OA18319A - Timing information for discovery in unlicensed spectrum. - Google Patents

Abstract

Apparatus and methods for transmitting and discovering timing information during wireless communications are described herein. In an aspect, the systems and methods include monitoring at a user equipment (UE) over an unlicensed radio frequency spectrum band for a discovery signal from a network entity; receiving the discovery signal during a subframe from the network entity; and determining a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes timing information corresponding to the current subframe location.

Description

[0001] The présent Application for Patent claims priority to U.S. Provisional Application No. 62/109,504 entitled “TIMING INFORMATION FOR DISCOVERY IN UNLICENSED 10 SPECTRUM” filed January 29, 2015, and to U.S. Patent Application No. 15/009,730, entitled “TIMING INFORMATION FOR DISCOVERY IN UNLICENSED SPECTRUM” and filed on January 28,2016, both applications assigned to the assignée hereof, and both applications expressiy incorporated by reference herein in their entirety.

BACKGROUND [0002] Aspects of this dîsclosure relate generally to télécommunications, and more particularly to techniques for transmitting and receiving synchronization signais over an unlicensed radio frequency spectrum band.

[0003] A wireless communication network may be deployed to provide various types of services 20 (e.g., voice, data, multimedia services, etc.) to users within a coverage area of the network.

In some implémentations, one or more access points (e.g., corresponding to different cells) provide wireless connectivity for access terminais (e.g., cell phones) that are operating within the coverage of the access point(s). In some implémentations, peer devices provide wireless connectively for communicating with one another.

[QQ04] Communication between devices in a wireless communication network may be subject to interférence. For a communication from a first network device to a second network device, émissions of radio frequency (RF) energy by a nearby device may interfère with réception of signais at the second network device. For example, a Long Term Evolution (LTE) device operating in an unlicensed RF band that is also being used by a Wi-Fi device 30 may expérience signîficant interférence from the Wi-Fi device, and/or can cause signîficant interférence to the Wi-Fi device.

[0005] Some modes of communication may enable communications between a base station and a user equipment (UE) over an unlicensed radio frequency spectrum band, or over different radio frequency spectrum bands (e.g., a licensed radio frequency spectrum band 35 and/or an unlicensed radio frequency spectrum band) of a cellular network. With increasing data traffic in cellular networks that use a licensed radio frequency spectrum band, offloading of at least some data traffic to an unlicensed radio frequency spectrum band may provide a cellular operator with opportunities for enhanced data transmission capacity. An unlicensed radio frequency spectrum band may also provide service in areas where access to a licensed radio frequency spectrum band is unavailable.

[0006] In some wireless networks, certain transmission procedures may not be permitted over an unlicensed frequency spectrum band. As such, a UE may be unable to properly receive and détermine synchronization information for a network entity and/or cell. As a resuit, 10 the UE may be unable to properly connect to the network entity and/or cell. Thus, improvements in discovery and synchronization procedures may be desired.

SUMMARY [0007] The following présents a simplified summary of one or more aspects in order to provide 15 a basic understanding of such aspects. This summary is not an extensive overview of ail contemplated aspects, and is intended to neither identify key or critical éléments of ail aspects nor delineate the scope of any or ail aspects. Its sole purpose is to présent some concepts of one or more aspects in a simplified form as a préludé to the more detailed description that is presented later.

[QH)8] In accordance with an aspect, a présent method relates to discovering timing information during wireless communications. The described aspects include monitoring at a user equipment (UE) over an unlicensed radio frequency spectrum band for a discovery signal from a network entity. The described aspects further include receiving the discovery signal during a subframe from the network entity. The described aspects further include 25 determinîng a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes timing information corresponding to the current subframe location.

[0009] In another aspect, a présent computer-readable medium storing computer exécutable code relates to discovering timing information during wireless communications. The described 30 aspects further include code for monitoring at a UE over an unlicensed radio frequency spectrum band for a discovery signal from a network entity. The described aspects further include code for receiving the discovery signal during a subframe from the network entity. The described aspects further include code for determinîng a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes 35 timing information corresponding to the current subframe location.

[0010] In further aspects, a présent apparatus relates to discovering timing information during wireless communications. The described aspects include means for monitoring at a UE over an unlicensed radio frequency spectrum band for a discovery signal from a network entity. The described aspects further include means for receiving the discovery signal during a subframe from the network entity. The described aspects further include means for determining a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes timing information corresponding to the current subframe location.

[QUI] In an additional aspect, a présent apparatus relates to discovering timing information during wireless communications. The described aspects include a memory configured to store data, and one or more processors communicatively coupled with the memory, wherein the one or more processors and the memory are configured to monitor at a UE over an unlicensed radio frequency spectrum band for a discovery signal from a network 15 entity. The described aspects further receive the discovery signal during a subframe from the network entity. The described aspects further détermine a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes timing information corresponding to the current subframe location.

[0012] In another aspect, a présent method relates to transmitting timing information during 20 wireless communications. The described aspects include establishing at a network entity the timing information for a discovery signal, wherein the timing information corresponds to a current subframe location of the network entity. The described aspects further include transmitting the discovery signal during a subframe over an unlicensed radio frequency spectrum band to a UE.

[QŒ13] In a further aspects, a présent computer-readable medium storing computer exécutable code relates to transmitting timing information during wireless communications. The described aspects include code for establishing at a network entity the timing information for a discovery signal, wherein the timing information corresponds to a current subframe location of the network entity. The described aspects further include code for transmitting 30 the discovery signal during a subframe over an unlicensed radio frequency spectrum band to a UE.

[0014] In another aspect, a présent apparatus relates to transmitting timing information during wireless communications. The described aspects include means for establishing at a network entity the timing information for a discovery signal, wherein the timing 35 information corresponds to a current subframe location of the network entity. The described aspects further include means for transmitting the discovery signal during a subframe over an unlicensed radio frequency spectrum band to a UE.

[0Œ15] In an additional aspect, a présent apparatus relates to transmitting timing information during wireless communications. The described aspects include a memory configured to store data, and one or more processors communicatively coupled with the memory, wherein the one or more processors and the memory are configured to establish at a network entity the timing information for a discovery signal, wherein the timing 10 information corresponds to a current subframe location of the network entity. The described aspects further include transmit the discovery signal during a subframe over an unlicensed radio frequency spectrum band to a UE.

[0016] Various aspects and features of the disclosure are described in further detail below with reference to various examples thereof as shown in the accompanying drawings. While 15 the présent disclosure is described below with reference to various examples, it should be understood that the présent disclosure is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional implémentations, modifications, and examples, as wel) as other fields of use, which are within the scope of the présent disclosure as described herein, and with respect to which the présent disclosure 20 may be of significant utility.

BRIEF DESCRIPTION OF THE DRAWINGS [0017] A further understanding of the nature and advantages of the présent invention may be realized by reference to the following drawings. In the appended figures, similar 25 components or features may hâve the same reference label. Further, various components of the same type may be distinguished by following the reference label by a second label that distinguishes among the similar components. If the first reference label is used in the spécification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[0818] FIG. 1 is a block diagram illustrating an example of several aspects of a communication System employing co-located radios.

[0019] FIG. 2 shows a downlink frame structure used in LTE.

[0020] FIG. 3 is a diagram illustrating an example of carrier sense adaptive transmission (CSAT) time division multiplexing (TDM) duty cycling.

[0021] FIG. 4 is schematic diagram illustrating an example of a communication network including an aspect of transmitting and discovering timing information during wireless communication.

[0(822] FIGs. 5A and 5B are flow diagrams illustrating an example method of discovering timing information during wireless communication.

[0023] FIG. 6 is a flow diagram illustrating another example method of transmitting timing information during wireless communication.

[0024] FIG. 7 is a conceptual diagram illustrating an example of the discovery procedure between 10 the UE and the network entity.

[0025] FIG. 8 is a simplified block diagram of several sample aspects of components that may be employed in communication nodes.

[0026] FIG. 9 is a simplified diagram of a wireless communication System.

[0027] FIG. 10 is a simplified diagram of a wireless communication System including small cells. [QG28] FIG. 11 is a simplified diagram illustrating coverage areas for wireless communication.

[0029] FIG. 12 is a simplified block diagram of several sample aspects of communication components.

DETAILED DESCRIPTION [ΜΒ0] The présent aspects generally relate to transmitting and discovery timing information during wireless communication. For example, prior to gaîning access to, and communicating over, an unlicensed radio frequency spectrum band, a base station or UE may perform a listen before talk (LBT) procedure to contend for access to the unlicensed radio frequency spectrum band. An LBT procedure may include performing a clear 25 channel assessment (CCA) procedure to détermine whether a channel of the unlicensed radio frequency spectrum band is available. The CCA procedure is composed of two related functions, carrier sense (CS) and energy détection (ED). Carrier sense refers the ability of the receiver to detect and décodé an incomîng Wi-Fi signal preamble. Energy détection (ED) refers to the ability of the receiver to detect the non-Wi-Fi energy level 30 présent on the current channel (frequency range) based on the noise floor, ambient energy, interférence sources, and unidentifiable Wi-Fi transmissions that may hâve been corrupted and can no longer be decoded. Unlike carrier sense, which can détermine the exact length of time the medium will be busy with the current frame, energy détection must sample the medium every slot time to détermine if the energy still exists. When it 35 is determined that the channel of the unlicensed radio frequency spectrum band is not available (e.g., because another apparatus is already using the channel of the unlicensed radio frequency spectrum band), a CCA procedure may be performed for the channel again at a later time.

