WO2016141519A1

WO2016141519A1 - Techniques for managing downlink/uplink flexible duplex in a heterogeneous network

Info

Publication number: WO2016141519A1
Application number: PCT/CN2015/073834
Authority: WO
Inventors: Yin Huang; Peng Cheng; Ruiming Zheng; Neng Wang
Original assignee: Qualcomm Incorporated
Priority date: 2015-03-07
Filing date: 2015-03-07
Publication date: 2016-09-15

Abstract

Aspects of the present disclosure generally relate to wireless communications. In some aspects, a device may configure a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications. The device may configure a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation. The device may transmit the one or more TDD communications of the first cell.

Description

TECHNIQUES FOR MANAGING DOWNLINK/UPLINK FLEXIBLE DUPLEX IN A HETEROGENEOUS NETWORK

BACKGROUND

Aspects of the present disclosure generally relate to wireless communications, and more particularly to techniques for managing downlink and/or uplink flexible duplex in a heterogeneous network.

Wireless communication systems are widely deployed to provide various telecommunication services, such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc. ) . Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency divisional multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of a telecommunication standard is Long Term Evolution (LTE) . LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP) . LTE is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, using new spectrum, and integrating with other open standards using OFDMA on the downlink (DL) , SC-FDMA on the uplink (UL) , and multiple-input multiple-output (MIMO) antenna technology.

SUMMARY

In some aspects, a method for wireless communication may include configuring, by a device, a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications. The method may include configuring, by the device, a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation. The method may include transmitting, by the device, the one or more TDD communications of the first cell.

In some aspects, a device for wireless communication may include one or more processors configured to configure a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications. The one or more processors may be configured to configure a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation. The one or more processors may be configured to transmit the one or more TDD communications of the first cell.

In some aspects, a non-transitory computer-readable medium may store computer executable code for wireless communications. The computer executable code may include code for configuring a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications, code for configuring a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation, and code for transmitting the one or more TDD communications of the first cell.

In some aspects, an apparatus for wireless communication may include means for configuring a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications. The apparatus may include means for configuring a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation. The apparatus may include means for transmitting the one or more TDD communications of the first cell.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, and user equipment as substantially described herein with reference to and as illustrated by the accompanying drawings.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purpose of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

Fig. 1 is an illustration of an example wireless communication system, in accordance with various aspects of the present disclosure；

Fig. 2 is a diagram illustrating an example access network in an LTE network architecture, in accordance with various aspects of the present disclosure；

Fig. 3 is a diagram illustrating an example of a downlink (DL) frame structure in LTE, in accordance with various aspects of the present disclosure；

Fig. 4 is a diagram illustrating an example of an uplink (UL) frame structure in LTE, in accordance with various aspects of the present disclosure；

Fig. 5 is a diagram illustrating an example of a radio protocol architecture for a user plane and a control plane in LTE, in accordance with various aspects of the present disclosure；

Fig. 6 is a diagram illustrating example components example components of a communication system including a base station and a UE, in accordance with various aspects of the present disclosure；

Fig. 7 is a diagram illustrating an example of flexible duplex, in accordance with various aspects of the present disclosure；

Fig. 8 is a diagram illustrating an example of configuring a guard band to mitigate interference and protect PUCCH communications during flexible duplex, in accordance with various aspects of the present disclosure；

Fig. 9 is a diagram illustrating another example of configuring a guard band to mitigate interference and protect PUCCH communications during flexible duplex, in accordance with various aspects of the present disclosure；

Fig. 10 is a flow diagram of an example process for configuring a guard band between TDD communications of a first cell and FDD communications of a second cell, in accordance with various aspects of the present disclosure；

Fig. 11 is a flow diagram of another example process for configuring a guard band between TDD communications of a first cell and FDD communications of a second cell, in accordance with various aspects of the present disclosure；

Fig. 12 is a flow diagram of another example process for configuring a guard band between TDD communications of a first cell and FDD communications of a second cell, in accordance with various aspects of the present disclosure； and

Fig. 13 is a flow diagram of another example process for configuring a guard band between TDD communications of a first cell and FDD communications of a second cell, in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with the appended 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 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.

LTE networks may support both frequency division duplex (FDD) operation and time division duplex (TDD) operation, and can be deployed in both paired and unpaired spectrum. For FDD operations, uplink communications and downlink communications use different radio frequency bands, while in TDD operations, the same radio frequency band is shared between uplink and downlink communications. An advantage of TDD is the ability to adjust available time domain resources to either uplink or downlink communications to match the uplink and downlink traffic characteristics of a cell. This may be achieved by changing the duplex switching point (e.g., from downlink to uplink, or from uplink to downlink) and thus moving capacity from downlink to uplink or from uplink to downlink as necessary.

Flexible duplex permits a device (e.g., a base station, a UE, etc. ) or a cell to switch from an FDD operation to a TDD operation for one or more communications, or to switch from a TDD operation to an FDD operation for one or more communications. Flexible duplex permits flexible resource allocation for traffic adaptation. For example, using flexible duplex, spare uplink resources configured for FDD communications may be reconfigured for downlink communications using TDD. In this way, radio resources can be flexibly utilized to satisfy downlink traffic demands with limited available spectrum.

However, reconfiguring a cell to communicate using a TDD operation from an FDD operation may cause interference between base stations, UEs, or other devices. The interference may be co-channel interference, adjacent channel interference, inter-cell interference, inter-symbol interference, or the like. For example, when a first cell switches from an FDD operation to a TDD operation, downlink transmissions on the first cell, intended for a UE, may interfere with communications of a second cell (e.g., in FDD operation) . Furthermore, such switching may cause other types of interference, such as co-channel interference between small cell (e.g., pico cell) base stations configured to use the same channels to communicate with UEs, co-channel or adjacent channel interference between a macro cell base station and a small cell (e.g., pico cell) base station, inter-cell interference between downlink and uplink signals in different cells, interference at a UE due to poor signal-to-interference-plus-noise ratio (SINR) parameters, or the like.

Techniques described herein may manage downlink/uplink flexible duplex in a heterogeneous network by configuring a guard band (e.g., a guard band of resources) between TDD communications of a first cell and FDD communications of a second cell in order to mitigate interference (e.g., as described above) between the first cell and the second cell. In this case, the FDD communications of the second cell may be uplink communications. The second cell may mute (e.g., not configure or blanking) uplink resources allocated for the Physical Uplink Shared Channel (PUSCH) , but may continue to communicate control signaling using resources allocated for the Physical Uplink Control Channel (PUCCH) . The guard band may be configured to mitigate the interference of the PUCCH communications of the second cell that uses an FDD operation, while permitting the first cell to communicate using a TDD operation (e.g., for downlink communications during periods of high downlink traffic) . In this way, network throughput may be increased and interference may be mitigated by utilizing flexible duplex on the first cell, while protecting control signals of the PUCCH on the first cell.

The techniques described herein may be used for one or more of various 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, or other types of networks. A CDMA network may implement a radio access technology (RAT) , such as universal terrestrial radio access (UTRA) , CDMA2000, or the like. UTRA may include wideband CDMA (WCDMA) and/or other variants of CDMA. CDMA2000 may include Interim Standard (IS) -2000, IS-95 and IS-856 standards. IS-2000 may also be referred to as 1x radio transmission technology (1xRTT) , CDMA2000 1X, or the like. A TDMA network may implement a RAT such as global system for mobile communications (GSM) , enhanced data rates for GSM evolution (EDGE) , or GSM/EDGE radio access network (GERAN) . An OFDMA network may implement a RAT such as evolved UTRA (E-UTRA) , ultra mobile broadband (UMB) , Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM, or the like. UTRA and E-UTRA may be part of the universal mobile telecommunication system (UMTS) . 3GPP long-term evolution (LTE) and LTE-Advanced (LTE-A) are example releases of UMTS that use E-UTRA, which employs OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP) . CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the wireless networks and RATs mentioned above as well as other wireless networks and RATs.

