Downlink control channel design and signaling for system where beamforming is used

Abstract

To provide a wireless transmit / receive unit (WTRU) that applies beamforming transmission and / or reception to control channel transmission / reception in mmW access link system design.SOLUTION: In an idle mode, WTRU that performs monitoring monitors a common search space, seeks presence of a common control channel beam at a symbol location within a control region, searches for a subframe, and correlates known reference signal sequence to search for the subframe, and defines different reference signal sequences for a common control channel beam and / or a WTRU-specific control channel beam.SELECTED DRAWING: Figure 22

Description

[Background technology]

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 253,599, filed Nov. 10, 2015, the entire contents of which are incorporated by reference for all purposes as if fully set forth herein.

[0002] A small cell mmW eNB (SCmB) deployment may be based on a 3GPP R12 small cell deployment. The mmW operation may be performed by one or more network nodes. A small cell mmW eNB (SCmB) may be an LTE small cell eNB capable of operating an mmW air interface in the downlink, possibly together with an LTE air interface.

[0003] An mmW WTRU (mWTRU) may be capable of operating in both LTE and mmW air interfaces. An mWTRU may have one or more sets of antennas and / or associated radio frequency (RF) chains, perhaps one operating in the LTE bands and / or in the mmW frequency bands. Summary of the Invention

[0004] Initial mmW access link system design may focus on cellular system procedures that enable add-on mmW data transmission (e.g., at least downlink transmission) to existing networks such as small cell LTE networks. Transmit and / or receive beamforming may be applied to control channel transmission / reception to overcome high path loss, for example, at frequencies above 6 GHz. Techniques for identifying candidate control channel beams and / or their locations within a subframe structure may provide efficient WTRU operation. A framework for beamformed control channel design may support various capabilities of mBs and / or WTRUs and / or may support time and / or space domain multiplexing of control channel beams. Modifications to reference signal design may discover, identify, measure, and / or decode one or more or each control channel beam, for example, for multi-beam systems, among other scenarios. Techniques may mitigate inter-beam interference. WTRU monitoring may consider a beam search space in addition to a time and / or frequency search space. Techniques for the downlink control channel can support scheduling of narrow data beams. The scheduling mechanism can achieve (e.g., high) resource utilization, perhaps when a large bandwidth is available and / or WTRUs can be spatially distributed.

[0005] For example, one or more beam-specific control channels may be utilized. The beam-specific control channels may utilize a fixed mapping within the frame structure. For example, the beam-specific control channels may be mapped to fixed symbols and / or to fixed subframes within the frame structure. For example, a flexible mapping may be used for the beam-specific control channels within the frame structure.

[0006] For example, a WTRU-specific and / or beam-specific search space may be used for transmission and / or reception of a control channel. The WTRU-specific and / or beam-specific search space may be associated with a serving control channel allocation. The WTRU-specific and / or beam-specific search space may be utilized in a WTRU monitoring procedure. For example, the WTRU may be configured to determine a beam-specific search space size (e.g., with respect to subframe and symbol location). The WTRU may be configured to determine a WTRU-specific search space within a beam and / or a beam-specific search space.

[0007] The WTRU and / or the base station can be configured to perform a method for resource allocation for subframe scheduling. For example, subframe scheduling can enable multiple allocations within a given subframe. For example, sub-subframe scheduling can be performed to take advantage of (e.g., TDM) multiplexing of WTRUs with different downlink beams within a given subframe.

[0008] The WTRU may be configured to identify a downlink data beam that the mB may use for the WTRU. For example, the WTRU may be configured to switch a receive beam used for downlink data based on one or more parameters. For example, the WTRU may be configured to switch a receive beam used for downlink data based on resource allocation information. For example, the WTRU may be configured to switch a receive beam used for downlink data independent of the received resource allocation information. For example, beam combining may be used for DL ​​and / or UL.

[0009] A wireless transmit / receive unit (WTRU) may be configured for wireless communication. The WTRU may comprise a memory. The WTRU may comprise a processor. The processor may be configured with at least one or more search spaces. The one or more search spaces may be configured to provide at least one of monitoring one or more downlink (DL) control channels and / or receiving one or more DL control channels. At least one search space of the one or more search spaces may correspond to at least one reference signal of one or more reference signals. The processor may be configured to at least monitor at least a portion of a control region for at least one reference signal of the one or more reference signals. The processor may be configured to detect the at least one reference signal within at least a portion of the control region. The processor may be configured to monitor at least one search space corresponding to the at least one reference signal for the at least one DL control channel upon detection of the at least one reference signal. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 illustrates an example of a mmW small cell deployment. [Diagram 2] FIG. 13 shows an example of a comparison between frequency filtering and spatial filtering. [Diagram 3] FIG. 2 illustrates an example of an OFDM frame structure. [Figure 4] A diagram showing examples of mmW downlink logical, transport, and physical channels. [Diagram 5] FIG. 1 illustrates an example of fully digitalized beamforming for an mWTRU. [Figure 6] FIG. 1 illustrates an example of analog beamforming for an mWTRU using at least one PAA and at least one RF chain. [Figure 7] FIG. 1 illustrates an example of analog beamforming for an mWTRU using at least one PAA and at least two RF chains. [Figure 8] FIG. 1 illustrates an example of analog beamforming for an mWTRU using at least two PAAs and at least two RF chains. [Figure 9] FIG. 1 illustrates an example of analog beamforming for an mWTRU using at least two PAAs and at least one RF chain. [Figure 10] FIG. 1 shows illustrative 2D and realistic 3D narrow beam pattern examples. [Figure 11] FIG. 1 shows an example of a realistic 3D broadside broad beam pattern. [Figure 12] A diagram showing an example of a physical downlink control channel (PDCCH) type 1a. [Figure 13] A diagram showing an example of PDCCH type 1b. [Figure 14] A diagram showing an example of PDCCH type 2. [Figure 15] A diagram showing an example of PDCCH type 3a. [Figure 16] A diagram showing an example of PDCCH type 3b. [Figure 17] FIG. 1 illustrates an example logical architecture for control channel beam generation. [Figure 18] A diagram showing an example of a subframe structure and arrangement for a control BRS. [Figure 19] FIG. 1 illustrates an example of resource allocation in two dimensions: frequency and time. [Figure 20] A diagram showing an example of a subframe structure and arrangement for a control BRS for parallel beam sweeping. [Figure 21] FIG. 1 illustrates an example of resource allocation in two dimensions: frequency and time. [Figure 22] FIG. 1 illustrates an example of a common control channel beam and search space. [Figure 23] A diagram showing an example of a WTRU beam specific search space. [Figure 24A] FIG. 1 is a system diagram of an example communication system. [Figure 24B] FIG. 24B is a system diagram of an example wireless transmit / receive unit (WTRU) that may be used within the communications system shown in FIG. 24A. [Figure 24C] A system diagram of an example radio access network and an example core network that can be used within the communication system shown in FIG. 24A. [Figure 24D] 24B is a system diagram of another example radio access network and an example core network that can be used within the communication system shown in FIG. 24A. [Figure 24E] 24B is a system diagram of another example radio access network and an example core network that can be used within the communication system shown in FIG. 24A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A detailed description of illustrative embodiments will now be provided with reference to various figures. While this description provides detailed examples of possible implementations, it should be noted that the details are intended to be examples and are in no way intended to limit the scope of the present application.

[0012] An mmW deployment may be used, for example, based on a 3GPP R12 small cell deployment, possibly using an extension of the LTE carrier aggregation scheme. An example is a small cell mmW eNB (SCmB) deployment. The SCmB may be based on a 3GPP R12 small cell deployment. The mmW operation may be performed by one or more of the following network nodes: The LTE small cell eNB may be capable of operating an mmW air interface in the downlink, for example, in parallel with the LTE air interface. The SCmB may simultaneously transmit an LTE downlink channel in a wide beam pattern and / or an mmW channel in a narrow beam pattern, for example, when it is equipped with an advanced antenna configuration and / or beamforming techniques. The SCmB may support functions and / or procedures in LTE uplink (UL) operation, for example, to support an mmW radio transmit / receive unit (WTRU) without mmW uplink transmission. A wireless transmit / receive unit (WTRU) capable of operating an mmW air interface, possibly in parallel with a non-mmW LTE system, may be referred to as an mmW wireless transmit / receive unit (mWTRU) and / or mmW user equipment (mUE). mWTRU and / or mUE may be used interchangeably herein. WTRU may be used herein to refer to an mWTRU.

[0013] For example, an mWTRU may include antennas (e.g., two or more sets) and / or associated RF chains, some operating in the LTE bands and / or some for operation in the mmW frequency bands. Some of the antennas and / or associated RF chains may share some hardware and / or functional blocks, but the antennas and / or associated RF chains may perform independent baseband processing functions. For example, when the mmW air interface has similarities to LTE systems, the baseband functions may share certain hardware blocks.

[0014] For example, mmW channels can be used as an extension of the LTE carrier aggregation scheme. One or more mmW channels can be carrier types in the mmW frequency band. One or more mmW channels can apply different air interfaces and / or legacy LTE. One or more mmW channels can serve opportunistically for high throughput and / or low latency traffic data applications.

[0015] LTE channels can carry control signaling, such as system information updates, paging, radio resource control (RRC), and / or non-access stratum (NAS) signaling (signaling radio bearers), and / or multicast traffic. LTE channels can be used to carry mmW Layer 1 (L1) control signaling.

[0016] The SCmB and / or mWTRU may utilize narrow beamforming, e.g., in non-line-of-sight (NLOS) in mmW frequency bands, possibly due to, e.g., the relatively high propagation loss associated with the mmW bands. The use of narrow beamforming may provide a (e.g., sufficient) link budget for high-throughput and / or low-latency data transmission.

[0017] Transmit and / or receive narrow beam pairing can be used. For example, consistent coverage with at least up to 200 meter cell radius can be achieved at 28 GHz and / or 38 GHz in metropolitan areas by using steerable 10° beamwidth and / or 24.5 dBi horn antennas for transmit and / or receive.

[0018] To meet the high data rates required for next generation cellular communication systems, the wireless industry and / or research institutes have been exploring ways to utilize the large bandwidth available in frequencies above 6 GHz, e.g., cmW and / or mmW frequencies. The large bandwidth available in these frequencies can provide capacity improvements for user-specific data transmissions. One challenge in using these frequencies above 6 GHz can be their propagation-related characteristics that can be disadvantageous for wireless communication, especially in outdoor environments. For example, higher frequency transmissions can experience higher free space path loss. Rainfall and / or atmospheric gases, e.g., oxygen, can add additional attenuation, and / or foliage can cause attenuation and / or depolarization. Narrow beam patterns that can be used to counter these losses can pose challenges for base stations (e.g., eNBs), for example, in delivering cell-specific and / or broadcasted information.

[0019] FIG. 1 shows an example of an SCmB deployment. The SCmB may use a narrow beam for downlink transmission. One or more mWTRUs may use a receiving narrow beam to receive the downlink transmission. The SCmB and / or mWTRU may apply a broad beam pattern for traditional LTE operations, including cell search, random access, and / or cell selection / reselection, etc.

[0020] 2 is an example of mWTRU receive beamforming, for example, using narrow spatial filtering, and includes an exemplary comparison with frequency domain filtering to show the effect of spatial and / or angular filtering.

[0021] Spatial filtering, perhaps similar to frequency filtering that removes undesired frequency components, can enable the mWTRU to detect the channel impulse response in different angular directions captured by a narrow receive beam. This can result in a flat effective channel by rejecting angular arrival paths outside its beamwidth. An R12 LTE WTRU can be assumed to have an omnidirectional receive beam pattern and / or can sense the channel impulse response superimposed over the entire angular domain. Aligned mmW transmit and receive beam pairs can provide a degree of freedom in the angular domain compared to current LTE systems.

[0022] mmW system (e.g., downlink system) design can focus on incorporating directionality, e.g., narrow transmit and / or receive beam pair directionality, into the cellular system, which can include L1 control signaling, data scheduling, narrow beam pairing, beam measurements, and / or L1 control information feedback, etc.

[0023] Several examples of mmW system parameters and / or assumptions are described herein. The parameters and / or assumptions may vary, for example, depending on the type of deployment. These parameters and / or assumptions are not intended to be limiting, but rather to help illustrate an example set of parameters and / or assumptions for an example mmW system. The parameters and / or assumptions may be utilized in various combinations.

[0024] For example, an exemplary carrier frequency for mmW operation may be 28 GHz. This is an exemplary system figure. Similar designs may be extended to other mmW frequencies, e.g., 38 GHz, 60 GHz, 72 GHz, etc. The system bandwidth may be variable (e.g., per carrier), e.g., up to a certain maximum system bandwidth. With carrier aggregation, possibly used to achieve a higher total bandwidth, a maximum system bandwidth of, e.g., 1 GHz may be used. With narrow beam patterns, the estimated RMS delay spread may be 100-200 ns. The latency may be 1 ms. The waveform may be OFDM-based, or broadband single carrier-based. For example, dual connectivity may be based on an LTE small cell eNB with mmW add-on channels and RF chains connected to two separate antennas and / or two different antenna solutions. The system design parameters may be to achieve a DL data rate of 30 Mbit / s for at least 95% of mWTRUs, although other design goals may be used. Mobility can be data optimized at 3km / h and / or maintain connectivity at 30km / h. Coverage can meet data rate and / or mobility requirements when using cell radii of less than 100m.

[0025] One or more waveforms, such as broadband cyclic prefixed single carrier (CP-SC), OFDM, SC-OFDM, MC-CDMA, generalized OFDM, and / or FBMC, may be used for the air interface of a system, e.g., an above 6 GHz system (e.g., cmW and / or mmW). The frame structure for the system may depend on the waveform applied. For example, to achieve low latency, a transmission time interval (TTI) length such as 100 μs may be used. For example, to achieve high data rates, a system bandwidth, e.g., one within the range of 50 MHz to 2 GHz, may be used.

[0026] The mmW frame structure of the OFDM-based waveform can provide flexibility in coordination between LTE and mmW channels and / or enable common functional block sharing in mWTRU devices. For example, the mmW sampling frequency can be selected as an integer multiple of the LTE minimum sampling frequency of 1.92 MHz, which can result in a mmW OFDM subcarrier spacing Δf that is an integer multiple of the LTE subcarrier spacing of 15 kHz, e.g., Δf=15×K kHz. The selection of the integer multiple K and / or the resulting Δf can take into account sensitivity to Doppler shift, ability to remove different types of frequency errors, and / or channel time dispersion, etc. Perhaps, for example, when the Doppler shift increases proportionally to the subcarrier spacing, the orthogonality between subcarriers may deteriorate and / or inter-subcarrier interference (ISI) may increase.

[0027] For example, the maximum Doppler shift at 30 km / h and 28 GHz can be about 778 Hz. An exemplary 28 GHz channel time dispersion measurement in a dense metropolitan area can show an RMS delay spread σ that can be between 100 and 200 ns for cell radii up to 200 m. The 90% coherence bandwidth can be estimated to be at 1 / 50σ of 100 kHz, and the 50% coherence bandwidth can be estimated to be at 1 / 5σ of 1 MHz.

[0028] A subcarrier spacing Δf between 100 kHz and 1 MHz may be reasonable. A subcarrier spacing of 300 kHz (K=20) may be robust to Doppler shifts and / or other types of frequency errors and / or may reduce implementation complexity. The corresponding symbol length (1 / Δf) may be approximately 3.33 μs.

[0029] The cyclic prefix (CP) length can be configured to span the length of the channel time dispersion to eliminate inter-symbol interference. For example, the CP may not be able to carry useful data or may not be able to carry useful data, and / or in some scenarios, a long CP may cause excessive system overhead. symbol An example of the CP length for T symbol The time can be chosen to be 0.24 μs, which is 1 / 14 of the time, and / or the corresponding CP overhead can be chosen to be T CP / (T CP +T symbol ) and can be 7%.

[0030] The TTI length of mmW transmissions can possibly be reduced, e.g., compared to the 1 ms TTI length of LTE systems, to achieve low latency. In some scenarios, it may be beneficial to have a 1 ms mmW subframe length to align with the LTE 1 ms subframe timing. A mmW subframe can include multiple mmW TTIs, whose length can be tied to other parameters, e.g., subcarrier spacing, symbol length, CP length, and / or FFT size.

[0031] Based on these and / or other considerations, an example of using a conservative CP length (4× channel delay spread) is summarized in Table 1. It can be assumed that the CP length selection is based on the delay spread over the potential mmW frequency band, below 200 ns.

[0032] [Table 1]

[0033] FIG. 3 shows an exemplary OFDM-based frame structure. In FIG. 3, the system bandwidth may be 1 GHz and / or a subcarrier spacing of 300 kHz may be used with a corresponding symbol length of 3.33 μs. T symbol An exemplary cyclic prefix (CP) length of 1 / 4 may be used.

[0034] Some of the example frame structures presented herein may be based on the assumption of an OFDM-based mmW waveform, which may be incorporated into an OFDM-based LTE small cell network. The system procedures described herein may be equally applicable to numerous types of frame designs and / or should not be construed as being bound by this particular frame structure and / or may apply to other waveform candidates.

[0035] An SCmB and / or mWTRU deployment may utilize, for example, one or more of the following mmW physical layer channels and / or reference signals instead of and / or in addition to LTE physical channels:

[0036] The SCmB and / or mWTRU may utilize a unique sequence transmitted per transmission beam, e.g., a Beam-Specific Reference Signal (BSRS), used for beam acquisition, timing / frequency synchronization, channel estimation for the Physical Downlink Directional Control Channel (PDDCCH), beam tracking and / or measurements, etc. The BSRS may implicitly carry beam identity information including a BSRS sequence index. Different types of BSRS may exist. BSRS resource allocation may be predefined.

