480 research outputs found
Generalized Area Spectral Efficiency: An Effective Performance Metric for Green Wireless Communications
Area spectral efficiency (ASE) was introduced as a metric to quantify the
spectral utilization efficiency of cellular systems. Unlike other performance
metrics, ASE takes into account the spatial property of cellular systems. In
this paper, we generalize the concept of ASE to study arbitrary wireless
transmissions. Specifically, we introduce the notion of affected area to
characterize the spatial property of arbitrary wireless transmissions. Based on
the definition of affected area, we define the performance metric, generalized
area spectral efficiency (GASE), to quantify the spatial spectral utilization
efficiency as well as the greenness of wireless transmissions. After
illustrating its evaluation for point-to-point transmission, we analyze the
GASE performance of several different transmission scenarios, including
dual-hop relay transmission, three-node cooperative relay transmission and
underlay cognitive radio transmission. We derive closed-form expressions for
the GASE metric of each transmission scenario under Rayleigh fading environment
whenever possible. Through mathematical analysis and numerical examples, we
show that the GASE metric provides a new perspective on the design and
optimization of wireless transmissions, especially on the transmitting power
selection. We also show that introducing relay nodes can greatly improve the
spatial utilization efficiency of wireless systems. We illustrate that the GASE
metric can help optimize the deployment of underlay cognitive radio systems.Comment: 11 pages, 8 figures, accepted by TCo
Bandwidth Partitioning in Decentralized Wireless Networks
This paper addresses the following question, which is of interest in the
design of a multiuser decentralized network. Given a total system bandwidth of
W Hz and a fixed data rate constraint of R bps for each transmission, how many
frequency slots N of size W/N should the band be partitioned into in order to
maximize the number of simultaneous links in the network? Dividing the
available spectrum results in two competing effects. On the positive side, a
larger N allows for more parallel, noninterfering communications to take place
in the same area. On the negative side, a larger N increases the SINR
requirement for each link because the same information rate must be achieved
over less bandwidth. Exploring this tradeoff and determining the optimum value
of N in terms of the system parameters is the focus of the paper. Using
stochastic geometry, the optimal SINR threshold - which directly corresponds to
the optimal spectral efficiency - is derived for both the low SNR
(power-limited) and high SNR (interference-limited) regimes. This leads to the
optimum choice of the number of frequency bands N in terms of the path loss
exponent, power and noise spectral density, desired rate, and total bandwidth.Comment: Revised for IEEE Trans. Wireless Communications, April 2008
(initially submitted Nov. 2007). Results shown to apply to the exact outage
probability/transmitter density, rather than to nearest neighbor boun
Multiobjective Optimization in 5G Hybrid Networks
The increasing adoption of the Internet of Things has led to the need for systems with higher spectral and energy efficiency (EE) in order to enable communication. Larger data rate demands had led researchers to look at millimeter wave (mmWave) bands to boost network rates. This paper investigates the downlink performance of a three-tier heterogeneous network that consists of sub-6 GHz macrocells overlaid with small cells operating on both the mmWave and sub-6 GHz bands. A model is developed using tools from stochastic geometry to analyze the coverage, rate, area spectral efficiency, and EE of such a network. Various deployment strategies and their impacts on the considered metrics are studied. Simulation results are used to verify the validity of the proposed model
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