for measurement can be a predefined beam such as an omnidirectional beam or a default beam. Alternatively, the UE can select a receiving beam or beam process that minimizes the estimated path loss or maximizes the received signal.

[0083] Alternatively, the receiving beam used for path loss measurement can be determined from signaling. For example, whether the receiving beam or the UE 402 should use a default beam process or select a beam process can be signaled from the system information. Such embodiments can be used, for example, to determine the path loss estimate and transmission power for PRACH transmission.

[0084] In some exemplary embodiments, the path loss measurement can be adjusted by the gain or directivity G of the beam used for taking the measurement. As expressed by the formula, the path loss measurement PL can be calculated as follows: b PL = P PL = P ref - P r + G b , In the above formula, P ref and P r can be in dBm units, and PL and G b can be in dB units. This adjustment can enable appropriate compensation for the difference in gain (or directivity) between the beam used for taking the path loss measurement and the beam used in subsequent transmissions. In the latter case, the transmission power for a beam with gain G b ’ can be set as a function of (PL - G b ’), where PL and G b ’ are in dB units. In some embodiments, the path loss measurement PL may not be adjusted and can be equal to (P ref - P r ), but the transmission power is PL + Gb -G r can be set as a function of

[0085] Power control - Closed-loop component UE402 may receive signaling (Transmit Power Control (TPC) command) to perform adjustment of the power applied to some transmissions. Such adjustment may be cumulative for each beam process (applied to all subsequent transmissions to which a particular beam process applies). The beam process may be explicitly identified together with the TPC command or may be implicitly based on the beam process corresponding to the transmission to which the TPC command is applied. Also, the value of the adjustment step may be configured independently for each beam process.

[0086] Power control - Configured maximum power (P cmax ) In some embodiments, UE402 may apply a configured maximum power (e.g., P cmax ) for each beam process based at least on a maximum power reduction parameter (e.g., MPR, A-MPR or P-MPR), where P cmax and the maximum power reduction parameter may vary between beam processes. For example, this may be due to the beam-specific power management MPR (P-MPR) value from the specific absorption rate (SAR).

[0087] Configured maximum gain or configured maximum EIRP In some embodiments, UE402 may operate to limit the gain of the beam with respect to the maximum possible gain considering the antenna configuration. Such a situation may occur, for example, when UE402 is operating to meet the specific absorption rate requirement.

[0088] The configuration parameter is, for example, EIRP, maximum gain (G max) and may include maximum directivity. The parameters may be based on the UE402 capability report regarding the UE antenna array beamforming configuration and capabilities. The eNB may configure the parameters using upper layer signaling. In another solution, the UE402 may autonomously set the maximum gain or directivity.

[0089] The UE402 may operate to maximize the EIRP using both the P cmax and the maximum gain parameter for each beam process. The G max parameter may be affected by the physical channel associated with the beam process. For example, a beam process for uplink control information (UCI) transmission in the physical layer uplink control channel may be specified with a lower G max . Accordingly, the UE may transmit UCI in a beam process with a wide beam width. The advantage may be to increase the reliability and robustness of UCI transmission.

[0090] The UE may report, for each beam process, the offset between the beamforming gain actively applied and the configured maximum gain. The difference may be caused, for example, by the MPR caused by the SAR. The eNB may receive the G max offset and trigger an uplink beam reselection procedure for the associated beam process. Such an embodiment may enable the eNB to flexibly adjust uplink reception based on the beam width and beamforming gain used for the beam process.

[0091] Power allocation for simultaneous beam processes connected to different TRPs UE402 can be associated with different TRPs in a mobility event and add beam processes to be transmitted thereto. The association may include uplink beam power control information specific to the new TRP. UE402 can receive power control configuration parameters of the new TRP including an uplink SINR target and a TRP reference signal power. UE402 can also receive the configuration of the new TRP for waveform and numerology, and accordingly derive the required initial power and power steps.

[0092] The UE can provide the power headroom information calculated for the associated beam process to the new TRP. The calculation may consider the transmissions of all simultaneous transmissions of all active beam processes maintained by UE402. Accordingly, the power headroom may include fields for beam process identification information and its corresponding power headroom values.

[0093] In embodiments where the TRPs are synchronized, the transmissions can be code multiplexed on the same frequency resource.

[0094] In another embodiment, UE402 can be composed of gaps on one TRP link when the TRPs are not synchronized or are spread across frequencies or bands in order to enable and maximize power transmission capabilities. This may be useful during mobility events in non-synchronized TRPs (e.g., in the case of FDD).

[0095] The gaps can be configured by the network at UE signaling events, for example, based on the quality of the current link(s). These gap patterns can have different lengths and can have a finite duration aimed at causing UE402 to report measurements. Then, the network can determine which TRP to use and can send a configuration message, or an instruction for the UE to start monitoring some control channels on some TRPs for scheduling, or an instruction regarding the UL transmission start point with appropriate parameters.

[0096] UE402 may not rely on the configured gap if it has the capabilities of two or more transceiver chains. In this particular case, synchronous or asynchronous reception / transmission may be available, and network signaling is reduced to a target TRP measurement indication indicating the (one or more) target TRPs after receiving a measurement report from UE402. The target TRP measurement configuration may be a triggered message based on the quality threshold of the report triggered by UE402. In this situation, the output power is carrier aggregation or dual connectivity P cmax Shared among these UL transmissions in a similar way as the definition. However, if deployment-specific situations occur where power sharing will not result in good outcomes, the network may configure a gap on the serving TRP to enable simultaneous connection with the target TRP. In this case, the gap determination may be based on the reported measurements from UE402, where the path loss estimate may indicate possible scaling on the target TRP UL while maintaining the serving TRP.

[0097] Transmission Timing for Beam Processes In some exemplary embodiments, the timing of transmission may depend on the applicable beam process. UE402 may determine the timing of transmission based on the timing of the downlink received signal, which may be referred to as a beam timing reference signal. Resources for such a beam timing reference signal may be provisioned independently for each beam process. In some exemplary embodiments, the beam timing reference signal may be equivalent to the beam selection reference signal.

[0098] UE402 may determine the transmission timing based on the timing advance or adjustment to be applied from the timing of the beam timing reference signal. Such timing advance or adjustment may be received from physical layer signaling, MAC signaling, or RRC signaling, such as a timing adjustment command. The timing adjustment is specific to a beam process and may be applied to all subsequent transmissions to which a particular beam process is applied. The beam process may be explicitly identified together with the timing adjustment command or may be implicitly based on the beam process corresponding to the transmission to which the timing adjustment command is applied.

[0099] In some exemplary embodiments, the time alignment timer may be configured for each beam process, with a value specific to this beam process in some cases. The time alignment timer for a beam process may be restarted each time a timing adjustment command is received for this beam process. UE402 may be enabled to perform transmissions according to the beam process only when the time alignment timer for this beam process is running (not expired).

[0100] Quasi - collocation assumption In some exemplary embodiments, UE402 receiving a downlink physical channel using a beam process may assume that the antenna port from which the reference signal associated with the beam process is transmitted is quasi - collocated with the antenna port(s) from which the downlink physical channel is transmitted, for at least one long - term channel property (such as timing, delay spread, or Doppler spread). Such a reference signal may correspond to the beam selection reference signal associated with the beam process.

[0101] Channel state information for each beam process In some exemplary embodiments, UE 402 may report channel state information for each beam process. UE 402 may perform measurements on at least one channel state information reference signal (CSI-RS) and at least one interference measurement (IM) resource. Resources for such signals may be provisioned independently for each beam process. The measurements may be performed using the current beam of a particular beam process. Physical layer signaling, such as an instance of downlink control information, may identify the beam process and, optionally, the current beam. Such downlink control information may include any of the following information: a request to perform CSI measurements, a request to report the measured CSI, an allocation of resources for CSI-RS, or an allocation of resources for interference measurements.

[0102] Beam process synchronization state In some exemplary embodiments, the synchronization state may be associated with a beam process. UE 402 may determine that the beam process is in a "synchronized" state if a synchronization timer is running and / or if the latest beam selection procedure has completed successfully. The synchronization timer may be restarted upon successful completion of the beam selection procedure of a beam process that results in at least one current beam. The duration of such a timer may be predefined or configured by a higher layer or per process. If UE 402 detects that the beam selection procedure has started and failed, the UE may stop the synchronization timer.

[0103] If UE 402 measures a signal that exceeds the level or quality for at least one beam, or if UE 402 receives an indication from the network that a beam sounding reference signal has been successfully received, UE 402 may determine that the beam selection procedure has been successful. UE 402 may be allowed to perform transmissions using the beam process only if the beam process is in a "synchronized" state or while an applicable synchronization timer is running.

[0104] Beam process procedure Beam creation procedure The procedures described in the following paragraphs can be used to create the first (or primary) beam process and / or synchronize the first beam process, create additional beam processes, or delete beam processes.

[0105] UE 402 may initially not have a beam process or may have a default beam process that is not in a synchronized state. Such a situation can occur, for example, before first accessing the system or after it has been determined that the beam process is not in a synchronized state. Creation of the first beam process (or synchronization of the default beam process) can be part of the first system access.

[0106] In an exemplary embodiment, UE 402 may initiate a random access procedure based on measurements taken on a signature sequence and / or a mobility reference signal and based on a random access configuration that may be broadcast. UE 402 may randomly select a signal, such as a preamble from among preamble groups. In some exemplary embodiments, the preamble group may depend on the beamforming capabilities of UE 402. Transmission of such a preamble may use a default beam, such as a very wide beam or a nearly omnidirectional beam. Alternatively, transmission of the preamble may use that beam if UE 402 can determine the beam for measurements taken on signals available to it.

[0107] UE402 may receive at least one random access response and, optionally, attempt to retransmit the preamble at a higher power level if such reception does not occur within a time window. UE402 may ultimately decode at least one random access response and select one such response. Each such response may include at least the configuration and resources applicable to the beam process. Such a response may include at least one of the following items, namely, resources for beam selection reference signals, resources for beam sounding reference signals, timing advance adjustment, beam process identification information, and at least one parameter for power control (such as reference transmission power). If no parameter for power control is provided, this parameter may use a value broadcast as part of the random access configuration.

