Frame structure design for downlink TDD-TDD carrier aggregation in cells without PUSCH

Abstract

Provided are wireless communication systems and methods related to transmitting communication signals on a TDD frequency band of a carrier aggregation (CA) system using a primary carrier component (PCC) and a secondary carrier component (SCC) without a PUSCH cell. Specifically, a CA frame structure having a PCC primary frame and an SCC secondary frame (wherein a sounding reference signal (SRS) transmitted on the SCC secondary frame) corresponds to a downlink time slot on the PCC primary frame to avoid throughput loss. In some embodiments, the CA frame can be arranged so that at least one uplink time slot on the PCC frame corresponds to a downlink time slot on the SCC frame.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to PCT / CN2020 / 087537 filed on April 28, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to wireless communication systems, and more particularly to a communication frame structure for TDD-TDD carrier aggregation. Background Art

[0004] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcast, etc. These systems are capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). A wireless multiple-access communication system may include multiple base stations (BSs), each of which simultaneously supports communication for multiple communication devices, which may also be referred to as user equipment (UE).

[0005] To meet the growing demand for extended mobile broadband connections, wireless communication technology is evolving from LTE technology to next-generation New Radio (NR) technology. For example, NR is designed to provide lower latency, higher bandwidth or throughput, and higher reliability than LTE. NR is designed to operate on a wide array of spectrum bands, for example, from low-frequency bands below about 1 gigahertz (GHz) and mid-frequency bands from about 1 GHz to about 6 GHz, to high-frequency bands such as millimeter wave (mmWave) bands. NR is also designed to operate across different spectrum types, from licensed spectrum to unlicensed and shared spectrum. Spectrum sharing enables operators to have the opportunity to aggregate spectrum to dynamically support high-bandwidth services. Spectrum sharing can extend the benefits of NR technology to operating entities that may not have access to licensed spectrum.

[0006] Aggregating spectrum typically involves aggregating transmissions from various transmission bands, which is known as carrier aggregation (CA). For example, the various bands are specified by uplink and downlink frequencies, duplex modes, and subcarrier spacing (SCS) parameters. It is very important to optimize data delivery for systems that employ CA under various network configurations. Summary of the invention

[0007] The following summarizes some aspects of the present disclosure to provide a basic understanding of the technology discussed. This summary is not an extensive review of all expected features of the present disclosure, and is neither intended to identify key or important elements of all aspects of the present disclosure, nor is it intended to describe the scope of any or all aspects of the present disclosure. Its sole purpose is to present some concepts of one or more aspects of the present disclosure in an overview form as a preface to a more detailed description presented later.

[0008] For example, in one aspect of the present disclosure, a method of operating a user equipment (UE) that communicates with a base station (BS) includes: using a main frame on a first time division duplex (TDD) frequency band of a primary component carrier (PCC) to perform downlink and uplink with the BS, wherein the main frame has a main frame structure including multiple time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; using a secondary frame on a second frequency band of a secondary component carrier (SCC) to perform a downlink with the BS, wherein the second frame has a secondary frame structure including multiple time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; and sending a sounding reference signal (SRS) on the SCC, wherein the main frame and the secondary frame form a carrier aggregation (CA) frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink time slot on the main frame of the PCC.

[0009] A user equipment (UE) device according to some embodiments of the present disclosure includes a processor; a memory coupled to the processor, the memory including data and instructions to be run on the processor; a frame module storing a carrier aggregation (CA) frame structure; a communication module coupled to receive a downlink and send an uplink according to the CA frame structure; a transceiver coupled to the communication module to send and receive according to the CA frame structure; and an antenna coupled to the transceiver to send and receive in a first time division duplex (TDD) frequency band of a primary component carrier (PCC) and in a second TDD frequency band of a secondary carrier component according to the CA frame structure, wherein the processor runs instructions to use the first time division duplex (TDD) frequency band of the primary component carrier (PCC) to transmit and receive uplink signals. A main frame is used to run a downlink and an uplink with a base station (BS), wherein the main frame has a main frame structure including a plurality of time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; a secondary frame on a second frequency band of a secondary component carrier (SCC) is used to perform a downlink with the BS, wherein the second frame has a secondary frame structure including a plurality of time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; and a sounding reference signal (SRS) is sent on the SCC, wherein the main frame and the secondary frame form a carrier aggregation (CA) frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink time slot on the main frame of the PCC.

[0010] In some embodiments according to the present disclosure, a method of operating a base station (BS) for communicating with a user equipment (UE) includes: using a main frame on a first time division duplex (TDD) frequency band of a primary component carrier (PCC) to perform downlink and uplink with the UE, wherein the main frame has a main frame structure including multiple time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; using a secondary frame on a second frequency band of a secondary component carrier (SCC) to perform a downlink with the UE, wherein the second frame has a secondary frame structure including multiple time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; and receiving a sounding reference signal (SRS) on the SCC, wherein the main frame and the secondary frame form a carrier aggregation (CA) frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink time slot on the main frame of the PCC.

[0011] In some embodiments, a base station (BS) according to some embodiments of the present disclosure includes a processor; a memory coupled to the processor, the memory including data and instructions to be run on the processor; a frame module storing a carrier aggregation (CA) frame structure; a communication module coupled to send a downlink and receive an uplink according to the CA frame structure; a transceiver coupled to the communication module to send and receive according to the CA frame structure; and an antenna coupled to the transceiver to send and receive in a first time division duplex (TDD) frequency band of a primary component carrier (PCC) and in a second TDD frequency band of a secondary component carrier according to the CA frame structure, wherein the processor runs instructions to use the first time division duplex (TDD) frequency band of the primary component carrier (PCC) to transmit and receive uplink. D) a main frame on a frequency band to perform downlink and uplink with a user equipment (UE), wherein the main frame has a main frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots and one or more switching time slots, and a secondary frame on a second frequency band using a secondary component carrier (SCC) to perform downlink with the UE, wherein the second frame has a secondary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and a sounding reference signal (SRS) is received on the SCC, wherein the main frame and the secondary frame form a carrier aggregation (CA) frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink time slot on the main frame of the PCC.

[0012] By reading the following description of specific example embodiments of the present disclosure in conjunction with the accompanying drawings, other aspects, features, and embodiments of the present disclosure will become apparent to those of ordinary skill in the art. Although features of the present disclosure may be discussed with respect to certain embodiments and drawings below, all embodiments of the present disclosure may include one or more advantageous features discussed herein. In other words, although one or more embodiments may be discussed as having certain advantageous features, one or more such features may also be used according to the various embodiments of the present disclosure discussed herein. In a similar manner, although example embodiments may be discussed below as device, system, or method embodiments, it should be understood that such example embodiments may be implemented in various devices, systems, and methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A wireless communication network according to some embodiments of the present disclosure is shown.

[0014] Figure 2 is a block diagram of an example user equipment (UE) according to an embodiment of the present disclosure.

[0015] Figure 3 is a block diagram of an example base station (BS) according to an embodiment of the present disclosure.

[0016] Figure 4A and Figure 4B Example frame structures of the currently used N41 and N78 communication frequency bands are shown respectively.

[0017] Figure 5A It is shown that uplink and downlink communications are performed between a UE and a BS using carrier aggregation (CA).

[0018] Figure 5B Communications utilizing CA for uplink and downlink are shown, where one of the frequency bands defines a PUSCH-less cell that cannot be used for uplink data.

[0019] Fig. 6A and Figure 6B It shows that Figure 5B The frame structure shown has CA in PUSCH-free cell communication.

[0020] Fig. 7A , Figure 7B , Figure 7C and Fig.7D An example of defining a frame structure according to some embodiments is shown.

[0021] Fig. 8A , Figure 8B , Figure 8C and Fig.8DA specific example of a frame structure according to some embodiments is shown.

[0022] Fig. 9A and Fig. 9B An example of defining a frame structure according to some embodiments is shown.

[0023] Fig. 10A and Fig. 10B The operations of the UE and the BS are shown respectively. DETAILED DESCRIPTION

[0024] The detailed description set forth below, in conjunction with the accompanying drawings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some cases, in order to avoid confusion with these concepts, well-known structures and components are shown in block diagram form.

[0025] The present disclosure generally relates to wireless communication systems, also referred to as wireless communication networks. In various embodiments, these techniques and devices can be used in wireless communication networks, such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single carrier FDMA (SC-FDMA) networks, LTE networks, GSM networks, fifth generation (5G) or new radio (NR) networks, and other communication networks. As described herein, the terms "network" and "system" can be used interchangeably.

[0026] OFDMA networks can implement radio technologies such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE802.16, IEEE 802.20, flash-OFDM, etc. UTRA, E-UTRA, and Global System for Mobile Communications (GSM) are part of Universal Mobile Telecommunications System (UMTS). In particular, Long Term Evolution (LTE) is a version of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are described in documents provided by an organization named "3rd Generation Partnership Project" (3GPP), and cdma2000 is described in documents provided by an organization named "3rd Generation Partnership Project 2" (3GPP 2). These different radio technologies and standards are known or under development. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between telecommunications association groups to define globally applicable third generation (3G) mobile phone specifications. 3GPP Long Term Evolution (LTE) is a 3GPP project that aims to improve the Universal Mobile Telecommunications System (UMTS) mobile phone standard. 3GPP may define specifications for next generation mobile networks, mobile systems, and mobile devices. The present disclosure relates to the evolution of wireless technology from LTE, 4G, 5G, NR, and sharing access to wireless spectrum between networks using a set of new and different radio access technologies or radio air interfaces.

