WO2018085726A1

WO2018085726A1 - Performing 2-step random access channel (rach) procedures

Info

Publication number: WO2018085726A1
Application number: PCT/US2017/060053
Authority: WO
Inventors: Seau Lim; Candy YIU; Umesh PHUYAL; Kyeongin Jeong; Youn Hyong HEO
Original assignee: Intel IP Corporation
Priority date: 2016-11-04
Filing date: 2017-11-03
Publication date: 2018-05-11

Abstract

Techniques described herein may increase the efficiency and load capacity of a telecommunication network by enabling successful 2- Step Random Access Channel RACH procedures to be implemented with greater frequency. A base station may determine, based on network conditions (e.g., congestion) types of User Equipment UE (101) that may be permitted to perform 2-Step RACH procedures (330, 440, 550, 640). The types of UE permitted may include UEs in a current state of operation (e.g., an idle or inactive mode), UEs capable of a certain type of communication (e.g., Ultra-Reliable-Low Latency Communication (URLLC), and UEs involved in time-sensitive communications (e.g., emergency calls). The base station may indicate which UEs are permitted to perform 2-Step RACH procedures via handover messages, broadcasting signals, dedicated signaling, and paging procedures. UEs may simultaneously perform 2-Step and 4-Step RACH procedures and operate based on which procedure is completed first (340, 450, 560, 650).

Description

PERFORMING 2-STEP RANDOM ACCESS CHANNEL (RACH) PROCEDURES

RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Patent Application No.

62/417,592, which was filed on November 4, 2016, the contents of which are hereby

incorporated by reference as though fully set forth herein.

BACKGROUND

Wireless telecommunication networks may include User Equipment (UE) (e.g., smartphones, tablet computers, laptop computers, etc.), one or more base stations, and a core network. When a UE is initially powered on, the UE may listen for system information (e.g., a Master Information Block (MIB), System Information Blocks (SIBs), etc.) broadcasted by a base station over a common channel. The UE may use the system information to synchronize with the base station and to verify that the base station corresponds to an appropriate public land mobile network (PLMN).

Before the UE may establish a connection with the base station, the UE may perform one or more procedures to notify the base station that the UE is within communication range and ready for the network to assign wireless resources to the UE. An example of such a procedure may include a Random Access Channel (RACH) procedure. In some scenarios, a RACH procedure may include four messages communicated between the UE and the base station (i.e., Message 1 (Msgl), Message 2 (Msg2), Message 3 (Msg3), and Message 4 (Msg4)). Due to the four messages, this type of RACH is sometimes referred to as a 4-Step RACH procedure.

In some scenarios, the UE may initiate communications with the base station by performing a shorter RACH procedure. An example of such a procedure may include a 2-Step RACH procedure, which may only involve two messages being sent between the UE and the base station. The 2-Step RACH procedure may combine the content of Msgl and Msg3 from the 4-Step RACH procedure into a first message (from the UE to the base station) and the content of Msg2 and Msg4 from the 4-Step RACH procedure into a second message (from the base station to the UE). As such, the overall content communicated between the UE and the base station may be the same, or very similar, for both the 4-Step and the 2-Step RACH procedures. BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments described herein will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals may designate like structural elements. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.

Fig. 1 illustrates an architecture of a system in accordance with some embodiments; Fig. 2 is a flowchart of an example process for enabling User Equipment (UEs) to perform 2-Step Random Access Channel (RACH) procedures;

Fig. 3 is a sequence flow diagram of an example for using a handover procedure to enable a UE to engage in a 2-Step RACH procedure with an enhanced NodeB (eNB);

Fig. 4 is a sequence flow diagram of an example for using a broadcast signal to enable UEs to engage in 2-Step RACH procedures with an eNB;

Fig. 5 is a sequence flow diagram of an example for using dedicated signaling to enable UEs to engage in 2-Step RACH procedures with an eNB;

Fig. 6 is a sequence flow diagram of an example for using a paging function to enable a

UE to engage in 2-Step RACH procedures with an eNB;

Fig. 7 illustrates example components of a device in accordance with some embodiments; Fig. 8 illustrates example interfaces of baseband circuitry in accordance with some embodiments; and

Fig. 9 is a block diagram illustrating components, according to some example

embodiments, able to read instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium) and perform any one or more of the methodologies discussed herein.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents.

Before User Equipment (UE) may establish a connection with a wireless telecommunication network, the UE may perform one or more procedures to notify a base station that the UE is in the area and ready for wireless resources to be assigned to the UE. An example of such a procedure may include a Random Access Channel (RACH) procedure. In a 4-Step RACH procedure, four messages may be exchanged between the UE and the base station (i.e., Message 1 (Msgl), Message 2 (Msg2), Message 3 (Msg3), and Message 4 (Msg4)). Msgl and Msg3 may be from the UE to the base station, and Msg2 and Msg4 may be from the base station to the UE.

For Msgl, the UE may randomly select a RACH preamble intended to enable the base station to identify communications from the UE (as opposed to communications from other UEs performing a RACH procedure). In response to Msgl, the base station may send the UE, in Msg2, a Cell Radio Network Temporary Identity (C-RNTI) that may be based on the RACH preamble from the UE, in addition to providing the UE with an uplink grant corresponding to an Uplink Shared Channel (UL-SCH). The UE may use the UL-SCH to respond to the base station with Msg3, which may include a Radio Resource Control (RRC) Connection Request message in the case of initial access with a Temporary Mobile Subscriber Identity (TMSI) or a random value (in the case the initial access is for MM NAS signaling) or may include the UE identity (e.g. C- RNTI, ResumelD etc.) in the case of performing UE initiated random access during RRC

Connected mode. In turn, the base station may communicate Msg4 to the UE, which is used for contention resolution via either Physical Downlink Control Channel (PDCCH) (C-RNTI) or UE Contention Resolution identity MAC (Media Access Control) Control Element (CE) (TMSI, random value or ResumelD etc.).

This type of RACH is sometimes referred to as a contention based RACH procedure, since it is possible for two UEs to randomly pick the same RACH preamble (for Msgl) and, therefore, receive the same C-RNTI from the base station (in Msg2). In such a scenario, Msg3 from each UE may conflict with one another, and the base station may only receive one (or neither) of the Msg3s due to interference (or "contention") between the Msg3s. If the base station does not receive a Msg3 from either UE, neither UE may receive a Msg4 from the base station and each UE may restart the RACH procedure after expiry of a specified timer. If the base station receives a Msg3 from only one UE, that UE will receive a Msg4 from the base station (which may include a TMSI) that the UE may go on to use for subsequent

communications with the base station. The other UE may restart the RACH procedure after expiry of the specified timer.

In a non-contention based RACH procedure, the base station may inform the UE which preamble or time and frequency resources to use for Msgl . This may ensure that the UE and base station may complete the RACH procedure without collision with another UE.

Limitations to implementing non-contention based RACH procedures may include a need for the base station to have a way to initially inform the UE about the preamble that the UE should use for the RACH procedure. As such, non-contention based RACH procedures may be limited to scenarios where the base station has a way of communicating with the UE before the RACH procedure. An example of such a scenario may include a handover procedure where the UE is being passed from one base station to another.

In some situations, a UE and base station may perform a 2- Step RACH procedure instead of the 4-Step RACH procedures described above. Similar to the 4-Step RACH procedures, the 2-Step RACH procedure may be contention based or non-contention based. However, in contrast to the 4-Step RACH procedure, the 2- Step RACH procedure may only include a first message from the UE to the base station, and a second message from the base station to the UE. The contents of the first message may include a combination of the contents of Msgl and Msg3 of the 4-Step RACH procedure, and the contents of the second message may include a combination of the contents of Msg2 and Msg4 of the 4-Step RACH procedure. For example, the first message of the 2-Step RACH procedure may include a combination of a RACH preamble (Msgl) and a RRC Connection Request message (Msg3) that may include an identifier for the UE. The base station may reply with a single message that includes a combination of a Random Access Response message (Msg2) and a Content Resolution message (Msg4 - UE contention resolution identity sent in Msgl). Contention resolution may be addressed as the message from the e B may include the same identifier provided by the UE in the first message.

