Showing papers by "Qualcomm published in 2014"

Spatially Sparse Precoding in Millimeter Wave MIMO Systems

Abstract: Millimeter wave (mmWave) signals experience orders-of-magnitude more pathloss than the microwave signals currently used in most wireless applications and all cellular systems. MmWave systems must therefore leverage large antenna arrays, made possible by the decrease in wavelength, to combat pathloss with beamforming gain. Beamforming with multiple data streams, known as precoding, can be used to further improve mmWave spectral efficiency. Both beamforming and precoding are done digitally at baseband in traditional multi-antenna systems. The high cost and power consumption of mixed-signal devices in mmWave systems, however, make analog processing in the RF domain more attractive. This hardware limitation restricts the feasible set of precoders and combiners that can be applied by practical mmWave transceivers. In this paper, we consider transmit precoding and receiver combining in mmWave systems with large antenna arrays. We exploit the spatial structure of mmWave channels to formulate the precoding/combining problem as a sparse reconstruction problem. Using the principle of basis pursuit, we develop algorithms that accurately approximate optimal unconstrained precoders and combiners such that they can be implemented in low-cost RF hardware. We present numerical results on the performance of the proposed algorithms and show that they allow mmWave systems to approach their unconstrained performance limits, even when transceiver hardware constraints are considered.

Channel Estimation and Hybrid Precoding for Millimeter Wave Cellular Systems

Abstract: Millimeter wave (mmWave) cellular systems will enable gigabit-per-second data rates thanks to the large bandwidth available at mmWave frequencies. To realize sufficient link margin, mmWave systems will employ directional beamforming with large antenna arrays at both the transmitter and receiver. Due to the high cost and power consumption of gigasample mixed-signal devices, mmWave precoding will likely be divided among the analog and digital domains. The large number of antennas and the presence of analog beamforming requires the development of mmWave-specific channel estimation and precoding algorithms. This paper develops an adaptive algorithm to estimate the mmWave channel parameters that exploits the poor scattering nature of the channel. To enable the efficient operation of this algorithm, a novel hierarchical multi-resolution codebook is designed to construct training beamforming vectors with different beamwidths. For single-path channels, an upper bound on the estimation error probability using the proposed algorithm is derived, and some insights into the efficient allocation of the training power among the adaptive stages of the algorithm are obtained. The adaptive channel estimation algorithm is then extended to the multi-path case relying on the sparse nature of the channel. Using the estimated channel, this paper proposes a new hybrid analog/digital precoding algorithm that overcomes the hardware constraints on the analog-only beamforming, and approaches the performance of digital solutions. Simulation results show that the proposed low-complexity channel estimation algorithm achieves comparable precoding gains compared to exhaustive channel training algorithms. The results illustrate that the proposed channel estimation and precoding algorithms can approach the coverage probability achieved by perfect channel knowledge even in the presence of interference.

Network densification: the dominant theme for wireless evolution into 5G

Abstract: This article explores network densification as the key mechanism for wireless evolution over the next decade. Network densification includes densification over space (e.g, dense deployment of small cells) and frequency (utilizing larger portions of radio spectrum in diverse bands). Large-scale cost-effective spatial densification is facilitated by self-organizing networks and intercell interference management. Full benefits of network densification can be realized only if it is complemented by backhaul densification, and advanced receivers capable of interference cancellation.

Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey

Abstract: This paper provides a comprehensive review of the domain of physical layer security in multiuser wireless networks. The essential premise of physical layer security is to enable the exchange of confidential messages over a wireless medium in the presence of unauthorized eavesdroppers, without relying on higher-layer encryption. This can be achieved primarily in two ways: without the need for a secret key by intelligently designing transmit coding strategies, or by exploiting the wireless communication medium to develop secret keys over public channels. The survey begins with an overview of the foundations dating back to the pioneering work of Shannon and Wyner on information-theoretic security. We then describe the evolution of secure transmission strategies from point-to-point channels to multiple-antenna systems, followed by generalizations to multiuser broadcast, multiple-access, interference, and relay networks. Secret-key generation and establishment protocols based on physical layer mechanisms are subsequently covered. Approaches for secrecy based on channel coding design are then examined, along with a description of inter-disciplinary approaches based on game theory and stochastic geometry. The associated problem of physical layer message authentication is also briefly introduced. The survey concludes with observations on potential research directions in this area.