[0027] Specifically, 5G networks consider different deployments, different spectrums, and different services and devices that can be implemented using a unified air interface based on OFDM. To achieve these goals, in addition to developing new radio technologies for 5G NR networks, further enhancements to LTE and LTE-A are also considered. 5G NR will be able to scale to provide coverage (1) Ultra-high density (e.g., ~1M nodes / km 2 ), ultra-low complexity (e.g., ~ tens of bits / second), ultra-low energy (e.g., ~10+ years of battery life), and deep coverage to reach challenging locations; (2) mission-critical control including strong security to protect sensitive personal, financial, or classified information, ultra-high reliability (e.g., ~99.9999% reliability), ultra-low latency (e.g., ~1 millisecond (ms)), and users with wide-area mobility or lack of mobility; and (3) enhanced mobile broadband, including extremely high capacity (e.g., ~10 Tbps / km 2 ), extremely high data rates (e.g., multi-Gbps rates, 100+Mbps user experience rates), and deep awareness for advanced discovery and optimization.

[0028] 5G NR can be implemented using an optimized OFDM-based waveform with scalable parameter sets and transmission time intervals (TTIs); with a common, flexible framework to efficiently multiplex services and features using dynamic, low-latency time division duplex (TDD) / frequency division duplex (FDD) designs; and advanced wireless technologies such as massive multiple-input multiple-output (MIMO), robust millimeter wave (mmWave) transmission, advanced channel coding, and device-centric mobility. The scalability of parameter sets in 5G NR, as well as the scaling of subcarrier spacing, can effectively solve the problem of operating different services on different spectrums and different deployments. For example, in various outdoor and macro coverage deployments of less than 3GHz FDD / TDD implementations, subcarrier spacing may appear at 15kHz, such as on bandwidths (BW) of 1, 5, 10, 20MHz, etc. For various other outdoor and small cell coverage deployments with TDD greater than 3GHz, subcarrier spacing on 80 / 100MHzBW may appear 30kHz. For various other indoor broadband implementations, using TDD on the unlicensed portion of the 5GHz band, a subcarrier spacing of 60kHz may occur on 160MHz BW. Finally, for various deployments transmitting the mmWave component with 28GHz TDD, a subcarrier spacing of 120kHz may occur on 500MHz BW.

[0029] 5G NR's scalable parameter sets facilitate scalable TTIs for different latency and quality of service (QoS) requirements. For example, shorter TTIs can be used for low latency and high reliability, while longer TTIs can be used for higher spectral efficiency. Efficient multiplexing of long and short TTIs allows transmissions to start on symbol boundaries. 5G NR also considers independent integrated subframe designs with uplink (UL) / downlink (DL) scheduling information, data, and acknowledgments in the same subframe. Independent integrated subframes support communications in unlicensed or contention-based shared spectrum, adaptive UL / DL, which can be flexibly configured on a per-cell basis to dynamically switch between UL and DL time slots to meet current business needs.

[0030] Embodiments of the present disclosure relate to a frame structure primarily for DL ​​between a UE and a BS using time division duplex (TDD) carrier aggregation. In some embodiments, one carrier of the carrier aggregation does not include a data uplink (i.e., no PUSCH). Specifically, the embodiments minimize the carrier switching time associated with a sounding reference signal (SRS) that occurs when a first band switch with SRS and a second band switch coincide, thereby causing a carrier switching retuning process.

[0031] In some embodiments, the CA frame structure includes a first frame in a first frequency band and a second frame in a second frequency band. Each of the first frame and the second frame includes a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots. One of the first frequency band and the second frequency band is a secondary component carrier (SCC), and the other of the first frequency band and the second frequency band is a primary component carrier (PCC). The uplink and downlink are performed in the PCC, so the PCC includes one or more uplink time slots, one or more downlink time slots, and one or more switching time slots. Therefore, the PCC carries control data. In some embodiments, the SCC only supports downlink and only allows uploading of SRS. Therefore, the SCC frame structure also includes downlink time slots, uplink time slots, and switching time slots, wherein the uplink time slot is not used for uplink.

[0032] In some embodiments, if the frame structure of the first frame is known, the frame structure of the second frame is derived by dividing the frame structure of the first frame into a first part and a second part, and forming the second frame by switching the order of the first part and the second part. This causes the SRS signal to coincide with the downlink timeslot in another carrier instead of coinciding with the switching timeslot. Another embodiment that causes the SRS signal in the SCC to coincide with the downlink timeslot is to time-shift the second frame from the first frame so that the SRS signal in the SCC coincides with the downlink timeslot. In a further embodiment, the first frame structure and the second frame structure are arranged so that at least one uplink timeslot in the PCC corresponds to a downlink timeslot in the SCC.

[0033] The various aspects and features of the present disclosure are further described below. It should be clear that the teachings here can be implemented in various forms, and any specific structure, function or both disclosed here are merely representative and non-restrictive. Based on the teachings here, it should be understood by those of ordinary skill in the art that an aspect disclosed here can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement a device or practice a method. In addition, in addition to one or more aspects set forth herein, or different from one or more aspects set forth herein, other structures, functions or structures and functions can be used to implement such a device or practice such a method. For example, a method can be implemented as a part of a system, device, device, and / or implemented as an instruction stored on a computer-readable medium for running on a processor or computer. In addition, an aspect can include at least one element of a claim.

[0034] Figure 1A wireless communication network 100 according to some embodiments of the present disclosure is shown. The network 100 may be a 5G network. The network 100 includes a plurality of base stations (BSs) 105 and other network entities. The BS 105 may be a station that communicates with the UE 115 and may also be referred to as an evolved Node B (eNB), a next generation eNB (gNB), an access point, etc. Each BS 105 may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" may refer to this particular geographic coverage area of ​​the BS 105 and / or a BS subsystem serving the coverage area, depending on the context in which the term is used.

[0035] BS 105 may provide communication coverage for macro cells or small cells (such as pico cells or femto cells) and / or other types of cells. Macro cells typically cover a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access to UEs that have subscribed to services with a network provider. Small cells, such as pico cells, typically cover a relatively small geographic area and may allow unrestricted access to UEs that have subscribed to services with a network provider. Small cells, such as femto cells, also typically cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, may provide restricted access to UEs associated with the femto cells (e.g., UEs in a closed subscriber group (CSG), UEs of users in a home, etc.). The BS for a macro cell may be referred to as a macro BS. The BS for a small cell may be referred to as a small cell BS, a pico BS, a femto BS, or a home BS. In Figure 1 In the example shown, BS 105d and 105e may be conventional macro BSs, while BS 105a-105c may be macro BSs that enable one of three-dimensional (3D), full-dimensional (FD), or massive MIMO. BS 105a-105c may utilize their higher-dimensional MIMO capabilities to utilize 3D beamforming in elevation and azimuth beamforming to increase coverage and capacity. BS 105f may be a small cell BS, which may be a home node or a portable access point. BS 105 may support one or more (e.g., two, three, four, etc.) cells.

[0036] The network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time.

[0037] UE 115 is dispersed throughout the wireless network 100, and each UE 115 can be fixed or mobile. UE 115 may also be referred to as a terminal, a mobile station, a subscriber unit, a station, etc. UE 115 may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, etc. In one aspect, UE 115 may be a device including a universal integrated circuit card (UICC). On the other hand, UE may be a device that does not include a UICC. In some aspects, UE 115 that does not include a UICC may also be referred to as an IoT device or an Internet of Everything (IoE) device. UE 115A-115d is an example of a mobile smart phone type device that accesses the network 100. UE 115 may also be a machine specifically configured for connecting communications, including machine type communications (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT), etc. UE 115e-115k is an example of various machines configured for communications of accessing the network 100. UE 115 is able to communicate with any type of BS, whether macro BS, small cell, etc. Figure 1 , lightning (eg, communication link) indicates wireless transmission between UE 115 and serving BS 105, which is a BS designated to serve UE 115 on DL and / or UL, or desired transmission between BSs, and backhaul transmission between BSs.

[0038] In operation, BS 105a-105c may use 3D beamforming and cooperative spatial techniques such as coordinated multi-point (CoMP) or multi-connectivity to serve UEs 115a and 115b. Macro BS 105d may perform backhaul communications with BS 105a-105c and small cell BS 105f. Macro BS 105d may also transmit multicast services that are subscribed to and received by UEs 115c and 115d. Such multicast services may include mobile TV or streaming video, or may include other services for providing community information, such as weather emergencies or alerts, such as yellow alerts or gray alerts.