The overall information exchanged in the 2-Step RACH procedure and the 4-Step RACH procedure may be similar, but the 2-Step RACH procedure may be completed more rapidly since only two messages may be involved. Nevertheless, while completing RACH procedures faster may be beneficial (e.g., an efficient use of network resources), the size of Msgl in the 2-Step RACH procedure may be much larger, which may result in more transmission failures due to higher collision rates or other factors (e.g. Increase UL interference, UE transmission power, MCS used etc.) and therefore reduced overall network load capacity. Due to these constraints, some wireless telecommunication networks may implement not to configure 2-Step RACH procedures at appropriate times and circumstances. For example, some wireless telecommunication networks may forego the benefits of 2-Step RACH procedures by being too restrictive about when 2-Step RACH procedures may be used, while other networks may inadvertently increase transmission failures and collision rates by being too liberal about when 2-Step RACH procedures may be used.

Techniques described herein may increase the efficiency and load capacity of a wireless telecommunication network by enabling 2-Step RACH procedures to be implemented at appropriate times and in appropriate ways. For example, a base station may monitor network conditions (e.g., congestion, interference, etc.) and determine, based on the network conditions, types of User Equipment (UE) that may be permitted to perform 2-Step RACH procedures involving the base station. The types of UEs may be limited to UEs in a current state of operation (e.g., an RRC idle mode, Inactive State, RRC Connected mode etc.), UEs capable of a certain type of functions (e.g., Ultra-Reliable-Low Latency Communication (URLLC)), and/or UEs involved in certain types of communications (such as emergency calls or other time- sensitive communications). Limiting the quantity of UEs permitted to perform 2-Step RACH procedures may help ensure that collision rates remain at an appropriate level, and determining the types of UEs permitted to perform 2-Step RACH procedures may help ensure that 2-Step RACH procedures are performed by appropriate UEs (e.g., UEs that may benefit the most from a faster RACH procedure).

Additionally, the base station may indicate which UEs are permitted to perform 2-

Step RACH procedures in one or more ways, which may include handover messages, broadcasting signals, dedicated signaling, and paging procedures. In some embodiments, the base station may provide general permission information (e.g., without assigning RACH preambles) such that UEs may perform 2-Step RACH procedures that are contention based. In some embodiments, the base station may provide specific permission information, which may include assigning RACH preambles to UEs, such that UEs may perform 2-Step RACH procedures that are not contention based or are reduced contention (e.g. the contention resources are to a smaller group of UEs etc.). The base station may also indicate to the UEs random access resources (time and frequency resources for Msgl) that have been reserved or otherwise dedicated to performing 2- Step RACH procedures, which may provide additional control and predictability about how many/often 2- Step RACH procedures may be supported by the base station.

In some embodiments, UEs may perform 2- Step and 4- Step RACH procedures in parallel (e.g., simultaneously). In such embodiments, the UEs may operate based on whichever RACH procedure is completed first and ignore the other (incomplete) procedure. Furthermore, while one or more of the techniques, described herein, may be described using examples and/or contexts that may correspond to third generation (3G) and/or fourth generation (4G) wireless technologies, the techniques described herein may also be applied to fifth generation (5G), New Radio (NR), and other wireless technologies as well.

Fig. 1 illustrates an architecture of a system 100 in accordance with some embodiments. The system 100 is shown to include UE 101 and a UE 102. The UEs 101 and 102 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks), but may also comprise any mobile or non-mobile computing device, such as Personal Data Assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, or any computing device including a wireless communications interface.

In some embodiments, any of the UEs 101 and 102 can comprise an Internet of

Things (IoT) UE, which can comprise a network access layer designed for low-power IoT applications utilizing short-lived UE connections. An IoT UE can utilize technologies such as machine-to-machine (M2M) or machine-type communications (MTC) for exchanging data with an MTC server or device via a public land mobile network (PLMN), Proximity-Based Service (ProSe) or device-to-device (D2D) communication, sensor networks, or IoT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An IoT network describes interconnecting IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The IoT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the IoT network.

The UEs 101 and 102 may be configured to connect, e.g., communicatively couple, with a radio access network (RAN) 110— the RAN 110 may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E- UTRAN), a NextGen RAN (NG RAN), or some other type of RAN. The UEs 101 and 102 utilize connections 103 and 104, respectively, each of which comprises a physical

communications interface or layer (discussed in further detail below); in this example, the connections 103 and 104 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code-division multiple access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3 GPP Long Term Evolution (LTE) protocol, a fifth generation (5G) protocol, a New Radio (NR) protocol, and the like.

In this embodiment, the UEs 101 and 102 may further directly exchange communication data via a ProSe interface 105. The ProSe interface 105 may alternatively be referred to as a sidelink interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery Channel (PSDCH), and a Physical Sidelink Broadcast Channel (PSBCH).

The UE 102 is shown to be configured to access an access point (AP) 106 via connection 107. The connection 107 can comprise a local wireless connection, such as a connection consistent with any IEEE 802.11 protocol, wherein the AP 106 would comprise a wireless fidelity (Wi-Fi®) router. In this example, the AP 106 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below).

The RAN 110 can include one or more access nodes that enable the connections 103 and 104. These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, eNBs, next Generation NodeBs (gNB), RAN nodes, and so forth, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). The RAN 110 may include one or more RAN nodes for providing macrocells, e.g., macro RAN node 111, and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node 112. Any of the RAN nodes 111 and 112 can terminate the air interface protocol and can be the first point of contact for the UEs 101 and 102. In some embodiments, any of the RAN nodes 111 and 112 can fulfill various logical functions for the RAN 110 including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management.

In accordance with some embodiments, the UEs 101 and 102 can be configured to communicate using Orthogonal Frequency-Division Multiplexing (OFDM) communication signals with each other or with any of the RAN nodes 111 and 112 over a multicarrier communication channel in accordance various communication techniques, such as, but not limited to, an Orthogonal Frequency-Division Multiple Access (OFDMA) communication technique (e.g., for downlink communications) or a Single Carrier Frequency Division Multiple Access (SC-FDMA) communication technique (e.g., for uplink and ProSe or sidelink

communications), although the scope of the embodiments is not limited in this respect. The OFDM signals can comprise a plurality of orthogonal subcarriers.

In some embodiments, a downlink resource grid can be used for downlink transmissions from any of the RAN nodes 111 and 112 to the UEs 101 and 102, while uplink transmissions can utilize similar techniques. The grid can be a time-frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Such a time-frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest time- frequency unit in a resource grid is denoted as a resource element. Each resource grid comprises a number of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements; in the frequency domain, this may represent the smallest quantity of resources that currently can be allocated. There are several different physical downlink channels that are conveyed using such resource blocks.

The physical downlink shared channel (PDSCH) may carry user data and higher-layer signaling to the UEs 101 and 102. The physical downlink control channel (PDCCH) may carry information about the transport format and resource allocations related to the PDSCH channel, among other things. It may also inform the UEs 101 and 102 about the transport format, resource allocation, and H-ARQ (Hybrid Automatic Repeat Request) information related to the uplink shared channel. Typically, downlink scheduling (assigning control and shared channel resource blocks to the UE 102 within a cell) may be performed at any of the RAN nodes 111 and 112 based on channel quality information fed back from any of the UEs 101 and 102. The downlink resource assignment information may be sent on the PDCCH used for (e.g., assigned to) each of the UEs 101 and 102.

