WO2018106658A1

WO2018106658A1 - Systems and methods for channel access in a multefire environment

Info

Publication number: WO2018106658A1
Application number: PCT/US2017/064653
Authority: WO
Inventors: Wenting CHANG; Huaning Niu; Qiaoyang Ye
Original assignee: Intel IP Corporation
Priority date: 2016-12-05
Filing date: 2017-12-05
Publication date: 2018-06-14

Abstract

Techniques described herein include a channel access procedure, for devices operating in the unlicensed spectrum, that includes Listen-Before-Talk (LBT) and frequency hopping. A User Equipment (UE) may receive a Discovery Reference Signal (DRS) transmission that includes the cell ID of a Radio Access Network (RAN) node transmitting the DRS transmission. The UE may determine, based on the cell ID, a frequency hopping pattern used by the RAN node. The RAN node and the UE may communicate with one another based on the frequency hopping pattern. When transitioning to a new channel, the RAN node may perform a LBT procedure to ensure that the channel is already being used. If the new channel does not become available within a dwell time, the RAN node and UE may transition to the next channel in the channel hopping pattern.

Description

SYSTEMS AND METHODS FOR CHANNEL ACCESS IN A MULTEFIRE

ENVIRONMENT

RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Patent Application No. 62/430,194, which was filed on December 5, 2016, and U.S. Provisional Patent Application No. 62/433,654, which was filed on December 13, 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.) Radio Access Networks (RANs) (that often include one or more base stations), and a core network. A UE may connect to the core network by communicating with a base station and registering with the core network.

Communications between the UE and the base station may occur over signal carriers corresponding to a particular frequency band, which may correspond to the licensed or the unlicensed spectrum.

Generally, the licensed spectrum refers to radio frequencies that have been reserved (i.e., licensed) for telecommunication technologies, such as Long-Term Evolution (LTE technologies of the 3rd Generation Partnership (3GPP) Communication Standard). By contrast, the unlicensed spectrum refers to radio frequencies that are not reserved for any particular use, and may therefore be used by any variety of technologies (e.g., Bluetooth®, Wi-Fi, etc.). In some instances, since the unlicensed spectrum is not reserved for any particular wireless technology, telecommunication technologies may be implemented using the unlicensed spectrum. An example of this may include MulteFire® technology, which includes a standalone implementation of LTE in the unlicensed spectrum, meaning that MulteFire® may be implemented in its entirety without assistance from licensed spectrum technologies.

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 sequence flow diagram of an example of a channel access technique using frequency hopping among unlicensed frequency bands;

Fig. 3 is a table of an example frequency hopping pattern that may be implemented by User Equipment (UE) UE and Radio Access Network (RAN) node for communication purposes;

Fig. 4 is a sequence flow diagram of an example of a Random Access Channel (RACH) procedure using the channel access techniques described herein;

Fig. 5 is a flowchart of an example process for a channel access procedure, from the perspective of a RAN node, in a MulteFire® environment;

Fig. 6 is a flowchart of an example process for a channel access procedure, from the perspective of a UE, in a MulteFire® environment;

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.

Wireless telecommunication techniques often involve two wireless devices that discover one another, become initially synchronized with one another, and proceed to determine one or more wireless channels via which the devices are to communicate with one another. This channel selection process is sometimes referred to as channel access.

Channels, and the procedures by which channels are selected and used, in the licensed spectrum are typically well-defined according to established communication standards, such as the Long-Term Evolution (LTE) Communication Standard of the 3rd Generation Partnership (3GPP). As the unlicensed spectrum is not reserved for specific wireless communication standards, different devices may use different channels, timings, and other procedures to communicate with one another, giving rise to a more unpredictable wireless signaling environment. As such, certain communication techniques may address issues inherent in such a varied and unpredictable environment. Examples of these techniques include Listen-Before-Talk (LBT) and frequency hopping (sometimes referred to as frequency hopping).

LBT may include a scenario in which a device detects, measures, etc., whether a particular channel is available for communication (as opposed to, for example, already being used by other wireless devices in the area). A benefit of determining whether a channel is available before using the channel may include a reduction in the frequency with which unsuccessful communications are attempted. However, while LBT may help ensure successful communications, LBT is not well suited for long distances because of the possibility of a hidden node (or so-called "man in the middle") attack.

Frequency hopping may include a scenario in which two wireless devices periodically change (i.e., "hop") from one channel to another during a communication session. A benefit of frequency hopping may include making it more difficult for hidden node attacks so long as the hidden node remains unaware of the channels that will be used during the communication session and when channel changes are to occur. However, while frequency hopping may help limit the risk of hidden node attacks, frequency hopping can be cumbersome to implement on a device (e.g. , a base station) that often communicates with a very large quantity of other (e.g. , User Equipment (UE)) devices since the base station may be burdened with managing the frequency hopping for each UE, which is one reason why frequency hopping is typically more suited to one-to-one communication scenarios (such as

Bluetooth®).

