451 research outputs found
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
Self-optimized Coverage Coordination in Femtocell Networks
This paper proposes a self-optimized coverage coordination scheme for
two-tier femtocell networks, in which a femtocell base station adjusts the
transmit power based on the statistics of the signal and the interference power
that is measured at a femtocell downlink. Furthermore, an analytic expression
is derived for the coverage leakage probability that a femtocell coverage area
leaks into an outdoor macrocell. The coverage analysis is verified by
simulation, which shows that the proposed scheme provides sufficient indoor
femtocell coverage and that the femtocell coverage does not leak into an
outdoor macrocell.Comment: 16 pages, 5 figure
Low energy indoor network : deployment optimisation
This article considers what the minimum energy indoor access point deployment is in order to achieve a certain downlink quality-of-service. The article investigates two conventional multiple-access technologies, namely: LTE-femtocells and 802.11n Wi-Fi. This is done in a dynamic multi-user and multi-cell interference network. Our baseline results are reinforced by novel theoretical expressions. Furthermore, the work underlines the importance of considering optimisation when accounting for the capacity saturation of realistic modulation and coding schemes. The results in this article show that optimising the location of access points both within a building and within the individual rooms is critical to minimise the energy consumption
Spectrum Leasing as an Incentive towards Uplink Macrocell and Femtocell Cooperation
The concept of femtocell access points underlaying existing communication
infrastructure has recently emerged as a key technology that can significantly
improve the coverage and performance of next-generation wireless networks. In
this paper, we propose a framework for macrocell-femtocell cooperation under a
closed access policy, in which a femtocell user may act as a relay for
macrocell users. In return, each cooperative macrocell user grants the
femtocell user a fraction of its superframe. We formulate a coalitional game
with macrocell and femtocell users being the players, which can take individual
and distributed decisions on whether to cooperate or not, while maximizing a
utility function that captures the cooperative gains, in terms of throughput
and delay.We show that the network can selforganize into a partition composed
of disjoint coalitions which constitutes the recursive core of the game
representing a key solution concept for coalition formation games in partition
form. Simulation results show that the proposed coalition formation algorithm
yields significant gains in terms of average rate per macrocell user, reaching
up to 239%, relative to the non-cooperative case. Moreover, the proposed
approach shows an improvement in terms of femtocell users' rate of up to 21%
when compared to the traditional closed access policy.Comment: 29 pages, 11 figures, accepted at the IEEE JSAC on Femtocell Network
Power Control in Two-Tier Femtocell Networks
In a two tier cellular network -- comprised of a central macrocell underlaid
with shorter range femtocell hotspots -- cross-tier interference limits overall
capacity with universal frequency reuse. To quantify near-far effects with
universal frequency reuse, this paper derives a fundamental relation providing
the largest feasible cellular Signal-to-Interference-Plus-Noise Ratio (SINR),
given any set of feasible femtocell SINRs. We provide a link budget analysis
which enables simple and accurate performance insights in a two-tier network. A
distributed utility-based SINR adaptation at femtocells is proposed in order to
alleviate cross-tier interference at the macrocell from cochannel femtocells.
The Foschini-Miljanic (FM) algorithm is a special case of the adaptation. Each
femtocell maximizes their individual utility consisting of a SINR based reward
less an incurred cost (interference to the macrocell). Numerical results show
greater than 30% improvement in mean femtocell SINRs relative to FM. In the
event that cross-tier interference prevents a cellular user from obtaining its
SINR target, an algorithm is proposed that reduces transmission powers of the
strongest femtocell interferers. The algorithm ensures that a cellular user
achieves its SINR target even with 100 femtocells/cell-site, and requires a
worst case SINR reduction of only 16% at femtocells. These results motivate
design of power control schemes requiring minimal network overhead in two-tier
networks with shared spectrum.Comment: 29 pages, 10 figures, Revised and resubmitted to the IEEE
Transactions on Wireless Communication
- …