[0039] The network 100 may also support mission-critical communications with ultra-reliable and redundant links for mission-critical devices, such as UE 115e, which may be a drone. The redundant communication links with UE 115e may include links from macro BSs 105d and 105e, and links from small cell BS 105f. Other machine-type devices, such as UE 115f (e.g., a thermometer), UE 115g (e.g., a smart meter), and UE 115h (e.g., a wearable device), may communicate directly with BSs, such as small cell BS 105f and macro BS 105e, through the network 100, or in a multi-hop configuration by communicating with another user device that relays its information to the network, such as UE 115f communicating temperature measurement information to a smart meter, UE 115g, which then reports it to the network. The network 100 may also provide additional network efficiency through dynamic, low latency TDD / FDD communications, such as in vehicle-to-vehicle (V2V).

[0040] In some implementations, the network 100 communicates using an OFDM-based waveform. An OFDM-based system can divide the system BW into multiple (K) orthogonal subcarriers, which are also commonly referred to as subcarriers, tones, bins, etc. Each subcarrier can be modulated with data. In some cases, the subcarrier spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system BW. The system BW can also be divided into subbands. In other cases, the subcarrier spacing and / or the duration of the TTI can be scalable.

[0041] Figure 2 is a block diagram of an example UE 200 according to an embodiment of the present disclosure. As described above, UE 200 may be UE 115. As shown, UE 200 may include a processor 202, a memory 204, a frame module 207, a communication module 208, a transceiver 210 including a modem subsystem 212 and a radio frequency (RF) unit 214, and one or more antennas 216. These elements may communicate with each other directly or indirectly (e.g., via one or more buses).

[0042] The processor 202 may include a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 202 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration.

[0043] The memory 204 may include a cache memory (e.g., a cache memory of the processor 202), a random access memory (RAM), a magnetoresistive RAM (MRAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), flash memory, a solid-state storage device, a hard disk drive, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an embodiment, the memory 204 includes a non-transitory computer-readable medium. The memory 204 may store instructions 206. The instructions 206 may include instructions that, when executed by the processor 202, cause the processor 202 to perform the operations described herein with reference to the UE 115 in conjunction with the embodiments of the present disclosure. The instructions 206 may also be referred to as code. The terms "instructions" and "code" should be broadly interpreted to include (a plurality of) any type of computer-readable statement. For example, the terms "instructions" and "code" may refer to one or more programs, routines, subroutines, functions, procedures, etc. "Instructions" and "code" may include a single computer-readable statement or a plurality of computer-readable statements.

[0044] Each of the frame module 207 and the communication module 208 can be implemented via hardware, software, or a combination thereof. For example, each of the frame module 207 and the communication module 202 can be implemented as a processor, circuit, and / or instruction 206 stored in the memory 204 and executed by the processor 202.

[0045] The frame module 207 may be configured to encapsulate uplink (UL) data in a predetermined frame structure, or receive downlink (DL) data. The predetermined frame structure is set to send and receive data through the network 100. The communication module 208 may be configured to send and receive data between the UE 200 and the BS according to the predetermined frame structure. The predetermined frame structure may be a time division duplex (TDD) or frequency division duplex (FDD) structure, and includes time slots for uplink and downlink.

[0046] As shown, the transceiver 210 may include a modem subsystem 212 and an RF unit 214. The transceiver 210 may be configured to communicate bidirectionally with other devices, such as the BS 105 and / or another core network element. The modem subsystem 212 may be configured to modulate and / or encode data from the memory 204 and / or the communication module 208 according to a modulation and coding scheme (MCS), such as a low-density parity check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc., and conform to a predetermined frame structure. The RF unit 214 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) the modulated / encoded data from the modem subsystem 212 (on outbound transmissions) or transmissions originating from another source (e.g., a UE or BS 105). The RF unit 214 may also be configured to perform analog beamforming in conjunction with digital beamforming. Although shown as integrated together in the transceiver 210, the modem subsystem 212 and the RF unit 214 may be separate devices coupled together at the UE 200 to enable the UE 200 to communicate with other devices.

[0047] The RF unit 214 can provide modulated and / or processed data, such as a data packet (or, more generally, a data message that can contain one or more data packets and other information), to the antenna 216 for transmission to one or more other devices. The antenna 216 can also receive data messages sent from other devices. The antenna 216 can provide received data messages for processing and / or demodulation at the transceiver 210. The antenna 216 can include multiple antennas of similar or different designs to maintain multiple transmission links. The RF unit 214 can configure the antenna 216.

[0048] Figure 3 is a block diagram of an example BS 300 according to an embodiment of the present disclosure. As described above, BS 300 may be BS 105. As shown, BS 300 may include a processor 302, a memory 304, a frame module 307, a communication module 308, a transceiver 310 including a modem subsystem 312 and an RF unit 314, and one or more antennas 316. These elements may communicate with each other directly or indirectly (e.g., via one or more buses).

[0049] The processor 302 may have various characteristics as a particular type of processor. For example, these may include a CPU, a DSP, an ASIC, a controller, an FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 302 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in combination with a DSP core, or any other such configuration.

[0050] Memory 304 may include cache memory (e.g., cache memory of processor 302), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solid-state storage devices, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some embodiments, memory 304 may include non-transitory computer-readable media. Memory 304 may store instructions 306. Instructions 306 may include instructions that, when executed by processor 302, cause processor 302 to perform the operations described herein. Instructions 306 may also be referred to as code, which may be broadly interpreted to include (a plurality of) any type of computer-readable statement (as described above with reference to the computer readable medium). Figure 2 discussed).

[0051] Each of the frame module 307 and the communication module 308 can be implemented via hardware, software, or a combination thereof. For example, each of the frame module 307 and the communication module 308 can be implemented as a processor, circuit, and / or instruction 306 stored in the memory 304 and executed by the processor 302.

[0052] The frame module 307 can be configured to prepare or receive data into a predetermined frame structure, or retrieve data according to a predetermined frame structure to send and receive data. The predetermined frame structure can be a time division duplex (TDD) or frequency division duplex (FDD) structure and include time slots for uplink and downlink.

[0053] As shown, the transceiver 310 may include a modem subsystem 312 and an RF unit 314. The transceiver 310 may be configured to communicate bidirectionally with other devices, such as UE 115 and / or another core network element. The modem subsystem 312 may be configured to modulate and / or encode data according to an MCS, such as an LDPC encoding scheme, a turbo encoding scheme, a convolutional encoding scheme, a digital beamforming scheme, etc. The RF unit 314 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc. 2) modulated / encoded data (on outbound transmission) from the modem subsystem 312 or a transmission originating from another source (e.g., UE 115 or another BS). The RF unit 314 may also be configured to perform analog beamforming in conjunction with digital beamforming. Although shown as being integrated together in the transceiver 310, the modem subsystem 312 and / or the RF unit 314 may be separate devices coupled together at the BS 300 to enable the BS 300 to communicate with other devices.

[0054] The RF unit 314 may provide modulated and / or processed data, such as data packets (or, more generally, data messages that may include one or more data packets and other information), to the antenna 316 for transmission to one or more other devices. According to an embodiment of the present disclosure, this may include, for example, transmitting information to complete attachment to a network and communication with a resident UE 115 or 200. The antenna 316 may also receive data messages sent from other devices and provide received data messages for processing and / or demodulation at the transceiver 310. The antenna 316 may include multiple antennas of similar or different designs in order to maintain multiple transmission links.

[0055] In an embodiment, BS 105 may allocate or schedule transmission resources (e.g., in the form of time-frequency resource blocks (RBs)) for DL ​​and UL in network 100. DL refers to the transmission direction from BS 105 to UE 115, while UL refers to the transmission direction from UE 115 to BS 105. The communication may be in the form of a radio frame. A radio frame may be divided into a plurality of subframes or time slots, e.g., 10 time slots per frame. Each time slot may be further divided into small time slots. In FDD mode, simultaneous UL and DL may occur in different frequency bands. For example, each subframe includes a UL subframe in a UL frequency band and a DL subframe in a DL frequency band. In TDD mode, the same frequency band is used, and UL and DL occur in different time periods. For example, a subset of time slots in a radio frame (e.g., DL time slots) may be used for DL, while another subset of time slots in a radio frame (e.g., UL time slots) may be used for UL.

[0056] DL subframes and UL subframes can be further divided into several areas. For example, each DL or UL subframe can have a predefined area for transmitting reference signals, control information and data. Reference signals are predetermined signals that facilitate communication between BS 105 and UE 115. For example, reference signals can have a specific pilot pattern or structure, where pilot frequency modulation can span an operating BW or frequency band, each located at a predefined time and a predefined frequency. For example, BS 105 can send a cell-specific reference signal (CRS) and / or a channel state information-reference signal (CSI-RS) to enable UE 115 to estimate a DL channel. Similarly, UE 115 can send a sounding reference signal (SRS) to enable BS 105 to estimate a UL channel. Control information may include resource allocation and protocol control. Data may include protocol data and / or operational data. In some embodiments, BS 105 and UE 115 can communicate using independent subframes. Independent subframes may include a portion for DL ​​communication and a portion for UL communication. Independent subframes may be DL-centric or UL-centric. A DL-centric subframe may include a longer duration for DL ​​communications than for UL communications. A UL-centric subframe may include a longer duration for UL communications than for DL ​​communications.