[0108] The random access response may include other information elements used for the first transmission on the uplink physical channel. The resources for beam selection reference signals may occupy several symbols that occur after a time offset following the random access response. Such a random access response may be predefined or signaled during the random access response. The UE may measure such resources to determine the best beam (or current beam) for reception. If the UE receives more than one random access response, UE402 may measure on the corresponding beam sounding reference signal resources for more than one and select, at least based on the measured signal quality or level among all the responses, which random access response to follow for subsequent transmissions.

[0109] UE402 may use the current beam for transmission on the beam sounding reference signal resource (for the beam selection reference signal of the selected random access response). Such a resource may generally occupy several symbols that occur after a time offset following the last symbol used for the beam selection reference signal resource. Transmission on the beam sounding reference signal resource enables the network to determine the best beam at the transmission / reception point (TRP). In some exemplary embodiments, UE402 may proceed with the procedure if it receives an indication of successful reception from the network following transmission of the beam sounding reference signal. Subsequent transmission and reception on the uplink physical channel and the downlink physical channel may use the current beam determined from measurements of the beam selection reference signal. Thereafter, further refinement of the current beam may be initiated by the network.

[0110] In some exemplary embodiments, UE402 may utilize at least one parameter provided for the beam selection reference signal resource and the beam sounding reference signal resource for generation of demodulation reference signals in the uplink and downlink. For example, such parameters may consist of identification information parameters used to determine a sequence.

[0111] In some exemplary embodiments, UE 402 may receive an indication for the creation of a new beam process from physical (or higher) layer signaling. The indication itself may be received using an existing beam process. For example, such an indication may consist of downlink control signaling that triggers a random access procedure. Resources for the new beam process may be provided during a subsequent random access response, as in other exemplary embodiments. Alternatively, the indication may directly allocate resources for the new beam process and directly trigger reception and transmission on the beam selection reference signal and the beam sounding reference signal, respectively. In such a case, the applicable timing advance may be the same as the existing beam process used to receive the indication.

[0112] In some exemplary embodiments, UE 402 may receive an indication for the deletion of an existing beam process from physical (or higher) layer signaling. UE 402 may perform measurements for the beam process. Such measurements may enable UE 402 to identify the best beam within the beam process. For example, UE 402 may be configured to use a beam (the current beam) within the beam process configuration. UE 402 may perform measurements using that beam together with a subset of other beams (possibly beams within a beam group defined later). Such measurements may be periodic and configured by the network. In another exemplary embodiment, such measurements may be aperiodic. For example, UE 402 may be triggered by its serving TRP to perform such measurements, possibly via transmissions using that beam process. In another example, the UE may be triggered to perform such measurements on a beam group by measurements performed on a beam associated with the beam process.

[0113] When taking such measurements, UE 402 may determine that a new beam improves reception (and possibly transmission) from / to the TRP / cell / eNB. In such a case, UE 402 may autonomously update the beam process to include the new beam. UE 402 may also indicate to the network (e.g., via transmissions using the beam process itself) that UE 402 has changed its beam. This may enable the network to determine whether its own beam still best suits the new UE beam. In another exemplary embodiment, when it is determined that a new beam may improve the execution of the beam process, UE 402 may request the network to initiate a new beam selection procedure. Such a process may or may not require UE 402 to use the newly determined beam.

[0114] Mobility-related aspects When measurements on a set of beams (beams within a beam group) are triggered, UE 402 may fail to find a suitable beam to use within the beam process. For example, UE 402 may initiate a synchronization process based on measurements on the original beam process configuration that indicate that it cannot successfully transmit and / or receive data using the beam process. Such a conclusion may be based on the measurements being less than a threshold. In this case, UE 402 may be instructed to find another beam to use within the beam process before continuing to use the beam process. If UE 402 fails to obtain another beam within the beam group, it may perform at least one of the following actions: continue to search for a beam in another beam group or possibly in the same beam class, continue to search for a beam in another beam class or a beam class that overlaps with the previously selected beam, or declare a radio link failure (RLF) or beam link failure (BLF) for the beam process. Whenever RLF is used herein, it includes BLF.

[0115] If the UE402 determines an RLF for a beam process, it may indicate such a situation to at least one serving TRP. If the UE402 is still configured with an operational (such as non-RLF) beam process, the UE402 may indicate to the TRP the identification information of the beam process that has received the RLF. In one embodiment, the UE402 may send an uplink beam recovery transmission to carry the indication. Moreover, in the beam recovery transmission, the UE402 may request a switch to a target beam process, for example, an operational (such as non-RLF) beam process, to maintain the UE radio link. The UE402 may use pre-configured time / frequency / code / beam resources for the beam recovery transmission. For example, the UE402 may use the uplink transmission beam associated with an operational (such as non-RLF) beam process. In another example, the UE402 may send the beam recovery transmission on the default UL beam. The beam recovery transmission may be repeated over multiple symbols, slots, or transmissions to enable beam sweeping at the receiver. In another example, the UE402 may send the beam recovery transmission in a mode of uplink beam sweeping using the uplink beams associated with all configured beam processes. The UE402 may monitor and receive a switching command during downlink L1 control signaling. The switching command may be received by the UE402 on the default beam pair link (for example, a wide beam Tx and Rx beam pair that may also be omnidirectional). The switching command may indicate the resources where the UE402 may perform beam capture. In another embodiment, the switching command may explicitly indicate to the UE402 one or more BPLs to be used for the next transmission. In another embodiment, the UE402 may monitor and receive a switching command during downlink L1 control signaling for the downlink beam associated with the target beam switching process.

[0116] If the UE no longer has any operational beam processes (e.g., if the UE is configured with a single beam process and that beam process has experienced an RLF), the UE may perform a new first beam process capture. In another exemplary embodiment, the UE may be configured with a master beam process or a primary beam process. A declaration of RLF on such a beam process may trigger the UE to perform a new first beam process capture. Such a process may remove all existing beam processes. During such a process, the UE 402 may indicate to the network whether the RLF occurred on one (such as master or primary) beam process (e.g., on all beam processes associated with that TRP / cell / eNB) or on all beam processes.

[0117] In an exemplary embodiment, the first beam process capture may use a random access procedure. In such a case, the UE 402 may be preconfigured with resources and / or preamble values to perform non-competition-based RA for beam process (re)capture. In another example, the UE may have connectivity to a second TRP / cell / eNB. The second TRP / cell / eNB may provide the UE with random access resources (or preambles) for performing non-competition-based random access if it declares an RLF on one or all of the beam processes of the first TRP / cell / eNB in some cases.

[0118] UE 402 may maintain measurements on at least one mobility reference signal (MRS). Such mobility reference signals may be transmitted per TRP or on orthogonal resources for each TRP. The mobility measurements may use a specific beam process (such as a beam process dedicated to such measurements). UE 402 may decide to add a new beam process. Such a decision may be triggered by measurements on at least one MRS indicating the possibility of obtaining one or more new beam processes, a decision by UE 402 that it will improve reception performance or transmission performance, the location of the UE, or RLF on one or more beam processes associated with the TRP / cell / eNB. UE 402 may improve reception performance or transmission performance via increased diversity with the addition of a new beam process. In another exemplary embodiment, UE 402 may require that the new beam process enable transmission and reception such as CoMP. With respect to location, UE 402 may store its location with respect to different TRPs and may decide that one or more new beam processes may be requested from a new TRP. When deciding to add a new beam process, UE 402 may indicate to the network the measurements taken or an explicit indication to add one or more new beam processes (or to replace an existing beam process with a new beam process). This indication may initiate a new procedure for beam process capture.

[0119] (Such as when there are remaining unused TRX chains) If UE 402 can add a new beam process without removing another beam process, UE 402 may indicate that the new beam process may be added to the list of existing beam processes. Alternatively, the network may be notified of the UE's beam process capabilities and may initiate adding a beam process without removing the previous beam process.

[0120] In another exemplary embodiment, the UE 402 may indicate to the network that it cannot add a new beam process without removing the existing beam process or at least modifying the parameters of the existing beam process. Further, the UE 402 may indicate to the existing beam process a request to add a new beam process. For example, the UE 402 may indicate that the existing beam process may be configured for a subset of time resources. The UE 402 may indicate a set of (one or more) beam processes to be used for such time resource limitations.

[0121] The UE 402 may indicate to the new TRP / cell / eNB, if applicable, which time resources should be configured for the new beam process. The new beam process may be configured for an orthogonal set of time resources. This configuration change may enable coexistence of the new beam process with the previously configured beam processes.

[0122] The UE 402 may maintain a set of beam processes. Elements of such a set may include beam processes that can be used simultaneously. Such a set may include fewer elements than the maximum number of TRX chains of either the UE 402 or the TRP / cell / eNB. A beam process may be included in more than one set. For example, the UE 402 may have a first beam process without time limitations, a second beam process applicable to a first set of time resources, and a third beam process applicable to a second set of time resources orthogonal to the first set of time resources. In such a case, the UE 402 may maintain a first set of beam processes having the first beam process and the second beam process, and a second set of beam processes having the first beam process and the third beam process. The time limitations for the previously configured beam processes and the new beam processes may remain suitable until reconfigured by the network or until the UE 402 requests a change in parameters on one or more beam processes.

[0123] In an exemplary embodiment, when triggering a mobility event, UE 402 may assume that one beam process (or all beam processes) may use a pre-configured set of time resources. One beam process may be the master beam process, or the time resources may be determined based on the beam process ID. The UE may perform beam process capture on time resources orthogonal to the time resources used for the previous beam process. When completing the mobility event, UE 402 may assume that the new beam process is valid for all time resources, and the previously configured beam process restricted during the mobility event may be completely removed.

[0124] UE 402 may use different beam process capture methods depending on the additional cause of the beam process. For example, if the cause is to increase the number of beam processes, such as increasing diversity or multiplexing, UE 402 may attempt to obtain a new beam process based on rules attached to the existing beam process. In this example, UE 402 may test a restricted set of beams (or beam groups or beam classes) to obtain the new beam process. The restriction may ensure the addition of the new beam process to the existing set of beam processes, and the new beam process is less likely to be correlated with the existing beam processes.

