5 research outputs found
Device Caching for Network Offloading: Delay Minimization with Presence of User Mobility
A delay-optimal caching problem (DOCP) in deviceto- device (D2D) networks
with moblity is modelled. The problem arises in the context of achieving
offloading using device caching, and the offloading effect is represented by
the expected network load ratio (NLR) which is the percentage of data that has
to be downloaded from the network. Compared with the related studies, this work
considers minimizing delay with NLR guarantee in mobility scenarios. A lower
bound of global optimum is derived, thus enabling performance benchmarking of
any sub-optimal algorithm. For problem-solving, an effective search algorithm
(ESA) is proposed based on the bound. Simulations are conducted to evaluate the
effectiveness of the ESA algorithm.Comment: To appear in IEEE Wireless Communication Letter
Cost-optimal caching for D2D networks with user mobility: Modeling, analysis, and computational approaches
Caching popular files at user equipments (UEs) provides an effective way to
alleviate the burden of the backhaul networks. Generally, popularity-based
caching is not a system-wide optimal strategy, especially for user mobility
scenarios. Motivated by this observation, we consider optimal caching with
presence of mobility. A cost-optimal caching problem (COCP) for
device-to-device (D2D) networks is modelled, in which the impact of user
mobility, cache size, and total number of encoded segments are all accounted
for. Compared with the related studies, our investigation guarantees that the
collected segments are non-overlapping, takes into account the cost of
downloading from the network, and provides a rigorous problem complexity
analysis. The hardness of the problem is proved via a reduction from the
satisfiability problem. Next, a lower-bounding function of the objective
function is derived. By the function, an approximation of COCP (ACOCP)
achieving linearization is obtained, which features two advantages. First, the
ACOCP approach can use an off-the-shelf integer linear programming algorithm to
obtain the global optimal solution, and it can effectively deliver solutions
for small-scale and mediumscale system scenarios. Second, and more importantly,
based on the ACOCP approach, one can derive the lower bound of global optimum
of COCP, thus enabling performance benchmarking of any suboptimal algorithm. To
tackle large scenarios with low complexity, we first prove that the optimal
caching placement of one user, giving other users' caching placements, can be
derived in polynomial time. Then, based on this proof, a mobility aware
user-by-user (MAUU) algorithm is developed. Simulation results verify the
effectivenesses of the two approaches by comparing them to the lower bound of
global optimum and conventional caching algorithms
Design and Implementation of SMARTHO -- A Network Initiated Handover mechanism in NG-RAN, on P4-based Xilinx NetFPGA switches
This report deals with the design of handover schemes for radio access
networks (RAN) in 5G networks, using programmable data plane switches. In 5G
networks, the NG-RAN architecture splits the Base Band Unit (BBU) into Central
and Distributed Units (CU and DU). This structure has created a mid-haul
Network, connecting CUs and DUs. The recent advancements in dataplane
programmability can be used to enhance system performance. We show how P4
switches can be used to parse the packets between DU, CU, and Back Haul (Core
Network) for potential system improvements. In particular, we consider the
scenario of mobile handover. The proposed protocol is called SMARTHO,
illustrating a smart handover.
Programming Protocol-Independent Packet Processors (P4) is a programming
language designed to support specification and programming the forwarding plane
behavior of network switches/routers. In SMARTHO, we use P4 Switches to
intervene in the handover process for fixed-path mobile users. A resource
pre-allocation scheme that reserves resources before the UE reaches a future
cell, is proposed. The solution is implemented using a P4-based switch
introduced between the CU and the DU. The P4 switch is used to spoof the
behavior of User Equipment (UE) and perform the resource allocation in advance.
The proposed SMARTHO framework is implemented in the mininet emulation
environment and in a reconfigurable hardware environment using NetFPGA-SUME
boards. The emulation results show a handover response time improvement of 18%
for a tandem of two HOs and 25% for a tandem of three HOs. For testbed
implementation, we used NetFPGA-SUME boards as P4 switches. The handover time
was measured to be approximately 50~milliseconds in the experiments conducted
A Survey on Mobile Edge Networks: Convergence of Computing, Caching and Communications
As the explosive growth of smart devices and the advent of many new
applications, traffic volume has been growing exponentially. The traditional
centralized network architecture cannot accommodate such user demands due to
heavy burden on the backhaul links and long latency. Therefore, new
architectures which bring network functions and contents to the network edge
are proposed, i.e., mobile edge computing and caching. Mobile edge networks
provide cloud computing and caching capabilities at the edge of cellular
networks. In this survey, we make an exhaustive review on the state-of-the-art
research efforts on mobile edge networks. We first give an overview of mobile
edge networks including definition, architecture and advantages. Next, a
comprehensive survey of issues on computing, caching and communication
techniques at the network edge is presented respectively. The applications and
use cases of mobile edge networks are discussed. Subsequently, the key enablers
of mobile edge networks such as cloud technology, SDN/NFV and smart devices are
discussed. Finally, open research challenges and future directions are
presented as well
Mobility Management in Emerging Ultra-Dense Cellular Networks: A Survey, Outlook, and Future Research Directions
The exponential rise in mobile traffic originating from mobile devices
highlights the need for making mobility management in future networks even more
efficient and seamless than ever before. Ultra-Dense Cellular Network vision
consisting of cells of varying sizes with conventional and mmWave bands is
being perceived as the panacea for the eminent capacity crunch. However,
mobility challenges in an ultra-dense heterogeneous network with motley of high
frequency and mmWave band cells will be unprecedented due to plurality of
handover instances, and the resulting signaling overhead and data interruptions
for miscellany of devices. Similarly, issues like user tracking and cell
discovery for mmWave with narrow beams need to be addressed before the
ambitious gains of emerging mobile networks can be realized. Mobility
challenges are further highlighted when considering the 5G deliverables of
multi-Gbps wireless connectivity, <1ms latency and support for devices moving
at maximum speed of 500km/h, to name a few. Despite its significance, few
mobility surveys exist with the majority focused on adhoc networks. This paper
is the first to provide a comprehensive survey on the panorama of mobility
challenges in the emerging ultra-dense mobile networks. We not only present a
detailed tutorial on 5G mobility approaches and highlight key mobility risks of
legacy networks, but also review key findings from recent studies and highlight
the technical challenges and potential opportunities related to mobility from
the perspective of emerging ultra-dense cellular networks.Comment: in IEEE Acces