Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/04—Wireless resource allocation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/20—Control channels or signalling for resource management
  • H04W72/23—Control channels or signalling for resource management in the downlink direction of a wireless link, i.e. towards a terminal
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/10—Connection setup
  • H04W76/14—Direct-mode setup
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/30—Connection release

Definitions

• the following relates generally to wireless communication, and more specifically to techniques for use in supporting or otherwise managing device-to-device (D2D) communication, and more particularly to techniques for potential use in D2D communication via grant-free uplink (GUL) resources in a shared radio frequency spectrum.
• D2D device-to-device
• GUL grant-free uplink
• Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may support communication with multiple users by sharing the available system resources (e.g., broadcast spectrum with regard to time, frequency, spatial, and/or power related aspects).
• Examples of some multiple-access systems include fourth generation (4G) systems such as a Long Term Evolution (LTE) systems or LTE-Advanced (LTE-A) systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems.
• 4G systems such as a Long Term Evolution (LTE) systems or LTE-Advanced (LTE-A) systems
• 5G systems which may be referred to as New Radio (NR) systems.
• a wireless multiple-access communications system may include several base stations or network access nodes, each supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
• UE user equipment
• 5G communications technology may include: enhanced mobile broadband addressing human-centric use cases for access to multimedia content, services and data; ultra-low latency (ULL) and/or ultra-reliable-low latency communications (URLLC) with certain specifications for latency and reliability; and massive machine type communications, which may allow a very large number of connected devices and transmission of a relatively low volume of non-delay-sensitive information.
• UDL ultra-low latency
• URLLC ultra-reliable-low latency communications
• massive machine type communications which may allow a very large number of connected devices and transmission of a relatively low volume of non-delay-sensitive information.
• 5G NR may provide more flexibility in wireless
• the described techniques relate to improved methods, systems, devices, or apparatuses that may be used in support of D2D communication, possibly using, at least in part, GUL resources in a shared radio frequency spectrum.
• a method may be provided for use at a first UE.
• the method may comprise, at the first UE, receiving an indication that a GUL resource allocation has been or will be provided for D2D communication between the first UE and a second UE.
• the indication may be transmitted, for example, by a base station.
• the method may further comprise, at the first UE, supporting the D2D communication, at least in part, by transmitting a first signal intended for the second UE via at least a first portion of the GUL resource allocation, and receiving a second signal from the second UE via at least a second portion of the GUL resource allocation.
• a first UE may be provided which includes a receiver, a transmitter and a processing unit.
• the processing unit may be coupled to the receiver and the transmitter and configured to obtain an indication that a GUL resource allocation has been or will be provided for D2D communication between the first UE and a second UE.
• the indication may be transmitted, for example, by a base station and received by the first EE via the receiver.
• the processing unit may be further configured to support of the D2D communication, for example, by initiating transmission, via the transmitter, of a first signal intended for the second EE via at least a first portion of the GEE resource allocation, and obtaining, via the receiver, a second signal from the second EE via at least a second portion of the GEE resource allocation.
• a method may be provided for use at base station.
• the method may comprise, at the base station determining that a GEE resource allocation is to be provided for D2D communication between a first EE and a second EE, and transmitting at least one indication to the first EE, the second EE, or both, wherein the at least one indication identifies at least a portion of the GEE resource allocation for use by the first EE, the second EE, or both in supporting the D2D communication therebetween.
• a base station may be provided which includes a receiver, a transmitter and a processing unit.
• the processing unit may be coupled to the receiver and the transmitter and configured to determine that a GEE resource allocation is to be provided for D2D communication between a first EE and a second EE, and initiate transmission, via the transmitter, of at least one indication to the first EE, the second EE, or both, wherein the at least one indication identifies at least a portion of the GEE resource allocation for use by the first EE, the second EE, or both in supporting the D2D communication therebetween.
• FIG. 1 illustrates an example of a system for wireless communication that may support D2D channel measurements and/or D2D communication, in accordance with certain aspects of the present disclosure.
• FIGs. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a downlink DL frame structure, DL channels within the DL frame structure, an uplink EE frame structure, and EE channels within the EE frame structure that may be measurable or otherwise of potential use in support of D2D channel measurements and/or D2D communication, for example as in the system illustrated in FIG. 1, in accordance with certain aspects of the present disclosure.
• FIG. 3 is a diagram illustrating an example of a base station and a user equipment (UE) that may support D2D channel measurements and/or D2D
• UE user equipment
• FIG. 4 is a flow diagram illustrating an example method for use by a base station to support D2D communication between two UEs, in accordance with certain aspects of the present disclosure.
• FIG. 5 is a flow diagram illustrating an example method for use by a UE to support D2D communication with another UE, in accordance with certain aspects of the present disclosure.
• FIG. 6 is a diagram illustrating some example components that may be included within a base station, in accordance with certain aspects of the present disclosure.
• FIG. 7 is a diagram illustrating some example components that may be included within a UE, in accordance with certain aspects of the present disclosure.
• FIG. 8 is a call flow diagram illustrating some example message exchanges that may be used, at least in part, to implement D2D communication techniques in accordance with certain aspects of the present disclosure
• wireless devices may generally communicate with each other via one or more network entities such as a base station or scheduling entity.
• Some networks may additionally or alternatively support D2D communication that enables discovery of, and communication with nearby devices using a direct link between devices (e.g., without necessarily passing messages through a base station, relay, or other node).
• D2D communication may, for example, enable mesh networks and device-to-network relay functionality.
• Some examples of D2D technology include Bluetooth pairing, Wi-Fi Direct, Miracast, and LTE-D.
• D2D communication may also be called point-to-point (P2P) or sidelink communication.
• P2P point-to-point
• D2D communication may be implemented using licensed or unlicensed bands.
• MuLTEfire is a form of Long-term Evolution (LTE) network that may support D2D communication using unlicensed frequency bands. MuLTEfire may be used in any unlicensed spectrum where there is contention for use of the spectrum, although deployments are initially expected in the 5 GHz unlicensed band and potentially also in the 3.5 GHz shared band in the ETnited States of America. MuLTEfire implements a listen-before-talk (LBT) strategy for coexistence management.
• LBT listen-before-talk
• the UE may perform a first LBT process (e.g., 25 ps) if within the base station TxOP.
• a UE may perform a second LBT process (e.g.,
• a UE may be configured to start an LBT process at different starting positions/times to reduce collisions between one or more other UEs.
• aspects of the present disclosure provide methods and apparatuses for supporting (e.g., initiating, managing, monitoring, ending, etc.) D2D communication, and in particular examples, making use, at least in part, of grant-free uplink (GUL) resources in a shared radio frequency spectrum.
• GUL grant-free uplink
• base stations may coordinate with each other in allocating GUL resources for a D2D connection or channel between UEs across the cells.
• a base station may provide GUL resource allocation (e.g., indications of activation/release, etc.) messages to a UE.
• GUL resource allocation messages may be transmitted in a semi-persistent scheduling manner.
• a UE may, by way of example, monitor such messages as part of the downlink control information (DCI).
• DCI downlink control information
• GUL transmissions may be implemented in addition to grant-based uplink transmission (e.g., DCI).
• a network entity e.g., a base station
• UEs e.g., for D2D communication.
• a first UE may utilize a GUL resource allocation for D2D communication with a second UE in a shared radio frequency spectrum.
• D2D communication in a shared radio frequency spectrum may be implemented in a more centralized control mode that may include more monitoring/assistance of the base station than might otherwise be the situation in a distributed control mode wherein UEs may be configured to have more control over D2D communication.
• a shared radio frequency spectrum is used for at least a portion of communications in a wireless communication system.
