8,405 research outputs found
Resource Allocation for Energy-Efficient Device-to-Device Communication in 4G Networks
Device-to-device (D2D) communications as an underlay of a LTE-A (4G) network
can reduce the traffic load as well as power consumption in cellular networks
by way of utilizing peer-to-peer links for users in proximity of each other.
This would enable other cellular users to increment their traffic, and the
aggregate traffic for all users can be significantly increased without
requiring additional spectrum. However, D2D communications may increase
interference to cellular users (CUs) and force CUs to increase their transmit
power levels in order to maintain their required quality-of-service (QoS). This
paper proposes an energy-efficient resource allocation scheme for D2D
communications as an underlay of a fully loaded LTE-A (4G) cellular network.
Simulations show that the proposed scheme allocates cellular uplink resources
(transmit power and channel) to D2D pairs while maintaining the required QoS
for D2D and cellular users and minimizing the total uplink transmit power for
all users.Comment: 2014 7th International Symposium on Telecommunications (IST'2014
A Delay-Aware Caching Algorithm for Wireless D2D Caching Networks
Recently, wireless caching techniques have been studied to satisfy lower
delay requirements and offload traffic from peak periods. By storing parts of
the popular files at the mobile users, users can locate some of their requested
files in their own caches or the caches at their neighbors. In the latter case,
when a user receives files from its neighbors, device-to-device (D2D)
communication is enabled. D2D communication underlaid with cellular networks is
also a new paradigm for the upcoming 5G wireless systems. By allowing a pair of
adjacent D2D users to communicate directly, D2D communication can achieve
higher throughput, better energy efficiency and lower traffic delay. In this
work, we propose a very efficient caching algorithm for D2D-enabled cellular
networks to minimize the average transmission delay. Instead of searching over
all possible solutions, our algorithm finds out the best pairs,
which provide the best delay improvement in each loop to form a caching policy
with very low transmission delay and high throughput. This algorithm is also
extended to address a more general scenario, in which the distributions of
fading coefficients and values of system parameters potentially change over
time. Via numerical results, the superiority of the proposed algorithm is
verified by comparing it with a naive algorithm, in which all users simply
cache their favorite files
Radio Resource Allocation for Device-to-Device Underlay Communication Using Hypergraph Theory
Device-to-Device (D2D) communication has been recognized as a promising
technique to offload the traffic for the evolved Node B (eNB). However, the D2D
transmission as an underlay causes severe interference to both the cellular and
other D2D links, which imposes a great technical challenge to radio resource
allocation. Conventional graph based resource allocation methods typically
consider the interference between two user equipments (UEs), but they cannot
model the interference from multiple UEs to completely characterize the
interference. In this paper, we study channel allocation using hypergraph
theory to coordinate the interference between D2D pairs and cellular UEs, where
an arbitrary number of D2D pairs are allowed to share the uplink channels with
the cellular UEs. Hypergraph coloring is used to model the cumulative
interference from multiple D2D pairs, and thus, eliminate the mutual
interference. Simulation results show that the system capacity is significantly
improved using the proposed hypergraph method in comparison to the conventional
graph based one.Comment: 27 pages,10 figure
Optimal time sharing in underlay cognitive radio systems with RF energy harvesting
Due to the fundamental tradeoffs, achieving spectrum efficiency and energy
efficiency are two contending design challenges for the future wireless
networks. However, applying radio-frequency (RF) energy harvesting (EH) in a
cognitive radio system could potentially circumvent this tradeoff, resulting in
a secondary system with limitless power supply and meaningful achievable
information rates. This paper proposes an online solution for the optimal time
allocation (time sharing) between the EH phase and the information transmission
(IT) phase in an underlay cognitive radio system, which harvests the RF energy
originating from the primary system. The proposed online solution maximizes the
average achievable rate of the cognitive radio system, subject to the
-percentile protection criteria for the primary system. The
optimal time sharing achieves significant gains compared to equal time
allocation between the EH and IT phases.Comment: Proceedings of the 2015 IEEE International Conference on
Communications (IEEE ICC 2015), 8-12 June 2015, London, U
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