Interference cancelation using edge signals for synchronization signal detection

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

p-0002The present application for patent claims benefit of U.S. Provisional Patent Application Ser. No. 61/322,223, entitled, “Implementation of PSS and SSS interference cancelation”, filed Apr. 8, 2010, and assigned to the assignee hereof and hereby expressly incorporated by reference herein.

TECHNICAL FIELD

p-0003Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to a method for applying a time domain cancelation in obtaining a synchronization signal from a serving cell.

BACKGROUND

p-0004Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may include multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, 3^rdGeneration Partnership Project (3GPP) Long Term Evolution (LTE) systems, Long Term Evolution Advanced (LTE-A) systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems.

p-0005Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-input single-output, multiple-input single-output or a multiple-input multiple-output (MIMO) system.

SUMMARY

p-0006In 3GPP Release (Rel) 8, a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) may be transmitted in six resource blocks, occupying, for example, the center 62 tones (i.e., subcarriers) of an LTE-A system, wherein the center tone may be skipped. In synchronous networks, cells may transmit their respective PSS and SSS on the same frequency at the same time, wherein strong cells may overshadow the weak ones. However, strong cells may not be the serving cell for a user equipment (UE), particularly in a heterogeneous network. Traditionally, interference cancelation, an enhanced receiver technique, has been used, wherein the UE may first find the strong cells and cancel them out to find the serving cell. However, due to propagation delay and synchronization uncertainty, a timing offset may exist among cells, even in synchronous networks. Therefore, systems and methods are disclosed, providing for improved handling of the timing offset among different cells by applying a time domain cancelation.

p-0007Certain aspects of the present disclosure provide a method for wireless communications. The method generally includes receiving a composite signal comprising a synchronization signal transmitted from a serving cell; detecting, within the composite signal, at least one other synchronization signal transmitted from at least one neighbor cell; reconstructing the at least one other synchronization signal; generating a combined signal by combining edge tones and a center tone from the composite signal with the reconstructed synchronization signal; and canceling the combined signal from the composite signal to obtain the synchronization signal from the serving cell.

p-0008Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes means for receiving a composite signal comprising a synchronization signal transmitted from a serving cell; means for detecting, within the composite signal, at least one other synchronization signal transmitted from at least one neighbor cell; means for reconstructing the at least one other synchronization signal; means for generating a combined signal by combining edge tones and a center tone from the composite signal with the reconstructed synchronization signal; and means for canceling the combined signal from the composite signal to obtain the synchronization signal from the serving cell.

p-0009Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes at least one processor configured to receive a composite signal comprising a synchronization signal transmitted from a serving cell, detect, within the composite signal, at least one other synchronization signal transmitted from at least one neighbor cell, reconstruct the at least one other synchronization signal, generate a combined signal by combining edge tones and a center tone from the composite signal with the reconstructed synchronization signal, and cancel the combined signal from the composite signal to obtain the synchronization signal from the serving cell.

p-0010Certain aspects provide a computer-program product for wireless communications. The computer-program product typically includes a computer-readable medium having instructions stored thereon, the instructions being executable by one or more processors. The instructions generally include code for receiving a composite signal comprising a synchronization signal transmitted from a serving cell; code for detecting, within the composite signal, at least one other synchronization signal transmitted from at least one neighbor cell; code for reconstructing the at least one other synchronization signal; code for generating a combined signal by combining edge tones and a center tone from the composite signal with the reconstructed synchronization signal; and code for canceling the combined signal from the composite signal to obtain the synchronization signal from the serving cell.

p-0011Various aspects and features of the disclosure are described in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0012So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

p-0013<figref idrefs="DRAWINGS">FIG. 1</figref> illustrates an example multiple access wireless communication system in accordance with certain aspects of the present disclosure.

p-0014<figref idrefs="DRAWINGS">FIG. 2</figref> illustrates a block diagram of an access point and a user terminal in accordance with certain aspects of the present disclosure.

p-0015<figref idrefs="DRAWINGS">FIG. 3</figref> illustrates various components that may be utilized in a wireless device in accordance with certain aspects of the present disclosure.

p-0016<figref idrefs="DRAWINGS">FIG. 4</figref> illustrates example operations for performing time domain cancelation in accordance with certain aspects of the present disclosure.

p-0017<figref idrefs="DRAWINGS">FIG. 4A</figref> illustrates example components capable of performing the operations illustrated in <figref idrefs="DRAWINGS">FIG. 4</figref>.

p-0018<figref idrefs="DRAWINGS">FIGS. 5A-D</figref> illustrate the processing of synchronization signals in accordance the operations illustrated in <figref idrefs="DRAWINGS">FIG. 4</figref>.