• the shared radio frequency spectrum may be used for Long Term Evolution (LTE) or LTE-Advanced (LTE-A) communications, Licensed Assisted Access (LAA) communications, enhanced LAA (eLAA) communications, or MuLTEfire
• LTE Long Term Evolution
• LTE-A LTE-Advanced
• LAA Licensed Assisted Access
• eLAA enhanced LAA
• the shared radio frequency spectrum may be used in combination with, or independent from, a dedicated radio frequency spectrum.
• the dedicated radio frequency spectrum may include a radio frequency spectrum licensed to particular users/devices for particular purposes.
• the shared radio frequency spectrum may include a radio frequency spectrum available for Wi-Fi use, a radio frequency spectrum available for use by different radio access technologies, a radio frequency spectrum available for use by multiple mobile network operators (MNOs) in an equally shared or prioritized manner, or the like.
• MNOs mobile network operators
• a base station may be configured to determine that a GUL resource allocation is to be provided for use in D2D communication between a first UE and a second UE.
• a GUL resource allocation may be provided as part of a MuLTEfire framework and/or the like.
• a base station having made such a determination, may transmit one or more indications to the first UE, and the second UE that identify all or applicable portions of the GUL resource allocation for use by the first UE, the second UE, or both in supporting the D2D communication therebetween.
• a base station may identify that a first UE and a second UE are D2D communication candidates based, at least in part, on one or more messages received from the first UE and/or the second UE indicating, e.g., estimated locations, ranges, etc.
• a base station may receive one or more requests for a D2D communication from the first UE, the second UE or both, and determine that a D2D communication may be provided based, at least in part, on one or more such requests.
• a base station may identify that such a D2D communication may be provided based on other received information. For example, a base station may monitor/measure channel conditions, consider resource allocations, etc., that may, at least in part, inform a D2D communication determination.
• a base station may monitor a D2D communication in some manner.
• a base station may monitor a D2D communication by receiving a first signal via at least a first portion of the GUL resource allocation and/or a second signal via at least a second portion of the GUL resource allocation, wherein the first signal is transmitted from the first UE to the second UE and the second signal is transmitted by the second UE to the first UE as part of the D2D communication.
• a first portion of such GUL resource allocation and a second portion of such GUL resource allocation may comprise the same GUL resource allocation, or different GUL resource allocations.
• a first or second portion of the GUL resource allocation may comprise at least a portion of a previous GUL resource allocation provided for the first or second UE (respectively), e.g., to transmit certain (possibly non-D2D communication) signals intended primarily for the base station.
• a base station may monitor a D2D communication by monitoring traffic signals, ACK/NACK (HARQ, etc.),“keep-alive” signals, etc., transmitted using the GUL resource allocation of the D2D communication.
• a base station may, for example, be configured to end a D2D
• a base station may decide to end a D2D communication based, at least in part, on one or more D2D channel measurement threshold parameters, one or more UE Sounding Reference Signal (SRS) threshold parameters, one or more D2D communication time-out threshold parameters, one or more D2D communication termination requests, a base station handover determination, a GUL resource reallocation determination, or some combination thereof or the like.
• SRS Sounding Reference Signal
• a first UE and a second UE may together or independently receive one or more indications that a GUL resource allocation has been or will be provided for D2D communication between the first UE and the second UE.
• the first UE may support the D2D communication by transmitting a first signal intended for the second UE via at least a first portion of the GUL resource allocation, and receiving a second signal from the second UE via at least a second portion of the GUL resource allocation.
• the second UE may support the D2D communication by transmitting the second signal intended for the first UE via at least the second portion of the GUL resource allocation, and receiving the first signal from the first UE via at least the first portion of the GUL resource allocation.
• the first UE, the second UE or both may be configured to transmit request(s) for a D2D communication to the base station.
• a first UE may be configured to determine a D2D channel measurement of a SRS transmission by the second UE, and determine whether to transmit a request to the base station based, at least in part, on the D2D channel measurement.
• the first UE, the second UE or both may be configured to transmit traffic, SRS,“keep- alive” signals, or the like, e.g., that may be of use by the base station in monitoring and maintaining of the D2D communication.
• D2D communications may allow one of the UEs to communicate directly with the another one of the UEs, which may increase throughput, reduce latency, extend range (coverage area), promote energy efficiency, or some combination thereof, just to name a few non-limiting examples.
• D2D communications may be of potential benefit to various social applications, e.g., gaming, media sharing, location-based services, and/or the like.
• such D2D communications may be of potential benefit with regard to wearable or other like devices that may be co-located, e.g., smart phones, smart watches, smart glasses, ear pieces, head sets, etc., particularly for data intensive communications, such as, media streaming, augmented reality, virtual reality, etc.
• such D2D communications may be of potential benefit to Internet-of-Things (IoT) devices or the like, some or all of which may benefit by saving battery or other like stored/available electrical power.
• IoT Internet-of-Things
• some UEs may comprise smart phones, tablets, laptops, positioning/tracking devices, wearable devices, display/glasses devices, vehicles, machines, appliances robots, drones, Internet-of-Things (IoT) devices, circuitry (e.g., controllers, sensors, actuators, data storage, etc.), and/or the like or some combination thereof.
• IoT Internet-of-Things
• circuitry e.g., controllers, sensors, actuators, data storage, etc.
• the techniques provided herein may be implemented to support D2D communications between more than two UEs.
• the present description includes some example D2D communication techniques illustrated as possibly being implemented with regard to an example framework (e.g., MuLTEfire 1.1) or other like configured devices/networks.
• Wireless communications system 100 may include, for example, base stations 105, UEs 115, and a core network 130.
• wireless communications system 100 may comprise a Long-Term Evolution (LTE) network, an LTE- Advanced (LTE- A) network, or a New Radio (NR) network.
• LTE Long-Term Evolution
• LTE- A LTE- Advanced
• NR New Radio
• wireless communications system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, communications with low-cost and low-complexity devices, etc.
• ultra-reliable e.g., mission critical
• wireless communication network 100 may comprise one or any combination of communication technologies, including a new radio (NR) or 5G technology, LTE, LTE-A, MuLTEfire technology, a Wi-Fi technology, a Bluetooth technology, or any other long or short range wireless communication
• Wireless communication network 100 may be a heterogeneous technology network in which different types of eNBs provide coverage for various geographical regions.
• an eNB or base station 105 may provide communication coverage for a macro cell, a small cell, or other types of cell.
• the term“cell” is a 3GPP term that may be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.
• Base stations 105 may wirelessly communicate with EIEs 115 via one or more base station antennas.
• Base stations 105 described herein may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next-generation Node B or giga-nodeB (either of which may be referred to as a gNB), a Home NodeB, a Home eNodeB, or some other suitable terminology.
• Wireless communications system 100 may include base stations 105 of different types (e.g., macro or small cell base stations).
• the UEs 115 described herein may be able to communicate with various types of base stations 105 and network equipment including macro eNBs, small cell eNBs, gNBs, relay base stations, and the like.
• a base station 105 may be associated with a geographic coverage area 110 in which communications with various UEs 115 is supported.
• a base station 105 may provide communication coverage for a respective geographic coverage area 110 via communication links 125, and communication links 125 between a base station 105 and a UE 115 may utilize one or more carriers.
• Communication links 125 shown in wireless communications system 100 may include uplink transmissions from a UE 115 to a base station 105, or downlink transmissions, from a base station 105 to a UE 115. Downlink transmissions may also be called forward link transmissions while uplink transmissions may also be called reverse link transmissions.
• a geographic coverage area 110 for a base station 105 may be divided into sectors making up only a portion of the geographic coverage area 110, and each sector may be associated with a cell.
• each base station 105 may provide communication coverage for a macro cell, a small cell, a hot spot, or other types of cells, or various combinations thereof.
