WO2017151173A1 - Self-contained tdd frame structure and dl-ul configuration in 5g system - Google Patents

Abstract

Devices and methods of flexible UL/DL scheduling in 5G systems are generally described. A UE decodes DL control information from an eNB. The control information indicates a particular UL/DL configuration that includes a ratio between UL and DL subframes for a configurable period that is able to be adjusted each time new control information is received, a location of the subframes and a period of application. HARQ-ACK feedback is indicated in a last subframe or an earliest subframe or spread evenly over one or more subframes at least K subframes after the associated DL subframe.

Description

SELF-CONTAINED TDD FRAME STRUCTURE AND DL-UL CONFIGURATION IN 5G SYSTEM

PRIORITY CLAIM

[0001] This application claims the benefit of priority to United States

Provisional Patent Application Serial No. 62/302,020, filed March 1, 2016, and entitled '^"SELF-CONTAINED TDD FRAME STRUCTURE AND DL-UL CONFIGURATION IN 5G S YSTEM," which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] Embodiments pertain to radio access networks. Some embodiments relate to providing data in cellular and wireless local area network (WLAN) networks, including Third Generation Partnership Project Long Term Evolution (3GPP LTF.) networks and LTE advanced (LTE-A) networks as well as 4^th generation (4G) networks and 5^th generation (5G) networks. Some embodiments relate to Time Division Duplexing (TDD) in 5G networks.

BACKGROUND

[0003] The use of 3 GPP LTE systems (including LTE and LTE-

Advanced systems) has increased due to both an increase in the types of devices user equipment (UEs) using network resources as well as the amount of data and bandwidth being used by various applications, such as video streaming, operating on these UEs. As a result, 3GPP LTE systems continue to develop, with the next generation wireless communication system, 5G, to improve access to information and data sharing. 5G looks to provide a unified network/system that is able to meet vastly different and sometime conflicting performance dimensions and services driven by disparate services and applications while maintaining compatibility with legacy UEs and applications.

[0004] The increased number and types of UEs may be conducive to maximum flexibility for subframe design. In particular, when TDD is used for communication, it may be desirable for UEs to monitor and blindly decode a large proportion of the subframes. This may undesirably increase power consumption, which may be of particular import for machine -type

communication (MTC) UEs that have limited batter}⁷ life, as well as the false alarm rate among the UEs.

BRIEF DESCRIPTION OF THE FIGURES

[0005] In the figures, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The figures illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0006] FIG. 1 is a functional diagram of a wireless network in accordance with some embodiments.

[0007] FIG. 2 illustrates components of a communication device in accordance with some embodiments.

[0008] FIG. 3 illustrates a block diagram of a communication device in accordance with some embodiments.

Θ009] FIG. 4 illustrates another block diagram of a communication device in accordance with some embodiments.

[0010] FIG. 5 illustrates a frame structure supporting a variable uplink

(UL)/downlink (DL) ratio configuration in accordance with some embodiments.

[0011] FIG. 6 illustrates UL/DL configurations in accordance with some embodiments.

[0012] FIG. 7 illustrates UL DL configuration modification in accordance with some embodiments.

[0013] FIG. 8 illustrates a physical downlink shared channel (PDSCH)

Hybrid Automatic Repeat Request (HARQ) timeline in accordance with some embodiments.

[0014] FIG. 9 illustrates a method of flexible communication in accordance with some embodiments.

DETAILED DESCRIPTION

[0015] The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims.

[0016 ] FIG. 1 shows an example of a portion of an end-to-end network architecture of a Long Term Evolution (LTE) network with various components of the network in accordance with some embodiments. As used herein, an LTE network refers to both LTE and LTE Advanced (LTE-A) networks as well as other versions of LTE networks to be developed. The network 100 may comprise a radio access network (RAN) (e.g., as depicted, the E-UTRAN or evolved universal terrestrial radio access network) 101 and core network 120 (e.g., shown as an evolved packet core (EPQ) coupled together through an SI interface 115. For convenience and brevity, only a portion of the core network 120, as well as the RAN 101, is shown in the example.

[0017] The core network 120 may include a mobility management entity

(MME) 122, serving gateway (serving GW) 124, and packet data network gateway (PDN GW) 126. The RAN 101 may include evolved node Bs (eNBs) 104 (which may operate as base stations) for communicating with user equipment (UE) 102. The eNBs 104 may include macro eNBs 104a and low power (LP) eNBs 104b. The eNBs 104 and UEs 102 may employ the techniques as described herein.

[0018] The MME 122 may be similar in function to the control plane of legacy Serving GPRS Support Nodes (SGSN). The MME 122 may manage mobility aspects in access such as gateway selection and tracking area list management. The serving GW 124 may terminate the interface toward the RAN 101 , and route data packets between the RAN 101 and the core network 120. In addition, the serving GW 124 may be a local mobility anchor point for inter-eNB handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement. The serving GW 124 and the MME 122 may he implemented in one physical node or separate physical nodes.

[0019] The PDN GW 126 may terminate a SGi interface toward the packet data network (PDN). The PDN GW 126 may route data packets between the EPC 120 and the external PDN, and may perform policy enforcement and charging data collection. The PDN GW 126 may also provide an anchor point for mobility devices with non-LTE access. The external PDN can be any kind of IP network, as well as an IP Multimedia Subsystem (IMS) domain. The PDN GW 126 and the serving GW 124 may be implemented in a single physical node or separate physical nodes.

[0020J The eNBs 104 (macro and micro) may terminate the air interface protocol and may be the first point of contact for a UE 102. In some embodiments, an eNB 104 may fulfill various logical functions for the RAN 101 including, but not limited to, RNC (radio network controller functions) such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management. In accordance with embodiments, UEs 102 may be configured to communicate orthogonal frequency di vision multiplexed (OFDM) communication signals with an eNB 104 over a multicarsier communication channel in accordance with an OFDMA communication technique. The OFDM signals may comprise a plurality of orthogonal subcarriers.

[0021] The Si interface 115 may be the interface that separates the RAN

101 and the EPC 120. It may be split into two parts: the S l -U, which may carry traffic data between the eNBs 104 and the serving GW 124, and the S l-MME, which may be a signaling interface between the eNBs 104 and the MME 122. The X2 interface may be the interface between eNBs 104. The X2 interface may comprise two parts, the X2-C and X2-U. The X2-C may be the control plane interface between the eNBs 104, while the X2-U may be the user plane interface between the eNBs 104.

[0022] With cellular networks, LP cells 1 4b may be typically used to extend coverage to indoor areas where outdoor signals do not reach well, or to add network capacity in areas with dense usage. In particular, it may be desirable to enhance the coverage of a wireless communication system using cells of different sizes, macrocells, microceils, picocells, and femtocells, to boost system performance. The cells of different sizes may operate on the same frequency band, or may operate on different frequency bands with each cell operating in a different frequency band or only cells of different sizes operating on different frequency bands. As used herein, the term LP eNB refers to any- suitable relatively LP eNB for implementing a smaller cell (smaller than a macro cell) such as a femtoceil, a picocell, or a microcell. Femtoceil eNBs may he typically provided by a mobile network operator to its residential or enterprise customers, A femtoceil may be typically the size of a residential gateway or smaller and generally connect to a broadband line. The femtoceil may connect to the mobile operator's mobile network and provide extra coverage in a range of typically 30 to 50 meters. Thus, a LP eNB 104b might be a femtoceil eNB since it is coupled through the PDN GW 126. Similarly, a picocell may be a wireless communication system typically covering a small area, such as in-building (offices, shopping malls, train stations, etc.), or more recently in-aircrafi. A picocell eNB may generally connect through the X2 link to another eNB such as a macro eNB through its base station controller (BSC) functionality. Thus, LP eNB may be implemented with a picocell eNB since it may be coupled to a macro eNB 104a via an X2 interface. Picocell eNBs or other LP eNBs LP eNB 104b may incorporate some or all functionality of a macro eNB LP eNB 104a. in some cases, this may be referred to as an access point base station or enterprise femtoceil.

