Patent Description:
Wireless communication systems are widely deployed to provide various types of communications such as voice, data, video, etc. These systems may be multiple-access systems capable of supporting communication with multiple access terminals by sharing available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems.

Typically, a wireless communication network comprises several base stations (BSs), wherein each BS communicates with a mobile station or user equipment (UE) using a forward link and each mobile station (or access terminal) communicates with base station(s) using a reverse link. A UE may synchronize to a network for initial cell access by performing a random access procedure, which may include a number of messages (e.g., about <NUM>) exchange between the UE and a BS. Thus, there is a latency in establishing a connection with the network. After the UE establishes a connection with the network, the UE may move from one cell coverage area to another cell coverage area. When the UE moved out of a current serving cell coverage area, a handover process may be performed to enable the UE to continue communication with the network under a different cell coverage area. Typically, UE mobility management is supported through a downlink (DL)-based mobility approach, where the network sends references signals (RSs) and the UE performs cell search and measurements based on the RSs. Cell search and measurements consume power at the UE, as evident from 3GPP R1-<NUM>. Thus, a more efficient random access procedure and mobility support may benefit wireless communication. <NPL>, and with non-patent literature reference number XP051082641, discloses that one simplification to the legacy LAA random access procedure in <NUM> steps would be to transmit the information which is carried in msg3 (such as RRC Connection Request) along with msg1 (i.e. RACH preamble). Similarly, the current msg2 and msg4 can be combined to a single message. In this case, for example, RRC Connection Setup can be completed in two steps, in order to reduce latency in the RACH procedure.

Embodiments of the present disclosure provide mechanisms for random access and UL-based mobility that can reduce random access latency. A UE simultaneously transmits a signal including a random access preamble and data in a single transmission. The data includes a connection request message during an initial network access or, in an example which does not fall within the scope of the claims, may include UE identifier information during a UL-based mobility procedure. A BS responds to the signal by including a random access response and a connection response in a single transmission during an initial network access or, in an example which does not fall within the scope of the claims, including an acknowledgement and paging information in a single transmission.

Apart from <FIG> all of the remaining figures are only used for illustrative purposes, aspects depicted therein which do not fall within the scope of the claims are merely examples used for explanation of the invention.

The techniques described herein may be used for various wireless communication networks such as code-division multiple access (CDMA), time-division multiple access (TDMA), frequency-division multiple access (FDMA), orthogonal frequency-division multiple access (OFDMA), single-carrier FDMA (SC-FDMA) and other networks. An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies, such as a next generation (e.g., <NUM>th Generation (<NUM>)) network.

The present disclosure describes an improved random access procedure and UL-based mobility. UL-based mobility refers to a network performing UE search and/or measurements based on reference signals transmitted by UEs. In the disclosed embodiments, a UE may simultaneously transmit a random access preamble and data in a single transmission. For random access, the UE may simultaneously transmit a random access preamble and a connection request message (e.g., the data) instead of separately, and thus may reduce random access latency. For UL-based mobility, when the UE is in a RRC common state, the UE may transmit a random access preamble and a UE-identifier (ID) (e.g., the data) that identifies the UE in the network. Upon detecting the random access preamble and the UE-ID, a BS or a transmission/reception point (TRP) may transmit an acknowledgement (ACK) to the UE and may include paging information. When the UE is in a RRC dedicated state, the UE may send a UL mobility reference signal and the BS may transmit an ACK to the UE and may include handover information. The disclosed embodiments define an ePRACH and a PUMICH in a UL-centric self-contained subframe for carrying both a random access preamble and data for random access and UL-based mobility, respectively. In addition, the disclosed embodiments defined a PUMRS channel in a UL-centric self-contained subframe for carrying a UL mobility reference signal.

<FIG> illustrates a wireless communication network <NUM> according to embodiments of the present disclosure. The network <NUM> may include a number of UEs <NUM>, as well as a number of BSs <NUM>. The BSs <NUM> may include an Evolve Node B (eNodeB). A BS <NUM> may be a station that communicates with the UEs <NUM> and may also be referred to as a base transceiver station, a node B, an access point, and the like.

The BSs <NUM> communicate with the UEs <NUM> as indicated by communication signals <NUM>. A UE <NUM> may communicate with the BS <NUM> via an uplink (UL) and a downlink (DL). The downlink (or forward link) refers to the communication link from the BS <NUM> to the UE <NUM>. The UL (or reverse link) refers to the communication link from the UE <NUM> to the BS <NUM>. The BSs <NUM> may also communicate with one another, directly or indirectly, over wired and/or wireless connections, as indicated by communication signals <NUM>.

The UEs <NUM> may be dispersed throughout the network <NUM>, as shown, and each UE <NUM> may be stationary or mobile. The UE <NUM> may also be referred to as a terminal, a mobile station, a subscriber unit, etc. The UE <NUM> may be a cellular phone, a smartphone, a personal digital assistant, a wireless modem, a laptop computer, a tablet computer, an IoT device, etc. The network <NUM> is one example of a network to which various aspects of the disclosure apply.