[0037] The SCmB and / or mWTRU may utilize a unique sequence, e.g., an Adaptive Antenna Reference Signal (AARS), that is dynamically scheduled and / or transmitted for the purpose of beam pair measurements specific to a given antenna port. The AARS may implicitly embed beam identity information in the sequence index and / or may carry a small payload containing the same.

[0038] The SCmB and / or mWTRU may utilize a physical downlink directional control channel (PDDCCH). The PDDCCH may carry some or all data-related control information for the mWTRU to properly identify, demodulate, and / or decode the associated physical downlink directional data channel (PDDDCH). The PDDCCH may be carried on a mmW narrow beam and / or on a broad beam and / or may apply to different multiple accesses. For example, when an mWTRU-specific data transmission is in progress, there may be a common PDDCCH transmitted on a downlink mmW broad beam covering a sector and / or cell, and / or a dedicated PDDCCH transmitted (e.g., transmitted) on a narrow beam pair. The dedicated PDDCCH may carry scheduling information for its associated PDDDCH per TTI and / or may not or may not carry beam-specific information. The common PDDCCH may include cell-specific information, including sector / segment identity and / or beam identity (beam identification). In addition, the mWTRU may determine whether it is scheduled for a narrow beam pairing procedure to read the common PDDCCH and then initiate narrow beam data transmission.

[0039] The SCmB and / or mWTRU may utilize a physical downlink directional data channel (PDDDCH). The PDDDCH may carry payload information received in the form of MAC PDUs from the mmW MAC layer. Resource allocation for this channel may be determined by downlink scheduling information carried in the PDDCCH. The PDDDCH destined for the mWTRU may be transmitted in a narrow transmit beam and / or received in an appropriately paired narrow receive beam, for example, with a narrow beam pair. Thanks to this spatial isolation, the PDDDCHs for different WTRUs in different beam pairs may reuse one or more time, frequency, and / or code resource combinations. Multiple PDDDCHs may also operate in one beam pair using multiple access in one or more of the time, frequency, and / or code domains, etc. A common PDDDCH may be used to carry data in a broad mmW antenna pattern associated with a common PDDCCH.

[0040] The SCmB and / or mWTRU may utilize symbols embedded in the transmission, e.g., demodulation reference signals (DMRS), for channel estimation for the PDDDCH. For example, the DMRS may be positioned in the time and / or frequency domain according to a predefined pattern to ensure correct interpolation and / or reconstruction of the channel.

[0041] Some or all channels and / or reference signals in a narrow beam pair may be beamformed in the same way and / or may be considered to be transmitted through a specific and / or single physical antenna port. Carrying of broadcast and / or multicast information on narrow beams may be utilized, but given the directional nature of the transmission of these channels, carrying broadcast, multicast, and / or other cell-specific information on narrow beams may not or may not be an optimal application. SCmB deployments using mmW downlink data transmission may employ a channel mapping as shown in FIG. 4, where the mmW channels are shown in bold colored lines.

[0042] The mWTRU can achieve beamforming gain using a phased antenna array, for example, to compensate for the high path loss at mmW frequencies, where the short wavelengths can allow for compact form factors in device design. Larger spacings, such as 0.7λ, can be applied. In theoretical performance analysis, an element spacing of 0.5λ can be used.

[0043] A phased antenna can apply one or more different beamforming methods. For example, a fully digitalized beamforming approach can have a dedicated RF chain. For example, the RF chain can include RF processing and / or analog-to-digital conversion (ADC), as shown in FIG. 5 for an antenna element. The signals processed by the antenna elements can be independently controlled in phase and amplitude to optimize channel capacity.

[0044] The configuration may have as many RF chains and ADCs as that of antenna elements. The mWTRU antenna may provide (e.g., very) high performance. The mWTRU antenna configuration may impose cost and / or complexity in implementation. The mWTRU antenna configuration may cause high energy consumption during operation. Fully digitalized beamforming may not or may not be employed in early 5G deployments and / or mWTRU implementations, but may be used in future releases.

[0045] FIG. 6 may be an example of analog beamforming. In analog beamforming, for a given phased antenna array (PAA), an RF chain (e.g., only one RF chain) may be applied. For example, an antenna element may be connected to a phase shifter. The phase shifter may be used to set weights for beamforming and / or steering. Using analog beamforming, the number of RF chains may be reduced (e.g., significantly) (e.g., compared to digital beamforming). Energy consumption may be reduced significantly.

[0046] In beamforming, the phase of the signals at the antenna elements may be adjusted (e.g., only the phase). Figure 6 shows that the phase shifting and / or combining may be performed at different stages, e.g., RF, baseband (BB) analog, and / or local oscillator (LO). One or more of the techniques described herein may be used to evaluate the effectiveness / efficiency of the approach, e.g., signal loss, phase error, and / or power consumption, etc.

[0047] The mWTRU analog beamforming method may include one or more of the following: The mWTRU analog beamforming algorithm may include a grid of beams with a fixed set of beams, e.g., fixed codebook-based beamforming, where the beams are determined by a beamforming weight vector v, v∈{v1, v2, v3...v} selected from a predefined codebook. N} may be applied to form by the mWTRU, where N denotes the number of fixed beams. The vector may include pre-calibrated phase shifts for some (e.g., one or more or all) phase shifters and / or may represent unique analog beam directions, e.g., "beams". The number of beams may depend on the half-power beamwidth (HPBW) of the beamforming and / or the desired coverage. The mWTRU analog beamforming algorithm may include continuous phase-shift beamforming. For example, the desired weights of the phase shifters may be calculated based on estimated short-term channel information and / or may be converted using a high-resolution digital-to-analog converter (DAC) for the phase shifters. The continuous phase-shift beamforming may provide continuous and / or adaptive beamforming to track channel conditions. The algorithm may work well in one or more scenarios, e.g., with increased multipath, high angular spread, and / or low WTRU mobility.

[0048] The mWTRU may utilize a hybrid approach including digitized beamforming and analog beamforming. For example, analog beamforming may be performed on a phased array antenna element, where the antenna element is associated with a phase shifter and / or connected to one RF chain. Digitalized beamforming may include digital precoding applied on the baseband signal of an RF chain, for example, when there are two or more RF chains. Digital precoding may be used to implement MIMO schemes.

[0049] An example of the basic system parameters for hybrid beamforming is given below for the number of data streams N DATA , the number of RF chains (TRX) N TRX , the number of antenna ports N AP , the number of antenna elements N AE , and / or the number of phased antenna arrays N PAA etc. Configuration of these parameters can affect system functionality and / or performance.

[0050] For example, perhaps N PAA ≦N AP ≦N TRX ≦N AEWhen p = 0, one or more of the following may occur: The PAA may comprise multiple antenna elements, e.g., a PAA of size 4×4 has 16 antenna elements; Antenna ports may be defined and / or the channel on which a symbol on an antenna port is carried may be inferred from the channel on which another symbol on the same antenna port is carried; There may be one (e.g., one or more) resource grids per antenna port; One or more cell-specific reference signals may support configurations of one, two, and / or four antenna ports and / or may be transmitted on antenna ports p=0, p∈{0,1}, and p∈{0,1,2,3}, respectively; A Multicast-Broadcast Single Frequency Network (MBSFN) reference signal may be transmitted on antenna port p=4. One or more WTRU-specific reference signals associated with the PDSCH may be transmitted on antenna ports p=5, p=7, p=8, or on one or more of p∈{7, 8, 9, 10, 11, 12, 13, 14}.

[0051] One or more demodulation reference signals associated with an enhanced physical downlink control channel (EPDCCH) may be transmitted on one or more of p∈{107, 108, 109, 110}. A positioning reference signal may be transmitted on antenna port p=6. A CSI reference signal may support a configuration of one, two, four, or eight antenna ports and / or may be transmitted on antenna ports p=15, p∈{15,16}, p∈{15,16,17,18}, and p∈{15,16,17,18,19,20,21,22}, respectively. An antenna port may carry a beamformed reference signal that may be uniquely associated with this antenna port and / or may be used to identify the antenna port. The antenna configuration may be (e.g., fully) digital, for example, as shown in FIG. 5, perhaps when the number of TRXs is equal to the number of antenna elements. An example may be one RF chain per antenna element. The PAA may be connected to an RF chain (as shown in FIG. 6) and / or multiple RF chains, depending on the system configuration, for example. In FIG. PAA <N AP =N TRX <N AE and one PAA of size 4×4 is connected to two RF chains, and / or one or more or each RF chain has a set of 16 phase shifters. The PAA can form two narrow beam patterns within the coverage of +45° to −45° in the azimuth plane. FIG. 8 is an example of two PAAs, and / or one or more or each PAA can have a dedicated RF chain, e.g., N PAA =N AP =N TRX ≦N AEThe example in Fig. 8 can enable spatial independence between two simultaneous beams, for example by placing the PAA at different orientations in the azimuth plane. The aligned PAA placement can provide a larger combined coverage compared to the configuration in Fig. 7. Both configurations with two RF chains can apply MIMO with two data streams.

[0052] For example, perhaps N AE >N PAA >N AP =N TRX When , multiple PAAs can be connected to a (e.g., single) RF chain by using a switch, as shown in Figure 9. The PAAs can form narrow beam patterns covering +45° to -45° in the azimuth plane. They can point in different directions. A single beam solution can provide (e.g., good) coverage by using narrow beams in different directions at different time steps.

[0053] For example, N DATA ≦N TRX ≦N AE When , the following can occur:

[0054] For example, N DATA =N TRXWhen r = 1, the mWTRU may have a single beam configuration and / or may operate one beam at a time. One or more of the following may occur: The mWTRU beamforming may form a narrow beam pattern. FIG. 10 is an example for a 16×16 PAA in the strongest angular direction, e.g., line-of-sight (LOS) path obtained from beam measurements. The mWTRU may form a broad beam pattern, e.g., a wide main lobe. FIG. 11 is an example of a wide main lobe covering a range of continuous angular directions with strong and / or weak spots in between. Antenna gain may be reduced (e.g., significantly) and / or link budget may be poor with a broad beam pattern.

[0055] For example, N DATA =1 <N TRX When N , the mWTRUs can have simultaneous beam patterns. The beam patterns can be different and / or can be used for different applications. For example, TRX When r = 2, the mWTRU can have two different simultaneous beam patterns and / or can be used for different applications. One or more of the following can be applied: The mWTRU can receive one data stream with two narrow beam patterns arranged at different angle arrival directions. For example, coherent beam combining can be used for spatial diversity and / or to mitigate occlusion effects and / or poor LOS conditions. The mWTRU can form one narrow beam and / or one broad beam for different applications. For example, the narrow beam can be used for data transmission and the broad beam can be for control signaling.

[0056] For example, perhaps 1 <N DATA =N TRXWhen , the transmission can apply MIMO to increase capacity, for example, in high SNR channel conditions. The mWTRU can receive two data streams in parallel by arranging two narrow beam patterns at different angle arrival directions.

[0057] One or more of the SCmB beamforming schemes may include fixed beams, adaptive beamforming (e.g., codebook-based and / or non-codebook-based), and / or classical beamforming, e.g., direction of arrival (DoA) estimation. One or more schemes may use different approaches and / or perform better in certain scenarios. For example, DoA estimation may use a smaller angular spread and / or the mWTRU may (e.g., may need to) transmit an LTE uplink reference signal to ensure DoA accuracy. Fixed beam systems may require beam cycling and / or switching.

[0058] One or more of the examples described herein may be described in terms that assume an mWTRU antenna configuration and / or beamforming configuration. The mWTRU antenna configuration and / or beamforming configuration may be based on a single beam mWTRU antenna configuration with analog beamforming as shown in Figure 6. Methods and / or techniques using other beamforming methods, such as digital beamforming and / or hybrid beamforming, may also be applied.

[0059] LTE / LTE-A and / or E-PDCCH have been developed. In Rel-8, RE, REG, CCE, and / or PDCCH may be as follows: The smallest time-frequency unit for downlink transmission may be referred to as a resource element (RE). An element (e.g., one or more or each) in a resource grid for antenna port p may be referred to as a resource element and / or may be uniquely identified within a slot by an index pair (k, l), where k and / or l may be an index in the frequency domain and / or the time domain, respectively. A physical downlink control channel (PDCCH) may carry scheduling allocations and / or other control information. A group of four consecutive resource elements may be referred to as a resource element group (REG). A physical control channel may be transmitted on an aggregation of one or more consecutive control channel elements (CCEs), where a control channel element corresponds to nine REGs.

[0060] In Rel-11, the EPDCCH WTRU specific search space may be as follows: EPDCCH was introduced in Rel-11 LTE Advanced to achieve frequency domain ICIC and / or beamforming gain. From now on, EPDCCH, ePDCCH, and / or E-PDCCH can be used interchangeably. Also, EREG and / or ECCE can be used interchangeably with eREG and / or eCCE, respectively.

[0061] In Rel-11, the PRB configuration may be as follows: In Rel-11, ePDCCH resources for a WTRU-specific search space may be configured as a subset of PRBs in a PDSCH region. The ePDCCH resources may be configured in a WTRU-specific manner and / or up to two ePDCCH resource sets may be configured for the WTRU. The ePDCCH resource set may include two, four, and / or eight PRB pairs according to the configuration and / or may be configured as a localized and / or distributed resource set.

[0062] In Rel-11, eREGs can be defined as follows: In (e.g., one or more or each) PRB pair configured as ePDCCH resource, 16 eREGs can be defined regardless of normal CP and / or extended CP. REs for eREGs can be assigned cyclically in a frequency-first manner and / or rate-matched around demodulation RSs such as antenna ports {107, 108, 109, 110}. Since channel estimation performance may differ according to RE location in PRB pair, randomization of channel estimation performance across eREGs may occur. Since antenna ports 107 and / or 108 are defined (e.g., only defined) for extended CP, REs for eREGs can be assigned cyclically in a frequency-first manner and / or rate-matched around demodulation RSs such as antenna ports {107, 108}.

[0063] An eCCE can be defined as follows: An eCCE can be defined as a group of 4 and / or 8 eREGs within an ePDCCH resource set. Therefore, the number of eCCEs per ePDCCH resource set (N eCCE,set ) is the number of PRB pairs configured for the ePDCCH resource set (NPRB.set ), and / or the number of eREGs that are grouped together to form an eCCE (N eREG ) as a function of N eCCE,set =16×N PRB,set / N eREG Two types of eCCEs, such as localized eCCE (L-eCCE) and / or distributed eCCE (D-eCCE), can be defined according to the mode of the ePDCCH resource set. Four and / or eight eREGs located in the same PRB pair can be grouped together to form an L-eCCE. On the other hand, eREGs in different PRB pairs can be grouped to form a D-eCCE. Possibly, according to the ePDCCH transmission configured for the ePDCCH resource set, a certain (e.g., one or more or all) eREGs in the ePDCCH resource set can be used to form an L-eCCE and / or a D-eCCE. For example, if the ePDCCH resource set can be configured as a localized ePDCCH, a certain (e.g., one or more or all) eREGs in the ePDCCH resource set can be used to form an L-eCCE. In other words, within an ePDCCH resource set, there may be L-eCCEs and / or D-eCCEs. Perhaps, for example, a (e.g., sufficient) number of REs per eCCE may be available to be able to use a (e.g., required) effective coding rate in one or more scenarios, so that, in TDD, for example, four eREGs may be grouped to form an eCCE in the case of normal subframes and / or special subframe configurations 3, 4, 8.

[0064] The antenna port mapping may be as follows: For normal CP and / or extended CP, antenna ports {107, 108, 109, 110} and {107, 108} may be used, respectively. According to the ePDCCH transmission mode (e.g., localized ePDCCH and / or distributed ePDCCH), the antenna port mapping rule may be different, since the (e.g., one or more or each) ePDCCH transmission mode targets different system and / or channel environments. For example, the antenna port mapping for distributed ePDCCH may be designed to maximize the diversity gain since it is introduced for open-loop transmission. On the other hand, the antenna port mapping rule for localized ePDCCH may be defined to take advantage of WTRU-specific beamforming gain and multi-user MIMO gain.

[0065] For a distributed ePDCCH, two (e.g., only two or more) antenna ports {107, 109} from {107, 108, 109, 110} may be used to improve channel estimation gain, while for a localized ePDCCH, one (e.g., one or more or all) antenna ports may be used. This may be due to the fact that one PRB pair may be shared with up to four WTRUs, so WTRU-specific beamforming may use (e.g., require) a larger number of antenna ports. This may enable, for example, WTRU-specific beamforming of up to four WTRUs within a PRB pair.

[0066] The reference signal sequence may be as follows: A predefined sequence (e.g., pseudorandom (PN) and / or m-sequence, etc.) may be multiplexed with the downlink RS to minimize inter-cell and / or intra-cell interference. This may improve the accuracy of channel estimation and / or increase the multi-user spatial multiplexing gain. For some (e.g., any) of the EPDCCH antenna ports {107, 108, 109, 110}, the reference signal sequence r(m) may be:

[0067]

number

[0068] can be defined by

[0069]

number

[0070] represents the maximum number of RBs for the downlink system bandwidth, and c(i) represents a pseudo-random sequence. The pseudo-random sequence generator is At the beginning of (e.g., one or more or each subframe),

[0071]

number

[0072] It can be initialized using:

[0073]

number

[0074] may be configured independently for each (e.g., one or more, or each) EPDCCH resource set;

[0075]

number

[0076] However, it can be used.

[0077] The WTRU-specific search space may be as follows: In Rel-11, a WTRU-specific search space may be introduced (e.g., only introduced) for EPDCCH. A common search space may be located in the PDCCH region. For downlink control signaling reception, the WTRU monitoring behavior may be defined in a downlink subframe as one of the following: The WTRU may monitor a WTRU-specific search space in the EPDCCH and / or a common search space in the PDCCH, e.g., the EPDCCH monitoring subframe may be configured via higher layer signaling. The WTRU may monitor a WTRU-specific search space and / or a common search space in the PDCCH, and possibly use a fallback of the WTRU-specific search space even if a subframe is configured for monitoring an ePDCCH subframe, e.g., when ePDCCH is not available in that subframe. Some collisions may occur between ePDCCH REs and / or other signals. The WTRU may monitor the PDCCH for a WTRU-specific search space.

