Device-to-device receiving window selection for cross-cell operation

Abstract

Computer-readable medium or media containing commands which, when executed, control first user equipment (UE) to: Assign to a first cell provided by a first evolved node B (eNB); Estimating a downstream (DL) receive time corresponding to a second cell provided by a second eNB using processing of regular DL-PSS / SSS / CRS signals; and Determining a receive window for a fast Fourier transform to receive communications from a second UE, which is associated with the second cell provided by the second eNB, based on the estimation of the DL receive time corresponding to the second cell.

Description

Area

[0001] Embodiments of the present disclosure relate generally to the field of wireless communications, and more particularly to apparatus and methods for device-to-device receive window selection for cross-cell operation. background

[0002] The device-to-device (D2D) air interface, and specifically the sidelink (SL) interface, were introduced in Long-Term Evolution (LTE) Publication 12. D2D operation is expected to be supported in a variety of deployment scenarios, including in-coverage, partial-coverage, and out-of-coverage conditions.

[0003] An within-coverage state can apply to: intra-cell operation (both a D2D transmitter node (TX node) and a D2D receiver node (RX node) are within network coverage and assigned to the same cell); synchronous cross-cell operation (both the D2D TX and the D2D RX nodes are within network coverage and assigned to different synchronous cells); and asynchronous cross-cell operation (both the D2D TX and the D2D RX nodes are within network coverage and assigned to different time-domain asynchronous cells).

[0004] A partial coverage condition may apply to a first scenario in which a D2D TX node is within network coverage and the D2D RX node is outside network coverage. Alternatively, the partial coverage condition may apply to a second scenario in which a D2D TX node is outside network coverage and the D2D RX node is within network coverage.

[0005] An out-of-coverage condition can occur when both the D2D TX node and the D2D RX node are outside of network coverage. Brief description of the drawings

[0006] The following detailed description, taken in conjunction with the accompanying drawings, will make the embodiments more readily understood. To simplify this description, like reference numerals designate like structural elements. The embodiments are shown in the figures of the accompanying drawings by way of example and not by way of limitation. Fig. 1 shows a communication environment according to some embodiments. Fig. 2 shows a timing model according to some embodiments. Fig. 3 shows a timing model according to some embodiments. Fig. 4 shows an electronic device circuit according to some embodiments.

[0007] The document WO 2014 / 168 573 A2 describes methods and devices for enabling device-to-device (D2D) communication in wireless communication systems, in particular with regard to the management and allocation of resources for direct control signals between radio nodes and wireless devices.

[0008] Fig. 5 is a flow diagram illustrating a receive window determination operation according to some embodiments.

[0009] Fig. 6 is a diagram illustrating concepts according to some embodiments.

[0010] Fig. 7 is a system according to some embodiments.

[0011] Fig. 8 is a computing device according to some embodiments. Detailed description

[0012] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, wherein like numerals designate like parts throughout, and in which is shown by way of example embodiments that may be practiced. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure.

[0013] Various acts may be described as multiple separate actions or acts in a manner that is particularly helpful in understanding the claimed subject matter. However, the order of description should not be construed to imply that these acts are necessarily order-dependent. In particular, these acts may not be performed in the order presented. The described acts may be performed in a different order than that of the described embodiment. Various additional acts may be performed and / or described acts may be omitted in additional embodiments.

[0014] For the purposes of this disclosure, the term "A or B" means (A), (B), or (A and B). For the purposes of this disclosure, the term "A, B, or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0015] The description may use the terms "in one embodiment" or "in embodiments," both of which refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," and the like, as used with respect to the embodiments of the present disclosure, are synonymous.

[0016] User-device (UE) receivers can be designed to ensure adequate D2D demodulation performance in all of the deployment scenarios described above. One factor that may need to be considered is receive signal timing. From the receiver implementation perspective, it is important to appropriately adjust the timing of a fast Fourier transform (FFT) receive window and support handling of timing errors / skews. For D2D signals, both a signal timing model and propagation time statistics may differ compared to communication over a conventional wireless access network (WAN). In many cases, D2D receivers may rely on post-FFT skew compensation. This can pose some challenges for D2D receiver implementations and lead to reduced D2D demodulation performance.

[0017] LTE technical specifications (LTE-TS) only define procedures for D2D transmit signal timing. D2D receive signal timing, for example, the time reference for starting D2D signal reception, may not be defined and may be based on a UE implementation. However, D2D receive signal timing can have a direct impact on demodulation performance, and its implementation can be controlled with relatively few UE demodulation requirements.

[0018] Embodiments of the present disclosure describe methods and apparatus for D2D receive window selection (including adaptation) for cross-coverage cross-cell D2D operation in synchronous or asynchronous networks.

[0019] Fig. 1 shows a communications environment 100 according to some embodiments. The communications environment 100 may include an evolved node B (eNB) 104 providing a cell 108. A UE 112 may be bound to the cell 108, e.g., communicatively coupled to it. In this context, the cell 108 may be referred to below as a serving cell of the UE 112. The UE 112 may derive time and frequency synchronization by processing primary synchronization signals (PSS), secondary synchronization signals (SSS), and a channel reference signal (CRS) of the cell 108.

[0020] The communication environment 100 may also include an eNB 116 that provides a cell 120. A UE 124 may be bound to the cell 120. In this context, the cell 120 may be referred to as a serving cell of the UE 124. The UE 124 may derive time and frequency synchronization by processing the PSS / SSS / CRS of the cell 120.

[0021] In some embodiments, the eNBs 104 and 116 may be part of an evolved Universal Terrestrial Radio Access Network (EUTRAN) that provides a radio interface in accordance with the specifications and protocols established by the 3 rdGeneration Partnership Project (3GPP), including but not limited to LTE-TS. As used herein, "LTE" may generally refer to releases associated with original LTE, LTE-Advanced (LTE-A), 5G, etc. In other embodiments, the eNBs 104 and 116 may be part of other cellular systems, including, but not limited to, Global System for Mobile Communication (GSM), General Packet Radio Service (GPRS), Universal Mobile Telecommunications System (UMTS), High Speed ​​Packet Access (HSPA), Evolved HSPA (E-HSPA), etc.

