BR112017002123B1 - TECHNIQUES FOR INDICATING A FRAME FORMAT FOR TRANSMISSIONS USING UNLICENSED RADIO FREQUENCY SPECTRUM BANDS - Google Patents

Abstract

The present disclosure, for example, relates to one or more techniques for indicating a frame format for transmissions using unlicensed radio frequency spectrum bands. A UE may receive, from a base station, a frame format indicator associated with a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band. The UE may determine a time division duplexing (TDD) configuration for the transmission opportunity based, at least in part, on the frame format indicator.

Description

CROSS REFERENCES

[0001] This Patent Application claims the priority of U.S. Patent Application 14/807,069, by Yerramalli et al., entitled “Techniques for Indicating a Frame Format for Transmissions Using Unlicensed Radio Frequency Spectrum Bands”, filed on July 23 2015, and Provisional Patent Application No. 62/032,953, by Yerramalli et al., entitled “Techniques for Indicating a Frame Format for Transmissions Using Unlicensed Radio Frequency Spectrum Bands”, filed on August 4, 2014; wherein each of them is attributed to the present applicant.

FIELD OF REVELATION

[0002] The present disclosure, for example, relates to wireless communication systems and, more particularly, to techniques for indicating a frame format for transmissions using unlicensed radio frequency spectrum bands.

BACKGROUND

[0003] Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcasting, and so on. These systems may be multiple access systems with the ability to support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and frequency division multiple access systems. orthogonal frequency control (OFDMA).

[0004] By way of example, a wireless multiple access communication system may include numerous base stations, each supporting communication simultaneously for multiple communication devices, otherwise known as user equipment (UEs). A base station can communicate with UEs on downlink channels (e.g., for transmissions from a base station to a UE) and uplink channels (e.g., for transmissions from a UE to a base station).

[0005] Some communication modes may enable communications with a UE across different radio frequency spectrum bands (e.g., a licensed radio frequency spectrum band and/or an unlicensed radio frequency spectrum band) of a cellular network. With increasing data traffic in cellular networks, offloading at least a portion of the data traffic to an unlicensed radio frequency spectrum band may provide a cellular operator with opportunities for improved data transmission capacity. Before gaining access to, and communicating over, the unlicensed radio frequency spectrum band, a transmitting device may, in some examples, deploy a Listen-Before-You-Talk (LBT) protocol to gain access to the spectrum band. unlicensed radio frequency. An LBT protocol may include performing a clear channel assessment (CCA) procedure to determine whether an unlicensed radio frequency spectrum band channel is available. Radio frames of various formats can be used for transmissions that utilize available channels of the unlicensed radio frequency spectrum band for uplink communications and downlink communications. Therefore, there is a need for techniques to indicate a frame format for transmissions using an unlicensed radio frequency spectrum band.

SUMMARY OF THE INVENTION

[0006] The present disclosure, for example, relates to one or more techniques for indicating a frame format for transmissions using unlicensed radio frequency spectrum bands. A UE may receive, from a base station, a frame format indicator associated with a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band. The UE may determine a time division duplexing (TDD) configuration for the transmission opportunity based, at least in part, on the frame format indicator.

[0007] In one example, a method for wireless communication is described. In one example, the method may include receiving, from a base station, a frame format indicator associated with a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band; and determining a time division duplexing (TDD) setting for the transmission opportunity based, at least in part, on the frame format indicator.

[0008] In some examples, the frame format indicator comprises a code word associated with the TDD configuration. In some examples, the codeword is scrambled with a sequence associated with the base station. In some examples, the sequence is additionally associated with a public land mobile network (PLMN) identification. In some examples, the scrambled codeword is modulated with quadrature phase shift keying (QPSK). In some examples, the codeword is mapped to space-frequency block code (SFBC) symbols associated with two antenna ports. In some examples, the two antenna ports correspond to antenna ports for channel usage warning signal (CUBS) transmissions. In some examples, SFBC symbols are mapped to an enhanced resource element group (eREG). In some examples, the method may include receiving the frame format indicator in a bitstream, wherein the length of the bitstream is determined by a number of cyclic extensions of the codeword.

[0009] In some examples, the code word comprises repetitions of a code. In some examples, the code indicates the TDD configuration. In some examples, the code is based, at least in part, on a three-bit word that indicates the TDD configuration. In some examples, the code is additionally based, at least in part, on parity checks of the three-bit word, wherein the parity checks comprise XOR operations on the bits of the three-bit word. In some examples, the code indicates a number of downlink subframes between two special subframes. In some examples, the frame format indicator is carried by at least one enhanced resource element group (eREG) of a resource block (RB). In some examples, the RB is one of a plurality of RBs of an unlicensed radio frequency spectrum band channel, wherein the plurality of RBs omits RBs located at edges of the channel and on a direct current (DC) carrier of the channel. . In some examples, the frame format indicator is multiplexed with a second frame format indicator from a second base station.

[0010] In some examples, the method may include receiving the frame format indicator in an orthogonal frequency division multiplexing (OFDM) symbol prior to a downlink subframe of the transmission opportunity. In some examples, the OFDM symbol comprises a channel usage warning signal (CUBS). In some examples, the method may include receiving the frame format indicator prior to a first subframe of the transmission opportunity. In some examples, the method may include receiving the frame format indicator during a middle portion of the transmission opportunity. In some examples, the method may include decoding the frame format indicator prior to an edge of a first downlink subframe of the transmission opportunity. In some examples, the method may include receiving a second frame format indicator during a subframe of the transmission opportunity; and invalidating the second frame format indicator based, at least in part, in which subframe the second frame format indicator is received. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to an inter-carrier grant of a primary cell. In some examples, intercarrier granting occurred at least four subframes before the uplink subframe.

[0011] In some examples, the TDD configuration comprises at least one uplink subframe corresponding to a self-scheduled uplink grant. In some examples, the auto-scheduled uplink grant occurred more than four subframes before the uplink subframe. In some examples, the TDD configuration is based, at least in part, on an extended clear channel assessment (eCCA) of the base station. In some examples, the base station eCCA is completed at least four subframes before an uplink subframe of the TDD configuration. In some examples, the TDD configuration comprises at least one downlink subframe and at least one uplink subframe. In some examples, the TDD configuration further comprises a first special subframe and a second special subframe, wherein the first special subframe comprises an uplink channel usage warning signal (U-CUBS) and wherein the second special subframe comprises a downlink channel usage warning signal (D-CUBS). In some examples, an uplink subframe follows the first special subframe and a downlink subframe follows the second special subframe.

[0012] In one example, a method for wireless communication is described. In one example, the method may include determining a time division duplexing (TDD) configuration for a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band; and transmitting, to a UE, a frame format indicator associated with the transmission opportunity, wherein the frame format indicator is based, at least in part, on the TDD configuration.

[0013] In some examples, the frame format indicator comprises a code word associated with the TDD configuration. In some examples, the method may include scrambling the codeword with a sequence associated with a base station. In some examples, the sequence is additionally associated with a public land mobile network (PLMN) identification. In some examples, the method may include modulating the scrambled codeword with quadrature phase shift keying (QPSK). In some examples, the method may include mapping the codeword to space-frequency block code (SFBC) symbols associated with two antenna ports. In some examples, the two antenna ports correspond to antenna ports for channel usage warning signal (CUBS) transmissions. In some examples, SFBC symbols are mapped to an enhanced resource element group (eREG). In some examples, the method may include cyclically extending the codeword a certain number of times; and transmitting the frame format indicator in a bitstream, wherein the length of the bitstream is determined by the number of cyclic extensions of the codeword.

[0014] In some examples, the code word may include repetitions of a code. In some examples, the code indicates the TDD configuration. In some examples, the code is based, at least in part, on a three-bit word that indicates the TDD configuration. In some examples, the code is additionally based, at least in part, on parity checks of the three-bit word, wherein the parity checks comprise XOR operations on the bits of the three-bit word. In some examples, the code indicates a number of downlink subframes between two special subframes. In some examples, the frame format indicator is carried by at least one enhanced resource element group (eREG) of a resource block (RB). In some examples, the RB is one of a plurality of RBs of an unlicensed radio frequency spectrum band channel, wherein the plurality of RBs omits RBs located at edges of the channel and on a direct current (DC) carrier of the channel. . In some examples, the method may include multiplexing the frame format indicator with a second frame format indicator from a second base station.

[0015] In some examples, the method may include transmitting the frame format indicator in an orthogonal frequency division multiplexing (OFDM) symbol prior to a downlink subframe of the transmission opportunity. In some examples, the OFDM symbol comprises a channel usage warning signal (CUBS). In some examples, the method may include transmitting the frame format indicator before a first subframe of the transmission opportunity. In some examples, the method may include transmitting the frame format indicator during a middle portion of the transmission opportunity. In some examples, the method may include transmitting a second frame format indicator during a subframe of the transmission opportunity. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to an inter-carrier grant of a primary cell. In some examples, intercarrier granting occurred at least four subframes before the uplink subframe. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to a self-scheduled uplink grant. In some examples, the auto-scheduled uplink grant occurred more than four subframes before the uplink subframe. In some examples, the method may include performing an extended patency assessment (eCCA); and determine the TDD configuration based, at least in part, on eCCA. In some examples, eCCA is completed at least four subframes before an uplink subframe of the TDD configuration.

[0016] In some examples, the TDD configuration comprises at least one downlink subframe and at least one uplink subframe. In some examples, the TDD configuration further comprises a first special subframe and a second special subframe, wherein the first special subframe comprises an uplink channel usage warning signal (U-CUBS) and wherein the second special subframe comprises a downlink channel usage warning signal (D-CUBS). In some examples, an uplink subframe follows the first special subframe and a downlink subframe follows the second special subframe.

[0017] In one example, a method for wireless communication is described. In one example, the method may include identifying a plurality of TDD configurations, wherein each of the plurality of TDD configurations comprises different numbers of uplink subframes and downlink subframes; and identifying an available TDD configuration among the plurality of TDD configurations, wherein the available TDD configuration is indicated by a frame format indicator.

[0018] In some examples, each of the plurality of TDD configurations comprises ten subframes. In some examples, each of the plurality of TDD configurations comprises at least one special subframe. In some examples, a first subframe of each of the plurality of TDD configurations comprises a downlink subframe. In some examples, a last subframe of each of the plurality of TDD configurations comprises a special subframe.

[0019] In some examples, the plurality of TDD configurations comprises: a first TDD configuration comprising a downlink subframe, a first special subframe, seven uplink subframes and a second special subframe; a second TDD configuration comprising two downlink subframes, a first special subframe, six uplink subframes, and a second special subframe; a third TDD configuration comprising three downlink subframes, a first special subframe, five uplink subframes and a second special subframe; a fourth TDD configuration comprising four downlink subframes, a first special subframe, four uplink subframes, and a second special subframe; a fifth TDD configuration comprising five downlink subframes, a first special subframe, three uplink subframes and a second special subframe; a sixth TDD configuration comprising six downlink subframes, a first special subframe, two uplink subframes, and a second special subframe; a seventh TDD configuration comprising seven downlink subframes, a first special subframe, an uplink subframe, and a second special subframe; and an eighth TDD configuration comprising nine downlink subframes and a second special subframe. In some examples, the first special subframe comprises an uplink channel usage warning signal (U-CUBS), and the second special subframe comprises a downlink channel usage warning signal (D-CUBS).

[0020] In one example, an apparatus for wireless communication is described. In one example, the apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. Instructions may be executable by the processor to receive, from a base station, a frame format indicator associated with a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band; and determining a time division duplexing (TDD) setting for the transmission opportunity based, at least in part, on the frame format indicator.

[0021] In some examples, the frame format indicator comprises a code word associated with the TDD configuration. In some examples, the codeword is scrambled with a sequence associated with the base station. In some examples, the sequence is additionally associated with a public land mobile network (PLMN) identification. In some examples, the scrambled codeword is modulated with quadrature phase shift keying (QPSK). In some examples, the codeword is mapped to space-frequency block code (SFBC) symbols associated with two antenna ports. In some examples, the two antenna ports correspond to antenna ports for channel usage warning signal (CUBS) transmissions. In some examples, SFBC symbols are mapped to an enhanced resource element group (eREG). In some examples of the apparatus, instructions may also be executable by the processor to receive the frame format indicator in a bit stream, wherein the length of the bit stream is determined by a given number of cyclic extensions of the code word.

[0022] In some examples, the code word comprises repetitions of a code. In some examples, the code indicates the TDD configuration. In some examples, the code is based, at least in part, on a three-bit word that indicates the TDD configuration. In some examples, the code is additionally based, at least in part, on three-bit word parity checks, wherein the parity checks comprise XOR operations on the bits of the three-bit word. In some examples, the code indicates a number of downlink subframes between two special subframes. In some examples, the frame format indicator is carried by at least one enhanced resource element group (eREG) of a resource block (RB). In some examples, the RB is one of a plurality of RBs of an unlicensed radio frequency spectrum band channel, wherein the plurality of RBs omits RBs located at edges of the channel and on a direct current (DC) carrier of the channel. . In some examples, the frame format indicator is multiplexed with a second frame format indicator from a second base station.

