HK1192084A - Hearability improvements for reference signals - Google Patents

Abstract

Systems and methodologies are described that facilitate providing high reuse for transmitting reference signals, such as positioning reference signals (PRS) and cell-specific reference signals (CRS), to improve hearability thereof for applications such as trilateration and/or the like. In particular, PRSs can be transmitted in designated or selected positioning subframes. Resource elements within the positioning subframe can be selected for transmitting the PRSs and can avoid conflict with designated control regions, resource elements used for transmitting cell-specific reference signals, and/or the like. Resource elements for transmitting PRSs can be selected according to a planned or pseudo-random reuse scheme. In addition, a transmit diversity scheme can be applied to the PRSs to minimize impact of introducing the PRSs to legacy devices. Moreover, potions of a subframe not designated for PRS transmission can be utilized for user plane data transmission.

Description

Audibility improvement for reference signals

Related information of divisional application

The scheme is a divisional application. The parent application of the scheme is an invention patent application with the international application number of PCT/US 2010/020271, the application date of the PCT application is 1 month and 6 days 2010, the application number of 201080003887.X is obtained after the PCT application enters the Chinese national stage, and the invention name is 'improvement of the audible capacity aiming at a reference signal'.

Cross referencing

The present application claims the benefit of: united states provisional application No. 61/142,784 entitled "METHOD AND APPARATUS FOR IMPROVING the audibility of a DISCONTINUOUS PILOT SYSTEM" (a METHOD AND APPARATUS FOR IMPROVING the audibility of a DISCONTINUOUS PILOT SYSTEM) filed on 6 th month of 2009, united states provisional application No. 61/144,075 entitled "METHOD AND APPARATUS FOR IMPROVING the audibility of a DISCONTINUOUS PILOT SYSTEM" (a METHOD AND APPARATUS FOR IMPROVING the audibility of a DISCONTINUOUS PILOT SYSTEM) "filed on 12 th month of 2009, united states provisional application No. 61/144,075 entitled" METHOD AND APPARATUS FOR IMPROVING the audibility of a DISCONTINUOUS PILOT SYSTEM "(a METHOD AND APPARATUS FOR IMPROVING the audibility of a DISCONTINUOUS PILOT SYSTEM) (i.e. 61/149,647 th us provisional application No. 2009, 9 th month of 2009 AND APPARATUS FOR IMPROVING the audibility of a DISCONTINUOUS PILOT SYSTEM)" filed on 61/151,128 th month of 2009, United states provisional application No. 61/163,429, filed on 25/3/2009 AND entitled "METHOD AND APPARATUS FOR IMPROVING the audibility of a DISCONTINUOUS PILOT SYSTEM" (a METHOD AND APPARATUS FOR IMPROVING hearing efficiency of a DISCONTINUOUS PILOT SYSTEM), "which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates generally to wireless communications, and more specifically to transmitting reference signals to improve the audibility of the reference signals.

Background

Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. A typical wireless communication system may be a multiple-access system capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access systems may include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, and the like. In addition, the system can conform to specifications such as third generation partnership project (3GPP), 3GPP Long Term Evolution (LTE), Ultra Mobile Broadband (UMB), and so forth.

In general, a wireless multiple-access communication system may simultaneously support communication for multiple mobile devices. Each mobile device may communicate with one or more access points (e.g., base stations, femto cells, pico cells, relay nodes, and/or the like) via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from the access points to the mobile devices, and the reverse link (or uplink) refers to the communication link from the mobile devices to the access points. Additionally, communication between mobile devices and access points may be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth. Further, in a peer-to-peer wireless network configuration, mobile devices can communicate with other mobile devices (and/or access points can communicate with other access points).

An access point in a wireless network may transmit cell-specific reference signals (CRS) to facilitate identifying a cell of the access point; further, the CRS may be utilized to determine the location of one or more mobile devices or other devices using trilateration or similar positioning mechanisms (10-location mechanism). For example, techniques such as observed time difference of arrival (OTDOA) in Universal Mobile Telecommunications System (UMTS) are used to calculate a likely location of a device based, at least in part, on measuring the time difference of a plurality of signals received and/or the location of the transmitter of each signal. Similar techniques in other arts include enhanced observed time difference (E-OTD) in GSM enhanced data rates (EDGE) for global system for mobile communications (GSM) evolved radio access network (GERAN), Advanced Forward Link Trilateration (AFLT) in CDMA2000, and so on.

Furthermore, the art of Idle Period Downlink (IPDL) and time-aligned IDPL (TA-IPDL) in UMTS and Highly Detectable Pilot (HDP) in CDMA2000, for example, improves the audibility of CRS by blanking (e.g., temporarily suspending) transmissions over a particular time period. In IPDL, one or more access points may blank transmissions in different time periods (e.g., subframe slots defined as IPDL periods), allowing devices to measure CRS of access points that are typically strongly interfered with by other access points during periods in which interfering access points blank transmissions. However, because only one interfering access point is blanked in a given IPDL period, the performance gain is limited. In TA-IPDL, the access point may define a similar common time period referred to as a TA-IPDL period. During this period, some access points will blank transmissions while other access points transmit an access point specific pilot, allowing the device to measure this pilot without substantial interference. The HDP concept in CDMA2000 uses the same principles as TA-IPDL. However, TA-IPDL is not always suitable for use in asynchronous networks. Moreover, in IPDL and TA-IPDL, legacy mobile devices (1 aggregation mobile) that are unaware of the time period for blanking and/or transmitting the common pilot may cause data errors. For example, lack of pilots or pilot modification may result in channel estimation errors and/or hybrid automatic repeat/request (HARQ) buffer corruption due to the assumption that pilots are present.

Disclosure of Invention

The following presents a simplified summary of various aspects of the claimed subject matter in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements nor delineate the scope of such aspects. Its sole purpose is to present some concepts of the disclosed aspects in a simplified form as a prelude to the more detailed description that is presented later.

In accordance with one or more embodiments and corresponding disclosure thereof, various aspects are described in connection with facilitating defining a set of time periods for transmitting positioning reference signals at various access points. In particular, an access point may transmit cell-specific reference signals (CRS) in a portion of a time period defined for transmitting these CRS, while other access points blank transmissions over the time period. During disparate portions of a time period reserved for transmitting CRS, one or more access points may transmit Positioning Reference Signals (PRS). In an example, the PRSs can be transmitted by an access point in a scheduled or pseudo-randomly selected time-frequency region (e.g., single or group (consecutive or otherwise) of subframes, slots, resource blocks, sub-bands, etc.) to increase their hearability. Moreover, PRSs can be transmitted by the access point in accordance with one or more transmit diversity schemes to mitigate interference between the PRSs. In an example, a remaining portion of a time period allocated for transmitting CRS (which would otherwise remain blanked by other access points) is leveraged for PRS transmission, allowing devices to receive the PRS without substantial interference. In an example, it should be appreciated that the PRS may be used for trilateration to determine a location of a receiving device.

According to a related aspect, there is provided a method comprising: determining a positioning subframe configured for transmitting PRSs; and selecting one or more resource elements (resources) in the positioning subframe for transmitting PRSs, avoiding resource elements in the positioning subframe configured for transmitting CRS. The method also includes transmitting the PRS in the one or more resource elements.

Another aspect relates to a wireless communications apparatus. The wireless communications apparatus can include at least one processor configured to select a portion of a positioning subframe for transmitting PRS, and determine one or more resource elements in the positioning subframe for transmitting PRS, excluding a plurality of disparate resource elements configured for transmitting CRS. The at least one processor is further configured to transmit the PRS in the one or more resource elements. The wireless communications apparatus also includes a memory coupled to the at least one processor.

Yet another aspect relates to an apparatus. The apparatus comprises: means for determining a positioning subframe configured for transmitting PRSs; and means for selecting one or more resource elements in the positioning subframe for transmitting PRSs and excluding a set of resource elements configured for transmitting CRSs. The apparatus further comprises means for transmitting the PRS in the one or more resource elements.

Yet another aspect relates to a computer program product, which may have a computer-readable medium, the computer-readable medium comprising: code for causing at least one computer to select a portion of a positioning subframe for transmitting PRSs; and code for causing the at least one computer to determine one or more resource elements in the positioning subframe for transmitting PRSs and to exclude a plurality of disparate resource elements allocated for transmitting CRSs. The computer-readable medium can also include code for causing the at least one computer to transmit the PRS in the one or more resource elements.