Fig. 1 is an illustration of an example wireless communication system 100, in accordance with various aspects of the disclosure. The wireless communication system 100 may include a WWAN network, such as a cellular network, and a WLAN network, such as a Wi-Fi network. The cellular network may include one or more base stations 105, 105-A, one or more UEs 115, 115-A, and a core network 130. The Wi-Fi network may include one or more WLAN access points 135, 135-A (e.g., Wi-Fi access points) and one or more WLAN stations 140, 140-A (e.g., Wi-Fi stations) .

With reference to the cellular network of the wireless communication system 100, the core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations 105, 105-A may interface with the core network 130 through backhaul links 132 (e.g., S1, etc. ) and may perform radio configuration and scheduling for communication with the UEs 115, 115-A, or may operate under the control of a base station controller (not shown) . In various examples, the base stations 105, 105-A may communicate, either directly or indirectly (e.g., through core network 130) , with each other over backhaul links 134 (e.g., X2, etc. ) , which may be wired or wireless communication links.

The base stations 105, 105-A may wirelessly communicate with the UEs 115, 115-A via one or more base station antennas. Each of the base station 105, 105-A sites may provide communication coverage for a respective geographic coverage area 110. In some examples, a base station 105, 105-A may be referred to as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB) , a Home NodeB, a Home eNodeB, or some other suitable terminology. The geographic coverage area 110 for a base station 105, 105-A may be divided into sectors making up a portion of the coverage area (not shown) . The cellular network may include base stations 105, 105-A of different types (e.g., macro and/or small cell base stations) . There may be overlapping geographic coverage areas 110 for different technologies.

In some examples, the cellular network may include an LTE/LTE-A network. In LTE/LTE-A networks, the term evolved Node B (eNB) may be used to describe the base stations 105, 105-A, while the term UE may be used to describe the UEs 115, 115-A. The cellular network may be a Heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station 105, 105-A may provide communication coverage for a macro cell, a small cell, and/or another type of cell. The term “cell” is a 3GPP term that can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc. ) of a carrier or base station, depending on context.

A macro cell may cover a relatively large geographic area (e.g.， several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell may be a lower-powered base station, as compared with a macro cell that may operate in the same or different (e.g., licensed, unlicensed, etc. ) radio frequency spectrum bands as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell may cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A femto cell also may cover a relatively small geographic area (e.g., a home) and may provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG) , UEs for users in the home, and the like) . An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or multiple (e.g., two, three, four, or the like) cells (e.g., component carriers) .

The cellular network may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations 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. The techniques described herein may be used for either synchronous or asynchronous operations.

The cellular network may in some examples include a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use Hybrid ARQ (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115, 115-A and the base stations 105, 105-A or core network 130 supporting radio bearers for the user plane data. At the Physical (PHY) layer, the transport channels may be mapped to Physical channels.

The UEs 115, 115-A may be dispersed throughout the wireless communication system 100, and each UE 115, 115-A may be stationary or mobile. A UE 115, 115-A may also include or be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE 115, 115-A 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, or the like. A UE may be able to communicate with various types of base stations 105, 105-A and network equipment, including macro eNBs, small cell eNBs, relay base stations, or the like.

The communication links 125 shown in wireless communication system 100 may carry downlink (DL) transmissions from a base station 105, 105-A to a UE 115, 115-A, and/or uplink (UL) transmissions from a UE 115, 115-A to a base station 105, 105-A. The downlink transmissions may also be called forward link transmissions, while the uplink transmissions may also be called reverse link transmissions.

In some examples, each communication link 125 may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different sub-carrier and may carry control information (e.g., reference signals, control channels, etc. ) , overhead information, user data, etc. The communication links 125 may transmit bidirectional communications using a frequency division duplexing (FDD) operation (e.g., using paired spectrum resources) or a time division duplexing (TDD) operation (e.g., using unpaired spectrum resources) . Frame structures for FDD operation (e.g., frame structure type 1) and TDD operation (e.g., frame structure type 2) may be defined.

In some aspects of the wireless communication system 100, base stations 105, 105-A and/or UEs 115, 115-A may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations 105, 105-A and UEs 115, 115-A. Additionally or alternatively, base stations 105, 105-A and/or UEs 115, 115-A may employ multiple-input, multiple-output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

The wireless communication system 100 may support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may also be referred to as a component carrier (CC) , a layer, a channel, etc. The terms “carrier, ” “component carrier, ” “cell, ” and “channel” may be used interchangeably herein. A UE 115, 115-A may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation. Carrier aggregation may be used with both FDD and TDD component carriers.

With reference to the Wi-Fi network of the wireless communication system 100, the WLAN access points 135, 135-A may wirelessly communicate with the WLAN stations 140, 140-A via one or more WLAN access point antennas, over one or more communication links 145. In some examples, the WLAN access points 135, 135-A may communicate with the WLAN stations 140, 140-A using one or more Wi-Fi communication standards, such as an Institute of Electrical and Electronics (IEEE) Standard 802.11 (e.g., IEEE Standard 802.11a, IEEE Standard 802.11n, or IEEE Standard 802.11ac) .

In some examples, a WLAN station 140, 140-A may be a cellular phone, a personal digital assistant (PDA) , a wireless communication device, a handheld device, a tablet computer, a laptop computer, or the like. In some examples, an apparatus may include aspects of both a UE 115, 115-A and a WLAN station 140, 140-A, and such an apparatus may communicate with one or more base stations 105, 105-A using a first radio access technology (RAT) (e.g., a cellular RAT or multiple cellular RATs) , and communicate with one or more WLAN access points 135, 135-A using a second RAT (e.g., a Wi-Fi RAT or multiple Wi-Fi RATs) .

In some examples, the base stations 105, 105-A and UEs 115, 115-A may communicate over a licensed radio frequency spectrum band and/or an unlicensed radio frequency spectrum band, whereas the WLAN access points 135, 135-A and WLAN stations 140, 140-A may communicate over the unlicensed radio frequency spectrum band. The unlicensed radio frequency spectrum band may therefore be shared by the base stations 105, 105-A, the UEs 115, 115-A, the WLAN access points 135, 135-A, and/or the WLAN stations 140, 140-A.

The number and arrangement of components shown in Fig. 1 are provided as an example. In practice, wireless communication system 100 may include additional devices, fewer devices, different devices, or differently arranged devices than those shown in Fig. 1. Additionally, or alternatively, a set of devices (e.g., one or more devices) of wireless communication system 100 may perform one or more functions described as being performed by another set of devices of wireless communication system 100.

Fig. 2 is a diagram illustrating an example access network 200 in an LTE network architecture, in accordance with various aspects of the present disclosure. As shown, access network 200 may include a set of eNBs 210 that serve a corresponding set of cellular regions (cells) 220, a set of low power eNBs 230 that serve a corresponding set of cells 240, and a set of UEs 250.

