waashk/dblp huggingface dataset:
iptv quality of service management in home networks. in the progressive development of iptv technology, special attention is being paid at the assurance of an appropriate service quality to the end user. several research and standardization activities are studying how to provide qos for iptv streams along the delivery path from the head end office/video server to the end user. the customer's premise is the last part of this path, and the one that is typically not under control of an operator. at the same time, the home network is becoming a complex environment, including a variety of devices and different network technologies. this paper presents an architecture for iptv quality of service management focused on the home network. a key point of this solution is the introduction of service assurance functions in the home gateway. a prototype of the proposed solution proves the applicability of this approach.
fast distributed multi-cell scheduling with delayed limited-capacity backhaul links. both fast scheduling and spatial signal processing have proven to be capacity-increasing methods in wireless communication systems. however, when applied in the downlink of a cellular network, the combination of both leads to non-stationary intercell interference. if the base stations do not cooperate, either they have to encode the data very conservatively to gain robustness or the non-stationary fluctuations of the interference powers lead to frequent outages, both of which strongly impair the average achievable throughput. on the other hand, base station cooperation increases complexity and delays, contradicting the desire for fast scheduling algorithms. in this paper, we propose a scheme that makes average channel state information available to all base stations via low-rate backhaul communication, whereas high-rate inter-base-station communication is limited to b ⌈log2 k⌉-bit integers, k being the number of users in each of the b cells. simulations show that for slow fading channels, the proposed algorithm preserves most of the per cell sum-rate of other beamforming and dirty-paper coding approaches that have unlimited-capacity backhaul links. furthermore, when out-of-cell information is outdated the proposed algorithm even outperforms those.
centralized and distributed power allocation in multi-user wireless relay networks. optimal power allocation for multi-user amplify-and-forward wireless relay networks in which multiple source-destination pairs are assisted by a set of relays is investigated. two relay power allocation strategies based on maximization of either i) the minimum rate among all users or ii) the weighted sum of rates are developed. a distributed implementation of the maximum weighted-sum-rate power allocation strategy is also studied. numerical results demonstrate the efficiency of the proposed strategies and reveal their interesting throughput-fairness tradeoff in resource allocation.
random access protocols for wlans based on mechanism design. in wireless local area networks (wlans), quality of service (qos) can be provided by mapping applications with different requirements (e.g., delay and throughput) into one of the available access categories (acs), as is done in the ieee 802.11e standard. with the increasing programmability of network adapters, a malicious user can strategically declare a higher ac for its application to gain an unfair share of resources. this can drastically degrade the network performance and avoid adequate service distinction among different acs. in this paper, we use the technique of mechanism design in game theory to tackle this problem in wlans with random access. we propose to use the vickrey-clarke-groves (vcg) mechanism in order to motivate each station to inform the access point (ap) truthfully, about the required ac of its application. the ap will then inform each station about its persistent probability and the price it needs to pay for the offered service. the result of the allocation of the persistent probabilities can be used for admission control. simulation results show that the use of mechanism design can lead to a higher aggregate utility and prevents malicious users from gaining an unfair share of the network bandwidth.
analysis of probabilistic flooding: how do we choose the right coin? this paper studies probabilistic information dissemination in random networks. consider the following scenario: a node intends to deliver a message to all other nodes in the network ("flooding"). it first transmits the message to all its neighboring nodes. each node forwards a received message with some network-wide probability pf. a natural question arises: which forwarding probability pf should each node use such that a flooded message is obtained by all nodes with high probability? in other words, what is the minimum pf to achieve a high global outreach probability? we first present a generic approach to estimate the probability for achieving global outreach. this approach is then employed in erdös rényi random graphs, where we derive an upper and a lower bound for the global outreach probability for given random network and flooding parameters. the analysis is complemented with simulation results showing the tightness of both bounds. as a final result, we take a system design perspective to show a number of parameter vectors leading to global outreach.
controller design for rate assignment in wireless networks. in this paper, data-rate assignment in is-856 uplink (reverse link) is studied. the problem is first formulated in an interference model framework, and then a dynamic control strategy is developed for efficient rate assignment. in the first step, the controller is designed for the special case when the number of users in the network is fixed. then, the minimum time required for a dynamic network (where the number of users is subject to change) to achieve a desired performance is obtained. the simulation results are presented to elucidate the effectiveness of the proposed approach.
protecting location privacy in large-scale wireless sensor networks. in a wireless sensor network, an adversary equipped monitoring antenna can easily overhear packets, which may facilitate identifying the directions of packet flows and trace to the sink or source nodes. in order to defend the location privacy of the sink and source nodes, we propose a location privacy support scheme (lpss). we prove that, with the increase in distance between sink and source node, the protection strength of the lpss increases exponentially. theoretical and simulation results show that lpss can provide strong location privacy protection for both the sink and source nodes under different attacks. under the similar delivery delay (or energy consumption), the safe time provided by lpss is much longer than other approaches. facilitated by the study on lpss, we further investigate that the correlation between sink and source nodes. we find that if one source node is exposed to a sophisticated adversary, conventional fake packet injection mechanisms for protecting sink node tend to be useless.