Moreover, an additional aspect relates to an apparatus, comprising: a special slot selection component that determines positioning subframes configured for transmitting PRSs; and a PRS resource element selecting component that selects one or more resource elements in the positioning subframe for transmitting PRSs, excluding a set of resource elements allocated for transmitting CRSs. The apparatus may further include a PRS transmitting component that transmits the PRS in the one or more resource elements.

According to another aspect, there is provided a method comprising: selecting one or more subframes as one or more positioning subframes for blanking data transmissions; and indicating one or more of the one or more positioning subframes as one or more multicast/broadcast single frequency network (MBSFN) subframes to additionally blank CRS transmissions on the one or more MBSFN subframes.

Another aspect relates to a wireless communications apparatus. The wireless communications apparatus can comprise at least one processor configured to determine one or more subframes as one or more positioning subframes for blanking data transmissions. The at least one processor is further configured to recognize one or more of the one or more positioning subframes as one or more MBSFN subframes to additionally blank CRS transmissions on the one or more MBSFN subframes, and to indicate the one or more MBSFN subframes as MBSFN subframes. The wireless communications apparatus also includes a memory coupled to the at least one processor.

Yet another aspect relates to an apparatus. The apparatus comprises: means for selecting one or more subframes as one or more positioning subframes for blanking data transmissions; and means for determining the one or more positioning subframes as one or more MBSFN subframes. The apparatus further comprises means for indicating the one or more MBSFN subframes as MBSFN subframes.

Yet another aspect relates to a computer program product, which may have a computer-readable medium, the computer-readable medium comprising: code for causing at least one computer to select one or more subframes as one or more positioning subframes for blanking data transmissions. The computer-readable medium may also include: code for causing the at least one computer to indicate the one or more positioning subframes as one or more MBSFN subframes to otherwise blank CRS transmissions on the one or more MBSFN subframes.

Moreover, an additional aspect relates to an apparatus, comprising: a positioning subframe selection component that determines one or more subframes as one or more positioning subframes for blanking data transmissions; and an MBSFN subframe determination component that selects the one or more positioning subframes as one or more MBSFN subframes. The apparatus may further include an MBSFN subframe specification component that indicates the one or more MBSFN subframes as MBSFN subframes.

To the accomplishment of the foregoing and related ends, the one or more embodiments comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the one or more embodiments. These aspects are indicative, however, of but a few of the various ways in which the principles of various embodiments may be employed and the described embodiments are intended to include all such aspects and their equivalents.

Drawings

Fig. 1 is a block diagram of a system for transmitting cell-specific reference signals (CRS) and Positioning Reference Signals (PRS).

Fig. 2 is an illustration of an example communications apparatus for use within a wireless communications environment.

Fig. 3 illustrates an example positioning subframe with resource elements allocated for CRS and PRS transmission.

Fig. 4 illustrates an example positioning subframe with control regions and resource elements allocated for CRS and PRS transmissions.

Fig. 5 illustrates an example location multicast/broadcast single frequency network (MBSFN) subframe.

Fig. 6 illustrates example subband allocations to boost the audibility of PRS transmissions.

Fig. 7 is an illustration of an example communications apparatus for use within a wireless communications environment.

Fig. 8 is a flow diagram of an example method of transmitting PRSs in positioning subframes to improve the audibility of PRSs.

Fig. 9 is a flow diagram of an example method of transmitting PRSs in positioning subframes indicated as MBSFN subframes.

Fig. 10 is a flow diagram of an example method of indicating positioning subframes as MBSFN subframes to control CRS transmission thereon.

Fig. 11 is a flow diagram of an example method of indicating a positioning subframe as an MBSFN subframe and transmitting a CRS-like waveform thereon.

Fig. 12 is a block diagram of an example apparatus that facilitates transmitting PRSs in positioning subframes.

Fig. 13 is a block diagram of an example apparatus that facilitates indicating positioning subframes as MBSFN subframes to control transmission of CRS.

Fig. 14-15 are block diagrams of example wireless communication devices that may be used to implement various aspects of the functionality described herein.

Fig. 16 illustrates an example wireless multiple-access communication system in accordance with various aspects set forth herein.

Fig. 17 is a block diagram illustrating an example wireless communication system in which various aspects described herein may function.

Detailed Description

Various aspects of the claimed subject matter are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more aspects.

As used in this application, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, an integrated circuit, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers. Further, these components can execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).

Moreover, various aspects are described herein in connection with a wireless terminal and/or a base station. A wireless terminal may refer to a device that provides voice connectivity and/or data connectivity to a user. The wireless terminal may be connected to a computing device, such as a laptop computer or desktop computer, or it may be a self-contained device, such as a Personal Digital Assistant (PDA). A wireless terminal can also be called a system, subscriber unit, subscriber station, mobile, remote station, access point, remote terminal, access terminal, user agent, user device, or User Equipment (UE). A wireless terminal may be a subscriber station, wireless device, cellular telephone, PCS telephone, cordless telephone, Session Initiation Protocol (SIP) phone, Wireless Local Loop (WLL) station, Personal Digital Assistant (PDA), handheld device having wireless connection capability, or other processing device connected to a wireless modem. A base station (e.g., an access point or evolved node b (enb)) may refer to a device that communicates over the air-interface, through one or more sectors, with wireless terminals in an access network. The base station may act as a router between the wireless terminal and the rest of the access network, which may include an Internet Protocol (IP) network, by converting received air-interface frames to IP packets. The base station also coordinates management of attributes of the air interface.

Further, the various functions described herein may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc (BD) where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

Various techniques described herein may be used for various wireless communication systems such as Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, single carrier FDMA (SC-FDMA) systems, and others. The terms "system" and "network" are often used interchangeably herein. A CDMA system may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, and so on. UTRA includes wideband CDMA (W-CDMA) and other variants of CDMA. In addition, CDMA2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA system may implement a radio technology such as global system for mobile communications (GSM). OFDMA systems may implement, for example, evolved UTRA (E)UTRA), Ultra Mobile Broadband (UMB), IEEE802.11(Wi-Fi), IEEE802.16(WiMAX), IEEE802.20, Flash-And so on. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) is an upcoming release that uses E-UTRA, which uses OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, and GSM are described in documents from an organization named "third Generation partnership project" (3 GPP). In addition, CDMA2000 and UMB are described in documents from an organization named "third generation partnership project 2" (3GPP 2).

Various aspects will be presented in terms of systems that may include a number of devices, components, modules, and the like. It is to be understood and appreciated that the various systems may include additional devices, components, modules, etc. and/or may not include all of the devices, components, modules etc. discussed in connection with the figures. Combinations of these methods may also be used.

Referring now to the drawings, fig. 1 illustrates an example wireless network 100 that facilitates transmitting cell-specific reference signals (CRS) and Positioning Reference Signals (PRS). Wireless network 100 includes an access point 102 that can provide wireless network access to one or more devices. For example, access point 102 may be an access point, such as a macrocell access point, femtocell or picocell access point, an eNB, a mobile base station, a portion thereof, and/or virtually any device that provides access to a wireless network. Further, the wireless network 100 includes a wireless device 104 that receives access to the wireless network. For example, the wireless device 104 may be a mobile device, such as a UE, a portion thereof, and/or virtually any device that receives access to a wireless network. It is to be appreciated that the components shown and described in access point 102 can be present in wireless device 104 and/or vice versa, in an example, to facilitate the functionality described below.

Access point 102 may include: a CRS scheduling component 106 that determines one or more time periods for scheduling CRS transmissions; a PRS scheduling component 108 that selects one or more time periods for transmitting PRSs; a muting component 110 that distinguishes one or more time periods in which data transmission is to be ceased; and a transmitting component 112 that transmits CRS and/or PRS and suspends transmissions over silent time periods. The wireless device 104 includes: a CRS receiving component 114 that obtains one or more CRSs for one or more access points during a particular time period; and a PRS receiving component 116 that determines one or more PRSs received during a portion of a particular time period at which one or more CRSs are received.

According to an example, the CRS scheduling component 106 may select a portion of a time period for transmitting the CRS. This may be defined, for example, according to a standard, network specification, configuration, hard coding, received variables, and/or the like. In an example, the CRS scheduling component 106 may select similar portions of a number of time periods for transmitting the CRS, such as one or more portions of a subframe or subframes, which may be continuous or discontinuous. The transmitting component 112 may transmit the CRS in the portion of the time period. Moreover, the PRS scheduling component 108 may select disparate portions, such as one or more subframes, in one or more of the time periods for additionally transmitting PRSs. In an example, the PRS scheduling component 108 may select one or more time periods according to a pseudo-random or programmatic selection function (selection function), which may be based on a standard, network specification, configuration, hard coding, and/or the like. Further, for example, one or more time periods may be substantially consistent among one or more access points.

