Harq design for LTE in unlicensed spectrum utilizing individual ACK/NACK

Methods, systems, and apparatuses are described for wireless communications. In one method, a sequence number corresponding to a data frame and one or more data subframes of the data frame may be transmitted over an unlicensed spectrum to a user equipment (UE), and hybrid automatic repeat request (HARQ) feedback for the one or more data subframes may be received over the unlicensed spectrum, from the UE, when the sequence number corresponding to the data frame is received by the UE in a specified order. In another method, a sequence number corresponding to a data frame and HARQ feedback may be transmitted over an unlicensed spectrum to a UE, and one or more data subframes may be received over the unlicensed spectrum, from the UE, in response to the HARQ feedback when the sequence number corresponding to the data frame is received by the UE in a specified order.

BACKGROUND

Wireless communications networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and the like. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources.

A wireless communications network may include a number of access points. The access points of a cellular network may include a number of base stations, such as NodeBs (NBs) or evolved NodeBs (eNBs). The access points of a wireless local area network (WLAN) may include a number of WLAN access points, such as WiFi nodes. Each access point may support communication for a number of user equipments (UEs) and may often communicate with multiple UEs at the same time. Similarly, each UE may communicate with a number of access points, and may sometimes communicate with multiple access points and/or access points employing different access technologies. An access point may communicate with a UE via downlink and uplink. The downlink (or forward link) refers to the communication link from the access point to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the access point.

As cellular networks become more congested, operators are beginning to look at ways to increase capacity. One approach may include the use of WLANs to offload some of the traffic and/or signaling of a cellular network. WLANs (or WiFi networks) are attractive because, unlike cellular networks that operate in a licensed spectrum, WiFi networks generally operate in an unlicensed spectrum. However, the use of unlicensed spectrum by both cellular and WiFi devices may require the use of a contention-based protocol to gain access to the unlicensed spectrum. Thus, devices wanting to communicate over the unlicensed spectrum over multiple data frames may have to account for transmission gaps between data frames (e.g., gaps caused by other devices capturing the unlicensed spectrum and preventing the devices from communicating over the unlicensed spectrum during multiple adjacent data frames).

SUMMARY

The described features generally relate to one or more improved methods, systems, and/or apparatuses for wireless communications. More particularly, the described features relate to the transmission of data frames including data subframes and/or hybrid automatic repeat request (HARQ) feedback, in a wireless communications system in which devices wanting to communicate over an unlicensed spectrum over multiple data frames may have to account for transmission gaps between data frames.

In a first set of illustrative examples, a method for wireless communication is provided. A method for wireless communications may comprise transmitting, over an unlicensed spectrum to a UE, a sequence number corresponding to a data frame and one or more data subframes of the data frame. The method includes receiving, over the unlicensed spectrum from the UE, hybrid automatic repeat request (HARQ) feedback for the one or more data subframes when the sequence number corresponding to the data frame is received by the UE in a specified order.

In some examples, the HARQ feedback may not be transmitted by the UE for the one or more data subframes when the sequence number corresponding to the data frame is received by the UE out of order. The method may further include transmitting, over the unlicensed spectrum to the UE, a sequence number corresponding to a subsequent data frame and one or more data subframes of the subsequent data frame, and receiving, over the unlicensed spectrum from the UE, HARQ feedback for the one or more data subframes of the subsequent data frame when the sequence number for the subsequent data frame is received by the UE in the specified order.

In other examples, the method may comprise receiving a separate HARQ feedback message for each of the one or more data subframes. Receiving a HARQ feedback over the unlicensed spectrum for the one or more data subframes may comprise receiving HARQ feedback for a subset of the one or more data subframes during the data frame, and receiving HARQ feedback for a remaining subset of the one or more data subframes during a next data frame. In yet another example, receiving HARQ feedback over the unlicensed spectrum from the UE may comprise receiving HARQ feedback for each of the one or more data subframes during each one or more corresponding uplink subframes. Each corresponding uplink subframe may occur during the data frame or during a next data frame. The method may further include performing clear channel assessment (CCA) to determine availability of the unlicensed spectrum, and accessing the unlicensed spectrum during the data frame when a determination is made that the unlicensed spectrum is available. In some examples, the method may comprise transmitting a request to send (RTS) signal to request and reserve channel access over an unlicensed spectrum. In such instance, a clear to send (CTS) signal may be received when the unlicensed spectrum is available for transmission. Additionally or alternatively, the method may comprise transmitting a CTS signal when the unlicensed spectrum is available for transmission.

In a second set of illustrative examples, an apparatus for wireless communication is provided. The apparatus may include a processor and memory communicatively coupled with the processor. The processor may be configured to transmit, over an unlicensed spectrum to a UE, a sequence number corresponding to a data frame and one or more data subframes of the data frame. The processor may be further configured to receive, over the unlicensed spectrum from the UE, HARQ feedback for the one or more data subframes when the sequence number corresponding to the data frame is received by the UE in a specified order. In certain examples, the apparatus may implement one or more aspects of the method for wireless communications described above with respect to the first set of illustrative examples.

In a third set of illustrative examples, a method for wireless communications is provided. The method may include transmitting, over an unlicensed spectrum to a UE, a sequence number corresponding to a data frame and HARQ feedback. The method includes receiving, over the unlicensed spectrum from the UE, one or more data subframes in response to the HARQ feedback when the sequence number corresponding to the data frame is received by the UE in a specified order. The one or more data subframes may not be transmitted by the UE when the sequence number corresponding to the data frame is received by the UE out of order.

In some examples, the method may include transmitting, over the unlicensed spectrum to the UE, a sequence number corresponding to a subsequent data frame and subsequent HARQ feedback, and receiving, over the unlicensed spectrum from the UE, one or more additional data subframes in response to the subsequent HARQ feedback when the sequence number for the subsequent data frame is received by the UE in the specified order. The HARQ feedback may include one or more HARQ feedback messages, and receiving, over the unlicensed spectrum from the UE, one or more data subframes may include receiving a separate data subframe for each of the one or more HARQ feedback messages. Receiving, over the unlicensed spectrum from the UE, one or more data subframes may include receiving each of the one or more data subframes during each of one or more corresponding uplink subframes, wherein each corresponding uplink subframe occurs during the data frame. The HARQ feedback may include one or more uplink grants. The method may include performing CCA to determine availability of the unlicensed spectrum, and accessing the unlicensed spectrum during the data frame when a determination is made that the unlicensed spectrum is available.

In a fourth set of illustrative examples, an apparatus for wireless communications is provided. The apparatus for wireless communications may include a processor and memory communicatively coupled to the processor. The processor may be configured to transmit, over an unlicensed spectrum to a UE, a sequence number corresponding to a data frame and HARQ feedback. The processor may be further configured to receive, over the unlicensed spectrum from the UE, one or more data subframes in response to the HARQ feedback when the sequence number corresponding to the data frame is received by the UE in a specified order. In certain examples, the apparatus may implement one or more aspects of the method for wireless communications described above with respect to the third set of illustrative examples.

DETAILED DESCRIPTION

Methods, systems, and apparatuses are described in which unlicensed spectrum is used for LTE communications. Generally, operators have looked at WiFi as the primary mechanism to use unlicensed spectrum to relieve ever increasing levels of congestion in cellular networks. However, a new carrier type (NCT) based on LTE in an unlicensed spectrum may be compatible with carrier-grade WiFi, which makes LTE/LTE-A communications in an unlicensed or shared spectrum an alternative to WiFi solutions directed at relieving network congestion. LTE/LTE-A communications in an unlicensed or shared spectrum may leverage many LTE concepts and may introduce some modifications to physical layer (PHY) and media access control (MAC) aspects of the network or network devices to provide efficient operation in the unlicensed spectrum and to meet regulatory requirements. The unlicensed spectrum may range from 600 Megahertz (MHz) to 6 Gigahertz (GHz), for example. In some cases, LTE/LTE-A in an unlicensed or shared spectrum may perform significantly better than WiFi. For example, when an all LTE/LTE-A in an unlicensed or shared deployment (for single or multiple operators) is compared to an all WiFi deployment, or when there are dense small cell deployments, LTE/LTE-A in an unlicensed or shared may perform significantly better than WiFi. LTE/LTE-A in an unlicensed or shared may also perform better than WiFi in other cases such as when LTE/LTE-A in an unlicensed or shared is mixed with WiFi (for single or multiple operators).

The described features relate to the transmission of data frames including data subframes and/or HARQ feedback. In a wireless communications system in which devices want to communicate over an unlicensed spectrum over multiple data frames, the devices may have to account for transmission gaps between data frames. To account for these transmission gaps, the data frames of a transmission over the unlicensed spectrum may be assigned sequence numbers. The data frames may then be transmitted, along with the sequence numbers, in accord with a specified order of the sequence numbers. In some cases, consecutive sequence numbers may be assigned to data frames separated by transmission gaps. When a device receives the data frames in the specified order, the device may transmit HARQ feedback and/or data subframes in response. When a device does not receive a data frame in the specified order (e.g., the device receives a third data frame in a transmission before receiving the second data frame in the transmission), the device may not transmit any data subframes or HARQ feedback, thereby signaling that it received the data frame out of order.

Referring first toFIG. 1, a diagram illustrates an example of a wireless communications system100. The system100includes a plurality of access points (e.g., base stations, eNBs, or WLAN access points)105, a number of user equipments (UEs)115, and a core network130. Some of the access points105may communicate with the UEs115under the control of a base station controller (not shown), which may be part of the core network130or certain access points105(e.g., base stations or eNBs) in various embodiments. Some of the access points105may communicate control information and/or user data with the core network130through backhaul132. In one example, some of the access points105may communicate, either directly or indirectly, with each other over backhaul links134, which may be wired or wireless communication links. The system100may support operation on multiple carriers (waveform signals of different frequencies). Multi-carrier transmitters can transmit modulated signals simultaneously on the multiple carriers. For example, each communications link125may be a multi-carrier signal modulated according to various radio technologies. Each modulated signal may be sent on a different carrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, data, etc.

The access points105may wirelessly communicate with the UEs115via one or more access point antennas. Each of the access points105may provide communication coverage for a respective coverage area110. In some examples, an access point105may be referred to as a base station, a base transceiver station (BTS), a radio base station, a radio transceiver, a basic service set (BSS), an extended service set (ESS), a NodeB, an evolved NodeB (eNB), a Home NodeB, a Home eNodeB, a WLAN access point, a WiFi node or some other suitable terminology. The coverage area110for an access point may be divided into sectors making up only a portion of the coverage area (not shown). The system100may include access points105of different types (e.g., macro, micro, and/or pico base stations). The access points105may also utilize different radio technologies, such as cellular and/or WLAN radio access technologies. The access points105may be associated with the same or different access networks or operator deployments. The coverage areas of different access points105, including the coverage areas of the same or different types of access points105, utilizing the same or different radio technologies, and/or belonging to the same or different access networks, may overlap.

