waashk/dblp huggingface dataset:
proposal of the architecture of a qos assured network by cooperating between ip flow control and mpls diffserv-te. this paper proposes a network architecture to achieve a qos assured network, which is composed of two qos control technologies such as ip flow control and mpls diffserv-te. ip flow control technology is utilized to treat ip packets as an ip flow distinguished by source and destination ip addresses, ports, protocol and priority and to apply the cac function on the per-flow basis. mpls diffserv-te is also used to accommodate multiple ip flows along the lsp via a bandwidth guarantee with certain service classes. by using the network testbed, we confirmed some of functions in our proposed architecture of the qos assured network worked properly following the cac capability of flow state routing and lsp-based bandwidth guarantee of mpls diffserv-te. multiple ip flows can be appropriately conveyed over the assigned lsp. moreover, we verified the operation of the prototype nms to monitor ip flows, lsps and the inclusion relationship between them. and we also derived a policy to set the bandwidth for cac at the edge router for effective utilization of bandwidth.
channel-assignment and scheduling in wireless mesh networks considering switching overhead. this paper considers the channel-assignment and scheduling in wireless mesh networks that employ multiple radios and multiple channels. in contrast to the various algorithms available in the literature, we explicitly model the delay overhead that is incurred during channel switching, and use that delay in the design of algorithms. we prove that the well known greedy maximal scheduling (gms) algorithm does not have any provable efficiency ratio when the switching overhead is considered. we present a centralized algorithm (cgsso), and a dynamic algorithm (dmsso), both of which consider switching overhead. simulation results show that the proposed algorithms significantly outperform other algorithms in packet throughput and average packet delay metrics. results also show that the improvements in performance become more pronounced as the switching delay increases.
a low ml-decoding complexity, high coding gain, full-rate, full-diversity stbc for 4 × 2 mimo system. this paper proposes a full-rate, full-diversity space-time block code (stbc) with low maximum likelihood (ml) decoding complexity and high coding gain for the 4 transmit antenna, 2 receive antenna (4×2) multiple-input multiple-output (mimo) system that employs 4/16-qam. for such a system, the best code known is the djabba code and recently, biglieri, hong and viterbo have proposed another stbc (bhv code) for 4-qam which has lower ml-decoding complexity than the djabba code but does not have full-diversity like the djabba code. the code proposed in this paper has the same ml-decoding complexity as the bhv code for any square m-qam but has full-diversity for 4- and 16-qam. compared with the djabba code, the proposed code has lower ml-decoding complexity for square m-qam constellation, higher coding gain for 4- and 16-qam, and hence a better codeword error rate (cer) performance. simulation results confirming this are presented.
dynamic resource allocation with limited feedback for ofdm based cooperative networks. we propose a dynamic resource allocation scheme for a wireless cooperative network based on orthogonal frequency division multiplexing (ofdm) modulations with limited feed-back. the amount of the feedback information required from the relay to the source in the proposed scheme is independent of the number of subchannels, which results in a dramatic reduced overhead over conventional resource allocation schemes. furthermore, the transmission durations at the source and the relay are designed to be asymmetric, which enhances the degree of freedom for transmission. simulation results show that the proposed resource allocation scheme achieves a higher system capacity, and has less sensitivity to channel estimation errors than the previously proposed schemes based on subchannel paring and power allocation. it also has a fast convergence speed. an intensive performance analysis is provided for the proposed resource allocation scheme.
probabilistic diagnosis of link loss using end-to-end path measurements and maximum likelihood estimation. internet fault diagnosis has attracted much attention in recent years. in this paper, we focus on the problem of finding the link pass ratios (lprs) when the path pass ratios (pprs) of a set of paths are given. usually, given the pprs of the paths, the lprs of a significant percentage of the links cannot be uniquely determined because the system is under-constrained. we consider the maximum likelihood estimation of the lprs of such links. we prove that the problem of finding the maximum likelihood estimation is np-hard, then propose a simple algorithm based on divide-and-conquer. we first estimate the number of faulty links on a path, then use the global information to assign lprs to the links. we conduct simulations on networks of various sizes and the results show that our algorithm performs very well in terms of identifying faulty links.
energy efficient error correction in mobile tv. the current error correction layer of digital mobile tv is designed for worst case scenarios, which often do not apply. in this paper, we propose a new opportunistic error correction layer based on fountain codes and a resolution adaptive adc, which has been integrated into the ofdm-based physical layer. the key element in the new proposed system is that only packets are processed by the receiver which have encountered high-energy channels. others are discarded. with this new approach, around 84% of the energy consumption in adcs can be saved compared with the conventional mobile tv system under the same channel conditions.
