136 research outputs found
Outage and Local Throughput and Capacity of Random Wireless Networks
Outage probabilities and single-hop throughput are two important performance
metrics that have been evaluated for certain specific types of wireless
networks. However, there is a lack of comprehensive results for larger classes
of networks, and there is no systematic approach that permits the convenient
comparison of the performance of networks with different geometries and levels
of randomness.
The uncertainty cube is introduced to categorize the uncertainty present in a
network. The three axes of the cube represent the three main potential sources
of uncertainty in interference-limited networks: the node distribution, the
channel gains (fading), and the channel access (set of transmitting nodes). For
the performance analysis, a new parameter, the so-called {\em spatial
contention}, is defined. It measures the slope of the outage probability in an
ALOHA network as a function of the transmit probability at . Outage is
defined as the event that the signal-to-interference ratio (SIR) is below a
certain threshold in a given time slot. It is shown that the spatial contention
is sufficient to characterize outage and throughput in large classes of
wireless networks, corresponding to different positions on the uncertainty
cube. Existing results are placed in this framework, and new ones are derived.
Further, interpreting the outage probability as the SIR distribution, the
ergodic capacity of unit-distance links is determined and compared to the
throughput achievable for fixed (yet optimized) transmission rates.Comment: 22 pages, 6 figures. Submitted to IEEE Trans. Wireles
Modeling Heterogeneous Network Interference Using Poisson Point Processes
Cellular systems are becoming more heterogeneous with the introduction of low
power nodes including femtocells, relays, and distributed antennas.
Unfortunately, the resulting interference environment is also becoming more
complicated, making evaluation of different communication strategies
challenging in both analysis and simulation. Leveraging recent applications of
stochastic geometry to analyze cellular systems, this paper proposes to analyze
downlink performance in a fixed-size cell, which is inscribed within a weighted
Voronoi cell in a Poisson field of interferers. A nearest out-of-cell
interferer, out-of-cell interferers outside a guard region, and cross-tier
interference are included in the interference calculations. Bounding the
interference power as a function of distance from the cell center, the total
interference is characterized through its Laplace transform. An equivalent
marked process is proposed for the out-of-cell interference under additional
assumptions. To facilitate simplified calculations, the interference
distribution is approximated using the Gamma distribution with second order
moment matching. The Gamma approximation simplifies calculation of the success
probability and average rate, incorporates small-scale and large-scale fading,
and works with co-tier and cross-tier interference. Simulations show that the
proposed model provides a flexible way to characterize outage probability and
rate as a function of the distance to the cell edge.Comment: Submitted to the IEEE Transactions on Signal Processing, July 2012,
Revised December 201
Packet Travel Times in Wireless Relay Chains under Spatially and Temporally Dependent Interference
We investigate the statistics of the number of time slots that it takes a
packet to travel through a chain of wireless relays. Derivations are performed
assuming an interference model for which interference possesses spatiotemporal
dependency properties. When using this model, results are harder to arrive at
analytically, but they are more realistic than the ones obtained in many
related works that are based on independent interference models.
First, we present a method for calculating the distribution of . As the
required computations are extensive, we also obtain simple expressions for the
expected value and variance . Finally, we
calculate the asymptotic limit of the average speed of the packet. Our
numerical results show that spatiotemporal dependence has a significant impact
on the statistics of the travel time . In particular, we show that, with
respect to the independent interference case, and
increase, whereas the packet speed decreases
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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