Patent Description:
An example telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to support mobile broadband access through improved spectral efficiency, lowered costs, and improved services using OFDMA on the downlink, SC-FDMA on the uplink, and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology.

In millimeter wave systems, user equipment may not be able to receive system information through a common control channel when the system information is transmitted with an omni-directional beam. The foregoing discussion provides solutions to address this problem.

<CIT>discusses an initial access method and device.

In accordance with the present invention, there is provided a method of wireless communication by a base station as set out in claim <NUM>, a base station for wireless communication as set out in claim <NUM> and a non-transitory computer-readable medium of a base station storing computer executable code as set out in claim <NUM>. Other aspects of the invention can be found in the dependent claims. Any embodiment referred to and not falling within the scope of the claims is merely an example useful to the understanding of the invention.

The macro cells include eNBs.

A network that includes both small cell and macro cells may be known as a heterogeneous network. The communication links <NUM> may use MIMO antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The base stations <NUM> / UEs <NUM> may use spectrum up to Y MHz (e.g., <NUM>, <NUM>, <NUM>, <NUM>) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

When operating in an unlicensed frequency spectrum, the small cell <NUM>' may employ LTE and use the same <NUM> unlicensed frequency spectrum as used by the Wi-Fi AP <NUM>. The small cell <NUM>', employing LTE in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network. LTE in an unlicensed spectrum may be referred to as LTE-unlicensed (LTE-U), licensed assisted access (LAA), or MuLTEfire.

The millimeter wave (mmW) base station <NUM> may operate in mmW frequencies and/or near mmW frequencies in communication with the UE <NUM>.

The IP Services <NUM> may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service (PSS), and/or other IP services.

The base station may also be referred to as a Node B, evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), or some other suitable terminology. The base station <NUM> provides an access point to the EPC <NUM> for a UE <NUM>. Examples of UEs <NUM> include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, or any other similar functioning device.

Referring again to <FIG>, in certain aspects, the eNB <NUM> may be configured to determine RACH parameters and transmit a subset of the parameters via a physical broadcast channel (<NUM>), and the UE <NUM> may be configured to receive the subset of the RACH parameters via the physical broadcast channel and initiate a RACH procedure with the eNB <NUM> (<NUM>).

<FIG> is a diagram <NUM> illustrating an example of a DL frame structure in LTE. <FIG> is a diagram <NUM> illustrating an example of channels within the DL frame structure in LTE. <FIG> is a diagram <NUM> illustrating an example of an UL frame structure in LTE. <FIG> is a diagram <NUM> illustrating an example of channels within the UL frame structure in LTE. In LTE, a frame (<NUM>) may be divided into <NUM> equally sized subframes. Each subframe may include two consecutive time slots. A resource grid may be used to represent the two time slots, each time slot including one or more time concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)). In LTE, for a normal cyclic prefix, an RB contains <NUM> consecutive subcarriers in the frequency domain and <NUM> consecutive symbols (for DL, OFDM symbols; for UL, SC-FDMA symbols) in the time domain, for a total of <NUM> REs. For an extended cyclic prefix, an RB contains <NUM> consecutive subcarriers in the frequency domain and <NUM> consecutive symbols in the time domain, for a total of <NUM> REs.

As illustrated in <FIG>, some of the REs carry DL reference (pilot) signals (DL-RS) for channel estimation at the UE. The DL-RS may include cell-specific reference signals (CRS) (also sometimes called common RS), UE-specific reference signals (UE-RS), and channel state information reference signals (CSI-RS). <FIG> illustrates CRS for antenna ports <NUM>, <NUM>, <NUM>, and <NUM> (indicated as R<NUM>, R<NUM>, R<NUM>, and R<NUM>, respectively), UE-RS for antenna port <NUM> (indicated as R<NUM>), and CSI-RS for antenna port <NUM> (indicated as R). <FIG> illustrates an example of various channels within a DL subframe of a frame. The physical control format indicator channel (PCFICH) is within symbol <NUM> of slot <NUM>, and carries a control format indicator (CFI) that indicates whether the physical downlink control channel (PDCCH) occupies <NUM>, <NUM>, or <NUM> symbols (<FIG> illustrates a PDCCH that occupies <NUM> symbols). The PDCCH carries downlink control information (DCI) within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. A UE may be configured with a UE-specific enhanced PDCCH (ePDCCH) that also carries DCI. The ePDCCH may have <NUM>, <NUM>, or <NUM> RB pairs (<FIG> shows two RB pairs, each subset including one RB pair). The physical hybrid automatic repeat request (ARQ) (HARQ) indicator channel (PHICH) is also within symbol <NUM> of slot <NUM> and carries the HARQ indicator (HI) that indicates HARQ acknowledgement (ACK) / negative ACK (NACK) feedback based on the physical uplink shared channel (PUSCH). The primary synchronization channel (PSCH) is within symbol <NUM> of slot <NUM> within subframes <NUM> and <NUM> of a frame, and carries a primary synchronization signal (PSS) that is used by a UE to determine subframe timing and a physical layer identity. The secondary synchronization channel (SSCH) is within symbol <NUM> of slot <NUM> within subframes <NUM> and <NUM> of a frame, and carries a secondary synchronization signal (SSS) that is used by a UE to determine a physical layer cell identity group number. Based on the PCI, the UE can determine the locations of the aforementioned DL-RS. The physical broadcast channel (PBCH) is within symbols <NUM>, <NUM>, <NUM>, <NUM> of slot <NUM> of subframe <NUM> of a frame, and carries a master information block (MIB). The MIB provides a number of RBs in the DL system bandwidth, a PHICH configuration, and a system frame number (SFN).

