58,075 research outputs found
Performance analysis of call admission control algorithm for wireless multimedia networks
In todays wireless networks different wireless multimedia services have diverse bandwidth and QOS requirements, which need to be guaranteed by the wireless cellular networks. The decision to admit or reject the new user call is made by the call admission control algorithm.In this paper, a novel Call Admission Control algorithm for wireless cellular networks is proposed. The call admission control algorithm is based on power control. It determines the optimum number of admission users with optimum transmission power level so as to reduce the interference level and call blocking. By our simulation we show that our proposed call admission control algorithm reduces the blocking probability
Capacity of Cellular Wireless Network
Earlier definitions of capacity for wireless networks, e.g., transport or
transmission capacity, for which exact theoretical results are known, are well
suited for ad hoc networks but are not directly applicable for cellular
wireless networks, where large-scale basestation (BS) coordination is not
possible, and retransmissions/ARQ under the SINR model is a universal feature.
In this paper, cellular wireless networks, where both BS locations and mobile
user (MU) locations are distributed as independent Poisson point processes are
considered, and each MU connects to its nearest BS. With ARQ, under the SINR
model, the effective downlink rate of packet transmission is the reciprocal of
the expected delay (number of retransmissions needed till success), which we
use as our network capacity definition after scaling it with the BS density.
Exact characterization of this natural capacity metric for cellular wireless
networks is derived. The capacity is shown to first increase polynomially with
the BS density in the low BS density regime and then scale inverse
exponentially with the increasing BS density. Two distinct upper bounds are
derived that are relevant for the low and the high BS density regimes. A single
power control strategy is shown to achieve the upper bounds in both the
regimes. This result is fundamentally different from the well known capacity
results for ad hoc networks, such as transport and transmission capacity that
scale as the square root of the (high) BS density. Our results show that the
strong temporal correlations of SINRs with PPP distributed BS locations is
limiting, and the realizable capacity in cellular wireless networks in high-BS
density regime is much smaller than previously thought. A byproduct of our
analysis shows that the capacity of the ALOHA strategy with retransmissions is
zero.Comment: A shorter version to appear in WiOpt 201
Autonomous Algorithms for Centralized and Distributed Interference Coordination: A Virtual Layer Based Approach
Interference mitigation techniques are essential for improving the
performance of interference limited wireless networks. In this paper, we
introduce novel interference mitigation schemes for wireless cellular networks
with space division multiple access (SDMA). The schemes are based on a virtual
layer that captures and simplifies the complicated interference situation in
the network and that is used for power control. We show how optimization in
this virtual layer generates gradually adapting power control settings that
lead to autonomous interference minimization. Thereby, the granularity of
control ranges from controlling frequency sub-band power via controlling the
power on a per-beam basis, to a granularity of only enforcing average power
constraints per beam. In conjunction with suitable short-term scheduling, our
algorithms gradually steer the network towards a higher utility. We use
extensive system-level simulations to compare three distributed algorithms and
evaluate their applicability for different user mobility assumptions. In
particular, it turns out that larger gains can be achieved by imposing average
power constraints and allowing opportunistic scheduling instantaneously, rather
than controlling the power in a strict way. Furthermore, we introduce a
centralized algorithm, which directly solves the underlying optimization and
shows fast convergence, as a performance benchmark for the distributed
solutions. Moreover, we investigate the deviation from global optimality by
comparing to a branch-and-bound-based solution.Comment: revised versio
Optimal channel assignment and power control in wireless cellular networks
Wireless mobile communication is a fast growing field in current telecommunication industry. In a wireless cellular network, channel assignment is a mechanism that assigns channels to mobile users in order to establish a communication between a mobile terminal and a base station. It is important to determine an optimal allocation of channels that makes effective use of channels and minimizes call-blocking and call-dropping probabilities. Another important issue, the power control, is a problem of determining an optimal allocation of power levels to transmitters such that the power consumption is minimized while signal quality is maintained. In wireless mobile networks, channels and transmitter powers are limited resources. Therefore, efficient utilization of both those resources can significantly increase the capacity of network.
In this thesis, we solve such optimizations by the hybrid channel assignment (HCA) method using integer linear programming (ILP). Two novel sets of ILP formulation are proposed for two different cases: Reuse Distance based HCA without power control, and Carrier-to-Interference Ratio based HCA combined with power control. For each of them, our experimental results show an improvement over other several approaches
Cellular Underwater Wireless Optical CDMA Network: Potentials and Challenges
Underwater wireless optical communications is an emerging solution to the
expanding demand for broadband links in oceans and seas. In this paper, a
cellular underwater wireless optical code division multiple-access (UW-OCDMA)
network is proposed to provide broadband links for commercial and military
applications. The optical orthogonal codes (OOC) are employed as signature
codes of underwater mobile users. Fundamental key aspects of the network such
as its backhaul architecture, its potential applications and its design
challenges are presented. In particular, the proposed network is used as
infrastructure of centralized, decentralized and relay-assisted underwater
sensor networks for high-speed real-time monitoring. Furthermore, a promising
underwater localization and positioning scheme based on this cellular network
is presented. Finally, probable design challenges such as cell edge coverage,
blockage avoidance, power control and increasing the network capacity are
addressed.Comment: 11 pages, 10 figure
Modeling and Analysis of Cellular Networks Using Stochastic Geometry: A Tutorial
This paper presents a tutorial on stochastic geometry (SG)-based analysis for cellular networks. This tutorial is distinguished by its depth with respect to wireless communication details and its focus on cellular networks. This paper starts by modeling and analyzing the baseband interference in a baseline single-tier downlink cellular network with single antenna base stations and universal frequency reuse. Then, it characterizes signal-to-interference-plus-noise-ratio and its related performance metrics. In particular, a unified approach to conduct error probability, outage probability, and transmission rate analysis is presented. Although the main focus of this paper is on cellular networks, the presented unified approach applies for other types of wireless networks that impose interference protection around receivers. This paper then extends the unified approach to capture cellular network characteristics (e.g., frequency reuse, multiple antenna, power control, etc.). It also presents numerical examples associated with demonstrations and discussions. To this end, this paper highlights the state-of-the-art research and points out future research directions
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