[0023] In some examples of the apparatus, instructions may also be executable by the processor to receive the frame format indicator in an orthogonal frequency division multiplexing (OFDM) symbol before a downlink subframe of the transmission opportunity. In some examples, the OFDM symbol comprises a channel usage warning signal (CUBS). In some examples of the apparatus, instructions may also be executable by the processor to receive the frame format indicator prior to a first subframe of the transmission opportunity. In some examples of the apparatus, instructions may also be executable by the processor to receive the frame format indicator during a middle portion of the transmission opportunity. In some examples of the apparatus, instructions may also be executable by the processor to decode the frame format indicator prior to an end of a first downlink subframe of the transmission opportunity. In some examples of the apparatus, instructions may also be executable by the processor to receive a second frame format indicator during a subframe of the transmission opportunity; and invalidating the second frame format indicator based, at least in part, in which subframe the second frame format indicator is received. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to an inter-carrier grant of a primary cell. In some examples, intercarrier granting occurred at least four subframes before the uplink subframe.

[0024] In some examples, the TDD configuration comprises at least one uplink subframe corresponding to a self-scheduled uplink grant. In some examples, the auto-scheduled uplink grant occurred more than four subframes before the uplink subframe. In some examples, the TDD configuration is based, at least in part, on an extended clear channel assessment (eCCA) of the base station. In some examples, the base station eCCA is completed at least four subframes before an uplink subframe of the TDD configuration. In some examples, the TDD configuration comprises at least one downlink subframe and at least one uplink subframe. In some examples, the TDD configuration further comprises a first special subframe and a second special subframe, wherein the first subframe The special subframe comprises an uplink channel usage warning signal (U-CUBS) and wherein the second special subframe comprises a downlink channel usage warning signal (D-CUBS). In some examples, an uplink subframe follows the first special subframe and a downlink subframe follows the second special subframe.

[0025] In one example, an apparatus for wireless communication is described. In one example, the apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. Instructions may be executable by the processor to determine a time division duplexing (TDD) setting for a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band; and transmitting, to a UE, a frame format indicator associated with the transmission opportunity, wherein the frame format indicator is based, at least in part, on the TDD configuration.

[0026] In some examples, the frame format indicator comprises a code word associated with the TDD configuration. In some examples of the apparatus, instructions may also be executable by the processor to scramble the code word with a sequence associated with a base station. In some examples, the sequence is additionally associated with a public land mobile network (PLMN) identification. In some examples of the apparatus, instructions may also be executable by the processor to modulate the scrambled codeword with quadrature phase shift keying (QPSK). In some examples of the apparatus, instructions may also be executable by the processor to map the code word to space-frequency block code (SFBC) symbols associated with two antenna ports. In some examples, the two antenna ports correspond to antenna ports for channel usage warning signal (CUBS) transmissions. In some examples, SFBC symbols are mapped to an enhanced resource element group (eREG). In some examples of the apparatus, the instructions may also be executable by the processor to cyclically extend the code word a given number of times; and transmitting the frame format indicator in a bitstream, wherein the length of the bitstream is determined by the given number of cyclic extensions of the codeword.

[0027] In some examples, the code word may include repetitions of a code. In some examples, the code indicates the TDD configuration. In some examples, the code is based, at least in part, on a three-bit word that indicates the TDD configuration. In some examples, the code is additionally based, at least in part, on parity checks of the three-bit word, wherein the parity checks comprise XOR operations on the bits of the three-bit word. In some examples, the code indicates a number of downlink subframes between two special subframes. In some examples, the frame format indicator is carried by at least one enhanced resource element group (eREG) of a resource block (RB). In some examples, the RB is one of a plurality of RBs of an unlicensed radio frequency spectrum band channel, wherein the plurality of RBs omits RBs located at edges of the channel and on a direct current (DC) carrier of the channel. . In some examples of the apparatus, instructions may also be executable by the processor to multiplex the frame format indicator with a second frame format indicator from a second base station.

[0028] In some examples of the apparatus, instructions may also be executable by the processor to transmit the frame format indicator in an orthogonal frequency division multiplexing (OFDM) symbol prior to a downlink subframe of the transmission opportunity. In some examples, the OFDM symbol comprises a channel usage warning signal (CUBS). In some examples of the apparatus, instructions may also be executable by the processor to transmit the frame format indicator prior to a first subframe of the transmission opportunity. In some examples of the apparatus, instructions may also be executable by the processor to transmit the frame format indicator during a middle portion of the transmission opportunity. In some examples of the apparatus, instructions may also be executable by the processor to transmit a second frame format indicator during a subframe of the transmission opportunity. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to an inter-carrier grant of a primary cell. In some examples, intercarrier granting occurred at least four subframes before the uplink subframe. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to a self-scheduled uplink grant. In some examples, the auto-scheduled uplink grant occurred more than four subframes before the uplink subframe. In some examples of the apparatus, the instructions may also be executable by the processor to perform an extended clear channel assessment (eCCA); and determine the TDD configuration based, at least in part, on eCCA. In some examples, eCCA is completed at least four subframes before an uplink subframe of the TDD configuration.

[0029] In some examples, the TDD configuration comprises at least one downlink subframe and at least one uplink subframe. In some examples, the TDD configuration further comprises a first special subframe and a second special subframe, wherein the first special subframe comprises an uplink channel usage warning signal (U-CUBS) and wherein the second special subframe comprises a downlink channel usage warning signal (D-CUBS). In some examples, an uplink subframe follows the first special subframe and a downlink subframe follows the second special subframe.

[0030] In one example, an apparatus for wireless communication is described. In one example, the apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. Instructions may be executable by the processor to identify a plurality of TDD configurations, wherein each of the plurality of TDD configurations comprises different numbers of uplink subframes and downlink subframes; and identifying an available TDD configuration among the plurality of TDD configurations, wherein the available TDD configuration is indicated by a frame format indicator.

[0031] In some examples, each of the plurality of TDD configurations comprises ten subframes. In some examples, each of the plurality of TDD configurations comprises at least one special subframe. In some examples, a first subframe of each of the plurality of TDD configurations comprises a downlink subframe. In some examples, a last subframe of each of the plurality of TDD configurations comprises a special subframe.

[0032] In some examples, the plurality of TDD configurations comprises: a first TDD configuration comprising a downlink subframe, a first special subframe, seven uplink subframes and a second special subframe; a second TDD configuration comprising two downlink subframes, a first special subframe, six uplink subframes, and a second special subframe; a third TDD configuration comprising three downlink subframes, a first special subframe, five uplink subframes and a second special subframe; a fourth TDD configuration comprising four downlink subframes, a first special subframe, four uplink subframes, and a second special subframe; a fifth TDD configuration comprising five downlink subframes, a first special subframe, three uplink subframes and a second special subframe; a sixth TDD configuration comprising six downlink subframes, a first special subframe, two uplink subframes, and a second special subframe; a seventh TDD configuration comprising seven downlink subframes, a first special subframe, an uplink subframe, and a second special subframe; and an eighth TDD configuration comprising nine downlink subframes and a second special subframe. In some examples, the first special subframe comprises an uplink channel usage warning signal (U-CUBS), and the second special subframe comprises a downlink channel usage warning signal (D-CUBS).

[0033] In an example, another apparatus for wireless communication is described. In one example, the apparatus may include means for receiving, from a base station, a frame format indicator associated with a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band; and means for determining a time division duplexing (TDD) configuration for the transmission opportunity based, at least in part, on the frame format indicator.

[0034] In some examples, the frame format indicator comprises a code word associated with the TDD configuration. In some examples, the codeword is scrambled with a sequence associated with the base station. In some examples, the sequence is additionally associated with a public land mobile network (PLMN) identification. In some examples, the scrambled codeword is modulated with quadrature phase shift keying (QPSK). In some examples, the codeword is mapped to space-frequency block code (SFBC) symbols associated with two antenna ports. In some examples, the two antenna ports correspond to antenna ports for channel usage warning signal (CUBS) transmissions. In some examples, SFBC symbols are mapped to an enhanced resource element group (eREG). In some examples, the apparatus may include means for receiving the frame format indicator in a bit stream, wherein the length of the bit stream is determined by a number of cyclic extensions of the code word.

[0035] In some examples, the code word comprises repetitions of a code. In some examples, the code indicates the TDD configuration. In some examples, the code is based, at least in part, on a three-bit word that indicates the TDD configuration. In some examples, the code is additionally based, at least in part, on parity checks of the three-bit word, wherein the parity checks comprise XOR operations on the bits of the three-bit word. In some examples, the code indicates a number of downlink subframes between two special subframes. In some examples, the frame format indicator is carried by at least one enhanced resource element group (eREG) of a resource block (RB). In some examples, the RB is one of a plurality of RBs of an unlicensed radio frequency spectrum band channel, wherein the plurality of RBs omits RBs located at edges of the channel and on a direct current (DC) carrier of the channel. . In some examples, the frame format indicator is multiplexed with a second frame format indicator from a second base station.

[0036] In some examples, the apparatus may include means for receiving the frame format indicator in an orthogonal frequency division multiplexing (OFDM) symbol prior to a downlink subframe of the transmission opportunity. In some examples, the OFDM symbol comprises a channel usage warning signal (CUBS). In some examples, the apparatus may include means for receiving the frame format indicator prior to a first subframe of the transmission opportunity. In some examples, the apparatus may include means for receiving the frame format indicator during a middle portion of the transmission opportunity. In some examples, the apparatus may include means for decoding the frame format indicator prior to an end of a first downlink subframe of the transmission opportunity. In some examples, the apparatus may include means for receiving a second frame format indicator during a subframe of the transmission opportunity; and invalidating the second frame format indicator based, at least in part, in which subframe the second frame format indicator is received. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to an inter-carrier grant of a primary cell. In some examples, intercarrier granting occurred at least four subframes before the uplink subframe.

[0037] In some examples, the TDD configuration comprises at least one uplink subframe corresponding to a self-scheduled uplink grant. In some examples, the auto-scheduled uplink grant occurred more than four subframes before the uplink subframe. In some examples, the TDD configuration is based, at least in part, on an extended clear channel assessment (eCCA) of the base station. In some examples, the base station eCCA is completed at least four subframes before an uplink subframe of the TDD configuration. In some examples, the TDD configuration comprises at least one downlink subframe and at least one uplink subframe. In some examples, the TDD configuration further comprises a first special subframe and a second special subframe, wherein the first subframe The special subframe comprises an uplink channel usage warning signal (U-CUBS) and wherein the second special subframe comprises a downlink channel usage warning signal (D-CUBS). In some examples, an uplink subframe follows the first special subframe and a downlink subframe follows the second special subframe.

[0038] In an example, another apparatus for wireless communication is described. In one example, the apparatus may include means for determining a time division duplexing (TDD) configuration for a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band; and means for transmitting, to a UE, a frame format indicator associated with the transmission opportunity, wherein the frame format indicator is based, at least in part, on the TDD configuration.

[0039] In some examples, the frame format indicator comprises a code word associated with the TDD configuration. In some examples, the apparatus may include means for scrambling the codeword with a sequence associated with a base station. In some examples, the sequence is additionally associated with a public land mobile network (PLMN) identification. In some examples, the apparatus may include means for modulating the scrambled codeword with quadrature phase shift keying (QPSK). In some examples, the apparatus may include means for mapping the codeword to space-frequency block code (SFBC) symbols associated with two antenna ports. In some examples, the two antenna ports correspond to antenna ports for channel usage warning signal (CUBS) transmissions. In some examples, SFBC symbols are mapped to an enhanced resource element group (eREG). In some examples, the apparatus may include means for cyclically extending the codeword a specified number of times; and means for transmitting the frame format indicator in a bit stream, wherein the length of the bit stream is determined by the number of cyclic extensions of the code word.

[0040] In some examples, the code word may include repetitions of a code. In some examples, the code indicates the TDD configuration. In some examples, the code is based, at least in part, on a three-bit word that indicates the TDD configuration. In some examples, the code is additionally based, at least in part, on parity checks of the three-bit word, wherein the parity checks comprise XOR operations on the bits of the three-bit word. In some examples, the code indicates a number of downlink subframes between two special subframes. In some examples, the frame format indicator is carried by at least one enhanced resource element group (eREG) of a resource block (RB). In some examples, the RB is one of a plurality of RBs of an unlicensed radio frequency spectrum band channel, wherein the plurality of RBs omits RBs located at edges of the channel and on a direct current (DC) carrier of the channel. . In some examples, the apparatus may include means for multiplexing the frame format indicator with a second frame format indicator of a second base station.

[0041] In some examples, the apparatus may include means for transmitting the frame format indicator in an orthogonal frequency division multiplexing (OFDM) symbol prior to a downlink subframe of the transmission opportunity. In some examples, the OFDM symbol comprises a channel usage warning signal (CUBS). In some examples, the apparatus may include means for transmitting the frame format indicator prior to a first subframe of the transmission opportunity. In some examples, the apparatus may include means for transmitting the frame format indicator during a middle portion of the transmission opportunity. In some examples, the apparatus may include means for transmitting a second frame format indicator during a subframe of the transmission opportunity. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to an inter-carrier grant of a primary cell. In some examples, intercarrier granting occurred at least four subframes before the uplink subframe. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to a self-scheduled uplink grant. In some examples, the auto-scheduled uplink grant occurred more than four subframes before the uplink subframe. In some examples, the apparatus may include means for performing an extended patency assessment (eCCA); and means for determining the TDD configuration based, at least in part, on eCCA. In some examples, eCCA is completed at least four subframes before an uplink subframe of the TDD configuration.

[0042] In some examples, the TDD configuration comprises at least one downlink subframe and at least one uplink subframe. In some examples, the TDD configuration further comprises a first special subframe and a second special subframe, wherein the first special subframe comprises an uplink channel usage warning signal (U-CUBS) and wherein the second special subframe comprises a downlink channel usage warning signal (D-CUBS). In some examples, an uplink subframe follows the first special subframe and a downlink subframe follows the second special subframe.