[0057] After the connection is established, the UE 115 and the BS 105 may enter a normal operation phase, in which operational data may be exchanged. For example, the BS 105 may schedule the UE 115 for UL and / or DL ​​communications. The BS 105 may send an UL and / or DL ​​scheduling grant to the UE 115 via a physical DL control channel (PDCCH). The BS 105 may send a DL communication signal to the UE 115 via a physical DL shared channel (PDSCH) according to the DL scheduling grant. The UE 115 may send an UL communication signal to the BS 105 via a physical UL shared channel (PUSCH) and / or a physical UL control channel (PUCCH) according to the UL scheduling grant.

[0058] The frame structure of various transmission bands may be defined for communication between the UE 115 and the BS 105. Specifically, the NR standard defines operating bands within a specific frequency range. For example, within the frequency range of 450 MHz–6000 MHz (FR1), NR defines a series of operating bands operating in FDD mode (N1, N2, N3, N4, N7, 8, N12, N20, N25, N28, N70, N71), TDD mode (N34, N38, N39, N40, N41, N51, N77, N78, N79), supplemental downlink mode SDL (N75, N76) or supplemental uplink mode SUL (N80, N81, N82, N83, N84, and N86). In the frequency range of 24250MHz–526500MHz, several TDD mode bands (N257, N258, N260, and N261) are defined. The transmission implementation will define a specific operating band or set of operating bands for communication between the UE 115 and the BS 105. In addition, a specific frame structure is used to provide UL and DL functions for the adopted operating band.

[0059] For example, operating band N41 refers to an operating band with uplink and downlink operating in time division duplex (TDD) mode between 2490MHz and 2690MHz. N41 can have subcarrier spacing (SCS) of 15, 30 and 60kHz. TDDN78 band refers to uplink and downlink operating between 3300MHz and 3800MHz and SCS of 15, 30 and 60kHz. In N79 band, uplink and downlink are both operated between 3300MHz and 3800MHz in TDD mode and SCS of 15, 30 and 60kHz. Other band structures can be used in certain applications. Those skilled in the art will recognize that various definitions of transmission bands can be included according to embodiments of the present disclosure. For example, these bands can be specifically defined for specific applications.

[0060] like Figure 4A and Figure 4B As shown, the TDD frame 402 is formed as a series of time slots 410 having a specific duration T. Each time slot 410 is designated as a downlink time slot (D) 404, an uplink time slot (U) 408, or a switching time slot (S). The BS 105 downloads data to the UE 115 in the downlink time slot 404. The UE 115 uploads data to the BS 105 in the uplink time slot 408. The switching time slot S 408 occurs when switching between the downlink time slot 404 and the uplink time slot 408.

[0061] As a specific example, China Telecom / China Unicom have established the TDD N78 operating band with 30KHz subcarrier spacing (SCS). The N78 operating band is defined as an operating band between 3300MHz and 3800MHz operating in TDD mode, suitable for both UL and DL operations. Figure 4A 4 shows a frame structure 402 specifically operating in the N78 operating band of 3500 MHz (3.5 GHz). Then, the frame 402 includes 10 time slots defining a 2.5 ms double-cycle frame, defined as "DDDSUDDSUU", where "D" represents a downlink time slot, S represents a switching time slot, and U represents an uplink time slot. Figure 4A As shown, the duration T of each time slot defined for a particular application is 0.5 ms, resulting in a half frame (5 time slots) of 2.5 ms duration and a full frame of 5 ms duration.

[0062] As another specific example, China Mobile Communications Corporation (CMCC) uses the TDD N41 band operating at 2600 MHz (2.6 GHz) and 30 kHz SCS, which also results in a frame 402 having 10 slots 410, each with a duration of 0.5 ms. Therefore, a 5 ms single-period DDDDDDSUU frame structure can be defined.

[0063] In order to increase the bandwidth, carrier aggregation can be used. Carrier aggregation refers to combining transmissions in two or more frequency bands. The transmission can be TDD, FDD, or a mixture of both. In carrier aggregation, the primary component carrier (PCC) is supplemented by one or more secondary component carriers (SCC). The distinguishing feature between the PCC and the SCC is that the control signals are processed by the PCC, while the SCC is used to increase the data throughput. Therefore, the PCC and SCC operating in different transmission bands can be used to increase the transmission throughput between the UE 115 and the BS 105. In the present disclosure, although it will be understood by those skilled in the art that multiple SCCs can be used, an aggregation focusing on two TDD transmission bands (one PCC combined with one SCC) is still presented.

[0064] For example, the N41 band can be aggregated with other bands such as the N78 or N79 bands to facilitate carrier aggregation communications between the UE 115 and the BS 105. Other combinations of operating bands may also be aggregated, depending on their compatibility. Although specific band names are discussed as examples in the present disclosure, they should not be considered restrictive. Embodiments of the present disclosure include an aggregation of a first band and a second band. The first band and the second band (one of which is a PCC and the other is an SCC) are TDD bands separated in operating frequency. Those skilled in the art will recognize that aspects of these embodiments may be implemented with a CA configuration having more than one SCC.

[0065] Figure 5A FIG. 5 shows a CA apparatus 500 for transmitting data between a UE 115 and a BS 105. Figure 5A As shown, the PCC 504 at the second frequency is a transmission channel with uplink (UL) and downlink (DL) capabilities. The SCC 502 at the first frequency is also a transmission channel with UL and DL capabilities. As shown, the PCC 504 is at the second frequency, and the SCC 502 is at the first frequency. The first frequency and the second frequency represent two separate frequency bands. In some examples, the first frequency of the SCC 502 may be in a frequency band lower than the second frequency of the PCC 504. However, in some cases, the frequency bands may be switched so that the second frequency of the PCC 504 is in a frequency band lower than the first frequency of the SCC 502. In the present disclosure, the PCC 504 may be referred to as a primary cell or Pcell. In addition, the SCC 502 may be referred to as a secondary cell or Scell.

[0066] Figure 5B A carrier aggregation configuration 510 including a PUSCH-free cell is shown. Figure 5B As shown, UE 115 and BS 105 communicate using PCC 514 and SCC 512. PCC 514 includes UL and DL capabilities. However, SCC 512 only includes DL capabilities, which defines SCC 512 as a PUSCH-free cell. Only sounding reference signal (SRS) switching is performed by TDD SCC 512 PUSCH-free cells.

[0067] In TDD, SRS switching is performed after one or more DL subframes in the frame structure have been completed. The UE 115 asserts the SRS to start carrier tuning of the carrier channel. The SRS itself is used to analyze the channels of the frequency band and can be sent in the switching subframe in the PCC 514 or SCC 512. However, the resulting analysis and carrier tuning process takes some time, possibly several subframes of the frame subframe.

[0068] Fig. 6A and Figure 6B Shown in Figure 5B Various aspects of the frame structure used in the PUSCH-free cell configuration 510 are shown. Fig. 6A As shown, frame structure 600 includes frames 628 and 630. Fig. 6AIn the particular example shown, frame 628 is a TDD N41 band frame on SCC 512. Frame 630 in this example is a TDD N79 frame on PCC 514. Thus, in this example, the higher frequency band (N79) is the primary cell PCC 514, while the lower frequency band (N41) is the secondary cell SCC 512. Thus, PUSCH / PUCCH uplink is not provided on frame 628 that supports only downlink, while PUSCH / PCCH communications are supported on frame 630 that supports both downlink and uplink.

[0069] like Fig. 6A As shown, the ten (10) time slot structure of frame 628 is DDDDDDDSUU, as shown in FIG. Figure 4B Thus, each of time slots 602 is a downlink time slot (in Fig. 6A As shown, the first seven (7) time slots include downlink time slots 602. The last downlink time slot 602 is followed by a switching time slot 604. The last two time slots are blanked UL time slots 606. Blanked UL time slots 606 provide switching time, but no uplink capability. Fig. 6A As further shown in FIG. 6 , carrier switching 632 begins in switching slot 604 and results in a switching gap 608 and the transmission of SRS 610 from UE 115, which occupies a portion of switching slot 604 and a portion of the first blanked uplink slot 606. Switching gap 608 also spans a portion of switching slot 604 and the first blanked uplink slot 606. During this time, the carrier is retuned as described above.

[0070] As mentioned above, in Fig. 6A In the example shown, the primary cell PCC 514 is the N79 band, which has the same Figure 4A The same frame structure and timing as previously discussed for the N78 band are shown. Fig. 6A As shown, the structure of the frame 630 is DDDSUDDSUU. In this case, the frame 630 begins with three (3) downlink time slots 612, in which data can be downloaded from the BS 105 to the UE 115. After the downlink time slots 612, a switching time slot 614 separates the downlink time slots 612 from the uplink time slots 618. In the uplink time slot 618, the UE 115 can upload data to the BS 105. The uplink time slot 618 is followed by two more downlink time slots 620. The second switching time slot 622 is followed by two uplink time slots 626. As shown, an SRS 616 can be sent during the switching time slots 614. The SRS 616 shown does not cause an intermittent time to perform carrier tuning.