[0023] Communication over an LTE network may be split up into 10ms radio frames, each of which may contain ten 1ms subframes. Each subframe of the frame, in turn, may contain two slots of 0.5ms. Each subframe may be used for uplink (UL) communications from the UE 102 to the eNB 104 or downlink (DL) communications from the eNB 104 to the UE. In one embodiment, the eNB 104 may allocate a greater number of DL communications than UL communications in a particular frame. The eNB 104 may schedule

transmissions over a variety of frequency bands. Each slot of the subframe may contain 6-7 OFDM symbols, depending on the system used. In one

embodiment, each subframe may contain 12 subcarriers. In the 5G system, however, the frame size (ms) and number of subframes within a frame may be different from that of a 4G or LTE system. The subframe size may also vary in the 5G system from frame to frame. In some embodiments, the 5G system may span 5 times the frequency of the LTE/4G system, in which case the frame size of the 5G system may be 5 times smaller than that of the LTE/4G system.

[0024] A downlink resource grid may be used for downlink

transmissions from an eNB 104 to a UE 102, while an uplink resource grid may be used for uplink transmissions from a UE 102 to an eNB 104 or from a UE 102 to another UE 102. The resource grid may be a time -freq ency grid, which is the physical resource in the downlink in each slot. The smallest time- frequency unit in a resource grid may be denoted as a resource element (RE). Each column and each row of the resource grid may correspond to one OFDM symbol and one OFDM subcarrier, respectively. The resource grid may contain resource blocks (RBs) that describe the mapping of physical channels to resource elements and physical RBs (PRBs), A PRB may be the smallest unit of resources that can be allocated to a UE. A RB in some embodiments may be 180 kHz wide in frequency and 1 slot long in time. In frequency, RBs may be either 12 x 15 kHz subcarriers or 24 x 7.5 kHz subcarriers wide, dependent on the system bandwidth. In Frequency Division Duplexing (FDD) systems, both the uplink and downlink frames may be 10ms and frequency (full-duplex) or time (half-duplex) separated. In TDD systems, the uplink and downlink subframes may be transmitted on the same frequency and are multiplexed in the time domain . The duration of the resource grid 400 in the time domain corresponds to one subframe or two resource blocks. Each resource grid may comprise 12 (subcarriers) * 14 (symbols) =168 resource elements.

[0025] TDD systems may include UL, DL and, unlike FDD systems, special subframes due to the time-division aspect of the system when switching between UL and DL subframes. In particular, the special subframe may be preceded by a DL or UL subframe (and succeeded by a subframe of the opposite type) and may include both a UL and DL control region. A guard period may be reserved at the initiation of the special subframe to permit the UE 102 to switch between the receiver and transmitter chain.

[0026] Each OFDM symbol may contain a cyclic prefix (CP) which may^¬ be used to effectively eliminate Inter Symbol Interference (ISI), and a Fast Fourier Transform (FFT) period. The duration of the CP may be determined by the highest anticipated degree of delay spread. Although distortion from the preceding OFDM symbol may exist within the CP, with a CP of sufficient duration, preceding OFDM symbols do not enter the FFT period. Once the FFT period signal is recei ved and digitized, the receiver may ignore the signal in the CP

[0027] There may be several different physical downlink channels that are conveyed using such resource blocks, including the physical downlink control channel (PDCCH) and the physical downlink shared channel (PDSCH). Each downlink subframe may be partitioned into the PDCCH and the PDSCH. The PDCCH may normally occupy the first two symbols of each subframe and cany, among other things, information about the transport format and resource allocations related to the PDSCH channel, as well as H-ARQ information related to the uplink shared channel. The PDSCH may carry user data and higher layer signaling to a UE and occupy the remainder of the subframe. Typically, downlink scheduling (assigning control and shared channel resource blocks to UEs within a cell) may be performed at the eNB based on channel quality information provided from the UEs to the eNB, and then the downlink resource assignment information may be sent to each UE on the PDCCH used for (assigned to) the UE. The PDCCH may contain downlink control information (DCI) in one of a number of formats that indicate to the UE how to find and decode data, transmitted on PDSCH in the same subframe, from the resource grid. The DCI format may provide details such as number of resource blocks, resource allocation type, modulation scheme, transport block, redundancy- version, coding rate etc. Each DCI format may have a cyclic redundancy code (CRC) and be scrambled with a Radio Network Temporary Identifier (RNTI) that identifies the target UE for which the PDSCH is intended. Use of the UE- specific R TI may limit decoding of the DCI format (and hence the

corresponding PDSCH) to only the intended UE.

[0028] In addition to the PDCCH, an enhanced PDCCH (EPDCCH) may^¬ be used by the eNB 104 and UE 102. Unlike the PDCCH, the EPDCCH may be disposed in the resource blocks normally allocated for the PDSCH. Different UEs may have different EPDCCH configurations that are configured via Radio Resource Control (RRC) signaling. Each UE 102 may be configured with sets of EPDCCHs, and the configuration can also be different between the sets. Each EPDCCH set may have 2, 4, or 8 PRB pairs. In some embodiments, resource blocks configured for EPDCCHs in a particular subframe may be used for PDSCH transmission if the resource blocks are not used for the EPDCCH transmissions during the subframe.

[0029] In order to enable retransmission of missing or erroneous data, the Hybrid Automatic Repeat Request (HARQ) scheme may be used to provide the feedback on success or failure of a decoding attempt to the transmitter after each received data block. When an eNB 104 sends data to the UE 102 in a PDSCH (or 5G PDSCH, referred to as an xPDSCH), the data packets may be sent together with indicators in a PDCCH in the same subframe that inform, the UE 102 about the scheduling of the PDSCH, including the transmission time and other scheduling information of the transmitted data. For each PDSCH codeword that the UE 102 receives, the UE 102 may respond with an ACK when the codeword is successfully decoded, or a N ACK when the codeword is not successfully decoded. The eNB 104 may expect the ACK NACK feedback after a predetermined number of subframes from the subframe in which the PDSCH data is sent. Upon receiving a NACK from the UE 02, the eNB 104 may retransmit the transport block or skip the retransmission if the retransmission number exceeds a maximum value. The ACK NACK for the corresponding the PDSCH may be transmitted by the UE four subframes after the PDSCH is received from, the eN B 04. Depending on the number of codewords present, HARQ-ACK information corresponding to a PDSCH may contain, for example, 1 or 2 information bits (DCI formats la and lb, respectively). The HARQ-ACK bits may then be processed, as per the PUCCH.