MAGIC—Memristor-Aided Logic

Abstract: Memristors are passive components with a varying resistance that depends on the previous voltage applied across the device. While memristors are naturally used as memory, memristors can also be used for other applications, including logic circuits. In this brief, a memristor-only logic family, i.e., memristor-aided logic (MAGIC), is presented. In each MAGIC logic gate, memristors serve as an input with previously stored data, and an additional memristor serves as an output. The topology of a MAGIC nor gate is similar to the structure of a common memristor-based crossbar memory array. A MAGIC nor gate can therefore be placed within memory, providing opportunities for novel non-von Neumann computer architectures. Other MAGIC gates also exist (e.g., and , or , not , and nand ) and are described in this brief.

Modeling and Discovering Vulnerabilities with Code Property Graphs

Abstract: The vast majority of security breaches encountered today are a direct result of insecure code. Consequently, the protection of computer systems critically depends on the rigorous identification of vulnerabilities in software, a tedious and error-prone process requiring significant expertise. Unfortunately, a single flaw suffices to undermine the security of a system and thus the sheer amount of code to audit plays into the attacker's cards. In this paper, we present a method to effectively mine large amounts of source code for vulnerabilities. To this end, we introduce a novel representation of source code called a code property graph that merges concepts of classic program analysis, namely abstract syntax trees, control flow graphs and program dependence graphs, into a joint data structure. This comprehensive representation enables us to elegantly model templates for common vulnerabilities with graph traversals that, for instance, can identify buffer overflows, integer overflows, format string vulnerabilities, or memory disclosures. We implement our approach using a popular graph database and demonstrate its efficacy by identifying 18 previously unknown vulnerabilities in the source code of the Linux kernel.

Space–time wiring specificity supports direction selectivity in the retina

Abstract: How does the mammalian retina detect motion? This classic problem in visual neuroscience has remained unsolved for 50 years. In search of clues, here we reconstruct Off-type starburst amacrine cells (SACs) and bipolar cells (BCs) in serial electron microscopic images with help from EyeWire, an online community of ‘citizen neuroscientists’. On the basis of quantitative analyses of contact area and branch depth in the retina, we find evidence that one BC type prefers to wire with a SAC dendrite near the SAC soma, whereas another BC type prefers to wire far from the soma. The near type is known to lag the far type in time of visual response. A mathematical model shows how such ‘space–time wiring specificity’ could endow SAC dendrites with receptive fields that are oriented in space–time and therefore respond selectively to stimuli that move in the outward direction from the soma. Motion detection by the retina is thought to rely largely on the biophysics of starburst amacrine cell dendrites; here machine learning is used with gamified crowdsourcing to draw the wiring diagram involving amacrine and bipolar cells to identify a plausible circuit mechanism for direction selectivity; the model suggests similarities between mammalian and insect vision. Motion detection by the mammalian retina has been thought to rely largely on the intrinsic biophysics of the dendrites of starburst amacrine cells (SACs). Now Sebastian Seung and colleagues have combined new machine-learning techniques with crowd sourcing via the EyeWire brain-mapping game to redraw the wiring diagram for amacrine cells and bipolar cells. Their results show that direction selectivity is established at the presynaptic level — in the spatiotemporal inputs to the amacrine cells — identifying neural circuits rather than intrinsic properties of SACs as the key to direction selectivity. This new model brings the mouse retina closer in certain respects to the Reichardt motion detector characteristic of insect vision.

Adaptive Observation of Behavioral Features on a Mobile Device

Abstract: Methods, devices and systems for detecting suspicious or performance-degrading mobile device behaviors intelligently, dynamically, and/or adaptively determine computing device behaviors that are to be observed, the number of behaviors that are to be observed, and the level of detail or granularity at which the mobile device behaviors are to be observed. The various aspects efficiently identify suspicious or performance-degrading mobile device behaviors without requiring an excessive amount of processing, memory, or energy resources.