[0078] Perhaps the available number of REs is less than a threshold (n EPDCCH <104), the aggregation level can be increased to maintain the effective coding rate. For example, EPDCCH Supportable ePDCCH formats for localized transmission when N ECCE ∈{2,4,8,16}, while in other cases, N ECCE ∈{1,2,4,8} can be used. According to the ePDCCH transmission mode the set of aggregation levels can be different.

[0079] Collision handling may be performed. An ePDCCH RE may be defined as an RE in a PRB pair that is not occupied by antenna ports {107, 108, 109, 110}. Figures 1-24 may show examples of ePDCCH RE definition in a PRB pair according to CP length without collision with other signals, resulting in 144 and / or 128 available REs for normal CP and / or extended CP, respectively. The ePDCCH resources may be configured in a PDSCH region. The REs for ePDCCH may collide with other signals, e.g., CSI-RS, CRS, PRS, PBCH, SCH, and / or PDCCH. The WTRU behavior when an RE collides with other signals may be defined as one or more of the following: The coded bits for ePDCCH may be rate matched to avoid REs that collide with CSI-RS, CRS, and / or PDCCH. A PRB pair used for the PBCH and SCH in a subframe may not be or may not be used for the ePDCCH, and the REs available for the ePDCCH may be smaller, for example, when other signals are transmitted within a PRB pair configured for the ePDCCH.

[0080] Transmit and / or receive beamforming can be applied to the control channel transmission / reception, for example, to overcome high path loss at frequencies above 6 GHz. The resulting beamformed link can be considered as spatial filtering and / or can restrict the WTRU to receive incoming angle paths (e.g., only incoming angle paths) within the formed beam pair.

[0081] Legacy cellular systems may rely on omnidirectional and / or cell-wide beams for control channel transmission. From the WTRU's perspective, the placement of the control channel may be well defined, e.g., within a control region. At higher frequencies, a base station (e.g., one or more or each) may have multiple control channel beams to cover a cell. A WTRU may be able to receive (e.g., only be able to receive) a subset of those control channel beams. One or more techniques for identifying candidate control channel beams and / or their locations within a subframe structure may be defined for efficient WTRU operation.

[0082] One or more mBs and / or WTRUs in a system in which beamforming is used may have a diverse set of capabilities, e.g., different numbers of RF chains, different beam widths, and / or different numbers of PAAs. One or more mBs using multiple RF chains may transmit control channel beams in the same control symbol. One or more WTRUs using one or more or multiple RF chains may receive the same control symbol using a receive beam pattern. For example, one or more mBs using one RF chain may (e.g., need to) multiplex control channel beams in the time domain (e.g., different symbols and / or different subframes). One or more mBs using an RF chain may multiplex control channel beams in the time and / or spatial domains.

[0083] The framework for beamformed control channel design may be used to support different capabilities of mBs and / or WTRUs and / or to support time and / or spatial domain multiplexing of the control channel beams.

[0084] The common reference signal design in LTE may assume cell-wide transmission. For multi-beam systems, modifications to the reference signal design may be used to discover, identify, measure, and / or decode (e.g., one or more or each) control channel beam. In multi-beam systems, interference between beams may degrade overall cell capacity, so additional mechanisms to mitigate inter-beam interference may be beneficial, e.g., for intra-cell and / or inter-cell scenarios.

[0085] WTRU monitoring may be defined to consider a beam search space in addition to a time and / or frequency search space.

[0086] Extensions to the downlink control channel may be beneficial to support scheduling of narrow data beams. For example, perhaps when large bandwidths are available and / or WTRUs can be spatially distributed, one or more mechanisms may be beneficial to achieve high resource utilization.

[0087] mB, SCmB, mmW eNB, eNB, cell, small cell, Pcell, and / or Scell ​​may be used interchangeably. The terms operation may be used interchangeably with transmitting and / or receiving. Component carrier and / or mmW carrier may be used interchangeably with serving cell.

[0088] An mmW eNB may transmit and / or receive one or more mmW channels in a band (e.g., licensed and / or unlicensed bands). An mmW eNB may transmit and / or receive one or more signals in a band (e.g., licensed and / or unlicensed bands). The eNB may be replaced with one or more WTRUs and still be consistent with the techniques described herein. The WTRU may be replaced with an eNB and still be consistent with the techniques described herein. The downlink (DL) may be replaced with an UL and still be consistent with the techniques described herein. The UL may be replaced with a DL and still be consistent with the techniques described herein.

[0089] A channel may refer to a frequency band, which may have a center and / or carrier frequency, and a bandwidth. A licensed spectrum may include one or more channels, which may or may not overlap. An unlicensed spectrum may include one or more channels, which may or may not overlap. Channel, frequency channel, radio channel, and / or mmW channel may be used interchangeably. Access to a channel may be the same as use of (e.g., transmitting and / or receiving on, and / or using) a channel.

[0090] A channel can refer to an mmW channel and / or signal, e.g., an uplink physical channel and / or signal. A channel can refer to an mmW channel and / or signal, e.g., a downlink physical channel and / or signal. The downlink channel and / or signal can include one or more of the following: mmW synchronization signal, mmW broadcast channel, mmW cell reference signal, mmW beam reference signal, mmW beam control channel, mmW beam data channel, mmW hybrid ARQ indicator channel, mmW demodulation reference signal, PSS, SSS, DMRS, CRS, CSI-RS, PBCH, PDCCH, PHICH, EPDCCH, and / or PDSCH, etc. The uplink channel and / or signal can include one or more of the following: mmW PRACH, mmW control channel, mmW data channel, mmW beam reference signal, mmW demodulation reference signal, PRACH, PUCCH, SRS, DMRS, and / or PUSCH, etc. The terms channel and mmW channel can be used interchangeably. Channel and signal may be used interchangeably.

[0091] Data / control may mean one or more of the following: data, control signals, and / or channels, etc. Control may include synchronization. Data / control may be mmW data / control. Data / control, data / control channels, and / or signals may be used interchangeably. Channels and signals may be used interchangeably. The terms control channel, control channel beam, PDCCH, mPDCCH, mmW PDCCH, mmW control channel, directional PDCCH, beamformed control channel, spatial control channel, control channel slice, and / or high frequency control channel may be used interchangeably. The terms data channel, data channel beam, PDSCH, mPDSCH, mmW PDSCH, mmW data channel, directional PDSCH, beamformed data channel, spatial data channel, data channel slice, and / or high frequency data channel may be used interchangeably.

[0092] A channel resource may be, for example, a resource (e.g., a 3GPP LTE and / or LTE-A resource) such as a time, frequency, code, and / or spatial resource. A channel resource may, for example, carry, at least some of the time, one or more channels and / or signals. Channel resource may be used interchangeably with channel and / or signal.

[0093] mmW beam reference signal, mmW reference resource for beam measurement, mmW measurement reference signal, mmW channel condition measurement reference signal, mmW demodulation reference signal, mmW sounding reference signal, reference signal, CSI-RS, CRS, DM-RS, DRS, measurement reference signal, reference resource for measurement, CSI-IM, and / or measurement RS may be used interchangeably. mmW cell, mmW small cell, SCell, secondary cell, licensed assisted cell, unlicensed cell, and / or LAA cell may be used interchangeably. mmW cell, mmW small cell, PCell, primary cell, LTE cell, and / or licensed cell may be used interchangeably. Interference, and interference plus noise may be used interchangeably.

[0094] The WTRU may determine the UL and / or DL ​​direction of one or more subframes according to one or more received TDD UL / DL configurations. The WTRU may determine the UL and / or DL ​​direction of one or more subframes according to one or more configured TDD UL / DL configurations. UL / DL and UL-DL may be used interchangeably.

[0095] The techniques described herein for beamformed control and data channels may be applicable to any system, possibly regardless of frequency band, use (e.g., licensed, unlicensed, shared), antenna configuration (e.g., phased array, and / or patch, and / or horn, etc.), RF configuration (e.g., single and / or multiple RF chains), beamforming method used (e.g., digital, analog, and / or hybrid, and / or codebook-based, etc.), and / or deployment (e.g., macro, small cell, heterogeneous network, dual connectivity, remote radio head, carrier aggregation). cmW (centimeter wave), and / or LTE / LTE-A / LTE Evolution may be replaced with mmW (millimeter wave) and still be consistent with the techniques described herein.

[0096] A scheduling interval may refer to a subframe, and / or a slot, and / or a frame, and / or a schedulable slice, and / or a control channel periodicity, and / or any other predefined time unit. Gaps, and / or guard periods, and / or silence periods, and / or switchover periods, and / or absence of transmission, and / or DTX periods may be used interchangeably.

[0097] The terms channel, beam, and / or channel beam may be used interchangeably. Antenna pattern, phase weight, steering vector, codebook, precoding, radiation pattern, beam pattern, beam, beamwidth, beamformed transmission, antenna port, virtual antenna port, transmission associated with a reference signal, directional transmission, and / or spatial channel may be used interchangeably.

[0098] The terms REG and CCE may generally refer to multiple time, frequency, code, and / or space resources and / or may not be or may not be limited by LTE number / context (e.g., LTE REG and LTE CCE may be considered types of REG and CCE in the context of the techniques described herein). A radiation pattern may refer to the angular distribution of a radiated electromagnetic field and / or the power level in a far-field region.

[0099] A beam can be one of the lobes, e.g., main / side / grating lobes, of the transmit radiation pattern and receive gain pattern of an antenna array. A beam can represent a spatial direction that can be represented using a beamforming weight vector. A beam can be identified using and / or associated with one or more of a reference signal, an antenna port, a beam identity (ID), and / or a scrambling sequence number, etc. A beam can transmit and / or receive at a particular time. A beam can transmit and / or receive at a particular frequency. A beam can transmit and / or receive with a particular code. A beam can transmit and / or receive with a particular spatial resource. A beam can be formed digitally and / or in an analog manner (hybrid beamforming). Analog beamforming can be based on a fixed codebook and / or continuous phase shifts. A beam can include omnidirectional and / or quasi-omnidirectional transmission. The two beams can be distinguished by the direction of highest radiated power and / or by the beam width.

[0100] The one or more reference signals may be associated with one or more search spaces and / or one or more antenna ports. The one or more search spaces may be associated with one or more beam search spaces and / or one or more antenna port search spaces.

[0101] In some scenarios, the WTRU may be configured to receive, possibly dynamically, one or more search spaces from a wireless communication system network node, hi some scenarios, the WTRU may be configured such that one or more search spaces are predefined on the WTRU.

[0102] A data channel beam may be used to transmit one or more of the following: a data channel, a data channel beam, a PDSCH, an mPDSCH, an mmW PDSCH, an mmW data channel, a directional PDSCH, a beamformed data channel, a spatial data channel, a data channel slice, and a high frequency data channel, etc. A data channel beam may be identified using and / or associated with one or more of the following: a reference signal, an antenna port, a beam identity (ID), a scrambling sequence number, and / or a data channel number, etc. A data channel beam may be transmitted and / or received at a particular time. A data channel beam may be transmitted and / or received at a particular frequency. A data channel beam may be transmitted and / or received with a particular code. A data channel beam may be transmitted and / or received on a particular spatial resource.

[0103] The control channel beam may be used to transmit one or more of the following: control channel, PDCCH, mPDCCH, mmW PDCCH, mmW control channel, directional PDCCH, beamformed control channel, spatial control channel, control channel slice, and high frequency control channel. The control channel may carry DCI for one or more users. The control channel may carry PHICH and PCFICH in the downlink and PUCCH in the uplink. The control channel beam may be identified with and / or associated with one or more of the following: reference signal, antenna port, beam identity (ID), scrambling sequence number, and control channel number. The control channel beam may be transmitted and / or received at a particular time. The control channel beam may be transmitted and / or received at a particular frequency. The control channel beam may be transmitted and / or received with a particular code. The control channel beam may be transmitted and / or received on a particular spatial resource. The control channel beam may be cell-specific and / or WTRU-specific.

[0104] A common channel may be used to refer to a transmission that carries information useful to multiple WTRUs. The term common channel may be used interchangeably with shared channel.

[0105] Half-power beamwidth (HPBW) may refer to the radiation pattern cut that includes the direction of the lobe maximum, the angle between two directions where the radiated intensity is half the maximum. The exact beamwidth for the beamformed control / data channel may or may not be specified and may depend on the mB and / or WTRU implementation. The mB may support WTRUs with different capabilities. The WTRU may function in the mB with different capabilities.

[0106] The control channel beam duration may be the number of OFDM symbols within a scheduling interval that is occupied by the control channel beam.

[0107] A control region may be the number of OFDM symbols within a scheduling interval that are occupied by some or all of the control channel beams transmitted within the scheduling interval.

[0108] Fixed codebook-based analog beamforming can refer to a grid of beams, which can include a set of fixed beams. A beam is a set of beamforming weight vectors v, v∈{v1, v2, v3...v} selected from a predefined codebook. N}, where N represents a fixed number of beams. The number of beams can depend on the half-power beamwidth (HPBW) of the beamforming and the desired coverage.

[0109] Continuous phase shift analog beamforming can provide continuous and adaptive beamforming to track channel conditions. The desired weights of the phase shifters can be calculated based on estimated channel information, e.g., angular information. The desired weights of the phase shifters can be converted using a high-resolution digital-to-analog converter (DAC) for application to the phase shifters.

[0110] Antenna ports can be defined. The channel on which a symbol on an antenna port is carried can be inferred from the channel on which another symbol on the same antenna port is carried. A time-frequency resource grid can be considered to be available per antenna port. For example, an antenna port (e.g., one or more or each) can be considered to be orthogonal to other antenna ports such that the time-frequency resources on the antenna port (e.g., one or more or each) can be used for independent transmissions. Code multiplexing can also be used on one or more antenna ports.

[0111] Beamforming includes building blocks. An exemplary subframe may have the following structure: A subframe, and / or a scheduling interval, and / or a slot, and / or a predefined time unit may include multiple symbols. One or more symbols may be used to transmit and / or carry and / or include and / or map one or more control signals / channels / information and / or may be configured to receive. One or more symbols may be configured to transmit / carry / include and / or receive one or more data channels.

[0112] The beamformed control and / or data channels may be one or more of the following: The control and / or data channels may be transmitted using a particular radiation pattern and / or beam. The control channel beam may be associated with one or more of the following: a unique reference signal, steering vector, scrambling code, antenna port, time, code, spatial resource, frequency resource, and / or control channel identity, etc. The data channel beam may be associated with one or more of the following: a unique reference signal, steering vector, scrambling code, antenna port, time, code, spatial resource, frequency resource, and / or control channel identity, etc. An mB and / or cell may transmit multiple beamformed control and / or data channels. The beamformed control and / or data channels may be multiplexed in time.

[0113] A data region may function with one or more beamformed data channels. One or more symbols in a subframe in which a data channel is transmitted may be referred to as a data region. Within a subframe, a data region may include multiple data channel beams multiplexed in time. For example, a data channel in a particular beam may occupy one or more symbols. The remaining symbols in the same subframe may be used to transmit data channels in other beams. The data channel beams in a data region may have variable beamwidths. The maximum data channel beamwidth for a WTRU may be as wide as its control channel beamwidth. The WTRU may receive the transmitted one or more data channels. The WTRU may use one or more beams and / or beamwidths within a subframe and / or across different subframes. Multiple WTRUs may be time multiplexed within the same data channel beam and / or across different data channel beams within a subframe. The smallest schedulable time resource within a subframe may be a symbol and / or a group of symbols. The scheduling granularity can be smaller than a subframe, e.g., the new DCI format can carry allocation information at the symbol level / symbol group.

[0114] The system may include a control region having one or more beamformed control channels. One or more symbols in a subframe in which a control channel is transmitted may be referred to as a cell-specific control region and / or an overall control region. Within a subframe, a cell-specific control region may include multiple control channel beams multiplexed in time. One or more symbols in a subframe in which a control channel for a particular beam is transmitted may be referred to as a beam-specific control region. The term control region may refer to a cell-specific control region and / or a beam-specific control region. The control region size may be fixed or flexible. The control region and the data region may overlap. One or more symbols may carry the control and / or data channels. The control and / or data channels may be multiplexed in the frequency and / or code and / or spatial domains.

[0115] The one or more search spaces may be configured to be used to monitor one or more downlink (DL) control channels. The one or more search spaces may be configured to be used to receive one or more DL control channels. At least one search space of the one or more search spaces may correspond to at least one reference signal of the one or more reference signals. At least a portion of a control region may be monitored for at least one reference signal of the one or more reference signals. At least one reference signal within at least a portion of a control region may be detected. Perhaps, for example, upon detection of the at least one reference signal, at least one search space corresponding to the at least one reference signal may be monitored for at least one DL control channel.

[0116] The system may include gaps and / or switching periods. The gaps, and / or guard periods, and / or silence periods, and / or switching periods, and / or absence of transmission, and / or DTX periods may be arranged between two consecutive symbols. The two consecutive symbols may carry transmissions with different beam directions, and / or radiation patterns, and / or steering vectors. Different gap types may be identified. Depending on the arrangement, one or more of the following examples may be identified: a gap between two control symbols and / or between groups of control symbols, a gap between two data symbols and / or between groups of data symbols, and / or a gap between a control symbol and a data symbol (e.g., between the last control symbol and the first data symbol, and / or between the first control symbol and the last data symbol), etc.

[0117] Different gap types can be preconfigured with different durations. The same gap type can be preconfigured with different durations in different subframes. A gap can be selectively placed between two consecutive symbols. The two consecutive symbols can be transmitted using different radiation patterns. The two consecutive symbols can be transmitted using different beam patterns. The two consecutive symbols can be transmitted using different directions. The two consecutive symbols can be transmitted using different channel types. A gap can be selectively placed between control symbols and data symbols. Gaps in the same subframe can have different durations. A gap may or may not be present in some or all of the subframes. A gap may or may not be placed between control symbols and not in data symbols. A gap may or may not be placed between data symbols and not in control symbols. Within the control and / or data region, a gap can be selectively placed between a subset of symbols.

