14 research outputs found
Ruin Theory for Dynamic Spectrum Allocation in LTE-U Networks
LTE in the unlicensed band (LTE-U) is a promising solution to overcome the
scarcity of the wireless spectrum. However, to reap the benefits of LTE-U, it
is essential to maintain its effective coexistence with WiFi systems. Such a
coexistence, hence, constitutes a major challenge for LTE-U deployment. In this
paper, the problem of unlicensed spectrum sharing among WiFi and LTE-U system
is studied. In particular, a fair time sharing model based on \emph{ruin
theory} is proposed to share redundant spectral resources from the unlicensed
band with LTE-U without jeopardizing the performance of the WiFi system.
Fairness among both WiFi and LTE-U is maintained by applying the concept of the
probability of ruin. In particular, the probability of ruin is used to perform
efficient duty-cycle allocation in LTE-U, so as to provide fairness to the WiFi
system and maintain certain WiFi performance. Simulation results show that the
proposed ruin-based algorithm provides better fairness to the WiFi system as
compared to equal duty-cycle sharing among WiFi and LTE-U.Comment: Accepted in IEEE Communications Letters (09-Dec 2018
A Multi-Game Framework for Harmonized LTE-U and WiFi Coexistence over Unlicensed Bands
The introduction of LTE over unlicensed bands (LTE-U) will enable LTE base
stations (BSs) to boost their capacity and offload their traffic by exploiting
the underused unlicensed bands. However, to reap the benefits of LTE-U, it is
necessary to address various new challenges associated with LTE-U and WiFi
coexistence. In particular, new resource management techniques must be
developed to optimize the usage of the network resources while handling the
interdependence between WiFi and LTE users and ensuring that WiFi users are not
jeopardized. To this end, in this paper, a new game theoretic tool, dubbed as
\emph{multi-game} framework is proposed as a promising approach for modeling
resource allocation problems in LTE-U. In such a framework, multiple,
co-existing and coupled games across heterogeneous channels can be formulated
to capture the specific characteristics of LTE-U. Such games can be of
different properties and types but their outcomes are largely interdependent.
After introducing the basics of the multi-game framework, two classes of
algorithms are outlined to achieve the new solution concepts of multi-games.
Simulation results are then conducted to show how such a multi-game can
effectively capture the specific properties of LTE-U and make of it a
"friendly" neighbor to WiFi.Comment: Accepted for publication at IEEE Wireless Communications Magazine,
Special Issue on LTE in Unlicensed Spectru
Echo State Learning for Wireless Virtual Reality Resource Allocation in UAV-enabled LTE-U Networks
In this paper, the problem of resource management is studied for a network of
wireless virtual reality (VR) users communicating using an unmanned aerial
vehicle (UAV)-enabled LTE-U network. In the studied model, the UAVs act as VR
control centers that collect tracking information from the VR users over the
wireless uplink and, then, send the constructed VR images to the VR users over
an LTE-U downlink. Therefore, resource allocation in such a UAV-enabled LTE-U
network must jointly consider the uplink and downlink links over both licensed
and unlicensed bands. In such a VR setting, the UAVs can dynamically adjust the
image quality and format of each VR image to change the data size of each VR
image, then meet the delay requirement. Therefore, resource allocation must
also take into account the image quality and format. This VR-centric resource
allocation problem is formulated as a noncooperative game that enables a joint
allocation of licensed and unlicensed spectrum bands, as well as a dynamic
adaptation of VR image quality and format. To solve this game, a learning
algorithm based on the machine learning tools of echo state networks (ESNs)
with leaky integrator neurons is proposed. Unlike conventional ESN based
learning algorithms that are suitable for discrete-time systems, the proposed
algorithm can dynamically adjust the update speed of the ESN's state and,
hence, it can enable the UAVs to learn the continuous dynamics of their
associated VR users. Simulation results show that the proposed algorithm
achieves up to 14% and 27.1% gains in terms of total VR QoE for all users
compared to Q-learning using LTE-U and Q-learning using LTE
Echo State Networks for Proactive Caching in Cloud-Based Radio Access Networks with Mobile Users
In this paper, the problem of proactive caching is studied for cloud radio
access networks (CRANs). In the studied model, the baseband units (BBUs) can
predict the content request distribution and mobility pattern of each user,
determine which content to cache at remote radio heads and BBUs. This problem
is formulated as an optimization problem which jointly incorporates backhaul
and fronthaul loads and content caching. To solve this problem, an algorithm
that combines the machine learning framework of echo state networks with
sublinear algorithms is proposed. Using echo state networks (ESNs), the BBUs
can predict each user's content request distribution and mobility pattern while
having only limited information on the network's and user's state. In order to
predict each user's periodic mobility pattern with minimal complexity, the
memory capacity of the corresponding ESN is derived for a periodic input. This
memory capacity is shown to be able to record the maximum amount of user
information for the proposed ESN model. Then, a sublinear algorithm is proposed
to determine which content to cache while using limited content request
distribution samples. Simulation results using real data from Youku and the
Beijing University of Posts and Telecommunications show that the proposed
approach yields significant gains, in terms of sum effective capacity, that
reach up to 27.8% and 30.7%, respectively, compared to random caching with
clustering and random caching without clustering algorithm.Comment: Accepted in the IEEE Transactions on Wireless Communication
Liquid State Machine Learning for Resource and Cache Management in LTE-U Unmanned Aerial Vehicle (UAV) Networks
In this paper, the problem of joint caching and resource allocation is
investigated for a network of cache-enabled unmanned aerial vehicles (UAVs)
that service wireless ground users over the LTE licensed and unlicensed (LTE-U)
bands. The considered model focuses on users that can access both licensed and
unlicensed bands while receiving contents from either the cache units at the
UAVs directly or via content server-UAV-user links. This problem is formulated
as an optimization problem which jointly incorporates user association,
spectrum allocation, and content caching. To solve this problem, a distributed
algorithm based on the machine learning framework of liquid state machine (LSM)
is proposed. Using the proposed LSM algorithm, the cloud can predict the users'
content request distribution while having only limited information on the
network's and users' states. The proposed algorithm also enables the UAVs to
autonomously choose the optimal resource allocation strategies that maximize
the number of users with stable queues depending on the network states. Based
on the users' association and content request distributions, the optimal
contents that need to be cached at UAVs as well as the optimal resource
allocation are derived. Simulation results using real datasets show that the
proposed approach yields up to 33.3% and 50.3% gains, respectively, in terms of
the number of users that have stable queues compared to two baseline
algorithms: Q-learning with cache and Q-learning without cache. The results
also show that LSM significantly improves the convergence time of up to 33.3%
compared to conventional learning algorithms such as Q-learning