Downlink Cellular Network Analysis with Multi-slope Path Loss Models

Abstract: Existing cellular network analyses, and even simulations, typically use the standard path loss model where received power decays like $\|x\|^{-\alpha}$ over a distance $\|x\|$. This standard path loss model is quite idealized, and in most scenarios the path loss exponent $\alpha$ is itself a function of $\|x\|$, typically an increasing one. Enforcing a single path loss exponent can lead to orders of magnitude differences in average received and interference powers versus the true values. In this paper we study \emph{multi-slope} path loss models, where different distance ranges are subject to different path loss exponents. We focus on the dual-slope path loss function, which is a piece-wise power law and continuous and accurately approximates many practical scenarios. We derive the distributions of SIR, SNR, and finally SINR before finding the potential throughput scaling, which provides insight on the observed cell-splitting rate gain. The exact mathematical results show that the SIR monotonically decreases with network density, while the converse is true for SNR, and thus the network coverage probability in terms of SINR is maximized at some finite density. With ultra-densification (network density goes to infinity), there exists a \emph{phase transition} in the near-field path loss exponent $\alpha_0$: if $\alpha_0 >1$ unbounded potential throughput can be achieved asymptotically; if $\alpha_0 <1$, ultra-densification leads in the extreme case to zero throughput.

Discovering cloud-based services for iot devices in an iot network associated with a user

Abstract: The disclosure relates to discovering and offering cloud-based services for Internet of Things (IoT) devices in an IoT network. In particular, an IoT gateway or other suitable device can discover information (e.g., device classes) about the IoT devices in the IoT network, discover cloud-based services tagged with the discovered information about the IoT devices, and offer the discovered cloud-based services in the IoT network. Accordingly, in response to receiving a request to invoke a discovered cloud-based service from an IoT device and/or a user associated with the IoT network, the IoT gateway may connect to the appropriate IoT devices to fetch any required data associated with the requested cloud-based services, pass the fetched data to publishers or providers associated with the requested cloud-based services, and return a result from the invoked cloud-based services to the IoT devices in the IoT network.

Methods to discover, configure, and leverage relationships in internet of things (IoT) networks

Abstract: The disclosure generally relates to various methods to discover, configure, and leverage relationships in Internet of Things (IoT) networks. More particularly, the methods disclosed herein may support automated processes to create configurable sub-divisions and access controls in an IoT network based on usage associated with objects that are registered in the IoT network and interactions among the registered objects. Furthermore, in one embodiment, relationships between IoT devices that belong to different users may be implicitly discovered and/or ranked based on meetings (e.g., interactions) between the IoT devices, and relationships between the different users may likewise be implicitly discovered and/or ranked. Moreover, locations and interactions associated with IoT devices may be tracked over time to further discover user-specific and potentially asymmetric relationships among the IoT devices and/or the users associated therewith (e.g., where one user considers another user a close friend and the other user considers the first user an acquaintance).

Methods, systems and devices for delivery drone security

Abstract: Methods, systems and devices are provided for securing a drone delivering a package of goods to a delivery destination. A notification may be provided to a device of the purchaser that the drone has arrived near the delivery destination. The drone may hover at a secure altitude from a landing zone at the delivery destination. The drone may receive a purchase code associated with a purchase of the package of goods. The drone may authenticate the purchase code as a condition for landing. The drone may land in the landing zone at the delivery destination when the purchase code is authenticated. The drone may abort the landing when the purchase code is not authenticated. The drone may receive a delivery code associated with completing delivery the package of goods. The drone may require the delivery code as a condition for releasing the package of goods.

Server-assisted device-to-device discovery and connection

Abstract: A method includes receiving, at a network node, a device-to-device D2D discovery request from a first device and sending a D2D discovery response from the network node to the first device. The D2D discovery response includes information associated with a second device that is available to establish a D2D connection with the first device. The network node may perform inquiries regarding D2D connection permission from both devices. If D2D connection is permitted by both devices, the network node may facilitate the D2D scanning by sending each device's scanning information to the other device via a non-D2D link. In parallel to D2D scanning, the network node may speed up D2D link setup by distributing, via non-D2D links, link setup information to each device, where the link setup information may include device credential(s), IP address allocation(s), and/or group owner assignment.

Adaptive OFDM Modulation for Underwater Acoustic Communications: Design Considerations and Experimental Results

Abstract: In this paper, we explore design aspects of adaptive modulation based on orthogonal frequency-division multiplexing (OFDM) for underwater acoustic (UWA) communications, and study its performance using real-time at-sea experiments. Our design criterion is to maximize the system throughput under a target average bit error rate (BER). We consider two different schemes based on the level of adaptivity: in the first scheme, only the modulation levels are adjusted while the power is allocated uniformly across the subcarriers, whereas in the second scheme, both the modulation levels and the power are adjusted adaptively. For both schemes we linearly predict the channel one travel time ahead so as to improve the performance in the presence of a long propagation delay. The system design assumes a feedback link from the receiver that is exploited in two forms: one that conveys the modulation alphabet and quantized power levels to be used for each subcarrier, and the other that conveys a quantized estimate of the sparse channel impulse response. The second approach is shown to be advantageous, as it requires significantly fewer feedback bits for the same system throughput. The effectiveness of the proposed adaptive schemes is demonstrated using computer simulations, real channel measurements recorded in shallow water off the western coast of Kauai, HI, USA, in June 2008, and real-time at-sea experiments conducted at the same location in July 2011. We note that this is the first paper that presents adaptive modulation results for UWA links with real-time at-sea experiments.

