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This work is inspired by the question "Can 100 speakers talk for 30 minutes each in one room within one hour and with zero interference to each other's audience?" posed by Cadambe and Jafar at the 45th Allerton conference 2007. We consider the problem of how many transmitter-receiver pairs can be placed such that each desired link may use half of the channel time free of interference from...
This paper investigates the concept of single frequency satellite networks (SFSNs), whereby multiple satellite beams that have no form of mutual phase coherence are unified through baseband signal processing to achieve uniform coverage across wide areas. We present a realistic application scenario and its link budget analysis, which allows to highlight the advantages with respect to a classic single...
This paper proposes a nonlinear-predictive QoS-promoted dynamic bandwidth allocation (NQ-DBA) scheme for upstream transmission in Ethernet passive optical network (EPON) systems. The proposed NQ-DBA scheme divides incoming packets of voice, video, data service into six priorities, whereas packets having less room before QoS requirements violation will be dynamically promoted to high priority. It predicts...
Uncertain capacity in newly emerged Cognitive Radio Networks(CRN) renders specific performance analysis for the secondary users (SUs), particularly in the aspects of Quality-of-Service (QoS). The effective bandwidth concept is employed to analyze the SUs' performance. Considering the time-varying arrival and service process, we analytically obtain the QoS metrics, such as the approximated delay-violation...
We present a cross-layer approach to the design of a wireless video streaming system, which includes the development of an adaptive radio link buffer and congestion control algorithm and the adoption of the H.264/SVC scalable video format. The proposed system performs a group-of-pictures (GOP) based post-channel adaptation, which does not require the channel status information at the media server...
Self-encoded spread spectrum (SESS) employs non-deterministic spreading codes that have been generated from the random information source and provide unique advantages over traditional pseudo-random codes. In previous work we have shown that the memory in SESS-modulated signals not only can deliver a 3dB gain in AWGN channels, but also can be exploited to achieve time diversity and robust bit-error...
The purpose of this paper is to reduce the complexity of scheduling scheme for OFDMA/SDMA system with multimedia traffic. To achieve this purpose, we propose a low-complexity beamforming-based scheduling (LCBS) scheme to solve the multi-dimensional (space, time, and frequency) radio resource allocation problem in OFDMA/SDMA systems. By utilizing a semi-orthogonal user selection (SUS) algorithm, the...
This paper studies loop-delay compensation as a means to improve the robustness of timing recovery loops in tape storage systems. The delay compensation scheme is derived under fairly general assumptions and is found to match a known Kalman-filtering-based solution if a random-walk model of frequency-offset evolution is assumed. Extensions of the scheme to achieve delay compensation in multichannel...
This paper provides parameter setting and 2-D local stability conditions for TCP/RED networks. In general, a network cannot avoid congestions due to the limit of network capacity. The RED scheme is one of the representative AQM that was proposed to avoid and alleviate network congestions. However, the issue of network stability with many TCP subscribers needs to be considered when setting the RED...
Medium access in ad-hoc wireless networks must be performed in a distributed fashion due to lack of coordination between nodes. Specifically, when nodes are capable of receiving more than one transmission simultaneously, the design of distributed medium-access mechanisms that efficiently exploit the receiver's capability becomes more challenging. Adaptive probabilistic medium access for ad-hoc wireless...
Delay Tolerant Networks (DTNs) are able to provide communication services in challenged networks where the end-to-end path between the source and destination does not exist. In order to increase the probability of delivery, DTN routing mechanisms may require nodes in the network to store and carry messages in their local buffer and replicate many copies. When the limited buffer is consumed, choosing...
In this paper, we propose a distributed contention resolution algorithm for multi-packet reception slotted ALOHA systems, which is based on backlog estimation. In the algorithm, a base station broadcasts a binary-valued collision indicator and the identifications of the packets successfully received, when some of packets simultaneously transmitted collide. Then, mobile terminals (MTs) estimate the...
The paper reports an analysis about the convenience of employing multi-protocol label switching (MPLS) to provide mobility in wireless mesh networks (WMNs). In such networks, which are expected to serve a considerable number of mobile users, the efficient support of mobility is a non-trivial issue. The starting point of our work is proxy mobile IPv6 (PMIPv6), a standardised network-based protocol...
In this paper, we propose an adaptive forwarding scheme for achieving efficient message delivery in the mobile sensor delay-tolerant network (DTN). By adaptively adjusting the probability of replicating a message based on the information about the number of existing message copies in the network, the proposed scheme can achieve nice balance between the delivery delay and the average message copy....
Ergodic capacity is not a suitable information-theoretic measure for delay sensitive applications over fading channels. On the other hand, delay-limited capacity becomes zero for Rayleigh channels. In this case, the Capacity with Probabilistic Delay Constraint becomes useful. In, the maximum constant source rate that may be supported in a wireless system with a probability ?? of exceeding certain...
With demands increasing in lunar and Mars explorations, the need for a new space communication standard protocol is becoming more and more critical. The DTN Research Group (DTNRG) is developing a series of communication protocols with new architecture, generally called DTN protocols, to tolerate highly stressed communication environments with long propagation delays and frequent link disruptions....
The CBC stands for the central-stage buffered Clos-network. This kind of switching fabric was proposed and theoretically evaluated by F. Wang and M. Hamdi. In this paper new packet dispatching schemes for the CBC switches are proposed and evaluated. We study three such schemes, called RGNA (request grant with no association), RGAM (request grant with associated output modules), and RGAP (request grant...
TCP experiences severe performance degradation in cislunar communications because of some assumptions built into its design. Delay/disruption tolerant networking (DTN) is a class of network techniques that is developed to work over Internet protocols to accommodate long link delay and frequent link disruptions in space communication environment. Most of the work concerning DTN protocols and techniques...
This paper deals with the evaluation of the end-to-end packet delay for a lossy network where network coding is adopted to achieve better performance. Differently from previous published papers on this subject, connection oriented services are assumed, this means that packets have to be in-order received and wait at the receiver buffer till all the previous ones have been correctly delivered. The...
With the recent evolution of network-based multiplayer games and the increasing popularity of online games demanding strict real-time interaction among players - like First Person Shooter (FPS) -, game providers face the problem to correlate network conditions with quality of gaming experience. This paper addresses the problem of the estimation gameplay quality during real-time games; in particular,...
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