[0125] In another example, when UE 402 is required to add a new beam, for example due to RLF, UE 402 may start the process using a specific beam group and / or class. This methodology may ensure finding a new beam process within a shorter time period, regardless of whether the new beam process optimizes the transmission / reception performance. For example, UE 402 that has received RLF using a beam of a specific beam class may attempt new beam process capture using beams of a higher or lower class.

[0126] UE402 may indicate to the network a request to add a beam process. Such an indication may include the reason for adding the beam process, an existing beam process to be replaced with the new beam process, or beam process usage restrictions. For example, the usage restrictions may include a communication link direction (such as UL, DL, SL, or a combination). In another example, the usage restrictions may include a transmission type (e.g., mMTC, URLLC, eMBB). In yet another example, the usage restrictions may include beam process parameters (e.g., SOM or numerology). In a further example, the usage restrictions may include the purpose of the beam process (e.g., for data transmission or for mobility measurements). In another example, the usage restrictions may list a subset of time resources expected to be used by the beam process.

[0127] UE402 may request to add or remove a beam process. Such a request may be made to the serving TRP / cell / eNB using dedicated resources. For example, the UE may use the beam process itself to send a request for removal of the beam process. In another example, the UE may request to add a beam process to the TRP and indicate the TRP ID (or any parameter obtained on the MRS) to the source TRP.

[0128] In an exemplary embodiment, UE402 may request to add a new beam process by using a procedure such as RA. UE402 may transmit a random access preamble using a beam to be used for the new beam process. This transmission may trigger an operation where only the TRP / cell / eNB beam is matched to the UE's beam for that beam process. In another example, UE402 may use a beam from an appropriate beam class of the specified RA. Subsequent procedures may enforce the optimization of both the UE's beam and the TRP / cell / eNB beam.

[0129] In another exemplary embodiment, UE 402 may have dedicated beams and / or beam processes to send requests for beam addition (e.g., using RA). Such dedicated beams and / or beam processes may be configured by the network. In another example, UE 402 may be configured with one or more beam processes for a particular use. Further, one or more such beam processes may be tagged to be used for additional beam process requests.

[0130] In some embodiments, UE 402 receives a beam process transmission multiplexing configuration for simultaneous beam processes.

[0131] In some embodiments, UE 402 may be configured to transmit simultaneously to different TRPs when the associated beam processes may have equivalent signal configurations including subcarrier spacing, symbol length, resource block size, cyclic prefix length, etc. In such embodiments, uplink beam transmissions to different TRPs may use the same frequency resources and may be spatially multiplexed, and the uplink beams are directed to the TRPs in such a way that the separation between beam patterns can be higher than a preconfigured threshold. A potential benefit of this approach may be the reuse of frequency resources and the resulting high uplink spectral efficiency.

[0132] In another embodiment, uplink beam transmissions may be multiplexed using dedicated frequency resources for each beam process associated with a different TRP. The resulting uplink beam patterns may partially overlap, resulting in reduced beamforming complexity.

[0133] Alternatively, UE 402 may use different orthogonal spreading codes for beam processes associated with different TRPs, and the code configurations may be received for each TRP.

[0134] Beam Selection Procedure The following sections describe methods and exemplary embodiments for beam selection. Exemplary embodiments may be described from the perspective of a single beam or a single beam process, but it should be understood that in practice the procedures may be applied in parallel to multiple beam processes.

[0135] Beam class Beams can generally be characterized, for example, as described in Non-Patent Document 1. As described previously, FIGS. 3A and 3B show the difference between the beam peak direction and the beam center direction. The beam peak direction refers to the maximum point for the beam, and the beam center direction refers to the center point of the beam distribution.

[0136] FIG. 5 shows the difference between beam 506, beam group 508, and beam classes 502, 504. It also shows the difference between the lower beam class 502 and the higher beam class 504. The beam family in this example can consist of all beams of the same class.

[0137] Exemplary embodiments for maintaining a link across beam classes Different beam classes can exhibit different coverage levels. Generally, the more directive the beam, the better the coverage in a specific direction. This observation also means that there is often a trade-off between directivity and coverage. A wider beam can exhibit a smaller coverage, which can be a problem for some types of traffic or control channels. When changing to a lower beam class, the UE may lose the radio link. Similarly, when the UE changes to a higher beam class, the UE may ultimately have to transmit too much power for a given rate.

[0138] In an exemplary embodiment, the UE may be configured to scale its transmission power according to a beam class. For example, a lower beam class may use more power (for a given bit rate, transport format, or MCS, etc.) compared to other higher beam classes. This configuration may be implemented, for example, using a predefined power scaling factor associated with the beam class. This approach may lead to similar received power at the eNB and may maintain the radio link, but it also limits the data rate per beam class since power amplifiers are generally power limited.

[0139] In an exemplary embodiment, the link may be maintained by using repetition on multiple beams. For example, the UE may be configured to repeat the transmission of a given data block over multiple beams over a plurality of time instances (e.g., belonging to the same beam group). The UE may be configured to use a predefined sequence of beams (e.g., within a beam group).

[0140] Repetition over multiple beams may be triggered, for example, when the UE changes to a lower beam class. In an exemplary embodiment, this approach avoids segmentation due to coverage changes, which results from a change to a lower beam class and is only applied to HARQ retransmissions.

[0141] In an exemplary embodiment, repetition over multiple beams may be triggered and controlled by the network. For example, the UE may receive an indication (e.g., DCI) on a control channel to start repetition over multiple beams. Optionally, the indication may include the beam class and / or beam group index to be used for transmitting the data. This indication may be associated with an indication to change to a lower beam class, for example.

[0142] In another exemplary embodiment, the UE may be configured to indicate (e.g., via UCI) to the network when repetition on multiple beams is required (e.g., when the UE has data to be retransmitted on the retransmission buffer on multiple beams).

[0143] In yet another exemplary embodiment, the UE may transmit on a subset of beams at a time. More specifically, the UE may be configured to transmit repeated data on a subset of multiple beams within a single TTI. The UE may receive ACK / NACK from the network and continue to transmit the repeated data on another subset of multiple beams. The UE may repeat this process until it receives an ACK from the network or until it transmits on all relevant beams.

[0144] Determining a set of available beams for selection The UE may be configured to select a beam for transmission on a subset of its beams (also referred to as a set of available beams). The subset of beams may be configured by the network (e.g., semi-statically (such as on RRC) or dynamically (such as via DCI type signaling)).

[0145] In an exemplary embodiment, the UE may be configured to determine a set of available beams based on beam classes. For example, the UE may determine that the set of available beams corresponds to a beam group associated with beams of a lower beam class linked to, for example, a beam process. In another option, the UE may determine a beam group based on, for example, the direction of arrival for a downlink reference signal associated with a beam process. For example, the set of available beams may be a beam group of a lower beam class having the beam direction closest as the direction of arrival (DoA) of the downlink reference signal.

[0146] In an exemplary embodiment, the UE may be configured with a set of available beams that are restricted by angle limitations. For example, these limitations may be applicable to the direction of the beams. The UE may be configured to limit the beam direction for the set of available beams to a specific angular distance from the DoA for the downlink reference signal associated with the beam process.

[0147] In another example, the UE may be configured to use any beam that is restricted to be within a certain beam space. The beam space may use angle limitations to set its boundaries. For example, the UE may determine that the set of available beams consists of any beam whose beam direction is within a set of values (e.g., associated with the DoA of the downlink reference signal of the associated beam process). The UE may further apply one or more conditions to beams having any shape. In an exemplary embodiment, the UE may limit a specific amount of beam energy (e.g., 90%) to a specific angular limitation. For example, the angular limitation may be determined based on an angle difference value (ΔDoA) configured by the network that is applied to the DoA of the downlink reference signal associated with the beam process.

[0148] The UE may be configured to determine which beam class to use for its uplink transmission. The network may configure the UE to use a specific beam class, such as via DCI or via semi-static signaling (such as RRC). In another exemplary embodiment, the UE may be configured to separately determine the most appropriate beam class based on factors stored by the UE.

[0149] The UE may determine the beam class to be used for transmission based on the transmitted data. For example, the UE may be configured to use one or more beam classes for control information (such as RRC signaling or RACH access) and one or more beam classes for data transfer. In another example, the UE may be configured to use a beam class for each logical channel. The UE may use the beam class associated with the transmitted logical channel. The UE may also store rules for determining which beam class to use when multiple logical channels with different associated beam classes are multiplexed together. For example, the rule may be to use the lowest beam class among the beam classes associated with the logical channels multiplexed in its transport block.

[0150] In another example, the UE may be configured to use a specific beam class for different traffic types, such as mMTC, eMBB URLLC, or QoS. For example, the UE may be configured directly with beam classes in the QoS configuration, or the UE may be configured with an association table or filter that links QoS to specific beam classes.

[0151] The UE may be configured to indicate to the network which beam class it uses in its UL transmission. This information may be carried in the UCI, or in a special MAC header or other type of signaling. The UE may indicate to the network only when it changes the beam class or when the UE makes a decision on which beam class to use.

[0152] In another exemplary embodiment, the UE may be explicitly configured by the eNB to use a specific beam class. For example, the eNB UL grant may indicate a specific beam class to be used for uplink beamforming. In such a case, the beam class may be valid only for the duration of the grant. Alternatively, the UE may be semi-statically configured with the beam class to be used.

[0153] The UE and the network can maintain synchronization of the beam class state such that both the UE and the network are always aware of which beam class is being used. Several techniques can achieve this synchronization. In one technique, the opposing entity acknowledges all beam class changes (e.g., at the MAC or RRC protocol level). In an example of this technique, the UE indicates a beam class change via a special MAC control element and can apply the change only when it receives a reliable acknowledgment from the network (e.g., from a DL MAC control element).

