3,421 research outputs found
Bandwidth Partitioning in Decentralized Wireless Networks
This paper addresses the following question, which is of interest in the
design of a multiuser decentralized network. Given a total system bandwidth of
W Hz and a fixed data rate constraint of R bps for each transmission, how many
frequency slots N of size W/N should the band be partitioned into in order to
maximize the number of simultaneous links in the network? Dividing the
available spectrum results in two competing effects. On the positive side, a
larger N allows for more parallel, noninterfering communications to take place
in the same area. On the negative side, a larger N increases the SINR
requirement for each link because the same information rate must be achieved
over less bandwidth. Exploring this tradeoff and determining the optimum value
of N in terms of the system parameters is the focus of the paper. Using
stochastic geometry, the optimal SINR threshold - which directly corresponds to
the optimal spectral efficiency - is derived for both the low SNR
(power-limited) and high SNR (interference-limited) regimes. This leads to the
optimum choice of the number of frequency bands N in terms of the path loss
exponent, power and noise spectral density, desired rate, and total bandwidth.Comment: Revised for IEEE Trans. Wireless Communications, April 2008
(initially submitted Nov. 2007). Results shown to apply to the exact outage
probability/transmitter density, rather than to nearest neighbor boun
Large-Scale Distributed Internet-based Discovery Mechanism for Dynamic Spectrum Allocation
Scarcity of frequencies and the demand for more bandwidth is likely to
increase the need for devices that utilize the available frequencies more
efficiently. Radios must be able to dynamically find other users of the
frequency bands and adapt so that they are not interfered, even if they use
different radio protocols. As transmitters far away may cause as much
interference as a transmitter located nearby, this mechanism can not be based
on location alone. Central databases can be used for this purpose, but require
expensive infrastructure and planning to scale. In this paper, we propose a
decentralized protocol and architecture for discovering radio devices over the
Internet. The protocol has low resource requirements, making it suitable for
implementation on limited platforms. We evaluate the protocol through
simulation in network topologies with up to 2.3 million nodes, including
topologies generated from population patterns in Norway. The protocol has also
been implemented as proof-of-concept in real Wi-Fi routers.Comment: Accepted for publication at IEEE DySPAN 201
Turbo-Aggregate: Breaking the Quadratic Aggregation Barrier in Secure Federated Learning
Federated learning is a distributed framework for training machine learning
models over the data residing at mobile devices, while protecting the privacy
of individual users. A major bottleneck in scaling federated learning to a
large number of users is the overhead of secure model aggregation across many
users. In particular, the overhead of the state-of-the-art protocols for secure
model aggregation grows quadratically with the number of users. In this paper,
we propose the first secure aggregation framework, named Turbo-Aggregate, that
in a network with users achieves a secure aggregation overhead of
, as opposed to , while tolerating up to a user dropout
rate of . Turbo-Aggregate employs a multi-group circular strategy for
efficient model aggregation, and leverages additive secret sharing and novel
coding techniques for injecting aggregation redundancy in order to handle user
dropouts while guaranteeing user privacy. We experimentally demonstrate that
Turbo-Aggregate achieves a total running time that grows almost linear in the
number of users, and provides up to speedup over the
state-of-the-art protocols with up to users. Our experiments also
demonstrate the impact of model size and bandwidth on the performance of
Turbo-Aggregate
- …