Patent ID: 12231999

DETAILED DESCRIPTION

As discussed above, in recent years, there has been significant focus on development and implementation of technologies for CV2X communication that may be implemented as part of the 5G NR technology deployment. In a CV2X system, vehicles or UEs within vehicles, may directly communicate with other vehicles or other UEs by directing radio signals in specific directions. Because CV2X communication rely primarily on D2D side-link communication, there may be a lack of centralized base station coordination for such communications. This lack of coordination may result in inefficient use of resources. Thus, in some instances, multiple UEs may be transmitting on overlapping resources or during same time period thereby violating half-duplex constraints.

Aspects of the present disclosure provide techniques for utilizing RSU that may be stationary units or mobile UEs (e.g., part of a vehicle) for managing scheduling requests from one or more UEs for side-link CV2X communication between UEs. To this end, an RSU may determine characteristics associated with the scheduling requests (e.g., traffic type, latency requirements, etc.) to allocate resources in the resource pool to the one or more UEs that comply with the half-duplex constraints. Although the terms “road side,” “roadside,” or the like are part of the terminology used herein for the example RSUs, it should be understood that an actual deployment of such devices need not necessarily require that such devices be located at or even nearby a side of a road, or the like. Instead, it should be understood that such terms are intended to indicate a function or capability rather than an intended location.

Various aspects are now described in more detail with reference to theFIGS.1-10. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect(s) may be practiced without these specific details. Additionally, the term “component” as used herein may be one of the parts that make up a system, may be hardware, firmware, and/or software stored on a computer-readable medium, and may be divided into other components.

The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in other examples.

FIG.1is a diagram illustrating an example of a wireless communications system and an access network100. The wireless communications system (also referred to as a wireless wide area network (WWAN)) includes base stations102, UEs104, an Evolved Packet Core (EPC)160, and a 5G Core (5GC)190. The base stations102may include macro cells (high power cellular base station) and/or small cells (low power cellular base station). The macro cells include base stations. The small cells include femtocells, picocells, and microcells.

The base stations102configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC160through backhaul links132(e.g., S1 interface). The base stations102configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with 5GC190through backhaul links184. In addition to other functions, the base stations102may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations102may communicate directly or indirectly (e.g., through the EPC160or 5GC190) with each other over backhaul links134(e.g., X2 interface). The backhaul links134may be wired or wireless.

The base stations102may wirelessly communicate with the UEs104. Each of the base stations102may provide communication coverage for a respective geographic coverage area110. There may be overlapping geographic coverage areas110. For example, the small cell102′ may have a coverage area110′ that overlaps the coverage area110of one or more macro base stations102. A network that includes both small cell and macro cells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG). The communication links120between the base stations102and the UEs104may include uplink (UL) (also referred to as reverse link) transmissions from a UE104to a base station102and/or downlink (DL) (also referred to as forward link) transmissions from a base station102to a UE104. The communication links120may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. The base stations102/UEs104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell).

Certain UEs104may communicate with each other using device-to-device (D2D) communication link. The D2D communication link158may use the DL/UL WWAN spectrum. The D2D communication link158may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communications systems, such as for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi access point (AP)150in communication with Wi-Fi stations (STAs)152via communication links154in a 5 GHz unlicensed frequency spectrum. When communicating in an unlicensed frequency spectrum, the STAs152/AP150may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.

The small cell102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell102′ may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP150. The small cell102′, employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network.

A base station102, whether a small cell102′ or a large cell (e.g., macro base station), may include an eNB, gNodeB (gNB), or other type of base station. Some base stations, such as gNB180may operate in a traditional sub 6 GHz spectrum, in millimeter wave (mmW) frequencies, and/or near mmW frequencies in communication with the UE104. When the gNB180operates in mmW or near mmW frequencies, the gNB180may be referred to as an mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in the band may be referred to as a millimeter wave. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, also referred to as centimeter wave. Communications using the mmW/near mmW radio frequency band has extremely high path loss and a short range. The mmW base station180may utilize beamforming182with the UE104to compensate for the extremely high path loss and short range.

The EPC160may include a Mobility Management Entity (MME)162, other MMEs164, a Serving Gateway166, a Multimedia Broadcast Multicast Service (MBMS) Gateway168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway172. The MME162may be in communication with a Home Subscriber Server (HSS)174. The MME162is the control node that processes the signaling between the UEs104and the EPC160. Generally, the MME162provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway166, which itself is connected to the PDN Gateway172. The PDN Gateway172provides UE IP address allocation as well as other functions. The PDN Gateway172and the BM-SC170are connected to the IP Services176. The IP Services176may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services. The BM-SC170may provide functions for MBMS user service provisioning and delivery. The BM-SC170may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway168may be used to distribute MBMS traffic to the base stations102belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

The 5GC190may include a Access and Mobility Management Function (AMF)192, other AMFs193, a Session Management Function (SMF)194, and a User Plane Function (UPF)195. The AMF192may be in communication with a Unified Data Management (UDM)196. The AMF192is the control node that processes the signaling between the UEs104and the 5GC190. Generally, the AMF192provides QoS flow and session management. All user Internet protocol (IP) packets are transferred through the UPF195. The UPF195provides UE IP address allocation as well as other functions. The UPF195is connected to the IP Services197. The IP Services197may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services.

The base station may also be referred to as a gNB, Node B, evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. The base station102provides an access point to the EPC160or 5GC190for a UE104. Examples of UEs104include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs104may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc.). The UE104may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

In certain aspects, one or more UEs104may be configured for CV2X communications between UEs104. The UEs104may include various devices related to vehicles and transportation. For example, the UEs104may include vehicles, devices within vehicles, and transportation infrastructure such as roadside devices, tolling stations, fuel supplies, or any other device that that may communicate with a vehicle. A UE104may act as either a host device or a client device for CV2X communication. A host UE104may advertise CV2X services supported by the host UE104. A client UE104may also discover CV2X services supported by the host UE104.

