SWITCHING IN WIRELESS COMMUNICATION

REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No.

62/336,386 filed May 13, 2016, entitled "ENABLE SRS CC-BASED SWITCHING IN A WIRELESS COMMUNICATION SYSTEM", the contents of which are herein

incorporated by reference in their entirety.

FIELD

[0002] The present disclosure relates to wireless technology, and more specifically to techniques that can enable SRS (Sounding Reference Signal) CC (Component Carrier)-based switching.

BACKGROUND

[0003] In LTE (Long Term Evolution) networks, there are many kinds of network traffic that are heavier on the DL (Downlink) than the UL (Uplink). As a result, there are generally a greater number of aggregated downlink component carriers (CC) than the number of aggregated uplink CCs. For the existing UE (User Equipment) categories, the typical CA (Carrier Aggregation)-capable UEs only support one or two uplink CCs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 is a block diagram illustrating an example user equipment (UE) useable in connection with various aspects described herein.

[0005] FIG. 2 is a diagram illustrating example components of a device that can be employed in accordance with various aspects discussed herein.

[0006] FIG. 3 is a diagram illustrating example interfaces of baseband circuitry that can be employed in accordance with various aspects discussed herein.

[0007] FIG. 4 is a diagram illustrating an example CC (Component Carrier) configuration that comprises both at least one normal CC and at least one SRS CC, in connection with various aspects discussed herein.

[0008] FIG. 5 is a block diagram illustrating a system employable at a UE (User Equipment) that facilitates SRS (Sounding Reference Signal) CC-based switching, according to various aspects described herein. [0009] FIG. 6 is a block diagram illustrating a system employable at a BS (Base Station) that facilitates techniques SRS CC-based switching by a UE, according to various aspects described herein.

[0010] FIG. 7 is a diagram illustrating an example scenario showing SRS CC-based switching based on a 1 bit SRS field, according to various aspects discussed herein.

[0011] FIG. 8 is a diagram illustrating an example scenario showing SRS CC-based switching using UpPTS (Uplink Pilot Time Slot) resources, according to various aspects discussed herein.

[0012] FIG. 9 is a diagram illustrating an example of SRS configuration for multiple CCs in a new DCI format, according to various aspects discussed herein.

[0013] FIG. 10 is a flow diagram of an example method that facilitates SRS CC- based switching, according to various aspects discussed herein.

[0014] FIG. 11 is a flow diagram of an example method that facilitates SRS CC- based switching by a UE, according to various aspects discussed herein.

DETAILED DESCRIPTION

[0015] The present disclosure will now be described with reference to the attached drawing figures, wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures and devices are not necessarily drawn to scale. As utilized herein, terms "component," "system," "interface," and the like are intended to refer to a computer-related entity, hardware, software (e.g., in execution), and/or firmware. For example, a component can be a processor (e.g., a microprocessor, a controller, or other processing device), a process running on a processor, a controller, an object, an executable, a program, a storage device, a computer, a tablet PC and/or a user equipment (e.g., mobile phone, etc.) with a processing device. By way of illustration, an application running on a server and the server can also be a component. One or more components can reside within a process, and a component can be localized on one computer and/or distributed between two or more computers. A set of elements or a set of other components can be described herein, in which the term "set" can be interpreted as "one or more."

[0016] Further, these components can execute from various computer readable storage media having various data structures stored thereon such as with a module, for example. The components can communicate via local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network, such as, the Internet, a local area network, a wide area network, or similar network with other systems via the signal).

[0017] As another example, a component can be an apparatus with specific functionality provided by mechanical parts operated by electric or electronic circuitry, in which the electric or electronic circuitry can be operated by a software application or a firmware application executed by one or more processors. The one or more processors can be internal or external to the apparatus and can execute at least a part of the software or firmware application. As yet another example, a component can be an apparatus that provides specific functionality through electronic components without mechanical parts; the electronic components can include one or more processors therein to execute software and/or firmware that confer(s), at least in part, the functionality of the electronic components.

[0018] Use of the word exemplary is intended to present concepts in a concrete fashion. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise, or clear from context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied under any of the foregoing instances. In addition, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form. Furthermore, to the extent that the terms "including", "includes", "having", "has", "with", or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term

"comprising." Additionally, in situations wherein one or more numbered items are discussed (e.g., a "first X", a "second X", etc.), in general the one or more numbered items may be distinct or they may be the same, although in some situations the context may indicate that they are distinct or that they are the same.

[0019] As used herein, the term "circuitry" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware. [0020] Embodiments described herein may be implemented into a system using any suitably configured hardware and/or software. FIG. 1 illustrates an architecture of a system 1 00 of a network in accordance with some embodiments. The system 100 is shown to include a user equipment (UE) 101 and a UE 102. The UEs 101 and 102 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks), but may also comprise any mobile or non-mobile computing device, such as Personal Data Assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, or any computing device including a wireless communications interface.

[0021] In some embodiments, any of the UEs 101 and 102 can comprise an Internet of Things (loT) UE, which can comprise a network access layer designed for low-power loT applications utilizing short-lived UE connections. An loT UE can utilize technologies such as machine-to-machine (M2M) or machine-type communications (MTC) for exchanging data with an MTC server or device via a public land mobile network (PLMN), Proximity-Based Service (ProSe) or device-to-device (D2D) communication, sensor networks, or loT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An loT network describes interconnecting loT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The loT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the loT network.

[0022] The UEs 101 and 102 may be configured to connect, e.g., communicatively couple, with a radio access network (RAN) 1 10— the RAN 1 10 may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), a NextGen RAN (NG RAN), or some other type of RAN. The UEs 101 and 102 utilize connections 103 and 104, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections 103 and 104 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code-division multiple access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3GPP Long Term Evolution (LTE) protocol, a fifth generation (5G) protocol, a New Radio (NR) protocol, and the like. [0023] In this embodiment, the UEs 101 and 1 02 may further directly exchange communication data via a ProSe interface 105. The ProSe interface 105 may

alternatively be referred to as a sidelink interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery Channel (PSDCH), and a Physical Sidelink Broadcast Channel (PSBCH).

[0024] The UE 102 is shown to be configured to access an access point (AP) 106 via connection 107. The connection 107 can comprise a local wireless connection, such as a connection consistent with any IEEE 802.1 1 protocol, wherein the AP 106 would comprise a wireless fidelity (WiFi®) router. In this example, the AP 1 06 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below).

[0025] The RAN 1 1 0 can include one or more access nodes that enable the connections 1 03 and 104. These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, evolved NodeBs (eNBs), next Generation NodeBs (gNB), RAN nodes, and so forth, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). The RAN 1 1 0 may include one or more RAN nodes for providing macrocells, e.g., macro RAN node 1 1 1 , and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node 1 12.

[0026] Any of the RAN nodes 1 1 1 and 1 12 can terminate the air interface protocol and can be the first point of contact for the UEs 101 and 102. In some embodiments, any of the RAN nodes 1 1 1 and 1 12 can fulfill various logical functions for the RAN 1 1 0 including, but not limited to, radio network controller (RNC) functions such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management.