[0043] In an example, another apparatus for wireless communication is described. In one example, the apparatus may include means for identifying a plurality of TDD configurations, wherein each of the plurality of TDD configurations comprises different numbers of uplink subframes and downlink subframes; and means for identifying an available TDD configuration among the plurality of TDD configurations, wherein the available TDD configuration is indicated by a frame format indicator.

[0044] In some examples, each of the plurality of TDD configurations comprises ten subframes. In some examples, each of the plurality of TDD configurations comprises at least one special subframe. In some examples, a first subframe of each of the plurality of TDD configurations comprises a downlink subframe. In some examples, a last subframe of each of the plurality of TDD configurations comprises a special subframe.

[0045] In some examples, the plurality of TDD configurations comprises: a first TDD configuration comprising a downlink subframe, a first special subframe, seven uplink subframes, and a second special subframe; a second TDD configuration comprising two downlink subframes, a first special subframe, six uplink subframes, and a second special subframe; a third TDD configuration comprising three downlink subframes, a first special subframe, five uplink subframes and a second special subframe; a fourth TDD configuration comprising four downlink subframes, a first special subframe, four uplink subframes, and a second special subframe; a fifth TDD configuration comprising five downlink subframes, a first special subframe, three uplink subframes and a second special subframe; a sixth TDD configuration comprising six downlink subframes, a first special subframe, two uplink subframes, and a second special subframe; a seventh TDD configuration comprising seven downlink subframes, a first special subframe, an uplink subframe, and a second special subframe; and an eighth TDD configuration comprising nine downlink subframes and a second special subframe. In some examples, the first special subframe comprises an uplink channel usage warning signal (U-CUBS), and the second special subframe comprises a downlink channel usage warning signal (D-CUBS).

[0046] In one example, a non-transitory computer-readable medium that stores computer-executable code for wireless communication is described. In one example, the code may be executable by a processor for receiving, from a base station, a frame format indicator associated with a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band; and determining a time division duplexing (TDD) setting for the transmission opportunity based, at least in part, on the frame format indicator.

[0047] In some examples, the frame format indicator comprises a code word associated with the TDD configuration. In some examples, the codeword is scrambled with a sequence associated with the base station. In some examples, the sequence is additionally associated with a public land mobile network (PLMN) identification. In some examples, the scrambled codeword is modulated with quadrature phase shift keying (QPSK). In some examples, the codeword is mapped to space-frequency block code (SFBC) symbols associated with two antenna ports. In some examples, the two antenna ports correspond to antenna ports for channel usage warning signal (CUBS) transmissions. In some examples, SFBC symbols are mapped to an enhanced resource element group (eREG). In some examples of non-transitory machine-readable media, code may also be executable by the processor to receive the frame format indicator in a bitstream, wherein the length of the bitstream is determined by a given number of cyclic extensions of the code word.

[0048] In some examples, the code word comprises repetitions of a code. In some examples, the code indicates the TDD configuration. In some examples, the code is based, at least in part, on a three-bit word that indicates the TDD configuration. In some examples, the code is additionally based, at least in part, on parity checks of the three-bit word, wherein the parity checks comprise XOR operations on the bits of the three-bit word. In some examples, the code indicates a number of downlink subframes between two special subframes. In some examples, the frame format indicator is carried by at least one enhanced resource element group (eREG) of a resource block (RB). In some examples, the RB is one of a plurality of RBs of an unlicensed radio frequency spectrum band channel, wherein the plurality of RBs omits RBs located at edges of the channel and on a direct current (DC) carrier of the channel. . In some examples, the frame format indicator is multiplexed with a second frame format indicator from a second base station.

[0049] In some examples of non-transitory computer-readable media, code may also be executable by the processor to receive the frame format indicator in an orthogonal frequency division multiplexing (OFDM) symbol before a downlink subframe of the transmission opportunity. In some examples, the OFDM symbol comprises a channel usage warning signal (CUBS). In some examples of non-transitory computer-readable media, code may also be executable by the processor to receive the frame format indicator prior to a first subframe of the transmission opportunity. In some examples of non-transient computer-readable media, code may also be executable by the processor to receive the frame format indicator during a middle portion of the transmission opportunity. In some examples of non-transitory computer-readable media, code may also be executable by the processor to decode the frame format indicator prior to one end of a first downlink subframe of the transmission opportunity. In some examples of non-transient computer-readable media, code may also be executable by the processor to receive a second frame format indicator during a subframe of the transmission opportunity; and invalidating the second frame format indicator based, at least in part, in which subframe the second frame format indicator is received. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to an inter-carrier grant of a primary cell. In some examples, intercarrier granting occurred at least four subframes before the uplink subframe.

[0050] In some examples, the TDD configuration comprises at least one uplink subframe corresponding to a self-scheduled uplink grant. In some examples, the auto-scheduled uplink grant occurred more than four subframes before the uplink subframe. In some examples, the TDD configuration is based, at least in part, on an extended clear channel assessment (eCCA) of the base station. In some examples, the base station eCCA is completed at least four subframes before an uplink subframe of the TDD configuration. In some examples, the TDD configuration comprises at least one downlink subframe and at least one uplink subframe. In some examples, the TDD configuration further comprises a first special subframe and a second special subframe, wherein the first special subframe comprises an uplink channel usage warning signal (U-CUBS) and wherein the second special subframe comprises a downlink channel usage warning signal (D-CUBS). In some examples, an uplink subframe follows the first special subframe and a downlink subframe follows the second special subframe.

[0051] In one example, a non-transitory computer-readable medium that stores computer-executable code for wireless communication is described. In one example, the code may be executable by a processor to determine a time division duplexing (TDD) setting for a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band; and transmitting, to a UE, a frame format indicator associated with the transmission opportunity, wherein the frame format indicator is based, at least in part, on the TDD configuration.

[0052] In some examples, the frame format indicator comprises a code word associated with the TDD configuration. In some examples of non-transitory computer-readable media, code may also be executable by the processor to scramble the code word with a sequence associated with a base station. In some examples, the sequence is additionally associated with a public land mobile network (PLMN) identification. In some examples of non-transitory computer-readable media, code may also be executable by the processor to modulate the scrambled codeword with quadrature phase shift keying (QPSK). In some examples of non-transitory computer-readable media, code may also be executable by the processor to map the code word to space-frequency block code (SFBC) symbols associated with two antenna ports. In some examples, the two antenna ports correspond to antenna ports for channel usage warning signal (CUBS) transmissions. In some examples, SFBC symbols are mapped to an enhanced resource element group (eREG). In some examples of non-transitory computer-readable media, the code may also be executable by the processor to cyclically extend the code word a certain number of times; and transmitting the frame format indicator in a bitstream, wherein the length of the bitstream is determined by the given number of cyclic extensions of the codeword.

[0053] In some examples, the code word may include repetitions of a code. In some examples, the code indicates the TDD configuration. In some examples, the code is based, at least in part, on a three-bit word that indicates the TDD configuration. In some examples, the code is additionally based, at least in part, on parity checks of the three-bit word, wherein the parity checks comprise XOR operations on the bits of the three-bit word. In some examples, the code indicates a number of downlink subframes between two special subframes. In some examples, the frame format indicator is carried by at least one enhanced resource element group (eREG) of a resource block (RB). In some examples, the RB is one of a plurality of RBs of an unlicensed radio frequency spectrum band channel, wherein the plurality of RBs omits RBs located at edges of the channel and on a direct current (DC) carrier of the channel. . In some examples of non-transitory computer readable media, code may also be executable by the processor to multiplex the frame format indicator with a second frame format indicator from a second base station.

[0054] In some examples of non-transitory computer readable media, code may also be executable by the processor to transmit the frame format indicator in an orthogonal frequency division multiplexing (OFDM) symbol before a downlink subframe of the transmission opportunity. In some examples, the OFDM symbol comprises a channel usage warning signal (CUBS). In some examples of non-transitory computer-readable media, code may also be executable by the processor to transmit the frame format indicator prior to a first subframe of the transmission opportunity. In some examples of non-transient computer-readable media, code may also be executable by the processor to transmit the frame format indicator during a middle portion of the transmission opportunity. In some examples of non-transient computer-readable media, code may also be executable by the processor to transmit a second frame format indicator during a subframe of the transmission opportunity. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to an inter-carrier grant of a primary cell. In some examples, intercarrier granting occurred at least four subframes before the uplink subframe. In some examples, the TDD configuration comprises at least one uplink subframe corresponding to a self-scheduled uplink grant. In some examples, the auto-scheduled uplink grant occurred more than four subframes before the uplink subframe. In some examples of non-transitory computer-readable media, code may also be executable by the processor to perform an extended clear channel assessment (eCCA); and determine the TDD configuration based, at least in part, on eCCA. In some examples, eCCA is completed at least four subframes before an uplink subframe of the TDD configuration.

[0055] In some examples, the TDD configuration comprises at least one downlink subframe and at least one uplink subframe. In some examples, the TDD configuration further comprises a first special subframe and a second special subframe, wherein the first special subframe comprises an uplink channel usage warning signal (U-CUBS) and wherein the second special subframe comprises a downlink channel usage warning signal (D-CUBS). In some examples, an uplink subframe follows the first special subframe and a downlink subframe follows the second special subframe.

[0056] In one example, a non-transitory computer-readable medium that stores computer-executable code for wireless communication is described. In one example, code may be executable by a processor for identifying a plurality of TDD configurations, wherein each of the plurality of TDD configurations comprises different numbers of uplink subframes and downlink subframes; and identifying an available TDD configuration among the plurality of TDD configurations, wherein the available TDD configuration is indicated by a frame format indicator.

[0057] In some examples, each of the plurality of TDD configurations comprises ten subframes. In some examples, each of the plurality of TDD configurations comprises at least one special subframe. In some examples, a first subframe of each of the plurality of TDD configurations comprises a downlink subframe. In some examples, a last subframe of each of the plurality of TDD configurations comprises a special subframe.

[0058] In some examples, the plurality of TDD configurations comprises: a first TDD configuration comprising a downlink subframe, a first special subframe, seven uplink subframes and a second special subframe; a second TDD configuration comprising two downlink subframes, a first special subframe, six uplink subframes, and a second special subframe; a third TDD configuration comprising three downlink subframes, a first special subframe, five uplink subframes and a second special subframe; a fourth TDD configuration comprising four downlink subframes, a first special subframe, four uplink subframes, and a second special subframe; a fifth TDD configuration comprising five downlink subframes, a first special subframe, three uplink subframes and a second special subframe; a sixth TDD configuration comprising six downlink subframes, a first special subframe, two uplink subframes, and a second special subframe; a seventh TDD configuration comprising seven downlink subframes, a first special subframe, an uplink subframe, and a second special subframe; and an eighth TDD configuration comprising nine downlink subframes and a second special subframe. In some examples, the first special subframe comprises an uplink channel usage warning signal (U-CUBS), and the second special subframe comprises a downlink channel usage warning signal (D-CUBS).

[0059] The aforementioned has broadly highlighted the particularities and technical advantages of the examples according to the disclosure so that the detailed disclosure that follows is better understood. Additional features and advantages will be described later in this document. The specific design and examples disclosed can be readily used as a basis for modifying or designing other structures to accomplish the same purposes as the present disclosure. Such equivalent interpretations do not depart from the spirit of the attached claims. The characteristics of the concepts disclosed in the present document, both their organization and their method of operation, together with the associated advantages will be better understood from the following description when considered in connection with the attached Figures. Each of the Figures is provided for the purpose of illustration and description only and is not intended to limit the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] A further understanding of the nature and advantages of the present disclosure can be obtained by reference to the following drawings. In the attached Figures, similar components or features may have the same reference marking. Furthermore, several components of the same type can be distinguished by following the reference marking by a dash and a second marking that distinguishes between similar components. If only the first reference marking is used in the specification, the description is applicable to any of the similar components that have the same first reference marking regardless of the second reference marking.

[0061] Figure 1 illustrates an example of a wireless communications system, in accordance with various aspects of the present disclosure;

[0062] Figure 2 shows a table illustrating examples of TDD configurations that may be applicable for a radio frame, in accordance with various aspects of the present disclosure;

[0063] Figure 3A shows an example of resource blocks of a channel of an unlicensed radio frequency spectrum band, in accordance with various aspects of the present disclosure;

[0064] Figure 3B shows an example of tones for carrying a frame format indicator, in accordance with various aspects of the present disclosure;

[0065] Figure 4 shows another example of resource blocks of a channel of an unlicensed radio frequency spectrum band, in accordance with various aspects of the present disclosure;

[0066] Figure 5A shows an example of a radio frame, in accordance with various aspects of the present disclosure;

[0067] Figure 5B shows another example of a radio frame, in accordance with various aspects of the present disclosure;

[0068] Figure 6 shows the block diagram of a UE for use in wireless communication, in accordance with various aspects of the present disclosure;

[0069] Figure 7 shows a system for use in wireless communication, in accordance with various aspects of the present disclosure.

[0070] Figure 8 shows the block diagram of a base station for use in wireless communication, in accordance with various aspects of the present disclosure;

[0071] Figure 9 shows the block diagram of a base station for use in wireless communication, in accordance with various aspects of the present disclosure;

[0072] Figure 10 shows the block diagram of a base station for use in wireless communication, in accordance with various aspects of the present disclosure;

[0073] Figure 11 is a flowchart illustrating an example of a method for wireless communication, in accordance with various aspects of the present disclosure;

[0074] Figure 12 is a flowchart illustrating an example of a method for wireless communication, in accordance with various aspects of the present disclosure; It is

[0075] Figure 13 is a flowchart illustrating an example of a method for wireless communication, in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

[0076] When communicating over an unlicensed radio frequency spectrum band, the channels available for communication may be changed on a radio frame by radio frame basis. Based on when a channel becomes available during a radio frame, a time division duplexing (TDD) setting for the radio frame, or transmission opportunity, can be determined. A UE may receive, from a base station, a frame format indicator associated with the transmission opportunity, or radio frame, for transmissions in the unlicensed radio frequency spectrum band. The UE may determine the TDD configuration for the transmission opportunity based, at least in part, on the received frame format indicator.