[0118] A gap may be defined from the perspective of a WTRU. During a gap period (e.g., a gap between control symbols and data symbols for a WTRU), the WTRU may not or may not be required to receive on the DL. The WTRU may use the gap period to decode a control channel, e.g., a control channel received before the start of the gap period. The WTRU may use the gap period to switch its receive beam. The WTRU may use the gap period to apply a new steering vector to receive a downlink data channel, which may be different from the receive beam and / or steering vector used to receive the downlink control channel. The WTRU may use the gap period (e.g., a gap between data symbols and / or groups of data symbols for a WTRU) to switch its receive beam. The WTRU may use the gap period (e.g., a gap between data symbols and / or groups of data symbols for a WTRU) to apply a new steering vector to receive a downlink data channel, which may be different from the receive beam and / or steering vector used to receive a previous downlink data channel in a (e.g., same or different) subframe.

[0119] The mmW control channel can be designed, for example, to facilitate control channel beammapping to physical resources. One or more control channels in a cell can be beamformed. One or more control channels in a cell can be arranged in different control symbols and / or groups of control symbols within a subframe.

[0120] For example, the mB may utilize a sweeping operation to examine all or some of the control beams. The mB may transmit a control channel beam in a subframe, e.g., one or more or all control channel beams in every subframe. The mB may receive a control channel in a subframe. For example, the entire cell coverage may receive a control channel in every subframe. The mB may utilize a sweeping operation, e.g., starting with one control beam and examining some (e.g., one or more or all) of the control beams in the cell in a fixed order. The sweeping operation may examine selected symbols (e.g., only certain symbols) in the subframe (e.g., only in the control region). The mB may utilize multiple subframes to transmit all or some of the control channel beams. For example, a subframe may include a partial sweep of the control channel beam. One or more subframes may be used for a complete sweep of the control channel beam covering the entire cell. The mB may follow a fixed order for the sweeping operation. For example, it can transmit the control channel beams in an order based on the control channel number and / or the BRS sequence number. The mB can follow a random order for the sweep. The random order can be generated from a hash function. The hash function can use the control channel number and / or the subframe number, etc.

[0121] The mapping between the control channel beams and / or control symbols may be predefined and / or communicated via one or more of the following: broadcast channels (e.g., MIB, SIB-x), higher layer signaling (e.g., RRC / MAC), L1 signal / channel, and / or any other common channel, etc. The mapping between the control channel beams and the control symbol groups may be predefined and communicated via one or more of the following: broadcast channels (e.g., MIB, SIB-x), higher layer signaling (e.g., RRC / MAC), L1 signal / channel, and / or any other common channel, etc. The WTRU may determine the control channel beam-to-control symbol mapping by blind decoding. For example, the WTRU may search for predefined BRS sequences within the control region, and the WTRU may determine the control channel beam-to-symbol mapping based on, for example, the received BRS signal quality (e.g., RSRP, SNR, etc.).

[0122] The mB may select a subset of beams. The mB may transmit a subset of control channel beams in a subframe. The subset may be determined by one or more of the following criteria: distribution of WTRUs and / or beams in a cell, activity levels of WTRUs and / or beams in a cell (e.g., buffer status of WTRUs, traffic patterns for WTRUs), WTRU grouping, WTRU service requirements, number of control channels with or without beamforming, scheduling algorithm, intra-cell and inter-cell interference, and / or type of control channel (e.g., common control and / or WTRU-specific control), etc. The mB may transmit (e.g., only one) control channel beam in a subframe. A data region in a subframe may include transmissions using the same control channel beam and / or any other data channel beams associated with the control channel beam, e.g., narrow data channel beams associated with the control channel beam.

[0123] The mapping between the control channel beams and the symbols and / or symbol groups associated with a subframe (e.g., within and / or across subframes) can be fixed and / or flexible. Regardless of the control channel beam selection mode (e.g., subset transmission and / or full sweep transmission), the following can apply.

[0124] The mapping between the control channel beams and the symbols and / or symbol groups associated with a subframe, e.g., within and / or across subframes, may be fixed. In a fixed mapping, the control channel beams, e.g., all control channel beams, may be placed and / or transmitted within predefined symbols and / or symbol groups within a subframe. The mapping between the control channel beams and symbol numbers may be the same within a (e.g., one or more or all) subframe. For example, control channel beam 1 may be transmitted during symbol number 1 within (e.g., all) subframes. Symbol hopping may be used for the control channel beams according to a predefined hash function. For example, the function may use a control channel number, a cell ID, a BRS sequence ID, a subframe number, a symbol number, etc. The WTRU may determine the mapping between the control channel beams and symbols / symbol groups, e.g., implicitly based on the PBCH beam mapping. The WTRU may determine the mapping between the control channel beams and symbols / symbol groups based on an explicit configuration using one or more of the following: broadcast channels (e.g., MIB, SIB-x), higher layer signaling (e.g., RRC / MAC), and L1 signals / channels, etc. The WTRU may determine the mapping between the control channel beams and symbols / symbol groups based on a predefined function of a cell ID and / or beam ID. A many-to-one mapping between the control channel beams and the control symbols / symbol groups may be defined.

[0125] With a fixed mapping structure, control channel beams that do not have active WTRUs may have null and / or empty control symbols. The null and / or empty control symbols may be reclaimed and / or reused to map data channel beams, e.g., to improve resource utilization. The data channel beams may be scheduled by the control channel beams that occurred before the original null and / or empty symbols. The data channel beams may be scheduled by the control channel beams that occurred after the original null and / or empty symbols. The WTRU may buffer a complete subframe before completing control channel decoding. The PDSCH may be mapped to the reused (e.g., empty and / or empty) control symbols. The reused control symbols may precede the associated PDCCH.

[0126] The mapping between the control channel beam and the symbols and / or symbol groups associated with a subframe, e.g., within and / or across subframes, can be flexible. In flexible mapping, the control channel beam can be placed in and / or transmitted within (e.g., any) symbol and / or symbol group within a subframe. Multiple control channel beams within a subframe can be transmitted using different symbols, e.g., time multiplexed. The mapping between the control channel beam and the symbols / symbol groups can vary for different subframes. mB can selectively transmit a subset of the control channel beams within a subframe. The number of transmitted control channel beams can vary for different subframes. The number of control symbols occupied by the control channel beams can vary for different subframes. The number of control symbols occupied by different control channel beams within a subframe can vary.

[0127] The mapping between the control channel beams and the symbols and / or symbol groups associated with the subframes in the frame structure, e.g., within and / or across subframes, may be a hybrid of fixed and flexible mapping. The mB may use fixed mapping for some beam types (e.g., common control beams, and / or omni-directional beams, and / or WTRU-specific control beams). The mB may use flexible mapping for other beam types (e.g., WTRU-specific control beams, and / or common control beams, and / or omni-directional beams). The mB may use fixed mapping for some subframes and flexible mapping for other subframes. The mapping format for different subframes may be explicitly conveyed using one or more of the following: broadcast channels (e.g., MIB, SIB-x), higher layer signaling (e.g., RRC / MAC), and / or L1 signals / channels, etc. The mapping format for different subframes may be implicitly known by the presence of certain channels. For example, subframes with PBCH may use fixed mapping, flexible mapping may be the default mode, and fixed mapping may be applied within some (e.g., specific) subframes with a predefined periodicity.

[0128] For example, a fixed mapping between control channel beams RS and / or control symbols can assist WTRU measurements in a particular subframe. The mB can use fixed mapping for a subset of beams for WTRUs in idle mode and flexible mapping for WTRUs in connected mode. The mB can use fixed mapping for a subset of beams for WTRUs in connected mode and WTRUs in idle mode. The mB can use fixed mapping when the cell is lightly loaded (e.g., when the number of active WTRUs is small) and switch to flexible mapping when the cell becomes heavily loaded. The WTRU can determine the mapping format for the control channel beam from configuration received in one or more of the following: broadcast channels (e.g., MIB, SIB-x), higher layer signaling (e.g., RRC / MAC), L1 signal / channel, and / or any other common channel, etc. One or more WTRUs may determine a change / switch in control channel beam mapping from configuration received in one or more of the following: broadcast channels (e.g., MIB, SIB-x), higher layer signaling (e.g., RRC / MAC), and / or L1 signals / channels, and / or any other common channels, etc.

[0129] The mmW control channel beam may have various control channel beams. The mmW control channel beam may carry multiple control channels destined for one or more WTRUs. The control channel beam may carry one or more of the following: downlink control information (DCI) [e.g., DCI may include scheduling grants (UL and DL)], UL control channel allocation, beam switching commands, power control commands, and / or any other control information, higher layer messages (MAC, RRC), small payloads (e.g., broadcast messages such as SIB / paging), and / or cell-specific and / or beam-specific reference signals for demodulation, measurement for one or more WTRUs, etc. The minimum time domain resource occupied by the control channel beam may be one symbol. The maximum time domain resource occupied by the control channel beam may be pre-configured (e.g., in MIB / SIB-x) and / or dynamically conveyed using a beam-specific PCFICH. The dwell time of the control channel beam may be pre-configured (e.g., in MIB / SIB-x) and / or may be dynamically conveyed using a beam-specific PCFICH. The time domain resources (e.g., number of symbols) occupied by the common control channel beam may be fixed (e.g., in MIB / SIB-x). The WTRU-specific control channel beam may be dynamic (e.g., beam-specific PCFICH).

[0130] The mmW control beam may carry one or more PDCCHs. The PDCCHs may be destined for / to one or more WTRUs. The PDCCHs may be transmitted on an aggregation of one or more CCEs (control channel elements), e.g., a control channel element may correspond to two or more REGs (resource element groups). For example, different PDCCH formats may be defined based on the aggregation level of the CCEs. The PDCCHs may be transmitted, e.g., using a hierarchy of different groups of resource elements. The allocation number of basic resource units to the level of the resource group may be associated with a PDCCH link adaptation scheme and / or other considerations. One or more features / characteristics of the REs may be a function of the beam ID and / or beam type. One or more features / characteristics of the CCEs may be a function of the beam ID and / or beam type.

[0131] The common control channel beam and / or the WTRU-specific control channel beam may use different PDCCH formats and / or aggregation levels. There may be a fixed aggregation level on the WTRU-specific control channel beam. The number of REGs per CCE may vary for different beam types. For example, the common control channel beam may have a larger number of REGs per CCE. The resource block structure and / or subcarrier spacing may vary for different beam types. For example, the symbols carrying the common control channel beam and / or the symbols carrying the WTRU-specific control beam may use different subcarrier spacing. The common control channel beam may be scrambled by a cell-specific identity (e.g., cell ID) and / or a beam-specific identity (e.g., beam ID). The WTRU-specific control channel beam may be scrambled by one or more of the following: a cell-specific identity (e.g., cell ID), a beam-specific identity (e.g., beam ID), and / or a WTRU-specific identity (e.g., C-RNTI), etc. The one or more modulation schemes and / or coding rates used for the control channel beams may be beam type specific. For example, the common control channel may use a fixed and / or preconfigured modulation scheme and / or coding rate. The WTRU-specific control channel beam may use dynamic MCS adaptation. The dynamic MCS adaptation may be conveyed using the beam PCFICH. The beam type may be WTRU specific. For example, the WTRU may use a common control channel beam. The WTRU may use a WTRU-specific control channel beam. The WTRU may use a beam carrying common control channel scheduling information and / or WTRU-specific scheduling information. The portion of the subframe in which the common control channel beam is transmitted may be referred to as a common control region.The portion of a subframe in which a WTRU-specific control channel beam is transmitted may be referred to as a dedicated control region.

[0132] The following examples are subframe configurations illustrating control channel beam arrangements and / or resource structures. The illustrated example diagrams for different control channel arrangements are not exhaustive and / or other control channel arrangements can be used. The diagrams are not intended to be exhaustive, e.g., not all channels are depicted in the diagrams. For clarity and / or explanation purposes, the examples may be described with respect to DL subframes (e.g., only DL subframes are shown) and / or UL subframes may be ignored. One or more techniques described with respect to DL operation may be equally applicable to uplink operation. The wide transmit beams in mB may be referred to as B1, B2, B3, B4, etc. The narrow transmit beams may be referred to as B11, B12 (e.g., in B1), B21, B22 (e.g., in B2), etc.

[0133] In FIG. 12, mB may transmit one or more wide beam control channels per subframe. For example, subframe 1 may carry control channel beams B1 and / or B2, subframe 2 may carry control channel beam B3, etc. The (e.g., one or more or each) control channel beam may carry DCI for one or more WTRUs. The (e.g., one or more or each) control channel beam in a subframe may carry some unique content. For example, in (e.g., only one) control channel beam, a DCI for a WTRU (e.g., a specific DCI for a WTRU) may be carried. The control channel beams in a subframe may carry the same DCI content. The number of control channel beams per TTI may vary. For example, it may range from one control channel beam per TTI to the maximum available number of control channel beams in a cell. The length / duration of (e.g., one or more or each) control channel beam may vary (e.g., from one symbol to more symbols). A data region in a subframe may carry a PDSCH for one or more WTRUs, e.g., PDSCH transmissions for different WTRUs may be multiplexed in the time, frequency, and / or spatial domains. For example, within a data region, multiple PDSCH beams may be transmitted. The beamwidth of the data beam may be adjusted based on one or more of the following: WTRU location, throughput requirements, and / or interference considerations, etc. The mapping between the control channel beams and symbol numbers within the control region may be flexible. The WTRU may receive assistance information for the control channel configuration, e.g., from the PBCH and / or the omnidirectional PCFICH channel.

[0134] 13, the mB may transmit one (e.g., exactly one) wide beam control channel per subframe. For example, subframe 1 may carry control channel beams B1 and / or B2, subframe 2 may carry control channel beam B3, etc. The WTRU may be configured to monitor certain subframes (e.g., only certain subframes) for possible occurrences of a preselected control channel beam.

[0135] In FIG. 14, the mB may sweep some or all of the control channel beams in a subframe. For example, a (e.g., one or more or each) subframe may carry control channel beams B1, B2, B3, and / or B4. A (e.g., one or more or each) control channel beam may carry DCI for one or more WTRUs. WTRUs with lower SNR may have their DCI repeated in some (e.g., all) control channel beams. WTRUs with higher SNR may have their DCI transmitted in a subset of the control channel beams. The mapping between the control channel beams and the control symbols may be fixed. A BRS for the control channel beams (e.g., instead of and / or in addition to the control channel) may be swept.

[0136] In FIG. 15, for example, to reduce blind decoding attempts for the WTRU, a control channel beam to symbol mapping can be predefined. The WTRU can attempt to decode symbols (e.g., only symbols) carrying the preselected control channel beam. An mB may not be or cannot be occupied by, for example, a control channel beam in some control channel symbols. A data channel beam can be mapped / placed / transmitted in the control channel symbol. The WTRU can start buffering symbols for possible data channels, for example, until it decodes the preselected control channel beam in the appropriate control symbol.

[0137] In FIG. 16, for example, to reduce control overhead when the number of control channel beams becomes high in a cell, many-to-one mapping can be utilized for mapping from control channel beams to control symbols. In FIG. 16, B1 and / or B5 can be mapped to symbol 1. For example, when the assumption is that one RF chain can be for mB, B1 and / or B5 can be transmitted in control symbol 1. A WTRU having a B1 control channel beam can be used (e.g., required) to decode control symbol 1. For example, a hash function can be used to reduce the blocking probability of the control channel beam. The hash function can avoid mapping the same set of control channel beams to the same control symbol. The hash can be a function of one or more of the following: subframe number, system frame number, control channel beam ID, cell ID, and / or control symbol number, etc.

[0138] An example of a logical architecture for control channel beam generation is shown in Figure 17. Figure 17 shows an example of the relationship between different mapping / selection functions.

[0139] The mmW PDCCH may use heterogeneous beam types. For WTRU-specific control channels, wide beams may be configured and / or allocated for groups of users and / or for one or more or all users' control channels, e.g., PDCCHs that may carry user-specific DL control information (DCI). For WTRU-specific control channels, one or more narrow beams may be configured and / or allocated for individual WTRUs. For example, one or more beams may be configured such that a wide beam may be used to cover a cluster of WTRUs and / or a narrow beam may be used for an individual WTRU. Table 2 is an example of some allocations and / or configurations for heterogeneous beam types. For common control channels, wide beams may be used for individual WTRUs and / or WTRU groups. Narrow beams may be used for individual WTRUs (e.g., only individual WTRUs). For example, a narrow beam may be used as a WTRU-specific beam for common control, depending on the beam configuration. A wide beam (e.g., only wide beams) may be used for a group of WTRUs for common control. For a WTRU-specific control channel, a narrow beam may be used as a WTRU-specific beam for WTRU-specific control. A wide beam (e.g., only a wide beam) may be used for a group of WTRUs for WTRU-specific control.

[0140] [Table 2]

[0141] For example, a wide beam can be configured and / or used as a WTRU-specific beam for the control channel to enable easy tracking of the WTRU. The control channel can be a common control channel. The control channel can be a WTRU-specific control channel, e.g., a common DCI carried by the PDCCH and / or ePDCCH, etc. This can enable easy tracking of the WTRU. This can sometimes reduce beamforming gain. Easy tracking of the WTRU can be beneficial. Easy tracking of the WTRU can be beneficial when beamforming gain can be less of a concern. Beamforming gain can be less of a concern when the WTRU is close to the eNB and / or AP. For example, a narrow beam can be configured and / or used (e.g., only used) as a WTRU-specific beam for the control channel to enable high beamforming gain. For example, high beamforming gain can be beneficial when the WTRU is far away from the eNB and / or AP. For example, a high beamforming gain may be beneficial when the WTRU is near a cell edge. The control channel may be a common control channel and / or a WTRU-specific control channel. The WTRU-specific control channel may be a WTRU-specific DCI carried by the PDCCH and / or ePDCCH, etc.

