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22
Survivable mobile wireless networks: issues, challenges, and research directions
- Proc. ACM workshop on Wireless security
, 2002
"... In this paper we survey issues and challenges in enhancing the survivability of mobile wireless networks, with particular emphasis on military requirements �. Research focus on three key aspects can significantly enhance network survivability: (i) establishing and maintaining survivable topologies t ..."
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Cited by 33 (2 self)
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In this paper we survey issues and challenges in enhancing the survivability of mobile wireless networks, with particular emphasis on military requirements �. Research focus on three key aspects can significantly enhance network survivability: (i) establishing and maintaining survivable topologies that strive to keep the network connected even under attack, (ii) design for endto-end communication in challenging environments in which the path from source to destination is not wholly available at any given instant of time, (iii) the use of technology to enhance survivability such as adaptive networks and satellites.
Next Century Challenges: RadioActive Networks
, 1999
"... A key challenge facing wireless networking is to utilize the spectrum as efficiently as possible given current channel conditions and in the most effective way for each application. This is difficult to achieve with existing wireless devices because physical layer functionality is fixed, while chann ..."
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Cited by 20 (0 self)
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A key challenge facing wireless networking is to utilize the spectrum as efficiently as possible given current channel conditions and in the most effective way for each application. This is difficult to achieve with existing wireless devices because physical layer functionality is fixed, while channel conditions and applications can change rapidly. Instead, we argue that RadioActive networks, an adaptable wireless network architecture which draws on the strengths of software radios and active networks, are needed to meet this challenge. Active networks provide a framework for programming network services, and software radios extend this programmability into the physical layer. We believe that this approach will offer significant improvements in functionality and performance over today's wireless networks because it is no longer necessary to design a priori with pessimistic assumptions that describe worst case conditions. In this paper, we outline our vision, the opportunities it afford...
Non-cooperative Spectrum Access – The Dedicated vs. Free Spectrum Choice
"... We consider a dynamic spectrum access system in which Secondary Users (SUs) choose to either acquire dedicated spectrum or to use spectrum-holes (white spaces) which belong to Primary Users (PUs). The tradeoff incorporated in this decision is between immediate yet costly transmission and free but de ..."
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Cited by 12 (1 self)
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We consider a dynamic spectrum access system in which Secondary Users (SUs) choose to either acquire dedicated spectrum or to use spectrum-holes (white spaces) which belong to Primary Users (PUs). The tradeoff incorporated in this decision is between immediate yet costly transmission and free but delayed transmission (a consequence of both the possible appearance of PUs and sharing the spectrum holes with multiple SUs). We first consider a system with a single PU band, in which the SU decisions are fixed. Employing queueing-theoretic methods, we obtain explicit expressions for the expected delays associated with using the PU band. Based on that, we then consider self-interested SUs and study the interaction between them as a noncooperative game. We prove the existence and uniqueness of a symmetric Nash equilibrium, and characterize the equilibrium behavior explicitly. Using our equilibrium results, we show how to maximize revenue from renting dedicated bands to SUs. Finally, we extend the scope to a scenario with multiple PUs, show that the band-pricing analysis can be applied to some special cases, and provide numerical examples.
Channel fragmentation in dynamic spectrum access systems: A theoretical study
- ACM SIGMETRICS Perf. Eval. review
, 2010
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Smart Delivery of Multimedia Content for Wireless Applications
- the 2nd International Workshop on Mobile and Wireless Communications Networks (MWCN'2000
, 2000
"... Abstract. Packet-oriented access to cellular networks enables us to deliver multimedia content to mobile users. As cellular networks will continue to deliver circuit switched voice for some time to come, care must be taken to avoid interference between these delivery mechanisms, while maximizing the ..."
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Cited by 8 (6 self)
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Abstract. Packet-oriented access to cellular networks enables us to deliver multimedia content to mobile users. As cellular networks will continue to deliver circuit switched voice for some time to come, care must be taken to avoid interference between these delivery mechanisms, while maximizing the range of services and the number of users. Smart delivery of multimedia content involving agents running in the mobile, the base station and the content provider allows us to dynamically adapt the application and network behavior to each other in order to meet the criteria for specific applications. In particular, this paper examines the delivery of streaming media and interactive voice as Voice over IP (VoIP) to mobile users. Our conclusion is that this, in combination with the dynamic adaptive properties as introduced by the agents, enables us to transfer voice entirely IP over wireless links, thereby freeing further resources for the new applications that we refer to in this paper. 1.
