348 research outputs found
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-
Wireless ad-hoc networks: Strategies and Scaling laws for the fixed SNR regime
This paper deals with throughput scaling laws for random ad-hoc wireless
networks in a rich scattering environment. We develop schemes to optimize the
ratio, of achievable network sum capacity to the sum of the
point-to-point capacities of source-destinations pairs operating in isolation.
For fixed SNR networks, i.e., where the worst case SNR over the
source-destination pairs is fixed independent of , we show that
collaborative strategies yield a scaling law of in contrast to multi-hop strategies which yield a
scaling law of . While, networks where
worst case SNR goes to zero, do not preclude the possibility of collaboration,
multi-hop strategies achieve optimal throughput. The plausible reason is that
the gains due to collaboration cannot offset the effect of vanishing receive
SNR. This suggests that for fixed SNR networks, a network designer should look
for network protocols that exploit collaboration. The fact that most current
networks operate in a fixed SNR interference limited environment provides
further motivation for considering this regime.Comment: 26 pages single column, submitted to Transactions on Information
Theor
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