[0071] However, the switching slot 622 of the frame 630 in the PCC 514 overlaps with the switching slot 608 of the frame 628 in the SCC 512, where the SRS 610 is transmitted by the UE 115 and forms a carrier switch 632. In the carrier switch 632, the SRS 610 causes a throughput loss indicated by the carrier switch gap 624 in the frame 630. Corresponding to the SRS 610, the switching gap 624 occurs during the first uplink time slot 626 and causes a loss of uplink capability. Specifically, the switching gap 624 can be from 100 to 140 μs, during which carrier tuning can be completed according to the typical capabilities of the UE 115. The switching gap 624 causes the lost transmission of multiple (e.g., about 5) symbols that cannot be scheduled for PUSCH / PUCCH immediately after the SRS switch 610 in the switching time slot 604.

[0072] Figure 6B Another example frame structure 640 is shown. The frame structure 640 includes a frame 642 of the TDD N79 frequency band on the secondary cell SCC 512 and a frame 644 of the TDD N41 frequency band on the primary cell PCC 514. Therefore, in this example, the low frequency band (N41) is the primary cell and the high frequency band (N79) is the secondary cell. For clarity, Figure 6B Frame structure 642 is shown as two concatenated frames of ten (10) time slots, frames 642-A and 642-B. For clarity, Figure 6B Frame structure 644 is also shown as two concatenated frames of ten (10) time slots, frames 644-A and 644-B.

[0073] like Figure 6B As shown, frame 642 is formed by concatenated frames 642-A and 642-B. Each of frames 642-A and 642-B has ten (10) time slots, including seven (7) downlink time slots 646, followed by a switching time slot 648 and two blanking uplink time slots 654. As shown, the switching time slot 648 in frame 642-A includes a gap 650 and an SRS 652 (DDDDDDDSUU). The switching time slot 648 in frame 642-B does not include an SRS.

[0074] As further shown, frame 644 is formed by concatenated frames 644-A and 644-B. Each of frames 644-A and 644-B has 10 time slots, including seven (7) downlink time slots 656, one switching time slot 658, and two uplink time slots 662 (DDDDDDDSUU). As shown, the switching time slot 658 of frame 644-A is aligned with the switching time slot 648 of frame 642-A including gap 650 and SRS 652. Therefore, in the carrier switch 666, the switching gap 660 is formed in the first uplink time slot 660 after the switching time slot 658, resulting in a transmission loss of between 100 and 140 μs. Therefore, as described above, a plurality of symbols (e.g., approximately 5) cannot be scheduled for PUSCH / PUCCH immediately following the SRS switch 652. As Figure 6B As further shown in FIG. 6 , SRS 664 may be sent in switching time slot 658 in frame 644-B. However, SRS 664 does not result in a noticeable throughput loss.

[0075] By providing a frame structure in which the SRS on the SCC 512 does not overlap with the switching time slot on the PCC 514, the Fig. 6A Carrier switching 632 and Figure 6B 514. As described in further detail below, this arrangement may occur in several ways. In one embodiment, the frame structure on the SCC 512 and the frame structure on the PCC 514 may be arranged to prevent the SRS on the SCC 512 from overlapping the switching time slots on the PCC 514. In a second embodiment, a time delay may be introduced between the frame structure on the SCC 512 and the frame structure on the PCC 514. In the second embodiment, the time delay is arranged so that the frame structure is time shifted, but the time slots remain aligned.

[0076] In a further embodiment according to the present disclosure, the frame structure on the SCC 512 and the frame structure on the PCC 514 are arranged so that the uplink timeslot in the PCC 514 is aligned with the downlink timeslot in the SCC 512. This arrangement prevents collisions between uplink timeslots on carriers of carrier aggregation.

[0077] Fig. 7A FIG. 7 shows a CA frame structure 700 for a PUSCH-free cell arrangement for TDD-TDD carrier aggregation for data transmission between a UE 115 and a BS 105 according to some embodiments. Fig. 7A As shown, the CA frame structure 700 is a carrier aggregation frame 702 operating in a first frequency band and a frame 704 operating in a second frequency band. Fig. 7AAs shown, the frame 702 is formed by N+1 consecutive time slots 706, each time slot having a duration T, labeled S0 to SN. In many applications, N+1 is ten (10) time slots. As described above, the time slots 706 include time slots designated as downlink time slots (D), uplink time slots (U), and switching time slots (S). The switching time slot may include one or more SRS signals.

[0078] The frame structure of frame 704 is derived from the frame structure of frame 702. Fig. 7A As shown, frame 702 is divided into a first portion 708 and a second portion 710. The first portion 708 includes time slots S0 to S10. n-1 , and the second portion 710 includes time slots S n To S N As mentioned above, N+1 is the total number of time slots in a frame. The parameter n can be a value from 1 to N-1. The frame 704 is then defined by switching the first portion 708 with the second portion 710 so that the order of the time slots 706 becomes S n To S N , then S0 to S n-1 .

[0079] Figure 7B An example frame structure 700 is shown where n is (N+1) / 2. The specific example shown is where N+1 is 10, such that n=5, and the first portion 708 includes time slots SO to S4, and the second portion 710 includes time slots S5 to S9. Figure 7B An example is shown in which the frame structure of frame 702 is split into two halves, and the two halves are switched to form the frame structure of frame 704 .

[0080] Figure 7C Another example frame structure formed according to some embodiments is shown. Figure 7C As shown, N+1 is ten (10), resulting in a frame 702 having 10 time slots 706. In this particular example, N is N-2, or seven (7). Thus, the first portion 708 includes time slots S0 through S6, while the second portion 710 includes time slots S7 through S9. Thus, the frame 704 derived from the frame 702 formed by switching the first portion 708 with the second portion 710 is, in sequence, time slots S7 through S9, followed by time slots S0 through S6. In some embodiments, the division of the time slots into the first portion 708 and the second portion 710 is arranged such that the resulting CA frame structure 700 includes non-overlapping carrier switching time slots to avoid sending SRS in the SCC that conflict with switching time slots in the PCC. Furthermore, the division of the time slots into the first portion 708 and the second portion 710 can be arranged such that the resulting CA frame structure 700 aligns uplink time slots in the PCC with downlink time slots in the SCC to avoid conflicts between uplink time slots.

[0081] Fig.7D A process 730 for forming the frame structure 700 is shown. Fig.7D As shown, a first frequency band frame 702 is provided. It should be noted that at this point, the first frequency band 702 can be associated with the SCC 512 or the PCC 514 without loss of generality. In step 734, the frame structure 702 is divided into a first part and a second part. In some cases, the first part and the second part can have the same number of time slots, or they can have different numbers of time slots. Each of the first part and the second part includes at least one time slot. In step 736, the frame structure of the frame 704 in frequency band 2 is defined by switching the order of the first part and the second part. In step 738, it can be confirmed that the switching time slot with SRS on the frequency band associated with the SCC 512 does not overlap with the switching time slot on the frequency band associated with the PCC 514. In some cases, if this condition is not met, the process can return from step 738 to step 734.

[0082] In some embodiments, in step 740, it may be confirmed that the uplink timeslots in the PCC are aligned with the downlink timeslots in the SCC. Again, if this condition is not met, the process 730 may return to step 734 to redefine the partitioning of the first portion and the second portion. Once the frame structure 700 is set, the process 730 proceeds to step 742, where the CA frame structure 700 may be used for communication between the UE 115 and the BS 105.

[0083] FIG. 8A to FIG. 8D Some specific examples of CA frame structures defined according to the present disclosure are shown. Fig. 8A A CA frame structure 800 is shown as defined in accordance with some embodiments. The CA frame structure 800 includes a frame 802 having a frame structure DDSUUDDDDD. Thus, the frame structure 802 includes two downlink time slots 810 followed by a switching time slot 812 having an SRS 818. The switching time slot 812 is followed by two uplink time slots 814 and five downlink time slots 810. Fig. 8A In the example of FIG. 8 , frame 802 is associated with frequency band 1 in SCC 512, so that uplink time slot 814 is a blanked uplink time slot. As shown, frame 802 is evenly divided into a first portion 806 including the first half of the time slots and a second portion 808 including the other half of the time slots. Therefore, the frame structure of frame 804 formed by switching first portion 806 and second portion 808 is DDDDDDDSUU. In this example, because frame 804 is associated with PCC 514, uplink time slot 816 can carry data. As shown in FIG. Fig. 8AAs shown, the switching time slot 812 and SRS 818 are now aligned with the downlink time slot 810. In addition, the uplink time slot 816 in frame 804 is aligned with the downlink time slot 810 in frame 802.