FIG.2is an example scenario200for implementing an RSU205in accordance with aspects of the present disclosure. In CV2X communication one or more UEs104may directly communicate with other UEs104without the need to route the data via a base station (not shown). Thus, in some instance, a first UE104-amay directly transmit packets to a second UE104-bby directing radio signals202in specific directions. While communication between two UEs104alone may be simple, managing resources may become more complicated when the same intersection or area becomes more congested with more UEs104participating in CV2X communication.

In such instances, number of UEs104may be ad-hoc contending for limited resources by selecting and transmitting packets in a congested network to other UEs in side-link communication. Such congestion may result in multiple UEs104transmitting at the same time (e.g., on different sub-bands) and/or on the same resources, thereby causing packet collisions.

Features of the present disclosure address the above-identified problem by implementing RSUs205to manage scheduling requests and resources for side-link communication between multiple UEs (e.g., for communication between first UE104-aand second UE104-b). In some examples, RSUs205may be implemented as stationary units (e.g., as part of the road side units, traffic lights, etc.) or as part of one of the UEs104that may act as a coordinator. To this end, the RSU205, may receive scheduling requests (in communications206/208) from one or more UEs104for resources for side-link communication. In turn, the RSU205may allocate resources in the resource pool based on the requested traffic type and latency requirements of the traffic and the UE to each requesting UE104. The RSU205may issue scheduling grants identifying the allocated resources to the one or more UEs104such that the UEs104may utilize the allocated resources for the side-link communication.

In some instances, UEs104may register with the RSU205to utilize a scheduling management system. The availability of the RSU205may be signaled or advertised by the RSU. In other examples, the UEs104may maintain a database of RSU locations in a region and can be obtained dynamically as UEs104move into different region. The UEs104may begin registering and communicating with the RSU205as the one or more UE104move into the RSU205coverage area220.

In some examples, the coverage area220of the RSU205(or RSU coverage zones) may be asymmetric to the coverage area210of the UE104due to differences in transmission power of the RSUs205and UEs104. Specifically, RSU205to the UE104transmission power may be greater than the transmission power from UE104to the RSU205. Thus, in some instances, while an RSU205may be able to transmit signals, and thus signal its availability to a wider coverage area220, UEs104(e.g., third UE104-c) may not be able to transmit scheduling requests to the RSU205until it is within the coverage area210of the UE104to transmit to RSU205.

FIG.3is an example of an RSU scheduling frame structure300in accordance with aspects of the present disclosure. In some examples, in order to facilitate efficient side-link communication between multiple UEs104in CV2X context for instance, an RSU205may receive and process scheduling requests325from one or more UEs104from previous frame for subsequent frame. In some examples, the RSU scheduling frame structure300as illustrated inFIG.3may be continuously repeated between multiple UEs104and the RSU205. As such, one or more UEs104may issue a scheduling request in the scheduling request portion325of a previous frame for allocation of resources in the subsequent frame (e.g., illustrated frame).

The RSU scheduling frame structure300may include a scheduling grant portion305portion that may include one or more TTIs of the frame. The scheduling grant portion305may include a common scheduling grant portion310that may be common to all UEs104, and thus may be decoded by all the UEs for control information. The scheduling grant portion305may also include a UE-specific (or UE-dedicated) scheduling grant portion315that may be specific to each UE104that may issue a resource grant. In some examples, the RSU205may determine the type of traffic (e.g., fixed or variable packet size, latency requirements of the traffic and UE, etc.) to allocate resources in the resource pool320as discussed in detail below.

FIG.4is an example of a scheduling request design architecture400in accordance with aspects of the present disclosure. In some examples, resource scheduling requests (rSRs)325may occupy two TTIs in the entire frame, and may be split into two types. The first type may be requests from UEs104that are being scheduled (e.g., rSR-S) and the second type may be requests from UEs104that have not been scheduled (e.g., rSR-NS). Specifically, as noted above, in some instances, one or more UEs104or vehicles may be in coverage area of the RSU205, while other UEs104may be outside the coverage area of the RSU205. Similarly, some UEs104may have previously been scheduled with resources.

Thus, for UEs104that have previously been scheduled or are in the coverage area of the RSU205, such UEs104may utilize resources reserved in the scheduling request portion405to issue new scheduling requests. The rSR-S may follow the same ordering as the rSG indication. Further, because the UEs104have been scheduled, the ordering may be known from prior scheduling. Additionally, scheduled UEs rSR-S405may benefit from contention-free issuance of scheduling requests to the RSU205.

In contrast, the non-scheduled UEs rSR-NS410may use listen before talk (LBT) structure to content for resources in the second portion of the scheduling request325. Thus, in some instances, dedicated resources may be made available for rSR-NS transmissions. Non-scheduled UEs may also use resources that may be left unutilized by scheduled UEs (e.g., UEs that may have left the coverage area of the RSU) by using LBT counter in order to utilize any resource gaps.

FIG.5Ais an example of a diagram500of scheduling resources for side-link communication by RSU for various traffic patterns. As illustrated, one or more frames may be transmitted and/or received by the UEs104and the RSU205to facilitate side-link communication for CV2X communication. In one instance, one or more UEs104may issue scheduling requests510(e.g., by UE1, UE2, and UE3) during a scheduling request portion325of the first frame505-a.