[0Œ31] Before a UE may communicate with a base station, the UE may need to discover or acquîre the base station (or a cell). After a UE discovers the base station or cell, the UE may need to periodically synchronize with the base station or cell in order to properly communicate with, and décodé communications from, the base station. In some examples, a base station may transmit a synchronization signal, and a UE may receive 10 and décodé the synchronization signal to discover and/or synchronize with the base station (or with a cell). Most transmissions onto the unlicensed carriers in networks with unlicensed spectrum are made by transmitters after first complying with the LBT protocole. However, certain transmissions are made without first checking for a clear channel. CCA-exempt transmissions (CET) occur in both downlink and uplink 15 communications. In an aspect, the network may prohibit CETs and/or the discovery signal transmitted in CETs may not be decodable due to interférence. As a resuit, the timing information may not be known to the UE, and so, the UE may not be able to properly connect with the network.

[0032] Accordingly, in some aspects, the présent methods and apparatuses may provide an 20 efficient solution, as compared to current solutions, by transmitting and discovering timing information during wireless communication over an unlicensed frequency spectrum band. In the instances where the network may prohibit CETs and/or the discovery signal transmitted in CETs may not be decodable due to interférence, the présent methods and apparatus provide that timing information may be transmitted as part 25 of the discovery signal instead of the CETs. As such, the timing information allows the UE to détermine the current subframe location in which the discovery signal is présent, which in tum, causes the UE to détermine the discovery window, discovery period, and radio frame boundary.

[0033] Aspects of the disclosure are provided in the following description and related drawings 30 directed to spécifie disclosed aspects. Altemate aspects may be devised without departing from the scope of the disclosure. Additionally, wetl-known aspects of the disclosure may not be described in detail or may be omitted so as not to obscure more relevant details. Further, many aspects are described in terms of sequences of actions to be performed by, for example, éléments of a computing device. It will be recognized that various actions 35 described herein can be performed by spécifie circuits (e.g., application spécifie integrated circuits (ASICs)), by program instructions being executed by one or more processors, or by a combination of both. Additionally, these sequence of actions described herein can be considered to be embodied entirely within any form of computer readable storage medium having stored therein a corresponding set of computer instructions that upon execution would cause an associated processor to perform the functionality described herein. Thus_t the various aspects of the disclosure may be embodied in a number of different forms, ail of which hâve been contemplated to be within the scope of the claimed subject matter. In addition, for each of the aspects described herein, the 10 corresponding form of any such aspects may be described herein as, for example, “logic configured to” perform the described action.

[0034] FIG. 1 illustrâtes several nodes of a sample communication System 100 (e.g., a portion of a communication network) where an access terminal may include a subframe component 420 (FIG. 4), and where an access point may include a corresponding 15 subframe component 460 (FIG. 4), wherein the respective subframe components operate to enable the access terminal to discover and/or synchronize with the access point when the access terminal is operating in a standalone mode in an unlicensed radio frequency spectrum band. The details of the operation of subframe component 420 and subframe component 460 are described below with respect to FIGS. 4-8. For illustration purposes, 20 various aspects of the disclosure will be described in the context of one or more access terminais, access points, and network entities that communicate with one another. It should be appreciated, however, that the teachings herein may be applicable to other types of apparatuses or other similar apparatuses that are referenced using other terminology. For example, in various implémentations access points may be referred to or implemented 25 as base stations, NodeBs, eNodeBs, Home NodeBs, Home eNodeBs, small cells, macro cells, femto cells, and so on, while access terminais may be referred to or implemented as user equipment (UEs), mobile stations, and so on.

[0035] Access points, which may correspond to network entity 404 including subframe component 420 (FIG. 4), in the System 100 provide access to one or more services (e.g., 30 network connectivity) for one or more wireless terminais (e.g., the access terminal 102 or the access terminal 104) that may be installed within or that may roam throughout a coverage area of the System 100. For example, at various points in time the access terminal 102 may connect to the access point 106 or some other access point in the System 100 (not shown). Similarly, the access terminal 104 may connect to the access point 108 35 or some other access point.

[0036] One or more of the access points may communicate with one or more network entities (represented, for convenience, by the network entities 110), including each other, to facilitate wide area network connectivity. Two or more of such network entities may be

F ' co-located and/or two or more of such network entities may be dîstributed throughout a network.

[0037] A network entity may take various forms such as, for example, one or more radio and/or core network entities. Thus, in various implémentations the network entities Π0 may represent functionality such as at least one of: network management (e.g., via an 10 operation, administration, management, and provisioning entity), call control, session management, mobility management, gateway fonctions, interworking fonctions, or some other suitable network functionality. In some aspects, mobility management relates to: keeping track of the current location of access terminais through the use of tracking areas, location areas, routing areas, or some other suitable technique; controlling paging for 15 access terminais; and providing access control for access terminais.

[0038] When the access point 106 (or any other devices in the system 100) uses a first RAT to communicate on a given resource, this communication may be subjected to interférence from nearby devices (e.g., the access point 108 and/or the access terminal 104) that use a second RAT to communicate on that resource. For example, communication by the access 20 point 106 via LTE on a particular unlîcensed RF band may be subject to interférence from Wi-Fi devices operating on that band. For convenience, LTE on an unlîcensed RF band may be referred to herein as LTE/LTE Advanced în unlîcensed spectrum, or simply LTE in the surrounding context. Moreover, a network or device that provides, adapts, or extends LTE/LTE Advanced in unlîcensed spectrum may refer to a network or device that 25 is configured to operate in a contention-based radio frequency band or spectrum.

[0039] In some Systems, LTE in unlîcensed spectrum may be employed in a standalone configuration, with ail carriers operating exclusively in an unlîcensed portion of the wireless spectrum (e.g., LTE Standalone). In other Systems, LTE in unlîcensed spectrum may be employed in a manner that is supplémentai to licensed band operation by 30 providing one or more unlîcensed carriers operating in the unlîcensed portion of the wireless spectrum in conjunction with an anchor licensed carrier operating in the licensed portion of the wireless spectrum (e.g., LTE Supplémentai DownLink (SDL)). In either case, carrier aggregation may be employed to manage the different component carriers, with one carrier serving as the Primary Cell (PCell) for the corresponding UE (e.g., an 35 anchor licensed carrier in LTE SDL or a designated one of the unlîcensed carriers in LTE

Standalone) and the remaining carriers serving as respective Secondary Cells (SCells). In this way, the PCell may provide an FDD paired downlink and uplink (licensed or unlîcensed), and each SCell may provide additional downlink capacity as desired.

[0Œ40] In general, LTE utilizes orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain 10 with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fîxed, and the total number of subcarriers (K) may be dépendent on the System bandwidth. For example, K may be equal to 128,256,512,1024 or 2048 for System bandwidth of 1.25, 2.5, 5, 10 or 20 mégahertz (MHz), respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.08 15 MHz, and there may be 1,2,4,8 or 16 subbands for system bandwidth of 1.25,2.5,5,10 or 20 MHz, respectively.

[0041] FIG. 2 shows a downlink frame structure 200 used in LTE, which may be used in sending communications from subframe component 460 (FIG. 4) to subframe component 420 (FIG. 4). The transmission timeline for the downlink may be partitioned into units of radio 20 frames 202, 204, 206. Each radio frame may hâve a predetermined duration (e.g., 10 milliseconds (ms)) and may be partitioned into 10 subframes 208 with indices of 0 through 9. Each subframe may include two slots, e.g., slots 210. Each radio frame may thus include 20 slots with indices of 0 through 19. Each slot may include L symbol periods, e.g., 7 symbol periods 212 for a normal cyclic prefix (CP), as shown in FIG. 2, 25 or 6 symbol periods for an extended cyclic prefix. The normal CP and extended CP may be referred to herein as different CP types. The 2L symbol periods in each subframe may be assigned indices of 0 through 2L-1, The available time frequency resources may be partitioned into resource blocks. Each resource block may cover N subcarriers (e.g., 12 subcarriers) in one slot.

[(N42] In LTE, the access point (referred to as an eNB), which may correspond to network entity 404 including subframe component 420 (FIG. 4), may send a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) for each cell in the eNB. The primary and secondary synchronization signais may be sent in symbol periods 6 and 5, respectively, in each of subframes 0 and 5 of each radio frame with the normal cyclic 35 prefix, as shown in FIG. 2. The synchronization signais may be used by the access terminais (referred to as UEs) for cell détection and acquisition. The eNB may send a Physical Broadcast Channel (PBCH) in symbol periods 0 to 3 in slot 1 of subframe 0. The PBCH may carry certain system information.

ιο [0(M3] The eNB may send a Cell-specific Référencé Signal (CRS) for each cell in the eNB. The CRS may be sent in symbols 0,1, and 4 of each slot in case of the normal cyclic prefix, and in symbols 0, 1, and 3 of each slot in case of the extended cyclic prefix. The CRS may be used by UEs for cohérent démodulation of physical channels, timing and frequency tracking, Radio Link Monîtoring (RLM), Référencé Signal Received Power 10 (RSRP), and Référencé Signal Received Quality (RSRQ) measurements, etc.