[0027] In accordance with some embodiments, the UEs 101 and 102 can be configured to communicate using Orthogonal Frequency-Division Multiplexing (OFDM) communication signals with each other or with any of the RAN nodes 1 1 1 and 1 1 2 over a multicarrier communication channel in accordance various communication techniques, such as, but not limited to, an Orthogonal Frequency-Division Multiple Access (OFDMA) communication technique (e.g., for downlink communications) or a Single Carrier Frequency Division Multiple Access (SC-FDMA) communication technique (e.g., for uplink and ProSe or sidelink communications), although the scope of the embodiments is not limited in this respect. The OFDM signals can comprise a plurality of orthogonal subcarriers.

[0028] In some embodiments, a downlink resource grid can be used for downlink transmissions from any of the RAN nodes 1 1 1 and 1 12 to the UEs 101 and 1 02, while uplink transmissions can utilize similar techniques. The grid can be a time-frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Such a time-frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest time-frequency unit in a resource grid is denoted as a resource element. Each resource grid comprises a number of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements; in the frequency domain, this may represent the smallest quantity of resources that currently can be allocated. There are several different physical downlink channels that are conveyed using such resource blocks.

[0029] The physical downlink shared channel (PDSCH) may carry user data and higher-layer signaling to the UEs 101 and 102. The physical downlink control channel (PDCCH) may carry information about the transport format and resource allocations related to the PDSCH channel, among other things. It may also inform the UEs 101 and 102 about the transport format, resource allocation, and H-ARQ (Hybrid Automatic Repeat Request) information related to the uplink shared channel. Typically, downlink scheduling (assigning control and shared channel resource blocks to the UE 102 within a cell) may be performed at any of the RAN nodes 1 1 1 and 1 12 based on channel quality information fed back from any of the UEs 101 and 102. The downlink resource assignment information may be sent on the PDCCH used for (e.g., assigned to) each of the UEs 101 and 1 02.

[0030] The PDCCH may use control channel elements (CCEs) to convey the control information. Before being mapped to resource elements, the PDCCH complex-valued symbols may first be organized into quadruplets, which may then be permuted using a sub-block interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, where each CCE may correspond to nine sets of four physical resource elements known as resource element groups (REGs). Four Quadrature Phase Shift Keying (QPSK) symbols may be mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of the downlink control information (DCI) and the channel condition. There can be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=1 , 2, 4, or 8).

[0031] Some embodiments may use concepts for resource allocation for control channel information that are an extension of the above-described concepts. For example, some embodiments may utilize an enhanced physical downlink control channel (EPDCCH) that uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more enhanced the control channel elements (ECCEs). Similar to above, each ECCE may correspond to nine sets of four physical resource elements known as an enhanced resource element groups (EREGs). An ECCE may have other numbers of EREGs in some situations.

[0032] The RAN 1 1 0 is shown to be communicatively coupled to a core network (CN) 1 20— via an S1 interface 1 1 3. In embodiments, the CN 120 may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN. In this embodiment the S1 interface 1 13 is split into two parts: the S1 -U interface 1 14, which carries traffic data between the RAN nodes 1 1 1 and 1 12 and the serving gateway (S-GW) 122, and the S1 -mobility management entity (MME) interface 1 15, which is a signaling interface between the RAN nodes 1 1 1 and 1 12 and MMEs 121 .

[0033] In this embodiment, the CN 1 20 comprises the MMEs 1 21 , the S-GW 122, the Packet Data Network (PDN) Gateway (P-GW) 123, and a home subscriber server (HSS) 124. The MMEs 121 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 121 may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS 124 may comprise a database for network users, including subscription-related information to support the network entities' handling of

communication sessions. The CN 120 may comprise one or several HSSs 124, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 124 can provide support for routing/roaming, authentication, authorization, naming/addressing resolution, location dependencies, etc.

[0034] The S-GW 122 may terminate the S1 interface 1 13 towards the RAN 1 1 0, and routes data packets between the RAN 1 10 and the CN 120. In addition, the S-GW 122 may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement.

[0035] The P-GW 123 may terminate an SGi interface toward a PDN. The P-GW 123 may route data packets between the EPC network 123 and external networks such as a network including the application server 130 (alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 125. Generally, the application server 130 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this embodiment, the P-GW 123 is shown to be communicatively coupled to an application server 130 via an IP communications interface 125. The application server 130 can also be configured to support one or more communication services (e.g., Voice-over-Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs 1 01 and 102 via the CN 120.

[0036] The P-GW 123 may further be a node for policy enforcement and charging data collection. Policy and Charging Enforcement Function (PCRF) 126 is the policy and charging control element of the CN 120. In a non-roaming scenario, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE's Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with local breakout of traffic, there may be two PCRFs associated with a UE's IP-CAN session: a Home PCRF (H-PCRF) within a HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF 126 may be communicatively coupled to the application server 130 via the P-GW 123. The application server 130 may signal the PCRF 126 to indicate a new service flow and select the appropriate Quality of Service (QoS) and charging parameters. The PCRF 126 may provision this rule into a Policy and Charging Enforcement Function (PCEF) (not shown) with the appropriate traffic flow template (TFT) and QoS class of identifier (QCI), which commences the QoS and charging as specified by the application server 130.

[0037] FIG. 2 illustrates example components of a device 200 in accordance with some embodiments. In some embodiments, the device 200 may include application circuitry 202, baseband circuitry 204, Radio Frequency (RF) circuitry 206, front-end module (FEM) circuitry 208, one or more antennas 21 0, and power management circuitry (PMC) 21 2 coupled together at least as shown. The components of the illustrated device 200 may be included in a UE or a RAN node. In some embodiments, the device 200 may include less elements (e.g., a RAN node may not utilize application circuitry 202, and instead include a processor/controller to process IP data received from an EPC). In some embodiments, the device 200 may include additional elements such as, for example, memory/storage, display, camera, sensor, or input/output (I/O) interface. In other embodiments, the components described below may be included in more than one device (e.g., said circuitries may be separately included in more than one device for Cloud-RAN (C-RAN) implementations).

[0038] The application circuitry 202 may include one or more application processors. For example, the application circuitry 202 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications or operating systems to run on the device 200. In some embodiments, processors of application circuitry 202 may process IP data packets received from an EPC.

[0039] The baseband circuitry 204 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 204 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 206 and to generate baseband signals for a transmit signal path of the RF circuitry 206. Baseband processing circuity 204 may interface with the application circuitry 202 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 206. For example, in some embodiments, the baseband circuitry 204 may include a third generation (3G) baseband processor 204A, a fourth generation (4G) baseband processor 204B, a fifth generation (5G) baseband processor 204C, or other baseband processor(s) 204D for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G), sixth generation (6G), etc.). The baseband circuitry 204 (e.g., one or more of baseband processors 204A-D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 206. In other embodiments, some or all of the functionality of baseband processors 204A-D may be included in modules stored in the memory 204G and executed via a Central Processing Unit (CPU) 204E. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 204 may include Fast-Fourier Transform (FFT), precoding, or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 204 may include convolution, tail- biting convolution, turbo, Viterbi, or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[0040] In some embodiments, the baseband circuitry 204 may include one or more audio digital signal processor(s) (DSP) 204F. The audio DSP(s) 204F may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 204 and the application circuitry 202 may be implemented together such as, for example, on a system on a chip (SOC).