Each BS <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to this particular geographic coverage area of a BS and/or a BS subsystem serving the coverage area, depending on the context in which the term is used. In this regard, a BS <NUM> may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cell. A pico cell may generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A femto cell may also generally cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, may also provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home, and the like).

In the example shown in <FIG>, the BSs 104a, 104b and 104c are examples of macro BSs for the coverage areas 110a, 110b and 110c, respectively. The BSs 104d and 104e are examples of pico and/or femto BSs for the coverage areas 110d and 110e, respectively. As will be recognized, a BS <NUM> may support one or multiple (e.g., two, three, four, and the like) cells.

The network <NUM> may also include relay stations. A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., a BS, a UE, or the like) and sends a transmission of the data and/or other information to a downstream station (e.g., another UE, another BS, or the like). A relay station may also be referred to as a relay BS, a relay UE, a relay, and the like.

For synchronous operation, the BSs <NUM> may have similar frame timing, and transmissions from different BSs <NUM> may be approximately aligned in time. For asynchronous operation, the BSs <NUM> may have different frame timing, and transmissions from different BSs <NUM> may not be aligned in time.

In some implementations, the network <NUM> utilizes orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the UL. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, or the like. Each subcarrier may be modulated with data. For example, K may be equal to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> for a corresponding system bandwidth of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> megahertz (MHz), respectively. The system bandwidth may also be partitioned into sub-bands. For example, a sub-band may cover <NUM>, and there may be <NUM>, <NUM>, <NUM>, <NUM> or <NUM> sub-bands for a corresponding system bandwidth of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, respectively.

In an embodiment, the BSs <NUM> can assign or schedule transmission resources (e.g., in the form of time-frequency resource blocks) for DL and UL transmissions in the network <NUM>. The communication can be in the form of radio frames. A radio frame may be divided into a plurality of subframes. In a FDD mode, simultaneous UL and DL transmissions may occur in different frequency bands. In a TDD mode, UL and DL transmissions occur at different time periods using the same frequency band. For example, a subset of the subframes in a radio frame may be used for DL transmissions and another subset of the subframes may be used for UL transmissions. The DL and UL subframes can be shared among the BSs <NUM> and the UEs <NUM>, respectively.

The DL subframes and the UL subframes can be further divided into several regions. For example, each DL or UL subframe may have pre-defined regions for transmissions of reference signals, control information, and data. Reference signals are pre-determined signals that facilitate the communications between the BSs <NUM> and the UEs <NUM>. For example, a reference signal can have a particular pilot pattern or structure, where pilot tones may span across an operational bandwidth or frequency band, each positioned at a pre-defined time and a pre-defined frequency. Control information may include resource assignments and protocol controls. Data may include protocol data and/or operational data.

In an embodiment, the BSs <NUM> can broadcast system information associated with the network <NUM>. Some examples of system information may include physical layer information such as cell bandwidths and frame configurations, cell access information, and neighbor cell information. A UE <NUM> can access the network <NUM> by listening to the broadcast system information and requests connection or channel establishments with a BS <NUM>. For example, the UE <NUM> can perform a random access procedure to begin communication with the BS <NUM> and subsequently may perform connection and/or registration procedures to register with the BS <NUM>. After completing the connection and/or the registration, the UE <NUM> and the BS <NUM> can enter a normal operation stage, where operational data may be exchanged.

<FIG> illustrates a subframe configuration <NUM> according to embodiments of the present disclosure. The configuration <NUM> may be employed by the BSs <NUM> and the UEs <NUM> for transmission. In <FIG>, the x-axis represents time in some constant units and the y-axis represents frequency in some constant units. The configuration <NUM> shows two self-contained subframes <NUM> and <NUM>. The subframes <NUM> and <NUM> can be configured for UL transmission or DL transmission. As an example, the subframe <NUM> is configured for UL transmission and the subframe <NUM> is configured for DL transmission. Thus, the subframe <NUM> may be referred to as a UL-centric subframe and the subframe <NUM> may be referred to as a DL-centric subframe. The subframe <NUM> includes a DL control portion <NUM> for carrying DL control, a UL data portion <NUM> for carrying UL data, and a UL control portion <NUM> for carrying UL control. The subframe <NUM> includes a DL control portion <NUM> for carrying DL control, a DL data portion <NUM> for carrying DL data, and a UL control portion <NUM> for carrying UL control. As shown, the subframe <NUM> further includes s a guard band <NUM> between the DL control portion <NUM> and the UL data portion <NUM>. The subframe <NUM> further includes s a guard band <NUM> between the DL data portion <NUM> and the UL control portion <NUM>. The guard bands <NUM> and <NUM> allow for switching between transmit and receive.

