Flexible Frequency-Band Reallocation Networks Using Variable Oversampled Complex-Modulated Filter Banks
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Research Article Flexible Frequency-Band Reallocation Networks Using Variable Oversampled Complex-Modulated Filter Banks ¨ H˚akan Johansson and Per Lowenborg Electronics Systems, Department of Electrical Engineering, Link¨oping University, 58183 Link¨oping, Sweden Received 22 December 2005; Revised 17 May 2006; Accepted 16 July 2006 Recommended by Soontorn Oraintara A crucial issue in the next-generation satellite-based communication systems is the satellite on-board reallocation of information which requires digital flexible frequency-band reallocation (FBR) networks. This paper introduces a new class of flexible FBR networks based on variable oversampled complex-modulated filter banks (FBs). The new class can outperform the previously existing ones when all the aspects flexibility, low complexity and inherent parallelism, near-perfect frequency-band reallocation, and simplicity are considered simultaneously. Copyright © 2007 H. Johansson and P. L¨owenborg. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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INTRODUCTION
The future society foresees globally interconnected digital communication systems offering multimedia services, information on demand, and delivery of information (data) at high data rates and low cost and with high performance. Terrestrial networks could in principle meet the requirements on communication capacity due to the practically unlimited bandwidth provided by fiber optic cables, but this capacity is rarely available today. A large investment is required to bridge the distance between the local exchange and the customer. It is therefore internationally recognized that satellite systems will play an important complementary role in providing the global coverage required for both fixed and mobile communications [1–3]. However, to meet the requirements of the communication systems of tomorrow, it is imperative to develop a new generation of satellite systems, payload architectures, ground technologies, and techniques combining flexibility with cost efficiency. It is envisaged that the improvements required as to the capacity as well as complexity fall in the range of one and two orders of magnitude [1]. The European Space Agency (ESA) outlines three major standard architectures for future broadband systems [1]. Two of these are the distributed access network and professional user network which are to provide high-capacity point-topoint and multicast services for ubiquitous Internet access.
The satellites are to communicate with user units via multiple spot beams. In order to use the limited available frequency spectrum efficiently, the satellite on-board signal processing must support frequency-band reusage among the beams and also flexibility in bandwidth and transmitted power allocated to each user. Further, dynamic frequency allocation is desired for covering different service types requiring different data rates and bandwidths.
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