• a base station 105 may be movable and therefore provide communication coverage for a moving geographic coverage area 110.
• different geographic coverage areas 110 associated with different technologies may overlap, and overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station or by different base stations.
• the wireless communications system 100 may include, for example, a heterogeneous LTE/LTE-A or NR network in which different types of base stations provide coverage for various geographic coverage areas 110.
• cell refers to a logical communication entity used for
• a base station 105 may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID)) operating via the same or a different carrier.
• a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., machine-type communication (MTC), narrowband Internet-of-Things (NB-IoT), enhanced mobile broadband (eMBB), or others) that may provide access for different types of devices.
• MTC machine-type communication
• NB-IoT narrowband Internet-of-Things
• eMBB enhanced mobile broadband
• the term “cell” may refer to a portion of a geographic coverage area 110 (e.g., a sector) over which the logical entity operates.
• UEs 115 may be dispersed throughout the wireless communications system 100, and such UEs may, at times, be stationary or mobile.
• a UE 115 may also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the“device” may also be referred to as a unit, a station, a terminal, or a client.
• a UE 115 may also be a personal electronic device such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer.
• PDA personal digital assistant
• a UE 115 may also refer to a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or an MTC device, or the like, which may be implemented in various articles such as appliances, vehicles, meters, or the like.
• WLL wireless local loop
• IoT Internet of Things
• IoE Internet of Everything
• MTC massive machine type communications
• Some UEs 115 may be low cost or low complexity devices, and may provide for automated communication between machines (e.g., via Machine-to-Machine (M2M) communication).
• M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention.
• M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application program that may make use of the information or present the information to humans interacting with the program or application.
• Some UEs 115 may be designed to collect information or enable automated behavior of machines. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.
• Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communications (e.g., a mode that supports one-way communication via transmission or reception, but not transmission and reception simultaneously). In some examples half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for UEs 115 include entering a power saving“deep sleep” mode when not engaging in active communications, or operating over a limited bandwidth (e.g., according to narrowband communications). In some cases, a UE 115 may be designed to support critical functions (e.g., mission critical functions), and a wireless communications system 100 may be configured to provide ultra-reliable communications for these functions.
• critical functions e.g., mission critical functions
• a UE 115 may also be able to communicate directly with other UEs 115 (e.g., using a peer-to-peer (P2P), a device-to-device (D2D) protocol, or the like).
• P2P peer-to-peer
• D2D device-to-device
• One or more of a group of UEs 115 utilizing D2D communications may be within the geographic coverage area 110 of a base station 105.
• Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105, or be otherwise unable to receive transmissions from a base station 105.
• groups of UEs 115 communicating via D2D communications may utilize a one-to-many (1 :M) system in which each UE 115 transmits to every other UE 115 in the group.
• a base station 105 may facilitate the scheduling/allocation of resources for D2D communications.
• some D2D communications may be carried out between UEs 115 without the involvement of a base station 105.
• Base stations 105 may communicate with the core network 130 and with one another.
• base stations 105 may interface with the core network 130 through backhaul links 132 (e.g., via an Sl or other interface).
• Base stations 105 may communicate with one another over backhaul links 134 (e.g., via an X2 or other interface) either directly (e.g., directly between base stations 105) or indirectly (e.g., via core network 130).
• a core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions.
• the core network 130 may be an evolved packet core (EPC), which may include at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one Packet Data Network (PDN) gateway (P-GW).
• EPC evolved packet core
• MME mobility management entity
• S-GW serving gateway
• PDN gateway Packet Data Network gateway
• P-GW Packet Data Network gateway
• the MME may manage non-access stratum (e.g., control plane) functions such as mobility,
• the P-GW may provide IP address allocation as well as other functions.
• the P-GW may be connected to the network operators IP services.
• the operators IP services may include access to the Internet, Intranet(s), an IP Multimedia Subsystem (IMS), or a Packet- Switched (PS) Streaming Service.
• IMS IP Multimedia Subsystem
• PS Packet- Switched
• Some of the network devices, such as a base station 105 may include subcomponents such as an access network entity, which may be an example of an access node controller (ANC).
• ANC access node controller
• An access network entity may communicate with UEs 115 through a number of other access network transmission entities, which may be referred to as a radio head, a smart radio head, or a transmission/reception point (TRP).
• TRP transmission/reception point
• various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., a base station 105).
• Wireless communications system 100 may operate using one or more frequency bands, typically in the range of 300 MHz to 300 GHz.
• the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band, since the wavelengths range from approximately one decimeter to one meter in length.
• UHF waves may be blocked or redirected by buildings and
• the waves may penetrate structures sufficiently for a macro cell to provide service to UEs 115 located indoors.
• Transmission of UHF waves may be associated with smaller antennas and shorter range (e.g., less than 100 km) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.
• HF high frequency
• VHF very high frequency
• Wireless communications system 100 may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band.
• SHF region includes bands such as the 5 GHz industrial, scientific, and medical (ISM) bands, which may be used opportunistically by devices that may tolerate interference from other users.
• ISM bands 5 GHz industrial, scientific, and medical bands
• Wireless communications system 100 may also operate in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz), also known as the millimeter band.
• EHF extremely high frequency
• wireless communications system 100 may support millimeter wave (mmW) communications between UEs 115 and base stations 105, and EHF antennas of the respective devices may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate use of antenna arrays within a UE 115 (e.g., for multiple-input multiple-output (MIMO) operations such as spatial multiplexing, or for directional beamforming).
• MIMO multiple-input multiple-output
• the propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. Techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.
• wireless communications system 100 may utilize both licensed and unlicensed/shared radio frequency spectrum bands.
• wireless communications system 100 may employ LTE License Assisted Access (LTE-LAA) or LTE-Unlicensed (LTE-U) radio access technology or MuLTEfire radio access technology or NR technology in an unlicensed/shared radio frequency band such as the 5 GHz ISM band.
• LTE-LAA LTE License Assisted Access
• LTE-U LTE-Unlicensed
• MuLTEfire radio access technology or NR technology in an unlicensed/shared radio frequency band such as the 5 GHz ISM band.
• wireless devices such as base stations 105 and EIEs 115 may employ listen- before-talk (LBT) procedures to ensure a frequency channel is clear before transmitting data.
• LBT listen- before-talk
• operations in unlicensed/shared radio frequency bands may be based on a CA configuration in conjunction with CCs operating in a licensed band.
• Operations in unlicensed/shared radio frequency spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these.
• Duplexing in unlicensed/shared radio frequency spectrum may be based on frequency division duplexing (FDD), time division duplexing (TDD), or a combination of both.
• FDD frequency division duplexing
• TDD time division duplexing
• the antennas of a base station 105 or EGE 115 may be located within one or more antennas or antenna arrays, which may support MIMO operations such as spatial multiplexing, or transmit or receive beamforming.
• one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower.
• antennas or antenna arrays associated with a base station 105 may be located in diverse geographic locations.
• a base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with a LIE 115.
• a LIE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.
• MIMO wireless systems use a transmission scheme between a transmitting device (e.g., a base station 105) and a receiving device (e.g., a LIE 115), where both transmitting device and the receiving device are equipped with multiple antennas.
• a transmitting device e.g., a base station 105
• a receiving device e.g., a LIE 115
• MIMO communications may employ multipath signal propagation to increase the utilization of a radio frequency spectrum band by transmitting or receiving different signals via different spatial paths, which may be referred to as spatial multiplexing.
• the different signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas.
• the different signals may be received by the receiving device via different antennas or different combinations of antennas.
• Each of the different signals may be referred to as a separate spatial stream, and the different antennas or different combinations of antennas at a given device (e.g., the orthogonal resource of the device associated with the spatial dimension) may be referred to as spatial layers.