[0041] In some embodiments, the baseband circuitry 204 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 204 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 204 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[0042] RF circuitry 206 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 206 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 206 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 208 and provide baseband signals to the baseband circuitry 204. RF circuitry 206 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 204 and provide RF output signals to the FEM circuitry 208 for transmission.

[0043] In some embodiments, the receive signal path of the RF circuitry 206 may include mixer circuitry 206a, amplifier circuitry 206b and filter circuitry 206c. In some embodiments, the transmit signal path of the RF circuitry 206 may include filter circuitry 206c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206d for synthesizing a frequency for use by the mixer circuitry 206a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 206a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 208 based on the synthesized frequency provided by synthesizer circuitry 206d. The amplifier circuitry 206b may be configured to amplify the down- converted signals and the filter circuitry 206c may be a low-pass filter (LPF) or bandpass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 204 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 206a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[0044] In some embodiments, the mixer circuitry 206a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 206d to generate RF output signals for the FEM circuitry 208. The baseband signals may be provided by the baseband circuitry 204 and may be filtered by filter circuitry 206c.

[0045] In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and upconversion, respectively. In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may be configured for super-heterodyne operation.

[0046] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 206 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 204 may include a digital baseband interface to communicate with the RF circuitry 206. [0047] In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the

embodiments is not limited in this respect.

[0048] In some embodiments, the synthesizer circuitry 206d may be a fractional-N synthesizer or a fractional N/N+1 synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 206d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[0049] The synthesizer circuitry 206d may be configured to synthesize an output frequency for use by the mixer circuitry 206a of the RF circuitry 206 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 206d may be a fractional N/N+1 synthesizer.

[0050] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 204 or the applications processor 202 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 202.

[0051] Synthesizer circuitry 206d of the RF circuitry 206 may include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip- flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0052] In some embodiments, synthesizer circuitry 206d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry 206 may include an IQ/polar converter.

[0053] FEM circuitry 208 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 210, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 206 for further processing. FEM circuitry 208 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 206 for transmission by one or more of the one or more antennas 21 0. In various embodiments, the amplification through the transmit or receive signal paths may be done solely in the RF circuitry 206, solely in the FEM 208, or in both the RF circuitry 206 and the FEM 208.

[0054] In some embodiments, the FEM circuitry 208 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include an LNA to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 206). The transmit signal path of the FEM circuitry 208 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 206), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 21 0).

[0055] In some embodiments, the PMC 212 may manage power provided to the baseband circuitry 204. In particular, the PMC 21 2 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 212 may often be included when the device 200 is capable of being powered by a battery, for example, when the device is included in a UE. The PMC 21 2 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation

characteristics.

[0056] While FIG. 2 shows the PMC 212 coupled only with the baseband circuitry 204. However, in other embodiments, the PMC 2 12 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, application circuitry 202, RF circuitry 206, or FEM 208.

[0057] In some embodiments, the PMC 212 may control, or otherwise be part of, various power saving mechanisms of the device 200. For example, if the device 200 is in an RRC_Connected state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it may enter a state known as Discontinuous Reception Mode (DRX) after a period of inactivity. During this state, the device 200 may power down for brief intervals of time and thus save power.

[0058] If there is no data traffic activity for an extended period of time, then the device 200 may transition off to an RRCJdle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 200 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 200 may not receive data in this state, in order to receive data, it must transition back to RRC_Connected state.

[0059] An additional power saving mode may allow a device to be unavailable to the network for periods longer than a paging interval (ranging from seconds to a few hours). During this time, the device is totally unreachable to the network and may power down completely. Any data sent during this time incurs a large delay and it is assumed the delay is acceptable.

[0060] Processors of the application circuitry 202 and processors of the baseband circuitry 204 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 204, alone or in combination, may be used execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 204 may utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g., transmission communication protocol (TCP) and user datagram protocol (UDP) layers). As referred to herein, Layer 3 may comprise a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 may comprise a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, described in further detail below. As referred to herein, Layer 1 may comprise a physical (PHY) layer of a UE/RAN node, described in further detail below.

[0061] FIG. 3 illustrates example interfaces of baseband circuitry in accordance with some embodiments. As discussed above, the baseband circuitry 204 of FIG. 2 may comprise processors 204A-204E and a memory 204G utilized by said processors. Each of the processors 204A-204E may include a memory interface, 304A-304E,

respectively, to send/receive data to/from the memory 204G.

[0062] The baseband circuitry 204 may further include one or more interfaces to communicatively couple to other circuitries/devices, such as a memory interface 312 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 204), an application circuitry interface 314 (e.g., an interface to send/receive data to/from the application circuitry 202 of FIG. 2), an RF circuitry interface 316 (e.g., an interface to send/receive data to/from RF circuitry 206 of FIG. 2), a wireless hardware connectivity interface 31 8 (e.g., an interface to send/receive data to/from Near Field Communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components), and a power management interface 320 (e.g., an interface to send/receive power or control signals to/from the PMC 212).

[0063] In general, a UE (User Equipment) can support more CCs (Component Carriers) for DL (Downlink) than for UL (Uplink). For a carrier supporting both uplink and downlink, transmit diversity based feedback without PMI (Precoding Matrix Indicator) and with SRS (Sounding Reference Signal) can be beneficial, as channel reciprocity can be used. However, a UE generally has the capability of aggregating a larger number of carriers in the DL than in the UL. As a result, some TDD (Time Division Duplexing) carriers with DL transmission for the UE can have no UL transmission including SRS, and channel reciprocity cannot be utilized for these carriers. Such situations can become more severe with CA (Carrier Aggregation) enhancement of up to 32 CCs where a large portion of CCs are TDD.

[0064] A new work item of "SRS Carrier based Switching for LTE" was approved at RAN#71 (Radio Access Network Working Group 1 Meeting 71 ). The main target is to provide the possibility of transmitting SRS on CCs for which uplink is not configured for PUSCH transmission, to enable a fast link adaptation and beamforming for TDD carriers by exploiting channel reciprocity.

[0065] In Rel-1 3 (Release 13) LTE (Long Term Evolution), a UL DCI (Downlink Control Information) format can trigger the transmission of a SRS on the same CC that the PUSCH transmission is scheduled. In addition, for TDD, a 1 -bit SRS request field in a DL DCI format can be used to trigger SRS transmission on SIB-2 (System Information Block 2)-linked UL CC(s).