[0044] The eNB may send a Physical Control Format Indicator Channel (PCFICH) in only a portion of the first symbol period of each sub frame, although depicted in the entire first symbol period in FIG. 2. The PCFICH may convey the number of symbol periods (M) used for control channels, where M may be equal to 1, 2 or 3 and may change from 15 subframe to subframe. M may also be equal to 4 for a small system bandwidth, e.g., with less than 10 resource blocks. In the example shown in FIG. 2, M=3. The eNB may send a Physical HARQ Indicator Channel (PHICH) and a Physical Downlink Control Channel (PDCCH) in the first M symbol periods of each subframe (M=3 in FIG. 2). The PHICH may carry information to support hybrid automatic retransmission (HARQ). The PDCCH 20 may carry information on resource allocation for UEs and control information for downlink channels. Although not shown in the first . symbol period in FIG. 2, it is understood that the PDCCH and PHICH may also be included in the first symbol period. Similarly, the PHICH and PDCCH may also both be in the second and third symbol periods, although not shown that way in FIG. 2. The eNB may send a Physical Downlink 25 Shared Channel (PDSCH) in the remaining symbol periods of each subframe. The PDSCH may carry data for UEs scheduled for data transmission on the downlink. The various signais and channels in LTE are described in 3GPP TS 36.211, entitled Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation, which îs publicly available.

[M45] The eNB may send the PSS, SSS and PBCH in the center 1.08 MHz of the system bandwidth used by the eNB. The eNB may send the PCFICH and PHICH across the entire system bandwidth in each symbol period in which these channels are sent. The eNB may send the PDCCH to groups of UEs in certain portions of the system bandwidth. The eNB may send the PDSCH to spécifie UEs in spécifie portions of the system bandwidth. The 35 eNB may send the PSS, SSS, PBCH, PCFICH and PHICH in a broadeast manner to ail UEs, may send the PDCCH in a unicast manner to spécifie UEs, and may also send the PDSCH in a unicast manner to spécifie UEs.

[<XM6] A number of resource éléments may be available in each symbol period. Each resource element may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value. Resource éléments not used for a référencé signal in each symbol period may be arranged into resource element groups (REGs). Each REG may include four resource éléments in one symbol period. The 10 PCFICH may occupy four REGs, which may be spaced approximately equally across frequency, in symbol period 0. The PHICH may occupy three REGs, which may be spread across frequency, in one or more configurable symbol periods. For example, the three REGs for the PHICH may ail belong in symbol period 0 or may be spread in symbol periods 0,1 and 2. The PDCCH may occupy 9,18,32 or 64 REGs, which may be selected 15 from the available REGs, in the first M symbol periods. Only certain combinations of REGs may be allowed for the PDCCH.

[0047] A UE may know the spécifie REGs used for the PHICH and the PCFICH. The UE may search different combinations of REGs for the PDCCH. The number of combinations to search is typically less than the number of allowed combinations for the PDCCH. An eNB 20 may send the PDCCH to the UE in any of the combinations that the UE will search. A UE may be within the coverage of multiple eNBs. One of these eNBs may be selected to serve the UE. The serving eNB may be selected based on various criteria such as received power, path loss, signal-to-noise ratio (SNR), etc.

[0048] Retuming to FIG. 1, the disclosure relates in some aspects to techniques referred to herein 25 as carrier sense adaptive transmission (CSAT), which may be used to facilitate coexistence between different technologies operating on a commonly used resource (e.g., a particular unlîcensed RF band or co-channel). The access point 106 includes co-located radios (e.g., transceivers) 112 and 114. The radio 112 uses a second RAT (e.g., LTE) to communicate. The radio 114 is capable of receiving signais using a first RAT (e.g., Wi30 Fi). In addition, an interface 116 enables the radios 112 and 114 to communicate with one another.

[0049] These co-located radios are leveraged to enable a carrier sense multiple access-like (CSMA-Iike) mode of operation whereby the radio 114 repeatedly (e.g., periodically) conducts measurements on the co-channel. Based on these measurements, the radio 112 35 détermines the extent to which the co-channel is being utilized by devices operating on the first RAT. The radio 112 is thus able to adapt its communication on the channel (using the second RAT) according to the resource utilization.

[0050] For example, if the utilization of the resource by Wi-Fi devices is high, an LTE radio may adjust one or more transmission parameters that the LTE radio uses to communicate via the co-channel such that usage of the co-channel by the LTE radio is reduced. For example, the LTE radio may reduce its transmit duty cycle, transmit power, or frequency allocation.

[Qf51] Conversely, if the utilization of the resource by Wi-Fi devices is low, an LTE radio may adjust one or more transmission parameters that the LTE radio uses to communicate via the co-channel such that usage of the co-channel by the LTE radio is increased. For example, the LTE radio may increase its transmit duty cycle, transmit power, or frequency allocation.

[0052] The disclosed scheme may provide several advantages. For example, by adapting communication based on signais associated with the fîrst RAT, the second RAT may be configured to only react to utilization of the co-channel by devices that use the fîrst RAT. Thus, interférence by other devices (e.g., non-Wi-Fi devices) or adjacent channel interférence may be ignored, if desired. As another example, the scheme enables a device 20 that uses a given RAT to control how much protection is to be afforded to co-channel communications by devices that use another RAT. Also, such a scheme may be implemented in an LTE System without changing the LTE PHY or MAC. For example, these changes may be implemented by simply changing LTE software.

[0053] In some aspects, the advantages discussed herein may be achieved by adding a Wi-H chip 25 or similar functionality to an LTE access point. If desired, a low functionality Wi-Fi circuit may be employed to reduce costs (e.g., the Wi-Fi circuit simply providing lowlevel sniffing).

[0054] As used herein, the term co-Iocated (e.g., radios, access points, transceivers, etc.) may include in various aspects, one or more of, for ex ample: components that are in the same 30 housing; components that are hosted by the same processor; components that are within a defïned distance of one another, or components that are connected via an interface (e.g., an Ethernet switch) where the interface meets the latency requirements of any required inter-component communication (e.g., messaging).

[0055] Although aspects of the disclosure are described with respect to carrier sense adaptîve 35 transmission, the disclosure need not be so limited. The same and/or different aspects or techniques described herein may, in some instances, be implemented using other mechanisms configured to facilitate co-existence between different technologies operating on a commonly used resource (e.g., unlicensed spectrum).

[0C56] FIG. 3 illustrâtes an example of CSAT Time Division Multiplexed (TDM) duty cycling for LTE in unlicensed spectrum communicated by an access terminal, where an access terminal may include a subframe component 420 (FIG. 4), and where an access point may include a corresponding subframe component 460 (FIG. 4), wherein the respective subframe components operate to enabte the access terminal to discover and/or 10 synchronize with the access point when the access terminal is operating in a standalone mode in an unlicensed radio frequency spectrum band. The details of the operation of subframe component 420 and subframe component 460 are described below with respect to FIGS. 4-8. During time Ton, transmission on the unlicensed RF band is enabled, which may be referred to as a CSAT ON period. During time Toff, transmission on the 15 unlicensed RF band is disabled, which may be referred to as a CSAT OFF period, to enable a co-located Wi-Fi radio to conduct measurements. In this way, TDM communication duty cycling for LTE in unlicensed spectrum may be implemented to create adaptable TDM transmission patterns.

[0057] FIG. 4 is a diagram illustrating an example of a télécommunications network System 400 20 in accordance with an aspect of the présent disclosure, including at least one UE 402 in communication coverage of at least one network entity 404 (e.g., base state or node B). UE 402 can communicate with network 406 via network entity 404. In an aspect, UE 402 may include one or more processors 456, and optionally, memory 458, that may operate in combination with subframe component 420 to discover timing information during 25 wireless communication. Similarly, network entity 404 may include one or more processors 482, and optionally, memory 484, that may operate in combination with subframe component 460 to transmit timing information during wireless communications. In other words, the respective subframe components operate to enable a UE or access terminal to discover and/or synchronize with an eNodeB or access point 30 when the UE or access terminal is operating in a standalone mode and/or carrier aggregation mode in an unlicensed frequency spectrum. Accordingly, the présent aspects may enable the UE 402 to discover timing information in situations in which the network may prohibit CETs and/or the discovery signal transmitted in CETs may not be decodable due to interférence.

[0058] In an aspect, the network entity 404 may be a base station such a NodeB in an UMTS network. UE 402 may communicate with a network 406 via network entity 404. In some aspects, multiple UEs including UE 402 may be in communication coverage with one or more network entities, including network entity 404. In an example, UE 402 may transmit and/or receive wireless communications 408/410 to and/or from network entity 404. In some aspects, UE 402 may communicate with network entity 404 across the licensed and/or unlicensed spectrum using communication channel 408 (e.g., both uplink and downlink) and downlink communication channel 410.