Feasible Point Pursuit and Successive Approximation of Non-convex QCQPs

Abstract: Quadratically constrained quadratic programs (QCQPs) have a wide range of applications in signal processing and wireless communications. Non-convex QCQPs are NP-hard in general. Existing approaches relax the non-convexity using semi-definite relaxation (SDR) or linearize the non-convex part and solve the resulting convex problem. However, these techniques are seldom successful in even obtaining a feasible solution when the QCQP matrices are indefinite. In this paper, a new feasible point pursuit successive convex approximation (FPP-SCA) algorithm is proposed for non-convex QCQPs. FPP-SCA linearizes the non-convex parts of the problem as conventional SCA does, but adds slack variables to sustain feasibility, and a penalty to ensure slacks are sparingly used. When FPP-SCA is successful in identifying a feasible point of the non-convex QCQP, convergence to a Karush-Kuhn-Tucker (KKT) point is thereafter ensured. Simulations show the effectiveness of our proposed algorithm in obtaining feasible and near-optimal solutions, significantly outperforming existing approaches.

Methods and apparatus for multiple user uplink

Abstract: Methods and apparatus for multiple user uplink are provided. In one aspect, a method for wireless communication is provided. The method includes transmitting a clear to transmit (CTX) message to two or more stations, the CTX indicating an uplink transmission opportunity, the CTX message further comprising a request that the two or more stations concurrently transmit uplink data at a specific time. The method further includes receiving a plurality of uplink data from at least two stations at the specific time.

Secure Transmission With Antenna Selection in MIMO Nakagami-m Fading Channels

Abstract: This paper considers transmit antenna selection (TAS) and receive generalized selection combining (GSC) for se- cure communication in the multiple-input-multiple-output wire- tap channel, where confidential messages transmitted from an NA-antenna transmitter to an NB-antenna legitimate receiver are overheard by an NE-antenna eavesdropper. We assume that the main channel and the eavesdropper's channel undergo Nakagami-m fading with fading parameters mB and mE ,r e- spectively. In order to assess the secrecy performance, we present a new unifying framework for the average secrecy rate and the se- crecy outage probability. We first derive expressions for the prob- ability density function and the cumulative distribution function of the signal-to-noise ratio with TAS/GSC, from which we derive exact expressions for the average secrecy rate and the secrecy outage probability. We then derive compact expressions for the asymptotic average secrecy rate and the asymptotic secrecy outage probability for two distinct scenarios: 1) the legitimate receiver is located close to the transmitter, and 2) the legitimate receiver and the eavesdropper are located close to the transmitter. For these scenarios, we present new closed-form expressions for several key performance indicators: 1) the capacity slope and the power offset of the asymptotic average secrecy rate, and 2) the secrecy diversity order and the secrecy array gain of the asymptotic secrecy outage probability. For the first scenario, we confirm that the capacity slope is one and the secrecy diversity order is mBNBNA .F or the second scenario, we confirm that the capacity slope and the secrecy diversity order collapse to zero.

Techniques for selecting subframe type or for interleaving signals for wireless communications over unlicensed spectrum

Abstract: Methods and apparatuses are described in which an unlicensed spectrum is used for Long Term Evolution (LTE) communications. A first method includes comparing past transmission activity on an unlicensed spectrum to an activity threshold, transmitting a first subframe type in the unlicensed spectrum during a next active transmission when the past transmission activity is greater than the activity threshold, and transmitting a second subframe type in the unlicensed spectrum during a next active transmission when the past transmission activity is lesser than the activity threshold, the second subframe type comprising a more robust subframe type than the first subframe type. A second method includes generating one or both of PUCCH signals and PUSCH signals based on interleaved signals that increase nominal bandwidth occupancy in an unlicensed spectrum, and transmitting the generated signals in the unlicensed spectrum. A third method includes receiving the PUCCH signals and the PUSCH signals.