[0066] Conventionally, there is no UL grant for SRS CCs where a UE is not configured for PUSCH (Physical Uplink Shared Channel) transmission, and there is a SRS triggering limitation using 1 -bit SRS request field in DL DCI format. However, techniques discussed herein can enable SRS CC-based switching that can trigger SRS transmission(s) in an efficient manner with minimized control overhead. In various aspects, an enhanced DL DCI format design and various means to dynamically trigger one or more SRS transmissions on SRS CC(s) where PUSCH is not configured can be employed. Additionally, in various aspects, signaling mechanisms discussed herein can be employed to determine the SRS CCs based on the configured DL CC and normal UL CCs. In aspects, UpPTS (Uplink Pilot Time Slot)-based SRS CC-based switching techniques can be employed to avoid collision between SRS and PUCCH (Physical Uplink Control Channel)/PUSCH on normal CC. Further, in various aspects, a timing relationship between HARQ (Hybrid ARQ (Automatic Repeat Request)-ACK

(Acknowledgement) and SRS transmission discussed herein can be employed.

Additionally, in aspects, a UE-group-specific DCI format design for SRS transmission triggering discussed herein can be employed.

[0067] Techniques discussed herein can facilitate SRS CC-based switching and triggering of aperiodic SRS (also referred to herein as "A-SRS") transmission. In aspects, techniques discussed herein can be employed to trigger SRS transmission(s) on CC(s) that are not configured with PUSCH transmission.

[0068] As used herein, a "SRS CC" represents an UL CC that is not configured with PUSCH transmission but can be configured with SRS transmission, while a "normal CC" represents a UL CC that can be configured with any UL channels, for example, at least PUSCH and SRS.

[0069] Referring to FIG. 4, illustrated is a diagram of an example CC configuration that comprises both at least one normal CC and at least one SRS CC, in connection with various aspects discussed herein. FIG. 4 illustrates one possible CA configuration for enabling SRS CC-based switching, which can be employed in a LTE system or another wireless system. The CA configuration can comprise a number of normal CCs, for example CC#0 and CC#1 in FIG. 4, where PUSCH transmission is configured on its SIB-2 linked UL 450 and 460, as in Rel-13. More particularly, a number of SRS CCs, for example, CC#2 and CC#3 can also be included, where PUSCH transmission is not configured on the SIB-2 linked UL 470 and 480. SRS is allowed to be transmitted on UL CC 470 and 480, for example, in a TDM manner, to enable a fast link adaptation and beamforming for DL transmission on CC#2 and CC#3 by exploiting channel reciprocity.

[0070] Referring to FIG. 5, illustrated is a block diagram of a system 500 employable at a UE (User Equipment) that facilitates SRS CC-based switching, according to various aspects described herein. System 500 can include one or more processors 510 (e.g., one or more baseband processors such as one or more of the baseband processors discussed in connection with FIG. 2 and/or FIG. 3) comprising processing circuitry and associated memory interface(s) (e.g., memory interface(s) discussed in connection with FIG. 3), transceiver circuitry 520 (e.g., comprising one or more of transmitter circuitry or receiver circuitry, which can employ common circuit elements, distinct circuit elements, or a combination thereof), and a memory 530 (which can comprise any of a variety of storage mediums and can store instructions and/or data associated with one or more of processor(s) 510 or transceiver circuitry 520). In various aspects, system 500 can be included within a user equipment (UE). As described in greater detail below, system 500 can facilitate generation of triggered SRS by a UE on one or more CCs not configured for PUSCH.

[0071] Referring to FIG. 6, illustrated is a block diagram of a system 600 employable at a BS (Base Station) that facilitates SRS CC-based switching by a UE, according to various aspects described herein. System 600 can include one or more processors 610 (e.g., one or more baseband processors such as one or more of the baseband processors discussed in connection with FIG. 2 and/or FIG. 3) comprising processing circuitry and associated memory interface(s) (e.g., memory interface(s) discussed in connection with FIG. 3), communication circuitry 620 (e.g., which can comprise circuitry for one or more wired (e.g., X2, etc.) connections and/or transceiver circuitry that can comprise one or more of transmitter circuitry (e.g., associated with one or more transmit chains) or receiver circuitry (e.g., associated with one or more receive chains), wherein the transmitter circuitry and receiver circuitry can employ common circuit elements, distinct circuit elements, or a combination thereof), and memory 630 (which can comprise any of a variety of storage mediums and can store instructions and/or data associated with one or more of processor(s) 610 or communication circuitry 620). In various aspects, system 600 can be included within an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (Evolved Node B, eNodeB, or eNB) or other base station in a wireless communications network. In some aspects, the processor(s) 61 0, communication circuitry 620, and the memory 630 can be included in a single device, while in other aspects, they can be included in different devices, such as part of a distributed architecture. As described in greater detail below, system 600 can facilitate triggering SRS from a UE on one or more CCs not configured for PUSCH, according to various aspects discussed herein.

[0072] In various aspects discussed herein, signals and/or messages can be generated and output for transmission, and transmitted messages can be received and processed. Depending on the type of signal or message generated, outputting for transmission (e.g., by processor(s) 510, processor(s) 610, etc.) can comprise one or more of the following: generating a set of associated bits that indicate the content of the signal or message, coding (e.g., which can include adding a cyclic redundancy check (CRC) and/or coding via one or more of turbo code, low density parity-check (LDPC) code, tailbiting convolution code (TBCC), etc.), scrambling (e.g., based on a scrambling seed), modulating (e.g., via one of binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), or some form of quadrature amplitude modulation (QAM), etc.), and/or resource mapping (e.g., to a scheduled set of resources, to a set of time and frequency resources granted for uplink transmission, etc.). Depending on the type of received signal or message, processing (e.g., by processor(s) 510, processor(s) 61 0, etc.) can comprise one or more of: identifying physical resources associated with the signal/message, detecting the signal/message, resource element group deinterleaving, demodulation, descrambling, and/or decoding.

[0073] In various aspects, the UL SRS CCs can be a subset of the configured DL CCs for a given UE, which can support channel reciprocity to all configured DL serving cells in accordance with various techniques discussed herein. Additionally, in aspects, one new IE (Information Element) can be introduced per band combination, which can indicate whether to support SRS CC-based switching for a particular CA configuration.

[0074] In various aspects, a UE can determine (e.g., via processor(s) 510) the serving cells or CCs and the corresponding SRS configuration(s) to transmit (e.g., via transceiver circuitry 520) SRS (e.g., generated by processor(s) 510) in response to detecting a positive SRS request in PDCCH (e.g., received via transceiver circuitry 520 and decoded by processor(s) 510) that schedules PDSCH on a serving cell c. SRS transmitted by a UE as discussed herein can be received at a BS (Base Station, e.g., eNB, etc.) via communication circuitry 620 and processed by processor(s) 610 (e.g., processor(s) 610 can measure the SRS on a given CC , and can estimate UL channel quality of the given CC based on the measured SRS for the given CC).

