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On the efficient utilization of radio resources in extremely dense wireless networks
Get PDFThe emergence of popular wireless technologies such as LTE and WiFi, and the exponential growth in the usage of these technologies, has led to extremely dense wireless networks. There are many proposals for coping with such densification. In particular, we evaluate the compound effect of inter-cell interference schemes and spectrum efficient intra-cell relay techniques, which have been individually proposed recently as separate solutions. We provide a jointly coordinated intracell and inter-cell resource allocation mechanism that opportunistically exploits network density as a resource. We show that intracell opportunistic relay, based on WiFi communications, reduces the complexity of Inter-Cell Interference Coordination (ICIC) and boosts the efficiency of ICIC in LTE. The superiority of the proposed solution to the legacy cellular network operation is proven via simulationspu
Algorithmic Mechanisms for Reliable Crowdsourcing Computation under Collusion
Get PDFWe consider a computing system where a master processor assigns a task for execution to worker processors that may collude. We model the workers’ decision of whether to comply (compute the task) or not (return a bogus result to save the computation cost) as a game among workers. That is, we assume that workers are rational in a game-theoretic sense. We identify analytically the parameter conditions for a unique Nash Equilibrium where the master obtains the correct result. We also evaluate experimentally mixed equilibria aiming to attain better reliability-profit trade-offs. For a wide range of parameter values that may be used in practice, our simulations show that, in fact, both master and workers are better off using a pure equilibrium where no worker cheats, even under collusion, and even for collud- ing behaviors that involve deviating from the game.pu
Context Information for Fast Cell Discovery in mm-wave 5G Networks
Get PDFThe exploitation of the mm-wave bands is one of the most promising solutions for 5G mobile radio networks. However, the use of mm-wave technologies in cellular networks is not straightforward due to mm-wave severe propagation conditions that limit access availability. In order to overcome this obstacle, hybrid network architectures are being considered where mm-wave small cells can exploit an overlay coverage layer based on legacy technology. The additional mm-wave layer can also take advantage of a functional split between control and user plane, that allows to delegate most of the signaling functions to legacy base stations and to gather context information from users for resource optimization. However, mm-wave technology requires multiple antennas and highly directional transmissions to compensate for high path loss and limited power. Directional transmissions must be also used for the cell discovery and synchronization process, and this can lead to a non negligible delay due to need to scan the cell area with multiple transmissions in different angles. In this paper, we propose to exploit the context information related to user position, provided by the separated control plane, to improve the cell discovery procedure and minimize delay. We investigate the fundamental trade-offs of the cell discovery process with directional antennas and the effects of the context information accuracy on its performance. Numerical results are provided to validate our observations.TRUEpu
HDMM: Deploying client and network-based Distributed Mobility Management. A hybrid approach
Get PDFMobile operators are now facing the challenges posed by a huge data demand from users, mainly due to the introduction of modern portable devices and the success of mobile applications. Moreover, users are now capable to connect from different access networks and establish several active sessions simultaneously, while being mobile. This triggered the introduction of a new paradigm: the distributed mobility
management (DMM) which aims at flattening the network and distributing the entities in charge of managing users' mobility.
In this article, we review existing DMM proposals and describe a hybrid solution which benefits from combining a network-based and a client-based approaches. We analyze the signaling cost and the handover latency of our proposal, comparing them with their centralized alternatives. We also include validation and performance results from experiments conducted with a Linux-based prototype, which show that achievable enhancements depend on the underlying network topology. We argue that the proposed hybrid DMM solution provides additional flexibility to the mobile network
operators, which can decide when and how to combine these two approaches.pu
Competitive Analysis of Task Scheduling Algorithms on a Fault-Prone Machine and the Impact of Resource Augmentation
Get PDFReliable task execution in machines that are prone to unpredictable crashes and restarts is challenging and of high importance. However, not much work exists on the worst case analysis of such systems. In this paper, we analyze the fault-tolerant properties of four popular scheduling algorithms: Longest In System (LIS), Shortest In System (SIS), Largest Processing Time (LPT) and Shortest Processing Time (SPT), under worst case scenarios on a fault-prone machine. We use three metrics for the evaluation and comparison of their competitive performance, namely, completed time, pending time and latency. We also investigate the effect of resource augmentation in their performance, by increasing the speed of the machine. To do so, we compare the behavior of the algorithms for different speed intervals and show that between LIS, SIS and SPT there is no clear winner with respect to all the three considered metrics, while LPT is not better than SPT.TRUEpu