In some examples, the system100may include an LTE/LTE-A communications system (or network) that supports one or more modes of operation or deployment scenarios in an unlicensed or shared spectrum. In other embodiments, the system100may support wireless communications using an unlicensed spectrum and an access technology different from LTE/LTE-A in a licensed, unlicensed or shared spectrum. In LTE/LTE-A communications systems, the term evolved NodeB or eNB may be generally used to describe of the access points105. The system100may be a Heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB105may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cell. Small cells such as pico cells, femto cells, and/or other types of cells may include low power nodes or LPNs. A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A pico cell would generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A femto cell would also generally cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, may also provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home, and the like). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a pico cell may be referred to as a pico eNB. And, an eNB for a femto cell may be referred to as a femto eNB or a home eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells.

The core network130may communicate with the eNBs105via a backhaul132(e.g., S1, etc.). The eNBs105may also communicate with one another, e.g., directly or indirectly via backhaul links134(e.g., X2, etc.) and/or via backhaul132(e.g., through core network130). The wireless communications system100may support synchronous or asynchronous operation. For synchronous operation, the eNBs may have similar frame and/or gating timing, and transmissions from different eNBs may be approximately aligned in time. For asynchronous operation, the eNBs may have different frame and/or gating timing, and transmissions from different eNBs may not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

The UEs115may be dispersed throughout the wireless communications system100, and each UE115may be stationary or mobile. A UE115may also be referred to by those skilled in the art as a mobile device, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE115may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wearable item such as a watch or glasses, a wireless local loop (WLL) station, or the like. A UE115may be able to communicate with macro eNBs, pico eNBs, femto eNBs, relays, and the like. A UE115may also be able to communicate over different access networks, such as cellular or other WWAN access networks, or WLAN access networks.

The communications links125shown in system100may include uplinks for carrying uplink (UL) transmissions (e.g., from a UE115to an eNB105) and/or downlinks for carrying downlink (DL) transmissions (e.g., from an eNB105to a UE115). The UL transmissions may also be called reverse link transmissions, while the DL transmissions may also be called forward link transmissions. The downlink transmissions may be made using a licensed spectrum (e.g., LTE), LTE/LTE-A in an unlicensed or shared spectrum, or both. Similarly, the uplink transmissions may be made using a licensed spectrum (e.g., LTE), LTE/LTE-A in an unlicensed or shared spectrum, or both.

In some examples of the system100, various deployment scenarios for LTE/LTE-A in an unlicensed or shared spectrum may be supported including a supplemental downlink mode in which LTE downlink capacity in a licensed spectrum may be offloaded to an unlicensed spectrum, a carrier aggregation mode in which both LTE downlink and uplink capacity may be offloaded from a licensed spectrum to an unlicensed spectrum, and a standalone mode in which LTE downlink and uplink communications between a base station (e.g., eNB) and a UE may take place in an unlicensed spectrum. Base stations or eNBs105as well as UEs115may support one or more of these or similar modes of operation. OFDMA communications signals may be used in the communications links125for LTE downlink transmissions in an unlicensed and/or a licensed spectrum, while SC-FDMA communications signals may be used in the communications links125for LTE uplink transmissions in an unlicensed and/or a licensed spectrum. Additional details regarding the implementation of LTE/LTE-A in an unlicensed or shared spectrum deployment scenarios or modes of operation in a system such as the system100, as well as other features and functions related to the operation of LTE/LTE-A in an unlicensed or shared spectrum, are provided below with reference toFIGS. 2-16.

Turning next toFIG. 2A, a wireless communications system200illustrates examples of a supplemental downlink mode and of a carrier aggregation mode for an LTE network that supports LTE/LTE-A in an unlicensed or shared spectrum. The system200may be an example of portions of the system100ofFIG. 1. Moreover, the base station205may be an example of the base stations105ofFIG. 1, while the UEs215,215-a, and215-bmay be examples of the UEs115ofFIG. 1.

In the example of a supplemental downlink mode in the system200, the base station205may transmit OFDMA communications signals to a UE215using a downlink220. The downlink220is associated with a frequency F1in an unlicensed spectrum. The base station205may transmit OFDMA communications signals to the same UE215using a bidirectional link225and may receive SC-FDMA communications signals from that UE215using the bidirectional link225. The bidirectional link225is associated with a frequency F4in a licensed spectrum. The downlink220in the unlicensed spectrum and the bidirectional link225in the licensed spectrum may operate concurrently. The downlink220may provide a downlink capacity offload for the base station205. In some examples, the downlink220may be used for unicast services (e.g., addressed to one UE) services or for multicast services (e.g., addressed to several UEs). This scenario may occur with any service provider (e.g., traditional mobile network operator or MNO) that uses a licensed spectrum and needs to relieve some of the traffic and/or signaling congestion.

In one example of a carrier aggregation mode in the system200, the base station205may transmit OFDMA communications signals to a UE215-ausing a bidirectional link230and may receive SC-FDMA communications signals from the same UE215-ausing the bidirectional link230. The bidirectional link230is associated with the frequency F1in the unlicensed spectrum. The base station205may also transmit OFDMA communications signals to the same UE215-ausing a bidirectional link235and may receive SC-FDMA communications signals from the same UE215-ausing the bidirectional link235. The bidirectional link235is associated with a frequency F2in a licensed spectrum. The bidirectional link230may provide a downlink and uplink capacity offload for the base station205. Like the supplemental downlink described above, this scenario may occur with any service provider (e.g., MNO) that uses a licensed spectrum and needs to relieve some of the traffic and/or signaling congestion.

In another example of a carrier aggregation mode in the system200, the base station205may transmit OFDMA communications signals to a UE215-busing a bidirectional link240and may receive SC-FDMA communications signals from the same UE215-busing the bidirectional link240. The bidirectional link240is associated with a frequency F3in an unlicensed spectrum. The base station205may also transmit OFDMA communications signals to the same UE215-busing a bidirectional link245and may receive SC-FDMA communications signals from the same UE215-busing the bidirectional link245. The bidirectional link245is associated with the frequency F2in the licensed spectrum. The bidirectional link240may provide a downlink and uplink capacity offload for the base station205. This example and those provided above are presented for illustrative purposes and there may be other similar modes of operation or deployment scenarios that combine LTE and LTE/LTE-A in an unlicensed or shared spectrum for capacity offload.

As described above, the typical service provider that may benefit from the capacity offload offered by using LTE/LTE-A in an unlicensed or shared spectrum is a traditional MNO with LTE spectrum. For these service providers, an operational configuration may include a bootstrapped mode (e.g., supplemental downlink, carrier aggregation) that uses the LTE primary component carrier (PCC) on the licensed spectrum and the LTE/LTE-A in an unlicensed or shared spectrum secondary component carrier (SCC) on the unlicensed spectrum.

In the carrier aggregation mode, data and control may generally be communicated in LTE (e.g., bidirectional links225,235, and245) while data may generally be communicated in LTE/LTE-A in an unlicensed or shared spectrum (e.g., bidirectional links230and240). The carrier aggregation mechanisms supported when using LTE/LTE-A in an unlicensed or shared spectrum may fall under a hybrid frequency division duplexing-time division duplexing (FDD-TDD) carrier aggregation or a TDD-TDD carrier aggregation with different symmetry across component carriers.

FIG. 2Bshows a wireless communications system250that illustrates an example of a standalone mode for LTE/LTE-A in an unlicensed or shared spectrum. The system250may be an example of portions of the system100ofFIG. 1. Moreover, the base station205may be an example of the base stations105and/or205described with reference toFIGS. 1 and/or 2A, while the UE215-cmay be an example of the UEs115and/or215ofFIGS. 1 and/or 2A.

In the example of a standalone mode in system250, the base station205may transmit OFDMA communications signals to the UE215-cusing a bidirectional link255and may receive SC-FDMA communications signals from the UE215-cusing the bidirectional link255. The bidirectional link255may be associated with the frequency F3in an unlicensed spectrum described above with reference toFIG. 2A. The standalone mode may be used in non-traditional wireless access scenarios, such as in-stadium access (e.g., unicast, multicast). The typical service provider for this mode of operation may be a stadium owner, cable company, event host, hotel, enterprise, or large corporation that does not have licensed spectrum.

In some examples, a transmitting device such as an eNB105and/or205described with reference toFIGS. 1, 2A, and/or2B, or a UE115and/or215described with reference toFIGS. 1, 2A, and/or2B, may use a gating interval to gain access to a channel of the unlicensed spectrum. The gating interval may define the application of a contention-based protocol, such as a Listen Before Talk (LBT) protocol based on the LBT protocol specified in ETSI (EN 301 893). When using a gating interval that defines the application of an LBT protocol, the gating interval may indicate when a transmitting device needs to perform a Clear Channel Assessment (CCA). The outcome of the CCA indicates to the transmitting device whether a channel of the unlicensed spectrum is available or in use. When the CCA indicates that the channel is available (e.g., “clear” for use), the gating interval may allow the transmitting device to use the channel—typically for a predefined transmission period. When the CCA indicates that the channel is not available (e.g., in use or reserved), the gating interval may prevent the transmitting device from using the channel during the transmission period.

In some cases, it may be useful for a transmitting device to generate a gating interval on a periodic basis and synchronize at least one boundary of the gating interval with at least one boundary of a periodic frame structure. For example, it may be useful to generate a periodic gating interval for a cellular downlink in an unlicensed spectrum, and to synchronize at least one boundary of the periodic gating interval with at least one boundary of a periodic frame structure (e.g., LTE radio frame) associated with the cellular downlink. Examples of such synchronization are shown inFIG. 3.

FIG. 3illustrates examples300of an unlicensed frame/interval305,315, and/or325for a cellular downlink in an unlicensed spectrum. The unlicensed frame/interval305,315, and/or325may be used as a periodic gating interval by an eNB that supports transmissions over an unlicensed spectrum. Examples of such an eNB may be the access points105and/or eNBs205described with reference toFIGS. 1, 2A, and/or2B. The unlicensed frame/interval305,315, and/or325may be used with the system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

By way of example, the duration of the unlicensed frame/interval305is shown to be equal to (or approximately equal to) an LTE radio frame310of a periodic frame structure associated with a cellular downlink. In some examples, “approximately equal” means the duration of the unlicensed frame/interval305is within a cyclic prefix (CP) duration of the duration of the periodic frame structure.

At least one boundary of the unlicensed frame/interval305may be synchronized with at least one boundary of the periodic frame structure that includes the LTE radio frames N−1 to N+1. In some cases, the unlicensed frame/interval305may have boundaries that are aligned with the frame boundaries of the periodic frame structure. In other cases, the unlicensed frame/interval305may have boundaries that are synchronized with, but offset from, the frame boundaries of the periodic frame structure. For example, the boundaries of the unlicensed frame/interval305may be aligned with subframe boundaries of the periodic frame structure, or with subframe midpoint boundaries (e.g., the midpoints of particular subframes) of the periodic frame structure.

