10 research outputs found
Delay-aware and power-efficient resource allocation in virtualized wireless networks
This paper proposes a delay-aware resource provisioning policy for virtualized wireless networks (VWNs) to minimize the total average transmit power while holding the minimum required average rate of each slice and maximum average packet transmission delay for each user. The proposed cross-layer optimization problem is inherently non-convex and has high computational complexity. To develop an efficient solution, we first transform cross-layer dependent constraints into physical layer dependent ones. Afterwards, we apply different convexification techniques based on variable transformations and relaxations, and propose an iterative algorithm to reach
the optimal solution. Simulation results illustrate the effects of the required average packet transmission delay and minimum average slice rate on the total transmission power in VWN
Resource Allocation for Outdoor-to-Indoor Multicarrier Transmission with Shared UE-side Distributed Antenna Systems
In this paper, we study the resource allocation algorithm design for downlink
multicarrier transmission with a shared user equipment (UE)-side distributed
antenna system (SUDAS) which utilizes both licensed and unlicensed frequency
bands for improving the system throughput. The joint UE selection and
transceiver processing matrix design is formulated as a non-convex optimization
problem for the maximization of the end-to-end system throughput (bits/s). In
order to obtain a tractable resource allocation algorithm, we first show that
the optimal transmitter precoding and receiver post-processing matrices jointly
diagonalize the end-to-end communication channel. Subsequently, the
optimization problem is converted to a scalar optimization problem for multiple
parallel channels, which is solved by using an asymptotically optimal iterative
algorithm. Simulation results illustrate that the proposed resource allocation
algorithm for the SUDAS achieves an excellent system performance and provides a
spatial multiplexing gain for single-antenna UEs.Comment: accepted for publication at the IEEE Vehicular Technology Conference
(VTC) Spring, Glasgow, Scotland, UK, May 201
Joint Scheduling and Resource Allocation in OFDMA Downlink Systems via ACK/NAK Feedback
In this paper, we consider the problem of joint scheduling and resource
allocation in the OFDMA downlink, with the goal of maximizing an expected
long-term goodput-based utility subject to an instantaneous sum-power
constraint, and where the feedback to the base station consists only of
ACK/NAKs from recently scheduled users. We first establish that the optimal
solution is a partially observable Markov decision process (POMDP), which is
impractical to implement. In response, we propose a greedy approach to joint
scheduling and resource allocation that maintains a posterior channel
distribution for every user, and has only polynomial complexity. For
frequency-selective channels with Markov time-variation, we then outline a
recursive method to update the channel posteriors, based on the ACK/NAK
feedback, that is made computationally efficient through the use of particle
filtering. To gauge the performance of our greedy approach relative to that of
the optimal POMDP, we derive a POMDP performance upper-bound. Numerical
experiments show that, for slowly fading channels, the performance of our
greedy scheme is relatively close to the upper bound, and much better than
fixed-power random user scheduling (FP-RUS), despite its relatively low
complexity
Channel assembling and resource allocation in multichannel spectrum sharing wireless networks
Submitted in fulfilment of the academic requirements for the degree of
Doctor of Philosophy (Ph.D.) in Engineering, in the School of Electrical and
Information Engineering, Faculty of Engineering and the Built Environment,
at the University of the Witwatersrand, Johannesburg, South Africa, 2017The continuous evolution of wireless communications technologies has increasingly imposed a
burden on the use of radio spectrum. Due to the proliferation of new wireless networks applications
and services, the radio spectrum is getting saturated and becoming a limited resource. To a large
extent, spectrum scarcity may be a result of deficient spectrum allocation and management policies,
rather than of the physical shortage of radio frequencies. The conventional static spectrum
allocation has been found to be ineffective, leading to overcrowding and inefficient use. Cognitive
radio (CR) has therefore emerged as an enabling technology that facilitates dynamic spectrum
access (DSA), with a great potential to address the issue of spectrum scarcity and inefficient use.
However, provisioning of reliable and robust communication with seamless operation in cognitive
radio networks (CRNs) is a challenging task. The underlying challenges include development of
non-intrusive dynamic resource allocation (DRA) and optimization techniques.
The main focus of this thesis is development of adaptive channel assembling (ChA) and DRA
schemes, with the aim to maximize performance of secondary user (SU) nodes in CRNs, without
degrading performance of primary user (PU) nodes in a primary network (PN). The key objectives
are therefore four-fold. Firstly, to optimize ChA and DRA schemes in overlay CRNs. Secondly, to
develop analytical models for quantifying performance of ChA schemes over fading channels in
overlay CRNs. Thirdly, to extend the overlay ChA schemes into hybrid overlay and underlay
architectures, subject to power control and interference mitigation; and finally, to extend the
adaptive ChA and DRA schemes for multiuser multichannel access CRNs.
Performance analysis and evaluation of the developed ChA and DRA is presented, mainly through
extensive simulations and analytical models. Further, the cross validation has been performed
between simulations and analytical results to confirm the accuracy and preciseness of the novel
analytical models developed in this thesis. In general, the presented results demonstrate improved
performance of SU nodes in terms of capacity, collision probability, outage probability and forced
termination probability when employing the adaptive ChA and DRA in CRNs.CK201
Assignació de potència de baixa complexitat per sistemas OFDMA-multiantena
Projecte realitzat en col.laboració amb l'empresa Newcom++Aquest projecte presenta una nova tècnica de gestió de recursos en escenaris de broadcasting.
Concretament gestiona l’accés dels usuaris mitjançant una assignació de potència
utilitzant una implementació de baixa complexitat. A més, també se’ls assigna una prioritat en la velocitat per tal d’assolir una determinada QoS. Aquest projecte té una fà cil implementació en sistemes comercials ja coneguts que incorporin OFDMA