3g/hspa performance in live networks from the end user perspective. operators around the world are improving their 3g/umts networks by introducing hspa (high speed packet access) that includes both, enhanced uplink and downlink. the hspa is expected to finally provide the mobile broadband access that is able to compete with the fixed connections in performance regarding popular applications such as web browsing, voip, and video. however, it has remained unclear how well the live networks fulfill the promises of performance. we contribute in filling this void by providing measurements in live 3g/hspa networks. we compare tcp and udp goodput performance in basic wcdma, hsdpa-only, and hspa. moreover, one-way delay and jitter measurement results are presented in a stationary as well as in a mobile scenario. the results show that the enhanced network outperforms clearly its predecessor by offering considerably higher data rates, lower delay, and lower jitter. also, because of the harq (hybrid automatic repeat request), there are notably less delay spikes observed with hspa than with wcdma. however, the drive tests show that handovers result in high jitter and interruptions to the communications, which causes, e.g., decreased voip call quality. the uplink enhancement (hsupa) improves the tcp performance beyond the hsdpa-only access, but it is still behind that of the fixed connections. in addition, the properties of the channel allocation mechanism still considerably deteriorate the data rates seen by the user. nevertheless, the hspa is an enabler for true mobile broadband internet access.
downlink scheduling for qos-guaranteed services in multi-user mimo systems with limited feedback. significant throughput gains and system fairness can be obtained by employing scheduling schemes based on precoding techniques. however, qos guarantee requirements are seldom taken into account. in this paper, we propose a downlink scheduling algorithm for qos-guaranteed services in multi-user multiple-input multiple-output (mimo) systems with limited feedback. the proposed algorithm combines stream selection with multi-user packet scheduling. to maximize the overall capacity and reduce co-channel interference, streams are selected in accordance with precoding matrices. in multi-user packet scheduling, the base station first determines the sdma region size for the primary streams. in addition, packet scheduling for the secondary streams is performed to completely exploit spatial multiplexing gains. numerical results show that, at the cost of slightly lower system fairness, the proposed algorithm can achieve higher spectrum efficiency, and have a noticeable improvement in guaranteeing qos requirements in terms of data rates and delay.
sleeping schedule-aware minimum latency broadcast in wireless ad hoc networks. broadcast is a fundamental operation of wireless ad hoc networks (wanet) and has been widely studied in the last decade. however, very few existing broadcasting strategies has considered the scenarios with sleeping schedule, which is a prevalent power-saving method in wireless networks. in this paper we study the sleeping schedule-aware minimum latency broadcast (mlb-sa) problem in wanets and prove its np-hardness. by constructing a shortest path tree (spt) defined with the latency function on the network, we derive a lower bound on the broadcast latency theoretically. following the top-down layered approach and using the d2-coloring solution, we proposed two progressively improved algorithms: the simple layered coloring algorithm (slac) and the enhanced layered coloring algorithm (elac) for the mlb-sa problem. the slac has an approximation ratio of o(δ2 + 1) where δ is maximum degree of the network, while the elac has constant approximation ratio of 24|t|+1 where |t| is the number of time-slotsin a scheduling period. the two algorithms have o(n2) and o(n3) time complexities respectively. the performance of the proposed algorithms are evaluated by simulations.
performance analysis of trust-based node evaluation schemes in wireless and mobile ad hoc networks. as the use of mobile ad hoc networks spreads beyond personal networks to practical military and commercial applications, addressing security issues becomes extremely important in this area. however, mobile networks are more susceptible to malicious behavior; thus, an effective node evaluation mechanism can prevent malicious nodes from initiating attacks and tampering the data communications process in these networks. in this article, we formalize the node evaluation problem, discuss its challenges, and present possible solutions. moreover, we propose a novel node evaluation solution with the assistance of trustworthy neighboring nodes, which allows a mobile node to more effectively evaluate its neighbors based on the additional trust information from selected neighboring nodes. our schemes can thus enhance the security of a network and improve the effectiveness of node evaluation. finally, we evaluate our node evaluation strategies and analyze their advantages when compared to existing node evaluation mechanisms used in wireless communications.