• Beamforming which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station 105 or a UE 115) to shape or steer an antenna beam (e.g., a transmit beam or receive beam) along a direction between the transmitting device and the receiving device.
• Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that signals propagating at particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference.
• the adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying certain phase offset, timing advance/delay, or amplitude adjustment to signals carried via each of the antenna elements associated with the device.
• the adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation).
• a base station 105 may multiple use antennas or antenna arrays to conduct beamforming operations for directional communications with a LIE 115. For instance, signals may be transmitted multiple times in different directions, which may include a signal being transmitted according to different beamforming weight sets associated with different directions of transmission.
• a receiving device e.g., a UE 115, which may be an example of a mmW receiving device
• a receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive beams or receive directions.
• wireless communications system 100 may be a packet-based network that operate according to a layered protocol stack.
• PDCP Packet Data Convergence Protocol
• a Radio Link Control (RLC) layer may in some cases perform packet segmentation and reassembly to communicate over logical channels.
• RLC Radio Link Control
• a Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels.
• the MAC layer may also use hybrid automatic repeat request (HARQ) to provide retransmission at the MAC layer to improve link efficiency.
• HARQ hybrid automatic repeat request
• the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a base station 105 or core network 130 supporting radio bearers for user plane data.
• RRC Radio Resource Control
• PHY Physical
• UEs 115 and base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully.
• HARQ feedback is one technique of increasing the likelihood that data is received correctly over a communication link 125.
• HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)).
• FEC forward error correction
• ARQ automatic repeat request
• HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., signal-to-noise conditions).
• a wireless device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot. In other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.
• the radio frames may be identified by a system frame number (SFN) ranging from 0 to 1023.
• SFN system frame number
• Each frame may include ten subframes numbered from 0 to 9, and each subframe may have a duration of 1 millisecond.
• a subframe may be further divided into two slots each having a duration of 0.5 milliseconds, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period). Excluding the cyclic prefix, each symbol period may contain 2048 sampling periods.
• a subframe may be the smallest scheduling unit of the wireless communications system 100, and may be referred to as a transmission time interval (TTI).
• TTI transmission time interval
• a smallest scheduling unit of the wireless communications system 100 may be shorter than a subframe or may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs) or in selected component carriers using sTTIs).
• a slot may further be divided into multiple mini-slots containing one or more symbols and, in some instances, a symbol of a mini-slot or a mini-slot may be the smallest unit of scheduling. Each symbol may vary in duration depending on the subcarrier spacing or frequency band of operation, for example.
• Some wireless communications systems may implement slot aggregation in which multiple slots or mini-slots may be aggregated together for communication between a EGE 115 and a base station 105.
• a resource element may consist of one symbol period (e.g., a duration of one modulation symbol) and one subcarrier (e.g., a 15 kHz frequency range).
• a resource block may contain 12 consecutive subcarriers in the frequency domain (e.g., collectively forming a“carrier”) and, for a normal cyclic prefix in each orthogonal frequency- division multiplexing (OFDM) symbol, 7 consecutive OFDM symbol periods in the time domain (1 slot), or 84 total resource elements across the frequency and time domains.
• the number of bits carried by each resource element may depend on the modulation scheme (the configuration of modulation symbols that may be applied during each symbol period).
• the more resource elements that a TIE 115 receives and the higher the modulation scheme e.g., the higher the number of bits that may be represented by a modulation symbol according to a given modulation scheme
• the higher the data rate may be for the TIE 115.
• communications resource may refer to a combination of a radio frequency spectrum band resource, a time resource, and a spatial resource (e.g., spatial layers), and the use of multiple spatial layers may further increase the data rate for communications with a UE 115.
• a spatial resource e.g., spatial layers
• carrier refers to a set of radio frequency spectrum resources having a defined organizational structure for supporting uplink or downlink
• communication link 125 may include a portion of a radio frequency spectrum band that may also be referred to as a frequency channel.
• a carrier may be made up of multiple sub-carriers (e.g., waveform signals of multiple different frequencies).
• a carrier may be organized to include multiple physical channels, where each physical channel may carry user data, control information, or other signaling.
• the organizational structure of the carriers may be different for different radio access technologies (e.g., LTE, LTE-A, NR, etc.). For example, communications over a carrier may be organized according to TTIs or slots, each of which may include user data as well as control information or signaling to support decoding the user data.
• LTE Long Term Evolution
• LTE-A Long Term Evolution Advanced
• NR New Radio
• a carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc.) and control signaling that coordinates operation for the carrier.
• acquisition signaling e.g., synchronization signals or system information, etc.
• control signaling that coordinates operation for the carrier.
• a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers.
• Physical channels may be multiplexed on a carrier according to various techniques.
• a physical control channel and a physical data channel may be multiplexed on a downlink carrier, for example, using time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques.
• TDM time division multiplexing
• FDM frequency division multiplexing
• control information transmitted in a physical control channel may be distributed between different control regions in a cascaded manner (e.g., between a common control region or common search space and one or more EIE-specific control regions or EGE-specific search spaces).
• a carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system 100.
• the carrier bandwidth may be one of a number of predetermined bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, or 20 MHz).
• the system bandwidth may refer to a minimum bandwidth unit for scheduling communications between a base station 105 and a TIE 115.
• a base station 105 or a TIE 115 may also support communications over carriers having a smaller bandwidth than the system bandwidth.
• the system bandwidth may be referred to as“wideband” bandwidth and the smaller bandwidth may be referred to as a“narrowband” bandwidth.
• wideband communications may be performed according to a 20 MHz carrier bandwidth and narrowband communications may be performed according to a 1.4 MHz carrier bandwidth.
• Devices of wireless communications system 100 e.g., base stations or UEs 115 may have a hardware configuration that supports communications over a particular carrier bandwidth, or may be configurable to support communications over one of a set of carrier bandwidths.
• base stations 105 or UEs 115 may perform some communications according to a system bandwidth (e.g., wideband communications), and may perform some communications according to a smaller bandwidth (e.g., narrowband communications).
• the wireless communications system 100 may include base stations 105 and/or UEs that may support simultaneous communications via carriers associated with more than one different bandwidth.
• Wireless communications system 100 may support communication with a UE 115 on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation.
• a UE 115 may be configured with multiple downlink CCs and one or more uplink CCs according to a carrier aggregation configuration.
• Carrier aggregation may be used with both FDD and TDD component carriers.
• wireless communications system 100 may utilize enhanced component carriers (eCCs).
• eCC may be characterized by one or more features including wider carrier or frequency channel bandwidth, shorter symbol duration, shorter TTI duration, or modified control channel configuration.
• an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have a suboptimal or non-ideal backhaul link).
• An eCC may also be configured for use in unlicensed/shared radio frequency spectrum or shared radio frequency spectrum (e.g., where more than one operator is allowed to use the spectrum).
• An eCC characterized by wide carrier bandwidth may include one or more segments that may be utilized by UEs 115 that are not capable of monitoring the whole carrier bandwidth or are otherwise configured to use a limited carrier bandwidth (e.g., to conserve power).
• an eCC may utilize a different symbol duration than other CCs, which may include use of a reduced symbol duration as compared with symbol durations of the other CCs.
• a shorter symbol duration may be associated with increased spacing between adjacent subcarriers.
• a device such as a UE 115 or base station 105, utilizing eCCs may transmit wideband signals (e.g., according to frequency channel or carrier bandwidths of 20, 40, 60, 80 MHz, etc.) at reduced symbol durations (e.g., 16.67 microseconds).
• a TTI in eCC may consist of one or multiple symbol periods. In some cases, the TTI duration (that is, the number of symbol periods in a TTI) may be variable.