The PDCCH may use control channel elements (CCEs) to convey the control information. Before being mapped to resource elements, the PDCCH complex- valued symbols may first be organized into quadruplets, which may then be permuted using a sub-block interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, where each CCE may correspond to nine sets of four physical resource elements known as resource element groups (REGs). Four Quadrature Phase Shift Keying (QPSK) symbols may be mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of the downlink control information (DCI) and the channel condition. There can be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=l, 2, 4, or 8).

Some embodiments may use concepts for resource allocation for control channel information that are an extension of the above-described concepts. For example, some embodiments may utilize an enhanced physical downlink control channel (EPDCCH) that uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more enhanced the control channel elements (ECCEs). Similar to above, each ECCE may correspond to nine sets of four physical resource elements known as an enhanced resource element groups (EREGs). An ECCE may have other numbers of EREGs in some situations.

The RAN 110 is shown to be communicatively coupled to a core network (CN) 120 — via an SI interface 113. In embodiments, the CN 120 may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN. In this embodiment, the SI interface 113 is split into two parts: the Sl-U interface 114, which carries traffic data between the RAN nodes 111 and 112 and the serving gateway (S-GW) 122, and the SI -mobility management entity (MME) interface 115, which is a signaling interface between the RAN nodes 111 and 112 and MMEs 121.

In this embodiment, the CN 120 comprises the MMEs 121, the S-GW 122, the Packet Data Network (PDN) Gateway (P-GW) 123, and a home subscriber server (HSS) 124. The MMEs 121 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 121 may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS 124 may comprise a database for network users, including subscription-related information to support the network entities' handling of communication sessions. The CN 120 may comprise one or several HSSs 124, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 124 can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc.

The S-GW 122 may terminate the SI interface 113 towards the RAN 110, and routes data packets between the RAN 110 and the CN 120. In addition, the S-GW 122 may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter- 3 GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement.

The P-GW 123 may terminate an SGi interface toward a PDN. The P-GW 123 may route data packets between the EPC network 123 and external networks such as a network including the application server 130 (alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 125. Generally, the application server 130 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this embodiment, the P-GW 123 is shown to be communicatively coupled to an application server 130 via an IP communications interface 125. The application server 130 can also be configured to support one or more communication services (e.g., Voice-over-Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs 101 and 102 via the CN 120.

The P-GW 123 may further be a node for policy enforcement and charging data collection. Policy and Charging Enforcement Function (PCRF) 126 is the policy and charging control element of the CN 120. In a non-roaming scenario, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE's Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with local breakout of traffic, there may be two PCRFs associated with a UE's IP-CAN session: a Home PCRF (H- PCRF) within a HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF 126 may be communicatively coupled to the application server 130 via the P-GW 123. The application server 130 may signal the PCRF 126 to indicate a new service flow and select the appropriate Quality of Service (QoS) and charging parameters. The PCRF 126 may provision this rule into a Policy and Charging Enforcement Function (PCEF) (not shown) with the appropriate traffic flow template (TFT) and QoS class of identifier (QCI), which commences the QoS and charging as specified by the application server 130.

The quantity of devices and/or networks, illustrated in Fig. 1, is provided for explanatory purposes only. In practice, system 100 may include additional devices and/or networks; fewer devices and/or networks; different devices and/or networks; or differently arranged devices and/or networks than illustrated in Fig. 1. For example, while not shown, environment 100 may include devices that facilitate or enable communication between various components shown in environment 100, such as routers, modems, gateways, switches, hubs, etc. Alternatively, or additionally, one or more of the devices of system 100 may perform one or more functions described as being performed by another one or more of the devices of system 100. Additionally, the devices of system 100 may interconnect with each other and/or other devices via wired connections, wireless connections, or a combination of wired and wireless connections. In some embodiments, one or more devices of system 100 may be physically integrated in, and/or may be physically attached to, one or more other devices of system 100. Also, while "direct" connections may be shown between certain devices in Fig. 1, some of said devices may, in practice, communicate with each other via one or more additional devices and/or networks.

Fig. 2 is a flowchart of an example process 200 for enabling UEs 101 to perform 2-

Step RACH procedures. Process 200 may be implemented by an eNB. In some embodiments, one or more of the operations described in Fig. 2 may be performed in whole, or in part, by another device, such as AP 106, another type of RAN node (1 1 1 or 1 12), MME 121, etc.

As shown, process 200 may include monitoring network conditions (block 210). For example, an eNB may be configured to monitor one or more aspects of a RAN, such as a quantity of wireless devices (e.g., UEs 101) operating within a coverage area of the eNB, wireless resources allocated to wireless communications, usage rates of wireless resources, an amount (e.g., level, rate, etc.) of congestion, signal interference, and/or collision rates, etc. In some embodiments, the aspects of the RAN monitored by the eNB may pertain to wireless resources relating to RACH procedures involving the eNB. For example, the eNB may monitor an amount of random access resources currently being used (and/or expected to be used in the near future) for RACH procedures relative to a total amount of wireless resources that may be used for RACH procedures.

Process 200 may include determining, based on the network conditions, UEs 101 that are permitted to perform 2- Step RACH procedures (block 220). For instance, the eNB may determine that an amount of wireless resources that are available for PRACH procedures are such that the eNB may reliably support 2-Step RACH procedures for certain (e.g., a limited quantity of) UEs 101. For example, the eNB may determine that UEs 101 in a particular mode or state of operation may be permitted to perform 2-Step RACH procedures. Examples of such states of operation may include an RRC idle mode and/or Inactive State and/or RRC Connected mode.

An RRC idle mode, as described herein, may include a mode of operation, of UE 101, before an RRC connection is established (e.g., after UE 101 is powered on but before an RRC connection is established with an eNB). The idle state may refer to a mode or state of operation of the 4G and/or LTE protocols. Additionally, or alternatively, an idle state, as described herein, may include a mode of operation, of UE 101, after an RRC connection with the network is released. During the idle state, a wireless interface (e.g., antenna array) of UE 101 may be inactive, but an IP addressed assigned to UE 101, by the network, may be maintained. During the idle state, core network 120 may remain aware of UE 101 though eNBs may not. In some embodiments, the idle state may include an RRC IDLE mode. Additionally, or alternatively, to transition from an idle state to a connected state (e.g., from RRC IDLE mode to

RRC CONNECTED mode) UE 101 may perform a 2-Step or 4-Step RACH procedure.

An inactive state, as described herein, may include UE 101 being in dormant mode, power save mode, and/or not engaging in wireless communications (no wireless transmissions or receptions) with the eNB. The inactive state may refer to a mode or state of operation of the 5G and/or NR protocols. While in the inactive state, UE 101 may retain context and configuration information regarding wireless resources previously assigned to UE 101 by the eNB. In some embodiments, by retaining the configuration information, UE 101 may expedite the process by which UE 101 may transition to an active state and reconnect with the network. To transition from an inactive state to an active state (i.e. RRC Connected mode), UE 101 may perform a 2- Step or 4- Step RACH procedure.

Additionally, the e B may determine that certain types of UEs 101 may perform 2-

Step RACH procedures. Examples of types of UEs 101 that may be permitted to use 2-Step RACH procedures may include UEs 101 with certain capabilities, certain configurations, and/or UEs 101 that are being used for communications of an especially high-priority level or time- sensitive reason (e.g., emergency calls). An example of UE 101 capabilities and/or

configurations may include UEs 101 capable of engaging in Ultra-Reliable-Low Latency Communication (URLLC), which may include the transmission of sporadic and/or small amounts of information (e.g., packets) with low latency and high reliability.