detecting primary user emulation attacks in dynamic spectrum access networks. in this paper, we present an analytical model as well as a practical mechanism to detect denial of service (dos) attacks on secondary users in dynamic spectrum access (dsa) networks. in particular, we analyze primary user emulation attacks (puea) in cognitive radio networks without using any location information and therefore can do away with dedicated sensor networks. we present an analysis using fenton's approximation and wald's sequential probability ratio test (wsprt) to detect puea. simulation results demonstrate that it is possible to keep the probability of success of puea low, while still keeping the probability of missing the return of the primary low as well.
steady-state kalman filtering for channel estimation in ofdm systems utilizing snr. kalman filters are effective channel estimators but they have the drawback of having heavy calculations when filtering needs to be done in each sample. in our paper we obtain the steady-state kalman gain to estimate the channel state thus eliminating a larger portion of the calculation burden. steady-state value is calculated by transforming the vector kalman filtering in to scalar domain by exploiting the filter characteristics when pilot subcarriers are used for channel estimation. kalman filters operate optimally in the steady-state condition. therefore by avoiding the convergence period of the kalman gain, the proposed scheme is able to perform better than the conventional method. also, driving noise variance of the channel is difficult to obtain practical situations and accurate knowledge is important for the proper operation of the kalman filter. thus we extend our scheme to operate in the absence of the knowledge of driving noise variance by utilizing received signal-to-noise ratio (snr). simulation results show considerable estimator performance gain can be obtained compared to the conventional kalman filter.
superior nda ml delay and gain estimators for uwb channels. novel non-data-aided maximum likelihood estimators for the delays and the attenuations in an ultra-wide bandwidth channel are proposed. numerical results show that these new estimators outperform the previous non-data-aided maximum likelihood channel estimators derived in the literature. moreover, in some cases, the performances of the new non-data-aided estimators approach those of the data-aided estimators, enabling us to reduce the overhead expense of pilot symbols.
fsa: a fast coordination scheme for opportunistic routing. opportunistic routing (or) has been considered as one promising technique to overcome the unreliability of the wireless medium by collaborating multiple neighboring receivers/candidates for packet forwarding. a key challenge in or is how to efficiently coordinate the multiple candidates and ensure only one of them to forward the packet. in this paper, we investigate the existing candidate coordination schemes and propose a "fast slotted acknowledgment" (fsa) to further improve the performance of or by using single ack with the help of channel sensing technique. the simulation results show that fsa can reduce the average end-to-end time delay of or protocols by up to 50% compared with state-of-the-art coordination schemes in light traffic scenarios and can increase the average end-to-end throughput by up to 20% in heavy traffic scenarios.
towards secure spectrum decision. the key idea of dynamic spectrum access (dsa) networks is to allow the secondary, unlicensed users to detect and use unused portions of the spectrum (white spaces) opportunistically. the two main constraints in the design of dsa networks is to make sure that this opportunistic access is done without any disruption of service to the primary users and without any modifications to the primaries themselves. most architectures and protocols for dsa networks in the literature assume that all parties are honest and that there are no attackers. recently (ieee icc, cognet 2008) we demonstrated the failure of this approach by showing that an attacker can manipulate messages to convince the parties involved in the protocol to make incorrect spectrum decisions. in this paper, we consider spectrum decision protocols in clustered infrastructure-based dynamic spectrum access networks where the spectrum decision in each cluster is coordinated by some central authority. we propose an efficient and provably secure protocol that can be used to protect the spectrum decision process against a malicious adversary.
opportunities, constraints, and benefits of relaying in the presence of interference. in this paper the interference channel is extended by additional relay nodes in order to investigate the influence of interference on the design and performance of relaying protocols. we introduce a framework in which the relay interference channel is decomposed into a cascade of individual interference channels with finite conference links at the transmitters. each of these stages is able to implement interference cancellation and mitigation schemes such as dirty-paper and han-kobayashi coding. we discuss the dependencies between individual stages and propose specific approaches with reasonable complexity. finally, we compare the performance of these protocols using a simplified model for the channel and network geometry of a mobile communications system. the results show that a reasonable choice is to coordinate the base-station to relay links using distributed dirty-paper coding and to mitigate interference on the relay to user link using han-kobayashi coding.