[0077] The following description provides examples and is not limited to the scope, applicability or examples set forth in the claims. Changes can be made to the function and arrangement of the elements discussed without deviating from the scope of the disclosure. Various examples may omit, replace, or add various procedures or components as appropriate. For example, the methods described may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described in connection with some examples may be combined in other examples.

[0078] Figure 1 illustrates an example of a wireless communications system 100, in accordance with various aspects of the present disclosure. The wireless communications system 100 includes base stations 105, UEs 115, and a core network 130. The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access functions. , routing or mobility. The base station 105 interfaces with the main network 130 via return traffic links 132 (e.g., SI, etc.) and may perform radio configuration and scheduling for communication with the UEs 115, or may operate upon control from a base station controller (not shown). In various examples, base stations 105 may communicate, either directly or indirectly (e.g., via core network 130), with each other via return traffic 134 (e.g., XI, etc.), which may wired or wireless communication links.

[0079] The base stations 105 may communicate wirelessly with the UEs 115 via one or more base station antennas. Each of the base station locations 105 may provide communications coverage for a respective geographic coverage area 110. In some examples, the base stations 105 may be referred to as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, eNodeB (eNB), Residential NodeB, a Residential eNodeB, or some other suitable terminology. The geographic coverage area 110 for a base station can be divided into sectors that form only a portion of the coverage area (not shown). The wireless communications system 100 may include base stations 105 of different types (e.g., macrocell and/or small cell base stations). There may be overlapping geographic coverage areas 110 for different technologies.

[0080] In some examples, the wireless communications system 100 is 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, while the term UE may be used to describe the UEs 115. The wireless communications system 100 It can be a Heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for different geographic regions. For example, each eNB or base station 105 may provide communications coverage for a macrocell, a small cell, and/or other cell types. 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 the context.

[0081] A macrocell can cover a relatively large geographic area (e.g., several kilometers in radius) and can allow unrestricted access by UEs with service subscriptions with the network provider. A small cell is a less powerful base station, compared to a macrocell, which can operate in the same or different frequency bands (e.g. licensed, unlicensed, etc.) as macrocells. Small cells may include picocells, femtocells, and microcells according to various examples. A picocell can cover a relatively smaller geographic area and can allow unrestricted access by UEs with service subscriptions with the network provider. A femtocell may also cover a relatively small geographic area (e.g., a home) and may provide restricted access by UEs that have a membership to the femtocell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home and similar). An eNB for a macrocell can be called a macro-eNB. An eNB for a small cell may be called a small cell eNB, a pico-eNB, a femto-eNB, or a Residential eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers).

[0082] The wireless communications system 100 may support synchronous or asynchronous operation. For synchronous operation, base stations can have similar frame timing, and transmissions from different base stations can be approximately aligned in time. For asynchronous operation, base stations may have different frame timing, and transmissions from different base stations may not be time aligned. The techniques described in this document can be used for both synchronous and asynchronous operations.

[0083] Communication networks that can accommodate some of the various examples disclosed may be packet-based networks that operate in accordance with a layered protocol stack. At the user plane, communications at the Packet Data Convergence Protocol (PDCP) layer or at the carrier can be IP-based. A Radio Link Control (RLC) layer can perform packet reassembly and segmentation to communicate over logical channels. A Media Access Control (MAC) layer can perform multiplexing and priority manipulation of logical channels on transport channels. The MAC layer can 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 for the establishment, configuration, and maintenance of an RRC connection between a UE 15 and base stations 105 or core network 130 supporting carriers. radio for the data user plan. At the Physical layer (PHY), transport channels can be mapped to Physical channels.

[0084] The UEs 115 are dispersed throughout the wireless communications systems 100, and each UE 115 may be stationary or mobile. A UE 115 may also include or be called, by those skilled in the art, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a customer or some other suitable terminology. A UE 115 may be a cellular telephone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet-type computer, a laptop-type computer, a cordless telephone , a wireless local loop station (WLL), or the like. A UE can communicate with various types of base stations and network equipment that include macro-eNBs, small cell eNBs, relay base stations, and the like.

[0085] The communication links 125 shown in the wireless communication system 100 may include uplink (UL) transmissions from a UE 115 to a base station 105 and/or downlink (DL) transmissions from a base station 105 to a UE 115. Downlink transmissions may also be called forwarding link transmissions while uplink transmissions may also be called reverse link transmissions. Each communication link 125 may include one or more carriers, wherein each carrier may be a signal consisting of multiple subcarriers (e.g., waveform signals of different frequencies) modulated in accordance with the various radio technologies described above. Each modulated signal can be sent on a different subcarrier and can carry control information (e.g. reference signals, control channels, etc.), overload information, user data, etc.

[0086] Each carrier may be provided over a band of licensed radio frequency spectrum or a band of unlicensed radio frequency spectrum. More broadly, unlicensed spectrum in some jurisdictions can range from 600 Megahertz (MHz) to 6 Gigahertz (GHz). As used herein, the terms “unlicensed radio frequency spectrum”, “unlicensed spectrum” or “shared spectrum” may therefore refer to industrial, scientific and medical (ISM) radio bands, regardless of the frequency of such bands. In some examples, the unlicensed spectrum is the U-NII radio band, which may also be called the 5 GHz band or 5G band. By contrast, the terms “licensed radio spectrum,” “licensed spectrum,” or “cellular spectrum” may be used herein to refer to wireless spectrum used by wireless network operators under administrative license from a government agency. A set of carriers used in a communication mode may all be received (e.g., in a UE 115) over the licensed radio frequency spectrum band, be all received (e.g., in a UE 115) over the licensed radio spectrum band. unlicensed radio frequency or be received (e.g., in a UE 115) over a combination of the licensed radio frequency spectrum band and the unlicensed radio frequency spectrum band.

[0087] Communication links 125 may transmit bidirectional communications using FDD (e.g., using paired spectrum resources) or TDD operation (e.g., using unpaired spectrum resources). Frame structures for FDD (e.g. frame structure type 1) and TDD (e.g. frame structure type 2) can be defined. DL transmissions and/or UL transmissions may be performed using the licensed radio frequency spectrum band, the unlicensed radio frequency spectrum band, or both.

[0088] In some examples of the wireless communications system 100, the base stations 105 and/or UEs 115 may include multiple antennas to employ antenna diversity schemes to improve the quality and reliability of communication between the base stations 105 and UEs 115. Additionally or alternatively, base stations 105 and/or UEs 115 may employ multiple-input multiple-output (MIMO) techniques that can take advantage of multi-path environments to transmit multiple spatial layers carrying the same or encoded data or different encoded data.

[0089] The wireless communications system 100 may support operation on multiple cells or carriers, a feature that may be called multi-carrier operation. A carrier may also be called a component carrier (CC), a layer, a channel, etc. The terms “carrier”, “component carrier”, “cell” and “channel” may be used interchangeably in this document. A UE 115 may be configured with multiple downlink CCs and one or more uplink CCs for multicarrier operation. Multi-carrier operation can be with both FDD and TDD component carriers. Component carriers may utilize the licensed radio frequency spectrum band, the unlicensed radio frequency spectrum band, or a combination of the unlicensed and licensed radio frequency spectrum bands.

[0090] In some examples of the wireless communications system 100, the unlicensed radio frequency spectrum band may be installed under different scenarios. Installation scenarios may include a supplemental downlink (SDL) mode, in which downlink communications in the licensed radio frequency spectrum band can be offloaded to the unlicensed radio frequency spectrum band, a carrier aggregation (CA) mode ) in which both downlink and uplink communications may be offloaded from the licensed radio frequency spectrum band to the unlicensed radio frequency spectrum band and/or an autonomous mode (SA) in which downlink and uplink communications Uplink between the base station 105 and a UE 115 may occur in the unlicensed radio frequency spectrum band. Base stations 105 as well as UEs 115 may support, in some examples, one or more of these or similar modes of operation.

[0091] With increasing data traffic in cellular networks that use a licensed radio frequency spectrum band, offloading at least a portion of the data traffic into an unlicensed radio frequency spectrum band may provide a cellular operator (e.g. For example, an operator of a public fixed mobile network (PLMN) and/or a coordinated set of base stations that define a cellular network, such as an LTE/LTE-A network) opportunities for improved data transmission capacity. Before gaining access to, and communicating through, the unlicensed radio frequency spectrum band, a transmitting apparatus may, in some examples, perform an LBT procedure to obtain access to the unlicensed radio frequency spectrum band. Such an LBT procedure may include performing a clear channel assessment (CCA) procedure to determine whether an unlicensed radio frequency spectrum band channel is available. In some examples, an extended CCA (eCCA) procedure comprising a plurality of N CCA procedures may be performed. When it is determined that a channel is available, the transmitting apparatus may communicate over a carrier that includes the available channel. The transmitting apparatus may also broadcast a channel usage warning signal (CUBS). The CUBS may indicate the use of the available channel for other UEs 115 and/or base stations 105. The CUBS may indicate the use of an available channel for uplink communications (U-CUBS) or for downlink communications (D- CUBS).

[0092] A transmission opportunity may include a radio frame, a subset of a radio frame, or any combination thereof. Similarly, a radio frame may be used herein to represent a transmission opportunity. A TDD radio frame may include downlink subframes, uplink subframes, a first special subframe S, and a second special subframe S'. The downlink subframes may include downlink communications. The uplink subframes may include uplink communications. Special subframes (S and S’) may include control and/or signaling communications. For example, the first special subframe S can carry D-CUBS and the second special subframe S' can carry U-CUBS. Special subframes (S and S') may also include uplink or downlink communications in addition to control and/or signaling communications. For example, the first special subframe S may include uplink communications and the second special subframe S' may include downlink communications.

[0093] A UE 115 may receive a frame format indicator from a base station 105. The frame format indicator may include a TDD configuration indicator that indicates to the UE 115 the format of downlink subframes, uplink and special subframes that may be applicable to a current radio frame. The TDD configuration indicator can change each radio frame. A number of available TDD configuration indicators for the current radio frame may be based, at least in part, on when a CCA procedure is completed. If the CCA procedure is completed later in time on the radio frame, a smaller number of TDD configuration indicators may be available for the radio frame.

[0094] Figure 2 shows a table 200 that illustrates examples of TDD configurations 215-a through 215-h that may be applicable for a radio frame, in accordance with various aspects of the present disclosure. Each of the TDD configurations 215-a through 215-h may be represented by a four-bit code 210. The four-bit code 210 may be based on a three-bit word to indicate a number from 0 to 7, plus a additional bit for parity. The numbers 0 through 7 can correspond to each of TDD configurations 215-a through 215-h. TDD configurations 215-a through 215-h may indicate which subframes 205-a through 205-j of the radio frame can be configured as downlink subframes (illustrated as “D” in table 200), uplink subframes ( illustrated as “U” in table 200) or special subframes (illustrated as “S” and “S'” in table 200). The additional bit for parity may be based on the three-bit word parity checks. If a0, a1, and a2 are the three bits of the three-bit word, then parity checks can include xor(a0,a1), xor(a0,a2), xor(a1,a2), and xor(a0,a1 ,a2). Sometimes the radio frame may represent a transmission opportunity.

[0095] For example, the TDD configuration 215-c may correspond to a four-bit code 210 that has “0101” bits. Subframes 205-a through 205-c of TDD configuration 215-c may be “D” downlink subframes; The 205-d subframe may be a special “S” subframe; subframes 205-e through 205-i may be “U” uplink subframes; and subframe 205-j may be a special “S’” subframe. The special subframe S may be configured before an uplink subframe U. The special subframe S may include a U-CUBS and may also include additional downlink communications. The special subframe S’ can be configured before a new radio frame. The special subframe S' may include a D-CUBS and may also include additional uplink communications. Each of the TDD configurations 215-a through 215-h may include at least one downlink subframe D and one special subframe S'. TDD configurations 215-a through 215-h can follow a canonical pattern of S’D[D...D]SU[U...U].

[0096] In some examples, the frame format indicator may support a supplementary downlink (SDL) configuration 215-h in a carrier aggregation mode that does not have U uplink subframes. The SDL configuration 215-h may include eight downlink subframes D and one special subframe S'.

[0097] A number of available TDD configurations may be based, at least in part, on an eCCA procedure performed by a base station. A number of available TDD configurations may be additionally based, at least in part, on the time it takes for a UE to detect and decode a D-CUBS before a first downlink subframe, and the time it takes for the UE to decode the channel before a first uplink subframe.