[0075] In various aspects, all CCs configured to a given UE, including both normal CCs and SRS CCs, can be grouped into one or more sets of CCs. Each set of CCs can comprise at least one normal CC. Mapping of SRS CCs to a respective set of CCs can be configured by RRC (Radio Resource Control) signaling (e.g., generated by processor(s) 610, transmitted via communication circuitry 620, received via

communication circuitry 520, and processed via processor(s) 510) and a set size of each set of CCs can be controlled by RRC. A unique CCs set ID can additionally be provided by RRC for each of the SRS CCs, which can facilitate management of SRS CCs. In various such aspects, the SRS carrier based switching operation can be limited to CCs that are within the same set of CCs. In various aspects, the CCs grouping can be based on the band information. For example, the CCs in a same band can be grouped into a set of CCs to minimize the interruption time (i.e., gap) between different UL carriers during switching. In some aspects, the order of CCs within a set of CCs for SRS CC-based switching can be explicitly configured as part of RRC signaling.

Alternatively, in other aspects, the order of CCs can be based on the SRS CC indices.

[0076] In various embodiments, a 1 -bit SRS request bit in a DL DCI format can be used for triggering set-based SRS CC-based switching. For example, upon detection of a positive SRS request (e.g., a field value of "1 ," as discussed in examples herein, or "0" in other embodiments) in PDCCH scheduling PUSCH/PDSCH on serving cell c, a UE can transmit SRS on all SRS CCs within the same set of CCs. Referring to FIG. 7, illustrated is a diagram of an example scenario showing SRS CC-based switching based on a 1 bit SRS field, according to various aspects discussed herein. As illustrated in FIG. 7, upon detection of PDCCH 710 (e.g., by processor(s) 51 0, based on signaling received via transceiver circuitry 520) with a SRS request field set to "1 ", the UE can transmit (e.g., via transceiver circuitry 520) SRS 730 (e.g., generated by processor(s) 51 0) on CC0, and SRS 740 and 750 (e.g., generated by processor(s) 510) on SRS CC1 and SRS CC2 of the same set of CCs 720, which can be based on a timing relationship (e.g., which can be predefined or configured via higher layer signaling (e.g., RRC, etc.)) and interruption gap(s) 760 and 770 (e.g., which can be predefined). In other aspects, different SRS timing can be employed than that illustrated in FIG. 7. For example, SRS transmissions on different CCs can be located in the last symbol of different subframes. In such aspects, the timing relationship between these SRS subframes can be either predefined or configured by higher layer signaling (e.g., generated by processor(s) 610, transmitted via communication circuitry 620, received via transceiver circuitry 520, and processed by processor(s) 510).

[0077] In various aspects, the SRS request field size can comprise more than 1 bit (e.g., 2 bits). In such aspects, more than one SRS transmission(s) on multiple SRS CCs can be triggered (e.g., generated by processor(s) 510, transmitted via transceiver circuitry 520, received via communication circuitry 620, and processed by processor(s) 61 0) according to the value of the SRS request field in the DL DCI formats, such as in the example multi-bit SRS request fields of Table 1 , below. In aspects, the sets of serving cells can be configured by RRC signaling. In some embodiments, a multi-bit (e.g., 2-bits) SRS request field is present in some, but not all, DCI format, for example, DCI formats 1 A, 2B, 2C, and 2D. In other embodiments, the multi-bit SRS request field can be present for all DL DCI formats. In some aspects, the symbol index within a subframe for SRS transmission can be configured by higher layers (e.g., via higher layer signaling generated by processor(s) 610, transmitted via communication circuitry 620, received via transceiver circuitry 520, and processed by processor(s) 510) in addition to the serving cell index information. In other aspects, the symbol index can be dynamically indicated via the DCI format(s) (e.g., indicated via DCI of an appropriate format (e.g., which can depend on the embodiment) generated by processor(s) 610, transmitted via communication circuitry 620, received via transceiver circuitry 520, and processed by processor(s) 510).

Table 1 : SRS request field in DL DCI format (e.g., 1 A/2B/2C/2D) in UE specific search space

[0078] In various aspects, a single common set of SRS parameters can be configured for DCI formats 1 A/2B/2C/2D by higher layer signaling (e.g., generated by processor(s) 610, transmitted via communication circuitry 620, received via transceiver circuitry 520, and processed by processor(s) 510). The common set of SRS parameters can comprise one or more of: the transmission comb, starting PRB (physical resource block) assignment, duration, SRS periodicity and offset index, SRS bandwidth, frequency hopping bandwidth, cyclic shift, and/or number of antenna ports parameter. For example, a SRS CC can be included in either a first set of serving cells or a second set of serving cells for aperiodic SRS transmissions triggering by DCI format

1 A/2B/2C/2D transmitted (e.g., via communication circuitry 620 of DCI generated by processor(s) 610, which can be received via transceiver circuitry 520 and processed by processor(s) 510) on any serving cell. Such techniques can provide more flexibility for SRS transmission on SRS CCs compared to conventional techniques.

[0079] In another set of aspects, the serving cell information where the DCI (e.g., format 1 A/2B/2C/2D/3B, etc.) is transmitted can be additionally utilized to support up to four separate sets of serving cells for SRS transmission triggering, via one or more of a 2-bit SRS request field and/or a serving cell index. One example of SRS request fields that can support up to four separate sets of serving cells is shown below in Table 2, showing an example utilizing a combination of SRS request field and serving cell index:

Table 2: SRS request field in DL DCI format (e.g., 1 A/2B/2C/2D) in UE specific search space

[0080] In various aspects, the combination of 2-bit SRS request field and serving cell index can be used to trigger SRS transmission on an associated serving cells in a particular CCs set. Table 3, below, gives an example set of SRS request fields for such aspects:

Table 2: SRS request field in DL DCI format (e.g., 1 A/2B/2C/2D) in UE specific search space

[0081] In various aspects, the sets of serving cells and sets of SRS parameters in Table 3 can be separately configured by higher layers using independent IE.

Additionally, in aspcts, the association between a combination of <One Serving cell, one value of SRS request field> and a corresponding set of CCs or a combination of <CCs set index, SRS parameter set index> can be explicitly configured by RRC signaling in a UE-specific manner (e.g., generated by processor(s) 610, transmitted via

communication circuitry 620, received via transceiver circuitry 520, and processed by processor(s) 510).

[0082] In various aspects, to reduce RRC signaling overhead, the CC index in a combination of Table 2 or 3 need not be transmitted over the air. In such aspect, rules to implicitly associate one or more CCs with a particular set of CCs for SRS

transmission triggering can be specified.

[0083] In some aspects, CC "k" can be used to trigger SRS transmission on the (k+1 )-th set of serving cells, where k = N mod L, N denotes the number of CCs, and L is the total number of CCs set configured by RRC for a given UE. As an example, for N = 16 and L =4, then any cell of <CC0, CC4, CC8, CC12> can be used together with "10" to trigger SRS transmission for the first set of CCs configured by higher layer.

