1,621 research outputs found
Optimal Power Control and Scheduling under Hard Deadline Constraints for Continuous Fading Channels
We consider a joint scheduling-and-power-allocation problem of a downlink
cellular system. The system consists of two groups of users: real-time (RT) and
non-real-time (NRT) users. Given an average power constraint on the base
station, the problem is to find an algorithm that satisfies the RT hard
deadline constraint and NRT queue stability constraint. We propose a
sum-rate-maximizing algorithm that satisfies these constraints. We also show,
through simulations, that the proposed algorithm has an average complexity that
is close-to-linear in the number of RT users. The power allocation policy in
the proposed algorithm has a closed-form expression for the two groups of
users. However, interestingly, the power policy of the RT users differ in
structure from that of the NRT users. We also show the superiority of the
proposed algorithms over existing approaches using extensive simulations.Comment: Submitted to Asilomar 2017. arXiv admin note: text overlap with
arXiv:1612.0832
Energy Efficient Scheduling for Loss Tolerant IoT Applications with Uninformed Transmitter
In this work we investigate energy efficient packet scheduling problem for
the loss tolerant applications. We consider slow fading channel for a point to
point connection with no channel state information at the transmitter side
(CSIT). In the absence of CSIT, the slow fading channel has an outage
probability associated with every transmit power. As a function of data loss
tolerance parameters and peak power constraints, we formulate an optimization
problem to minimize the average transmit energy for the user equipment (UE).
The optimization problem is not convex and we use stochastic optimization
technique to solve the problem. The numerical results quantify the effect of
different system parameters on average transmit power and show significant
power savings for the loss tolerant applications.Comment: Published in ICC 201
Energy Optimal Transmission Scheduling in Wireless Sensor Networks
One of the main issues in the design of sensor networks is energy efficient
communication of time-critical data. Energy wastage can be caused by failed
packet transmission attempts at each node due to channel dynamics and
interference. Therefore transmission control techniques that are unaware of the
channel dynamics can lead to suboptimal channel use patterns. In this paper we
propose a transmission controller that utilizes different "grades" of channel
side information to schedule packet transmissions in an optimal way, while
meeting a deadline constraint for all packets waiting in the transmission
queue. The wireless channel is modeled as a finite-state Markov channel. We are
specifically interested in the case where the transmitter has low-grade channel
side information that can be obtained based solely on the ACK/NAK sequence for
the previous transmissions. Our scheduler is readily implementable and it is
based on the dynamic programming solution to the finite-horizon transmission
control problem. We also calculate the information theoretic capacity of the
finite state Markov channel with feedback containing different grades of
channel side information including that, obtained through the ACK/NAK sequence.
We illustrate that our scheduler achieves a given throughput at a power level
that is fairly close to the fundamental limit achievable over the channel.Comment: Accepted for publication in the IEEE Transactions on Wireless
Communication
Individual packet deadline delay constrained opportunistic scheduling for large multiuser systems
This work addresses opportunistic distributed multiuser scheduling in the presence of a fixed packet deadline delay
constraint. A threshold-based scheduling scheme is proposed which uses the instantaneous channel gain and
buffering time of the individual packets to schedule a group of users simultaneously in order to minimize the average
system energy consumption while fulfilling the deadline delay constraint for every packet. The multiuser environment
is modeled as a continuum of interference such that the optimization can be performed for each buffered packet
separately by using a Markov chain where the states represent the waiting time of each buffered packet. We analyze
the proposed scheme in the large user limit and demonstrate the delay-energy trade-off exhibited by the scheme. We
show that the multiuser scheduling can be broken into a packet-based scheduling problem in the large user limit and
the packet scheduling decisions are independent of the deadline delay distribution of the packets
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