[0098] A number of TDD settings available for the frame format indicator may be based, at least in part, on when a base station completes the eCCA procedure. In some examples, the available TDD configuration may configure an uplink subframe at least four subframes after the eCCA procedure is complete. For example, if the base station completes the eCCA procedure during subframe 5, then the frame format indicator may indicate a TDD configuration (e.g., TDD configuration 6 215-g) with an uplink subframe four subframes after subframe 5. If an uplink subframe is configured previously, the UE may not have sufficient time to configure data for the uplink subframe. In this way, a TDD configuration (e.g., TDD configuration 6 215-g) can be signaled to the UE. As another example, if the base station completes the eCCA procedure during subframe 4, then the frame format indicator may indicate TDD settings 5 or 6 (215-f or 215-g). If the base station completes the eCCA procedure during subframe 3, then the frame format indicator may indicate TDD settings 4, 5, or 6 (215-e, 215-f, or 215-g). If the base station completes the eCCA procedure during subframe 2, then the frame format indicator may indicate one of TDD configurations 3 through 6 (215-d through 215-g). If the base station completes the eCCA procedure during subframe 1, then the frame format indicator may indicate one of TDD configurations 2 through 6 (215-c through 215-g). If the base station completes the eCCA procedure during subframe 0, then the frame format indicator may indicate one of TDD configurations 1 through 6 (215-b through 215-g). Any of TDD settings 0 through 6 (215-a through 215-h) may be indicated by the frame format indicator if the eCCA procedure is completed during subframe 9 of the previous radio frame. The SDL 215-h configuration may be independent of the base station eCCA procedure.

[0099] In some examples, the frame format indicator may be transmitted by the base station during the current radio frame due to a change in the TDD configuration. Changing the TDD configuration during a radio frame may not be due to the timing of when the eCCA procedure completes as described above.

[0101] In some examples, a UE may self-schedule an uplink transmission on an uplink secondary component carrier (U-SCC). With uplink self-scheduling, the UE may receive an uplink grant four or more subframes before the corresponding self-scheduled uplink subframe. With uplink self-scheduling, the available TDD configurations may be based, at least in part, on a delay time for the UE to respond to the uplink grant, and may also be based, at least in part, on the processing time in the UE for uplink granting. The uplink grant for self-scheduled uplink may be for one uplink subframe U, or for multiple consecutive uplink subframes U of the current transmission opportunity or radio frame. The uplink lease may expire after the current radio frame in which the uplink lease was transmitted.

[0102] If the UE self-schedules an uplink transmission, then the available TDD settings may be based, at least in part, on the additional time for the UE to self-schedule the uplink transmission. In some examples, a TDD configuration for a self-scheduling UE may configure an uplink subframe more than four subframes after the base station eCCA procedure is completed. If an uplink subframe is previously configured, the self-scheduling UE may not have sufficient time to configure data for the uplink subframe. For example, if the base station completes the eCCA procedure during subframe 4, then the frame format indicator may indicate the TDD 6 (215-g) setting. The UE may not have time to configure an uplink subframe if one of the other TDD configurations were indicated. As another example, if the base station completes the eCCA procedure during subframe 3, then the frame format indicator may indicate TDD settings 5 or 6 (215-f or 215-g). If the base station completes the eCCA procedure during subframe 2, then the frame format indicator may indicate TDD settings 4, 5, or 6 (215-e, 215-f, or 215-g). If the base station completes the eCCA procedure during subframe 1, then the frame format indicator may indicate one of TDD configurations 3 through 6 (215-d through 215-g). If the base station completes the eCCA procedure during subframe 0, then the frame format indicator may indicate one of TDD configurations 2 through 6 (215-c through 215-g). In some examples, TDD settings 0 and 1 (215-a and 215-b) may indicate that an uplink subframe must occur before a self-scheduling UE has time to configure data for the uplink subframe. Therefore, TDD configurations 0 and 1 (215-a and 215-b) may be based, at least in part, on the possibility of the UE self-scheduling an uplink transmission.

[0103] In some examples, the UE may receive inter-carrier uplink grants from a primary component carrier (PCC) to a U-SCC. Each inter-carrier uplink grant may be from an uplink subframe U. The inter-carrier uplink grant may correspond to the uplink subframe U which is four subframes after the intercarrier uplink grant is received. Therefore, the TDD configurations available with intercarrier uplink leases can be the same as the TDD configurations available with a self-scheduled uplink. If the subframe that is four subframes after the inter-carrier uplink grant is not configured as a U uplink subframe, then the inter-carrier uplink grant may be invalid.

[0104] The base station, such as a base station 105 of Figure 1, may transmit the frame format indicator to the UE. The frame format indicator may also be called a physical frame format indicator, a physical frame format indicator channel, a TDD format indicator channel, an enhanced TDD format indicator channel, etc. The frame format indicator may include a code word that indicates which of TDD settings 215-a to 215-h may be applicable for a radio frame, or transmission opportunity. The code word may be a repetition of a code 210 corresponding to the applicable TDD configuration. For example, a code word for TDD configuration 215-e with four repetitions of the corresponding code 210 might be “1001100110011001”. In some examples, the codeword may include 12 repetitions of the corresponding code 210. In some examples, the codeword may be cyclically extended to adjust the length of a bit stream that includes the frame format indicator. Adjusting the length of the bitstream that includes the frame format indicator can allow the bitstream to match a rate of other bitstreams.

[0105] In some cases, code 210 or codeword may be based on a different encryption or decryption scheme. For example, a six-bit Reed Muller code can be used. Specifically, a (32,0) encoding scheme can be implemented, where the output is at least 32 bits and O is the number of encryption or input bits. In some cases, O may be 11 or less. Code 210, or the code word, can be repeated countless times. In some cases, code 210, or code word, may be encoded similarly to a physical uplink control channel (PUCCH) for uplink transmission. It should be noted that code 210, or the code word, can be encrypted or decoded using any coding scheme known in the art.

[0106] In some examples, the code may indicate a number of downlink subframes D that occur before a special subframe S for the current transmission opportunity. The UE can then configure all subframes of the current transmission opportunity that come after the special subframe S as uplink subframes U up to the last subframe (for example, up to subframe 9). The last subframe (e.g., subframe 9) may be configured as a special subframe S' in order to perform the LBT procedure to gain access to a channel of an unlicensed radio frequency spectrum band. For example, a code of “000” may indicate one D downlink subframe before the S special subframe. A “001” code may indicate two D downlink subframes before the S special subframe. indicate seven D downlink subframes before the special S subframe. And a code of “110” may indicate an SDL configuration that has eight D downlink subframes and no special S subframes. In some examples, a parity bit may be added to codes to produce a four-bit code.

[0107] Codewords may be non-linear. The distance between any two codewords can be greater than or equal to 2*N, where N is the number of repetitions of a code 210 used for each codeword. The minimum distance between any code words can be at least two. As an example, if N = 8 repetitions, then the distance between any two code words could be 16. If N = 12 repetitions, then the distance between any two code words could be 24. Repetition of a code 210 could generate a sequence of bits from a code word. For N = 12 repetitions, the bit sequence can be denoted as b(0),b(1),...,b(47).

[0108] A base station, such as base station 105 of Figure 1, can scramble the bit block b(0), b(1),...,b(1) with a cell-specific sequence, resulting in a block of bits shuffled according to b'(i) = (b(i) + c(i))mod 2, where c(i) corresponds to the cell-specific sequence. The sequence generator for the cell-specific sequence can be initialized with an initialization code. The block of bits b(0), b(1),...,b(1) can also be shuffled based on the PLMN ID.

[0109] The block of scrambled bits b'(0),b'(1),...,b'(47) can be modulated using a quadrature phase shift keying (QPSK) modulation, resulting in a block of modulation symbols with complex values d(0), d(1),...,d(23). The modulated symbols can be mapped to two-port space-frequency block code (SFBC) symbols. The two ports can correspond to a first and a second base station antenna port. The first and second antenna ports can also be used for CUBS transmissions. The encryption output of SFBC can be a block of vectors y(i) = [y(0)(, ym(1) (i)] = 0, 1,2,3,..., 23.

[0110] Figure 3A shows an example 300-a of resource blocks (RBs) 305-a at 305-m of a channel of an unlicensed radio frequency spectrum band, in accordance with various aspects of the present disclosure. In some examples, the channel may have a bandwidth of 20 MHz, and may include a certain number of RBs, NRB (e.g., NRB = 100). Each RB 305-a through 305-m can include two enhanced resource element groups (eREGs). For example, RB 305-b may include eREG 2, 310-a and eREG 3, 310b. The index of each eREG can be associated with the indexes of the RBs. For example, the set of eREG indices associated with RB m can be 2m and 2m+l, where m = 0, 1,2,..., NRB - 1. Each eREG can be divided into six tones. For example, eREG 2, 310-a, can be divided into tones 315-a through 315-f.

[0111] CUBS can occupy two of the six tones of an eREG. For example, tone 0 315-a and tone 3 315-d of eREG 2, 310-a, can be occupied by CUBS. A UE, such as UE 115 of Figure 1, can expect to receive CUBS in an RB of the last OFDM symbol before a first DL subframe. CUBS can be used to estimate channel condition (similar to a reference signal). The choice of which two tones are occupied by CUBS may be a function of a cell identification (ID) and/or a public land mobile network (PLMN) ID.

[0112] One or more of the remaining tones of an eREG occupied by CUBS may be available for the frame format indicator. For example, tone 1, 315b, tone 2, 315-c, tone 4, 315-e and/or tone 5, 315-f, of eREG 2, 310-a may be available for the format indicator of frame. A frame format indicator mapped to an eREG can have the same power increase value as the CUBS that occupies the eREG, denoted as βFFI = βCUBS.

[0113] Modulated symbols mapped to two-port SFBC symbols ([y(0)(i), y(1)(i)]) can be multiplied by βFFI before being mapped to the eREG. The mapping to an eREG can be defined in terms of quadruplets of complex-valued symbols, denoted as zP(i) = βFFI {yp(4i), yp(4i+1), yp(4i+2), yp(4i+ 3)}, i=0, 1,2,3,4,5, and, that the symbol quadruple corresponds to the antenna port p. The ith quadruple mapped to eREG can be represented by , on what

[0114] Figure 3B shows an example of tones 300-b for carrying a frame format indicator, in accordance with various aspects of the present disclosure. Tones 315-a to 315-f may be eREG 2 tones (as shown in Figure 3A). Tones 320-a to 320-f may be eREG 3 tones (as shown in Figure 3A). CUBS can occupy two of the six tones of an eREG. For example, tone 0, 315-a, and tone 3, 315-d, of eREG 2, and tone 0, 320-a, and tone 3, 320-d, of eREG 3 can be occupied by CUBS . The remaining tones of an eREG that ports CUBS may carry a frame format indicator. For example, an eREG 2 frame format indicator, 325-a, may be carried by tone 1, 315b, tone 2, 315-c, tone 4, 315-e, and/or tone 5, 315-f , of eREG 2. An eREG 3 frame format indicator, 325-b, may be carried by tone 1, 320-b, tone 2, 320-c, tone 4, 320-e and/or tone 5, 320-f, from eREG 3.

[0115] Figure 4 shows another example 400 of resource blocks (RBs) 4050 to 40599 of a channel of an unlicensed radio frequency spectrum band, in accordance with various aspects of the present disclosure. In some examples, the channel may have a bandwidth of 20 MHz (e.g., NRB = 100). In some examples, a subset (NRB,FFI) of the 100 RBs 4050 to 40599 may be available for the frame format indicator. For example, 96 RBs may be available for the frame format indicator and four RBs may be omitted (NRB,FFI = 96). The availability of 96 RBs for the frame format indicator can simplify the mapping of the frame format indicator to the RBs and can also improve decoding performance (for example, due to the fact that 96 is a multiple of six). Additional frame format indicators from other base stations (e.g., base stations 105 of Figure 1) may be multiplexed into one or more of the 96 RBs.

[0116] RBs that may be omitted from availability for the frame format indicator may include RB 0, 4050, and RB 99, 40599. RB 0, 4050, and RB 99, 40599, may be on the edge of the spectrum of the channel and may experience degraded channel estimates. RB 49, 40549, and RB 50, 40550, can also be omitted from availability for the frame format indicator. RB 49, 40549, and RB 50, 40550, may be adjacent to the direct current (DC) carrier frequency, which may impact channel interpolation for such RBs. The eREGs of the remaining RBs available for the frame format indicator can be indexed as {0,1,2,3,...,2NRB,FFI - 1}. For example, if NRB,FFI = 96, then the set of eREGs available for the frame format indicator may have indices {0, 1,2,3,..., 191}.

[0117] Figure 5A shows an example 500-a of a radio frame, in accordance with various aspects of the present disclosure. The radio frame may represent a transmission opportunity. The radio frame may include subframe 0 to subframe 9. In some examples, subframe 9 of the previous radio frame may be a special first downlink subframe 505-a. The first special downlink subframe 505-a may include a D-CUBS. The first downlink special subframe 505-a may also include a first frame format indicator 510-a. In some examples, the frame format indicator may be transmitted in all OFDM symbols that carry D-CUBS. OFDM symbols in which fractional D-CUBS are transmitted may not include a frame format indicator. The first frame format indicator 510-a may indicate the TDD configuration for the current radio frame before the start of subframe 0. For example, the first frame format indicator 510-a may indicate a TDD configuration that includes six downlink subframes 515-a to 515-f, and two uplink subframes 525-a and 525-b (i.e., TDD configuration 5 of Figure 2). A special uplink subframe 520 may be configured before the uplink subframes 525-a and 525-b. The special uplink subframe 520 may include a U-CUBS and may also include additional downlink communications. After the uplink subframes 525-a and 525-b, a second special downlink subframe 505-b may be configured for subframe 9 of the current radio frame. The second downlink subframe 505-b may include a second frame format indicator 510-b and may also include additional uplink communications. The second frame format indicator may indicate a TDD setting for the next radio frame.