Similarly, the PRS scheduling component 108 may select disparate portions of one or more of the time periods as follows: according to standards, network specifications, configurations, hard coding, etc.; pseudo-randomly according to a standard, network specification, configuration, hard coding, etc.; using one or more sequences, such as a pseudo-random binary sequence, followed by Quadrature Amplitude Modulation (QAM), such as Quadrature Phase Shift Keying (QPSK), or using sequences that facilitate detectability, such as Zadoff-Chu sequences, Walsh sequences, and/or the like; using a sequence formed by encoding the payload (e.g., using a low reuse preamble); and so on. Moreover, transmit component 112 can transmit PRSs using one or more disparate transmit diversity schemes (e.g., Precoding Vector Switching (PVS), small Cyclic Delay Diversity (CDD), etc.) to minimize receiver impact due to the introduction of one or more time periods and PRSs. Further, in this aspect, transmit component 112 may transmit PRSs (and CRSs) over a single antenna port (or a single virtual antenna over multiple physical antennas) using one or more transmit diversity schemes.

Further, transmitting component 112 can transmit PRSs over disparate portions of one or more time periods. The muting component 110 can suspend transmissions by the access point 102 for a remaining portion of the one or more time periods selected by the PRS scheduling component 108. The CRS receiving component 114 may obtain a CRS transmitted by the access point 102 for identifying, for example, the access point, and a PRS for utilization in trilateration positioning of the wireless device 104. In this example, by transmitting PRSs in available portions of one or more time periods, the audibility is improved for wireless devices because other interfering access points may be silent when PRSs for disparate access points are transmitted, but may still transmit CRS. This may also ensure correct channel estimation for legacy device support.

According to an example, wireless network 100 can be an LTE network such that access point 102 and wireless device 104 communicate according to an LTE standard. An LTE system may be an Orthogonal Frequency Division Multiplexing (OFDM) system in which data is communicated in 1 millisecond (ms) subframes. A subframe may be defined as a portion (e.g., 1ms) of frequency over time (frequency over time). For example, a subframe may include a number of contiguous or non-contiguous OFDM symbols that are part of frequency in time and may be divided into smaller resource elements that represent a number of frequency carriers over an OFDM symbol. For example, consecutive resource elements on an OFDM symbol may be referred to as resource blocks. Furthermore, each subframe may have, for example, two slots, which are thus also defined by a number of OFDM symbols and/or resource elements thereof, with control data being transmitted over a portion of the first slot (over one or more OFDM symbols) and user-plane data being transmitted over the remaining portion of the first slot and the entire second slot.

In this example, in accordance with the LTE specification, CRS scheduling component 106 may schedule multiple CRSs (e.g., 2 CRSs) for transmission in each slot, the multiple CRSs being transmitted on multiple resource elements. For example, CRS receiving component 114 may obtain CRS for data demodulation purposes, for cell-specific measurements in cell selection/reselection and handover, and so on. In addition, however, the PRS scheduling component 108 may select a particular time slot for transmitting PRSs, which may be a particular time-frequency region. As described, this can be in accordance with the LTE specification, which can define special timeslots using an Idle Period Downlink (IPDL), a time-consistent IDPL (TA-IPDL), a Highly Detectable Pilot (HDP), or similar scheme. In this regard, the special time slots may be different for each access point (e.g., selected according to a pseudo-random scheme), substantially time-consistent special time slots that are similar across access points, and/or the like. Further, the special time slot may be a second time slot of the respective subframe (e.g., in an LTE configuration) so as not to interfere with control data transmission in the first time slot, and/or the special time slot may be a portion of the first time slot of the respective subframe that is not used for transmitting control data.

The PRS scheduling component 108 may select one or more resource elements as frequency regions of a particular slot for transmitting PRSs related to the access point 102 over which CRSs are not transmitted. Although not shown in the figure, other access points may also select one or more resource elements for transmitting PRSs. In this regard, in an example, as described, the PRS scheduling component 108 can schedule PRSs according to one or more sequences (e.g., Zadoff-Chu sequences, Walsh sequences, QPSK sequences, etc.) that facilitate detectability and/or mitigate interference. Additionally, as shown above, in an example, transmitting component 112 can transmit PRSs in resource elements of a particular slot, and can do so using transmit diversity such as PVS, CDD, and so forth. In an example, the PRS receiving component 116 can obtain the PRS for the access point 102 and the wireless device 104 can perform trilateration or another positioning algorithm. Moreover, PRS receiving component 116 can receive PRSs of one or more disparate access points, for example, in a special time slot for transmitting PRSs where PRSs of access point 102 are not received. Alternatively or additionally, these PRSs may be used in trilateration and the like.

Further, the muting component 110 can ensure that transmissions are aborted for remaining resource elements in a particular slot; thus, access point 102 does not transmit data or any signal other than the aforementioned CRS (which may be mandatory) and PRS (which may be optional on a pseudo-random basis) in a particular slot. It should be appreciated, however, that a portion of a particular slot (rather than the entire slot) can be used for transmitting PRSs, within which portion the muting component 110 ensures that transmissions are suspended for the remainder of the particular slot and not necessarily for the entire remaining slot.

Referring next to fig. 2, a communication device 200 that may participate in a wireless communication network is illustrated. The communication apparatus 200 can be an access point, a mobile device, a portion thereof, or virtually any device that receives communications in a wireless network. The communication device 200 may include: a special slot selection component 202 that determines one or more slots or subframes (or other time/frequency regions) for transmitting one or more PRSs, which may be referred to as positioning subframes when a special slot includes one subframe; a PRS resource element selection component 204 that distinguishes one or more resource elements within a particular slot for transmitting one or more PRSs; a PRS transmit diversity component 206 that applies a transmit diversity scheme to one or more PRSs to facilitate distinguishing PRSs of various communication apparatuses; a PRS transmitting component 208 that may communicate PRSs in selected slots on selected resource elements using selectable transmit diversity; and a data scheduling component 210 that can select resources for communicating user-plane data in a wireless network.

According to an example, special slot selection component 202 can determine one or more special slots and/or related subframes for transmitting PRSs (e.g., and blanking data transmissions). In an example, the special time slots or positioning subframes may be defined in a network specification or standard, and the special time slot selection component 202 selects the special time slots or positioning subframes based on the standard, network specification, hard coding, configuration, and/or the like. Alternatively or additionally, special timeslot selection component 202 may select a timeslot as one or more timeslots reserved for IPDL, TA-IPDL, HDP, or the like.

For example, IPDL may be used in an asynchronous network such that IPDL time slots (e.g., time slots blanked at a respective communication device) are selected pseudo-randomly or according to a pattern to facilitate diversity in blanking IPDL time slots. In another example, TA-IPDL or HDP can be used in a synchronous network such that TA-IPDL or HDP timeslots are substantially consistent at the communications device. As previously described, in TA-IPDL or HDP, some communication devices in a set transmit pilots in TA-IPDL timeslots while the remaining communication devices in the set blank transmissions in the timeslots. In an example, determining which communication devices transmit and which are blanked may additionally be assigned pseudo-randomly or according to a planned deployment based on standards, network specifications, hard coding, configuration, and so forth, which may be based on identifiers of communication devices and/or the like.

In another example, special time slot selection component 202 can determine one or more time slots based at least in part on a standard, a network specification, hard coding, configuration, communication received from a wireless network or related device, and/or the like. For example, special slot selection component 202 can receive slot information from one or more communication apparatuses (e.g., over a backhaul link), detect CRS transmissions from one or more communication apparatuses, and select a slot in which CRS is detected for transmission of PRSs, and/or the like. Further, as described, in an example, the special slot selecting component 202 can select a second slot of a respective positioning subframe for transmitting PRSs. Alternatively or additionally, the special slot selecting component 202 can select a portion of the first slot that excludes the control channel portion used to transmit PRSs. Further, the special slot selection component 202 can select a portion of a slot for transmitting PRSs. In addition, the special slot selecting component 202 can select a set of consecutive positioning subframes for transmitting PRSs.