<FIG> illustrates a UE RRC state diagram <NUM>, which is an example explaining the invention. The RRC state diagram <NUM> shows the RRC states of the UE <NUM> after completing an initial radio access network (RAN) or cell access. As shown, the UE <NUM> may transitions between a RRC dedicated state <NUM>, a RRC common state <NUM>, a reachable idle state <NUM>, and a power saving state <NUM>. In the RRC dedicated state <NUM>, the UE <NUM> context is known to the RAN. The UE <NUM> may be assigned with air interface resources (e.g., physical resources). The UE <NUM> may transmit and receive any data. The UE <NUM> may transition from the RRC dedicated state <NUM> to the RRC common state <NUM> due to inactivity.

In the RRC common state <NUM>, the UE <NUM> context is known to the RAN. The UE <NUM> has no assigned air interface resources. The UE <NUM> may transmit and receive a small amount of data. The UE <NUM> may transition from the RRC common state <NUM> to the RRC dedicated state <NUM> when a nominal amount of data reception or transmission occurs. The UE <NUM> may transition to from the RRC common state <NUM> to the reachable idle state <NUM> due to inactivity. When the UE <NUM> is in the RRC dedicated state <NUM> or the RRC common state <NUM>, the UE <NUM> is in a connected mode.

In the reachable idle state <NUM>, the context of the UE <NUM> is not known to the RAN. The UE <NUM> has no assigned air interface resources. The UE <NUM> may transmit and receive a small amount of data. The UE <NUM> may transition from the reachable idle state <NUM> to the RRC dedicated state <NUM> when a nominal amount of data reception or transmission occurs. The UE <NUM> may transition from the reachable idle state <NUM> to the power saving state <NUM> when a reachability timer expires.

In the power saving state <NUM>, the context of the UE <NUM> is not known to the RAN. The UE <NUM> has no assigned air interface resources. The UE <NUM> has no data transmission or reception. The UE <NUM> may transition from the power saving state <NUM> to the reachability idle state <NUM> upon any data transmission or reception. When the UE <NUM> is in the reachability idle state <NUM> or the power saving state <NUM>, the UE <NUM> is in an idle mode.

<FIG> illustrates a wireless communication network <NUM> that implements UL-based mobility according to embodiments of the present disclosure. <FIG> illustrates one transmission/reception point (TRP) <NUM> and one UE <NUM> for purposes of simplicity of discussion, though it will be recognized that embodiments of the present disclosure may scale to many more UEs <NUM> and/or TRPs <NUM>. The TRP <NUM> may be substantially similar to the BSs <NUM>, but may include remote radio heads for wireless signal transmission and reception and may communicate with a central unit for baseband processing. The UEs <NUM> may be substantially similar to the UEs <NUM>. The UE <NUM> and the TRP <NUM> may communicate with each other at any suitable frequencies.

The network <NUM> includes a plurality of zones <NUM>. A zone <NUM> is a collection of tightly synchronized cells. As shown, the zone 410a includes the zone 410b where the TRP <NUM> is located and a cluster of cells <NUM> serving the UE <NUM>. To support UL-based intra-zone mobility, for example, within the zone 410a, the UE <NUM> may send UL mobility RSs for mobility tracking at the network side. For example, the TRP <NUM> may perform UE search and measurements based on the RSs sent by the UE <NUM>. The TRP <NUM> may acknowledge the UL mobility RSs and signal paging indicator, as described in greater detail herein. The network <NUM> may autonomously selects a serving cell <NUM> (e.g., a TRP) or cells <NUM> (e.g., TRPs) to send the acknowledgement (ACK). Thus, intra-zone mobility may be transparent to the UE <NUM>. For inter-zone mobility, for example, from the zone 410a to the zone 410b, the UE <NUM> may perform handover when a pre-determined condition is satisfied.

UL-based mobility provides several benefits. For example, power consumption may be reliably tradeoff at a UE. The handshake at the physical layer (e.g., layer <NUM> (L1)) may be more efficient, and thus may provide UEs and the network with channel information in a shorter amount of time than DL-based mobility. In addition, UL-based mobility may provide better mobility tracking since the network may have more antennas than UEs. UL-based mobility may benefit high mobility or poor channel conditions. For example, UL-based mobility may reduce UE power consumption, improve paging miss and call set up delay, improve network resource utilization efficiency, and reduce handover failure rate.

<FIG> is a block diagram of an exemplary UE <NUM> according to embodiments of the present disclosure. The UE <NUM> may be a UE <NUM> as discussed above. As shown, the UE <NUM> may include a processor <NUM>, a memory <NUM>, a random access (RACH) and UL mobility processing module <NUM>, a transceiver <NUM> including a modem subsystem <NUM> and a RF unit <NUM>, and an antenna <NUM>. These elements may be in direct or indirect communication with each other, for example via one or more buses or other communication mediums.