[0118] In some examples, a frame format indicator may be present in the last OFDM symbol of a subframe before the start of a downlink subframe. For example, if subframes 2 and 3 (515-c and 515-d) are inactive after downlink communications in subframes 0 and 1 (515-a and 515-b), then the first frame format indicator 510- a may be present in subframe 3 (515-d) before downlink communication resumes in subframe 4 (515-e). The first frame format indicator 510-a in subframe 3 (515-d) may indicate the same TDD configuration as the first frame format indicator 510-a in subframe 9 (505-a) of the previous radio frame.

[0119] In some cases, a frame format indicator may indicate a TDD setting for a subframe, a partial subframe, or a blank subframe. Similarly, the frame format indicator may indicate a TDD configuration for a transmission opportunity, such as any combination of a radio frame, a subframe, a blank subframe, and a partial subframe, such as simultaneously. The frame format indicator may indicate a TDD setting for additional subframes, blank subframes, or partial subframes through additional bits appended to the frame format indicator. In some cases, a frame format indicator that indicates a TDD setting for multiple radio frames, subframes, blank subframes, or partial subframes may include additional bits as a part of the frame format indicator prior to encryption of the format indicator. of frame. In some examples, a radio frame may have a partial subframe before or a partial subframe after the radio frame, such as for scheduling or formatting, which may enable the radio frame to be used for uplink and downlink transmissions. , as data. In some cases, blank subframes may be used, such as for timing purposes. For example, if two carriers are close in frequency but have different amounts of data to transmit on the downlink, the blank subframes can be added or attached to the carrier with less data so that the uplink can be started at the same time. same time for both carriers, as if the carriers were sufficiently close in frequency that they could not be used for uplink and downlink simultaneously.

[0120] The frame format indicator may indicate a TDD setting based on the size or length of subframes. For example, a frame format indicator that indicates a TDD setting for partial subframes can be used for small frame formats, such as 1 ms or 3 ms. In some cases, partial subframes can be used for small frame formats, up to a threshold, such as 5 ms or 6 ms, after which full subframes can be used. In some examples, if the frame format exceeds the threshold, partial subframes may not be used.

[0121] In some examples, the UE may determine that a frame format indicator 510 received during a current radio frame is invalid. The UE may determine that the frame format indicator 510 is invalid if the frame format indicator 510 indicates a TDD configuration that is not available as when the frame format indicator 510 is received. For example, if frame format indicator 510 is received in subframe 3 (515-d) and indicates a TDD configuration that has subframe 4 (515-e) as an uplink subframe, then the UE may determine that the frame format indicator 510 is invalid.

[0122] Figure 5B shows another example 500-b of a radio frame, in accordance with various aspects of the present disclosure. The radio frame may represent a transmission opportunity. The radio frame may include subframe 0 through subframe 9. The radio frame of Figure 5B may have the same TDD configuration as the radio frame of Figure 5A, however, the first four downlink subframes 515-a through 515- d may not perform a CCA procedure due to interference 530. Therefore, the first frame format indicator 510-a may not be present until subframe 3 (515-d), when interference 530 decreases and a CCA procedure is performed is detected. Although the first frame format indicator 510-a may be received in the middle of the current radio frame, the first frame format indicator 510-a may still indicate the TDD setting for the current radio frame. For example, as in Figure 5A, the first frame format indicator 510-a may indicate a TDD configuration that includes six downlink subframes 515-a to 515-f, and two uplink subframes 525-a and 525-b. (i.e., TDD 5 configuration from Figure 2). The first four downlink subframes 515-a to 515-d can be discounted, as they occurred before the detection of the CCA procedure performed. If a frame format indicator is received in the middle of a radio frame, a UE, such as UE 115 of Figure 1, may assume that any subframes occurring before the frame format indicator were downlink subframes that did not perform a CCA procedure. The remaining subframes 4 to 9 of Figure 5B can be configured the same as subframes 4 to 9 of Figure 5A. A special uplink subframe 520 may be configured before the uplink subframes 525-a and 525-b. The special uplink subframe 520 may include a U-CUBS and may also include additional downlink communications. After the uplink subframes 525-a and 525-b, a second special downlink subframe 505-b may be configured for subframe 9 of the current radio frame. The second downlink subframe 505-b may include a second frame format indicator 510-b and may also include additional uplink communications. The second frame format indicator may indicate a TDD setting for the next radio frame.

[0123] Figure 6 shows a block diagram 600 of a UE 615 for use in wireless communication, in accordance with various aspects of the present disclosure. In some examples, the UE 615 may be an example of aspects of the UE 115 described with reference to Figure 1. The UE 615 may also include a processor. The UE 615 may include a UE 610 receiver component, a UE 620 frame format indicator component, and/or a UE 630 transmitter component. Each of these components may be in communication with the other.

[0124] The components of the UE 615 may, individually or collectively, be implemented using one or more application-specific integrated circuits (ASICs) adapted to perform all or part of the applicable hardware functions. Alternatively, the functions may be performed by one or more different processing units (or cores), on one or more integrated circuits. In other examples, other types of integrated circuits may be used (e.g., structured/platform ASICs, Field Programmable Gate Arrays (FPGAs, and other semi-custom ICs), which may be programmed in any manner known in the art. Each unit can also be implemented, in whole or in part, with instructions embedded in memory, formatted to be executed by one or more general or application-specific processors.

[0125] In some examples, the UE receiver component 610 may include at least one radio frequency (RF) receiver, such as at least one RF receiver operable to receive transmissions over a licensed radio frequency spectrum band (e.g., a radio frequency spectrum band to which devices do not request access as the radio frequency spectrum band is licensed to one or more users (e.g., LTE/LTE-A users) for some uses) and/or a unlicensed radio frequency spectrum band (e.g., a radio frequency spectrum band to which devices may need to request access because the radio frequency spectrum band is available, at least in part, for unlicensed use (e.g. , use of Wi-Fi and/or use of LTE/LTE-A in an unlicensed radio frequency spectrum band)). In some examples, the licensed radio frequency spectrum band and/or the unlicensed radio frequency spectrum band may be used for communicating a radio frame and/or a frame format indicator, as described, for example, with reference to Figures 1 to 5. The UE 610 receiver component may, in some cases, include separate receivers for the licensed radio frequency spectrum band and the unlicensed radio frequency spectrum band. The separate receivers may, in some examples, take the form of a licensed RF spectrum band receiver component 612 for communicating across the licensed radio frequency spectrum band, and an unlicensed RF spectrum band receiver component 612 614 to communicate over the unlicensed radio frequency spectrum band. The receiver component of UE 610 may also include receiver components for communicating via other radio frequency spectrum bands and/or for communicating via other radio access technologies (e.g., Wi-Fi). The UE receiver component 610, which includes the licensed RF spectrum band receiver component 612 and/or the unlicensed RF spectrum band receiver component 614 can be used to receive various types of data signals and /or control (i.e., transmissions) via one or more communication links of a wireless communication system, such as one or more communication links of the wireless communications system 100 described with reference to Figure 1. Communication may be established through the licensed radio frequency spectrum band and/or the unlicensed radio frequency spectrum band.

[0126] In some examples, the transmitter component of UE 630 may include at least one RF transmitter, such as at least one RF transmitter operable to transmit over the licensed radio frequency spectrum band and/or the radio frequency spectrum band unlicensed. The transmitter component of UE 630 may, in some cases, include separate transmitters for the licensed radio frequency spectrum band and the unlicensed radio frequency spectrum band. The separate transmitters may, in some examples, take the form of a licensed RF spectrum band transmitter component 632 for communicating across the licensed radio frequency spectrum band, and an unlicensed RF spectrum band transmitter component 632 634 to communicate over the unlicensed radio frequency spectrum band. The UE transmitter component 630, which includes the licensed RF spectrum band transmitter component 632 and/or the unlicensed RF spectrum band transmitter component 634 can be used to transmit various types of data signals and /or control (i.e., transmissions) via one or more communication links of a wireless communication system, such as one or more communication links of the wireless communications system 100 described with reference to Figure 1. Communication may be established through the licensed radio frequency spectrum band and/or the unlicensed radio frequency spectrum band.

[0127] In some examples, the UE frame format indicator component 620 may receive a frame format indicator from a base station. The UE frame format indicator component 620 may receive the frame format indicator in an eREG from a base station RB. The RB that contains the eREG can be located between an edge of a system bandwidth and a direct current (DC) carrier of the system bandwidth. The frame format indicator can be received in an OFDM symbol corresponding to the eREG. The OFDM symbol may be received before a downlink subframe of the current radio frame. The ODFM symbol can also carry a CUBS. The UE frame format indicator component 620 may decode the frame format indicator received before an end of a first downlink subframe of the current radio frame. Decoding the frame format indicator may include demodulating and unscrambling the frame format indicator to obtain a code word. The code word can be associated with a TDD configuration.

[0128] In some examples, the UE frame format indicator component 620 may include a UE TDD configuration component 635. The UE TDD configuration component 635 may determine a TDD configuration for the current subframe with based on the code word. The codeword may include repetitions of a code, and the code may indicate the TDD configuration for the TDD configuration components of UE 635. In some examples, the code may indicate a number of downlink subframes between two special subframes. The UE TDD configuration component 635 may determine the TDD configuration for the current subframe based on the number.

[0129] In some examples, the UE frame format indicator component 620 may receive a second frame format indicator during a subframe of the current radio frame. The UE TDD configuration component 635 may invalidate the second frame format indicator based, at least in part, in which subframe the second frame format indicator is received.

[0130] In some examples, the UE TDD configuration component 635 may determine the TDD configuration includes at least one uplink subframe corresponding to an inter-carrier grant of a primary cell. The UE TDD configuration component 635 may configure the uplink subframe if the inter-carrier grant occurred at least four subframes before the scheduled uplink subframe. In some examples, the UE TDD configuration component 635 may determine that the TDD configuration includes at least one uplink subframe corresponding to a self-scheduled uplink grant. The UE TDD configuration component 635 may configure the uplink subframe if the self-scheduled uplink grant occurred more than four subframes before the self-scheduled uplink subframe.

[0131] Figure 7 shows a system 700 for use in wireless communication, in accordance with various aspects of the present disclosure. System 700 may include a UE 715, which may be an example of the UEs 115 of Figure 1. The UE 715 may also be an example of one or more aspects of the UE 615 of Figure 6.

[0132] The UE 715 may include components for two-way data and voice communications that include components for transmitting communications and components for receiving communications. The UE 715 may include UE antenna(s) 740, UE transceiver component(s) 735, a UE processor component 705, and a UE memory component 710 (which includes software code 750), wherein each one may be communicating, directly or indirectly, with others (e.g., via one or more buses 745). The UE 735 transceiver component(s) may be configured to communicate bidirectionally, through the UE 740 antenna(s) and/or one or more more wired or wireless links, with one or more networks, as described above. For example, the UE transceiver component(s) 735 may be configured to communicate bidirectionally with the base stations 105 with reference to Figure 1. The component(s) UE transceiver s) 735 may include a modem configured to modulate packets and provide the modulated packets to the UE antenna(s) 740 for transmission and to demodulate packets received from the ) antenna(s) of UE 740. Although the UE 715 may include a single antenna 740, the UE 715 may have multiple antennas 740 capable of simultaneously transmitting and/or receiving multiple wireless transmissions. The UE transceiver component 735 may co-communicate with one or more base stations 105 via multiple component carriers. The UE 715 may also include a UE 720 frame format indicator component, which may perform the functions described above for the UE 620 frame format indicator component of the UE 615 of Figure 6.

[0133] The memory component of UE 710 may include random access memory (RAM) and read-only memory (ROM). The UE memory component 710 may store computer-executable and computer-readable software/firmware code 750 that contains instructions that are configured to, when executed, cause the UE processor component 705 to perform various functions described herein. (e.g. determining a TDD setting of a frame format indicator, etc.). Alternatively, the computer-executable and computer-readable software/firmware code 750 may not be directly executable by the UE processor component 705, but be configured to cause a computer (e.g., when compiled and executed) to perform functions described in this document. The processor component of UE 705 may include an intelligent hardware device, e.g., a central processing unit (CPU), a microcontroller, an application-specific integrated circuit (ASIC), etc.

[0134] Figure 8 shows a block diagram 800 of a base station 805 for use in wireless communication, in accordance with various aspects of the present disclosure. In some examples, the base station 805 may be an example of aspects of the base station 105 described with reference to Figure 1. The base station 805 may also be a processor. The base station 805 may include a base station receiver component 810, a base station frame format indicator component 820, and/or a base station transmitter component 830. Each of these components may be in communication with each other. with the other.

[0135] The UE 805 base station components may be deployed, individually or collectively, using one or more application-specific integrated circuits (ASICs) adapted to perform all or part of the applicable hardware functions. Alternatively, the functions may be performed by one or more different processing units (or cores), on one or more integrated circuits. In other examples, other types of integrated circuits may be used (e.g., structured/platform ASICs, Field Programmable Gate Arrays (FPGAs, and other semi-custom ICs), which may be programmed in any manner known in the art. Each unit can also be implemented, in whole or in part, with instructions embedded in memory, formatted to be executed by one or more general or application-specific processors.