[0059] In an aspect, each network entity 404 may include subframe component 460, which may 10 be confîgured to transmit one or more discovery signais 432 including timing information 434 over an unlicensed radio frequency spectrum to a UE, such as UE 402, which may be configured with subframe component 420 to monitor for the one or more discovery signais 432. For example, in an aspect, discovery signal 432 may include, but is not limited to, a transmitted signal on a physical channel configured to provide information to the UE 402 to connect with network entity 404. Further, for example, in an aspect, timing information may include, but is not limited to, one or more bits indicating a current subframe location in relation to the radio frame. In some instances, the unlicensed frequency band may be considered to be any portion of the radio spectrum (e.g., a portion of a shared channel in the radio spectrum) whose use is not restricted through a spectrum licensing approach. In some instances, the network 406 may be allowed to operate with clear channel assessment (CCA) exempt transmissions (CETs) and/or the discovery signal 432 transmitted in CET occasions may not be decodable due to interférence. In an aspect, the CCA procedure détermines whether a channel of the unlicensed radio frequency spectrum band is available. In previous instances, where CETs are unable to be transmitted and/or received, the timing information for the network entity 404 may be difficult to obtain or otherwise détermine. As such, subframe component 460 of network entity 404 may transmit the discovery signal 432 via downlink communication channel 410 to UE 402 without the need for a CET because the discovery signal 432 includes timing information 434 corresponding to the current subframe location of the network entity 404. For example, in an aspect, the subframe component 460 may transmit downlink control information (DCI) on a physical downlink control channel (PDCCH) and/or an enhanced PDCCH (ePDCCH) including the timing information 434.

[0060] In an aspect, subframe component 420 of UE 402 may include monitoring component 430, which may be configured to monitor over an unlicensed radio frequency spectrum 35 band for a discovery signal 432 from network entity 404. Further, subframe component 420 of UE 402 may include receiving component 440, which may be configured to receive the discovery signal 432 during a subframe 452 from the network entity 404. Moreover, subframe component 420 of UE 402 may include determinîng component 450, which may be configured to détermine a current subframe location (corresponding to subframe 452) of the network entity 404 based on the discovery signal 432, wherein the discovery signal 432 includes timing information 434 corresponding to the current subframe location. As a resuit of determining the current subframe location, UE 402 may détermine the timing information corresponding to the radio frame boundary of the network entity 404 and synchronize with the network entity 404. Subframe component 420 may be further configured to include demodulating component 454, which may be configured to demodulate the ePDCCH based on synchronization information included in the discovery signal 432.

[0061] In another aspect, subframe component 460 of network entity 404 may include 15 establishing component 470, which may be configured to establîsh the timing information 434 for inclusion in a discovery signal 432. In some instances, the timing information 434 corresponds to a current subframe location of network entity 404. Further, subframe component 460 of network entity 404 may include transmitting component 480, which may be configured to transmit the discovery signal 432 during a subframe 452 over an unlicensed radio frequency spectrum band to a UE 402. As such, the network entity 404 may transmit the discovery signal 432 without the need for CETs.

[0062] Moreover, for example, the télécommunications network System 400 may be an LTE network. The télécommunications network System 400 may include a number of evolved NodeBs (eNodeBs) (e.g., network entity 404) and UEs 402 and other network entities.

An eNodeB may be a station that communicates with the UEs 402 and may also be referred to as a base station, an access point, etc. A NodeB îs another example of a station that communicates with the UEs 402.

[0063] Each eNodeB (e.g., network entity 404) may provide communication coverage for a particular géographie area. In 3GPP, the term “cell” can refer to a coverage area of an 30 eNodeB and/or an eNodeB subsystem serving the coverage area, depending on the context in which the term îs used.

[0064] An eNodeB (e.g., network entity 404) may provide communication coverage for a small cell and/or other types of cell. The term “small cell” (or “small coverage cell”), as used herein, may refer to an access point or to a corresponding coverage area of the access 35 point, where the access point in this case has a relatively low transmit power or relatively small coverage as compared to, for example, the transmit power or coverage area of a macro network access point or macro cell. For instance, a macro cell may cover a relatively large géographie area, such as, but not Iimited to, several kilometers în radius. In contrast, a small cell may cover a relatively small géographie area, such as, but not limited to, a home, a building, or a floor of a building. As such, a small cell may include, but is not limited to, an apparatus such as a base station (BS), an access point, a femto node, a femtocell, a pico node, a micro node, a Node B, evolved Node B (eNB), home Node B (HNB) or home evolved Node B (HeNB). Therefore, the term small cell,” as used herein, refers to a relatively low transmit power and/or a relatively small coverage area cell as compared to a macro cell. An eNodeB for a macro cell may be referred to as a macro eNodeB. An eNodeB for a pico cell may be referred to as a pico eNodeB. An eNodeB for a femto cell may be referred to as a femto eNodeB or a home eNodeB.

[0065] In some aspects, UE 402 may also be referred to by those skilled in the art (as well as interchangeably herein) as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. A UE 402 may 20 be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a global positioning System (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a caméra, a game console, a wearable computing device (e.g., a smart-watch, smart-glasses, 25 a health or fitness tracker, etc), an appliance, a sensor, a vehicle communication System, a medical device, a vending machine, a device for the Intemet-of-Things, or any other similar functioning device. Addîtionally, network entity 404 may be a macrocell, picocell, femtocell, relay, Node B, mobile Node B, UE (e.g., communicating in peer-to-peer or adhoc mode with UE 402), or substantially any type of component that can communicate with UE 402 to provide wireless network access at the UE 402.

[0066] Referring to FIG. 5, in operation, a UE such as UE 402 (FIG. 4) may perform an aspect of method 500A for discovering timing information during wireless communication. While, for purposes of simplicity of explanation, the methods herein are shown and described as a sériés of acts, it is to be understood and apprecîated that the methods are not limited by the order of acts, as some acts may, in accordance with one or more aspects, occur in different orders and/or concurrently with other acts from that shown and described herein. For example, it is to be apprecîated that the methods could altemativeïy be represented as a sériés of interrelated states or events, such as in a state diagram.

Moreover, not al! illustrated acts may be required to implement a method in accordance with one or more features described herein.

[0067] In an aspect, at block 510, method 500A includes monitoring at a UE over an unlicensed radio frequency spectrum band for a discovery signal from a network entity. For example, as described herein, subframe component 420 may include monitoring component 430 10 (FIG. 4) to monitor at a UE (e.g., UE 402) over an unlicensed radio frequency spectrum band for a discovery signal 432 from a network entity 404. In some instances, the discovery signal 432 includes an enhanced System information block (eSIB), wherein the eSIB includes SIB1, SIB2, and master information block (MIB) which are parameters that allow the UE 402 to connect to the network entity 404. In certain instances, the discovery signal 432 includes synchronization information corresponding to a primary synchronization signal (PSS) and a secondary synchronization signal (SSS).

[0068] At block 520, method 500A includes receiving the discovery signal during a subframe from the network entity. For example, as described herein, subframe component 420 may include receiving component 440 (FIG. 4) to receive the discovery signal during a 20 subframe from the network entity. In some instances, the discovery signal 432 is received on a physical downlink control channel (PDCCH) and/or an enhanced PDCCH (ePDCCH) (e.g., downlink communication channel 410 of FIG. 4) from the network entity 404 during a CCA procedure to establish whether a channel of the unlicensed radio frequency spectrum band is available.

[0069] Further, at block 530, method 500A includes determining a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes timing information corresponding to the current subframe location. For example, as described herein, subframe component 420 may include determining component 450 (FIG. 4) to détermine a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes timing information corresponding to the current subframe location. In some aspects, method 500A may proceed to block 540 of FIG. 5B.

[0070] Referring to FIG. 5B, in an aspect, at block 540, method 500B includes demodulating the downlink control channel. For example, as described herein, subframe component 420 may include demodulating component 454 (FIG. 4) to demodulate the downlink control channel. In some aspects, the downlink control channel may correspond to either a PDCCH or an ePDCCH. In some instances, subframe component 420 and/or demodulating component 454 may be configured to demodulate the ePDCCH based on synchronîzatîon information included in the discovery signal 432. The subframe component 420 may demodulate the ePDCCH without a cell-specific référencé signal (CRS).

[0071] In an aspect, at block 550, method 500B includes determining a location of the eSIB within the subframe in response to demodulating the downlink control channel. For 10 example, as described herein, subframe component 420 may include determining component 450 (FIG. 4) to détermine a location of the eSIB within the subframe 452 in response to demodulating the ePDCCH.

[0072] In an aspect, at block 560, method 500B includes determining a radio frame boundary (RFB) based on the current subframe location of the network entity. For example, as 15 described herein, subframe component 420 may include determining component 450 (FIG. 4) to détermine détermine a RFB based on the current subframe location of the network entity 404.

[0073] In an aspect, at block 570, method 500B includes determining a discovery window and a discovery period based on the current subframe location of the network entity. For 20 example, as described herein, subframe component 420 may include determining component 450 (FIG. 4) to détermine a discovery window and a discovery period based on the current subframe location of the network entity 404. In some instances, a size of the discovery window and a size of the discovery period are preconfigured. In other instances, a time indication may be received by subframe component 420 corresponding 25 to the timing information for the discovery window. The discovery signal 432 may be received as a non-periodic opportunistic signal during the discovery window.

[0074] Referring to FIG. 6, in operation, a network entity such as network entity 404 (FIG. 4) may perform an aspect of method 600 for transmitting timing information during wireless communication. While, for purposes of simplicity of explanation, the methods herein are 30 shown and described as a sériés of acts, it is to be understood and appreciated that the methods are not limited by the order of acts, as some acts may, in accordance with one or more aspects, occur in different orders and/or concurrently with other acts from that shown and described herein. For example, it is to be appreciated that the methods could altematively be represented as a sériés of interrelated states or events, such as in a state 35 diagram. Moreover, not ail illustrated acts may be required to implement a method in accordance with one or more features described herein.