In turn, upon receiving the scheduling requests510, the RSU205may determine at least one characteristic associated with the scheduling request (e.g., type of traffic, latency requirements of the UEs, etc.) and issue scheduling grant in the scheduling grant portion305of the second frame505-b. As noted above, the scheduling grant portion305may include a common scheduling grant portion310(e.g., first portion) that may be common for all UEs issuing requests (e.g., UE1, UE2, UE3) and second portion that is UE-dedicated portion to be specifically decoded by the intended recipient UE104. Specifically, the RSU205may allocate resources (e.g., resource blocks) in the resource pool320(seeFIG.3) based on the type of traffic and latency requirements. In some examples, the RSU205may allocate resources in the resource pool320such that resources are distributed in the time domain to satisfy half-duplex constraints of the UEs104. Specifically, half-duplex constraint prevents multiple UEs104from transmitting concurrently. This is because if the first UE104is transmitting at the same time as the second UE104, neither the first UE104nor the second UE104would be able to hear or receive the transmission of the other during the period each is performing its own transmission. In side-link communication, especially for CV2X communication, it may be important to ensure that transmitted communication is received by the intended UEs104. Thus, to accommodate the half-duplex constraints, the RSU205may allocate and organize resources to the one or more UEs104in the time domain in a manner that ensures that no two UEs104transmit during the same time period or TTI in different sub-bands.

In the illustrated example, the one or more UEs104may issue scheduling requests for transmissions of fixed packet size and a latency requirements (e.g., 100 ms latency) that satisfy the latency threshold (e.g., non-urgent packets). Because the UEs104may be scheduled to transmit a fixed packet size data for a specified time interval, the RSU205, in some instances, may be configured to allocate fixed resources to the UEs104. For example, the RSU205may allocate a first set of fixed resources530to the first UE104-abased on first scheduling request510-aissued in first scheduling grant520-a. Similarly, the RSU205may allocate a second set of fixed resources540to the second UE104-bbased on second scheduling request510-bissued in the third scheduling grant520-b. Finally, the RSU205may allocate a third set of fixed resources545to the third UE104-cbased on third scheduling request510-cissued in the third scheduling grant520-c.

While each of the allocated resources (e.g., first resources530, second resources540, third resources545) may be of varying sizes (e.g., first resources530includes four resource blocks and third resource540includes two resource blocks) depending on the packet size transmission requested by corresponding UEs104, each of the resources may be fixed for subsequent number of frames such that the UEs104may omit having to repeatedly request resources. Thus, for example, if a first UE104needs to transmit same size packets for ten continuous frames to a second UE104in side-link communication, the RSU205may be configured to allocate fixed resources in the resource pool with a single scheduling grant that alleviates the need for the UE104to continuously request additional resources for each frame.

FIG.5Bis another example of a diagram550of scheduling resources for side-link communication by RSU for various traffic patterns. As discussed above, the RSU205, may be configured to allocate resources in the resource pool to one or more UEs104in response to scheduling requests based on characteristics of the scheduling requests, including the traffic type, latency requirements of the traffic or the UE104. WhileFIG.5Aabove illustrates an example of fixed packet size traffic type, the diagram550inFIG.5Bis an example of resource allocation for a requests for variable packet sizes.

As withFIG.5Aabove, one or more UEs104may issue a scheduling request510in a scheduling request portion of a frame505-afor resources in subsequent frame505-b. The RSU205, upon receiving the scheduling requests may determine the traffic type and the latency requirements of the traffic and the UE104in allocating resources. If the RSU205determines that the traffic request is for variable packet size, the RSU205may order the allocation of resources in time domain in same sub-band (e.g., to maintain half-duplex constraints) for the one or more UEs104. For example, for a specific sub-band, the RSU may allocate the first TTI resources555to the first UE104-a, second TTI resources560to the second UE104-b, and third TTI resources565to the third UE104-c.

In some examples, the UEs may vary allocation sizes dynamically depending on the traffic. However, the order in which the UEs104may transmit may be strictly maintained as specified by the RSU205. In other words, while one or more UEs104may utilize more or less time on the sub-band for packet transmission, the order in which it would transmit (e.g., the second UE104-bwould follow first UE104-a) would be maintained. Thus, UEs104that may run out of resources for corresponding transmission, may use the rest of the spectrum for transmission by utilizing listen before talk (LBT) procedures to reduce collisions. In some instances, unused resources can also be used by other UEs104by implementing LBT.

Additionally or alternatively, in some examples, the RSU205may be configured to partition the resource pool into one or more virtual frames. For example, a resource pool of 100 ms may be partitioned into ten virtual frames of 10 ms each. Thus, in some instances, the RSU205may order allocation of resources for the UEs based on UE identifications (IDs) based on their respective latency requirements. Thus, for UEs104that may have a lower latency requirements may be scheduled more often in the virtual frames than UEs that have higher latency requirements. For instance, for a 100 ms resource pool, where first UE (UE1) and second UE (UE2) have latency requirements of 20 ms, third UE (UE3) and fourth UE (UE4) have latency requirements of 50 ms, and fifth UE (UE5) and sixth UE (UE6) have latency requirements of 100 ms, the RSU205, in one example, may allocate resources in the virtual frames as follow:

TABLE 1Virtual FramesUE Sequence0 ms-10 msUE110 ms-20 msUE2, UE320 ms-30 msUE1, UE 530 ms-40 msUE2, U440 ms-50 msUE 150 ms-60 msUE 260 ms-70 msUE1, UE370 ms-80 msUE2, UE680 ms-90 msUE1, UE490 ms-100 msUE2

In the above example, UEs that have packets for transmission may transmit in the TTI corresponding to the allocated virtual frame of the resource pool. However, if a UE (e.g., UE2in fourth virtual frame (30 ms-40 ms)) does not have a packet for transmission at the time, the fourth UE (UE4) may recognize absence of any transmission based on the a gap in resources that may indicate that resources are not utilized. As such, if the allocated resource is not being utilized, the subsequent UE that has been allocated that resource may occupy the allocated resource for transmission. Thus, in such manner, RSU205may implement priority transmissions for UEs104to prioritize low latency, high priority traffic.