Techniques described herein include a channel access procedure, for devices operating in the unlicensed spectrum, that includes Listen-Before-Talk (LBT) and frequency hopping, in which LBT is used in the downlink and frequency hopping is used in the uplink. A Radio Access Network (RAN) node (e.g. , an enhanced Node B (eNB)) may communicate a Discovery Reference Signal (DRS) transmission over one or more anchor channels/anchor carriers that a UE may receive and recognize as a DRS from a network access point. The DRS transmission may include a cell ID of the RAN node, which the UE may use to derive a frequency hopping partem being used by the RAN node. The frequency hopping pattern may include a sequence of channels the RAN node uses to communicate with UEs in the area and a duration of time for which each channel is used before transitioning to the next channel in the frequency hopping pattern. The UE may also extract a Sequence Frame Number (SFN) and subframe number from the DRS transmission, and use the SFN and subframe number to determine the actual time in which each channel is being used (e.g. , to become synchronized with the actual channel transition of the frequency hopping pattern).

The UE and the RAN node may use the frequency hopping pattem to communicate with one another. For example, in accordance with the frequency hopping pattern, the RAN node may provide the UE with system information (e.g. , subframe configuration information, Random Access Channel (RACH) configuration information, etc.), and the UE may respond by initiating a RACH procedure to establish a connection with the RAN node. As such, the frequency hopping pattern may enable the UE and the RAN to implement frequency hopping while communicating with one another.

When transitioning from one channel to another, the RAN node may perform a LBT procedure to ensure that the next channel is available. Meanwhile, the UE may monitor the channel in anticipation of a transmission from the RAN node. Additionally, the UE may (without performing a LBT procedure) communicate with the RAN node in the uplink direction in accordance with the frequency hopping pattem. When the RAN node determines that the channel is available, the RAN node may use the channel in accordance with the frequency hopping pattern. When the channel is unavailable, the RAN node may not attempt to use the channel but instead may wait for the next channel as per the frequency hopping pattern.

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 altematively 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 S 1 interface 113 is split into two parts : the S 1 -U interface 114, which carries traffic data between the RAN nodes 111 and 112 and the serving gateway (S-GW) 122, and the Sl-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-3GPP 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 sequence flow diagram of an example of a channel access technique using frequency hopping among unlicensed frequency bands. The example of Fig. 2 may include UE 101 and RAN node 111, examples of which are described above with reference to Fig. 1. In some embodiments, RAN node 111 may alternatively be RAN node 112.

As shown, RAN node 111 may send a Discovery Reference Signal (DRS) transmission to UE 101 using an anchor channel (line 210). The DRS may be transmitted by RAN node 111 periodically (e.g., during a periodic DRS transmission window). In some embodiments, multiple anchor carriers may be defined, and RAN node 111 may randomly select one or many anchor channels for the DRS transmission. RAN node 111 may be configured to only transmit the DRS via anchor channels. In embodiments where RAN node 111 may use one or more of many anchor channels, UE 101 may be capable of searching over each of the anchor channels for the DRS transmission from RAN node 111. As described in further detail below, RAN node 111 may be configured to periodically return to the anchor channels to perform DRS transmissions and/or may perform a LBT procedure with respect to one or more anchor channels before using the anchor channel for the DRS transmission.

The DRS transmission may include information for initiating communication between RAN node 111 and UE 101, such as synchronization information and system information. Examples of such information may include a Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS), Physical Broadcast Channel (PBCH), enhanced System Information Blocks (eSIB or SIBa), enhanced Primary Synchronization Signal (ePSS), and enhanced Secondary Synchronization Signal (eSSS), enhanced Master

Information Blocks (eMIB), etc. The DRS transmission may also include a cell ID of RAN node 111. Examples of a cell ID may include an eNB ID, a Primary Cell Identification (PCI) value (which may involve a PCI collusion scenario), a Cell Global Identification (CGI) value, etc. Alternatively, system information may be transmitted in a different communication (e.g., a PDCCH transmission) than the DRS transmission.

UE 101 may determine the cell ID of RAN node 111 and essential system information (e.g. , eSIBs) based on the information contained in the DRS transmission (block 220). UE 101 may also determine, derive, etc., a frequency hopping pattern for communicating with RAN node 111 (block 220). For example, UE 101 may apply the cell ID of RAN node 111 to an algorithm, executable code, etc., stored by UE 101, for determining the frequency hopping pattern used by RAN node 111. UE 101 may resolve synchronization with respect to using the channel hopping pattern based on timing reference information, such as System Frame Number (SFN) and subframe number, which may be part of the DRS transmission. For example, the frequency hopping pattern determined by UE 101 (based on, for example, the cell ID of RAN node 101) may generally set forth the channels of the frequency hopping partem, the sequence of the channels of the frequency hopping pattern, and a duration corresponding to each channel, UE 101 may use the SFN and/or subframe number to become synchronized with the frequency hopping pattern (e.g., when the frequency hopping pattern is to begin).

Fig. 3 is a table of an example frequency hopping pattern that may be implemented by UE 101 and RAN node 111 for communication purposes. As shown, for example, frequency hopping pattern may include a sequence of channels that are used at different times for communication purposes. For instance, RAN node 111 may use an anchor channel to initially communicate with UE 101. At time 310, RAN node 111 may switch from the anchor channel to a first channel (e.g. , Channel 1), which uses different radio frequencies than the anchor channel. At time 320, RAN node 111 may switch back to the anchor channel for a while, and at time 330, may begin using another channel (e.g. , Channel 2), which corresponds to a different frequency band than the anchor channel or the previous non-anchor channel (Channel 1). Later, at time 340, the frequency hopping partem may transition back to the anchor channel, and the frequency hopping partem may proceed as such by using different channels at different times.