a user-decided service model and resource management in a cooperative wimax/hsdpa network. employing multiple radio access technologies such as wimax, hsdpa and wi-fi in a mobile network to provide users with more cost-effective communication services has long been a vision of many service network providers. in this paper, we propose a novel user-decided service model for a cooperative wireless network in which the radio resources of multiple wireless networks are collectively managed. under the model, users are provided with multiple service options with different levels of service quality and charges. it is up to users to choose the most suitable service option (and access network) based on their personal preference and the amount of money they are willing to pay. we use a video streaming service in a wimax/hsdpa network as an example to illustrate the key concepts and resource management of our approach. the results of simulation show that, under the model, the service network can accommodate more users and provide higher user satisfaction than the traditional network-decided service model. it can also achieve higher resource utilization and revenues. this demonstrates the importance of defining the concept of user-decided service model in a cooperative heterogeneous networking environment.
system design and resource allocation in 802.16j multi-hop relay systems under the user rate fairness constraint. ieee 802.16j multi-hop relay task standard includes two mutually exclusive options: transparent relay stations (t-rs) and non-transparent relay stations (nt-rs). in this work, a system design approach is proposed to compare different relay systems in term of their capacity with rate fairness constraint among the mobile stations (ms). single-input single-output (siso) and multi-input multi-output (mimo) antenna systems are considered in the links between the base station (bs) and relay stations (rs). 1 and 3 rss per sector are considered. our simulation results show that for any case, the highest capacity is achieved by nt-rs with 3 rss per sector in distributed scheduling mode. in addition, the effect of the ms association rule, which determines the access station (bs or rs) for each ms, is also investigated. two rules: highest mcs scheme with the highest modulation and coding rate, and highest (mod) ese scheme with the highest (modified) effective spectrum efficiency, are studied along with the optimal rule that maximizes system capacity with rate fairness constraint. it is demonstrated that highest (mod) ese scheme performs closely to the optimal rule in term of capacity.
vb-rescheduling: an efficient data channel rescheduling algorithm based on virtual burst for obs networks. in optical burst switching (obs) networks, the data channel scheduling algorithm is one of the most important issues, which have a great impact on network performances. currently, there are various data channel scheduling algorithms. among them, the rescheduling algorithm is more attractive because it could adaptively reallocate the data channels even when they have been occupied by some data bursts (db), and release some channel resource for the latter db in most situations. however when the traffic load is heavy, it is not effective any more, and would worsen network performance. therefore, this paper proposes a new rescheduling algorithm, namely vb-rescheduling algorithm. according to the state of the data channels, it reschedules data blocks on demand by three granularities (i.e., virtual burst, child-burst cluster and normal burst). compared with other rescheduling algorithms, it has some advantages as follows. firstly, it could keep the same sequence of the arriving data bursts at a node as the corresponding control packets. secondly, it is more flexible to reschedule data blocks. finally, simulation results show that it can greatly improve obs network performance in terms of the overall packet loss probability and the link utilization, compared with traditional obs rescheduling algorithm (whose rescheduling granularity is normal burst) and the native virtual burst scheduling scheme.
routing games for traffic engineering. current data network scenario makes traffic engineering (te) a very challenging task. the ever growing access rates and new applications running on end-hosts result in more variable and unpredictable traffic patterns. by providing origin-destination pairs with several possible paths, load-balancing has proved itself an excellent tool to face this uncertainty. in particular, mechanisms where routers greedily minimize a path cost function (thus requiring minimum coordination) have been studied from a game-theoretic perspective in what is known as a routing game (rg). the contribution of this paper is twofold. we first propose a new rg specifically designed for elastic traffic, where we maximize the total utility through load-balancing only. secondly, we consider several important rgs from a te perspective and, using several real topologies and traffic demands, present a thorough comparison of their performance. this paper brings insight into several rgs, which will help one in choosing an adequate dynamic load-balancing mechanism. the comparison shows that the performance gain of the proposed game can be important.
capacity of hierarchical wifi/wimax networks. in this paper, we assess the capacity of hierarchical wifi/wimax networks, where end users are connected to the internet via wifi access points while wimax plays the part of backhaul. at the packet level, we model both wifi and wimax throughputs, taking into account inter-cell interference and radio conditions heterogeneity over the network. at the flow level, we provide a markovian analysis that calculates the performance metrics like the blocking rate and the user-perceived throughput. the interaction between the different cells in the network, at the access and backhaul layers, is solved by a fixed point approach. our numerical results illustrate the capacity of the network and the impact of replacing the wired backhaul by a wimax one.