[0075] In an aspect, at block 610, method 600 includes establishing at a network entity the timing information for a discovery signal, wherein the timing information corresponds to a current subframe location of the network entity. For example, as described herein, subframe component 460 may include establishing component 470 (FIG. 4) to establish at a network entity the timing information for a discovery signal, wherein the timing information corresponds to a current subframe location of the network entity. In some instances, the discovery signal 432 includes an enhanced system information block 10 (eSIB), wherein the eSIB includes, at least one or more of SIB1, SIB2, and master information block (MIB), which are parameters used by the UE 402 to connect to the network entity 404.

[0076] Moreover, the subframe component 460 establishes the timing information 434 for the discovery signal 432 by determining a number of discovery Windows présent during each 15 discovery period; and calculating a number of bits to include in the discovery signal 432 based on the détermination of the number of discovery Windows présent during each discovery period. In certain instances, calculating the number of bits încluded in the discovery signal 432 further comprises calculating the number of bits based on a size of the discovery window when one discovery window is présent during each discovery 20 period. In other instances, calculating the number of bits încluded in the discovery signal 432 further comprises calculating the number of bits based on a size of the discovery period when more than one discovery window is présent during each discovery period.

[0077] Further, at block 620, method 600 includes transmittîng the discovery signal during a subframe over an unlicensed radio frequency spectrum band to a user equipment (UE).

For example, as described herein, subframe component 460 may include transmittîng component 480 (FIG. 4) to transmit the discovery signal during a subframe over an unlicensed radio frequency spectrum band to a user equipment (UE). In some instances, the discovery signal 432 is transmitted on an enhanced physical downlink control channel (ePDCCH) to the UE 402 during a clear channel assessment (CCA) procedure to establish whether a channel of the unlicensed radio frequency spectrum band is available. As such, the discovery signal 432 includes synchronization information used to demodulate the ePDCCH and wherein a location of the eSIB within the subframe is determined in response to demodulating the ePDCCH. The synchronization information may include a primary synchronization signal (PSS) and a secondary synchronization signal (SSS).

Moreover, in some instances, for example, the discovery signal may be transmitted without a cell-specific reference signal (CRS). The discovery signal may also be transmitted by the subframe component 460 as a non-periodic opportunisme signal during a discovery window.

[0Œ78] FIG. 7 shows an example 700 of transmissions made by a network entity over an unlicensed radio frequency spectrum band, in accordance with various aspects of the présent disclosure. In some examples, the network entity making the transmissions may be an example of aspects of the network entity 404 described with référencé to FIG. 4.

[0079] By way of example, FIG. 7 illustrâtes transmissions over time made by a network entity 10 over time, in three adjacent discovery periods. The three adjacent discovery periods include a first discovery period 705, a second discovery period 710, and a third discovery period715.

[0080] The transmissions made by the network entity may include synchronous transmissions made during downlink CETs (CETs 720) of the network entity, synchronous 15 transmissions made during non-periodic subframe locations (e.g., foltowing successful CCAs 725), and asynchronous transmissions made during a discovery window 730.

[0081] The discovery window 730 may be provided in each of the first discovery period 705, the second discovery period 710, and the third discovery period 715; once every N discovery periods (where N >1 ); or in one or more discovery periods on a dynamic basis. The length 20 or duration of the discovery window 730 may be shorter or longer than shown. In some examptes, the discovery window 730 may overlap in time with at least one non-periodic subframe location (e.g., at least one subframe following a CCA 725). In some examples, the discovery window 730 may be associated with a different set of subcarrier frequencies of the unlicensed radio frequency spectrum band than the set of subcarrier frequencies 25 included in a CET 720, a CCA 725, or a periodic fixed subframe following a CCA 725.

[0082] In some aspects, a synchronization signal may be transmitted by the network entity during one or more of the CETs 720, during one or more periodic fixed subframe locations (e.g., following one or more successful CETs 720), and/or during the discovery window 730. A transmission of a synchronization signal during a CET 720 or during a periodic fixed 30 subframe may be considered a synchronous transmission, whereas a transmission of a synchronization signal during the discovery window 730 may be considered an asynchronous transmission. In some examples, a transmitted synchronization signal may be used for cell discovery, synchronization, and/or other purposes. In some examples, a transmitted synchronization signal may include a PSS, and/or an SSS.

[QG83] In some aspects, the network entity may attempt to transmit an opportunistic discovery signal (e.g., one or more CCA 725) during the discovery window 730. In certain instances, the network may be prevented from transmitting CETs 720 and/or the discovery signal transmitted in CET 720 may not be decodable due to interférence. As such, the network entity may transmit one or more CCAs 725, outside of a time period for transmitting thé CET 720, during the discovery window 730, where the one or more CCAs 725 may be discovery signais, such as discovery signal 432 of FIG. 4. The CCAs 725 may include timing information that the UE may use in order to détermine the location of the current subframe in which the discovery signal was transmitted. Based on 10 the timing information, the UE may be able to détermine boundaries of the discovery window 730, and/or boundaries of a discovery period 705 or 710 or 715, and/or boundaries of a radio frame, and as such, synchronize with the network entity and/or cell. Therefore, receiving the CETs 720 are no longer necessary for the UE to be able to properly synchronize with the network entity.

[0®4] FIG. 8 illustrâtes several sample components (represented by corresponding blocks) that may be incorporated into an apparatus 802 (e.g., an access terminal), which may correspond to UE 402 (FIG. 4), which may correspond to UE 402 including subframe component 420 (FIG. 4), and an apparatus 804 and an apparatus 806 (e.g., an access point and a network entity, respectively), where one or both of which may correspond to 20 network entity 404 including subframe component 460 (FIG. 4), to support operations as taught herein. It should be appreciated that these components may be implemented in different types of apparatuses in different implémentations (e.g., in an ASIC, in an SoC, etc.). The described components also may be incorporated into other apparatuses in a communication System. For example, other apparatuses in a System may include 25 components similar to those described to provide similar functionality. Also, a given apparatus may contain one or more of the described components. For example, an apparatus may include multiple transceiver components that enable the apparatus to operate on multiple carriers and/or communicate via different technologies.

[0085] The apparatus 802 and the apparatus 804 each include at least one wireless 30 communication device (represented by the communication devices 808 and 814 (and the communication device 820 if the apparatus 804 is a relay)) for communicating with other nodes via at least one designated radio access technology. Each communication device 808 includes at least one transmitter (represented by the transmitter 810) for transmitting and encoding signais (e.g., messages, indications, information, and so on) and at least one 35 receiver (represented by the receiver 812) for receiving and decoding signais (e.g., messages, indications, information, pilots, and so on). Similarly, each communication device 814 includes at least one transmitter (represented by the transmitter 816) for transmitting signais (e.g., messages, indications, information, pilots, and so on) and at least one receiver (represented by the receiver 818) for receiving signais (e.g., messages, indications, information, and so on). If the apparatus 804 is a relay access point, each communication device 820 may include at least one transmitter (represented by the transmitter 822) for transmitting signais (e.g., messages, indications, information, pilots, and so on) and at least one receiver (represented by the receiver 824) for receiving signais 10 (e.g., messages, indications, information, and so on).

[0086] A transmitter and a receiver may comprise an integrated device (e.g., embodied as a transmitter circuit and a receiver circuit of a single communication device) in some implémentations, may comprise a separate transmitter device and a separate receiver device in some implémentations, or may be embodied in other ways in other 15 implémentations. In some aspects, a wireless communication device (e.g., one of multiple wireless communication devices) of the apparatus 804 comprises a network listen module.

[0087] The apparatus 806 (and the apparatus 804 if it is not a relay access point) includes at least one communication device (represented by the communication device 826 and, 20 optionally, 820) for communicating with other nodes. For example, the communication device 826 may comprise a network interface that is configured to communîcate with one or more network entities via a wire-based or wireless backhaul. In some aspects, the communication device 826 may be implemented as a transceiver configured to support wire-based or wireless signal communication. This communication may involve, for 25 example, sending and receiving: messages, parameters, or other types of information.

Accordingly, in the example of FIG. 8, the communication device 826 is shown as comprising a transmitter 828 and a receiver 830. Similarly, if the apparatus 804 is not a relay access point, the communication device 820 may comprise a network interface that is configured to communîcate with one or more network entities via a wire-based or 30 wireless backhaul. As with the communication device 826, the communication device

820 is shown as comprising a transmitter 822 and a receiver 824.

[0088] The apparatuses 802, 804, and 806 also include other components that may be used in conjunction with communication adaptation operations as taught herein. The apparatus 802 includes one or more processor(s) 456 for providing functionality relating to, for 35 example, communicating with an access point to support communication adaptation as taught herein and for providing other processing functionality. The apparatus 804 includes a processing System 834 for providing functionality relating to, for example, communication adaptation as taught herein and for providing other processing functionality, The apparatus 806 includes one or more processor(s) 482 for providing functionality relating to, for example, communication adaptation as taught herein and for providing other processing functionality. The apparatuses 802, 804, and 806 include memory devices 458,840, and 484 (e.g., each including a memory device), respectively, for maintaining information (e.g., information indicative of reserved resources, thresholds, parameters, and so on). In addition, the apparatuses 802,804, and 806 include user interface devices 844, 846, and 848, respectively, for providing indications (e.g., audible and/or visual indications) to a user and/or for receiving user input (e.g., upon user actuation of a sensing device such a keypad, a touch screen, a microphone, and so on).