Narrowband Channel Extraction For Wideband Receivers
- In ICASSP'99
"... One of the most computationally intensive processing stages of a wideband digital receiver is the extraction of a narrowband channel from a wideband input signal. In implementations that compute the convolutional sum, the computation is proportional to the bandwidth of the input signal. This paper s ..."
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Cited by 6 (1 self)
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One of the most computationally intensive processing stages of a wideband digital receiver is the extraction of a narrowband channel from a wideband input signal. In implementations that compute the convolutional sum, the computation is proportional to the bandwidth of the input signal. This paper shows how to break this dependence, reducing the limiting factor to the requirement to maintain a sufficient output signal-to-noise ratio (SNR). This paper describes two complementary algorithms for efficient channel extraction in wideband receivers. The first allows the required frequency translation to be performed at the lower sample rate of the channel filter output. The second algorithm decouples the effect of interference rejection from SNR improvement and improves the computational efficiency of filtering by using only a subset of the input samples. Additionally, we present a simple model to quantify the effects of this technique and experimental verification using a wideband software ...
VoIP over Wireless for Mobile Multimedia Applications
- Personal Computing and Communication Workshop
, 1999
"... Abstract. Voice over IP (VoIP) exploits the ability of IP to deliver multiple services over a single access link. Increased computing power and available bandwidth in endpoints, reduced cost and size of electronics, as well as sensor and positioning technologies allow us to develop new interactive m ..."
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Cited by 5 (2 self)
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Abstract. Voice over IP (VoIP) exploits the ability of IP to deliver multiple services over a single access link. Increased computing power and available bandwidth in endpoints, reduced cost and size of electronics, as well as sensor and positioning technologies allow us to develop new interactive multimedia applications that are able to adapt to the communication context of the end-user. This is particularly important as wireless access to the Internet and connectivity between mobile artifacts can leverage these possibilities even further to bring us new ways of communication. Our work shows that, with respect to VoIP over wireless networks, bandwidth is not the problem and that QoS can match that of voice in today’s cellular networks. We therefore propose to run IP directly over wireless links to bring multimedia services to mobile users. Even more importantly, this leads to a significant simplification, and consequently a cost reduction, of the wireless infrastructure. 1.
Functional Analysis of a SDR Based Bluetooth/HiperLAN Terminal Demonstrator
, 2001
"... In our Software Defined Radio (SDR) project we aim at combining two di#erent types of standards, Bluetooth and HiperLAN/2 on one common hardware platform. HiperLAN/2 is a high-speed Wireless LAN (WLAN) standard, whereas Bluetooth is a low-cost and low-speed Personal Area Network (PAN) standard. An S ..."
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Cited by 5 (5 self)
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In our Software Defined Radio (SDR) project we aim at combining two di#erent types of standards, Bluetooth and HiperLAN/2 on one common hardware platform. HiperLAN/2 is a high-speed Wireless LAN (WLAN) standard, whereas Bluetooth is a low-cost and low-speed Personal Area Network (PAN) standard. An SDR system is a flexible radio system that is re-programmable and re-configurable by software in order to cope with its multiservice, multi-standard and multi-band environment.
Direct Waveform Synthesis for Software Radios
- in Proceedings of WCNC'99
, 1999
"... This work presents results that show how direct digital synthesis (DDS) techniques can be extended to produce frequency modulated (FM) waveforms as well as many types of digitally modulated waveforms, such as PSK or QAM. We show how digitally modulated waveforms can be efficiently synthesized from t ..."
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Cited by 4 (0 self)
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This work presents results that show how direct digital synthesis (DDS) techniques can be extended to produce frequency modulated (FM) waveforms as well as many types of digitally modulated waveforms, such as PSK or QAM. We show how digitally modulated waveforms can be efficiently synthesized from tables of pre-computed samples. This work also reports on the implementation of these algorithms in a software radio system. I. Introduction The technique of direct digital synthesis (DDS) is gaining popularity as a method of generating sinusoidal signals in digital systems [5]. This technique is especially well suited to software radio systems implemented on architectures which use general purpose processors (GPPs) because these systems often have large amounts of main memory available for storage of pre-computed output samples. These systems can therefore provide great flexibility in the type of waveforms which can be generated. The algorithms developed below show how DDS techniques can b...