[0136] In some examples, the base station receiver component 810 may include at least one radio frequency (RF) receiver, such as at least one RF receiver operable to receive transmissions over a licensed radio frequency spectrum band (e.g. example, a radio frequency spectrum band to which devices do not request access as the radio frequency spectrum band is licensed to one or more users (e.g., LTE/LTE-A users) for some uses) and/ or a band of unlicensed radio frequency spectrum (for example, a band of radio frequency spectrum to which devices may need to request access because the band of radio frequency spectrum is available, at least in part, for unlicensed use ( e.g., use of Wi-Fi and/or use of LTE/LTE-A in an unlicensed radio frequency spectrum band)). In some examples, the licensed radio frequency spectrum band and/or the unlicensed radio frequency spectrum band may be used for communicating a radio frame and/or a frame format indicator, as described, for example, with reference to Figures 1 to 5. The base station receiver component 810 may, in some cases, include separate receivers for the licensed radio frequency spectrum band and the unlicensed radio frequency spectrum band. The separate receivers may, in some examples, take the form of a licensed RF spectrum band receiver component 812 for communicating across the licensed radio frequency spectrum band, and an unlicensed RF spectrum band receiver component 812 814 to communicate over the unlicensed radio frequency spectrum band. Base station receiver component 810 may also include receiver components for communicating via other radio frequency spectrum bands and/or for communicating via other radio access technologies (e.g., Wi-Fi). The base station receiver component 810, which includes the licensed RF spectrum band receiver component 812 and/or the unlicensed RF spectrum band receiver component 814 can be used to receive various types of radio signals. data and/or control (i.e., transmissions) over one or more communication links of a wireless communication system, such as one or more communication links of the wireless communication system 100 described with reference to Figure 1. Communication links may be established across the licensed radio frequency spectrum band and/or the unlicensed radio frequency spectrum band.

[0137] In some examples, the base station transmitter component 830 may include at least one RF transmitter, such as at least one RF transmitter operable to transmit across the licensed radio frequency spectrum band and/or the spectrum band unlicensed radio frequency. The base station transmitter component 830 may, in some cases, include separate transmitters for the licensed radio frequency spectrum band and the unlicensed radio frequency spectrum band. The separate transmitters may, in some examples, take the form of a licensed RF spectrum band transmitter component 832 for communicating across the licensed radio frequency spectrum band, and an unlicensed RF spectrum band transmitter component 834 to communicate over the unlicensed radio frequency spectrum band. The base station transmitter component 830, which includes the licensed RF spectrum band transmitter component 832 and/or the unlicensed RF spectrum band transmitter component 834 can be used to transmit various types of radio signals. data and/or control (i.e., transmissions) over one or more communication links of a wireless communication system, such as one or more communication links of the wireless communication system 100 described with reference to Figure 1. Communication links may be established across the licensed radio frequency spectrum band and/or the unlicensed radio frequency spectrum band.

[0138] In some examples, the base station frame format indicator component 820 may transmit a frame format indicator to a UE. In some examples, the base station frame format indicator component 820 may also include a TDD configuration component 835 and an encryption component 840.

[0139] In some examples, the frame format indicator may include a code word associated with a TDD configuration. The encryption component 840 may scramble the codeword with a string associated with the base station 805. Alternatively or additionally, the string may be associated with a public land mobile network (PLMN) identification. The encryption component 840 can then modulate the scrambled codeword with quadrature phase shift keying (QPSK). In some examples, the encryption component 840 may map the codeword to space-frequency block code (SFBC) symbols associated with two antenna ports of the base station 805. In some examples, the two antenna ports may correspond to antenna ports for channel usage warning signal (CUBS) transmissions. In some examples, the encryption component 840 may map SFBC symbols to an enhanced resource element group (eREG) of an RB.

[0140] The RB configured with the frame format indicator can be located between an edge of a bandwidth system and a direct current (DC) carrier of the bandwidth system. In some examples, the encryption component 840 may multiplex the frame format indicator with a second frame format indicator from a second base station.

[0141] In some examples, the base station frame format indicator component 820 may transmit the frame format indicator in an orthogonal frequency division multiplexing (OFDM) symbol before a downlink subframe of the base station frame. radio. In some examples, the OFDM symbol may also carry a channel usage warning signal (CUBS).

[0142] In some examples, the TDD configuration component 835 may determine a TDD configuration for the current radio frame. The TDD configuration can include uplink subframes, downlink subframes, and special subframes. The TDD configuration component 835 may determine an available configuration of uplink subframes, downlink subframes, and special subframes. The TDD configuration component 835 may then determine a code to indicate the TDD configuration. In some examples, the code may indicate a number of downlink subframes between two special subframes. The TDD configuration component 835 may repeat the code to generate a code word. The TDD configuration component 835 may then pass the codeword to the encryption component 840 for inclusion in the frame format indicator.

[0143] In some examples, the TDD configuration component 835 may determine a TDD configuration that includes at least one uplink subframe corresponding to an inter-carrier lease of a primary cell. The base station frame format indicator component 820 may transmit the corresponding frame format indicator at least four subframes before the scheduled uplink subframe. In some examples, the TDD configuration component 835 may determine a TDD configuration that includes at least one uplink subframe corresponding to a UE self-scheduled uplink grant. The base station frame format indicator component 820 may transmit the corresponding frame format indicator more than four subframes before the self-scheduled uplink subframe.

[0144] Figure 9 shows a block diagram 900 of a base station 905 for use in wireless communication, in accordance with various aspects of the present disclosure. In some examples, the base station 905 may be an example of aspects of the base station 105 described with reference to Figure 1 and/or the base station 805 described with reference to Figure 8. The base station 905 may also be a processor. The base station 905 may include a base station receiver component 910, a base station frame format indicator component 920, and/or a base station transmitter component 930. Each of these components may be in communication with each other. with the other.

[0145] The UE 905 base station components may be deployed, individually or collectively, using one or more application-specific integrated circuits (ASICs) adapted to perform all or part of the applicable hardware functions. Alternatively, the functions may be performed by one or more different processing units (or cores), on one or more integrated circuits. In other examples, other types of integrated circuits may be used (e.g., Structured/Platform ASICs, Field Programmable Gate Arrays (FPGAs), and other semi-custom ICs), which may be programmed in any manner known in the art. The functions of each unit can also be implemented, in whole or in part, with instructions embedded in a memory, formatted to be executed by one or more general or application-specific processors.

[0146] In some examples, the base station receiver component 910 may include at least one radio frequency (RF) receiver, such as at least one RF receiver operable to receive transmissions over a licensed radio frequency spectrum band (e.g. example, a radio frequency spectrum band to which devices do not request access as the radio frequency spectrum band is licensed to one or more users (e.g., LTE/LTE-A users) for some uses) and/ or a band of unlicensed radio frequency spectrum (for example, a band of radio frequency spectrum to which devices may need to request access because the band of radio frequency spectrum is available, at least in part, for unlicensed use ( e.g., use of Wi-Fi and/or use of LTE/LTE-A in an unlicensed radio frequency spectrum band)). In some examples, the licensed radio frequency spectrum band and/or the unlicensed radio frequency spectrum band may be used for communicating a radio frame and/or a frame format indicator, as described, for example, with reference to Figures 1 to 5. The base station receiver component 910 may, in some cases, include separate receivers for the licensed radio frequency spectrum band and the unlicensed radio frequency spectrum band. The separate receivers may, in some examples, take the form of a licensed RF spectrum band receiver component 912 for communicating across the licensed radio frequency spectrum band, and an unlicensed RF spectrum band receiver component 912 914 to communicate over the unlicensed radio frequency spectrum band. The base station receiver component 910 may also include receiver components for communicating via other radio frequency spectrum bands and/or for communicating via other radio access technologies (e.g., Wi-Fi). The base station receiver component 910, which includes the licensed RF spectrum band receiver component 912 and/or the unlicensed RF spectrum band receiver component 914 can be used to receive various types of radio signals. data and/or control (i.e., transmissions) over one or more communication links of a wireless communication system, such as one or more communication links of the wireless communication system 100 described with reference to Figure 1. Communication links may be established across the licensed radio frequency spectrum band and/or the unlicensed radio frequency spectrum band.

[0147] In some examples, the base station transmitter component 930 may include at least one RF transmitter, such as at least one RF transmitter operable to transmit across the licensed radio frequency spectrum band and/or the spectrum band unlicensed radio frequency. The base station transmitter component 930 may, in some cases, include separate transmitters for the licensed radio frequency spectrum band and the unlicensed radio frequency spectrum band. The separate transmitters may, in some examples, take the form of a licensed RF spectrum band transmitter component 932 for communicating across the licensed radio frequency spectrum band, and an unlicensed RF spectrum band transmitter component 934 to communicate over the unlicensed radio frequency spectrum band. The base station transmitter component 930, which includes the licensed RF spectrum band transmitter component 932 and/or the unlicensed RF spectrum band transmitter component 934 can be used to transmit various types of radio signals. data and/or control (i.e., transmissions) over one or more communication links of a wireless communication system, such as one or more communication links of the wireless communication system 100 described with reference to Figure 1. Communication links may be established across the licensed radio frequency spectrum band and/or the unlicensed radio frequency spectrum band.

[0148] In some examples, the base station frame format indicator component 920 may be an example of one or more aspects of the base station frame format indicator component 820 described with reference to Figure 8. The base station frame format indicator 920 may include a TDD configuration component 935 and an encryption component 940. The TDD configuration component 935 and the encryption component 940 may be examples of one or more aspects of the configuration component of TDD 835 and encryption component 840 described with reference to Figure 8.

[0149] In some examples, the base station frame format indicator component 920 may also include an eCCA component 945. The eCCA component 945 may perform an eCCA procedure to determine whether a channel of a spectrum band is Unlicensed radio frequency is available for use as an uplink channel or as a downlink channel. Once the eCCA component 945 completes an eCCA procedure and determines that a channel may be available for downlink, the eCCA component 945 may generate a D-CUBS. The TDD configuration component 935 may then determine an available TDD configuration based, at least in part, on when, within the radio frame, the eCCA procedure is completed. The determined available TDD configuration may include a first uplink subframe that is at least four subframes after the eCCA procedure is completed. In some examples, the encryption component 940 may configure an eREG that ports the D-CUBS to also port the frame format indicator.

[0150] Figure 10 shows a block diagram 1000 of a base station 1005 (e.g., a base station that forms part or all of an eNB) for use in wireless communication, in accordance with various aspects of the present disclosure. In some examples, the base station 1005 may be an example of aspects of one or more of the base stations 105 described with reference to Figure 1 and/or aspects of one or more of the base stations 805 and/or 905, as described with reference to Figures 8 and/or 9. Base station 1005 may be configured to implement or facilitate at least part of the base station features and functions described with reference to Figures 1 to 9.

[0151] The base station 1005 may include a base station processor component 1010, a base station memory component 1015, at least one base station transceiver component (represented by the component(s) base station transceiver component 1050), at least one base station antenna (represented by base station antenna(s) 1055) and/or a base station frame format indicator component 1020. The base station 1005 may also include one or more of a base station communications component 1030 and/or a network communications component 1040. Each of these components may be in communication with each other, directly or indirectly, through one or more 1035 buses.

[0152] The base station memory component 1015 may include a Random Access Memory (RAM) and/or a Read-Only Memory (ROM). The base station memory component 1015 may store computer-executable and computer-readable software/firmware code 1025 that contains instructions that are configured to, when executed, cause the base station processor component 1010 to perform various functions described in this document with respect to wireless communication (e.g., transmitting a frame format indicator corresponding to a TDD configuration, etc.). Alternatively, the machine-readable, executable software/firmware code 1025 may not be directly executable by the base station processor component 1010, but be configured to cause the base station 1005 to (e.g., when compiled and executed) perform many of the functions described in this document.

[0153] The base station processor component 1010 may include an intelligent hardware device, e.g., a central processing unit CPU, a microcontroller, an ASIC, etc. The base station processor component 1010 may process information received through the base station transceiver component(s) 1050, the base station communications component 1030, and/or the network communications component 1040 The base station processor component 1010 may also process information to be sent to the transceiver component(s) 1050 for transmission via the antenna(s) 1055 to the base station communications component 1030. for transmission to one or more other base stations 105-a and 105-b and/or to the network communications component 1040 for transmission to a core network 1045, which may be an example of one or more aspects of the core network 130 described in reference to Figure 1. The base station processor component 1010 may handle, alone or in connection with the base station frame format indicator component 1020, various aspects of determining a TDD configuration and generating a format indicator. of frame.

[0154] The base station transceiver component(s) 1050 may include a modem configured to modulate packets and provide the modulated packets to the base station antenna(s) 1055 for transmission and to demodulate packets received from the base station antenna(s) 1055. The base station transceiver components 1050 may, in some examples, be deployed as one or more transmitter components. base station and one or more separate base station receiver components. The base station transceiver component(s) 1050 may support communications in a licensed radio frequency spectrum band and an unlicensed radio frequency spectrum band. The base station transceiver component(s) 1050 may be configured to communicate bidirectionally, via the antenna(s) 1055, with one or more UEs or devices , such as one or more of the UEs 15 described with reference to Figure 1 and/or UEs 615 and/or 715 described with reference to Figures 6 and/or 7. The base station 1005 may, for example, include multiple antennas. base station 1055 (e.g., an antenna array). Base station 1005 may communicate with core network 1045 via network communications component 1040. Base station 1005 may also communicate with other base stations, such as base stations 105-a and 105-b, with the use of the base station communications component 1030.

[0155] The base station frame format indicator component 1020 may be configured to perform and/or control some or all of the features and/or functions described with reference to Figures 1 to 9 relating to the generation and/or transmission of a frame format indicator. The base station frame format indicator component 1020, or portions of the base station frame format indicator component 1020, may include a processor and/or some or all of the functions of the base station frame format indicator component 1020. base station 1020 may be performed by the base station processor component 1010 and/or in connection with the base station processor component 1010. In some examples, the base station frame format indicator component 1020 may be an example of the base station frame format indicator component 820 and/or 920 described with reference to Figures 8 and/or 9.