[0089] For convenience, the apparatus 802 is shown in FIG. 8 as including components that may 15 be used in the various examples described herein. In practice, the illustrated blocks may hâve different functionality in different aspects.

[0090] The components of FIG. 8 may be implemented in various ways. In some implémentations, the components of FIG. 8 may be implemented in one or more circuits such as, for example, one or more processors and/or one or more ASICs (which may 20 include one or more processors). Here, each circuit may use and/or incorporate at least one memory component for storing information or exécutable code used by the circuit to provide this functionality. For example, some or al! of the functionality represented by blocks 808, 832, 838, and 844 may be implemented by processor and memory component(s) of the apparatus 802 (e.g., by execution of appropriate code and/or by 25 appropriate configuration of processor components). Similarly, some or ail of the functionality represented by blocks 814,820,834,840, and 846 may be implemented by processor and memory component(s) of the apparatus 804 (e.g., by execution of appropriate code and/or by appropriate configuration of processor components). Also, some or ail of the functionality represented by blocks 826, 836, 842, and 848 may be implemented by processor and memory component(s) of the apparatus 806 (e.g., by execution of appropriate code and/or by appropriate configuration of processor components).

[0091] Some of the access points referred to herein may comprise Iow-power access points. In a typical network, low-power access points (e.g., femto cells) are deployed to supplément 35 conventîonal network access points (e.g., macro access points). For example, a low-power access point installed in a user's home or in an enterprise environment (e.g., commercial buildings) may provide voice and high speed data service for access terminais supporting cellular radio communication (e.g., CDMA, WCDMA, UMTS, LTE, etc.). In general, these low-power access points provide more robust coverage and higher throughput for access terminais in the vicinity of the low-power access points.

[0092] As used herein, the term low-power access point refers to an access point having a transmit power (e.g., one or more of: maximum transmit power, instantaneous transmit power, nominal transmit power, average transmit power, or some other form of transmit 10 power) that is less than a transmit power (e.g., as defined above) of any macro access point in the coverage area. In some implémentations, each low-power access point has a transmit power (e.g., as defined above) that is less than a transmit power (e.g., as defined above) of the macro access point by a relative margin (e.g., 10 dBm or more). In some implémentations, low-power access points such as femto cells may hâve a maximum 15 transmit power of 20 dBm or less. In some implémentations, low-power access points such as pico cells may hâve a maximum transmit power of 24 dBm or less. It should be appreciated, however, that these or other types of low-power access points may hâve a higher or lower maximum transmit power in other implémentations (e.g., up to 1 Watt in some cases, up to 10 Watts in some cases, and so on).

[0193] Typically, low-power access points connect to the Internet via a broadband connection (e.g., a digital subscriber line (DSL) router, a cable modem, or some other type of modem) that provides a backhaul link to a mobile operator’s network. Thus, a low-power access point deployed in a user’s home or business provides mobile network access to one or more devices via the broadband connection.

[<HK>4] Various types of low-power access points may be employed in a given system. For example, low-power access points may be implemented as or referred to as femto cells, femto access points, small cells, femto nodes, home NodeBs (HNBs), home eNodeBs (HeNBs), access point base stations, pico cells, pico nodes, or micro cells.

[0095] For convenience, low-power access points may be referred to sîmply as small cells in the 30 discussion that follows. Thus, it should be appreciated that any discussion related to small cells herein may be equally applicable to low-power access points in general (e.g., to femto cells, to micro cells, to pico cells, etc.).

[0096] Small cells may be configured to support different types of access modes. For example, in an open access mode, a small cell may allow any access terminal to obtain any type of 35 service via the small cell. In a restricted (or ctosed) access mode, a small cell may only allow authorized access terminais to obtain service via the small cell. For example, a small cell may only allow access terminais (e.g., so called home access terminais) belonging to a certain subscriber group (e.g., a closed subscriber group (CSG)) to obtain service via the small cell. In a hybrid access mode, alien access terminais (e.g., non-home access terminais, non-CSG access terminais) may be given lîmited access to the small cell. For example, a macro access terminal that does not belong to a small cell’s CSG may be allowed to access the small cell only if suffîcient resources are available for ail home access terminais currently being served by the small cell.

[GC97] Thus, small cells operating in one or more of these access modes may be used to provide indoor coverage and/or extended outdoor coverage. By allowing access to users through adoption of a desired access mode of operation, small cells may provide improved service within the coverage area and potentially extend the service coverage area for users of a macro network.

[G®8] Thus, in some aspects the teachings herein may be employed in a network that includes macro scale coverage (e.g., a large area cellular network such as a third génération (3G) network, typically referred to as a macro cell network or a WAN) and smaller scale coverage (e.g., a residence-based or building-based network environment, typically referred to as a LAN). As an access terminal (AT) moves through such a network, the 20 access terminal may be served in certain locations by access points that provide macro coverage while the access terminal may be served at other locations by access points that provide smaller scale coverage. In some aspects, the smaller coverage nodes may be used to provide incrémental capacity growth, in-buildîng coverage, and different services (e.g., for a more robust user expérience).

[Q®9] In the description herein, a node (e.g., an access point) that provides coverage over a relatively large area may be referred to as a macro access point while a node that provides coverage over a relatively small area (e.g., a résidence) may be referred to as a small cell. It should be appreciated that the teachings herein may be applicable to nodes associated with other types of coverage areas. For ex ample, a pico access point may provide 30 coverage (e.g., coverage within a commercial building) over an area that is smaller than a macro area and larger than a femto cell area. In various applications, other terminology may be used to référencé a macro access point, a small cell, or other access point-type nodes. For example, a macro access point may be configured or referred to as an access node, base station, access point, eNodeB, macro cell, and so on. In some implémentations, a node may be associated with (e.g., referred to as or divided into) one or more cells or sectors. A cell or sector associated with a macro access point, a femto access point, or a pico access point may be referred to as a macro cell, a femto cell, or a pico cell, respectively.

> Γ [ΟβΙΟΟ] FIG. 9 illustrâtes a wireless communication System 900, configured to support a number of users, including one or more access terminais and access points havîng respective subframe components that operate to enable the access terminal to discover and/or synchronize with the access point when the access terminal is operating in a standalone mode in an unlicensed frequency spectrum. The System 900 provides 10 communication for multiple cells 902, such as, for example, macro cells 902A - 902G, with each cell being serviced by a corresponding access point 904 (e.g., access points 9O4A - 904G), which may correspond to network entity 404 including subframe component 460 (FIG. 4). As shown in FIG. 9, access terminais 906 (e.g., access terminais 906A - 906L), whîch may correspond to UE 402 including subframe component 420 15 (FIG. 4), may be dispersed at various locations throughout the System over time. Each access terminal 906 may communicate with one or more access points 904 on a forward Iink (FL) and/or a reverse link (RL) at a given moment, depending upon whether the access terminal 906 is active and whether it is in soft handoff, for example. The wireless communication System 900 may provide service over a large géographie région. For 20 example, macro cells 902A - 902G may cover a few blocks in a neighborhood or several miles in a rural environment.

[00101] FIG. 10 illustrâtes an example of a communication System 1000 where one or more small cells are deployed within a network environment. Specifically, the System 1000 includes multiple small cells 1010 (e.g., small cells 1010A and 1010B), which may 25 correspond to network entity 404 including subframe component 460 (FIG. 4), installed in a relatively small scale network environment (e.g., in one or more user résidences 1030). Each small cell 1010 may be coupled to a wide area network 1040 (e.g., the Internet) and a mobile operator core network 1050 via a DSL router, a cable modem, a wireless link, or other connectivity means (not shown). As will be discussed below, each 30 small cell 1010 may be configured to serve associated access terminais 1020 (e.g., access terminal 1020A) and, optionally, other (e.g., hybrid or alien) access terminais 1020 (e.g., access terminal 1020B), where each access terminal may correspond to network UE 402 including subframe component 420 (FIG. 4). In other words, access to small cells 1010 may be restricted whereby a given access terminal 1020 may be served by a set of 35 designated (e.g., home) small cell(s) 1010 but may not be served by any non-designated small cells 1010 (e.g., a neighbor’s small cell 1010).

[00102] FIG. 11 illustrâtes an example of a coverage map 1100 where several tracking areas 1102 (or routing areas or location areas) are defïned, each of which includes several macro coverage areas 1104. Here, areas of coverage associated with tracking areas 1102 A, 1102B, and 1102C are delineated by the wide lines and the macro coverage areas 1104 are represented by the larger hexagons. The tracking areas 1102 also include femto coverage areas 1106. In this example, each of the femto coverage areas 1106 (e.g., femto coverage areas 1106B and 1106C) is depicted within one or more macro coverage areas

1104 (e.g., macro coverage areas 1104 A and 1104B). It should be appreciated, however, that some or ail of a femto coverage area 1106 might not lie within a macro coverage area 1104. In practice, a large number of femto coverage areas 1106 (e.g., femto coverage areas 1106A and 1106D) may be defined within a given tracking area 1102 or macro coverage area 1104. Also, one or more pico coverage areas (not shown) may be defined within a given tracking area 1102 or macro coverage area 1104.

