Channel allocation schemes

About: Channel allocation schemes is a research topic. Over the lifetime, 10656 publications have been published within this topic receiving 182117 citations.

Performance of Distributed Dynamic Frequency Selection Schemes for Interference Reducing Networks

Abstract: One of the more commonly envisioned algorithms for cognitive radios is spectrum filling via dynamic frequency selection. Applying the cognitive radio design framework proposed in [1], we formalize a low complexity distributed ad-hoc dynamic frequency sele ction algorithm that converges to near-minimal interference frequency re-use patterns. We then examine the performance of this algorithm in the presences of practical considerations such as intra-network policy variations and timing issues and show that while this leads to situations that violate the framework of [1], the steady-state and convergence properties of the framework are still preserved. 1. This work was made possible through the support basic research grant # N000140310629 from the Office of Naval Research, the National Science Foundation Integrated Graduate Education and Research Training (IGERT) sponsored Integrated Research and Education in Advanced Networking (IREAN) fellowship and the support of MPRG and Wireless @ Virginia Tech industrial affiliates.

Method and apparatus for updating carrier channel allocations

Abstract: In a communication system that utilizes DMT technology to couple a primary site (102) to a plurality of secondary sites (104-108), carrier channel allocations may be updated as follows. At periodic intervals, the primary site requests updating bit loading information from the secondary sites. Upon receiving the updated bit loading information, the primary site (102) determines an updated call bit loading table for each active call. From this, the primary site (102) determines whether current carrier channel allocation provides sufficient bandwidth. When the current carrier channel allocation does not provide the sufficient bandwidth, the primary site modifies the current carrier channel allocation to meet the bandwidth requirements.

Optimal Cooperative Internetwork Spectrum Sharing for Cognitive Radio Systems With Spectrum Pooling

Abstract: Spectrum pooling in cognitive radio systems is an approach to manage the available spectrum bands from different licensed networks. Most previous work on spectrum pooling concentrates on the system architecture and the design of flexible-access algorithms and schemes. In this paper, we present a cooperative scheme for internetwork spectrum sharing among multiple secondary systems, which takes into account the price and spectrum efficiency as the design criteria. Specifically, the spectrum-sharing problem is formulated as a stochastic bandit system; thus, the optimal spectrum-sharing scheme is simply allocating the new available band to the secondary network with the lowest index. Extensive simulation examples illustrate that the proposed scheme significantly improves the performance compared with the existing scheme that ignores optimal spectrum sharing.

Adaptive resource allocation in metropolitan area cellular mobile radio systems

Abstract: It is shown that microcellular structures which will be found in future high-density traffic metropolitan areas require the application of adaptive methods for efficiently allocating the radio resource. Different dimensions of adaptation-adaptive base station allocation, dynamic channel allocation, and adaptive power control-are considered in an integrated manner. To answer if and how the proposed methods can work together, a generic algorithm comprising the different adaptive approaches is introduced. This was complemented by the derivation and definition of a comprehensive set of evaluation criteria. For the evaluation a simulation environment is developed, based on a Manhattan-like road grid structure, and comprising corresponding traffic and propagation models. First results indicate that the combined application of the different adaptation approaches yields the best performance. >

Practical multiuser diversity with outdated channel feedback

Abstract: Inspired by the information theoretic results concerning multiuser diversity, we address practical issues in implementing multiuser diversity in a multiple access wireless setting. Considering a channel-assigning strategy that assigns the channel only to the user with the best instantaneous SNR , our emphasis is on the effects of channel feedback delay in downlink transmissions. A finite set of M-ary quadrature amplitude modulation (M-QAM) constellations is adopted and a constant transmit power is assumed in this practical multiuser adaptive modulation scheme. Based on the closed-form expressions for average bit error rate (BER) and average data rate, we illustrate the impact of channel feedback delay on the achievable multiuser diversity gain with the number of users. Simple and accurate asymptotic approximations are also provided in the limit of large numbers of users. Focusing on different applications, we propose two optimization criteria for the switching thresholds, based on either an average BER, or an outage probability constraint. Two novel constant power, variable rate M-QAM schemes that are less sensitive to feedback delay are proposed using the optimal switching thresholds, which are derived to maximize the average data rate subject to these two constraints, respectively. To obtain a certain degree of fairness among the users, we also consider a fair channel-assigning strategy that assigns the channel to only the user with the greatest normalized SNR.