Each eNB 210 may be assigned to a respective cell 220 and may be configured to provide an access point to a RAN. For example, eNB 210 may provide an access point for UE 250 to a RAN (e.g., eNB 210 may correspond to base station 105, shown in Fig. 1) . UE 250 may correspond to UE 115, shown in Fig. 1. Fig. 2 does not illustrate a centralized controller for example access network 200, but access network 200 may use a centralized controller in some aspects. The eNBs 210 may perform radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and network connectivity.

As shown in Fig. 2, one or more low power eNBs 230 may serve respective cells 240, which may overlap with one or more cells 220 served by eNBs 210. The low power eNBs 230 may correspond to base station 105, shown in Fig. 1. A low power eNB 230 may be referred to as a remote radio head (RRH) . The low power eNB 230 may include a femto cell eNB (e.g., home eNB (HeNB) ) , a pico cell eNB, a micro cell eNB, or the like.

A modulation and multiple access scheme employed by access network 200 may vary depending on the particular telecommunications standard being deployed. In LTE applications, OFDM is used on the downlink (DL) and SC-FDMA is used on the uplink (UL) to support both frequency division duplexing (FDD) and time division duplexing (TDD) . The various concepts presented herein are well suited for LTE applications. However, these concepts may be readily extended to other telecommunication standards employing other modulation and multiple access techniques. By way of example, these concepts may be extended to Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB) . EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. As another example, these concepts may also be extended to UTRA employing WCDMA and other variants of CDMA (e.g., such as TD-SCDMA, GSM employing TDMA, E-UTRA, or the like) , UMB, IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM employing OFDMA, or the like. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

The number and arrangement of devices and cells shown in Fig. 2 are provided as an example. In practice, there may be additional devices and/or cells, fewer devices and/or cells, different devices and/or cells, or differently arranged devices and/or cells than those shown in Fig. 2. Furthermore, two or more devices shown in Fig. 2 may be implemented within a single device, or a single device shown in Fig. 2 may be implemented as multiple, distributed devices. Additionally, or alternatively, a set of devices (e.g., one or more devices) shown in Fig. 2 may perform one or more functions described as being performed by another set of devices shown in Fig. 2.

Fig. 3 is a diagram illustrating an example 300 of a downlink (DL) frame structure in LTE, in accordance with various aspects of the present disclosure. A frame (e.g., of 10 ms) may be divided into 10 equally sized sub-frames with indices of 0 through 9. Each sub-frame may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including a resource block (RB) . The resource grid is divided into multiple resource elements. In LTE, a resource block includes 12 consecutive subcarriers in the frequency domain and, for a normal cyclic prefix in each OFDM symbol, 7 consecutive OFDM symbols in the time domain, or 84 resource elements. For an extended cyclic prefix, a resource block includes 6 consecutive OFDM symbols in the time domain and has 72 resource elements. Some of the resource elements, as indicated as R 310 and R 320, include DL reference signals (DL-RS) . The DL-RS include Cell-specific RS (CRS) (also sometimes called common RS) 310 and UE-specific RS (UE-RS) 320. UE-RS 320 are transmitted only on the resource blocks upon which the corresponding physical DL shared channel (PDSCH) is mapped. The number of bits carried by each resource element depends on the modulation scheme. Thus, the more resource blocks that a UE receives and the higher the modulation scheme, the higher the data rate for the UE.

In LTE, an eNB may send a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) for each cell in the eNB. The primary and secondary synchronization signals may be sent in

symbol periods

6 and 5, respectively, in each of

subframes

0 and 5 of each radio frame with the normal cyclic prefix (CP) . The synchronization signals may be used by UEs for cell detection and acquisition. The eNB may send a Physical Broadcast Channel (PBCH) in symbol periods 0 to 3 in slot 1 of subframe 0. The PBCH may carry certain system information.

The eNB may send a Physical Control Format Indicator Channel (PCFICH) in the first symbol period of each subframe. The PCFICH may convey the number of symbol periods (M) used for control channels, where M may be equal to 1, 2 or 3 and may change from subframe to subframe. M may also be equal to 4 for a small system bandwidth, e.g., with less than 10 resource blocks. The eNB may send a Physical HARQ Indicator Channel (PHICH) and a Physical Downlink Control Channel (PDCCH) in the first M symbol periods of each subframe. The PHICH may carry information to support hybrid automatic repeat request (HARQ) . The PDCCH may carry information on resource allocation for UEs and control information for downlink channels. The eNB may send a Physical Downlink Shared Channel (PDSCH) in the remaining symbol periods of each subframe. The PDSCH may carry data for UEs scheduled for data transmission on the downlink.

The eNB may send the PSS, SSS, and PBCH in the center 1.08 MHz of the system bandwidth used by the eNB. The eNB may send the PCFICH and PHICH across the entire system bandwidth in each symbol period in which these channels are sent. The eNB may send the PDCCH to groups of UEs in certain portions of the system bandwidth. The eNB may send the PDSCH to specific UEs in specific portions of the system bandwidth. The eNB may send the PSS, SSS, PBCH, PCFICH, and PHICH in a broadcast manner to all UEs, may send the PDCCH in a unicast manner to specific UEs, and may also send the PDSCH in a unicast manner to specific UEs.

A number of resource elements may be available in each symbol period. Each resource element (RE) may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value. Resource elements not used for a reference signal in each symbol period may be arranged into resource element groups (REGs) . Each REG may include four resource elements in one symbol period. The PCFICH may occupy four REGs, which may be spaced approximately equally across frequency, in symbol period 0. The PHICH may occupy three REGs, which may be spread across frequency, in one or more configurable symbol periods. For example, the three REGs for the PHICH may all belong in symbol period 0 or may be spread in

symbol periods

0, 1, and 2. The PDCCH may occupy 9, 18, 36, or 72 REGs, which may be selected from the available REGs, in the first M symbol periods, for example. Only certain combinations of REGs may be allowed for the PDCCH.

A UE may know the specific REGs used for the PHICH and the PCFICH. The UE may search different combinations of REGs for the PDCCH. The number of combinations to search is typically less than the number of allowed combinations for the PDCCH. An eNB may send the PDCCH to the UE in any of the combinations that the UE will search.

As indicated above, Fig. 3 is provided as an example. Other examples are possible and may differ from what was described above in connection with Fig. 3.

Fig. 4 is a diagram illustrating an example 400 of an uplink (UL) frame structure in LTE, in accordance with various aspects of the present disclosure. The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

A UE may be assigned

resource blocks

410a, 410b in the control section to transmit control information to an eNB. The UE may also be assigned

resource blocks

420a, 420b in the data section to transmit data to the eNB. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. In some aspects, the UE may transmit only data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may span both slots of a subframe and may hop across frequencies.

A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (PRACH) 430. The PRACH 430 carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (e.g., of 1 ms) or in a sequence of few contiguous subframes.

As indicated above, Fig. 4 is provided as an example. Other examples are possible and may differ from what was described above in connection with Fig. 4.

Fig. 5 is a diagram illustrating an example 500 of a radio protocol architecture for a user plane and a control plane in LTE, in accordance with various aspects of the present disclosure. The radio protocol architecture for the UE and the eNB is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer and implements various physical layer signal processing functions. The L1 layer will be referred to herein as the physical layer 510. Layer 2 (L2 layer) 520 is above the physical layer 510 and is responsible for the link between the UE and eNB over the physical layer 510.

In the user plane, the L2 layer 520 includes a media access control (MAC) sublayer 530, a radio link control (RLC) sublayer 540, and a packet data convergence protocol (PDCP) 550 sublayer, which are terminated at the eNB on the network side. Although not shown, the UE may have several upper layers above the L2 layer 520 including a network layer (e.g., IP layer) that is terminated at a packet data network (PDN) gateway on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc. ) .

