44,707 research outputs found
Interference Networks with Point-to-Point Codes
The paper establishes the capacity region of the Gaussian interference
channel with many transmitter-receiver pairs constrained to use point-to-point
codes. The capacity region is shown to be strictly larger in general than the
achievable rate regions when treating interference as noise, using successive
interference cancellation decoding, and using joint decoding. The gains in
coverage and achievable rate using the optimal decoder are analyzed in terms of
ensemble averages using stochastic geometry. In a spatial network where the
nodes are distributed according to a Poisson point process and the channel path
loss exponent is , it is shown that the density of users that can be
supported by treating interference as noise can scale no faster than
as the bandwidth grows, while the density of users can scale
linearly with under optimal decoding
An Advanced Tree Algorithm with Interference Cancellation in Uplink and Downlink
In this paper, we propose Advanced Tree-algorithm with Interference
Cancellation (ATIC), a variant of binary tree-algorithm with successive
interference cancellation (SICTA) introduced by Yu and Giannakis. ATIC assumes
that Interference Cancellation (IC) can be performed both by the access point
(AP), as in SICTA, but also by the users. Specifically, after every collision
slot, the AP broadcasts the observed collision as feedback. Users who
participated in the collision then attempt to perform IC by subtracting their
transmissions from the collision signal. This way, the users can resolve
collisions of degree 2 and, using a simple distributed arbitration algorithm
based on user IDs, ensure that the next slot will contain just a single
transmission. We show that ATIC reaches the asymptotic throughput of 0.924 as
the number of initially collided users tends to infinity and reduces the number
of collisions and packet delay. We also compare ATIC with other tree algorithms
and indicate the extra feedback resources it requires.Comment: This paper will be presented at the ASILOMAR Conference on Signals,
Systems, and Computer
Power control algorithms for CDMA networks based on large system analysis
Power control is a fundamental task accomplished in any wireless cellular
network; its aim is to set the transmit power of any mobile terminal, so that
each user is able to achieve its own target SINR. While conventional power
control algorithms require knowledge of a number of parameters of the signal of
interest and of the multiaccess interference, in this paper it is shown that in
a large CDMA system much of this information can be dispensed with, and
effective distributed power control algorithms may be implemented with very
little information on the user of interest. An uplink CDMA system subject to
flat fading is considered with a focus on the cases in which a linear MMSE
receiver and a non-linear MMSE serial interference cancellation receiver are
adopted; for the latter case new formulas are also given for the system SINR in
the large system asymptote. Experimental results show an excellent agreement
between the performance and the power profile of the proposed distributed
algorithms and that of conventional ones that require much greater prior
knowledge.Comment: To appear in the Proceedings of the 2007 IEEE International Symposium
on Information Theory, Nice, France, June 24 - 29, 200
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