[0022] The eNBs 104 and 116 may be in a temporally synchronous or asynchronous relationship with each other. When the eNBs 104 and 116 are in a synchronous relationship with each other, the communication environment 100 may be referred to as a synchronous inter-cell embodiment. When the eNBs 104 and 116 are in an asynchronous relationship with each other, the communication environment 100 may be referred to as an asynchronous inter-cell embodiment.

[0023] The signal propagation times between the various components of the communication environment 100 are in Fig. 1. In particular, signal propagation times are given as follows: between the eNB 104 (also referred to as “eNB1”) and the UE 112 (also referred to as “UE1”) by T eNB1 / UE1 ; between the eNB 104 and the UE 124 (also referred to as “UE2”) by T eNB1 / UE2 ; between the eNB 116 (also referred to as “eNB2”) and the UE 124 by T eNB2 / UE2; and between the UE 112 and the UE 124 by T UE1 / UE2 .

[0024] In addition to communication connections established with respective eNBs, the UEs may have side links established with each other to communicate in a D2D manner. For the purposes of this description, UE 112 may be referred to as D2D-TX and UE 124 as D2D-RX. However, it should be understood that each of these UEs may have both receive and transmit capabilities for both D2D communication and cellular communication.

[0025] The UE 124 may determine a receive window to receive D2D signals from the UE 112. The receive window may be a selected interval over which a receiver in the UE 124 is to process received waveforms to reconstruct the transmitted D2D signal. The processing may include applying an FFT function to the waveforms, and thus, in some embodiments, the receive window may also be referred to as an FFT window.

[0026] Selecting a receive window may depend on a D2D transmission type. If the D2D transmission type is Mode 1 transmission over a physical sidelink common channel (PSSCH), a downlink-based (DL-based) D2D signal transmission timing may be used. If the D2D transmission type refers to any other physical D2D channel (e.g., PSSCH Mode 2, a physical sidelink control channel (PSCCH), or a physical sidelink discovery channel (PSDCH)), an uplink-based (UL-based) D2D signal transmission timing may be used.

[0027] The DL-based D2D signal transmission timing may refer to a procedure in which the D2D signal transmission is initiated at a time T D2D_TXwhich can be selected based on a WAN-DL reception time reference point. The UL-based D2D signal transmission timing can refer to a procedure in which the D2D signal transmission is initiated at a time T D2D_TX which can be based on a WAN UL broadcast time reference point.

[0028] The DL- or UL-based D2D signal transmission timing may be consistent with the UE transmission timing specifications for Proximity Services (ProSe) provided in 3GPP-TS 36.133 Publication 12.7.0 Section 7.16.2 (3 April 2015). In particular, these specifications stipulate that sidelink transmissions (N TA,SL +N TA offset ) * T S before the reception of the first detected path (in time) of the corresponding downlink frame from the reference cell, where N TA offset\is specified in section 8.1 of 3GPP-TS 36.211 Publication 12.5.0 (26 March 2015) and is the specific time division duplex (TDD) offset (0 for frequency division duplex (FDD)), where N TA,SL =0 for the DL-based D2D transmission timing and N TA,SL =N TA for UL-based D2D transmission timing. N TA is a timing offset between uplink and downlink radio frames with a UE in accordance with the definition in section 3.1 in TS 36.211; N TA offset is a fixed leading timing offset in accordance with the definition in section 3.1 of TS 36.211; N TA,SL is a timing offset between sidelink and timing reference frames at the UE in accordance with the definition in section 9.10 of TS 36.211.

[0029] As discussed above, a suitable selection of a receive window can facilitate accurate and efficient demodulation of D2D signals. A D2D RX timing parameter T D2D_RX can refer to the beginning of an FFT window used to receive a D2D signal. The selection of the D2D RX timing parameter T D2D_RX by the UE 124 can first be described in terms of the DL-based D2D signal transmission timing.

[0030] In some embodiments, the D2D RX timing parameter corresponding to the DL-based D2D signal transmission timing may be determined at the D2D RX as follows: TD2D_RX=TDL_RX_eNB1−NTA,OFFSET×TS+Δ.

[0031] T DL_RX_eNB1is a DL reception timing estimated at the UE 124 based on signals from the eNB 104. The DL reception timing can be defined as a time at which the first detected path (in time) of a corresponding DL frame is received at the UE 124 from a reference cell, e.g., cell 108.

[0032] N TA offset can be specified in section 8.1 of TS 36.211 as discussed above and is the TDD-specific offset (0 for FDD). T S is the sampling period (for example 1 / (15000*2048) seconds) with which N TA offset is multiplied.

[0033] Δ is the UE implementation-specific offset that can be used to shift the receive window.

[0034] In some embodiments, the UE implementation-specific offset may be used to adjust a receive window for an individual D2D TX timing offset; for average timing offset statistics from multiple D2D transmitters; or for potential effects of imperfect measurements, for example, to compensate for DL ​​timing errors at the D2D TX / RX sides.

[0035] In one embodiment, Δ may be equal to „ -T CP / 2“ can be selected, where T CP is the duration of the cyclic prefix (CP) of the D2D signal in units of Ts.

[0036] Fig. 2 illustrates a timing model 200 of the D2D receive signal timing for the DL-based D2D signal transmission timing, according to some embodiments. The timing model 200 may correspond to a simplified case where an estimated DL timing is exactly equal to an eNB-to-UE propagation time. For example, a UE1 eNB1 DL RX timing estimate (e.g., a DL receive timing estimated at the UE 112 based on signals from the eNB 104) is equal to a time it takes for a signal to travel from the eNB 104 to the UE 112. Similarly, a UE2-eNB1 DL RX timing estimate (e.g., a DL reception timing estimated at the UE 124 based on signals from the eNB 116) is equal to a time it takes for a signal to travel from the eNB 104 to the UE 124. The UE2-eNB1 DL RX timing may be T DL_RX_eNB1described above in equation 1. The simplified case represented by the timing model 200 can also assume that there are no measurement errors and N TA offset and Δ are zero.