The PDCP sublayer 550 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 550 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between eNBs. The RLC sublayer 540 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ) . The MAC sublayer 530 provides multiplexing between logical and transport channels. The MAC sublayer 530 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 530 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNB is substantially the same for the physical layer 510 and the L2 layer 520 with the exception that there is no header compression function for the control plane. In some aspects, integrity protection may be provided for the control plane data. The control plane also includes a radio resource control (RRC) sublayer 560 in Layer 3 (L3 layer) . The RRC sublayer 560 is responsible for obtaining radio resources (i.e., radio bearers) and for configuring the lower layers using RRC signaling between the eNB and the UE.

As indicated above, Fig. 5 is provided as an example. Other examples are possible and may differ from what was described above in connection with Fig. 5.

Fig. 6 is an illustration of example components of a communication system 600 including a base station 610 and a UE 615, in accordance with various aspects of the present disclosure. In some aspects, base station 610 may correspond to one or more of the base stations and/or eNBs 105, 105-A, 210, or 230 described with reference to Fig. 1 or 2. In some aspects, UE 615 may correspond to one or more of the UEs 115, 115-A, or 250 described above with reference to Fig. 1 or 2. Base station 610 may be equipped with antennas 634_1-t, and UE 615 may be equipped with antennas 652_1-r, wherein t and r are integers greater than or equal to one.

At base station 610, a base station transmit processor 620 may receive data from a base station data source 612 and control information from a base station controller/processor 640. The control information may be carried on the Physical Broadcast Channel (PBCH) , the Physical Control Format Indicator Channel (PCFICH) , the Physical Hybrid-ARQ Indicator Channel (PHICH) , the Physical Downlink Control Channel (PDCCH) , or the like. The data may be carried on the Physical Downlink Shared Channel (PDSCH) , for example. Base station transmit processor 620 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. Base station transmit processor 620 may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal (RS) . A base station transmit (TX) multiple-input multiple-output (MIMO) processor 630 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to base station modulators/demodulators (MODs/DEMODs) 632_1-t. Each base station modulator/demodulator 632 may process a respective output symbol stream (e.g., for orthogonal frequency-division multiplexing (OFDM) , or the like) to obtain an output sample stream. Each base station modulator/demodulator 632 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators/demodulators 632_1-t may be transmitted via antennas 634_1-t, respectively.

At UE 615, UE antennas 652_1-r may receive the downlink signals from base station 610 and may provide received signals to UE modulators/demodulators (MODs/DEMODs) 654_1-r, respectively. Each UE modulator/demodulator 654 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each UE modulator/demodulator 654 may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A UE MIMO detector 656 may obtain received symbols from all UE modulators/demodulators 654_1-r, and perform MIMO detection on the received symbols, if applicable, and provide detected symbols. A UE reception processor 658 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 615 to a UE data sink 660, and provide decoded control information to a UE controller/processor 680.

On the uplink, at UE 615, a UE transmit processor 664 may receive and process data (e.g., for the Physical Uplink Shared Channel (PUSCH) ) from a UE data source 662 and control information (e.g., for the Physical Uplink Control Channel (PUCCH) ) from UE controller/processor 680. UE transmit processor 664 may also generate reference symbols for a reference signal. The symbols from UE transmit processor 664 may be precoded by a UE TX MIMO processor 666, if applicable, may be further processed by UE modulator/demodulators 654_1-r (e.g., for SC-FDM, etc. ) , and may be transmitted to base station 610. At base station 610, the uplink signals from UE 615 may be received by base station antennas 634, processed by base station modulators/demodulators 632, detected by a base station MIMO detector 636, if applicable, and further processed by a base station reception processor 638 to obtain decoded data and control information sent by UE 615. Base station reception processor 638 may provide the decoded data to a base station data sink 646 and the decoded control information to base station controller/processor 640.

Base station controller/processor 640 and UE controller/processor 680 may direct the operation at base station 610 and UE 615, respectively. Base station controller/processor 640 and/or other processors and modules at base station 610 may perform or direct, for example, execution of various processes for the techniques described herein. UE controller/processor 680 and/or other processors and modules at UE 615 may also perform or direct, for example, execution of one or more blocks illustrated in Fig. 10, Fig. 11, Fig. 12, Fig. 13, and/or other processes for the techniques described herein. A base station memory 642 and a UE memory 682 may store data and program codes for base station 610 and UE 615, respectively. A scheduler 644 may schedule UEs 615 for data transmission on the downlink and/or uplink.

In one configuration, base station 610 may include means for generating a compact Downlink Control Information (DCI) for at least one of uplink (UL) or downlink (DL) transmissions, wherein the compact DCI comprises a reduced number of bits when compared to certain standard DCI formats； and means for transmitting the DCI. In one aspect, the aforementioned means may be base station controller/processor 640, base station memory 642, base station transmit processor 620, base station modulators/demodulators 632, and/or base station antennas 634 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means. In one configuration, UE 615 may include means for receiving compact Downlink Control Information (DCI) for at least one of uplink (UL) or downlink (DL) transmissions, wherein the DCI comprises a reduced number of bits of a standard DCI format； and means for processing the DCI. In one aspect, the aforementioned means may be UE controller/processor 680, UE memory 682, UE reception processor 658, UE MIMO detector 656, UE modulators/demodulators 654, and/or UE antennas 652 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.

The number and arrangement of components shown in Fig. 6 are provided as an example. In practice, there may be additional components, fewer components, different components, or differently arranged components than those shown in Fig. 6. Furthermore, two or more components shown in Fig. 6 may be implemented within a single component, or a single components shown in Fig. 6 may be implemented as multiple, distributed components. Additionally, or alternatively, a set of components (e.g.， one or more components) shown in Fig. 6 may perform one or more functions described as being performed by another set of components shown in Fig. 6.

Fig. 7 is a diagram illustrating an example 700 of flexible duplex, in accordance with various aspects of the present disclosure. As shown in Fig. 7, and by reference number 710, a first cell (e.g., configured by a first base station 610) , shown as “Cell A, ” uses an FDD operation. Cell A may configure uplink communications (e.g., may configure resources for the PUSCH and/or the PUCCH) to be unmuted during a T_ON time period 720, and may configure uplink communications (e.g., may configure resources for the PUSCH) be muted during a T_OFF time period 730. For example, Cell A may mute (e.g., by not configuring resources for, or by blanking) uplink PUSCH communications during the T_OFF time period 730. A muted communication may refer to a communication transmitted with reduced energy, a communication transmitted with zero energy, a communication for which resources are not configured (e.g., a communication for which PUSCH resources are not configured, a communication for which PUCCH resources are not configured, etc. ) . In some aspects, base station 610 may configure the muted communication by preventing resources from being granted to UE 615 for the communication (e.g., on the PUSCH) , by granting resources to UE 615 and instructing UE 615 to transmit communications associated with the resources with reduced energy or zero energy, or the like. As shown by reference number 740, a second cell (e.g., configured by a second base station 610) , shown as “Cell B, ” is capable of flexible duplex. During T_OFF time period 730, Cell B may configure the second cell for a TDD operation rather than an FDD operation.