Similarly, the PRS resource element selection component 204 may determine one or more resource elements within one or more special slots for transmitting PRSs. As described in further detail below, the PRS resource element selection component 204 may select resource elements according to a PRS pattern. As described, the PRS resource element selection component 204 can determine resource elements according to a pseudo-random selection function (e.g., based on a cell identifier of a cell of the communication apparatus 200) and/or according to a programmatic selection function. In any case, in an example, the PRS resource element selection component 204 may retrieve a selection function for determining a PRS pattern based on a standard, a network specification, hard coding, configuration, and/or the like. By selecting time slots that are muted relative to data transmission and CRS and using the remaining resources of the time slots with a reuse scheme, the audibility of PRSs is improved over otherwise muted resource elements in a subframe.

Upon selecting one or more special time slots and related resource elements, PRS transmit diversity component 206 may optionally apply a transmit diversity scheme to the PRS. For example, PVS, small CDD, and/or the like may be applied to the PRS to minimize the standard and receiver impact caused by the introduction of PRS and positioning subframes or slots. In another example, a non-transparent diversity scheme may also be utilized. For example, this allows the PRS transmitting component 208 to transmit PRSs via a single antenna port (or a single virtual antenna port on multiple physical antennas). In either case, for example, PRS transmit diversity component 206 may additionally signal necessary information (e.g., delays between different transmit antennas in the CDD) to the receiving device. In another example, PRS transmit diversity component 206 may apply a diversity scheme that uses different sets of tones for transmitting disparate PRSs. Thus, for example, a set of tones can be selected by the PRS transmit diversity component 206 for transmitting a first PRS, and the PRS transmit diversity component 206 can select a disparate set of tones for transmitting a subsequent PRS.

In any case, PRS transmitting component 208 may transmit PRSs in selected resource elements of a selected slot (or portion thereof) according to one or more transmit diversity schemes, if any. Moreover, because the communication apparatus 200 does not transmit other data in the selected time slot (or portion thereof), the PRS transmitting component 208 can increase the energy of the PRS or reshape its spectrum. Further, data scheduling component 210 can select one or more resources for transmitting user-plane data for communication apparatus 200. In this example, the data scheduling component 210 can avoid scheduling data on the time slot (or portion thereof) selected for transmitting PRSs so as not to interfere with PRSs. As described, this allows a receiving device to receive and measure PRSs without significant interference from surrounding communication equipment.

In another example, to introduce the functionality described herein in a backward compatible manner, the PRS transmitting component 208 may indicate a selected slot or related subframe as being allocated for multicast/broadcast single frequency network (MBSFN) signals. In this regard, a previous version of the wireless device (e.g., LTE release 8UE) may avoid the non-control region of the MBSFN subframe. Thus, assuming that CRS is not transmitted in the non-control region of MBSFN subframes, these legacy devices will not attempt to process CRS. For example, MBSFN subframes may be designated as positioning subframes for transmitting PRSs, and may have a high value periodicity (e.g., 80/160/320 ms). Moreover, the physical control region and Cyclic Prefix (CP) of the control region and non-control region may be the same as the physical control region and Cyclic Prefix (CP) in MBSFN subframes of the mixed carrier to facilitate indicating subframes as MBSFN and indicating detected subframes as MBSFN subframes by legacy devices. However, as described, other wireless devices may be aware of the use of MBSFN indicated subframes for transmitting PRS, and may thus utilize PRS.

Referring now to fig. 3, an example positioning subframe 300 in a wireless network is illustrated. For example, as described, the positioning subframe 300 may be an OFDM subframe. The positioning subframe 300 may be a subframe (e.g., a 1ms or similar subframe) in an LTE system that is communicated to one or more wireless devices by an access point. For example, as described herein, an access point (not shown in the figures) in a wireless network may conceal user-plane data transmission on positioning subframes 300.

The positioning subframe 300 includes two slots 302 and 304, each of which includes a number of resource elements. As described, in a first slot of a given subframe in LTE, control data may be transmitted over a portion of the resource elements (e.g., over one or more initial OFDM symbols). In this regard, CRS may be transmitted by various access points in resource elements 306 and similarly patterned resource elements in the first slot 302, optionally also transmitting control data (not shown). User-plane data transmissions by a given access point may be suspended on remaining resource elements of a slot to allow reception of CRS without substantial interference from other transmissions.

In slot 304, PRSs may be transmitted by various access points at resource elements 308 and similarly patterned resource elements in slot 304. In this regard, the slot 304 may be a special slot selected for transmitting PRSs. Furthermore, the PRS does not interfere with control data transmissions. Moreover, by transmitting PRSs in otherwise muted resource elements with the access point, the audible capability of PRSs is improved. As described, PRS resource elements 308 and similarly patterned resource elements in a slot 304 may be collectively defined as a PRS pattern. As depicted, the PRS pattern may be a diagonal pattern assigned by the access point for transmitting PRSs. In this regard, for example, an access point may utilize different subcarriers in different OFDM symbols to transmit PRSs in addition to the OFDM symbols used to transmit CRS in the depicted example. In an example, nearly all of the subcarriers in a resource block (or slot 304) are used over the duration of the slot 304. This ensures that the channel estimates provided by PRS have the largest possible length and mitigates ambiguity (ambiguities) regarding cyclic shifts. In an example, using different subcarriers forming a diagonal pattern in an OFDM symbol is one way to utilize nearly all of the subcarriers in a resource block.

According to an example, PRS patterns can be assigned according to standards or network specifications, which can be hard coded in access point implementations, configurations, and the like. Further, in addition to being a diagonal pattern, the PRS pattern may use roughly the following configuration: the configuration is such that a PRS is transmitted in each OFDM symbol of a special slot and/or positioning subframe (except for OFDM symbols reserved for CRS transmission) in order to maximize the energy contained in the PRS and fully utilize the access point transmit power. In an example, the resource elements may be included within the same subcarrier in consecutive OFDM symbols used to transmit PRSs. In other examples, such as the depicted example, shifts (diagonal, random, pseudo-random, or otherwise) may be applied to the subcarriers at each OFDM symbol to provide a degree of diversity and to ensure that the channel estimates have little uncertainty regarding the cyclic shift. Further, for example, the resource elements selected for the PRS pattern may have a periodicity and structure similar to the periodicity and structure of the resource elements selected for the CRS pattern.

In this example or an alternative example, the PRS patterns may be assigned to the access points or cells thereof according to a planned and/or pseudo-random reuse scheme. In either case, for example, the PRS pattern may be assigned based at least in part on an identifier of the access point, e.g., a Physical Cell Identifier (PCI) of a cell provided by the access point. Further, for example, the PRS sequence assigned to the access point can be selected as a Zadoff-Chu sequence, a Walsh sequence, or the like that facilitates detection of the PRS sequence after transmission of the PRS. Moreover, as described, PRSs can be energy boosted or spectrally reshaped in selected resource elements to further improve audibility (e.g., because the respective access point did not otherwise transmit in the time slot).

As depicted, in positioning subframe 300, CRS is transmitted as in other subframes for legacy support and/or identification of related cells. Further, data is not transmitted in the positioning subframe (although data may be transmitted, for example, if it is important information, such as pre-scheduled broadcast information, etc.). This mitigates interference from surrounding access points, improving the audibility of the PRS, which may enhance application of trilateration or other device positioning algorithms, for example. As described, it should be appreciated that user-plane data can be transmitted by one or more access points in portions of a subframe not used for transmitting PRSs and/or CRSs (and/or control data). Furthermore, the PRS are not embedded within the CRS so as not to interfere with current applications that utilize the CRS (e.g., channel estimation and measurement algorithms, etc.). In this regard, PRSs with increased audibility are provided to enhance trilateration or similar skills without interfering with legacy skills.

Turning to fig. 4, example positioning subframes 400 and 402 transmitted by an access point having multiple antennas in a wireless network are illustrated. For example, as described, positioning subframes 400 and 402 may be OFDM subframes. Positioning subframes 400 and 402 may be subframes (e.g., 1ms or similar subframes) in an LTE system that are communicated to one or more wireless devices by an access point. In an example, positioning subframe 400 may represent a subframe transmitted with normal CP and positioning subframe 402 may represent a subframe transmitted with extended CP. Thus, for example, positioning subframe 400 may include 7 OFDM symbols per slot, while positioning subframe 402 includes 6 OFDM symbols per slot. Further, in an example, an access point (not shown in the figures) in a wireless network can conceal user-plane data transmission on positioning subframes 400 and/or 402, as described herein.