rate and end-to-end delay control for multicast and unicast flows. there is growing evidence that a new generation of potentially high-revenue applications are emerging that can benefit from widespread multicast support in large ip networks. these applications, such as streaming video and interactive games, have inherent quality of service (qos) requirements. current methods of qos provisioning have either scalability concerns or cannot guarantee end-to-end delay with acceptable packet loss unless bandwidth is over-provisioned. while low jitter guarantee is sufficient for streaming applications, maximum end-to-end delay is also required for interactive games. previously, we presented a new holistic architecture for end-to-end qos guarantee for unicast flows only in the core network based on several novel combined rate and end-to-end delay control algorithms. we also demonstrated the viability of this architecture and its advantage over differentiated services by implementing it in edge and core routers and monitoring the rate, end-to-end delay and packet loss of all flows in a six-node core network with long delay links. here, we extend the architecture to include multicast flows and demonstrate that network operators can tune the architectural configuration parameters so as to fairly share the excess bandwidth between multicast and unicast flows.
ergodic secrecy capacity region of the fading broadcast channel. we consider the fading broadcast channel from a secrecy point of view. in this channel, each user views the other user as an eavesdropper, and wants to keep its information as secret from the other user as possible. first, we consider a more general channel model which consists of l independent sub-channels, where in each sub-channel, one of the users' channel is less noisy with respect to the other user. since the user which has the less noisy observation can be different in each sub-channel, the overall channel is not less noisy for any one of the users. we establish the secrecy capacity region of this channel for the case where the transmitter sends a common message to both users and an individual confidential message to each user. this channel model encompasses the sub-class of channels, where in each sub-channel, one of the users' observation is degraded with respect to the other user. the parallel gaussian broadcast channel belongs to this sub-class. in the gaussian case, we identify the optimum input distribution, which is gaussian, and the optimum power allocation corresponding to each point on the boundary of the secrecy capacity region. finally, noting that the fading gaussian broadcast channel is equivalent to a parallel gaussian broadcast channel from an ergodic capacity perspective, we explicitly evaluate the ergodic secrecy capacity region of the fading broadcast channel.
performance analysis of the signal-to-noise ratio assisted crosstalk channel estimation for dsl systems. in this paper we investigate the tracking performance of the downstream (ds) crosstalk (xt) channel estimation based on the reported signal to noise ratio (snr), in particular for digital subscriber line (dsl) systems. aiming to its simplicity, the snr-assisted xt estimation, has been recognized in itu as a backward compatible method that does not require any change in the very high speed digital subscriber line 2 (vdsl2) standard. this low complex algorithm can be used for xt channel estimation in dynamic spectrum management (dsm) techniques today. the algorithm as proposed recently, relies on sending perturbing signals on the victim lines (vls) and reporting the snrs by those lines to acquire the crosstalk channel from some disturber line (dl) to the vls. we generalize this concept to include full startup, tracking and joining scenarios as well as the impact of different perturbation signal choices. simulation results reveal that starting from no crosstalk precompensation, and updating a precoder matrix based on the ds crosstalk channel estimates, the far-end crosstalk (fext) free snr can be reached in few iterations (36 snr measurements for the four lines case).
lightpath establishment in wdm networks with best effort shared path protection in impaired-transmissions. in wavelength division multiplexing (wdm) networks, failures can imply in great loss of data due to high transmission rates, leading to the need of employment of protection mechanisms. transparency and switching in all-optical networks causes physical impairments, which can significantly degrade the signal quality. if the signal quality in a path is below acceptable values, this path cannot be used by incoming requests for lighpath establishment. therefore, quality needs to be checked by the routing and wavelength assignment algorithm. this paper introduces two novel algorithms for shared path protection in wdm networks that take into account the pmd, ase and homowavelength crosstalk physical impairments in path selection. the efficacy of these algorithms are compared to those of their impairment unaware counterpart.
beamforming in dual-hop fixed gain relaying systems. the performance of beamforming in dual-hop co-operative networks with fixed-gain relays is investigated. these kinds of relays offer low complexity and ease of deployment when compared with variable-gain relays. in our analysis, the source and destination nodes are equipped with multiple antennas, whereas the relay is assumed to be a single-antenna device. closed-form expressions for the outage probability (op), probability density function (pdf), moment generating function (mgf), and generalized moments of the end-to-end signal-to-noise ratio (snr) are obtained. it is shown that when the same antenna configurations are considered at the source and destination sides, the power imbalance between the hops may be either beneficial or detrimental for the overall system performance. in addition, depending on whether the average snr of the second hop is equal, lower, or higher than that of the first hop, an increase of the number of antennas may not necessarily result in a substantial improvement in performance.