[0142] To cover different WTRU densities (e.g., number of WTRUs in a given direction / area related to mB), beams with different beam widths can be used. The pairing of which beams with a certain width should cover which WTRU densities can depend on the density distribution of WTRUs in the terrain. For example, for high density areas, beams with narrower beam widths can be configured and / or used. For low density areas, beams with medium and / or larger beam widths can be configured and / or used.

[0143] For example, beams can be assigned to WTRUs such that the WTRU density per beam (e.g., the number of WTRUs in a beam) can be uniform and / or constant. This can, for example, facilitate the use of digital beamforming in analog beams to support a given number of active WTRUs. The number of analog beams can be reduced. For example, control overhead can be reduced when multiple control channels can be transmitted simultaneously in the same beam and / or frequency resource. A trade-off may occur between the number of OFDM symbols for control (e.g., for beam sweeping) and / or the number of OFDM symbols for data. Different compromises between overhead and throughput can be considered based on the particular deployment scenario.

[0144] For example, heterogeneous beam types having different beamwidths may be configured and / or used to improve flexibility of network operation and / or reduce control overhead.

[0145] The heterogeneous beam types may support one or more of the following: heterogeneous beam types with different beam widths for common and / or WTRU-specific channels, heterogeneous beam types with different beam widths for the same WTRU at different time steps, heterogeneous beam types with different beam widths for different WTRUs, and / or heterogeneous beam types with different beam widths for a group of WTRUs according to the WTRU's locations, etc. Heterogeneous beam types with different beam widths may be configured and / or used for common control and / or WTRU-specific control channels. Heterogeneous beam types with different beam widths may be configured and / or used for the same WTRU at different time steps. Heterogeneous beam types with different beam widths may be configured and / or used for different WTRUs at the same and / or different time steps. Heterogeneous beam types with different beam widths may be configured and / or used for a group of WTRUs, e.g., a group of WTRUs having various WTRU locations. Control overhead, e.g., the number of OFDM symbols for control relative to the number of OFDM symbols for data and / or the number of beams required for beam sweeping relative to the number of OFDM symbols for data, can be reduced.

[0146] For example, at (e.g., any) given time, when one RF chain and / or (e.g., one) beam is formed, one or more of the following beam configurations may be considered:

[0147] Beam sweeping can use homogenous beam types (e.g., homogenous wide beams). The (e.g., one or more or each) beam can have the same beam width covering 360 / N degrees, where N is the number of OFDM symbols for the control channel. For example, the (e.g., one or more or each) beam covers 120 degrees at a time when N=3. The beam sweeping cycle can cover 360 degrees. The homogenous beam type can be for a uniform angular distribution of WTRUs. The homogenous beam type may be less efficient for, for example, a non-uniform angular distribution of WTRUs.

[0148] Heterogeneous beam types can be efficient, for example, for non-uniform angular distribution of WTRUs. Beam sweeping can use heterogeneous beam types (e.g., heterogeneous wide beams). One or more or each beam can have different beam widths but still cover 360 / N degrees, where N is the number of OFDM symbols for the control channel. One or more or each beam can cover more or less than 120 degrees at a time, and / or a complete beam sweeping cycle covers 360 degrees. For example, if N=3, the beams can have beam widths of 60, 120, and / or 180 degrees. The eNB can keep the number of WTRUs per beam uniform and / or constant when it transmits a control channel to (e.g., one or more or each) WTRU. A uniform search space for the control channel can be maintained. The search space can avoid being over-utilized for some beams and / or under-utilized for other beams.

[0149] For example, when two or more RF chains are utilized for hybrid beamforming, the number of WTRUs per beam may be kept constant and / or approximately constant. Within a beam (e.g., one or more or each beam), the number of ranks for spatial multiplexing may be limited. Retaining the number of WTRUs under such ranks per beam may be performed to enable spatial multiplexing for future evolution.

[0150] Beam sweeping can use a narrow beam. The beam can have a narrow beam width and can cover a WTRU within N OFDM symbols for a control channel. For example, one or more or each beam can have a narrow beam width and can cover one or more or all WTRUs within N OFDM symbols for a control channel. One or more or each beam can cover one WTRU at a time, and a complete beam sweeping cycle can cover N WTRUs. For K WTRUs, when N≥K, one beam sweeping cycle can deliver a control channel to K WTRUs within a TTI. When N<K, one beam sweeping cycle cannot, or may not be able to, deliver one or more or all control channels to one or more or all of the K WTRUs within a TTI. To deliver a control channel to the remaining K - N WTRUs, another one and / or more TTIs can be used (e.g., as needed). How many TTIs can be used (e.g., as needed) for beam sweeping can depend on N and / or K. K / N beam sweeping cycles and / or TTIs can be needed to deliver one or more or all control channels to all K WTRUs. This example can also function when N≥K. This example may not be very efficient when N<K. For example, when the number of OFDM symbols for control increases, the overhead may increase. For example, when the number of users and / or K decreases, the number of WTRUs that can be supported may be limited. Beam sweeping may be performed over multiple TTIs, introducing latency (e.g., additional latency).

[0151] Beam sweeping can use different beam types (e.g., different wide / narrow beams). The beam can have a wide and / or narrow beamwidth and can cover the WTRU within N OFDM symbols for the control channel. For example, one or more or each beam can have one or more or each wide and / or narrow beamwidth and can cover one or more or all of the WTRUs within N OFDM symbols for the control channel. One or more or each beam can cover one or more WTRUs at a time, and a complete beam sweeping cycle can cover N WTRUs. For K WTRUs, when N≥K, one beam sweeping cycle can deliver the control channel to the K WTRUs within the TTI. When N<K, one beam sweeping cycle can deliver one or more or all of the control channels to one or more or all of the K WTRUs within the TTI. For example, N - 1 narrow beams can deliver control to N - 1 WTRUs and / or the last beam (wide beam) can deliver control to the remaining K - N + 1 WTRUs. It may or may not be necessary to use another one and / or more TTIs to deliver the control channel to the remaining K - N WTRUs. How many narrow beams and / or wide beams can be used (e.g., are needed) can depend on design considerations and / or N and / or K. The use of different beam types can reduce control overhead, reduce latency, and / or increase the number of WTRUs that can be supported.

[0152] Heterogeneous beams may be considered. Heterogeneous beams may be multiple beams associated with one or more different features and / or characteristics, e.g., beam width, transmit power, number of lobes, and / or number of active antenna elements. Beams with different beam widths and / or narrow beams may be used for the same cell and / or eNB. Narrow beams carrying control information and / or PDCCH may be used for individual WTRUs. Wide beams may be used for groups of control channels and / or PDCCHs. Heterogeneous beam types, e.g., wide and / or narrow beams, may be used. Heterogeneous beam widths may be used for wide beams. Different beam types and / or beam widths may be used, e.g., when beam sweeping is required. For example, for three beams, beams 1, 2, and / or 3 may have beam widths x, y, and / or z, respectively. For a uniform setting, beams 1, 2, and / or 3 may have beam widths x=y=z. For non-uniform settings, x, y, and / or z may not or cannot be equal to one another. Depending on the settings of x, y, and / or z, wide and / or narrow beams having different beam widths may be configured and / or formed.

[0153] To support beamforming reference signals (BRS), antenna ports can be designed to transmit BRS. Beam-specific antenna ports can be designed and / or assigned. Antenna ports can be designed for beams that can be used to transmit common control and / or WTRU-specific control information. Antenna ports can be associated with reference signals called BRS. BRS can be used to demodulate control channels. Antenna ports can be orthogonal to each other, e.g., in time, frequency, code, and / or any combination thereof, to avoid mutual interference between BRS. The design can use an even / odd pattern for BRS. Even and / or odd BRS can be assigned in different frequency and / or time grids. Even BRS (E-BRS) can be placed in the same frequency and / or time grid. Odd BRS (O-BRS) can be placed in the same frequency and / or time grid. E-BRS and / or O-BRS can be assigned in different resources, e.g., resources that are orthogonal to each other. For the control channel, a control beam RS (CBRS) may be used. An even CBRS (E-CBRS) may be arranged in the same frequency and / or time grid. An odd CBRS (O-CBRS) may be arranged in the same frequency and / or time grid. The E-CBRS and / or O-CBRS may be allocated in different resources, e.g., resources that are orthogonal to each other. For the data channel, a data BRS may be used.

[0154] In an even beam, an EAP can transmit E-CBRS for a control channel. In an odd beam, an OAP can transmit O-CBRS for control. The EAP and / or OAP can be in orthogonal resources. The E-CBRS and / or O-CBRS can be in orthogonal resources. Mutual interference between the EAP and / or OAP, or between the E-CBRS and / or O-CBRS can be avoided.

[0155] One or more (e.g., only one) BRS may be used (e.g., instead of and / or in addition to two BRSs (E-CBRS, O-CBRS)). For example, to make one BRS more efficient than other designs, (e.g., perfect) spatial separation may be achieved. The BRS and / or E-CBRS in the even beam may be active for a control channel. The BRS and / or O-CBRS in the odd beam may not be or may not be active for a control channel. The BRS and / or O-CBRS in the odd beam may be reused for data. The O-CBRS may be active for control, and / or the E-CBRS may not be or may not be active for control. The E-CBRS may be reused for data. For example, when perfect spatial separation may not or may not be achieved, the CBRS in the even and / or odd beams may not or may not be reused for data. The side lobes of the beams may be related to the spatial separation. For example, side lobes of the beams may prevent perfect spatial separation. When designing antenna ports for the BRS and / or CBRS, antenna patterns may be considered. When designing antenna ports for the BRS and / or CBRS, side lobes may be considered. Antenna port and / or BRS designs for data beams may be similar.

[0156] The spatial separation and / or resource reuse factor may be related to the efficiency of the channel design. For example, E-CBRS and / or O-CBRS may avoid mutual interference between them when the resource reuse factor for the two is considered. The resource reuse factor for the two may be considered efficient. For example, when perfect spatial separation is achievable, the resource reuse factor Q may be considered to be 1. For example, when perfect spatial separation is not or may not be achievable, the reuse factor Q may be set to be 2 or more. For example, for sequential beam sweeping for the control channel, the reuse factor may be set to be 1. For example, for parallel beam sweeping and / or transmission, the resource reuse factor may be set to be 2 or more. Parallel beam sweeping and / or transmission may occur, for example, when two or more beams transmitted in parallel sweep over K WTRUs simultaneously over N OFDM symbols for control. For example, when the spatial separation is not perfect, potential mutual interference between beams may occur during parallel beam transmission. The resource reuse factor can be set to be 2 or greater.

[0157] For multi-layer beamforming, for example, when the wide beam and / or narrow beam can coexist, some offset in the frequency / time grid can be applied to enable orthogonality between the BRS for the wide and / or narrow beam. For example, when they can (e.g., must) serve simultaneously and two (e.g., only two) beams are available and / or the two beams can include a wide beam and / or a narrow beam, the narrow beam can serve one WTRU in the WTRU group while the wide beam can serve the remaining WTRU in the WTRU group. The narrow beam and / or wide beam can overlap. The narrow beam and / or wide beam can use FDM to enable coexistence, for example, when no spatial separation occurs between them. BRS using FDM can be applied to the narrow beam and / or the wide beam.

[0158] One or more techniques associated with the BRS may be applied to the data BRS and / or the control BRS. The control channel may be decoded. For example, channel estimation may be performed via the CBRS to decode the control channel.

[0159] For example, in an even beam, energy detection can be used for channel estimation and / or control channel demodulation. For example, in an even beam, E-CBRS can be turned on and / or O-CBRS can be turned off. The beam index may not be decoded in advance. To decode the control channel, energy detection can be used to determine which antenna port is used for channel estimation.

[0160] For example, when even / odd BRS is used, channel estimation can be performed to decode the data channel. The beam index may already be decoded in the control channel. The even / odd beam index can be obtained by one or more of the following: In an even beam, for example, the even DBRS can be on and the odd DBRS can be off to avoid mutual interference between BRS at the beam edge. Energy detection can be used to determine which antenna port can be used for channel estimation. The same is true for odd beams. In an even beam, the even DBRS can be on and the odd DBRS can be on but can be used for data, and redundant data can be for control and / or carry some short control messages. Mutual interference between RS and / or data / etc. at the beam edge may occur. The same is true for odd beams.

[0161] The WTRU may not or may not rely on blind energy detection. Perhaps, for example, the WTRU may be able to decide between even / odd DBRS even if the WTRU may not or may not be able to detect the correct energy level. There may be an assumption that data demodulation can be performed after control channel decoding. In the control channel decoding, one or more beam indices may be obtained (e.g., have been obtained).

[0162] A (e.g., one or more or each) cell may have multiple PDCCH regions, e.g., one for one or more or each wide beam. A (e.g., one or more or each) PDCCH may carry beam-specific BRS sequences. BRS RE mapping in control channel symbols may be a function of PCI. BRS RE mapping in control channel symbols may be a function of beam index. The sequence carried in the BRS may be provided by an associated PBCH.

[0163] The WTRU may monitor the PDCCH. The WTRU may detect the BRS associated with the serving beam at the control symbol location. The control symbol location may be fixed. For example, when the control symbol location is not fixed and / or variable, the WTRU may perform the BRS detection operation at (e.g., one or more or all) control symbols defined by the cell PCFICH. For example, when the control symbol location may possibly not be fixed and / or may be variable, the WTRU may perform the BRS detection operation at a control symbol (e.g., only that control symbol) defined by the beam-specific PCFICH. The WTRU may compare the measured BRSRP with an implementation-dependent threshold. For example, when the BRSRP is greater than the threshold, the WTRU may perform PDCCH decoding. For example, the WTRU may assume that no DL / UL grant is received within the current TTI, unless perhaps a semi-static grant is configured.

[0164] A subframe structure and / or arrangement for the PDCCH BRS can be designed. For sequential beam sweeping, FIG. 18 can be an example subframe structure and / or arrangement for the control BRS. The resources can be shown in FIG. 18. The example subframe in FIG. 18 shows three control symbols followed by several data symbols. The beams can be swept over the three control symbols sequentially by the order of beams 1, 2, and / or 3 (e.g., B1, B2, and / or B3).

[0165] FIG. 19 may be an example resource allocation in two dimensions: frequency and / or time. The BRS may be used in (e.g., one or more or each) control symbol and / or may be uniformly (and / or non-uniformly) located across frequency. FIG. 19 shows that the BRS may have the same location in frequency across one or more or all control symbols. Other allocations may be used, e.g., the BRS may be at different locations in frequency across different control symbols. The BRS may use a staggered pattern and / or design.

[0166] FIG. 20 may be an example control BRS subframe structure and / or arrangement for parallel beam sweeping. Resources may also be shown in a block diagram. The example subframe in FIG. 20 shows three control symbols followed by several data symbols. One or more beams may be swept over the three control symbols sequentially by the order of beams 1&2, 3&4, and / or 5&6 (e.g., B1 / B2, B3 / B4, and / or B5 / B6). Parallel beams may be used in the control symbols. Two parallel beams may be used simultaneously in the control symbols. For example, a total of six beams may be swept over the three control symbols. The number of users covered by the control channel may be increased by using parallel beam transmission and / or sweeping. The capacity of the system may be increased.

[0167] FIG. 21 may be an example resource allocation in two dimensions, frequency and time. BRS may be used in control symbols and / or may be uniformly (and / or non-uniformly) placed across frequency. BRS may also be placed contiguously and / or non-contiguously. For example, O-BRS and / or E-BRS may be placed contiguously within an O-BRS / E-BRS pair. O-BRS / E-BRS pair may be placed uniformly and / or non-uniformly across frequency. O-BRS and / or E-BRS may be placed non-contiguously within an O-BRS / E-BRS pair. O-BRS / E-BRS pair may be placed uniformly and / or non-uniformly across frequency. An example may show that O-BRS / E-BRS pair has the same location in frequency across one or more or all control symbols. Other allocations may also be used, for example, when BRS may be at different locations in frequency across different control symbols. The BRS may use a staggered pattern and / or design.

[0168] The mmW PCFICH design may include, for example, a cell-specific control region and / or a beam-specific control region. In a subframe, one or more beamformed control channels may be transmitted during one or more control symbols time multiplexed within a control region. The overall control region size / length / duration may be a function of one or more of the following: the number of control channel beams selected for transmission, the number of control symbols occupied by the (e.g., one or more or each) control channel beam, a predefined maximum size / length / duration of a beam-specific control region, and / or a predefined maximum size / length / duration of a cell-specific control region, etc.

[0169] The number of control channel beams and / or the maximum number of control channel beams in a subframe may be fixed. The number of control channel beams may be less than or equal to the total number of control channel beams in a cell coverage. The number of control symbols may be a function of the number of control channel beams and / or the number of symbols per control channel beam. The number of control symbols and / or the maximum number of control symbols in a subframe may be fixed. The partial sweep function and / or the control channel beam subset selection function may select a control channel beam based on one or more of the following: the number of control symbols in a subframe and / or the number of control symbols per control channel beam, etc. The ratio of control symbols to data symbols may be configured to be less than or equal to a predefined value (e.g., a control overhead percentage). The number of control symbols per control channel beam may be a function of the number of WTRUs in the control channel beam and / or the type of control channel beam (e.g., a common control channel beam and / or a WTRU-specific control beam).

[0170] At least a portion of a control region may be part of multiple portions of a control region. The number of portions of a control region may be a function of the number of symbols configured for the control region. The number of portions of a control region may be a function of the number of symbols used for the control region.