[0030] Embodiments described herein may be implemented into a system using any suitably configured hardware and/or software. FIG. 2 illustrates components of a UE in accordance with some embodiments. At least some of the components shown m ay be used in the UE 102 (or eNB 104) shown in FIG. 1. The UE 200 and other components may be configured to use the synchronization signals as described herein. The UE 200 may be one of the UEs 102 shown in FIG. 1 and may be a stationary, non-mobile device or may be a mobile device. In some embodiments, the UE 200 may include application circuitry 202, baseband circuitry 204, Radio Frequency (RF) circuitry 206, front- end module (FEM) circuitry 208 and one or more antennas 210, coupled together at least as shown. At least some of the baseband circuitry 204, RF circuitr ' 206, and FEM circuitry 208 may form a transceiver. In some embodiments, other network elements, such as the eNB may contain some or all of the components shown in FIG. 2. Other of the network elements, such as the MME, may contain an interface, such as the SI interface, to communicate with the eNB over a wired connection regarding the UE. [0031] The application or processing circuitry 202 may include one or more application processors. For example, the application circuitry 202 may include circuitry such as, but not limited to, one or more single-core or multi- core processors. The processors) may include any combination of general - purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with and/or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems to run on the system.

[0032] The baseband circuitry 204 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 204 may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry 206 and to generate baseband signals for a transmit signal path of the RF circuitry 206. Baseband processing circuity 204 may interface with the application circuitry 202 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 206. For example, in some embodiments, the baseband circuitry 204 may include a second generation (2G) baseband processor 204a, third generation (3G) baseband processor 204b, fourth generation (4G) baseband processor 204c, and/or other baseband processor(s) 204d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 5G, etc.). The baseband circuitry 204 (e.g., one or more of baseband processors 204a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 206. The radio control functions may include, but are not limited to, signal modulation/demodulation,

encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuits"}' 204 may include FFT, preceding, and/or constellation mapping/demapping functionality, in some embodiments, encoding/decoding circuitry of the baseband circuitry 204 may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[0033] In some embodiments, the baseband circuitry 204 may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU) 204e of the baseband circuitry 204 may be configured to am elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processors) (DSP) 204 Γ The audio DSP(s) 204f may be include elements for

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

[0034J In some embodiments, the baseband circuitry 204 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 204 may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network

(WPAN). Embodiments in which the baseband circuitry 204 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry. In some embodiments, the device can be configured to operate in accordance with communication standards or other protocols or standards, including Institute of Electrical and Electronic Engineers (IEEE) 802.16 wireless technology (WiMax), IEEE 802.11 wireless technology (WiFi) including IEEE 802.1 1 ad, which operates in the 60 GHz millimeter wave spectrum, various other wireless technologies such as global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE radio access network (GERAN), universal mobile telecommunications system (UMTS), UMTS terrestrial radio access network (I THA N ), or other 2G, 3G, 4G, 5G, etc. technologies either already developed or to be developed.

0035| RF circuitry 206 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 206 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 206 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 208 and provide baseband signals to the baseband circuitr - 204. RF circuitry 206 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 204 and provide RF output signals to the FEM circuitry 208 for transmission.

[0036] In some embodiments, the RF circuitry 206 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 206 may include mixer circuitry 206a, amplifier circuitry 206b and filter circuitry 206c. The transmit signal path of the RF circuitry 206 may include filter circuitry 206c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206d for synthesizing a frequency for use by the mixer circuitry 206a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 206a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 208 based on the synthesized frequency provided by synthesizer circuitry 206d. The amplifier circuitry 206b may be configured to amplify the down-converted signals and the filter circuitry 206c may be a low -pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 204 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although tins is not a requirement. In some embodiments, mixer circuitry 206a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect. [0037] In some embodiments, the mixer circuitiy 206a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 206d to generate RF output signals for the FEM circuitry 208. The baseband signals may be provided by the baseband circuitiy 204 and may be filtered by filter circuitry 206c. The filter circuitry 206c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

[0038] In some embodiments, the mixer circuitiy 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and/or upconversion respectively. In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitiy 206a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a may be arranged for direct downconversion and/or direct upconversion, respectively. In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may be configured for super-heterodyne operation .

[0039] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 206 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 204 may include a digital baseband interface to communicate with the RF circuitry 206.

[0040J In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

[0041] In some embodiments, the synthesizer circuitry 2()6d may be a fractional -N synthesizer or a fractional N/N+l synthesizer, altliough the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 206d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[0042] The synthesizer circuitry 206d may be configured to synthesize an output frequency for use by the mixer circuitrv' 206a of the RF circuitry- 206 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 206d may be a fractional N/N+l synthesizer.

[0043] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitrv' 204 or the applications processor 202 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a lookup table based on a channel indicated by the applications processor 202.

[0044] Synthesizer circuitry 206d of the RF circuitry 206 may include a divider, a delay -locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+l (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up in to Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0045] In some embodiments, synthesizer circuitry 206d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the earner frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (flo). In some embodiments, the RF circuits"}' 206 may include an IQ/polar converter. [0046] FEM circuitry 208 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 210, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 206 for further processing. FEM circuitry 208 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 206 for transmission by one or more of the one or more antennas 2 0.

[0047] In some embodiments, the FEM circuitry 208 may include a

TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include a low-noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 206). The transmit signal path of the FEM circuits"}' 208 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 206), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 210.

Θ048] In some embodiments, the UE 200 may include additional elements such as, for example, memory/storage, display, camera, sensor, and/or input/output (I/O) interface as described in more detail below. In some embodiments, the UE 200 descri bed herein may be part of a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a smartphone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wirelessly. In some embodiments, the UE 200 may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. For example, the UE 200 may include one or more of a keyboard, a keypad, a touchpad, a display, a sensor, a non -volatile memory port, a universal serial bus (USB) port, an audio jack, a power supply interface, one or more antennas, a graphics processor, an application processor, a speaker, a microphone, and other I/O components. The display may be an LCD or LED screen including a touch screen. The sensor may include a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite.

[0049J The antennas 210 may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some multiple -input multiple-output (ΜΊΜΌ) embodiments, the antennas 210 may be effectively separated to take advantage of spatial diversity and the different channel characteristics thai may result.

[0050J Although the UE 200 is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software -configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements.

[0051] Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage device may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage device may include readonly memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media. Some embodiments may include one or more processors and may be configured with instructions stored on a computer-readable storage device. [0052] FIG. 3 is a block diagram of a communication device in accordance with some embodiments. The device may be a UE or eNB, for example, such as the UE 102 or eNB 104 shown in FIG. 1 that may be configured to track the UE as described herein . The physical layer circuitry 302 may perform various encoding and decoding functions that may include formation of baseband signals for transmission and decoding of recei ved signals. The communication device 300 may also include medium access control layer (MAC) circuitry 304 for controlling access to the wireless medium. The communication device 300 may also include processing circuitry 306, such as one or more single-core or multi-core processors, and memory 308 arranged to perform the operations described herein. The physical layer circuitry- 302, MAC circuitry 304 and processing circuitry 306 may handle various radio control functions that enable communication with one or more radio networks compatible with one or more radio technologies. The radio control functions may include signal modulation, encoding, decoding, radio frequency shifting, etc. For example, similar to the device shown in FIG. 2, in some embodiments, communication may be enabled with one or more of a WMAN, a WLAN, and a WPAN. In some embodiments, the communication device 300 can be configured to operate in accordance with 3 GPP standards or other protocols or standards, including WiMax, WiFi, WiGig, GSM, EDGE, GERAN, UMTS,

UTRAN, or other 3G, 3G, 4G, 5G, etc. technologies either already developed or to be developed. The communication device 300 may include transceiver circuitry 312 to enable communication with other external devices wirelessly and interfaces 314 to enable wired communication with other external devices. As another example, the transceiver circuitry 312 may perform various transmission and reception functions such as conversion of signals between a baseband range and a Radio Frequency (RF) range.