[0037] In Fig. 2, time “0” may correspond to an eNB 1 / 2 DL TX timing, which may be the downlink transmission timing of the eNB 104 and the eNB 116 (e.g., the reference time at which the eNBs perform the DL transmissions).

[0038] In some embodiments, the WAN DL receive time reference point used for the DL-based D2D signal transmission timing may be the UE1 eNB1 DL RX timing. Thus, the D2D TX timing (e.g., a time at which the D2D TX 112 is configured to transmit a D2D transmission 204) may be set equal to the UE1 eNB1 DL RX timing.

[0039] Referring to Equation 1 and setting N TA offsetand Δ is set to zero, the D2D RX timing parameter can be set equal to the UE2 eNB1 DL RX timing estimate. Thus, a receiver of UE 124 can adjust its receive window to a D2D reception 208.

[0040] The D2D transmission 204 may actually be transmitted to the UE 124 as a D2D RX signal 212 after a period of time (T UE1 / UE2 ) after being sent by the UE 112. T OFFSET may denote a time difference between the start of D2D reception 208 and the D2D RX signal 212. In some embodiments, Δ may be set such that the value of T OFFSET is reduced to move the receive window closer to the D2D RX signal 212.

[0041] In the case of UL-based D2D signal transmission timing, the D2D RX timing parameter can be determined at the D2D receiver as follows: TD2D_RX=TDL_RX_eNB1−NTA,OFFSETxTS−NTA_D2DxTS+Δ.

[0042] T DL_RX_eNB1 , N TA,OFFSET , TS and Δ may be similar to the terms described above with respect to Equation 1.

[0043] N TA_D2D can be the component responsible for D2D TX lead time (D2D TX TA) compensation. In the case of receiving the PSSCH from a single source in a transmission time interval (TTI), N TA_D2D be set equal to the D2D TA command signaled in a Sidelink Control Information (SCI) format 0 (notified in the PSCCH), which may be consistent with the information in the lead time specification of TS 36.212. In the case of simultaneous reception of the PSSCH from multiple sources in a TTI, N TA_D2DD2D TA commands signaled in SCI format 0 for different D2D transmitters take into account the respective PSCCH receive power and PSSCH PRB allocation (contiguous or not). This can be important if the UE is expected to receive multiple D2D signals in one subframe (TTI) from different D2D TXs. Each D2D TX can have its own TA indication in the SCI. The D2D RXs can use different strategies: (1) N TA_D2D equal to the largest TA signaled in different SCI, (2) N TA_D2D equal to the average TA among those signaled in different SCIs, or (3) weighted averaging, etc.

[0044] Fig. 3 shows a timing model 300 of the D2D receive signal timing for the UL-based D2D signal transmission timing according to some embodiments. The timing model 300, like the timing model 200, may correspond to a simplified case in which an estimated DL receive timing is exactly equal to an eNB-to-UE propagation time, there are no measurement errors, and N TA offset and Δ are zero.

[0045] In this case, a D2D reception 304 by the UE 124 may be performed using a TA correction N TA_D2D × T S which, with the given assumptions of the timing model 300, equals 2 × T eNB1 / UE2 can be.

[0046] To provide the D2D transmission 308, the UE 112 may, in accordance with the UL-based D2D signal transmission timing procedure, transmit its TA, TA UE1 , equal to 2 × T eNB1 / UE2 The UE 124 can receive the D2D transmission 308 for a D2D RX signal 312, which T UE1 / UE2after sending.

[0047] T OFFSET may denote a time difference between the start of D2D reception 304 and the D2D RX signal 312. In some embodiments, Δ may be set such that the value of T OFFSET is reduced to move the receive window closer to the D2D RX signal 312.

[0048] Under certain conditions, UE 124 can receive both intra-cell D2D signals (e.g., from another UE within cell 120) and cross-cell D2D signals (e.g., from UE 112) within a TTI. For receiving the intra-cell D2D signals, a serving cell DL timing can be used as the D2D RX timing reference. Meanwhile, for receiving the cross-cell D2D signals, the neighboring cell signal can be used (as described above). The following approaches can address such scenarios.

[0049] In some embodiments, the UE 124 may apply a one-time, single FFT processing. The receive signal timing may be selected based on the serving cell DL receive timing; based on the neighboring cell DL receive timing; or by using an adaptive timing selection between the serving cell and neighboring cell DL receive timing.

[0050] In some embodiments, the adaptive selection of the timing between the serving cell and the neighboring cell DL receive timing may be given by the following equation: TDL_RX_Adaptive=TDL_RX_eNB1*A+TDL_RX_eNB2*B, where A and B are scalar weights. In a simple form, A = B = 0.5, which can be the mean of the two values. An alternative is A=0, B=1 or A=1, B=0. Other weights can be used in other embodiments.

[0051] Then the DL-based D2D TX timing can be given by the following equation: TD2D_RX=TDL_RX_Adaptive−NTA,OFFSET×Ts+Δ, and the UL-based D2D-TX timing can be given by the following equation: TD2D_RX=TDL_RX_Adaptive−NTA,OFFSET×Ts−NTA_D2D×Ts+Δ.

[0052] In some embodiments, the UE 124 may apply dual FFT receive processing (e.g., one based on the serving cell DL receive timing and another based on the neighboring cell receive timing).

[0053] Fig. 4 shows an electronic device circuit 400 according to some embodiments. In some embodiments, the electronic device circuit may be a UE such as UE 124, or may be embedded within or otherwise part of a UE. In embodiments, the electronic device circuit 400 may include a transmit circuit 404 and a receive circuit 408 coupled to a control circuit 412. In embodiments, the transmit circuit 404 and / or the receive circuit 408 may be elements or modules of a transceiver circuit. The electronic device circuit 400 may be coupled to one or more antenna elements of one or more antennas 416.

[0054] As used herein, the term "circuit" may refer to, include, or be a part of an application-specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and / or memory (shared, dedicated, or group) executing one or more software or firmware programs, a combinational logic circuit, and / or other suitable hardware components that provide the described functionality. In some embodiments, the electronic device circuitry or functions associated with the circuitry may be implemented by one or more software or firmware modules.