As illustrated in <FIG>, some of the REs carry demodulation reference signals (DM-RS) for channel estimation at the eNB. The UE may additionally transmit sounding reference signals (SRS) in the last symbol of a subframe. The SRS may be used by an eNB for channel quality estimation to enable frequency-dependent scheduling on the UL. <FIG> illustrates an example of various channels within an UL subframe of a frame. A physical random access channel (PRACH) may be within one or more subframes within a frame based on the PRACH configuration. The PRACH may include six consecutive RB pairs within a subframe. The PRACH allows the UE to perform initial system access and achieve UL synchronization. A physical uplink control channel (PUCCH) may be located on edges of the UL system bandwidth.

<FIG> is a block diagram of an eNB <NUM> in communication with a UE <NUM> in an access network.

The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the eNB <NUM>. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the eNB <NUM> on the physical channel.

Similar to the functionality described in connection with the DL transmission by the eNB <NUM>, the controller/processor <NUM> provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression / decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

Channel estimates derived by a channel estimator <NUM> from a reference signal or feedback transmitted by the eNB <NUM> may be used by the TX processor <NUM> to select the appropriate coding and modulation schemes, and to facilitate spatial processing.

The UL transmission is processed at the eNB <NUM> in a manner similar to that described in connection with the receiver function at the UE <NUM>.

<FIG> is a call flow diagram <NUM> illustrating a RACH procedure. Referring to <FIG>, the RACH procedure may enable uplink synchronization between a UE <NUM> and a base station <NUM> (e.g., the mmW base station <NUM>). The RACH procedure may also be used to obtain resources for communication. The UE <NUM> may engage in a contention-based RACH procedure with the base station <NUM>. The RACH procedure may include a message exchange involving four messages - a first message <NUM>, a second message <NUM>, a third message <NUM>, and a fourth message <NUM>. In an aspect, the UE <NUM> may select an available physical RACH (PRACH) contention-based preamble (or a RACH signature). The preamble may be one of <NUM> different patterns (or some other number of patterns) generated from Zadoff-Chu sequences, but if multiple UEs have the same preamble, then a collision may occur. The Zadoff-Chu sequence may be generated based on a root value, which may be determined by a RACH preamble index (cell-specific). In an aspect, a subset of the <NUM> signatures/preambles may be reserved for the contention-free RACH procedure. In an aspect, the UE <NUM> may select the signature based on the size of the transmission resource needed for transmitting the third message <NUM>. The UE <NUM> may determine the size of the transmission resource based on a pathloss and a required transmission power for the third message <NUM>. The preamble may be transmitted by the UE <NUM> to the base station <NUM> in the first message <NUM>. If the UE <NUM> does not receive a response from the base station <NUM> after transmitting the first message <NUM>, then the UE <NUM> may ramp up the transmission power in a fixed step and retransmit the first message <NUM>.

After receiving the first message <NUM>, the base station <NUM> may transmit the second message <NUM> to the UE <NUM>. The second message <NUM> may be a RACH response (RAR) message sent via the PDSCH. The second message <NUM> may provide the identity of the detected preamble, a timing alignment instruction that enables the UE <NUM> to synchronize subsequent uplink transmissions (e.g., a timing advance used to compensate for the round trip delay caused by the distance between the UE <NUM> and the base station <NUM>), and an initial uplink resource grant for the UE <NUM> to transmit the third message <NUM> (e.g., via the PUSCH). The second message <NUM> may also include a cell radio network temporary identity (C-RNTI) that identifies the UE <NUM>.

The UE <NUM> may transmit the third message <NUM> to the base station <NUM>, and the third message <NUM> may be a Layer <NUM>/Layer <NUM> message or an RRC connection request message. The third message <NUM> may also include a UE identifier that identifies the UE <NUM> (e.g., a random value or a temporary mobile subscriber identity (TMSI)), an RRC connection request, a tracking area update, and/or a scheduling request. The third message <NUM> may also include a connection establishment clause, indicating why the UE <NUM> needs to connect to the network. In an aspect, the third message <NUM> may also include the C-RNTI.

After receiving the third message <NUM>, the base station <NUM> may adjust one or more transmission parameters for transmitting the fourth message <NUM> to the UE <NUM>. For example, the base station <NUM> may select one or more antennas, determine the transmit power on the selected antennas, and/or choose an MCS to use for subsequent transmission to the UE <NUM>. The base station <NUM> may transmit the fourth message <NUM> to the UE <NUM>. The fourth message <NUM> may be a contention resolution message (e.g., if multiple UEs initiated the RACH procedure using the same selected signature the selected UE is indicated). The fourth message <NUM> may be addressed to the UE identifier included in the third message <NUM> and may contain a new C-RNTI to be used for further communication.