In some cases, the periodic frame structure may include LTE radio frames N−1 to N+1. Each LTE radio frame310may have a duration of ten milliseconds, for example, and the unlicensed frame/interval305may also have a duration of ten milliseconds. In these cases, the boundaries of the unlicensed frame/interval305may be synchronized with the boundaries (e.g., frame boundaries, subframe boundaries, or subframe midpoint boundaries) of one of the LTE radio frames (e.g., the LTE radio frame (N)).

By way of example, the duration of the unlicensed frames/intervals315and325are shown to be sub-multiples of (or approximate sub-multiples of) the duration of the periodic frame structure associated with the cellular downlink. In some examples, an “approximate sub-multiple of” means the duration of the unlicensed frame/interval315,325is within a cyclic prefix (CP) duration of the duration of a sub-multiple of (e.g., half or one-tenth) the periodic frame structure. For example, the unlicensed frame/interval315may have a duration of five milliseconds and the unlicensed frame/interval325may have a duration of 1 or 2 milliseconds.

FIG. 4illustrates an example use400of unlicensed frames/intervals405,405-a. In some examples, the unlicensed frames/intervals405,405-amay be examples of frames used by one or more of the eNBs105and/or205described with reference toFIGS. 1, 2A, and/or2B. The unlicensed frame/interval405may include a CCA slot period410, a Request To Send (RTS) signal period415, a Clear To Send (CTS) signal period420, a sequence number (or sequence number period)425, and/or a number of data subframes430,431,432,433. In some cases, the unlicensed frame/interval405may have a duration of five or ten milliseconds.

The CCA slot period410may include one or more CCA slots. In some cases, one of the CCA slots may be pseudo-randomly selected by an eNB for performing CCA to determine availability of an unlicensed spectrum. The CCA slots may be pseudo-randomly selected such that some or all of the eNBs of a same operator deployment perform CCA in a common one of the CCA slots, and the eNBs of different operator deployments perform CCA in different ones of the CCA slots. In successive instances of the unlicensed frame/interval405, the pseudo-random selection of CCA slots may result in different operator deployments selecting the first of the CCA slots. In this manner, each of a number of operator deployments may be given the first chance to perform CCA (e.g., a first operator deployment may select the first CCA slot in one unlicensed frame/interval, a second operator deployment may select the first CCA slot in a subsequent frame/interval, etc.). In some instances, the CCA slots may each have a duration of approximately 20 microseconds.

When an eNB performs CCA to determine availability of an unlicensed spectrum and determines that the unlicensed spectrum is available, the eNB may reserve a transmission period for transmitting one or more data subframes430,431,432,433. In some cases, multiple coordinated eNBs (e.g., two or more coordinated eNBs) may reserve the transmission period and transmit data. The simultaneous use of the transmission period by more than one eNB may be possible as a result of orthogonal transmissions, multiplexed transmissions, and/or the use of other time and/or frequency sharing mechanisms employed by a set of coordinated eNBs.

Optionally, the RTS and CTS signal periods415,420may be used to request and reserve channel access over an unlicensed spectrum (e.g., instead of or along with using CCA).

Upon transmitting each of one or more data subframes430,431,432,433to a UE, the UE may respond to the eNB with hybrid automatic repeat request (HARQ) feedback445,446,447,448. By way of example, the HARQ feedback445,446,447,448may indicate to the eNB whether the one or more data subframes430,431,432,433were successfully received and decoded by the UE (e.g., via an acknowledgement (ACK) or non-acknowledgement (NACK)). In some cases, the HARQ feedback may be transmitted as a separate HARQ feedback message445,446,447,448for each of the one or more data subframes430,431,432,433. Each HARQ feedback message (e.g., message445) may be transmitted after a decoding delay440following the receipt of a corresponding data subframe430by the UE.

In accord with various examples, the UE may transmit the HARQ feedback messages445,446,447,448after determining that the sequence number (SEQ #1) corresponding to the data frame405is received in a specified order (e.g., the data frame405is received as the first data frame in a transmission). Subsequently, the eNB may transmit a subsequent data frame405-aincluding a CCA slot period410-a, an RTS signal period415-a, a CTS signal period420-a, a sequence number (or sequence number period)425-a, and/or a number of data subframes430-a,431-a,432-a,433-a. When the UE receives the sequence number (SEQ #2) of the subsequent data frame405-a, the UE may determine that the subsequent data frame405-ais received in the specified order (e.g., the subsequent data frame405-ais received as the second data frame in a transmission) and proceed to transmit HARQ feedback messages445-a,446-a,447-a,448-afor the data subframes430-a,431-a,432-a,433-afollowing respective decoding delays (e.g., delay440-a).

FIG. 5illustrates an example use500of unlicensed frame/intervals505,505-a. In some examples, the unlicensed frames/intervals505,505-amay be examples of frames used by one or more of the eNBs105and/or205described with reference toFIGS. 1, 2A, and/or2B. The unlicensed frame/interval505may include a CCA slot period510, an RTS signal period515, a CTS signal period520, a sequence number (or sequence number period)525, and/or a number of data subframes530,531,532,533. In some cases, the unlicensed frame/interval505may have a duration of five or ten milliseconds.

The CCA slot period510may include one or more CCA slots. In some cases, one of the CCA slots may be pseudo-randomly selected by an eNB for performing CCA to determine availability of an unlicensed spectrum. The CCA slots may be pseudo-randomly selected such that some or all of the eNBs of a same operator deployment perform CCA in a common one of the CCA slots, and the eNBs of different operator deployments perform CCA in different ones of the CCA slots. In successive instances of the unlicensed frame/interval405, the pseudo-random selection of CCA slots may result in different operator deployments selecting the first of the CCA slots. In this manner, each of a number of operator deployments may be given the first chance to perform CCA (e.g., a first operator deployment may select the first CCA slot in one unlicensed frame/interval, a second operator deployment may select the first CCA slot in a subsequent frame/interval, etc.). In some instances, the CCA slots may each have a duration of approximately 20 microseconds.

When an eNB performs CCA to determine availability of an unlicensed spectrum and determines that the unlicensed spectrum is available, the eNB may reserve a transmission period for transmitting one or more data subframes530,531,532,533. In some cases, multiple coordinated eNBs (e.g., two or more coordinated eNBs) may reserve the transmission period and transmit data. The simultaneous use of the transmission period by more than one eNB may be possible as a result of orthogonal transmissions, multiplexed transmissions, and/or the use of other time and/or frequency sharing mechanisms employed by a set of coordinated eNBs.

Optionally, the RTS and CTS signal periods515,520may be used to request and reserve channel access over an unlicensed spectrum (e.g., instead of or along with using CCA).

Upon transmitting each of one or more data subframes530,531,532,533to a UE, the UE may respond to the eNB with hybrid automatic repeat request (HARQ) feedback545,546,547,548. By way of example, the HARQ feedback545,546,547,548may indicate to the eNB whether the one or more data subframes530,531,532,533were successfully received and decoded by the UE (e.g., via an acknowledgement (ACK) or non-acknowledgement (NACK)). In some cases, the HARQ feedback may be transmitted as a separate HARQ feedback message545,546,547,548for each of the one or more data subframes530,531,532,533. Each HARQ feedback message (e.g., message545) may be transmitted after a decoding delay540following the receipt of a corresponding data subframe530by the UE.

In accord with various examples, the UE may transmit the HARQ feedback messages545,546,547,548after determining that that sequence number (SEQ #1) corresponding to the data frame505is received in a specified order (e.g., the data frame505is received as the first data frame in a transmission). Subsequently, the eNB may transmit a subsequent data frame505-aincluding a CCA slot period510-a, an RTS signal period515-a, a CTS signal period520-a, a sequence number (or sequence number period)525-a, and/or a number of data subframes530-a,531-a,532-a,533-a. When the UE receives the sequence number (SEQ #3) of the subsequent data frame505-a, the UE may determine that the subsequent data frame505-ais received out of order (e.g., the subsequent data frame505-ais the second data frame received by the UE, but its sequence number (SEQ #3) indicates that it is the third data frame in a transmission) and not transmit HARQ feedback for the one or more data subframes530-a,531-a,532-a,533-a. Because the eNB does not receive any HARQ feedback, it may retransmit the data frame (or the contents of the data frame) corresponding to sequence number SEQ #2, as well as the data frame505-a(or the contents of the data frame505-a).

FIG. 6illustrates an example use600of unlicensed frames/intervals605,605-a. In some examples, the unlicensed frames/intervals605,605-amay be examples of frames used by one or more of the eNBs105and/or205described with reference toFIGS. 1, 2A, and/or2B. The unlicensed frame/interval605may include a CCA slot period610, an RTS signal period615, a CTS signal period620, a sequence number (or sequence number period)625, and/or a number of HARQ feedback messages630,631,632,633including uplink grants. In some cases, the unlicensed frame/interval605may have a duration of five or ten milliseconds.

The CCA slot period610may include one or more CCA slots. In some cases, one of the CCA slots may be pseudo-randomly selected by an eNB for performing CCA to determine availability of an unlicensed spectrum. The CCA slots may be pseudo-randomly selected such that some or all of the eNBs of a same operator deployment perform CCA in a common one of the CCA slots, and the eNBs of different operator deployments perform CCA in different ones of the CCA slots. In successive instances of the unlicensed frame/interval605, the pseudo-random selection of CCA slots may result in different operator deployments selecting the first of the CCA slots. In this manner, each of a number of operator deployments may be given the first chance to perform CCA (e.g., a first operator deployment may select the first CCA slot in one unlicensed frame/interval, a second operator deployment may select the first CCA slot in a subsequent frame/interval, etc.). In some instances, the CCA slots may each have a duration of approximately 20 microseconds.

When an eNB performs CCA to determine availability of an unlicensed spectrum and determines that the unlicensed spectrum is available, the eNB may reserve a transmission period for transmitting one or more HARQ feedback messages630,631,632,633. In some cases, multiple coordinated eNBs (e.g., two or more coordinated eNBs) may reserve the transmission period and transmit data. The simultaneous use of the transmission period by more than one eNB may be possible as a result of orthogonal transmissions, multiplexed transmissions, and/or the use of other time and/or frequency sharing mechanisms employed by a set of coordinated eNBs.

Optionally, the RTS and CTS signal periods615,620may be used to request and reserve channel access over an unlicensed spectrum (e.g., instead of or along with using CCA).

Upon transmitting each of one or more HARQ feedback messages630,631,632,633to a UE, the UE may respond to the eNB by transmitting one or more data subframes645,646,647,648. Each data subframe (e.g., message645) may be transmitted after a decoding delay640following the receipt of a corresponding uplink grant (e.g., the uplink grant included with HARQ feedback630).