[0055] The electronic device circuitry 400 and / or the components of the electronic device circuitry 400 may be configured to perform operations similar to those described elsewhere in this disclosure with respect to the UE 124. In some embodiments, the electronic device circuitry 400 incorporated into or otherwise part of the UE 124 may be configured to perform a method of D2D receive timing selection based on neighboring cell DL signal receive timing measurements for inter-cell D2D operation when the D2D TX (e.g., the UE 112) and the D2D RX (e.g., the UE 124) are associated with neighboring cells, for example, cells 108 and 120.

[0056] In particular, the control circuit 412 may control components of the receive circuit 408 such that a receive window for D2D communication from the UE 112 is determined based on DL signals from the eNB 104.

[0057] The receiving circuit 408 may include an analog-to-digital (A / D) circuit 424 coupled to an FFT circuit 428, which in turn is coupled to an SL demodulation circuit 432. The A / D circuit 424 may receive a baseband signal from the antennas 416 (via one or more intermediate components, such as a downconverter) and perform an analog-to-digital conversion. The digital baseband signal may be provided to the FFT circuit 428. The control circuit 412, which in some embodiments may be within the receiving circuit 408, may determine an FFT window in which the FFT circuit 428 converts waveforms of the baseband signal to the frequency domain to provide a frequency-domain baseband digital sequence.In some embodiments, control circuitry 412 may control a filter in, for example, A / D circuitry 424 or another component to selectively transmit signals within the receive window to FFT circuitry 428. SL demodulation circuitry 432 may receive the frequency-domain baseband digital signal and demodulate the signal based on the signal processing used by the D2D transmitter. SL demodulation circuitry 432 may include such processing as, for example, channel estimation, equalization, demodulation, or decoding.

[0058] Fig. 5 is a flowchart illustrating an operation 500 for determining a receive window according to some embodiments. The operation 500 may be performed by the UE 124. In some embodiments, the operation 500 may be performed by components of the electronic device circuitry 400, including, but not limited to, a control circuitry 412, an A / D circuitry 424, and an FFT circuitry 428.

[0059] Operation 500 may include estimating a DL receive time at 504. The DL receive time estimate may be based on DL signals transmitted by the eNB 104 and received by the UE 124. The DL receive timing may be estimated using processing of regular DL PSS / SSS / CRS signals as part of the cell search and synchronization procedures. The general processing flow for deriving the timing estimate may include: PSS / SSS processing (typically performed before the FFT in the time domain); and a finer timing offset estimation after the FFT using CRS processing (the UE estimates the residual phase offset for symbols containing CRS and thus measures the residual timing offset).

[0060] To provide a DL timing estimate for a neighboring cell, it may be desirable to process neighboring cell DL CRS signals in the frequency domain and estimate the timing offset.

[0061] In various embodiments, the estimation may be performed periodically (e.g., once every several frames), possibly with some filtering in the time domain.

[0062] Operation 500 may include determining a D2D transmission type at 508. Specifically, UE 124 may determine whether a D2D transmission to be received from UE 112 is a PSSCH Mode 1 or another type of D2D transmission (e.g., PSSCH Mode 2, PSCCH, PSDCH, etc.).

[0063] Operation 500 may include determining a receive window at 512. The receive window may be determined based on the estimated DL receive timing and the D2D transmission type. Specifically, if it is determined at 508 that the D2D transmission type is PSSCH Mode 1, the UE 124 may select a receive window using the DL-based D2D signal transmission timing. If it is determined at 508 that the D2D transmission type is not PSSCH Mode 1, the UE 124 may select a receive window using the UL-based D2D signal transmission timing.

[0064] Determining a receive window by referring to the neighboring cell DL timing, as described here, can result in fewer post-FFT errors observed at the D2D receiver side. For example, in a synchronous cross-cell scenario, the cross-cell synchronization accuracy would affect the receive signal timing error in the case where the receive timing is derived from the serving cell DL. For synchronous networks, the eNB synchronization requirements are defined in TS 36.133 (the requirements are defined for TDD networks and can be assumed similarly for synchronous FDD networks). In particular, the cell phase synchronization accuracy measured at the base station (BS) antenna ports can be set to better than 3 µs (microseconds) for cells with a radius of <3 kilometers (km).Therefore, the timing error introduced by imperfect eNB synchronization can be ±3 µs (microseconds) (±92 Ts).

[0065] Embodiments of the present disclosure that derive the D2D RX timing based on the neighboring cell DL timing may not exhibit similar errors. In particular, cell phase synchronization accuracy would not affect D2D receive timing errors because both the D2D TX node and the D2D RX node derive synchronization from the same eNB.

[0066] A D2D signal propagation delay can also be considered when comparing the D2D RX timing based on the serving cell and neighboring cell DL. The D2D receive signal timing offset can depend on propagation delays between the eNodeB and the D2D Tx / Rx nodes and between the D2D Tx and D2D Rx nodes. For the considered cross-cell D2D propagation scenarios described in Fig. 1, the runtime offset can be estimated as follows: D2D−RX−timing based on supply cells−DL:Toffset=TeNB1 / UE1−TeNB2 / UE2+TUE1 / UE2 D2D−RX−timing based on neighboring cells−DL:Toffset=TeNB1 / UE1−TeNB2 / UE1+TUE1 / UE2

[0067] Fig. Figure 6 is a graph 600 illustrating results from a system-level analysis of a received signal timing offset between the D2D RX timing window start and an actually received D2D signal due to propagation. Specifically, the graph 600 compares the cumulative timing offset distribution functions (CDFs) for the case of using two described D2D RX timing selection methods for the inter-cell scenario. Furthermore, the results for intra-cell D2D operation are provided. The following key assumptions were used for the system-level analysis: urban public safety macro-deployment (1732 meters inter-site distance (ISD)); maximum D2D signal coupling loss -130 dBm (for example, with 23 dBm maximum UE transmit power and -107 dB target sensitivity).

[0068] Graph 600 illustrates that the cross-cell scenario using a neighbor-cell DL RX timing avoids the negative timing skew due to signal propagation effects and further reduces the positive timing skew observed at the D2D receiver. This can improve the overall demodulation performance of the D2D receiver.