[00103] Referring again to FIG. 10, the owner of a small cell 1010 may subscribe to mobile service, such as, for example, 3G mobile service, offered through the mobile operator core network 1050. In addition, an access terminal 1020 may be capable of operating both in macro environments and in smaller scale (e.g., résidentiel) network environments. In other words, depending on the current location of the access terminal 1020, the access terminal 1020 may be served by a macro cell access point 1060 associated with the mobile operator core network 1050 or by any one of a set of small cells 1010 (e.g., the small cells 1010A and 1010B that résidé within a corresponding user résidence 1030). For example, when a subscriber is outside his home, he is served by a standard macro access point (e.g., access point 1060) and when the subscriber is at home, he is served by a small cell (e.g., small cell 1010A). Here, a small cell 1010 may be backward compatible with legacy access terminais 1020.

[00104] A small cell 1010 may be deployed on a single frequency or, in the alternative, on multiple frequencies. Depending on the particular configuration, the single frequency or one or more of the multiple frequencies may overlap with one or more frequencies used by a macro access point (e.g., access point 1060).

[00105] In some aspects, an access terminal 1020 may be configured to connect to a preferred small cell (e.g., the home small cell of the access terminal 1020) whenever such connectivity is possible. For example, whenever the access terminal 1020A is within the user's résidence 1030, it may be desired that the access terminal 1020A communicate only with the home small cell 1010A or 1010B.

[00106] In some aspects, if the access terminal 1020 opérâtes within the macro cellular network 1050 but is not residing on its most preferred network (e.g., as defined in a » ’ preferred roaming list), the access terminal 1020 may continue to search for the most preferred network (e.g., the preferred small cell 1010) using a better System reselection (BSR) procedure, which may involve a periodic scanning of available Systems to détermine whether better Systems are currently available and subsequently acquire such preferred Systems. The access terminal 1020 may limit the search for spécifie band and channel. For example, one or more femto channels may be defined whereby ail small cells (or ail restricted small cells) in a région operate on the femto channel(s). The search for the most preferred System may be repeated periodically. Upon discovery of a preferred small cell 1010, the access terminal 1020 selects the small cell 1010 and registers on it for use when within its coverage area.

[ŒJ107] Access to a small cell may be restricted in some aspects. For example, a given small cell may only provide certain services to certain access terminais. In deployments with so-called restricted (or closed) access, a given access terminal may only be served by the macro cell mobile network and a defined set of small cells (e.g., the small cells 1010 that résidé within the corresponding user résidence 1030). In some implémentations, 20 an access point may be restricted to not provide, for at least one node (e.g., access terminal), at least one of: signaling, data access, registration, paging, or service.

[00108] In some aspects, a restricted small cell (which may also be referred to as a Closed Subscriber Group Home NodeB) is one that provides service to a restricted provisioned set of access terminais. This set may be temporarily or permanently extended as 25 necessary. In some aspects, a Closed Subscriber Group (CSG) may be defined as the set of access points (e.g., small cells) that share a common access control list of access terminais.

[00109] Various relationships may thus exist between a given smal 1 cell and a given access terminal. For example, from the perspective of an access terminal, an open small cell may 30 refer to a small cell with unrestricted access (e.g., the small cell allows access to any access terminal). A restricted small cell may refer to a small cell that is restricted in some manner (e.g., restricted for access and/or registration). A home small cell may refer to a small cell on which the access terminal is authorized to access and operate on (e.g., permanent access is provided for a defined set of one or more access terminais). A hybrid 35 (or guest) small cell may refer to a small cell on which different access terminais are provided different levels of service (e.g., some access terminais may be allowed partial and/or temporary access while other access terminais may be allowed full access). An alien small cell may refer to a small cell on which the access terminal is not authorized to access or operate on, except for perhaps emergency situations (e.g., emergency-911 calls).

[00110] From a restricted small cell perspective, a home access terminal may refer to an access terminal that is authorized to access the restricted small cell installed in the résidence of that access terminal’s owner (usually the home access terminal has 10 permanent access to that small cell). A guest access terminal may refer to an access terminal with temporary access to the restricted small cell (e.g., Iimited based on deadline, time of use, bytes, connection count, or some other criterion or criteria). An alien access terminal may refer to an access terminal that does not hâve permission to access the restricted small cell, except for perhaps emergency situations, for example, such as 911 calls (e.g., an access terminal that does not hâve the credentials or permission to register with the restricted small cell).

[00111] For convenîence, the disclosure herein describes various functionality in the context of a small cell. It should be appreciated, however, that a pico access point may provide the same or simïlar functionality for a larger coverage area. For example, a pico 20 access point may be restricted, a home pico access point may be defined for a given access terminal, and so on.

[00112] The teachings herein may be employed in a wireless multiple-access communication System that simultaneously supports communication for multiple wireless access terminais. Here, each terminal may communicate with one or more access points 25 via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the access points to the terminais, and the reverse link (or uplink) refers to the communication link from the terminais to the access points. This communication link may be established via a single-in-single-out System, a multiple-inmultiple-out (ΜΙΜΟ) System, or some other type of System.

[OBI 13] A ΜΙΜΟ System employs multiple (Nr) transmit antennas and multiple (M?) receîve antennas for data transmission. A ΜΙΜΟ channel formed by the Nt transmit and Nr receîve antennas may be decomposed into Ns independent channels, which are also referred to as spatial channels, where Ns < min{A7, Afe). Each of the Ns independent channels corresponds to a dimension. The ΜΙΜΟ System may provide improved 35 performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.

[00114] A ΜΙΜΟ System may support time division duplex (TDD) and frequency division duplex (FDD). In a TDD System, the forward and reverse link transmissions are on the same frequency région so that the reciprocîty principle allows the estimation of the forward link channel from the reverse link channel. This enables the access point to extract transmit beam-forming gain on the forward link when multiple antennas are available at the access point.

[00115] FIG. 12 illustrâtes in more detail the components of a wireless device 1210, which may correspond to network entity 404 including subframe component 460 (FIG. 4), and / a wireless device 1250 (e.g., a UE), which may correspond to UE 402 including subframe component 420 (FIG. 4), of a sample communication system 1200 that may be adapted as described herein. At the device 1210, traffîc data for a number of data streams is provided from a data source 1212 to a transmit (TX) data processor 1214. Each data stream may then be transmitted over a respective transmit antenna.

[00116] The TX data processor 1214 formats, codes, and interleaves the traffîc data for each data stream based on a particular coding scheme selected for that data stream to provide coded data. The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by a processor 482. A data memory 484 may store program code, data, and other information used by the processor 482 or other components of the device 1210.

[00117] The modulation symbols for ail data streams are then provided to a TX ΜΙΜΟ processor 1220, which may further process the modulation symbols (e.g., for OFDM).

The TX ΜΙΜΟ processor 1220 then provides NT modulation symbol streams to NT transceivers (XCVR) 1222A through 1222T. In some aspects, the TX ΜΙΜΟ processor 1220 applies beam-forming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

[00118] Each transceiver 1222 receives and processes a respective symbol stream to provide one or more analog signais, and further conditions (e.g., amplifies, filters, and upconverts) the analog signais to provide a modulated signal suitable for transmission over the ΜΙΜΟ channel. NT modulated signais from transceivers 1222A through 1222T are then transmitted from NT antennas 1224A through 1224T, respectively.

[0(1119] At the device 1250, the transmitted modulated signais are received by NR antennas 1252A through 1252R and the received signal from each antenna 1252 is provided to a respective transceiver (XCVR) 1254A through 1254R. Each transceiver 1254 conditions (e.g., fîlters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to 10 provide a corresponding “received” symbol stream.

[00120] A receive (RX) data processor 1260 then receives and processes the NR received symbol streams from NR transceivers 1254 based on a particular receiver processing technique to provide NT “detected” symbol streams. The RX data processor 1260 then démodulâtes, deinterleaves, and décodés each detected symbol stream to recover the 15 traffic data for the data stream. The processing by the RX data processor 1260 is complementary to that performed by the TX ΜΙΜΟ processor 1220 and the TX data processor 1214 at the device 1210.

[00121] A processor 456 periodicalty détermines which pre-coding matrix to use (discussed below). The processor 456 formulâtes a reverse link message comprising a 20 matrix index portion and a rank value portion. A data memory 458 may store program code, data, and other information used by the processor 456 or other components of the device 1250.

[00122] The reverse link message may comprise various types of information regardîng the communication link and/or the received data stream. The reverse link message is then 25 processed by a TX data processor 1238, which also receives traffic data for a number of data streams from a data source 1236, modulated by a modulator 1280, conditioned by the transceivers 1254A through 1254R, and transmitted back to the device 1210.

[00123] At the device 1210, the modulated signais from the device 1250 are received by the antennas 1224, conditioned by the transceivers 1222, demodulated by a demodulator 30 (DEMOD) 1240, and processed by a RX data processor 1242 to extract the reverse link message transmitted by the device 1250. The processor 482 then détermines which precoding matrix to use for determining the beam-forming weights then processes the extracted message.