DETAILED DESCRIPTION

p-0019Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method, which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

p-0020The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

p-0021Although particular aspects are described herein, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular benefits, uses or objectives. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks and transmission protocols, some of which are illustrated by way of example in the figures and in the following description of the preferred aspects. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.

An Example Wireless Communication System

p-0022The techniques described herein may be used for various wireless communication networks such as Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms “networks” and “systems” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate (LCR). CDMA2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM, etc. UTRA, E-UTRA, and GSM are part of Universal Mobile Telecommunication System (UMTS). Long Term Evolution (LTE) is an upcoming release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). CDMA2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2).

p-0023Single carrier frequency division multiple access (SC-FDMA) is a transmission technique that utilizes single carrier modulation at a transmitter side and frequency domain equalization at a receiver side. The SC-FDMA has similar performance and essentially the same overall complexity as those of OFDMA system. However, SC-FDMA signal has lower peak-to-average power ratio (PAPR) because of its inherent single carrier structure. The SC-FDMA has drawn great attention, especially in the uplink communications where lower PAPR greatly benefits the mobile terminal in terms of transmit power efficiency. It is currently a working assumption for uplink multiple access scheme in the 3GPP LTE and the Evolved UTRA.

p-0024An access point (“AP”) may comprise, be implemented as, or known as NodeB, Radio Network Controller (“RNC”), eNodeB, Base Station Controller (“BSC”), Base Transceiver Station (“BTS”), Base Station (“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, Basic Service Set (“BSS”), Extended Service Set (“ESS”), Radio Base Station (“RBS”), or some other terminology.

p-0025An access terminal (“AT”) may comprise, be implemented as, or known as an access terminal, a subscriber station, a subscriber unit, a mobile station, a remote station, a remote terminal, a user terminal, a user agent, a user device, user equipment, a user station, or some other terminology. In some implementations, an access terminal may comprise a cellular telephone, a cordless telephone, a Session Initiation Protocol (“SIP”) phone, a wireless local loop (“WLL”) station, a personal digital assistant (“PDA”), a handheld device having wireless connection capability, a Station (“STA”), or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or smart phone), a computer (e.g., a laptop), a portable communication device, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device, or a satellite radio), a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. In some aspects, the node is a wireless node. Such wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link.

p-0026Referring to <figref idrefs="DRAWINGS">FIG. 1</figref>, a multiple access wireless communication system according to one aspect is illustrated. An access point <b>100</b> (AP) may include multiple antenna groups, one group including antennas <b>104</b> and <b>106</b>, another group including antennas <b>108</b> and <b>110</b>, and an additional group including antennas <b>112</b> and <b>114</b>. In <figref idrefs="DRAWINGS">FIG. 1</figref>, only two antennas are shown for each antenna group, however, more or fewer antennas may be utilized for each antenna group. Access terminal <b>116</b> (AT) may be in communication with antennas <b>112</b> and <b>114</b>, where antennas <b>112</b> and <b>114</b> transmit information to access terminal <b>116</b> over forward link <b>120</b> and receive information from access terminal <b>116</b> over reverse link <b>118</b>. Access terminal <b>122</b> may be in communication with antennas <b>106</b> and <b>108</b>, where antennas <b>106</b> and <b>108</b> transmit information to access terminal <b>122</b> over forward link <b>126</b> and receive information from access terminal <b>122</b> over reverse link <b>124</b>. In a FDD system, communication links <b>118</b>, <b>120</b>, <b>124</b> and <b>126</b> may use different frequency for communication. For example, forward link <b>120</b> may use a different frequency then that used by reverse link <b>118</b>.

p-0027Each group of antennas and/or the area in which they are designed to communicate is often referred to as a sector of the access point. In one aspect of the present disclosure, each antenna group may be designed to communicate to access terminals in a sector of the areas covered by access point <b>100</b>.

p-0028In communication over forward links <b>120</b> and <b>126</b>, the transmitting antennas of access point <b>100</b> may utilize beamforming in order to improve the signal-to-noise ratio of forward links for the different access terminals <b>116</b> and <b>122</b>. 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 through a single antenna to all its access terminals.