FIG.5Cis another example of a diagram575of scheduling resources for side-link communication by RSU for various traffic patterns. Specifically, for fixed packet size packets with low latency (e.g., 5 ms) packets, the RSU205may allocate multiple resources to one or more UEs104in the resource pool320in order to maintain tight quality of service (QoS) requirements. For example, with respect to the first UE104-a, the RSU205may allocate a first set of resources580-aand a second set of resources580-bin the resource pool of the same frame. Similarly, the RSU205may allocate different first set of resources582-aand a second set of resources582-bin the resource pool of the same frame to the second UE104-b. The periodicity of the first set and the second set of resources may be adjusted within the frame itself. However, by providing non-continuous resources within the resource pool, the RSU205is able to maintain a tight QoS for the UEs104with low latency (e.g., less than latency threshold) requirements.

FIG.5Dis another example of a diagram585of scheduling resources for side-link communication by RSU for various traffic patterns. Specifically, diagram585illustrates an example of overcoming the half-duplex constraints when the RSU205is forced to allocate resources to one or more UEs104during the same TTI. Specifically, in some instances, one or more UEs104may issue scheduling requests for variable packet sizes with low latency requirements (e.g., 5 ms). In order to satisfy the tight QoS requirements, the RSU205, in some instances, may allocate a first set of resources587to the first104-aduring the first TTI589and a second set of resources588in the different frequency sub-bands, but during the same first TTI589to the second UE104-b. As such, when the first UE104-aand the second UE104-bboth transmit their respective packets during the first TTI589, neither UE104(e.g., first UE104-aor second UE104-b) would be able to hear or receive signals from the other UE's transmission. This is because, in the limited scenario, RSU205failed to satisfy the half-duplex constraints.

However, in order to overcome the above-identified limitation, features of the present disclosure provide techniques that allow the RSU205to hear the transmissions from both the first UE104-aand the second UE104-bduring the first TTI589, and rebroadcast both the first UE packet590-aand the second UE packet590-bat a later portion of the resource pool during a second TTI. Because the RSU205may broadcast all the packets, any UE104that may have failed to receive packets at an earlier time (e.g., due to its own concurrent transmissions), may be able to receive and decode the packets transmitted by the other UE104. Thus, in such instance, the first UE104-amay receive the packets transmitted by the second UE104-b, and the second UE104-bmay receive the packets transmitted by the first UE104-avia the RSU205, while the RSU205is able to satisfy the tight QoS requirements.

FIG.6is an example of a modified RSU scheduling frame structure600that may be implemented by an RSU205to accommodate one or more UEs104with low latency requirements. Specifically, in some instances, the RSU205may receive scheduling requests from one or more UEs104(e.g., a group of UEs) that require low latency (e.g., urgent packets). For such UEs104, it may not be sufficient to wait the entire length of a frame to request new resources. As such, for some low latency UEs104, a single scheduling request period (e.g., scheduling request325TTI) and a single scheduling grant305period that may be available for each frame may be insufficient.

In order to accommodate such low latency UEs104, the UEs104may issue a scheduling request to the RSU205that identifies a first group of UEs (collectively “low latency UEs”) as having low latency requirements for side-link communications. In turn, the RSU205may modify the RSU scheduling frame structure600to accommodate the low latency group of UEs104(e.g., first group of UEs104) by configuring a portion of the resource pool (e.g., one or more frequency sub-bands) to be made available for the low latency UEs104to request and receive scheduling grants inter-frame. Specifically, in addition to the scheduling grant305that includes the common scheduling grant portion310and the UE-Specific scheduling grant portion315, the modified RSU scheduling frame structure600may include additional slots for UEs104to issue resource scheduling requests (rSRs)605and slots for UE-dedicated resource scheduling grants610(rSG-D). Thus, in such instances, the rSR-S605and rSG-D610may be transmitted more frequently than the rSG-Common310for each frame in order to meet the strict latency requirements as well as packet size requirements indicated in the rSR by the UEs.

FIG.7illustrates a hardware components and subcomponents of a RSU205for implementing one or more methods (e.g., methods800,900, and1000) described herein in accordance with various aspects of the present disclosure. For example, one example of an implementation of the RSU205may include a variety of components, some of which have already been described above, but including components such as one or more processors712, memory716and transceiver702in communication via one or more buses744, which may operate in conjunction with the resource management component750to perform functions described herein related to including one or more methods (e.g., methods800,900, and1000) of the present disclosure. In some examples, the RSU205may be a standalone user equipment (e.g., IoT device) or another UE104in a vehicle. In other words, in some instances, a UE104may also act as a RSU205for purposes of scheduling communication for one or more UEs for side-link CV2X communication. Additionally or alternatively, the RSU104may communicate with one or more base stations102or other UEs104wirelessly via antennas765.

The one or more processors712, modem710, memory716, transceiver702, RF front end788and one or more antennas765, may be configured to support voice and/or data calls (simultaneously or non-simultaneously) in one or more radio access technologies. In an aspect, the one or more processors712can include a modem714that uses one or more modem processors. The various functions related to the resource management component750may be included in modem714and/or processors712and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors712may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with transceiver702. In other aspects, some of the features of the one or more processors712and/or modem714associated with resource management component450may be performed by transceiver702.

In some examples, the resource management component750may include scheduling requesting management component755for receiving and processing scheduling requests from one or more UEs104and issuing scheduling grants. Additionally or alternatively, the resource management component750may include resource allocation component760for allocating resources in the resource pool to the one or more UEs to ensure compliance with half-duplex constraints.