Referring to <FIG>, the UE <NUM> may need different information, known as RACH parameters (e.g., a system frame number, a RACH preamble index, base station transmit power, RACH power ramping step, etc.), before the UE <NUM> can transmit the first message <NUM> of the RACH procedure to the base station <NUM>. Such information may be divided into two groups: a MIB and a SIB. In an aspect, the system frame number may be included in the MIB, which may be transmitted by the base station <NUM> through the PBCH. The remaining RACH parameters may be transmitted in the SIB.

In one aspect of LTE, the SIB may be transmitted through the PDCCH. The PDCCH may be transmitted in a cell-specific manner (e.g., scrambled with a RNTI associated with the cell or a device within the cell) using an omni-directional or quasi-omni-directional beam. In this manner, all UEs regardless of their location in the cell may be able to receive the PDCCH and decode the PDCCH to obtain the SIB and to extract the RACH parameters needed to transmit RACH to the base station <NUM>.

In mmW systems, free space path loss and additional non-line-of-sight loss is high. If the SIB is transmitted through a cell-specific PDCCH, the SIB may not reach all UEs in the mmW system. As such, transmissions in mmW systems may need to be beamformed. <FIG> are diagrams <NUM>, <NUM> of a base station <NUM> using beamforming and beam sweeping to transmit a synchronization subframe in a mmW system. Referring to <FIG>, for example, the base station <NUM> may opt to transmit the SIB using beamforming. If the base station <NUM> has at least four antenna ports, the base station <NUM> may directionally sweep the transmission in four directions to transmit four beams <NUM>, <NUM>, <NUM>, and <NUM> using four antenna ports in a cell-specific manner. The directional sweeping may otherwise be known as beam sweeping. The SIB may be transmitted in the first symbol of a synchronization subframe (e.g., symbol <NUM> in slot <NUM> of subframe <NUM> in <FIG>). Referring to <FIG>, the base station <NUM> may sweep in four different directions using the four antenna ports in the second symbol of the synchronization subframe (e.g., symbol <NUM> in slot <NUM> of subframe <NUM> in <FIG>) to transmit the four beams <NUM>, <NUM>, <NUM>, <NUM>. Because the base station <NUM> sweeps in different symbols in <FIG>, the angular/directional range of the beams for the example in <FIG> may be different from the angular/directional range of the beams for the example in <FIG>. The beams transmitted by the base station <NUM> during the same symbol may not be adjacent with each other.

In an aspect, the SIB may be transmitted in a new channel named extended PBCH (ePBCH) or another name. The ePBCH may be a second broadcast channel different from the PBCH. In an aspect, the ePBCH may carry more bits than the PBCH, and accordingly, may have a longer duration than the PBCH. The periodicity of the ePBCH may be greater than the periodicity of the PBCH to reduce overhead such that the effective overhead of the ePBCH and the PBCH are the same even though the ePBCH may carry more bits. Using the ePBCH, the same SIB may be transmitted in <NUM> directions using <NUM> symbols. The SIB, however, may have a significant amount of data (e.g., over <NUM> bits). By repeating the transmission <NUM> times, SIB transmission via the ePBCH may create a large amount of overhead. To reduce the overhead, the ePBCH may not be transmitted as frequently. The ePBCH may be transmitted once every <NUM>, whereas the PBCH may be transmitted every <NUM>. If a UE decodes a synchronization subframe containing the PBCH (with the MIB), the UE may have to wait for <NUM> to receive to the SIB via the ePBCH before the UE may transmit the first message in the RACH procedure. To reduce the latency, at least some of the RACH parameters may be transmitted via the PBCH.

<FIG> is a call flow diagram <NUM> illustrating a method of transmitting RACH parameters via a PBCH. Referring to <FIG>, a base station <NUM> determines RACH parameters that enable a UE <NUM> to transmit a first message <NUM> of the RACH procedure for uplink synchronization. The RACH parameters may include a system frame number, a RACH preamble index (denotes preamble indices for contention-based RACH transmission among available preambles), a contention timer (timer for contention resolution), a maximum HARQ transmission (a maximum number of HARQ transmission for message <NUM> in the RACH procedure), a base station transmit power (the UE <NUM> may use the base station transmit power to compute the UE <NUM> transmit power by measuring the received power of a message from the base station and determining the pathloss based on the measured power and the base station transmit power), a maximum preamble transmit power, a random access response window size (duration of the random access response window), a RACH power ramping step (corresponds to a step size, such as <NUM> dB, to increase the transmit power for messages if the transmission is unsuccessful), a RACH format (indicating the duration of the RACH), a RACH frequency, a preamble received target power (a target power for receiving the preamble at the base station <NUM>), and a beam sweep periodicity. The beam sweep periodicity denotes the periodicity of sweeping beams in the system. In some systems, beam sweep periodicity may allow the UE <NUM>, for example, to select the resource of RACH transmission which depends on the best beam index. Resource denotes transmission time or tones of RACH transmission. The foregoing list of RACH parameters is not exhaustive and other parameters may be included. In an aspect, the base station <NUM> may be preconfigured with the RACH parameters. In this aspect, the base station <NUM> may determine the RACH parameters by looking up the RACH parameters in memory and retrieving the parameters for transmission.