Process 200 may also include informing UEs 101 regarding permissions to perform 2- Step RACH procedures (block 230). For example, the eNB may communicate with UEs 101 in one or more ways in order to notify UEs 101 about which UEs 101 are permitted to engage in 2- Step RACH procedures with the eNB. Examples of how the eNB may notify the UEs 101 may include, but are not limited to, handover command messages, SIB provided in broadcast signals, dedicated signaling messages (e.g., dedicated RRC signaling), and paging messages. Examples of such scenarios are described below, in detail, with reference to Figs. 3-6.

Process 200 may include engaging in 2- Step RACH procedures with permitted UEs

101 (block 240). For instance, after providing UEs 101 with information about which UEs 101 engage in 2-Step RACH procedures, the eNB may begin to receive messages, from UEs 101, initiating 2-Step RACH procedures. As mentioned above, such messages may include a combination of Msgl and Msg3 of the 4-Step RACH procedure (e.g., a combination of the RACH Request message and the UE identification message). The eNB may respond to such messages by communicating a message back to UEs 101 in accordance with the 2-Step RACH procedure. The messages communicated back to UEs 101 may include a combination of Msg2 and Msg4 of the 4-Step RACH procedure (e.g., a combination of the RACH Response message and the Contention Resolution message). The information provided to UEs 101 as a result of the 2-Step RACH procedures may enable the UEs 101 to continue communicating with the eNB in order to, for example, register with core network 120 and/or establish a connection with the eNB (e.g., an RRC connection).

Fig. 3 is a sequence flow diagram of an example for using a handover procedure to enable UE 101 to engage in a 2-Step RACH procedure with an eNB. As shown, UE 101 may be engaged in a handover procedure involving different eNBs (e.g., a source eNB and target eNB) (block 310). During the handover procedure, an eNB involved in the handover may

communicate a handover command message to UE 101 (line 320). As shown, the handover command may include information about wireless resources that have been dedicated to (e.g., reserved for) Physical RACH (PRACH) procedures involving the target eNB and/or an indication of whether UE 101 is permitted to perform 2-Step RACH procedure when

communicating with the eNB, In some embodiments, the handover command may also, or alternatively, provide UE 101 with information (e.g., a specified preamble) that UE 101 may use to perform a non-contention based RACH procedure with the target eNB, In some embodiments, the handover comraand may be an RRC Connection Reconfiguration Request message and/or may include an Information Element (IE) similar to the MobiiityControlInfo IE of the 3 GPP Communication Standard. An example of information that may be included in the

MobiiityControlInfo IE is provided in Table 1 below.

Table J

An example MobiiityControlInfo Informatio Element (IE) including 2-Step RACH permission information

-- ASN1 START

MobiiityControlInfo : : = SEQUENCE

targetPhysCellld PhysCeiild OPTIONAL, cairierFreq Carrier FreqEUTRA OPTIONAL, carrierBandwidth CarrierBandwidtliEUTRA OPTIONAL, additional SpectruniEmi ssion AdditionalSpectrumEmission OPTIONAL, t.304 ENUMERATED {

ffis50, mslOO, msl50, ms200, ms500, mslOOO, ms2000, msl0000-vl310>.

ne lJEIdentiiy C-RNTl,

radio esourceConfigCommon RadioResourceCondifgCommon OPTIONAL, rach-Confi gDedicated RACH-ConfigPedicated

rach2step-NR ENUMERATED{true} OPTIONAL,

[ I carrierFreq-v9eO CarrierFreqEUTRA-v9eO OPTIONAL,

1 J 1

h

[ [ drb-ContinueROHC-rl l ENUMERATED {true} OPTIONAL, ] ] The above IE may be provided by the network (e.g., eNB) to the UE whenever the network wants UE 101 to engage in a handover. When UE 101 receives rach2astep-NR set to true, UE 101 may perform a 2-step random access procedure on the subsequent handover. Such indication can also be provided in other cases (e.g. Secondary Cell Group (SCG) change, Secondary Node (SN) change, etc.).

As part of the ongoing handover procedure, UE 101 and the target eNB may perform a 2-Step RACH procedure (block 330) for contention based random access. Alternatively, if UE 101 is configured to perform simultaneous RACH procedures, UE 101 may initiate a 2-Step RACH procedure and a 4-Step RACH procedure with the target eNB for contention based random access. In such a scenario, UE 101 may proceed with the handover procedure based on whichever RACH procedure is completed first and discontinue, ignore, etc., the other RACH procedure. For example, if the 2-Step RACH procedure is completed first, UE 101 may use the parameters (e.g., the C-RNTI) resulting from the 2-Step RACH procedure to complete the handover procedure (block 350). By contrast, if the 4-Step RACH procedure is completed first, UE 101 may use the parameters (e.g., the C-RNTI) resulting from the 4-Step RACH procedure to complete the handover procedure (block 350).

Fig. 4 is a sequence flow diagram of an example for using a broadcast signal to enable UEs 101 to engage in 2-Step RACH procedures with an eNB. As shown, UEs 101 in a coverage area of an eNB may be in one or more states of operations, which may include an idle state and/or an inactive state (block 410). Additionally, the eNB may transmit a broadcast signal to UEs 101 within the coverage area (block 420). The broadcast signal may include SIBs that indicate which types of UEs 101 are permitted to use 2-Step RACH procedures, such as UEs 101 currently in one or more states of operation specified by the eNB (e.g., UEs 101 initially accessing the network, in an idle state, inactive state, etc.). Additional examples of types of UEs 101 that may be permitted to use 2-Step RACH procedures may include UEs 101 with certain capabilities (URLLC), configurations, and/or that are attempting to connect to the eNB for a high-priority or time-sensitive reason (e.g., emergency calls).

After receiving the broadcasted signal from the eNB, UEs 101 permitted to do so (by the broadcast signal) may initiate a 2-Step RACH procedure with the eNB (block 440). For example, if UE 101 was in an idle state upon receiving the broadcast signal, UE 101 may perform a 2- Step RACH procedure when transitioning to an active state and connecting or reconnecting with the eNB. In another example, if UE 101 was in an inactive state upon receiving the broadcast signal, UE 101 may perform a 2- Step RACH procedure when going from a suspend function to a resume function communicating once again with the eNB. In another example, a type of UE 101 and/or UE 101 capable of performing a type of function specified by the broadcast signal may perform a 2- Step RACH procedure. In some embodiments, the broadcast signal may also include timer information describing a duration of time for which permission is granted to UEs 101 described in the broadcast signal. In such embodiments, UEs 101 may verify whether the specified has expired before attempting to perform a 2- Step RACH.

Additionally, or alternatively, UE 101 may be configured to initiate/perform a 2-Step

RACH procedure and a 4-Step RACH procedure simultaneous (block 450). In such a scenario, UE 101 may proceed to communicate with the eNB based on whichever RACH procedure is completed first and disregard, terminate, etc., the other RACH procedure. For example, if the 2- Step RACH procedure is completed first, UE 101 may use the assigned parameters from the 2- Step RACH procedure to communicate with the eNB. By contrast, if the 4-Step RACH procedure is completed first, UE 101 may use the parameters resulting from the 4-Step RACH procedure to complete the handover procedure.

Fig. 5 is a sequence flow diagram of an example for using dedicated signaling to enable UEs 101 to engage in 2- Step RACH procedures with an eNB. As shown, UE 101 may be in an RRC connected mode of operation with respect to an eNB (block 510) and the eNB may use dedicated signaling to indicate that certain UEs 101 are permitted to use 2-Step RACH with the eNB (block 520). Examples of such UEs 101 may include UEs 101 currently in one or more states of operation (e.g., an idle state, inactive state, etc.) and/or UEs 101 with certain capabilities (e.g., URLLC), configurations, and/or that are attempting to connect to the eNB for a high- priority or time- sensitive reason (e.g., emergency calls). Dedicated signaling, as described herein, may include one or more message and/or wireless resources specified for providing information about UEs 101 (e.g., the types of UEs) are permitted to engage in a 2-Step RACH procedure with a particular eNB. In some embodiments, dedicated signaling may include one or more RRC message and/or signals that have been dedicated, specified, reserved, created, etc., for communicating permission information to UEs 101 in a RRC CONNECTEDs mode of operation (and/or another type of mode that may involve UEs 101 maintaining an active connection with the e B).