The positioning subframe 400 includes two slots 404 and 406. As described, in a first slot of a given subframe in LTE, control data may be transmitted over a portion of the resource elements (e.g., over one or more initial OFDM symbols). Thus, the OFDM symbols represented at 408 may be reserved for control data, which may include CRSs shown transmitted at resource elements 410 and similarly patterned resource elements within and outside of control region 408. Additionally, as depicted, resource elements outside the control region (e.g., resource element 412 and similarly patterned resource elements) can also be used to transmit PRSs; as described, the resource elements may be collectively referred to as a PRS pattern. Further, the PRS pattern may be a diagonal or other shifted pattern over consecutive OFDM symbols. As illustrated, the PRS pattern utilizes subcarriers of nearly all OFDM symbols in a particular slot (except for OFDM symbols in the control region 408) for transmitting the PRS for an access point. It should be appreciated, however, that other modes may be utilized that utilize different subcarriers (e.g., or one or more shifted subcarriers) on nearly all OFDM symbols of a particular slot (except for OFDM symbols in control region 408) as resource elements, as previously described. In this aspect, resource elements in slots 404 and 406 are reserved for transmitting PRSs as long as the resource elements are outside of control region 408 and do not interfere with CRS resource elements and similar patterned CRS resource elements at 410.

Further, the positioning subframe 402 includes two slots 414 and 416. As described, in a first slot of a given subframe in LTE, control data may be transmitted over a portion of the resource elements (e.g., over one or more initial OFDM symbols). Thus, the OFDM symbols represented at 418 may be reserved for control data, which may include CRSs shown transmitted at resource elements 420 and similarly patterned resource elements within and outside of control region 418. In addition, as depicted, resource elements outside the control region (e.g., resource element 422 and similarly patterned resource elements) can also be utilized to transmit PRSs, which represent PRS patterns for access points. In this aspect, resource elements in slots 414 and 416 are reserved for transmitting PRSs as long as the resource elements are outside of control region 418 and do not interfere with CRS resource elements and similar patterned CRS resource elements at 420.

Thus, in either example, the PRS pattern does not interfere with control data transmissions. Moreover, as described, by transmitting PRSs in originally muted resource elements with an access point, the audibility of PRSs is improved. As described, resource elements 412 and 422 and similarly patterned resource elements can be assigned to access points in various manners. For example, resource elements may be assigned according to a standard or network specification, which may be hard coded in an access point implementation. In this example or an alternative example, the resource elements can be assigned to the access point or its cell according to a planned and/or pseudo-random reuse scheme.

In the case where the reuse scheme is planned, in an example, the access points or related cells can be grouped into clusters, where each cluster is assigned common resources for transmitting PRSs. In either case, for example, resource elements can be assigned based at least in part on an identifier of an access point (e.g., via a PCI of a cell provided by the access point) and/or the like. Further, for example, the sequences transmitted on the resource elements can be assigned to the access point according to a sequence such as a Zadoff-Chu sequence, a Walsh sequence, or similar sequence that facilitates detection thereof. Moreover, as described, PRSs can be energy boosted or spectrally reshaped in selected resource elements to further improve audibility (e.g., because the respective access point did not otherwise transmit in the time slot).

As depicted, in positioning subframes 400 and 402, CRS is transmitted as in the other subframes for legacy support and/or identification of related cells. Moreover, data is not transmitted in positioning subframes (at least not in the portion used to transmit PRSs). This mitigates interference from surrounding access points, improving the audibility of the PRS, which may enhance application of trilateration or other device positioning algorithms, for example. As described, it should be appreciated that user-plane data can be transmitted by one or more access points in portions of a subframe not used for transmitting PRSs and/or CRSs (and/or control data). Furthermore, the PRS are not embedded within the CRS so as not to interfere with current applications that utilize the CRS (e.g., channel estimation and measurement algorithms, etc.). In this regard, PRSs are provided to enhance trilateration or similar skills without interfering with legacy skills.

Referring now to fig. 5, an example positioning subframe 500 in a wireless network is illustrated. For example, as described, positioning subframe 500 may be an OFDM subframe. The positioning subframe 500 may be an MBSFN subframe (e.g., a 1ms or similar subframe) communicated by an access point to one or more wireless devices in an LTE system according to the MBSFN specification. The positioning subframe 500 includes two slots 502 and 504. As described, in the first slot of a given subframe in LTE, control data may be transmitted over the portion of the subframe as indicated by region 506 (e.g., over one or more initial OFDM symbols). In this aspect, CRS may be transmitted by various access points in resource elements 508 in the first time slot 502 and similarly patterned resource elements along with control data in region 506.

Because the positioning subframe 500 is indicated as an MBSFN subframe, legacy devices may receive CRS transmitted in the control region 506 at resource elements 508 and similarly patterned resource elements in the same OFDM symbol, and legacy devices may ignore the remainder of the positioning subframe 500 because it is an MBSFN subframe. An access point may transmit PRSs in the slot 502 and the remainder of the slot 504 (indicated at resource element 510 and similar patterned resource elements), including PRS patterns, and devices equipped to process PRSs may receive and process PRSs to perform trilateration or similar functionality. This minimizes confusion of legacy devices that may result from the introduction of PRSs, and also improves the audibility of PRSs by transmitting in timeslots or related subframes in which transmissions from other access points are substantially blanked. Moreover, as described, utilizing a PRS pattern (e.g., the illustrated diagonal pattern) that occupies subcarriers in nearly all OFDM symbols (avoiding the control region 506) can improve channel estimation for PRS in MBSFN subframes.

As described, resource elements 510 and similar patterned resource elements can be assigned to an access point in various manners for transmitting PRSs. For example, resource elements may be assigned according to a standard or network specification, which may be hard-coded in an access point implementation, configuration, and/or the like. In this example or an alternative example, the resource elements can be assigned to the access point or its cell according to a planned and/or pseudo-random reuse scheme. In either case, for example, the resource elements can be assigned based at least in part on an identifier of the access point (e.g., a PCI of a cell provided by the access point), and/or the like. Further, for example, the sequences transmitted on the resource elements can be assigned to the access point according to sequences such as Zadoff-Chu sequences, Walsh sequences, or similar sequences that facilitate detection thereof. Moreover, as described, PRSs can be energy boosted or spectrally reshaped in selected resource elements to further improve audibility (e.g., because the respective access point did not otherwise transmit in the time slot).

Turning to fig. 6, example frequency portions 600, 602, and 604 are shown representing PRS resource element selection schemes. For example, frequency portions 600, 602, and 604 may represent allocations of a plurality of sub-bands (including, e.g., a plurality of consecutive resource blocks) in one or more PRS slots selected or otherwise reserved for transmission of PRSs by one or more access points in a wireless network. Further, although a particular number of subbands are shown in frequency portions 600, 602, and 604, it should be appreciated that frequency portions 600, 602, and 604 may include more or less subbands than the depicted subbands.

According to an example, frequency portion 600 may comprise subbands reserved for PRS/CRS transmission as well as data transmission. In this example, numerically labeled subbands (such as subbands 606, 608, and 610, and subbands with similar numbers) are reserved for transmitting PRSs through the first, second, and third groups of access points, respectively. In this regard, a sub-band corresponding to the sub-band labeled with a number 1 (which includes the sub-band 606 and other sub-bands labeled with a number 1) may be assigned to an access point for transmitting PRSs in a PRS slot. Further, disparate access points can be assigned sub-bands corresponding to numerical labels 2 and 3 (e.g., sub-bands 608 and 610, respectively, and similarly numbered sub-bands) for transmitting PRSs.

In an example, as described, assignments can be made to access points in accordance with one or more reuse schemes. Further, one or more access points may transmit data (e.g., Physical Data Shared Channel (PDSCH) data) on a sub-band labeled D, such as sub-band 612 and similarly labeled sub-bands. Furthermore, it should be appreciated that additional groups of subbands reserved for transmitting PRSs may be supported, but only 3 groups of subbands are shown for purposes of explanation. Moreover, nearly any ordering of the subbands is possible and/or may be modified according to a number of factors such as a planning scheme, a reuse scheme, pseudo-random allocations, and/or the like. In another example, subbands used for a particular purpose may be contiguous; thus, for example, a sub-band with numeral 1 may be contiguous, followed by a sub-band with numeral 2, and so on.