p-0029<figref idrefs="DRAWINGS">FIG. 2</figref> illustrates a block diagram of an aspect of a transmitter system <b>210</b> (also known as the access point) and a receiver system <b>250</b> (also known as the access terminal) in a multiple-input multiple-output (MIMO) system <b>200</b>. At the transmitter system <b>210</b>, traffic data for a number of data streams is provided from a data source <b>212</b> to a transmit (TX) data processor <b>214</b>.

p-0030In one aspect of the present disclosure, each data stream may be transmitted over a respective transmit antenna. TX data processor <b>214</b> formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.

p-0031The coded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream is then modulated (i.e., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding and modulation for each data stream may be determined by instructions performed by processor <b>230</b>. Memory <b>232</b> may store data and software for the transmitter system <b>210</b>.

p-0032The modulation symbols for all data streams are then provided to a TX MIMO processor <b>220</b>, which may further process the modulation symbols (e.g., for OFDM). TX MIMO processor <b>220</b> then provides N_Tmodulation symbol streams to N_Ttransmitters (TMTR) <b>222</b><i>a </i>through <b>222</b><i>t</i>. In certain aspects of the present disclosure, TX MIMO processor <b>220</b> applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

p-0033Each transmitter <b>222</b> receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. N_Tmodulated signals from transmitters <b>222</b><i>a </i>through <b>222</b><i>t </i>are then transmitted from N_Tantennas <b>224</b><i>a </i>through <b>224</b><i>t</i>, respectively.

p-0034At receiver system <b>250</b>, the transmitted modulated signals may be received by N_Rantennas <b>252</b><i>a </i>through <b>252</b><i>r </i>and the received signal from each antenna <b>252</b> may be provided to a respective receiver (RCVR) <b>254</b><i>a </i>through <b>254</b><i>r</i>. Each receiver <b>254</b> may condition (e.g., filters, amplifies, and downconverts) a respective received signal, digitize the conditioned signal to provide samples, and further process the samples to provide a corresponding “received” symbol stream.

p-0035An RX data processor <b>260</b> then receives and processes the N_Rreceived symbol streams from N_Rreceivers <b>254</b> based on a particular receiver processing technique to provide N_T“detected” symbol streams. The RX data processor <b>260</b> then demodulates, deinterleaves and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor <b>260</b> may be complementary to that performed by TX MIMO processor <b>220</b> and TX data processor <b>214</b> at transmitter system <b>210</b>.

p-0036A processor <b>270</b> periodically determines which pre-coding matrix to use. Processor <b>270</b> formulates a reverse link message comprising a matrix index portion and a rank value portion. Memory <b>272</b> may store data and software for the receiver system <b>250</b>. The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor <b>238</b>, which also receives traffic data for a number of data streams from a data source <b>236</b>, modulated by a modulator <b>280</b>, conditioned by transmitters <b>254</b><i>a </i>through <b>254</b><i>r</i>, and transmitted back to transmitter system <b>210</b>.

p-0037At transmitter system <b>210</b>, the modulated signals from receiver system <b>250</b> are received by antennas <b>224</b>, conditioned by receivers <b>222</b>, demodulated by a demodulator <b>240</b> and processed by a RX data processor <b>242</b> to extract the reserve link message transmitted by the receiver system <b>250</b>. Processor <b>230</b> then determines which pre-coding matrix to use for determining the beamforming weights, and then processes the extracted message.

p-0038<figref idrefs="DRAWINGS">FIG. 3</figref> illustrates various components that may be utilized in a wireless device <b>302</b> that may be employed within the wireless communication system illustrated in <figref idrefs="DRAWINGS">FIG. 1</figref>. The wireless device <b>302</b> is an example of a device that may be configured to implement the various methods described herein. The wireless device <b>302</b> may include a base station <b>100</b> or any of user terminals <b>116</b> and <b>122</b>.

p-0039The wireless device <b>302</b> may include a processor <b>304</b>, which controls operation of the wireless device <b>302</b>. The processor <b>304</b> may also be referred to as a central processing unit (CPU). Memory <b>306</b>, which may include both read-only memory (ROM) and random access memory (RAM), provides instructions and data to the processor <b>304</b>. A portion of the memory <b>306</b> may also include non-volatile random access memory (NVRAM). The processor <b>304</b> typically performs logical and arithmetic operations based on program instructions stored within the memory <b>306</b>. The instructions in the memory <b>306</b> may be executable to implement the methods described herein.

