45 research outputs found
Optimal Base Station Placement: A Stochastic Method Using Interference Gradient In Downlink Case
In this paper, we study the optimal placement and optimal number of base
stations added to an existing wireless data network through the interference
gradient method. This proposed method considers a sub-region of the existing
wireless data network, hereafter called region of interest. In this region, the
provider wants to increase the network coverage and the users throughput. In
this aim, the provider needs to determine the optimal number of base stations
to be added and their optimal placement. The proposed approach is based on the
Delaunay triangulation of the region of interest and the gradient descent
method in each triangle to compute the minimum interference locations. We
quantify the increase of coverage and throughput.Comment: This work has been presented in the 5th International ICST Conference
on Performance Evaluation Methodologies and Tools (Valuetools 2011
New Cross-Layer Channel Switching Policy for TCP Transmission on 3G UMTS Downlink
In 3G UMTS, two main transport channels have been provided for downlink data
transmission: a common FACH channel and a dedicated DCH channel. The
performance of TCP in UMTS depends much on the channel switching policy used.
In this paper, we propose and analyze three new basic threshold-based channel
switching policies for UMTS that we name as QS (Queue Size), FS (Flow Size) and
QSFS (QS & FS combined) policy. These policies significantly improve over a
modified threshold policy in [1] by about 17% in response time metrics. We
further propose and evaluate a new improved switching policy that we call
FS-DCH (at-least flow-size threshold on DCH) policy. This policy is biased
towards short TCP flows of few packets and is thus a cross-layer policy that
improves the performance of TCP by giving priority to the initial few packets
of a flow on the fast DCH channel. Extensive simulation results confirm this
improvement for the case when number of TCP connections is low