The processor <NUM> may include a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

The memory <NUM> may include a cache memory (e.g., a cache memory of the processor <NUM>), random access memory (RAM), magnetoresistive RAM (MRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, solid state memory device, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an embodiment, the memory <NUM> includes a non-transitory computer-readable medium. The instructions <NUM> may include instructions that, when executed by the processor <NUM>, cause the processor <NUM> to perform the operations described herein with reference to the UEs <NUM> in connection with embodiments of the present disclosure. Instructions <NUM> may also be referred to as code. The terms "instructions" and "code" should be interpreted broadly to include any type of computer-readable statement(s). For example, the terms "instructions" and "code" may refer to one or more programs, routines, subroutines, functions, procedures, etc. "Instructions" and "code" may include a single computer-readable statement or many computer-readable statements.

The RACH and UL mobility processing module <NUM> may be implemented via hardware, software, or combinations thereof. For example, the RACH and UL mobility processing module <NUM> may be implemented as a processor, circuit, and/or instructions <NUM> stored in the memory <NUM> and executed by the processor <NUM>. The RACH and UL mobility processing module <NUM> may be used for various aspects of the present disclosure. For example, the RACH and UL mobility processing module <NUM> is configured to perform RACH and facilitate UL mobility, as described in greater detail herein.

As shown, the transceiver <NUM> may include the modem subsystem <NUM> and the RF unit <NUM>. The transceiver <NUM> can be configured to communicate bi-directionally with other devices, such as the BSs <NUM>. The modem subsystem <NUM> may be configured to modulate and/or encode the data from the memory <NUM> and/or the RACH and UL mobility processing module <NUM> according to a modulation and coding scheme (MCS), e.g., a low-density parity check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit <NUM> may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated/encoded data from the modem subsystem <NUM> (on outbound transmissions) or of transmissions originating from another source such as a UE <NUM> or a BS <NUM>. Although shown as integrated together in transceiver <NUM>, the modem subsystem <NUM> and the RF unit <NUM> may be separate devices that are coupled together at the UE <NUM> to enable the UE <NUM> to communicate with other devices.

The RF unit <NUM> may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information), to the antenna <NUM> for transmission to one or more other devices. The antenna <NUM> may further receive data messages transmitted from other devices. This may include, for example, transmission and reception of signals associated with RACH and UL mobility according to embodiments of the present disclosure. The antenna <NUM> may provide the received data messages for processing and/or demodulation at the transceiver <NUM>. Although <FIG> illustrates antenna <NUM> as a single antenna, antenna <NUM> may include multiple antennas of similar or different designs in order to sustain multiple transmission links. The RF unit <NUM> may configure the antenna <NUM>.

<FIG> is a block diagram of an exemplary BS <NUM> according to embodiments of the present disclosure. The BS <NUM> may be a BS <NUM> as discussed above. As shown, the BS <NUM> may include a processor <NUM>, a memory <NUM>, a RACH and UL mobility processing module <NUM>, a transceiver <NUM> including a modem subsystem <NUM> and a RF unit <NUM>, and an antenna <NUM>. These elements may be in direct or indirect communication with each other, for example via one or more buses.

The RACH and UL mobility processing module <NUM> may be implemented via hardware, software, or combinations thereof. For example, the RACH and UL mobility processing module <NUM> may be implemented as a processor, circuit, and/or instructions <NUM> stored in the memory <NUM> and executed by the processor <NUM>. The RACH and UL mobility processing module <NUM> may be used for various aspects of the present disclosure. For example, the RACH and UL mobility processing module <NUM> may perform RACH and support UL mobility, as described in greater detail herein.

As shown, the transceiver <NUM> may include the modem subsystem <NUM> and the RF unit <NUM>. The transceiver <NUM> can be configured to communicate bi-directionally with other devices, such as the UEs <NUM> and/or another core network element. The modem subsystem <NUM> may be configured to modulate and/or encode data according to a MCS, e.g., a LDPC coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit <NUM> may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc.) modulated/encoded data from the modem subsystem <NUM> (on outbound transmissions) or of transmissions originating from another source such as a UE <NUM>. Although shown as integrated together in transceiver <NUM>, the modem subsystem <NUM> and the RF unit <NUM> may be separate devices that are coupled together at the BS <NUM> to enable the BS <NUM> to communicate with other devices.

The RF unit <NUM> may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information), to the antenna <NUM> for transmission to one or more other devices. This may include, for example, transmission of information to complete attachment to a network and communication with a camped UE <NUM> according to embodiments of the present disclosure. The antenna <NUM> may further receive data messages transmitted from other devices and provide the received data messages for processing and/or demodulation at the transceiver <NUM>. Although <FIG> illustrates antenna <NUM> as a single antenna, antenna <NUM> may include multiple antennas of similar or different designs in order to sustain multiple transmission links.