The memory716may be configured to store data used herein and/or local versions of application(s)715or resource management component750and/or one or more of its subcomponents being executed by at least one processor712. The memory716can include any type of computer-readable medium usable by a computer or at least one processor712, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, the memory716may be a non-transitory computer-readable storage medium that stores one or more computer-executable codes defining resource management component750and/or one or more of its subcomponents, and/or data associated therewith, when the UE104is operating at least one processor712to execute resource management component750and/or one or more of its subcomponents.

The transceiver702may include at least one receiver706and at least one transmitter708. The receiver706may include hardware, firmware, and/or software code executable by a processor for receiving data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). The receiver706may be, for example, a radio frequency (RF) receiver. In an aspect, the receiver706may receive signals transmitted by at least one UE104. Additionally, receiver706may process such received signals, and also may obtain measurements of the signals, such as, but not limited to, Ec/Io, SNR, RSRP, RSSI, etc. The transmitter708may include hardware, firmware, and/or software code executable by a processor for transmitting data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). A suitable example of the transmitter708may including, but is not limited to, an RF transmitter.

Moreover, in an aspect, transmitting device may include the RF front end788, which may operate in communication with one or more antennas765and transceiver702for receiving and transmitting radio transmissions, for example, wireless communications transmitted by at least one UE104. The RF front end788may be connected to one or more antennas765and can include one or more low-noise amplifiers (LNAs)790, one or more switches792, one or more power amplifiers (PAs)798, and one or more filters796for transmitting and receiving RF signals.

In an aspect, the LNA790can amplify a received signal at a desired output level. In an aspect, each LNA790may have a specified minimum and maximum gain values. In an aspect, the RF front end788may use one or more switches792to select a particular LNA790and its specified gain value based on a desired gain value for a particular application.

Further, for example, one or more PA(s)798may be used by the RF front end788to amplify a signal for an RF output at a desired output power level. In an aspect, each PA798may have specified minimum and maximum gain values. In an aspect, the RF front end788may use one or more switches792to select a particular PA798and its specified gain value based on a desired gain value for a particular application.

Also, for example, one or more filters796can be used by the RF front end788to filter a received signal to obtain an input RF signal. Similarly, in an aspect, for example, a respective filter796can be used to filter an output from a respective PA798to produce an output signal for transmission. In an aspect, each filter796can be connected to a specific LNA790and/or PA798. In an aspect, the RF front end788can use one or more switches792to select a transmit or receive path using a specified filter796, LNA790, and/or PA798, based on a configuration as specified by the transceiver702and/or processor712.

As such, the transceiver702may be configured to transmit and receive wireless signals through one or more antennas765via the RF front end788. In an aspect, the transceiver702may be tuned to operate at specified frequencies such that transmitting device can communicate with, for example, one or more UEs104or one or more cells associated with one or more base stations102. In an aspect, for example, the modem714can configure the transceiver702to operate at a specified frequency and power level based on the configuration of the transmitting device and the communication protocol used by the modem714.

In an aspect, the modem714can be a multiband-multimode modem, which can process digital data and communicate with the transceiver702such that the digital data is sent and received using the transceiver702. In an aspect, the modem714can be multiband and be configured to support multiple frequency bands for a specific communications protocol. In an aspect, the modem714can be multimode and be configured to support multiple operating networks and communications protocols. In an aspect, the modem714can control one or more components of transmitting device (e.g., RF front end788, transceiver702) to enable transmission and/or reception of signals from the network based on a specified modem configuration. In an aspect, the modem configuration can be based on the mode of the modem714and the frequency band in use. In another aspect, the modem configuration can be based on UE configuration information associated with transmitting device as provided by the network during cell selection and/or cell reselection.

FIG.8is a flowchart of an example method800for wireless communications in accordance with aspects of the present disclosure. The method800may be performed by a RSU205that may be an example of a UE104. Although the method800is described below with respect to the elements of the RSU205or UE104, other components may be used to implement one or more of the steps described herein.

At block805, the method800may include receiving, at a RSU, a scheduling request for resources from a first UE for side-link communication with a second UE. In some examples, the scheduling request from the first UE may be received on a first TTI reserved for one or more UEs to transmit scheduling requests to the RSU. In some examples, the resources reserved for scheduling requests may be part of the tail end of the previous frame such that the RSU may issue scheduling grants for resources in subsequent frame. Thus, as noted below, the scheduling grant may be transmitted by the RSU on a second TTI reserved for transmitting scheduling grants to one or more UEs. In some examples, the resources reserved for the scheduling grant may be one or more first slots in the beginning of a frame. Aspects of block805may be performed by transceiver702and scheduling request management component755described with reference toFIG.7above. Thus, with respect to aspects of block805, the modem714, the one or more processors712, the RSU, the scheduling request management component755or one of its subcomponents may define the means for receiving, at a RSU, a scheduling request for resources from a first UE for side-link communication with a second UE.

At block810, the method800may include determining at least one characteristic associated with the scheduling request. In some aspects, the at least one characteristic associated with the scheduling request may include one or more of a packet size for transmission by the first UE or latency requirements of the first UE. Specifically, the first UE may request either resources to transmit fixed packet sizes or variable packet sizes. Further, the first UE may have either a low latency requirement (e.g., collision prevention applications may require high priority transmissions to other vehicles). To this end, in some examples, the method may include determining whether the first UE is scheduled to periodically transmit a fixed packet size based on the scheduling request, and allocating a fixed set of resources in the resource pool for a set number of frames (e.g., next 10 frames) based on determining that the first UE is scheduled to periodically transmit fixed packet size. As such, the first UE may omit repeatedly issuing scheduling request for each frame if the RSU determines that for a specified number of subsequent frames the first UE is set to transmit a fixed size packet.