Anticipatory Admission Control and Resource Allocation for Media Streaming in Mobile Networks
Get PDFThe exponential growth of media streaming traffic will have a strong impact on the bandwidth consumption of the future wireless infrastructure. One key challenge is to deliver services taking into account the stringent requirements of mobile video streaming, e.g., the users' expected Quality-of-Service. Admission control and resource allocation can strongly benefit from the use of anticipatory information such as the prediction of future user's demand and expected channel gain. In this paper, we use this information to formulate an optimal admission control scheme that maximizes the number of accepted users into the system with the constraint that not only the current but also the expected demand of all users must be satisfied. Together with the optimal set of accepted users, the optimal resource scheduling is derived. In order to have a solution that can be computed in a reasonable time, we propose a low complexity heuristic. Numerical results show the performance of the proposed scheme with respect to the state of the art.TRUEpu
Millimeter-Wave Small-Cell Deployment Scenarios as an Enabler for 5G Applications and Use Cases
Get PDFMillimeter-wave; 5G; reference scenarios.The millimeter-wave band is a much discussed candidate as additional access technology of the fifth generation of mobile radio networks (5G). This paper gives a background on the fundamentals of mmwave
propagation and then investigates a set of reference scenarios, where the new bands will enable new applications and use cases.TRUEpu
Demonstration Abstract: A Low-cost Sensor Platform for Large-scale Wideband Spectrum Monitoring
Get PDFToday’s radio frequency (RF) spectrum measurements are mainly performed by governmental agencies which drive around using bulky and expensive specialized hardware. This approach does not scale well, providing us with only a poor situational awareness of the actual RF spectrum usage around us. We have developed a wideband spectrum monitoring sensor for remote operation that builds upon portable and low-cost commercial off-the-shelf (COTS) hardware components with a total cost per sensor device below $100. This results in a stunning cost reduction factor of 50 to 500 comparing to
professional equipment. Our sensor platform adopts the software-defined radio paradigm and performs all signal processing steps on the CPU and GPU of a low-cost single-board computer. We address the challenges of large frequency errors and long scanning times due to the hardware constraints by proposing new correction and optimization methods, providing a satisfactory level of accuracy in
indoor and outdoor environments. Our remote sensing platform is envisioned to be used at larger scale for various applications such as dynamic spectrum access in cognitive radios, detecting regions with elevated electro-smog, or for policy enforcement in the electromagnetic space.TRUEpu
Floating Band D2D: Exploring and Exploiting the Potentials of Adaptive D2D-enabled Networks
Get PDFIn this paper, we propose Floating Band D2D, an adaptive framework to exploit the full potential of Device-to- Device (D2D) transmission modes. We show that inband and outband D2D modes exhibit different pros and cons in terms of complexity, interference, and spectral efficiency. Moreover, none of these modes is suitable as a one-size-fits-all solution for today’s cellular networks, due to diverse network requirements and variable users’ behavior. Therefore, we unveil the need for going beyond traditional single-band mode-selection schemes. Specifically, we model and formulate a general and adaptive multi-band mode selection problem, namely Floating Band D2D. The problem is NP-hard, so we propose simple yet effective heuristics. Our results show the superiority of the Floating Band D2D framework, which dramatically increases network utility and achieves near complete fairness.TRUEpu
Steering with Eyes Closed: mm-Wave Beam Steering without In-Band Measurement
Get PDFMillimeter-wave communication achieves multi-Gb/sec data rates via highly directional beamforming to overcome pathloss and provide the desired SNR. Unfortunately, establishing communication with sufficiently narrow beamwidth to obtain the necessary link budget is a high overhead procedure in which the search space scales with device mobility and the product of the sender-receiver beam resolution.
In this paper, we design, implement, and experimentally evaluate Blind Beam Steering (BBS) a novel architecture and algorithm that removes in-band overhead for directional mm-Wave link establishment. Our system architecture couples mm-Wave and legacy 2.4/5 GHz bands using out-of-band direction inference to establish (overhead-free) multi Gb/sec mm-Wave communication.
Further, BBS evaluates direction estimates retrieved from passively overheard 2.4/5 GHz frames to assure highest mm-Wave link quality on unobstructed direct paths.
By removing in-band overhead, we leverage mm-Wave's very high throughput capabilities, beam-width scalability and provide robustness to mobility. We demonstrate that BBS achieves 97.8% accuracy estimating direction between pairing nodes using at least 5 detection band antennas. Further, \sys successfully detects unobstructed direct path conditions with a rate of 96.5\% and reduces the IEEE 802.11ad beamforming training overhead by 81%.TRUEpu