[0053] The antennas 301 may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some MIMO embodiments, the antennas 301 may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may result. [0054] Although the communication device 300 is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including DSPs, and/or other hardware elements. For example, some elements may comprise one or more

microprocessors, DSPs, FPGAs, ASICs, RFICs and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operatmg on one or more processing elements. Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer- readable storage device, which may be read and executed by at least one processor to perform the operations described herein.

[0055] FIG. 4 illustrates another block diagram of a communication device in accordance with some embodiments. In alternative embodiments, the communication device 400 may operate as a standalone device or may be connected (e.g., networked) to other communication devices. In a networked deployment, the communication device 400 may operate in the capacity of a server communication device, a client communication device, or both in server- client network environments. In an example, the communication device 400 may act as a peer communication device in peer-to-peer (P2P) (or other distributed) network environment. The communication device 400 may be a UE, eNB, PC, a tablet PC, a STB, a PDA, a mobile telephone, a smart phone, a web appliance, a network router, switch or bridge, or any communication device capable of executing instructions (sequential or otherwise) that specify actions to be taken by that communication device. Further, while only a single communication device is illustrated, the term '^"communication device" shall also be taken to include any collection of communication devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a service (SaaS), other computer cluster configurations.

[0056] Examples, as described herein, may include, or may operate on, logic or a number of components, modules, or mechanisms. Modules are tangible entities (e.g., hardware) capable of performing specified operations and may be configured or arranged in a certain manner. In an example, circuits may be arranged (e.g., internally or with respect to external entities such as other circuits) in a specified manner as a module. In an example, the whole or part of one or more computer systems (e.g., a standalone, client or server computer system) or one or more hardware processors may be configured by firmware or software (e.g., instructions, an application portion, or an application) as a module that operates to perform specified operations. In an example, the software may reside on a communication device readable medium. In an example, the software, when executed by the underlying hardware of the module, causes the hardware to perform the specified operations.

ΘΘ57] Accordingly, the term "module^" is understood to encompass a tangible entity, be that an entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transitorily) configured (e.g., programmed) to operate in a specified manner or to perform part or all of any operation described herein . Considering examples in which modules are temporarily configured, each of the modules need not be instantiated at any one moment in time. For example, where the modules comprise a general-purpose hardware processor configured using software, the general-purpose hardware processor may be configured as respective different modules at different times. Software may accordingly configure a hardware processor, for example, to constitute a particular module at one instance of time and to constitute a different module at a different instance of time.

[0058] Communication device (e.g., computer system) 400 may include a hardware processor 402 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 404 and a static memory 406, some or all of which may communicate with each other via an interlink (e.g., bus) 408. The

communication device 400 may further include a display unit 410, an alphanumeric input device 412 (e.g., a keyboard), and a user interface (UI) navigation device 414 (e.g., a mouse). In an example, the display unit 410, input device 412 and UI navigation device 414 may be a touch screen display. The communication device 400 may additionally include a storage device (e.g., drive unit) 416, a signal generation device 418 (e.g., a speaker), a network interface device 420, and one or more sensors 421, such as a global positioning system (GPS) sensor, compass, acceleromeier, or other sensor. The communication device 400 may include an output controller 428, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).

[0059J The storage de vice 416 may include a communication device readable medium 422 on which is stored one or more sets of data structures or instructions 424 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions 424 may also reside, completely or at least partially, within the main memory 404, within static memory 406, or within the hardware processor 402 during execution thereof by the communication device 400. In an example, one or any combination of the hardware processor 402, the main memory 404, the static memory 406, or the storage device 416 may constitute communication device readable media.

[0060] While the communication device readable medium 422 is illustrated as a single medium, the term "communication device readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) configured to store the one or more instructions 424.

[0061 J The term "communication device readable medium" may include any medium that is capable of storing, encoding, or carrying instructions for execution by the communication device 400 and that cause the communication device 400 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting communication device readable medium examples may include solid-state memories, and optical and magnetic media. Specific examples of communication device readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices: magnetic disks, such as internal hard disks and removable disks:

magneto-optical disks; Random Access Memory (RAM); and CD-ROM and DVD-ROM disks. In some examples, communication device readable media may include non-transitory communication device readable media. In some examples, communication device readable media may include communication device readable media that is not a transitory propagating signal.

[0062] The instructions 424 may further be transmitted or received over a communications network 426 using a transmission medium via the network interface device 420 utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone netw orks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks (e.g., institute of Electrical and Electronics Engineers (IEEE) 802.1 1 family of standards known as Wi-Fi®, IEEE 802.16 family of standards known as WiMax®), IEEE 802.15.4 family of standards, a Long Term Evolution (LTE) family of standards, a Universal Mobile Telecommunications System (UMTS) family of standards, peer-to-peer (P2P) networks, among others. In an example, the network interface device 420 may include one or more physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or more antennas to connect to the communications network 426. In an example, the network interface device 420 may include a plurality of antennas to wirelessly communicate using at least one of single-input multiple-output (S1MO), MIMO, or multiple-input single-output (MISO) techniques. In some examples, the network interface device 420 may wirelessly communicate using Multiple User MIMO techniques. The term "transmission medium" shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the communication device 400, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

[0063] As above, the 5G system may either be FDD or TDD based. In some embodiments, the LTE system may reserve only a limited number of subfrarnes within each radio frame as DL or UL subframes, while the remaining subframes may be allocated as flexible subframes. The flexible subframes may be either DL or UL subframes, depending on the configuration used. To maintain maximum schedule flexibility, rather than being provided a particular configuration, a UE may simply assume that all subframes are flexible subframes (and thus as a default can be used as DL subframes or as UL subframe when scheduled) - with the exception of a small number of fixed UL subframes used for random, access procedures. In this case, the UE may monitor all the DL and flexible subframes and blindly decode the control channel to determine, e.g., whether the UE is being paged using that subframe. This ma - increase the power consumption as the UE may decode the 5G physical downlink control channel (xPDCCH) in every flexible and DL subframe. Note that while both the PDCCH and xPDCCH are used for transmission of DL control information, the physical structure may be different. This may include, for example, the mapping to physical resources (e.g., which REs are used, whether the signal is beamformed), what kind of information is encoded in a respective DCI. In addition, if the UE has not detected a UL grant for a flexible subframe in a substantial amount of time, the UE may assume that the subframes are DL subframes and thus may blindly decode the xPDCCHs in UL subframes, thereby increasing the false alarm rate.

[0064] To reduce power consumption at the UE without sacrificing

UL/DL resource scheduling flexibility, particular elements in the 5G system may be considered. It would be desirable to design UL/DL configuration to support finer UL/DL ratio granularity while simultaneously maximizing resource efficiency. To achieve this, in various embodiments, multiple UL/DL configurations may be used to support a variety of UL/DL ratios. It would also be desirable to dynamically signal the UL/DL configuration while

simultaneously minimizing control signaling overhead. To achieve this, in some embodiments, detailed signaling design mechanisms may enable dynamic UL/DL adaptation to achieve two targets: maximizing spectrum efficiency and minimizing power consumption at the UE. It would further be desirable to determine a detailed HARQ-ACK timeline for UL/DL configuration to guarantee uplink control information (UCI) performance. To achieve this, in various embodiments, different HARQ timelines for data, transmission aimed at different use cases and requirements may be used.

