2,054 research outputs found
Energy-Efficient selective activation in Femtocell Networks
Provisioning the capacity of wireless networks is difficult when peak load is significantly higher than average load, for example, in public spaces like airports or train stations. Service providers can use femtocells and small cells to increase local capacity, but deploying enough femtocells to serve peak loads requires a large number of femtocells that will remain idle most of the time, which wastes a significant amount of power.
To reduce the energy consumption of over-provisioned femtocell networks, we formulate a femtocell selective activation problem, which we formalize as an integer nonlinear optimization problem. Then we introduce GREENFEMTO, a distributed femtocell selective activation algorithm that deactivates idle femtocells to
save power and activates them on-the-fly as the number of users increases. We prove that GREENFEMTO converges to a locally Pareto optimal solution and demonstrate its performance using extensive simulations of an LTE wireless system. Overall, we find that GREENFEMTO requires up to 55% fewer femtocells to serve a given user load, relative to an existing femtocell power-saving procedure, and comes within 15% of a globally optimal solution
Opportunistic Third-Party Backhaul for Cellular Wireless Networks
With high capacity air interfaces and large numbers of small cells, backhaul
-- the wired connectivity to base stations -- is increasingly becoming the cost
driver in cellular wireless networks. One reason for the high cost of backhaul
is that capacity is often purchased on leased lines with guaranteed rates
provisioned to peak loads. In this paper, we present an alternate
\emph{opportunistic backhaul} model where third parties provide base stations
and backhaul connections and lease out excess capacity in their networks to the
cellular provider when available, presumably at significantly lower costs than
guaranteed connections. We describe a scalable architecture for such
deployments using open access femtocells, which are small plug-and-play base
stations that operate in the carrier's spectrum but can connect directly into
the third party provider's wired network. Within the proposed architecture, we
present a general user association optimization algorithm that enables the
cellular provider to dynamically determine which mobiles should be assigned to
the third-party femtocells based on the traffic demands, interference and
channel conditions and third-party access pricing. Although the optimization is
non-convex, the algorithm uses a computationally efficient method for finding
approximate solutions via dual decomposition. Simulations of the deployment
model based on actual base station locations are presented that show that large
capacity gains are achievable if adoption of third-party, open access
femtocells can reach even a small fraction of the current market penetration of
WiFi access points.Comment: 9 pages, 6 figure
Price-Based Resource Allocation for Spectrum-Sharing Femtocell Networks: A Stackelberg Game Approach
This paper investigates the price-based resource allocation strategies for
the uplink transmission of a spectrum-sharing femtocell network, in which a
central macrocell is underlaid with distributed femtocells, all operating over
the same frequency band as the macrocell. Assuming that the macrocell base
station (MBS) protects itself by pricing the interference from the femtocell
users, a Stackelberg game is formulated to study the joint utility maximization
of the macrocell and the femtocells subject to a maximum tolerable interference
power constraint at the MBS. Especially, two practical femtocell channel
models: sparsely deployed scenario for rural areas and densely deployed
scenario for urban areas, are investigated. For each scenario, two pricing
schemes: uniform pricing and non-uniform pricing, are proposed. Then, the
Stackelberg equilibriums for these proposed games are studied, and an effective
distributed interference price bargaining algorithm with guaranteed convergence
is proposed for the uniform-pricing case. Finally, numerical examples are
presented to verify the proposed studies. It is shown that the proposed
algorithms are effective in resource allocation and macrocell protection
requiring minimal network overhead for spectrum-sharing-based two-tier
femtocell networks.Comment: 27 pages, 7 figures, Submitted to JSA
Interference-Aware Downlink Resource Management for OFDMA Femtocell Networks
Femtocell is an economical solution to provide high speed indoor communication instead of the conventional macro-cellular networks. Especially, OFDMA femtocell is considered in the next generation cellular network such as 3GPP LTE and mobile WiMAX system. Although the femtocell has great advantages to accommodate indoor users, interference management problem is a critical issue to operate femtocell network. Existing OFDMA resource management algorithms only consider optimizing system-centric metric, and cannot manage the co-channel interference. Moreover, it is hard to cooperate with other femtocells to control the interference, since the self-configurable characteristics of femtocell. This paper proposes a novel interference-aware resource allocation algorithm for OFDMA femtocell networks. The proposed algorithm allocates resources according to a new objective function which reflects the effect of interference, and the heuristic algorithm is also introduced to reduce the complexity of the original problem. The Monte-Carlo simulation is performed to evaluate the performance of the proposed algorithm compared to the existing solutions
Handover Management in Highly Dense Femtocellular Networks
For dense femtocells, intelligent integrated femtocell/macrocell network
architecture, a neighbor cell list with a minimum number of femtocells,
effective call admission control (CAC), and handover processes with proper
signaling are the open research issues. An appropriate traffic model for the
integrated femtocell/macrocell network is also not yet developed. In this
paper, we present the major issue of mobility management for the integrated
femtocell/macrocell network. We propose a novel algorithm to create a neighbor
cell list with a minimum, but appropriate, number of cells for handover. We
also propose detailed handover procedures and a novel traffic model for the
integrated femtocell/macrocell network. The proposed CAC effectively handles
various calls. The numerical and simulation results show the importance of the
integrated femtocell/macrocell network and the performance improvement of the
proposed schemes. Our proposed schemes for dense femtocells will be very
effective for those in research and industry to implement
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