In accord with various examples, the UE may transmit the data subframes645,646,647,648after determining that that sequence number (SEQ #1) corresponding to the data frame605is received in a specified order (e.g., the data frame605is received as the first data frame in a transmission). Subsequently, the eNB may transmit a subsequent data frame605-aincluding a CCA slot period610-a, an RTS signal period615-a, a CTS signal period620-a, a sequence number (or sequence number period)625-a, and/or a number of HARQ feedback messages630-a,631-a,632-a,633-a. When the UE receives the sequence number (SEQ #2) of the subsequent data frame605-a, the UE may determine that the subsequent data frame605-ais received in the specified order (e.g., the subsequent data frame605-ais received as the second data frame in a transmission) and proceed to transmit one or more data subframes645-a,646-a,647-a,648-ain response to the HARQ feedback messages630-a,631-a,632-a,633-afollowing respective decoding delays (e.g., delay640-a).

FIG. 7illustrates an example use700of unlicensed frames/intervals705,705-a. In some examples, the unlicensed frames/intervals705,705-amay be examples of frames used by one or more of the eNBs105and/or205described with reference toFIGS. 1, 2A, and/or2B. The unlicensed frame/interval705may include a CCA slot period710, an RTS signal period715, a CTS signal period720, a sequence number (or sequence number period)725, and/or a number of HARQ feedback messages730,731,732,733including uplink grants. In some cases, the unlicensed frame/interval705may have a duration of five or ten milliseconds.

The CCA slot period710may include one or more CCA slots. In some cases, one of the CCA slots may be pseudo-randomly selected by an eNB for performing CCA to determine availability of an unlicensed spectrum. The CCA slots may be pseudo-randomly selected such that some or all of the eNBs of a same operator deployment perform CCA in a common one of the CCA slots, and the eNBs of different operator deployments perform CCA in different ones of the CCA slots. In successive instances of the unlicensed frame/interval705, the pseudo-random selection of CCA slots may result in different operator deployments selecting the first of the CCA slots. In this manner, each of a number of operator deployments may be given the first chance to perform CCA (e.g., a first operator deployment may select the first CCA slot in one unlicensed frame/interval, a second operator deployment may select the first CCA slot in a subsequent frame/interval, etc.). In some instances, the CCA slots may each have a duration of approximately 20 microseconds.

When an eNB performs CCA to determine availability of an unlicensed spectrum and determines that the unlicensed spectrum is available, the eNB may reserve a transmission period for transmitting one or more HARQ feedback messages730,731,732,733. In some cases, multiple coordinated eNBs (e.g., two or more coordinated eNBs) may reserve the transmission period and transmit data. The simultaneous use of the transmission period by more than one eNB may be possible as a result of orthogonal transmissions, multiplexed transmissions, and/or the use of other time and/or frequency sharing mechanisms employed by a set of coordinated eNBs.

Optionally, the RTS and CTS signal periods715,720may be used to request and reserve channel access over an unlicensed spectrum (e.g., instead of or along with using CCA). For example, the eNB may transmit a request to send (RTS) signal to reserve channel access over the unlicensed spectrum, and receive, in response to the RTS signal, a CTS signal identifying when the unlicensed spectrum is available for transmission. Additionally or alternatively, the eNB may transmit a CTS signal to itself to denote when the unlicensed spectrum is available for transmission.

Upon transmitting each of one or more HARQ feedback messages730,731,732,733to a UE, the UE may respond to the eNB by transmitting one or more data subframes745,746,747,748. Each data subframe (e.g., data subframe745) may be transmitted after a decoding delay740following the receipt of a corresponding uplink grant (e.g., the uplink grant included with HARQ feedback730).

In accord with various examples, the UE may transmit the data subframes745,746,747,748after determining that that sequence number (SEQ #1) corresponding to the data frame705is received in a specified order (e.g., the data frame705is received as the first data frame in a transmission). Subsequently, the eNB may transmit a subsequent data frame705-aincluding a CCA slot period710-a, an RTS signal period715-a, a CTS signal period720-a, a sequence number (or sequence number period)725-a, and/or a number of HARQ feedback messages730-a,731-a,732-a,733-a. When the UE receives the sequence number (SEQ #3) of the subsequent data frame705-a, the UE may determine that the subsequent data frame705-ais received out of order (e.g., the subsequent data frame505-ais the second data frame received by the UE, but its sequence number (SEQ #3) indicates that it is the third data frame in a transmission) and not transmit any data subframes in response to the uplink grants of the HARQ feedback messages730-a,731-a,732-a,733-a. Because the eNB does not receive any data subframes, it may retransmit the data frame (or the contents of the data frame) corresponding to sequence number SEQ #2, as well as the data frame705-aor the contents of the data frame705-a.

Referring now toFIG. 8A, a block diagram800illustrates a device805for use in wireless communications in accordance with various examples. In some examples, the device805may be an example of one or more aspects of the eNBs105and/or205described with reference toFIGS. 1, 2A, and/or2B. The device805may also be a processor. The device805may include a receiver module810, an eNB LTE HARQ module820, and/or a transmitter module830. Each of these components may be in communication with each other.

In some examples, the receiver module810may be or include a radio frequency (RF) receiver, such as an RF receiver operable to receive transmissions in a licensed spectrum (e.g., an LTE spectrum) and/or an unlicensed spectrum. The receiver module810may be used to receive various types of data and/or control signals (i.e., transmissions) over one or more communication links of a wireless communications system including the licensed and unlicensed spectrums, such as one or more communication links of the wireless communications system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

In some examples, the transmitter module830may be or include an RF transmitter, such as an RF transmitter operable to transmit in the licensed spectrum and/or the unlicensed spectrum. The transmitter module830may be used to transmit various types of data and/or control signals (i.e., transmissions) over one or more communication links of a wireless communications system, such as one or more communication links of the wireless communications system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

In some examples or modes of operation (e.g., in a downlink mode of operation between the device805and a UE), the eNB LTE HARQ module820may transmit a sequence number corresponding to a data frame and one or more data subframes of the data frame over an unlicensed spectrum to a UE. An example transmission of a sequence number425corresponding to a data frame405and one or more data subframes430,431,432,433is described with reference toFIG. 4. When the sequence number corresponding to the data frame is received by the UE in a specified order (e.g., numerical order), the eNB LTE HARQ module820may receive, from the UE, HARQ feedback for the one or more data subframes. The HARQ feedback may be received over the unlicensed spectrum. An example transmission of HARQ feedback445,446,447,448is also described with reference toFIG. 4.

In some examples or modes of operation (e.g., in an uplink mode of operation between the device805and a UE), the eNB LTE HARQ module820may transmit a sequence number corresponding to a data frame and HARQ feedback over an unlicensed spectrum to a UE. In some cases, the HARQ feedback may include one or more uplink grants. An example transmission of a sequence number625corresponding to a data frame605and HARQ feedback including uplink grants630,631,632,633is described with reference toFIG. 6. When the sequence number corresponding to the data frame is received by the UE in a specified order (e.g., numerical order), the eNB LTE HARQ module820may receive one or more data subframes, from the UE, in response to the HARQ feedback. The one or more data subframes may be received over the unlicensed spectrum. An example transmission of one or more data subframes645,646,647,648is described with reference toFIG. 6.

Referring now toFIG. 8B, a block diagram850illustrates a device855for use in wireless communications in accordance with various embodiments. In some examples, the device855may be an example of one or more aspects of the eNBs105,205, and/or805described with reference toFIGS. 1, 2A, 2B, and/or8. The device855may also be a processor. The device855may include a receiver module812, an eNB LTE HARQ module860, a CCA module861, and/or a transmitter module832. Each of these components may be in communication with each other.

In some examples, the receiver module812may be or include a radio frequency (RF) receiver, such as an RF receiver operable to receive transmissions in a licensed spectrum (e.g., an LTE spectrum) and/or an unlicensed spectrum. The RF receiver may include separate receivers for the licensed spectrum and the unlicensed spectrum. The separate receivers may in some cases take the form of an LTE system frame number (SFN) module814and an LTE frame sequence number module816. The LTE SFN module814may be used to receive LTE frames according to the use of SFNs and the LTE frame sequence number module816may be used to receive LTE/LTE-A in an unlicensed or shared spectrum frames according to the use of sequence numbers. The LTE SFN module814may be optional (as shown by the dotted lines) when the device855is used for LTE/LTE-A in an unlicensed or shared spectrum operations. The receiver module812, including the modules814and/or816, may be used to receive various types of data and/or control signals (i.e., transmissions) over one or more communication links of a wireless communications system including the licensed and unlicensed spectrums, such as one or more communication links of the wireless communications system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

In some examples, the transmitter module832may be or include an RF transmitter, such as an RF transmitter operable to transmit in the licensed spectrum and/or the unlicensed spectrum. The RF transmitter may include separate transmitters for the licensed spectrum and the unlicensed spectrum. The separate transmitters may in some cases take the form of an LTE SFN module834and an LTE frame sequence number module836. The LTE SFN module834may be used to receive LTE frames according to the use of SFNs and the LTE frame sequence number module836may be used to receive LTE/LTE-A in an unlicensed or shared spectrum frames according to the use of sequence numbers. The LTE SFN module834may be optional (as shown by the dotted lines) when the device855is used for LTE operations. The transmitter module832, including the modules834and836, may be used to transmit various types of data and/or control signals (i.e., transmissions) over one or more communication links of a wireless communications system, such as one or more communication links of the wireless communications system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

In some examples, the CCA module861may perform CCA to determine availability of an unlicensed spectrum. When a determination is made that the unlicensed spectrum is available, the unlicensed spectrum may be accessed during a data frame to which the CCA applies. The CCA module861may perform a respective CCA for each data frame during which it desires to access the unlicensed spectrum.

The eNB LTE HARQ module860may be an example of the eNB LTE HARQ module820described with reference toFIG. 8Aand may include an RTS/CTS module862, a sequence number module863, a DL HARQ module864, and/or a UL HARQ module866. Each of these components may be in communication with each other.

The RTS/CTS module862may be used to reserve channel access over an unlicensed spectrum using RTS/CTS messages and/or self-addressed CTS messages. In some examples, the RTS/CTS module862may be used to request and reserve channel access over an unlicensed spectrum (e.g., instead of or along with using the CCA module961). For example, the RTS/CTS module862may transmit a request to send (RTS) signal to reserve channel access over the unlicensed spectrum. In other examples, the RTS/CTS module862may transmit the RTS signal to determine availability of the unlicensed spectrum or to request channel access over the unlicensed spectrum. In response, the RTS/CTS module862may receive a clear to send (CTS) signal identifying when the unlicensed spectrum is available for transmission. Additionally or alternatively, the RTS/CTS module862may transmit a CTS signal to itself to denote when the unlicensed spectrum is available for transmission.

In some examples, the sequence number module863may generate a sequence number for each of a number of data frames to be transmitted over an unlicensed spectrum. By way of example, the sequence numbers may be generated in numerical order or some other order known or conveyed to the UE (or UEs) with which the device855communicates. When transmitted to a UE in conjunction with the transmission of a data frame, the sequence number corresponding to the data frame enables a UE to determine whether the data frame is received in a specified order or received out of order. When the data frame is received by the UE in the specified order, the UE may respond to transmissions of the device855by transmitting HARQ feedback and/or one or more data subframes to the device855. When the data frame is received by the UE out of order, the UE may not respond to the device855, thereby signaling to the device855that a missing, corrupted, or otherwise not decodable data frame needs to be retransmitted to the UE.

