765 research outputs found
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
Energy and throughput efficient strategies for heterogeneous future communication networks
As a result of the proliferation of wireless-enabled user equipment and data-hungry applications, mobile data traffic has exponentially increased in recent years.This in-crease has not only forced mobile networks to compete on the scarce wireless spectrum but also to intensify their power consumption to serve an ever-increasing number of user devices. The Heterogeneous Network (HetNet) concept, where mixed types of low-power base stations coexist with large macro base stations, has emerged as a potential solution to address power consumption and spectrum scarcity challenges. However, as a consequence of their inflexible, constrained, and hardware-based configurations, HetNets have major limitations in adapting to fluctuating traffic patterns. Moreover, for large mobile networks, the number of low-power base stations (BSs) may increase dramatically leading to sever power consumption. This can easily overwhelm the benefits of the HetNet concept.
This thesis exploits the adaptive nature of Software-defined Radio (SDR) technology to design novel and optimal communication strategies. These strategies have been designed to leverage the spectrum-based cell zooming technique, the long-term evolution licensed assisted access (LTE-LAA) concept, and green energy, in order to introduce a novel communication framework that endeavors to minimize overall network on-grid power consumption and to maximize aggregated throughput, which brings significant benefits for both network operators and their customers. The proposed strategies take into consideration user data demands, BS loads, BS power consumption, and available spectrum to model the research questions as optimization problems.
In addition, this thesis leverages the opportunistic nature of the cognitive radio (CR) technique and the adaptive nature of the SDR to introduce a CR-based communication strategy. This proposed CR-based strategy alleviates the power consumption of the CR technique and enhances its security measures according to the confidentiality level of the data being sent. Furthermore, the introduced strategy takes into account user-related factors, such as user battery levels and user data types, and network-related factors, such as the number of unutilized bands and vulnerability level, and then models the research question as a constrained optimization problem.
Considering the time complexity of the optimum solutions for the above-mentioned strategies, heuristic solutions were proposed and examined against existing solutions. The obtained results show that the proposed strategies can save energy consumption up to 18%, increase user throughput up to 23%, and achieve better spectrum utilization. Therefore, the proposed strategies offer substantial benefits for both network operators and users
Holistic Small Cell Traffic Balancing across Licensed and Unlicensed Bands
Due to the dramatic growth in mobile data traffic on one hand and the
scarcity of the licensed spectrum on the other hand, mobile operators are
considering the use of unlicensed bands (especially those in 5 GHz) as
complementary spectrum for providing higher system capacity and better user
experience. This approach is currently being standardized by 3GPP under the
name of LTE Licensed-Assisted Access (LTE-LAA). In this paper, we take a
holistic approach for LTE-LAA small cell traffic balancing by jointly
optimizing the use of the licensed and unlicensed bands. We pose this traffic
balancing as an optimization problem that seeks proportional fair coexistence
of WiFi, small cell and macro cell users by adapting the transmission
probability of the LTE-LAA small cell in the licensed and unlicensed bands. The
motivation for this formulation is for the LTE-LAA small cell to switch between
or aggregate licensed and unlicensed bands depending on the
interference/traffic level and the number of active users in each band. We
derive a closed form solution for this optimization problem and additionally
propose a transmission mechanism for the operation of the LTE-LAA small cell on
both bands. Through numerical and simulation results, we show that our proposed
traffic balancing scheme, besides enabling better LTE-WiFi coexistence and
efficient utilization of the radio resources relative to the existing traffic
balancing scheme, also provides a better tradeoff between maximizing the total
network throughput and achieving fairness among all network flows compared to
alternative approaches.Comment: Accepted for publication at MSWiM 201
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