592 research outputs found
TCP Performance Analysis for LTE and LTE/WLAN Aggregation
Software Defined Radio (SDR) enables the execution of many hardware-based operations through software. With an open-source LTE software and an SDR, we are able to run a LTE base station on a PC or a portable and low-cost device. At the same time, simple devices such as Raspberry Pi can be turned into WiFi APs. In this work, we will work on the developed LTE/WiFi integration solution using OpenAirInterface software that implements the LTE eNB and the core network.Nowadays, mobile IP data traffic is increasing exponentially and predictions tells that it will triplicate its actual value in 2020. A solution to this dare is LTE/WLAN Aggregation technique where cellular networks such as LTE and WLAN networks such as WiFi are combined to improve its performance. In this thesis, a prototype, based on very tight coupling between LTE and WiFi, is evaluated for their performance. There will be three policies assessed: No Offload policy, when data traffic is sent over LTE link; Full Offload, when data packets is sent over WiFi link and control packets through LTE link; and LWA with different techniques to split traffic through both links: Time division, Par/Impar, Low ICMP RTT and Port division. In very tight coupling, eNB manages offloading and aggregation techniques, and does not require the core network in any case. PDCP layer, as common layer between both technologies, switches the traffic depending on the policy. Moreover, prioritizing reliability in front of throughput, an analysis of TCP flow control and default TCP congestion control method employed by Linux, namely CUBIC, theoretically and showing their functioning through physical experiments was performed
Fair Coexistence of Scheduled and Random Access Wireless Networks: Unlicensed LTE/WiFi
We study the fair coexistence of scheduled and random access transmitters
sharing the same frequency channel. Interest in coexistence is topical due to
the need for emerging unlicensed LTE technologies to coexist fairly with WiFi.
However, this interest is not confined to LTE/WiFi as coexistence is likely to
become increasingly commonplace in IoT networks and beyond 5G. In this article
we show that mixing scheduled and random access incurs and inherent
throughput/delay cost, the cost of heterogeneity. We derive the joint
proportional fair rate allocation, which casts useful light on current LTE/WiFi
discussions. We present experimental results on inter-technology detection and
consider the impact of imperfect carrier sensing.Comment: 14 pages, 8 figures, journa
Data Offloading in Load Coupled Networks: A Utility Maximization Framework
We provide a general framework for the problem of data offloading in a
heterogeneous wireless network, where some demand of cellular users is served
by a complementary network. The complementary network is either a small-cell
network that shares the same resources as the cellular network, or a WiFi
network that uses orthogonal resources. For a given demand served in a cellular
network, the load, or the level of resource usage, of each cell depends in a
non-linear manner on the load of other cells due to the mutual coupling of
interference seen by one another. With load coupling, we optimize the demand to
be served in the cellular or the complementary networks, so as to maximize a
utility function. We consider three representative utility functions that
balance, to varying degrees, the revenue from serving the users vs the user
fairness. We establish conditions for which the optimization problem has a
feasible solution and is convex, and hence tractable to numerical computations.
Finally, we propose a strategy with theoretical justification to constrain the
load to some maximum value, as required for practical implementation. Numerical
studies are conducted for both under-loaded and over-loaded networks.Comment: 12 pages, accepted for publication in IEEE Transactions on Wireless
Communication
Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks
Soaring capacity and coverage demands dictate that future cellular networks
need to soon migrate towards ultra-dense networks. However, network
densification comes with a host of challenges that include compromised energy
efficiency, complex interference management, cumbersome mobility management,
burdensome signaling overheads and higher backhaul costs. Interestingly, most
of the problems, that beleaguer network densification, stem from legacy
networks' one common feature i.e., tight coupling between the control and data
planes regardless of their degree of heterogeneity and cell density.
Consequently, in wake of 5G, control and data planes separation architecture
(SARC) has recently been conceived as a promising paradigm that has potential
to address most of aforementioned challenges. In this article, we review
various proposals that have been presented in literature so far to enable SARC.
More specifically, we analyze how and to what degree various SARC proposals
address the four main challenges in network densification namely: energy
efficiency, system level capacity maximization, interference management and
mobility management. We then focus on two salient features of future cellular
networks that have not yet been adapted in legacy networks at wide scale and
thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and
device-to-device (D2D) communications. After providing necessary background on
CoMP and D2D, we analyze how SARC can particularly act as a major enabler for
CoMP and D2D in context of 5G. This article thus serves as both a tutorial as
well as an up to date survey on SARC, CoMP and D2D. Most importantly, the
article provides an extensive outlook of challenges and opportunities that lie
at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201
Hybrid Spectrum Sharing in mmWave Cellular Networks
While spectrum at millimeter wave (mmWave) frequencies is less scarce than at
traditional frequencies below 6 GHz, still it is not unlimited, in particular
if we consider the requirements from other services using the same band and the
need to license mmWave bands to multiple mobile operators. Therefore, an
efficient spectrum access scheme is critical to harvest the maximum benefit
from emerging mmWave technologies. In this paper, we introduce a new hybrid
spectrum access scheme for mmWave networks, where data is aggregated through
two mmWave carriers with different characteristics. In particular, we consider
the case of a hybrid spectrum scheme between a mmWave band with exclusive
access and a mmWave band where spectrum is pooled between multiple operators.
To the best of our knowledge, this is the first study proposing hybrid spectrum
access for mmWave networks and providing a quantitative assessment of its
benefits. Our results show that this approach provides major advantages with
respect to traditional fully licensed or fully unlicensed spectrum access
schemes, though further work is needed to achieve a more complete understanding
of both technical and non technical implications
Proportional Fair RAT Aggregation in HetNets
Heterogeneity in wireless network architectures (i.e., the coexistence of 3G,
LTE, 5G, WiFi, etc.) has become a key component of current and future
generation cellular networks. Simultaneous aggregation of each client's traffic
across multiple such radio access technologies (RATs) / base stations (BSs) can
significantly increase the system throughput, and has become an important
feature of cellular standards on multi-RAT integration. Distributed algorithms
that can realize the full potential of this aggregation are thus of great
importance to operators. In this paper, we study the problem of resource
allocation for multi-RAT traffic aggregation in HetNets (heterogeneous
networks). Our goal is to ensure that the resources at each BS are allocated so
that the aggregate throughput achieved by each client across its RATs satisfies
a proportional fairness (PF) criterion. In particular, we provide a simple
distributed algorithm for resource allocation at each BS that extends the PF
allocation algorithm for a single BS. Despite its simplicity and lack of
coordination across the BSs, we show that our algorithm converges to the
desired PF solution and provide (tight) bounds on its convergence speed. We
also study the characteristics of the optimal solution and use its properties
to prove the optimality of our algorithm's outcomes.Comment: Extended version of the 31st International Teletraffic Congress (ITC
2019) conference pape
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