After determining the RACH parameters, the base station <NUM> may select a subset of the RACH parameters for transmission. The subset of the RACH parameters may be referred to as RACH information. The RACH information may have <NUM> bits, <NUM> bits, or some other number of bits. In one example, the RACH information may include the RACH preamble index, the beam sweep periodicity, the RACH frequency, and the RACH format. In another example, other RACH parameters may be included. The RACH information is transmitted in a message via a PBCH <NUM>. In an aspect, the PBCH <NUM> may have a frequency (or periodicity) of <NUM> or another value. The message may be transmitted using beamforming, similar to the beamforming as shown in <FIG>, in which the message is beam-formed in a cell-specific manner (e.g., partially scrambled with a RNTI) by sweeping through one or more angular regions in a cell associated with the base station <NUM> during different time units (e.g., symbols).

In one configuration which is not comprised within the scope of the claims, the base station <NUM> may be configured to transmit the full list of RACH parameters via an ePBCH <NUM>. In this configuration, the base station <NUM> may transmit an indication in the PBCH <NUM> that indicates whether the full list of RACH parameters will be transmitted via the ePBCH <NUM>. In one aspect, if the base station <NUM> is not transmitting the RACH parameters via the ePBCH <NUM>, then the base station <NUM> may transmit the RACH information via the PBCH <NUM>. In another aspect, the base station <NUM> may transmit the RACH information via the PBCH <NUM> regardless of whether the base station <NUM> transmits the full list of RACH parameters via the ePBCH <NUM>. In an aspect, the ePBCH <NUM> may also contain other parameters apart from RACH related parameters. For example, the ePBCH <NUM> may include information related to a PDSCH configuration, PUCCH configuration, PUSCH configuration, uplink sounding reference signal configuration, uplink power control information, uplink carrier frequency and bandwidth, etc..

By transmitting the RACH information more frequently via the PBCH <NUM>, the base station <NUM> may reduce latency because the UE <NUM> will have enough information to transmit the first message <NUM> in the RACH procedure immediately after the UE <NUM> decodes the message (or the synchronization frame) rather than having to wait for the full list of RACH parameters, or for remaining RACH parameters not included in the RACH information transmitted in the PBCH, in the ePBCH <NUM>.

In one aspect, the base station <NUM> transmits the RACH information such as the RACH preamble index, the RACH configuration, the beam sweep periodicity, and/or the RACH format in the MIB via the PBCH <NUM> so that each UE in the cell may find the base RACH sequence and the allotted time to transmit RACH. The remaining RACH parameters, not including those that make up the RACH information (e.g., the base station transmit power, the RACH power ramping step, and other parameters) are transmitted through the SIB. The SIB may be transmitted in a cell-specific manner by sweeping through one or more angular regions of the cell. The SIB is transmitted via the ePBCH <NUM>. Alternatively, and not comprised within the scope of the claims, the SIB may be transmitted via a dedicated PDCCH or via the PDSCH. In another configuration, which is not comprised within the scope of the claims, instead of being transmitted in the SIB, one or more of the remaining RACH parameters may be transmitted during the RACH procedure, such as in the second message <NUM> of the RACH procedure, to be used by the UE <NUM> for transmitting the third message <NUM>.

In another aspect, the base station <NUM> may transmit an indication via the PBCH <NUM> that indicates a periodicity with which the full list of RACH parameters is to be transmitted via the ePBCH <NUM>. If the UE <NUM> determines that the periodicity has a time duration greater than a threshold (e.g., greater than <NUM>), then the UE <NUM> may determine not to wait for the full list of RACH parameters in the ePBCH <NUM> and initiate the RACH procedure based on the RACH information received via the PBCH <NUM>.

In another aspect, the subframe in which the PBCH is transmitted may be frequency-division multiplexed or time-division multiplexed as later described with respect to <FIG> and <FIG>.

After receiving the RACH information via the PBCH <NUM>, the UE <NUM> may determine to transmit the first message <NUM> to the base station <NUM>. The UE <NUM> may determine the RACH preamble to use based on the RACH preamble index indicated in the RACH information from the PBCH <NUM>. The UE <NUM> may determine the frequency on which to transmit the first message <NUM> based on the RACH information. The UE <NUM> may determine the duration of the RACH procedure based on the RACH format.

In an aspect, if the UE <NUM> receives an indication that the RACH parameters will be transmitted via the ePBCH <NUM>, then the UE <NUM> may wait for the RACH parameters before transmitting the first message <NUM>. In another aspect, the UE <NUM> may not wait for the RACH parameters via the ePBCH <NUM> before transmitting the first message <NUM>. In another aspect, if the UE <NUM> receives an indication that the RACH parameters will not be transmitted via the ePBCH <NUM>, then the UE <NUM> may transmit the first message <NUM> immediately after receiving the RACH information via the PBCH <NUM>. In another aspect, the UE <NUM> may receive an indication of the periodicity with which the RACH parameters are to be transmitted by the base station <NUM> via the ePBCH <NUM>. If the UE <NUM> determines that the periodicity leads to a latency above a threshold, then the UE <NUM> may determine not to wait for the RACH parameters and to transmit the first message <NUM> immediately after receiving the RACH information from the PBCH <NUM>.