Assume that a UE 101 previously in the RRC connected mode transitions to a state of operation described by the dedicated signaling (e.g., an idle state, inactive state, etc.) (block 530). The UE 101 may retain the information from the eNB such that the UE 101 may perform a 2- Step RACH procedure to transition from the idle or inactive state and begin communicating once again with the eNB (block 550). Additionally, if/when a UE 101 engages in a type of communication specified by the permissions provided in the dedicated signaling (e.g., URLLC call type) (block 540), the UE 101 may reengage with the eNB by performing a 2-Step RACH procedure (block 550).

Additionally, or alternatively, UE 101 may be configured to initiate/perform a 2-Step RACH procedure and a 4- Step RACH procedure simultaneous (block 560). In such a scenario, UE 101 may proceed to communicate with the eNB based on whichever RACH procedure is completed first and terminate, ignore, etc., the incomplete RACH procedure. For example, if the 2-Step RACH procedure is completed first, UE 101 may use the assigned parameters from the 2- Step RACH procedure to communicate with the eNB. By contrast, if the 4- Step RACH procedure is completed first, UE 101 may use the parameters resulting from the 4-Step RACH procedure to complete the handover procedure.

Fig. 6 is a sequence flow diagram of an example for using a paging function to enable UE 101 to engage in 2-Step RACH procedures with an eNB. As shown, UE 101 may be in a state of operation (e.g., an idle state, inactive state, etc.) that is conducive to UE 101 receiving a paging message from an eNB of core network 120 (block 610). For purposes of explaining Fig. 6, assume that core network 120 determines that UE 101 is to be paged. As such, MME 121 or another device of core network 120 may send a request or command message to an eNB corresponding to UE 101 for paging purposes (line 620). As shown, the message may indicate a paging priority level (e.g., low, moderate, high, etc.) for paging UE 101.

In response, the eNB may communicate a paging message to UE 101 (line 630). The paging message may indicate whether UE 101 is permitted to use a 2-Step RACH procedure to reconnect with the eNB. In some embodiments, the paging message may also indicate RACH resources that eNB has assigned, dedicated, reserved, etc. for 2-Step RACH procedures in general and/or for a 2-Step RACH procedure involving UE 101 in particular. Additionally, or alternatively, the paging message may provide UE 101 with a preamble that UE 101 may use for a non-contention based, 2- Step RACH procedure.

As shown, UE 101 may respond to the paging message by performing a 2-Step RACH procedure involving the e B (block 640). Additionally, or alternatively, UE 101 may be configured to initiate/perform a 2-Step RACH procedure and a 4-Step RACH procedure simultaneous (block 650). In such a scenario, UE 101 may proceed to communicate with the eNB based on whichever RACH procedure is completed first and terminate, ignore, etc., the incomplete RACH procedure. For example, if the 2-Step RACH procedure is completed first, UE 101 may use the assigned parameters from the 2-Step RACH procedure to communicate with the eNB. By contrast, if the 4-Step RACH procedure is completed first, UE 101 may use the parameters resulting from the 4-Step RACH procedure to complete the handover procedure.

As used herein, the term "circuitry," "processing circuitry," or "logic" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware.

Embodiments described herein may be implemented into a system using any suitably configured hardware and/or software. Fig. 7 illustrates example components of a device 700 in accordance with some embodiments. In some embodiments, the device 700 may include application circuitry 702, baseband circuitry 704, Radio Frequency (RF) circuitry 706, front-end module (FEM) circuitry 708, one or more antennas 710, and power management circuitry (PMC) 712 coupled together at least as shown. The components of the illustrated device 700 may be included in a UE or a RAN node. In some embodiments, the device 700 may include less elements (e.g., a RAN node may not utilize application circuitry 702, and instead include a processor/controller to process IP data received from an EPC). In some embodiments, the device 700 may include additional elements such as, for example, memory/storage, display, camera, sensor, or input/output (I/O) interface. In other embodiments, the components described below may be included in more than one device (e.g., said circuitries may be separately included in more than one device for Cloud-RAN (C-RAN) implementations).

The application circuitry 702 may include one or more application processors. For example, the application circuitry 702 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with or may include memory/ storage and may be configured to execute instructions stored in the memory/ storage to enable various applications or operating systems to run on the device 700. In some embodiments, processors of application circuitry 702 may process IP data packets received from an EPC.

The baseband circuitry 704 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 704 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 706 and to generate baseband signals for a transmit signal path of the RF circuitry 706. Baseband processing circuity 704 may interface with the application circuitry 702 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 706. For example, in some embodiments, the baseband circuitry 704 may include a third generation (3G) baseband processor 704 A, a fourth generation (4G) baseband processor 704B, a fifth generation (5G) baseband processor 704C, or other baseband processor(s) 704D for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G), sixth generation (6G), etc.). The baseband circuitry 704 (e.g., one or more of baseband processors 704 A-D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 706. In other

embodiments, some or all of the functionality of baseband processors 704 A-D may be included in modules stored in the memory 704G and executed via a Central Processing Unit (CPU) 704E. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments,

modulation/demodulation circuitry of the baseband circuitry 704 may include Fast-Fourier Transform (FFT), precoding, or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 704 may include convolution, tail-biting convolution, turbo, Viterbi, or Low-Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

In some embodiments, the baseband circuitry 704 may include one or more audio digital signal processor(s) (DSP) 704F. The audio DSP(s) 704F may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 704 and the application circuitry 702 may be implemented together such as, for example, on a system on a chip (SOC).

In some embodiments, the baseband circuitry 704 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 704 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks WMA ), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 704 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

RF circuitry 706 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 706 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 706 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 708 and provide baseband signals to the baseband circuitry 704. RF circuitry 706 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 704 and provide RF output signals to the FEM circuitry 708 for transmission.

In some embodiments, the receive signal path of the RF circuitry 706 may include mixer circuitry 706a, amplifier circuitry 706b and filter circuitry 706c. In some embodiments, the transmit signal path of the RF circuitry 706 may include filter circuitry 706c and mixer circuitry 706a. RF circuitry 706 may also include synthesizer circuitry 706d for synthesizing a frequency for use by the mixer circuitry 706a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 706a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 708 based on the synthesized frequency provided by synthesizer circuitry 706d. The amplifier circuitry 706b may be configured to amplify the down-converted signals and the filter circuitry 706c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down- converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 704 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 706a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 706a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 706d to generate RF output signals for the FEM circuitry 708. The baseband signals may be provided by the baseband circuitry 704 and may be filtered by filter circuitry 706c.

In some embodiments, the mixer circuitry 706a of the receive signal path and the mixer circuitry 706a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and upconversion, respectively. In some embodiments, the mixer circuitry 706a of the receive signal path and the mixer circuitry 706a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 706a of the receive signal path and the mixer circuitry 706a may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 706a of the receive signal path and the mixer circuitry 706a of the transmit signal path may be configured for super- heterodyne operation.

In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 706 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 704 may include a digital baseband interface to communicate with the RF circuitry 706.

In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 706d may be a fractional-N synthesizer or a fractional N/N+l synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 706d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

The synthesizer circuitry 706d may be configured to synthesize an output frequency for use by the mixer circuitry 706a of the RF circuitry 706 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 706d may be a fractional N/N+l synthesizer.