[0069] Embodiments described herein may be implemented in a system using any suitably configured hardware and / or software. Fig. 7 illustrates, for one embodiment, an example system 700 that may correspond to, and be substantially interchangeable with, the UE 124 or the electronic device circuitry 400. The system 700 may include radio frequency (RF) circuitry 704, baseband circuitry 708, application circuitry 712, memory 716, display 720, camera 724, sensor 728, and input / output (I / O) interface 732, coupled to one another at least as shown.

[0070] Application circuitry 712 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The one or more processors may be any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled to memory 716 and configured to execute instructions stored in memory 716 to enable various applications and / or operating systems to run on system 700.

[0071] The baseband circuitry 708 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The one or more processors may include a baseband processor. The baseband circuitry 708 may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 704. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuitry 708 may provide communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 708 may enable communication with a EUTRAN (through, for example, cell 120) and / or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN) (e.g.,through side links to other D2D devices). Embodiments in which the baseband circuit is configured to support radio connections with more than one radio protocol may be referred to as multi-mode baseband circuitry.

[0072] In various embodiments, baseband circuitry 708 may include circuitry for operating with signals that are not strictly considered to be at a baseband frequency. For example, in some embodiments, the baseband circuitry may include circuitry for operating with signals having an intermediate frequency that lies between a baseband frequency and a radio frequency.

[0073] RF circuitry 704 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, RF circuitry 704 may include switches, filters, amplifiers, etc., to facilitate communication with the wireless network.

[0074] In various embodiments, RF circuitry 704 may include circuitry for operating with signals that are not strictly considered to be at a radio frequency. For example, in some embodiments, RF circuitry 704 may include circuitry for operating with signals having an intermediate frequency that lies between a baseband frequency and a radio frequency.

[0075] In various embodiments, the transmit circuitry 404, the control circuitry 412, and / or the receive circuitry 408 explained or described herein may be embodied in whole or in part in the RF circuitry 704 and / or the baseband circuitry 708 and / or the application circuitry 712.

[0076] In some embodiments, some or all of the components of baseband circuitry 708, application circuitry 712, and / or memory 716 may be implemented together on a system-on-chip (SOC).

[0077] Memory 716 may be used to load and store data and / or instructions, for example, for system 700. Memory 716 for one embodiment may include any suitable combination of volatile memory (e.g., dynamic random access memory (DRAM)) and / or non-volatile memory (e.g., flash memory).

[0078] In various embodiments, the I / O interface 732 may include one or more user interfaces configured to enable user interaction with the system and / or peripheral component interfaces configured to enable peripheral component interaction with the system. The user interfaces may include, but are not limited to, a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. The peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB), an audio jack, and a power interface.

[0079] In various embodiments, sensor 728 may include one or more sensor devices to determine environmental conditions and / or location information related to system 700. In some embodiments, sensor 728 may include, but is not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of or interact with baseband circuitry 708 and / or RF circuitry 704 to communicate with components of a positioning network, such as global positioning system (GPS) satellites.

[0080] In various embodiments, the display 720 may include a display (e.g., a liquid crystal display, a touch screen display, etc.).

[0081] In various embodiments, system 700 may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, etc. In various embodiments, system 700 may include more or fewer components and / or different architectures.

[0082] Fig. Figure 8 illustrates a computing device 800 incorporating aspects of the present disclosure according to various embodiments. In various embodiments, the computing device 800 may be used to implement various embodiments of the present disclosure.

[0083] As shown, computing device 800 may include storage media 808, where RX logic 812 may be configured to implement embodiments or aspects of embodiments of any of the processes described herein. Storage media 808 may represent a variety of persistent storage media known in the art, including, but not limited to, flash memory, dynamic random access memory, static random access memory, optical disk, magnetic disk, etc. In embodiments, storage media 808 may include one or more computer-readable non-transitory storage media. In other embodiments, storage media 808 may be volatile, such as signals encrypted with RX logic 812.

[0084] In various embodiments, RX logic 812 may enable a device, such as UE 124, to perform various operations described herein in response to their execution by one or more processors 804. As an example, RX logic 812 may include instructions that, when executed, control UE 124 to determine D2D receive signal timing based on signals from a neighboring cell.

[0085] The following sections describe examples of various embodiments.

[0086] Example 1 includes one or more computer-readable media, which may be non-transitory, and having instructions that, when executed, direct a first user equipment (UE) to: associate with a first cell provided by a first evolved node B (eNB); estimate a downlink reception time

[0087] (DL reception time) corresponding to a second cell provided by a second eNB; and determining a reception window for receiving communication from a second UE associated with the second cell provided by the second eNB based on the estimate of the DL reception time corresponding to the second cell.

[0088] Example 2 includes the one or more computer-readable media of Example 1, wherein the instructions, when executed, further control the first UE to: determine the receive window for receiving communication based on a specific offset for time division duplex (TDD).

[0089] Example 3 includes the one or more computer-readable media of any of Examples 1-2, wherein the instructions, when executed, further control the first UE to: determine the receive window to receive communication based on a D2D transmit lead time (D2D transmit TA) compensation value.

[0090] Example 4 includes the one or more computer-readable media of Example 3, wherein the D2D transmit TA compensation value is signaled in sidelink control information transmitted in a physical sidelink control channel (PSCCH).

[0091] Example 5 includes the one or more computer-readable media of Example 3, wherein the instructions, when executed, further control the first UE to: determine the receive window to receive communication based on a product of the D2D transmit TA compensation value and a sampling duration.

[0092] Example 6 includes the one or more computer-readable media of any of Examples 1-5, wherein the instructions, when executed, further control the first UE to: determine the receive window for receiving communication based on an implementation-specific offset to shift a time window for an individual D2D transmit timing offset or average timing offset statistics from multiple D2D transmitters, or to compensate for downlink timing measurement errors.

[0093] Example 7 includes the one or more computer-readable media of any of Examples 1-6, wherein the instructions, when executed, further control the first UE to: determine the receive window for receiving communication based on a downlink-based D2D signal transmission timing.

[0094] Example 8 includes the one or more computer-readable media of any of Examples 1-7, wherein the instructions, when executed, further control the first UE to: determine the receive window based on an uplink-based D2D signal transmission timing.