For example, and as shown by reference number 750, a large quantity (e.g., greater than a threshold) of downlink data packets may arrive in Cell B. As shown by reference number 760, during the T_ON time period 720 of Cell A, Cell B may not switch to the TDD operation, despite the heavy downlink traffic, to prevent interference with Cell A. Cell A and Cell B may negotiate via a backhaul link (e.g., X2 interface) for a T_OFF time period in order for Cell B to transmit the large quantity of downlink data packets without interference from Cell A. As shown by reference number 770, during the T_OFF time period, Cell B switches to the TDD operation to transmit the downlink packets. Cell B may determine a start time and/or an end time of the T_ON time period and/or the T_OFF time period based at least in part on radio resource control (RRC) information. To mitigate interference between communications of Cell B using the TDD operation and communications of Cell A using the FDD operation, a guard band may be configured between communications associated with Cell A (e.g., PUCCH communications utilizing an FDD uplink frequency band) and communications associated with Cell B (e.g., TDD communications, which could be downlink or uplink communications, as shown) , as described in more detail below.

As indicated above, Fig. 7 is provided as an example. Other examples are possible and may differ from what was described in connection with Fig. 7.

Fig. 8 is a diagram illustrating an example 800 of configuring a guard band to mitigate interference and protect PUCCH communications during flexible duplex, in accordance with various aspects of the present disclosure. Fig. 8 shows an example of using different bandwidths of a radio frequency (RF) band 810 for TDD communications and FDD communications during flexible duplex.

As shown in Fig. 8, a guard band may be configured between TDD communications of a first cell (e.g., a pico cell, or another type of cell) and FDD communications of a second cell (e.g., a macro cell, or another type of cell) . In some aspects, the first cell and the second cell may be configured to operate in a radio frequency (RF) band 810. The first cell may use a first bandwidth 820 of RF band 810 (e.g., an entirety of sub-bands of RF band 810) for FDD communications, and the second cell may use a second bandwidth 830 of RF band 810 (e.g., a portion of the sub-bands of RF band 810) for TDD communications. In some aspects, the second bandwidth 830 may be smaller than the first bandwidth 820. For example, the first bandwidth 820 may be 20 Megahertz (MHz) , and the second bandwidth 830 may be less than 20 MHz (e.g., 10 MHz, 15 MHz) , etc. The remaining bandwidth 840, which may be a difference between the first bandwidth 820 and the second bandwidth 830 (e.g. 10 MHz, 5 MHz, etc. ) , may be used for the guard band, as shown.

In other words, the guard band may be configured by configuring a first sub-band 850 of RF band 810 for TDD communications (e.g., associated with the second cell) , by configuring a second sub-band 860 of RF band 810 for FDD communications (e.g., associated with the first cell) , and configuring a third sub-band 870 of RF band 810 for the guard band between the first sub-band 850 and the second sub-band 860. A sub-band of RF band 810 may be contiguous (e.g., as shown by a contiguous first sub-band 850) or may be non-contiguous (e.g., as shown by non-contiguous second sub-band 860 and non-contiguous third sub-band 870) . In some aspects, the first sub-band 850, the second sub-band 860, and the third sub-band 870 may be non-overlapping sub-bands of RF band 810.

The first sub-band 850 may be used by the second cell for TDD communications, and may be smaller (e.g., may use less bandwidth) than was used by the second cell for uplink FDD communications prior to switching to the TDD operation using flexible duplex. The second sub-band 860 may be used by the first cell for PUCCH communications using the FDD operation (e.g., resources for non-PUCCH communications, such as PUSCH communications, may be muted by the first cell, as described above in connection with the T_OFF time period 730 shown in Fig. 7) . The third sub-band 870 may be used for a guard band that protects the PUCCH communications from interference with the TDD communications.

By configuring the guard band in this manner, the TDD communications may be configured to use different sized bandwidths without changing the TDD waveform. This configuration may limit an amount of downlink offloading achieved by flexible duplex by limiting the bandwidth of TDD communications used for downlink offloading.

As indicated above, Fig. 8 is provided as an example. Other examples are possible and may differ from what was described in connection with Fig. 8.

Fig. 9 is a diagram illustrating an example 900 of configuring a guard band to mitigate interference and protect PUCCH communications during flexible duplex, in accordance with various aspects of the present disclosure. Figs. 9 show an example of muting resources for communications on a radio frequency (RF) band to create a guard band between FDD communications and TDD communications during flexible duplex.

As shown in Fig. 9, a first cell that performs a TDD operation may mute resources (e.g., resource blocks) associated with communications at the edges of the system bandwidth. For example, and as shown by reference number 905, the first cell may mute resources associated with control communications (e.g., on the PUCCH and/or the PDCCH) , and may mute resources associated with one or more data communications (e.g., on the PUSCH and/or the PDSCH) at the edge of the bandwidth reserved for data communications. In some aspects, a first base station 610, associated with the first cell, may configure the edge resources to be muted by preventing the edge resources from being granted to UE 615, by instructing UE 615 to transmit communications associated with the edge resources with reduced energy or zero energy, or the like.

As shown by reference number 910, a second cell that performs an FDD operation may mute resources (e.g., resource blocks) associated with PUSCH communications. In some aspects, a second base station 610, associated with the second cell, may configure the PUSCH resources to be muted by preventing the PUSCH resources from being granted to UE 615, by instructing UE 615 to transmit communications associated with the PUSCH resources with reduced energy or zero energy, or the like.

As shown by reference number 915, overlapping muted resources from the first cell and the second cell may form a muted sub-band of an RF band associated with the cell, which may act as a guard band between the TDD data communications (e.g., on the PUSCH and/or the PDSCH) and the FDD control communications (e.g., on the PUCCH) . While the overlapping muted resources are shown as muted data resources on the first cell and muted data resources on the second cell, the overlapping muted resources that form the guard band may be different resources in some aspects. For example, the overlapping muted resources may be muted control resources on the first cell and muted control resources on the second cell, in some aspects.

By configuring the guard band in this manner, flexible downlink offloading may be achieved using flexible duplex, and FDD PUCCH communications may be protected from interference with TDD communications. In some aspects, the TDD communications and the FDD communications may be orthogonal (e.g., in the frequency domain) . In this way, in-band inter-carrier interference, caused by non-orthogonal FDD communications and TDD communications, may be mitigated. In some aspects, the TDD communications and the FDD communication may be made orthogonal during transmission using an FFT component. When SC-FDMA is used for downlink TDD communications during flexible duplex, the downlink waveform need not be modified for orthogonality with FDD PUCCH communications (e.g., which also use SC-FDMA) . However, when OFDMA is used for downlink TDD communications during flexible duplex, a half-subcarrier shift may be applied to OFDM modulation to guarantee that the final modulated waveform is orthogonal to FDD PUCCH communications using SC-FDMA.

In some aspects, the first cell may listen to the second cell to determine a timing advance adjustment for the TDD communications, and may transmit the TDD communications based at least in part on the timing advance adjustment. Additionally, or alternatively, the first cell may use an extended cyclic prefix, when transmitting the TDD communications, to protect the TDD communications against time domain collision with other TDD communications. Additionally, or alternatively, the first cell may apply time domain windowing when transmitting the TDD communications, and/or the second cell may apply frequency domain windowing when transmitting the FDD communications. In this way, interference between the TDD communications and the FDD communications may be mitigated. For example, a lack of synchronization between TDD communications associated with the first cell and other TDD communications associated with UEs 615, which may cause inter-symbol interference at the Micro Cell, may be mitigated.

As indicated above, Fig. 9 is provided as an example. Other examples are possible and may differ from what was described in connection with Fig. 9.