[0084] Figure 8B Another example CA frame structure 820 is shown. Frame structure 820 includes frame 822, which in the example shown is DDDSUDDDDD. In other words, frame 822 includes three downlink time slots 810, followed by a switching time slot 812 with SRS 818, followed by an uplink time slot 814 and five downlink time slots 810. As shown, the frame structure of frame 822 is separated into two equal parts, where a first part 826 includes the first five time slots DDDSU and a second part 828 includes the last five time slots DDDDD. Then, frame 824 is derived by switching the first part 826 and the second part 828, resulting in the frame structure of frame 824 being DDDDDDDDSU. As shown in FIG. Figure 8B As shown in the example of , one of the frames 822 or 824 is associated with the SCC 512, while the other is associated with the PCC 514. If the frame 822 is associated with the SCC 512, the uplink time slot 814 is a blanked uplink time slot, while the uplink time slot 816 can carry data. As shown, the switching time slot 812 with the SRS 818 is aligned with the downlink time slot 810 in the frame 824, and the uplink time slot 816 in the frame 824 is aligned with the downlink time slot 810 in the frame 822.

[0085] Figure 8C Another example CA frame structure 830 is shown. In this example, the frame structure 830 includes a frame 832 associated with the TDD N41 frequency band designated as SCC 512, and a frame 834 associated with the TDD N79 frequency band designated as PCC 514. As shown, the frame structure of frame 832 is DDDDDDDSUU. Figure 8CAs shown, frame 832 includes seven downlink time slots 810, followed by a switching time slot 812 and two blanking uplink time slots 814. The switching time slot 812 includes an SRS 818. As shown, the frame structure is evenly divided between a first portion 836 including the first five downlink time slots 810 and a second portion 838 including the remaining time slots DDSUU. Then, frame 834 is derived by switching the first portion 836 with the second portion 838 to form a frame structure DDSUUDDDDD. The uplink time slot 816 in frame 834 can be used to send data. As shown, the switching time slot 812 is not aligned with another switching time slot, so that the SRS 818 in frame 832 is not sent during the switching time slot in frame 834. In addition, the uplink time slot 816 in frame 834 is arranged to align with the downlink time slot in frame 830 to avoid conflicts between uplink time slots.

[0086] Fig.8D Another specific example CA frame structure 840 is shown. Frame structure 840 includes frames 842 and 844. Figure 8C As shown, in contrast, frame 842 is used for the TDD N79 band as SCC 512, while frame 844 is used for the TDD N41 band as PCC 514. Thus, the frame structure of frame 842 is DDSUUDDDDD, where the first two time slots are downlink time slots 810, followed by a switching time slot 812 with SRS 818, followed by two blanked uplink time slots 816 and five downlink time slots 810. As shown, the frame structure is evenly divided such that a first portion 846 includes the first five time slots DDSUU, and a second portion 848 includes five downlink time slots DDDDD. The frame structure of frame 844 is then derived from the frame structure of frame 842 by switching the first portion 846 with the second portion 848. In this case, the frame structure of frame 844 is DDDDDDDSUU, where the uplink time slot 814 can now carry data. As shown, frames 842 and 844 are arranged so that the switching time slot 812 having the SRS 818 is not aligned with another switching time slot. In addition, the uplink time slot 814 in frame 844 is arranged to align with the downlink time slot 810 of frame 842.

[0087] FIG. 8A to FIG. 8DA specific example of deriving a CA frame structure from a first frame in a first frequency band is shown. In particular, a second frame in a second frequency band is derived from the frame structure of the first frequency band. The first frequency band may be associated with an SCC 512, or may be associated with a PCC 514. In many cases, the derivation includes dividing the frame structure of the first frame into a first part and a second part, and defining the frame structure of the second frequency band by switching the first part and the second part of the first frequency band. As described above, the resulting CA frame structure is arranged so that the switching time slot in the SCC is not aligned with the switching time slot in the PCC. In addition, in some embodiments, it is arranged so that the uplink time slot in the PCC frame is aligned with the downlink time slot in the SCC frame.

[0088] Fig. 9A and Fig. 9B Another embodiment of constructing a frame structure for a CA frame according to the present disclosure is shown. FIG. 7A to FIG. 7D and FIG. 8A to FIG. 8D In the illustrated embodiment, the separation between the switching time slot with SRS on SCC 512 and the switching time slot on PCC 514 is achieved by deriving the frame structure of one frame from the frame structure of the other frame. However, this separation can also be achieved by providing a separation delay between the second frame and the first frame.

[0089] Fig. 9A A CA frame structure 900 is shown, including a frame 902 of frequency band 1 and a frame 904 of frequency band 904. One of frequency band 1 or frequency band 2 is associated with SCC 512, while the other is associated with PCC 514. The frame structure of frame 902 and the frame structure of frame 904 may be different. Frame 902 includes N+1 time slots 906, Fig. 9A Frame 904 also includes N+1 time slots 908, also labeled S0 to SN. Fig. 9A As shown, each of time slots 906 and 908 has a duration T. For example, N+1 may be 10, and T may be 0.5 ms. Fig. 9A As shown, frame 904 is time-shifted by an integer multiple of time T (nT) so that frame 904 is shifted relative to frame 902.

[0090] Fig. 9B An example of a CA frame structure 920 according to some embodiments is shown. Fig. 9B As shown, CA frame structure 920 includes frame 922 in band 1, which may be SCC 512 or PCC 514. CA frame structure 920 also includes one of the illustrated frames (frames 924, 926, 928, 930, or 932) in band 2. Note that these are just example frame combinations, and any combination of available frames may be used.

[0091] In such Fig. 9BIn the particular embodiment shown, frame 922 is a DDDDDDDSUU, where the switching time slot 934 includes SRS 936. In one example, CA frame structure 920 includes frame 922 combined with frame 924. Frame 924 has the same structure as frame 922, DDDDDDDSUU, shifted in time by 1T. Therefore, SRS 936 is aligned with downlink time slot 938 and does not cause a throughput delay gap as described above. In addition, at least one uplink time slot in frame 924 is aligned with a downlink time slot of frame 922 (another uplink time slot is aligned with an unused uplink time slot of frame 922).

[0092] In such Fig. 9B In another example shown, CA frame structure 920 includes frame 922 aggregated with band 2 frame 926. Frame 926 has the same structure as frame 922, DDDDDDSUU, shifted in time by 2T. Therefore, SRS 936 is aligned with downlink time slot 940 and does not cause a throughput delay gap as described above. In addition, both uplink time slots shown in frame 926 are aligned with the downlink time slot of frame 922.

[0093] In such Fig. 9B In another example shown, CA frame structure 920 includes frame 922 aggregated with band 2 frame 928. Frame 928 has the same structure as frame 922, DDDDDDDSUU, shifted in time by 5T. Therefore, SRS 936 is aligned with downlink time slot 942 of frame 928 and does not cause throughput delay gaps as described above. In addition, the uplink time slots in frame 928 are aligned with the downlink time slots in frame 922.

[0094] In such Fig. 9B In another example shown, CA frame structure 920 includes frame 922 aggregated with band 2 frame 930. In this example, frame 930 has a different structure than frame 922, DDDSUDDSUU. As shown, frame 930 is shifted by 2T from frame 922 so that SRS 936 is aligned with downlink timeslot 946 instead of a switching timeslot. Therefore, as described above, SRS 936 does not cause transmission delays. In addition, the uplink timeslots in frame 930 are aligned with the downlink timeslots in frame 922.

[0095] In such Fig. 9BIn another example shown, CA frame structure 920 includes frame 922 aggregated with band 2 frame 932. Frame 932 is a different structure from frame 922DDDSUDDSUU. As shown, frame 932 is shifted by T from frame 922, which causes SRS 936 to coincide with downlink time slot 948 and thus does not cause transmission delay. In addition, the uplink time slot in frame 932 is aligned with the downlink time slot in frame 922.

[0096] exist Fig. 9A and Fig. 9B In the illustrated embodiment, in a carrier aggregation system, a frame structure of one frequency band is defined. Then an offset is determined based on the frame structure in another frequency band so that the SRS symbol in the SCC frequency band is aligned with the DL time slot in the PCC frequency band. In addition, in these examples, at least one uplink time slot and generally all uplink time slots in the PCC frequency band are aligned with the downlink time slots in the SCC frequency band.

[0097] Fig. 10A and Fig. 10B The operations of UE and BS are shown respectively. Fig. 10A As shown, according to some embodiments, operations 1000 of a UE communicating with a BS. Fig. 10A As shown, in step 1002, the UE performs downlink and uplink using a PCC frame of a CA frame, the PCC frame including multiple time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots. In step 1004, the UE performs downlink using an SCC frame, the SCC frame including multiple time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots. Then, in step 1006, the UE sends an SRS on the SCC of the CA frame. The CA frame aligns the SRS on the SCC frame with the downlink time slot on the PCC frame. In some embodiments, the CA frame is also arranged so that the uplink time slot in the PCC frame is aligned with the downlink time slot in the SCC.

[0098] like Fig. 10B As shown, according to some embodiments, the BS performs operation 1010 of communicating with the UE. Fig. 10BAs shown, in step 1012, the BS performs downlink and uplink using a PCC frame of a CA frame, the PCC frame including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots. In step 1014, the BS performs downlink using an SCC frame, the SCC frame including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots. Then, in step 1016, the BS receives an SRS on the SCC of the CA frame. The CA frame aligns the SRS on the SCC frame with the downlink time slot on the PCC frame. In some embodiments, the CA frame is also arranged so that the uplink time slot in the PCC frame is aligned with the downlink time slot in the SCC.