In some aspects, determining the at least one characteristic associated with the scheduling request may comprise determining whether a latency requirements of the first UE satisfies a latency threshold, and modifying RSU scheduling structure for a frame based on the determining that the latency requirements of the first UE are less than the latency threshold (e.g., the first UE has applications that require priority transmissions). In some examples, modifying the RSU scheduling structure includes increasing periodicity of resources reserved for scheduling requests and UE specific scheduling grants within a frame more than a common scheduling grant portions310.

Further in some instances, to account for low latency requirements of some UEs, the method may include determining that a first UE has a low latency requirement based on the scheduling request, and wherein the first UE has requested transmissions of fixed packet sizes. In such instances, the RSU may allocate a first set of resources in the resource pool of the first frame to the first UE, and allocate a second set of resources in the resource pool of the first frame to the first UE, wherein the first set of resources and the second set of resources are a fixed set of non-continuous resources within same frame. Aspects of block810may be performed by resource management component750described with reference toFIG.7above. Thus, with respect to aspects of block810, the modem714, the one or more processors712, the RSU, the scheduling request management component750or one of its subcomponents may define the means for determining at least one characteristic associated with the scheduling request.

At bock815, the method800may include allocating resources in a resource pool to the first UE based on determining the at least one characteristic associated with the scheduling request. In the instance of variable packet sizes, the method may include the RSU determining whether the first UE is scheduled to transmit packets of variable sizes based on the scheduling request, and allocating a first set of resources in the resource pool based on determining that the first UE is scheduled to transmit packets of variable sizes. In some instances, the RSU may further receive requests from multiple UEs for resources to transmit packets of variable sizes generally during the same TTI as the first request from the first UE. For example, the method may include receiving, at the RSU, a second scheduling request from the second UE for side-link communication. The method may further include determining that the second UE is scheduled to transmit packets of variable sizes based on the second scheduling request. As such, the method may include allocating a second set of resources in the resource pool for the second UE to transmit packets of variable sizes. In some examples, the first set of resources for the first UE and the second set of resources for the second UE may be ordered in time domain by the RSU to comply with half-duplex constraints. Aspects of block815may be performed by resource allocation component760described with reference toFIG.7above. Thus, with respect to aspects of block815, the modem714, the one or more processors712, the RSU, the scheduling resource allocation component760or one of its subcomponents may define the means for allocating resources in a resource pool to the first UE based on determining the at least one characteristic associated with the scheduling request.

At block820, the method800may include transmitting a scheduling grant identifying the allocated resources, wherein the scheduling grant indicates to the first UE the allocated resources in the resource pool that the first UE may utilize for transmission of packets for side-link communication to the second UE. As noted above, the scheduling grant may be transmitted by the RSU on a second TTI reserved for transmitting scheduling grants to one or more UEs. In some examples, the resources reserved for the scheduling grant may be one or more first slots in the beginning of a frame. In some examples, the second TTI reserved for the scheduling grants includes a first portion that is common for all UEs in coverage area of the RSU (e.g., common scheduling grant portion310) and a second portion that is UE specific (e.g., UE-specific scheduling grant portion315). Aspects of block820may be performed by transceiver702and scheduling request management component755described with reference toFIG.7above. Thus, with respect to aspects of block820, the modem714, the one or more processors712, the RSU, the request management component755or one of its subcomponents may define the means for transmitting a scheduling grant identifying the allocated resources, wherein the scheduling grant indicates to the first UE the allocated resources in the resource pool that the first UE may utilize for transmission of packets for side-link communication to the second UE.

FIG.9is a flowchart of another example method900for wireless communications in accordance with aspects of the present disclosure. The method900may be performed by a RSU205that may be an example of a UE104. Although the method900is described below with respect to the elements of the RSU205or UE104, other components may be used to implement one or more of the steps described herein.

At block905, the method900may include, receiving, at a RSU, scheduling requests for resources from one or more UEs for side-link communications. In some examples, the scheduling requests may be for variable packet sizes from the one or more UEs with variable latency requirements. Aspects of block905, may be performed by transceiver702and scheduling request management component755described with reference toFIG.7above. Thus, with respect to aspects of block905, the modem714, the one or more processors712, the RSU, the scheduling request management component755or one of its subcomponents may define the means for receiving, at a RSU, scheduling requests for resources from one or more UEs for side-link communications.

At block910, the method900may include partitioning a set of resources in a resource pool of a frame into a plurality of virtual frames, wherein each virtual frame of the plurality of virtual frames corresponds to a TTI of frequency resources in the resource pool. Aspects of block910may be performed by resource management component750described with reference toFIG.7above. Thus, with respect to aspects of block910, the modem714, the one or more processors712, the RSU, the resource management component750or one of its subcomponents may define the means for partitioning a set of resources in a resource pool of a frame into a plurality of virtual frames, wherein each virtual frame of the plurality of virtual frames corresponds to a TTI of frequency resources in the resource pool.

At block915, the method900may include allocating the plurality of virtual frames to the one or more UEs based on the scheduling requests. In some examples, allocating the plurality of virtual frames to the one or more UEs may include determining a latency requirements of the one or more UEs based on the scheduled requests received at the RSU, and ordering allocation of the resources in the resource pool to the one or more UEs based in part on the latency requirements of the one or more UEs. Aspects of block915may be performed by resource allocation component760described with reference toFIG.7above. Thus, with respect to aspects of block915, the modem714, the one or more processors712, the RSU, the resource allocation component760or one of its subcomponents may define the means for allocating the plurality of virtual frames to the one or more UEs based on the scheduling requests.