[0065] To achieve the above, a 5G system in which TDD

communications are used may be designed in which a 5G transmission frame is used that is different from the typical LTE radio frame. In particular, the 5G transmission frame may have a period that is different from that of the LTE radio frame. While the 5G transmission frame may contain a number of 5G subframes, the number of 5G subframes within the 5G transmission frame may be the same as, or may differ from, the number of subframes in the LTE radio frame.

[0066] FIG. 5 illustrates a frame structure supporting a variable UL/DL ratio configuration in accordance with some embodiments. Although 5G transmission frame i 502 and 5G transmission frame i+1 502 are shown, details of the 5G subframes 504 of only one of the multiple 5G transmission frames 502 is shown for convenience. Similarly, only a limited number of 5G subframes 504 of 5G transmission frame i 502 are shown for convenience.

[0067] In particular, the 5G transmission frames 502 may employ one of a plurality of UL/DL configurations that specify the number and proportion of UL and DL subframes 504 within each 5G transmission frame 502. The UL/DL configurations may indicate the number of DL and UL transition periods within a particular period, which may include one or more 5G transmission frames 502. In some embodiments, two UL/DL configurations may be used, while in other embodiments a greater number may be used. For example, the 5G transmission frame 502 may have UL/DL configuration A 506, which may comprise two DL transmission periods 510, 516 and two UL transmission periods 514, 518, or the 5G transmission frame 502 may have UL/DL configuration B 508, which may- comprise two DL transmission periods 512, 516 and one UL transmission period 518,

[0068] The duration of each 5G transmission frame 502 may, in some embodiments, remain the same. In such embodiments, duration of the transmission periods, whether UL or DL, may vary between configurations but the sum of the durations of all transmission periods may remain the duration of the 5G transmission frame 502. Each UL or DL transmission period may respectively contain a plurality of consecutive UL or DL 5G subframes 504. Each 5G subframes 504 may have the same predetermined duration, which may^¬ be 0.2ms for example. Thus, the total number of 5G subframes 504 may remain constant independent of the configuration used, albeit the number of DL and UL 5G subframes 504 may change.

[0069] In configurations with multiple DL transmission periods, the number of DL 5G subframes 504 may differ in one or more of the DL transmission periods: similarly in configurations with multiple UL transmission periods, the number of UL 5G subframes 504 may differ in one or more of the DL transmission periods. In other embodiments, the number 5G subframes 504 may remain the same for each UL and/or DL transmission period, and may be the same or may be different between the different types (UL/DL) of transmission period. For example, as shown in UL/DL configuration A 506 of FIG. 5, a first DL transmission period 510 has the same number of DL 5G subframes 504 as UL 5G subframes 504 of a second UL transmission period 518 and a greater number of DL 5G subframes 504 than UL 5G subframes 504 of a first UL transmission period 514, while a second DL transmission period 516 has the same number of DL 5G subframes 504 as UL 5G subframes 504 of the first UL transmission period 514 and fewer DL 5G subframes 504 than UL 5G subframes 504 of the second UL transmission period 518 (thus having few er DL 5G subframes 504 than the first DL transmission period 10), As shown in UL/DL configuration B 508 of FIG. 5, a first DL transmission period 512 has a greater number of DL 5G subframes 504 than either the second DL transmission period 516 or UL 5G subframes 504 of the UL transmission period 18, while the second DL transmission period 516 has fewer DL 5G subframes 504 than UL 5G subframes 504 of the UL transmission period 518 (thus having fewer DL 5G subframes 504 than the first DL transmission period 512),

[0070] Guard periods (not shown in FIG. 5) may be inserted to account for the time used by the UE to activate and deactivate transmitters and receivers, as well as to account for radio propagation delay. The guard periods may thus differ dependent on the activation/deactivation time for the physical components of the transmit and receive chain in the UE,

[0071 ] FIG. 6 illustrates UL/DL configurations in accordance with some embodiments. A greater number of, or fewer, UL/DL configurations may be available than those shown. In addition, in other embodiments the specific UL/DL configurations may vary from those shown in FIG. 6. As shown, the ratio of DL to UL transmission periods in each 5G transmission frame (which may be, for example, 1 ms or 2 ms) can be independently adapted to support applications with a variety of traffic pattern s, from symmetric (configurations 0- 3) to highly asymmetric (configurations 4-7). The UE may thus in some embodiments indicate either a desired pattern or one or more applications to the eNB, which the eNB may then use to assign a particular UL/DL configuration. Note that at least one UL and at least one DL subframe may be present in each configuration. In this way, a large variety of applications can be supported efficiently using a single component earner (CC). In some embodiments, when carrier aggregation is used, multiple CCs can be used to increase capacity, or add more flexibility, with different configurations able to be used for each CC (i.e., the UL/DL configurations for each CC may be independent of each other).

[0072] In one embodiment, each 5G transmission frame of length X ms

(e.g. 2ms) may include two half-frames of length X/2 ms each. Each half-frame may include N subframes of length X/2N ms (e.g. 0.2ms for N = 10). In TDD UL-DL configurations 0-3, two guard periods may be used (when switching from a DL subframe to an UL subframe); in configuration 4-7, however, only- one GP may be used. UL-DL configurations with both X/2 ms and X ms DL-to- UL switch-point periodicity may be supported.

[0073] In the embodiment shown in FIG. 6, each half-frame may include five subframes. To support different applications ranging from symmetric sendees to highly asymmetric sendees, the ten subframes within each 5G transmission frame shown in FIG. 6 can be configured to eight different DL and UL ratios (8:2, 6:4, 4:6, 2:8, 9: 1, 7:3, 5:5 and 1 :9) in the different configurations. The frame structure allows rapid feedback between UE and their eNBs and enables an adaptable frame structure system, to make more effective use of other advanced technologies such as link adaptation, hybrid ARQ, beamforming, and transmit diversity.

[0074] As shown in FIG. 6, in each configuration, each 5G transmission frame may contain one or more predefined DL subframes. The eNB may broadcast during any number of these DL subframes the ratio of UL/DL configuration. This configuration may be maintained for a configurable period of one or more 5G transmission frames to reduce the overhead and to increase the overall system spectrum efficiency. FIG. 7 illustrates UL/DL configuration modification in accordance with some embodiments. In some embodiments, the DL subframe(s) 704 during which the eNB broadcasts the configuration may be at the beginning of the configurable period (also referred to as a modification period 702). The duration of a modification period 702 may thus be fixed. [0075] As shown in FIG. 7, some of the modification periods 702 may have a dedicated DL sub frame 704 that is reserved for the eNB to signal the UL/DL configuration. In other cases, multiple modification periods 702 may share the use of the same DL subframe(s) 704 used to signal the UL/DL configuration to reduce the overhead and to increase the overall system spectmm efficiency. In one embodiment, the period to apply the UL/DL configuration broadcasted in fixed DL subframe(s) may be signaled using a dedicated information element (IE) of a DCI format transmitted in the dedicated DL subframe(s) 704. In some embodiments, the modification period 702 may be a single frame, while in other embodiments, the modification period 702 may comprise multiple frames.