[0099] Therefore, in some aspects, a UE is presented that performs uplink and downlink with a BS using a PCC frame of a CA frame, the PCC frame including one or more uplink time slots, one or more downlink time slots, and one or more switching time slots. The UE performs downlink using an SCC frame of a CA frame, the SCC frame including one or more uplink time slots, one or more downlink time slots, and one or more switching time slots. The UE sends an SRS within the SCC frame. In some aspects, the CA frame is arranged so that the SRS on the SCC is aligned with the downlink time slot on the PCC frame. In some aspects, the CA frame is arranged so that the uplink time slot on the PCC frame is aligned with the downlink time slot on the SCC frame.

[0100] In addition, in some aspects, a BS is presented that performs uplink and downlink with a UE using a PCC frame of a CA frame, the PCC frame including one or more uplink time slots, one or more downlink time slots, and one or more switching time slots. The BS performs downlink using an SCC frame of a CA frame, the SCC frame including one or more uplink time slots, one or more downlink time slots, and one or more switching time slots. The BS receives an SRS within the SCC frame. In some aspects, the CA frame is arranged so that the SRS on the SCC is aligned with the downlink time slot on the PCC frame. In some aspects, the CA frame is arranged so that the uplink time slot on the PCC frame is aligned with the downlink time slot on the SCC frame.

[0101] Aspects of the present disclosure include the following:

[0102] Aspect 1 includes a method of operating a user equipment (UE) communicating with a base station (BS), comprising: using a primary frame on a first time division duplex (TDD) frequency band of a primary component carrier (PCC) to perform downlink and uplink with the BS, wherein the primary frame has a primary frame structure including a plurality of time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; using a secondary frame on a second frequency band of a secondary component carrier (SCC) to perform downlink with the BS, wherein the second frame has a secondary frame structure including a plurality of time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; and sending a sounding reference signal (SRS) on the SCC, wherein the primary frame and the secondary frame form a carrier aggregation (CA) frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink time slot on the primary frame of the PCC.

[0103] Aspect 2 includes the method of aspect 1, wherein the primary frame and the secondary frame are configured such that an uplink time slot of the primary frame is aligned with a downlink time slot of the secondary frame.

[0104] Aspect 3 includes the method of aspects 1-2, wherein the CA frame structure is determined by dividing a plurality of time slots of the main frame structure into a first part and a second part; and the second frame structure is derived by switching the order of the first part and the second part.

[0105] Aspect 4 includes the method of aspects 1-2, wherein the CA frame structure is determined by dividing a plurality of time slots of the secondary frame structure into a first part and a second part; and the primary frame structure is derived by switching the order of the first part and the second part.

[0106] Aspect 5 includes the method of aspects 1-4, wherein the TDD frequency bands of the PCC and the SCC are the N41 frequency band and the N79 frequency band.

[0107] Aspect 6 includes the method of aspects 1-5, wherein the CA frame structure is determined by time-shifting the primary frame from the secondary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots of the primary frame and the secondary frame.

[0108] Aspect 7 includes the method of aspects 1-5, wherein the CA frame structure is determined by time-shifting the secondary frame from the primary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots in the primary frame and the secondary frame.

[0109] Aspect 8 includes a user equipment (UE) device, comprising: a processor; a memory coupled to the processor, the memory including data and instructions to be run on the processor; a frame module storing a carrier aggregation (CA) frame structure; a communication module coupled to receive a downlink and send an uplink according to the CA frame structure; a transceiver coupled to the communication module to send and receive according to the CA frame structure; and an antenna coupled to the transceiver to send and receive in a first time division duplex (TDD) frequency band of a primary component carrier (PCC) and in a second TDD frequency band of a secondary component carrier according to the CA frame structure, wherein the processor runs the instructions to use the primary component carrier (PCC) on the first time division duplex (TDD) frequency band A frame is used to perform downlink and uplink with a base station (BS), wherein the main frame has a main frame structure including a plurality of time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; a secondary frame on a second frequency band of a secondary component carrier (SCC) is used to perform downlink with the BS, wherein the second frame has a secondary frame structure including a plurality of time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; and a sounding reference signal (SRS) is sent on the SCC, wherein the main frame and the secondary frame form a carrier aggregation (CA) frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink time slot on the main frame of the PCC.

[0110] Aspect 9 includes the UE apparatus of aspect 8, wherein the primary frame and the secondary frame are configured such that an uplink time slot of the primary frame is aligned with a downlink time slot of the secondary frame.

[0111] Aspect 10 includes the UE apparatus of aspects 8-9, wherein the CA frame structure is determined by dividing a plurality of time slots of the main frame structure into a first part and a second part; and the second frame structure is derived by switching the order of the first part and the second part.

[0112] Aspect 11 includes the UE apparatus of aspects 8-9, wherein the CA frame structure is determined by dividing a plurality of time slots of the secondary frame structure into a first part and a second part; and the primary frame structure is derived by switching the order of the first part and the second part.

[0113] Aspect 12 includes the UE device of aspects 8-11, wherein the TDD frequency bands of the PCC and the SCC are the N41 frequency band and the N79 frequency band.

[0114] • Aspect 13 includes the UE apparatus of aspects 8-12, wherein the CA frame structure is determined by time-shifting the primary frame from the secondary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots of the primary frame and the secondary frame.

[0115] • Aspect 14 includes the UE apparatus of aspects 8-12, wherein the CA frame structure is determined by time-shifting the secondary frame from the primary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots in the primary frame and the secondary frame.

[0116] Aspect 15 includes a method of operating a base station (BS) for communicating with a user equipment (UE), comprising: using a primary frame on a first time division duplex (TDD) frequency band of a primary component carrier (PCC) to perform downlink and uplink with the UE, wherein the primary frame has a primary frame structure including a plurality of time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; using a secondary frame on a second frequency band of a secondary component carrier (SCC) to perform a downlink with the UE, wherein the second frame has a secondary frame structure including a plurality of time slots having one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; and receiving a sounding reference signal (SRS) on the SCC, wherein the primary frame and the secondary frame form a carrier aggregation (CA) frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink time slot on the primary frame of the PCC.

[0117] • Aspect 16 includes the method of aspect 15, wherein the primary frame and the secondary frame are further configured such that an uplink time slot of the primary frame is aligned with a downlink time slot of the secondary frame.

[0118] Aspect 17 includes the method of aspects 15-16, wherein the CA frame structure is determined by dividing a plurality of time slots of the main frame structure into a first part and a second part; and the second frame structure is derived by switching the order of the first part and the second part.

[0119] Aspect 18 includes the method of aspects 15-16, wherein the CA frame structure is determined by dividing a plurality of time slots of the secondary frame structure into a first part and a second part; and the primary frame structure is derived by switching the order of the first part and the second part.

[0120] Aspect 19 includes the method of aspects 15-18, wherein the TDD frequency bands of the PCC and the SCC are the N41 frequency band and the N79 frequency band.

[0121] Aspect 20 includes the method of aspects 15-19, wherein the CA frame structure is determined by time-shifting the primary frame from the secondary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots of the primary frame and the secondary frame.

[0122] Aspect 21 includes the method of aspects 15-19, wherein the CA frame structure is determined by time-shifting the secondary frame from the primary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots in the primary frame and the secondary frame.

[0123] Aspect 22 includes a base station (BS), comprising: a processor; a memory coupled to the processor, the memory including data and instructions to be run on the processor; a frame module storing a carrier aggregation (CA) frame structure; a communication module coupled to transmit a downlink and receive an uplink according to the CA frame structure; a transceiver coupled to the communication module to transmit and receive according to the CA frame structure; and an antenna coupled to the transceiver to transmit and receive in a first time division duplex (TDD) frequency band of a primary component carrier (PCC) and in a second TDD frequency band of a secondary component carrier according to the CA frame structure, wherein the processor runs the instructions to use the primary frame on the first time division duplex (TDD) frequency band of the primary component carrier (PCC) to transmit and receive uplink. to perform downlink and uplink with a user equipment (UE), wherein a main frame has a main frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; to perform a downlink with the UE using a secondary frame on a second frequency band of a secondary component carrier (SCC), wherein the second frame has a secondary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; and to receive a sounding reference signal (SRS) on the SCC, wherein the main frame and the secondary frame form a carrier aggregation (CA) frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink time slot on the main frame of the PCC.

[0124] Aspect 23 includes the BS of Aspect 22, wherein the primary frame and the secondary frame are further configured such that an uplink time slot of the primary frame is aligned with a downlink time slot of the secondary frame.

[0125] Aspect 24 includes the BS of aspects 22-23, wherein the CA frame structure is determined by dividing a plurality of time slots of the primary frame structure into a first part and a second part; and the second frame structure is derived by switching the order of the first part and the second part.

[0126] Aspect 25 includes the BS of aspects 22-23, wherein the CA frame structure is determined by dividing a plurality of time slots of the secondary frame structure into a first part and a second part; and the primary frame structure is derived by switching the order of the first part and the second part.

[0127] Aspect 26 includes the BS of aspects 22-25, wherein the TDD frequency bands of the PCC and the SCC are the N41 frequency band and the N79 frequency band.