Fig. 10 is a flow diagram of an example process 1000 for configuring a guard band between TDD communications of a first cell and FDD communications of a second cell, in accordance with various aspects of the present disclosure. In some aspects, one or more process blocks of Fig. 10 may be performed by base station 610. In some aspects, one or more process blocks of Fig. 10 may be performed by UE 615.

As shown in Fig. 10, process 1000 may include configuring a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications (block 1010) . For example, base station 610, associated with a first cell, may configure the first cell, using flexible duplex, from communicating using an FDD operation to communicating using a TDD operation. To mitigate interference caused by TDD communications (e.g., communicated using the TDD operation) of the first cell, base station 610 may configure a guard band between the TDD communications and FDD communications (e.g., communicated using the FDD operation) of a second cell, as described in more detail elsewhere herein.

As shown in Fig. 10, process 1000 may include configuring a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation (block 1020) . For example, base station 610 may configure a guard band between the one or more TDD communications and the one or more FDD communications to protect the one or more FDD communications from interference from the one or more TDD communications. In some aspects, the one or more FDD communications may be one or more PUCCH communications associated with the second cell, and the guard band may protect the one or more PUCCH communications.

In some aspects, base station 610 may configure the guard band by configuring a first sub-band of an RF band, associated with the first cell, for the one or more TDD communications of the first cell, by configuring a second sub-band of the RF band for the one or more FDD communications of the second cell, and configuring a third sub-band of the RF band for the guard band between the one or more TDD communications and the one or more FDD communications, as described in more detail elsewhere herein (e.g., in connection with Fig. 12) .

In some aspects, base station 610 may configure the guard band by muting one or more resources (e.g., for TDD communications) , of the first cell, associated with a sub-band of the RF band used for one or more FDD communications of the second cell, or by muting one or more resources (e.g., for TDD communications) associated with a sub-band of the RF band used for the guard band, as described in more detail elsewhere herein (e.g., in connection with Fig. 13) .

As shown in Fig. 10, process 1000 may include transmitting the one or more TDD communications of the first cell (block 1030) . For example, base station 610 may transmit the one or more TDD communications, via the first cell, using the TDD operation. In some aspects, the one or more TDD communications may include one or more downlink communications (e.g., via the PDSCH, the PDCCH, etc. ) . Additionally, or alternatively, the one or more TDD communications may include one or more uplink communications (e.g., via the PUSCH, the PUCCH, etc. ) . Base station 610 may configure the guard band such that when the one or more TDD communications of the first cell are transmitted, interference is mitigated between the one or more TDD communications and the one or more FDD communications of the second cell.

Although Fig. 10 shows example blocks of process 1000, in some aspects, process 1000 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 10. Additionally, or alternatively, two or more of the blocks of process 1000 may be performed in parallel.

Fig. 11 is a flow diagram of another example process 1100 for configuring a guard band between TDD communications of a first cell and FDD communications of a second cell, in accordance with various aspects of the present disclosure. In some aspects, one or more process blocks of Fig. 11 may be performed by base station 610. In some aspects, one or more process blocks of Fig. 11 may be performed by UE 615.

As shown in Fig. 11, process 1100 may include detecting a start time of a time period for configuring a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation (block 1110) . For example, base station 610 may detect a start time of a time period during which flexible duplex may be implemented to switch from an FDD operation to a TDD operation for a first cell. In some aspects, base station 610 may receive remote radio control (RRC) information that identifies the start time of the time period, a pattern that indicates a start time of the time period, or the like. For example, base station 610 may receive the RRC information from another base station 610 associated with the second cell, which may use the FDD operation to communicate. Base station 610 may detect the start time based at least in part on the RRC information.

As shown in Fig. 11, process 1100 may include configuring the first cell for the TDD operation from the FDD operation for one or more TDD communications (block 1120) . For example, base station 610 may configure the first cell for the TDD operation from the FDD operation based at least in part on detecting the start time. Additionally, or alternatively, base station 610 may configure the first cell for the TDD operation from the FDD operation for one or more TDD communications, as described above in connection with block 1010 of Fig. 10.

As shown in Fig. 11, process 1100 may include configuring a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation (block 1130) , and transmitting the one or more TDD communications of the first cell (block 1140) . For example, base station 610 may configure the guard band between the one or more TDD communications and the one or more FDD communications, as described above in connection with block 1020 of Fig. 10. Additionally, or alternatively, base station 610 may transmit the one or more TDD communications, as described above in connection with block 1030 of Fig. 10.

By detecting the start time before configuring the first cell for the TDD operation and before transmitting the one or more TDD communications, base station 610 may transmit the TDD communications during a time period when the second cell is not transmitting FDD communications, or during a time period when the second cell has muted one or more FDD communications (e.g., when a base station 610, associated with the second cell, has muted FDD communications on the PUSCH) . In this way, base station 610 may mitigate interference between the TDD communications and the FDD communications.

Although Fig. 11 shows example blocks of process 1100, in some aspects, process 1100 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 11. Additionally, or alternatively, two or more of the blocks of process 1100 may be performed in parallel.

Fig. 12 is a flow diagram of another example process 1200 for configuring a guard band between TDD communications of a first cell and FDD communications of a second cell, in accordance with various aspects of the present disclosure. In some aspects, one or more process blocks of Fig. 12 may be performed by base station 610. In some aspects, one or more process blocks of Fig. 12 may be performed by UE 615.

As shown in Fig. 12, process 1200 may include configuring a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications (block 1210) . For example, base station 610 may configure the first cell for the TDD operation from the FDD operation for one or more TDD communications, as described above in connection with block 1010 of Fig. 10.

As shown in Fig. 12, process 1200 may include configuring a first sub-band of a radio frequency band for the one or more TDD communications of the first cell (block 1220) , configuring a second sub-band of the radio frequency band for one or more FDD communications of a second cell, wherein the second cell uses the FDD operation (block 1230) , and configuring a third sub-band of the radio frequency band for a guard band between the one or more TDD communications and the one or more FDD communications (block 1240) .

For example, the first cell may be associated with an RF band used for communications on the first cell. In some aspects, base station 610 may configure a first sub-band of the RF band for the one or more TDD communications of the first cell. In some aspects, base station 610 may configure a second sub-band of the RF band for one or more FDD communications of a second cell (e.g., one or more PUCCH communications that use the FDD operation) . The second cell may use the FDD operation to communicate (e.g., with one or more UEs 615) . In some aspects, base station 610 may configure a third sub-band of the RF band for a guard band between the one or more TDD communications and the one or more FDD communications. In this way, base station 610 may mitigate interference between the one or more TDD communications and the one or more FDD communications.

As shown in Fig. 12, process 1200 may include transmitting the one or more TDD communications via the first sub-band of the radio frequency band (block 1250) . For example, base station 610 may transmit the one or more TDD communications, as described above in connection with block 1030 of Fig. 10. In some aspects, base station 610 may transmit the one or more TDD communications via the first sub-band of the RF band. In this way, the second sub-band may be used for FDD communications of the second cell, and the third sub-band may be used for a guard band between the one or more TDD communications and the one or more FDD communications, thereby mitigating interference between the one or more TDD communications and the one or more FDD communications.

Although Fig. 12 shows example blocks of process 1200, in some aspects, process 1200 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 12. Additionally, or alternatively, two or more of the blocks of process 1200 may be performed in parallel.