[0095] Example 9 includes the one or more computer-readable media of any of Examples 1-8, wherein the instructions, when executed, further control the first UE to: determine the receive window based on a downlink-based D2D signal transmission timing.

[0096] Example 10 includes an apparatus comprising: a receive circuit to receive and process cellular communication signals and device communication signals, wherein the receive circuit is to include a fast Fourier transform (FFT) circuit to provide a frequency-domain baseband digital sequence based on the device communication signals; and a control circuit coupled to the FFT circuit, wherein the control circuit is configured to: estimate a downlink (DL) receive time based on one or more signals from a neighboring cell; determine a transmission type of the device communication signals; and determine an FFT window for the FFT circuit to receive the device communication signals based on the estimate of the DL receive time and the transmission type.

[0097] Example 11 includes the apparatus of Example 10, wherein the control circuit is configured to determine that the transmission type is a Physical Sidelink Common Channel (PSSCH) Mode 1 transmission and to determine the FFT window using a DL-based D2D signal transmission timing.

[0098] Example 12 includes the apparatus of Example 11, wherein the control circuit is configured to determine a D2D RX timing parameter (T D2D_RX ), which indicates a start of the FFT window based on T D2D_RX =T DL_RX_eNB1 -N TA,OFFSET ×T S +Δ, where T DL_RX_eNB1 the estimate of the DL reception time, N TA , OFFSET a time-division duplex-specific (TDD-specific) offset, T S is a sampling period and Δ is an offset specific to a user equipment (UE) implementation.

[0099] Example 13 includes the apparatus of Example 12, wherein Δ is to shift the FFT window for an individual D2D transmit timing offset or average timing offset statistics from multiple D2D transmitters or to compensate for downlink timing measurement errors.

[0100] Example 14 comprises the device of Example 13, wherein Δ „ -T CP / 2", where TCP is a duration of a cyclic prefix (CP) of a D2D signal.

[0101] Example 15 includes the apparatus of any of Examples 10-14, wherein the control circuit is configured to determine that the transmission type is not a Physical Sidelink Common Channel (PSSCH) Mode 1 transmission and to determine the FFT window using a UL-based D2D signal transmission timing.

[0102] Example 16 includes the apparatus of Example 15, wherein the control circuit is configured to determine a D2D RX timing parameter (T D2D_RX ), which indicates a start of the FFT window based on T D2D_RX =T DL_RX_eNB1 -N TA,OFFSET ×T S -N TA_D2D ×T S +Δ, where T DL_RX_eNB1 the estimate of the DL reception time, N TA , OFFSET a time-division duplex-specific (TDD-specific) offset, T S a sampling period, N TA_D2D is a component for compensating a D2D TX lead time (D2D TX TA) and Δ is an offset specific to a user equipment (UE) implementation.

[0103] Example 17 includes the apparatus of Example 16, wherein the device communication signals comprise a PSSCH Mode 2 transmission from a single source in a transmit time interval (TTI), and N TA_D2Dis equal to a D2D TA command signaled in a side link control information (SCI) format 0.

[0104] Example 18 includes the apparatus of Example 16, wherein the device communication signals comprise a PSSCH Mode 2 transmission from multiple sources in a transmission time interval (TTI), and N TA_D2D is equal to a D2D TA command signaled in a side link control information (SCI) format 0.

[0105] Example 19 includes one or more computer-readable media, which may be non-transitory, comprising instructions that, when executed, control a device to: estimate a downlink (DL) receive time based on one or more signals from a neighboring cell; determine a transmission type of device communication signals; and determine a receive window for a receive circuit to receive the device communication signals based on the estimate of the DL receive time and the transmission type.

[0106] Example 20 includes the one or more computer-readable media of Example 19, wherein the one or more signals from the neighboring cell comprise primary synchronization signals, secondary synchronization signals, or channel reference signals.

[0107] Example 21 includes the one or more computer-readable media of any of Examples 19-20, wherein the instructions, when executed, further control the device to: determine that the transmission type is a Mode 1 Physical Common Sidelink Channel (PSSCH) transmission; and determine the receive window using a DL-based D2D signal transmission timing.

[0108] Example 22 includes the one or more computer-readable media of Example 21, wherein the instructions, when executed, further control the device to: determine a D2D RX timing parameter T D2D_RX , which indicates a start of the reception window based on: T D2D_RX =T DL_RX_eNB1 -N TA,OFFSET ×T S +Δ, where T DL_RX_eNB1 the estimate of the DL reception time, N TA , OFFSET a time-division duplex-specific (TDD-specific) offset, T Sis a sampling period and Δ is an offset specific to a user equipment (UE) implementation.

[0109] Example 23 includes the one or more computer-readable media of Example 22, wherein Δ is to shift the receive window for an individual D2D transmit timing offset or average timing offset statistics from multiple D2D transmitters or to compensate for downlink timing measurement errors.

[0110] Example 24 includes the one or more computer-readable media of Example 23, wherein Δ „ -TCP / 2", where TCP is a duration of a cyclic prefix (CP) of a D2D signal.

[0111] Example 25 includes the one or more computer-readable media of any of Examples 19-24, wherein the instructions, when executed, further control the device to: determine that the transmission type is not a Mode 1 Physical Common Sidelink Channel (PSSCH) transmission; and determine the receive window using a UL-based D2D signal transmission timing.

[0112] Example 26 includes the one or more computer-readable media of Example 25, wherein the instructions, when executed, further control the device to: determine a D2D RX timing parameter (T D2D_RX ), which indicates a start of the receive window based on T D2D_RX =T DL_RX_eNB1 -N TΆ,OFFSET ×T S -N TA_D2D ×T S +Δ, where T DL_RX_eNB1 the estimate of the DL reception time, N TA , OFFSET a time-division duplex-specific (TDD-specific) offset, TS a sampling period, N TA_D2D is a component for compensating a D2D TX lead time (D2D TX TA) and Δ is an offset specific to a user equipment (UE) implementation.

[0113] Example 27 includes the one or more computer-readable media of Example 26, wherein the D2D signals comprise a PSSCH Mode 2 transmission from a single source in a transmission time interval (TTI), and N TA_D2D is equal to a D2D TA command signaled in a side link control information (SCI) format 0.