Human-body-gesture-based region and volume selection for hmd

Abstract: Methods, systems, computer-readable media, and apparatuses for selecting an Augmented Reality (AR) object on a head mounted device (HMD) are presented. In some embodiments, an HMD may define a Region-of-Interest (ROI) based on a gesture formed by at least one hand of a user. Subsequently the HMD may display to the user a shape on the HMD. In at least one arrangement, the shape outlines the ROI. Additionally, the HMD may display to the user a plurality of AR objects, each of the plurality of AR objects being associated with a target inside the ROI. Furthermore, the HMD may reduce the size of the ROI based on a first movement of the at least one hand of the user to form a reduced-sized ROI. In at least one arrangement, the reduced-sized ROI is used to select a specific AR object from the plurality of AR objects.

System and method for implementing a vehicle configuration based on parameters that are specified by a mobile computing device when outside of a vehicle

Abstract: A mobile computing device is operated to control a vehicle. A digital key for accessing a vehicle is stored for accessing the vehicle. Profile information is associated with the digital key for configuring operation and/or use of a vehicle. The profile information may include one or more outside parameters for implementing one or more pre-entry vehicle configurations. When one or more proximity conditions are detected as being satisfied as between the mobile computing device and the vehicle, a communication is sent to the vehicle in order to cause the vehicle to implement one or more pre-entry vehicle configurations. The communication can be based on the digital key and may specify the one or more outside parameters.

Enabling a communication feasibility determination time to complete communication exchanges between an m2m server and one or more m2m devices

Abstract: A method, an apparatus, and a computer program product for machine-to-machine communication are provided. A device receives a request from a requestor. The request requests the device to transmit information to the requestor according to a primary time duration. The device determines at least one secondary time duration within the primary time duration for transmitting the information to the requestor and schedules a transmission time within the at least one secondary time duration to transmit the information to the requestor in response to the request. The scheduling is based on additional information known to the device. A requestor determines a time duration for communicating with at least one device, transmits a request to the at least one device to transmit information to the requestor according to the time duration, and receives in response to the request the information from the at least one device within the time duration.

Systems and methods for backwards-compatible preamble formats for multiple access wireless communication

Abstract: Systems, methods, and devices for wireless communication are disclosed herein. One aspect of the disclosure provides a method of receiving a transmission from two or more wireless communication devices. The method includes receiving a first preamble transmitted by a first wireless device; simultaneously receiving a second preamble transmitted by a second wireless device; receiving a first portion of the transmission in a first section of a bandwidth, the first portion transmitted by the first wireless device including a first data section; and simultaneously receiving a second portion of the transmission in a second section of the bandwidth, the second section of the bandwidth not overlapping with the first section of the bandwidth, the second portion transmitted by the second wireless device, the second portion including a second data section.

System and method for thermal management in wireless charging devices

Abstract: The invention described herein relates to wireless power transfer systems and methods that efficiently and safely transfer power to electronic devices. In an aspect of the disclosure, an apparatus for wirelessly transmitting power is provided. The apparatus may comprise a wireless power transmitter and a charging surface. The charging surface at least partially covers the wireless power transmitter and is formed with an array of orthogonally disposed protrusions. The protrusions are configured to extend away from the charging surface.

Neighbor network channel reuse with MIMO capable stations

Abstract: Channel reuse may be used so that multiple networks may communicate via a shared powerline communication (PLC) medium. In a PLC network that supports different transmission modes, channel reuse may be improved by determining signal performance metrics associated with the different transmission modes. A transmission mode may be selected to facilitate channel reuse of the PLC medium by the local network and neighbor network. A first device and a second device may belong to a local network that shares the PLC medium with a neighbor network. The transmission mode may be selected based on interference and signal measurements at one or more receivers of the second device. The transmission mode may be selected from a group comprising a 2-stream multi-input multi-output (MIMO) eigen-beamforming transmission mode, a 1-stream MIMO spot-beamforming transmission mode, and a 1-stream single-input-single-output (SISO) transmission mode.

Downlink procedures for lte/lte-a communication systems with unlicensed spectrum

Abstract: Long term evolution (LTE)/LTE- Advanced (LTE-A) deployments with unlicensed spectrum leverage more efficient LTE communication aspects over unlicensed spectrum, such as over WIFI radio access technology. In order to accommodate such communications, various downlink procedures may be modified in order to handle communications between licensed and unlicensed spectrum with LTE/LTE-A deployments with unlicensed spectrum.