[00124] It will be appreciated that for each device 1210 and 1250 the functionalîty of two 35 or more of the described components may be provided by a single component. It will be also be appreciated that the various communication components illustrated in FIG. 12 and described above may be further confîgured as appropriate to perform communication adaptation as taught herein. For example, the processors 482 / 456 may cooperate with the memories 484 / 458 and/or other components of the respective devices 1210 /1250 to perform the communication adaptation as taught herein.

[00125] In some aspects, an apparatus or any component of an apparatus may be configured to (or opérable to or adapted to) provide functionality as taught herein. This may be achieved, for example: by manufacturing (e.g., fabricating) the apparatus or 10 component so that it will provide the functionality; by programming the apparatus or component so that it will provide the functionality; or through the use of some other suitable implémentation technique. As one example, an integrated circuit may be fabricated to provide the requisite functionality. As another example, an integrated circuit may be fabricated to support the requisite functionality and then configured (e.g., via 15 programming) to provide the requisite functionality. As yet another example, a processor circuit may execute code to provide the requisite functionality.

[00126] It should be understood that any reference to an element herein using a des ignation such as “first,” “second, and so forth does not generally limit the quantity or order of those éléments. Rather, these désignations may be used herein as a convenient method of 20 distinguishing between two or more éléments or instances of an element. Thus, a reference to first and second éléments does not mean that only two éléments may be employed there or that the first element must précédé the second element în some manner. Also, unless stated otherwise a set of éléments may comprise one or more éléments. In addition, terminology of the form “at least one of A, B, or C” or “one or more of A, B, or 25 C or “at least one of the group consisting of A, B, and C’ used in the description or the daims means A or B or C or any combination of these éléments.” For example, this terminology may include A, or B, or C, or A and B, or A and C, or A and B and C, or 2A, or 2B, or 2C, and so on.

[00127] Those of skïll in the art will apprecîate that information and signais may be 30 represented using any of a variety of different technologies and techniques. For example, data, instructions, commande, information, signais, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fîelds or particles, optical fields or particles, or any combination thereof.

[0Œ128] Further, those of skill in the art will apprecîate that the various illustrative logïcal blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps hâve been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software dépends upon the particular application and design constraints imposed on the overall System. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implémentation 10 decisions should not be interpreted as causing a departure from the scope of the présent disclosure.

[00129] The methods, sequences and/or algorithms described in connection with the aspects dîsclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may résidé 15 in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be intégral to the processor.

[QK30] Accordingly, an aspect of the disclosure can include a computer readable medium embodying a method for schedulîng a first set of subframes in a frame duration for traffic based at least in part on a first configuration for communications in an unlicensed frequency band; schedulîng, based at least in part on the first configuration, a second set of subframes in the frame duration for détection of a primary user of the unlicensed 25 frequency band (e.g., radar détection); and adjusting a number of subframes in the first and second set of subframes based on a second configuration for communications, wherein the second configuration for communications is identified based on a type of primary user being detected (e.g., radar type). Accordingly, the disclosure is not limited to the illustrated examples.

[QH31] While the foregoing disclosure shows illustrative aspects, it should be noted that various changes and modifications could be made herein without departing from the scope of the disclosure as defined by the appended daims. The functions, steps and/or actions of the method daims in accordance with the aspects of the disclosure described herein need not be performed in any particular order. Furthermore, although certain aspects may 35 be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

Claims (30)

1. What is claimed is:

   1. A method for discovering timing information during wireless communications, comprising:

   monitoring at a user equipment (UE) over an unlicensed radio frequency spectrum band for a discovery signal from a network entity;

   receiving the discovery signal during a subframe from the network entity; and determining a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes timing information corresponding to the current subframe location.
2. 2. The method of claim 1, wherein the discovery signal is received on a downlink control channel from the network entity after a clear channel assessment (CCA) procedure to establish whether a channel of the unlicensed radio frequency spectrum band is available.
3. 3. The method of claim 2, wherein the discovery signal includes an enhanced System information block (eSIB), wherein the eSIB includes the timing information in at least one or more of SIB1, SIB2, and a master information block (MIB).
4. 4. The method of claim 3, further comprising:

   demodulating the downlink control channel; and determining a location of the eSIB within the subframe in response to demodulating the downlink control channel.
5. 5. The method of claim 2, wherein the downlink control channel corresponds to eîther a physical downlink control channel (PDCCH) or an enhanced downlink control channel (ePDCCH).
6. 6. The method of claim 1, wherein the discovery signal includes synchronization information corresponding to a primary synchronization signal (PSS) and a secondary synchronization signal (SSS).
7. 7. The method of claim 1, further comprising determining a radio frame boundary (RFB) based on the current subframe location of the network entity.
8. 8. The method of claim 1, further comprising determining a discovery window and a discovery period based on the current subframe location of the network entity.
9. 9. The method of claim 8, wherein a size of the discovery window and a size of the discovery period are preconfigured.
10. 10. The method of claim 8, wherein the discovery signal is received as a nonperiodic opportunistic signal during the discovery window.
11. 11. An apparatus for discovering timing information during wireless communications, comprising:

    a memory configured to store data, and one or more processors communicativety coupled with the memory, wherein the one or more processors and the memory are configured to:

    monitor at a user equipment (UE) over an unlicensed radio frequency spectrum band for a discovery signal from a network entity;

    receive the discovery signal during a subframe from the network entity; and déterminé a current subframe location of the network entity based on the discovery signal, wherein the discovery signa] includes timing information corresponding to the current subframe location.
12. 12. The apparatus of claim 11, wherein the discovery signal is received on a downlink control channel from the network entity after a clear channel assessment (CCA) procedure to establish whether a channel of the unlicensed radio frequency spectrum band is available.

    F
13. 13. The apparatus of claim 12, wherein the discovery signal includes an enhanced System information block (eSIB), wherein the eSIB includes the timing information in at least one or more of S IB 1, SIB2, and a master information block (MIB).
14. 14. The apparatus of claim 13, wherein the one or more processors and the memory are further configured to:

    demodulate the downlink control channel; and détermine a location of the eSIB within the subframe in response to demodulating the downlink control channel.
15. 15. The apparatus of claim 12, wherein the downlink control channel corresponds to either a physical downlink control channel (PDCCH) or an enhanced downlink control channel (ePDCCH).
16. 16. The apparatus of claim 11, wherein the discovery signal includes synchronizatîon information corresponding to a primary synchronization signal (PSS) and a secondary synchronization signal (SSS).
17. 17. The apparatus of claim 11, wherein the one or more processors and the memory are further configured to détermine a radio frame boundary (RFB) based on the current subframe location of the network entity.
18. 18. The apparatus of claim 11, wherein the one or more processors and the memory are further configured to détermine a discovery window and a discovery period based on the current subframe location of the network entity.
19. 19. The apparatus of claim 18, wherein a size of the discovery window and a size of the discovery period are preconfigured.
20. 20. The apparatus of claim 18, wherein the discovery signal is received as a non-periodic opportunistîc signal during the discovery window.
21. 21. An apparatus for discovering timing information during wireless communications, comprising:

    means for monitoring at a user equipment (UE) over an unlicensed radio frequency spectrum band for a discovery signal from a network entity;

    means for receiving the discovery signal during a subframe from the network entity; and means for determining a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes timing information corresponding to the current subframe location.
22. 22. The apparatus of claim 21, wherein the discovery signal is received on a downlink control channel from the network entity after a clear channel assessment (CCA) procedure to establish whether a channel of the unlicensed radio frequency spectrum band is available.
23. 23. The apparatus of claim 22, wherein the discovery signal includes an enhanced System information block (eSIB), wherein the eSIB includes the timing information in at least one or more of SIB1, SIB2, and a master information block (MIB).
24. 24. The apparatus of claim 23, further comprising:

    means for demodulating the downlink control channel; and means for determining a location of the eSIB within the subframe in response to demodulating the downlink control channel.
25. 25. The apparatus of claim 22, wherein the downlink control channel corresponds to either a physical downlink control channel (PDCCH) or an enhanced downlink control channel (ePDCCH).
26. 26. A computer-readable medium storing computer exécutable code for discovering timing information during wireless communications, comprising:

    code for monitoring at a user equipment (UE) over an unlicensed radio frequency spectrum band for a discovery signal from a network entity;

    code for receiving the discovery signal during a subframe from the network entity; and code for determining a current subframe location of the network entity based on the discovery signal, wherein the discovery signal includes timing information corresponding to the current subframe location.
27. 27. The computer-readable medium of claim 26, wherein the discovery signal is received on a downlink control channel from the network entity after a clear channel assessment (CCA) procedure to establish whether a channel of the unlîcensed radio frequency spectrum band is available.
28. 28. The computer-readable medium of claim 27, wherein the discovery signal includes an enhanced System information block (eSIB), wherein the eSIB includes the timing information in at least one or more of SIB1, S IB 2, and a master information block (MIB).
29. 29. The computer-readable medium of claim 28, further comprising:

    code for demodulating the downlink control channel; and code for determining a location of the eSIB within the subframe in response to demodulating the downlink control channel.
30. 30. The computer-readable medium of claim 27, wherein the downlink control channel corresponds to either a physical downlink control channel (PDCCH) or an enhanced downlink control channel (ePDCCH).