<FIG> is a protocol diagram of a method <NUM> of a <NUM>-step random access procedure according to embodiments of the present disclosure. Steps of the method <NUM> can be executed by computing devices (e.g., a processor, processing circuit, and/or other suitable component) of wireless communication devices, such as the BSs <NUM> and <NUM>, the TRP <NUM>, and the UEs <NUM>, <NUM>, and <NUM>. The method <NUM> is suitable for use in any RRC states as described in the UE RRC state diagram <NUM>. The method <NUM> can be better understood with reference to <FIG>. The method <NUM> may employ similar mechanisms as in the network <NUM>. As illustrated, the method <NUM> includes a number of enumerated steps, but embodiments of the method <NUM> may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. The method <NUM> illustrates two TRPs 404a and 404b and one UE <NUM> for purposes of simplicity of discussion, though it will be recognized that embodiments of the present disclosure may scale to many more UEs <NUM> and/or TRPs <NUM>.

At step <NUM>, the UE <NUM> transmits a message <NUM> (MSG1), which may be referred to as a random access preamble. The UE <NUM> may transmit the MSG1 in a physical random access channel (PRACH). The random access preamble may be a Zadoff-Chu sequence, a gold sequence, a m-sequence or any suitable orthogonal sequence and may include cyclic shifts. In some embodiments, the MSG1 may also reach the TRP 404b as shown by the arrows in the dashed oval.

At step <NUM>, upon detecting the MSG1, the TRP 404a transmits a message <NUM> (MSG2), which may be referred to as a random access response (RAR). The TRP 404a may transmit allocation information for the MSG2 in a physical downlink control channel (PDCCH) and the MSG2 in a physical downlink shared channel (PDSCH). The MSG2 may include a detected random access preamble identifier (ID), timing advance (TA) information, a UL grant, a temporary cell-radio network temporary identifier (C-RNTI), and a backoff indicator. In some embodiments, the TRP 404b may also detect the MSG1 and may respond with a MSG2 as shown by the dashed arrow.

At step <NUM>, the UE <NUM> transmits a message <NUM> (MSG3) based on the MSG2. The UE <NUM> may transmit the MSG3 in a physical uplink shared channel (PUSCH). The MSG3 may include a RRC connection request, a tracking area update, and a scheduling request.

At step <NUM>, the TRP 404a transmits a message <NUM> (MSG4). The TRP 404a may transmit allocation information for the MSG4 in a PDCCH and the MSG4 in a PDSCH. The MSG4 includes a contention resolution. The PRACH and the PUSCH are sent in a UL-centric subframe (e.g., the subframe <NUM>), as described in greater detail herein. The PRACH and the PUSCH may have the same numerology (e.g., a tone spacing of <NUM>) or different numerologies.

<FIG> illustrates a subframe <NUM> that includes a PRACH <NUM> according to the present disclosure. The subframe <NUM> is employed by the UE <NUM> when implementing the <NUM>-step random access procedure described in the method <NUM>. In <FIG>, the x-axis represents time in some constant units and the y-axis represents frequency in some constant units. The subframe <NUM> is a UL-centric subframe and has a similar structure as the subframe <NUM>. The subframe <NUM> may carry a DL common burst, a UL regular burst, and a UL common burst in a DL control portion <NUM>, a UL data portion <NUM>, and a UL control portion <NUM>. As shown, the subframe <NUM> carriers the PRACH <NUM> in the UL data portion <NUM>. In some embodiments, the position of the PRACH <NUM> may be configurable. For example, the PRACH <NUM> may be in both the UL data portion <NUM> and the UL control portion <NUM>. In addition, the PRACH <NUM> may span more than one subframe <NUM>.

<FIG> is a protocol diagram of a method <NUM> of performing a <NUM>-step random access according to embodiments of the present disclosure. Steps of the method <NUM> can be executed by computing devices (e.g., a processor, processing circuit, and/or other suitable component) of wireless communication devices, such as the BSs <NUM> and <NUM>, the TRP <NUM>, and the UEs <NUM>, <NUM>, and <NUM>. The method <NUM> is suitable for use when a UE is in a RRC common state (e.g., the RRC common state <NUM>). The method <NUM> can be better understood with reference to <FIG>. The method <NUM> may employ similar mechanisms as in the network <NUM>. As illustrated, the method <NUM> includes a number of enumerated steps, but embodiments of the method <NUM> may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. The method <NUM> illustrates two TRPs 404a and 404b and one UE <NUM> for purposes of simplicity of discussion, though it will be recognized that embodiments of the present disclosure may scale to many more UEs <NUM> and/or TRPs <NUM>.

At step <NUM>, the UE <NUM> transmits an enhanced message <NUM> (eMSG1), which includes the MSG1 and the MSG3 of the method <NUM>. The UE <NUM> may transmit the eMSG1 in an enhanced physical random access channel (ePRACH). The ePRACH includes PUSCHs and a PRACH, as described in greater detail herein. The eMSG1 may include a random access preamble, a RRC connection request, a tracking area update, a scheduling request, and a UE identifier (UE-ID). For example, the PRACH is transmitted in the PRACH of the ePRACH and the remaining eMSG1 is transmitted in the PUSCHs of the ePRACH. In some embodiments, the eMSG1 may also reach the TRP 404b as shown by the arrows in the dashed oval.