p-0040The wireless device <b>302</b> may also include a housing <b>308</b> that may include a transmitter <b>310</b> and a receiver <b>312</b> to allow transmission and reception of data between the wireless device <b>302</b> and a remote location. The transmitter <b>310</b> and receiver <b>312</b> may be combined into a transceiver <b>314</b>. A single or a plurality of transmit antennas <b>316</b> may be attached to the housing <b>308</b> and electrically coupled to the transceiver <b>314</b>. The wireless device <b>302</b> may also include (not shown) multiple transmitters, multiple receivers, and multiple transceivers.

p-0041The wireless device <b>302</b> may also include a signal detector <b>318</b> that may be used in an effort to detect and quantify the level of signals received by the transceiver <b>314</b>. The signal detector <b>318</b> may detect such signals as total energy, energy per subcarrier per symbol, power spectral density and other signals. The wireless device <b>302</b> may also include a digital signal processor (DSP) <b>320</b> for use in processing signals.

p-0042The various components of the wireless device <b>302</b> may be coupled together by a bus system <b>322</b>, which may include a power bus, a control signal bus, and a status signal bus in addition to a data bus.

Interference Cancelation Using Edge Signals for Synchronization Signal Detection

p-0043In 3GPP Release (Rel) 8, a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) may be transmitted in six resource blocks, occupying, for example, the center 62 tones (i.e., subcarriers) of an LTE-A system, wherein the center subcarrier may be skipped. Therefore, the synchronization signals may be transmitted on the 31 subcarriers on either side of the center subcarrier. In synchronous networks, cells may transmit their respective PSS and SSS on the same frequency at the same time, wherein strong cells may overshadow the weak ones. However, strong cells may not be the serving cell for a user equipment (UE), particularly in a heterogeneous network. Further, due to propagation delay and synchronization uncertainty, a timing offset may exist among cells, even in synchronous networks. Certain aspects of the present disclosure provide for improved handling of the timing offset among different cells by applying a time domain cancelation.

p-0044<figref idrefs="DRAWINGS">FIG. 4</figref> illustrates operations <b>400</b> for performing time domain cancelation in accordance with certain aspects of the present disclosure. The operations <b>400</b> may be performed, for example, by the receiver system <b>250</b> (e.g., a UE) for performing time domain cancelation.

p-0045At <b>402</b>, the UE may receive a composite signal comprising a synchronization signal transmitted from a serving cell. The composite signal may include signaling from multiple cells, including both the serving cell and at least one non-serving cell.

p-0046At <b>404</b>, the UE may detect, within the composite signal, at least one synchronization signal transmitted from at least one neighboring non-serving cell. The synchronization signals may comprise at least one of a primary synchronization signal (PSS) or a secondary synchronization signal (SSS), but is not limited thereto and may include any signals sufficient for synchronizing a UE with a serving cell.

p-0047At <b>406</b>, the UE may reconstruct the at least one other synchronization signal. For example, the reconstruction may be performed by the RX data processor <b>260</b> of the receiver system <b>250</b>. An inverse fast Fourier transform (IFFT) may be performed to reconstruct the at least one synchronization signal in the time domain.

p-0048At <b>408</b>, the UE may generate a combined signal by combining edge tones and a center tone from the composite signal with the reconstructed synchronization signal. The combined signal may serve as an appropriate frequency domain filter for signal reconstruction to ensure that signals outside of the useful 62 tones may be nulled out. For some embodiments, when generating the combined signal, a cyclic prefix (CP) may be added. For some embodiments, the combining may be performed in the time domain. For other embodiments, the combining may be performed in the frequency domain. The number of edge tones combined may be dependent on a fast Fourier transform (FFT) size.

p-0049At <b>410</b>, the UE may cancel the combined signal from the composite signal to obtain the synchronization signal from the serving cell (i.e., using time domain cancelation).