Architectural support for address translation on GPUs: designing memory management units for CPU/GPUs with unified address spaces

Abstract: The proliferation of heterogeneous compute platforms, of which CPU/GPU is a prevalent example, necessitates a manageable programming model to ensure widespread adoption. A key component of this is a shared unified address space between the heterogeneous units to obtain the programmability benefits of virtual memory. To this end, we are the first to explore GPU Memory Management Units(MMUs) consisting of Translation Lookaside Buffers (TLBs) and page table walkers (PTWs) for address translation in unified heterogeneous systems. We show the performance challenges posed by GPU warp schedulers on TLBs accessed in parallel with L1 caches, which provide many well-known programmability benefits. In response, we propose modest TLB and PTW augmentations that recover most of the performance lost by introducing L1 parallel TLB access. We also show that a little TLB-awareness can make other GPU performance enhancements (e.g., cache-conscious warp scheduling and dynamic warp formation on branch divergence) feasible in the face of cache-parallel address translation, bringing overheads in the range deemed acceptable for CPUs (10-15\% of runtime). We presume this initial design leaves room for improvement but anticipate that our bigger insight, that a little TLB-awareness goes a long way in GPUs, will spur further work in this fruitful area.

Cytoscape: the network visualization tool for GenomeSpace workflows.

Abstract: Modern genomic analysis often requires workflows incorporating multiple best-of-breed tools. GenomeSpace is a web-based visual workbench that combines a selection of these tools with mechanisms that create data flows between them. One such tool is Cytoscape 3, a popular application that enables analysis and visualization of graph-oriented genomic networks. As Cytoscape runs on the desktop, and not in a web browser, integrating it into GenomeSpace required special care in creating a seamless user experience and enabling appropriate data flows. In this paper, we present the design and operation of the Cytoscape GenomeSpace app, which accomplishes this integration, thereby providing critical analysis and visualization functionality for GenomeSpace users. It has been downloaded over 850 times since the release of its first version in September, 2013.

Establishing groups of internet of things (iot) devices and enabling communication among the groups of iot devices

Abstract: The disclosure generally relates to enabling communication among one or more Internet of Things (IoT) device groups. In particular, various heterogeneous IoT devices that may need to interact with one another in different ways may be organized into IoT device groups to support efficient interaction among the IoT devices. For example, pre-defined IoT device groups may be formed organize certain IoT devices that perform similar activities and certain IoT devices may be dynamically allocated to ad-hoc IoT device groups for certain contexts (e.g., the ad-hoc IoT device groups may include IoT devices that can implement a desired function and therefore be dynamically formed to implement the desired function). Furthermore, the IoT groups may communicate hierarchically, wherein messages may be exchanged among IoT group owners or ranking members to support efficient communication between different IoT groups.

Lte-u uplink waveform and variable multi-subframe scheduling

Abstract: Uplink waveforms for operating long term evolution (LTE) in an unlicensed band (i.e., long term evolution-unlicensed (LTE-U) communication) are disclosed. Carrier aggregation (CA) and standalone (SA) are disclosed. LTE on the licensed channel may provide both control and data, LTE on the unlicensed channel may provide data. Managing variable transmission time interval (TTI) continuous transmission is disclosed for transmission over multiple subframes of an unlicensed carrier in LTE-U. Listen-before-talk (LBT) requirements of unlicensed carriers provide for additional channel occupancy constraints when scheduling resources for multiple UEs for variable TTI continuous uplink transmissions over multiple subframes. A joint control channel is disclosed that provides control information for all of the potentially available subframes to be scheduled for the uplink transmissions. In addition to management of the variable TTI continuous transmissions, adjustments to uplink signal parameters are also disclosed that address the constraints due to the LBT requirements of unlicensed carriers.

LTE/LTE—A uplink carrier aggregation using unlicensed spectrum

Abstract: Methods, systems, and apparatuses are described for wireless communications. In one method, an uplink grant may be received over a licensed spectrum. A clear channel assessment (CCA) may be performed in response to the uplink grant to determine availability of an unlicensed spectrum. The CCA may be performed prior to a transmission associated with the uplink grant. In another method, scheduling information may be received over a licensed spectrum. An uplink grant may be transmitted over the licensed spectrum. The uplink grant may be based at least in part on the scheduling information. The uplink grant may be configured to trigger a CCA to determine availability of an unlicensed spectrum prior to a transmission associated with the uplink grant.