49,784 research outputs found
Sub-channel Assignment, Power Allocation and User Scheduling for Non-Orthogonal Multiple Access Networks
In this paper, we study the resource allocation and user scheduling problem
for a downlink nonorthogonal multiple access network where the base station
allocates spectrum and power resources to a set of users. We aim to jointly
optimize the sub-channel assignment and power allocation to maximize the
weighted total sum-rate while taking into account user fairness. We formulate
the sub-channel allocation problem as equivalent to a many-to-many two-sided
user-subchannel matching game in which the set of users and sub-channels are
considered as two sets of players pursuing their own interests. We then propose
a matching algorithm which converges to a two-side exchange stable matching
after a limited number of iterations. A joint solution is thus provided to
solve the sub-channel assignment and power allocation problems iteratively.
Simulation results show that the proposed algorithm greatly outperforms the
orthogonal multiple access scheme and a previous non-orthogonal multiple access
scheme.Comment: Accepted as a regular paper by IEEE Transactions on Wireless
Communication
Getting the Most Out of Your VNFs: Flexible Assignment of Service Priorities in 5G
Through their computational and forwarding capabilities, 5G networks can
support multiple vertical services. Such services may include several common
virtual (network) functions (VNFs), which could be shared to increase resource
efficiency. In this paper, we focus on the seldom studied VNF-sharing problem,
and decide (i) whether sharing a VNF instance is possible/beneficial or not,
(ii) how to scale virtual machines hosting the VNFs to share, and (iii) the
priorities of the different services sharing the same VNF. These decisions are
made with the aim to minimize the mobile operator's costs while meeting the
verticals' performance requirements. Importantly, we show that the
aforementioned priorities should not be determined a priori on a per-service
basis, rather they should change across VNFs since such additional flexibility
allows for more efficient solutions. We then present an effective methodology
called FlexShare, enabling near-optimal VNF-sharing decisions in polynomial
time. Our performance evaluation, using real-world VNF graphs, confirms the
effectiveness of our approach, which consistently outperforms baseline
solutions using per-service priorities
Energy-Efficient Flow Scheduling and Routing with Hard Deadlines in Data Center Networks
The power consumption of enormous network devices in data centers has emerged
as a big concern to data center operators. Despite many
traffic-engineering-based solutions, very little attention has been paid on
performance-guaranteed energy saving schemes. In this paper, we propose a novel
energy-saving model for data center networks by scheduling and routing
"deadline-constrained flows" where the transmission of every flow has to be
accomplished before a rigorous deadline, being the most critical requirement in
production data center networks. Based on speed scaling and power-down energy
saving strategies for network devices, we aim to explore the most energy
efficient way of scheduling and routing flows on the network, as well as
determining the transmission speed for every flow. We consider two general
versions of the problem. For the version of only flow scheduling where routes
of flows are pre-given, we show that it can be solved polynomially and we
develop an optimal combinatorial algorithm for it. For the version of joint
flow scheduling and routing, we prove that it is strongly NP-hard and cannot
have a Fully Polynomial-Time Approximation Scheme (FPTAS) unless P=NP. Based on
a relaxation and randomized rounding technique, we provide an efficient
approximation algorithm which can guarantee a provable performance ratio with
respect to a polynomial of the total number of flows.Comment: 11 pages, accepted by ICDCS'1
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