p-0050Operation <b>400</b> illustrated in <figref idrefs="DRAWINGS">FIG. 4</figref> may correspond to means <b>400</b>A illustrated in <figref idrefs="DRAWINGS">FIG. 4A</figref>. Composite signal receiver <b>402</b>A may receive a composite signal comprising a synchronization signal transmitted from a serving cell (step <b>402</b>). Synchronization signal detector <b>404</b>A may detect, within the composite signal, at least one synchronization signal transmitted from at least one neighboring non-serving cell (step <b>404</b>). Synchronization signal re-generator <b>406</b>A may reconstruct the at least one other synchronization signal (step <b>406</b>). Edge tone isolator <b>408</b>A may isolate edge tones and a center tone from the composite signal. At <b>410</b>A, a combined signal may be generated by combining the edge tones and the center tone with the reconstructed synchronization signal (step <b>408</b>). At <b>412</b>A, the combined signal may be canceled from the composite signal to obtain the synchronization signal from the serving cell (step <b>410</b>).

p-0051<figref idrefs="DRAWINGS">FIGS. 5A-D</figref> illustrate the processing of synchronization signals received by a UE, in accordance with example operations <b>400</b>. As illustrated in <figref idrefs="DRAWINGS">FIG. 5A</figref>, the UE receives a composite signal <b>500</b> that include edge tones <b>504</b> and synchronization signals <b>502</b> transmitted from multiple cells. According to the illustration, the composite signal <b>500</b> is transmitted in six resource blocks, wherein the synchronization signals <b>502</b> occupy the center <b>62</b> subcarriers (i.e., tones) of the resource blocks. In synchronous networks, since cells may transmit their respective synchronization signals (e.g., PSS and SSS) on the same frequency at the same time, strong cells may overshadow the weak ones (see, e.g., synchronization signals <b>502</b> transmitted from the multiple cells). However, as described earlier, the detected strong cells may not include the desired serving cell for a UE, particularly in a heterogeneous network.

p-0052As illustrated in <figref idrefs="DRAWINGS">FIG. 5B</figref>, the UE detects, within the composite signal <b>500</b>, at least one synchronization signal <b>506</b> transmitted from at least one neighbor cell. The synchronization signals may comprise at least one of a PSS or a SSS. The UE may reconstruct the at least one other synchronization signal <b>506</b>. For example, an inverse fast Fourier transform (IFFT) may be performed to reconstruct a synchronization signal in the time domain.

p-0053As illustrated in <figref idrefs="DRAWINGS">FIG. 5C</figref>, the UE generates a combined signal <b>507</b> by combining edge tones <b>504</b> and a center tone (not shown) received in the composite signal <b>500</b> with the reconstructed synchronization signal <b>506</b>. This may serve as an appropriate frequency domain filter for signal reconstruction to ensure that signals outside of the tones of the synchronization signal may be nulled out. For some embodiments, the combining may be performed in the time domain. For other embodiments, the combining may be performed in the frequency domain (e.g., before performing IFFT). The UE may then cancel the combined signal <b>507</b> from the composite signal <b>500</b> to obtain the synchronization signal <b>508</b> from the serving cell (i.e., time domain cancelation), as illustrated in <figref idrefs="DRAWINGS">FIG. 5D</figref>.

p-0054Certain aspects of the present disclosure provide for improved handling of the timing offset among different cells by applying a time domain cancelation. Further, frequency domain reconstruction with copying received signals on the edge tones and center tones may have improved performance compared to simply zero padding the edge tones and center tones. For example, the probability of detection by a UE of a particular cell may increase due to the combination of the edge tones and the center tone with the synchronization signal when applying the time domain cancelation.

p-0055The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in Figures, those operations may have corresponding counterpart means-plus-function components.

p-0056As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing, and the like.

p-0057As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

p-0058The various operations of methods described above may be performed by any suitable means capable of performing the operations, such as various hardware and/or software component(s), circuits, and/or module(s). Generally, any operations illustrated in the Figures may be performed by corresponding functional means capable of performing the operations.

p-0059The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array signal (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components or any combination thereof designed to perform the functions described herein. A general purpose processor may include a microprocessor, but in the alternative, the processor may include any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

p-0060The steps of a method or algorithm described in connection with the present disclosure may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in any form of storage medium that is known in the art. Some examples of storage media that may be used include random access memory (RAM), read only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, and so forth. A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. A storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor.

p-0061The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

p-0062The functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions on a computer-readable medium. A storage media may include 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. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers.

p-0063Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For certain aspects, the computer program product may include packaging material.

p-0064Software or instructions may also be transmitted over a transmission 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 transmission medium.

p-0065Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.

p-0066It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation, and details of the methods and apparatus described above without departing from the scope of the claims.

p-0067While the foregoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.