[0084] In various aspects, the serving cells can be first grouped into multiple cell groups (CGs). In such aspects, each CG can comprise at least one CC that can be configured with PUSCH transmission. Then, any serving cell belonging to CG 'X' can be used to trigger SRS transmission for a set of CCs within CG 'X' by setting the 2-bit SRS request field with one respective value (e.g., "10" or "1 1 "). The UE can perform SRS transmission (e.g., via transceiver circuitry 520 of SRS generated by processor(s) 510) for serving cells of the associated CG upon decoding (e.g., via processor(s) 51 0) DL DCI (e.g., of format 1 A/2B/2C/2D/3B, etc., received via transceiver circuitry 520) on any serving cell within a CG if the respective SRS request field in the DL format is set to trigger a SRS transmission.

[0085] In various aspects, the triggered SRS transmissions can be limited to an Uplink pilot time slot (UpPTS) field to avoid the collision with PUSCH or PUCCH on other normal CCs.

[0086] Referring to FIG. 8, illustrated is a diagram of an example scenario showing SRS CC-based switching using UpPTS resources, according to various aspects discussed herein. In the example of FIG. 8, SRS CC1 and CC2 can be grouped into a set of CCs (e.g., due to being within a same frequency band), SRS 810 on SRS CC1 and SRS 820 on SRC CC2 (e.g., generated by processor(s) 510) can be transmitted (e.g., via transceiver circuitry 520) via different symbols within a single UpPTS of Special subframe 800 (e.g., which can comprise a DwPTS (Downlink Pilot Time Slot), an optional guard period, and an UpPTS). The symbol index 810 and 820 or location in an UpPTS can be either explicitly configured by RRC message (e.g., generated by processor(s) 610, transmitted via communication circuitry 620, received via transceiver circuitry 520, and processed by processor(s) 510) as part of SRS resource

configuration, or can be dynamically indicated by physical DCI format (e.g., in a DCI message generated by processor(s) 610, transmitted via communication circuitry 620, received via transceiver circuitry 520, and processed by processor(s) 510). In addition, the DCI format can also be utilized to indicate one or more of the bandwidth, UL antenna, timing, etc. In one example embodiment, a UE can be configured with four possible combinations of SRS locations and/or bandwidth and/or antenna indices. In such aspects, a 2-bit SRS request field in a DL DCI format can be used to trigger one of the four combinations according to a predefined mapping relationship. Such

embodiments can be advantageous in scenarios wherein the interruption time is on the order of 10s of με or 100 με.

[0087] For SRS switching between inter-band CCs, the interruption time can potentially be up to several milliseconds. In order to align the reception time of SRS from different UEs, a contention-free random access (CFRA) procedure ordered by PDCCH can be initiated before SRS transmission on a SRS CC to obtain the timing advance value. In some aspects, the SRS transmissions on one or more SRS CCs can be triggered in a Random Access Response (RAR) grant (e.g., generated by

processor(s) 610, transmitted via communication circuitry 620, received via transceiver circuitry 520, and processed by processor(s) 510). For example, SRS can be triggering via a new bit added to a conventional RAR. Alternatively, an existing bit of the RAR (e.g., the CQI request bit) can be re-interpreted to trigger SRS transmission.

[0088] In some aspects wherein a DL DCI format is employed to trigger an SRS transmission on a SRS CC, there can be a fixed timing relationship between the HARQ- ACK timing and the SRS timing. As one example, the SRS transmission can be scheduled in a subsequent (e.g., the first available, etc.) cell-specific SRS opportunity after the corresponding PUCCH subframe used to convey HARQ-ACK based on the DL HARQ-ACK timeline. In other embodiments, another fixed relationship between the HARQ-ACK timing and SRS timing can be employed. Alternatively, in various embodiments, SRS (e.g., generated by processor(s) 510) transmission (e.g., via transceiver circuitry 520) can be in the same subframe as that of HARQ-ACK, and a shortened PUCCH format can be used (e.g., by processor(s) 51 0).

[0089] In some aspects, a new DCI format introduced herein can be defined to trigger SRS transmission for mutliple UEs on different UL CCs. The new DCI format can contain the UL CC index and SRS configurations. Additionally, in aspects, a new RNTI (Radio Network Temporary Identity, e.g., SRS-RNTI) can be defined for the

transmission of PDCCH, wherein the CRC (Cyclic Redundancy Check) can be scrambled by the SRS-RNTI. In various aspects, this SRS-RNTI can be predefined or can be configured by higher layers via SIB or RRC signaling (e.g., generated by processor(s) 610, transmitted via communication circuitry 620, received via transceiver circuitry 520, and processed by processor(s) 510). In addition, to avoid excessive blind decoding attempts, zero padding can be employed for this new DCI format to match with other DCI format(s).

[0090] In some aspects, cell specific parameter(s) comprising SRS configuration for each CC can be included in the new DCI. Referring to FIG. 9, illustrated is a diagram of an example of SRS configuration for multiple CCs in a new DCI format, according to various aspects discussed herein. In the new DCI format, SRS configuration for N CCs can be included. In the example shown in FIG. 9, a first UE (UE#1 ) can obtain SRS configuration information for CC#0 and CC#2 while a second UE (UE#2) can obtain SRS configuration information for CC#2 and CC#3. [0091] Referring to FIG. 10, illustrated is a flow diagram of an example method 1 000 that facilitates SRS CC-based switching by a UE, according to various aspects discussed herein. In other aspects, a machine readable medium can store instructions associated with method 1 000 that, when executed, can cause a UE to perform the acts of method 1 000.

[0092] At 1010, one or more SRS CCs can be determined from a plurality of configured CCs.

[0093] At 1020, a DCI message can be received triggering SRS transmission.

[0094] At 1030, SRS can be transmitted via at least one of the one or more SRS CCs based on the DCI message.

[0095] Additionally or alternatively, method 1000 can include one or more other acts described herein in connection with system 500.

[0096] Referring to FIG. 11 , illustrated is a flow diagram of an example method 1 100 employable at a BS that facilitates SRS CC-based switching by one or more UEs, according to various aspects discussed herein. In other aspects, a machine readable medium can store instructions associated with method 1 1 00 that, when executed, can cause a BS to perform the acts of method 1 100.

[0097] At 1 1 10, a UE can be configured with a plurality of CCs comprising DL CC(s) and UL CC(s), wherein at least one of the UL CC(s) is a SRS CC.

[0098] At 1 120, a DCI message can be transmitted that comprises a SRS request field triggering SRS transmission by the UE.

[0099] At 1 130, SRS can be received via at least one of the SRS CCs based on the SRS request field.

[00100] Additionally or alternatively, method 1 100 can include one or more other acts described herein in connection with system 600.

[00101 ] Examples herein can include subject matter such as a method, means for performing acts or blocks of the method, at least one machine-readable medium including executable instructions that, when performed by a machine (e.g., a processor with memory, an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like) cause the machine to perform acts of the method or of an apparatus or system for concurrent communication using multiple communication technologies according to embodiments and examples described.