practical scalability of wavelength routing switches. packet switches with optical fabrics can potentially scale to higher capacities. it is also potentially possible to improve their reliability, and reduce both their footprint and power consumption. a well-known alternative for implementing hardwired switches is arrayed waveguide grating (awg). ideally, awg insertion losses do not depend on the number of input-output ports, meaning that scalability is theoretically infinite. however, accurate second-order assessment has demonstrated that in-band crosstalk exponentially increases the power penalty, limiting the realistic useful size of awg commercial devices to about 10-15 ports (13-18 db) [1]. on the other hand, the in-band crosstalk at awg outputs depends on the connection pattern set by the scheduling algorithm and this port count limitation is calculated for worst-case scenarios. in this paper, we show that distributed schedulers with predetermined connection patterns can be used to avoid these harmful arrangements. we also show that the probability of worst-case patterns is very low, allowing us to set a more realistic port limit for general centralized schedulers and very small losses. with these results, we calculate more realistic port count limits for both scheduler types.
low complexity decision directed channel tracking for high mobility ofdm systems. pilot assisted channel tracking (pact) has been very popular for channel estimation in ofdm systems. however, as the mobility in the system increases and one has to maintain a high accuracy in channel estimation, the pilot overhead typically has to be increased. emerging cellular ofdm standards are expected to use about 6 - 12% pilot overhead per stream, and any possible reduction in pilot overhead would be useful. decision directed channel tracking (ddct) can help reduce pilot overhead, but is known to suffer from error propagation at high fade rates. in emerging broadband wireless systems promising peak bit rates of 50 mbps or more, saving on pilot overhead by using ddct schemes would be highly attractive provided: (a) such a ddct approach does not suffer from error propagation and has an error rate performance comparable to (or better than) pact schemes even at high fade rates; (b) the computational complexity of such a ddct approach is not significantly more than that of the mmse based pact scheme. in this work, we propose a low complexity ddct method which exploits the structure of the regression matrix in conjunction with robust statistics to mitigate the effect of error propagation. it has a much lower computational complexity and a better error rate performance than the decision directed em-kalman and other existing robust statistics based ddct schemes. the proposed method also outperforms a 12.5% pilot overhead based pact scheme with only a modest increase in computational complexity.
chip-level modulated bppm fiber-optic code division multiple access. chip-level modulated binary pulse position modulation (clm-bppm) is proposed as a modulation scheme for fiber-optic code division multiple access (fo-cdma) systems using optical orthogonal code (ooc) for time domain signal spreading. the proposed scheme provides better synchronization and source activity detection at the receiver side as compared to on-off keying (ook). a mathematical expression is derived for the ber of clm-bppm using a combinatorial interference pattern analysis approach. the mathematical model is verified using simulation. numerical results demonstrate that clmbppm has a ber that is very close to ook. moreover, increasing the average source activity causes the performance of the clmbppm to approach that of the ook system with an asymptotic ber equal to the ber of ook at full user activity.
efficient implementation of binary sequence generator for wimax and wran on programmable digital signal processor. in this paper, an efficient design for implementing binary sequence generator on 32-bit instruction execution mode ti tms320c6416 dsp is presented. the main goal is to achieve high-speed channel coding sequence generator that can support ieee802.16 wimax and ieee 802.22 wireless regional area network (wran). the paper focuses on exploiting the binary property of data value and the finite bit-string organization of data on the dsp systems. the impact on parametric variables of the sequence generator on the computational clock-cycles is analyzed. computational results of sequence generation on ti 'c64x dsp show that the proposed design achieves significant speed improvement over the conventional sequential implementation. with this improvement, more functionalities can be included in a single dsp or lower power consumptions can be expected.
on the optimal transmission for the mimo bidirectional broadcast channel. in this work the transmit covariance matrix optimization problem for the mimo gaussian bidirectional broadcast channel is studied. a half-duplex relay node establishes bidirectional communication between two nodes using a decode-and-forward protocol. in the initial multiple access phase both nodes transmit their messages to the relay node. in the succeeding phase the relay broadcasts an optimal re-encoded message so that both nodes can decode the other's message using their own message as side information. we show that if the channels are orthogonal then there exist equivalent transmit strategies with different ranks. the study of special cases reveals some of the difficult structure of the optimal solution. in particular a closed form procedure for the case of full rank transmission for invertible channels is derived. moreover, for parallel channels the optimal solution is completely characterized and discussed.