In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 704 or the applications processor 702 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 702.

Synthesizer circuitry 706d of the RF circuitry 706 may include a divider, a delay- locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DP A). In some embodiments, the DMD may be configured to divide the input signal by either N or N+l (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 706d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some

embodiments, the RF circuitry 706 may include an IQ/polar converter.

FEM circuitry 708 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 710, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 706 for further processing. FEM circuitry 708 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 706 for transmission by one or more of the one or more antennas 710. In various embodiments, the amplification through the transmit or receive signal paths may be done solely in the RF circuitry 706, solely in the FEM 708, or in both the RF circuitry 706 and the FEM 708.

In some embodiments, the FEM circuitry 708 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include an LNA to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 706). The transmit signal path of the FEM circuitry 708 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 706), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 710).

In some embodiments, the PMC 712 may manage power provided to the baseband circuitry 704. In particular, the PMC 712 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 712 may often be included when the device 700 is capable of being powered by a battery, for example, when the device is included in a UE. The PMC 712 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation characteristics.

While Fig. 7 shows the PMC 712 coupled only with the baseband circuitry 704.

However, in other embodiments, the PMC 712 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, application circuitry 702, RF circuitry 706, or FEM 708. In some embodiments, the PMC 712 may control, or otherwise be part of, various power saving mechanisms of the device 700. For example, if the device 700 is in an

RRC Connected state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it may enter a state known as Discontinuous Reception Mode (DRX) after a period of inactivity. During this state, the device 700 may power down for brief intervals of time and thus save power.

If there is no data traffic activity for an extended period of time, then the device 700 may transition off to an RRC Idle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 700 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 700 may not receive data in this state, in order to receive data, it must transition back to RRC Connected state.

An additional power saving mode may allow a device to be unavailable to the network for periods longer than a paging interval (ranging from seconds to a few hours). During this time, the device is totally unreachable to the network and may power down completely. Any data sent during this time incurs a large delay and it is assumed the delay is acceptable.

Processors of the application circuitry 702 and processors of the baseband circuitry 704 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 704, alone or in combination, may be used execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 704 may utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g., transmission communication protocol (TCP) and user datagram protocol (UDP) layers). As referred to herein, Layer 3 may comprise a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 may comprise a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, described in further detail below. As referred to herein, Layer 1 may comprise a physical (PHY) layer of a UE/RAN node, described in further detail below.

Fig. 8 illustrates example interfaces of baseband circuitry in accordance with some embodiments. As discussed above, the baseband circuitry 704 of Fig. 7 may comprise processors 804A-804E and a memory 804G utilized by said processors. Each of the processors 804A-804E may include a memory interface, respectively, to send/receive data to/from the memory 804G.

The baseband circuitry 804 may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface 812 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 704), an application circuitry interface 814 (e.g., an interface to send/receive data to/from the application circuitry 702 of Fig. 7), an RF circuitry interface 816 (e.g., an interface to send/receive data to/from RF circuitry 706 of Fig. 7), a wireless hardware connectivity interface 818 (e.g., an interface to send/receive data to/from Near Field Communication (NFC) components,

Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components), and a power management interface 820 (e.g., an interface to send/receive power or control signals to/from the PMC 712).

Fig. 9 is a block diagram illustrating components, according to some example embodiments, able to read instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium) and perform any one or more of the methodologies discussed herein. Specifically, Fig. 9 shows a diagrammatic representation of hardware resources 900 including one or more processors (or processor cores) 910, one or more memory/ storage devices 920, and one or more communication resources 930, each of which may be communicatively coupled via a bus 940. For embodiments where node virtualization (e.g., NFV) is utilized, a hypervisor 902 may be executed to provide an execution environment for one or more network slices/sub-slices to utilize the hardware resources 900

The processors 910 (e.g., a central processing unit (CPU), a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a digital signal processor (DSP) such as a baseband processor, an application specific integrated circuit (ASIC), a radio-frequency integrated circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, a processor 912 and a processor 914.

The memory/storage devices 920 may include main memory, disk storage, or any suitable combination thereof. The memory/storage devices 920 may include, but are not limited to any type of volatile or non- volatile memory such as dynamic random-access memory

(DRAM), static random-access memory (SRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), Flash memory, solid-state storage, etc.

The communication resources 930 may include interconnection or network interface components or other suitable devices to communicate with one or more peripheral devices 904 or one or more databases 906 via a network 908. For example, the communication resources 930 may include wired communication components (e.g., for coupling via a Universal Serial Bus (USB)), cellular communication components, NFC components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components.

Instructions 950 may comprise software, a program, an application, an applet, an app, or other executable code for causing at least any of the processors 910 to perform any one or more of the methodologies discussed herein. The instructions 950 may reside, completely or partially, within at least one of the processors 910 (e.g., within the processor's cache memory), the memory/ storage devices 920, or any suitable combination thereof. Furthermore, any portion of the instructions 950 may be transferred to the hardware resources 900 from any combination of the peripheral devices 904 or the databases 906. Accordingly, the memory of processors 910, the memory/ storage devices 920, the peripheral devices 904, and the databases 906 are examples of computer-readable and machine-readable media.

A number of examples, relating to embodiments of the techniques described above, will next be given.

In a first example, an apparatus of a base station may comprise: an interface to radio frequency (RF) circuitry; and one or more processors that are controlled to: create System Information Blocks (SIBs) that include information describing a type of User Equipment (UE), of a wireless telecommunication network, that is permitted to perform a 2-Step Random Access Channel (RACH) procedure involving the base station; cause, via the interface, the RF circuitry to communicate a broadcast signal, throughout a coverage area of the base station, that includes the SIBs; process a first message, corresponding to the 2-Step RACH procedure and from a UE corresponding to the described type of UE to create, in response to the first message, a second message corresponding to the 2-Step RACH procedure; and communicate the second message to the UE to complete the 2-Step RACH procedure In example 2, the subject matter of example 1, or any of the examples herein, wherein the one or more processors are controlled further to: perform, in parallel with the 2- Step RACH procedure, a 4-Step RACH procedure with the UE.

In example 3, the subject matter of example 1, or any of the examples herein, wherein the one or more processors are controlled further to: monitor network conditions corresponding to a Radio Access Network (RAN) of the base station; and determine, based on the network conditions, the type of UE permitted to perform a 2-Step RACH procedure.

In example 4, the subject matter of example 1, or any of the examples herein, wherein the SIBs include information describing a duration of time during which the type of UE is permitted to perform the 2- Step RACH procedure.

In a fifth example, an apparatus of a base station may comprise: a computer-readable memory device storing processor-executable instructions; and one or more processors configured to execute the processor-executable instructions, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors to: monitor network conditions corresponding to a Radio Access Network (RAN) of the base station;

determine, based on the network conditions, a type of User Equipment (UE) permitted to perform a 2-Step Random Access Channel (RACH) procedure; communicate, to a plurality of UEs connected to the base station, information describing the type of UE permitted to perform the 2-Step RACH procedure; process a first message, corresponding to the 2-Step RACH procedure and from a UE corresponding to the described type of UE to create, in response to the first message, a second message corresponding to the 2-Step RACH procedure; and cause the second message to be communicated to the UE to complete the 2-Step RACH procedure

In example 6, the subject matter of example 5, or any of the examples herein, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to: perform, in parallel with the 2-Step RACH procedure, a 4-Step RACH procedure with the UE.

In example 7, the subject matter of example 6, or any of the examples herein, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to: communicate, to the plurality of UEs, information describing a duration of time during which the type of UE is permitted to perform the 2-Step RACH procedure. In example, 8, the subject matter of example 1 or 5, or any of the examples herein, wherein the type of UE includes UEs in an Radio Resource Control (RRC) IDLE state.