[0154] The UE can maintain the beam class configuration until it changes the configuration or receives a message from the network to change it. The UE can be configured to change the beam class immediately and acknowledge the network message in its next transmission (e.g., in the MAC header or other control message), or the UE can acknowledge the network message and apply the change only after receiving an acknowledgment from the network (e.g., HARQ-ACK or other higher layer acknowledgment).

[0155] The UE can actually be composed of multiple beam processes. To utilize the channel spatial diversity or spatial multiplexing ability, the network can control the transmission direction for the associated downlink reference signal, and each beam process should lead to an independent propagation path. The UE avoids transmitting data on the same propagation path (beam) for different beam processes. When determining the set of available beams, the UE can be configured to exclude one or more beams related to other ongoing or active beam processes.

[0156] The UE may be configured to determine a set of beams related to a given beam process. The UE may create a list that includes the same beam as the selected beam in (another) beam process, beams in the beam group associated with the beam process, beams within the range of beam indices for the selected beam of (another) beam process, and beams within the angular distance of the selected beam of (another) beam process. The beams in the beam group associated with the beam process include beam groups of lower beam classes associated with the selected beam of the beam process. The range of beam indices may be configured a priori by the network or via a specification. For example, the range of beams may include all beams within ±N beam indices from the selected beam.

[0157] The angular distance may be configured a priori by the network. The related beams include beams (for the same beam class) whose beam centers are within a specific maximum angular distance from the beam center of the selected beam for (another) beam process. The maximum angular distance (e.g., in degrees or radians) may be configured by the network. For example, the related beams may be defined as beams whose beam centers are within ±Δ max of the beam center of the selected beam of (another) beam process. Alternatively, the set of related beams may be defined based on both the 3dB (or other value) lobe of the beam and the beam center of the selected beam of (another) beam process. Beams whose 3dB lobes enter within ±Δ max of the beam center of the selected beam of (another) beam process may be considered related.

[0158] When composed of two or more beam processes, the UE may be configured for each beam process to select beams outside the set of related beams (considering all external beam processes). The UE may be configured to select the best available (and non-related) beams.

[0159] In an exemplary embodiment, when the UE determines that the best beam to be selected falls within the set of beams related to it and / or when the UE determines that the set of available beams is empty, the UE may be configured to stop transmission on the associated beam process, or the UE may notify the network (e.g., via control signaling) by transmitting on a different beam process having available beams. The UE may further indicate the number of beam processes or identification information, and the related beam or beam process.

[0160] Selection procedure The UE may determine the beam class, beam group, and beam to be used for uplink transmission based on the measurement of one or more downlink beams by using at least one of the following exemplary embodiments, i.e., quality / space / energy metric, periodicity, downlink control / data / reference signal transmission, single-stage measurement, or multi-stage measurement.

[0161] Beam quality metric measurements may be based on SNR, E b / N0, RSSQ, and CQI. Beam space information measurements may be based on the angle of arrival (AoA). Beam energy metric measurements may be based on RSSI and broadband AGC settings.

[0162] Beam periodicity measurements may be periodic or aperiodic, where the beam measurements may be scheduled by the network. During active downlink data transmission, a measurement field or gap may be included during measurement scheduling. Beam measurements may be configured in system broadcast information or upper layer dedicated signaling, including measurement periodicity. The UE may be triggered for periodic measurements within a predefined period.

[0163] In downlink control / data / reference signal transmission, beam measurement can be performed on a downlink beam associated with downlink control information, downlink data transmission, scheduled downlink reference signal transmission (e.g., beam selection reference signal), or periodic downlink reference signal transmission (e.g., beam selection reference signal).

[0164] Single-stage beam measurement can be performed using one or more beams from a beam group of one beam class preconfigured and selected by the UE for beam measurement, a target measurement beam class based on the one or more beams, the uplink transmission service type for which the measurement is to be used, or a beam class, or a sweep of applied beams in a continuous or arbitrary manner to cover the beam space in which the target downlink beam can be received.

[0165] Multi-stage measurement can be performed using one or more beams from a beam group of a first beam class to obtain a first measurement result in a manner similar to single-stage measurement, one or more beams of a second beam class having one or more different characteristics compared to the first beam class (such as a reduced beam width or adjusted center direction) for use in the next measurement and based on the first measurement result, a continuation of the first measurement process, or a multi-stage sweep where each stage can consist of a selected beam and the UE can gradually reduce the beam space while determining the spatial information and quality metrics of the measured downlink beam.

[0166] Based on the measurement results, the UE can select at least one beam from a beam group of a beam class for uplink transmission using a linkage between the beam class used for measurement and the associated beam class for uplink transmission, a calculation based on direction reciprocity, or a sweep of a plurality of selected uplink beams over the beam space based on the measurement.

[0167] A beam class linkage for measurement and for transmission may be included during the beam process. In some exemplary embodiments, the UE may select an uplink beam of the same beam class as that used for measurement. For example, the selected uplink beam may have a similar beam width, beam center direction, or beam space.

[0168] The direction reversibility calculation may be, for example, between the AoA and the AoD. In an exemplary embodiment, the UE may select an uplink beam from a beam class using beam center direction calculation based on the estimated AoA information of the downlink measurement and the beam width.

[0169] In the sweep of multiple selected uplink beams, the UE may select a group of beams of a beam class different from that used for measurement and a sweep of the beams on the measured downlink beam space.

[0170] The UE may set the beam-specific power for the selected beam based on measurement, the expected power offset associated with the measured beam class signaled by the network, the uplink channel type and service targeted for uplink transmission, the priority and maximum limit of the selected beam class, the maximum transmission power of each antenna element, the maximum EIRP of the UE uplink transmission, and other configurations including the EIRP adjustment instruction from the network that the UE may use to adjust the beam class or to maintain the beam class while adjusting the power for each element.

[0171] The UE may determine one or more of a beam class, a beam group, and a beam to be used for uplink transmission based on the feedback received for the uplink beam sounding procedure. The sounding procedure may be scheduled and configured by the network. The configuration may include an antenna port configuration, a beam class indicator, the number of sounding beams, a time resource allocation, a frequency resource allocation, a reference signal configuration of the sounding beam, and an EIRP of the sounding beam. The antenna port configuration indicates which port should be used. The beam class indicator indicates which beam class can be used for sounding for each antenna port. The number of sounding beams indicates how many sounding beams should be transmitted for each antenna port. An exemplary embodiment for time resource allocation may allocate a field of a plurality of symbols in the control field of one subframe or a gap of a plurality of symbols in the data section of one subframe. In another exemplary embodiment, a special subframe may be configured for the sounding procedure. An exemplary frequency resource allocation may be a group of subcarriers or resource blocks. An exemplary reference signal configuration of the sounding beam may be a basic Zadoff-Chu (ZC) sequence for each antenna port or for the UE. The EIRP of the sounding beam may include the beamforming gain and power for each antenna element.

[0172] The UE may arbitrarily select sounding beams according to the configured number of sounding beams from the beam group for the indicated beam class. For each sounding beam transmitted from the same antenna port, the UE may apply the same ZC basic sequence. The ZC basic sequence may be configured for each antenna port. The sounding beams for each antenna port may be transmitted one by one. Different antenna ports may have sounding beams using different ZC basic sequences to maintain orthogonality.

[0173] In another exemplary embodiment, the ZC basic sequence may be configured for each UE, where each antenna port may be assigned by the UE by means of a cyclic shift based on downlink beam measurements. In such a case, the sounding beam reference signal may be orthogonal among the antenna ports of the UE.

[0174] Uplink beam sounding may be triggered by a preconfigured event, such as the UE entering fallback or the quality of the downlink data beam falling below a preconfigured threshold.

[0175] The UE may execute a multi-stage uplink beam sounding procedure for several scenarios as described in the following exemplary embodiments. In an exemplary embodiment, the UE may be configured with a multi-stage sounding procedure request with a sequence of beam classes to be used for each stage of the sounding procedure. The configuration may include time resources and reference signal configurations for each beam class. In another exemplary embodiment, the UE may autonomously determine a sequence of beam classes and use a predefined set of reference signal sequences reserved for autonomous uplink beam sounding so that the network can detect the sounding beams. The UE may receive network feedback in the control information received in the downlink beam. Such feedback control information may have a fixed timing relationship with the sounding beam transmission timing, and the UE may monitor the feedback based on the timing relationship. In another exemplary embodiment, the feedback may be included in the scheduled downlink data. The feedback content may be a bitmap indicating which sounding beams can be received above a threshold and can be used for further sounding. The feedback may also include the sounding beam metric information and the reference signal index of those sounding beams. The UE may determine which beam class to use based on the received feedback. In an exemplary embodiment, the UE may use a beam class according to the configured beam class sequence. The UE transmits the next set of sounding beams in the beam space of the sounding beams before the feedback exceeds the threshold. The network may configure a new resource allocation for each stage or apply the same resources until the multi-stage sounding procedure is completed.

[0176] The UE may select an uplink beam based on the best sounding beam indicated during the feedback of the uplink beam sounding procedure. In another exemplary embodiment, the network may schedule one or more beams of a beam class according to uplink beam sounding. The UE may receive the uplink beam and beam class configuration in the downlink control information.

[0177] The network may schedule beams of different beam classes for each antenna port according to the uplink and service type of the uplink transmission. For example, the network may schedule a beam class for uplink control information transmission at a certain antenna port and another beam class for data transmission at another antenna port. The scheduling may be performed using one or more fields in the DCI for indicating the beam and beam class.

[0178] The transmission beams may be multiplexed in the time domain and frequency domain. For example, in one subframe, the UE may use a beam class in the uplink control field and a different beam class in the uplink data field. In another exemplary embodiment, the UE may transmit simultaneous beams of different beam classes, where each beam may apply to different groups of subcarriers or resource blocks.

[0179] The power of each beam class may be determined based on the feedback of the uplink beam sounding procedure. Each beam class may have an independent maximum EIRP and maximum transmission power for each antenna element. The power control for each beam may be limited by the maximum EIRP of the beam class.