[00102] Example 1 is an apparatus configured to be employed in a User Equipment (UE), comprising: a memory interface; and processing circuitry configured to: determine one or more SRS (Sounding Reference Signal) CCs (Component Carriers) from a plurality of configured CCs that comprises one or more configured DL (Downlink) CCs and one or more configured UL (Uplink) CCs, wherein each SRS CC of the one or more SRS CCs is a configured UL CC of the one or more configured UL CCs that is not configured for a PUSCH (Physical Uplink Shared Channel); decode a first DCI

(Downlink Control Information) message; generate SRS for each of at least one SRS CC of the one or more SRS CCs, based at least in part on the first DCI message; and send one or more identifiers associated with the one or more SRS CCs to a memory via the memory interface.

[00103] Example 2 comprises the subject matter of any variation of any of example(s) 1 , wherein each of the one or more SRS CCs is one of the one or more configured DL CCs.

[00104] Example 3 comprises the subject matter of any variation of any of example(s) 1 , wherein the processing circuitry is further configured to process one or more lEs (Information Elements), wherein each one of the one or more lEs indicates whether to support SRS CC-based switching for an associated CA (Carrier Aggregation) configuration of one or more CA configurations.

[00105] Example 4 comprises the subject matter of any variation of any of example(s) 1 -3, wherein the processing circuitry is configured to generate the SRS for each of the one or more SRS CCs based at least in part on a SRS request field, wherein the SRS request field is one of a 1 -bit field or a 2-bit field.

[00106] Example 5 comprises the subject matter of any variation of any of example(s)

4, wherein the first DCI message comprises the SRS request field.

[00107] Example 6 comprises the subject matter of any variation of any of example(s)

4, wherein the processing circuitry is further configured to process a RAR (Random

Access Response) message that comprises the SRS request field.

[00108] Example 7 comprises the subject matter of any variation of any of example(s)

4, wherein the processing circuitry is further configured to associate each CC of the plurality of CCs with a set of CCs of one or more sets of CCs, wherein the SRS request field indicates a first set of CCs of the one or more sets of CCs, and wherein the at least one SRS CC is associated with the first set of CCs.

[00109] Example 8 comprises the subject matter of any variation of any of example(s) 7, wherein each set of CCs of the one or more sets of CCs comprises at least one UL CC configured for PUSCH.

[001 10] Example 9 comprises the subject matter of any variation of any of example(s) 1 -3, wherein the processing circuitry is further configured to map the SRS for each SRS CC of the at least one SRS CC to a distinct symbol of an UpPTS (Uplink Pilot Time Slot) of a special subframe.

[00111 ] Example 10 comprises the subject matter of any variation of any of example(s) 1 -3, wherein the processing circuitry is configured to determine one or more SRS parameters based on one of RRC (Radio Resource Control) signaling or a second DCI message, wherein the one or more SRS parameters comprise at least one of: a bandwidth, one or more symbol indices, one or more UL antennas, or one or more SRS transmission timings.

[00112] Example 1 1 comprises the subject matter of any variation of any of example(s) 1 -3, wherein the processing circuitry is configured to generate the SRS for each SRS CC of the at least one SRS CC in a first available cell-specific SRS opportunity after a corresponding PUCCH (Physical Uplink Control Channel) subframe for HARQ (Hybrid Automatic Repeat Request)-ACK (Acknowledgement) feedback.

[00113] Example 12 comprises the subject matter of any variation of any of example(s) 1 -3, wherein the processing circuitry is configured to: generate the SRS for each SRS CC of the at least one SRS CC in a subframe for HARQ (Hybrid Automatic Repeat Request)-ACK (Acknowledgement) feedback; and employ a shortened PUCCH (Physical Uplink Control Channel) format for the HARQ-ACK feedback.

[00114] Example 13 comprises the subject matter of any variation of any of example(s) 1 -3, wherein the first DCI message indicates SRS triggering for the UE and at least one additional UE.

[00115] Example 14 comprises the subject matter of any variation of any of example(s) 13, wherein the first DCI message indicates at least a first field to trigger SRS transmission for one or a set of predefined UL CCs without PUCCH and PUSCH transmissions and at least one SRS configuration associated with the at least one SRS CC for the UE, and wherein a CRC of the first DCI message is scrambled by a dedicated RNTI (Radio Network Temporary Identity).

[00116] Example 15 comprises the subject matter of any variation of any of example(s) 14, wherein the first DCI format further comprises one or more additional fields to trigger SRS transmissions for one or more additional UEs, wherein the processing circuitry is configured to determine a starting position of the first field based on higher layer signaling.

[00117] Example 16 comprises the subject matter of any variation of any of example(s) 1 -2, wherein the processing circuitry is further configured to process one or more lEs (Information Elements), wherein each one of the one or more lEs indicates whether to support SRS CC-based switching for an associated CA (Carrier

Aggregation) configuration of one or more CA configurations.

[00118] Example 17 comprises the subject matter of any variation of any of example(s) 4-6, wherein the processing circuitry is further configured to associate each CC of the plurality of CCs with a set of CCs of one or more sets of CCs, wherein the SRS request field indicates a first set of CCs of the one or more sets of CCs, and wherein the at least one SRS CC is associated with the first set of CCs.

[00119] Example 18 comprises the subject matter of any variation of any of example(s) 1 -8, wherein the processing circuitry is further configured to map the SRS for each SRS CC of the at least one SRS CC to a distinct symbol of an UpPTS (Uplink Pilot Time Slot) of a special subframe.

[00120] Example 19 comprises the subject matter of any variation of any of example(s) 1 -9, wherein the processing circuitry is configured to determine one or more SRS parameters based on one of RRC (Radio Resource Control) signaling or a second DCI message, wherein the one or more SRS parameters comprise at least one of: a bandwidth, one or more symbol indices, one or more UL antennas, or one or more SRS transmission timings.

[00121 ] Example 20 comprises the subject matter of any variation of any of example(s) 1 -10, wherein the processing circuitry is configured to generate the SRS for each SRS CC of the at least one SRS CC in a first available cell-specific SRS opportunity after a corresponding PUCCH (Physical Uplink Control Channel) subframe for HARQ (Hybrid Automatic Repeat Request)-ACK (Acknowledgement) feedback.

[00122] Example 21 comprises the subject matter of any variation of any of example(s) 1 -9, wherein the processing circuitry is configured to: generate the SRS for each SRS CC of the at least one SRS CC in a subframe for HARQ (Hybrid Automatic Repeat Request)-ACK (Acknowledgement) feedback; and employ a shortened PUCCH (Physical Uplink Control Channel) format for the HARQ-ACK feedback.