In example, 9, the subject matter of example 1 or 5, or any of the examples herein, wherein the type of UE includes UEs in an inactive state.

In example, 10, the subject matter of example 1 or 5, or any of the examples herein, wherein the type of UE includes UEs capable of communicating in accordance with Ultra- Reliable-Low Latency Communication (URLLC).

In an eleventh example, an apparatus of a base station may comprise: a computer- readable memory device storing processor-executable instructions; and one or more processors configured to execute the processor-executable instructions, wherein execution of the processor- executable instructions, by the one or more processors, causes the one or more processors to: receive, from a core network of the base station, a request to page a User Equipment (UE) corresponding to the base station, the request including an indication of a high paging priority; generate, in response to the request, a paging message indicating that the UE is permitted perform a 2-Step RACH procedure involving the base station; communicate the paging message to the UE; receive, from the UE and in response to the paging message, a first message corresponding to the 2-Step RACH procedure; create, in response to the first message, a second message corresponding to the 2-Step RACH procedure; and communicate the second message to the UE to complete the 2-Step RACH procedure.

In example 12, the subject matter of example 11, or any of the examples herein, wherein the UE is in a Radio Resource Control (RRC) IDLE state prior to the base station communicating the paging message.

In example 13, the subject matter of example 11, or any of the examples herein, wherein the UE is in an inactive state prior to the base station communicating the paging message.

In example 14, the subject matter of example 11, or any of the examples herein, wherein the UE is in a Radio Resource Control (RRC) IDLE state.

In example 15, the subject matter of example 11, or any of the examples herein, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to: perform, in parallel with the 2-Step RACH procedure, a 4-Step RACH procedure with the UE. In example 16, the subject matter of example 11, or any of the examples herein, wherein the paging message includes information to enable the UE to perform a non-contention based 2-Step RACH procedure.

In a seventeenth example, an apparatus of a base station may comprise: a computer- readable memory device storing processor-executable instructions; and one or more processors configured to execute the processor-executable instructions, wherein execution of the processor- executable instructions, by the one or more processors, causes the one or more processors to: detect a handover procedure corresponding to a User Equipment (UE); determine that the UE is permitted to perform a 2-Step RACH procedure as part of the handover procedure; communicate, to the UE and as part of the handover procedure, an indication that the UE is permitted to perform the 2-Step RACH procedure; receive, the UE, a first message corresponding to the 2- Step RACH procedure; create, in response to the first message, a second message corresponding to the 2-Step RACH procedure; and communicate the second message to the UE to complete the 2-Step RACH procedure.

In example 18, the subject matter of example 17, or any of the examples herein, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to: perform, in parallel with the 2-Step RACH procedure, a 4-Step RACH procedure with the UE.

In example 19, the subject matter of example 17, or any of the examples herein, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to: monitor network conditions corresponding to a Radio Access Network (RAN) of the base station; and determine, based on the network conditions, that the UE is permitted to perform a 2-Step RACH procedure.

In example 20, the subject matter of example 176, or any of the examples herein, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to: provide, to the UE, information to enable the UE to perform a non-contention based 2-Step RACH procedure.

In a twenty-first example, an apparatus of a User Equipment (UE) may comprise: an interface to radio frequency (RF) circuitry; and one or more processors that are controlled to: receive, via the interface and from a base station of a wireless telecommunication network, an indication of a type of UE permitted to perform a 2-Step Random Access Channel (RACH) procedure involving the base station; determine, based on the indication, that the UE corresponds to the type of UE permitted to perform the 2-Step RACH procedure; generate a first message corresponding to the 2-Step RACH procedure; communicate, via the interface, the first message to the base station; and receive, via the interface, from the base station, and in response to the first message, a second message from the base station corresponding to the 2-Step RACH procedure.

In example 22, the subject matter of example 21, or any of the examples herein, wherein the type of UE includes UEs in an Radio Resource Control (RRC) IDLE state.

In example 23, the subject matter of example 21, or any of the examples herein, wherein the type of UE includes UEs in an inactive state.

In example 24, the subject matter of example 21, or any of the examples herein, wherein the type of UE includes UEs capable of communicating in accordance with Ultra- Reliable-Low Latency Communication (URLLC).

In example 25, the subject matter of example 21, or any of the examples herein, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to: perform, in parallel with the 2-Step RACH procedure, a 4- Step RACH procedure with the base station; and communicate with the base station based on whichever RACH procedure, of the 2-Step RACH procedure and the 4- Step RACH procedure is completed first.

In a twenty-sixth example, a computer-readable medium containing program may comprise instructions for causing one or more processors, associated with a base station, to: create System Information Blocks (SIBs) that include information describing a type of User Equipment (UE), of a wireless telecommunication network, that is permitted to perform a 2-Step Random Access Channel (RACH) procedure involving the base station; cause, via the interface, the RF circuitry to communicate a broadcast signal, throughout a coverage area of the base station, that includes the SIBs; process a first message, corresponding to the 2-Step RACH procedure and from a UE corresponding to the described type of UE to create, in response to the first message, a second message corresponding to the 2-Step RACH procedure; and

communicate the second message to the UE to complete the 2-Step RACH procedure. In example 27, the subject matter of example 26, or any of the examples herein, wherein the one or more processors are controlled further to: perform, in parallel with the 2- Step RACH procedure, a 4-Step RACH procedure with the UE.

In example 28, the subject matter of example 26, or any of the examples herein, wherein the one or more processors are further to: monitor network conditions corresponding to a Radio Access Network (RAN) of the base station; and determine, based on the network conditions, the type of UE permitted to perform a 2-Step RACH procedure.

In example 29, the subject matter of example 26, or any of the examples herein, wherein the SIBs include information describing a duration of time during which the type of UE is permitted to perform the 2-Step RACH procedure.

In a thirtieth example, a method, performed by an enhanced NodeB (eNB), may comprise: creating System Information Blocks (SIBs) that include information describing a type of User Equipment (UE), of a wireless telecommunication network, that is permitted to perform a 2-Step Random Access Channel (RACH) procedure involving the base station; causing, via the interface, the RF circuitry to communicate a broadcast signal, throughout a coverage area of the base station, that includes the SIBs; processing a first message, corresponding to the 2-Step RACH procedure and from a UE corresponding to the described type of UE to create, in response to the first message, a second message corresponding to the 2-Step RACH procedure; and communicating the second message to the UE to complete the 2-Step RACH procedure.

In example 31, the subject matter of example 30, or any of the examples herein, further comprising: performing, in parallel with the 2-Step RACH procedure, a 4-Step RACH procedure with the UE.

In example 32, the subject matter of example 30, or any of the examples herein, further comprising: monitoring network conditions corresponding to a Radio Access Network (RAN) of the base station; and determining, based on the network conditions, the type of UE permitted to perform a 2-Step RACH procedure.

In example 33, the subject matter of example 30, or any of the examples herein, wherein the SIBs include information describing a duration of time during which the type of UE is permitted to perform the 2-Step RACH procedure.

In a thirty-fourth example, apparatus of a base station, may comprise: means for monitoring network conditions corresponding to a Radio Access Network (RAN) of the base station; means for creating System Information Blocks (SIBs) that include information describing a type of User Equipment (UE), of a wireless telecommunication network, that is permitted to perform a 2-Step Random Access Channel (RACH) procedure involving the base station; means for causing, via the interface, the RF circuitry to communicate a broadcast signal, throughout a coverage area of the base station, that includes the SIBs; means for processing a first message, corresponding to the 2-Step RACH procedure and from a UE corresponding to the described type of UE to create, in response to the first message, a second message corresponding to the 2-Step RACH procedure; and means for communicating the second message to the UE to complete the 2-Step RACH procedure.