• Wireless communications systems such as an NR system may use a combination of licensed, shared, and unlicensed/shared radio frequency spectrum bands, among others.
• the flexibility of eCC symbol duration and subcarrier spacing may allow for the use of eCC across multiple spectrums.
• NR shared spectrum may increase spectrum utilization and spectral efficiency, specifically through dynamic vertical (e.g., across frequency) and horizontal (e.g., across time) sharing of resources.
• a first UE 115-1 may be configured to support D2D communication with a second UE 115-2.
• a D2D communication is represented by communication link 150.
• UE 115-1 may be requested by base station 105-1 over communication link 125-1 to monitor an SRS transmission from UE 115-2 represented by communication link 125-2.
• base station 105-1 may determine that UE 115-1 and UE115-2 may be indicated as being within a threshold communication proximity of one another, e.g., based on serving node activity, location information, etc.
• UE 115-2 may be instructed (e.g., by base station 105-1) to transmit one or more particular SRS that may be monitored by UE 115-1. In a similar manner, UE 115-2 may monitor one or more SRS transmission from UE-l 15-1. In this manner, UEs may make D2D channel measurement s) and transmit corresponding reports to base station 105-1. Base station 105-1, having identified UE 115-1 and UE 115-2 as D2D communication candidates may set-up D2D communication therebetween and monitor the D2D communication, at least in part, using the example techniques provided herein.
• FIG. 2A is a diagram 200 illustrating an example frame structure of one or more downlink (DL) frames in accordance with various aspects of the present disclosure.
• FIG. 2B is a diagram 230 illustrating an example of channels within the frame structure of a DL frame in accordance with various aspects of the present disclosure.
• FIG. 2C is a diagram 250 illustrating an example frame structure of one or more uplink (UL) frames in accordance with various aspects of the present disclosure.
• FIG. 2D is a diagram 280 illustrating an example of channels within the frame structure of a UL frame in accordance with various aspects of the present disclosure.
• Other wireless communication technologies may have a different frame structure and/or different channels.
• a frame (10 ms) may be divided into 10 equally sized subframes.
• Each subframe may include two consecutive time slots.
• a resource grid may be used to represent the two time slots, each time slot including one or more time concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)).
• the resource grid is divided into multiple resource elements (REs).
• REs resource elements
• an RB contains 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs.
• the number of bits carried by each RE depends on the modulation scheme.
• DL-RS DL reference (pilot) signals
• the DL-RS may include cell-specific reference signals (CRS) (e.g., also sometimes called common RS), UE-specific reference signals (EIE-RS), and channel state information reference signals (CSI-RS).
• CRS cell-specific reference signals
• EIE-RS UE-specific reference signals
• CSI-RS channel state information reference signals
• FIG. 2 A illustrates CRS for antenna ports 0, 1, 2, and 3 (indicated as Ro, Ri, R2, and R3, respectively), EIE-RS for antenna port 5 (indicated as Rs), and CSI-RS for antenna port 15 (indicated as R).
• FIG. 2B illustrates an example of various channels within a DL subframe of a frame.
• the physical control format indicator channel (PCFICH) is within symbol 0 of slot 0, and carries a control format indicator (CFI) that indicates whether the physical downlink control channel (PDCCH) occupies 1, 2, or 3 symbols (FIG. 2B illustrates a PDCCH that occupies 3 symbols).
• the PDCCH carries downlink control information (DCI) within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol.
• DCI downlink control information
• CCEs control channel elements
• REGs RE groups
• a UE may be configured with a UE-specific enhanced PDCCH (ePDCCH) that also carries DCI.
• ePDCCH UE-specific enhanced PDCCH
• the ePDCCH may have 2, 4, or 8 RB pairs (FIG. 2B shows two RB pairs, each subset including one RB pair).
• the physical hybrid automatic repeat request (ARQ) (HARQ) indicator channel (PHICH) is also within symbol 0 of slot 0 and carries the HARQ indicator (HI) that indicates HARQ acknowledgement (ACK) / negative ACK (NACK) feedback based on the physical uplink shared channel (PUSCH).
• the primary synchronization channel (PSCH) may be within symbol 6 of slot 0 within subframes 0 and 5 of a frame.
• the PSCH carries a primary synchronization signal (PSS) that is used by a UE to determine subframe/symbol timing and a physical layer identity.
• the secondary synchronization channel (SSCH) may be within symbol 5 of slot 0 within subframes 0 and 5 of a frame.
• the SSCH carries a secondary
• the UE may determine a physical cell identifier (PCI). Based on the PCI, the UE may determine the locations of the aforementioned DL-RS.
• the physical broadcast channel (PBCH) which carries a master information block (MIB), may be logically grouped with the PSCH and SSCH to form a synchronization signal (SS) block.
• MIB master information block
• the MIB provides a number of RBs in the DL system bandwidth, a PHICH configuration, and a system frame number (SFN).
• the physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and paging messages.
• SIBs system information blocks
• some of the REs carry demodulation reference signals (DM-RS) for channel estimation at the base station.
• the UE may additionally transmit sounding reference signals (SRS) in the last symbol of a subframe.
• SRS transmissions may be measured by receiving UEs to determine D2D channel measurements.
• a SRS may have a comb structure, and a UE may transmit SRS on one of the combs.
• a SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.
• FIG. 2D illustrates an example of various channels within an UL subframe of a frame.
• a physical random-access channel PRACH
• the PRACH may be within one or more subframes within a frame based on the PRACH configuration.
• the PRACH may include six consecutive RB pairs within a subframe.
• the PRACH allows the UE to perform initial system access and achieve UL synchronization.
• a physical uplink control channel PUCCH
• the PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback.
• the PUSCH carries data, and may
• BSR buffer status report
• PHR power headroom report
• UCI UCI
• FIG. 3 is a block diagram of a base station 310 in communication with a UE 350 in an access network.
• IP packets from the EPC 160 may be provided to a controller/processor 375.
• the controller/processor 375 implements layer 3 and layer 2 functionality.
• Layer 3 includes a radio resource control (RRC) layer
• layer 2 includes a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer.
• RRC radio resource control
• PDCP packet data convergence protocol
• RLC radio link control
• MAC medium access control
• the controller/processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re- segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HAR
• the transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions.
• Layer 1 which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels,
• FEC forward error correction
• the TX processor 316 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying
• BPSK binary phase-shift keying
• QPSK QPSK
• M-PSK M-phase-shift keying
• M- QAM M-quadrature amplitude modulation
• Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream.
• the OFDM stream is spatially precoded to produce multiple spatial streams.
• Channel estimates from a channel estimator 374 may be used to determine the coding and modulation scheme, as well as for spatial processing.
• the channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 350.
• Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX.
• Each transmitter 318TX may modulate an RF carrier with a respective spatial stream for transmission.
• the controller/processor and/or other example components in base station 310 may represent one or more processing units that may be configured to support/implement certain D2D channel measurement and communication techniques as provided herein.
• each receiver 354RX receives a signal through its respective antenna 352.
• Each receiver 354RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 356.
• the TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions.
• the RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the EE 350. If multiple spatial streams are destined for the EE 350, they may be combined by the RX processor 356 into a single OFDM symbol stream.
• the RX processor 356 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT).
• FFT Fast Fourier Transform
• the frequency domain signal may include a separate OFDM symbol stream for each subcarrier of the OFDM signal.
• the symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on channel estimates computed by the channel estimator 358.
• the soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 310 on the physical channel.
• the data and control signals are then provided to the controller/processor 359, which implements layer 3 and layer 2 functionality.
• the controller/processor 359 may be associated with a memory 360 that stores program codes and data.
• the memory 360 may be referred to as a computer- readable medium.