The example frequency hopping pattern of Fig. 3 is provided as a non-limiting example. In practice, the quantity, channel sequence, times, and/or other features of the example frequency hopping partem may be different. For example, while the example frequency hopping partem of Fig. 3 includes the use of an anchor channel before and after each non-anchor channel (e.g. , Channel 1 and Channel 2), in another embodiment, an example frequency hopping partem may include the use of two or more non-anchor channels between the periodic use of the anchor channel. As another example, while the frequency hopping partem of Fig. 3 includes only two non-anchor channels, in another example, a frequency hopping pattern may include more and/or a different arrangement of non-anchor channels and/or frequency bands corresponding to the channels shown in Fig. 3. As shown in Fig. 3, the frequency hopping pattern may be configured to return to an anchor channel more frequency than other channels included in the frequency hopping pattern.

In some embodiments, for unicast information transmissions, a starting channel of one specific subframe may be conveyed to UE 101 through high layer signaling or indicated via the PDCCH. In such scenarios, different UEs 101 may transmit in different channels using Frequency Division Multiplexing (FDM) and sharing the same frequency hopping pattern. In some embodiments, for broadcasting information, e.g. paging information, the starting channel of one specific subframe may be cell specific, can be pre-defined or configured by RAN node 111 through Physical Broadcast Channel (PBCH) System Information (SI). Additionally, as described above, RAN node 111 may perform a LBR procedure on a channel before using the channel to communicate with UE 101. In some embodiments, a LBR gap may be specified to give RAN node 111 time to perform the LBT. In some embodiments, the LBR gap may include a specified number of symbols in a first subframe of the new channel.

Returning to Fig. 2, RAN node 111 may perform a LBT procedure when

communicating with UE 101 in accordance with the frequency hopping partem (block 230). For example, since RAN node 111 and UE 101 may be using channels within the non- licensed radio frequency spectrum, RAN node 111 may perform a LBT procedure before communicating with UE 101 in the downlink direction. A LBT procedure, as described herein, may include measuring a level of congesting, signal interference, a signal-to-noise ratio, etc., and/or comparing the measured conditions to a threshold level that defines whether the channel is currently in use. Doing so may, for example, better ensure that a particular channel (whether an anchor channel or a non-anchor channel) that RAN node 111 is to use to communicate with UE 101 may not have such a high level of interference, signal-to-noise ratio, so as to undermine the use of the channel.

As described in further detail with respect to Fig. 5, when RAN node 111 determines that a channel is available (e.g. , not being used), RAN node 111 may use the channel to communicate information to UE 101. By contrast, when RAN node 111 determines that a channel is not available (e.g. , is being used by other devices), RAN node 111 may wait for the channel to become available before using the channel to communicate with UE 101. If the channel does not become available within the time allotted by the channel hopping schedule, RAN node 111 may move on to the next channel in the frequency hopping pattern. In some embodiments, prior to transmitting a DRS in an anchor channel, RAN node 111 may be perform a LBT procedure on the anchor channel (e.g., to verify that the anchor channel is available). In embodiments where RAN node 111 may communicate the DRS overt multiple channels, RAN node 111 may perform a LBT procedure for each anchor channel and only communicate the DRS (within a DRS window) on anchor channels that are determined to be available. Alternatively, RAN node 111 may randomly select one or more (but not all) of the available anchor channels for transmitting the DRS. UE 101 may be aware of all possible anchor channels that RAN node 111 may use to communicate a DRS, and may therefore search, listen to, etc., these channels for a DRS from RAN node 111.

As such, RAN node 111 may communicate PDCCH information and PDSCH information to UE 101 in accordance with the frequency hopping partem (line 240). PDCCH information may include physical layer control channel information for communications in the downlink direction, which may include scheduling information, resource block assignments for PDSCH information. The PDCCH information may be sent to UE 101 shortly before PDSCH information begins being sent to UE 101. PDSCH information may include user specific data (e.g. , a downlink payload) and/or Random Access Response Messages.

UE 101 may communicate PUCCH information and PUSCH information to RAN node 111 in accordance with the frequency hopping pattem (line 250). PUCCH information may include physical layer control information for communications in the uplink direction. PUCCH information may include HARQ messages, Acknowledgement (ACK) messages, Negative Acknowledgement (NACK) messages, Carrier Quality Indication (CQI) information, feedback information to optimize Multiple Input and Multiple Output (MIMO) communications, etc. PUSCH information may user information data, MIMO related parameters, transport format indicators, etc.

In some embodiments, before RAN node 111 begins using a different channel to communicate with UE 101, RAN node 111 may perform another LBT procedure to ensure that the channel is available for use. By contrast, in some embodiments, UE 101 may not perform a LBT procedure since the availability of the channel with respect to

communications from UE 101 to RAN node 111 may be assumed when UE 101 receives information from RAN node 111 in the downlink direction.