At step <NUM>, upon detecting the eMSG1, the TRP 404a transmits an enhanced message <NUM> (eMSG2), which includes the MSG2 and MSG4 of the method <NUM>. The TRP 404a may transmit allocation information for the eMSG2 in a PDCCH and the eMSG2 in a PDSCH. The eMSG2 may include a detected random access preamble ID, TA information, a C-RNTI, a backoff indicator, and a contention resolution. In some embodiments, the TRP 404b may also detect the eMSG1 and may respond with an eMSG2 as shown by the dashed arrow.

As shown, the method <NUM> requires two steps instead of four steps as in the method <NUM>. Thus, the method <NUM> may reduce latency for random access. The method <NUM> is suitable for small-cell deployments or in unlicensed bands.

<FIG> illustrates a subframe <NUM> that includes an ePRACH <NUM> according to the present disclosure. The subframe <NUM> is employed by the UE <NUM> when implementing the <NUM>-step random access procedure described in the method <NUM>. In <FIG>, the x-axis represents time in some constant units and the y-axis represents frequency in some constant units. The subframe <NUM> is a UL-centric subframe and has a similar structure as the subframe <NUM>. The subframe <NUM> may carry a DL common burst, a UL regular burst, and a UL common burst in a DL control portion <NUM>, a UL data portion <NUM>, and a UL control portion <NUM>. As shown, the subframe <NUM> carries the ePRACH <NUM> in the UL data portion <NUM>.

The ePRACH <NUM> includes a plurality of PUSCHs <NUM>, a PRACH <NUM>, and a guard band <NUM> at the end of the ePRACH <NUM>. The PRACH <NUM> carries a random access preamble of an eMSG1 and the PUSCHs <NUM> carry remaining portions of the eMSG1. Each of the PUSCHs <NUM> and the PRACH <NUM> includes a cyclic prefix (CP) portion <NUM>. Each of the PUSCHs <NUM> and the PRACH <NUM> may span a duration of one symbol. For example, each of the PUSCHs <NUM> and the PRACH <NUM> may be configured to have a tone spacing of about <NUM> with about <NUM> tones, a symbol duration of about <NUM> microseconds (µs), and a CP duration of about <NUM>.

In an embodiment, the PRACH <NUM> may be used as a reference signal for demodulation at the TRP <NUM>. The PRACH <NUM> is configured to be about the center of the ePRACH <NUM> to provide better performance. Thus, the random access preamble may also be referred to as a random access mid-amble. The PUSCHs <NUM> and the PRACH <NUM> may have the same numerology or different numerologies. For example, a network may broadcast the configuration or numerology of the ePRACH <NUM>. In an embodiment, the tone spacing of the PRACH <NUM> are configured such that the PRACH <NUM> may accommodate a selected random access preamble length. For example, a random access preamble length may be selected by dimensioning cyclic shifts based on channel conditions. Although the PUSCHs <NUM> and PRACH <NUM> are shown as time-division multiplexed, the PUSCHs <NUM> and the PRACH <NUM> may be frequency-division multiplexed. The time-multiplexed PUSCHs <NUM> and the PRACH <NUM> may be transmitted over the same antenna ports, which may be mapped to one or more physical antennas such as the antennas <NUM>.

<FIG> is a protocol diagram of a method <NUM> of performing UL mobility in a RRC common state (e.g., the RRC common state <NUM>) according to embodiments of the present disclosure. Steps of the method <NUM> can be executed by computing devices (e.g., a processor, processing circuit, and/or other suitable component) of wireless communication devices, such as the BSs <NUM> and <NUM>, the TRP <NUM>, and the UEs <NUM>, <NUM>, and <NUM>. The method <NUM> can be better understood with reference to <FIG>. The method <NUM> may employ similar mechanisms as in the network <NUM>. As illustrated, the method <NUM> includes a number of enumerated steps, but embodiments of the method <NUM> may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. The method <NUM> illustrates two TRPs 404a and 404b and one UE <NUM> for purposes of simplicity of discussion, though it will be recognized that embodiments of the present disclosure may scale to many more UEs <NUM> and/or TRPs <NUM>.