[0171] A cell-specific control region configuration may be indicated. The WTRU may receive an indication and / or configuration of the cell-specific control region from a broadcast channel (e.g., MIB, SIB-x) and / or any other common channel. The configuration may be WTRU-specific. The configuration may be conveyed using dedicated signaling (e.g., MAC and / or RRC messages). A physical channel / signal (e.g., cell PCFICH) may be defined. The physical channel / signal may carry the configuration, for example, for the cell-specific control region. The new physical channel / signal may be placed in one or more predefined symbols in a subframe. The cell PCFICH may be transmitted using an omni-directional beam and / or a wide beam. The cell PCFICH may be transmitted using a narrow beam. The cell PCFICH may include two or more repetitions in a wide beam. The cell PCFICH may include two or more repetitions in a narrow beam. The WTRU may accumulate energy from the cell PCFICH repetitions to increase the SNR. The cell PCFICH may be repeated in different directions to provide coverage, e.g., when transmitted using wide and / or narrow beams. The cell PCFICH may be repeated with different beam widths to provide coverage, e.g., when transmitted using wide and / or narrow beams. The beam used for the cell PCFICH may be the same as the beam used for one or more of the synchronization channels (PSS and / or SSS and / or any other signal). The beam used for the cell PCFICH may be the same as the beam used for the PBCH. One or more WTRUs may determine the location of the cell PCFICH symbol by applying a predefined offset from a symbol carrying a PSS in the same beam.

[0172] The at least one DL control channel may be conveyed via one or more Orthogonal Frequency Division Multiplexing (OFDM) symbols. The one or more OFDM symbols on which the at least one DL control channel may be conveyed may be located within a control region. The WTRU may obtain the number of the one or more OFDM symbols in the control region via a Physical Control Format Indicator Channel (PCFICH). In some scenarios, the PCFICH may be obtained via a beam of a synchronization channel and / or via a beam of a Physical Broadcast Channel (PBCH).

[0173] The WTRU may determine the location of the cell PCFICH symbol by applying a predefined offset from a symbol carrying an SSS in the same beam. One or more WTRUs may determine the location of the cell PCFICH symbol by applying a predefined offset from a symbol carrying a PBCH in the same beam. When a time and / or frequency location of another channel / beam cell PCFICH may be included within a subframe (e.g., every subframe), a relationship (e.g., a predefined offset between two channels / beams) may be used to determine the time and / or frequency location of the channel / beam. When a time and / or frequency location of another channel / beam cell PCFICH may be included within n subframes and / or subframes (e.g., every nth subframe and / or every subframe), a relationship (e.g., a predefined offset between two channels / beams) may be used to determine the time and / or frequency location of the channel / beam. The cell PCFICH may be transmitted at a predefined location within a subframe, e.g., within the first few symbols of the subframe.

[0174] At least one search space corresponding to the at least one reference signal may be monitored for at least one data channel, possibly upon detection of the at least one reference signal, for example. The at least one search space may have a duration. A time location of the at least one data channel may be determined, possibly based on the at least one reference signal, or the duration, for example.

[0175] The cell-specific control region size can be fixed. The cell-specific control region size can indicate the maximum size / length / duration of the cell-specific control region. The cell-specific control region size can be semi-static. The cell-specific control region size can indicate the size / length / duration of the cell-specific control region for n subframes. n can be equal to or greater than the periodicity of the corresponding MIB / SIB-x and / or other common channels (e.g., any other common channels). The cell-specific control region size can be equal to or greater than the sum of the beam-specific control region sizes of a (e.g., one or more or all) control channel beams transmitted in that subframe. The cell-specific control region size can be equal to the product of the maximum beam-specific control region size and / or the maximum number of control channel beams in a subframe. The maximum beam-specific control region size and / or the maximum number of control channel beams in a subframe can be predefined in a standard. The maximum beam-specific control region size and / or the maximum number of control channel beams in a subframe can be configured in a common / broadcast channel. For example, when a cell-specific control region size is greater than or equal to the sum of beam-specific control region sizes of a (e.g., one or more or all) control channel beams transmitted in that subframe, one or more symbols in the control region may carry a data channel. The WTRU may receive two or more configurations for the cell-specific control region. For example, one configuration may apply for subframes with flexible mapping. One configuration may apply for subframes with fixed mapping.

[0176] One or more WTRUs may receive a configuration for flexible mapping (e.g., only for flexible mapping) and / or the WTRU may apply a predefined configuration (e.g., fixed length and / or maximum length for cell-specific control region) to the fixed mapping. The configuration may be applied to the common control channel and / or the configuration may be applied to the WTRU-specific control channel. The cell-specific control region configuration, e.g., cell PCFICH, may be dynamic. The cell-specific control region configuration, e.g., cell PCFICH, may vary every (e.g., every) subframe. The cell PCFICH may indicate the presence of a common control region in a subframe. The cell PCFICH may indicate the end and / or start of a common control region in a subframe. The WTRU may assume that the remainder of the control region not occupied by the common control region may be a dedicated control region.

[0177] The cell-specific control region configuration may have content. The configuration may include and / or identify the size / duration / length of the cell-specific control region. The length may be expressed in one or more of the following: subframes, time slots, and / or number of OFDM symbols, etc. One or more WTRUs may assume the start of the cell-specific control region to be the first symbol in a subframe. The WTRU may receive an explicit indication of the first and / or last symbol of the cell-specific control region. The values ​​transmitted in the cell-specific control region configuration may be logical values. The values ​​transmitted in the cell-specific control region configuration may have a predefined mapping to the actual duration / length / duration of the cell-specific control region. The WTRU may use the indication of the cell-specific control region configuration to calculate and / or determine the end of the cell-specific control region. The WTRU may use the indication of the cell-specific control region configuration to calculate and / or determine the start of the data region. The configuration may include / identify the number of control channel beams to be transmitted in a subframe (e.g., in the current subframe and / or in n subsequent subframes and / or in some or all subframes). The configuration may include / identify the type of mapping (e.g., fixed and / or flexible mapping) to be applied to the control channel beams. The configuration may include beam identification information (e.g., RS sequence ID, antenna port number, and / or control channel number) of a (e.g., one or more or all) control channel beams to be transmitted in the subframe. The subframes may be the current subframe, the n subsequent subframes, and / or a (e.g., one or more or all) subframes.

[0178] A beam-specific control region configuration may be indicated. One or more WTRUs may receive an indication and / or configuration for a beam-specific control region size from a broadcast channel (e.g., MIB, SIB-x). The WTRU may receive an indication and / or configuration for a beam-specific control region size from any other common channel / signal. The beam-specific control region size / length / duration may be predefined as a constant value. The constant value may be treated as a maximum value. Different beams in a cell may have different beam-specific control region configurations. The beam-specific control region size / length / duration may be semi-static. The beam-specific control region configuration may vary for different beams in a cell. For example, a common control channel beam may have a different configuration than the configuration for a WTRU-specific control channel beam. The beam-specific control region configuration for the common control channel may be fixed and / or semi-static. The beam-specific control region configuration for the WTRU-specific control channel beam may be dynamic.

[0179] The configuration can be WTRU-specific and / or beam-specific. The configuration can be conveyed using dedicated signaling (e.g., MAC and / or RRC messages). In the absence of dedicated signaling, the WTRU can apply the configuration in the MIB / SIB-x and / or predefined values. A physical channel / signal (e.g., beam PCFICH) can be defined. The physical channel / signal can carry configuration for beam-specific control regions. A cell and / or mB can transmit multiple beam PCFICHs in the same subframe. The beam PCFICH can be transmitted with a particular beam pattern and / or beam width. The beam PCFICH can carry a corresponding beam-specific control region configuration. The beam-specific control region configuration for a particular beam can vary across subframes. The beam PCFICH for a beam in a subframe can be conditionally transmitted based on the presence of a corresponding control channel beam (e.g., a beam with similar properties and / or characteristics) in that subframe. The beam PCFICH transmission can be combined with the control channel beam transmission. The control channel and / or beam PCFICH can be transmitted, for example, within the beam dwell time. The beam used for the beam PCFICH can be the same as the corresponding control channel for which configuration can be provided / conveyed. The beam PCFICH can be time multiplexed (e.g., different symbols and / or the first few symbols in the PDCCH). The beam PCFICH can be frequency multiplexed with the control channel transmission (e.g., CCE, RE, and / or RB).

[0180] The mB may transmit a (e.g., one or more or all) beam PCFICHs and / or may transmit the control channel beams in a certain order. The mB may multiplex the beam PCFICHs and / or the cell PCFICHs and / or the control channels, for example, when the cell PCFICHs are transmitted with wide and / or narrow beams. The mB may multiplex the beam PCFICHs and / or the cell PCFICHs and / or the control channels, for example, when the cell PCFICHs are transmitted with wide and / or narrow beams. The beam PCFICHs may carry cell-specific configurations and / or beam-specific control region configurations. The beam PCFICHs may be transmitted with a beam pattern that is different from the beam pattern used by the control channel beam. The (e.g., one) beam PCFICH may carry configurations for multiple control channel beams. The WTRU may determine the presence of a beam PCFICH. For example, the WTRU may determine the presence of a beam PCFICH, indicated by a bit and / or a bitmap in the cell PCFICH. The WTRU may determine the presence of a beam PCFICH, as indicated by a bit and / or a bitmap for (eg, one or more or each) control beam in the cell PCFICH.

[0181] The beam-specific control region configuration may have content. The WTRU may determine the beam-specific search space from the beam-specific control region configuration. The beam-specific control region configuration may include one or more of the following: a (e.g., single) beam-specific control region size common to a (e.g., one or more or all) beams, a separate beam-specific control region size for each (e.g., one or more or each) beam, and / or a beam-specific control region size as a group of beams with similar control region sizes, etc. The configuration may include and / or identify the length of the beam-specific control region size / duration / period. The size may be expressed in one or more of the following: subframes, time slots, and / or number of OFDM symbols, etc. One or more WTRUs may receive an explicit indication of the first and / or last symbol of the beam-specific control region. The values ​​transmitted in the beam-specific control region configuration may be logical values. The values ​​transmitted in the beam-specific control region configuration may have a predefined mapping to the actual duration / length / period of the beam-specific control region. The WTRU may use the indication of the beam-specific control region configuration to, for example, calculate and / or determine the end of the beam-specific control region. The WTRU may use the indication of the beam-specific control region configuration to, for example, calculate and / or determine the start of the data region.

[0182] The configuration may include / identify the number of control symbols carrying a corresponding control channel beam in a subframe (e.g., in the current subframe and / or in n consecutive subframes and / or in a (e.g., in one or more or all subframes)). The configuration may include / identify the type of mapping (e.g., fixed and / or flexible) applied to the control channel beam. The configuration may also include beam identification information (e.g., RS sequence ID, and / or antenna port number, and / or control channel number) of the corresponding control channel beam transmitted in a subframe (e.g., in the current subframe and / or in n consecutive subframes and / or in all subframes).

[0183] WTRU monitoring may be performed in idle mode. The monitoring may select a common control channel beam. The WTRU may not or may not be involved in active data transfer (e.g., in idle mode). For example, the WTRU may be in idle mode when selecting one or more common control channel beams to perform monitoring. The WTRU may monitor one or more common control channel beams. The WTRU may monitor one or more common control channel beams to receive system information. The WTRU may monitor one or more common control channel beams to page messages. The WTRU may monitor one or more common control channel beams to perform coarse beam tracking / beamforming. The WTRU may monitor one or more common control channel beams to receive beam training. The WTRU may select one or more common control channel beams for monitoring. The WTRU may perform measurements on the beamformed RS. The RS may not or may not be multiplexed with the common control channel beam for beam evaluation purposes. The common control channel beams may be detected / measured / identified by a reference signal that is different from the WTRU-specific beam. Some (eg, one or more or all) common control channel beams may be associated with the same reference signal, which may be cell-specific.

[0184] The (e.g., one or more or each) common control channel beam may be associated with a different reference signal sequence. The WTRU may select a (e.g., one or more or all) common control channel beam. The WTRU may select a common control channel beam for which a measured signal quality (e.g., RSRP, SNR, SINR, RSRQ, etc.) may be above a threshold. The WTRU may select a (e.g., best) beam based on the measured signal quality for monitoring purposes. The WTRU may perform signal quality measurements on a limited set of subframes, e.g., on subframes in which the PBCH and / or synchronization channel may be transmitted. The WTRU may perform signal quality measurements on subframes in which there is a fixed and / or predefined mapping between the control channel beams and / or control symbols, for example.

[0185] A WTRU may receive an explicit and / or implicit relationship between synchronization beams and / or control channel beams using disparate control channel beams. One or more WTRUs may receive an explicit and / or implicit relationship between PBCH beams and / or control channel beams using disparate control channel beams. A cell selection and / or reselection of a WTRU may be based on a PBCH beam. A cell selection and / or reselection of one or more WTRUs may be based on a synchronization beam. A WTRU may select a type of control channel beam based on an associated serving PBCH to perform monitoring herein. A WTRU may select a type of control channel beam based on an associated serving synchronization beam type to perform monitoring herein. For example, a preconfigured offset may be defined between PBCH / synchronization beams and / or corresponding control channels on the same beam. The offset may be in terms of time (e.g., subframe, symbol) and / or frequency.

[0186] One or more WTRUs may determine the presence of a control channel beam by searching the PBCH on the same beam, e.g., at a preconfigured location in the frame structure. The WTRU may detect the presence of a beam type using a beam-specific reference signal. The beam-specific reference signal may be defined as a function of a cell ID. One or more WTRUs may determine the cell ID from a discovery signal and / or the number of beams in the cell via the PBCH. The WTRU may determine the cell ID from a set of beam reference signals associated with the cell. The beam reference signals may be associated with a cell by a predefined function of the cell ID and / or the number of beams. The beam-specific reference signals may identify a beam type and / or a beam. The WTRU may monitor control channel beams associated with (e.g., belonging to) a current serving PBCH beam type and / or a beam narrower than the detected PBCH beam type.

[0187] The common control channel beams may have a search space. A control region in the (e.g., one or more or each) serving cell and / or mB may include one or more control symbols carrying one or more control channel beams. A control region of the (e.g., one or more or each) control channel beam may include one or more symbols, where the number of symbols may be fixed and / or variable. A control region of the (e.g., one or more or each) control channel beam may include one or more symbols, where the symbols and / or symbol groups (e.g., the exact symbols and / or symbol groups) may depend on a mapping function. The common search space may be a function of one or more of the following: the number of common control channel beams transmitted by the mB, the number of common control channels selected by the WTRU, the beam-specific control region size / duration, the overall control region duration, the cell bandwidth, and / or the aggregation level, etc. Within the symbols used for the common control channel beam, a frequency domain mapping can be explicitly provided for the PDCCH candidates that are mapped to, for example, n carriers around a center frequency, even / odd RBs, a hash function, and / or any other pattern for the control channel. A common search space with beamformed control channels can be defined as a set of PDCCH candidates on one or more common control channel beams, for example, as determined by a control channel beam selection function. On a control channel beam, one or more WTRUs can monitor corresponding beam-specific control regions for a set of PDCCH candidates defined by one or more aggregation levels.

[0188] FIG. 22 is an example of a common control channel beam and / or associated search space. The WTRU may perform monitoring. The WTRU may monitor the common search space in idle mode. The WTRU may perform monitoring on a set of predefined subframes, for example, when mapping between common control channel beams is known and / or can be configured in terms of control channel beam ID and / or symbol mapping. The WTRU may search certain subframes (e.g., all subframes and / or preconfigured subframes) for the presence of a common control channel beam at a symbol location within the control region. The WTRU may search the subframes by correlating known reference signal sequences (e.g., signal sequences that may be cell-specific and / or beam-specific). Different reference signal sequences may be defined for the common control channel beam and / or the WTRU-specific control channel beam. A beam (e.g., one or more or each) may possibly have its own reference signal sequence within the common control channel beam. Within the common control channel beam, one or more beams (e.g., all beams) may use a cell-specific sequence. The WTRU may monitor a common search space within a beam-specific control region, for example, when the received reference signal power may be above a threshold. The reference signal sequence may be cell-specific. Some or all of the common control channel beams in a cell may carry the same information. The WTRU may accumulate the energy received from some or all of the common control channels to increase the SNR.

[0189] A WTRU may perform monitoring in connected mode. A WTRU may perform monitoring in connected mode by allocating a control channel beam. A WTRU may monitor one or more control channel beams to receive control information in connected mode. The control channel beam may be a WTRU-specific control channel beam and / or a cell-specific common control channel beam. A set of control channel beams that a WTRU may monitor may be referred to as serving control channel beams. One or more WTRUs may be allocated one or more serving control channel beams. A WTRU may consider some or all control channel beams from an mB as serving control channels. A WTRU may consider a control channel beam selected during idle mode operation as a WTRU-specific control channel beam, for example, for connected mode operation. A WTRU may receive a serving control channel beam configuration using dedicated signaling (e.g., L1, and / or MAC, and / or RRC messages). One or more WTRUs may monitor one or more serving control channels in connected mode for one or more of the following: UL and / or DL ​​grants, beam switching commands, handover commands, higher layer messages, and / or small payloads, and / or any other control information. One or more WTRUs may distinguish common control channel beams from WTRU-specific control channel beams by the presence of predefined beam reference signals.

[0190] The WTRU may monitor a cell-specific common control channel beam to receive common channels (e.g., paging and / or SIBs) during connected mode. The WTRU may autonomously select a common control channel beam. The WTRU may select a common control channel beam based on dedicated signaling (e.g., L1, and / or MAC, and / or RRC messages) received in the serving control channel. The WTRU may monitor the serving control channel beam for common channels (e.g., paging and / or SIBs). One or more WTRUs may select a common control channel beam that is implicitly and / or explicitly related to the current serving control channel beam.

[0191] The WTRU may have a beam-specific search space. A control region in a serving cell and / or mB may include one or more control symbols. A control symbol may carry one or more control channel beams. A control region of (e.g., one or more or each) control channel beam may include one or more symbols. For example, the number of symbols may be fixed and / or variable. The exact symbols and / or symbol groups may depend on a mapping function.