Fig. 13 is a flow diagram of another example process 1300 for configuring a guard band between TDD communications of a first cell and FDD communications of a second cell, in accordance with various aspects of the present disclosure. In some aspects, one or more process blocks of Fig. 13 may be performed by base station 610. In some aspects, one or more process blocks of Fig. 13 may be performed by UE 615.

As shown in Fig. 13, process 1300 may include configuring a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications (block 1310) . For example, base station 610 may configure the first cell for the TDD operation from the FDD operation for one or more TDD communications, as described above in connection with block 1010 of Fig. 10.

As shown in Fig. 13, process 1300 may include muting at least one resource of at least one TDD communication, of the one or more TDD communications of the first cell, associated with a sub-band of a radio frequency band used for one or more FDD communications of a second cell or associated with a sub-band of the radio frequency band used for a guard band (block 1320) . For example, the first cell may be associated with an RF band used for communications on the first cell. In some aspects, base station 610 may mute at least one resource for at least one TDD communication associated with a sub-band of the RF band. For example, base station 610 may mute a resource associated with a sub-band of the RF band used for FDD communications of a second cell. Additionally, or alternatively, base station 610 may mute a resource associated with a sub-band of the RF band used for a guard band between the one or more TDD communications and the one or more FDD communications. In some aspects, base station 610 may mute an edge resource within a threshold of an edge of the RF band. Additionally, or alternatively, UE 615 may mute a resource (e.g., based at least in part on an instruction received from base station 610) .

In some aspects, at least one resource, for at least one FDD communication of the one or more FDD communications, may be muted (e.g., by another base station 610 and/or UE 615 associated with the second cell) . For example, base station 610 and/or UE 615 may mute a resource for an FDD communication on a channel other than the PUCCH (e.g., may mute a resource of the PUSCH) . In some aspects, base station 610 and/or UE 615, associated with the second cell, may mute a resource associated with a sub-band of the RF band used for the one or more TDD communications. Additionally, or alternatively, base station 610 and/or UE 615, associated with the second cell, may mute a resource associated with a sub-band of the RF band used for the guard band.

In some aspects, one or more first resources, associated with one or more TDD communications, may be unmuted on a first sub-band of the RF band, may be muted on a second sub-band of the RF band associated with the one or more FDD communications, and may be muted on a third sub-band of the RF band used for the guard band. Additionally, or alternatively, one or more second resources, associated with the one or more FDD communications, may be unmuted on the second sub-band of the RF band, and may be muted on the first sub-band of the RF band and the third sub-band of the RF band. In this way, the one or more first resources and the one or more second resources may be muted on the third sub-band of the RF band, which may correspond to the guard band.

As shown in Fig. 13, process 1300 may include transmitting the one or more TDD communications of the first cell (block 1330) . For example, base station 610 may transmit the one or more TDD communications, as described above in connection with block 1030 of Fig. 10. In some aspects, the one or more TDD communications may be orthogonal to the one or more FDD communications. In some aspects, base station 610 may transmit the one or more TDD communications based at least in part on a timing advance adjustment determined based at least in part on listening to the second cell. In some aspects, base station 610 may transmit the one or more TDD communications using an extended cyclic prefix. In some aspects, base station 610 may transmit the one or more communications using time domain windowing. Additionally, or alternatively, the one or more FDD communications may be transmitted using frequency domain windowing.

By muting resources of one or more TDD communications and one or more FDD communications on a common sub-band of the RF band (e.g., a common sub-band corresponding to the guard band) , base station (s) 105 may mitigate interference between the one or more TDD communications and the one or more FDD communications.

Although Fig. 13 shows example blocks of process 1300, in some aspects, process 1300 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 13. Additionally, or alternatively, two or more of the blocks of process 1300 may be performed in parallel.

Techniques described herein may mitigate interference caused by flexible duplex by creating a guard band between one or more TDD communications and one or more FDD communications. In this way, a network (e.g., an LTE network) may better utilize network resources.

The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the aspects.

As used herein, the term component is intended to be broadly construed as hardware, firmware, or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, or a combination of hardware and software.

Some aspects are described herein in connection with thresholds. As used herein, satisfying a threshold may refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, or the like.

It will be apparent that systems and/or methods, described herein, may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods were described herein without reference to specific software code—it being understood that software and hardware can be designed to implement the systems and/or methods based on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of possible aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of possible aspects includes each dependent claim in combination with every other claim in the claim set. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a； b； c； a and b； a and c； b and c； and a, b and c.

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more. ” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, etc. ) , and may be used interchangeably with “one or more. ” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has, ” “have, ” “having, ” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

A method for wireless communication, comprising:

configuring, by a device, a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications；

configuring, by the device, a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation； and

transmitting, by the device, the one or more TDD communications of the first cell.
The method of claim 1, wherein configuring the guard band comprises:

configuring a first sub-band of a radio frequency band for the one or more TDD communications of the first cell；

configuring a second sub-band of the radio frequency band for the one or more FDD communications of the second cell； and

configuring a third sub-band of the radio frequency band for the guard band.
The method of claim 2, wherein transmitting the one or more TDD communications comprises:

transmitting the one or more TDD communications via the first sub-band of the radio frequency band.
The method of claim 1, wherein configuring the guard band comprises:

muting at least one resource of at least one TDD communication, of the one or more TDD communications of the first cell, associated with a sub-band of a radio frequency band used for the one or more FDD communications of the second cell or associated with a sub-band of the radio frequency band used for the guard band.
The method of claim 4, wherein the at least one resource is within a threshold of an edge of the radio frequency band.
The method of claim 1, wherein at least one resource of at least one TDD communication, of the one or more TDD communications of the first cell, is muted on the guard band.
The method of claim 1, wherein at least one resource of at least one FDD communication, of the one or more FDD communications of the second cell, is muted on the guard band.
The method of claim 1, wherein the one or more FDD communications are one or more communications on a Physical Uplink Control Channel (PUCCH) .
The method of claim 1, wherein the one or more FDD communications include a muted FDD communication on a channel other than a Physical Uplink Control Channel (PUCCH) .
The method of claim 1, further comprising:

detecting a start of a time period for configuring the first cell for the TDD operation from the FDD operation； and

wherein configuring the first cell comprises:

configuring the first cell based at least in part on detecting the start of the time period.
The method of claim 1, wherein the one or more TDD communications of the first cell are orthogonal to the one or more FDD communications of the second cell.
The method of claim 1, wherein transmitting the one or more TDD communications comprises:

transmitting the one or more TDD communications based at least in part on a timing advance adjustment determined based at least in part on listening to communications of the second cell.
The method of claim 1, wherein transmitting the one or more TDD communications comprises:

transmitting the one or more TDD communications using an extended cyclic prefix.
The method of claim 1, wherein transmitting the one or more TDD communications comprises:

transmitting the one or more TDD communications using time domain windowing.
The method of claim 1, wherein the one or more FDD communications are transmitted using frequency domain windowing.
The method of claim 1, wherein the device is a base station.
A device for wireless communication, comprising:

one or more processors to:

configure a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications；

configure a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation； and

transmit the one or more TDD communications of the first cell.
The device of claim 17, wherein the one or more processors, when configuring the guard band, are further to:

configure a first sub-band of a radio frequency band for the one or more TDD communications of the first cell；

configure a second sub-band of the radio frequency band for the one or more FDD communications of the second cell； and

configure a third sub-band of the radio frequency band for the guard band.
The device of claim 18, wherein the one or more processors, when transmitting the one or more TDD communications, are further to:

transmit the one or more TDD communications via the first sub-band of the radio frequency band.
The device of claim 17, wherein the one or more processors, when configuring the guard band, are further to:

mute at least one resource of at least one TDD communication, of the one or more TDD communications of the first cell, associated with a sub-band of a radio frequency band used for the one or more FDD communications of the second cell or associated with a sub-band of the radio frequency band used for the guard band.
The device of claim 20, wherein the at least one resource is within a threshold of an edge of the radio frequency band.
The device of claim 17, wherein at least one resource of at least one TDD communication, of the one or more TDD communications of the first cell, is muted on the guard band.
The device of claim 17, wherein at least one resource of at least one FDD communication, of the one or more FDD communications of the second cell, is muted on the guard band.
The device of claim 17, wherein the one or more FDD communications are one or more communications on a Physical Uplink Control Channel (PUCCH) .
The device of claim 17, wherein the one or more FDD communications include a muted FDD communication on a channel other than a Physical Uplink Control Channel (PUCCH) .
The device of claim 17, wherein the one or more processors are further to:

detect a start of a time period for configuring the first cell for the TDD operation from the FDD operation； and

wherein the one or more processors, when configuring the first cell, are further to:

configure the first cell based at least in part on detecting the start of the time period.
The device of claim 17, wherein the one or more TDD communications of the first cell are orthogonal to the one or more FDD communications of the second cell.
The device of claim 17, wherein the one or more processors, when transmitting the one or more TDD communications, are further to:

transmit the one or more TDD communications based at least in part on a timing advance adjustment determined based at least in part on listening to communications of the second cell.
The device of claim 17, wherein the one or more processors, when transmitting the one or more TDD communications, are further to:

transmit the one or more TDD communications using an extended cyclic prefix.
The device of claim 17, wherein the one or more processors, when transmitting the one or more TDD communications, are further to:

transmit the one or more TDD communications using time domain windowing.
The device of claim 17, wherein the one or more FDD communications are transmitted using frequency domain windowing.
The device of claim 17, wherein the device is a base station.
A non-transitory computer-readable medium storing computer executable code for wireless communication, comprising:

code for configuring a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications；

code for configuring a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation； and

code for transmitting the one or more TDD communications of the first cell.
The computer-readable medium of claim 33, wherein the code for configuring the guard band further comprises:

code for configuring a first sub-band of a radio frequency band for the one or more TDD communications of the first cell；

code for configuring a second sub-band of the radio frequency band for the one or more FDD communications of the second cell； and

code for configuring a third sub-band of the radio frequency band for the guard band.
The computer-readable medium of claim 34, wherein the code for transmitting further comprises:

code for transmitting the one or more TDD communications via the first sub-band of the radio frequency band.
The computer-readable medium of claim 33, wherein the code for configuring the guard band further comprises:

code for muting at least one resource of at least one TDD communication, of the one or more TDD communications of the first cell, associated with a sub-band of a radio frequency band used for the one or more FDD communications of the second cell or associated with a sub-band of the radio frequency band used for the guard band.
The computer-readable medium of claim 36, wherein the at least one resource is within a threshold of an edge of the radio frequency band.
The computer-readable medium of claim 33, wherein at least one resource of at least one TDD communication, of the one or more TDD communications of the first cell, is muted on the guard band.
The computer-readable medium of claim 33, wherein at least one resource of at least one FDD communication, of the one or more FDD communications of the second cell, is muted on the guard band.
The computer-readable medium of claim 33, wherein the one or more FDD communications are one or more communications on a Physical Uplink Control Channel (PUCCH) .
The computer-readable medium of claim 33, wherein the one or more FDD communications include a muted FDD communication on a channel other than a Physical Uplink Control Channel (PUCCH) .
The computer-readable medium of claim 33, further comprising:

code for detecting a start of a time period for configuring the first cell for the TDD operation from the FDD operation； and

code for configuring the first cell based at least in part on detecting the start of the time period.
The computer-readable medium of claim 33, wherein the one or more TDD communications of the first cell are orthogonal to the one or more FDD communications of the second cell.
The computer-readable medium of claim 33, wherein the code for transmitting the one or more TDD communications further comprises:

code for transmitting the one or more TDD communications based at least in part on a timing advance adjustment determined based at least in part on listening to communications of the second cell.
The computer-readable medium of claim 33, wherein the code for transmitting the one or more TDD communications, further comprises:

code for transmitting the one or more TDD communications using an extended cyclic prefix.
The computer-readable medium of claim 33, further comprising:

code for transmitting the one or more TDD communications using time domain windowing.
The computer-readable medium of claim 33, wherein the one or more FDD communications are transmitted using frequency domain windowing.
The computer-readable medium of claim 33, wherein the device is a base station.
An apparatus for wireless communication, comprising:

means for configuring a first cell for a time division duplex (TDD) operation from a frequency division duplex (FDD) operation for one or more TDD communications；

means for configuring a guard band between the one or more TDD communications of the first cell and one or more FDD communications of a second cell, wherein the second cell uses the FDD operation； and

means for transmitting the one or more TDD communications of the first cell.
The apparatus of claim 49, wherein the means for configuring the guard band comprises:

means for configuring a first sub-band of a radio frequency band for the one or more TDD communications of the first cell；

means for configuring a second sub-band of the radio frequency band for the one or more FDD communications of the second cell； and

means for configuring a third sub-band of the radio frequency band for the guard band.
The apparatus of claim 50, wherein the means for transmitting the one or more TDD communications comprises:

means for transmitting the one or more TDD communications via the first sub-band of the radio frequency band.
The apparatus of claim 49, wherein the means for configuring the guard band comprises:

means for muting at least one resource of at least one TDD communication, of the one or more TDD communications of the first cell, associated with a sub-band of a radio frequency band used for the one or more FDD communications of the second cell or associated with a sub-band of the radio frequency band used for the guard band.
The apparatus of claim 52, wherein the at least one resource is within a threshold of an edge of the radio frequency band.
The apparatus of claim 49, wherein at least one resource of at least one TDD communication, of the one or more TDD communications of the first cell, is muted on the guard band.
The apparatus of claim 49, wherein at least one resource of at least one FDD communication, of the one or more FDD communications of the second cell, is muted on the guard band.
The apparatus of claim 49, wherein the one or more FDD communications are one or more communications on a Physical Uplink Control Channel (PUCCH) .
The apparatus of claim 49, wherein the one or more FDD communications include a muted FDD communication on a channel other than a Physical Uplink Control Channel (PUCCH) .
The apparatus of claim 49, further comprising:

means for detecting a start of a time period for configuring the first cell for the TDD operation from the FDD operation； and

wherein the means for configuring the first cell comprises:

means for configuring the first cell based at least in part on detecting the start of the time period.
The apparatus of claim 49, wherein the one or more TDD communications of the first cell are orthogonal to the one or more FDD communications of the second cell.
The apparatus of claim 49, wherein the means for transmitting the one or more TDD communications comprises:

means for transmitting the one or more TDD communications based at least in part on a timing advance adjustment determined based at least in part on listening to communications of the second cell.
The apparatus of claim 49, wherein the means for transmitting the one or more TDD communications comprises:

means for transmitting the one or more TDD communications using an extended cyclic prefix.
The apparatus of claim 49, wherein the means for transmitting the one or more TDD communications comprises:

means for transmitting the one or more TDD communications using time domain windowing.
The apparatus of claim 49, wherein the one or more FDD communications are transmitted using frequency domain windowing.
The apparatus of claim 49, wherein the apparatus is a base station.