For example, the UE <NUM> has obtained a UE-ID after establishing a connection with the network and is in a RRC common state. At step <NUM>, the UE <NUM> transmits a RRC common state UL mobility signal including a UE-ID of the UE <NUM> and a random access preamble. The random access preamble may be similar to the random access preamble in the methods <NUM> and <NUM>. When the UE <NUM> is in the RRC common state, the context (e.g., the UE-ID) of the UE <NUM> is saved in the network, but the UE <NUM> is not assigned with any air interface resource. Thus, UE <NUM> transmits the random access preamble to access the network and the UE-ID identifies the sender of the random access preamble as the UE <NUM>. The UE <NUM> may transmit the UL mobility signal in a PUMICH. The PUMICH includes PUSCHs and a PRACH, as described in greater detail herein. For example, the random access preamble is transmitted in the PRACH and the UE-ID is transmitted in the PUSCHs. In some embodiments, the RRC common state UL mobility signal may also reach the TRP 404b as shown by the arrows in the dashed oval.

At step <NUM>, upon detecting the UE-ID and the random access preamble, the TRP 404a transmits a UL mobility response signal including a PUMICH ACK and a paging indicator to the UE <NUM>. The TRP 404a may transmit the UL mobility response signal in a physical keep alive channel (PKACH). The PUMICH ACK may have a length of one bit. For example, a bit-value of <NUM> indicates an acknowledgement (ACK) of a successful reception of the PUMICH and a bit-value of <NUM> indicates a not-ACK (NACK) that the PUMICH is received with error. When the UE <NUM> fails to receive an ACK, the UE <NUM> may perform power control, for example, to increase the transmit power, for a next UL mobility signal transmission. In an embodiment, when the UE <NUM> is in the RRC common state, the UE <NUM> may transmit the UL mobility signal periodically, for example, at every <NUM> second (sec) and the TRP 404a may transmit a paging indicator along with the PUMICH ACK. Thus, the transmission of PUMICH facilitates UL mobility management and UE paging indicator polling.

<FIG> illustrates a subframe <NUM> that includes a PUMICH <NUM> according to the present disclosure. The subframe <NUM> is employed by the UE <NUM> when implementing the UL mobility procedure described in the method <NUM>. In <FIG>, the x-axis represents time in some constant units and the y-axis represents frequency in some constant units. The subframe <NUM> is similar to the subframe <NUM>, but includes the PUMICH <NUM> instead of the ePRACH <NUM>. As shown, the subframe <NUM> carries the PUMICH <NUM> in a UL data portion <NUM>. The position of the PUMICH <NUM> within the subframe <NUM> may be configurable. For example, a network may broadcast the configuration of the PUMICH <NUM>. The PUMICH <NUM> has a similar structure as the ePRACH <NUM>. For example, the PRACH <NUM> carries the random access preamble of the RRC common state UL mobility signal and the PUSCHs <NUM> carry the UE-ID of the RRC common state UL mobility signal of the method <NUM>.

<FIG> is a protocol diagram of a method <NUM> of performing UL mobility in a RRC dedicated state (e.g., the RRC dedicated state <NUM>) according to embodiments of the present disclosure. Steps of the method <NUM> can be executed by computing devices (e.g., a processor, processing circuit, and/or other suitable component) of wireless communication devices, such as the BSs <NUM> and <NUM>, the TRP <NUM>, and the UEs <NUM>, <NUM>, and <NUM>. The method <NUM> can be better understood with reference to <FIG>. The method <NUM> may employ similar mechanisms as in the network <NUM>. As illustrated, the method <NUM> includes a number of enumerated steps, but embodiments of the method <NUM> may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order. The method <NUM> illustrates two TRPs 404a and 404b and one UE <NUM> for purposes of simplicity of discussion, though it will be recognized that embodiments of the present disclosure may scale to many more UEs <NUM> and/or TRPs <NUM>.

For example, the UE <NUM> has obtained a UE-ID after establishing a connection with the network and is in a RRC dedicated state. At step <NUM>, the UE <NUM> transmits a UL mobility RS in a PUMRS channel, as described in greater detail herein. In an embodiment, the UL mobility RS includes a sounding reference signal (SRS) with an extended CP. The extended CP may enable the UL mobility RS to reach multiple TRPs. In some embodiments, the UE <NUM> may transmit the UL mobility RS in one or more transmit antenna ports that are the same or different from the regular SRS transmissions for sounding measurements. In some embodiments, the UL mobility RS may also reach the TRP 404b as shown by the arrows in the dashed oval.

At step <NUM>, the TRP 404a transmits a RRC dedicated UL mobility response signal in a PKACH. The network may perform mobility management based on the UL mobility RS. For example, the network may measure the receive signal strength of the UL mobility RS and tracks the mobility of the UE <NUM> based on the receive signal strength. In some embodiments, the network may determine to hand the UE <NUM> control over to another cell when the signal strength received from a current serving cell (e.g., the TRP 404a) is weak. Thus, the RRC dedicated UL mobility signal may include information associated with handover.