[0076] In another embodiment, rather than use a fixed DL subframe(s), the use of uplink transmission period may be fully or partially controlled by the eNB and the scheduling information carried in the DL DCI format used for a PUSCH grant. The number and duration of each DL and UL period in FIG. 5 may be varied across 5G transmission frames. For example, one 5G

transmission frame can be re-configured to a different UL/DL ratio when the traffic pattern changes, by dynamically scheduling some subframes from DL in 5G transmission frame i to UL in 5G transmission frame i+1 by means of one or more DCI formats used for a UL grant.

[0077] As shown in FIG. 6, in each configuration, each 5G transmission frame may contain one or more fixed special UL subframe. During the special UL subframe, the UE may transmit a Hybrid automatic repeat request (HARQ) acknowledgement (HARQ-ACK) in response to a previous DL transmission to the UE. In addition, during the special UL subframe the UE may perform functions such as random access procedure, channel sounding to assist DL scheduling or CS1 feedback for advanced MIMO technologies and to promote other radio functionality. The special UL subframe may be coordinated across neighboring cells, for example in a Coordinated Multipoint system (CoMP), to improve the UL control channel performance and simultaneously avoid crosslink interference among multiple cells.

[0078] Various schemes may be used to design a HARQ-ACK timeline for PDSCH transmission. FIG. 8 illustrates a PDSCH Hybrid Automatic Repeat Request (HARQ) timeline in accordance with some embodiments. FIG. 8 shows a 5G transmission frame 800 whose configuration is similar to UL/DL

configuration A 506 in FIG. 5. The frame 800 contains multiple DL data transmission periods 802, 804 and an UL data transmission period 806. As above, each of the transmission periods 802, 804, 806 may include a plurality of subframes. A unified HARQ-ACK timeline may be designed for all UL/DL ratio configurations in FIG. 6, with variations dependent on a particular emphasis.

[0079] In one embodiment (scheme 1), the HARQ-ACK feedback for the

DL subframes in the first DL transmission period 802 of the 5G transmission frame 800 may be transmitted in the UL data transmission period 806.

Specifically, in some embodiments, the HARQ-ACK feedback may be transmitted in the last UL subframe 808 of the UL data transmission period 806. This may provide a predetermined amount of delay between the DL

transmissions and the HARQ-ACK feedback. The final UL subframe 808 of the UL data transmission period 806 may contain a PUSCH (in which the UL data is transmitted) and further include a UCI. The UCI may, in addition to containing the HARQ-ACK, include either or both a SR (Scheduling Request) and the Channel Quality Indicator (CQI). In one embodiment, the HARQ-ACK feedback for the DL subframes in the first DL transmission period 802 of the 5G transmission frame 800 may be transmitted in the UL data transmission period 806, i.e., the HARQ-ACK feedback may be transmitted in the same 5G transmission frame 800 as the received communications.

[0080] In other embodiments, the HARQ-ACK feedback may appear in a

UL subframe in the UL data transmission period other than the last UL subframe. The UL subframe that is to include the HARQ-ACK feedback may be provided in RRC or other higher layer signaling. In other embodiments in which multiple UL data transmission periods are present, the HARQ-ACK feedback may appear in the last (or another) subframe in the last or anothe UL data transmission period. As above, the location of the UL subframe (and UL data transmission period) that is to include the HARQ-ACK feedback may be provided in RRC or other higher layer signaling.

[0081] Whether the particular configuration contains a single UL data transmission period or multiple UL data transmission periods, another scheme (scheme 2) may desire to minimize the HARQ-ACK feedback latency. To minimize this latency, in some embodiments the HARQ-ACK feedback for a given DL subframe (subframe n) may be transmitted in the earliest UL subframe after subframe n+K, that is K subframes after the DL subframe. K may be fixed in the IEEE specification or may be provided in RRC or other higher layer signaling. For example, K may be 4 or 5 subframes.

[00821 Rather than placing an emphasis on minimizing the HARQ-ACK feedback latency, other embodiments may focus on providing maximum, scheduling flexibility for the eNB (scheme 3). In such embodiments, the HARQ-ACK payload may be distributed over available UL subframes as e venly as possible in an attempt to avoid restricting xPUSCH scheduling of the eNB.

[0083] The various embodiments above thus focus on a set subframe location, minimized latency or maximized scheduling flexibility. Details for these embodiments are described below using Tables 1-3. The tables may show embodiments in which an xPDSCH transmission is present a corresponding xPDCCH detected within subframe(s) n~k, where k>5, keK and K is defined in Table 1-3 for the different schemes to achieve various goals. 5 subframes may be selected as the minimum (k=4) so that sufficient time is present for the UE to decode the xPDCCH. Each of Tables 1-3 illustrates K for the UL/DL configurations shown in FIG. 6, with the number N of subframes = 10.

[0084] In Table 1, the last UL subframe may contain the HARQ-ACK feedback. Thus, for example, in UL/DL configuration 0, in which subframes 0-3 and 5-8 are DL subframes and only subframes 4 and 9 are UL subframes, K may take the values 6-9 (as K is greater than 4), which correspond to prior DL subframes 0-3 (in subframe 4) and prior DL subframes 5-8 (in subframe 9), the prior subframes being in the previous frame. Note that in neither case does K take the value of 5 as 5 subframes prior to subframe 4 or 9 coiresponds to a UL, not DL, subframe. In UL/DL configuration 3, in which only subframes 0 and 5 are DL subframes and subframes 1-4 and 6-9 are UL subframes, K may be limited to the value 9, which corresponds to prior DL subframe 0 (in subframe 4) and prior DL subframe 5 (in subframe 9). In UL/DL configuration 4, in which subframes 0-8 are DL subframes and subframe 9 is a UL subframe, K may take the values 5-9 and 1 1-14, which correspond to DL subframes 0-4 in the current subframe 4 and prior DL subframes 5-8, with K= 10 being unavailable as it corresponds to UL subframe 9 in the prior frame.

Table 2; Downlink association set index K ; ··'½„)) of Scheme 2

[0085] In Table 2, the first UL subframe may contain the HARQ-ACK feedback. The K values in each configuration are similar to those of Table 1, however occurring in a different subframe and thus generally taking slightly different values. For example, in UL/DL configurations 0 and 4, the K values may occur in the same subframes and take one of the same values available as in Table 1. In UL/DL configuration 6, however, rather than K taking values 5-9 in UL subframe 9 only, each of UL subframes 6-9 may only take the value 5, which correspond to subframes 0-4 of the same frame.

[0086] In Table 3, the HARQ-ACK feedback is distributed as evenly as possible among the UL subframes. Thus, for example, when multiple UL subframes are available to provide the HARQ-ACK feedback for multiple DL subframes, the HARQ- ACK feedback is spread to maxim ize the num ber of UL subframes used. Tims, for example, in UL/DL configuration 1 only two UL subframes (e.g., 8, 9) are available to provide the HARQ-ACK feedback for three DL subframes (e.g., 0-2), so each UL subframe provides the HARQ-ACK feedback for at least one DL subframe. In UL/DL configuration 2 only three UL subframes (e.g., 7-9) are available to provide the HARQ-ACK feedback for two DL subframes (e.g., 0-1), so two of the three UL subframes provide the HARQ-ACK feedback for one DL subframe and one UL subframe is free from providing the HARQ-ACK feedback. In UL/DL configuration 6, which has 5 UL and 5 DL subframes, each UL subframe (5-9) provides the HARQ-ACK feedback for a corresponding DL subframe (e.g., 0-4).