In another example, frequency portions 602 and 604 illustrate examples where the bandwidth of the carrier is greater than required for time resolution capability. In this regard, frequency portions 602 and 604 may comprise guard bands 614 between contiguous subbands reserved for similar types of transmissions. Thus, for example, as shown, frequency portion 602 may not include data transmission subbands, but only subbands used for transmitting PRS/CRS, such as the subband represented by numeral designation 1 including subband 606, the subband represented by numeral designation 2 including subband 608, and the subband represented by numeral designation 3 including subband 610. Guard band 614 and the unmarked similar subbands separate the subbands to facilitate independent reception of the subbands without significant interference leakage from the respective group of subbands.

Frequency portion 604 may include multiple groups of subbands reserved for data (e.g., subband 612 and other subbands labeled D) and one or more subbands used for transmitting PRS/CRS (e.g., subband 606 and other subbands labeled 1). Similarly, groups of subbands in frequency portion 604 may be separated by guard bands 614 to facilitate independent reception of signals transmitted in the groups of subbands, as the guard bands provide separation that mitigates leakage (and thus mitigates interference) between the frequency bands. It should be appreciated that additional configurations are possible; frequency portions 600, 602, and 604 are only 3 examples of allocating subbands in a slot selected for transmission of PRSs to mitigate interference between PRSs and/or data transmitted in the selected slot.

Referring next to fig. 7, a communication device 700 that may participate in a wireless communication network is illustrated. The communication apparatus 700 can be an access point, a mobile device, a portion thereof, or virtually any device that receives communications in a wireless network. The communication device 700 may include: a positioning subframe selection component 702 that determines one or more subframes to be subframes for transmitting CRS; an MBSFN subframe determining component 704 that distinguishes one or more subframes as MBSFN subframes; an MBSFN subframe specification component 706 that may indicate a subframe as an MBSFN subframe; and a transmitting component 708 that can transmit data and/or CRS in one or more subframes.

According to an example, as described, positioning subframe selection component 702 can select one or more subframes for transmitting CRS according to a network specification, configuration, hard coding, or the like, or according to a fixed or pseudo-random pattern, and/or the like. In this regard, the transmitting component 708 may generally blank data transmissions and transmit CRS in the selected positioning subframe. Moreover, however, the MBSFN subframe determining component 704 may select one or more of the positioning subframes to indicate as MBSFN subframes to mitigate CRS transmission in MBSFN indicated subframes. This mitigates interference to other devices (not shown) transmitting CRS in the subframe, which provides a degree of reuse for CRS transmission. In this manner, the MBSFN subframe determining component 704 may select the positioning subframe as the MBSFN subframe to increase reuse according to one or more factors. For example, MBSFN subframe determining component 704 may receive an indication from an underlying wireless network (not shown) that a subframe is MBSFN, determine a subframe according to a planned or pseudo-random pattern (which may be received according to a specification, configuration, hard coding, etc.), and/or the like. For example, MBSFN subframe specification component 706 may indicate the subframe as MBSFN, allowing a receiving device to receive other CRSs without attempting to decode CRSs from communication apparatus 700. Further, transmitting component 708 can blank data transmissions and transmit CRS in positioning subframes selected by positioning subframe selection component 702 that were not determined by MBSFM subframe determination component 704 to be MBSFN subframes.

In another example, the MBSFN subframe determining component 704 may discern that substantially all subframes selected as positioning subframes by the positioning subframe selecting component 702 are MBSFN subframes to blank CRS transmission on the subframes. In this regard, the transmitting component 708 and similar components of other apparatuses may select MBSFN subframes for transmitting CRS-like waveforms and blanking data transmissions according to a planned or pseudo-random pattern and/or the like. As described, this increases the reuse factor of CRS (or similar waveforms), improving the audibility of CRS (or similar waveforms) over multiple subframes by some devices (e.g., LTE-a devices), while other devices (e.g., LTE release 8 devices) do not process CRS-like waveforms because CRS is not desired in MBSFN subframes.

Referring now to fig. 8-11, methodologies that may be implemented in accordance with various aspects set forth herein are illustrated. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts, it is to be understood and appreciated that the methodologies 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, those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a methodology in accordance with one or more aspects.

Referring to fig. 8, an example method 800 for transmitting PRSs in a portion of a positioning subframe is illustrated. At 802, a positioning subframe for transmitting a PRS may be determined. In an example, such an action can include determining a portion of a positioning subframe (e.g., a slot or a portion thereof) allocated for PRS transmission, which can be determined based on a standard, network specification, configuration, hard coding, and/or the like. As described, a positioning subframe may comprise a plurality of resource elements, a portion of which may be reserved for CRS and/or control data transmission. At 804, one or more resource elements in a positioning subframe that are not allocated for CRS transmission may be selected for transmitting PRSs. As described, one or more resource elements may be selected according to a programmatic or pseudo-random selection function, which may be based on a cell identifier, or the like.

Furthermore, one or more resource elements may be excluded from resource elements allocated for transmission of control data. In this regard, legacy devices may still receive CRS and control data to reduce the impact of introducing PRS transmissions. In another example, one or more resource elements may be selected from within a sub-band of a positioning subframe, where the sub-band is allocated for transmitting PRSs. As previously described, the sub-band can be adjacent to additional sub-bands allocated for transmitting disparate PRSs, user plane data, and/or the like, adjacent to a guard band, and/or the like. At 806, PRSs may be transmitted in one or more resource elements. In an example, a transmit diversity scheme can be applied to the PRS to further reduce the impact of the PRS on legacy devices and to ensure that the channel estimate of the PRS has little uncertainty regarding the cyclic shift. Furthermore, PRSs may be transmitted with nearly all available transmit power.

Turning to fig. 9, an example methodology 900 that facilitates transmitting PRSs in a backward compatible manner is illustrated. At 902, a positioning subframe for transmitting a PRS may be determined. In an example, this can include determining a portion of a positioning subframe, such as a slot or a portion thereof, allocated for PRS transmission. As described, a positioning subframe may comprise a plurality of resource elements, a portion of which may be reserved for CRS and/or control data transmission. At 904, one or more resource elements in a positioning subframe that are not allocated for CRS transmission may be selected for transmitting PRSs. As described, one or more resource elements may be selected according to a programmatic or pseudo-random selection function, which may be based on a cell identifier, or the like. At 906, the positioning subframe may be indicated as an MBSFN subframe. In this regard, legacy devices receiving positioning subframes may ignore portions that are not reserved for control data, and thus will not receive PRSs. This mitigates potential confusion for legacy devices caused by the introduction of PRSs. At 908, PRSs may be transmitted in one or more resource elements, as described.

Turning to fig. 10, an example methodology 1000 that facilitates indicating positioning subframes as MBSFN subframes to control CRS transmission in the subframes is illustrated. At 1002, one or more subframes may be selected as positioning subframes for blanking data transmissions. As described, the subframes may be selected according to a pseudo-random or planned pattern, which may be received from a network device, determined according to a network specification, configuration, or hard-coding, and so forth. At 1004, one or more of the positioning subframes may be indicated as MBSFN subframes to further blank CRS transmissions. As described, positioning subframes to be indicated as MBSFN subframes may be selected according to a planned, pseudo-random, or other pattern to increase reuse of CRS among multiple access points. Further, the modes may be defined in network specifications, configurations, hard coding, and the like. In an alternative example, it should be appreciated that all positioning subframes may be indicated as MBSFN subframes. Subsequently, as described above, MBSFN subframes may be selected for transmitting CRS.

Turning to fig. 11, an example methodology 1100 that facilitates indicating positioning subframes as MBSFN subframes to control CRS transmission in the subframes is illustrated. At 1102, one or more subframes may be selected as positioning subframes for blanking data transmissions. As described, the subframes may be selected according to a pseudo-random or planned pattern, which may be received from a network device, determined according to a network specification, configuration, or hard-coding, and so forth. At 1104, substantially all positioning subframes may be indicated as MBSFN subframes. At 1106, a CRS-like waveform may be transmitted in one or more of the MBSFN subframes. As described, one or more MBSFN subframes on which CRS-like waveforms are transmitted may be selected according to a planned, pseudo-random, or other pattern to increase reuse of CRS (or CRS-like waveforms) among multiple access points. Further, the modes may be defined in network specifications, configurations, hard coding, and the like.