[0180] For specific uplink channel transmissions, the network may configure a power control command specific to a beam class. The UE may adjust the transmission power for each element. In another exemplary embodiment, the network may configure different beam classes for uplink transmission, and the UE may adjust the transmission power for each element according to the new beam class. For example, the reconfigured beam class may have a wider beam width, and the UE may increase the transmission power to maintain the total EIRP.

[0181] The network may schedule uplink beams and beam classes to maximize uplink transmission capacity and avoid uplink transmission interference among co-scheduled UEs. When maximizing uplink transmission capacity, the network may use an uplink beam based on the beam class with the best sounding result with a very narrow beam width. The procedure may increase the spectral efficiency for a single user. When avoiding uplink transmission interference, the network may evaluate, for example, the uplink beam sounding results from all UEs that may transmit to the same TRP, and select the beam and beam class for each UE such that the transmission beam of one UE may have a null towards the main lobe direction of the transmission beams of co-scheduled UEs. This technique may enable co-scheduled UEs to use the same time resources, frequency resources, and code resources and increase the average spectral efficiency per TRP.

[0182] The UE may trigger an uplink fallback procedure under multiple scenarios, such as when receiving ramp-up TPC bits while receiving a downlink NACK for data beam transmission, when receiving a predefined number of NACK messages for a specific uplink beam used for data transmission when the maximum EIRP of the beam class has been reached, or when entering a beam mismatch state based on a preconfigured criterion.

[0183] The UE fallback procedure may include the following actions: aborting the use of the currently selected beam and beam class; selecting another beam class to continue uplink data transmission; setting the transmission power for each element according to the selected beam class; and starting the uplink sounding procedure using pre-defined resources.

[0184] When selecting another beam class to continue uplink data transmission, the new beam class may be the lowest beam class or a beam class with a pre-defined offset lower than the beam class used. Also, for example, the new beam class may have a wider beam width or a different beam center direction.

[0185] When setting the transmission power for each element according to the selected beam class, the UE may increase the transmission power to compensate for the reduced beamforming gain when using a lower beam class, for example. When the maximum power per element is reached, the UE may apply beam sweeping to provide cumulative gain.

[0186] Starting the uplink beam sounding procedure using pre-defined resources may include reserving a reference signal sequence for the fallback trigger of uplink beam sounding and allocating pre-configured time and frequency resources for the fallback trigger of uplink beam sounding. For example, there may be symbol and subframe locations calculated based on UE and TRP identification information that can be used for sounding.

[0187] In another exemplary embodiment, the UE may send a fallback indicator to the network using uplink beams of different beam classes (such as a beam used for uplink control information transmission from another antenna port). The uplink beam for control transmission may experience uncorrected interference or channel events and may be used. The UE may receive an uplink sounding beam request and configuration for starting uplink sounding. The resource configuration may not be reserved and may be configured dynamically. In another exemplary embodiment, the UE may receive a first beam process request.

[0188] Maximum Power Reduction (MPR) by SAR The UE may receive human body monitoring information including the detected distance and angular direction from a motion sensor. The UE may collate the human body detection data to determine which uplink beam may be within a predefined proximity of the detected human body. The UE may autonomously apply, for example, a maximum power reduction (MPR) of a predefined value to each identified uplink beam. Note that the maximum power may indicate the total effective isotropic radiation power (EIRP) emitted by the uplink beam pattern.

[0189] The UE may perform maximum power reduction using one or more of a variety of different techniques. In one technique, the UE backs off the maximum transmit power for each of all antenna elements associated with the identified uplink beam. In another technique, the number of antenna elements used for the identified uplink beam is reduced. Note that this can be implemented in a UE having the ability to scale the number of antenna elements used for analog beamforming. Also, the reduction of antenna elements may cause a change in the beam class. In another technique, the UE may switch to a different set of antennas that may be located on the opposite side to keep the radiation pattern at an optimal power (this may be the case in a band above 6 GHz if it has such an ability).

[0190] The UE may autonomously determine how to reduce the total EIRP. In some embodiments, the network may pre - configure a UE with antenna element scaling capabilities with information on how MPR may be performed.

[0191] The UE may be configured with an indication of which method should be applied for reducing the maximum EIRP, e.g., whether the reduction should be applied by reducing the maximum power or by reducing the number of antenna elements. Such configuration may be provided by upper layer signaling.

[0192] Beam process parameter update The UE may further identify which active beam process can be associated with the uplink beam having MPR caused by SAR and update the relevant parameters of the identified beam process. Beam process specific parameters may include the updated maximum total EIRP, the maximum configured power, the resulting power headroom, and the beam class. A beam class change may cause the UE to update the estimated value of the interference received at the TRP within the uplink beam.

[0193] PHR Triggered by MPR Caused by SAR In each identified beam process, the UE may be triggered to send a report, such as a power headroom report (PHR) or an EIRP report, indicating new parameters applicable to the adjusted maximum power for the beam process where at least the maximum EIRP and / or P cmax has changed. In the report, the UE may specify the MPR cause related to SAR and the identification information of the affected beam process. The report may be sent as control information in the physical layer. In the latter case, the control information may be associated with the same or different beam processes. Since MPR caused by SAR can be more frequent in beamformed operations of HF NR, the potential benefits of using UCI transmission can be low latency and overhead. In another embodiment, the UE may send the report using MAC signaling or RRC signaling.

[0194] Maximum Gain Offset Report Triggered by MPR Caused by SAR The UE may be configured by reducing the number of antenna elements or apply MPR autonomously, thereby reducing the beamforming gain of the beam process. The UE may keep the power per element unchanged. The UE may be triggered to report a maximum gain offset report indicating the offset between the applied beamforming gain of the beam process and the configured maximum gain. The eNB may trigger uplink beam reselection for the beam process. In another solution, the eNB may reduce the transport format, such as the coding rate and modulation scheme, for the beam process with reduced beamforming gain, to maintain the radio link. This may improve the robustness of the beam process during MPR.

[0195] Beam Process Reselection Triggered by SAR The UE may reselect an active beam process where the UE has updated parameters and PHR as a result of MPR caused by SAR. Uplink beam reselection may be performed according to a set of preconfigured rules. The UE may apply the rules according to the beam process uplink transmission type, updated uplink transmission, uplink channel type, and uplink transmission mode and scheme. In some exemplary embodiments, the UE may change the beam process association by establishing a new beam process or switching to another active beam process with a new set of downlink and uplink beams.

[0196] Uplink Beam Reselection of Active Beam Processes Affected by SAR UE 602 may reselect the uplink beam of the active beam processed as a result of MPR caused by SAR. As shown in the exemplary embodiment 600 shown in FIG. 6, UE 602 may reselect beam B1(604) to replace beam B2(606) for the active beam process due to the proximity of beam B2(606) to the human body 608. UE 602 may take into account the reduced maximum EIRP and MRP in the open-loop selection of the uplink beam. For example, UE 602 may apply a negative EIRP reduction to the uplink beam that may correspond contrarily to the active downlink beam associated with the beam process. As a result, UE 602 may not select an uplink beam that is contrary to the active downlink beam associated with the beam process. UE 602 may select another uplink beam based on the adjusted maximum EIRP of the available uplink beams, including those affected by SAR, rather than based on contrariety. UE 602 may also fallback to a preselected and maintained default uplink beam for the beam process.

[0197] UE602 can re-estimate the path loss of the reselected uplink beam. The "paired" downlink beam of each beam process can be a downlink data beam, or a reference beam, or another type of downlink beam. The pairing may not be a one-to-one mapping, and the path loss estimate can use the transmission power specified in the system broadcast information. The uplink power of the reselected uplink beam can be based on the re-estimated path loss. In another solution, the uplink power can be implicitly indicated using a periodic synchronization signal sequence.

[0198] UE602 can re-establish the transmission timing of the reselected uplink beam. Further, beam reselection can trigger uplink beam sweeping using updated power, and UE602 can initiate an uplink beam pairing and beam reacquisition procedure. Beam reacquisition may not be based on the associated downlink beam using reciprocity. UE602 can update the re-paired downlink beam and uplink beam for the associated beam process. UE602 can send beam process update information to the eNB using the reselected uplink beam transmission.

[0199] Beam Process Procedure Triggered by Rotation or Obstacle Detection Data: Uplink Beam Reselection and Repairing UE602 can periodically estimate the orientation change of the antenna array and update the local coordinate system that can be a reference for the beam direction. The UE602 estimation can be based on the rotation and obstacle detection data provided by the motion sensor.

[0200] UE602 can autonomously fallback on one or more transmission properties, including transmission mode, transmission method, beamforming property, etc. For example, UE602 can apply a preconfigured wide or omnidirectional beamwidth. The increased beamwidth may enable some of the uplink transmission energy to reach the eNB around the detected obstacle through diffraction. Also, the wide beam pattern may reduce the impact of UE602 rotation. UE602 can further use a preconfigured uplink control and data channel transport format including block size and modulation and coding scheme (MCS). With the widening of the beamwidth, the total EIRP can be reduced, and UE602 can use a smaller block size and a conservative MCS to maintain uplink quality.

[0201] In another embodiment, UE602 can start uplink sounding transmission using uplink beam sweeping that uses a predefined uplink sounding configuration. The configuration may include a reference signal type and resource allocation. This may enable UE602 to identify an uplink beam that may not be affected by rotation or detected obstacles. UE602 can reselect the uplink beam based on the result of the started uplink sounding procedure. UE602 can transmit a measurement or uplink beam re-pairing request following the sounding procedure.

[0202] UE602 with multiple simultaneous active beam processes can start uplink beam reselection and re-pairing for each beam process when rotation and obstacle detection occur. UE602 can apply an orthogonal uplink resource configuration for uplink fallback and re-pairing transmission in either the frequency domain or the time domain. In another solution, UE602 can have two spatially separated simultaneous beam processes, in which case UE602 can use the same frequency resources and time resources for beam process transmission.

