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With the development of ubiquitous Internet and user's devices, seamless access property becomes essential in the world today, which motivates the new notion of mobility capability. Several protocols have been designed in order to bring seamless access to users. Several solutions have been proposed, which can be classified as client-based mobility and network-based mobility solutions. Client-based...
This paper proposes and devises a simple and cost-effective native Ethernet-based self-healing WDM-PON access ring architecture for next-generation broadband access. Specifically, this paper proposes and devises simple, efficient, and cost-effective fully distributed fault detection and recovery schemes for the proposed WDM-PON ring architecture. The main characteristics of the proposed architecture...
The following topics are dealt with: communication theory; signal processing; wireless communication system; mobile network; Internet; quality of service; ad hoc network; wireless sensor network; wireless mesh network; optical network; multimedia services; and information system security.
In this paper, we study a cognitive coexistence strategy for heterogeneous networks. While a lot of previous works focused on spectrum underlay approaches for weak interference scenarios, a high power infrastructure (IS) transmitter creates a large dead zone for nearby ad-hoc (AH) links using the same spectrum. To address this problem, we propose to utilize a half-duplex decode-and-forward (DF) relay...
In this paper, we consider the problem of exploiting spectrum resources for a secondary user (SU) of a wireless communication network. We suggest that Upper Confidence Bound (UCB) algorithms could be useful to design decision making strategies for SUs to exploit intelligently the spectrum resources based on their past observations. The algorithms use an index that provides an optimistic estimation...
A hybrid electro-optic router is attractive, where packet buffering and table lookup are carried out in electrical domain and switching is done optically. In this paper, we propose a load-balanced optical switch (LBOS) fabric for a hybrid router. LBOS comprises N linecards connected by an N-wavelength WDM fiber ring. Each linecard i is configured to receive on channel λi. To send a packet, it can...
With the irreversible trend of the convergence and cooperation among heterogeneous wireless networks, the need for network information awareness of user equipments (UEs) becomes increasingly imperative in the Cognitive Wireless Networks (CWN). As one of the candidate solutions for network information delivery for UEs, the Cognitive Pilot Channel (CPC) concept has been brought forward recently, providing...
Security risk management for information technology-based organizations has become increasingly important in recent years. However, the risk assessment and mitigation strategies that these organizations employ have remained relatively ad hoc and qualitative. In this paper, we extend a quantitative framework for risk assessment called Risk-Rank to include risk mitigation through Markov Decision Processes...
Identification and isolation of attackers in a distributed system is a challenging problem. This problem is even more aggravated in a wireless network because the unreliable channel makes the actions of the users (nodes) hidden from each other. Therefore, legitimate users can only construct a belief about a potential attacker through monitoring and observation. In this paper, we use game theory to...
We present a novel BCH code based sequences design method for generating large families of ranging sequences. The sequences can be used in an OFDMA network to offer sufficient ranging opportunities and guarantee low probability of false detection. Each derived sequence has low peak to average power ratio (PAPR) and cross-correlations with other sequences. These properties enable a mobile receiver...
Geographic message forwarding in vehicular ad hoc networks (VANET) has attracted much attention and become one of the most promising research areas recent years. In this paper, inspired with the intuition that drivers' route are with high regularity, we propose a prediction-based message forwarding strategy named Seer. Seer trains a 2nd-order Markov model based on long-term historic trip GPS data...
Two fundamental problems related to multi-carrier modulation are considered in this paper. The first is finding the best modulation schemes in all subcarriers to minimize the total energy consumption required to send a given number of bits between two wireless nodes. The second is finding the best modulation schemes to maximize the number of bits transmitted between two nodes under total energy constraint...
In this paper the performance of coded cooperation has been analyzed for independent flat Nakagami-m fading channels. The outage behavior of the cooperative system has been presented and analyzed with two instantaneous variable (i.e. one with instantaneous Signal to noise ratio (SNR) and other with instantaneous received power). Finally we have presented an analytical approach to calculate the critical...
Voice over Internet (VoIP) has been experiencing enormous growth in recent years. While posed to replace traditional PSTN for both enterprise and residential customers, VoIP has yet to achieve the same level of quality and reliability as PSTN. One key challenge is that a growing segment of customers is increasingly relying on WiFi connections. VoIP over WiFi (VoWiFi) experiences significant degradation...
This paper focuses on the spectrum sensing issues in the unslotted cognitive radio networks with wireless fading channels. To overcome the energy-inefficiency problem of the existing continuous/fixed-schedule spectrum sensing schemes in the cognitive radio networks, we propose an efficient spectrum sensing scheme for secondary users (SUs). The design goal of our proposed scheme is to save the sensing...
This paper investigates the error performance and precoder design for a bandwidth-efficient bit-interleaved coded modulation (BICM) system over a non-orthogonal amplify-and-forward (NAF)half-duplex single-relay channel. A tight union bound on the bit error probability (BEP) is first derived for an arbitrary block length of 2N using a 2N × 2N precoder. This bound provides an useful tool to predict...
Network coding is expected to improve throughput performance of multihop wireless networks. However, the throughput performance is significantly affected by the coding overhead at intermediate nodes. In this paper, we consider the trade-off between the throughput and coding overhead. Focusing on an intermediate node of a three-node chain topology, we model it as a single-server queueing system with...
A Space-Time Turbo Bayesian Compressed Sensing (STTBCS) algorithm is proposed for Ultra-Wideband (UWB) systems in this paper. Based on the sparsity of UWB signals, the STTBCS algorithm provides an efficient approach for integrating spatial and temporal redundancies. A space-time structure is also designed for exploiting and transferring the spatial and temporal \emph{a priori} information for signal...
Recently, many new types of distributed denial of service (DDoS) attacks have emerged, posing a great challenge to intrusion detection systems. In this paper, we introduce a new type of DDoS attacks called stealthy DDoS attacks, which can be launched by sophisticated attackers. Such attacks are different from traditional DDoS attacks in that they cannot be detected by previous detection methods effectively...
Policy Filtering (PF) and Content Filtering (CF) are two important tasks in packet forwarding of today's Internet. It is both technologically and economically important to develop integrated solutions for executing both tasks to reduce cost. In this paper, we propose a distributed Ternary Content Addressable Memory (TCAM) coprocessor architecture to allow fast and integrated PF and CF. Due to significant...
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