[0087] FIG. 9 illustrates a method of flexible communication in accordance with some embodiments. The method may be performed by any of the UEs shown and described in FIGS. 1-4. Embodiments of the method may thus include additional or fewer operations or processes in comparison to what is illustrated in FIG. 9. In addition, embodiments of the method are not necessarily limited to the chronological order that is shown in FIG. 9. The method may be practiced with suitable systems, interfaces and components. In addition, while the method and other methods described herein may refer to UEs operating in accordance with 3GPP or other standards, embodiments of those methods are not limited to just those UEs and may also be practiced by other communication devices. [0088] At operation 902, the UE may receive TDD control information.

The TDD control information may be provided by an eNB and may, in some embodiments, be coordinated with multiple cells. The TDD control information may be received, for example, in a SIB or in a predetermined DL subframe. In the latter case, the TDD control information may be indicated by a DCI format carried by the xPDCCH. The DCI format may be modified from 4G DCI formats or may be an entirely new DCI format. In some embodiments, the predetermined DL subframe may be the first subframe in a configurable period. The configurable period may able to be adjusted each time new TDD control information is received by the UE.

[0089] At operation 904, the UE may decode the TDD control information and determine a DL/UL configuration. The predetermined DL subframe may be reserved for signaling the UL/DL configuration. The predetermined DL subframe may be associated with consecutive frames such that the plurality of consecutive frames share the UL/DL configuration indicated by the predefined DL subframe. The configurable period that the UL/DL configuration is appropriate for may be indicated by a dedicated information element. The DL and UL configuration may indicate a ratio between UL and DL subframes for the configurable period and the placement of the UL and DL subframes.

[0090] Once the UL/DL configuration has been determined at operation

904, the UE may communicate with the eNB at operation 906. This may include receiving control and data from the eNB in DL subframes indicated by the UL/DL configuration and transmitting or scheduling transmissions to the eNB in UL subframes indicated by the UL/DL configuration. The UL DL configuration may comprise a transmission frame comprising a plurality of DL transmission periods and at least one UL transmission period. Each of the DL and UL transmission periods may contain a plurality of DL and UL subframes, respectively,

[0091] At operation 908 the UE may, having received data from the eNB in at least one DL subframe, subsequently transmit HARQ-ACK feedback to the eNB as indicated by the TDD control information. The HARQ-ACK feedback may be transmitted in a fixed UL subframe that is independent of in which DL subframe of the frame the data was received. In one embodiment, this fixed UL subframe may be the final UL subframe in the frame. In oilier embodiments, the UL subframe may vary dependent on the DL subframe. For example, the earliest UL subframe after a particular delay (say 4 or 5 subframes, which may be set by the 5G specification) may be used to permit the UE to decode the DL subframe and determine the data is intended for the UE. Alternatively, a set of UL subframes may be used over which the HARQ-ACK feedback is distributed as evenly as possible.

[0092] At operation 910, the UE may determine whether the

configurable period has ended and thus it is time to receive a new UL/DL configuration having another configuration period. If so, the UE may return to operation 902, in which new TDD control information is received. The ratio of DL to UL subframes in the new UL/DL configuration may be dependent on feedback from the UE as to the types of applications running, with certain applications needing a greater number of DL subframes than UL subframes and vice-versa for other applications. This information may be provided to the eNB in a dedicated UL subframe so that the UL/DL configuration may be adjusted by the eNB in a subsequent configurable period. If not, the UE may continue to communicate with the eNB in the next frame at operation 906 using the same UL/DL configuration.

[0093J Although an embodiment has been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader scope of the present disclosure. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The

accompanying drawings that form a part hereof show, by way of illustration, and not of limitation, specific embodiments in which the subject matter may be practiced. The embodiments illustrated are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of tins disclosure. This Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. [0094] Such embodiments of the subject matter may be referred to herein, individually and/or collectively, by the term "embodiment" merely for convenience and without intending to voluntarily limit the scope of this application to any single inventive concept if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, it should be appreciated that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various

embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description,

[0095] In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of "at least one" or "one or more." In this document, the term "or" is used to refer to a nonexclusive or, such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated. In this document, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein," Also, in the following claims, the terms "including" and "comprising" are open-ended, that is, a sy stem, UE, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim . Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

[0096] The Abstract of the Disclosure is provided to comply with 37

C.F.R. § 1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incoiporated into the Detailed Description, with each claim standing on its own as a separate embodiment.

Claims

CLAIMS What is claimed is:

1. An apparatus of user equipment (UE) comprising:

a memory; and

processing circuitry in communication with the memory and arranged to: decode downlink (DL) control information from an evolved NodeB (eNB), the DL control information indicating a particular uplink (UL)/DL configuration selected from a set of predetermined UL/DL configurations and indicating a ratio between UL and DL subframes for a configurable period: and

communicate with the eNB based on the particular UL/DL configuration.

2. The apparatus of claim 1, wherein:

the DL control information is encoded in a system information block

(SIB),

3. The apparatus of claim 1, wherein:

the DL control information is encoded in a downlink control information (DCI) format carried by a fifth generation (5G) physical downlink control channel (xPDCCH).

4. The apparatus of claim I or 2, wherein:

each frame comprises a predefined number of DL subframes at a beginning of the configurable period, and

the DL control information is received during the predefined number of DL subframes.

5. The apparatus of claim 1 or 2, wherein:

each DL control information decoded by the UE comprises a configurable period independent of a previous configurable period, wherein the processing circuitry is further arranged to determine that the UL/DL configuration for a radio frame is same as the UL/DL configuration indicated by the DL control information.

6. The apparatus of claim 1 or 2, wherein:

the DL control information is received during a predefined DL subframe reserved for signaling the UL/DL configuration, and

the predefined DL subframe is associated with, and disposed in one of, a plurality of consecutive frames such that the plurality of consecutive frames share the UL/DL configuration indicated by the predefined DL subframe.

7. The apparatus of claim 6, wherein;

a period to apply the UL/DL configuration indicated by the predefined DL subframe is signaled through use of a dedicated information element (IE) of a DC! format.

8. The apparatus of claim 1 or 2, wherein:

UL scheduling information is carried in a DL downlink control information (DCI) format used for a 5G physical uplink shared channel (xPUSCH) grant, and

UL/DL configurations between frames is independent and based on the UL scheduling information such that one of:

predetermined UL subframes in a previous frame are changed to DL subframes in a current frame, and

predetermined DL subframes in the previous frame are changed to UL subframes in the current frame.

9. The apparatus of claim 1 or 2, wherein the processing circuitry comprises baseband circuitry arranged to:

generate, at a time indicated by the DL control information for a number of DL subframes dependent on the UL/DL configuration, a Hybrid Automatic Repeat request (HARQ) acknowledgement (HARQ-ACK) in at least one UL subframe.

10. The apparatus of claim 9, wherein: the UL DL configuration comprises a transmission frame comprising a plurality of DL transmission periods and at least one UL transmission period, each of the DL and UL transmission periods comprising a plurality of DL and UL subframes, respectively, and

the processing circuitry is further arranged to generate, for transmission on a last UL subfrarne in the transmission frame, the HARQ-ACK feedback for at least one of a DL subfrarne in a first of the DL transmission periods and a DL subfrarne in a DL transmission period of a previous transmission frame.