The DL HARQ module864may be used in a downlink mode of operation of the device855(e.g., a downlink mode between the device855and a UE). In such a mode, the DL HARQ module864may transmit a sequence number corresponding to a data frame and one or more data subframes of the data frame over an unlicensed spectrum to a UE. The sequence number may be obtained from the sequence number module863, and the transmission of the sequence number may be made via the unlicensed spectrum module836of the transmitter module832. An example transmission of a sequence number425corresponding to a data frame405and one or more data subframes430,431,432,433, as may be accomplished using the DL HARQ module864, is described with reference toFIG. 4.

When the sequence number corresponding to the data frame is received by the UE in a specified order (e.g., numerical order), a HARQ feedback module865of the DL HARQ module864may receive, from the UE, HARQ feedback for the one or more data subframes. However, when the sequence number corresponding to the data frame is received by the UE out of order, the UE may not transmit HARQ feedback for the one or more data subframes, and the HARQ feedback module865may not receive any HARQ feedback. When received, the HARQ feedback may be received over the unlicensed spectrum via the unlicensed spectrum module816of the receiver module812. An example transmission of HARQ feedback445,446,447,448, as may be made by a UE to the device855, is described with reference toFIG. 4. An example out of order sequence number525-aand non-transmission of HARQ feedback is described with reference toFIG. 5.

In some cases, the HARQ feedback module865may receive HARQ feedback for a subset of the plurality of data subframes in the current data frame, and receive HARQ feedback for a remaining subset of the plurality of data subframes (i.e., data subframes in the current data frame) during a next data frame. That is, when the number of UL subframes available to provide the HARQ feedback in a current frame is smaller than the number of HARQ messages being provided, then the remaining HARQ messages (those not yet provided) may be provided in UL subframes in a subsequent frame.

In some cases, a separate HARQ feedback message may be received for each of a plurality of data subframes in a current data frame. The HARQ feedback messages may be received in the current data frame and/or a next data frame.

In some examples, HARQ feedback may be received for each of the one or more data subframes in a data frame during each of a plurality of corresponding uplink subframes. Some or all of the uplink subframes may occur during the current data frame and/or during a next data frame.

The UL HARQ module866may be used in an uplink mode of operation of the device855(e.g., an uplink mode between the device855and a UE). In such a mode, the UL HARQ module866may transmit a sequence number corresponding to a data frame and HARQ feedback over an unlicensed spectrum to a UE. The sequence number may be obtained from the sequence number module863, and the transmission of the sequence number may be made via the unlicensed spectrum module836of the transmitter module832. In some cases, the HARQ feedback may include one or more uplink grants. An example transmission of a sequence number625corresponding to a data frame605and HARQ feedback including uplink grants630,631,632,633is described with reference toFIG. 6.

When the sequence number corresponding to the data frame is received by the UE in a specified order (e.g., numerical order), a data subframe receiver module867of the UL HARQ module866may receive one or more data subframes, from the UE, in response to the HARQ feedback. However, when the sequence number corresponding to the data frame is received by the UE out of order, the UE may not transmit the one or more data subframes, and the data subframe receiver module867may not receive any data subframes. When received, the one or more data subframes may be received over the unlicensed spectrum via the unlicensed spectrum module816of the receiver module812. An example transmission of one or more data subframes645,646,647,648is described with reference toFIG. 6. An example out of order sequence number725-aand non-transmission of one or more data subframes is described with reference toFIG. 7.

In some cases, the HARQ feedback may include one or more HARQ feedback messages, and a separate data subframe may be received for each of the one or more HARQ feedback messages. Each HARQ feedback message may include a separate uplink grant.

In some cases, each of one or more data subframes may be received by the data subframe receiver module867during each of one or more corresponding uplink subframes, and each corresponding uplink subframe may occur during a current data frame.

Referring now toFIG. 9A, a block diagram900illustrates a device915for use in wireless communications in accordance with various examples. In some examples, the device915may be an example of one or more aspects of the UEs115and/or215described with reference toFIGS. 1, 2A, and/or2B. The device915may also be a processor. The device915may include a receiver module910, a UE LTE HARQ module920, and/or a transmitter module930. Each of these components may be in communication with each other.

In some examples, the receiver module910may be or include a radio frequency (RF) receiver, such as an RF receiver operable to receive transmissions in a licensed spectrum (e.g., an LTE spectrum) and/or an unlicensed spectrum. The receiver module910may be used to receive various types of data and/or control signals (i.e., transmissions) over one or more communication links of a wireless communications system including the licensed and unlicensed spectrums, such as one or more communication links of the wireless communications system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

In some examples, the transmitter module930may be or include an RF transmitter, such as an RF transmitter operable to transmit in the licensed spectrum and/or the unlicensed spectrum. The transmitter module930may be used to transmit various types of data and/or control signals (i.e., transmissions) over one or more communication links of a wireless communications system, such as one or more communication links of the wireless communications system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

In some examples or modes of operation (e.g., in a downlink mode of operation between an eNB and the device915), the UE LTE HARQ module920may receive a sequence number corresponding to a data frame and one or more data subframes of the data frame over an unlicensed spectrum. An example transmission of a sequence number425corresponding to a data frame405and one or more data subframes430,431,432,433is described with reference toFIG. 4. When the sequence number corresponding to the data frame is received by the device915in a specified order (e.g., numerical order), the UE LTE HARQ module920may transmit HARQ feedback for the one or more data subframes. The HARQ feedback may be transmitted over the unlicensed spectrum. An example transmission of HARQ feedback445,446,447,448is also described with reference toFIG. 4.

In some examples or modes of operation (e.g., in an uplink mode of operation between an eNB and the device915), the UE LTE HARQ module920may receive a sequence number corresponding to a data frame and HARQ feedback over an unlicensed spectrum. In some cases, the HARQ feedback may include one or more uplink grants. An example transmission of a sequence number625corresponding to a data frame605and HARQ feedback including uplink grants630,631,632,633is described with reference toFIG. 6. When the sequence number corresponding to the data frame is received by the device915in a specified order (e.g., numerical order), the UE LTE HARQ module920may transmit one or more data subframes in response to the HARQ feedback. The one or more data subframes may be transmitted over the unlicensed spectrum. An example transmission of one or more data subframes645,646,647,648is described with reference toFIG. 6.

Referring now toFIG. 9B, a block diagram950illustrates a device955for use in wireless communications in accordance with various embodiments. In some examples, the device955may be an example of one or more aspects of the UEs115,215, and/or915described with reference toFIGS. 1, 2A, 2B, and/or9A. The device955may also be a processor. The device955may include a receiver module912, a UE LTE HARQ module960, and/or a transmitter module932. Each of these components may be in communication with each other.

In some examples, the receiver module912may be or include a radio frequency (RF) receiver, such as an RF receiver operable to receive transmissions in a licensed spectrum (e.g., an LTE spectrum) and/or an unlicensed spectrum. The RF receiver may include separate receivers for the licensed spectrum and the unlicensed spectrum. The separate receivers may in some cases take the form of an LTE SFN module914and an LTE frame sequence number module916. The LTE SFN module914may be used to receive LTE frames according to the use of SFNs and the LTE frame sequence number module916may be used to receive LTE frames according to the use of sequence numbers. The LTE SFN module914may be optional (as shown by the dotted lines) when the device955is used for LTE operations. The receiver module912, including the modules914and916, may be used to receive various types of data and/or control signals (i.e., transmissions) over one or more communication links of a wireless communications system including the licensed and unlicensed spectrums, such as one or more communication links of the wireless communications system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

In some examples, the transmitter module932may be or include an RF transmitter, such as an RF transmitter operable to transmit in the licensed spectrum and/or the unlicensed spectrum. The RF transmitter may include separate transmitters for the licensed spectrum and the unlicensed spectrum. The separate transmitters may in some cases take the form of an LTE SFN module934and an LTE frame sequence number module936. The LTE SFN module934may be used to receive LTE frames according to the use of SFNs and the LTE frame sequence number module936may be used to receive LTE/LTE-A in an unlicensed or shared spectrum frames according to the use of sequence numbers. The LTE SFN module934may be optional (as shown by the dotted lines) when the device955is used for LTE/LTE-A in an unlicensed or shared spectrum operations. The transmitter module932, including modules934and936, may be used to transmit various types of data and/or control signals (i.e., transmissions) over one or more communication links of a wireless communications system, such as one or more communication links of the wireless communications system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

The UE LTE HARQ module960may be an example of the UE LTE HARQ module920described with reference toFIG. 9Aand may include a sequence number module961, a DL HARQ module962, and/or a UL HARQ module964. Each of these components may be in communication with each other.

In some examples, the sequence number module961may receive a sequence number for each of a number of data frames received over an unlicensed spectrum. The sequence number(s) may be received over the unlicensed spectrum via the unlicensed spectrum module916of the receiver module912. By way of example, the sequence numbers may be generated in numerical order or some other order known or conveyed to the device955. When received by the device955in conjunction with the reception of a data frame, the sequence number corresponding to the data frame enables the sequence number module961to determine whether the data frame is received by the device955in a specified order or received out of order. When the sequence number module961determines that the data frame is received by the device955in the specified order, the device955may indicate this to the DL HARQ module962and/or the UL HARQ module964. When the sequence number module961determines that the data frame is received by the device955out of order, the device955may indicate this to the DL HARQ module962and/or the UL HARQ module964. An example transmission of a sequence number425corresponding to a data frame405and one or more data subframes430,431,432,433, as may be received by the sequence number module961, is described with reference toFIG. 4. An example transmission of a sequence number625corresponding to a data frame605and HARQ feedback including uplink grants630,631,632,633is described with reference toFIG. 6.

The DL HARQ module962may be used in a downlink mode of operation of the device955(e.g., a downlink mode between an eNB and the device955). In such a mode, the DL HARQ module962may receive, from the sequence number module961, an indication of whether a sequence number is received in a specified order or out of order. The sequence number may correspond to a data frame and one or more data subframes of the data frame.

When the sequence number corresponding to the data frame is received by the device955in a specified order (e.g., numerical order), a HARQ feedback module963of the DL HARQ module962may transmit HARQ feedback for the one or more data subframes. However, when the sequence number corresponding to the data frame is received by the device955out of order, the HARQ feedback module963may not transmit HARQ feedback for the one or more data subframes. When transmitted, the HARQ feedback may be transmitted over the unlicensed spectrum via the unlicensed spectrum module936of the transmitter module932. An example transmission of HARQ feedback445,446,447,448, as may be made by the device955, is described with reference toFIG. 4. An example out of order sequence number525-aand non-transmission of HARQ feedback is described with reference toFIG. 5.