Fig. 4 is a sequence flow diagram of an example of a Random Access Channel (RACH) procedure using the channel access techniques described herein. The example of Fig. 3 may include UE 101 and RAN node 111, examples of which are described above with reference to Fig. 1. In some embodiments, RAN node 111 may alternatively be RAN node 112.

As shown, the example of Fig. 4 may include certain operations (e.g. , line 410, block 420, and block 430) that are similar to operations described above with reference to Fig. 2 (e.g. , line 210, block 220, and block 230), and therefore will not be repeated in detail.

Referring now to line 440 of Fig. 4, after RAN node 111 has sent a DRS transmission to UE 101 via an anchor channel, UE 101 has determined (based on a cell ID of RAN node 101) a channel hopping pattern for communicating with RAN node 111, and RAN node 111 has performed an LBT procedure for an anchor channel and a data channel, RAN node 111 may communicate system information (e.g., downlink/uplink subframe configuration information, RACH configuration information, etc.) to enable UE 101 to proceed with a RACH procedure (line 440).

In response to the system information from RAN node 111, UE 101 may initiate a RACH procedure by communicating a RACH procedure Msg 1 to RAN node 111 (line 450). The channel used by UE 101 to do so may be consistent with, based on, correspond to, etc., the frequency hopping pattern previously determined by UE 101. Upon receiving the RACH procedure Msg 1, RAN node 111 may determine, based on the frequency hopping pattern, which channel to use to respond to UE 101. RAN node 111 may also perform a LBT procedure to verify that the determined channel is available (block 460). Assume that the channel is available.

RAN node 111 may respond to the RACH procedure Msg 1 by sending a RACH procedure Msg 2 to UE 101 via the channel determined channel (line 470). In response, UE 101 may communicate a RACH procedure Msg 3 to RAN 111 in continuation of the ongoing RACH procedure (line 480). The channel used by UE 101 to do so may be consistent with, based on, correspond to, etc., the frequency hopping pattern previously determined by UE 101. Upon receiving the RACH procedure Msg 3, RAN node 111 may determine, based on the frequency hopping pattern, which channel to use to respond to UE 101. RAN node 111 may also perform a LBT procedure to verify that the determined channel is available (block 490). Assume that the channel is available. RAN node 111 may respond to the RACH procedure Msg 3 by sending a RACH procedure Msg 4 to UE 101 via the channel determined channel (line 495).

Fig. 5 is a flowchart of an example process 500 for a channel access procedure, from the perspective of a RAN node, in a MulteFire® environment. Process 500 may be implemented by RAN node 111. In some embodiments, one or more of the operations described in Fig. 5 may be performed in whole, or in part, by another device, such as RAN node 112.

As shown, process 500 may include determining a frequency hopping partem based on a cell ID (block 510). For example, RAN node 111 may be assigned a cell ID that uniquely identifies RAN node 111 from among other RAN nodes of a wireless network. Examples of such a cell ID may include a PCI value, a CGI value, or another type of unique identifier assigned to, or associated with, RAN node 111. In some embodiments, RAN node 111 may be configured to execute an internal process that determines, identifies, etc., a frequency hopping partem that RAN node 111 is to implement. In some embodiments, this process may be similar to the process performed by UE 101 when determining a frequency hopping pattern for a given RAN node 111. In some embodiments, RAN node 111 may perform this process as RAN node 111 may already be configured with a frequency hopping partem upon initial deployment.

Process 500 may include selecting a channel based on the frequency hopping pattern

(block 520). The frequency hopping partem determined by RAN node 111 may include an indication of the channel(s) that RAN node 111 is to be using to communicate with one or more UEs 101. RAN node 111 may use a single channel to communicate with a particular UE 101 or multiple channels (simultaneously) to communicate with UE 101. In some embodiments, RAN node 101 may use multiple instances of the same type of channel. For example, RAN node 111 may be configured to use multiple anchor channels, such that RAN node 111 may send out multiple DRS transmissions over multiple anchor channels.

Process 500 may also include performing a LBT procedure to determine whether the channel is available (block 530). For example, before RAN node 111 begins using a channel to communicate information to UE 101, RAN node 111 may detect, measure, etc., the conditions corresponding to the channel. Examples of such conditions may include a level of wireless activity, signal interference, signal-to-noise ratio, etc., to determine whether the channel is suitable for communicating information to UE 101. In some embodiments, RAN node 111 may make such a determination by, for example, comparing one or more conditions or measurements to one or more corresponding threshold levels.