[0114] Example 28 includes the one or more computer-readable media of Example 26, wherein the D2D signals comprise PSSCH Mode 2 transmission from multiple sources in a transmission time interval (TTI), and N TA_D2D is equal to a D2D TA command signaled in a side link control information (SCI) format 0.

[0115] Example 29 includes a method comprising: associating, by a first terminal equipment (UE), a first cell provided by a first evolved node B (eNB); estimating a downlink (DL) receive time corresponding to a second cell provided by a second eNB; and determining a receive window for receiving communication from a second UE associated with the second cell provided by the second eNB based on the estimate of the DL receive time corresponding to the second cell.

[0116] Example 30 includes the method of Example 29, further comprising: determining the receive window for receiving D2D communication based on a time division duplex (TDD) specific offset.

[0117] Example 31 includes the method of any of Examples 29-30, further comprising: determining the receive window for receiving D2D communication based on a D2D transmit lead time (D2D transmit TA) compensation value.

[0118] Example 32 includes the method of Example 31, wherein the D2D transmit TA compensation value is signaled in sidelink control information transmitted in a physical sidelink control channel (PSCCH).

[0119] Example 33 includes the method of Example 31, further comprising: determining the receive window for receiving D2D communication based on a product of the D2D transmit TA compensation value and a sampling duration.

[0120] Example 34 includes the method of any of Examples 29-33, further comprising: determining the receive window for receiving D2D communication based on an implementation-specific offset to shift a time window for an individual D2D transmit timing offset or average timing offset statistics from multiple D2D transmitters or to compensate for downlink timing measurement errors.

[0121] Example 35 includes the method of any of Examples 29-34, further comprising: determining the receive window for receiving D2D communication based on a downlink-based D2D signal transmission timing.

[0122] Example 36 includes the method of any of Examples 29-35, further comprising: determining the receive window based on an uplink-based D2D signal transmission timing.

[0123] Example 37 includes the method of any of Examples 29-36, further comprising: determining the receive window based on a downlink-based D2D signal transmission timing.

[0124] Example 38 includes a method comprising: estimating a downlink (DL) receive time based on one or more signals from a neighboring cell; determining a transmission type of device communication signals; and determining a receive window for a receive circuit to receive the device communication signals based on the estimate of the DL receive time and the transmission type.

[0125] Example 39 includes the method of Example 38, wherein the one or more signals from the neighboring cell comprise primary synchronization signals, secondary synchronization signals, or channel reference signals.

[0126] Example 40 includes the method of any of Examples 38-39, further comprising: determining that the D2D transmission type is a Physical Common Sidelink Channel (PSSCH) Mode 1 transmission, and determining the receive window using a DL-based D2D signal transmission timing.

[0127] Example 41 includes the method of Example 40, further comprising: determining a D2D RX timing parameter T D2D_RX , which indicates a start of the receive window based on T D2D_RX =T DL_RX_eNB1 -N TA,OFFSET ×T S +Δ, where T DL_RX_eNB1 the estimate of the DL reception time, N TA , OFFSET a time-division duplex-specific (TDD-specific) offset, T S is a sampling period and Δ is an offset specific to a user equipment (UE) implementation.

[0128] Example 42 includes the method of Example 41, wherein Δ is to shift the receive window for an individual D2D transmit timing offset or average timing offset statistics from multiple D2D transmitters or to compensate for downlink timing measurement errors.

[0129] Example 43 includes the method of any one of Examples 41-42, wherein Δ „ -TCP / 2", where TCP is a duration of a cyclic prefix (CP) of a D2D signal.

[0130] Example 44 includes the method of any of Examples 38-43, further comprising: determining that the D2D transmission type is not a Physical Common Sidelink Channel (PSSCH) Mode 1 transmission, and determining the receive window using a UL-based D2D signal transmission timing.

[0131] Example 45 includes the method of Example 44, further comprising: determining a D2D RX timing parameter (T D2D_RX ), which indicates a start of the receive window based on T D2D_RX =T DL_RX_eMB1 -N TA,OFFSET ×T S -N TA_D2D ×T S +Δ, where T DL_RX_eNB1 the estimate of the DL reception time, N TA , OFFSET a time-division duplex-specific (TDD-specific) offset, T S a sampling period, N TA_D2D is a component for compensating a D2D TX lead time (D2D TX TA) and Δ is an offset specific to a user equipment (UE) implementation.

[0132] Example 46 includes the method of Example 45, wherein the device communication signals comprise a PSSCH Mode 2 transmission from a single source in a transmit time interval (TTI), and N TA_D2D is equal to a D2D TA command signaled in a side link control information (SCI) format 0.

[0133] Example 47 includes the method of Example 45, wherein the device communication signals comprise a PSSCH Mode 2 transmission from multiple sources in a transmission time interval (TTI), and N TA_D2D is equal to a D2D TA command signaled in a side link control information (SCI) format 0.

[0134] Example 48 includes an apparatus having circuitry configured to perform any of Methods 29-47.

[0135] Example 49 includes an apparatus having means to perform any of Methods 29-47.

[0136] The description of illustrated implementations herein, including what is described in the abstract, is not intended to be exhaustive or to limit the present invention to the precise forms disclosed. Although specific implementations and examples are described for illustrative purposes, numerous alternative and / or equivalent embodiments or implementations designed to achieve the same purposes may be devised in light of the above detailed description without departing from the scope of the present disclosure, as will be appreciated by those skilled in the relevant art.