In some cases, the HARQ feedback module963may transmit HARQ feedback for a subset of the plurality of data subframes in the current data frame, and transmit HARQ feedback for a remaining subset of the plurality of data subframes (i.e., data subframes in the current data frame) during a next data frame.

In some cases, a separate HARQ feedback message may be transmitted for each of a plurality of data subframes in a current data frame. The HARQ feedback messages may be transmitted in the current data frame and/or a next data frame.

In some examples, HARQ feedback may be transmitted for each of the one or more data subframes in a data frame during each of a plurality of corresponding uplink subframes. Some or all of the uplink subframes may occur during the current data frame and/or during a next data frame.

The UL HARQ module964may be used in an uplink mode of operation of the device555(e.g., an uplink mode between an eNB and the device955). In such a mode, the UL HARQ module964may receive, from the sequence number module961, an indication of whether a sequence number is received in a specified order or out of order. The sequence number may correspond to a data frame and HARQ feedback of the data frame. In some cases, the HARQ feedback may include one or more uplink grants.

When the sequence number corresponding to the data frame is received by the device955in a specified order (e.g., numerical order), a data subframe transmitter module965of the UL HARQ module964may transmit one or more data subframes in response to the HARQ feedback. However, when the sequence number corresponding to the data frame is received by the device955out of order, the data subframe transmitter module965may not transmit any data subframes. When transmitted, the one or more data subframes may be transmitted over the unlicensed spectrum via the unlicensed spectrum module936of the transmitter module932. An example transmission of one or more data subframes645,646,647,648is described with reference toFIG. 6. An example out of order sequence number725-aand non-transmission of one or more data subframes is described with reference toFIG. 7.

In some cases, the HARQ feedback may include one or more HARQ feedback messages, and a separate data subframe may be transmitted for each of the one or more HARQ feedback messages. Each HARQ feedback message may include a separate uplink grant.

In some cases, each of one or more data subframes may be transmitted during each of one or more corresponding uplink subframes, and each corresponding uplink subframe may occur during a current data frame.

Turning toFIG. 10, a block diagram1000is shown that illustrates an eNB1005configured for LTE/LTE-A in an unlicensed or shared spectrum. In some examples, the eNB1005may be an example of one or more aspects of the eNBs or devices105,205,805, and/or855described with reference toFIGS. 1, 2A, 2B, 8A, and/or8B. The eNB1005may be configured to implement at least some of the eNB LTE features and functions described with reference toFIGS. 1, 2A, 2B, 4, 5, 6, 7, 8A, and/or8B. The eNB1005may include a processor module1010, a memory module1020, at least one transceiver module (represented by transceiver module(s)1055), at least one antenna (represented by antenna(s)1060), and/or an eNB LTE module1070. The eNB1005may also include one or both of a base station communications module1030and a network communications module1040. Each of these components may be in communication with each other, directly or indirectly, over one or more buses1035.

The memory module1020may include random access memory (RAM) and/or read-only memory (ROM). The memory module1020may store computer-readable, computer-executable software (SW) code1025containing instructions that are configured to, when executed, cause the processor module1010to perform various functions described herein for using LTE-based communications in a licensed and/or unlicensed spectrum, including, for example 1) the transmission of a sequence number corresponding to a data frame, over the unlicensed spectrum, to a UE, and 2) the transmission or reception of one or more data subframes and/or HARQ feedback corresponding to the sequence number and/or data frame. Alternatively, the software code1025may not be directly executable by the processor module1010but be configured to cause the eNB1005, e.g., when compiled and executed, to perform various of the functions described herein.

The processor module1010may include an intelligent hardware device, e.g., a central processing unit (CPU), a microcontroller, an ASIC, etc. The processor module1010may process information received through the transceiver module(s)1055, the base station communications module1030, and/or the network communications module1040. The processor module1010may also process information to be sent to the transceiver module(s)1055for transmission through the antenna(s)1060, to the base station communications module1030for transmission to one or more other base stations or eNBs1005-aand1005-b, and/or to the network communications module1040for transmission to a core network1045, which may be an example of aspects of the core network130described with reference toFIG. 1. The processor module1010may handle, alone or in connection with the eNB LTE module1070, various aspects of using LTE-based communications in a licensed and/or unlicensed spectrum, including, for example 1) the transmission of a sequence number corresponding to a data frame, over the unlicensed spectrum, to a UE, and 2) the transmission or reception of one or more data subframes and/or HARQ feedback corresponding to the sequence number and/or data frame.

The transceiver module(s)1055may include a modem configured to modulate the packets and provide the modulated packets to the antenna(s)1060for transmission, and to demodulate packets received from the antenna(s)1060. The transceiver module(s)1055may be implemented as one or more transmitter modules and one or more separate receiver modules. The transceiver module(s)1055may support communications in a licensed spectrum (e.g., an LTE spectrum) and/or an unlicensed spectrum. The transceiver module(s)1055may be configured to communicate bi-directionally, via the antenna(s)1060, with one or more of the UEs or devices115,215,915, and/or955described with reference toFIGS. 1, 2A, 2B, 9A, and/or9B, for example. The eNB1005may typically include multiple antennas1060(e.g., an antenna array). The eNB1005may communicate with the core network1045through the network communications module1040. The eNB1005may communicate with other base stations or eNBs, such as the eNBs1005-aand1005-b, using the base station communications module1030.

According to the architecture ofFIG. 10, the eNB1005may further include a communications management module1050. The communications management module1050may manage communications with other base stations, eNBs, and/or devices. The communications management module1050may be in communication with some or all of the other components of the eNB1005via the bus or buses1035. Alternatively, functionality of the communications management module1050may be implemented as a component of the transceiver module(s)1055, as a computer program product, and/or as one or more controller elements of the processor module1010.

The eNB LTE module1070may be configured to perform and/or control some or all of the features and/or functions described with reference toFIGS. 1, 2A, 2B, 4, 5, 6, 7, 8A, and/or8B related to using LTE-based communications in a licensed and/or unlicensed spectrum. For example, the eNB LTE module1070may be configured to support a supplemental downlink mode, a carrier aggregation mode, and/or a standalone mode. The eNB LTE module1070may include an LTE module1075configured to handle LTE communications, an LTE unlicensed module1080configured to handle LTE/LTE-A in an unlicensed or shared spectrum communications (including the performance of CCA for an unlicensed spectrum), and/or an unlicensed module1085configured to handle communications other than LTE in an unlicensed spectrum. The eNB LTE module1070may also include an LTE HARQ module1090configured to perform, for example, any of the eNB LTE HARQ functions described with reference toFIGS. 1, 4, 5, 6, 7, 8A, and/or8B. The LTE HARQ module1090may be an example of similar modules (e.g., module820and/or module860) described with reference toFIGS. 8A and/or 8B. The eNB LTE module1070, or portions of it, may include a processor, and/or some or all of the functionality of the eNB LTE module1070may be performed by the processor module1010and/or in connection with the processor module1010.

Turning toFIG. 11, a block diagram1100is shown that illustrates a UE1115configured for LTE/LTE-A in an unlicensed or shared spectrum. The UE1115may have various other configurations and may be included or be part of a personal computer (e.g., laptop computer, netbook computer, tablet computer, etc.), a cellular telephone, a PDA, a digital video recorder (DVR), an internet appliance, a gaming console, an e-readers, etc. The UE1115may have an internal power supply (not shown), such as a small battery, to facilitate mobile operation. In some examples, the UE1115may be an example of one or more of the UEs or devices115,215,915, and/or955described with reference toFIGS. 1, 2A, 2B, 9A, and/or9B. The UE1115may be configured to communicate with one or more of the eNBs or devices105,205,805,855, and/or1005described with reference toFIGS. 1, 2A, 2B, 8A, 8B, and/or10.

The UE1115may include a processor module1110, a memory module1120, at least one transceiver module (represented by transceiver module(s)1170), at least one antenna (represented by antenna(s)1180), and/or a UE LTE module1140. Each of these components may be in communication with each other, directly or indirectly, over one or more buses1135.

The memory module1120may include RAM and/or ROM. The memory module1120may store computer-readable, computer-executable software (SW) code1125containing instructions that are configured to, when executed, cause the processor module1110to perform various functions described herein for using LTE-based communications in a licensed and/or unlicensed spectrum, including, for example 1) the reception, over the unlicensed spectrum, of a sequence number corresponding to a data frame, and 2) the transmission or reception of one or more data subframes and/or HARQ feedback corresponding to the sequence number and/or data frame. Alternatively, the software code1125may not be directly executable by the processor module1110but be configured to cause the UE1115(e.g., when compiled and executed) to perform various of the UE functions described herein.

The processor module1110may include an intelligent hardware device, e.g., a CPU, a microcontroller, an ASIC, etc. The processor module1110may process information received through the transceiver module(s)1170and/or information to be sent to the transceiver module(s)1170for transmission through the antenna(s)1180. The processor module1110may handle, alone or in connection with the UE LTE module1140, various aspects of using LTE-based communications in a licensed and/or unlicensed spectrum, including, for example 1) the reception, over the unlicensed spectrum, of a sequence number corresponding to a data frame, and 2) the transmission or reception of one or more data subframes and/or HARQ feedback corresponding to the sequence number and/or data frame.

The transceiver module(s)1170may be configured to communicate bi-directionally with eNBs. The transceiver module(s)1170may be implemented as one or more transmitter modules and one or more separate receiver modules. The transceiver module(s)1170may support communications in at least one licensed spectrum (e.g., an LTE spectrum) and in at least one unlicensed spectrum. The transceiver module(s)1170may include a modem configured to modulate the packets and provide the modulated packets to the antenna(s)1180for transmission, and to demodulate packets received from the antenna(s)1180. While the UE1115may include a single antenna, there may be examples in which the UE1115may include multiple antennas1180.

According to the architecture ofFIG. 11, the UE1115may further include a communications management module1130. The communications management module1130may manage communications with various base stations or eNBs. The communications management module1130may be a component of the UE1115in communication with some or all of the other components of the UE1115over the one or more buses1135. Alternatively, functionality of the communications management module1130may be implemented as a component of the transceiver module(s)1170, as a computer program product, and/or as one or more controller elements of the processor module1110.

The UE LTE module1140may be configured to perform and/or control some or all of the features and/or functions described with reference toFIGS. 1, 2A, 2B, 4, 5, 6, 7, 9A, and/or9B related to using LTE-based communications in a licensed and/or unlicensed spectrum. For example, the UE LTE module1140may be configured to support a supplemental downlink mode, a carrier aggregation mode, and/or a standalone mode. The UE LTE module1140may include an LTE module1145configured to handle LTE communications, an LTE unlicensed module1150configured to handle LTE communications, and/or an unlicensed module1155configured to handle communications other than LTE in an unlicensed spectrum. The UE LTE module1140may also include an LTE HARQ module1160configured to perform, for example, any of the UE LTE HARQ functions described with reference toFIGS. 1, 4, 5, 6, 7, 9A, and/or9B. The LTE HARQ module1160may be an example of similar modules (e.g., module920and/or module960) described with reference toFIGS. 9A and/or 9B. The UE LTE module1140, or portions of it, may include a processor, and/or some or all of the functionality of the UE LTE module1140may be performed by the processor module1110and/or in connection with the processor module1110.