When the channel is available (block 540 - Yes), process 500 may include using the selected channel to communicate with UE 101 in the uplink and downlink directions (block 550). This may include providing UE 101 with control level information (e.g. , uplink (UL) grant information via the PDCCH) and/or data level information (e.g., via the PDSCH). While uplink transmission control information (e.g. , the carrier scheduled for UL

transmission) may be inferred (or implicitly provided) to UE 101 based on the frequency hopping pattern, RAN node 111 may also provide such information explicitly (which may result in, or amount to, a departure from the frequency hopping pattern). For example, RAN node 111 may use a PDCCH to provide UE 101 with explicit carrier scheduling information for uplink transmissions, to indicate the carrier that UE 101 is to use for uplink transmissions (which may be provided in a particular downlink control information (DCI) field designated for carrier indication), etc. In some embodiments, UE 101 may include a UL transmission map for interpreting transmission control information (e.g. , a UL grant from RAN node 111. For example, RAN node 111 may use one channel to provide a UL grant to UE 101, and UE 101 may map the channel used by RAN node 111 to determine the channel to which the UL grant actually corresponds, and may use that channel for subsequent uplink transmissions. In some embodiments, RAN node 111 may use one channel to provide an explicit uplink grant for a second channel, and UE 101 may use the second channel for uplink transmissions. As such, the channel access techniques described herein may include the use of cross-carrier and/or self-carrier scheduling.

In some embodiments, existing fields of the PDCCH may be used (e.g. , resource block assignment field) may be used (e.g., reinterpreted) for carrier indication. In addition to using the selected channel to explicitly provide control level information and/or data level information, in some embodiments RAN node 111 may be configured to provide repeated transmissions of PDCCH information and/or PDSCH information. Similarly, RAN node 111 may also be configured to receive repeated transmission vie the PUSCH and/or PUCCH.

When the channel is unavailable (block 540 - No), process 500 may include determining whether the channel is busy (block 560). For example, RAN node 111 may perform a channel sensing procedure to determine whether the channel is being used.

Assume that RAN node 111 determines that the channel is being used and is therefore unavailable and unsuitable for communicating with UE 101. As such, RAN node 111 may monitor the channel for a preselected period (also referred to as a dwell period dwell time, etc.) in case the channel becomes available. Meanwhile, UE 101 may be listening to the channel in case RAN node 111 begins using the channel. UE 101 may listen for

communications from RAN node 111 for the dwell period.

If the channel becomes available within the dwell period, RAN node 111 may being using the channel to communicate information to UE 101. If the channel does not become available within the dwell period, RAN node 111 may transition to the next channel in the frequency hopping partem. Since the dwell period may be shorter in duration than the time allocated to using the channel per the frequency hopping partem, switching channels based on the dwell period (instead of waiting for the entire duration allocated to the channel by the frequency hopping pattern) may increase efficiency and the overall communication capabilities between RAN node 111 and UE 101. Additionally, while RAN node 111 may not provide an explicit indication of the transition to the next channel in the frequency hopping pattern, UE 101 may infer that RAN node 111 is hopping to the next channel in the frequency hopping pattern because no communications were received from RAN node 111 during the dwell period.

Fig. 6 is a flowchart of an example process 600 for a channel access procedure, from the perspective of a UE, in a MulteFire® environment. Process 600 may be implemented by UE 101. In some embodiments, one or more of the operations described in Fig. 6 may be performed in whole, or in part, by another device, such as one or more of the devices described above with reference to Fig. 1.

As shown, process 600 may include determining a cell ID (block 610). For example, when UE 101 is powered on, UE 101 may search for base stations or other types of RAN nodes that may be in the area. As described herein, UE 101 may detect a DRS transmission from RAN node 111. The DRS transmission may include timing and synchronization information for communicating with RAN node 111 , in addition to a cell ID that uniquely identifies RAN node 111. UE 101 may extract the cell ID from the DRS transmission. The DRS transmission may be provided in in one or more anchor channels of RAN node 111, and UE 101 may be configured (e.g. , during manufacture) to search for, and identify, the anchor channels and DRS transmissions.

Process 600 may also include determining a frequency hopping partem based on the cell ID (block 620). For example, UE 101 may have a function, algorithm, or another type of executable code or software that is capable of receiving the cell ID as an input and generating a frequency hopping pattern that UE 101 may use to begin communicating with RAN node 111 as described herein. Additionally, or alternatively, UE 101 may have access to records that include cell IDs and frequency hopping patterns associated with each cell ID, and UE 101 may determine the frequency hopping pattern by querying the records based on the cell ID from RAN node 111. The frequency hopping partem may indicate a pattern or sequence of channels, and corresponding duration for each, used by RAN node 111 to communicate with UEs 101. In some embodiments, UE 101 may derive actual start and end times of each channel and channel transition based on SFN and subframe number information from the DRS transmission. As such, UE 101 may derive the frequency hopping partem from the cell ID of RAN node and may determine the actual start and end times of the channel transitions from information provided n DRS transmission from RAN node 101.

Process 600 may include communicating PUSCH and PUCCH information using the selected channel (block 640). UE 101 may use the selected channel to communicate control layer and data layer information to RAN node 111. Further, UE 101 may determine and monitor a duration, a point in time, etc., for transitioning from the selected channel to the next channel provided in the frequency hopping pattern. Upon arriving at a time to transition from the selected channel to the next channel in the frequency hopping pattern, UE 101 may begin monitoring, listening, etc. for communications from RAN 111 as confirmation that the new channel is suitable for continued communications. As described above, UE 101 may monitor the new channel during the dwell time, which may be a standardized duration or a duration previously specified by RAN node 111 (e.g., in system information provided by RAN node 111, in a PDCCH message, or at another time). If RAN node 111 does not use the new channel to communicate with UE 101 during the dwell period, UE 101 may be configured to determine the next channel in the frequency hopping partem and start listening for RAN node 111 on that channel.