Claims

[1] Computer-readable medium or media containing instructions that, when executed, control a first user equipment (UE) to: Assigning to a first cell provided by a first evolved node B (eNB); Estimating a downlink (DL) reception time corresponding to a second cell provided by a second eNB using processing of regular DL PSS / SSS / CRS signals; and Determining a fast Fourier transform receive window for receiving communication from a second UE associated with the second cell provided by the second eNB based on the DL receive time estimate corresponding to the second cell. [2] The computer-readable medium or media of claim 1, wherein the instructions, when executed, further control the first UE to: determine the receive window for receiving communication based on a time division duplex (TDD) specific offset. [3] The computer-readable medium or computer-readable media of claim 1, wherein the instructions, when executed, further control the first UE to: determine the receive window for receiving communication based on a D2D transmit lead time (TA) compensation value. [4] The computer-readable medium or computer-readable media of claim 3, wherein the D2D transmit TA compensation value is signaled in sidelink control information transmitted in a physical sidelink control channel (PSCCH). [5] The computer-readable medium or computer-readable media of claim 3, wherein the instructions, when executed, further control the first UE to: determine the receive window for receiving communication based on a product of the D2D transmit TA compensation value and a sampling period. [6] The computer-readable medium or computer-readable media of any of claims 1-5, wherein the instructions, when executed, further control the first UE to: determine the receive window for receiving communication based on an implementation-specific offset to shift a time window for an individual D2D transmit timing offset or average timing offset statistics from multiple D2D transmitters, or to compensate for downlink timing measurement errors. [7] The computer-readable medium or computer-readable media of any of claims 1-5, wherein the instructions, when executed, further control the first UE to: determine the receive window for receiving communication based on a downlink-based D2D signal transmission timing. [8] The computer-readable medium or computer-readable media of any of claims 1-5, wherein the instructions, when executed, further control the first UE to: determine the receive window based on an uplink-based D2D signal transmission timing. [9] Device comprising: a receiving circuit for receiving and processing cellular communication signals and device communication signals, the receiving circuit comprising a fast Fourier transform (FFT) circuit for providing a frequency-domain baseband digital sequence based on the device communication signals; and a control circuit coupled to the FFT circuit, the control circuit being configured to: Estimating a downlink (DL) reception time based on one or more signals from a neighboring cell using processing of regular DL PSS / SSS / CRS signals; Determining a transmission type of the device communication signals; and Determining an FFT window for the FFT circuit to receive the device communication signals based on the DL receive time estimate and the transmission type. [10] The apparatus of claim 9, wherein the control circuit is configured to determine that the transmission type is a mode 1 physical sidelink common channel (PSSCH) transmission and to determine the FFT window using a DL-based D2D signal transmission timing. [11] The apparatus of claim 10, wherein the control circuit is configured to determine a D2D RX timing parameter (T D2D_RX ), which indicates a start of the FFT window based on T D2D_RX =T DL_RX_eNB1 -N TA,OFFSET ×T S +Δ, where T DL_RX_eNB1 the estimate of the DL reception time, N TA , OFFSET a time-division duplex-specific (TDD-specific) offset, T S is a sampling duration and Δ is an offset specific to a User Equipment (UE) implementation. [12] The apparatus of claim 11, wherein Δ shifts the FFT window for an individual D2D transmit timing offset or average timing offset statistics from multiple D2D transmitters or compensates for downlink timing measurement errors. [13] Device according to claim 12, wherein Δ „ -T CP / 2", where TCP is a duration of a cyclic prefix (CP) of a D2D signal. [14] The apparatus of claim 9, wherein the control circuit is configured to determine that the transmission type is not a Physical Sidelink Common Channel (PSSCH) Mode 1 transmission and to determine the FFT window using a UL-based D2D signal transmission timing. [15] The apparatus of claim 14, wherein the control circuit is configured to determine a D2D RX timing parameter (T D2D_RX ), which indicates a start of the FFT window based on T D2D_RX =T DL_RX_eNB1 -NTA,OFFSET ×T S -N TA_D2D ×T S +Δ, where T DL_RX_eNB1 the estimate of the DL reception time, N TA , OFFSET a time-division duplex-specific (TDD-specific) offset, T S a sampling period, N TA_D2D is a component for compensating a D2D-TX lead time (D2D-TX-TA) and Δ is an offset specific to a User Equipment (UE) implementation. [16] The apparatus of claim 15, wherein the device communication signals comprise a PSSCH Mode 2 transmission from a single source in a transmit time interval (TTI), and N TA_D2D is equal to a D2D TA command signaled in a side link control information (SCI) format 0. [17] The apparatus of claim 15, wherein the device communication signals comprise PSSCH Mode 2 transmission from multiple sources in a transmission time interval (TTI), and N TA_D2Dis equal to a D2D TA command signaled in a side link control information (SCI) format 0. [18] Computer-readable medium or media containing instructions which, when executed, control a device to: Estimating a downlink (DL) reception time based on one or more signals from a neighboring cell using processing of regular DL PSS / SSS / CRS signals; Determining a transmission type of device communication signals; and Determining a fast Fourier transform receive window for a receive circuit to receive the device communication signals based on the DL receive time estimate and the transmission type. [19] The computer-readable medium or computer-readable media of claim 18, wherein the one or more signals from the neighboring cell comprise primary synchronization signals, secondary synchronization signals, or channel reference signals. [20] The computer-readable medium or media of claim 18, wherein the instructions, when executed, further control the device to: determine that the transmission type is a Mode 1 Physical Common Sidelink Channel (PSSCH) transmission; and determine the receive window using a DL-based D2D signal transmission timing. [21] The computer-readable medium or media of claim 20, wherein the instructions, when executed, further control the device to: determine a D2D RX timing parameter T D2D_RX , which indicates a start of the receive window based on T D2D_RX =T DL_RX_eNB1 -N TA,OFFSET ×TS +Δ, where T DL_RX_eNB1 the estimate of the DL reception time, N TA , OFFSET a time-division duplex-specific (TDD-specific) offset, T S is a sampling duration and Δ is an offset specific to a User Equipment (UE) implementation. [22] The computer-readable medium or computer-readable media of claim 21, wherein Δ shifts the receive window for an individual D2D transmit timing offset or average timing offset statistics from multiple D2D transmitters or compensates for downlink timing measurement errors. [23] The computer-readable medium or computer-readable media of claim 22, wherein Δ „ -TCP / 2", where TCP is a duration of a cyclic prefix (CP) of a D2D signal. [24] The computer-readable medium or media of any of claims 18-23, wherein the instructions, when executed, further control the device to: Determining that the transmission type is not a Physical Sidelink Common Channel (PSSCH) Mode 1 transmission, and determining the receive window using a UL-based D2D signal transmission timing.

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