Turning next toFIG. 12, a block diagram of a multiple-input multiple-output (MIMO) communication system1200is shown including an eNB1205and a UE1215. The eNB1205and the UE1215may support LTE-based communications using a licensed and/or unlicensed spectrum. The eNB1205may be an example of one or more aspects of the eNBs or devices105,205,805,855, and/or1005described with reference toFIGS. 1, 2A, 2B, 8A, 8B, and/or10, while the UE1215may be an example of one or more aspects of the UEs or devices115,215,915,955, and/or1115described with reference toFIGS. 1, 2A, 2B, 9A, 9B, and/or11. The system1200may illustrate aspects of the wireless communications system100,200, and/or250described with reference toFIGS. 1, 2A, and/or2B.

The eNB1205may be equipped with antennas1234-athrough1234-x, and the UE1215may be equipped with antennas1252-athrough1252-n. In the system1200, the eNB1205may be able to send data over multiple communication links at the same time. Each communication link may be called a “layer” and the “rank” of the communication link may indicate the number of layers used for communication. For example, in a 2×2 MIMO system where eNB1205transmits two “layers,” the rank of the communication link between the eNB1205and the UE1215may be two.

At the eNB1205, a transmit (Tx) processor1220may receive data from a data source. The transmit processor1220may process the data. The transmit processor1220may also generate reference symbols and/or a cell-specific reference signal. A transmit (Tx) MIMO processor1230may perform spatial processing (e.g., precoding) on data symbols, control symbols, and/or reference symbols, if applicable, and may provide output symbol streams to the transmit (Tx) modulators/demodulator1232-athrough1232-x. Each modulator/demodulator1232may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator/demodulator1232may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink (DL) signal. In one example, DL signals from modulator/demodulator1232-athrough1232-xmay be transmitted via the antennas1234-athrough1234-x, respectively.

At the UE1215, the antennas1252-athrough1252-nmay receive the DL signals from the eNB1205and may provide the received signals to the receive (Rx) modulator/demodulators1254-athrough1254-n, respectively. Each modulator/demodulator1254may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each modulator/demodulator1254may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector1256may obtain received symbols from all the modulator/demodulators1254-athrough1254-n, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive (Rx) processor1258may process (e.g., demodulate, deinterleave, and decode) the detected symbols, providing decoded data for the UE1215to a data output, and provide decoded control information to a processor1280, or memory1282. The processor1280may include a module or function1281that may perform various functions related to using LTE-based communications in a licensed and/or unlicensed spectrum. For example, the module or function1281may perform some or all of the functions of the LTE HARQ module920,960, and/or1160described with reference toFIGS. 9A, 9B, and/or11, and/or the UE LTE module1140described with reference toFIG. 11.

On the uplink (UL), at the UE1215, a transmit (Tx) processor1264may receive and process data from a data source. The transmit processor1264may also generate reference symbols for a reference signal. The symbols from the transmit processor1264may be precoded by a transmit (Tx) MIMO processor1266if applicable, further processed by the transmit (Tx) modulator/demodulators1254-athrough1254-n(e.g., for SC-FDMA, etc.), and be transmitted to the eNB1205in accordance with the transmission parameters received from the eNB1205. At the eNB1205, the UL signals from the UE1215may be received by the antennas1234, processed by the receiver (Rx) modulator/demodulators1232, detected by a MIMO detector1236if applicable, and further processed by a receive (Rx) processor1238. The receive processor1238may provide decoded data to a data output and to the processor1240. The processor1240may include a module or function1241that may perform various aspects related to using LTE-based communications in a licensed and/or unlicensed spectrum. For example, the module or function1241may perform some or all of the functions of the LTE HARQ module820,860, and/or1090described with reference toFIGS. 8A, 8B, and/or10, the CCA module861described with reference toFIG. 8B, and/or the eNB LTE module1070described with reference toFIG. 10.

The components of the eNB1205may, individually or collectively, be implemented with one or more ASICs adapted to perform some or all of the applicable functions in hardware. Each of the noted modules may be a means for performing one or more functions related to operation of the system1200. Similarly, the components of the UE1215may, individually or collectively, be implemented with one or more ASICs adapted to perform some or all of the applicable functions in hardware. Each of the noted components may be a means for performing one or more functions related to operation of the system1200.

FIG. 13is a flow chart illustrating an example of a method1300for wireless communications. For clarity, the method1300is described below with reference to one of the eNBs or devices105,205,805,855,1005, and/or1205described with reference toFIGS. 1, 2A, 2B, 8A, 8B, 10, and/or12and one of the UEs or devices115,215,915,955,1115, and/or1215described with reference toFIGS. 1, 2A, 2B, 9A, 9B, 10, and/or12. In one examples, an eNB may execute one or more sets of codes to control the functional elements of the eNB to perform the functions described below.

At block1305, a sequence number corresponding to a data frame and one or more data subframes of the data frame may be transmitted over an unlicensed spectrum to a UE. An example transmission of a sequence number425corresponding to a data frame405and one or more data subframes430,431,432,433is described with reference toFIG. 4. The operation(s) at block1305may in some cases be performed using the eNB LTE HARQ module820,860, and/or1090described with reference toFIGS. 8A, 8B, and/or10, the sequence number module863and/or DL HARQ module864described with reference toFIG. 8B, and/or the module or function1241described with reference toFIG. 12.

At block1310, HARQ feedback for the one or more data subframes may be received over the unlicensed spectrum, from the UE, when the sequence number corresponding to the data frame is received by the UE in a specified order (e.g., numerical order). An example transmission of HARQ feedback445,446,447,448is described with reference toFIG. 4.

In some cases, a separate HARQ feedback message may be received for each of the one or more data subframes. In some cases, HARQ feedback may be received for each of the one or more data subframes during each of one or more corresponding uplink subframes, and each corresponding uplink subframe may occur during the data frame or during a next data frame.

The operation(s) at block1310may in some cases be performed using the eNB LTE HARQ module820,860, and/or1090described with reference toFIGS. 8A, 8B, and/or10, the HARQ feedback module865described with reference toFIG. 8B, and/or the module or function1241described with reference toFIG. 12.

In some examples of the method1300, the method1300may continue with the transmission over the unlicensed spectrum, to the UE, of a sequence number corresponding to a subsequent data frame and one or more data subframes of the subsequent data frame. HARQ feedback for the one or more data subframes of the subsequent data frame may then be received over the unlicensed spectrum, from the UE, when the sequence number for the subsequent data frame is received by the UE in the specified order. An example transmission of a sequence number425-acorresponding to a subsequent data subframe405-aand one or more data subframes430-a,431-a,432-a,433-aof the subsequent data frame is described with reference toFIG. 4. An example transmission of HARQ feedback445-a,446-a,447-a,448-ais also described with reference toFIG. 4.

In some examples of the method1300, HARQ feedback may not be transmitted by the UE for the one or more data subframes when the sequence number corresponding to the data frame is received by the UE out of order. An example out of order sequence number525-aand non-transmission of HARQ feedback is described with reference toFIG. 5.

In some examples, CCA may be performed to determine availability of the unlicensed spectrum, and the unlicensed spectrum may be accessed during the data frame (e.g., for transmitting the sequence number and/or data subframes at block1305) when a determination is made that the unlicensed spectrum is available. Another CCA may be performed to determine availability of the unlicensed spectrum during the next data frame, and so on.

Thus, the method1300may provide for wireless communications. It should be noted that the method1300is just one implementation and that the operations of the method1300may be rearranged or otherwise modified such that other implementations are possible.

FIG. 14is a flow chart illustrating an example of a method1400for wireless communications. For clarity, the method1400is described below with reference to one of the eNBs or devices105,205,805,855,1005, and/or1205described with reference toFIGS. 1, 2A, 2B, 8A, 8B, 10, and/or12and one of the UEs or devices115,215,915,955,1115, and/or1215described with reference toFIGS. 1, 2A, 2B, 9A, 9B, 10, and/or12. In one example, an eNB may execute one or more sets of codes to control the functional elements of the eNB to perform the functions described below.

At block1405, a sequence number corresponding to a data frame and a plurality of data subframes of the data frame may be transmitted over an unlicensed spectrum to a UE. An example transmission of a sequence number425corresponding to a data frame405and a plurality of data subframes430,431,432,433is described with reference toFIG. 4. The operation(s) at block1405may in some cases be performed using the eNB LTE HARQ module820,860, and/or1090described with reference toFIGS. 8A, 8B, and/or10, the sequence number module863and/or DL HARQ module864described with reference toFIG. 8B, and/or the module or function1241described with reference toFIG. 12.

At block1410and/or1415, HARQ feedback for the plurality of data subframes may be received over the unlicensed spectrum, from the UE, when the sequence number corresponding to the data frame is received by the UE in a specified order (e.g., numerical order). At block1410, and during the data frame, HARQ feedback may be received for a subset of the plurality of data subframes (e.g., for one or more of the data subframes). At block1415, and during a next data frame, HARQ feedback may be received for a remaining subset of the plurality of data subframes (e.g., for a remaining one or more of the data subframes). An example transmission of HARQ feedback445,446,447,448is described with reference toFIG. 4.

In some cases, a separate HARQ feedback message may be received for each of the plurality of data subframes, with at least one of the HARQ feedback messages being received during the data frame and at least one of the HARQ feedback messages being received during the next data frame. In some cases, HARQ feedback may be received for each of the plurality of data subframes during each of a plurality of corresponding uplink subframes, with at least one of the corresponding uplink subframes occurring during the data frame and at least one of the corresponding uplink subframes occurring during a next data frame.

The operation(s) at block1410may in some cases be performed using the eNB LTE HARQ module820,860, and/or1090described with reference toFIGS. 8A, 8B, and/or10, the HARQ feedback module865described with reference toFIG. 8B, and/or the module or function1241described with reference toFIG. 12.

In some examples of the method1400, the method1400may continue with the transmission over the unlicensed spectrum, to the UE, of a sequence number corresponding to a subsequent data frame and one or more data subframes of the subsequent data frame. HARQ feedback for the one or more data subframes of the subsequent data frame may then be received over the unlicensed spectrum, from the UE, when the sequence number for the subsequent data frame is received by the UE in the specified order. An example transmission of a sequence number425-acorresponding to a subsequent data subframe405-aand one or more data subframes430-a,431-a,432-a,433-aof the subsequent data frame is described with reference toFIG. 4. An example transmission of HARQ feedback445-a,446-a,447-a,448-ais also described with reference toFIG. 4.

In some examples of the method1400, HARQ feedback may not be transmitted by the UE for the one or more data subframes when the sequence number corresponding to the data frame is received by the UE out of order. An example out of order sequence number525-aand non-transmission of HARQ feedback is described with reference toFIG. 5.