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 704A, 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 704A-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 704A-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 (WMAN), 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+1 (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 Radio Access Network (RAN) node may comprise: an interface to radio frequency (RF) circuitry; and one or more processors to: cause, via the interface to the RF circuitry, a cell ID of the RAN node to be communicated to User Equipment (UE), the cell ID being associated with a frequency hopping pattern used by the RAN node to communicate with the UE via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels for

communicating with the UE; and prior to transitioning to a channel to communicate with the UE, in accordance with the frequency hopping pattern, perform a Listen-Before-Talk (LBT) procedure on the channel to verify that the channel is available for use.

In example 2, the subject matter of example 1 , or any of the examples herein, wherein the one or more processors are further to: cause a cell ID of the RAN node to be sent to the UE in a Discovery Reference Signal (DRS) transmitted over an anchor channel of the RAN node.

In example 3, the subject matter of example 1 , or any of the examples herein, wherein, prior to transmission of the DRS, an availability of the anchor channel is verified via an application of the LBT procedure to the anchor channel.

In example 4, the subject matter of example 1 , or any of the examples herein, wherein the one or more processors are further to: when the LBT procedure indicates that the channel is not available, monitor whether the channel becomes available within a specified duration, when the channel becomes available within the specified duration, use the channel to communicate with the UE, and when the channel remains unavailable throughout the specified duration, transition to a subsequent channel of the frequency hopping pattern.

In a fifth example, an apparatus of a User Equipment (UE) may comprise: an interface to radio frequency (RF) circuitry; and one or more processors to: receive, via the interface to the RF circuity, a reference signal transmitted by a Radio Access Network (RAN) node, the reference signal including a cell ID of the RAN node; determine, based on the cell ID, a frequency hopping partem used by the RAN node to communicate via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels; and communicate, via the interface to the RF circuitry, with the RAN node in accordance with the frequency hopping partem

In example 6, the subject matter of example 5, or any of the examples herein, wherein the reference signal is a Discovery Reference Signal transmitted over an anchor channel of the RAN node.

In example 7, the subject matter of example 1 or 5, or any of the examples herein, wherein the UE is an Narrowband Internet-of-Things (NB-IoT) device.

In example 8, the subject matter of example 1 or 5, or any of the examples herein, wherein the sequence of radio frequency channels of the frequency hopping partem is a cell- specific hopping pattern.

In example 9, the subject matter of example 1 or 5, or any of the examples herein, wherein the cell ID is a Physical Cell ID (PCI) that uniquely identifies the RAN node.

In a tenth example, a computer-readable medium may contain program instructions for causing one or more processors, associated with a Radio Access Network (RAN) node, to: cause a cell ID of the RAN node to be communicated to User Equipment (UE), the cell ID being associated with a frequency hopping pattern used by the RAN node to communicate with the UE via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels for communicating with the UE; and prior to transitioning to a channel to communicate with the UE, in accordance with the frequency hopping pattern, perform a Listen-Before-Talk (LBT) procedure on the channel to verify that the channel is available for use.

In example 11 , the subject matter of example 10, or any of the examples herein, wherein the one or more processors are further to: cause a cell ID of the RAN node to be sent to the UE in a Discovery Reference Signal (DRS) transmitted over an anchor channel of the RAN node.

In example 12, the subject matter of example 10, or any of the examples herein, wherein, prior to transmission of the DRS, an availability of the anchor channel is verified via an application of the LBT procedure to the anchor channel.

In example 13, the subject matter of example 10, or any of the examples herein, wherein the one or more processors are further to: when the LBT procedure indicates that the channel is not available, monitor whether the channel becomes available within a specified duration, when the channel becomes available within the specified duration, use the channel to communicate with the UE, and when the channel remains unavailable throughout the specified duration, transition to a subsequent channel of the frequency hopping pattern.

In a fourteenth example, a computer-readable medium may contain program instructions for causing one or more processors, associated with User Equipment (UE), to: receive a reference signal transmitted by a Radio Access Network (RAN) node, the reference signal including a cell ID of the RAN node; determine, based on the cell ID, a frequency hopping pattern used by the RAN node to communicate via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels; and communicate with the RAN node in accordance with the frequency hopping partem.

In example 15, the subject matter of example 14, or any of the examples herein, wherein the reference signal is a Discovery Reference Signal transmitted over an anchor channel of the RAN node.

In example 16, the subject matter of example 10 or 15, or any of the examples herein, wherein the UE is an Narrowband Internet-of-Things (NB-IoT) device.

In example 17, the subject matter of example 10 or 15, or any of the examples herein, wherein the sequence of radio frequency channels of the frequency hopping partem is a cell- specific hopping pattern.

In example 18, the subject matter of example 10 or 15, or any of the examples herein, wherein the cell ID is a Physical Cell ID (PCI) that uniquely identifies the RAN node.

In a nineteenth example, an apparatus of a Radio Access Network (RAN) node, mahy comprise: means for causing a cell ID of the RAN node to be communicated to User

Equipment (UE), the cell ID being associated with a frequency hopping partem used by the RAN node to communicate with the UE via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels for communicating with the UE; and means for, prior to transitioning to a channel to

communicate with the UE, in accordance with the frequency hopping pattern, performing a Listen-Before-Talk (LBT) procedure on the channel to verify that the channel is available for use.