[0192] The WTRU-specific search space may be a function of one or more of the following: number of control channel beams transmitted by an mB, number of control channels selected by and / or allocated to the WTRU, beam-specific control region size / duration, overall control region duration, cell bandwidth, aggregation level, WTRU ID, subframe number, and / or subframe, etc. The WTRU-specific search space may be defined as the union of beam-specific search spaces of certain serving control channel beams selected by / allocated to the WTRU. The beam-specific search space may be defined as a set of PDCCH candidates within a beam-specific control region. A beam-specific control region may be defined as one or more control symbols and / or symbol groups used to transmit and / or mapped to a corresponding beam. The number of symbols per control channel beam may be static, semi-static, and / or dynamic. On a serving control channel beam (e.g., one or more or each), the WTRU may monitor the corresponding beam-specific control region for a set of PDCCH candidates defined by one or more aggregation levels. Within a symbol used for a control channel beam, frequency domain mappings and / or restrictions can be explicitly and / or implicitly defined for PDCCH candidates (e.g., mapped to n carriers around a center frequency, and / or even / odd RBs, and / or hash functions, and / or any other pattern). A WTRU can be configured with different sets of aggregation levels for different control channel beams. A WTRU-specific search space within a beam can be a function of beam ID, WTRU ID, symbol number, subframe number, etc.

[0193] FIG. 23 is an example of a WTRU beam-specific search space. The WTRU may perform monitoring. In connected mode, the WTRU may monitor their WTRU-specific search space. In connected mode, the WTRU may monitor a common search space. The WTRU may perform conditional monitoring, for example, based on the presence of one or more serving control channel beams. One or more WTRUs may search a subframe and / or one or more preconfigured subframes for the presence of a WTRU-specific control channel beam by correlating one or more of the following: preconfigured beam-specific reference signal sequences, cell-specific reference signal sequences, and / or beam-type-specific reference signal sequences in a control region, etc. One or more WTRUs may be configured with a mapping between control channel beams and control symbol locations. The WTRU may search (e.g., only) the configured control channel beam in (e.g., one or more or each) symbol location. The WTRU may monitor PDCCH candidates in a detected beam-specific search space, for example, when the received reference signal power may be above a threshold.

[0194] A WTRU may monitor a beam-specific search space in some or all subframes and / or in configured subframes in which it may transmit one or more serving control channel beams. A WTRU may monitor a common search space in all or some of the subframes or in configured subframes in which it may transmit one or more common control channel beams. For example, a control region in a preconfigured subframe may include one or more (e.g., two) portions, e.g., one for a common control channel beam and / or another for a WTRU-specific control channel beam. One or more WTRUs may monitor a common search space in a common control region and / or a WTRU-specific and / or beam-specific search space in a dedicated control region.

[0195] The WTRU may perform monitoring using one or more techniques as described herein. The WTRU may determine a WTRU-specific control channel beam and / or a common control channel beam by doing one or more of the following: The WTRU-specific control channel beam may be configured by the mB. The WTRU-specific control channel beam may be selected during cell selection. The WTRU-specific control channel beam may be selected autonomously by the WTRU and / or indicated to the mB during a random access procedure. The common control channel beam may be selected autonomously by the WTRU (e.g., relationship to a PBCH / sync beam). The common control channel beam may be selected by the WTRU implicitly associated with the current serving control channel beam (e.g., many-to-one mapping between WTRU-specific and common control channel beams). The mB may override the common control channel beam for the WTRU in connected mode.

[0196] The WTRU may determine which subframes to monitor based on a beam mapping capability through one or more of the following: The WTRU may be pre-configured (in MIB / SIB-x and / or dedicated signaling) with beam-to-subframe mapping. The WTRU may monitor, for example, one or more serving control channel beams and / or common control channel beams (e.g., only those subframes) if those subframes can be transmitted. The WTRU upon waking up from DRX mode may monitor, for example, those subframes (e.g., only those subframes) if a fixed mapping to a serving control beam can be pre-configured. The WTRU may assume and / or configure a flexible mapping, for example, any-to-any mapping between beams and subframes, where a (e.g., one or more or each) subframe includes multiple control channel beams. One or more WTRUs may monitor a (e.g., one or more or all) DL subframes for a serving control channel beam and / or a common control channel beam. Upon waking up from DRX mode and / or receiving a valid allocation, the WTRU may continue to monitor a (e.g., one or more or all) subframes for a serving control channel beam. The WTRU may monitor a particular subframe for a common control channel beam and / or a (e.g., one or more or all) subframes for a WTRU-specific control channel beam.

[0197] The WTRU can determine the overall control region in a subframe. The WTRU can determine the overall control region size / duration in a subframe from the MIB / SIB-x. The WTRU can determine the overall control region size / duration in a subframe from fixed parameters. The WTRU can determine the overall control region size / duration in a subframe that is dynamically signaled via the cell PCFICH.

[0198] The WTRU may determine the beam-specific search space by one or more of the following: Within an overall control region, the WTRU may assume one or more beam-specific control regions. For (e.g., one or more or each) monitored control channel beams, the WTRU may determine (e.g., initially determine) the presence of those control beams and / or the starting symbol for the control channel beams by explicit signaling in the cell PCFICH. For (e.g., one or more or each) monitored control channel beams, the WTRU may determine the presence of those control beams and / or the starting symbol for the control channel beams by detecting a beam-specific BRS above a threshold. For (e.g., one or more or all) monitored control channel beams, the WTRU may perform blind decoding, e.g., when a cell-specific BRS is used. The WTRU may assume, e.g., that no DCI is received in that subframe when the BRS for a (e.g., one or more or all) serving control channel beams is below a threshold. The WTRU may identify the beam based on a beam-specific preamble that is added to the (e.g., one or more or each) control symbol carrying the beam. The preamble may be a function of one or more of the following: beam ID, cell ID, and / or WTRU ID, etc.

[0199] One or more WTRUs may utilize BRS-based measurements to determine the characteristics / characteristics of the control channel beam, e.g., the presence of a particular control channel type and / or beam, the length of the control channel beam, etc. For a (e.g., one or more or all) detected control channel beams, the WTRU may determine the beam-specific control region size / duration and / or the last symbol in the beam-specific control region from the MIB / SIB-x. For a (e.g., one or more or all) detected control channel beams, the WTRU may determine the beam-specific control region size / duration and / or the last symbol in the beam-specific control region from fixed parameters. For a (e.g., one or more or all) detected control channel beams, the WTRU may determine the beam-specific control region size / duration and / or the last symbol in the beam-specific control region may be dynamically conveyed via the beam PCFICH. One or more WTRUs may be provided (e.g., explicitly) with a fixed mapping between the control channel beams and the symbol locations of the beam-specific control regions. One or more WTRUs may be provided (e.g., explicitly) with a fixed mapping between control channel beams and beam-specific control region sizes / durations. The overall control region may be divided into common control regions and / or dedicated control regions.

[0200] Within the (e.g., one or more or each) detected beam-specific control region, one or more WTRUs may do one or more of the following: The WTRU may apply frequency and / or time domain restrictions (e.g., remove the center n carriers, and / or specific RBs, and / or any other pattern, and / or non-PDCCH channels (e.g., PHICH, beam PCICH, sync / PBCH), if present). Within the beam-specific search space, several (e.g., additional) WTRU-specific search spaces may be configured. For example, the starting CCE may be different for different WTRUs (e.g., based on WTRU ID, beam type, beam ID, subframe number, symbol number, etc.). The WTRU may group REGs within the (e.g., one or more or each) beam-specific control region into one set of CCEs. Within the (e.g., one or more or each) set of CCEs, the WTRU may monitor one or more PDCCH candidates based on the (e.g., one or more or each) beam type and / or aggregation level configured for the beam. The DCI CRC may be scrambled with the beam ID in addition to the WTRU ID (e.g., CRNTI) and / or common ID (e.g., SI_RNTI and / or Paging RNTI). For WTRU-specific control channel beams, the WTRU-specific search space may be simplified (e.g., further simplified) by pre-configuring a fixed starting CCE, an explicit indication of the aggregation level to be used, etc.

[0201] DL data may perform scheduling. When the WTRU detects a PDCCH in some (e.g., at least one) of the serving control channel beams, it may indicate a DL grant for data, and / or some other (e.g., any) higher layer information, addressed to the WTRU. The WTRU may attempt to decode the corresponding data channel beam in the resources indicated by the DCI. The WTRU may assume that it can use the serving control channel beam for data transmission, for example, when no data beam specific identity is included in the DCI message. The WTRU may assume, for example, the last indicated data channel beam, when no data beam specific identity is included in the DCI message. The WTRU may assume, for example, the data channel indicated by the higher layer configuration, when no data beam specific identity is included in the DCI message. The scrambling initialization of the PDSCH may be a function of one or more of the following: the control channel beam ID carrying the allocation, the beam ID of the DL data channel beam, a WTRU-specific RNTI (e.g., C-RNTI and / or SPS-RNTI), a fixed RNTI (e.g., SI-RNTI and / or paging RNTI), and / or the beam type, etc.

[0202] Sub-subframe scheduling can perform resource allocation by allowing multiple allocations within a subframe. Beamforming can be used (e.g., required) to compensate for additional path loss at higher frequencies. Given the large bandwidth at higher frequencies and / or analog beamforming, one or more WTRUs can be multiplexed using different beams within a subframe and / or scheduling interval. One or more control channels can be transmitted using a wide beam. A (e.g., one or more or each) control channel beam can schedule one or more narrow data beams for one or more WTRUs in the same subframe.

[0203] The smallest schedulable time resource within a subframe may be a symbol and / or a group of symbols. The scheduling granularity may be smaller than a subframe and / or a scheduling interval. New (e.g., new and / or previously unused) DCI formats may be defined to carry allocation information at the symbol level / symbol group, for example, to indicate starting offsets (e.g., symbol offsets), recurring information (e.g., more than one data channel per WTRU per subframe), and / or spatial information (e.g., transmit beam ID), etc.

[0204] Within a subframe, a data region may include multiple data channel beams multiplexed in time. For example, a data channel may occupy some symbols and / or the remaining symbols within the same subframe may be used by other data channel beams destined for the same and / or different WTRUs. A WTRU may be assigned multiple data channel resources within the same subframe. A (e.g., one or more or each) set of data channel resources may be associated with a different data beam.

[0205] A downlink data beam that the mB can use for the WTRU may be identified. The WTRU may use a receive beam pattern for downlink data channel reception. The WTRU may use a different receive beam pattern for downlink control channel beam reception compared to the receive beam pattern used for downlink data channel beam reception. The mB may include a transmit beam ID corresponding to the data channel beam to enable the WTRU to switch the receive beam accordingly. One or more WTRUs may use (e.g., require) gaps and / or decoding periods between PDCCHs carrying grants and / or actual data channel resources. The data beam may be the same as a WTRU-specific control channel beam, so that, for example, when a WTRU-specific control channel beam is used, the transmit beam ID may be implicitly determined by the WTRU.

[0206] The data channel beam information can be combined with the resource allocation information. For example, the DCI can include a transmit beam identification in the PDCCH, which carries the resource allocation in terms of time (e.g., symbols, symbol groups) and / or frequency (e.g., RBs). The mB can explicitly provide a gap and / or a guard period between the last symbol of the PDCCH and the first symbol of the PDSCH in the same subframe. The guard period can be defined from the perspective of the WTRU. The mB can use the symbols in the guard period to schedule other WTRUs. The WTRU can assume (e.g., always assume) an offset between the PDCCH and the PDSCH. For example, the PDCCH in subframe n can allocate the PDSCH in subframe n+k. The value of k can be dynamic and / or configured by higher layer signaling (MAC and / or RRC) and / or included in the DCI message and / or can be a predefined constant. The WTRU can assume k=0 to buffer data in the current subframe. Depending on the value of k in the DCI, the WTRU may determine the PDSCH location in the current subframe (if k=0 and / or is not included in the DCI) and / or in subframe n+k (if k is included in the DCI).

[0207] The at least one search space may include downlink control information (DCI). Perhaps, for example, at least one data channel may be monitored based at least in part on the DCI. Perhaps, for example, at least one beam may be identified for reception of the at least one data channel based at least in part on the DCI.

[0208] The data channel beam information and / or spatial information can be independent of the resource allocation (e.g., time / frequency, code) information. The spatial information (e.g., data channel transmission beam identification information) can be derived from a beam-specific reference signal for the corresponding DL beam. The spatial information can be derived from a beam-specific reference signal for the corresponding antenna port. The spatial information can be derived from a beam-specific reference signal for the corresponding steering vector and / or codebook index. The spatial information can be conveyed using an RRC configuration / MAC CE / DCI that is separate from the time and / or frequency resource allocation information. The spatial information can be acknowledged by the WTRU to prevent mismatch between the mB and the WTRU before the actual data transmission on the indicated data channel beam. The spatial information and / or resource allocation information (e.g., time and / or frequency) can have a predefined and / or configured offset with respect to the assigned resources. The spatial information can be associated with a validity period and / or expiration time of the validity period. The WTRU may perform (e.g., be required to perform) one or more of beam measurements, and / or beam tracking, and / or beam reporting (e.g., CSI).

[0209] Common channels may be scheduled using separate spatial information. WTRU-specific channels may be scheduled using combined spatial information. Common channels may be scheduled using combined spatial information. WTRU-specific channels may be scheduled using separate spatial information. Different WTRUs in the same cell may receive scheduling information using different configurations (e.g., combined and / or separate).

[0210] The DCI may have a format and / or content. The downlink control information for a DL data channel grant may include one or more of the following: spatial information, time resource information, and / or frequency resource information, etc. The spatial information may include one or more of the following: an implicit data channel beam identity (e.g., an associated data channel RS sequence number, an associated control channel RS sequence number, and / or an index in a WTRU measurement report) and / or an explicit data channel ID that may be mapped to a particular data channel beam, a UL control channel beam configuration associated with a DL transmission, and / or a set of control symbols to monitor for a serving control channel beam, etc. The time and / or frequency resource information may include one or more of the following: resource allocation information corresponding to a downlink data channel beam indicated in the spatial information, a starting symbol location for the PDSCH within a subframe, a duration (in number of symbols), frequency / resource block information, and / or an index to a pre-configured symbol group / resource group in time and / or frequency, etc.

[0211] The spatial information may be conveyed using L23 signaling (e.g., RRC and / or MAC CE) and / or L1 signaling (e.g., in DCI). The WTRU may consider the spatial information valid after transmitting an ACK corresponding to the DL PDSCH carrying the spatial information. The WTRU may assume that the spatial information is valid until they receive an RRC / MAC CE / DCI with different spatial information. The time and / or frequency resource information may be conveyed using L1 signaling (e.g., in DCI). The scheduling information in the time and / or frequency resource information may be valid for (e.g., only for) the subframe in which the resource information is received. Different DCI formats may be defined. For example, two different DCI formats may be defined, one having time and / or frequency resource information and / or the other having time and / or frequency resource information and / or spatial information. The DCI format may include time and / or frequency resource information and / or other DCI formats may include spatial information.

[0212] For DL, beams can be combined. For downlink data transmission, the spatial information can be conveyed to the WTRU using L23 signaling (e.g., RRC and / or MAC CE) and / or L1 signaling (e.g., in DCI). The DCI and / or L23 message can carry one or more of the following per spatial information: symbol location, duration, resource block configuration, WTRU-specific reference signal ID and / or beam ID, antenna port number, and / or HARQ information (e.g., redundancy version), etc. The spatial information (e.g., one or more or each spatial information) can identify the transmission direction and / or data channel beam to the WTRU. The WTRU can receive a single transport block in a subframe and / or a sequence of subframes multiplexed in the time domain using multiple spatial configurations (e.g., multiple data channel beams). The WTRU can soft-combine spatial repetitions of the transport block to improve the effective SNR. The WTRU may use the same and / or different receive antenna configurations and / or receive beam patterns that correspond to the downlink spatial information signaled for beam combining.

[0213] UL data may be scheduled. Upon detection of a PDCCH in some (e.g., at least one) of the serving control channel beams in subframe / subframe n indicating an UL grant addressed to the WTRU, the WTRU may transmit a PUSCH in subframe / subframe n+k using the UL data channel beam indicated in the PDCCH. The WTRU may assume that it can use the current UL control channel beam for UL data transmission, e.g., when no data channel beam identity is included in the DCI message. One or more WTRUs may assume the last indicated UL data channel beam and / or the data channel indicated by higher layer configuration for UL data transmission, e.g., when no data channel beam identity is included in the DCI message. The scrambling initialization of the PUSCH may be a function of the control channel beam ID carrying the allocation and / or the beam ID of the UL data channel beam and / or the WTRU-specific RNTI (e.g., C-RNTI and / or SPS-RNTI) and / or the beam type.

[0214] Within an UL subframe, a data region may include multiple UL data channel beams from one or more WTRUs multiplexed in time. For example, a data channel may occupy one or more symbols and / or the remaining symbols within the same subframe may be used by other UL data channel beams destined for the same and / or different WTRUs. A WTRU may be assigned multiple UL data channel resources within the same subframe. A (e.g., one or more or each) set of UL data channel resources may be associated with a different UL data beam.

[0215] Uplink transmissions from multiple WTRUs within the same subframe and / or scheduling interval can be multiplexed in the time and / or frequency domain. The scheduling granularity can be smaller than a subframe and / or scheduling interval. The new DCI format can carry UL allocation information at the symbol level / symbol group, starting offset, repetition information (e.g., more than one UL data channel per WTRU per subframe), spatial information (e.g., UL transmission beam ID).

[0216] One or more WTRUs may identify and / or communicate an uplink data beam. One or more WTRUs may use a particular beam pattern for UL data channel transmission. One or more WTRUs may use a different transmit beam pattern for the uplink control channel as compared to the transmit beam pattern used for the uplink data channel beam. The mB may include a transmit beam ID corresponding to the UL data channel beam to enable the WTRU to switch the transmit beam accordingly. One or more WTRUs may use (e.g., require) gaps and / or decoding periods between the PDCCH and / or actual UL data channel resources carrying UL grants.