[0156] Figure 11 is a flowchart illustrating an example of a method 1100 for wireless communication, in accordance with various aspects of the present disclosure. For clarity, method 1100 is described below with reference to aspects of one or more of the UEs described with reference to Figures 1 to 9. In some examples, a UE may execute one or more sets of codes to control functional elements of the UE. to perform the functions described below. Additionally or alternatively, the UE may perform one or more of the functions described below using special purpose hardware.

[0157] In block 1105, method 1100 may include receiving a frame format indicator associated with a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band. In some examples, the frame format indicator may be received before a first subframe of the transmission opportunity. In other examples, the frame format indicator may be received during a middle portion of the transmission opportunity. In block 1110, method 1100 may include decoding the frame format indicator. In some examples, the frame format indicator may be decoded prior to an edge of a first downlink subframe of the transmission opportunity. In some examples, the frame format indicator may include a codeword associated with a TDD configuration, and decoding the frame format indicator may include decoding the codeword. In block 1115, method 1100 may include determining a TDD setting for the transmission opportunity based, at least in part, on the decoded frame format indicator. In block 1120, method 1100 may include configuring a subframe of the transmission opportunity based on the determined TDD configuration. The subframe may be configured as an uplink subframe, a downlink subframe, a first special subframe S, or a second special subframe S'. Operations in blocks 1105, 1110, 1115, and 1120 can be performed using the UE frame format indicator component 620 and/or 720 described with reference to Figures 6 and 7.

[0158] In this way, method 1100 can provide wireless communication. It should be noted that method 1100 is only one implementation and that the operations of method 1100 may be rearranged or otherwise modified so that other implementations are possible.

[0159] Figure 12 is a flowchart illustrating an example of a method 1200 for wireless communication, in accordance with various aspects of the present disclosure. For clarity, method 1200 is described below with reference to aspects of one or more of the base stations described with reference to Figures 1 to 9. In some examples, a base station may execute one or more sets of codes to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, the base station may perform one or more of the functions described below using special purpose hardware.

[0160] In block 1205, method 1200 may include determining a time division duplexing (TDD) configuration for a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band. In block 1210, method 1200 may include generating a frame format indicator associated with the transmission opportunity, wherein the frame format indicator is based, at least in part, on the TDD configuration. In some examples, generating the frame format indicator may include scrambling a codeword associated with the TDD configuration with a string. The scrambled codeword can be modulated with quadrature phase shift keying (QPSK) and mapped to space-frequency block code (SFBC) symbols. SFBC symbols can be mapped to an enhanced resource element group (eREG) of a resource block (RB). In block 1215, method 1200 may include transmitting the frame format indicator associated with the transmission opportunity. Operations in blocks 1205, 1210 and 1215 can be performed using the base station frame format indicator component 820, 920 and/or 1020 described with reference to Figures 8, 9 and 10.

[0161] In this way, method 1200 can provide wireless communication. It should be noted that method 1200 is only one implementation and that the operations of method 1200 may be rearranged or otherwise modified so that other implementations are possible.

[0162] Figure 13 is a flowchart illustrating an example of a method 1300 for wireless communication, in accordance with various aspects of the present disclosure. For clarity, method 1300 is described below with reference to aspects of one or more of the base stations described with reference to Figures 1 to 9. In some examples, a base station may execute one or more sets of codes to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, the base station may perform one or more of the functions described below using special purpose hardware.

[0163] In block 1305, method 1300 may include performing an extended clear channel assessment (eCCA). In block 1310, method 1300 may include determining a time division duplexing (TDD) configuration for a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band based, at least in part, on the eCCA. In some examples, eCCA may complete at least four subframes before an uplink subframe of the TDD configuration. In block 1315, method 1300 may include generating a frame format indicator associated with the transmission opportunity, wherein the frame format indicator is based, at least in part, on the TDD configuration. In some examples, generating the frame format indicator may include scrambling a codeword associated with the TDD configuration with a sequence. The scrambled codeword can be modulated with quadrature phase shift keying (QPSK) and mapped to space-frequency block code (SFBC) symbols. SFBC symbols can be mapped to an enhanced resource element group (eREG) of a resource block (RB). In block 1320, method 1300 may include transmitting the frame format indicator associated with the transmission opportunity. Operations in blocks 1305, 1310, 1315 and 1320 can be performed using the base station frame format indicator component 820, 920 and/or 1020 described with reference to Figures 8, 9 and 10.

[0164] In this way, method 1300 can provide wireless communication. It should be noted that method 1300 is only one implementation and that the operations of method 1300 may be rearranged or otherwise modified so that other implementations are possible.

[0165] In some examples, aspects of two or more of methods 1100, 1200 and/or 1300 may be combined. It should be noted that methods 1100, 1200 and/or 1300 are exemplary implementations only and that the operations of methods 1100, 1200 and/or 1300 may be rearranged or otherwise modified so that other implementations are possible.

[0166] The techniques described in this document can be used for various wireless communications systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other systems. The terms “system” and “network” are often used interchangeably. A CDMA system can deploy radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000, IS-95 and IS-856 standards. Releases 0 and A of IS-2000 are commonly called CDMA2000 IX, IX, etc. IS-856 (TIA-856) is commonly called lxEV-DO of CDMA2000, High Rate Packet Data (HRPD), etc. UTRA includes Broadband CDMA (WCDMA) and other CDMA variants. A TDMA system can implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA system can implement radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM™, etc. UTRA and E-UTRA are parts of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new UMTS releases that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization called the “Third Generation Partnership Project” (3GPP). CDMA2000 and UMB are described in documents from an organization called “Third Generation Partnership Project 2” (3GPP2). The techniques described herein can be used for the radio systems and technologies mentioned above as well as other radio systems and technologies, which include cellular communications (e.g., LTE) over an unlicensed and/or shared bandwidth. The above description, however, describes an LTE/LTE-A system for example purposes, and LTE terminology is used throughout much of the above description, although the techniques are applicable beyond LTE/LTE-A applications.

[0167] The detailed description set forth above in connection with the attached drawings describes examples and does not represent only those examples that can be implemented or that are within the scope of the claims. The terms “example” and “exemplary”, when used in this description, mean “serving as an example, occurrence or illustration”, and not “preferred” or “advantageous over other examples”. The detailed description includes specific details for the purpose of providing an understanding of the techniques described. These techniques, however, can be practiced without these specific details. In some examples, known structures and apparatus are shown in block diagram form in order to avoid obscuring concepts in the examples described.

[0168] Information and signals can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols and integrated circuits that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic particles or fields, optical particles or fields or any combination thereof.

[0169] The various illustrative blocks and modules described together in connection with the disclosure herein may be implemented or realized with a general purpose processor, a digital signal processor (DSP), an ASIC, an FPGA or other programmable logic device , discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this document. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be deployed as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0170] The functions described in this document can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, functions can be stored or transmitted through one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software, the functions described above may be implemented using software running by a processor, hardware, firmware, wired connection, or combinations of any of these. Resource deployment functions may also be physically located in multiple locations, which includes being distributed so that portions of the functions are deployed in different physical locations. As used herein, inclusive of the claims, the term “and/or”, when used in a list of two or more items, means that any one of the items listed may be employed alone, or any combination of two or more of the following. The listed items can be employed. For example, if a composition is described to contain components A, B and/or C, the composition may contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B and C in combination. Additionally, as used herein, including in the claims, “or” as used in a list of items (e.g., a list of items preceded by a phrase such as “at least one of” or “one or more of” ), indicates a disjunctive list so that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (that is, A and B and C ).

[0171] Computer-readable media includes both computer storage media and communication media, including any media that facilitates the transfer of a computer program from one location to another. A storage medium can be any available media that can be accessed by a general purpose or specific purpose computer. By way of example, and without limitation, computer-readable media may comprise RAM, ROM, EEPROM, flash memory, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other media that can be used to carry or store desired program code means in the form of instructions or data structures and can be accessed by a general purpose or special purpose computer or a general purpose or specific purpose processor. Also, any connection can be properly termed as a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscription line (DSL), or wireless technologies such as infrared, radio and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. Magnetic disc and optical disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where magnetic discs often reproduce data in a magnetic, while optical discs reproduce data optically with lasers. Combinations of the foregoing are also included within the scope of computer-readable media.

[0172] The foregoing description of the disclosure is provided to enable any person skilled in the art to produce or use the disclosure. Various modifications in such embodiments will be immediately apparent to those skilled in the art and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Therefore, the disclosure should not be limited to the examples and designs described herein, but should be compatible with the broadest scope consistent with the principles and innovative features disclosed herein.

Claims (15)

1. Method for wireless communication in a user equipment, UE, characterized in that it comprises: receiving (1105), from a base station, a frame format indicator associated with a transmission opportunity for transmissions in a unlicensed radio frequency spectrum band; and determining (1115) a time division duplexing, TDD, configuration for the transmission opportunity based, at least in part, on the frame format indicator. 2. Method according to claim 1, characterized by the fact that the frame format indicator comprises a code word associated with the TDD configuration. 3. The method of claim 2, further comprising: receiving the frame format indicator in a bit stream, wherein the length of the bit stream is determined by a number of cyclic word extensions of code. 4. The method of claim 1, wherein the frame format indicator is carried by at least one enhanced resource element group, eREG, of a resource block, RB, or wherein the indicator of frame format is multiplexed with a second frame format indicator of a second base station. 5. The method of claim 1, further comprising: receiving the frame format indicator in an orthogonal frequency division multiplexing, OFDM, symbol prior to a downlink subframe of the transmission opportunity ; or which further comprises: receiving the frame format indicator prior to a first subframe of the transmission opportunity, or which further comprises: receiving the frame format indicator during a middle portion of the transmission opportunity, or which further comprises: decoding the frame format indicator before an end of a first downlink subframe of the transmission opportunity, or further comprising: receiving a second frame format indicator during a subframe of the transmission opportunity; and invalidating the second frame format indicator based, at least in part, in which subframe the second frame format indicator is received. 6. Method according to claim 1, characterized in that the TDD configuration comprises at least one of an uplink subframe corresponding to a concession between carriers of a primary cell, an uplink subframe corresponding to a concession self-scheduled uplink subframe, a downlink subframe, and an uplink subframe, or combinations thereof. 7. Method for wireless communication at a base station, comprising: determining (1205) a time division duplexing, TDD, configuration for a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band ; and transmitting (1215), to a user equipment, UE, a frame format indicator associated with the transmission opportunity, the frame format indicator being based, at least in part, on the TDD configuration. 8. Method according to claim 7, characterized by the fact that the frame format indicator comprises a code word associated with the TDD configuration. 9. Method according to claim 8, characterized by the fact that it further comprises: scrambling the code word with a sequence associated with a base station. 10. The method of claim 9, further comprising: modulating the scrambled codeword with quadrature phase shift keying, QPSK. 11. The method of claim 8, further comprising: mapping the code word to space-frequency block code symbols, SFBC, associated with two antenna ports; or which further comprises: cyclically extending the code word a specified number of times; and transmitting the frame format indicator in a bitstream, wherein the length of the bitstream is determined by the number of cyclic extensions of the codeword. 12. The method of claim 7, further comprising: multiplexing the frame format indicator with a second frame format indicator from a second base station, or further comprising: transmitting the frame format indicator frame in an orthogonal frequency division multiplexing, OFDM, symbol, before a downlink subframe of the transmission opportunity, or which further comprises: transmitting the frame format indicator before a first subframe of the transmission opportunity, or which further comprises: transmitting the frame format indicator during a middle portion of the transmission opportunity, or which further comprises: transmitting a second frame format indicator during a subframe of the transmission opportunity, or which further comprises: performing an evaluation of extended clear channel, eCCA; and determine the TDD configuration based, at least in part, on eCCA. 13. Method for wireless communication at a base station, comprising: identifying a plurality of TDD configurations, wherein each of the plurality of TDD configurations comprises different numbers of uplink subframes and downlink subframes downward; and identifying an available TDD configuration from among the plurality of TDD configurations for a transmission opportunity for transmissions in an unlicensed radio frequency spectrum band, wherein the available TDD configuration is indicated by a transmitted frame format indicator for a user equipment, EU. 14. Method, according to claim 13, characterized by the fact that each of the plurality of TDD configurations comprises ten subframes; wherein each of the plurality of TDD configurations comprises at least one spatial subframe, or wherein a first subframe of each of the plurality of TDD configurations comprises a downlink subframe; or wherein a last subframe of each of the plurality of TDD configurations comprises a spatial subframe; or wherein the plurality of TDD configurations comprises: a first TDD configuration comprising a downlink subframe, a first spatial subframe, seven uplink subframes, and a second spatial subframe; a second TDD configuration comprising two downlink subframes, a first spatial subframe, six uplink subframes, and a second spatial subframe; a third TDD configuration comprising three downlink subframes, a first spatial subframe, five uplink subframes, and a second spatial subframe; a fourth TDD configuration comprising four downlink subframes, a first spatial subframe, four uplink subframes, and a second spatial subframe; a fifth TDD configuration comprising five downlink subframes, a first spatial subframe, three uplink subframes, and a second spatial subframe; a sixth TDD configuration comprising six downlink subframes, a first spatial subframe, two uplink subframes, and a second spatial subframe; a seventh TDD configuration comprising seven downlink subframes, a first spatial subframe, an uplink subframe, and a second spatial subframe; and an eighth TDD configuration comprising nine downlink subframes and a second space subframe. 15. Apparatus for wireless communication, characterized in that it comprises: arranged means for carrying out the steps of the methods as defined in any one of claims 1 to 14.