In example 35, the subject matter of example 34, or any of the examples herein, further comprising: means for performing, in parallel with the 2-Step RACH procedure, a 4-Step RACH procedure with the UE.

In example 36, the subject matter of example 34, or any of the examples herein, further comprising: means for monitoring network conditions corresponding to a Radio Access Network (RAN) of the base station; and means for determining, based on the network conditions, the type of UE permitted to perform a 2-Step RACH procedure.

In example 37, the subject matter of example 34, or any of the examples herein, wherein the SIBs include information describing a duration of time during which the type of UE is permitted to perform the 2-Step RACH procedure.

In the preceding specification, various embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.

For example, while series of signals and/or operations have been described with regard to Figs. 2-6 the order of the signals/operations may be modified in other implementations. Further, non-dependent signals may be performed in parallel.

It will be apparent that example aspects, as described above, may be implemented in many different forms of software, firmware, and hardware in the implementations illustrated in the figures. The actual software code or specialized control hardware used to implement these aspects should not be construed as limiting. Thus, the operation and behavior of the aspects were described without reference to the specific software code— it being understood that software and control hardware could be designed to implement the aspects based on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to be limiting. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification.

No element, act, or instruction used in the present application should be construed as critical or essential unless explicitly described as such. An instance of the use of the term "and," as used herein, does not necessarily preclude the interpretation that the phrase "and/or" was intended in that instance. Similarly, an instance of the use of the term "or," as used herein, does not necessarily preclude the interpretation that the phrase "and/or" was intended in that instance. Also, as used herein, the article "a" is intended to include one or more items, and may be used interchangeably with the phrase "one or more." Where only one item is intended, the terms "one," "single," "only," or similar language is used.

Claims

WHAT IS CLAIMED IS:

1. An apparatus of a base station, the apparatus comprising:

an interface to radio frequency (RF) circuitry; and

one or more processors that are controlled to:

create System Information Blocks (SIBs) that include information describing a type of User Equipment (UE), of a wireless telecommunication network, that is permitted to perform a 2-Step Random Access Channel (RACH) procedure involving the base station;

cause, via the interface, the RF circuitry to communicate a broadcast signal, throughout a coverage area of the base station, that includes the SIBs;

process a first message, corresponding to the 2-Step RACH procedure and from a UE corresponding to the described type of UE to create, in response to the first message, a second message corresponding to the 2-Step RACH procedure; and

communicate the second message to the UE to complete the 2-Step RACH procedure.

2. The apparatus of claim 1, wherein the one or more processors are controlled further to: perform, in parallel with the 2-Step RACH procedure, a 4- Step RACH procedure with the

UE.

3. The apparatus of claim 1, wherein the one or more processors are controlled further to: monitor network conditions corresponding to a Radio Access Network (RAN) of the base station; and

determine, based on the network conditions, the type of UE permitted to perform a 2-Step RACH procedure.

4. The apparatus of claim 1, wherein the SIBs include information describing a duration of time during which the type of UE is permitted to perform the 2-Step RACH procedure.

5. An apparatus of a base station, the apparatus comprising:

a computer-readable memory device storing processor-executable instructions; and one or more processors configured to execute the processor-executable instructions, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors to:

monitor network conditions corresponding to a Radio Access Network (RAN) of the base station;

determine, based on the network conditions, a type of User Equipment (UE) permitted to perform a 2-Step Random Access Channel (RACH) procedure;

communicate, to a plurality of UEs connected to the base station, information describing the type of UE permitted to perform the 2- Step RACH procedure;

cause the second message to be communicated to the UE to complete the 2-Step RACH procedure.

6. The apparatus of claim 5, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to:

perform, in parallel with the 2-Step RACH procedure, a 4- Step RACH procedure with the

UE.

7. The apparatus of claim 5, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to:

communicate, to the plurality of UEs, information describing a duration of time during which the type of UE is permitted to perform the 2-Step RACH procedure.

8. A device as in claim 1 or 5, wherein the type of UE includes UEs in an Radio Resource Control (RRC) IDLE state.

9. A device as in claim 1 or 5, wherein the type of UE includes UEs in an inactive state.

10. A device as in claim 1 or 5, wherein the type of UE includes UEs capable of communicating in accordance with Ultra-Reliable-Low Latency Communication (URLLC).

11. An apparatus of a base station, the apparatus comprising:

receive, from a core network of the base station, a request to page a User Equipment (UE) corresponding to the base station, the request including an indication of a high paging priority;

generate, in response to the request, a paging message indicating that the UE is permitted perform a 2- Step RACH procedure involving the base station;

communicate the paging message to the UE;

receive, from the UE and in response to the paging message, a first message corresponding to the 2- Step RACH procedure;

create, in response to the first message, a second message corresponding to the 2- Step RACH procedure; and

communicate the second message to the UE to complete the 2-Step RACH procedure.

12. The apparatus of claim 11, wherein the UE is in a Radio Resource Control (RRC) IDLE state prior to the base station communicating the paging message.

13. The apparatus of claim 11, wherein the UE is in an inactive state prior to the base station communicating the paging message.

14. The apparatus of claim 11, wherein the UE is in a Radio Resource Control (RRC) IDLE state.

15. The apparatus of claim 11, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to:

perform, in parallel with the 2- Step RACH procedure, a 4- Step RACH procedure with the

UE.

16. The apparatus of claim 11, wherein the paging message includes information to enable the UE to perform a non-contention based 2-Step RACH procedure.

17. An apparatus of a base station, the apparatus comprising:

detect a handover procedure corresponding to a User Equipment (UE);

determine that the UE is permitted to perform a 2- Step RACH procedure as part of the handover procedure;

communicate, to the UE and as part of the handover procedure, an indication that the UE is permitted to perform the 2- Step RACH procedure;

receive, the UE, a first message corresponding to the 2-Step RACH procedure; create, in response to the first message, a second message corresponding to the 2-

Step RACH procedure; and

communicate the second message to the UE to complete the 2-Step RACH procedure.

18. The apparatus of claim 17, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to:

UE.

19. The apparatus of claim 17, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to: monitor network conditions corresponding to a Radio Access Network (RAN) of the base station; and

determine, based on the network conditions, that the UE is permitted to perform a 2- Step RACH procedure.

20. The apparatus of claim 17, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to:

provide, to the UE, information to enable the UE to perform a non-contention based 2- Step RACH procedure.

21. An apparatus of a User Equipment (UE), the apparatus comprising:

an interface to radio frequency (RF) circuitry; and

one or more processors that are controlled to:

receive, via the interface and from a base station of a wireless telecommunication network, an indication of a type of UE permitted to perform a 2-Step Random Access

Channel (RACH) procedure involving the base station;

determine, based on the indication, that the UE corresponds to the type of UE permitted to perform the 2- Step RACH procedure;

generate a first message corresponding to the 2- Step RACH procedure;

communicate, via the interface, the first message to the base station; and receive, via the interface, from the base station, and in response to the first message, a second message from the base station corresponding to the 2-Step RACH procedure.

22. The apparatus of claim 21, wherein the type of UE includes UEs in an Radio Resource Control (RRC) IDLE state.

23. The apparatus of claim 21, wherein the type of UE includes UEs in an inactive state.

24. The apparatus of claim 21, wherein the type of UE includes UEs capable of

communicating in accordance with Ultra-Reliable-Low Latency Communication (URLLC).

25. The apparatus of claim 21, wherein execution of the processor-executable instructions, by the one or more processors, causes the one or more processors further to:

perform, in parallel with the 2- Step RACH procedure, a 4- Step RACH procedure with the base station; and

communicate with the base station based on whichever RACH procedure, of the 2- Step RACH procedure and the 4-Step RACH procedure is completed first.