In an aspect, having received the RACH information over the PBCH <NUM>, the UE <NUM> may perform initial uplink transmission (e.g., transmit the first message <NUM>) for uplink synchronization without decoding any other channel except synchronization channels (e.g., the PSS, SSS, BRS, and ESS).

After transmitting the first message <NUM>, the UE <NUM> may receive the second message <NUM> from the base station <NUM>. The second message <NUM> may include a timing adjustment for the UE <NUM>, uplink resource grants for transmitting a third message <NUM>, etc. In an aspect, the second message <NUM> may also include RACH parameters. The RACH parameters may be different from those transmitted in the PBCH <NUM>, and the RACH parameters may also be transmitted via the ePBCH <NUM>.

Subsequently, the UE <NUM> may transmit the third message <NUM> to the base station <NUM> that indicates an RRC connection request, and the base station <NUM> may respond by transmitting the fourth message <NUM> to the UE <NUM>. The fourth message <NUM> may be a contention resolution message with an identifier associated with the UE <NUM>.

<FIG> is a diagram <NUM> of a frequency-division multiplexed synchronization subframe. The synchronization subframe may be divided into <NUM> symbols, from symbol <NUM> to symbol <NUM>. Each symbol may have <NUM> resource blocks (RBs) for communication. As an example, each RB may have <NUM> subcarriers, which would mean that each symbol may have <NUM>,<NUM> subcarriers (or tones). The first <NUM> RBs may be used to carry beam reference signals (BRSs) and PBCHs, which may include RACH information. The next <NUM> RBs may carry a SSS, a PSS, and an extended synchronization signal (ESS). The next <NUM> RBs may carry BRSs and PBCHs, and like the first <NUM> RBs, the PBCHs may include RACH information.

The beam transmitted by each antenna port may change from symbol to symbol. As discussed above, for example, for a first symbol, four beams from four antenna ports of the base station may cover one angular range (e.g., as illustrated in <FIG>), while four beams from the four antenna ports may cover another angular range for a different symbol (e.g., as illustrated in <FIG>). For example, the base station may have <NUM>, <NUM>, <NUM>, or <NUM> active antenna ports. Within each symbol, the base station transmits a PSS, an SSS, an ESS, a PBCH, and a BRS. Each of the PSS, the ESS, the SSS, and the PBCH is transmitted by all antenna ports of the base station on the same subcarriers throughout different symbols of the synchronization subframe.

In an aspect, the angular space of the coverage area of a cell may be divided into three sectors, where each sector is associated with <NUM> degrees. A base station may provide coverage for one or more sectors. Each symbol of the synchronization subframe may be associated with a different range in direction/angle. For example, the <NUM> symbols may collectively cover <NUM> degrees (one sector). In this example, because there are <NUM> symbols (thus <NUM> direction ranges) per subframe and there are <NUM> antenna ports in this example, the base station may transmit beams in <NUM> (14x4) different directions. In another example, the symbols within a subframe may cover the angular range more than once. In such an example, if there are <NUM> symbols within a subframe, the first seven symbols may cover <NUM> degrees, and then the next seven symbols may cover the same <NUM> degrees.

<FIG> is a diagram <NUM> of a time-division multiplexed synchronization subframe. The synchronization subframe may be divided into <NUM> symbols, from symbol <NUM> to symbol <NUM>. The tone-spacing within each symbol may be <NUM> or <NUM>. Referring to <FIG>, a base station <NUM> may transmit a synchronization subframe with PSS, SSS, and PBCH, each separated by a cyclic prefix. In another aspect, the synchronization subframe may also have ESS as shown in <FIG>. The PBCH may include the RACH information. The PBCH may be frequency-division multiplexed with beam reference signals. Upon receiving and decoding the PBCH, a UE <NUM> may transmit a first message (RACH message) in the RACH procedure immediately without waiting for the SIB, which may have the remaining RACH parameters that are not in the PBCH.

<FIG> is a flowchart <NUM> of a method of wireless communication. The method may be performed by a base station (e.g., the eNB <NUM>, the mmW base station <NUM>, the apparatus <NUM>/<NUM>'). At <NUM>, the base station may determine RACH parameters. For example, referring to <FIG>, the base station may correspond to the base station <NUM>. The base station <NUM> may determine the RACH parameters that include a system frame number, a RACH preamble index, a contention timer, a maximum HARQ transmission, a base station transmit power, a maximum preamble transmit power, a random access response window size, a RACH power ramping step, a RACH format, a RACH frequency, a preamble received target power, and a beam sweep periodicity. The base station <NUM> may determine the RACH parameters by retrieving the RACH parameters from memory and providing the parameters for transmission. In an aspect, the base station <NUM> may determine the RACH parameters based on channel conditions and/or on a base station maximum transmit power.

At <NUM>, the base station may transmit a message that includes RACH information, based on the determined RACH parameters, via a PBCH. For example, referring to <FIG>, the base station <NUM> may transmit a message that includes the RACH information via the PBCH <NUM>. In an aspect, the RACH information may be a subset of the RACH parameters. In another aspect, the base station <NUM> may transmit the message using beamforming, and the beam-formed message may be beam swept in a cell-specific manner through one or more angular regions in a cell served by the base station <NUM>. The message may be beam swept during symbols using a synchronization subframe.