[0128] • Aspect 27 includes the BS of aspects 22-26, wherein the CA frame structure is determined by time offsetting the primary frame from the secondary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots of the primary frame and the secondary frame.

[0129] • Aspect 28 includes the BS of aspects 22-26, wherein the CA frame structure is determined by time offsetting the secondary frame from the primary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots in the primary frame and the secondary frame.

[0130] Information and signals may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0131] The various illustrative blocks and modules described in conjunction with the disclosure herein may be designed to be implemented or executed using a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration).

[0132] The functions described herein can be implemented in hardware, software run by a processor, firmware, or any combination thereof. If implemented in software run by a processor, these functions can be stored or sent as one or more instructions or codes on a computer-readable medium. Other examples and implementations are within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the above functions can be implemented using software run by a processor, hardware, firmware, hard wiring, or any combination of these. The features that implement the functions can also be physically located in various locations, including being distributed so that some functions are implemented in different physical locations. In addition, as used herein (including in the claims), "or" used in a list of items (e.g., a list of items starting with a phrase such as "at least one" or "one or more") represents a list of inclusions, so that, for example: a list of [at least one of A, B, or C] represents A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

[0133] As those skilled in the art will now appreciate, and depending on the particular application at hand, many modifications, substitutions and changes may be made to the materials, devices, configurations and methods of use of the apparatus of the present disclosure without departing from the spirit and scope of the present disclosure. In view of this, the scope of the present disclosure should not be limited to the scope of the specific embodiments shown and described herein, as they are merely some examples thereof, but should be fully commensurate with the scope of the appended claims and their functional equivalents.

Claims

1. A method of operating a user equipment (UE) in communication with a network entity, comprising: performing downlink and uplink with a network entity using a primary frame on a first time division duplex TDD frequency band of a primary component carrier PCC, wherein the primary frame has a primary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; performing a downlink with a network entity using a secondary frame on a second frequency band of a secondary component carrier SCC, wherein the secondary frame has a secondary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; as well as A sounding reference signal SRS is sent on the SCC. The primary frame and the secondary frame form a carrier aggregation CA frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink timeslot on the primary frame of the PCC.

2. The method for operating a UE according to claim 1, wherein the primary frame and the secondary frame are configured such that an uplink time slot of the primary frame is aligned with a downlink time slot of the secondary frame.

3. The method for operating a UE according to claim 2, wherein the CA frame structure is determined by: dividing the plurality of time slots of the main frame structure into a first part and a second part; and The secondary frame structure is derived by switching the order of the first part and the second part.

4. The method for operating a UE according to claim 2, wherein the CA frame structure is determined by: dividing the plurality of time slots of the subframe structure into a first portion and a second portion; and The main frame structure is derived by switching the order of the first part and the second part.

5. The method for operating a UE according to claim 2, wherein the TDD frequency bands of the PCC and the SCC are N41 frequency band and N79 frequency band.

6. The method of operating a UE according to claim 2, wherein the CA frame structure is determined by time-shifting the primary frame from the secondary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots of the primary frame and the secondary frame.

7. The method for operating a UE according to claim 2, wherein: The CA frame structure is determined by time-shifting the secondary frame from the primary frame by an integer number of durations T, which is the duration of each of the plurality of time slots in the primary and secondary frames.

8. A user equipment UE device, comprising: processor; a memory, coupled to the processor, the memory comprising data and instructions to be executed on the processor; Frame module, storing carrier aggregation CA frame structure; a communication module coupled to receive a downlink and send an uplink according to a CA frame structure; a transceiver coupled to the communication module to transmit and receive according to the CA frame structure; as well as an antenna coupled to the transceiver to transmit and receive in a first time division duplex TDD frequency band of a primary component carrier PCC and in a second TDD frequency band of a secondary component carrier according to a CA frame structure, The processor executes instructions to performing downlink and uplink with a network entity using a primary frame on a first time division duplex TDD frequency band of a primary component carrier PCC, wherein the primary frame has a primary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; performing a downlink with a network entity using a secondary frame on a second frequency band of a secondary component carrier SCC, wherein the secondary frame has a secondary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; as well as A sounding reference signal SRS is sent on the SCC. The primary frame and the secondary frame form a carrier aggregation CA frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink timeslot on the primary frame of the PCC.

9. The UE device of claim 8, wherein the primary frame and the secondary frame are configured such that an uplink time slot of the primary frame is aligned with a downlink time slot of the secondary frame.

10. The UE device according to claim 9, wherein the CA frame structure is determined by: dividing the plurality of time slots of the main frame structure into a first part and a second part; and The secondary frame structure is derived by switching the order of the first part and the second part.

11. The UE device according to claim 9, wherein: The CA frame structure is determined by: dividing the plurality of time slots of the subframe structure into a first portion and a second portion; and The main frame structure is derived by switching the order of the first part and the second part.

12. The UE device according to claim 9, wherein the TDD frequency bands of the PCC and the SCC are N41 frequency band and N79 frequency band.

13. The UE device according to claim 9, wherein: The CA frame structure is determined by time offsetting the primary frame from the secondary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots of the primary frame and the secondary frame.

14. The UE device of claim 9, wherein the CA frame structure is determined by time-shifting the secondary frame from the primary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots in the primary frame and the secondary frame.

15. A method of operating a network entity in communication with a user equipment UE, comprising: Performing downlink and uplink with the UE using a primary frame on a first time division duplex TDD frequency band of a primary component carrier PCC, wherein the primary frame has a primary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; performing a downlink with the UE using a secondary frame on the second frequency band of the secondary component carrier SCC, wherein the secondary frame has a secondary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; as well as receiving a sounding reference signal SRS on the SCC, The primary frame and the secondary frame form a carrier aggregation CA frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink timeslot on the primary frame of the PCC.

16. The method of operating a network entity according to claim 15, wherein the primary frame and the secondary frame are further configured such that an uplink time slot of the primary frame is aligned with a downlink time slot of the secondary frame.

17. The method for operating a network entity according to claim 16, wherein the CA frame structure is determined by: dividing the plurality of time slots of the main frame structure into a first part and a second part; and The secondary frame structure is derived by switching the order of the first part and the second part.

18. The method for operating a network entity according to claim 16, wherein the CA frame structure is determined by: dividing the plurality of time slots of the subframe structure into a first portion and a second portion; and The main frame structure is derived by switching the order of the first part and the second part.

19. The method for operating a network entity according to claim 16, wherein the TDD frequency bands of the PCC and the SCC are N41 frequency band and N79 frequency band.

20. The method of operating a network entity according to claim 16, wherein the CA frame structure is determined by time-shifting the primary frame from the secondary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots of the primary frame and the secondary frame.

21. The method of operating a network entity according to claim 16, wherein the CA frame structure is determined by time-shifting the secondary frame from the primary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots in the primary frame and the secondary frame.

22. A network entity, comprising: processor; a memory, coupled to the processor, the memory comprising data and instructions to be executed on the processor; Frame module, storing carrier aggregation CA frame structure; a communication module coupled to transmit downlink and receive uplink according to the CA frame structure; a transceiver coupled to the communication module to transmit and receive according to the CA frame structure; as well as an antenna coupled to the transceiver to transmit and receive in a first time division duplex TDD frequency band of a primary component carrier PCC and in a second TDD frequency band of a secondary component carrier according to a CA frame structure, The processor executes instructions to performing downlink and uplink with a user equipment UE using a primary frame on a first time division duplex TDD frequency band of a primary component carrier PCC, wherein the primary frame has a primary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; performing a downlink with the UE using a secondary frame on the second frequency band of the secondary component carrier SCC, wherein the secondary frame has a secondary frame structure including a plurality of time slots including one or more downlink time slots, one or more uplink time slots, and one or more switching time slots; as well as receiving a sounding reference signal SRS on the SCC, The primary frame and the secondary frame form a carrier aggregation CA frame structure, wherein the SRS on the secondary frame of the SCC is aligned with the downlink timeslot on the primary frame of the PCC.

23. The network entity of claim 22, wherein the primary frame and the secondary frame are further configured such that an uplink timeslot of the primary frame is aligned with a downlink timeslot of the secondary frame.

24. The network entity according to claim 23, wherein: The CA frame structure is determined by: dividing the plurality of time slots of the main frame structure into a first part and a second part; and The secondary frame structure is derived by switching the order of the first part and the second part.

25. The network entity of claim 23, wherein the CA frame structure is determined by: dividing the plurality of time slots of the subframe structure into a first portion and a second portion; and The main frame structure is derived by switching the order of the first part and the second part.

26. The network entity according to claim 23, wherein the TDD frequency bands of the PCC and the SCC are N41 frequency band and N79 frequency band.

27. The network entity of claim 23, wherein the CA frame structure is determined by time-shifting the primary frame from the secondary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots of the primary frame and the secondary frame.

28. The network entity of claim 23, wherein the CA frame structure is determined by time-shifting the secondary frame from the primary frame by an integer duration T, the duration T being the duration of each of the plurality of time slots in the primary frame and the secondary frame.

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