• the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160.
• the controller/processor 359 may also be responsible for error detection using an ACK and/or NACK protocol to support FLARQ operations.
• the controller/processor and/or other example components in EE 350 may represent one or more processing units that may be configured to support/implement certain D2D channel measurement and communication techniques as provided herein.
• the controller/processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression / decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.
• RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting
• PDCP layer functionality associated with header compression
• Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing.
• the spatial streams generated by the TX processor 368 may be provided to different antenna 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.
• the UL transmission is processed at the base station 310 in a manner similar to that described in connection with the receiver function at the UE 350.
• Each receiver 318RX receives a signal through its respective antenna 320.
• Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.
• the controller/processor 375 may be associated with a memory 376 that stores program codes and data.
• the memory 376 may be referred to as a computer- readable medium.
• the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE 350. IP packets from the controller/processor 375 may be provided to the EPC 160.
• the controller/processor 375 may also be responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.
• FIG. 4 is a flow diagram illustrating an example method 400 for use at a base station, in accordance with certain aspects of the present disclosure.
• Blocks shown in dashed lines are intended to be optional in certain implementations.
• blocks 402, 403, 408, and 410 in example method 400 may be individually optional, while blocks 404 and 406 may represent a complete example method 400 in certain implementations.
• a base station may determine whether a first UE and a second UE are D2D communication candidates. For example, such a determination by the base station may consider, at least in part, one or more D2D channel measurements that may be provided in one or more reports from one or more EIEs.
• a D2D channel measurement may comprise a received signal strength measurement, or some other like signal parameter that may be useful in determining if a D2D communication may be possible between the first EE and the second EE.
• a base station may also determine that a first EE and a second EE may be indicated as being within a threshold communication proximity of one another.
• a location e.g., coordinates, ranges, or the like
• a comparison of such may indicate that the two EIEs may be within a threshold communication proximity of one another.
• one or both EIEs may indicate to the base station that the other EIE may be within a threshold communication proximity.
• a EIE may be configured to make D2D channel measurements based on SRS or other like
• a base station may receive a request for D2D communication from the first EIE, the second EIE, or both. Such a request(s) may inform, at least in part, a determination made by the base station as at block 402, or may otherwise be indicative that the first EIE and second EIE are already deemed to be D2D communication candidates. With such a decision made, a possible result as illustrated in FIG. 4 of either example (optional) blocks 402 and/or 403 may be that method 400 proceeds at block 404.
• a base station may determine that a GEIL resource allocation is to be provided for D2D communication between a first EIE and a second EIE.
• a first GEIL resource allocation may be provided to the first EIE and a second GEIL resource allocation may be provided to the second EE.
• a GEL resource allocation may comprise, at least in part, one or more previously arranged GEL resource allocations for a given EE, while in other instances such a GEL resource allocation may be new/different.
• a GUL resource allocation determination at block 404 may consider, at least in part, various network condition(s), D2D channel measurement(s), report(s) from UE(s), D2D communication request(s) from UE(s), a type of a UE, a service or other like capability associated with an UE or user thereof, a time of day or date, potential wireless interference considerations, a quality of service associated with the D2D
• the base station may transmit at least one indication to the first UE, the second UE or both, that identifies at least a portion of a GUL resource allocation for use in supporting the D2D communication between the first UE and the second UE, e.g., as determined at block 404.
• An indication to a UE at block 406 may indicate, at least in part, one or more wireless signaling parameters for use in supporting at least a portion of a D2D communication.
• an indication may inform a first UE that it is to support a D2D communication with the second UE by transmitting D2D signals over first GUL resources and receiving D2D signals from the second UE over second GUL resources.
• an indication may inform a second UE that it is to support a D2D communication with the first UE by transmitting D2D signals over second GUL resources and receiving D2D signals from the first UE over first GUL resources.
• an indication in accordance with example block 406 may comprise or otherwise correspond to a time-related parameter, a frequency-related parameter, a spatial-related parameter, a resource block related parameter, a carrier-related parameter, a transmitter-related parameter, a transmit power-related parameter, and/or the like or some combination thereof, just to name a few examples.
• a D2D communication between the first UE and the second UE will be set-up and may proceed accordingly.
• the base station may monitor D2D communication (e.g., as set-up via block 406) between a first UE and a second UE.
• a base station may actively monitor some or all of the signals transmitted via the D2D communication between the first UE, the second UE or both.
• a base station may monitor D2D communication signals to determine whether the GUL resource allocation(s) are adequate, being efficiently used, etc.
• a base station may monitor D2D communication traffic and/or“keep alive” signals, at least in part, to determine if the D2D communication should continue, or be altered in some manner.
• a base station may monitor the D2D communication, at least in part, by receiving one or more UE-to-base station reports/requests corresponding to an on-going (possibly problematic) D2D communication, signaling environment (e.g., link quality, D2D channel measurement, etc.), a change in UE/communi cation needs, etc.
• signaling environment e.g., link quality, D2D channel measurement, etc.
• a base station may determine that a D2D communication as set-up at block 406 is to end.
• a base station may end a D2D communication by altering one or more GEIL resource allocations as determined a block 404 and informing the affected EE(s).
• a base station may provide indirect communication between the EEs that were involved in the D2D communication.
• a D2D communication may be set to end at block 410 based on one or more events.
• a need to change GEE resource allocation(s), a loss of D2D signaling, a passage of a period of time, a lack of keep-alive signals, etc. may represent events that may trigger, at least in part, the end of a D2D communication in accordance with block 410.
• example method 400 may proceed to block 410 from block 406 or possible block 408.
• method 400 may permit a base station to handover one or both EEs to another base station.
• a handover may comprise ending the D2D communication as set-up at block 406.
• a handover may be configured to maintain all or part of an on-going or scheduled D2D communication, e.g., wherein monitoring of the D2D communication may also be transferred to the target base station in some manner, e.g., as part of a handover, etc.
• indirect communication between the EEs involved in the D2D communication may be re-routed via a first base station and a second base station.
• Some example signals that may support all or part of method 400 and method 500 are also further described and illustrated in an example call-flow 800 in FIG. 8.
• FIG. 5 is a flow diagram illustrating an example method 500 for use by a EE, in accordance with certain aspects of the present disclosure.
• Blocks shown in dashed lines are intended to be optional in certain implementations.
• blocks 502, 512 and 514 in example method 500 may be individually optional, while blocks 504 and 506 (including blocks 508 and 510) may represent a complete example method 500 in certain implementations.
• a (first) UE may transmit to a base station, a request for a D2D communication, a report corresponding to D2D channel measurement, and/or the like which may be considered, at least in part, by the base station in possibly setting up a D2D communication between the first UE and another (second) UE.
• a request, report, etc. may be transmitted, for example, via an existing/previous GUL resource allocation in certain instances.
• the first UE may receive an indication that a GUL resource allocation has been or will be provided for use in D2D communication between the first UE and a second UE.
• a base station may transmit at least one indication to the first UE, the second UE or both, that identifies at least a portion of a GUL resource allocation for use in supporting the D2D communication between the first UE and the second UE.
• an indication to the first UE at block 504 may indicate, at least in part, various wireless signaling parameters for use in providing at least a portion of the D2D communication.
• an indication may inform the first UE that it is to support a D2D communication with the second UE by transmitting D2D signals over first GUL resources and receiving D2D signals from the second UE over second GUL resources.
• an indication in accordance with example block 504 may comprise or otherwise correspond to a time-related parameter, a frequency- related parameter, a spatial-related parameter, a resource block related parameter, a carrier-related parameter, a transmitter-related parameter, a transmit power-related parameter, and/or the like or some combination thereof, just to name a few examples.