It is to be appreciated that, in accordance with one or more aspects described herein, inferences can be made regarding determining subframes, slots, subbands, resource blocks, resource elements, and so forth for transmitting PRSs and/or the like. As used herein, the term to "infer" or "inference" refers generally to the process of reasoning about or inferring states of the system, environment, and/or user from a set of observations as captured via events and/or data. Inference can be employed to identify a specific context or action, or can generate a probability distribution over states, for example. The inference can be probabilistic-that is, the computation of a probability distribution over states of interest based on a consideration of data and events. Inference can also refer to techniques employed for composing higher-level events from a set of events and/or data. This inference results in the construction of new events or actions from a set of observed events and/or stored event data, whether or not the events are correlated in close temporal proximity, and whether the events and data come from one event and data source or from several event and data sources.

Referring to fig. 12, illustrated is a system 1200 that transmits PRSs in positioning subframes to improve the audibility of PRSs. For example, system 1200 can reside at least partially within a base station, mobile device, and/or the like. It is to be appreciated that system 1200 is represented as including functional blocks, which can be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System 1200 includes a logical grouping 1202 of electrical components that can act in conjunction. For instance, logical grouping 1202 can include an electrical component for determining positioning subframes configured for transmitting PRSs 1204. As described, this may be determined according to a standard, network specification, configuration, hard coding, and/or the like. Moreover, electrical component 1204 can determine a portion of a positioning subframe allocated for transmitting PRSs, such as a slot, a subband, and/or the like.

Additionally, logical grouping 1202 can include an electrical component for selecting one or more resource elements in a positioning subframe for transmitting PRSs and excluding a set of resource elements allocated for transmitting CRS 1206. As described, this can include selecting resource elements according to a programmatic or pseudo-random function, which can be based on an identifier of a cell provided by system 1200, or other constants or variables, and so forth. Moreover, electrical component 1206 can select one or more resource elements in accordance with a PRS pattern as previously described (in accordance with a planned or pseudo-random function or otherwise), which can be a diagonal pattern, or virtually any pattern that selects different resource elements for transmitting PRS from among consecutive OFDM symbols in a positioning subframe.

Moreover, logical grouping 1202 includes an electrical component for transmitting PRSs in the one or more resource elements 1208. In an example, the electrical component 1208 can transmit the PRS at substantially all available transmit power. Further, the logical grouping 1202 can include an electrical component for applying a transmit diversity scheme to the PRS 1210. This may include PVS, CDD, and/or the like to ensure that the channel estimate for the PRS has little uncertainty regarding the cyclic shift. Additionally, system 1200 can include a memory 1212 that retains instructions for executing functions associated with electrical components 1204, 1206, 1208, and 1210. While shown as being external to memory 1212, it is to be understood that one or more of electrical components 1204, 1206, 1208, and 1210 can exist within memory 1212.

Referring to fig. 13, illustrated is a system 1500 that indicates one or more positioning subframes as MBSFN subframes to improve hearability of CRS. For example, system 1500 can reside at least partially within a base station, mobile device, and/or the like. It is to be appreciated that system 1500 is represented as including functional blocks, which can be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System 1500 includes a logical grouping 1502 of electrical components that can act in conjunction. For example, logical grouping 1502 may comprise an electrical component for selecting one or more subframes as one or more positioning subframes for blanking data transmissions 1504. As described, the positioning subframes may be selected according to a planned, pseudo-random, or other pattern, which may be determined or received according to a standard, network specification, configuration, hard coding, and/or the like.

Additionally, logical grouping 1502 may include an electrical component for determining one or more positioning subframes as one or more MBSFN subframes 1306. As described, this can include selecting MBSFN subframes according to a planned, pseudo-random, or other pattern that increases reuse of CRS transmitted in non-MBSFN positioning subframes. Further, the logical grouping 1302 includes an electrical component for indicating one or more MBSFN subframes as MBSFN subframes 1308. Accordingly, the receiving apparatus can appropriately process the signal received in the subframe. Moreover, the logical grouping 1302 can include an electrical component for transmitting a CRS-like waveform in at least one of the one or more MBSFN subframes 1310. When the electrical component 1310 is present, as described, substantially all positioning subframes may be indicated as MBSFN subframes, allowing the electrical component 1310 to select subframes for transmitting CRS-like waveforms to improve its audibility to devices capable of receiving and processing these waveforms. Additionally, system 1300 can include a memory 1312 that retains instructions for executing functions associated with electrical components 1304, 1306, 1308, and 1310. While shown as being external to memory 1312, it is to be understood that one or more of electrical components 1304, 1306, 1308, and 1310 can exist within memory 1312.

FIG. 14 is a block diagram of a system 1400 that may be used to implement various aspects of the functionality described herein. In an example, system 1400 includes a base station or eNB 1402. As illustrated, eNB1402 may receive signals from one or more UEs 1404 via one or more receive (Rx) antennas 1406 and transmit signals to one or more UEs 1404 via one or more transmit (Tx) antennas 1408. Additionally, eNB1402 can include a receiver 1410 that receives information from receive antenna 1406. In an example, the receiver 1410 can be operatively associated with a demodulator (Demod)1412 that demodulates received information. Demodulated symbols can then be analyzed by a processor 1414. The processor 1414 can be coupled to a memory 1416, and the memory 1416 can store information related to code clusters, access terminal assignments, lookup tables related thereto, unique scrambling sequences, and/or other suitable types of information. In an example, eNB1402 can employ processor 1414 to perform methodologies 800, 900, 1000, 1100, and/or other similar and appropriate methodologies. eNB1402 may also include a modulator 1418 that may multiplex a signal for transmission by a transmitter 1420 via transmit antennas 1408.

FIG. 15 is a block diagram of another system 1500 that may be used to implement various aspects of the functionality described herein. In one example, the system 1500 includes a mobile terminal 1502. As illustrated, mobile terminal 1502 can receive signal(s) from one or more base stations 1504 via one or more antennas 1508 and transmit signal(s) to one or more base stations 1504 via one or more antennas 1508. Additionally, mobile terminal 1502 can include a receiver 1510 that receives information from antenna 1508. In an example, the receiver 1510 can be operatively associated with a demodulator (Demod)1512 that demodulates received information. Demodulated symbols can then be analyzed by a processor 1514. Processor 1514 can be coupled to memory 1516, and memory 1516 can store data and/or program codes related to mobile terminal 1502. Additionally, mobile terminal 1502 can employ processor 1514 to perform methodologies 800, 900, 1000, 1100, and/or other similar and appropriate methodologies. The mobile terminal 1502 may also use one or more components described in previous figures to carry out the described functionality; in an example, the components may be implemented by the processor 1514. Mobile terminal 1502 may also include a modulator 1518 that can multiplex a signal for transmission by a transmitter 1520 via antenna 1508.

Referring now to fig. 16, an illustration of a wireless multiple-access communication system in accordance with various aspects is provided. In an example, an access point 1600(AP) includes multiple antenna groups. As illustrated in fig. 16, one antenna group may include antennas 1604 and 1606, another antenna group may include antennas 1608 and 1610, and another antenna group may include antennas 1612 and 1614. Although only two antennas are shown in fig. 16 for each antenna group, it should be understood that more or fewer antennas may be used for each antenna group. In another example, access terminal 1616 can be in communication with antennas 1612 and 1614, where antennas 1612 and 1614 transmit information to access terminal 1616 over forward link 1620 and receive information from access terminal 1616 over reverse link 1618. Alternatively and/or additionally, access terminal 1622 can be in communication with antennas 1606 and 1608, where antennas 1606 and 1608 transmit information to access terminal 1622 over forward link 1626 and receive information from access terminal 1622 over reverse link 1624. In a frequency division duplex system, communication links 1618, 1620, 1624, and 1626 may use different frequencies for communication. For example, forward link 1620 may use a different frequency than that used by reverse link 1618.

Each group of antennas and/or the area in which they are designed to communicate may be referred to as a sector of the access point. In accordance with an aspect, a group of antennas can be designed to communicate to access terminals in a sector of the areas covered by access point 1600. In communication over forward links 1620 and 1626, the transmitting antennas of access point 1600 can utilize beamforming in order to improve signal-to-noise ratio of forward links for the different access terminals 1616 and 1622. Also, an access point using beamforming to transmit to access terminals scattered randomly through its coverage causes less interference to access terminals in neighboring cells than an access point transmitting to all its access terminals via a single antenna.

An access point (e.g., access point 1600) can be a fixed station used for communicating with the terminals and can also be referred to as a base station, an eNB, an access network, and/or other suitable terminology. Moreover, an access terminal (e.g., access terminal 1616 or 1622) can also be referred to as a mobile terminal, user equipment, a wireless communication device, a terminal, a wireless terminal, and/or other appropriate terminology.