<FIG> illustrates a subframe <NUM> including a PUMRS channel <NUM> according to the present disclosure. The subframe <NUM> is employed by the UE <NUM> when implementing the UL mobility procedure described in the method <NUM>. In <FIG>, the x-axis represents time in some constant units and the y-axis represents frequency in some constant units. The subframe <NUM> has a similar structure as the subframes <NUM>, <NUM>, <NUM>, and <NUM> and includes the PUMRS channel <NUM>. As shown, the subframe <NUM> carries PUMRS channel <NUM> in a UL data portion <NUM>. The position of the PUMRS channel <NUM> within the UL data portion <NUM> may be configurable. For example, a network may broadcast the configuration of the PUMRS channel <NUM>. In an embodiment, the PUMRS channel <NUM> spans a time duration of one symbol. For example, the PUMRS channel <NUM> carries the UL mobility RS of the method <NUM>.

In an embodiment, the UL-based mobility mechanisms described in the methods <NUM> and <NUM> and the <NUM>-step random access mechanisms described in the method <NUM> are suitable for use in small-cell areas, for example, with a cell radius of less than about <NUM> kilometers (km). The network <NUM> may employ two sets of random access preamble sequences with cyclic shifts, one set for random access procedure and the other set for UL mobility. In an embodiment, each set may include <NUM> Zadoff-Chu sequences, gold sequences, m-sequences, or any suitable orthogonal sequences. The following table illustrates an example configuration for the PRACH <NUM> and the PUSCHs <NUM> of the ePRACH <NUM> or the PUMICH <NUM> with a bandwidth of <NUM>:.

A UE may transmit a random access preamble over multiple subframes (e.g., the subframes) based on link budget. The UE may transmit the random access preamble based on one numerology and the data based on another numerology when transmitting the eMSG1 or the RRC common state UL mobility signal. A BS or a TRP may utilize the random access preamble as a demodulation references signal to demodulate the data or the PUSCH.

In an embodiment, the random access procedure described above may be suitable for use is in large-cell deployment. The PRACH may be configured similar to the LTE PRACH in terms of random access preamble sequences (e.g., Zadoff-Chu with cyclic shifts), dimensioning of cyclic shifts such that delay spread and/or Doppler shift have minimal impacts on the RACH sequence cross-correlation. For example, the CP length may be dimensioned and a RACH sequence may be repeated to support different cell range requirements. The following table shows example PRACH formats and configurations:.

<FIG> is a flow diagram of a method <NUM> of performing UL-based mobility and random access according to embodiments of the present disclosure. Steps of the method <NUM> can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device, such as the UEs <NUM> and <NUM>. The method <NUM> may employ similar mechanisms as in the methods <NUM>, <NUM>, and <NUM>. The method <NUM> can be better understood with reference to <FIG>. As illustrated, the method <NUM> includes a number of enumerated steps, but embodiments of the method <NUM> may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

At step <NUM>, the method <NUM> includes transmitting a first signal carrying a random access preamble and data, for example, by a UE. At step <NUM>, the method includes receiving a second signal in response to the first signal. In an embodiment of random access, the first signal carries the eMSG1 as described in the method <NUM>, where the data may include at least one of a connection request, tracking area updated information, a scheduling request, or a UE-ID of the UE. The second signal may include at least one of a random access preamble ID of the random access preamble, timing advance information, backoff information, or a contention resolution.

In an embodiment UL-based mobility, the first signal carries the RRC common state UL mobility signal as described in the method <NUM>, where the data carries a UE-ID of the UE. The second signal may include at least one of an acknowledgement for the first signal or paging information.

<FIG> is a flow diagram of a method <NUM> of performing UL-based mobility and random access according to embodiments of the present disclosure. Steps of the method <NUM> can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device, such as the TRPs <NUM> and the BS <NUM>. The method <NUM> may employ similar mechanisms as in the methods <NUM>, <NUM>, and <NUM>. The method <NUM> can be better understood with reference to <FIG>. As illustrated, the method <NUM> includes a number of enumerated steps, but embodiments of the method <NUM> may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

At step <NUM>, the method <NUM> includes receiving a first signal carrying a random access preamble and data, for example, by a TRP. At step <NUM>, the method includes transmitting a second signal in response to the first signal. In an embodiment of random access, the first signal carries the eMSG1 as described in the method <NUM>, where the data may include at least one of a connection request, tracking area updated information, a scheduling request, or a UE-ID of the UE. The second signal may include at least one of a random access preamble ID of the random access preamble, timing advance information, backoff information, or a contention resolution.

Also, as used herein, including in the claims, "or" as used in a list of items (for example, a list of items prefaced by a phrase such as "at least one of" or "one or more of") indicates an inclusive list such that, for example, a list of [at least one of A, B, or C] means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

Claim 1:
A method of wireless communication in a network, comprising:
transmitting, by a user equipment, UE, a first signal carrying a random access preamble and a connection request message, the connection request message including a first and a second portion spaced apart in time by the random access preamble, wherein the transmitting comprises transmitting the random access preamble after the first portion of the connection request message and before the second portion of the connection request message; and
receiving, by the UE from a network device in response to the first signal, a second signal, including at least a random access response based on the random access preamble and a connection response based on the connection request message.