• the first UE may be configured to support the D2D communication as indicated at block 504.
• the first UE may transmit at least a first signal intended for the second UE via at least a first portion of the GUL resource allocation as may be indicated at block 504.
• the first UE may receive at least a second signal intended for the first UE via at least a second portion of the GUL resource allocation as may be indicated at block 504.
• the first UE may support the D2D communication, at least in part, by transmitted a first SRS that may be used by the base station, the second UE, or both for possible channel measurements that may indicate whether the D2D communication or other wireless communication with the first UE should be continued, altered in some manner, or possibly ended.
• a first SRS may be transmitted via previously allocated GUL resources and/or via at least a portion of the GUL resource allocation associated with the D2D communication.
• one or more keep-alive signals may be transmitted via the D2D communication with the intended purpose of supporting/maintaining the D2D communication, e.g., possibly in an absence/delay of other D2D traffic.
• a keep-alive signal may be received by the second UE and/or the base station, one or both of which may continue to support the D2D communication in consideration of the keep-alive signal from the first UE.
• the UEs and/or base station involved in setting-up and supporting the D2D communication may also monitor, as applicable, ACK/NACK signals and/or the like that may inform a decision to maintain, alter or possibly end a D2D communication.
• ACK/NACK signals and/or the like may inform a decision to maintain, alter or possibly end a D2D communication.
• a decision may be made by a UE to transmit a request, a report or the like to the base station to affect a possible change or end to the D2D communication.
• the base station may change the D2D communication in some manner, e.g., end it, re-allocate GUL resources, handover one or both UEs to another base station, etc., in response to such a request or report, and/or by monitoring the D2D communication.
• the example methods 400 and 500 illustrate techniques by which conditions of channel quality may be measured and considered in determining if UEs may be D2D communication candidates. Some of the examples presented herein make use of SRS transmissions for D2D channel measurements; however, other transmissions may also be measured using such techniques.
• DM-RS demodulation reference signal
• a base station may instruct the UEs to take channel measurements via SRS transmissions in a distributed fashion.
• Channel quality may be an important factor in determining whether a channel may be used, possibly more so than the distance between UEs.
• switching communication to D2D communication may result in additional interference to neighboring devices.
• Such a cost may also be weighed against the improvement in efficiency when determining whether to switch to D2D communication or not.
• a base station may monitor the D2D communication performance (e.g. RF and latency) because UEs may move with respect to each other, and if needed, the base station may decide to end the D2D communication and possibly switch to an indirect transmission route between the two UEs.
• an existing UL SRS may be utilized to measure channel conditions.
• a UE on request from an gNB, may send a UL SRS aperiodically either in a PUCCH as part of an S subframe, or along with a PUSCH.
• Special subframes are used in TDD mode for switching from downlink to uplink.
• Such subframes may include GP, UpPTS and DwPTS sections, wherein the GP section comprises a guard period between UpPTS and DwPTS sections.
• a UpPTS comprises an Uplink Pilot Time Slot.
• Such an UpPTS may not include a PUCCH or a PUSCH, but may include a PRACH and SRS.
• Such a DwPTS comprises a Downlink Pilot Time Slot which may include a P-SS.
• an SRS may be transmitted once, periodically, or aperiodically.
• the subframes including such SRS transmissions that may be available may be indicated along with SRS bandwidths by the UE specific or cell specific configurations supplied by the gNB. Such a configuration may indicate frequency domain and time domain resources the UE may use.
• the subframe where an SRS transmission occurs is an example of a time domain resource.
• the base station may request a monitored UE to transmit aperiodic SRS in upcoming short PUCCHs (sPUCCHs), or if the monitored UE is already sending UL traffic, to send the SRS with a physical uplink shared channel (PUSCH).
• a sPUCCH may comprise a PUCCH for standalone operation in unlicensed spectrum.
• a gNB may request that the monitoring UE monitor an SRS transmission from a monitored UE in an upcoming sPUCCH/PUSCH transmissions, and provide a corresponding report of such to the gNB.
• FIG. 6 is a block diagram illustrating some example components that may be included within a base station 600.
• base station 600 may comprise or otherwise represent an access point, a NodeB, an evolved NodeB, etc.
• Base station 600 includes a processing unit 602.
• the processing unit 602 may be a general-purpose single- or multi-chip microprocessor (e.g., an ARM), a special purpose microprocessor (e.g., a digital signal processor (DSP)), a microcontroller, a programmable gate array, etc.
• the processing unit 602 may be referred to as a central processing unit (CPU). Although just a single processing unit 602 is shown in the base station 600 of Figure 6, in an alternative configuration, a combination of processors (e.g., an ARM and DSP) could be used.
• Base station 600 may also include memory 606.
• the memory 606 may be any electronic component capable of storing electronic information.
• the memory 606 may be embodied as random access memory (RAM), read only memory (ROM), magnetic disk storage media, optical storage media, flash memory devices in RAM, on board memory included with the processor, EPROM memory, EEPROM memory, registers, and so forth, including combinations thereof.
• data 614 and/or instructions 612 may be stored in memory 606.
• Instructions 612 may be executable by processing unit 602, e.g., to implement, at least in part, techniques disclosed herein. Executing instructions 612 may involve the use of data 614 that may be stored in memory 606.
• processing unit 602 executes instructions 1609
• various portions of instructions 6l2a may be loaded onto processing unit 602, and various pieces of data 6l4a may be loaded onto processing unit 602.
• Base station 600 may also include a transmitter 620 and a receiver 622 to allow transmission and reception of wireless signals, e.g., to and from one or more UEs (not shown).
• Transmitter 620 and receiver 622 may be collectively referred to as a transceiver 604.
• One or more antennas 624a-b may be electrically coupled to the transceiver 604.
• Base station 600 may also include (not shown) multiple transmitters, multiple receivers and/or multiple transceivers.
• the various components of base station 600 may be coupled together by one or more buses or the like, e.g., which may include a power bus, a control signal bus, a status signal bus, a data bus, etc.
• buses or the like e.g., which may include a power bus, a control signal bus, a status signal bus, a data bus, etc.
• the various buses are represented in Figure 6 as a bus 610.
• FIG. 7 is a block diagram illustrating some example components that may be included within a UE 700.
• UE 700 may comprise a processing unit 702.
• Processing unit 702 may be a general-purpose single- or multi-chip microprocessor (e.g., an ARM), a special purpose microprocessor (e.g., a digital signal processor (DSP)), a microcontroller, a
• DSP digital signal processor
• Processing unit 702 may be referred to as a central processing unit (CPU). Although just a single processing unit 702 is shown in the wireless communication device 700 of Figure 12, in an alternative configuration, a combination of processors (e.g., an ARM and DSP) could be used.
• processors e.g., an ARM and DSP
• UE 700 may also include memory 706.
• Memory 706 may be any electronic component capable of storing electronic information.
• Memory 706 may be embodied as random access memory (RAM), read only memory (ROM), magnetic disk storage media, optical storage media, flash memory devices in RAM, on-board memory included with the processor, EPROM memory, EEPROM memory, registers, and so forth, including combinations thereof.
• data 714 and/or instructions 712 may be stored in memory 706.
• Instructions 712 may be executable by processing unit 702 to implement the techniques disclosed herein. Executing instructions 712 may involve the use of the data 714 that may be stored in memory 706.
• processing unit 702 executes instructions 1709, various portions of instructions 7l2a may be loaded onto the processing unit 702, and various pieces of data 7l4a may be loaded onto processing unit 702.
• EE 700 may also include a transmitter 720 and a receiver 722 to allow transmission and reception of wireless signals to and from other devices (not shown).
• Transmitter 720 and receiver 722 may be collectively referred to as a transceiver 704.