At block920, the method900may include transmitting scheduling grant associated with the allocation to the one or more UEs, wherein the scheduling grant indicates to the one or more UEs the virtual frame allocated to the one or more UEs for side-link communication. Aspects of block920may be performed by transceiver702and scheduling request management component755described with reference toFIG.7above. Thus, with respect to aspects of block920, the modem714, the one or more processors712, the RSU, the scheduling request management component755or one of its subcomponents may define the means for transmitting scheduling grant associated with the allocation to the one or more UEs, wherein the scheduling grant indicates to the one or more UEs the virtual frame allocated to the one or more UEs for side-link communication.

FIG.10is a flowchart of another example method1000for wireless communications in accordance with aspects of the present disclosure. The method1000may be performed by a RSU205that may be an example of a UE104. Although the method1000is described below with respect to the elements of the RSU205or UE104, other components may be used to implement one or more of the steps described herein.

At block1005, the method1000may include receiving, at a RSU, a first scheduling request for resources from a first UE for side-link communication. Aspects of block1005, may be performed by transceiver702and scheduling request management component755described with reference toFIG.7above.

At block1010, the method1000may include receiving, at a RSU, a second scheduling request for resources from a second UE for side-link communication. Aspects of block1010, may be performed by transceiver702and scheduling request management component755described with reference toFIG.7above.

At block1015, the method1000may include allocating, to the first UE, a first set of resources in a first frequency sub-band during a first TTI in a resource pool to transmit a first packet. Aspects of block1015may be performed by resource allocation component760described with reference toFIG.7above.

At block1020, the method1000may include allocating, to the second UE, a second set of resources in a second frequency sub-band during the first TTI in a resource pool to transmit a second packet. Aspects of block1020may be performed by resource allocation component760described with reference toFIG.7above.

At block1025, the method1000may include broadcasting, from the RSU, the first packet corresponding to the first UE and the second packet corresponding to the second UE during a second TTI. Aspects of block1025may be performed by transceiver702and scheduling request management component755described with reference toFIG.7above.

Some Further Example Implementations

An example method for wireless communications, comprising: receiving, at a road side unit (RSU), a scheduling request for resources from a first user equipment (UE) for side-link communication with a second UE; determining at least one characteristic associated with the scheduling request; allocating resources in a resource pool to the first UE based on determining the at least one characteristic associated with the scheduling request; and transmitting a scheduling grant identifying the allocated resources, wherein the scheduling grant indicates to the first UE the allocated resources in the resource pool that the first UE is to utilize for transmissions of packets for side-link communication to the second UE.

The above example, wherein the at least one characteristic associated with the scheduling request includes one or more of a packet size for transmission by the first UE or latency requirements of the first UE.

Any of the above example methods, wherein determining the at least one characteristic associated with the scheduling request comprises: determining whether the first UE is scheduled to transmit a fixed packet size or a variable packet size based on the scheduling request; and allocating a fixed set of resources in the resource pool for a set number of frames based on determining that the first UE is scheduled to periodically transmit fixed packet size.

Any of the above example methods, wherein determining the at least one characteristic associated with the scheduling request comprises: determining whether the first UE is scheduled to transmit a fixed packet size or a variable packet size based on the scheduling request; and allocating a first set of resources in the resource pool based on determining that the first UE is scheduled to transmit packets of variable sizes.

Any of the above example methods, further comprising: receiving, at the RSU, a second scheduling request from the second UE for side-link communication; determining that the second UE is scheduled to transmit packets of variable sizes based on the second scheduling request; and allocating a second set of resources in the resource pool for the second UE to transmit packets of variable sizes.

Any of the above example methods, wherein the first set of resources for the first UE and the second set of resources for the second UE are ordered in time domain by the RSU to comply with half-duplex constraints.

Any of the above example methods, wherein the scheduling request from the first UE is received on a first transmission time interval (TTI) reserved for one or more UEs to transmit scheduling requests to the RSU.

Any of the above example methods, wherein the scheduling grant is transmitted by the RSU on a second transmission time interval (TTI) reserved for transmitting scheduling grants to one or more UEs.

Any of the above example methods, wherein the second TTI reserved for the scheduling grants includes a first portion that is common for all UEs in coverage area of the RSU and a second portion that is UE specific.

Any of the above example methods, wherein determining the at least one characteristic associated with the scheduling request comprises: determining whether a latency requirements of the first UE satisfies a latency threshold; and modifying RSU scheduling structure for a frame based on the determining that the latency requirements of the first UE are less than the latency threshold.

Any of the above example methods, wherein modifying the RSU scheduling structure includes increasing periodicity of resources reserved for scheduling requests and UE specific scheduling grants within a frame.

Any of the above example methods, wherein determining the at least one characteristic associated with the scheduling request comprises: determining that a first UE has a low latency requirement based on the scheduling request, wherein the scheduling request further indicates that the first UE is requesting transmission of packets with a fixed packet size.

Any of the above example methods, further comprising: allocating a first set of resources in the resource pool of the first frame to the first UE; and allocating a second set of resources in the resource pool of the first frame to the first UE, wherein the first set of resources and the second set of resources are a fixed set of non-continuous resources within same frame.

An example apparatus for wireless communications, comprising: a memory configured to store instructions; a processor communicatively coupled with the memory, the processor configured to execute the instructions to: receive, at a road side unit (RSU), a scheduling request for resources from a first user equipment (UE) for side-link communication with a second UE; determine at least one characteristic associated with the scheduling request; allocate resources in a resource pool to the first UE based on determining the at least one characteristic associated with the scheduling request; and transmit a scheduling grant identifying the allocated resources, wherein the scheduling grant indicates to the first UE the allocated resources in the resource pool that the first UE is to utilize for transmissions of packets for side-link communication to the second UE.

The above example apparatus, wherein the at least one characteristic associated with the scheduling request includes one or more of a packet size for transmission by the first UE or latency requirements of the first UE.