a service-transparent and self-organized optical network architecture. in this paper, a new service oriented networking paradigm is presented, where network nodes (peers) are self-organized into individual service entities. the key idea relies on the overlay approach, where there exists a virtual service plane, fragmented into self-organized and self-managed entities called islands of service transparency. the islands are formed in an upstream, ad-hoc mode from the non-networking resources (i.e vod, grid server, etc) towards all ingress routers of the network, using link state advertisements and multi-cost path selection algorithms (i.e residual bandwidth, server capacity, storage, etc). organization and re-organization of nodes around nonnetwork resources is transparent to end-users, and thus any request within a specific service island is transparently routed to the island's resource for execution. a service proxy is commissioned to resolve service addresses and service attributes to qos metrics. in this paper, we present the main notations and metrics of the proposed architecture as well as node behavior and potential gmpls extensions for implementation issues.
an insider-resistant group key exchange protocol without signatures. the well-known method for a group key exchange (gke) protocol to be against insider attack is to make use of signatures. however, using signatures considerably degrades the performance of the gke protocol. in this paper, we propose a new method to resist insider attack. the underlying tool of our method is a two-party authenticated key exchange (ake) protocol, which can be used to authenticate all other participants' session identifiers instead of using signatures. based on the two-party ake protocol, we propose an efficient insider-resistant gke protocol without signatures. we show that our proposal is provably secure against insider attack if the underlying two-party ake protocol is secure.
resource management in stargate-based ethernet passive optical networks (sg-epons). at present there is a strong worldwide push towards bringing fiber closer to individual homes and businesses. another evolutionary step is the cost-effective all-optical integration of fiber-based access and metro networks. stargate [1] is an all-optical access-metro architecture which does not rely on costly active devices and makes use of an overlay island of transparency with optical bypassing capabilities. in this paper we propose onu architectures, and discuss several technical challenges, which allow stargate epons (sg-epons) to evolve in a pay-as-you grow manner while providing backward compatibility with legacy infrastructure and protecting previous investment. using a simple bandwidth and wavelength allocation, we study the capacity and delay performance of sg-epon through simulations
arbitrarily tight upper and lower bounds on the gaussian q-function and related functions. we present a new family of tight lower and upper bounds on the gaussian q-function q(x). it is first shown that, for any x, the integrand ϕ(θ x) of the craig representation of q(x) can be partitioned into a pair of complementary convex and concave segments. as a consequence of this property, integrals of ϕ(θ x) over arbitrary intervals within its convex region can be lower-bounded by jensen's inequality and upper-bounded by cotes' quadrature rule, with the opposite occurring for the concave region ϕ(θ x). the combination of these complementary bounds yield a complete family of both lower and upper bounds on q(x), which are expressed in terms of elementary transcendental functions and can be made arbitrarily tight by finer segmentation. a by-product of the method is that various other functions, such as the squared gaussian q-function q2(x), the 2d joint gaussian q-function q(x, y, ρ), and the generalized marcum q-function qm(x, y), can also be both upper and lower bounded with arbitrarily tightness, which to the best of our knowledge finds no precedence in the literature. explicit examples of the latter applications are given.
impact of alliances on end-to-end qos satisfaction in an interdomain network. this paper focuses on qos guarantees in an interdomain selfish network where each domain may sell qos guarantees for its transit traffic. the main objective of the paper is to evaluate the benefit for some of these domains to develop together a privileged partnership in terms of economic alliance. this alliance permits the members to share their local knowledge of the network and to exchange some traffic network services. after defining the alliance model and the way each domain may use it to obtain better qos guarantees, we analyse by simulation on realistic generated topologies the impact of such alliances on the qos requests satisfaction.
linear mmse mimo channel estimation with imperfect channel covariance information. in this paper, we investigate the effects of imperfect knowledge of the channel covariance matrix on the performance of a linear minimum mean-square-error (mmse) estimator for multiple-input multiple-output (mimo) channels. the estimation mean-square-error (mse) is analytically analyzed by providing both a very tight lower bound and an upper bound. the proposed analysis is useful for the understanding of how estimation accuracy of the channel covariance matrix impacts on system performance, depending on the average signal-to-noise ratio (snr) and specific propagation conditions. conclusions are fully supported by numerical results.