In example 20, the subject matter of example 19, or any of the examples herein, further comprising: means for causing a cell ID of the RAN node to be sent to the UE in a Discovery Reference Signal (DRS) transmitted over an anchor channel of the RAN node.

In example 21 , the subject matter of example 19, or any of the examples herein, wherein, prior to transmission of the DRS, an availability of the anchor channel is verified via an application of the LBT procedure to the anchor channel.

In example 22, the subject matter of example 19, or any of the examples herein, further comprising: when the LBT procedure indicates that the channel is not available, means for monitoring whether the channel becomes available within a specified duration, when the channel becomes available within the specified duration, means for using the channel to communicate with the UE, and when the channel remains unavailable throughout the specified duration, means for transitioning to a subsequent channel of the frequency hopping partem.

In a twent -third example, an apparatus of a Radio Access Network (RAN) node, comprising: means for receiving a reference signal transmitted by a Radio Access Network (RAN) node, the reference signal including a cell ID of the RAN node; means for determining, based on the cell ID, a frequency hopping pattern used by the RAN node to communicate via an unlicensed radio frequency spectrum, the frequency hopping partem including a sequence of radio frequency channels; and means for communicating with the RAN node in accordance with the frequency hopping pattern.

In example 24, the subject matter of example 23, or any of the examples herein, wherein the reference signal is a Discovery Reference Signal transmitted over an anchor channel of the RAN node.

In example 25, the subject matter of example 19 or 23, or any of the examples herein, wherein the UE is an Narrowband Internet-of-Things (NB-IoT) device.

In example 26, the subject matter of example 19 or 23, or any of the examples herein, wherein the sequence of radio frequency channels of the frequency hopping partem is a cell- specific hopping pattern. In example 27, the subject matter of example 19 or 23, or any of the examples herein, wherein the cell ID is a Physical Cell ID (PCI) that uniquely identifies the RAN node.

In a twenty-eighth example, a method performed by a Radio Access Network (RAN) node, may comprise: causing a cell ID of the RAN node to be communicated to User Equipment (UE), the cell ID being associated with a frequency hopping pattern used by the RAN node to communicate with the UE via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels for

communicating with the UE; and prior to transitioning to a channel to communicate with the UE, in accordance with the frequency hopping partem, performing a Listen-Before-Talk (LBT) procedure on the channel to verify that the channel is available for use.

In example 29, the subject matter of example 28, or any of the examples herein, further comprising: causing a cell ID of the RAN node to be sent to the UE in a Discovery Reference Signal (DRS) transmitted over an anchor channel of the RAN node.

In example 30, the subject matter of example 28, or any of the examples herein, wherein, prior to transmission of the DRS, an availability of the anchor channel is verified via an application of the LBT procedure to the anchor channel.

In example 31 , the subject matter of example 28, or any of the examples herein, further comprising: when the LBT procedure indicates that the channel is not available, monitoring whether the channel becomes available within a specified duration, when the channel becomes available within the specified duration, using the channel to communicate with the UE, and when the channel remains unavailable throughout the specified duration, transitioning to a subsequent channel of the frequency hopping pattern.

In a thirty-second example, a method performed by a User Equipment (UE), may comprise: receiving a reference signal transmitted by a Radio Access Network (RAN) node, the reference signal including a cell ID of the RAN node; determining, based on the cell ID, a frequency hopping partem used by the RAN node to communicate via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels; and communicating with the RAN node in accordance with the frequency hopping pattern.

In example 33, the subject matter of example 32, or any of the examples herein, wherein the reference signal is a Discovery Reference Signal transmitted over an anchor channel of the RAN node. In example 34, the subject matter of example 28 or 32, or any of the examples herein, wherein the UE is an Narrowband Internet-of-Things (NB-IoT) device.

In example 35, the subject matter of example 28 or 32, or any of the examples herein, wherein the sequence of radio frequency channels of the frequency hopping partem is a cell- specific hopping pattern.

In example 36, the subject matter of example 28 or 32, or any of the examples herein, wherein the cell ID is a Physical Cell ID (PCI) that uniquely identifies the RAN node.

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 and 4-6 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 :

An apparatus of a Radio Access Network (RAN) node, comprising:

an interface to radio frequency (RF) circuitry; and

one or more processors to:

cause, via the interface to the RF circuitry, a cell ID of the RAN node to be communicated to User Equipment (UE), the cell ID being associated with a frequency hopping partem used by the RAN node to communicate with the UE via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels for communicating with the UE; and

prior to transitioning to a channel to communicate with the UE, in accordance with the frequency hopping pattern, perform a Listen-Before-Talk (LBT) procedure on the channel to verify that the channel is available for use.

2. The apparatus of claim 1 , wherein the one or more processors are further to:

cause a cell ID of the RAN node to be sent to the UE in a Discovery Reference Signal (DRS) transmitted over an anchor channel of the RAN node.

