1,285 research outputs found
Computing Exact Clustering Posteriors with Subset Convolution
An exponential-time exact algorithm is provided for the task of clustering n
items of data into k clusters. Instead of seeking one partition, posterior
probabilities are computed for summary statistics: the number of clusters, and
pairwise co-occurrence. The method is based on subset convolution, and yields
the posterior distribution for the number of clusters in O(n * 3^n) operations,
or O(n^3 * 2^n) using fast subset convolution. Pairwise co-occurrence
probabilities are then obtained in O(n^3 * 2^n) operations. This is
considerably faster than exhaustive enumeration of all partitions.Comment: 6 figure
On the Outage Capacity of Orthogonal Space-time Block Codes Over Multi-cluster Scattering MIMO Channels
Multiple cluster scattering MIMO channel is a useful model for pico-cellular
MIMO networks. In this paper, orthogonal space-time block coded transmission
over such a channel is considered, where the effective channel equals the
product of n complex Gaussian matrices. A simple and accurate closed-form
approximation to the channel outage capacity has been derived in this setting.
The result is valid for an arbitrary number of clusters n-1 of scatterers and
an arbitrary antenna configuration. Numerical results are provided to study the
relative outage performance between the multi-cluster and the Rayleigh-fading
MIMO channels for which n=1.Comment: Added references; changes made in Section 3-
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