• One or more antennas 724a-b may be electrically coupled to transceiver 704.
• EE 700 may also include (not shown) multiple transmitters, multiple receivers and/or multiple transceivers.
• the various components of EE 700 may be coupled together by one or more buses or the like, which may include a power bus, a control signal bus, a status signal bus, a data bus, etc.
• buses or the like may include a power bus, a control signal bus, a status signal bus, a data bus, etc.
• the various buses are illustrated in FIG. 7as a bus 710.
• FIG. 7a a bus 710.
• these methods describe possible implementation, and that the operations and the steps may be rearranged or otherwise modified such that other implementations are possible.
• aspects from two or more of the methods may be combined.
• aspects of each of the methods may include steps or aspects of the other methods, or other steps or techniques described herein.
• FIG. 8 includes an example call-flow 800 that may be implemented, at least in part, by techniques provided herein to allow for D2D communication between a first EE 115-1 and a second EE 115-2.
• call flow 800 in addition to the EEs, a first base station 105-1 and a second base station 105-2 are also included.
• the first base station 105-1 sets-up the D2D communication and there is an example handover to second base station 105-2.
• Signals 802 and 804 may represent one or more reports, requests, or other like indications that may be transmitted from first UE 115-1 and UE 115-2,
• first base station 105-1 respectively, to first base station 105-1, and which may be considered, at least in part, by first base station 105-1 to determine whether a D2D communication is to be set-up.
• first base station 105-1 may be considered, at least in part, by first base station 105-1 to determine whether a D2D communication is to be set-up.
• Signals 806 and 808 are shown as transmitted by first base station 105-1 to first EE 115-1 and second EE 115-2, respectively, and may represent one or more indications that a D2D communication is or will be set-up between the two EEs.
• Signals 806 and 808 may identify at least a portion of GEE resource allocation associated with the D2D communication.
• second EE 115-2 may transmit signal 810 to first EE 115-1, and receive signal 814 from first EE 115-1.
• first EE 115-1 and second EE 115-12 may support, at least in part, the D2D communication.
• method 500 at block 506.
• signal 810 from second EE 115-2 may be received by first base station 105-1, as represented by signal 812.
• signal 814 from first EE 115-2 may be received by first base station 105-1, as represented by signal 816.
• first base station 105-1 may support or otherwise monitor, at least in part, the D2D communication.
• a signal 818 is shown as being transmitted by first EE 115-1 to second EE 115-2 as part of the D2D communication and represents at least one keep-alive message.
• method 500 at block 514.
• keep-alive message may also be received by first base station 105-1 as represented by signal 820.
• method 400 at block 408 wherein the base station may monitor all or part of the D2D communication.
• signal 818/820 may represent an ACK or NACK, e.g., as part of a HARQ process or the like.
• Dashed line 822 is intended to represent some signal that may normally be expected to be received from second UE 115-2 as part of the D2D communication, but for some reason has not been received by first UE 115-1 as further illustrated by the crossed-out section.
• “missing” signal 822 may have been an expected traffic message, an ACK/NACK message, a keep-alive message, etc.
• Signal 822 may be“missing” for any number of reasons, e.g., it was not transmitted, it was attenuated, etc.
• FIG. 8 it is also assumed that signal 822 was also not received by first base station 105-1 or second base station 105-2.
• the D2D communication may possibly be changed or ended, based, at least in part, on a lack of signal 822 transmission/reception.
• a D2D communication may need to be affected in some manner, e.g., changed, ended, handed-off, etc.
• An example of one type of change may be represented by signals 824 and/or 826 by which first base station 105-1 may indicate to first UE 115-1 and second UE 115-2, respectively, a change effecting a D2D communication.
• new/different GUL resource allocation(s) may be indicated, or an end to the D2D communication may be indicated.
• signal(s) 824 and/or 826 may represent indirect signaling supportive of an on-going D2D communication.
• Another example change may be represented by signal 828 by which first base station 105-1 may indicate to second base station 105-2 that first UE 115-1, second UE 115-2 or both may be handed-off
• first base station 105-1 may indicate to second base station 105-2 that first UE 115-1, second UE 115-2 or both may be handed-off
• the D2D the D2D
• Signals 830 and 832 may, for example, represent potential changes to or maintenance of a D2D communication as a result of some handoff from first base station 105-1 to second base station 105-2.
• the functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical (PHY) locations.
• PHY physical
• “or” as used in a list of items indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).
• Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another.
• a non-transitory storage medium may be any available medium that may be accessed by a general purpose or special purpose computer.
• non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable read only memory (EEPROM), compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.
• RAM random access memory
• ROM read only memory
• EEPROM electrically erasable programmable read only memory
• CD compact disk
• magnetic disk storage or other magnetic storage devices or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures
• any connection is properly termed a computer-readable medium.
• the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave
• the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium.
• Disk and disc include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.
• a CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc.
• CDMA2000 covers IS-2000, IS-95, and IS-856 standards.
• IS-2000 Releases 0 and A are commonly referred to as CDMA2000 IX, IX, etc.
• IS-856 (TIA-856) is commonly referred to as CDMA2000 lxEV-DO, High Rate Packet Data (HRPD), etc.
• UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA.
• a TDMA system may implement a radio technology such as (Global System for Mobile communications (GSM)).
• GSM Global System for Mobile communications
• An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (wireless fidelity (Wi- Fi)), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc.
• UMB Ultra Mobile Broadband
• E-UTRA Evolved UTRA
• IEEE 802.11 wireless fidelity
• WiMAX IEEE 802.16
• IEEE 802.20 Flash-OFDM
• UTRA Telecommunications System
• LTE-A LTE-advanced
• the term evolved node B may be generally used to describe the base stations.
• the wireless communications system or systems described herein may include a heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station may provide
• cell is a 3GPP term that may be used to describe a base station, a carrier or component carrier (CC) associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.
• CC component carrier
• Base stations may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point (AP), a radio transceiver, a NodeB, eNodeB (eNB), Home NodeB, a Home eNodeB, or some other suitable terminology.
• the geographic coverage area for a base station may be divided into sectors making up a portion of the coverage area.
• the wireless communications system or systems described herein may include base stations of different types (e.g., macro or small cell base stations).
• the UEs described herein may be able to communicate with various types of base stations and network equipment including macro eNBs, small cell eNBs, relay base stations, and the like.
• Different technologies may be associated with the same base station, or with different base stations.
• the wireless communications system or systems described herein may support synchronous or asynchronous operation.
• the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time.
• the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time.
• the techniques described herein may be used for either synchronous or asynchronous operations.
• the DL transmissions described herein may also be called forward link transmissions while the UL transmissions may also be called reverse link transmissions.
• Each communication link described herein including, for example, wireless
• FIG. 1 may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies). Each modulated signal may be sent on a different sub-carrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc.
• the communication links described herein may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources).
• FDD frequency division duplex
• TDD time division duplex
• Frame structures may be defined for FDD (e.g., frame structure type 1) and TDD (e.g., frame structure type 2).
• aspects of the disclosure may provide for receiving on transmit and transmitting on receive. It should be noted that these methods describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified such that other implementations are possible. In some examples, aspects from two or more of the methods may be combined.
• a general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine.
• a processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).
• the functions described herein may be performed by one or more other processing units (or cores), on at least one integrated circuit (IC).
• IC integrated circuit
• different types of ICs may be used (e.g., Structured/Platform ASICs, an FPGA, or another semi custom IC), which may be programmed in any manner known in the art.
• the functions of each unit may also be implemented, in whole or in part, with instructions embodied in a memory, formatted to be executed by one or more general or application-specific processors.

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• 2019
  • 2019-06-18 EP EP19737357.4A patent/EP3811706A1/de active Pending
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