Efficient Spectrum Allocation Research Articles

Multi-Stage Pricing Game for Collusion-Resistant Dynamic Spectrum Allocation

In order to fully utilize scarce spectrum resources, dynamic spectrum allocation becomes a promising approach to increase the spectrum efficiency for wireless networks. However, the collusion among selfish network users may seriously deteriorate the efficiency of dynamic spectrum sharing. The network users' behaviors and dynamics need to be taken into consideration for efficient and robust spectrum allocation. In this paper, we model the spectrum allocation in wireless networks with multiple selfish legacy spectrum holders and unlicensed users as multi-stage dynamic games. In order to combat user collusion, we propose a pricing-based collusion-resistant dynamic spectrum allocation approach to optimize overall spectrum efficiency, while not only keeping the participating incentives of the selfish users but also combating possible user collusion. The simulation results show that the proposed scheme achieves high efficiency of spectrum usage even with the presence of severe user collusion.

QoS-aware distributed spectrum sharing for heterogeneous wireless cognitive networks

Ubiquitous wireless networking calls for efficient dynamic spectrum allocation (DSA) among heterogeneous users with diverse transmission types and bandwidth demands. To meet user-specific quality-of-service (QoS) requirements, the power and spectrum allocated to each user should lie inside a bounded region in order to be meaningful for the intended application. Most existing DSA methods aim at enhancing the total system utility. As such, spectrum wastage may arise when the system-wise optimal allocation falls outside individual users' desired regions for QoS provisioning. The goal of this paper is to develop QoS-aware distributed DSA schemes using game-theoretic approach. We derive DSA solutions that respect QoS and avoid naively boosting or sacrificing some users' utilities to maximize the network spectrum utilization. Specifically, we propose two game-based DSA algorithms: one resorts to proper scaling of the transmission power according to each user's useful utility range, and the other embeds the QoS factor into the utility function used during gaming. To evaluate DSA schemes from a practical QoS perspective, we introduce two new metrics, namely ''system useful utility'' and ''fraction of QoS-satisfied users''. Simulations confirm that the proposed DSA techniques outperform existing QoS-blind game models in terms of the spectrum sharing efficiency in heterogeneous networks. Convergence analysis of the proposed QoS-aware DSA algorithms is also provided.

Satellite mobility pattern scheme for centrical and seamless handover management in LEO satellite networks

Since low earth orbit (LEO) satellite constellations have important advantages over geosynchronous earth orbit (GEO) systems such as low propagation delay, low power requirements, and more efficient spectrum allocation due to frequency reuse between satellites and spotbeams, they are considered to be used to complement the existing terrestrial fixed and wireless networks in the evolving global mobile network. However, one of the major problems with LEO satellites is their higher speed relative to the terrestrial mobile terminals, which move at lower speeds but at more random directions. Therefore, handover management in LEO satellite networks becomes a very challenging task for supporting global mobile communication. Efficient and accurate methods are needed for LEO satellite handovers between the moving footprints. In this paper, we propose a new seamless handover management scheme for LEO satellites (SeaHO-LEO), which utilizes the handover management schemes aiming at decreasing latency, data loss, and handover blocking probability. We also present another interesting handover management model called satellite mobility pattern based handover management in LEO satellites (PatHO-LEO) which takes mobility pattern of both satellites and mobile terminals into account to minimize the handover messaging traffic. This is achieved by the newly introduced billboard manager which is used for location updates of mobile users and satellites. The billboard manager makes the proposed handover model much more flexible and easier than the current solutions, since it is a central server and supports the management of the whole system. To show the performance of the proposed algorithms, we run an extensive set of simulations both for the proposed algorithms and well known handover management methods as a baseline model. The simulation results show that the proposed algorithms are very promising for seamless handover in LEO satellites.

Collaborative Allocation of Orthogonal Frequency Division Multiplex Sub-Carriers using the Swarm Intelligence

Future generations of wireless systems require op- portunistic spectrum access techniques to effectively detect and access temporarily unused spectrum bands. Cognitive radios, with their ability to learn and adapt to their environment, promise to possess such powerful capabilities. As a consequence, the spectrum allocation of a wireless system could quickly and appropriately auto-adapt to react to a sudden traffic variation. In this article, we propose an innovative and efficient distributed spectrum allocation algorithm, whose objective is to maximize the system UL capacity by exploiting multi- user diversity. The algorithm is capable of learning over time and of adapting the spectrum allocation when changes occur in the radio environment. Such an algorithm finds its application in the scope of future WLAN systems (e.g.: 802.11x).

Strategic and technological challenges for wireless communications beyond 3G

In order to facilitate and to meet the ever increasing demands for the wireless communication in the next decade and also to satisfy the high data rates for the new services, the future development of 3G (IMT2000) and systems beyond 3G (B3G) are foreseen. This article presents the need for these developments and motivations for systems beyond 3G taking into account both strategic and technological challenges to be faced. Moreover, the concepts and potential technologies involved including multiple air-interfaces, efficient spectrum allocation and utilisation for the success of systems B3G are briefly reviewed.

Spectrum auctions and efficient resource allocation: learning from the 3G experiences in Europe

Proposes a framework for the constructive application of 3G auctions. Suggests that other forms of auctions should be investigated, especially where the policy priority is rapid network rollout. Sums up that early experience with the 3G auctions in Europe points to several conclusions about efficient spectrum allocation and assignment.

LTPSK: simple, bandwidth efficient modulation for multi-rate satellite channels

A constant envelope modulation called linear-transition phase shift keying (LTPSK) is examined as a candidate for use as a bandwidth and power efficient modulation on nonlinear satellite channels. This modulation is similar to differential phase shift keying (DPSK), but with phase transitions realized as a linear phase ramp between symbols to decrease spectral occupancy without introducing amplitude variation. The ratio of phase-transition time to symbol duration is referred to as the LTPSK mode. Spectral occupancy and BER performance with differential detection vary between that of DPSK and differential minimum shift keying (MSK), depending on the mode selected. By making the LTPSK mode proportional to the data rate, a simple LTPSK modulator and differential demodulator can support multiple data rates without the need for a bank of filters. The highest rate supported has the lowest ratio of spectral occupancy to data rate, and spectral occupancy is approximately constant for all rates, allowing efficient spectrum allocation with fixed frequency assignments. >

Efficient spectrum allocation for personal communications services

Principal features of personal communications service (PCS), namely, ubiquity, portability, and integration of voice and data, are examined, highlighting some issues affecting the spectrum choices before today's policymakers. Spectrum issues are discussed, focusing on two tools for promoting efficient spectrum use: the use of generic service definitions and band assignment. >