4,989 research outputs found
Optimal Distributed Scheduling in Wireless Networks under the SINR interference model
Radio resource sharing mechanisms are key to ensuring good performance in
wireless networks. In their seminal paper \cite{tassiulas1}, Tassiulas and
Ephremides introduced the Maximum Weighted Scheduling algorithm, and proved its
throughput-optimality. Since then, there have been extensive research efforts
to devise distributed implementations of this algorithm. Recently, distributed
adaptive CSMA scheduling schemes \cite{jiang08} have been proposed and shown to
be optimal, without the need of message passing among transmitters. However
their analysis relies on the assumption that interference can be accurately
modelled by a simple interference graph. In this paper, we consider the more
realistic and challenging SINR interference model. We present {\it the first
distributed scheduling algorithms that (i) are optimal under the SINR
interference model, and (ii) that do not require any message passing}. They are
based on a combination of a simple and efficient power allocation strategy
referred to as {\it Power Packing} and randomization techniques. We first
devise algorithms that are rate-optimal in the sense that they perform as well
as the best centralized scheduling schemes in scenarios where each transmitter
is aware of the rate at which it should send packets to the corresponding
receiver. We then extend these algorithms so that they reach
throughput-optimality
“CSMA-Based Link Scheduling in Multihop MIMO Networks using SINR Model ”
The main aim of this study to resolve the problem of distributed scheduling in multi-hop MIMO networks. We will first develop a “MIMO pipe” model which will provide the required SINR , which gives the rate-reliability tradeoff in MIMO communications.Here we are going to study development of CSMA-based MIMO-pipe scheduling especially under the SINR model.We are going to choose the SINR model over the conventionally studied matching or protocol-based interference models because it has ability to capture the impact of interference in wireless networks. Here each node is equipped with an antenna array. In CSMA based scheduling, nodes will first sense the channel activity before attempting transmissions, whenever the channel is sensed to be idle, the nodes will continue with data transmissions. When the channel is detected to be busy, the nodes have to wait for a random amount of backoff time before reattempting the transmission.We will study that protocol model based throughput-optimal CSMA based scheduling, would not work well under the SINR model because its has dynamic and intrinsic link coupling. To tackle this challenge,CSMA-based MIMO-pipe scheduling is develpoed in both discrete-time system and continuous-time system
Wireless Scheduling with Power Control
We consider the scheduling of arbitrary wireless links in the physical model
of interference to minimize the time for satisfying all requests. We study here
the combined problem of scheduling and power control, where we seek both an
assignment of power settings and a partition of the links so that each set
satisfies the signal-to-interference-plus-noise (SINR) constraints.
We give an algorithm that attains an approximation ratio of , where is the number of links and is the ratio
between the longest and the shortest link length. Under the natural assumption
that lengths are represented in binary, this gives the first approximation
ratio that is polylogarithmic in the size of the input. The algorithm has the
desirable property of using an oblivious power assignment, where the power
assigned to a sender depends only on the length of the link. We give evidence
that this dependence on is unavoidable, showing that any
reasonably-behaving oblivious power assignment results in a -approximation.
These results hold also for the (weighted) capacity problem of finding a
maximum (weighted) subset of links that can be scheduled in a single time slot.
In addition, we obtain improved approximation for a bidirectional variant of
the scheduling problem, give partial answers to questions about the utility of
graphs for modeling physical interference, and generalize the setting from the
standard 2-dimensional Euclidean plane to doubling metrics. Finally, we explore
the utility of graph models in capturing wireless interference.Comment: Revised full versio
On Wireless Scheduling Using the Mean Power Assignment
In this paper the problem of scheduling with power control in wireless
networks is studied: given a set of communication requests, one needs to assign
the powers of the network nodes, and schedule the transmissions so that they
can be done in a minimum time, taking into account the signal interference of
concurrently transmitting nodes. The signal interference is modeled by SINR
constraints. Approximation algorithms are given for this problem, which use the
mean power assignment. The problem of schduling with fixed mean power
assignment is also considered, and approximation guarantees are proven
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