At <NUM>, the base station may transmit via the PBCH an indication of whether the determined RACH parameters are to be transmitted via an ePBCH. For example, referring to <FIG>, the base station <NUM> may transmit via the PBCH <NUM> an indication of whether the determined RACH parameters are to be transmitted via the ePBCH <NUM>. In one aspect, the base station <NUM> may transmit the RACH information via the PBCH <NUM> based on whether the determined RACH parameters are to be transmitted via the ePBCH <NUM>. For example, if the base station <NUM> will not transmit the RACH parameters via the ePBCH <NUM>, then the base station <NUM> may transmit the RACH information via the PBCH <NUM>.

At <NUM>, the base station may transmit via the PBCH an indication of a periodicity with which the determined RACH parameters are to be transmitted via an ePBCH. For example, referring to <FIG>, the base station <NUM> transmits via the PBCH <NUM> an indication that the determined RACH parameters are to be transmitted every <NUM>. If the periodicity is too long (e.g., greater than <NUM>), the UEs receiving the indication may determine not to wait for the RACH parameters before transmitting a RACH message (e.g., the first message <NUM>).

At <NUM>, the base station may transmit at least a subset of the determined RACH parameters via a SIB. For example, referring to <FIG>, the base station <NUM> may transmit at least a subset of the determined RACH parameters via a SIB. In one aspect, the at least the subset of the determined RACH parameters may include the remaining RACH parameters that were not transmitted with the RACH information. In another respect, the at least the subset of the determined RACH parameters may include the full list of RACH parameters. In another aspect, the RACH parameters may be transmitted in a cell-specific manner by sweeping through one or more angular regions in a cell. In another aspect, the SIB may be transmitted via the ePBCH <NUM>. In another aspect, the SIB may be transmitted via the PDCCH or the PDSCH.

At <NUM>, the base station may transmit at least a subset of the determined RACH parameters during a RACH procedure. For example, referring to <FIG>, the base station <NUM> may transmit the at least the subset of the determined RACH parameters in the second message <NUM> during the <NUM>-message RACH procedure.

<FIG> is a flowchart <NUM> of a method of wireless communication. The method may be performed by a UE (e.g., the UE <NUM>, the apparatus <NUM>/<NUM>'). At <NUM>, the UE may receive a message that includes RACH information associated with a base station via a PBCH. For example, referring to <FIG>, the UE may be the UE <NUM>. The UE <NUM> may receive a message that include RACH information associated with the base station <NUM> via the PBCH <NUM>.

At <NUM>, the UE may transmit a RACH message to the base station during a RACH procedure based on the received RACH information. For example, referring to <FIG>, the UE <NUM> may transmit the first message <NUM> (a RACH message) to the base station <NUM> during a RACH procedure. The first message <NUM> may be transmitted based on the RACH information received via the PBCH <NUM>.

At <NUM>, the UE may receive via the PBCH an indication of whether the RACH parameters are to be transmitted via an ePBCH. For example, referring to <FIG>, the UE <NUM> may receive via the PBCH <NUM> an indication of whether the base station <NUM> will transmit the RACH parameters via the ePBCH <NUM>.

At <NUM>, the UE may receive via the PBCH an indication of a periodicity with which the RACH parameters are to be transmitted via an ePBCH. For example, referring to <FIG>, the UE <NUM> may receive via the PBCH <NUM> an indication of a periodicity (e.g., every <NUM>) with which the base station <NUM> is to transmit the RACH parameters via the ePBCH <NUM>.

At <NUM>, the UE may receive at least a subset of the RACH parameters via a SIB. For example, referring to <FIG>, the UE <NUM> may receive at least the subset of RACH parameters via a SIB. The subset of the RACH parameters may include the remaining RACH parameters that were not received by the UE <NUM> in the RACH information.

At <NUM>, the UE may receive at least a subset of the RACH parameters during a RACH procedure. For example, referring to <FIG>, the UE <NUM> may receive a subset of the RACH parameters in the second message <NUM>.

<FIG> is a conceptual data flow diagram <NUM> illustrating the data flow between different means/components in an exemplary apparatus <NUM>. The apparatus may be an eNB or a mmW base station. The apparatus includes a reception component <NUM>, a RACH component <NUM>, and a transmission component <NUM>. The RACH component <NUM> may be configured to determine RACH parameters. The transmission component <NUM> may be configured to transmit a message that includes RACH information, based on the determined RACH parameters, via a PBCH. In an aspect, the message that includes RACH information may be transmitted using beamforming. In another aspect, the message may be beam-formed in a cell-specific manner by sweeping through one or more angular regions in a cell during different time units. In another aspect, the RACH parameters may include a beam sweep periodicity, a RACH preamble index, a RACH configuration, a RACH format, a RACH periodicity, a base station transmit power, and a RACH power ramping step. In another aspect, the RACH information may be a subset of the RACH parameters. In one configuration, the transmission component <NUM> may be configured to transmit via the PBCH an indication of whether the determined RACH parameters are to be transmitted via an ePBCH. In an aspect, the RACH information may be transmitted via the PBCH based on whether the determined RACH parameters are to be transmitted via the ePBCH. In another configuration, the transmission component <NUM> may be configured to transmit via the PBCH an indication of a periodicity with which the determined RACH parameters are to be transmitted via an ePBCH. In another configuration, the transmission component <NUM> may be configured to transmit at least a subset of the determined RACH parameters via a SIB. In an aspect, the at least the subset of the determined RACH parameters may be transmitted in a cell-specific manner by sweeping through one or more angular regions in a cell. In another aspect, the SIB may be transmitted via an ePBCH. In another aspect, the SIB may be transmitted via a PDCCH or a PDSCH. In another configuration, the transmission component <NUM> may be configured to transmit at least a subset of the determined RACH parameters during a RACH procedure. In an aspect, the PBCH may be frequency-division multiplexed with initial access signals, or the PBCH may be time-division multiplexed with the initial access signals. In another aspect, the initial access signals may include one or more of a primary synchronization sequence, a secondary synchronization sequence, an extended synchronization sequence, and beam reference signals.