11. The apparatus of claim 9, wherein:

the UL/DL configuration comprises a transmission frame comprising a plurality of DL transmission periods and at least one UL transmission period, each of the DL and U L transmission periods comprising a plurality of DL and UL subframes, respectively, and

the processing circuitry is further arranged to generate, for transmission on an earliest UL subfrarne in the transmission frame, the HARQ-ACK feedback for a particular DL subfrarne in at least one of a DL transmission period in the transmission frame and in a previous transmission frame, the earliest UL subfrarne being at least K subframes subsequent to the particular DL subfrarne, where K is fixed by specification.

12. The apparatus of claim 9, wherein:

the UL/DL configuration comprises a transmission frame comprising a plurality of DL transmission periods and at least one UL transmission period, each of the DL and UL transmission periods comprising a plurality of DL and UL subframes, respectively, and

the processing circuitry is further arranged to generate, for transmission on one or more UL subframes in the transmission frame, the HARQ-ACK feedback for DL subframes in at least one of a DL transmission period in the transmission frame and in a previous transmission frame, each UL subfrarne being at least K subframes subsequent to a DL subfrarne associated with the HARQ-ACK feedback, where K is fixed by specification, and the HARQ-ACK feedback is distributed as evenly as possible over the one or more UL subframes.

13. The apparatus of claim 1 or 2, further comprising:

an antenna configured to provide communications between the UE and the eNB.

14. An apparatus of an evolved NodeB (eNB) comprising:

a memory; and

processing circuitry in communication with the memory and arranged to: generate, for transmission to a user equipment (UE) in a predetermined downlink (DL) subframe of a configurable period, DL control information indicating a particular TDD uplink (UL)/DL configuration selected from a set of predetermined TDD DL and UL configurations in which the particular UL/DL configuration indicates a ratio between UL and DL subframes for the configurable period; and communicate with the UE based on the particular TDD DL and UL configuration.

15. The apparatus of claim 14, wherein:

each TDD control infomiation generated by the processing circuitry comprises a configurable period independent of a previous configurable period, each configurable period comprising at least one frame.

16. The apparatus of claim 14 or 15, wherein:

a period to apply the UL/DL configuration indicated by the

predetermined DL subframe is signaled in a dedicated information element (IE) of a DCI format.

17. The apparatus of claim 14 or 15, wherein:

UL scheduling information is carried in a DL downlink control information (DCI) format used for a 5G physical uplink shared channel (xPUSCH) grant, and

UL/DL configurations between frames is independent and based on the UL scheduling information such that one of:

predetermined UL subframes in a previous frame are changed to

DL subframes in a current frame, and predetermined DL subframes in the previous frame are changed to UL subframes in the current frame.

18. The apparatus of claim 14 or 15, wherein the processing circuitry is further arranged to:

decode, at a time indicated by the DL control information for a number of DL subframes dependent on the UL DL configuration, a Hybrid Automatic Repeat request (HARQ) acknowledgement (HARQ-ACK) in at least one UL subframe.

19. The apparatus of claim 18, wherein:

the UL/DL configuration comprises a transmission frame comprising a plurality of DL transmission periods and at least one UL transmission period, each of the DL and UL transmission periods comprising a plurality of DL and UL subframes, respectively, and

the processing circuitry is further arranged to decode, for transmission on a last UL subframe in the transmission frame, the HARQ-ACK feedback for at least one of a DL subframe in a first of the DL transmission periods and a DL subframe in a DL transmission period of a previous transmission frame.

20. The apparatus of claim 18, wherein:

the UL DL configuration comprises a transmission frame comprising a plurality of DL transmission periods and at least one UL transmission period, each of the DL and UL transmission periods comprising a plurality of DL and UL subframes, respectively, and

the processing circuitry is further arranged to decode, for transmission on an earliest UL subframe in the transmission frame, the HARQ-ACK feedback for a particular DL subframe in at least one of a DL transmission period in the transmission frame and in a previous transmission frame, the earliest UL subframe being at least K subframes subsequent to the particular DL subframe, where K is fixed by specification.

21. The apparatus of claim 18, wherein : the UL DL configuration comprises a transmission frame comprising a plurality of DL transmission periods and at least one UL transmission period, each of the DL and UL transmission periods comprising a plurality of DL and UL subframes, respectively, and

the processing circuitry is further arranged to decode, for transmission on one or more UL subframes in the transmission frame, the HARQ-ACK feedback for DL subframes in at least one of a DL transmission period in the transmission frame and in a previous transmission frame, each UL subframe being at least K subframes subsequent to a DL subframe associated with the HARQ-ACK feedback, where K is fixed by specification, and the HARQ-ACK feedback is distributed as evenly as possible over the one or more UL subframes.

22. The apparatus of claim 14 or 15, herein:

the DL control information is encoded in a system information block (SIB) or a downlink control information (DC!) format earned by a fifth generation (5G) physical downlink control channel (xPDCCH).

23. A computer-readable storage medium that stores instructions for execution by one or more processors of user equipment (UE), the one or more processors to configure the UE to:

decode DL control information from, an evolved NodeB (eNB), the DL control information indicating a particular TDD uplink (UL)/downlink (DL) configuration selected from a set of predetermined UL/DL configurations in which the particular TDD DL and UL configuration indicates:

a ratio between UL and DL subframes for a configurable period thai is independent of a previous configurable period, and

a location of the UL and DL subframes within a frame; and communicate with the eNB based on the particular UL/DL configuration.

24. The medium of claim 23, wherein:

the DL control information is received during a predefined DL subframe reserved for signaling the UL/DL configuration, the predefined DL subframe is associated with, and disposed in one of, a plurality of consecutive frames such that the plurality of consecutive frames share the UL DL configuration indicated by the predefined DL subframe, and a period to apply the UL/DL configuration indicated by the predefined DL subframe is signaled through use of a dedicated information element (IE) of a DCI format.

25. The medium of claim 23 or 24, wherein:

UL scheduling information is carried in a DL downlink control information (DCI) format used for a 5G physical uplink shared channel (xPUSCH) grant, and

UL/DL configurations between frames is independent and based on the UL scheduling information such that one of:

predetermined UL subframes in a previous frame are changed to DL subframes in a current frame, and

predetermined DL subframes in the previous frame are changed to UL subframes in the current frame.

26. The medium of claim 23 or 24, wherein the processing circuitry is further arranged to:

generate, at a time indicated by the DL control information for a number of DL subframes dependent on the UL/DL configuration, a Hybrid Automatic Repeat request (HARQ) acknowledgement (HARQ-ACK) in at least one UL subframe,

the UL/DL configuration comprises a transmission frame comprising a plurality of DL transmission periods and at least one UL transmission period, each of the DL and UL transmission periods comprising a plurality of DL and UL subframes, respectively, and

the processing circuitry is further arranged to generate one of:

for transmission on a last UL subframe in the transmission frame, the HARQ-ACK feedback for at least one of a DL subframe in a first of the DL transmission periods and a DL subframe in a DL transmission period of a previous transmission frame, for transmission on an earliest UL subframe in the transmission frame, the HARQ-ACK feedback for a particular DL subframe in at least one of a DL transmission period in the transmission frame and in the previous transmission frame, the earliest UL subframe being at least K subframes subsequent to the particular DL subframe, where K is fixed by specification, and

for transmission on one or more UL subframes in the transmission frame, the HARQ-ACK feedback for DL subframes in at least one of the DL transmission period in the transmission frame and in the previous transmission frame, each UL subframe being at least K subframes subsequent to a DL subframe associated with the HARQ-ACK feedback, and the HARQ-ACK feedback is distributed as evenly as possible over the one or more UL subframes.