2 research outputs found
Optimizing Throughput Fairness of Cluster-based Cooperation in Underlay Cognitive WPCNs
In this paper, we consider a secondary wireless powered communication network
(WPCN) underlaid to a primary point-to-point communication link. The WPCN
consists of a multi-antenna hybrid access point (HAP) that transfers wireless
energy to a cluster of low-power wireless devices (WDs) and receives sensing
data from them. To tackle the inherent severe user unfairness problem in WPCN,
we consider a cluster-based cooperation where a WD acts as the cluster head
that relays the information of the other WDs. Besides, we apply energy
beamforming technique to balance the dissimilar energy consumptions of the WDs
to further improve the fairness. However, the use of energy beamforming and
cluster-based cooperation may introduce more severe interference to the primary
system than the WDs transmit independently. To guarantee the performance of
primary system, we consider an interference-temperature constraint to the
primary system and derive the throughput performance of each WD under the peak
interference-temperature constraint. To achieve maximum throughput fairness, we
jointly optimize the energy beamforming design, the transmit time allocation
among the HAP and the WDs, and the transmit power allocation of each WD to
maximize the minimum data rate achievable among the WDs (the max-min
throughput). We show that the non-convex joint optimization problem can be
transformed to a convex one and then be efficiently solved using off-the-shelf
convex algorithms. Moreover, we simulate under practical network setups and
show that the proposed method can effectively improve the throughput fairness
of the secondary WPCN, meanwhile guaranteeing the communication quality of the
primary network.Comment: The paper has been submitted for potential journal publication. arXiv
admin note: text overlap with arXiv:1707.0320
Throughput Optimization of Intelligent Reflecting Surface Assisted User Cooperation in WPCNs
Intelligent reflecting surface (IRS) can effectively enhance the energy and
spectral efficiency of wireless communication system through the use of a large
number of lowcost passive reflecting elements. In this paper, we investigate
throughput optimization of IRS-assisted user cooperation in a wireless powered
communication network (WPCN), where the two WDs harvest wireless energy and
transmit information to a common hybrid access point (HAP). In particular, the
two WDs first exchange their independent information with each other and then
form a virtual antenna array to transmit jointly to the HAP. We aim to maximize
the common (minimum) throughput performance by jointly optimizing the transmit
time and power allocations of the two WDs on wireless energy and information
transmissions and the passive array coefficients on reflecting the wireless
energy and information signals. By comparing with some existing benchmark
schemes, our results show that the proposed IRS-assisted user cooperation
method can effectively improve the throughput performance of cooperative
transmission in WPCNs.Comment: The paper has been accepted by Proc. IEEE VTC 2020 Fal