<FIG> is a diagram <NUM> illustrating an example of a hardware implementation for an apparatus <NUM>' employing a processing system <NUM>. The processing system <NUM> may be implemented with a bus architecture, represented generally by the bus <NUM>. The bus <NUM> may include any number of interconnecting buses and bridges depending on the specific application of the processing system <NUM> and the overall design constraints. The bus <NUM> links together various circuits including one or more processors and/or hardware components, represented by the processor <NUM>, the components <NUM>, <NUM>, <NUM>, and the computer-readable medium / memory <NUM>. The bus <NUM> may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system <NUM> may be coupled to a transceiver <NUM>. The transceiver <NUM> is coupled to one or more antennas <NUM>. The transceiver <NUM> provides a means for communicating with various other apparatus over a transmission medium. The transceiver <NUM> receives a signal from the one or more antennas <NUM>, extracts information from the received signal, and provides the extracted information to the processing system <NUM>, specifically the reception component <NUM>. In addition, the transceiver <NUM> receives information from the processing system <NUM>, specifically the transmission component <NUM>, and based on the received information, generates a signal to be applied to the one or more antennas <NUM>. The processing system <NUM> includes a processor <NUM> coupled to a computer-readable medium / memory <NUM>. The processor <NUM> is responsible for general processing, including the execution of software stored on the computer-readable medium / memory <NUM>. The software, when executed by the processor <NUM>, causes the processing system <NUM> to perform the various functions described supra for any particular apparatus. The computer-readable medium / memory <NUM> may also be used for storing data that is manipulated by the processor <NUM> when executing software. The processing system <NUM> further includes at least one of the components <NUM>, <NUM>, <NUM>. The components may be software components running in the processor <NUM>, resident/stored in the computer readable medium / memory <NUM>, one or more hardware components coupled to the processor <NUM>, or some combination thereof. The processing system <NUM> may be a component of the eNB <NUM> (or the mmW base station <NUM>) and may include the memory <NUM> and/or at least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM>.

In one configuration, the apparatus <NUM>/<NUM>' for wireless communication includes means for determining RACH parameters. The apparatus may include means for transmitting a message that includes RACH information, based on the determined RACH parameters, via a PBCH. In an aspect, the message that includes RACH information may be transmitted using beamforming. In another aspect, the message may be beam-formed in a cell-specific manner by sweeping through one or more angular regions in a cell during different time units. In another aspect, the RACH parameters may include a beam sweep periodicity, a RACH preamble index, a RACH configuration, a RACH format, a RACH periodicity, a base station transmit power, and a RACH power ramping step. In another aspect, the RACH information may be a subset of the RACH parameters. In one configuration, the apparatus may include means for transmitting via the PBCH an indication of whether the determined RACH parameters are to be transmitted via an ePBCH. In an aspect, the RACH information may be transmitted via the PBCH based on whether the determined RACH parameters are to be transmitted via the ePBCH. In another configuration, the apparatus may include means for transmitting via the PBCH an indication of a periodicity with which the determined RACH parameters are to be transmitted via an ePBCH. In another configuration, the apparatus may include means for transmitting at least a subset of the determined RACH parameters via a SIB. In an aspect, the at least the subset of the determined RACH parameters may be transmitted in a cell-specific manner by sweeping through one or more angular regions in a cell. In another aspect, the SIB may be transmitted via an ePBCH. In another aspect, the SIB may be transmitted via a PDCCH or a PDSCH. In another configuration, the apparatus may include means for transmitting at least a subset of the determined RACH parameters during a RACH procedure. In an aspect, the PBCH may be frequency-division multiplexed with initial access signals, or the PBCH may be time-division multiplexed with the initial access signals. In another aspect, the initial access signals may include one or more of a primary synchronization sequence, a secondary synchronization sequence, an extended synchronization sequence, and beam reference signals.

