233 research outputs found
On the Role of Mobility for Multi-message Gossip
We consider information dissemination in a large -user wireless network in
which users wish to share a unique message with all other users. Each of
the users only has knowledge of its own contents and state information;
this corresponds to a one-sided push-only scenario. The goal is to disseminate
all messages efficiently, hopefully achieving an order-optimal spreading rate
over unicast wireless random networks. First, we show that a random-push
strategy -- where a user sends its own or a received packet at random -- is
order-wise suboptimal in a random geometric graph: specifically,
times slower than optimal spreading. It is known that this
gap can be closed if each user has "full" mobility, since this effectively
creates a complete graph. We instead consider velocity-constrained mobility
where at each time slot the user moves locally using a discrete random walk
with velocity that is much lower than full mobility. We propose a simple
two-stage dissemination strategy that alternates between individual message
flooding ("self promotion") and random gossiping. We prove that this scheme
achieves a close to optimal spreading rate (within only a logarithmic gap) as
long as the velocity is at least . The key
insight is that the mixing property introduced by the partial mobility helps
users to spread in space within a relatively short period compared to the
optimal spreading time, which macroscopically mimics message dissemination over
a complete graph.Comment: accepted to IEEE Transactions on Information Theory, 201
Wireless Network Stability in the SINR Model
We study the stability of wireless networks under stochastic arrival
processes of packets, and design efficient, distributed algorithms that achieve
stability in the SINR (Signal to Interference and Noise Ratio) interference
model.
Specifically, we make the following contributions. We give a distributed
algorithm that achieves -efficiency on all networks
(where is the number of links in the network), for all length monotone,
sub-linear power assignments. For the power control version of the problem, we
give a distributed algorithm with -efficiency (where is the length diversity of the link set).Comment: 10 pages, appeared in SIROCCO'1
On the stability of flow-aware CSMA
We consider a wireless network where each flow (instead of each link) runs
its own CSMA (Carrier Sense Multiple Access) algorithm. Specifically, each flow
attempts to access the radio channel after some random time and transmits a
packet if the channel is sensed idle. We prove that, unlike the standard CSMA
algorithm, this simple distributed access scheme is optimal in the sense that
the network is stable for all traffic intensities in the capacity region of the
network
ASUMAN: Age Sense Updating Multiple Access in Networks
We consider a fully-connected wireless gossip network which consists of a
source and receiver nodes. The source updates itself with a Poisson process
and also sends updates to the nodes as Poisson arrivals. Upon receiving the
updates, the nodes update their knowledge about the source. The nodes gossip
the data among themselves in the form of Poisson arrivals to disperse their
knowledge about the source. The total gossiping rate is bounded by a
constraint. The goal of the network is to be as timely as possible with the
source. In this work, we propose ASUMAN, a distributed opportunistic gossiping
scheme, where after each time the source updates itself, each node waits for a
time proportional to its current age and broadcasts a signal to the other nodes
of the network. This allows the nodes in the network which have higher age to
remain silent and only the low-age nodes to gossip, thus utilizing a
significant portion of the constrained total gossip rate. We calculate the
average age for a typical node in such a network with symmetric settings and
show that the theoretical upper bound on the age scales as . ASUMAN, with
an average age of , offers significant gains compared to a system where
the nodes just gossip blindly with a fixed update rate in which case the age
scales as
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