[0217] The UL data channel beam information can be combined with resource allocation information. For example, the DCI can include a transmit beam identification in the PDCCH, which carries resource allocation in terms of time (e.g., symbols, symbol groups) and / or frequency (e.g., RBs). The mB can provide (e.g., explicitly) a gap and / or a guard period between the last symbol of the PDCCH and the first symbol of the PUSCH. The guard period can be defined from the perspective of the WTRU. The mB can use the symbols in the guard period to schedule other WTRUs. The WTRU can assume (e.g., always assume) an offset between the PDCCH and the PUSCH. For example, the PDCCH in subframe n can allocate a PUSCH in subframe n+k. The value of k can be dynamic and / or configured by higher layer signaling (MAC and / or RRC) and / or included in the DCI message.

[0218] The UL data channel beam information and / or spatial information can be independent of the resource allocation (e.g., time, frequency, code) information. The spatial information, e.g., UL data channel transmission beam identification information, can be derived from the SRS (e.g., SRS sequence ID, and / or SRS configuration ID, etc.) decoupled from the time and / or frequency resource allocation information. The spatial information can be derived from the random access procedure (preamble ID and / or subframe) decoupled from the time and / or frequency resource allocation information. The spatial information can be conveyed using the RRC configuration / MAC CE / DCI decoupled from the time and / or frequency resource allocation information. The spatial information can be acknowledged by the WTRU, for example, to prevent mismatch between the mB and the WTRU before the actual data transmission on the indicated data channel beam. The spatial information, as well as the resource allocation information (e.g., time and / or frequency), can have a predefined and / or configured offset with respect to the assigned resources. The spatial information can be associated with a validity period. For example, upon expiration of the validity period, the WTRU may perform (eg, be required to perform) one or more of a sounding procedure and / or a RACH, etc.

[0219] The UL control channel beams may be scheduled using separate spatial information. The UL data channel beams may be scheduled using combined spatial information. One or more WTRUs in the same cell may receive scheduling information using different configurations (e.g., combined and / or separate).

[0220] The DCI may have a format and / or content. Downlink control information for a UL data channel grant may include one or more of the following: spatial information, time resource information, and / or frequency resource information, etc. The spatial information may include one or more of the following: implicit data channel beam identity, and / or DL ​​PHICH beam configuration, etc. The implicit data channel beam identity (beam identification) may include one or more of the following: a preamble ID, a subframe, and / or an explicit data channel ID that may be mapped to a particular data channel beam, such as an SRS sequence ID and / or an SRS configuration ID, and / or an explicit ID negotiated with the WTRU, etc. The time and / or frequency resource information may include one or more of the following: information that may indicate resource allocation information corresponding to a downlink data channel beam indicated in the most recent spatial information, a starting symbol location for the PUSCH within a subframe, a duration (in number of symbols), frequency / resource block information, and / or an index to a pre-configured symbol group / resource group in time and / or frequency, etc.

[0221] The spatial information may be conveyed using Layer 2 and / or 3 (L23) signaling (e.g., RRC and / or MAC CE) and / or L1 signaling (e.g., in DCI). After the WTRU transmits an ACK corresponding to the DL PDSCH carrying the spatial information, it may consider the scheduling information received in the spatial information to be valid. The WTRU may possibly assume that the spatial information is valid, for example, until it receives an RRC / MAC CE / DCI with different spatial information. The time and / or frequency resource information may be conveyed using L1 signaling (e.g., in DCI). The scheduling information in the time and / or frequency resource information may be valid for (e.g., only for) the subframe in which the resource information is received.

[0222] Different DCI formats may be defined. One or more (e.g., two) different DCI formats may be defined, perhaps one having time and / or frequency resource information and / or another having time and / or frequency resource information and / or spatial information. A DCI format may include time and / or frequency resource information and / or another DCI format may include spatial information.

[0223] For the UL, one or more beams may be combined. For uplink data transmission, spatial information may be conveyed to the WTRU using L23 signaling (e.g., RRC and / or MAC CE) and / or L1 signaling (e.g., in DCI). The DCI and / or L23 messages may carry one or more of the following per spatial information: symbol location, duration, resource block configuration, WTRU-specific reference signal ID and / or beam ID and / or SRS configuration ID, antenna port number, and / or HARQ information (e.g., redundancy version), etc.

[0224] The (e.g., one or more or each) spatial information may identify (e.g., uniquely identify) a transmission direction and / or a data channel beam from the WTRU. The WTRU may transmit a single transport block, possibly, for example, in a subframe and / or a sequence of subframes multiplexed in the time domain using multiple spatial configurations (e.g., multiple data channel beams). The mB may soft-combine spatial repetitions of the transport block, for example, to improve the effective SNR. The mB may use the same receive antenna configuration and / or receive beam pattern corresponding to the uplink spatial information signaled for beam combining. The mB may use a different receive antenna configuration and / or receive beam pattern corresponding to the uplink spatial information signaled for beam combining.

[0225] The UL control channel information may be part of the UL data scheduling. The DCI may carry UL control channel information and / or DL ​​grants for data channels. The UL control channel information may include resources used for feedback (e.g., ACK / NACK and / or CSI, etc.). The mB may dynamically communicate WTRU UL control beams for feedback using a DCI carrying a corresponding DL resource allocation. One or more WTRUs may associate UL control channel resources allocated in a DCI with DL data channel allocations present in the same DCI. The UL control channel information may include time resources (e.g., subframe offset or symbol offset from the current subframe) and / or frequency resources (e.g., resource blocks). The UL control channel information may include spatial information for the UL control channel. For example, a UL control beam for a WTRU may be identified by an SRS configuration ID and / or an SRS sequence, and / or a RACH identifier (RA-RNTI and / or preamble sequence number) used by the WTRU for periodic / aperiodic transmission of the corresponding UL control channel beam.

[0226] The mB may pre-configure a mapping between DL control beams carrying DL data allocations and WTRU UL control beams carrying feedback. The configuration may be WTRU-specific. The mB may pre-configure a mapping between DL transmit control beams carrying DL data allocations and mB UL receive control beam resources for receiving feedback. The configuration may provide WTRU-specific resources (e.g., frequency / time / code) within the mB UL receive beam. The mB may semi-statically schedule uplink control beams using higher layer signaling. The mB may schedule different uplink control beams for different feedback types (e.g., ACK / NACK vs. CSI). In some or all of the schemes described herein, the mB may configure two or more UL WTRU control beams for feedback (e.g., repeat and / or implicit HARQ retransmissions).

[0227] 24A is a diagram of an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communication system 100 may utilize one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), and Single Carrier FDMA (SC-FDMA).

[0228] 24A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, and / or 102d (which may be referred to generally or collectively as WTRUs 102), radio access networks (RANs) 103 / 104 / 105, a core network 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 may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, and home appliances.

[0229] The communication system 100 may also include a base station 114a and a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the core network 106 / 107 / 109, the Internet 110, and / or the network 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each shown as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0230] The base station 114a may be part of the RAN 103 / 104 / 105, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the 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). The cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, e.g., one for each sector of the cell. In another embodiment, the base station 114a may utilize multiple-input multiple-output (MIMO) technology and thus may utilize multiple transceivers for each sector of the cell.

[0231] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 115 / 116 / 117, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 115 / 116 / 117 may be established using any suitable radio access technology (RAT).

[0232] More specifically, as mentioned above, the communication system 100 may be a multiple access system and may utilize one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, and SC-FDMA. For example, the base station 114a in the RAN 103 / 104 / 105 and the WTRUs 102a, 102b, 102c may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using Wideband CDMA (WCDMA). WCDMA may include communication protocols, such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0233] In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 115 / 116 / 117 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A).

[0234] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as IEEE 802.16 (e.g., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0235] The base station 114b of FIG. 24A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a workplace, a home, a vehicle, and a campus. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology, such as IEEE 802.11, to establish a wireless local area network (WLAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology, such as IEEE 802.15, to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocell or femtocell. 24A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not or may not be used to access the Internet 110 via the core network 106 / 107 / 109.

[0236] The RAN 103 / 104 / 105 may communicate with the core network 106 / 107 / 109, which may be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. For example, the core network 106 / 107 / 109 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high level security functions, such as user authentication. Although not shown in FIG. 24A, it will be appreciated that the RAN 103 / 104 / 105 and / or the core network 106 / 107 / 109 may communicate directly or indirectly with other RANs that utilize the same RAT as the RAN 103 / 104 / 105 or a different RAT. For example, in addition to connecting to the RANs 103 / 104 / 105 that may utilize E-UTRA radio technology, the core networks 106 / 107 / 109 may also communicate with another RAN (not shown) that utilizes GSM radio technology.

[0237] The core network 106 / 107 / 109 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Protocol (IP) in the TCP / IP Internet protocol suite. The network 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another core network connected to one or more RANs that may utilize the same RAT as the RANs 103 / 104 / 105 or a different RAT.

[0238] One or more of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities, e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links. For example, the WTRU 102c shown in FIG. 24A may be configured to communicate with a base station 114a that may utilize a cellular-based wireless technology and with a base station 114b that may utilize an IEEE 802 wireless technology.

[0239] Figure 24B is a system diagram of an example WTRU 102. As shown in Figure 24B, 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, non-removable memory 130, removable memory 132, a power source 134, a Global Positioning System (GPS) chipset 136, and other peripherals 138. It will be understood that the WTRU 102 may include any subcombination of the above elements while remaining consistent with an embodiment. Also, embodiments contemplate that the base stations 114a, 114b, and / or the nodes that the base stations 114a, 114b may represent, such as, but not limited to, a transceiver station (BTS), a Node B, a site controller, an access point (AP), a Home Node B, an Evolved Node B (eNodeB), a Home Evolved Node B (HeNB), a Home Evolved Node B Gateway, and a proxy node, among others, may include some or all of the elements shown in FIG. 24B and described herein.

[0240] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors in conjunction with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although FIG. 24B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0241] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) over the air interface 115 / 116 / 117. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In another embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0242] 24B, the transmit / receive element 122 is shown as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may utilize MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 115 / 116 / 117.

[0243] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, 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.

[0244] The processor 118 of the WTRU 102 may be coupled to and may 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. In addition, the processor 118 may obtain 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, memory that is not physically located on the WTRU 102, such as located on a server or home computer (not shown).

[0245] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components within the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 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, etc.

[0246] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 115 / 116 / 117 from a base station (e.g., base stations 114a, 114b) 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 the WTRU 102 may obtain location information using any suitable location determination method while remaining consistent with an embodiment.

[0247] The processor 118 may further be coupled to other peripherals 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, the peripherals 138 may include an accelerometer, an e-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 modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, and the like.

[0248] FIG. 24C is a system diagram of the RAN 103 and the core network 106, according to an embodiment. As mentioned above, the RAN 103 may communicate with the WTRUs 102a, 102b, 102c over the air interface 115 utilizing UTRA radio technology. The RAN 103 may also communicate with the core network 106. As shown in FIG. 24C, the RAN 103 may include Node Bs 140a, 140b, 140c, each of which may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 115. The Node Bs 140a, 140b, 140c may each be associated with a particular cell (not shown) within the RAN 103. The RAN 103 may also include RNCs 142a, 142b. It will be appreciated that the RAN 103 may include any number of Node Bs and RNCs while remaining consistent with an embodiment.

[0249] As shown in FIG. 24C, the Node Bs 140a, 140b can communicate with the RNC 142a. Additionally, the Node Bs 140c can communicate with the RNC 142b. The Node Bs 140a, 140b, 140c can communicate with their respective RNCs 142a, 142b via an Iub interface. The RNCs 142a, 142b can communicate with each other via an Iur interface. Each of the RNCs 142a, 142b can be configured to control the respective Node Bs 140a, 140b, 140c to which it is connected. Additionally, each of the RNCs 142a, 142b can be configured to implement or support other functionalities, such as outer loop power control, load control, admission control, packet scheduling, handover control, macro diversity, security functions, and data encryption.

[0250] The core network 106 shown in Figure 24C 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 different from the core network operator.

[0251] The RNC 142a in the RAN 103 may be connected to an MSC 146 in the core network 106 via an IuCS interface. The MSC 146 may be connected to the MGW 144. The MSC 146 and MGW 144 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and land-line communication devices.

[0252] The RNC 142a in the RAN 103 may also be connected to an SGSN 148 in the core network 106 via an IuPS interface. The SGSN 148 may be connected to a GGSN 150. The SGSN 148 and GGSN 150 may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0253] As mentioned above, the core network 106 may also connect to the networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0254] 24D is a system diagram of the RAN 104 and the core network 107, according to an embodiment. As mentioned above, the RAN 104 may utilize E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also communicate with the core network 107.

[0255] The RAN 104 may include eNodeBs 160a, 160b, 160c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNodeBs 160a, 160b, 160c may implement MIMO technology. Thus, the eNodeB 160a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0256] Each of the 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 on the uplink and / or downlink, etc. As shown in Figure 24D, the eNodeBs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0257] The core network 107 shown in Figure 24D may include a mobility management gateway (MME) 162, a serving gateway 164, and a packet data network (PDN) gateway 166. Although each of the above elements is shown as part of the core network 107, it will be understood that any one of these elements may be owned and / or operated by an entity different from the core network operator.

[0258] The MME 162 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface and may act as a control node. For example, the MME 162 may be responsible for authentication of users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selection of a particular serving gateway during initial attachment of the WTRUs 102a, 102b, 102c, etc. The MME 162 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[0259] The serving gateway 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The serving gateway 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The serving gateway 164 may also perform other functions, such as anchoring the user plane during inter-eNodeB handovers, triggering paging when downlink data is available to the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0260] The serving gateway 164 may also be connected to a PDN gateway 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0261] The core network 107 may facilitate communications with other networks. For example, the core network 107 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and land-line communications devices. For example, the core network 107 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the core network 107 and the PSTN 108. In addition, the core network 107 may provide the WTRUs 102a, 102b, 102c with access to the network 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0262] 24E is a system diagram of the RAN 105 and the core network 109, according to an embodiment. The RAN 105 may be an Access Service Network (ASN) that utilizes IEEE 802.16 wireless technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 117. As described further 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.

[0263] As shown in FIG. 24E, the RAN 105 may include base stations 180a, 180b, 180c and an ASN gateway 182, although it will be understood that the RAN 105 may include any number of base stations and ASN gateways while remaining consistent with an embodiment. The base stations 180a, 180b, 180c may each be associated with a particular cell (not shown) in the RAN 105 and each may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 117. In one embodiment, the base stations 180a, 180b, 180c may implement MIMO technology. Thus, the base station 180a may, for example, use multiple antennas to transmit wireless signals to and receive wireless signals from the WTRU 102a. The base stations 180a, 180b, 180c may also provide mobility management functions such as handoff triggering, tunnel establishment, radio resource management, traffic classification, and quality of service (QoS) policy enforcement. The ASN gateway 182 may act as a traffic aggregation point and may be responsible for paging, caching of subscriber profiles, routing to the core network 109, etc.

[0264] The air interface 117 between the WTRUs 102a, 102b, 102c and the RAN 105 may be defined as an R1 reference point, which implements the IEEE 802.16 specification. In addition, each of the WTRUs 102a, 102b, 102c may establish a logical interface (not shown) with the core network 109. The logical interface between the WTRUs 102a, 102b, 102c and the core network 109 may be defined as an R2 reference point, which may be used for authentication, authorization, IP host configuration management, and / or mobility management.

[0265] The communication link between each of the base stations 180a, 180b, 180c may be defined as an R8 reference point, which includes protocols for facilitating WTRU handovers and the transfer of data between base stations. The communication link between the base stations 180a, 180b, 180c and the ASN gateway 182 may be defined as an R6 reference point, which may include protocols for facilitating mobility management based on mobility events associated with each of the WTRUs 102a, 102b, 102c.

[0266] As shown in FIG. 24E, the RAN 105 may be connected to a core network 109. The communication link between the RAN 105 and the core network 109 may be defined as an R3 reference point, which includes protocols for facilitating, for example, data forwarding and mobility management functions. The core network 109 may include a Mobile IP Home Agent (MIP-HA) 184, an Authentication, Authorization, and Accounting (AAA) server 186, and a gateway 188. Although each of the above elements is shown as part of the core network 109, it will be understood that any one of these elements may be owned and / or operated by an entity different from the core network operator.

[0267] The MIP-HA 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 packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The AAA server 186 may be responsible for user authentication and support of user services. The gateway 188 may facilitate interworking with other networks. For example, the gateway 188 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and land-line communications devices. In addition, the gateway 188 may provide access to the network 112 for the WTRUs 102a, 102b, 102c, which may include other wired or wireless networks owned and / or operated by other service providers.

[0268] Although not shown in Figure 24E, 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 the other ASNs may be defined as an R4 reference point, which may include protocols for coordinating mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and the other ASNs. The communication link between the core network 109 and the other core networks may be defined as an R5 reference point, which may include protocols for facilitating interworking between a home core network and a visited core network.

[0269] Although features and elements have been described above in certain combinations, one skilled in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein can be implemented in a computer program, software, or firmware embodied in a computer-readable medium that is executed 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, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor in conjunction with software can be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

[Claim 1] 1. A wireless transmit / receive unit (WTRU) configured for wireless communication, comprising: Memory, and a processor, the processor comprising at least one or more search spaces configured to provide at least one of monitoring one or more downlink (DL) control channels or receiving the one or more DL control channels, at least one search space of the one or more search spaces corresponding to at least one reference signal of the one or more reference signals; The processor is configured with at least monitoring at least a portion of a control region for at least one reference signal of the one or more reference signals; detecting the at least one reference signal within at least a portion of the control region; Upon detection of the at least one reference signal, monitor the at least one search space corresponding to the at least one reference signal for at least one DL control channel. The WTRU is configured as follows.

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