<FIG> is a conceptual data flow diagram <NUM> illustrating the data flow between different means/components in an exemplary apparatus <NUM>. The apparatus may be a UE. The apparatus includes a reception component <NUM>, a RACH component <NUM>, and a transmission component <NUM>. The reception component <NUM> may be configured to receive a message that includes RACH information associated with a base station <NUM> via a PBCH. The transmission component <NUM> may be configured to transmit a RACH message to the base station <NUM> during a RACH procedure based on the received RACH information. In an aspect, the RACH information may be a subset of RACH parameters associated with the base station <NUM>. The RACH parameters may include a beam sweep periodicity, a RACH preamble index, a RACH configuration, a RACH format, a RACH frequency, a base station transmit power, and a RACH power ramping step. In one configuration, the reception component <NUM> may be configured to receive via the PBCH an indication of whether the RACH parameters are to be transmitted via an ePBCH. In another aspect, the RACH information may be received based on whether the RACH parameters are to be transmitted via the ePBCH. In another aspect, the RACH message may be transmitted during the RACH procedure based on the RACH information if the RACH parameters will not be transmitted via the ePBCH. In another aspect, the RACH message may be transmitted during the RACH procedure based on a periodicity with which the RACH parameters are to be received in the ePBCH. In another configuration, the reception component <NUM> may be configured to receive via the PBCH an indication of a periodicity with which the RACH parameters are to be transmitted via an ePBCH. In another configuration, the reception component <NUM> may be configured to receive at least a subset of the RACH parameters via a SIB. In an aspect, the SIB may be received via an ePBCH. In another aspect, the SIB may be received via a PDCCH or a PDSCH. In another configuration, the reception component <NUM> may be configured to receive at least a subset of the RACH parameters during a RACH procedure. In an aspect, the RACH message may be transmitted to the base station <NUM> before the apparatus receives a SIB from the base station <NUM> via a PDCCH, a PDSCH, or an ePBCH. In another aspect, the message that includes RACH information may be beamformed.

The processing system <NUM> may be coupled to a transceiver <NUM>. The transceiver <NUM> is coupled to one or more antennas <NUM>. The transceiver <NUM> provides a means for communicating with various other apparatus over a transmission medium. The transceiver <NUM> receives a signal from the one or more antennas <NUM>, extracts information from the received signal, and provides the extracted information to the processing system <NUM>, specifically the reception component <NUM>. In addition, the transceiver <NUM> receives information from the processing system <NUM>, specifically the transmission component <NUM>, and based on the received information, generates a signal to be applied to the one or more antennas <NUM>. The processing system <NUM> includes a processor <NUM> coupled to a computer-readable medium / memory <NUM>. The processor <NUM> is responsible for general processing, including the execution of software stored on the computer-readable medium / memory <NUM>. The software, when executed by the processor <NUM>, causes the processing system <NUM> to perform the various functions described supra for any particular apparatus. The computer-readable medium / memory <NUM> may also be used for storing data that is manipulated by the processor <NUM> when executing software. The processing system <NUM> further includes at least one of the components <NUM>, <NUM>, <NUM>. The components may be software components running in the processor <NUM>, resident/stored in the computer readable medium / memory <NUM>, one or more hardware components coupled to the processor <NUM>, or some combination thereof. The processing system <NUM> may be a component of the UE <NUM> and may include the memory <NUM> and/or at least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM>.

In one configuration, the apparatus <NUM>/<NUM>' for wireless communication includes means for receiving a message that includes RACH information associated with a base station via a PBCH. The apparatus includes means for transmitting a RACH message to the base station during a RACH procedure based on the received RACH information. In an aspect, the RACH information may be a subset of RACH parameters associated with the base station. The RACH parameters may include a beam sweep periodicity, a RACH preamble index, a RACH configuration, a RACH format, a RACH frequency, a base station transmit power, and a RACH power ramping step. In one configuration, the apparatus may include means for receiving via the PBCH an indication of whether the RACH parameters are to be transmitted via an ePBCH. In another aspect, the RACH information may be received based on whether the RACH parameters are to be transmitted via the ePBCH. In another aspect, the RACH message may be transmitted during the RACH procedure based on the RACH information if the RACH parameters will not be transmitted via the ePBCH. In another aspect, the RACH message may be transmitted during the RACH procedure based on a periodicity with which the RACH parameters are to be received in the ePBCH. In another configuration, the apparatus may include means for receiving via the PBCH an indication of a periodicity with which the RACH parameters are to be transmitted via an ePBCH. In another configuration, the apparatus may include means for receiving at least a subset of the RACH parameters via a SIB. In an aspect, the SIB may be received via an ePBCH. In another aspect, the SIB may be received via a PDCCH or a PDSCH. In another configuration, the apparatus may include means for receiving at least a subset of the RACH parameters during a RACH procedure. In an aspect, the RACH message may be transmitted to the base station before the apparatus receives a SIB from the base station via a PDCCH, a PDSCH, or an ePBCH. In another aspect, the message that includes RACH information may be beamformed.

Claim 1:
A method of wireless communication by a base station (<NUM>), comprising:
determining random access channel, RACH, parameters:
transmitting a message that includes RACH information via a physical broadcast channel, PBCH, wherein the RACH information comprises a subset of the determined RACH parameters including at least one of a beam sweep periodicity, a base station transmit power, a RACH preamble index, a RACH configuration, a RACH frequency, or a RACH power ramping step;
characterized by:
receiving a RACH message (<NUM>) from a user equipment, UE, (<NUM>) during a RACH procedure based on the transmitted RACH information, wherein the RACH message is received before transmitting, by the base station, remaining RACH parameters via an extended PBCH, ePBCH, wherein the remaining RACH parameters are the determined RACH parameters not including those that make up the RACH information.