[0203] Downlink RLF avoidance Obstacles can be the cause of UE downlink RLF, and UE 602 can use the rotation vector and rate estimates to predict the conditions. UE 602 can apply rules or criteria to determine whether the rotational movement or detected obstacles will cause RLF in the near time frame. The rules can include the rate of SINR degradation, received energy reduction, and BLER increase. UE 602 can send a preconfigured sequence to trigger the downlink beam reselection procedure using a control channel with a predefined transport format. In another solution, UE 602 can apply autonomous transmission OFF based on the detected data, in which case UE 602 can switch all uplink transmission beams off and interrupt the active beam process. This prevents UE 602 from wasting energy when operating in extremely unfavorable channel conditions, such as with extremely fast rotational movements, extremely fast or large obstacles moving extremely rapidly towards UE 602. Beamformed transmissions may not be viable under these conditions.

[0204] Downlink beam probing and adjustment UE 602 can request beam-specific reference signal transmission for downlink beam adjustment. UE 602 can monitor the quality metric of the downlink beam associated with the active beam process during active data reception. The quality metric can include energy detection within the active beam pair on the allocated frequency resource, DMRS symbol energy over noise, and the magnitude of the detected rotation. UE 602 can send a request for BSRS transmission when the monitored quality metric exceeds a predefined threshold. The beam-specific reference signal resource configuration can be preconfigured, and UE 602 can use received beam sweeping to start pairing of new beams based on the detected BRS. UE 602 can determine and update the received beam associated with the active beam process.

[0205] The UE 602 can be triggered periodically or by a predefined event for each active beam process to probe the received beam. The UE 602 performs receive beamforming probing for each TTI or for each number of TTIs averaged over a predefined time period during active downlink data transmission. The UE can use the CP or GP attached to each symbol or the fields specific to the subframe structure where there is no useful data transmission, especially for a single receive beam UE. The time period can also be scheduled as a special subframe or a block of one or more symbols. The UE 602 can also perform probing on the UW on the UE waveform without CP or GP. For a multi-receive beam UE, the time period may overlap with data transmission, such as data and DMRS symbols.

[0206] Receive beamforming probing can include full receive beam sweeping, receive beams, such as a predefined group of adjacent receive beams (GOB) or + / -x degrees (continuous BF), and / or cycling through the previously used best receive beam. The UE 602 can measure the detected energy for each adjusted receive beam and find the best receive beam according to a predefined criterion.

[0207] The probing period can be shortened to reduce measurement overhead. Analog measurements may not require reference signal transmission for a certain waveform and may require a short probing time. The UE 602 can update the active beam process using receive beam selection as a result of probing.

[0208] UE602 can also adjust the received beam associated with the active beam process based on the results of UE602 rotation detection and received beamforming measurements. UE602 can autonomously track the received beam using continuous analog beamforming capabilities. UE602 can perform received beamforming adjustments during a predefined time period, similar to the received beam probing configuration. UE602 can determine the adjustment based on the measured rotation vector, detected active beam pair energy variation (wideband AGC value), received channel SINR using the active beam pair, channel quality measured in received beamforming measurements, etc. UE602 can apply the updated received beam to continue active data reception without knowledge of the TRP. UE602 can update the active beam process with received beam adjustments and maintain the mapping of beam pairs between one or more received beams and one transmitted beam.

[0209] The UE can determine the "best beam" based on measuring energy on a set of resources using a set of candidate beams. In some embodiments, the set of resources can be a specific time period or sequence of symbols within the downlink data transmission for UE602. The presence of the set of resources can be indicated in the downlink control information applicable to the transmission or can be configured by a higher layer. In some solutions, the information mapped on the set of resources can be encoded and / or modulated using different parameters than those of the remaining resources of the transmission to increase the probability of successful decoding even when a sub-optimal beam is used. The applicable parameters (e.g., code rate, modulation, or modulation and coding scheme index) can be indicated by the downlink control information or configured by a higher layer or can be implicitly determined from the parameters used in the remaining resources, such as a pre-determined or pre-configured offset to the MCS index applied for the rest of the transmission.

[0210] Network architecture Systems and methods related to forming multicast groups can be used with the wireless communication systems described with respect to FIGS. 7A-7F. First, these wireless systems are described. FIG. 7A is a diagram of an exemplary communication system 700 in which one or more of the disclosed embodiments may be implemented. The communication system 700 can be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to a plurality of wireless users. The communication system 700 can enable a plurality of wireless users to access such content through sharing of system resources, including wireless bandwidth.

[0211] As shown in FIG. 7A, the communication system 700 can include WTRUs 102a, 102b, 102c, and / or 102d (which may generally or collectively be referred to as WTRU 102), RANs 103 / 104 / 105, core networks 106 / 107 / 109, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d can be any type of device configured to operate and / or communicate in a wireless environment. For example, the WTRUs 102a, 102b, 102c, 102d can be configured to transmit and / or receive wireless signals and can include user equipment (UE), mobile stations, fixed or mobile subscriber units, pagers, cellular telephones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, consumer electronics, etc.

[0212] The communication system 700 may also include base station 114a and base station 114b. Each of base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, 102d to enable access to one or more communication networks such as core network 106 / 107 / 109, Internet 110, and / or network 112. For example, base stations 114a, 114b may be a base transceiver station (BTS), Node B, eNode B, home Node B, home eNode B, site controller, access point (AP), wireless router, etc. Although base stations 114a, 114b are each shown as a single element, it will be understood that base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0213] Base station 114a may be part of RANs 103 / 104 / 105, which may also include other base stations and / or network elements (not shown) such as a base station controller (BSC), radio network controller (RNC), relay node, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals within a particular geographical area, sometimes referred to as a cell (not shown). A cell may be further divided into sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers (one for each sector of the cell). In another embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and utilize multiple transceivers for each sector of the cell.

[0214] The base stations 114a, 114b can communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over the air interfaces 115 / 116 / 117, and the air interfaces 115 / 116 / 117 can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interfaces 115 / 116 / 117 can be established using any suitable radio access technology (RAT).

[0215] More specifically, as described above, the communication system 700 can be a multi-connection system and can employ one or more channel access methods such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base stations 114a in the RANs 103 / 104 / 105, and the WTRUs 102a, 102b, 102c can implement a radio technology such as Universal Mobile Telecommunications System (UMTS) terrestrial radio access (UTRA) that can establish the air interfaces 115 / 116 / 117 using Wideband CDMA (WCDMA (R)). WCDMA can include communication protocols such as High-Speed Packet Access (HSPA) and / or evolved HSPA (HSPA+). HSPA can include High-Speed Downlink Packet Access (HSDPA) and / or High-Speed Uplink Packet Access (HSUPA).

[0216] In another embodiment, the base stations 114a and the WTRUs 102a, 102b, 102c can implement a radio technology such as evolved UMTS terrestrial radio access (E-UTRA) that can establish the air interfaces 115 / 116 / 117 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A).

[0217] In other embodiments, base station 114a and WTRUs 102a, 102b, 102c may implement wireless technologies such as IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX (registered trademark))), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, IS-2000 (Interim Standard 2000), IS-95 (Interim Standard 95), IS-856 (Interim Standard 856), GSM (registered trademark) (Global System for Mobile Communications), GSM Enhanced Data Rate for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0218] Base station 114b in FIG. 7A can be, for example, a wireless router, a home node B, a home e-node B, or an access point, and can utilize any suitable RAT to enable wireless connectivity in a localized area such as an office, a home, a vehicle, a campus, etc. In one embodiment, base station 114b and WTRUs 102c, 102d may implement a wireless technology such as IEEE 802.11 to establish a Wireless Local Area Network (WLAN). In another embodiment, base station 114b and WTRUs 102c, 102d may implement a wireless technology such as IEEE 802.15 to establish a Wireless Personal Area Network (WPAN). In yet another embodiment, base station 114b and WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a pico cell or a femto cell. As shown in FIG. 7A, base station 114b may have a direct connection to the Internet 110. Thus, base station 114b may not be required to access the Internet 110 via the core network 106 / 107 / 109.

[0219] RAN 103 / 104 / 105 may communicate with core networks 106 / 107 / 109, which can be any type of network configured to provide voice, data, applications, and / or VoIP services to one or more of WTRUs 102a, 102b, 102c, 102d. For example, core networks 106 / 107 / 109 may provide call control, billing services, mobile location information services, prepaid calling, Internet connectivity, video distribution, etc., and / or may perform high-level security functions such as user authentication. Although not shown in Figure 7A, it should be understood that RAN 103 / 104 / 105 and / or core networks 106 / 107 / 109 may communicate directly or indirectly with other RANs that employ the same or a different RAT as RAN 103 / 104 / 105. For example, in addition to being connected to a RAN 103 / 104 / 105 that may utilize E-UTRA radio technology, core networks 106 / 107 / 109 may also communicate with another RAN (not shown) that employs GSM radio technology.

[0220] The core networks 106 / 107 / 109 can also act as gateways for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 can include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 can include a global system of interconnected computer networks and devices that use common communication protocols such as TCP, User Datagram Protocol (UDP), and IP in the Transmission Control Protocol (TCP) / IP Internet protocol suite. The network 112 can include wired and / or wireless communication networks that are owned and / or operated by other service providers. For example, the network 112 can include another core network connected to one or more RANs that may employ the same or a different radio access technology (RAT) as the RANs 103 / 104 / 105.

[0221] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 700 can include multimode capabilities, i.e., the WTRUs 102a, 102b, 102c, 102d can include multiple transceivers for communicating with different wireless networks over different wireless links. For example, the WTRU 102c shown in FIG. 7A can be configured to communicate with a base station 114a that may employ a cellular-based radio technology and can be configured to communicate with a base station 114b that may employ IEEE 802 radio technology.

[0222] Figure 7B is a system diagram of RAN 103 and core network 106 according to an embodiment. As described above, RAN 103 may employ UTRA radio technology to communicate with WTRUs 102a, 102b, 102c over air interface 115. RAN 103 may also communicate with core network 106. As shown in Figure 7B, RAN 103 may include Node Bs 140a, 140b, 140c, which may each include one or more transceivers for communicating with WTRUs 102a, 102b, 102c over air interface 115. Node Bs 140a, 140b, 140c may each be associated with a particular cell (not shown) within RAN 103. RAN 103 may also include RNCs 142a, 142b. It will be appreciated that RAN 103 may include any number of Node Bs and RNCs while remaining in accordance with the embodiment.