[00123] Example 22 is an apparatus configured to be employed in an Evolved NodeB (eNB), comprising: a memory interface; and processing circuitry configured to: generate signaling that configures a plurality of CCs (Component Carriers) for a UE (User Equipment), wherein the plurality of CCs comprises one or more configured DL

(Downlink) CCs and one or more configured UL (Uplink) CCs that comprise one or more SRS (Sounding Reference Signal) CCs, wherein each SRS CC of the one or more SRS CCs is a configured UL CC of the one or more configured UL CCs that is not configured for a PUSCH (Physical Uplink Shared Channel); generate a first DCI (Downlink Control Information) message comprising an SRS request field that indicates at least one SRS CC of the one or more SRS CCs; process SRS from each SRS CC of the at least one SRS CC; and send one or more identifiers associated with the one or more SRS CCs to a memory via the memory interface.

[00124] Example 23 comprises the subject matter of any variation of any of example(s) 22, wherein each of the one or more SRS CCs is one of the one or more configured DL CCs.

[00125] Example 24 comprises the subject matter of any variation of any of example(s) 22, wherein the SRS request field comprises 1 or 2 bits.

[00126] Example 25 comprises the subject matter of any variation of any of example(s) 22-24, wherein the SRS request field indicates a set of CCs of a plurality of sets of CCs.

[00127] Example 26 comprises the subject matter of any variation of any of example(s) 25, wherein each set of CCs of the plurality of sets of CCs comprises at least one UL CC configured for PUSCH.

[00128] Example 27 comprises the subject matter of any variation of any of example(s) 22-24, wherein the SRS from each SRS CC of the at least one SRS CCs is mapped to a distinct symbol of an UpPTS (Uplink Pilot Time Slot) of a special subframe.

[00129] Example 28 comprises the subject matter of any variation of any of example(s) 22-24, wherein the processing circuitry is further configured to generate one of RRC (Radio Resource Control) signaling indicating one or more SRS parameters or a second DCI message indicating one or more SRS parameters, wherein the one or more SRS parameters comprise at least one of: a bandwidth, one or more symbol indices, one or more UL antennas, or one or more SRS transmission timings.

[00130] Example 29 comprises the subject matter of any variation of any of example(s) 22-24, wherein the SRS from the at least one SRS CCs is scheduled in a first available cell-specific SRS opportunity after a corresponding PUCCH (Physical Uplink Control Channel) subframe for HARQ (Hybrid Automatic Repeat Request)-ACK (Acknowledgement) feedback.

[00131 ] Example 30 comprises the subject matter of any variation of any of example(s) 22-24, wherein the SRS from the at least one SRS CCs is scheduled in a common subframe with HARQ (Hybrid Automatic Repeat Request)-ACK

(Acknowledgement) feedback.

[00132] Example 31 comprises the subject matter of any variation of any of example(s) 22-23, wherein the SRS request field comprises 1 or 2 bits. [00133] Example 32 is a machine readable medium comprising instructions that, when executed, cause a UE (User Equipment) to: determine one or more SRS

(Sounding Reference Signal) CCs (Component Carriers) from a plurality of configured CCs that comprises one or more configured DL (Downlink) CCs and one or more configured UL (Uplink) CCs, wherein each SRS CC of the one or more SRS CCs is a configured UL CC of the one or more configured UL CCs that is not configured for a PUSCH (Physical Uplink Shared Channel); receive a first DCI (Downlink Control Information) message; and transmit SRS via each of at least one SRS CC of the one or more SRS CCs, based at least in part on the first DCI message.

[00134] Example 33 comprises the subject matter of any variation of any of example(s) 32, wherein the instructions, when executed, cause the UE to transmit the SRS for each of the one or more SRS CCs based at least in part on a SRS request field, wherein the SRS request field is one of a 1 -bit field or a 2-bit field.

[00135] Example 34 comprises the subject matter of any variation of any of example(s) 33, wherein the first DCI message comprises the SRS request field.

[00136] Example 35 comprises the subject matter of any variation of any of example(s) 33, wherein the instructions, when executed, further cause the UE to group each CC of the plurality of CCs into a set of CCs of four sets of CCs, wherein the SRS request field indicates a first set of CCs of the four sets of CCs, and wherein the at least one SRS CC is associated with the first set of CCs.

[00137] Example 36 comprises the subject matter of any variation of any of example(s) 32-35, wherein the instructions, when executed, cause the UE to transmit the SRS for each SRS CC of the at least one SRS CC in a first available cell-specific SRS opportunity after a corresponding PUCCH (Physical Uplink Control Channel) subframe for HARQ (Hybrid Automatic Repeat Request)-ACK (Acknowledgement) feedback.

[00138] Example 37 is an apparatus configured to be employed in a User Equipment (UE), comprising: means for determining one or more SRS (Sounding Reference Signal) CCs (Component Carriers) from a plurality of configured CCs that comprises one or more configured DL (Downlink) CCs and one or more configured UL (Uplink) CCs, wherein each SRS CC of the one or more SRS CCs is a configured UL CC of the one or more configured UL CCs that is not configured for a PUSCH (Physical Uplink Shared Channel); means for decoding a first DCI (Downlink Control Information) message; means for generating SRS for each of at least one SRS CC of the one or more SRS CCs, based at least in part on the first DCI message; and means for sending one or more identifiers associated with the one or more SRS CCs to a memory via the memory interface.

[00139] Example 38 comprises the subject matter of any variation of any of example(s) 37, wherein each of the one or more SRS CCs is one of the one or more configured DL CCs.

[00140] Example 39 comprises the subject matter of any variation of any of example(s) 37, further comprising means for processing one or more lEs (Information Elements), wherein each one of the one or more lEs indicates whether to support SRS CC-based switching for an associated CA (Carrier Aggregation) configuration of one or more CA configurations.

[00141 ] Example 40 comprises the subject matter of any variation of any of example(s) 37-39, wherein the means for generating the SRS is configured to generate the SRS for each of the one or more SRS CCs based at least in part on a SRS request field, wherein the SRS request field is one of a 1 -bit field or a 2-bit field.

[00142] Example 41 comprises the subject matter of any variation of any of example(s) 40, wherein the first DCI message comprises the SRS request field.

[00143] Example 42 comprises an apparatus comprising means for executing any of the described operations of examples 1 -31 .

[00144] Example 43 comprises a machine readable medium that stores instructions for execution by a processor to perform any of the described operations of examples 1 - 41 .

[00145] Example 44 comprises an apparatus comprising: a memory interface; and processing circuitry configured to: performing any of the described operations of examples 1 -41 .

[00146] The above description of illustrated embodiments of the subject disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. While specific embodiments and examples are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such embodiments and examples, as those skilled in the relevant art can recognize.

[00147] In this regard, while the disclosed subject matter has been described in connection with various embodiments and corresponding Figures, where applicable, it is to be understood that other similar embodiments can be used or modifications and additions can be made to the described embodiments for performing the same, similar, alternative, or substitute function of the disclosed subject matter without deviating therefrom. Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, but rather should be construed in breadth and scope in accordance with the appended claims below.

[00148] In particular regard to the various functions performed by the above described components or structures (assemblies, devices, circuits, systems, etc.), the terms (including a reference to a "means") used to describe such components are intended to correspond, unless otherwise indicated, to any component or structure which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations. In addition, while a particular feature may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.