11,285 research outputs found
Energy-Optimal Scheduling in Low Duty Cycle Sensor Networks
Energy consumption of a wireless sensor node mainly depends on the amount of
time the node spends in each of the high power active (e.g., transmit, receive)
and low power sleep modes. It has been well established that in order to
prolong node's lifetime the duty-cycle of the node should be low. However, low
power sleep modes usually have low current draw but high energy cost while
switching to the active mode with a higher current draw. In this work, we
investigate a MaxWeightlike opportunistic sleep-active scheduling algorithm
that takes into account time- varying channel and traffic conditions. We show
that our algorithm is energy optimal in the sense that the proposed ESS
algorithm can achieve an energy consumption which is arbitrarily close to the
global minimum solution. Simulation studies are provided to confirm the
theoretical results
Throughput Optimal Scheduling with Dynamic Channel Feedback
It is well known that opportunistic scheduling algorithms are throughput
optimal under full knowledge of channel and network conditions. However, these
algorithms achieve a hypothetical achievable rate region which does not take
into account the overhead associated with channel probing and feedback required
to obtain the full channel state information at every slot. We adopt a channel
probing model where fraction of time slot is consumed for acquiring the
channel state information (CSI) of a single channel. In this work, we design a
joint scheduling and channel probing algorithm named SDF by considering the
overhead of obtaining the channel state information. We first analytically
prove SDF algorithm can support fraction of of the full rate
region achieved when all users are probed where depends on the
expected number of users which are not probed. Then, for homogenous channel, we
show that when the number of users in the network is greater than 3, , i.e., we guarantee to expand the rate region. In addition, for
heterogenous channels, we prove the conditions under which SDF guarantees to
increase the rate region. We also demonstrate numerically in a realistic
simulation setting that this rate region can be achieved by probing only less
than 50% of all channels in a CDMA based cellular network utilizing high data
rate protocol under normal channel conditions.Comment: submitte
Cross-layer design of multi-hop wireless networks
MULTI -hop wireless networks are usually defined as a collection of nodes
equipped with radio transmitters, which not only have the capability to
communicate each other in a multi-hop fashion, but also to route each others’ data
packets. The distributed nature of such networks makes them suitable for a variety of
applications where there are no assumed reliable central entities, or controllers, and
may significantly improve the scalability issues of conventional single-hop wireless
networks.
This Ph.D. dissertation mainly investigates two aspects of the research issues
related to the efficient multi-hop wireless networks design, namely: (a) network
protocols and (b) network management, both in cross-layer design paradigms to
ensure the notion of service quality, such as quality of service (QoS) in wireless mesh
networks (WMNs) for backhaul applications and quality of information (QoI) in
wireless sensor networks (WSNs) for sensing tasks. Throughout the presentation of
this Ph.D. dissertation, different network settings are used as illustrative examples,
however the proposed algorithms, methodologies, protocols, and models are not
restricted in the considered networks, but rather have wide applicability.
First, this dissertation proposes a cross-layer design framework integrating
a distributed proportional-fair scheduler and a QoS routing algorithm, while using
WMNs as an illustrative example. The proposed approach has significant performance
gain compared with other network protocols. Second, this dissertation proposes
a generic admission control methodology for any packet network, wired and
wireless, by modeling the network as a black box, and using a generic mathematical
0. Abstract 3
function and Taylor expansion to capture the admission impact. Third, this dissertation
further enhances the previous designs by proposing a negotiation process,
to bridge the applications’ service quality demands and the resource management,
while using WSNs as an illustrative example. This approach allows the negotiation
among different service classes and WSN resource allocations to reach the optimal
operational status. Finally, the guarantees of the service quality are extended to
the environment of multiple, disconnected, mobile subnetworks, where the question
of how to maintain communications using dynamically controlled, unmanned data
ferries is investigated
- …