[0223] As shown in Figure 7B, Node Bs 140a, 140b may communicate with RNC 142a. Further, Node B 140c may communicate with RNC 142b. Node Bs 140a, 140b, 140c may communicate with their respective RNCs 142a, 142b via the Iub interface. RNCs 142a, 142b may communicate with each other via the Iur interface. Each of RNCs 142a, 142b may be configured to control their respective connected Node Bs 140a, 140b, 140c. Further, each of RNCs 142a, 142b may be configured to perform or support other functionality such as outer loop power control, load control, admission control, packet scheduling, handover control, macro diversity, security functions, data encryption, etc.

[0224] The core network 106 shown in FIG. 7B may include a media gateway (MGW) 144, a mobile switching center (MSC) 146, a serving GPRS support node (SGSN) 148, and / or a gateway GPRS support node (GGSN) 150. Although each of the above elements is shown as part of the core network 106, it will be understood that any one of these elements may be owned and / or operated by an entity other than the core network operator.

[0225] The RNC 142a in the RAN 103 may be connected to the MSC 146 in the core network 106 via the IuCS interface. The MSC 146 may be connected to the MGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network such as the PSTN 108 to enable communication between the WTRUs 102a, 102b, 102c and legacy landline communication devices.

[0226] The RNC 142a in the RAN 103 may also be connected to the SGSN 148 in the core network 106 via the IuPS interface. The SGSN 148 may be connected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide the WTRUs 102a, 102b, 102c with access to a packet-switched network such as the Internet 110 to enable communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0227] As described above, the core network 106 may also be connected to a network 112 that may include other wired and / or wireless networks owned and / or operated by other service providers.

[0228] Figure 7C is a system diagram of RAN 104 and core network 107 according to an embodiment. As described above, RAN 104 may employ E-UTRA radio technology to communicate with WTRUs 102a, 102b, 102c over air interface 116. RAN 104 may also communicate with core network 107.

[0229] RAN 104 may include eNodeBs 160a, 160b, 160c, although it will be appreciated that RAN 104 may include any number of eNodeBs while remaining in accordance with the embodiment. Each of eNodeBs 160a, 160b, 160c may include one or more transceivers for communicating with WTRUs 102a, 102b, 102c over air interface 116. In one embodiment, eNodeBs 160a, 160b, 160c may implement MIMO technology. Thus, eNodeB 160a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, WTRU 102a.

[0230] Each of eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink and / or downlink, etc. As shown in Figure 7C, eNodeBs 160a, 160b, 160c may communicate with each other over the X2 interface.

[0231] The core network 107 shown in Figure 7C may include a Mobility Management Entity (MME) 162, a Serving Gateway 164, and a Packet Data Network (PDN) Gateway 166. Each of the above elements is shown as part of core network 107, although it will be appreciated that any one of these elements may be owned and / or operated by an entity other than the core network operator.

[0232] The MME 162 can be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via the S1 interface and can act as a control node. For example, the MME 162 can be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a specific serving gateway during the first attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 can also provide control plane functions for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies such as GSM or WCDMA.

[0233] The serving gateway 164 can be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via the S1 interface. The serving gateway 164 can generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The serving gateway 164 can also perform other functions such as anchoring the user plane during handover between eNodeBs, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0234] The serving gateway 164 can also be connected to the PDN gateway 166, which can provide the WTRUs 102a, 102b, 102c access to a packet switched network such as the Internet 110 to enable communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0235] The core network 107 may enable communication with other networks. For example, the core network 107 may provide access to a circuit-switched network such as the PSTN 108 to the WTRUs 102a, 102b, 102c to enable communication between the WTRUs 102a, 102b, 102c and legacy landline communication devices. For example, the core network 107 may include, or communicate with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the core network 107 and the PSTN 108. Further, the core network 107 may provide the WTRUs 102a, 102b, 102c with access to a network 112 that may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0236] FIG. 7D is a system diagram of a RAN 105 and a core network 109, according to an embodiment. The RAN 105 may be an access service network (ASN) that employs IEEE 802.16 wireless technology to communicate with the WTRUs 102a, 102b, 102c over an air interface 117. As will be further described below, communication links between different functional entities of the WTRUs 102a, 102b, 102c, the RAN 105, and the core network 109 may be defined as reference points.

[0237] As shown in FIG. 7D, RAN 105 may include base stations 180a, 180b, 180c and an ASN gateway 182, although it will be appreciated that RAN 105 may include any number of base stations and ASN gateways while remaining in accordance with the embodiments. Base stations 180a, 180b, 180c may each be associated with a particular cell (not shown) in RAN 105 and may each include one or more transceivers for communicating with WTRUs 102a, 102b, 102c over air interface 117. In one embodiment, base stations 180a, 180b, 180c may implement MIMO technology. Thus, base station 180a, for example, may use multiple antennas to transmit wireless signals to and receive wireless signals from WTRU 102a. Base stations 180a, 180b, 180c may also provide mobility management functions such as handoff triggering, tunnel establishment, radio resource management, traffic classification, quality of service (QoS) policy enforcement, etc. ASN gateway 182 may act as a traffic aggregation point and may be responsible for paging, caching of subscriber profiles, routing to core network 109, etc.

[0238] Air interface 117 between WTRUs 102a, 102b, 102c and RAN 105 may be defined as an R1 reference point implementing the IEEE 802.16 specification. Further, each of WTRUs 102a, 102b, 102c may establish a logical interface (not shown) with core network 109. The logical interface between WTRUs 102a, 102b, 102c and core network 109 may be defined as an R2 reference point (not shown) that may be used for authentication, authorization, IP host configuration management, and / or mobility management.

[0239] The communication links between each of base stations 180a, 180b, and 180c can be defined as Release 8 reference points that include protocols to enable inter-base station WTRU handover and data transfer. The communication links between base stations 180a, 180b, 180c and the ASN gateway 182 can be defined as Release 6 reference points. The Release 6 reference points can include protocols to enable mobility management based on mobility events associated with each of WTRUs 102a, 102b, and 102c.

[0240] As shown in FIG. 7D, the RAN 105 can be connected to the core network 109. The communication link between the RAN 105 and the core network 109 can be defined as a Release 3 reference point that includes, for example, protocols to enable data transfer and mobility management capabilities. The core network 109 can include a Mobile IP Home Agent (MIP-HA) 184, an Authentication, Authorization, Accounting (AAA) server 186, and a gateway 188. Although each of the above elements is shown as part of the core network 109, it should be understood that any one of these elements can be owned and / or operated by an entity other than the core network operator.

[0241] The MIP-HA 184 may be responsible for IP address management and may enable the WTRUs 102a, 102b, 102c to roam between different ASNs and / or different core networks. The MIP-HA 184 may provide the WTRUs 102a, 102b, 102c with access to a packet switched network, such as the Internet 110, in order to enable communication between the WTRUs 102a, 102b, 102c and IP-enabled devices. The AAA server 186 may be responsible for supporting user authentication and user services. The gateway 188 may enable interworking with other networks. For example, the gateway 188 may provide the WTRUs 102a, 102b, 102c with access to a circuit switched network, such as the PSTN 108, in order to enable communication between the WTRUs 102a, 102b, 102c and legacy landline communication devices. Further, the gateway 188 may provide the WTRUs 102a, 102b, 102c with access to a network 112 that may include other wired and / or wireless networks owned and / or operated by other service providers.

[0242] Although not shown in FIG. 7D, it will be appreciated that the RAN 105 may be connected to other ASNs and the core network 109 may be connected to other core networks. The communication link between the RAN 105 and other ASNs may be defined as an R4 reference point (not shown) that may include a protocol for coordinating the mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and other ASNs. The communication link between the core network 109 and other core networks may be defined as an R5 reference point (not shown) that may include a protocol for enabling interworking between the home core network and the visited core network.

[0243] Figure 7E is a system diagram of an exemplary WTRU 102. As shown in Figure 7E, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power supply 134, a GPS chipset 136, and other peripheral devices 138. The transceiver 120 may be implemented as a component of the decoder logic 119. For example, the transceiver 120 and the decoder logic 119 may be implemented on a single LTE or LTE-A chip. The decoder logic may include a processor operable to execute instructions stored on a non-transitory computer-readable medium. Alternatively, or in addition, the decoder logic may be implemented using custom and / or programmable digital logic circuits.

[0244] It should be understood that the WTRU 102 may include a partial combination of the above elements while remaining in accordance with the embodiments. Also contemplated is that the embodiments include base stations 114a and 114b, and / or nodes that base stations 114a and 114b may represent, including but not limited to, in particular, transceiver stations (BTSs), Node Bs, site controllers, access points (APs), home Node Bs, evolved home Node Bs (eNode Bs), home evolved Node Bs (HeNBs), home evolved Node B gateways, and proxy nodes, which may include some or all of the elements shown in Figure 7E and described herein.

[0245] Processor 118 can be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, other types of integrated circuit (IC), a state machine, etc. Processor 118 can perform signal coding, data processing, power control, input / output processing, and / or other functionality that enables the WTRU 102 to operate in a wireless environment. Processor 118 can be coupled to transceiver 120, which can be coupled to transmit / receive element 122. FIG. 7E shows processor 118 and transceiver 120 as separate components, but it will be appreciated that processor 118 and transceiver 120 can be incorporated together in an electronic package or chip.

[0246] Transmit / receive element 122 can be configured to transmit signals to, or receive signals from, a base station (e.g., base station 114a) on air interface 115 / 116 / 117. For example, in one embodiment, transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In another embodiment, transmit / receive element 122 can be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In another embodiment, transmit / receive element 122 can be configured to transmit and receive both RF signals and optical signals. It will be appreciated that transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0247] Further, although transmit / receive element 122 is shown in FIG. 7E as a single element, the WTRU 102 can include any number of transmit / receive elements 122. More particularly, the WTRU 102 can employ MIMO technology. Thus, in one embodiment, the WTRU 102 can include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals on air interface 115 / 116 / 117.