Referring now to fig. 17, a block diagram illustrating an example wireless communication system 1700 is provided, in which various aspects described herein can function in the wireless communication system 1700. In an example, system 1700 is a multiple-input multiple-output (MIMO) system that includes a transmitter system 1710 and a receiver system 1750. It should be appreciated, however, that transmitter system 1710 and/or receiver system 1750 can also be applied to a multiple-input single-output system, where, for example, multiple transmit antennas (e.g., on a base station) can transmit one or more symbol streams to a single antenna device (e.g., a mobile station). Additionally, it should be appreciated that aspects of the transmitter system 1710 and/or the receiver system 1750 described herein may be utilized in conjunction with a single-output to single-input antenna system.

In accordance with an aspect, traffic data for a number of data streams is provided at transmitter system 1710 from a data source 1712 to a Transmit (TX) data processor 1714. In an example, each data stream can then be transmitted via a respective transmit antenna 1724. Additionally, TX data processor 1714 can format, encode, and interleave traffic data for each data stream based on a particular coding scheme selected for each respective data stream in order to provide coded data. In an example, the coded data for each data stream can then be multiplexed with pilot data using OFDM techniques. The pilot data may be, for example, a known data pattern that is processed in a known manner. In addition, pilot data can be used at receiver system 1750 to estimate channel response. Returning at transmitter system 1710, the multiplexed pilot and coded data for each data stream can be 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. In an example, the data rate, coding, and modulation for each data stream can be determined by instructions executed on processor 1730 and/or provided by processor 1730.

Next, the modulation symbols for all data streams can be provided to a TX processor 1720, which can further process the modulation symbols (e.g., for OFDM). TX MIMO processor 1720 may then sum N_TA stream of modulation symbols is provided to N_TA plurality of transceivers 1722a through 1722 t. In an example, each transceiver 1722 can receive and process a respective symbol stream to provide one or more analog signals. Each transceiver 1722 may then further condition (e.g., amplify, filter, and upconvert) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. Thus, one can then separately proceed from N_TN transmitted by antennas 1724a through 1724t from transceivers 1722a through 1722t_TA modulated signal.

According to another aspect, N may be passed_RThe transmitted modulated signals are received by the individual antennas 1752a through 1752r at receiver system 1750. Can then come from each antenna1752 are provided to respective transceivers 1754. In an example, each transceiver 1754 can condition (e.g., filter, amplify, and downconvert) a respective received signal, digitize the conditioned signal to provide samples, and then processes the samples to provide a corresponding "received" symbol stream. RX MIMO/data processor 1760 may then be driven from N_RN is received by a transceiver 1754_RA plurality of received symbol streams and processing the received symbol streams based on a particular receiver processing technique to provide N_TA stream of "detected" symbols. In an example, each detected symbol stream can comprise symbols that are estimates of the modulation symbols transmitted for the corresponding data stream. RX processor 1760 can then process each symbol stream at least in part by demodulating, deinterleaving, and decoding each detected symbol stream to recover traffic data for a corresponding data stream. Thus, the processing by RX processor 1760 can be complementary to that performed by TX MIMO processor 1720 and TX data processor 1718 at transmitter system 1710. RX processor 1760 can additionally provide a stream of processed symbols to a data sink 1764.

In accordance with an aspect, the channel response estimate generated by RX processor 1760 can be used to perform space/time processing at the receiver, adjust power levels, change modulation rates or schemes, and/or other appropriate actions. Additionally, RX processor 1760 can further estimate channel characteristics, such as the signal-to-noise-and-interference ratios (SNRs) of the detected symbol streams. RX processor 1760 can then provide estimated channel characteristics to a processor 1770. In an example, RX processor 1760 and/or processor 1770 can further derive an estimate of the "operating" SNR for the system. Processor 1770 can then provide Channel State Information (CSI), which can comprise information regarding the communication link and/or the received data stream. This information may include, for example, the operating SNR. The CSI can then be processed by a TX data processor 1718, modulated by a modulator 1780, conditioned by transceivers 1754a through 1754r, and transmitted back to transmitter system 1710. Further, a data source 1716 at receiver system 1750 may provide additional data for processing by TX data processor 1718.

Returning to transmitter system 1710, the modulated signals from receiver system 1750 may then be received by antennas 1724, conditioned by transceivers 1722, demodulated by a demodulator 1740, and processed by a RX data processor 1742 to recover the CSI reported by receiver system 1750. In an example, the reported CSI can then be provided to processor 1730 and used to determine data rates and coding and modulation schemes to be used for one or more data streams. The determined coding and modulation schemes can then be provided to transceiver 1722 for quantization and/or use in later transmissions to receiver system 1750. Alternatively, and/or in addition, the reported CSI can be used by processor 1730 to generate various controls for TX data processor 1714 and TX MIMO processor 1720. In another example, CSI and/or other information processed by RX data processor 1742 can be provided to a data sink 1744.

In an example, processor 1730 at transmitter system 1710 and processor 1770 at receiver system 1750 direct operation at their respective systems. Additionally, memory 1732 at transmitter system 1710 and memory 1772 at receiver system 1750 can provide storage for program codes and data used by processors 1730 and 1770, respectively. Additionally, at receiver system 1750, N may be processed using various processing techniques_RA received signal to detect N_TA stream of transmitted symbols. These receiver processing techniques may include spatial and space-time receiver processing techniques, which may also be referred to as equalization techniques, and/or "successive nulling/equalization and interference cancellation" receiver processing techniques, which may also be referred to as "successive interference cancellation" or "successive cancellation" receiver processing techniques.

It is to be understood that the aspects described herein may be implemented by hardware, software, firmware, middleware, microcode, or any combination thereof. When the systems and/or methods are implemented in software, firmware, middleware or microcode, program code or code segments, they can be stored in a machine-readable medium, such as a storage component. A code segment may represent a program, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted using any suitable means including memory sharing, message passing, token passing, network transmission, etc.

For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via various means as is known in the art.

What has been described above includes examples of one or more aspects. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned aspects, but one of ordinary skill in the art may recognize that many further combinations and permutations of various aspects are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. Furthermore, the term "or" as used in the detailed description or claims means "non-exclusive or".

Claims (8)

1. A method, comprising:

selecting one or more subframes as one or more positioning subframes for blanking data transmissions; and

indicating one or more of the one or more positioning subframes as one or more multicast/broadcast single frequency network (MBSFN) subframes to otherwise blank cell-specific reference signal (CRS) transmissions on the one or more MBSFN subframes.

2. The method of claim 1, further comprising determining the one or more positioning subframes as the one or more MBSFN subframes according to a planned pattern or a pseudorandom pattern.

3. The method of claim 2, wherein the planned pattern or the pseudo-random pattern is received from a network specification, configuration, or hard-coding.

4. The method of claim 1, further comprising transmitting a CRS-like waveform in at least one of the one or more MBSFN subframes.

5. A wireless communications apparatus, comprising:

at least one processor configured to:

determining one or more subframes as one or more positioning subframes for blanking data transmissions;

discern one or more of the one or more positioning subframes as one or more multicast/broadcast single frequency network (MBSFN) subframes to otherwise blank cell-specific reference signal (CRS) transmissions on the one or more MBSFN subframes; and

indicating the one or more MBSFN subframes as MBSFN subframes; and

a memory coupled to the at least one processor.

6. An apparatus, comprising:

means for selecting one or more subframes as one or more positioning subframes for blanking data transmissions;

means for determining the one or more positioning subframes as one or more multicast/broadcast single frequency network (MBSFN) subframes; and

means for indicating the one or more MBSFN subframes as MBSFN subframes.

7. A computer program product, comprising:

a computer-readable medium, comprising:

code for causing at least one computer to select one or more subframes as one or more positioning subframes for blanking data transmissions; and

code for causing the at least one computer to indicate the one or more positioning subframes as one or more multicast/broadcast single frequency network (MBSFN) subframes to additionally blank cell-specific reference signal (CRS) transmissions on the one or more MBSFN subframes.

8. An apparatus, comprising:

a positioning subframe selection component that determines one or more subframes as one or more positioning subframes for blanking data transmissions;

a multicast/broadcast single frequency network (MBSFN) subframe determination component that selects the one or more positioning subframes as one or more MBSFN subframes; and

an MBSFN subframe specification component that indicates the one or more MBSFN subframes as MBSFN subframes.