3. The apparatus of claim 1 , wherein, prior to transmission of the DRS, an availability of the anchor channel is verified via an application of the LBT procedure to the anchor channel.

4. The apparatus of claim 1 , wherein the one or more processors are further to:

when the LBT procedure indicates that the channel is not available,

monitor whether the channel becomes available within a specified duration, when the channel becomes available within the specified duration,

use the channel to communicate with the UE, and

when the channel remains unavailable throughout the specified duration,

transition to a subsequent channel of the frequency hopping pattern.

5. An apparatus of a User Equipment (UE) comprising:

an interface to radio frequency (RF) circuitry; and

one or more processors to: receive, via the interface to the RF circuity, a reference signal transmitted by a Radio Access Network (RAN) node, the reference signal including a cell ID of the RAN node;

determine, based on the cell ID, a frequency hopping pattern used by the RAN node to communicate via an unlicensed radio frequency spectrum, the frequency hopping partem including a sequence of radio frequency channels; and

communicate, via the interface to the RF circuitry, with the RAN node in accordance with the frequency hopping partem.

6. The apparatus of claim 1, wherein the reference signal is a Discovery Reference Signal transmitted over an anchor channel of the RAN node.

7. The apparatus of claim 1 or 5, wherein the UE is an Narrowband Internet-of-Things (NB-IoT) device.

8. The apparatus of claim 1 or 5, wherein the sequence of radio frequency channels of the frequency hopping pattern is a cell-specific hopping partem.

9. The apparatus of claim 1 or 5, wherein the cell ID is a Physical Cell ID (PCI) that uniquely identifies the RAN node.

10. A computer-readable medium containing program instructions for causing one or more processors, associated with a Radio Access Network (RAN) node, to:

cause a cell ID of the RAN node to be communicated to User Equipment (UE), the cell ID being associated with a frequency hopping pattern used by the RAN node to communicate with the UE via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels for communicating with the UE; and

11. The computer-readable medium of claim 10, wherein the one or more processors are further to:

12. The computer-readable medium of claim 10, wherein, prior to transmission of the DRS, an availability of the anchor channel is verified via an application of the LBT procedure to the anchor channel.

13. The computer-readable medium of claim 10, wherein the one or more processors are further to:

when the LBT procedure indicates that the channel is not available,

use the channel to communicate with the UE, and

when the channel remains unavailable throughout the specified duration,

transition to a subsequent channel of the frequency hopping pattern.

14. A computer-readable medium containing program instructions for causing one or more processors, associated with User Equipment (UE), to:

receive a reference signal transmitted by a Radio Access Network (RAN) node, the reference signal including a cell ID of the RAN node;

determine, based on the cell ID, a frequency hopping pattern used by the RAN node to communicate via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels; and

communicate with the RAN node in accordance with the frequency hopping pattern.

15. The computer-readable medium of claim 14, wherein the reference signal is a Discovery Reference Signal transmitted over an anchor channel of the RAN node.

16. The computer-readable medium of claim 10 or 14, wherein the UE is an Narrowband Internet-of-Things (NB-IoT) device.

17. The computer-readable medium of claim 10 or 14, wherein the sequence of radio frequency channels of the frequency hopping pattern is a cell-specific hopping pattem.

18. The computer-readable medium of claim 10 or 14, wherein the cell ID is a Physical Cell ID (PCI) that uniquely identifies the RAN node.

19. An apparatus of a Radio Access Network (RAN) node, comprising:

means for causing a cell ID of the RAN node to be communicated to User Equipment (UE), the cell ID being associated with a frequency hopping pattem used by the RAN node to communicate with the UE via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels for communicating with the UE; and

means for, prior to transitioning to a channel to communicate with the UE, in accordance with the frequency hopping pattem, performing a Listen-Before-Talk (LBT) procedure on the channel to verify that the channel is available for use.

20. The apparatus of claim 19, further comprising:

means for causing a cell ID of the RAN node to be sent to the UE in a Discovery Reference Signal (DRS) transmitted over an anchor channel of the RAN node.

21. The apparatus of claim 19, wherein, prior to transmission of the DRS, an availability of the anchor channel is verified via an application of the LBT procedure to the anchor channel.

22. The apparatus of claim 19, further comprising:

when the LBT procedure indicates that the channel is not available,

means for monitoring whether the channel becomes available within a specified duration,

when the channel becomes available within the specified duration,

means for using the channel to communicate with the UE, and when the channel remains unavailable throughout the specified duration,

means for transitioning to a subsequent channel of the frequency hopping pattern.

23. An apparatus of a Radio Access Network (RAN) node, comprising: means for receiving a reference signal transmitted by a Radio Access Network (RAN) node, the reference signal including a cell ID of the RAN node;

means for determining, based on the cell ID, a frequency hopping pattern used by the RAN node to communicate via an unlicensed radio frequency spectrum, the frequency hopping pattern including a sequence of radio frequency channels; and

means for communicating with the RAN node in accordance with the frequency hopping partem.

24. The apparatus of claims 23, wherein the reference signal is a Discovery Reference Signal transmitted over an anchor channel of the RAN node.

25. The apparatus of claim 19 or 23, wherein the UE is an Narrowband Internet-of-Things (NB-IoT) device.