[0248] The transceiver 120 may be configured to modulate a signal to be transmitted by the transceiver element 122 and demodulate a signal received by the transceiver element 122. As described above, the WTRU 102 may have multimode capabilities. Accordingly, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, UTRA and IEEE 802.11.

[0249] The processor 118 of the WTRU 102 may be coupled to and receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Further, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as, for example, on a server or a home computer (not shown).

[0250] Processor 118 may receive power from power supply 134 and may be configured to distribute and / or control power to other components in WTRU 102. Power supply 134 may be any suitable device for supplying power to WTRU 102. For example, power supply 134 may include one or more dry batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0251] Processor 118 may also be coupled to GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of WTRU 102. In addition to, or instead of, information from GPS chipset 136, WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over air interfaces 115 / 116 / 117 and / or may determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that WTRU 102 may capture location information via any suitable location determination method while remaining in accordance with the embodiments.

[0252] Processor 118 may further be coupled to other peripheral devices 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, peripheral devices 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, and the like.

[0253] FIG. 7F shows an exemplary network entity 190 that can be used within the communication system 700 of FIG. 7A. As shown in FIG. 7F, the network entity 190 includes a communication interface 192, a processor 194, and non-transitory data storage 196, all of which are communicatively linked by a bus, network, or other communication path 198.

[0254] The communication interface 192 can include one or more wired communication interfaces and / or one or more wireless communication interfaces. With regard to wired communication, the communication interface 192 can include one or more interfaces such as, for example, an Ethernet interface. With regard to wireless communication, the communication interface 192 can include components such as one or more antennas, one or more transceivers / chip sets designed and configured for one or more types of wireless (e.g., LTE) communication, and / or any other components considered suitable by those skilled in the art. Further, with regard to wireless communication, the communication interface 192 can be equipped in terms of scale and configuration to operate on the network side as opposed to the client side of wireless communication (e.g., LTE communication, Wi-Fi communication, etc.). Thus, the communication interface 192 can include suitable devices and circuitry (optionally including multiple transceivers) for servicing multiple mobile stations, UEs, or other access terminals within a coverage area.

[0255] The processor 194 can include one or more processors of any type considered suitable by those skilled in the art, and one example includes general-purpose microprocessors and dedicated DSPs.

[0256] The data storage 196 can take the form of any non-transitory computer-readable medium or a combination of such media, and some examples include, by way of just a few examples, flash memory, ROM, and RAM, such that any one or more types of non-transitory data storage considered suitable by those skilled in the art can be used. As shown in FIG. 7F, the data storage 196 includes program instructions 197 executable by the processor 194 for performing various combinations of the various network entity functions described herein.

[0257] In some embodiments, the network entity functions described herein are performed by a network entity having a structure similar to that of network entity 190 of FIG. 7F. In some embodiments, one or more of such functions are performed in combination by a set of multiple network entities, where each network entity has a structure similar to that of network entity 190 of FIG. 7F. In various different embodiments, network entity 190 is one or more of RAN 103 (one or more entities therein), RAN 104 (one or more entities therein), RAN 105 (one or more entities therein), core network 106 (one or more entities therein), core network 107 (one or more entities therein), core network 109 (one or more entities therein), base station 114a, base station 114b, Node B 140a, Node B 140b, Node B 140c, RNC 142a, RNC 142b, MGW 144, MSC 146, SGSN 148, GGSN 150, eNodeB 160a, eNodeB 160b, eNodeB 160c, MME 162, serving gateway 164, PDN gateway 166, base station 180a, base station 180b, base station 180c, ASN gateway 182, MIP-HA 184, AAA 186, and gateway 188, or at least includes them. Also, to be sure, other network entities and / or combinations of network entities may be used in various embodiments to perform the network entity functions described herein, since the above list is provided as an example and not as a limitation.

[0258] Although features and elements have been described above in specific combinations, one of ordinary skill in the art will understand that each feature or element may be used alone or in any combination with other features and elements. Further, the methods described herein may be implemented in a computer program, software, or firmware incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, magnetic media such as ROM, RAM, registers, cache memory, semiconductor memory devices, internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor associated with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

[0259] Abbreviations Used Δf Subcarrier Spacing 5gFlex 5G Flexible Radio Access Technology 5gNB 5GFlex Node B ACK Acknowledgment BB Baseband BLER Block Error Rate BTI Basic TI (at an integer multiple of one or more symbol durations) CB Contention Based (e.g., access, channel, resource) CoMP Coordinated Multi-Point Transmission / Reception CP Cyclic Prefix CP-OFDM Conventional OFDM (relying on cyclic prefix) CQI Channel Quality Indicator CSI Channel State Information CN Core Network (e.g., LTE Packet Core) CRC Cyclic Redundancy Check CSG Closed Subscriber Group Device-to-Device (D2D) transmission (e.g., LTE side link) Downlink Control Information (DCI) Downlink (DL) Demodulation Reference Signal (DM-RS) Data Radio Bearer (DRB) Equivalent Isotropically-Radiated Power (EIRP) Evolved Packet Core (EPC) Feedback (FB) Filtered Band Multi-Carrier (FBMC) FBMC technique using Offset Quadrature Amplitude Modulation (FBMC / OQAM) Frequency Division Duplexing (FDD) Frequency Division Multiplexing (FDM) Industrial Control and Communications (ICC) Inter-Cell Interference Cancellation (ICIC) Internet Protocol (IP) License-Assisted Access (LAA) Listen Before Talk (LBT) Logical Channel (LCH) Logical Channel Prioritization (LCP) Low Latency Communication (LLC) Long-Term Evolution (LTE), e.g., 3GPP LTE Release 8 and above Medium Access Control (MAC) Negative ACK (NACK) Massive Broadband Communications (MBB) Multi-Carrier (MC) Modulation and Coding Scheme (MCS) Multiple-Input Multiple-Output (MIMO) Machine-Type Communication (MTC) Non-Access Stratum (NAS) Orthogonal Frequency Division Multiplexing (OFDM) Out-of-Band (Emission) P cmax Total Available UE Power in a Given TI PHY Physical Layer PRACH Physical Random Access Channel PDU Protocol Data Unit PER Packet Error Rate PLMN Public Land Mobile Network PLR Packet Loss Rate PSS Primary Synchronization Signal QoS Quality of Service (from the Physical Layer Perspective) RAB Radio Access Bearer RACH Random Access Channel (or Procedure) RF Radio Front End RLF Radio Link Failure RNTI Radio Network Temporary Identifier RRC Radio Resource Control RRM Radio Resource Management RS Reference Signal RTT Round Trip Time SCMA Single Carrier Multiple Access SDU Service Data Unit SL SideLink SOM Spectrum Operation Mode SS Synchronization Signal SSS Secondary Synchronization Signal SRB Signaling Radio Bearer SWG Switching Gap (in a Self-Contained Subframe) TB Transport Block TDD Time Division Duplexing TDM Time Division Multiplexing TI Time Interval (at an Integer Multiple of One or More BTIs) TTI Transmission Time Interval (at an Integer Multiple of One or More TIs) TRP Transmission / Reception Point TRX Transceiver UE User Equipment UFMC Universal Filtered Multi-Carrier UF-OFDM Universal Filtered OFDM UL Uplink URC Ultra-Reliable Communications URLLC Ultra-Reliable and Low Latency Communications V2V Vehicle-to-Vehicle Communication V2X Vehicle Communication WLAN Wireless Local Area Network and Related Technologies (IEEE802.xx Area) ZC Zadoff-Chu Sequence

Claims

Claim 1 A method performed by a wireless transmit / receive unit (WTRU), comprising: the WTRU receiving configuration information indicating a plurality of beam processes, at least one of the plurality of beam processes having a respective identifier, at least one of the plurality of beam processes being associated with an uplink reference signal, at least one of the plurality of beam processes being provisioned with resources for the uplink reference signal, the provisioned resources including an indication of time and frequency resources, and the uplink reference signal being associated with one or more antenna ports; the WTRU receiving downlink control information including an indication of the respective identifier of at least one of the plurality of beam processes; the WTRU selecting a beam process of the plurality of beam processes based on the indication of the respective identifier of at least one of the plurality of beam processes received in the downlink control information; the WTRU performing an uplink transmission based on the selected beam process; A method comprising the above steps. Claim 2 The method of claim 1, further comprising the WTRU receiving using the selected beam process. Claim 3 The method of claim 1, further comprising the WTRU configuring an additional beam process in response to an indication received from a transmit / receive point. Claim 4 The method of claim 1, further comprising configuring the WTRU with at least one of the plurality of beam processes by performing measurements on a downlink reference signal. Claim 5 The method of claim 4, wherein a beam process of the at least one beam process is a beam process for transmission, and the beam process for transmission is determined by the WTRU by performing measurements on the downlink reference signal. Claim 6 A wireless transmit / receive unit (WTRU) comprising a circuit including a plurality of antenna elements, a transmitter, a receiver, a processor, and a memory. Receiving configuration information indicating a plurality of beam processes, wherein at least one of the plurality of beam processes has a respective identifier, at least one of the plurality of beam processes is associated with an uplink reference signal, at least one of the plurality of beam processes is provisioned with resources for the uplink reference signal, the provisioned resources include an indication of time and frequency resources, and the uplink reference signal is associated with one or more antenna ports, and Receiving downlink control information including an indication of the respective identifier of at least one of the plurality of beam processes Selecting a beam process among the plurality of beam processes based on the indication of the respective identifier of at least one of the plurality of beam processes received in the downlink control information Performing an uplink transmission based on the selected beam process A WTRU configured to perform the above Claim 7 The WTRU of claim 6, further configured to receive using the selected beam process Claim 8 The WTRU of claim 6, further configured to configure an additional beam process in response to an indication received by the WTRU from a transmit-receive point Claim 9 The WTRU of claim 6, further configured to configure the WTRU in at least one of the plurality of beam processes by performing measurements on a downlink reference signal Claim 10 A beam process among at least one of the beam processes is a beam process for transmission, The beam process is determined by the WTRU by performing measurements on the downlink reference signal The WTRU of claim 9

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