In some examples, CCA may be performed to determine availability of the unlicensed spectrum, and the unlicensed spectrum may be accessed during the data frame (e.g., for transmitting the sequence number and/or data subframes at block1305) when a determination is made that the unlicensed spectrum is available. Another CCA may be performed to determine availability of the unlicensed spectrum during the next data frame, and so on.

Thus, the method1400may provide for wireless communications. It should be noted that the method1400is just one implementation and that the operations of the method1400may be rearranged or otherwise modified such that other implementations are possible.

FIG. 15is a flow chart illustrating an example of a method1500for wireless communications. For clarity, the method1500is described below with reference to one of the UEs or devices115,215,915,955,1115, and/or1215described with reference toFIGS. 1, 2A, 2B, 9A, 9B, 10, and/or12and one of the eNBs or devices105,205,805,855,1005, and/or1205described with reference toFIGS. 1, 2A, 2B, 8A, 8B, 10, and/or12. In one examples, a UE may execute one or more sets of codes to control the functional elements of the UE to perform the functions described below.

At block1505, a sequence number corresponding to a data frame and one or more data subframes of the data frame may be received over an unlicensed spectrum. In some cases, the sequence number may be received at a UE from an eNB. An example transmission of a sequence number425corresponding to a data frame405and one or more data subframes430,431,432,433is described with reference toFIG. 4.

At block1510, it may be determined whether the sequence number is received in a specified order (e.g., numerical order) by the UE.

The operation(s) at block1505and/or block1510may in some cases be performed using the UE LTE HARQ module920,960, and/or1160described with reference toFIGS. 9A, 9B, and/or11, the sequence number module961and/or DL HARQ module962described with reference toFIG. 9B, and/or the module or function1281described with reference toFIG. 12.

At block1515, and upon determining at block1510that the sequence number corresponding to the data frame is received in the specified order, HARQ feedback for the one or more data subframes may be transmitted over the unlicensed spectrum (e.g., from the UE to the eNB). An example transmission of HARQ feedback445,446,447,448is described with reference toFIG. 4.

In some cases, a separate HARQ feedback message may be transmitted for each of the one or more data subframes. In some cases, HARQ feedback may be transmitted for each of the one or more data subframes during each of one or more corresponding uplink subframes, and each corresponding uplink subframe may occur during the data frame or during a next data frame.

The operation(s) at block1515may in some cases be performed using the UE LTE HARQ module920,960, and/or1160described with reference toFIGS. 9A, 9B, and/or11, the HARQ feedback module963described with reference toFIG. 9B, and/or the module or function1281described with reference toFIG. 12.

In some examples of the method1500, the method1500may continue with the reception over the unlicensed spectrum of a sequence number corresponding to a subsequent data frame and one or more data subframes of the subsequent data frame. It may then be determined whether the sequence number corresponding to the subsequent data frame is received by the UE in the specified order. Upon determining that the sequence number for the subsequent data frame is received in the specified order, HARQ feedback for the one or more data subframes of the subsequent data frame may be transmitted over the unlicensed spectrum. An example transmission of a sequence number425-acorresponding to a subsequent data subframe405-aand one or more data subframes430-a,431-a,432-a,433-aof the subsequent data frame is described with reference toFIG. 4. An example transmission of HARQ feedback445-a,446-a,447-a,448-ais also described with reference toFIG. 4.

In some examples of the method1500, it may be determined not to transmit HARQ feedback for the one or more data subframes upon determining that the sequence number corresponding to the data frame is received out of order. It may also be determined to discard the one or more data subframes upon determining that the sequence number corresponding to the data frame is received out of order. An example out of order sequence number525-aand non-transmission of HARQ feedback is described with reference toFIG. 5.

In some examples of the method1500, transmitting HARQ feedback for the one or more data subframes may include 1) transmitting HARQ feedback for a subset of the one or more data subframes during the data frame, and 2) transmitting HARQ feedback for a remaining subset of the one or more data subframes during a next data frame.

Thus, the method1500may provide for wireless communications. It should be noted that the method1500is just one implementation and that the operations of the method1500may be rearranged or otherwise modified such that other implementations are possible.

FIG. 16is a flow chart illustrating an example of a method1600for wireless communications. For clarity, the method1600is described below with reference to one of the eNBs or devices105,205,805,855,1005, and/or1205described with reference toFIGS. 1, 2A, 2B, 8A, 8B, 10, and/or12and one of the UEs or devices115,215,915,955,1115, and/or1215described with reference toFIGS. 1, 2A, 2B, 9A, 9B, 10, and/or12. In one example, an eNB may execute one or more sets of codes to control the functional elements of the eNB to perform the functions described below.

At block1605, a sequence number corresponding to a data frame and HARQ feedback may be transmitted over an unlicensed spectrum to a UE. In some cases, the HARQ feedback may include one or more uplink grants. An example transmission of a sequence number625corresponding to a data frame605and HARQ feedback including uplink grants630,631,632,633is described with reference toFIG. 6. The operation(s) at block1605may in some cases be performed using the eNB LTE HARQ module820,860, and/or1090described with reference toFIGS. 8A, 8B, and/or10, the sequence number module863and/or UL HARQ module866described with reference toFIG. 8B, and/or the module or function1241described with reference toFIG. 12.

At block1610, one or more data subframes may be received from the UE over the unlicensed spectrum, in response to the HARQ feedback, when the sequence number corresponding to the data frame is received by the UE in a specified order (e.g., numerical order). An example transmission of one or more data subframes645,646,647,648is described with reference toFIG. 6.

In some cases, the HARQ feedback may include one or more HARQ feedback messages, and a separate data subframe may be received for each of the one or more HARQ feedback messages. Each HARQ feedback message may include a separate uplink grant. In some cases, each of one or more data subframes may be received during each of one or more corresponding uplink subframes, and each corresponding uplink subframe may occur during the data frame.

The operation(s) at block1610may in some cases be performed using the eNB LTE HARQ module820,860, and/or1090described with reference toFIGS. 8A, 8B, and/or10, the data subframe receiver module867described with reference toFIG. 8B, and/or the module or function1241described with reference toFIG. 12.

In some examples of the method1600, the method1600may continue with the transmission over the unlicensed spectrum, to the UE, of a sequence number corresponding to a subsequent data frame and subsequent HARQ feedback. One or more additional subframes may then be received from the UE over the unlicensed spectrum, in response to receiving the subsequent HARQ feedback, when the sequence number for the subsequent data frame is received by the UE in the specified order. An example transmission of a sequence number625-acorresponding to a subsequent data subframe605-aand HARQ feedback630-a,631-a,632-a,633-aof the subsequent data frame is described with reference toFIG. 6. An example transmission of one or more additional data subframes645-a,646-a,647-a,648-ain response to receiving the HARQ feedback of the subsequent data frame is also described with reference toFIG. 6.

In some examples of the method1600, the one or more data subframes may not be transmitted by the UE when the sequence number corresponding to the data frame is received by the UE out of order. An example out of order sequence number725-aand non-transmission of one or more data subframes is described with reference toFIG. 7.

In some examples, CCA may be performed to determine availability of the unlicensed spectrum, and the unlicensed spectrum may be accessed during the data frame (e.g., for transmitting the sequence number and/or HARQ feedback at block1705) when a determination is made that the unlicensed spectrum is available. Another CCA may be performed to determine availability of the unlicensed spectrum during the next data frame, and so on.

Thus, the method1600may provide for wireless communications. It should be noted that the method1600is just one implementation and that the operations of the method1600may be rearranged or otherwise modified such that other implementations are possible.

FIG. 17is a flow chart illustrating an example of a method1700for wireless communications. For clarity, the method1700is described below with reference to one of the UEs or devices115,215,915,955,1115, and/or1215described with reference toFIGS. 1, 2A, 2B, 9A, 9B, 10, and/or12and one of the eNBs or devices105,205,805,855,1005, and/or1205described with reference toFIGS. 1, 2A, 2B, 8A, 8B, 10, and/or12. In one example, a UE may execute one or more sets of codes to control the functional elements of the UE to perform the functions described below.

At block1705, a sequence number corresponding to a data frame and HARQ feedback may be received over an unlicensed spectrum. In some cases, the sequence number may be received at a UE from an eNB. In some cases, the HARQ feedback may include one or more uplink grants. An example transmission of a sequence number425corresponding to a data frame605and HARQ feedback including uplink grants630,631,632,633is described with reference toFIG. 6. T

At block1710, it may be determined whether the sequence number is received in a specified order (e.g., numerical order) by the UE.

The operation(s) at block1705and/or block1710may in some cases be performed using the UE LTE HARQ module920,960, and/or1160described with reference toFIGS. 9A, 9B, and/or11, the sequence number module961and/or UL HARQ module964described with reference toFIG. 9B, and/or the module or function1281described with reference toFIG. 12.

At block1715, and upon determining at block1710that the sequence number corresponding to the data frame is received in the specified order, one or more data subframes may be transmitted over the unlicensed spectrum (e.g., from the UE to the eNB) in response to receiving the HARQ feedback. An example transmission of one or more data subframes645,646,647,648is described with reference toFIG. 6.

In some cases, the HARQ feedback may include one or more HARQ feedback messages, and a separate data subframe may be transmitted for each of the one or more HARQ feedback messages. Each HARQ feedback message may include a separate uplink grant. In some cases, each of one or more data subframes may be transmitted during each of one or more corresponding uplink subframes, and each corresponding uplink subframe may occur during the data frame.

The operation(s) at block1715may in some cases be performed using the UE LTE HARQ module920,960, and/or1160described with reference toFIGS. 9A, 9B, and/or11, the data subframe transmitter module965described with reference toFIG. 9B, and/or the module or function1281described with reference toFIG. 12.

In some examples of the method1700, the method1700may continue with the reception over the unlicensed spectrum of a sequence number corresponding to a subsequent data frame and subsequent HARQ feedback. It may then be determined whether the sequence number corresponding to the subsequent data frame is received by the UE in the specified order. Upon determining that the sequence number for the subsequent data frame is received in the specified order, one or more additional data subframes of the subsequent data frame may be transmitted over the unlicensed spectrum, in response to receiving the subsequent HARQ feedback. An example transmission of a sequence number625-acorresponding to a subsequent data subframe605-aand HARQ feedback630-a,631-a,632-a,633-aof the subsequent data frame is described with reference toFIG. 6. An example transmission of one or more additional data subframes645-a,646-a,647-a,648-ain response to receiving the HARQ feedback of the subsequent data frame is also described with reference toFIG. 6.

In some examples of the method1700, the one or more data subframes may not be transmitted when the sequence number corresponding to the data frame is received out of order. An example out of order sequence number725-aand non-transmission of one or more data subframes is described with reference toFIG. 7.

Thus, the method1700may provide for wireless communications. It should be noted that the method1700is just one implementation and that the operations of the method1700may be rearranged or otherwise modified such that other implementations are possible.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed 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 herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. A processor may in some cases be in electronic communication with a memory, where the memory stores instructions that are executable by the processor.