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Virgilio Rodriguez Klaus Moessner Rahim Tafazolli 《Mobile Networks and Applications》2006,11(6):847-860
The radio frequency spectrum is a naturally limited resource of extraordinary value, as the key to the provision of important
communication and information services. Traditionally, spectrum has been allocated first to specific access technologies,
and then sub-allocated to specific access networks, on very long term basis (up to decades). The traditional scheme can be
very inefficient when demand patterns (“loads”) exhibit high temporal and spatial variations. Dynamic spectrum allocation
(DSA) improves radio spectrum efficiency by adjusting the allocation as demand changes in time and/or space. In previous work,
we introduced a DSA scheme in which a spectrum manager periodically auctions short-term spectrum licenses. The scheme can
be supported by a realistic “pooling” business model, and can work with many radio-access technologies. But our previous analysis
only considers a code-division multiple access (CDMA) technology; and DSA provides the greatest benefits with the participation
of networks having complementary “busy hours,” such as video entertainment services and cellular telephony. Here, a digital
video broadcast (DVB) terrestrial network joins the scheme. A typical DVB terrestrial cell is (much) larger than a UMTS cell.
This brings to the forefront inter-cell interference, and inter-related auctions in different cells. To capture the essence
of these issues we focus first on a situation where one DVB terrestrial cell overlays two adjacent CDMA cells. Subsequently
we discuss extensions to richer scenarios. The contributions of the present work over our previous publications include to
: (i) address the impact of inter-cell interference among several CDMA cells, (ii) introduce the DVB access technology into
the DSA scheme, (iii) modify the auction scheme to consider that a DVB cell overlays several CDMA cells, (iv) characterise
analytically the marketing and bidding behaviour of the DVB network.
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Rahim TafazolliEmail: |
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针对低仰角宽带地空通信中信道多径时延较大和快速时变的特点,提出了一种多址方式新颖的星型网组网方案.其内向链路采用基于Golay互补序列的异步码分多址方式,其外向链路采用基于Walsh序列的M元扩频码分复用技术,内向链路抗多址干扰能力很强,两种链路的接收端 都因结合了滤波器组频域均衡技术(FB-FDE)因而具有很强的抗多径衰落能力,并具有频带效率高,结构简单等优点.这种多址接入方式和组网方案很适合于低仰角下宽带地空通信信道环境中的应用,其主要性能得到仿真验证,具有很好的应用前景. 相似文献
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Juan Cantillo Bernhard Collini‐Nocker Ulrik De Bie Oscar Del Rio Gorry Fairhurst Axel Jahn Rita Rinaldo 《International Journal of Satellite Communications and Networking》2008,26(3):231-250
The second‐generation specification for Digital Video Broadcast over Satellite, DVB‐S2, defines an improved and adaptive physical layer. A new framing structure at the link layer, known as the generic stream (GS), is introduced offering an alternative to the well‐known MPEG transport stream (TS). This paper presents the requirements for and the design of an encapsulation protocol to transport IPv4 and IPv6 datagrams and other network protocol packets directly over DVB‐S2 using this GS profile. The resulting generic stream encapsulation (GSE) is a novel method that provides flexible encapsulation with support for fragmentation. A flexible extension header format allows GSE to carry additional header information, suitable for enhanced features, such as link layer encryption and IP header compression. The paper assesses GSE performance by simulation using realistic traffic profiles and attenuation fading. This demonstrates considerable improvement in efficiency compared with the MPE/MPEG‐2 TS, especially when used with adaptive coding and modulation (ACM). Although designed for DVB‐S2 systems, the new encapsulation is suitable for other second‐generation physical layer standards. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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The integration of cellular and VoIP over WLAN (VoWLAN) systems recently has attracted considerable interest from both academia
and industry. A cellular/VoWLAN dual-mode system enables users to access a low-cost VoIP service in a WLAN hotspot and switch
to a wide-area cellular system without WLANs. Unfortunately, cellular/VoWLAN dual-mode mobiles suffer the power consumption
problem that becomes one of the major concerns for commercial deployment of the dual-mode service. In this study, we present
a novel power saving mechanism, called PIANO (paging via another radio), for the integration of heterogeneous wireless networks,
and further apply the proposed methods to implement a cellular/VoWLAN dual-mode system. Based on the proposed mechanisms,
a dual-mode mobile can completely switch off its WLAN interface, only leaving the cellular interface awake to listen to paging
messages. When a mobile receives a paging message from its cellular interface, it wakes up the WLAN interface and responds
to connection requests via WLAN networks. Therefore, a dual-mode mobile reduces the power consumption by turning off the WLAN
interface during idle, and can also receive VoWLAN services. Measurement results based on the prototype system demonstrate
that the proposed methods significantly extend the standby hours of a dual-mode mobile. 相似文献
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This paper presents an overview of a new very high throughput millimeter- wave WLAN system operating at 45 GHz band. We begin by reviewing standards process of IEEE 802.11aj (45GHz). Then the frequency spectrum allocation at 45 GHz band is introduced. Next, the channel measurement and mod-eling is given. Specifically, the millimeter-wave MIMO for physical layer enhancement is given in detail. 相似文献