Any of the above example apparatus, wherein the instructions to determine the at least one characteristic associated with the scheduling request further include instructions to: determining whether the first UE is scheduled to transmit a fixed packet size or a variable packet size based on the scheduling request; and allocate a fixed set of resources in the resource pool for a set number of frames based on determining that the first UE is scheduled to periodically transmit fixed packet size.

Any of the above example apparatus, wherein the instructions to determine the at least one characteristic associated with the scheduling request further include instructions to: determine whether the first UE is scheduled to transmit a fixed packet size or a variable packet size based on the scheduling request; and allocate a first set of resources in the resource pool based on determining that the first UE is scheduled to transmit packets of variable sizes.

Any of the above example apparatus, wherein the processor is further configured to execute the instructions to: receive, at the RSU, a second scheduling request from the second UE for side-link communication; determine that the second UE is scheduled to transmit packets of variable sizes based on the second scheduling request; and allocate a second set of resources in the resource pool for the second UE to transmit packets of variable sizes.

Any of the above example apparatus, wherein the first set of resources for the first UE and the second set of resources for the second UE are ordered in time domain by the RSU to comply with half-duplex constraints.

Any of the above example apparatus, wherein the scheduling request from the first UE is received on a first transmission time interval (TTI) reserved for one or more UEs to transmit scheduling requests to the RSU.

Any of the above example apparatus, wherein the scheduling grant is transmitted by the RSU on a second transmission time interval (TTI) reserved for transmitting scheduling grants to one or more UEs.

Any of the above example apparatus, wherein the second TTI reserved for the scheduling grants includes a first portion that is common for all UEs in coverage area of the RSU and a second portion that is UE specific.

Any of the above example apparatus, wherein the instructions to determine the at least one characteristic associated with the scheduling request further include instructions to: determine whether a latency requirements of the first UE satisfies a latency threshold; and modify RSU scheduling structure for a frame based on the determining that the latency requirements of the first UE are less than the latency threshold.

Any of the above example apparatus, wherein modifying the RSU scheduling structure includes increasing periodicity of resources reserved for scheduling requests and UE specific scheduling grants within a frame.

Any of the above example apparatus, wherein the instructions to determine the at least one characteristic associated with the scheduling request further include instructions to: determine that a first UE has a low latency requirement based on the scheduling request, wherein the scheduling request further indicates that the first UE is requesting transmission of packets with a fixed packet size.

Any of the above example apparatus, wherein the processor is further configured to execute the instructions to: allocate a first set of resources in the resource pool of the first frame to the first UE; and allocate a second set of resources in the resource pool of the first frame to the first UE, wherein the first set of resources and the second set of resources are a fixed set of non-continuous resources within same frame.

An example non-transitory computer readable medium storing instructions, executable by a processor, for wireless communications, comprising instructions for: receiving, at a road side unit (RSU), a scheduling request for resources from a first user equipment (UE) for side-link communication with a second UE; determining at least one characteristic associated with the scheduling request; allocating resources in a resource pool to the first UE based on determining the at least one characteristic associated with the scheduling request; and transmitting a scheduling grant identifying the allocated resources, wherein the scheduling grant indicates to the first UE the allocated resources in the resource pool that the first UE is to utilize for transmissions of packets for side-link communication to the second UE.

The above example non-transitory computer readable medium, wherein the at least one characteristic associated with the scheduling request includes one or more of a packet size for transmission by the first UE or latency requirements of the first UE.

Any of the above example non-transitory computer readable medium, wherein the instructions for determining the at least one characteristic associated with the scheduling request further include instructions for: determining whether the first UE is scheduled to transmit a fixed packet size or a variable packet size based on the scheduling request; and allocating a fixed set of resources in the resource pool for a set number of frames based on determining that the first UE is scheduled to periodically transmit fixed packet size.

An example apparatus for wireless communications, comprising: means for receiving, at a road side unit (RSU), a scheduling request for resources from a first user equipment (UE) for side-link communication with a second UE; means for determining at least one characteristic associated with the scheduling request; means for allocating resources in a resource pool to the first UE based on determining the at least one characteristic associated with the scheduling request; and means for transmitting a scheduling grant identifying the allocated resources, wherein the scheduling grant indicates to the first UE the allocated resources in the resource pool that the first UE is to utilize for transmissions of packets for side-link communication to the second UE.

The above detailed description set forth above in connection with the appended drawings describes examples and does not represent the only examples that may be implemented or that are within the scope of the claims. The term “example,” when used in this description, means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and apparatuses are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, computer-executable code or instructions stored on a computer-readable medium, or any combination thereof.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a specially-programmed device, such as but not limited to a processor, a digital signal processor (DSP), an ASIC, a FPGA or other programmable logic device, a discrete gate or transistor logic, a discrete hardware component, or any combination thereof designed to perform the functions described herein. A specially-programmed processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A specially-programmed 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 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 non-transitory computer-readable medium. Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a specially programmed 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 locations. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of” indicates a disjunctive 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 computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if 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, then 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, as used herein, include compact disc (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.

It should be noted that the techniques described above may be used for various wireless communication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms “system” and “network” are often used interchangeably. 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 1×, 1×, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1×EV-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). An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM™, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies, including cellular (e.g., LTE) communications over a shared radio frequency spectrum band. The description below, however, describes an LTE/LTE-A system for purposes of example, and LTE terminology is used in much of the description below, although the techniques are applicable beyond LTE/LTE-A applications (e.g., to 5G networks or other next generation communication systems).

The previous description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the common principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Furthermore, although elements of the described aspects and/or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and/or embodiment may be utilized with all or a portion of any other aspect and/or embodiment, unless stated otherwise. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.